Dissertations / Theses on the topic 'Metabolismo bioenergetico'

Molte cellule tumorali, al fine di generare ATP e sostenere i processi anabolici, si servono principalmente della glicolisi piuttosto che della respirazione mitocondriale. Di conseguenza, il glucosio assume un ruolo critico per la sopravvivenza e la proliferazione delle cellule tumorali. Inoltre, attraverso la via dei pentosi fosfati, il glucosio porta alla formazione di NADPH, contribuendo al mantenimento nelle cellule dell’equilibrio ossidativo. Nondimeno, il glucosio può entrare anche nel pathway biosintetico delle esosammine (HBP), sostenendo la N- e O-glicosilazione di lipidi e proteine, importante per lo sviluppo tumorale. Considerando l’essenziale ruolo del glucosio, un possibile approccio per la terapia antitumorale è l’utilizzo del metabolismo del glucosio come target, non solo attraverso la glicolisi ma sfruttando anche gli altri processi glucosio-dipendenti. A tal proposito, la deprivazione di glucosio e la seguente analisi del destino cellulare a livello fenotipico e molecolare possono costituire una strategia utile per smascherare tutti i meccanismi mediati dal glucosio che partecipano alla crescita e alla sopravvivenza delle cellule tumorali. Tale strategia potrebbe essere poi sfruttata per offrire nuovi target e progettare nuove terapie antitumorali. Sebbene alcuni dati indichino che i tumori originino da cellule con persistenti difetti alla catena respiratoria mitocondriale, l’inibizione della fosforilazione ossidativa (OXPHOS) sembra una condizione di adattamento più che una causa della riprogrammazione metabolica delle cellule tumorali. In questo scenario, i meccanismi di regolazione post-traduzionali, di natura essenzialmente reversibile, a carico di proteine mitocondriali potrebbero assumere un importante ruolo regolatorio. Una delle principali modificazioni post-traduzionali è la fosforilazione dei residui Ser/Thr e, a tal proposito, la chinasi PKA presenta numerosi target a livello mitocondriale ed è coinvolta nella regolazione di biogenesi, trasporto e attività dei Complessi I e IV e della morfologia mitocondriale. Poiché è stato osservato che K-ras può causare la diminuzione dell’espressione di geni codificanti per componenti della via cAMP/PKA, nelle cellule K-ras-trasformate la deregolazione di tale via potrebbe portare alla disfunzione mitocondriale ed allo switch metabolico caratteristico delle cellule tumorali. A conferma di questa ipotesi, le cellule K-ras-trasformate mostrano minori livelli di attività dell’enzima PKA rispetto alle cellule normali. Inoltre, la stimolazione esogena della attività della PKA, ottenuta mediante trattamento con forskolina (FSK), protegge le cellule K-ras-trasformate, sia murine sia umane, dalla morte indotta dalla deplezione di glucosio. Tale protezione è dovuta alla stimolazione dell’attività del Complesso I, all’aumento dell’ATP intracellulare e della fusione mitocondriale e alla riduzione dei livelli di ROS. L’inibizione specifica di PKA previene quasi completamente molti di questi effetti. Inoltre, il breve trattamento con Mdivi-1, molecola in grado di favorire la fusione mitocondriale, riduce fortemente i livelli di ROS specialmente nelle cellule trasformate, indicando una stretta relazione tra morfologia e attività mitocondriale. Queste osservazioni supportano l’idea che l’apoptosi indotta dalla deprivazione di glucosio nelle cellule K-ras-trasformate è associata alla deregolazione della via cAMP/PKA che a sua volta causa la diminuzione dell’attività del Complesso I, la riduzione della produzione di ATP e la prevalenza della fissione mitocondriale rispetto alla fusione. Tale scoperta può aprire nuovi scenari per lo sviluppo di farmaci antitumorali. Poiché la carenza di glucosio si può riscontrare nell’ambiente in cui cresce e si sviluppa il tumore, tale condizione può essere sfruttata per potenziare l’azione di specifici agenti, come alcuni modulatori dell’OXPHOS. Infatti, l’inibizione delle funzioni mitocondriali in condizioni di deprivazione di glucosio potrebbe risultare letale per le cellule tumorali. In accordo, in questo lavoro viene mostrato che la deprivazione di glucosio e gli inibitori del Complesso I, come rotenone, piericidina A e capsaicina, hanno un effetto sinergico nell’indurre la morte delle cellule tumorali. Nello specifico, basse dosi d’inibitori del Complesso I, inefficaci sulle cellule normali e su cellule cresciute in alto glucosio, diventano citotossiche per le cellule tumorali cresciute in basso glucosio. L’effetto citotossico degli inibitori del Complesso I sulle cellule tumorali è ulteriormente e fortemente aumentato quando l’attività OXPHOS viene stimolata tramite il trattamento con FSK. Queste osservazioni dimostrano che la riattivazione della funzione mitocondriale associata alla deplezione di glucosio e al trattamento con basse dosi di inibitori del Complesso I riduce fortemente la sopravvivenza delle cellule tumorali e potrebbe quindi essere valutato come approccio terapeutico. Come indicato in precedenza, nelle cellule tumorali il glucosio è implicato in numerosi processi. L’analisi trascrittomica e proteomica di cellule murine K-ras-trasformate e della loro controparte normale mostra che la deprivazione di glucosio modula l’espressione di molti geni legati allo stress del reticolo endoplasmatico e all’Unfolded Protein Response (UPR). L’attivazione di tale risposta si osserva in entrambe le linee cellulari ma più fortemente nelle cellule trasformate, dove è associata anche alla morte cellulare. Infatti, la sua attenuazione tramite l’inibitore della traduzione proteica, cicloesimide, o lo chaperone chimico, 4-fenil-butirrato, protegge specificatamente le cellule trasformate dalla morte cellulare in basso glucosio. Anche l’inibizione della chinasi proapoptotica JNK, attivata a valle dell’UPR, previene specificatamente la morte delle cellule trasformate. Questa osservazione è in accordo col fatto che in basso glucosio le cellule trasformate mostrano una maggiore attivazione di JNK rispetto alle cellule normali. Inoltre, l’attivazione dell’UPR e la morte glucosio-dipendente delle cellule trasformate è completamente prevenuta dall’aggiunta nel terreno di coltura di un substrato dell’HBP, N-Acetyl-D-glucosammina, cosa che suggerisce una stretta relazione tra i due processi. È interessante notare che anche cellule umane esprimenti l’oncogene K-ras e caratterizzate da un fenotipo iperglicolitico mostrano simili effetti in seguito alla modulazione dell’UPR o dell’HBP. Quindi, la deprivazione di glucosio nelle cellule K-ras-trasformate può indurre un meccanismo di morte cellulare UPR-dipendente, attivato dall’eccessivo accumulo di proteine mal foldate, probabilmente come conseguenza della riduzione della N-glicosilazione delle proteine. La piena delucidazione di questa risposta potrebbe essere importante per progettare nuove strategie terapeutiche antitumorali. Oggi la nuova sfida della ricerca e della terapia antitumorale è il totale sradicamento del tumore, uccidendo anche le cellule staminali tumorali (cancer stem cells, CSCs). Considerando l’importante ruolo del metabolismo e della sua riprogrammazione nello sviluppo tumorale, la caratterizzazione del metabolismo delle CSCs può essere considerata un importante mezzo per lo sviluppo di nuove strategie antitumorali. Recentemente, è stata ottenuta la linea cellulare staminale di osteosarcoma umano, 3AB-OS. In questo lavoro di tesi ho svolto una prima caratterizzazione del suo profilo metabolico, paragonato a quello delle cellule tumorali MG63, da cui le cellule 3AB-OS sono state selezionate. Si è osservato che le cellule 3AB-OS dipendono più fortemente dalla glicolisi rispetto alle cellule MG63. Infatti, quando cresciute in presenza di galattosio e piruvato (substrati mitocondriali) le cellule 3AB-OS riducono maggiormente la propria capacità proliferativa rispetto alle cellule MG63. Esse risultano anche essere fortemente sensibili alla deprivazione di glucosio e al trattamento con inibitori della glicolisi mentre sono insensibili all’inibizione della catena respiratoria. Inoltre, diversamente dalle cellule MG63, le cellule 3AB-OS presentano principalmente mitocondri frammentati, in particolare in basso glucosio. Tutte queste osservazioni suggeriscono che il metabolismo energetico delle cellule 3AB-OS presenti caratteristiche paragonabili a quello delle cellule staminali normali e delle cellule tumorali caratterizzate da un metabolismo glicolitico. Può essere interessante notare che il profilo trascrizionale delle cellule 3AB-OS è simile a quello delle cellule K-ras-trasformate, confermando la similitudine tra le CSCs e le cellule tumorali glicolitiche. Quindi, alcune strategie sviluppate per il trattamento delle cellule tumorali glucosio-dipendenti potrebbero essere usate anche per trattare specifiche CSCs.
Several cancer cells, in order to generate ATP and sustain different anabolic processes, rely mainly on glycolysis instead of Oxidative Phosphorylation (OXPHOS). Thus, glucose assumes a critical role for cancer cell survival and proliferation. Moreover, through the penthose phospate pathway glucose leads to production of NADPH contributing to maintenance of cellular oxidative equilibrium. Besides, glucose can also enter Hexosamine Biosynthesis Pathway (HBP), sustaining lipid and protein N- and O-glycosylation that cover an important role in cancer development. Taking in consideration the essential role of glucose in cancer, one important anticancer therapeutic approach is to target its metabolism namely glycolysis and the other processes in which it is involved. On this regard, glucose deprivation and consequent analysis of cancer cell fate both at phenotypical and molecular level can be a useful strategy to unmask all mechanisms that participate to glucose-mediated cancer cell growth and survival. Such a strategy could be subsequently exploited to provide new targets and to set new anticancer therapies. Although there is evidence that tumors originate from cells with persistent defects in the mitochondrial respiratory system, inhibition of OXPHOS activity seems to be an adaptation to cancer metabolism reprogramming rather than a cause. In this scenario, reversible post-translational modifications of mitochondrial components could assume an important regulatory role. Among the most important post-translational modifications there is Ser/Thr phosphorylation and, on this regard, the protein kinase PKA has numerous mitochondrial targets being involved in the regulation of the biogenesis, the import and the activity of mitochondrial Complex I or IV as well as of mitochondrial morphology. Since it has been observed that oncogenic K-ras may lead to a depression of genes encoding for components of the cAMP/PKA signaling pathway, in K-ras-transformed cells the deregulation of cAMP/PKA pathway could cause OXPHOS depression and “glucose addiction” of cancer cells. In agreement with such a hypothesis, K-ras-transformed cells show lower PKA activity as compared to normal cells. Moreover, exogenous stimulation of PKA activity, achieved by Forskolin (FSK) treatment, protects mouse and human K-ras-transformed cells from apoptosis induced by glucose deprivation, by enhancing Complex I activity, intracellular ATP levels and mitochondrial fusion and by decreasing intracellular ROS levels. Worth noting, several of these effects are almost completely prevented by inhibition of PKA activity. Moreover, short time treatment with Mdivi-1, a molecule that favors mitochondrial fusion, strongly decreases the cellular ROS levels especially in transformed cells, indicating a close relationship between mitochondrial morphology and activity. These findings support the notion that glucose shortage-induced apoptosis, specific of K-ras-transformed cells, is associated to a derangement of PKA signaling that leads to mitochondrial Complex I decrease, reduction of ATP formation and prevalence of mitochondrial fission over fusion. Such a discovery can thereby open new approaches for the development of anticancer drugs. Given that glucose shortage is often encountered in the tumor microenvironment, it can be exploited to potentiate the action of specific agents, such as the mitochondrial OXPHOS activity modulators, that in condition of glucose deprivation could be lethal for cancer cells. Accordingly, it is shown that glucose deprivation and Complex I inhibitors, i.e., rotenone, piericidin A and capsaicin, synergize in inducing cancer cell death. In particular, low doses of Complex I inhibitors, ineffective on normal cells and on cells grown in high glucose, become specifically cytotoxic on cancer cells cultured in low glucose. Importantly, the cytotoxic effect of Complex I inhibitors is strongly enhanced when mitochondrial OXPHOS activity is stimulated by FSK. These findings demonstrate that the reactivation of the mitochondrial function associated with glucose depletion and low doses of mitochondrial Complex I inhibitors strongly affect cancer cell survival. This therapeutic approach might be valuable to eradicate cancer cells. As above indicated, glucose is implicated in numerous processes in cancer cells. Transcriptomic and proteomic analyses applied to mouse K-ras-transformed cells as compared to normal cells show that glucose deprivation modulates the expression of several genes linked to endoplasmic reticulum stress and the Unfolded Protein Response (UPR). The activation of such a response, as confirmed by mRNA and protein expression, is observed in both cell lines, but only in transformed cells is strictly associated to their death. In fact, its attenuation by protein translation inhibitor cycloheximide or chemical chaperone 4-Phenyl-butyrate specifically rescues transformed cells from death. Moreover, glucose deprivation-induced transformed cell death is also prevented by inhibition of an UPR downstream pro-apoptotic kinase, JNK, whose activation is observed specifically in transformed cells as compared to normal cells. Interestingly, UPR activation and death of transformed cells is completely prevented by addition of a specific HBP substrate, namely N-Acetyl-D-glucosamine, suggesting a strict relation between the two processes. Notably, also oncogenic K-ras expressing human glycolytic cells show similar effects after UPR modulating treatments. Thus, we show that glucose deprivation can induce an UPR-dependent transformed cell death mechanism, which is activated by harmful accumulation of unfolded proteins, probably as consequence of N-glycosylation protein reduction. The full elucidation of this response could be relevant to design new therapeutic strategies. Today the new challenge of anticancer research and therapy is the total eradication of the cancer, targeting cancer stem cells (CSCs). Considering the important role of metabolism and metabolic reprogramming in cancer development, also the definition of CSCs metabolism can be considered an important tool for future strategies targeting these cells. Recently, a human osteosarcoma 3AB-OS CSC-like line has been developed. Therefore we have decided to characterize its metabolic features as compared to the parental osteosarcoma MG63 cells, from which 3AB-OS cells were previously selected. 3AB-OS cells depend on glycolytic metabolism more strongly than MG63 cells. Indeed, addition to the growth medium of galactose and pyruvate -mitochondrial specific substrates- instead of glucose markedly reduces 3AB-OS growth, as compared to MG63 cells. In line with these findings 3AB-OS cells, compared to MG63 cells, are strongly sensitive to glucose depletion, glycolysis inhibition and less sensitive to respiratory inhibitors. Additionally, in contrast to MG63 cells, 3AB-OS display mainly fragmented mitochondria, particularly in low glucose. Overall, these findings suggest that 3AB-OS energy metabolism is more similar either to normal stem cells or to cancer cells characterized by a glycolytic metabolism. Interestingly, the transcriptional profile of CSCs is similar to that of K-ras-transformed cells, confirming a possible similarity to glycolytic cancer cells. Therefore, some strategies developed for glucose addicted cancer cells could be used also to treat specific CSCs.

