Дисертації з теми "NRT2"
Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: NRT2.
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 дисертацій для дослідження на тему "NRT2".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Faure, Sandrine. "Étude de l'absorption du nitrate chez Brassica napus L. : évolution de l'activité des transporteurs et de la transcription des gènes NRT1 et NRT2 en réponse à une privation en NO 3, évaluation de leur rôle sur le cycle de culture." Caen, 2000. http://www.theses.fr/2000CAEN2007.
Повний текст джерелаАнотація:
Le colza, espece phylogenetiquement proche d'arabidopsis thaliana et presentant des capacites d'absorption elevees, a ete choisi pour etudier le metabolisme azote des especes cultivees. Les etudes cinetiques revelent un profil d'absorption du nitrate biphasique, suggerant qu'il existe au moins 2 systemes d'absorption : un systeme saturable a forte affinite agissant pour des faibles concentrations externes en no 3 (hats), et un systeme non saturable a faible affinite intervenant pour les fortes concentrations (lats). Ces deux systemes seraient constitues chacun d'une composante constitutive (chats et clats) et d'une composante inductible (ihats et ilats). Le suivi de la transcription des genes nrt1 et nrt2 au cours d'une privation partielle ou totale en azote conforte l'hypothese selon laquelle le gene nrt2 code un systeme ihats alors que le gene nrt1 code un systeme ilats. Si dans nos conditions experimentales, l'existence d'un mecanisme de de-induction et/ou de repression par les acides amines libres pourrait expliquer la chute de la transcription des genes nrt1 et nrt2 pendant les 48 premieres heures de privation. Par contre aucun mecanisme de de-repression n'a pu etre mis en evidence. L'expression des genes nrt1 et nrt2 est regulee au niveau transcriptionnel par le no 3 externe et probablement par la demande en azote des parties aeriennes, mais aussi au niveau post-transcriptionnel. Nos resultats montrent que chez le colza, les pools racinaires en no 3 et en acides amines libres n'interviennent pas au niveau transcriptionnel. Nous avons initier un modele mecaniste de l'absorption du nitrate au cous d'un cycle de culture uniquement base sur l'offre en nitrate du sol et sur le fonctionnement des transporteurs. Les simulations realisees montrent que le systeme hats intervient pour 94% en l'absence de fertilisation et pour 82% lors d'un apport azote a l'automne. Une fertilisation azotee augmente la capacite et la duree d'intervention du systeme lats.
2
Tao, Shasha, Pengfei Liu, Gang Luo, de la Vega Montserrat Rojo, Heping Chen, Tongde Wu, Joseph Tillotson, Eli Chapman, and Donna D. Zhang. "p97 Negatively Regulates NRF2 by Extracting Ubiquitylated NRF2 from the KEAP1-CUL3 E3 Complex." AMER SOC MICROBIOLOGY, 2017. http://hdl.handle.net/10150/623934.
Повний текст джерелаАнотація:
Activation of the stress-responsive transcription factor NRF2 is the major line of defense to combat oxidative or electrophilic insults. Under basal conditions, NRF2 is continuously ubiquitylated by the KEAP1-CUL3-RBX1 E3 ubiquitin ligase complex and is targeted to the proteasome for degradation ( the canonical mechanism). However, the path from the CUL3 complex to ultimate proteasomal degradation was previously unknown. p97 is a ubiquitin-targeted ATP-dependent segregase that extracts ubiquitylated client proteins from membranes, protein complexes, or chromatin and has an essential role in autophagy and the ubiquitin proteasome system ( UPS). In this study, we show that p97 negatively regulates NRF2 through the canonical pathway by extracting ubiquitylated NRF2 from the KEAP1-CUL3 E3 complex, with the aid of the heterodimeric cofactor UFD1/NPL4 and the UBA-UBX containing protein UBXN7, for efficient proteasomal degradation. Given the role of NRF2 in chemoresistance and the surging interest in p97 inhibitors to treat cancers, our results indicate that dual p97/NRF2 inhibitors may offer a more potent and long-term avenue of p97-targeted treatment.
3
Steel, Richard James. "Targeting the Nrf2/Keap1 interaction." Thesis, University of East Anglia, 2014. https://ueaeprints.uea.ac.uk/48776/.
Повний текст джерелаАнотація:
The Nrf2/Keap1 protein-protein interaction (PPI) regulates activity of the Nrf2 antioxidant and anti-inflammatory pathway. The transcription factor Nrf2 has been found to be a key mediator in the resolution of inflammation and the progression of chronic diseases. Most known inducers of the Nrf2 pathway act by covalent modification of Keap1 via electrophilic functional groups. Controlled induction of the Nrf2 pathway via specific disruption of the Nrf2/Keap1 interaction is an attractive therapeutic target. This work describes a cell penetrating, TAT-Nrf2 peptide which targets the Nrf2/Keap1 interaction in vitro. Induction of downstream genes is both sequence and dose dependent. In an established model of bacterial sepsis, the peptide reduces pro-inflammatory mediators. Investigation of both cell penetrating and Keap1 binding sequences has identified the requirements for effective Nrf2 induction in cell based assays. An in vitro purified protein, fluorescence polarisation (FP) assay was established in order to rapidly characterise these peptides. Based on the secondary structure of the Keap1 binding portion of Nrf2, further peptides were designed to constrain the conformation and mimic the full protein, while reducing overall size. Synthesis of cyclic peptides has identified the minimal sequence required for efficient binding and provides significant improvement in affinity over linear sequences. Several macrocyclisation techniques were explored in an attempt to retain biological activity, without the need for cell penetration sequences. Initially, disulfide bridge formation was used to produce peptides with affinities for Keap1 similar to the TAT-Nrf2 peptides at considerably reduced size. Subsequently, both head-to-tail cyclisation and peptide stapling were examined in order to restore potency in cell based assays. Finally, an alternative method for identification of Nrf2/Keap1 disruptors was explored. In silico docking calculations were used to identify potential novel PPI disruptors through library screening. Extracted hits were assessed using the FP assay, validating its use for high throughput screening.
4
Cowan, Jonathan. "Targeting Nrf2 in inflammation and cancer." Thesis, University of East Anglia, 2014. https://ueaeprints.uea.ac.uk/53467/.
Повний текст джерелаАнотація:
The transcription factor Nrf2 protects against cellular stress by inducing cytoprotective proteins. Activation of Nrf2 protects against inflammation and oxidative damage in disease models in vitro and in vivo. Nrf2 activation may be a good therapeutic strategy in these diseases. Some dietary components activate Nrf2, which may be partially responsible for their beneficial effects in preventing disease. In this study a novel organosulfur compound from garlic, diallyl pentasulfide (DAPS), was investigated. DAPS strongly activated the Nrf2 pathway. Furthermore, it was a much more powerful activator of heme oxygenase-1 than any diallyl sulfides reported to date. Nrf2 is regulated by Keap1, which targets it for degradation. Disruption of the Nrf2/Keap1 interaction results in Nrf2 activation. In this study, a novel cell-penetrating peptide, based on the Keap1-binding site of Nrf2, disrupted the Nrf2/Keap1 interaction, and activated the Nrf2 pathway. Furthermore, it demonstrated anti-inflammatory activity, significantly inhibiting LPS-induced TNF expression in THP-1 monocytes, suggesting that the interaction is a valid therapeutic target in inflammation. In cancer, Nrf2 plays a dual role. Activation of Nrf2 protects cells from carcinogens. However, once a tumour has developed, Nrf2 can be hijacked by cancer cells to induce chemoresistance. This study examined the role of Nrf2 in malignant melanoma cells. Nrf2 was found to be overexpressed in 11 human melanoma cell lines in comparison with melanocytes. Chemoresistance to dacarbazine, doxorubicin and cisplatin correlated with Nrf2 expression, and Nrf2 siRNA increased the susceptibility of M202 and SK-MEL-5 cells to cisplatin, suggesting that Nrf2 plays a role in chemoresistance in melanoma. In conclusion, this study has identified novel activators of Nrf2, including a dietary compound and a cell penetrating peptide which inhibits inflammation in vitro. In addition, Nrf2 inhibition sensitises melanoma cells to chemotherapy. These results suggest that targeting Nrf2 is a viable strategy in both inflammation and cancer.