Submitted by PAULO FRANCISCO VEIGA BIZERRA null (paulo_veiga22@hotmail.com) on 2018-03-10T16:15:00Z No. of bitstreams: 1 003-2018-Paulo Francisco Veiga Bizerra2.pdf: 2018178 bytes, checksum: a64e6835d0947709c560109bd815c3e7 (MD5)
Approved for entry into archive by Fabio Sampaio Rosas null (fabio@dracena.unesp.br) on 2018-03-14T11:58:06Z (GMT) No. of bitstreams: 1 bizerra_pfv_me_dra.pdf: 2018178 bytes, checksum: a64e6835d0947709c560109bd815c3e7 (MD5)
Made available in DSpace on 2018-03-14T11:58:06Z (GMT). No. of bitstreams: 1 bizerra_pfv_me_dra.pdf: 2018178 bytes, checksum: a64e6835d0947709c560109bd815c3e7 (MD5) Previous issue date: 2018-02-16
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
O imidacloprido (IMD) é um inseticida neonicotinóide largamente utilizado em diversas culturas agrícolas e em animais para o controle de pragas. O IMD é rapidamente absorvido pelo trato gastrointestinal e por contato, sendo rápida e uniformemente distribuído nos órgãos e tecidos. Dados da literatura mostram que as concentrações mais elevadas foram observadas nos órgãos de eliminação: fígado e rins. O fígado é o principal órgão envolvido na biotransformação de substâncias exógenas (xenobióticos), convertendo compostos hidrofóbicos em hidrossolúveis, mais facilmente eliminados pelo organismo. Vários estudos vêm sendo conduzidos sobre os efeitos tóxicos do IMD em animais, causando danos ao fígado. Nesse sentido, o objetivo desse estudo foi avaliar os mecanismos envolvidos na toxicidade do IMD sobre a bioenergética de mitocôndrias e hepatócitos isolados de rato e ações do IMD sobre o metabolismo de carboidratos e proteínas em fígado de rato em perfusão. Em mitocôndrias isoladas, o IMD promoveu uma diminuição dose-dependente no estado 3 da respiração e na produção de ATP, sem afetar o potencial de membrana mitocondrial. Experimentos subsequentes medindo o consumo de oxigênio mostraram que o IMD não afeta a cadeia respiratória e que seu efeito é semelhante ao da oligomicina (inibidora da FoF1-ATP sintase) e/ou ao do atractilosídeo (inibidor do translocador de nucleotídeos de adenina, ANT). IMD inibiu a atividade da FoF1-ATP sintase em mitocôndrias rompidas e inibiu parcialmente a despolarização do potencial de membrana induzida pelo ADP. Esses resultados indicam que o IMD afeta a bioenergética mitocondrial por meio da inibição da FoF1-ATP sintase. Em Experimentos com hepatócitos isolados de rato os resultados da respiração foram semelhantes aos encontrados nas mitocôndrias isoladas, porém o IMD afetou a produção intracelular de ATP e induziu a morte celular somente nos hepatócitos isolados de ratos previamente tratados com dexametasona, um ativador do citocromo P450. No fígado de rato em perfusão o IMD também inibiu a produção de glicose por meio da gliconeogênese. Esses resultados sugerem que a toxicidade do IMD pode estar associada a alterações no metabolismo energético celular sendo a enzima FoF1-ATP sintase o principal alvo da ação tóxica deste inseticida, e que os metabólitos formados na biotransformação do IMD podem ser mais tóxicos do que o próprio IMD.
Imidacloprid (IMD) is a neonicotinoid insecticide widely used in various crops and animals for pest control. IMD is rapidly absorbed by the gastrointestinal tract, being rapidly and evenly distributed in the organs and tissues. The highest concentrations were observed in the elimination organs: liver and kidneys. The liver is the main organ involved in the biotransformation of exogenous substances (xenobiotics), with the capacity to convert hydrophobic compounds into water soluble metabolites, which are more easily eliminated by the organism. Studies have been conducted on the toxic effects of IMD on animals, causing damage to the liver. In this sense, the objective of this study was to evaluate the mechanisms involved in the toxicity of IMD on the bioenergetics of mitochondria and isolated hepatocytes of rats and its actions on the metabolism of carbohydrates and proteins in liver of rats in perfusion. In isolated mitochondria, IMD promoted a dose-dependent decrease in the state 3 of mitochondrial respiration and ATP levels, without affecting mitochondrial membrane potential. Subsequent experiments measuring oxygen consumption have shown that IMD does not affect the electron transport chain and that its effect is similar to that of oligomycin (FoF1-ATP synthase inhibitor) and/or atracytoside (ANT adenine nucleotide translocator inhibitor). In the perfusion rat liver IMD inhibited the activity of FoF1-ATP synthase in freeze/thaw-disrupted mitochondria and partially inhibited the depolarization of the membrane potential induced by ADP. These results indicate that IMD affects in mitochondrial bioenergetics by inhibiting FoF1-ATP synthase. In experiments with isolated hepatocytes respiration results were similar to those found in isolated mitochondria, but IMD affected the intracellular production of ATP and induced cell death only in hepatocytes isolated from rats previously treated with dexamethasone, a cytochrome P450 activator. IMD also inhibited the production of glucose by gluconeogenesis. These results suggest that IMD toxicity may be associated with changes in cellular energy metabolism with the enzyme FoF1-ATP synthase being the main target of the toxic action of this insecticide, and that the metabolites formed in the biotransformation of the IMD may be more toxic than the IMD itself.
FAPESP: 2015/19549-8

Aquest és el primer informe que demostra que l'autofàgia està mecànicament vinculat al manteniment de les cèl•lules tumorals que expressen alts nivells de CD44 i baixos nivells de CD24, que són típics de les cèl•lules mare del càncer de mama. Els nostres resultats actuals proporcionen una nova visió de com la divisió mitocondrial s'integra a la xarxa de la transcripció impulsada per factors de reprogramació, especifica de la pluripotència única de les cèl•lules mare. L'autofàgia pot controlar la refractarietat de novo de carcinomes de mama amb el gen HER2 amplificat per l'anticòs monoclonal trastuzumab (Herceptin). Per tant, el tractament de combinació amb trastuzumab i cloroquina, com a fàrmac anti-malàric i inhibidor de l’autofàgia, suprimeix radicalment el creixement del tumor en un xenoempelt de tumor completament refractari a trastuzumab en un model murí. L’addició de cloroquina amb els règims amb trastuzumab pot, per tant, millorar els resultats en les dones amb càncer de mama HER2. Aquesta és una àrea molt emocionant i molt prometedora de la investigació del càncer, com la modulació farmacològica de l'autofàgia sembla augmentar l'eficàcia dels règims contra el càncer disponibles en l'actualitat i s'obre el camí per al desenvolupament de noves estratègies terapèutiques combinatòries que s'espera que contribueixin a l'eradicació del càncer.
This is the first report demonstrating that autophagy is mechanistically linked to the maintenance of tumor cells expressing high levels of CD44 and low levels of CD24, which are typical of breast cancer stem cells. Our current findings provide new insight into how mitochondrial division is integrated into the reprogramming of the factors-driven transcriptional network that specifies the unique pluripotency of stem cells. Autophagy may control the de novo refractoriness of HER2 gene-amplified breast carcinomas to the monoclonal antibody trastuzumab (Herceptin). Accordingly, treatment with trastuzumab and chloroquine, as antimalarial drug and inhibitor of autophagy, radically suppresses tumor growth in a tumor xenograft completely refractory to trastuzumab in a mouse model. Adding chloroquine to trastuzumab-based regimens may therefore improve outcomes among women with autophagy-addicted HER2-positive breast cancer. This is a very exciting and highly promising area of cancer research, as pharmacologic modulation of autophagy appears to augment the efficacy of currently available anticancer regimens and opens the way to the development of new combinatorial therapeutic strategies that will hopefully contribute to cancer eradication.

Thesis: Ph. D. in Biochemistry, Massachusetts Institute of Technology, Department of Biology, February, 2021
Cataloged from the official PDF of thesis. "February 2021." Vita. Page 179 blank.
Includes bibliographical references.
Cellular growth and proliferation necessitates the transformation of cell-external nutrients into biomass. Strategies of biomass accumulation across the kingdoms of life are diverse and range from carbon fixation by autotrophic organisms to direct biomass incorporation of consumed nutrients by heterotrophic organisms. The goal of this dissertation is to better understand the divergent and convergent modes of metabolism that support biomass accumulation and proliferation in eukaryotic cells. We first determined that the underlying mechanism behind why rapidly proliferating cells preferentially ferment the terminal glycolytic product pyruvate is due to an intrinsic deficiency of respiration to regenerate electron acceptors. We tested this model across an assorted array of proliferating cells and organisms ranging from human cancer cells to the baker's yeast Saccharomyces cerevesiae. We next determined that a major metabolic pathway of avid electron acceptor consumption in the context of biomass accumulation is the synthesis of lipids. Insights from this work has led to the realization that net-reductive pathways such as lipid synthesis may be rate-limited by oxidative reactions. Lastly, we established the green algae Chlorella vulgaris as a model system to study the comparative metabolism of photoautotrophic and heterotrophic growth. We determined that heterotrophic growth of plant cells is associated with aerobic glycolysis in a mechanism that may be suppressed by light. Collectively, these studies contribute to a more holistic understanding of the bioenergetics and metabolic pathways employed by eukaryotic cells to accumulate biomass and lay the foundation for future studies to understand proliferative metabolism.
by Zhaoqi Li.
Ph. D. in Biochemistry
Ph.D.inBiochemistry Massachusetts Institute of Technology, Department of Biology

Bilirubin is a haem catabolite that is excreted through the hepatobiliary pathway and is therefore, commonly used as a biomarker of hepatic dysfunction and haemolysis in the clinical setting [1]. Although, bilirubin has been considered toxic [2], recent evidence suggests that mildly elevated circulating bilirubin concentrations may be protective against obesity, cardiovascular diseases (CVDs) and all-cause mortality [3–5]. Generally, the protective effects of bilirubin are attributed to its antioxidant potential [6–8], however, recent studies demonstrate that bilirubin modulates lipid metabolism and reduces adiposity, which could partly contribute to CVD protection [5,9–12]. However, a shortage of studies have examined the precise mechanisms of cholesterol metabolism and adiposity that could be affected by bilirubin. The main aims of this thesis were to: 1) determine whether hyperbilirubinaemia affects cholesterol synthesis, transport, and excretion; 2) explore bilirubin’s impact on body composition and bioenergetics including mitochondrial function in liver/skeletal muscle and changes in mitochondrial density and quality; 3) determine the effectiveness of oral Legalon® ingestion on circulating bilirubin concentrations, to investigate whether inducing mild hyperbilirubinaemia could impact circulating lipid concentrations in human participants. The first study measured the effect of hyperbilirubinaemia in mutant Gunn rats on circulating lipid concentrations, cholesterol synthesis, lipid excretion, and expression of hepatic genes/proteins involved in cholesterol metabolism. Female hyperbilirubinaemic (Gunn) rats had reduced serum cholesterol concentrations (0.60 ± 0.12 vs 1.56 ± 0.34 mM, P<0.001), elevated cholesterol synthesis (33.8 ± 3.77 vs 28.4 ± 5.73 % [13C]-cholesterol, P<0.05), enhanced LDL receptor (LDLr; P<0.01) expression, and increased biliary cholesterol excretion (232 ± 32.7 vs 141 ± 42.1 nmol hr-1 100g-1 bodyweight, P<0.001) compared to female normobilirubinaemic littermate (control) rats. These results indicate that female hyperbilirubinaemic Gunn rats have reduced circulating cholesterol in association with elevated LDLr expression. Increased LDLr expression and cholesterol synthesis is typical when hepatic cholesterol concentrations are decreased [13,14]. Therefore, increased cholesterol synthesis and LDLr expression observed in female Gunn rats may represent a counter-regulatory mechanism to maintain hepatic cholesterol content in the presence of elevated biliary cholesterol excretion [13,14]. The underlying mechanism explaining increased biliary lipid excretion in female Gunn rats remains unknown. However, this observation could be partly explained by greater relative biliary lipid (cholesterol+phospholipid) to bile acid excretion (0.33 ± 0.06 vs 0.24 ± 0.03 mol:mol, lipid:bile acids, P<0.01) in female Gunn rats. Previous studies have established that organic anions including bilirubin glucuronides disrupt the capacity of bile acid micelles to excrete lipids in the bile [15]. Biliary excretion of bilirubin conjugates was decreased in female (13.1 ± 2.92 vs 33.5 ± 5.09 nmol hr-1 100g-1 bodyweight, P<0.001) and male (11.0 ± 2.43 vs 43.2 ± 12.8 nmol hr-1 100g-1 bodyweight, P<0.001) Gunn rats compared to controls, due to UGT1A1 dysfunction and the inability to conjugate bilirubin. Therefore, decreased biliary excretion of bilirubin conjugates, as observed in Gunn rats, may potentially facilitate the greater coupled excretion of biliary lipids to bile acids as demonstrated in this study. It should be noted that this conclusion does not completely explain the results reported here because Gunn rats demonstrated significant sexual dimorphism in cholesterol metabolism. Male Gunn rats exhibited a non-significant reduction in circulating cholesterol concentrations (1.41 ± 0.15 vs 1.56 ± 0.23, P=0.14) and increased biliary lipid:bile acid excretion (0.31 ± 0.07 vs 0.25 ± 0.04 mol:mol, lipid:bile acid, P=0.08) compared to male normobilirubinaemic littermate (control) rats, indicating that additional mechanisms, beyond bilirubin excretion, are involved. For example, UGT1A1, which conjugates bilirubin also conjugates and facilitates the excretion of sex hormones including oestrogen. Therefore, oestrogen concentrations may be elevated in female hyperbilirubinaemic rats and synergistically impact lipid metabolism [16,17]. The second study examined the effect of hyperbilirubinaemia in vitro and in vivo on mitochondrial function and body composition. Dual X-ray absorptiometry (DEXA) analysis revealed that female Gunn rats had significantly reduced fat mass (9.94 ± 5.35 vs 16.1 ± 6.65 g, P<0.05) and lean mass (140 ± 12.1 vs 160 ± 16.0 g, P<0.05) compared to littermate controls. Female Gunn rats consumed fewer calories per day (54.1 ± 6.38 vs 63.3 ± 6.95 kcal day-1, P<0.01). However, weight gain relative to calories consumed was reduced (8.09 ± 5.75 vs 14.9 ± 5.10 mg kcal-1, P<0.05) in female Gunn rats indicating that they are less energetically efficient. This led to the analysis of mitochondrial function in liver and skeletal muscle using high-resolution respirometry to ascertain the cause of reduced energetic efficiency. This analysis revealed that female Gunn rats exhibited increased oxidative phosphorylation (OXPHOS) relative to maximal noncoupled mitochondrial respiration (ETS) in hepatic mitochondria (0.78 ± 0.16 vs 0.62 ± 0.09 OXPHOS:ETS, P<0.05). The above findings were consistent with the effect of exogenous addition of unconjugated bilirubin (UCB) to control hepatic mitochondria, with 31.3 and 62.5 μM UCB increasing the OXPHOS: ETS ratio. However, exogenous UCB addition produced this effect by inhibiting ETS without affecting OXPHOS, indicating that UCB induces mitochondrial dysfunction at high concentrations. Conversely, no change in ETS (1130 ± 217 vs 1290 ± 373 pmol s-1 ng-1 citrate synthase (CS), P=0.16) or OXPHOS (901 ± 222 vs 796 ± 259 pmol s-1 ng-1 CS, P=0.36) was observed between female Gunn rats and controls. These data indicate that the greater OXPHOS:ETS ratios are a combination of increased OXPHOS and decreased ETS in female Gunn rats. Analysis of mitochondrial respiratory complexes revealed greater hepatic mitochondrial complex IV (CIV; P<0.01) expression in female Gunn rats. These findings support a conclusion that hepatic mitochondria have increased quality in female Gunn rats [18,19]. At present it remains unknown how this change in mitochondrial quality relates to reduced fat mass and energetic efficiency, however, the changes observed in female Gunn rats could represent an adaptation to bilirubin mediated inhibition of CIV as reported in vitro [20,21]. Otherwise, alterations in reproductive hormone metabolism in Gunn rats could also partially explain altered energetic states, as speculated in study one. Considering that hyperbilirubinaemia induced perturbed lipid metabolism and body composition in chapters one and two, study three sought to determine whether increasing bilirubin could alter circulating lipid profile in humans. The effect of Legalon®, containing the active ingredient silymarin, supplementation on circulating bilirubin concentrations and lipid status was investigated in a placebo controlled, single blind crossover clinical trial in healthy individuals (ACTRN12619001296123). Legalon® capsules containing 140 mg of silymarin were supplemented thrice daily (total dose of 420 mg silymarin) in a cohort of healthy males for two weeks. Two weeks of Legalon® supplementation did not change UCB concentrations compared to baseline (Legalon®: 12.5 ± 7.63 vs Baseline: 11.4 ± 4.14 μM, P=0.79). Secondary outcomes including lipid concentrations, inflammation, and total antioxidant status were also reported. Two weeks of Legalon® supplementation did not change serum cholesterol (4.80 ± 1.00 vs 4.88 ± 1.00 mM, P=0.19), triglyceride (1.07 ± 0.63 vs 1.04 ± 0.54 mM, P=0.79), C-reactive protein concentrations (1.74 ± 1.88 vs 0.92 ± 0.87 mg L-1, P=0.23) or serum antioxidant capacity (1194 ± 182 vs 1183 ± 201 mmol Fe2+ L-1, P=0.19) compared to baseline. Several clinical trials evaluating the impact of silymarin have reported changes to bilirubin concentrations following treatment [22–24]. However, these studies were conducted in patients with hepatic disease, which confounded bilirubin results, and with greater doses or different formulations of silymarin to that reported in this thesis. Although the results of this study demonstrated a negative finding, they are important because they represent the first attempt to use an orally administered, commercially approved, nutraceutical compound to increase bilirubin. These results provide important guidance to future studies that could utilise different doses or commercial preparations to induce a transient unconjugated hyperbilirubinaemia and test the impact on circulating cholesterol concentrations. In conclusion, this thesis contains three novel investigations that aimed to determine the impact of unconjugated hyperbilirubinaemia on cholesterol metabolism, synthesis and hepatic excretion; in addition to its effect on mitochondrial metabolism and body composition in Gunn rats. To determine whether these effects could be induced in humans, a nutraceutical with documented effects on circulating bilirubin was administered in a clinical trial, utilising a randomised, single-blind, crossover design. The results of this thesis suggest that bilirubin has the potential to modulate lipid and whole-body metabolism, particularly in female animals and provides the groundwork for additional studies that seek to reveal the mechanisms responsible for bilirubin’s effects. In addition, this thesis will support the discovery of more effective orally administered compounds that can modulate circulating bilirubin and lipid profile for protection against CVD.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Medical Science
Griffith Health
Full Text

Non-canonical bioenergetics concerns with those physiological and pathophysiological situations under which ATP synthesis is suppressed. This thesis brings an outcome of three types of studies within the field of the non-canonical bioenergetics, investigating specific bioenergetic phenotypes of cancer cells, on one hand; and a role of mitochondrial uncoupling proteins as deduced from their transcript distribution in various tissues and organs; plus a role of a novel and likely pro-apoptotic factor CIDEa in mitochondria. Cancer cells generally present abnormal bioenergetic properties including an elevated glucose uptake, a high glycolysis and a poorly efficient oxidative phosphorylation system. However, the determinants of cancer cells metabolic reprogramming remain unknown. The main question in this project was how environmental conditions in vivo can influence functioning of mitochondrial OXPHOS, because details of mitochondrial bioenergetics of cancer cells is poorly documented. We have combined two conditions, namely glucose and oxygen deprivation, to measure their potential interaction. We examined the impact of glucose deprivation and oxygen deprivation on cell survival, overall bioenergetics and OXPHOS protein expression. As a model, we have chosen a human breast carcinoma (HTB-126) and appropriate control (HTB-125) cultured cells, as large fraction of breast malignancies exhibit hypoxic tumor regions with low oxygen concentrations and poor glucose delivery. The results demonstrate that glucose presence or absence largely influence functioning of mitochochondrial oxidative phosphorylation. The level of mitochondrial respiration capacity is regulated by glucose; by Crabtree effect, by energy substrate channeling towards anabolic pathways that support cell growth and by mitochondrial biogenesis pathways. Both oxygen deprivation and glucose deprivation can remodel the OXPHOS system, albeit in opposite directions. As an adaptative response to hypoxia, glucose inhibits mitochondrial oxidative phosphorylation to the larger extent than in normoxia. We concluded that the energy profile of cancer cells can be determined by specific balance between two main environmental stresses, glucose and oxygen deprivation. Thus, variability of intratumoral environment might explain the variability of cancer cells´ bioenergetic profile. Mitochondrial uncoupling proteins are proteins of inner mitochondrial membrane that uncouple respiration from ATP synthesis by their protonophoric activity. Originally determined tissue distribution seems to be invalid, since novel findings show that UCP1 is not restricted exclusively to brown fat and that originally considered brain-specific isoforms UCP4 and UCP5 might have wider tissue distribution. Hence, in second part of this thesis, I discuss consequences of findings of UCPn transcripts in the studied mouse and rat tissues. We have shown that mRNA of UCPn varies up to four orders of magnitude in rat and mouse tissues with highest expression in rat spleen, rat and mouse lung, and rat heart. Levels of the same order of magnitude were found for UCP3 mRNA in rat 100 and mouse skeletal muscle, for UCP4 and UCP5 mRNA in mouse brain, and for UCP2 and UCP5 mRNA in mouse white adipose tissue. Further, we have shown that expression pattern of UCPn varies between animal species, rat versus mouse, such as the dominance of UCP3/UCP5 vs. UCP2 transcript in mouse heart and vice versa in rat heart; or UCP2 (UCP5) dominance in rat brain contrary to 10-fold higher UCP4 and UCP5 dominance in mouse brain. spontaneous apoptosis due to CIDEa overexpression in HeLa cells, adapted for a tetracycline-inducible CIDEa expression, a portion of mitochondria-localized CIDEa molecules migrates to cytosol or nucleus
Résumé non disponible

During the past 30-years, Biochemical System Theory (BST) has been provided a concrete foundation for the study of the dynamic biological systems, e.g. S-systems models for reverse engineering of metabolic networks (Savageau, 1969; Savageau, 1970; Voit, 2000). One of the remarkable characteristics of these models is its parameters not only quantify the interactions between the components of the network, but also elucidate the networks topology. Automatic procedures for S-system parameterization from biological time series have been developed by many researches, where they assume a noise-free time series and a true estimated first derivative in their methodologies (Chou, et al., 2006; Kikuchi, et al., 2003). Nevertheless, this noise-free data is not a realistic scenario of the real biological experimental world. Methods as artificial neural network (ANN), Support Vectors Machines (SVM) and Saviztsky-Golay filter were proposed to overcome the denoising time series problem with the advantage of a closed form output which allowed determining the first derivative symbolically (Almeida and Voit, 2003; Borges, et al., 2006; Borges, et al., 2004; Voit and Almeida, 2004). However, these solutions showed some problematic artifacts in its first derivative even when they are not visually apparent in the smoothed data, leaving a gap on the issue of a fully automatic method for S-system parameterization from experimental data. The algorithm presented in this work is a proposal to fill this gap up providing an unbiased robust tool for signal extraction and first derivative estimation from noisy time series.
Nos últimos 30 anos, a Teoria dos Sistemas Bioquímicos (Biochemical System Theory - BST) tem fornecido uma fundação concreta para o estudo da dinâmica de sistemas biológicos, por exemplo, Sistemas-S (S-systems) usados em engenharia reversa de vias metabólicas (Savageau, 1969; Savageau, 1970; Voit, 2000). Uma característica marcante desse tipo de modelo é que os parâmetros não só quantificam as interações entres os componentes da rede metabólica, mas também fornecem a sua topologia de regulação. Procedimentos automáticos para a parametrização dos Sistemas-S a partir de séries temporais biológicas vêm sendo desenvolvidos por vários pesquisadores, onde se assume que a série temporal e sua derivada temporal são livres de ruído. Entretando, perfis metabólicos livres de ruído não são um realistas em cenários de experimentos de biologia molecular. Técnicas como Redes Neurais Artificiais (RNA), Máquinas de Vetores de Suporte (MVP) e filtro de Saviztsky-Golay foram propostas como solução do problema de suavização dos perfis metabólicos com a vantagem da obtenção da derivada temporal simbólica (Almeida and Voit, 2003; Borges, et al., 2006; Borges, et al., 2004; Voit and Almeida, 2004). Entretanto, essas soluções apresentaram alguns artefatos problemáticos na derivada até mesmo quando nenhum problema é visualmente detectado no dado suavizado, deixando aberto um espaço vazio na questão de um método automático para a parametrização dos Sistemas-S a partir de dados experimentais. O algoritmo apresentado neste trabalho propõe preencher esse espaço com uma ferramenta robusta para a extração de sinal e de sua derivada temporal a partir de séries temporais ruidosas.

L'inflammation est associée à des modifications du métabolisme cellulaire avec une glycolyse (libération de lactate) accrue accompagnée d'une baisse de la phosphorylation oxydative mitochondriale. L'inflammation cause l'hyperosmolarité du milieu extracellulaire. Cette thèse examine les effets de l'hyperosmolarité sur le métabolisme énergétique cellulaire. Nous avons mesuré la consommation d'oxygène cellulaire (OCR) et la production d'acide (PPR) c'est à dire de lactate libéré dans le milieu extérieur avec deux approches expérimentales : l'oxygraphie haute résolution (O2k Oroboros instrument) pour l'OCR et l'analyseur de flux extracellulaires (Seahorse Agilent) pour l'OCR et le PPR. L'exposition de cellules à des conditions hyperosmolaires (600 mOsmoles au lieu de la valeur normale 300) cause une répression de la consommation d'oxygène qui s'établit en quelques minutes et dure des heures (indéfiniment?) et à la longue affecte la viabilité cellulaire. Cet effet a été retrouvé sur plusieurs types cellulaires: CHO (épithélium ovarien), HT29 (colonocytes), HEK293 (rein embryonnaire), SH-SY5Y (neuroblastome). Il est reproduit avec trois osmolytes différents: le mannitol, le polyéthylène glycol et le chlorure de sodium. Un stress osmotique plus modéré (450 mOsm) cause une même chute de la respiration mais de durée limitée (une-deux heures). Une recherche des mécanismes à l'origine de cette inhibition montre que l'hyperosmolarité altère la fonction mitochondriale de différentes manières. Un premier effet est une inhibition du système enzymatique de production d'ATP. En présence de glucose cette inhibition s'accompagne d'une importante augmentation de la glycolyse qui cause une inhibition mitochondriale supplémentaire qui repose sur l'amplification de l'effet Crabtree (inhibition de la respiration par le glucose) dont la cible sont les complexes respiratoires. En l'absence de glucose le turnover cellulaire e l'ATP est sérieusement diminué mais de façon inattendue la survie cellulaire est plutôt meilleure. Ces résultats posent la question de la contribution des conditions hyperosmotiques liées à l'inflammation dans l'établissement d'un profil métabolique de type inflammatoire
Metabolic alterations associated with inflammation include increased recruitment of glycolysis (lactate release) and repression of mitochondrial oxidative phosphorylation. Inflammation causes hyperosmolar conditions in the extracellular medium. This thesis examines the consequences of hyperosmolarity on cellular bioenergetics. For this purpose we measured the cellular oxygen consumption rate (OCR) and proton production rate (PPR) for lactate release in the external medium. Two methodologies were used the high-resolution respirometer (O2k Oroboros Instruments) for OCR and the extracellular flux analyzer (Seahorse, Agilent) for OCR and PPR. The exposure cells to hypertonic conditions (600 milliOsmoles while normal value is 300) causes within few minutes a decrease in OCR (cellular respiration) that lasts for hours (indefinitely) and in the long term impact on cellular viability. This effect was observed with four different cell lines CHO (ovarian epithelial), HT29 (colonocytes), HEK293 (Embryonic kidney) and SH-SY5Y (Neuroblastoma). It was shown to be caused by three different osmolytes: Mannitol, polyethylene glycol, sodium chloride. A milder osmotic challenge (450 mOsm) caused a similar initial decrease but with restoration of initial OCR within few hours. The mechanisms underlying this effect have been investigated, hyperosmolarity impacts on mitochondrial respiration at different steps. A first effect is the inhibition of the mitochondrial ATP production step. In presence of glucose this is accompanied by a large increase in glycolysis (lactate release) that causes further mitochondrial inhibition by a second mechanism, which is likely to represent an enhancement of the Crabtree effect (inhibition of respiration by glycolysis) that impacts on respiratory complexes. In absence of glucose the cellular ATP turnover is seriously repressed surprisingly cellular survival is rather improved. These results raise therefore the question of the possible contribution of the hyperosmotic conditions caused by inflammation in the acquisition of the inflammatory metabolic profile

The rampant growth of obesity worldwide has stimulated explosive research into human metabolism. Metabolic rate has been shown to be altered by diets differing in macronutrient composition, with low-carbohydrate, ketogenic diets eliciting a significant increase over other interventions. The purpose of this study was to determine the effects of the ketone β-hydroxybutyrate (βHB) on mitochondrial respiration and coupling status in adipose tissue. To explore this, we employed three distinct systems, namely cell, rodent, and human models. In every model, βHB robustly increased mitochondrial respiration. Furthermore, in cultured adipocytes and rodent adipose, we quantified the expression of genes involved in mitochondrial biogenesis and coupling status. We observed that genes involved in mitochondrial biogenesis and uncoupling were significantly higher in models exposed to ketone treatments. In conclusion, ketones increase mitochondrial respiration in cells and mammalian adipose tissue, but not ATP production, indicating greater mitochondrial uncoupling. These findings may partly explain the increased metabolic rate evident in states of elevated ketones and may facilitate the development of novel obesity interventions in the future.

Multicellular tumour spheroids (TS) are an in vitro model of avascular tumours, and have been widely used to investigate tumour growth, metabolism and hypoxia. The geometry of the TS lends itself to mathematical representation, and theoretical models of TS growth and the development of hypoxia are abundant. With some notable exceptions however, these models have been developed independently of the biological data collection process and are overwhelmingly based upon data from multiple sources. Thus, whilst mathematical modeling has the potential to help explain and guide biological experiments, without reliable data it is unlikely to live up to this expectation. In this thesis, a combination of experimental and theoretical approaches was used to characterize the relationship between proliferation, hypoxia and metabolism during the growth of TS derived from the DLD-1 human colon adenocarcinoma cell line. Experimental data were collected over the entire period of TS growth, generating a high volume of predominantly imaging data. To facilitate the extraction of quantitative information from this, a suite of image analysis software, which is readily applicable to other data sets, was developed. During growth, the DLD-1 TS maintained a macroscopic spherical geometry but at the microscale level the TS boundary was increasingly irregular, with TS disintegrating rapidly after 20 days. Immunofluorescence (IF) studies showed that hypoxia developed soon after TS initiation, followed by the characteristic onset of necrosis. Reduced proliferation was found to be concomitant with the development of hypoxia, although some cells retained proliferative capacity even under severely hypoxic conditions. Towards the end of culture, TS were primarily comprised of severely hypoxic and necrotic cells, a probable cause of disintegration. Mathematical simulation of oxygen gradients in TS using literature-based values for the maximal rate of oxygen consumption was used to estimate the partial oxygen pressure (pO₂) at which the IF marker of hypoxia was bound. Assuming a spatially-invariant rate of oxygen consumption, the model predicted that the onset of hypoxic binding occurs at pO₂ levels similar to those reported in the literature, however the onset of necrosis was overestimated. Mathematical simulations predicted that oxygen consumption decreases as TSs increase in size, supporting previous observations. The Warburg Effect, where glucose metabolism is favoured even under aerobic conditions, is a hallmark of tumours. Although development of the glycolytic phenotype during TS growth was observed in the form of an elevated activity of the lactate dehydrogenase V (LDHV) enzyme, the activity and expression of other glycolytic enzymes, such as hexokinase II (HKII), was unaltered. Whilst the spatial distribution of HKII was unrestricted throughout the TS's viable fraction, LDHV expression was elevated in regions of hypoxia, suggesting constant adaptation of tumour cells to their microenvironment. In addition to the above findings, the data generated have been collected and analysed in the context of the requirements of theoretical modelling at each step; thus, they can be used to parameterise and inform more sophisticated models of tumour metabolism.