5
Wu, Suquin, and s3102813@student rmit edu au. "Performance of regional atmospheric error models for NRTK in GPSnet and the implementation of a NRTK system." RMIT University. Mathematical and Geospatial Sciences, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20091014.144831.
Повний текст джерелаАнотація:
Many high-accuracy regional GPS continuously operating reference (CORS) networks have been established globally. These networks are used to facilitate better positioning services, such as high accuracy real-time positioning. GPSnet is the first state-wide CORS network in Australia. In order to maximize the benefits of the expensive CORS geospatial infrastructure, the state of Victoria in collaboration with three universities (RMIT University, the University of NSW and the University of Melbourne) embarked on research into regional atmospheric error modelling for Network-based RTK (NRTK) via an Australian Research Council project in early 2005. The core of the NRTK technique is the modelling of the spatially-correlated errors. The accuracy of the regional error model is a determining factor for the performance of NRTK positioning. In this research, a number of error models are examined and comprehensively analysed. Among them, the following three models are tested: 1) the Linear Interpolation Method (LIM); 2) the Distance-Based interpolation method (DIM); and 3) the Low-order surface model (LSM). The accuracy of the three models is evaluated using three different observation sessions and a variety of network configurations of GPSnet. Results show that the LIM and DIM can be used to significantly reduce the double-differenced (DD) residuals (up to 60% improvement), and the LIM is slightly better than the DIM (most at mm level). However the DD residuals with the LSM corrections are, in some cases, not only much worse than that of the LIM and DIM but also even must greater/worse than the DD residuals without any corrections applied at all. This indicates that there are no advantages by using the LSM for the error modelling for NRTK in GPSnet, even though it is the most commonly used method by researchers. The performance difference of the LIM for different GPSnet configurations is also tested. Results show that in most cases, the performance difference mainly caused by the number of reference stations used is not significant. This implies that more redundant reference stations may not contribute much to the accuracy improvement of the LIM. However, it may mitigate the station specific errors (if any). The magnitude of the temporal variations of both the tropospheric and ionospheric effects in GPSnet observations is also investigated. Test results suggest that the frequency of generating and transmitting the tropospheric corrections should not be significantly different from that for the ionospehric corrections. Thus 1Hz frequency (i.e. once every second) is recommended for the generation and transmission for both types of the atmospheric corrections for NRTK in GPSnet. The algorithms of the NRTK software package used are examined and extensive analyses are conducted. The performance and limitation of the NRTK system in terms of network ambiguity resolution are assessed. The methodology for generating virtual reference station (VRS) observations in the system is presented. The validation of the algorithms for the generated VRS observations is undertaken. It is expected that this research is significant for both the selection of regional error models and the implementation of the NRTK technique in GPSnet or in the Victorian region.
6
Lee, Sang C., Jack Zhang, Josh Strom, Danzhou Yang, Thai Nho Dinh, Kyle Kappeler, and Qin M. Chen. "G-Quadruplex in the NRF2 mRNA 5′ Untranslated Region Regulates De Novo NRF2 Protein Translation under Oxidative Stress." AMER SOC MICROBIOLOGY, 2017. http://hdl.handle.net/10150/622753.
Повний текст джерелаАнотація:
Inhibition of protein synthesis serves as a general measure of cellular consequences of chemical stress. A few proteins are translated selectively and influence cell fate. How these proteins can bypass the general control of translation remains unknown. We found that low to mild doses of oxidants induce de novo translation of the NRF2 protein. Here we demonstrate the presence of a G-quadruplex structure in the 5' untranslated region (UTR) of NRF2 mRNA, as measured by circular dichroism, nuclear magnetic resonance, and dimethylsulfate footprinting analyses. Such a structure is important for 5'-UTR activity, since its removal by sequence mutation eliminated H2O2-induced activation of the NRF2 5' UTR. Liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based proteomics revealed elongation factor 1 alpha (EF1a) as a protein binding to the G-quadruplex sequence. Cells responded to H2O2 treatment by increasing the EF1a protein association with NRF2 mRNA, as measured by RNA-protein interaction assays. The EF1a interaction with small and large subunits of ribosomes did not appear to change due to H2O2 treatment, nor did post translational modifications, as measured by two-dimensional (2-D) Western blot analysis. Since NRF2 encodes a transcription factor essential for protection against tissue injury, our data have revealed a novel mechanism of cellular defense involving de novo NRF2 protein translation governed by the EF1a interaction with the G-quadruplex in the NRF2 5' UTR during oxidative stress.
7
Werling, Kristoffer, and Andreas Höglund. "Jämförelse av mätosäkerhet i höjd över tid med NRTK : Undersökning av tidsvariationer för GNSS-höjder inmätta med NRTK." Thesis, Karlstads universitet, Institutionen för miljö- och livsvetenskaper (from 2013), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-85239.