Energetic efficiency is important for health (e.g. genesis of obesity in humans), socio-economically important for meat production systems (e.g. feed cost to produce high quality protein) and important for the environment (e.g. use of natural resources and production of green house gases for meat production). Mitochondria are organelles that play an essential role in cellular metabolism and homeostasis related to energy utilization. These processes involve several proteins to ensure continuous availability of energy to the cells. The Shc proteins play a key role in substrate oxidation and energy metabolism. Additionally, the mitochondrial uncoupling proteins (UCPs) participate in physiological processes that may account for variation in energy expenditures in tissues. However, the mechanisms behind energy expenditure in animals are largely unknown. Thus, in order to study the energy metabolism and mitochondria function, studies using a nutritional, biochemical and molecular approaches were conducted with mice and cattle. The purpose of the first study was to determine if Shc proteins influence the metabolic response to acute (5-7 days) feeding of a high fat diet (HFD). To this end, whole animal energy expenditure and substrate oxidation were measured in the Shc knockout (ShcKO) and wild-type (WT) male mice consuming either a control or HFD diet. The activities of enzymes of glycolysis, the citric acid cycle, electron transport chain (ETC), and β-oxidation were investigated in liver and skeletal muscle. The study showed that ShcKO increases (P < 0.05) energy expenditure (EE) adjusted for either total body weight or lean mass. This change in EE could explain the decrease in weight gain observed in ShcKO versus WT mice fed an HFD. Thus, our results indicate that Shc proteins should be considered as potential targets for developing interventions to mitigate weight gain on HFD by stimulating EE. Although decreased levels of Shc proteins influenced the activity of some enzymes in response to high fat feeding, such as increasing the activity of acyl-CoA dehydrogenase, it did not produce concerted changes in enzymes of glycolysis, citric acid cycle or the ETC. However, the physiological significance of these changes in enzyme activities remains to be determined. The purpose of experiment 2 was to study the association among heat production, blood parameters and mitochondrial DNA (mtDNA) copy number in Nellore bulls with high and low residual feed intake (RFI). The RFI values were obtained by regression of dry mater intake (DMI) in relation to average daily gain and mid-test metabolic body weight. Thus, 18 animals (9 in each group) were individually fed in a feedlot for 98 days. The heart rate (HR) of bulls was monitored for 4 consecutive days and used to calculate the estimated heat production (EHP). Electrodes were fitted to bulls with stretch belts and oxygen consumption was obtained using a facemask connected to the gas analyzer and HR was simultaneously measured for 15 minutes period. Daily EHP was calculated multiplying oxygen pulse (O2P) by the average HR, assuming 4.89 kcal/L of O2. Blood parameters such as hematocrit, hemoglobin, and glucose were assayed between 45 and 90 days. Immediately after slaughter, liver, muscle and adipose tissues (subcutaneous and visceral fat) were collected and, subsequently, mtDNA copy number per cell was quantified in tissues by quantitative real-time PCR. The proteome of hepatic tissue and levels of mitochondrial UCPs were also investigated. We found similar EHP and O2 consumption between RFI groups, while low RFI bulls (more efficient in feed conversion) shown lower HR, hemoglobin and hematocrit percentage (P < 0.05), confirming previous data from our group. In addition, 71 protein spots in liver were differentially expressed (P < 0.05) and no differences were detected for UCPs levels between RFI groups. Finally, there was no association between amounts of mtDNA and the RFI phenotypes, suggesting that mitochondrial abundance in liver, muscle, and adipose tissue was similar between efficient and inefficient groups. However, additional studies to confirm this hypothesis are needed.
A eficiência energética é importante para a saúde humana (gênese da obesidade), sistemas de produção de carne (custo dos alimentos para produzir proteínas de alta qualidade) e para o meio ambiente (uso de recursos naturais e mitigação de gases de efeito estufa). As mitocôndrias são organelas que desempenham papel central no metabolismo e homeostase relacionada a utilização da energia. Nas células, diversas proteínas são importantes para melhorar a eficiência energética. Como exemplos, as proteínas de sinalização Shc são fundamentais na oxidação de substratos e metabolismo energético e, nas mitocôndrias, existem as proteínas desacopladoras (UCPs), que participam do gasto energético e produção de calor. Entretanto, os mecanismos que controlam o gasto energético nos animais ainda é bastante desconhecido. Assim, para estudar o metabolismo energético e a função das mitocôndrias foram conduzidos dois estudos utilizando-se estratégias nutricionais, bioquímicas e moleculares com camundongos (1) e bovinos (2). Objetivou-se, no estudo 1, determinar se as proteínas Shc influenciam a resposta metabólica à alimentação contendo dieta rica em gordura (HFD) por 7 dias. Enzimas da via glicolítica, ciclo de Krebs, cadeia transportadora de elétron (CTE) e β-oxidação foram analisadas no fígado e músculo de camundongos com baixa expressão de Shc (knockout ou ShcKO) e comuns (wild-type ou WT) submetidos à uma dieta controle ou à HFD. O gasto energético foi medido por câmara calorimétrica de respiração nos animais. O genótipo ShcKO apresentou maior gasto energético (P < 0.05) ajustado para o peso corporal total ou massa magra. Essa mudança poderia explicar o menor ganho de peso observado no genótipo ShcKO comparado ao WT quando consumindo a HFD. Esses resultados sugerem que as proteínas Shc podem contribuir no desenvolvimento de estratégias para mitigar o ganho de peso. Embora a redução dos níveis de Shc (ShcKO) tenha modificado a atividade de enzimas da β-oxidação em resposta a HFD, tal condição não produziu mudanças semelhantes na via glicolítica, ciclo de Krebs ou CTE. Por isso, mais estudos são necessários para compreender a significância fisiológica dessas alterações. No experimento 2, objetivou-se estudar a associação entre produção de calor, variáveis sanguíneas e número de cópias de DNA mitocondrial (mtDNA) em bovinos Nelore agrupados pelo consumo alimentar residual (CAR). O CAR foi obtido por regressão do consumo de matéria seca em relação ao ganho de peso diário e peso metabólico do teste de desempenho (fase de crescimento). Assim, 18 bovinos (9 alto CAR versus 9 baixo CAR) foram confinados em baias individuais por 98 dias (fase de terminação). Os batimentos cardíacos (BC) dos bovinos foram monitorados por quatro dias consecutivos e, então, utilizados para o cálculo da produção de calor estimada (PCe). O consumo e pulso de oxigênio (O2) foram obtidos por meio de analisador de gás conectado à uma máscara facial, com medição simultânea dos BC por 15 minutos. A PCe diária foi calculada por multiplicação do pulso de O2 pela média dos BC, assumindo-se a constante 4.89 kcal/L de O2. Foram analisadas variáveis sanguíneas como hematócrito, hemoglobina e glicose (alto vs. baixo CAR). Imediatamente após o abate dos animais, amostras de fígado, músculo e tecido adiposo foram coletadas para determinação do mtDNA por PCR em tempo real. Adicionalmente, o proteoma do tecido hepático e os níveis de UCPs nos tecidos foram também investigados. Não houve diferença para PCe e consumo de O2 (P > 0.05) entre os grupos experimentais, entretanto, os animais baixo CAR (mais eficientes em conversão alimentar) demonstraram menor BC, concentração de hemoglobina e percentagem de hematócrito (P < 0.05), confirmando resultados previamente observados em nossos estudos. No fígado, 71 spots proteicos foram diferentes (P < 0.05) entre os grupos alto e baixo CAR, mas nenhuma diferença foi observada para os níveis de UCPs no músculo, fígado ou tecido adiposo. Por fim, não existiu diferença (P > 0.05) entre o número de cópias do mtDNA por célula entre os fenótipos estudados, sugerindo que o número de mitocôndrias e possivelmente a fosforilação oxidativa foi semelhante entre os grupos de animais eficientes e ineficientes. Contudo, são necessários estudos adicionais para confirmar essa hipótese.

This thesis consists of two literature reviews followed by three empirical chapters that examined the relationship between chronic sleep restriction and obesity. Chapter 2 reviewed available research data and presented a theoretical model linking chronic sleep restriction to obesity. This model hypothesises that chronic sleep restriction contributes to obesity by altering energy regulatory hormones such as ghrelin and leptin. It was also argued that factors such as poor mental health, medication use and long work hours contribute to chronic sleep restriction at a population level, and could have implications for improving sleep. This model provides a sound theoretical framework, which was used to guide the subsequent empirical chapters. In chapter 3, the key methodological limitations of previous studies examining the relationship between chronic sleep restriction and obesity were outlined. Methodological recommendations for future research were then provided to facilitate a more complete understanding of how chronic sleep restriction and obesity are linked in the general population. Chapter 4 tested a path model linking chronic sleep restriction to obesity in 325 adults aged 18 to 87 years, based on the theoretical framework provided in chapter 2 and the methodological recommendations listed in chapter 3. The results indicated that short sleep durations and age were associated with obesity, whilst age, uncomfortable sleep environments, irregular sleep/wake cycles and poor mental health were associated with short sleep durations. However, the results also identified potential environmental, behavioural and psychological determinants of chronic sleep restriction that could be targeted in the future treatment and prevention of obesity. Chapter 5 examined the relationship between three dimensions of sleep quality as assessed by the Pittsburgh Sleep Quality Index and obesity in 262 adults aged 18 to 35 years. Short sleep durations and increased levels of daytime dysfunction (e.g., sleepiness) were associated with obesity, whilst irregular bedtimes, noisy environments, discomfort and depression were the major factors associated with poor sleep quality. These factors could play a role in obesity interventions that target sleeping patterns and need to be further investigated. Finally, chapter 6 examined the effects of two nights of seep restriction on energy expenditure and neuroendocrine hormones involved in energy balance regulation in ten healthy male adults. The results indicated that sleep restriction led to an increase in ghrelin and a reduction in PYY, which corresponded with increased hunger and reduced satiety. The results also suggested that energy expenditure declined with sleep restriction. These results suggest that sleep restriction could contribute to obesity by altering energy expenditure and the hormonal regulation of food intake. The findings from this thesis therefore suggest that chronic sleep restriction contributes to the development of obesity by altering key pathways identified in chapter 2. The identification of possible determinants of chronic sleep restriction has potential applications for the treatment and prevention of obesity. For example, the factors identified in chapters 4 and 5 could be targeted as a way to promote healthy sleep durations, and could be effective in improving the efficacy of existing interventions for obesity.

This PhD thesis describes the effects of Vitamin D on skeletal muscle and includes details of two main research projects. The first study validated a physiologically significant effect of VitD3 in proliferation, differentiation, protein synthesis and mitochondrial metabolism in primary human skeletal muscle cells, in cell culture. The second study demonstrated that VitD3 supplementation does not result in additional benefits on muscle strength, power, resting metabolic rate and body composition in VitD sufficient physically active adults.

The properties of the mitochondrial F1FO-ATPase activated by the natural cofactor Mg2+ or by Ca2+, were studied, mainly on heart mitochondria from swine, widely used in translational medicine. The Ca2+ driven conformational changes in the F1FO-ATPase form the mitochondrial permeability transition pore (mPTP), which triggers regulated cell death and is involved in severe pathologies. The Ca2+-activated F1FO-ATPase hydrolyzes ATP with kinetics slightly different from those of the Mg2+-ATPase. Known F1-ATPase inhibitors inhibit both the Ca2+-activated F1FO-ATPase and the mPTP formation strengthening the molecular link between them. The different Gd3+ effects on the Ca2+- and Mg2+-activated F1FO-ATPases confirm their difference as also phenylglyoxal which preferentially inhibits the Ca2+-activated F1FO-ATPase. The effects of phenylarsine and dibromobimane, which interact with differently distant Cys thiols, show that mPTP opening is ruled by nearby or distant dithiols. Bergamot polyphenols and melatonin inhibit the mPTP and ROS formation. H2S, a known cardiovascular protector, unaffects the F1FO-ATPase, but inhibits Ca2+ absorption and indirectly the mPTP, both in swine heart and mussel midgut gland mitochondria. New generation triazoles inhibit the Ca2+-activated F1FO-ATPase and the mPTP, but unaffect the Mg2+-activated F1FOATPase. In parallel, the energy metabolism was investigated in mammalian cells. In boar sperm ATP is mainly produced by mitochondrial oxidative phosphorylation (OXPHOS), even if it decreases over time because of less active mitochondria. Insufficient ATP may induce sperm dysfunction. Also, canine mesenchymal stem cells rely on OXPHOS; those from umbilical cord which produce more ATP than those from adipose tissue, seem preferable for transplant studies. The intestinal porcine enterocyte cell line IPEC-J2, used for human gut research, responds to different fetal bovine serum concentrations by remodeling OXPHOS without altering the bioenergetic parameters. The IPEC-J2 bioenergetics is modulated by Vitamin K vitamers. These data shoulder cell bioenergetics as precious tool for medical research.

A identificação de novos alvos para controlar o processo inflamatório é, provavelmente, o principal desafio que dificulta o desenvolvimento de novas drogas anti-inflamatórias. Assim, a modulação das vias de sinalização intracelulares em fagócitos desponta como uma forma interessante de alcançar este objetivo. No entanto, isso pode trazer como consequência a diminuição da defesa do hospedeiro contra patógenos. Este estudo teve como objetivo examinar se o nitróxido 4-hidroxi-2,2,6,6-tetrametil-1-piperidiniloxi (Tempol) exerce efeito sobre produção de oxidantes por neutrófilos inflamatórios através da regulação da atividade de proteínas quinases e da proteína dissulfeto isomerase (PDI), uma chaperona cujos sítios ativos contêm o motivo Cys-Gly-His-Cys (CXXC) e está envolvida na montagem do complexo enzimático NADPH oxidase (Nox2) de fagócitos. Vias bioquímicas diferentes foram ativadas para a liberação de espécies reativas de oxigênio por neutrófilos inflamatórios, e, paralelamente, a atividade de proteínas quinases foi determinada sob efeito de Tempol nos fagócitos. O nitróxido inibiu significativamente o burst oxidativo dos neutrófilos de maneira dependente da concentração. Este efeito foi detectado pelo consumo de oxigênio, onde a IC50 encontrada foi de 45±4 μM. Utilizando-se ensaios de quimioluminescência dependente de luminol ou de isoluminol, mostramos que o Tempol provocou um atraso no período de resposta latente da ativação de Nox2 dos neutrófilos sob diferentes estímulos. Coerentemente, o nitróxido inibiu a atividade de proteínas quinases de neutrófilos estimuladas por diferentes vias bioquímicas, como quantificado por ensaios quimioluminescentes e por teste dot blot. Nas mesmas condições, Tempol reduziu a atividade fungicida de neutrófilos contra Candida albicans. Na presença de Tempol a atividade redutase de PDI foi reversivelmente afetada tanto in vitro como em neutrófilos inflamatórios estimulados, cuja IC50 de 35±3,3 μM foi calculada através de metodologia de espectrofluorescência. Esta atividade inibitória foi confirmada com o método espectrofotométrico de enovelamento de insulina. Foi utilizada PDI recombinante para ser estudado o mecanismo de inibição que o Tempol exerce sobre a esta tiol óxido-redutase, através de espectrometria de massa. Na análise da proteína total, 1 e 4 moléculas de Tempol foram detectadas ligadas à proteína. No entanto, somente uma molécula do nitróxido foi encontrada ligada covalentemente à PDI. Mais especificamente, a Cys400 foi modificada por Tempol. Em conjunto, os resultados revelam um novo mecanismo do Tempol sobre a regulação de enzimas associadas à atividade do complexo Nox2 de neutrófilos inflamatórios, os quais apresentam aplicações clínicas potenciais para intervenção terapêutica em processos patológicos. Entretanto, o possível uso do Tempol como agente anti-inflamatório deve ser cauteloso, uma vez que este nitróxido diminuiu a resposta microbicida de neutrófilos.
The identification of new targets for controlling inflammatory processes is, almost certainly, the major challenge that hampers the development of new anti-inflammatory drugs. Thus, the modulation of intracellular signaling pathways in phagocytes emerges as an interesting way to achieve this goal. However, this strategy can bring the effect of lowering the host defense against pathogens. This study aimed to examine whether the nitroxide 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy (Tempol) has an effect on production of oxidants by inflammatory neutrophils through regulation of protein kinase activity and protein disulfide isomerase (PDI), a chaperone whose active sites containing the motif Cys-Gly-His-Cys (CXXC) and is involved in the assembly of the NADPH oxidase enzyme complex (Nox2) on phagocytes. Different biochemical pathways were activated for the release of reactive oxygen species by inflammatory neutrophils, and, in parallel, the protein kinase activities were determined under Tempol treatment of phagocytes. The nitroxide significantly inhibited oxidative burst of neutrophils in a concentration dependent manner. This effect was detected by oxygen consumption, where the IC50 was found to be 45±4 µM. By means of chemiluminescence luminol- or isoluminol-dependent assay, we showed that Tempol caused a delay in the lag period of neutrophils Nox2 activation under different stimuli. Accordingly, the nitroxide inhibited the activity of protein kinases in neutrophils stimulated by various biochemical pathways, as quantitated by chemiluminescent assays and dot blot test. Under the same conditions, Tempol reduced neutrophil fungicidal activity against Candida albicans. In the presence of Tempol, PDI reductase activity was reversibly affected both in vitro and in stimulated inflammatory neutrophils, whose IC50 of 35±3.3 µM was calculated by fluorescent methodology. This inhibitory activity was confirmed by the spectrophotometric insulin method. Recombinant PDI was used for the purpose of studying the mechanism of inhibition that Tempol exerts on this thiol oxide reductase enzyme, by mass spectrometry. In the analysis of total protein, 1 and 4 molecules of Tempol were detected bound to the protein. However, only one molecule of the nitroxide was found covalently linked to PDI. More specifically, Cys400 has been changed by Tempol. Together, these results reveal a novel mechanism of Tempol on the regulation of enzymes associated with Nox2 complex inflammatory activity of neutrophils, which have potential clinical applications for therapeutic intervention in pathological processes. However, the promising use of Tempol as an anti-inflammatory agent must be taken with caution, since this nitroxide decreased neutrophil microbicidal response.

Blood flow distribution during forced and voluntary diving in ducks, and the energetic cost of diving was investigated. It has been suggested that in order for the leg muscles to generate enough power for ducks to dive, blood flow to those tissues must be maintained. A technique to determine blood flow distribution which could be used during voluntary diving was first developed and tested during forced laboratory dives of ducks. This technique was then used to determine the blood flow distribution during voluntary diving. Regional blood flow distribution was visualized by utilizing a radioactive tracer technique (macro aggregated albumin labelled with ⁹⁹ⅿ technetium). The tracer when injected into an animal is trapped and held by capillaries. During forced dives in dabbling (Anas platyrhynchos) and diving (Aythya affinis) ducks the blood flow distribution was found to be restricted to the thoracic and head areas. Whereas during a voluntary dive in A. affinis blood flow distribution was shown to be preferentially directed towards three tissue areas, the heart, brain, and active leg muscles. The work required to dive was determined from the measurement of subsurface drag forces and buoyancy in A. affinis. Subsurface drag increased as a nonlinear function of swimming velocity. At a velocity of 1 m•s⁻¹, the drag force was approximately 1.067 N. The average measured buoyant force of 11 ducks was 0.953 N. The calculated mechanical work done by ducks during a 14.4 s unrestrained dive was 9.34 J. The power output during voluntary was estimated to be 0.751 W (0.0374 ml 0₂•s⁻¹). During diving buoyancy is clearly the dominant force (8.8 J) against which ducks have to work while drag (0.54 J) adds little (~6%) to the energetic cost of diving.
Science, Faculty of
Zoology, Department of
Graduate

Obesity and type 2 diabetes mellitus (T2DM) are both complex diseases with multifactorial etiologies. Together they affect over 640 million people worldwide and have a significant impact on the global healthcare system incurring costs of over 800 billion dollars. The overall goal of my doctoral research has been to elucidate metabolic predictors and underlying mechanisms in obesity and T2DM. Specifically, I have examined mechanisms contributing to disordered oxidative metabolism in skeletal muscle. My research included participants who were recruited from the Ottawa Hospital Weight Management Clinic in which they completed a clinically supervised meal-replacement and lifestyle intervention program. More so, my doctoral studies evaluated characteristics of muscle mitochondrial function in obesity and T2DM and revealed impaired mitochondrial respiration and electron transport chain supercomplex assembly in muscle from patients with T2DM. The first aim was to study the impact of T2DM on weight loss ability in a large population of obese patients participating in a standardized meal replacement and lifestyle modification program. As there is considerable variability in weight loss propensity, it was found that T2DM significantly deters weight loss although the effect is not large. Since skeletal muscle energetics are central in the development and progression of obesity and T2DM, the second and third aims were to study mitochondrial function in this tissue with the idea of uncovering molecular etiologies. The second aim found deficiencies in mitochondrial respiration in individuals with obesity and T2DM compared to individuals with obesity alone. Reductions in mitochondrial respiration were correlated with increasing levels of HbA1C and attributed to paucity in supercomplex formation in the mitochondrial inner membrane (MIM) of the electron transport chain (ETC). The third aim was to delineate differential fuel oxidation mechanisms and circulating protein biomarkers in obese diet-sensitive (ODS) and obese diet-resistant (ODR) participants following a high fat meal (HFM) challenge. Whole-body analyses were conducted in addition to measures in blood, adipose tissue, skeletal muscle and primary cells. Remarkable increases in oxidative capacity were measured post-HFM. In addition, impaired mitochondrial function was found in the ODR group despite lack of differences in mitochondrial content or the assembly of supercomplexes. Differences were also found in circulating acylcarnitines as well as expression of several proteins including Heat shock 70 kDa protein 1A/1B, Tyrosine-protein kinase Fgr, and Peptidyl-prolyl cis-trans isomerase D. Ultimately, a better understanding of mechanisms involved could lead to significant improvements in personalized medical approaches in obesity and T2DM.

El sobrepeso y la obesidad son condiciones patológicas, con una prevalencia elevada, que están consideradas como una de las principales causas de mortalidad. Los factores genéticos, y especialmente, los factores ambientales y los estilos de vida son determinantes para su desarrollo. Existen varias patologías asociadas a la obesidad como la resistencia a la acción de la insulina, la hipertensión, la hiperlipidemia y las enfermedades cardiovasculares, que son las principales comorbilidades del síndrome metabólico. A lo largo de las décadas se han desarrollado infinidad de estudios enfocados en la prevención y el tratamiento de la obesidad y sus complicaciones, la mayoría de ellos relacionados con el control del peso a través de la intervención nutricional, que se basa principalmente en la modificación de la proporción de los macronutrientes de la dieta. Sin embargo, dichas modificaciones conllevan adaptaciones metabólicas que, con la tentativa de mantener la homeostasis en el organismo, pueden comprometer algunas funciones biológicas. En la presente Tesis, se han estudiado algunas de las adaptaciones metabólicas que se producen tras aplicar una intervención nutricional con cuatro dietas distintas durante un mes. La intervención se realizó en ratas Wistar hembra y macho de 10 semanas de edad. Las dietas utilizadas diferían en la proporción y/o la composición de macronutrientes, y a la vez, fueron comparables entre sí al estar ajustadas al resto de componentes. Los resultados obtenidos en relación a la medida de la glucemia indican que las lecturas de glucosa estarían sujetas a una infraestimación sistemática, pudiendo comprometer los criterios diagnósticos. Las medidas de glucemia y glucosilación obtenidas apuntan a una influencia de la dieta sobre la proporción anomérica de la glucosa, y a diferencias en la compartimentación de la glucosa sanguínea; por ello, se sugiere la medida de la glucosilación de las proteínas de membrana de los eritrocitos (debido a su contacto continuado con la glucosa del plasma) como mejor indicador del desarrollo de la hiperglucemia. En relación a los efectos obesogénicos de la dieta, parece que las consecuencias metabólicas no vienen dadas únicamente por un exceso de nutrientes de la dieta sino también por un desequilibrio en su proporción. Se ha observado que la ingesta de componentes sabrosos (dulce/salado) junto con la textura que aporta el lípido, son los principales responsables de la inducción de hiperfagia y el desarrollo de obesidad. La relación lípido / proteína de la dieta influye positivamente en la acumulación de lípido ectópico, siendo esta también diferente entre sexos. Por otro lado, la composición lipídica de la dieta generó efectos importantes en el metabolismo de carbohidratos y de lípidos, que parecen estar mediados por el estradiol. Respecto al metabolismo nitrogenado, la relación energía / proteína de la dieta parece tener un papel clave en la regulación del ciclo de la urea hepático. Ante un exceso energético y proteico simultáneo proveniente de la dieta, el funcionamiento del ciclo y la producción de urea se ven comprometidos, dificultando la excreción de nitrógeno amínico. Por otro lado, la capacidad del tejido adiposo marrón para contribuir a la eliminación de nitrógeno amínico está limitada debido a la presencia parcial del ciclo de la urea, que parece estar relacionado con la síntesis de arginina. Estos hallazgos refuerzan las hipótesis relacionadas con la existencia de mecanismos alternativos para eliminar un superávit de nitrógeno amínico.
Overweight and obesity are pathologic conditions with a high prevalence, and are considered as one of the leading risks for global deaths. Genetic factors, and especially, environmental factors and lifestyle habits are crucial for their development. There are several obesity- associated pathologies, as insulin resistance, hypertension, cardiovascular disease and hiperlipidemia, which are the main comorbidities of Metabolic Syndrome. Over the decades several approaches have been carried out for the prevention and treatment of obesity and its complications. Most of them are related to weight control through nutritional intervention, which is mainly based on macronutrient’s proportion modifications. However, these modifications involve metabolic adaptations for homeostasis maintenance that can compromise some biological functions. Some of those metabolic adaptations have been studied by carrying out a one-month nutritional intervention with four different diets. It has been performed in 10-week old female and male Wistar rats. The diets used differed in macronutrients proportion or composition, and were comparable to each other since the rest of the components were adjusted. The results obtained in relation to glycaemia measurement suggest the existence of a systematic underestimation of glucose readings, which could be compromising the diagnostic criteria. The obtained glycaemia and glycosylation measurements point to an influence of the diet on glucose anomer proportion and to a different blood glucose compartmentalization, suggesting the measurement of red blood cell membrane protein glycosylation (due to its sustained exposure to glucose) as better marker of hyperglycaemia development. Regarding diet obesogenic effects, it seems that the metabolic consequences are not only given by an excess of nutrients from the diet but also by an imbalance in their proportion. It has been observed that the intake of tasty components (sweet / salty) together with lipid texture, are the main responsible factors for hyperphagia induction and obesity development. The lipid / protein ratio of the diets positively influences the accumulation of ectopic lipid, which also exhibited sex-related differences. On the other hand, the lipid composition of the diet promoted important effects on carbohydrate and lipid metabolism, which seemed to be mediated by oestradiol. In relation to nitrogen metabolism, the energy / protein ratio of the diet seems to play a key role in liver urea cycle regulation. When high amounts of energy and protein simultaneously come from the diet, the operation of urea cycle, and so the excretion of nitrogen as urea, is compromised. Furthermore, the capacity of brown adipose tissue to contribute to the nitrogen excess elimination is limited due to its partial urea cycle presence, which may be more related to arginine synthesis. These findings reinforce the hypotheses related to the existence of alternative mechanisms to eliminate the nitrogen surplus.

Os modelos de evolução de vias metabólicas estão baseados em técnicas moleculares e bioinformática e nem sempre levam em consideração o contextos fisiológico e ecológico do organismo. Assim, tomando como plataforma o metabolismo de nitrogênio, procurou-se estabelecer uma hipótese evolutiva para o uso de α-aminoácidos por metazoários como fonte de nitrogênio. O objetivo é traçar essa história evolutiva, contextualizando fisiológica e ecologicamente as alterações que ocorreram no perfil de utilização desses compostos. Para traçar essa história evolutiva, recorreu-se a dados disponíveis na literatura partindo-se dos elementos moleculares/metabólicos que compõem o ciclo do nitrogênio e em qual contexto geológico e evolutivo se deu tal história. Os dados obtidos, reorganizados e reestruturados nesse novo contexto, permitiram conclusões originais no presente trabalho, a saber: (1) a capacidade de fixação de nitrogênio atmosférico foi um fator de seleção natural positiva na transição da atmosfera redutora para oxidante; (2) os organismos fixadores de nitrogênio são bem mais disseminados do que o admitido classicamente; (3) o produto final da fixação biológica de nitrogênio in vivo são α- aminoácidos, e foram um fator de pressão seletiva para os organismos incapazes de fixar nitrogênio; (4) os metazoários evoluíram posteriormente a esse cenário e seu aparato metabólico está mais adaptado para o aproveitamento líquido do nitrogênio obtido apenas na forma de α-aminoácidos.
Metabolic pathway evolution models are molecular and computational based, and do not take account the physiological and ecological contexts in which organisms are inserted. Thus using the nitrogen metabolism as a platform, an evolutionary hypothesis on the α-amino acids utilization by metazoans was proposed. The objective of the present work is to trace an evolutionary history of the nitrogen usage by metazoans taking account the profile changes on a physiological and ecological basis. In order to trace this evolutionary history, a scrutiny were performed in the specialized literature aiming at data about the molecular and metabolic elements which perform the nitrogen cycle and in which geologic and evolutive context has passed such history. The reorganization of obtained data in a new context allowed original conclusions in the present work as follows: (1) the capability of fixing the atmospheric nitrogen was a positive selection factor in the atmospheric condition transition from reductive to oxidant; (2) nitrogen fixing organisms are far most wide spread than classically admitted; (3) α-amino acids are the biological nitrogen fixation end product in vivo, and are a selective factor for non-fixing organisms; (4) metazoans evolved afterwards in these scenario and their metabolic apparatus is adapted to the nitrogen net utilization obtained in the α-amino acid form.

Diabetes mellitus affects more than 382 million people worldwide and an estimated 30-50% of patients develop some form of neuropathy. Patients typically present with sensory symptoms including hypersensitivity/pain and/or loss of somatosensation. In diabetic neuropathy, the longest nerves of the peripheral nervous system (PNS) show the worst pathology and symptoms are typically felt in the distal extremities. The cause of this apparent length-dependent pathology remains unknown. Through comprehensive integration of untargeted proteomic and metabolomic analyses of the PNS in the streptozotocin rat model of diabetes, we showed that bioenergetic pathways were more dysfunctional in the distal sciatic nerve (SN) than the lumbar 4/5 dorsal root ganglia (DRG) and cranial trigeminal ganglia (TG). Whilst glucose levels increased in all tissues in diabetes, there was extensive upregulation of proteins involved in mitochondrial oxidative phosphorylation in the distal SN compared to healthy age/weight-matched controls which was not evident in the proximal DRG or TG. There were significant changes in lipid metabolites in the SN, a phenomenon which is less apparent in the DRG and not evident in the TG. We investigated the therapeutic potential of copper chelation with triethylenetetramine to reverse such changes and whilst copper chelation prevented nerve conduction velocity deficits, it did not alter aberrant nerve metabolism. To further understand the functional deficits in diabetic neuropathy, we performed in vivo microelectrode recordings from the TG and the thalamic ventral posteromedial (VPM) nucleus in control and diabetic rats in response to precise whisker stimulation. Recordings from the TG showed that the tuning of the primary afferents to graded stimuli is preserved in diabetes. Furthermore, we found that neurons within the VPM showed increased spontaneous activity in diabetes, but maintained tuning to graded whisker stimulation in their evoked firing rate. Thus, the cranial TG appear to be relatively unaffected by diabetes at a biochemical or physiological level, but diabetes may lead to pathophysiological changes within the thalamus which could alter somatosensory processing. Despite a global metabolic insult in diabetes, the molecular consequences are not consistent throughout the nervous system. We show that metabolic dysfunction occurs specifically in regions known to be more affected in neuropathy. Due to such a focal dysfunction, aberrant oxidative phosphorylation in the sciatic nerve may be a key driver to the distal pathogenesis of diabetic neuropathy.

Cancer cells have been known for some time to have very different metabolismas compared to that of normal non proliferating cells. As metabolism is involvedin almost every aspect of cell function, there has been a recent resurgence ofinterest in inhibiting cancer metabolism as a therapeutic strategy. Inhibitors thatspecifically target altered metabolic components in cancer cells are being developedas antiproliferative agents. However, many such inhibitors have not progressedinto the clinic due to limited efficacy either in vitro or in vivo. In this study weexplore the hypothesis that this is often due to the robustness of the metabolicnetwork and the differences between individual cancer cell lines in their metaboliccharacteristics. We take a systems biology approach. We investigate the cellular bioenergetic profiles of a panel of five non-small celllung cancer cell lines before and after treatment with a novel inhibitor of theglutaminase-1 (GLS1) enzyme. Additionally, we explore the effects of this inhibitoron intracellular metabolism of these cell lines as well as on the uptake and secretionof glucose, lactate and amino acids. To be able to do the latter robustly, wehad to modify the experimental assay considerably from procedures that seemto be standard in the literature; using these earlier procedures the metabolicenvironment of the cells was highly variable, leading to misleading results onthe metabolic effects of the inhibitor. We reduced cell density, altered mediumvolume and changed the time-window of the assay. This led to the cells growingexponentially, appearing indifferent to the few remaining changes. In this newassay, the metabolic effects of the glutaminase inhibitor became robust. One of the most significant results of this study is the metabolic heterogeneitydisplayed across the cell line panel under basal conditions. Differences in themetabolic functioning of the cell lines were observed in terms of both theirbioenergetic and metabolic profile. The amount of respiration attributed tooxidative phosphorylation differed between cell lines and respiratory capacity wasattenuated in most cells. However, the rate of glycolysis was similar betweencell lines in this assay. These results suggest that the Warburg effect arisesthrough a greater diversity of mechanisms than traditionally assumed, involvingvarious combinations of changes in the expression of glycolytic and mitochondrialmetabolic enzymes. The effects of GLS1 inhibition on cellular bioenergetics and metabolism alsodiffered between cell lines, even between resistant cell lines, indicating that theremay also be a diversity of resistance mechanisms. The metabolomic response ofcell lines to treatment suggests potential resistance mechanisms through metabolicadaptation or through the prior differences in the metabolic function of resistantcell lines. Part of the metabolome response to GLS1 inhibition was quite specificfor sensitive cells, with high concentrations of IMP as the strongest marker. Our results suggest that the metabolome is a significant player in what determinesthe response of cells to metabolic inhibitors, that its responses differ between cancercells, that responses are not beyond systems understanding, and that thereforethe metabolome should be taken into account in the design of and therapy withanti-cancer drugs.