Повний текст джерелаАнотація:
Global Navigation Satellite Systems (GNSS) i kombination med Nätverks-RTK (NRTK) har idag blivit en vanlig metod för geodetiska inmätningar i plan och höjd. Inmätningar med NRTK har fördelen att de är relativt enkel att använda, ger koordinater i realtid och med låg mätosäkerhet (2–3 cm). Dock har användare rapporterat om att större avvikelser i höjd är vanligare än avvikelser i plan, vilka varierar över tid. Tidigare studier har inte funnit samband mellan avvikelser i höjd med NRTK och variationen över tid. Studiens syfte var att undersöka hur resultatet av inmätta höjder med NRTK varierar över tid och vad som påverkar avvikelsen i höjd samt om det går att finna ett samband för avvikelserna. I studien användes en GNSS-mottagare med NRTK för att på två stompunkter insamla mätdata en gång i minuten i tre timmar på varje punkt, under totalt två dagar. Mätdata som lagrades och analyserades var antal satelliter, PDOP, vertikal precision, och tidpunkt för inmätt höjd och höjdvärde. Under fältarbetet användes också två olika elevationsvinklar, 10 och 15 grader, för att se hur mätosäkerheten påverkades. Vidare utfördes en dubbelavvägning mellan stompunkterna som en kontroll av de angivna höjdkoordinaterna. Resultatet visar att variationen för enskild inmätt höjd är slumpmässig. En undersökning av PDOP, antal satelliter, horisontell och vertikal precision gav inga korrelationer till mätresultatet. Standardosäkerheten i höjd för mätserie på punkt 8316 med 10° elevationsvinkel beräknades till 1,2 cm och med en förändring till 15° elevationsvinkel 1,6 cm. På punkt 8318 med 10° elevationsvinkel beräknades 2,6 cm och med 15° elevationsvinkel 3,4 cm. Analysen av mätdata förtydligar att behov finns för att öka tillförlitligheten vid GNSS-mätning med NRTK. Standardosäkerheten överskrider angiven mätosäkerhet för metoden, vid mätning på 8318 med 15° elevationsvinkel. Med elevationsvinkel 10° uppnås inte 68 % av mätningarna inom sigmanivå 2, och drygt 13 % återfinns inom sigmanivå 2–3. Vid en beräkning av standardosäkerhet, med medeltals-bildning, erhölls markanta förbättringar på punkt 8316 för båda mätserierna upp till 20 min medan det följande ger avtagande förbättringar. På punkt 8318 erhölls ständiga förbättringar kontinuerligt till 60 min vilket var den högsta gränsen som undersöktes. Differens mellan högsta och lägsta avvikelse för inmätt höjd, jämfört med känd höjd, beräknades till 9,2 cm för punkt 8316 med 15° elevation och 6,9 cm med 10°. Motsvarande för punkt 8318 med 15° beräknades avvikelsen till 16,5 cm och 12,3 cm för 10°. För GNSS-användare behövs insikt i att enskilda mätningar, med lågt angivna värden i handenheten, inte säkerställer goda mätresultat. Flera mätningar under kort tid kan ge mycket låg standardosäkerhet, men en timme senare kan samma låga standard-osäkerhet för nya mätningar fortfarande representera en avvikande inmätt höjd. Medeltalsbildning, tidsseparation och en lämplig elevationsvinkel är sannolikt krav för att tillförlitligt kunna säkerställa att metoden uppnår 2–3 cm mätosäkerhet i höjd för 68 % av mätningarna.The usage of GNSS is becoming increasingly more common due to its efficiency and time saving capacities. Network-RTK is a method that uses relative positioning and is supposed to deliver measurements with a positional accuracy of about 2-3 cm for plane and height. Previous research shows variety in measuring results using NRTK at different times or days, but the focus was on other aspects than time itself. This study focused on time and its impact on GNSS-derived heights, linked to used methods for practical use of GNSS, and these results were meant to create guidelines or routines for increased reliability in measuring data if it exceeded the positional accuracy. Measurment data were gathered at two vertical control points during three hours each, on two separate days, with data being collected at a one-minute interval. The findings of this study show that the variety over time is random, and that there are no standard settings or routines that guarantee reliability for the method to deliver commonly stated positional accuracies. Although, we found that certain steps for improving measurements are time-separating, averaged measurements for at least twenty minutes, and a good understanding of how to set an appropriate elevation mask.
8
Hong, Fei. "ANALYSIS OF ELECTROPHILE-INDUCED NRF2 GENE ACTIVATION." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1280%5F1%5Fm.pdf&type=application/pdf.
Повний текст джерела
9
Baird, Liam. "Single cell analysis of Keap1-Nrf2 dynamics." Thesis, University of Dundee, 2013. https://discovery.dundee.ac.uk/en/studentTheses/50580cee-d8e3-4618-aa7d-3a9c0fa8a96f.
Повний текст джерелаАнотація:
The transcription factor Nrf2 is a master regulator of cytoprotective gene expression. Nrf2 is negatively controlled by Keap1, a sensor protein which allows Nrf2 to respond to changing cellular conditions. In the basal state, Nrf2 binds to two sites of a Keap1 dimer allowing its ubiquitination in a Cullin-3/Rbx1-dependent manner. In response to electrophiles and oxidants (termed inducers, which bind directly to Keap1) ubiquitination of Nrf2 is inhibited; consequently, Nrf2 accumulates and activates transcription.We have developed aFLIM-based assay to study the dynamic interaction between Keap1 and Nrf2 in single live cells. Combinations of wild type and mutant proteins revealed that under basal conditions the Keap1-Nrf2 complex exists in two conformations, one in which Nrf2 is bound to both members or the Keap1 dimer (‘closed’ conformation), and a second in which Nrf2 interacts with a single Keap1 monomer (‘open’ conformation). We found that following exposure to a range of inducers the Cul3-Keap1-Nrf2 complex does not dissociate, but remains intact. Furthermore, we found that inducers lead to the accumulation of the Keap1-Nrf2 complex in the ‘closed’ conformation. Interestingly, blockage of the proteasome also leads to the accumulation of the complex in the closed conformation, suggesting that the binding of Nrf2 and its subsequent Keap1-dependent ubiquitination follows a cyclical pattern. We believe that the existence of a Keap1-Nrf2 binding cycle benefits the cell, as it allows other signaling pathways, such as those mediated by p21 and p62, to regulate Nrf2 activity in the absence of inducers. Together our results show that the interaction between Keap1 and Nrf2 is more dynamic than previously anticipated and that inducers function to modulate this dynamism, leading to Nrf2 stabilisation and cytoprotective gene expression.
10
Gacesa, Ranko. "Agonists of the transcriptional Keap1-Nrf2 gatekeeper." Thesis, King's College London (University of London), 2017. https://kclpure.kcl.ac.uk/portal/en/theses/agonists-of-the-transcriptional-keap1nrf2-gatekeeper(fa9acc9f-63a5-4bb4-9d0e-cbf03ea4f104).html.
Повний текст джерелаАнотація:
Oxidative stress has been associated with numerous degenerative diseases and disorders, as well as cancer and the process of ageing. In higher animals, the response to oxidative stress is largely regulated by the master transcription factor Nrf2, which controls the transcription of cytoprotective genes, and its inhibitor Keap1 which functions as a “sensor” of oxidative stress. Keap1-Nrf2 pathway is known to be conserved across vertebrates and certain invertebrates, but its evolution is yet to be described and it is currently unknown if microbes such as yeasts and bacteria possess this pathway. This thesis examines microbial genomes for evidence of Keap1-Nrf2 pathway, investigates the evolution of this pathway over geological time, and assesses the potential for activation of Nrf2-controlled cytoprotection by microbially produced small compounds. The novel software for identification of distant homologs was developed and utilized to study the homologs of Keap1 and Nrf2 proteins in genomes of animals and microorganisms. The evolution of Keap1-Nrf2 pathway was reconstructed by phylogenetic studies, and the time-frame of evolution was calibrated using the fossil record. The existence of Keap1-Nrf2 pathway in fungi was also examined empirically by utilizing high-throughput proteomics to quantify the stress response mechanisms of an UV-tolerant yeast model. Structure based virtual screening was employed to identify microbial natural products with potential to activate human Nrf2 pathway by inhibiting the Keap1-Nrf2 binding, and the prospective in-silico activators of Nrf2 were tested in vitro by fluorescence polarisation and thermal shift assays to detect competitive inhibition of human Keap1-Nrf2 binding. In-silico analyses identified that the Keap1-Nrf2 pathway exists in all major eukaryotic phyla, ranging from fungi to mammals, and that Nrf2 evolved under a selective pressure incurred by the rise of oxygen levels over geological time. The in-silico virtual screen identified the potential for competitive inhibition of Keap1-Nrf2 binding by mycosporine-like amino acids (MAAs), small compound UV-protective and antioxidant metabolites of marine microorganisms. This activity of MAAs was tested empirically, and the MAAs shinorine and porphyra-334 were confirmed to competitively inhibit the human Keap1-Nrf2 interaction in vitro. The results presented herein indicate that natural products of microorganisms, such as MAAs, are the prospective compound leads for the design of novel therapeutics to target activation of the human Keap1-Nrf2 pathway for treating degenerative diseases of oxidative stress, whilst avoiding the off-target effects of currently utilized Nrf2 activators.
11
Lázaro, López Iolanda. "Regulació de fabp4 depenent de nrf2 en macròfags." Doctoral thesis, Universitat Rovira i Virgili, 2010. http://hdl.handle.net/10803/8886.
Повний текст джерелаАнотація:
Els macròfags desenvolupen un paper clau en la formació de la lesió d'ateroma. Les LDL oxidades (LDLox) indueixen l'expressió de la adipocyte fatty acid-binding protein (FABP4) en els macròfags, fet que constitueix un dels desencadenants de l'evolució d'aquestes cèl·lules al fenotip de cèl·lula escumosa. Les LDLox són una font d'aldehids, que són els productes finals de l'oxidació dels àcids grassos poliinsaturats. El treball realitzat ha estat dissenyat per provar la hipòtesi de la participació dels aldehids en la inducció de l'expressió de FABP4 en macròfags. A causa del caràcter prooxidant d'aquestes espècies, s'ha avaluat si aquesta inducció podria relacionar-se amb el sistema antioxidant cel·lular dirigit pel factor de transcripció Nrf2. El treball experimental es va dur a terme amb monòcits de la línia cel·lular THP-1 que es van diferenciar a macròfags mitjançant èsters de forbol. Els aldehids apolars estudiats van ser el 2,4-decadienal (DDE) i l'hexanal. La valoració dels efectes sobre les expressions gènica i proteica de FABP4 es va realitzar per RT-PCR a temps real i western blot, respectivament. Ambdós aldehids van produir augments en l'expressió gènica i proteica de la FABP4 en els macròfags. L'estudi in silico del promotor de la FABP4 humana va revelar la presència d'un possible lloc antioxidant response element (ARE) per la unió de Nrf2 amb un elevat grau d'homologia amb la seqüència consens. L'assaig d'immunoprecipitació de la cromatina va confirmar al unió in vivo de Nrf2 a aquest lloc ARE. L'estudi de l'efecte dels aldehids sobre l'activació del factor de transcripció Nrf2 va evidenciar un comportament diferencial entre els dos compostos. El DDE augmentava la forma fosforilada i activa de Nrf2, mentre que l'hexanal no produïa cap efecte. Es va provar que en l'activació de Nrf2 produïda pel DDE estaven implicades dues de les principals vies de senyalització intracel·lular: PI-3k/Akt i ERK-MAPK. Considerant els resultats obtinguts, podem suggerir un nou paper de la via Nrf2-ARE com a desencadenant de la formació de cèl·lules escumoses a través de la inducció de FABP4 en resposta a l'oxidació. Aquests resultats proposa la via de Nrf2 com a nova diana per la intervenció terapèutica dirigida a la prevenció i el control del desenvolupament de l'aterosclerosi.Macrophages play a crucial role in the development of atherosclerosis. It has been shown that oxidized LDL (oxLDL) induces adipocyte fatty acid-binding protein (FABP4) in human macrophages, which constitutes one of the major contributors to foam cell formation. oxLDL is a source of apolar aldehydes formed as end-products of polyunsaturated fatty acid oxidation in LDL. This thesis has been designed to study the hypothesis that apolar aldehydes participate in the induction of FABP4 expression in human macrophages. According to the prooxidant nature of these species, we have assessed whether FABP4 expression could be related to the cellular antioxidant system leadered by the transcription factor Nrf2. The experimental procedure was mainly performed by using human monocytic leukemia THP-1 cells which were differentiated to macrophages through a 72-hour phorbol ester treatment. 2,4-decadienal (DDE) and hexanal were the two apolar aldehydes studied. Reverse transcription and real time-PCR (RT-rtPCR) and Western blotting were used to assess FABP4 mRNA and protein expression, respectively. Both aldehydes produced a markedly increase in FABP4 expression at mRNA and protein levels. In silico analysis of human FABP4 promoter revealed the presence of a putative antioxidant response element (ARE) where Nrf2 could bind. This putative binding site had a high matrix similarity score with the consensus sequence. Chromatin immunoprecipitation (ChIP) assay using an Nrf2-specific antibody confirmed the in vivo binding of Nrf2 to this ARE found in human FABP4 promoter. The assessment of the effect of the two aldehydes on Nrf2 activation evidenced a differential behaviour between DDE and hexanal. Whereas DDE increased nuclear phosphorylated Nrf2 levels, hexanal showed no effect. We observed that two of the major intracellular signal transduction pathways, PI-3k/Akt and ERK-MAPK, are implicated in DDE-induced Nrf2 activation. According to our results, we propose a novel role of Nrf2-ARE pathways as a triggering step on foam cell formation mediated by FABP4 induction in response to oxidation. These results open new therapeutic targets addressed to control arteriosclerosis development.
12
Gjyshi, Olsi. "Role of Nrf2 in KSHV Biology and Oncogenesis." Thesis, Rosalind Franklin University of Medicine and Science, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3712340.
Повний текст джерелаАнотація:
Kaposi’s sarcoma-associated herpesvirus (KSHV), or human herpes virus 8 (HHV8), is a ?2 lymphotropic herpesvirus and is the etiological agent of Kaposi’s sarcoma (KS), primary effusion B-cell lymphoma (PEL), and the multicentric Castleman’s disease (MCD). KSHV malignancies are associated with immune suppression, such as in AIDS or organ transplantation patients, and with certain African and Mediterranean populations.
In an effort to identify host factors involved in the establishment of KSHV infection, we focused on the nuclear factor E2-related factor 2 (Nrf2) a member of the Cap’n’Collar basic leucine zipper (bZIP) family of transcription factors. Nrf2 is induced by ROS, and has been shown to play an important role for infection by several viruses. Moreover, Nrf2 activation leads to the expression of a cohort of genes involved in apoptosis, angoigensis, metastasis, drug resistance, and the proliferative pentose pyrophosphate pathway (PPP) enzymes. Interestingly, several of these pathways are upregulated during KSHV infection through unknown mechanisms. Because KSHV infection, like other viruses that activate Nrf2, induces ROS, a powerful activator of Nrf2, we hypothesized that KSHV infection of target cells activates Nrf2 in order to induce Nrf2 target genes and create a microenvironment conducive to infection and tumorigenesis. To this end, we utilized cellular models to assess Nrf2 activity during de novo and latent KSHV infection, the mechanism of its activation, and its role in host and virus biology.
In the first part of this study, we found that Kaposi's sarcoma (KS) skin tissue exhibited elevated Nrf2 levels compared to healthy skin tissue. De novo infection of endothelial (HMVEC-d) cells showed that ROS were essential for Nrf2 activation during the early stages of infection, but dispensable during latency, where the COX-2/PGE2/PKCζ axis played an essential role in the sustained activation. Interestingly, Nrf2 was essential for optimal COX-2 expression, a major pro-viral agent during KSHV infection, establishing a feed-forward loop between COX-2 and Nrf2 in KSHV biology. Nrf2 activation was also necessary for the KSHV-mediated induction of host Bcl-2, VEGF, and the PPP enzymes. Nrf2 colocalized with LANA-1 and the KSHV genome during latency, and played an important role in proper lytic (ORF50) and latent (ORF73) gene expression. This study demonstrated for the first time that KSHV induces Nrf2 during de novo infection of endothelial cells to aid with establishment of latency.