IF1, the endogenous inhibitor protein of mitochondrial F1Fo-ATPase, has raised interest in cancer research due to its overexpression in solid tumours compared to normal tissues. Physiologically, IF1 protects cells from energy depletion by limiting the ATP hydrolytic activity of ATP synthase triggered by mitochondrial depolarization caused by oxygen deficiency as it occurs during ischemic episodes. Considering both the physiological function of IF1 and that cancer cells in solid tumour are frequently exposed to oxygen deprivation, we hypothesized that IF1 overexpression represents a strategy that cancer cells develop to protect themselves from energy depletion under conditions of low oxygen availability. To assess this, we assayed the bioenergetic changes in 143B and HCT116 cancer cells with different metabolic features following stable silencing of IF1. Interestingly, we found that in both cell lines exposed to oxygen deprivation conditions the presence of IF1 limits the energy dissipation due to the activation of the ATP hydrolytic activity of ATP synthase. Furthermore, the analyses of cellular growth and viability revealed that the IF1 silencing inhibited proliferation in the highly glycolytic 143B cells, while it induced more than 50% of cellular death in HCT116 OXPHOS-dependent cells, indicating that the energetic advantage conferred by IF1 is essential for cancer cell proliferation or survival depending on the energy metabolism of each cell line. Moreover, under mitochondrial depolarization conditions, both mitophagy and mitochondrial biogenesis markers were found up-regulated in IF1-expressing cells only, thus indicating a continuous renewal and preservation of the mitochondrial mass. Taken together, our results sustain the idea that IF1 overexpression supports cancer cell adaptation to hypoxic or anoxic conditions also favouring the proliferation of re-oxygenated cells by promptly providing functional mitochondria.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Estudos demostram que a hiperalimentação no período pós-natal causa obesidade, alterações cardiometabólicas e resistência à insulina em longo prazo. O objetivo do estudo foi investigar as consequências da hiperalimentação na lactação nos corações de camundongos filhotes e adultos ao longo do desenvolvimento. Para induzir a hiperalimentação na lactação, o tamanho da ninhada foi reduzida a 3 filhotes machos no terceiro dia, grupo hiperalimentado (GH). O grupo controle (GC) permaneceu com 9 filhotes da lactação ao desmame. Avaliamos a massa corporal, gordura epididimária e retroperitoneal, morfologia hepática e cardíaca, ultraestrutura dos cardiomiócitos, peso do PVE/CT, glicemia de jejum, triglicerídeos, colesterol total, insulina plasmática e HOMA-IR. Analisamos o consumo de oxigênio das fibras cardíacas através da respirometria de alta resolução, atividade enzimática da PDH, CS e LDH no coração e glicogênio hepático. Biologia molecular, através das proteínas: IRβ, IRS1, pIRS1, PTP1B, PI3K, Akt, pAkt, GLUT1, GLUT4, AMPKα, pAMPKα, HKII, CPT1, UCP2, FABPm, CD36, PGC-1α, PPARα, 4HNE, complexos da CTE (I, II, III, IV e V), α-tubulina, GP91 e VADC. Diferenças entre os grupos analisadas por Two-Way ANOVA, com significância p<0,05. O GH apresentou aumento da massa corporal, gordura epididimária, retroperitoneal e colesterol total em todas as idades; glicemia de jejum, insulina, índice de HOMA-IR e triglicerídeos aos 21 e 90 dias. Aumento do índice de Lee aos 60 e 90 dias. GH apresentou diminuição: do IRβ e GLUT4 aos 21 e 60 dias; aumento do IRβ aos 90 dias; aumento do IRS1, PTP1B, aos 21 e 90 dias e da AKT, pAMPK/AMPK e GLUT1 aos 21 dias; diminuição da pIRS1/IRS1, PI3K, pAKT/AKT aos 21 e 90 dias; diminuição da HKII aos 21 dias e aumento aos 60 e 90 dias; aumento da PDH aos 90 dias; aumento da LDH aos 21 dias e redução aos 60 dias; aumento da CS aos 21 dias e diminuição aos 60 e 90 dias; aumento da oxidação de carboidratos aos 21 dias e redução aos 90 dias; diminuição na oxidação de ácidos graxos aos 60 e 90 dias. Adicionalmente, aumento do desacoplamento mitocondrial entre a fosforilação oxidativa e a síntese de ATP aos 60 e 90 dias. Diminuição da CPT1 e aumento da UCP2 aos 21 e 90 dias. Diminuição da PGC-1α aos 60 e 90 dias; da FABPm e CD36 em todas idades. Aumento da 4HNE aos 21 e diminuição aos 90 dias. Diminuição na expressão do mRNA para CPT1 aos 21, 60 dias. Diminuição na expressão do mRNA para PPARα e aumento na expressão do mRNA para UCP2 aos 21 dias; diminuição na expressão do mRNA para UCP2 ao 60 dias. Alterações morfológicas cardíacas e hepáticas, assim como na ultraestrutura dos cardiomiócitos, em todas as idades, maior conteúdo de glicogênio hepático aos 21 e 90 dias. Concluímos que a hiperalimentação na lactação levou à obesidade, com aumento da oxidação de glicose, alterações no metabolismo energético associadas à diminuição da sensibilidade à insulina, redução da capacidade oxidativa mitocondrial, levando ao desacoplamento e alteração da morfologia e ultraestrutura dos cardiomiócitos do desmame até a idade adulta.
Recent studies have shown that overnutrition in the postnatal period lead obesity, cardiometabolic alterations, insulin resistance at long term. The objective of the study was to investigate the consequences of overnutrition lactation in the hearts of mice pups and adults throughout the development. To induce overnutrition during lactation, the litter size was reduced from three male pups at the third day, overnutrition group (OG). The control group (CG) remained with 9 pups per litter at lactation until weaning. We evaluated the body weight, epididymal and retroperitoneal fat, liver and cardiac morphology, ultrastructure of cardiomyocytes, left ventricle weight/ tibia length ratio, fasting glucose, triglycerides, total cholesterol, plasma insulin and HOMA-IR. The oxygen consumption of cardiac fibers was analyzed by high-resolution respirometry. We evaluated the enzymatic activity of PDH, CS and LDH and liver glycogen. Molecular biology, through: IRβ, IRS1, pIRS1, PTP1B, PI3K, Akt, pAkt, GLUT1, GLUT4, AMPKα, pAMPKα, HKII, CPT1, UCP2, FABPm, CD36, PGC-1α, PPARα, 4HNE, eletrons transport chain complex (I, II, III, IV and V), α-tubulin, GP91 and VADC. Differences between groups analyzed by Two-way ANOVA, significance level p <0.05. The OG had increased body weight, epididymal and retroperitoneal fat and total cholesterol in all ages. Fasting glucose, insulin, HOMA-IR and triglyceride levels at 21 and 90 days. Increased Lee index at 60 and 90 days. OG showed a decrease: the IRβ and GLUT4 at 21 and 60 days; IRβ increased to 90 days; increased IRS1, PTP1B, at 21 and 90 days and AKT, pAMPK/ AMPK and GLUT1 to 21 days; decrease of pIRS1/IRS1, PI3K, pAKT/ AKT at 21 and 90 days; HKII decreased at 21 days and increased at 60 and 90 days; PDH increased to 90 days; increased LDH at 21 days and reduced to 60 days; CS increased at 21 days and decreased at 60 and 90 days; increased oxidation of carbohydrates to 21 days and reduced to 90 days; decrease in fatty acid oxidation at 60 and 90 days. Additionally, increased mitochondrial uncoupling oxidative phosphorylation and ATP synthesis at 60 and 90 days. We observed decrease in CPT1 and increased UCP2 at 21 and 90 days. Decreased PGC-1α at 60 and 90 days and FABPm and CD36 in all ages. increased 4HNE at 21 and decrease at 90 days. However, we observed a decrease in the expression of mRNA for CPT1 to 21 and 60 days. Decrease in mRNA expression of PPARα and increased in mRNA expression of UCP2 at 21 days; decrease in mRNA expression of UCP2 at 60 days. Heart and liver morphological changes, as well as the ultrastructure of cardiomyocytes, in all ages, hepatic glycogen content at 21 and 90 days. We conclude that the overfeeding lactation led to obesity with increased glucose oxidation, changes in energy metabolism, associated with decreased insulin signaling, reduced mitochondrial oxidative capacity, leading to decoupling and changing the morphology and ultrastructure of cardiomyocytes from weaning to adulthood.

Submitted by Cleide Dantas (cleidedantas@ufpa.br) on 2014-04-15T16:28:42Z No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_AvaliacaoQualidadeVida.pdf: 947352 bytes, checksum: 5ee5e6cbf12e59a1ac5d4c59855706d5 (MD5)
Approved for entry into archive by Ana Rosa Silva (arosa@ufpa.br) on 2014-04-30T16:56:24Z (GMT) No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_AvaliacaoQualidadeVida.pdf: 947352 bytes, checksum: 5ee5e6cbf12e59a1ac5d4c59855706d5 (MD5)
Made available in DSpace on 2014-04-30T16:56:25Z (GMT). No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_AvaliacaoQualidadeVida.pdf: 947352 bytes, checksum: 5ee5e6cbf12e59a1ac5d4c59855706d5 (MD5) Previous issue date: 2013
O Diabetes Mellitus tipo 1 (DM1) é a endocrinopatia mais comum da infância e adolescência e impacta negativamente na qualidade de vida (QV). O EuroQol é um instrumento que afere o estado de saúde e vem sendo utilizado na grande maioria dos estudos multicêntricos mundiais em diabetes e tem se mostrado uma ferramenta extremamente útil e confiável. O objetivo desse estudo é avaliar a QV de pacientes com DM1 do Brasil, país de proporções continentais, por meio da análise do EuroQol. Para isso, realizou-se estudo retrospectivo e transversal, no qual foram analisados questionários de pacientes com DM1, respondidos no período de dezembro de 2008 a dezembro de 2010, em 28 centros de pesquisa de 20 cidades das quatro regiões do país (sudeste, norte/nordeste, sul e centro-oeste). Foram também coletados dados sobre complicações crônicas micro e macrovasculares e perfil lipídico. A avaliação da qualidade de vida pelo EuroQol mostra que a nota média atribuída ao estado geral de saúde é nitidamente menor que a encontrada em dois outros estudos populacionais com DM1 realizados na Europa (EQ-VAS da Alemanha, Holanda e Brasil foram de 82,1 ± 14; 81 ± 15 e 72 ± 22, respectivamente). O EuroQol demonstra que a região Norte-Nordeste apresenta melhor índice na avaliação do estado geral de saúde quando comparada a região Sudeste e menor frequência de ansiedade-depressão autorreferidas, quando comparada às demais regiões do país (Norte-Nordeste = 1,53 ± 0,6, Sudeste = 1,65 ± 0,7, Sul = 1,72 ± 0,7 e Centro-Oeste = 1,67 ± 0,7; p <0,05). Adicionalmente, diversas variáveis conhecidas (idade, duração do DM, prática de atividade física, HbA1c, glicemia de jejum e presença de complicações crônicas se correlacionaram com a QV (r = -0,1, p <0,05; r = -0,1, p <0,05; r = -0,1, p <0,05; r = -0,2, p <0,05; r = -0,1, p <0,05 e r= -0,1, p <0,05, respectivamente). Esse é o primeiro estudo a avaliar a qualidade de vida de pacientes com DM1 a nível populacional no hemisfério sul. Nossos dados indicam uma pior qualidade de vida dos pacientes com DM 1 no Brasil quando comparado a dados de países europeus. Apesar de ter sido encontrado uma inferior duração do DM e menor presença de complicações microvasculares na região Norte/ Nordeste, quando comparada à outras regiões, nossos dados sugerem a existência de elementos adicionais responsáveis pela melhor QV e menor presença de ansiedade/depressão encontradas nesta região. Novos estudos são necessários para identificar esses possíveis fatores.
The type 1 diabetes mellitus type 1 (T1DM) is the most common endocrine disease of childhood and adolescence and it negatively impacts the quality of life (QOL). The EuroQol is an instrument that assess the health state. It has been used in most global multicenter studies in diabetes and it has been shown to be an extremely useful and reliable tool. The aim of this study is to evaluate the QOL of patients with T1DM in Brazil, a country of continental proportions, by analyzing the EuroQol. For this purpose, we performed a retrospective and cross-sectional study, which analyzed questionnaires from patients with T1DM, answered in the period of December 2008 to December 2010 in 28 research centers in 20 cities of the four regions (Southeast, North-Northeast, South and Midwest). We also collected data about chronic micro and macrovascular complications and lipid profile. The assessment of quality of life by EuroQol shows that the average score assigned to general health is markedly lower than those found in two other T1DM population studies conducted in Europe (EQ – VAS from Germany, Netherlands and Brazil were 82.1 ± 14, 81 ± 15 and 72 ± 22, respectively). The EuroQol shows that the North-Northeast region has the best index in the assessment of the overall health status compared to the Southeast and lower frequency of self-reported anxiety -depression, compared to other regions of the country (North-Northeast = 1.53 ± 0.6, Southeast = 1.65 ± 0.7, South = 1.72 ± 0.7 and Midwest = 1.67 ± 0.7, p <0.05). Additionally, several known variables (age, duration of diabetes, physical activity, HbA1c, fasting glucose, and presence of chronic complications correlated with QOL (r = -0.1, p <0.05, r = -0.1, p <0.05, r = -0.1, p <0.05, r = -0.2, p <0.05, r = -0.1, p <0.05 and r = -0.1, p <0.05, respectively). This is the first population study to evaluate the quality of life of patients with type 1 diabetes in the south hemisphere. Our data indicates poorer quality of life of patients with T1DM in Brazil when compared to data from European countries. Although we found an inferior diabetes duration and lower presence of microvascular complications in the North -Northeast region compared to other regions, our data suggests the existence of additional factors responsible for better QOL and lower presence of anxiety-depression found in this region. More studies are necessary to identify these possible factors.

Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro
O Trypanosoma cruzi é o agente etiológico da doença de Chagas, transmitida através de insetos vetores triatomíneos durante a alimentação no hospedeiro vertebrado. Os triatomíneos ingerem numa única alimentação cerca de 10 mM de heme ligado à hemoglobina. O heme é uma importante molécula no metabolismo dos organismos. Um mecanismo intracelular importante no controle de sua homeostase é a degradação enzimática pela Heme Oxigenase (HO) formando biliverdina (Bv), monóxido de carbono e ferro. Como esta enzima não está presente no genoma de T. cruzi, esse trabalho tem por objetivo identificar uma atividade funcional de HO neste parasito, uma vez que dados do nosso laboratório mostram a presença de biliverdina nas incubações dessas células com heme. No presente trabalho testamos o efeito do SnPPIX (inibidor da HO-1), CoPPIX (indutor da HO-1) e Bv sobre a proliferação da forma epimastigota do parasito. A adição de SnPPIX diminuiu a proliferação do parasito na tanto na ausência quanto na presença de heme. Quando a Bv foi adicionada à cultura esse efeito foi revertido; a Bv aumenta a proliferação celular na presença de heme. Por outro lado, a adição de CoPPIX não interferiu na proliferação. Posteriormente, mostramos através da técnica de immunoblotting, utilizando anticorpo monoclonal contra a HO-1, um aumento da expressão de uma proteína em resposta ao heme. Diferentemente das HO-1 já descritas que possuem massa molecular de 32 kDa, a única banda reconhecida pelo anticorpo apresenta 45 kDa. Analisamos também a expressão da HO-1 na presença de CoPPIX, SnPPIX e biliverdina, e somente o CoPPIX foi capaz de modular os níveis de expressão da HO-1. A análise estrutural através da técnica de imunocitoquímica mostrou uma maior expressão da enzima na presença de heme, e que a HO-1 de T. cruzi pode ter mais de uma localização, apresentando marcação citoplasmática e glicossomal. A fim de investigar a sequência da HO-1 de T. cruzi, o DNA genômico foi extraído para amplificação por PCR do gene da HO-1 utilizando oligonucleotídeos desenhados no genoma de T. cruzi. Os dois pares de oligonucleotídeos utilizados nao foram capazes de amplificar uma sequência equivalente a uma HO. Em seguida, utilizamos a técnica de imunoprecipitação, seguida de immunoblotting, com anticorpo anti-HO-1, com objetivo de concentrar a proteína alvo, e observamos um aumento significativo do imunocomplexo nas células tratadas com heme 300 mM, cerca de 2 vezes em relação ao controle. Dando seguimento à tentativa de identificação da HO-1 de T. cruzi, utilizamos a técnica de espectrometria de massa a partir de eletroforese unidimensional, que mostrou uma grande alteração do perfil protéico na presença de heme, mas futuros experimentos são necessários, como eletroforese 2D, para a identificação da proteína alvo
Trypanosoma cruzi, the ethiologic agent of Chagas disease, is transmitted through triatomine vectors during their blood-meal on vertebrate host. These hematophagous insects ingest blood about 6 to 12 times its original weight, reaching in a single meal about 10 mM heme bound to hemoglobin. Heme (iron protoporphyrin IX) is an important molecule in metabolism of all living organisms. One important intracellular mechanism to control heme homeostasis is its enzymatic degradation by heme oxygenase (HO). HO catalyzes the degradation of heme to biliverdin (Bv), carbon monoxide and iron. HO is absent in T. cruzi genome, thus we have been investigating the presence of a functional HO in this parasite, since our previous results showed a presence of biliverdin in heme-treated epimastigotes. In the present work, we evaluated the effect of SnPPIX, a HO-1 inhibitor, CoPPIX, a HO inducer, and Bv upon T. cruzi epimastigotes proliferation. The addition of SnPPIX decreased the parasite proliferation in the absence or in the presence of heme. When Bv was added to the culture this effect was reversed; Bv increases the parasite proliferation in the presence of heme. On the other hand, CoPPIX did not interfered on proliferation. Furthermore, we showed through immunoblotting, using an anti-HO-1 monoclonal antibody, an increase in the protein expression in heme-treated epimastigotes. Differently of described HO-1 that has a mass molecular of a 32 kDa, we showed a 45 kDa protein, the only band recognize by the HO-1 antibody. HO-1 expression analysis in the presence of CoPPIX, SnPPIX and biliverdin, showed that only CoPPIX was able to modulate its expression level. Ultrastructural immunocytochemistry analysis suggests a higher expression of the enzyme in heme-treated epimastigotes, and that T. cruzi HO-1 might have a dual distribution, since the anti-HO-1 antibody labeled both cytosol and glycosomes. In order to investigate the T. cruzi HO-1 gene sequence, we isolated genomic DNA from T. cruzi for PCR amplification using primers designed as from the parasite genome. Unfortunately, the two pairs of the designed oligonucleotides tested were unable to amplify a sequence equivalent to a HO-1. In order to isolate the target protein, immunoprecipitation was performed and subsequently immunoblotted with anti-HO-1 antibody. The immunocomplex level was two-fold higher in heme-treated cells. Following the attempt to identify a HO-1 in T. cruzi, we used mass spectrometry from unidimensional electrophoresis. We showed a significant protein profile modification in heme-treated epimastigotes, but further experiments will be necessary, such as mass spectrometry from bidimensional electrophoresis, for identification of the target protein