In the second part of the study, we focused on long-term-infected telomerase-immortalized endothelial cells (TIVE-LTC), which provide a model of prolonged KSHV latency. We determined that ROS did not affect Nrf2 activity in these cells. More interestingly, we identified the existence of two simultaneous Nrf2 activating pathways. The first, the non-canonical pathway, involved the autophagic protein p62-mediated sequestration of the Nrf2 inhibitor Keap1, promoting intracellular Nrf2 protein accumulation. A second activating pathway involving the COX-2/PGE2/PKCζ axis further induced Nrf2 activation and phosphorylation, which was necessary for sustained expression of Nrf2 target genes, including GCS, NQO1, xCT, VEGF and IL6, all important agents in KSHV infection and oncogenesis.
In the third part of the study, we shifted our attention to KSHV latency in PEL models. We determined that histopathological tissue obtained from PEL of the stomach exhibited significant Nrf2 activation. Investigation of PEL-derived cell lines revealed that the COX-2/PGE2/PKCζ axis required prostaglandin E receptor 4 (EP4) activation, which acted as the receptor used by PGE2 to activate Nrf2. Next-generation RNA sequencing (NGS) and qPCR experiments revealed that Nrf2 knockdown or inhibition with the chemical Brusatol resulted in elevated global lytic gene expression. Additionally, we identified a novel regulatory mechanism of the major lytic regulatory gene, ORF50, that involved Nrf2, viral LANA-1 and the host transcriptional repressor KAP1. We determined that Nrf2 played a crucial role in the ORF50-mediated lytic burst during early de novo infection, an effect that is repressed in latency by LANA-1 recruitment of KAP1 to the ORF50 promoter in an Nrf2-dependent manner. (Abstract shortened by UMI.)
13
Liddell, Mary Katherine. "Nrf2 in metabolic related inflammation in the brain." Thesis, University of Dundee, 2015. https://discovery.dundee.ac.uk/en/studentTheses/071665a4-1d42-450c-ad49-854ead5d6814.
Повний текст джерелаАнотація:
Novel approaches are required to address Alzheimer’s disease (AD) in our ageing population, with recent interest focused on inflammation and oxidative stress (OS). Disruption of NF-E2-related factor 2 (Nrf2) signalling increases OS and promotes AD. Amyloid precursor protein (APP) is intimately linked with AD, with the Swedish mutation (hAPPswe) used in numerous transgenic models. Furthermore, increasing importance has been placed on the suggested link between nutritional status and AD. To assess Nrf2 as a potential target in AD, we examined the effect of metabolic stress, by chronic high fat (HF) feeding or acute lipopolysaccharide (LPS) treatment on the brains of aged WT, Nrf2-/-, hAPPswe and Nrf2-/-/hAPPswe mice. Nrf2-/- mice displayed impaired enthorinal cortex-dependent cognition, with raised basal hippocampal inflammation. The inflammatory state was attenuated by chronic HF feeding, whilst maintaining insulin sensitivity. In contrast, hAPPswe did not display an inflammatory response to HF feeding, but demonstrated impaired insulin signalling; in line with AD-associated insulin resistance. Additionally, Nrf2-/- mice display increased glial cell activation and activation of mitogen activated protein kinases and mitochondrial impairment. These may be indicative of OS-induced cellular dysfunction and is supported by an aggravated response to LPS, which potentiates IL-1β production. Furthermore, despite an attenuated LPS response following the induction of tolerance, Nrf2-/- mice maintain glial cell activation following treatment which may be suggestive of a primed immune environment within the brain. In conclusion, these data indicate altered glucose homeostasis in both Nrf2-/- and hAPPswe mice, as previously reported. Further, we advocate that Nrf2 plays a key role in mitochondrial function and health and may be important for the ameliorative effects of HF feeding. Taken together, mitochondrial dysregulation and associated OS may help explain the development of cognitive impairment in Nrf2-/- mice. This may be relevant for AD given the age-dependent decline in Nrf2 expression in humans.
14
Ponsford, A. H. "A systematic analysis of the human Nrf2 network." Thesis, University of Liverpool, 2016. http://livrepository.liverpool.ac.uk/3001771/.
Повний текст джерелаАнотація:
Nrf2 is the main transcriptional controller of cellular oxidative stress responses. This is achieved by driving the transcription of a battery of cytoprotective genes that possess a characteristic Antioxidant Response Element (ARE) sequence in their upstream promoter regions. As such, the Nrf2 signalling pathway plays a vital role in health, aging and disease. Defects in Nrf2 activity can lead to impaired mitochondrial function and reduced protection against free radical damage. Over time these effects contribute to common age-related conditions including cardiovascular disease, neurodegeneration and chronic inflammatory conditions. Despite the well-characterised cytoprotective role of Nrf2, inappropriate over or under activation of Nrf2 signalling can also be detrimental. It is therefore important to develop a better understanding of how Nrf2 signalling networks may be regulated. For that reason, the primary aim of this project was to provide a better systems level contextual understanding of Nrf2 signalling in human cells, by generating an improved high-density experimentally defined human Nrf2-centric protein-protein interaction network. Under normal basal conditions Nrf2 binds to Keap1, a component of the Cul3/Rbx1 ubiquitin ligase complex, resulting in a constant process of Nrf2 ubiquitination and proteasomal degradation. However, under conditions of oxidative stress or pharmacological intervention, Keap1 becomes modified, thus altering the interaction with Nrf2 and allowing newly synthesised Nrf2 to be transported into the nucleus, resulting in the transcription of a diverse range of ARE-driven cytoprotective genes. While this simple process appears to operate in most cells, Nrf2 and Keap1 both have many more known and predicted interaction partners. Additionally, other components of the Nrf2 cascade are known to interact with components of other pathways and signalling networks such as the NF-ĸB complex. Currently it is not clear which of these interactions are competitive, sequential or conditional; or how these proteins may work together in multi-protein complexes. By addressing these questions we will be able to provide better insight into the detailed molecular mechanism of Nrf2 signalling and the potential effects of crosstalk between different signalling cascades in human cells. Protein-protein interaction (PPI) networks can also provide insight into the function of uncharacterised proteins and can guide future hypothesis driven research into protein function and the regulation of complex biological processes. PPI data for Nrf2 remains unclear and incomplete, therefore a predicted Nrf2 PPI network was initially generated from publically available datasets, an ‘in-house’ interactome and from literature. The yeast two-hybrid system was then initially employed to test 135 predicted binary interactions and identify novel Nrf2 interaction partners. A combination of secondary interaction methods and transcriptional activity assays were then used to assess confidence limits for Nrf2 partner interaction profiles. Finally, conditional changes in Nrf2 protein complex profiles were investigated in a series of Affinity Purification coupled with Mass Spectrometry assays. This study identified 98 novel experimentally defined binary Nrf2 interaction partners using the yeast two-hybrid assays, together with 96 novel interactions from the Mass Spectrometry studies. This increased the complexity of the binary Nrf2 PPI network by almost 4-fold, and the total Nrf2 interactome by 3.7- fold. This Nrf2-centric network can be used to guide future hypothesis driven research into the physiological mechanisms and functional relevance of these interactions, providing a more in-depth understanding of the molecular mechanisms of Nrf2 regulation and pathway crosstalk in human cells.
15
Hérou, Mathias, and Ragnar Boll. "Bestämning av vattenytor med hjälp av Nätverks-RTK och totalstation : Inmätning av Karlbergsån i Grums kommun." Thesis, Karlstads universitet, Fakulteten för samhälls- och livsvetenskaper, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-6118.
Повний текст джерелаАнотація:
This report is presenting an approach that can be used to measure water surfaces in difficult conditions caused by dense vegetation and lack of nearby known points. The objective was to make a contribution to necessary measures for adaptation against floods in Grums Municipality along the stream Karlbergsån, which may occur when persistent rain raises the level of the stream. Along the river there are low-lying areas prone to flooding. According to Grums Municipality, the stream may widen where the water level differences are large, to create a better flow path and to counteract flooding. Grums Municipality was also interested in survey stormwater discharges which may affect the water level in the stream. The requirement for measurement accuracy must be reached is less than 0.1 m in height with the maximum of 10 m between the measured points in plane. The question we asked ourselves was: "How can an area be measured when there is a lack of nearby known fixpoints and when the visibility to satellites is poor due to dense vegetation?" To be able to measure the area, we established a net of temporary fixpoints with NRTK , which later was used for the measuring of water surfaces and stormwater discharges by using total station. For measuring, both prism and reflectorless measurement have been used. Coordinates for the net of temporary fixpoints, input water levels and storm water discharges are presented and the report files and coordinates for station establishment. Graphic elevation profiles of water levels are registered. Visualization was created by using aerial photographs and measured data showing the entire surveyed area, including free station establishment with directions to the reference points together with the measured fixpoints and stormwater discharges. We believe we have come below the accuracy requirement of 0.1 m and sought a distance between points at less than 10 m but in some places where the measurements were limited the distance is greater than 10 m.
16
Genard, Romain. "Rôle du facteur de transcription Nrf2 dans l'immunomodulation induit par les adjuvants vaccinaux." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS230/document.
Повний текст джерелаАнотація:
Les adjuvants vaccinaux permettent d’augmenter la réponse immunitaire dirigée contre un antigène donné. Certains de ces adjuvants miment des signaux de danger, tels que des agonistes des récepteurs de l’immunité, les récepteurs Toll-like (TLR) ou les récepteurs NOD-like (NLR), et permettent une activation des cellules dendritiques (DC). Les DC sont essentielles dans la mise en place d’une réponse adaptative contre un antigène : elles acquièrent un phénotype mature, contrôlé par les voies des MAPK et NF-κB, permettant la présentation de l’antigène aux lymphocyte T et l’initiation d’une réponse spécifique. La voie Nrf2/Keap1, impliquée principalement dans la détoxication des xénobiotiques et le contrôle du stress oxydant, peut être activée en réponse à des agonistes des TLR tels que le LPS (agoniste TLR 4). Nous avons mis en évidence qu’un traitement par le R848 (agoniste TLR7/8) ou le MDP (agoniste NOD2) induit la transcription des gènes cibles de Nrf2 dans les DC murines. Nrf2 participe également à la production de cytokines inflammatoires en réponse au LPS et au R848 et jouet un rôle dans la prolifération lymphocytaire induite par les DC pré-traitées avec le MDP. Par ailleurs, Nrf2 contrôle la réponse anticorps spécifiques de l’antigène chez la souris. L’injection d’anatoxine tétanique induit une production d’anticorps plus élevé chez la souris déficiente nrf2 par rapport aux souris sauvages. Cette augmentation de la production d’anticorps est corrélée avec une augmentation du nombre de lymphocyte B dans la moelle osseuse et la rateVaccine adjuvants are able to boost immune response toward antigens when there are simultaneously injected. Some of these adjuvant mimic danger signals, such as Toll like receptors (TLR) agonists or NOD-like receptors agonists, required for dendritic cell (DC) activation. DC are essentiales for adaptative immune response against antigens : they acquire mature phenotype, controlled by MAPK and NF-kB signaling pathway, leading to antigen presentation and specific immune response. The Nrf2/keap1 signaling pathway, mainly involves in xenobiotics detoxication and oxidative stress control, can be activate by TLR agonists, such as LPS (TLR 4 agonist).We showed that R848 (TLR 7/8 agonist) and MDP (NOD2 agonist) could induce Nrf2’s target genes transcription in murines dendritic cells (BMDC). Nrf2 seems also to be part of inflammatory cytokines production in response to LPS or R848 and modulated T lymphocyte proliferation induced by MDP pre-treated BMDC. Moreover, Nrf2 appears to play a role in specific antibodies response against an antigen in mice. . In fact, Tetanus toxoid (TT) injection induces higher titer of antibodies anti-TT in nrf2-/- mice compared to nrf2+/+ mice. This increase is also correlated with more specific B lymphocytes in bone marrow and spleen after TT immunisation
17
Shah, Niraj Mayank. "The role of NRF2 in acute myeloid leukaemia (AML)." Thesis, University of Liverpool, 2018. http://livrepository.liverpool.ac.uk/3022789/.
Повний текст джерелаАнотація:
Acute Myeloid Leukaemia refers to the excess proliferation of myeloid progenitor cells. Whilst the 5-year survival rate is 40% in younger patients, this falls to 5% in patients over 65 and resistance to front-line chemotherapy agents remain a problem. We previously identified NRF2, a regulator of anti-oxidant genes, to be constitutively activated in AML and this correlated with resistance to chemotherapy. Recent studies have also suggested NRF2 also plays a more oncogenic role. To further understand NRF2's role in both chemotherapy resistance and oncogenesis we looked at its ability to regulate miRNA in AML. Using a miRNA array, we identified several miRNAs, including miR-125b and miR-29b, whose expression correlated with that of NRF2 in both cell lines and AML patient samples. Both miRNAs exist as paralogs, in that they contain the same miRNA sequence but exist in different genomic locations and we used qPCR to identify miR-125b1 and miR-29b1 as paralogs regulated by NRF2. Using a reporter assay we confirmed the activity of putative NRF2-ARE binding sites in both miRNA promoters. To understand the function of both in AML we manipulated their expression using miRNA 'mimics' or antagomIRs. Individual manipulation of either miRNA resulted in a slight increase in apoptosis. However, the miRNAs appeared to act synergistically as when expressed simultaneously a significant increase in apoptosis was seen both in cell lines and patient blasts. Manipulation of both miRNA also resulted in the increased sensitivity of AML cells to chemotherapy agents. BAK1, STAT3 and AKT2 were shown to be targets of both miRNAs providing a novel mechanism by which NRF2 expression can affect AML cells. To further study the role of NRF2 in AML we used CRISPR-Cas9 to generate NRF2-deficient cells. CRISPR guide RNA were designed to target NRF2 Exons 1, 2 and genome editing validated in HEK293T cells. Leukaemic cell lines (K562 and THP-1) were virally transduced with guides targeting Exon 4 of NRF2. Once editing was verified clones were derived by growing selected cells in Methycellulose-containing medium. Putative clones were initially screened using MG-132 (to stabilise NRF2) and further confirmed by treatment with the NRF2 inducers CDDO-Me and Sulforaphane. Verified clones were characterised by Sanger Sequencing. In addition to CRISPR-Cas9 we also validated a number of other gene-editing methodologies including CRISPR-Cpf-1 and TALENs. Overall these methodologies represent powerful tools to further characterise the role of NRF2 in AML.