Made available in DSpace on 2014-08-20T13:32:56Z (GMT). No. of bitstreams: 1 dissertacao_tatiane_lotufo_leite.pdf: 2051891 bytes, checksum: e4c441e2609b224ad75ff5b6b7b0d609 (MD5) Previous issue date: 2010-11-22
The growing demand for energy and attempt to replace the energy matrix based on fossil fuels causes exist multiple searches in the search for alternative fuels. Hydrogen gas, which has potential energy 2.5 times larger than any hydrocarbon, and when burned releases only water, being their combustion free greenhouse gas potentializing. Several processes have been used for the production of biohydrogen. Of these processes is based on anaerobic degradation of waste, especially rich in carbohydrates. The parboiling is a process hydrothermal treatment of rice in the husk, which aims to improve the nutritional quality of the product. The rice parboiling generates approximately 4 L of effluent per kilogram of rice. This effluent presents a high content of organic substances and nutrients such as nitrogen and phosphorus, showing significant concentrations of carbohydrates also. The potential of hydrogen production from the effluent of parboiling rice was tested on reactors with anaerobic sludge of UASB heat-treated with sludge acidogenic hydrogen producer. Also studied the need for addition of nutrients to effluent parboiled for hydrogen production. The pH of the experiment was kept 5.5 to avoid growth of arquea metanogenic, that consume hydrogen. The temperature of the reactor was maintained at 20 ± 5 ºC. The experiment was mounted in batch of 48 hours, using sucrose as substrate control. The effluent from parboiled rice presents an average concentration of COD gross 4988.6 mg L-1 and carbohydrate 1030.0 mg L-1. Of the UASB anaerobic sludge heat-treated produced hydrogen with maximum rate of 62, 3 mL. g-1 COD removed, while the slime acidogenic produced 217.5 mL g-1 COD removed. The acidogenic reactor fed with effluent from parboiling presented removing 32.9% COD and 77.8% carbohydrates. Maximum production of hydrogen from the effluent was 9, 61 mL. Hydrogen gas production per gram of SSV in acidogenic reactor fed with sucrose was superior to reactor fed with effluent from parboiling. Reactors with three different gradients of addition of nutrients have been tested, showing that the hydrogen production was not significantly increased with increasing concentration of nutrient solution, indicating that the effluent from parboiling has potential for hydrogen production by anaerobic processes without the need for addition of nutrients tested.
A crescente demanda por energia e a tentativa de substituir a matriz energética baseada nos combustíveis fósseis faz com que existam várias pesquisas na busca de combustíveis alternativos. O gás hidrogênio, que possui potencial energético 2,5 vezes maior que qualquer hidrocarboneto, e que quando queimado libera somente água, sendo sua combustão livre de gases potencializadores do efeito estufa. Vários processos têm sido utilizados para a produção de biohidrogênio. Um desses processos é baseado na degradação anaeróbia de resíduos, principalmente os ricos em carboidratos. A parboilização é um processo hidrotérmico do arroz com casca, que tem por objetivo melhorar a qualidade nutritiva do produto. A parboilização do arroz gera cerca de 4L de efluente por quilo de arroz produzido. Esse efluente apresenta taxas elevadas de substâncias orgânicas e nutrientes como nitrogênio e fósforo, apresentando também concentrações consideráveis de carboidratos. O potencial de produção de hidrogênio do efluente da parboilização do arroz foi testado em reatores com lodo anaeróbio de UASB tratado termicamente e com lodo acidogênico produtor de hidrogênio. Também se estudou a necessidade de adição de nutrientes ao efluente de parboilizado para produção de hidrogênio. O pH do experimento foi mantido a 5,5 para evitar o crescimento de árqueas metanogênicas, consumidoras de hidrogênio. A temperatura do reator foi mantida a 20± 5°C. O experimento foi montado em batelada de 48 horas, utilizando sacarose como substrato controle. O efluente da parboilização do arroz apresenta uma concentração média de DQO bruta de 4988,6 mg.L-1 e de carboidratos de 1030,0 mg L-1. O lodo anaeróbio de UASB tratado termicamente produziu hidrogênio com taxa máxima de 62,3mL.g-1 DQO removida, enquanto o lodo acidogênico produziu 217,5 mL.g-1 DQO removida. O reator acidogênico alimentado com efluente da parboilização apresentou remoção de 32,9% de DQO e de 77,8% de carboidratos. A produção máxima de hidrogênio do efluente foi de 9,61mL. A produção de gás hidrogênio por grama de SSV no reator acidogênico alimentado com sacarose foi superior ao reator alimentado com efluente da parboilização. Os reatores com três diferentes gradientes de adição de nutrientes foram testados, mostrando que a produção de hidrogênio não foi aumentada significativamente com o aumento da concentração da solução de nutrientes, indicando que o efluente da parboilização tem potencial de produção de hidrogênio por processos anaeróbicos, sem a necessidade de adição dos nutrientes testados.

A indústria biotecnológica vem ganhando destaque em função das negativas atreladas ao uso de recursos fósseis. Nesse cenário, o Brasil se destaca por seu programa de produção de bioetanol bem estabelecido e pelo uso de cana-de-açúcar como matéria prima barata. O presente trabalho construiu Saccharomyces cerevisiae transgênicas para aprodução de compostos de interesse econômico cuja biossíntese consome energia livre (ATP). Para tanto, a expressão de proteínas heterólogas e engenharia evolutiva foram realizadas em levedura de modo que a produção de determinados compostos se torne energicamente viável.
The biotechs industry is a growing field since fossil resources are being attached to ecological and geopolitical constraints. In this scenario, Brazil has a major role due to its large experience in the bioethanol industry and sugarcane use as a cheap feedstock. The aim of this work is to optimize Saccharomyces cerevisiae allowing them to occupy a new niche: the production of economically valuable chemicals that require cellular free energy (ATP) on their biosynthesis. In this context, heterologous protein expression and evolutionary engineering were done. Therefore, this work will potentially contribute to make certain energy demanding chemicals production economically viable.

Cette thèse étudie le remodelage métabolique des cellules cancéreuses. Trois modèles sont analysés par de nombreuses approches biochimiques et génétiques : (i) des cellules de poumon transduites avec une forme oncogénique de HRASG12V, (ii) des cellules HeLa soumises à une privation de glucose et (iii) des pièces chirurgicales de cancer du poumon. Sur chaque modèle, le remodelage métabolique observé met en jeu de nombreuses voies du catabolisme et de l’anabolisme, notamment la glutaminolyse et la biosynthèse de sérine. Ce travail révèle un rôle important des mitochondries dans ce remodelage, à la fois pour l’apport d’énergie et pour la synthèse d’antioxydants et d’acides aminés, mais aussi de phospholipides. J’ai montré l’impact étendu d’une simple mutation HRASG12V sur un très grand nombre de processus, révélant ainsi l’importance de la génétique dans le remodelage métabolique des cellules cancéreuses. Toutefois, la privation de glucose induit elle aussi un remarquable remodelage à de très nombreux niveaux, depuis l’épissage des ARN messagers jusqu’à la synthèse de sérine. Enfin, cette thèse identifie deux classes bioénergétiques de tumeurs du poumon, ouvrant de nombreuses perspectives pour le diagnostic et la compréhension de ce type de tumeurs, mais aussi pour proposer des stratégies thérapeutiques adaptées. Les résultats identifient des biomarqueurs et des cibles validées sur nos modèles in vitro. Les perspectives de cette thèse vont consister à la transposition de ces approches à la clinique
This thesis investigates the metabolic remodeling of cancer cells. Three models are analyzed by different biochemical and genetic approaches: (i) lung cells transduced with oncogenic HRASG12V, (ii) HeLa cells challenged with glucose deprivation and (iii) surgical pieces of lung tumors. On each model the observed metabolic remodeling involves numerous catabolic and anabolic pathways, including glutaminolysis and serine biosynthesis. Our work revealed an important role of mitochondria in metabolic remodeling, both for the supply of energy and for the synthesis of antioxidants and amino acids, but also phospholipids. We show the extent of a single mutation HRASG12V on a very large number of metabolic processes, revealing the importance of genetics in the metabolic remodeling of cancer cells. However, glucose deprivation also induced a remarkable remodeling at many levels of cell metabolism, from the splicing of messenger RNAs to serine biosynthesis. In the third part, this thesis identified two bioenergetic classes of lung tumors, opening interesting opportunities for the diagnosis and understanding of this type of tumor, but also to propose appropriate therapeutic strategies. The results identify biomarkers and targets validated in our in vitro models. The outlook of this thesis will be to the implementation of these approaches in the clinic

Altered glucose metabolism is the underlying factor in many metabolic disorders, including diabetes. A novel protein recently linked to diabetes through animal and clinical studies is Sarcolemmal Membrane Associated Protein (SLMAP) but its role in metabolism remains undefined. The data here reveals a novel role for SLMAP isoform1 in glucose metabolism within the myocardium. Neonatal cardiomyocytes (NCMs) harvested from hearts of transgenic mice expressing SLMAP1, presented with increased glucose uptake, glycolytic rate, as well as glucose transporter 4 (GLUT4) expressions with minimal impact on lipid metabolism. SLMAP1 expression markedly increased the machinery required for endosomal trafficking of GLUT4 to the membrane within NCMs, accounting for the observed effects on glucose metabolism. The data here indicates SLMAP1 as a unique regulator of glucose metabolism through endosomal regulation of GLUT4 trafficking and suggests it may uniquely serve as a target to limit cardiovascular disease in metabolic disorders such as diabetes.

The peripheral skin microcirculation reflects the overall health status of the cardiovascular system and can be examined non-invasively by laser methods to assess early cardiovascular disease (CVD) risk factors, i.e. oxidative stress and endothelial dysfunction. Examples of methods used for this task are the laser Doppler flowmetry (LDF) and laser fluorescence spectroscopy (LFS), which respectively allow tracing blood flow and the amounts of the coenzyme NAD(P)H (nicotamide adenine dinucleotide) that is involved in the cellular production of ATP (adenosine triphosphate) energy. In this work, these methods were combined with iontophoresis and PORH (post-occlusive reactive hyperaemia) reactive tests to assess skin microvascular function and oxidative stress in mice and human subjects. The main focus of the research was exploring the nonlinear dynamics of skin LDF and NAD(P)H time series by processing the signals with the wavelet transform analysis. The study of nonlinear fluctuations of the microcirculation and cell energy metabolism allows detecting dynamic oscillators reflecting the activity of microvascular factors (i.e. endothelial cells, smooth muscle cells, sympathetic nerves) and specific patterns of mitochondrial or glycolytic ATP production. Monitoring these dynamic factors is powerful for the prediction of general vascular/metabolic health conditions, and can help the study of the mechanisms at the basis of the rhythmic fluctuations of micro-vessels diameter (vasomotion). In this thesis, the microvascular and metabolic dynamic biomarkers were characterised in-vivo in a mouse model affected by oxidative stress and a human cohort of smokers. Data comparison, respectively, with results from control mice and non-smokers, revealed significant differences suggesting the eligibility of these markers as predictors of risk associated with oxidative stress and smoke. Moreover, a relevant link between microvascular and metabolic oscillators was observed during vasomotion induced by α-adrenergic (in mice) or PORH (in humans) stimulations, suggesting a possible role of cellular Ca²⁺ oscillations of metabolic origin as drivers of vasomotion which is a theory poorly explored in literature. As future perspective, further exploration of these promising nonlinear biomarkers is required in the presence of risk factors different from smoke or oxidative stress and during vasomotion induced by stimuli different from PORH or α-adrenergic reactive challenges, to obtain a full picture on the use of these factors as predictors of risk and their role in the regulation of vasomotion.

We are the first lab to report the occurrence of a diet-induced transsulfuration (TS) blockade associating with elevated S-adenosylmethionine (i.e. SAM) synthesis, enhanced lifespan and enhanced reproductive capacity, in a vertebrate animal model. In this paradoxical study, we used LC-MS/MS-derived metabolomics data to report the effects of flaxseed (Linum Usitatissimum) on one-carbon metabolism in White Leghorn laying hens (Gallus gallus). Flaxseed contains a vitamin B6-antagonizing molecule called ‘linatine’ that is particularly effective at reducing vitamin B6 levels in small rodents and poultry. Linatine reduces TS flux through its inhibition of the vitamin B6-dependent enzymes cystathionine beta synthase (CBS) and cystathionine gamma lyase (CSE). In this study, our flaxseed-fed hens displayed decreased 4-pyridoxic acid and decreased pyridoxamine, concomitant with 15-fold elevated cystathionine. Homocysteine levels were stable in flaxseed-fed hens despite such highly elevated cystathionine. This is an astonishing finding, because mammalian models would predict the induction of hyperhomocysteinemia (i.e. elevated homocysteine) when cystathionine is so highly elevated (1). We are therefore reporting a phenomenon that might be unique to birds. Our metabolomics data indicate increased consumption of one-carbon donor molecules (e.g. choline, betaine, dimethylglycine, serine, etc) in flaxseed-fed hens, probably as a means of fueling the betaine homocysteine methyltransferase (BHMT) and methionine synthase-B12 (MS-B12) reactions. This modeling approach provides a rationale that flaxseed-fed hens increase their rate of homocysteine remethylation via BHMT and MS-B12, and in turn this would maintain stable homocysteine levels in the animal. We observed that the culminating outcome is elevated synthesis of SAM and an elevated SAM:SAH ratio. The associated biological outcomes are extended lifespan and increased reproductive capacity (i.e. increased daily egg laying) in flaxseed-fed hens. Our data further indicate that flaxseed tremendously stimulates a glucagon-like phenotype in hens. Specifically, flaxseed-fed hens exhibit 3-fold elevated glycated hemoglobin (HbA1c), 2-fold elevated serum free fatty acids (FFAs), 10 to 14% reduced body weight, and slightly reduced plasma pyruvate. These phenotypic markers suggest that glucagon might also play a large role in extending lifespan and enhancing reproductive capacity in flaxseed-fed hens. We predict that the anti-vitamin B6 effects of flaxseed are responsible for stimulating this glucagon-like phenotype in hens. Therefore, we conclude that the vitamin B6-antagonizing effects of linatine (via flaxseed dieting) improve liver function, body leanness, egg laying and survival, in a manner associated with increased SAM synthesis, increased blood FFA levels and increased blood glucose levels, in laying hens. The second part of this dissertation is used to test the hypothesis that polyunsaturated fatty acids (PUFAs) regulate lipid metabolism, increase mitochondrial respiration and decrease E-cadherin expression, in laying hen ovarian tumors. Researchers are unaware of the mitochondrial effects of PUFAs within laying hen ovarian tumors, and only a few publications exist regarding the analysis of E-cadherin in laying hen ovarian cancer. The results of this present work suggest that dietary PUFAs accumulate within laying hen ovarian tumors, and these same tumors exhibit decreased gene transcripts that govern de novo lipogenesis (i.e. FASN). Simultaneously, these tumors exhibit elevated transcripts for oxidative phosphorylation (OXPHOS) and decreased transcripts for phase 2 antioxidant enzymes. These patterns associated with decreased transcript levels of CDH1 (the gene for E-cadherin) in ovarian tumors, but no effect on full length 120kDa protein was observed by PUFAs versus our control diet. Interestingly, the effect of PUFAs on E-cadherin occurred at the level of the cleaved 37kDa and 80kDa E-cadherin fragments, such that PUFAs reduced their levels in hen ovarian tumors. We therefore developed a system for depleting the 80kDa E-cadherin fragment from hen ascites fluid (i.e. fluid from a hen that had ovarian cancer), so that we could test our hypothesis that the 80kDa E-cadherin fragment is important for supporting mitochondrial respiration in normal ovarian surface epithelial cells (IOSE80s). Mitochondrial membrane potential was decreased in IOSE80s when the 80kDa fragment was removed from the ascites; however, there was no effect on basal oxygen consumption in subsequent tests using extracellular flux analysis with Seahorse XFp. During our analysis of microRNA-200a-3p (miR-200a) we did not observe any effect of diet on miR-200a within hen ovarian tumors; however, we did observe that miR-200a levels increased within the tumor when going from stage 2 to stage 4 disease. Overall, we observed reduced risk of ovarian cancer, stage 4 ovarian cancer, multiple peritoneal tumor involvement and cancer-associated mortality, in laying hens that consumed a diet that was supplemented with PUFAs.