18
Wang, Hui, Xiufei Liu, Min Long, Yi Huang, Linlin Zhang, Rui Zhang, Yi Zheng, et al. "NRF2 activation by antioxidant antidiabetic agents accelerates tumor metastasis." AMER ASSOC ADVANCEMENT SCIENCE, 2016. http://hdl.handle.net/10150/615617.
Повний текст джерелаАнотація:
Cancer is a common comorbidity of diabetic patients; however, little is known about the effects that antidiabetic drugs have on tumors. We discovered that common classes of drugs used in type 2 diabetes mellitus, the hypoglycemic dipeptidyl peptidase-4 inhibitors (DPP-4i) saxagliptin and sitagliptin, as well as the antineuropathic α-lipoic acid (ALA), do not increase tumor incidence but increase the risk of metastasis of existing tumors. Specifically, these drugs induce prolonged activation of the nuclear factor E2-related factor 2 (NRF2)-mediated antioxidant response through inhibition of KEAP1-C151-dependent ubiquitination and subsequent degradation of NRF2, resulting in up-regulated expression of metastasis-associated proteins, increased cancer cell migration, and promotion of metastasis in xenograft mouse models. Accordingly, knockdown ofNRF2attenuated naturally occurring and DPP-4i-induced tumor metastasis, whereas NRF2 activation accelerated metastasis. Furthermore, in human liver cancer tissue samples, increased NRF2 expression correlated with metastasis. Our findings suggest that antioxidants that activate NRF2 signaling may need to be administered with caution in cancer patients, such as diabetic patients with cancer. Moreover, NRF2 may be a potential biomarker and therapeutic target for tumor metastasis.
19
Harder, Bryan, and Bryan Harder. "Molecular and Chemical Modulation of NRF2 for Disease Intervention." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/624590.
Повний текст джерелаАнотація:
Cells are frequently exposed to endogenous and environmental stressors that pose a threat to homeostatic cellular conditions. In response to such stress, the cell activates an adaptive antioxidant response, which is regulated by the transcription factor NRF2 to mitigate the harmful effects of electrophilic or oxidative species. Pharmacological activation of NRF2 has shown to be effective for preventing the initiation and promotion of cancer, neurodegenerative diseases, and other chronic illnesses, leading to the search for more specific molecules that activate this pathway. Intriguingly, because it is a pro-survival factor, NRF2 is frequently found to be deregulated in many cancer types that are resistant to chemotherapy, calling for the use of NRF2 inhibitors as an adjuvant therapy to enhance the effects of primary chemotherapeutic regimens. In this dissertation, detailed molecular studies have identified a new mechanism by which NRF2 can be aberrantly up-regulated in Type 1 endometrial carcinoma. Additionally, key mechanistic approaches were undertaken to understand the biological consequence of the first NRF2 inhibitor, brusatol. Furthermore, strategic approaches to identify novel chemical modulators of the NRF2 pathway were used, using natural products as a primary source. Assessment of the mechanism of action of biological activity for chemical modulators of the NRF2 pathway was of extreme interest, and rational approaches for the use of these compounds for disease intervention based on disease context will be discussed. Strat-MTM is a synthetic model for transdermal diffusion testing made by EMD Millipore and was marketed as a new skin mimetic membrane. It has been reported to be predictive of diffusion in human skin. Independent researchers had evaluated this membrane and compared it with animal and human skin and other polymeric membranes. Yet, there are not a published research to correlate the animal skin and Strat-MTM based on the amount of drug retained after topical application, which is one of the critical criteria for dermal drug delivery system.
In this research, five compounds, with various physiochemical properties, were selected to perform this correlation. Resatorvid, Methyl Para aminobenzoate (M-PABA), Diclofenac sodium, Salicylic acid and hydrocortisone, each one was dissolved in phosphate buffer saline (pH 7.4) in concentrations of 60 ug/ml for resatorvid and 100-120 ug/ ml for others. All experiments were uniform in the setting and made in triplicate.
As a conclusion from the results, the number of tested compounds were shorted to reflect the correlation in flux or permeability coefficient between murine skin and Strat-MTM membrane. With exception of M-PABA, there is a trend of correlation with the percentage of drug retained in dermis layers; however, the number of compounds still low to reflect a real correlation.
20
Wu, Tongde. "Post-Transcriptional Regulation of Nrf2: Novel Mechanisms beyond Keap1." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/301750.
Повний текст джерелаАнотація:
Nrf2 (NF-E2-related factor 2) is a transcription factor that regulates a battery of downstream genes that contain the antioxidant response element (ARE) in their promoter regions, including intracellular redox-balancing proteins, phase II detoxifying enzymes, and transporters. These Nrf2-dependent proteins work in collaboration to protect against many diseases where oxidative stress plays an essential role in disease onset and progression. Consequently, it is imperative to understand the basic molecular mechanisms of how Nrf2 is regulated so that this pathway can be targeted for disease prevention and treatment.Nrf2 is mainly regulated at the protein level by the ubiquitin proteasome system. Under basal conditions Nrf2 is constantly ubiquitinated by the Keap1-Cul3-E3 ubiquitin ligase complex and subsequently degraded by the 26S proteasome. Currently, regulation of the Nrf2-Keap1 pathway by ubiquitination is largely understood. However, other mechanism responsible for modulating Nrf2-ARE signal remains to be explored. This dissertation identifies three molecular mechanisms that are important in understanding how the Nrf2-Keap1 pathway is regulated: (i) In Chapter 2, KPNA6 was identified and characterized as a negative regulatory mechanism of the Nrf2 pathway, which mediates Keap1 nuclear import and represses the Nrf2-dependent antioxidant response at post-induction phase. (ii) In Chapter 3, I identified PARP-1 as a new transcription co-activator of Nrf2, which augments ARE-specific DNA binding of Nrf2 and enhances the transcription of Nrf2 target genes. This indicates a novel function of PARP-1 and reveals another layer of regulation of Nrf2. (iii) In Chapter 4, I demonstrated that XBP1 and SYVN1 are involved in regulating the Nrf2 pathway in a Keap1-independent mechanism. During ER stress, XBP1s upregulates transcription of SYVN1, which is an ubiquitin E3 ligase. SYVN1 accelerates the clearance of Nrf2 protein through promoting ubiquitination of Nrf2, and subsequent proteasomal degradation. Moreover, we observed an inverse correlation between XBP1s/SYVN1 and Nrf2 expression in the end stage alcoholic cirrhosis liver samples, implying a pathological role of ER stress-oxidative stress crosstalk. Taken together, these findings further our understanding of how the Nrf2-Keap1 pathway is regulated, providing novel targets of chemoprevention or chemotherapy.
21
Svensson, Mikael, and Daniel Lidbom. "En kvalitetsjämförelse av NRTK-mätningar med olika GNSS-instrument." Thesis, Karlstads universitet, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-70289.
Повний текст джерела
22
di, BELLO GIORGIA. "Nrf2 Inhibition Is Required To Activate Hepatic Progenitor Cells." Doctoral thesis, Università degli studi di Foggia, 2019. http://hdl.handle.net/11369/382255.