Conselho Nacional de Desenvolvimento Científico e Tecnológico
O carcinoma epidermoide de esôfago (CEE) representa 90% dos casos de câncer de esôfago no Brasil. O CEE tem detecção tardia, um comportamento extremamente agressivo e baixa sobrevida, sendo, portanto, um alvo interessante para o estudo dos mecanismos envolvidos em sua carcinogênese, a fim de se identificar possíveis alvos terapêuticos ou marcadores moleculares que ajudem na prática clínica. Mudanças no metabolismo energético da célula tumoral parecem ter papel de destaque na transformação maligna. Sabe-se que células tumorais consomem glicose avidamente produzindo ácido lático, mesmo em condições de normóxia. Dentre os fatores que podem contribuir para o estímulo da glicólise em células tumorais destacam-se as alterações em enzimas da via glicolítica tais como: as piruvato-cinases M1 e M2 (PKM1 e PKM2), a hexocinase II (HKII), isofoma 1 do transportador de glicose, GLUT-1, e o fator de transcrição induzido por hipóxia (HIF1α), responsável pela transcrição das proteínas citadas. O objetivo do estudo é avaliar a relação entre a expressão de HIF1α, HK2, PKM2, PKM1 e GLUT-1 e dados clínico-patológicos no CEE. Para tal, foram avaliados tumores conservados em parafina de 44 pacientes com CEE matriculados no INCA e no Hospital das Clínicas de Porto Alegre. Além disso, foram coletadas amostras de biópsia de esôfago em 67 pacientes sem doença esofágica, que foram submetidos à endoscopia no Hospital Universitário Pedro Ernesto (HUPE). A expressão das proteínas foi avaliada nos tecidos por imuno-histoquímica, enquanto que a expressão do mRNA de GLUT-1 também foi avaliada nas amostras controle. Foi observado que as amostras controle expressam HK2, PKM1, PKM2, HIF1α nas camadas do epitélio esofágico. Já GLUT-1 e Ki-67 são vistos apenas na camada basal. Além disso, a expressão do mRNA de GLUT-1 não teve correlação com fatores etiológicos da doença. Em CEE a expressão de HK2, PKM2 e GLUT-1 foi vista em todos os tumores, já a expressão de HIF1α e PKM1 foi variável. Além disso, observou-se que maior expressão de HIF-1α apresenta correlação com invasão linfonodal e diferenciação, enquanto que a expressão de HK2 tem relação com sobrevida e PKM1 com diferenciação. As correlações clínicas encontradas sugerem que alterações no metabolismo energético é um alvo de estudo interessante para desenvolvimento de marcadores moleculares que auxiliem a prática clínica.
The esophageal squamous cell carcinoma (ESCC) represents 90% of cases of esophageal cancer in Brazil. The ESCC has late diagnosis, highly aggressive behavior and poor survival. ESCC is an interesting target to the study of mechanism involved in its carcinogenesis, in order to identify potential drug targets or biomarkers to help clinical practice. Changes in tumor cell energy metabolism appear to have a prominent role in malignant transformation. Tumor cells consume glucose avidly and produce lactic acid, even under normoxia. Among the factors that may contribute to the stimulation of glycolysis in tumor cells, there are changes in the glycolytic pathway enzymes such as: pyruvate kinase M1 and M2 (PKM2 and PKM1), hexokinase II (HKII), glucose transporter isoform 1, GLUT-1, and transcription factor induced by hypoxia (HIF1α), responsible for the transcription of proteins cited. The goal of the study is to evaluate the relationship between the expression of HIF1α, HK2, PKM2, PKM1 and GLUT-1 and clinicopathological data in ESCC. Biopsy of the esophagus in patients without esophageal disease were collected, who underwent endoscopy at University Hospital Pedro Ernesto (HUPE). Tissue samples were collected from 44 patients with a histologically confirmed diagnosis of ESCC recruted from Hospital Universitário Pedro Ernesto (HUPE-UERJ), and Instituto Nacional de Câncer (INCA). Tissue samples from healthy individuals submitted to endoscopic routine examination, not related to cancer or esophageal disorders, at HUPE-UERJ were also included in this study. The expression of proteins in tissues was evaluated by immunohistochemistry, while mRNA expression of GLUT-1 was also evaluated in the control samples. It was observed that the control samples express HK2, PKM1, PKM2, HIF1α layers of the esophageal epithelium. GLUT-1 and Ki-67 are seen only in the basal layer. Furthermore, expression of GLUT-1 mRNA did not correlate with disease etiological factors. In ESCC expression of HK2, PKM2 and GLUT-1 was seen in all tumors, and the expression of HIF1α and PKM1 was variable. We found that increased expression of HIF-1α correlates with lymph node invasion and differentiation, whereas the expression of HK2 is related to survival, and differentiation with PKM1. The clinical correlations found suggest that alterations in energy metabolism are an interesting subject of study for development of biomarkers that help clinical practice.

Despite improvements in treatment regimens over the past few decades patients living with cystic fibrosis (CF) continue to present with malnutrition due to energy imbalance. A major factor effecting energy balance in this disease is an increased energy expenditure, the causes of which remain contentious. At rest patients with CF expend between 1 O and 20% more calories than healthy individuals however during activity energy expenditure has not been thoroughly investigated. Therefore the papers described within this dissertation provide insight relating to the energy costs of standard physical activity sessions in patients with CF. Accurate body composition analysis in CF is a fundamental requirement for routine assessment of nutritional status and for appropriate expression of energy expenditure when making comparisons with healthy individuals. Use of bioelectrical impedance analysis may prove beneficial in this disease but as it stands this instrument is not valid for monitoring total body water and hence fat free mass in this population. This is because factory installed regression equations that predict total body water from impedance overestimate the true volume of body water in CF. Use of the resistance index (ie- Height2 I Impedance) to predict total body water in CF permits more accurate use of bioelectrical impedance analysis in this population. The energy cost of physical activity in patients with CF is increased but is also greater than the increase in energy expenditure observed at rest. This implies that an additional energyrequiring process occurs during activity in this disease, perhaps related to the efficiency of oxidative work performance within skeletal muscles or to an increased oxygen cost of breathing. A unique feature of this thesis was the refinement of a non-invasive 13C02 breath test to evaluate energy expenditure during physical activity. This technique was developed for use in the remaining studies. In healthy controls, the 13C02 breath test is accurate in assessing energy expenditure during activity both at the population level and for individuals. This is not the case in patients with CF who demonstrate increased intra-individual variation between energy expenditure values from indirect calorimetry and the 13C02 breath test, thus indicating that this test is not useful for individual assessment in this disease.

Cellular senescence represents status, when the cells cease to divide and remain in permanent cell cycle arrest. Senescence is considered to be an active response of the cell to various extrinsic and intrinsic types of stress such as certain oncogene activation, exposing to several cytokines or drugs and damaged and/or uncapped telomeres. Senescent cells are characterised by extensive modification of gene expression, flattened and enlargement of cellular body. Hypothetically, altered gene expression may lead also to increase of certain surface proteins expression. Such protein can be L1 cell adhesive molecule (L1CAM), which is expressed heterogeneously within the population. This Thesis describes current knowledge of cellular senescence, the mechanism, which may result in establishment of senescence phenotype, and also the characteristic markers of senescence. Thesis also puts together the heterogeneity of L1CAM expression in A375 senescent cells with oxygen consumption rate and extracellular acidification rate performed by Seahorse XFe24 metabolic analyser. Therefore, ells were sorted according to their levels of expressing L1CAM onto low and high L1CAM expressing subpopulations. Obtained data show potential correlation between the rate of L1CAM expression in A375 cells and the metabolic rate. Key...

This thesis deals with in vivo MR spectroscopy. Measurements in this thesis were performed on whole-body MR tomograph at the Institute for Clinical and Experimental Medicine in Prague. The objective of the thesis was to study differences in the biochemical processes and energy metabolism in the muscle tissue under physical workload between the groups of healthy subjects and patients with type 1 diabetes mellitus (DM1). We used phosphorous spectroscopy in combination with ergometer. The thesis is divided into five chapters. The first chapter describes theoretical introduction to in vivo 1 H and 31 P MR spectroscopy and muscle metabolism, the second chapter deals with the description of the experimental equipment and measurement, results of the thesis are reported in the third chapter and the fourth chapter is a discussion of results. Main result of this work is summarized in conclusion; we found differences between the metabolism of patients with DM1 and healthy volunteers.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1990.
Includes bibliographical references.
v. 1. Energetics and adaptation -- v. 2. The average daily metabolic rate and associated energy substrate utilization as determined by the doubly labeled water technique.
Microfiche.
2 v. bound ill. (some col.) 29 cm

碩士
國立臺灣大學
海洋研究所
97
Thermophilic microorganisms using chemical compounds to carry on their metabolisms not only are limited by geological and geochemical characteristics but also enhance geological and geochemical cycling in hydrothermal ecosystems. Hot springs are widely hosted in igneous, metamorphic and sedimentary rocks in Taiwan. These diverse natural habitats for thermophilic microorganisms are ideal studying sites to understanding the interaction between microbial communities and geochemical circumstance in various geological regions. On the basis of geochemical compositions, free energy and energy flux could be calculated for certain reactions. Such evaluation would provide a complete and quick way to clarify the energetic metabolic pathways, to understand the competition among microbial populations and to reveal the relationship between community structures and environmental factors in various Taiwan hot springs ecosystems. This study sampled 16 hot springs derived from three geological domains, the northern volcanic region, the eastern metamorphic region and the western sedimentary region. Anions, cations, organic acids, dissolved gases, as well as minerals were measured in these hot springs. Chemical analyses showed that various electron donors, including H2, NH4+, Fe2+, H2S, CH4 and organic acids and electron acceptors, including O2, NO3-, Fe3+, SO42-, S0 and CO2 were available in Taiwan hot spring ecosystems. According to the thermodynamic principle and the concept of lowest free energy requirement, energetic metabolic pathways were revealed by the calculation of free energy and energy flux of various chemical reactions. Energetic metabolic reactions and their energy flux basically depended on the availability and concentration of electron acceptors and donors in different regions. Whether the metabolic reaction can continuously provide energy for the microorganism in the hot spring was also evaluated by the free energy and energy flux change due to certain geochemical variations. Most energetic metabolism pathways should be persistent despite of the dynamic change of chemical and physical conditions. These results were generally supported by molecular biology and microbial incubation analyses. The structure and the competition within microbial community were examined in the view of geochemical conditions and energy flux in the hydrothermal ecosystems.

Cells require adenosine triphosphate (ATP) to drive the myriad processes associated with growth, replication, and homeostasis. Eukaryotic cells rely on mitochondria to produce the vast majority of their ATP. Mitochondria consist of a relatively smooth outer mitochondrial membrane (OMM) and a highly complex inner mitochondrial membrane (IMM), containing numerous invaginations, called cristae, which house the molecular machinery of oxidative phosphorylation (OXPHOS). Although mitochondrial form and function are intimately connected, limitations in the resolution of live-cell imaging have hindered the ability to directly visualize the relationship between the architecture of the IMM and its associated bioenergetic properties. Using advanced imaging technologies, including Airyscan, stimulated emission depletion (STED), and structured illumination microscopy (SIM), we developed an approach to image the IMM in living cells. Staining mitochondria with various ΔΨm-dependent dyes, we found that the fluorescence pattern along the IMM was heterogeneous, with cristae possessing a significantly greater fluorescence intensity than the contiguous inner boundary membrane (IBM). Applying the Nernst equation, we determined that the ΔΨm of cristae is approximately 12 mV stronger than that of IBM, indicating that the electrochemical gradient that drives ATP synthesis is compartmentalized in cristae membranes. Notably, deletion of key components of the mitochondrial contact site and cristae organizing system (MICOS), as well as OPA1, which regulate crista junctions (CJs), decreased ΔΨm heterogeneity. Complementing our super-resolution imaging of cristae in living cells, we also developed a machine-learning protocol to quantify IMM architecture. Tracking real-time changes in cristae density, size, and shape, we determined that cristae dynamically remodel on a scale of seconds. Furthermore, we found that cristae move away from sites of mitochondrial fission, and, prior to mitochondrial fusion, the IMM forms finger-like protrusions bridging the membranes of the fusing organelles. Lastly, we investigated the role of the motor adaptor protein, Milton1/TRAK1, in mitochondrial dynamics. Patient-derived Milton1-null fibroblasts not only had impaired mitochondrial motility but exhibited fragmentation corresponding to a roughly 40% decrease in mitochondrial aspect ratio and a 17% increase in circularity, associated with increased DRP1 activity. Conversely, we found that overexpression of Milton1 led to mitochondrial hyperfusion, decreased DRP1 activity, and aberrant clustering of mtDNA. Overall, our studies directly demonstrate that maintaining mitochondrial architecture is essential for preserving the functionality of mitochondria, the hubs of eukaryotic metabolism.

BACKGROUND: Tuberous sclerosis complex (TSC) is a multisystem hamartomatous disease caused by inactivating mutations in the TSC1/TSC2 genes leading to hyperactivation of mammalian target of rapamycin complex 1 (mTORC1) in TSC tumors. Novel therapeutic regimens and imaging biomarkers remain critical unmet needs in TSC. Mitochondrial fatty acid oxidation (FAO) is a major cellular source of acetyl-CoA. Acetyl-CoA is a central metabolite in lipid anabolism and catabolism. The purpose of this study was to identify novel metabolic therapeutic targets, particularly involving lipid metabolism, to achieve durable responses in TSC. METHODS AND RESULTS: Fluoroacetate (FACE), an acetate derivative, is a surrogate biomarker of mitochondrial activity. It accumulates in the mitochondria without being oxidized to CO2, and it is converted to fluorocitrate, irreversibly inhibiting the TCA (tricarboxylic acid) cycle enzyme aconitase. Micro-positron emission tomography (PET) imaging of subcutaneous xenografts of TSC2-deficient Eker rat uterine leiomyoma-derived ELT3 cells showed rapid uptake of [18F]FACE that was maintained after 72-hour treatment with mTORC1 inhibitor rapamycin. This result suggests that mitochondrial oxidative metabolism is sustained in the presence of rapamycin. Consistent with this finding, treatment of TSC2-deficient cells with rapamycin led to a significant increase in FAO and a decrease in glucose oxidation in vitro as measured by a 14C-CO2 collection metabolic assay. Expression of the A isoform of carnitine palmitoyltransferase I (CPT1A; FAO rate-limiting enzyme) was selectively increased in TSC2-deficient cells. Pharmacological inhibition of CPT1A by ST1326 led to a decrease in FAO, as measured by a 14C-CO2 collection metabolic assay, and a decrease in mitochondrial ATP production, measured by the Seahorse analyzer. CONCLUSIONS: This study proposes a role for FAO in TSC tumor bioenergetics and for CPT1A as a potential therapeutic target in TSC.

Changes in intracellular redox homeostasis are implicated in both normal cell signaling and as pathophysiological mechanisms contributing to a variety of age-related diseases, including diabetes, atherosclerosis, neurodegenerative conditions, and cancer. Though a variety of well described mechanisms exist to counterbalance the overproduction of cellular oxidants and maintain optimal intracellular redox poise, the understanding of the mechanism(s) through which cellular redox homeostasis regulates cell signaling functions is less well understood. Here, we demonstrate that signaling by the immediate early gene / orphan nuclear hormone receptor NGFI-B (Nur77, TR3), which functions pleiotropically in the regulation of cell growth, metabolism, differentiation and death in diverse tissues, is redox-regulated at both the level of induction and NGFI-B-dependent gene transcription. Using co-immunoprecipitation experiments in cells, we also identified a novel interaction between NGFI-B and the cytoplasmic thiol-reducing catalyst thioredoxin1 (Trx1), that, similar to DTT, blocks NGFI-B-dependent gene expression in a manner that depends on the Trx1 active site cysteines. Together these observations add NGFI-B-dependent gene expression to a growing portfolio of transcription factor pathways that are redox-regulated. NGFI-B, in addition, appears to regulate the mitochondrial membrane potential in L6 skeletal myoblasts. NGFI-B is indispensible for T-cell receptor-mediated apoptosis and induces cell death in a variety of cell types in response to diverse pro-apoptotic stimuli. Like p53, translocation of NGFI-B from the nucleus to the mitochondria may be a critical aspect of its pro-apoptotic function. Interestingly, we found that enforced NGFI-B expression in L6 skeletal muscle myoblasts led to a significant decrease of MMP that peaked 48hr after transfection and did not require a cell death-inducing stimulus. Moreover, NGFI-B transfected cells had no increase in mitochondrial cytochrome C release despite loss of MMP at 48 hr. Combined, these data suggest that loss of MMP in muscle cells may be an early event in the apoptotic process regulated by NGFI-B. This, along with the redox regulation of NGFI-B, provides unique evidence of a relationship between the mitochondria, mitochondrial by-products, ROS, and the regulation of and by the transcription factor NGFI-B.
text