Повний текст джерелаАнотація:
L'attuale trattamento dell'insufficienza epatica è il trapianto di organo. Tuttavia, i costi elevati, la mancanza di donatori, la mortalità correlata al trattamento e l'immunosoppressione a lungo termine rendono questa opzione possibile solo per un numero limitato di pazienti. Il trapianto di cellule staminali del fegato è stato recentemente proposto come trattamento alternativo. L'identificazione dei principali regolatori nella differenziazione delle cellule progenitrici epatiche è determinante per la rigenerazione dell’ organo e può migliorare il trapianto di cellule staminali per la malattia epatica allo stadio terminale. Questo lavoro si basa sullo studio del ruolo che il fattore di trascrizione Nrf2 può avere nella regolazione del destino delle cellule progenitrici epatiche. I nostri dati mostrano che Nrf2 è costitutivamente attivato nelle nicchie delle cellule staminali epatiche per il mantenimento delle stesse, ma è down-regolato nelle lesioni croniche del fegato. L'inibizione in vitro di Nrf2 induce modificazioni morfologiche, fenotipiche e funzionali tipiche degli elementi differenziati. Abbiamo quindi inibito Nrf2 tramite il modulatore di espressione ARE 1 (AEM1) nella linea cellulare umana HepaRG; queste cellule sono state trapiantate in topi SCID/beige somministrati con anticorpi anti-Fas per indurre apoptosi epatocellulare, con conseguente ripopolamento efficace da parte degli epatociti umani e ripristino della funzionalità epatica. Per concludere, questo studio mostra che l'inibizione di Nrf2 porta all'attivazione e alla differenziazione delle cellule progenitrici del fegato. Questo fattore di trascrizione redox-dipendente può dunque rappresentare un potenziale bersaglio per regolare il processo di attivazione e differenziazione in linee specifiche di cellule progenitrici epatiche indifferenziate.The current treatment of liver failure is organ transplantation. Nevertheless, the high costs, lack of donors, treatment-related mortality and long-term immunosuppression make this option possible only for a limited number of patients. Liver stem cell transplantation has been recently proposed as an alternative treatment. The identification of key regulators in hepatic progenitor cell differentiation is determinant for organ regeneration and may improve stem cell transplantation for end-stage liver disease. The present investigation studied the role of the transcription factor Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) in the regulation of hepatic progenitor cell fate. Our data show that Nrf2 is constitutively activated in the hepatic stem cell niches to maintain progenitor stemness, but it is down-regulated in chronic liver injury. The in vitro inhibition of Nrf2 induces morphological, phenotypical and functional modifications typical of differentiated elements. We thus inhibited Nrf2 via ARE expression modulator 1 (AEM1) in the human-derived HepaRG cell line; these cells were transplanted into SCID/beige mice administered with anti-Fas antibody to induce hepatocellular apoptosis, resulting in effective human hepatocyte repopulation with restoration of liver function. To conclude, the present study shows that Nrf2 inhibition leads to the activation and differentiation of liver progenitor cells. This redox-dependent transcription factor may represent a potential target to regulate the commitment of undifferentiated hepatic progenitor cells into specific lineages.
23
ORRU', CLAUDIA. "Nrf2 targeting: a potential therapeutic strategy in hepatocellular carcinoma." Doctoral thesis, Università degli Studi di Cagliari, 2019. http://hdl.handle.net/11584/260483.
Повний текст джерелаАнотація:
The NRF2-KEAP1 pathway is the main intracellular defence against environmental stress, but its dysregulation has been observed in several human cancers, including hepatocellular carcinoma (HCC), one of the most aggressive cancer. However, how exactly aberrant NRF2 activation contributes to malignancy remains elusive.
Aim of the present work is to assess i) whether the activation of the Nrf2-Keap1 pathway is an early event in rat hepatocarcinogenesis and is maintained all along the process, and ii) the molecular alterations underlying the activation of the pathway. Moreover, to directly establish the role of Nrf2 in hepatocarcinogenesis we used the recently developed Nrf2-Knockout (Nrf2-KO) rats.
To this aim, we adopted a nutritional model of rat hepatocarcinogenesis consisting of a single dose of diethylnitrosamine (DENA) followed by a choline-methionine-deficient (CMD) diet for 4 months. This regimen causes extensive triglyceride accumulation, oxidative damage and the onset of preneoplastic lesions. Rats were then placed on basal diet and sacrificed after 6,10 and 13 months from DENA injection. When using Nrf2-KO rats, the animals were subjected to the CMD diet for 6 and 10 weeks following a single injection of DENA.
The results showed that Nrf2 activation occurs since the early steps of hepatocarcinogenesis and persists all along the tumorigenic process even in the absence of the promoting environment generated by the CMD diet. Nrf2 mutations were very frequent at early steps of hepatocarcinogenesis (90%), but their number diminished with the progression of malignancy (25%). Interestingly, while very few mutations of Keap1 and no methylation of its promoter could be found at any stage of the process, accumulation of P62 occurred in HCCs suggesting that activation of Nrf2 at late stages of the process could be a consequence of Keap1 sequestration by p62.
To directly assess the role of Nrf2 in hepatocarcinogenesis, we used a genetic approach consisting of Nrf2-KO rats. The results showed that Nrf2-KO rats, unlike wild-type animals, did not develop preneoplastic lesions after treatment with DENA followed by CMD diet for 6 or 10 weeks. Interestingly, no difference in biotransformation of DENA, DNA alkylation, hepatocellular necrosis or compensatory regeneration was found between WT and KO rats. The latter result demonstrates that while loss of Nrf2 does not inhibit the initiation step of hepatocarcinogenesis, it completely impairs the clonal expansion of initiated cells, suggesting that Nrf2 is critical in the onset of HCC.
24
Machado, Alex Barreto. "Caracterização de sistemas envolvidos nos processos de purificação de biodiesel." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266930.
Повний текст джерелаАнотація:
Orientadores: Maria Regina Wolf Maciel, Martín AznarTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
Made available in DSpace on 2018-08-17T10:23:34Z (GMT). No. of bitstreams: 1 Machado_AlexBarreto_D.pdf: 10485061 bytes, checksum: 1bbe757a7cc410835bff5b7be09c251b (MD5) Previous issue date: 2010
Resumo: Vários são os interesses que têm impulsionado o investimento em novos processos de produção de fontes alternativas de energia: preocupação com o esgotamento de fontes limitadas de petróleo; dependência do mercado brasileiro de recursos estrangeiros, apelo a fontes renováveis de matéria prima e preocupações ambientais (Protocolo de Kyoto). Dentre as alternativas aos combustíveis fósseis, o biodiesel aparece como uma alternativa promissora. O biodiesel pode ser definido como sendo um mono-alquil éster de ácidos graxos derivado de fontes renováveis, como óleos e gorduras, obtido através de processo de transesterificação, no qual ocorre a transformação de triacilgliceróis em moléculas menores de ésteres de ácidos graxos, rendendo como subproduto o glicerol (ou glicerina). O biodiesel encontra-se registrado na Environmental Protection Agency (EPA-USA) como combustível e como aditivo para combustíveis e pode ser usado puro a 100% (B100), em mistura com o diesel de petróleo, por exemplo de 20% (B20), ou em uma proporção baixa (1 a 5%) como aditivo, sendo o seu uso possível sem nenhuma modificação nos motores convencionais. Inúmeros trabalhos vêm sendo desenvolvidos testando diferentes óleos, processos e misturas finais, mas para a correta avaliação destes trabalhos torna-se necessário caracterizar o produto obtido e reconhecer as diferenças presentes nas matérias primas capazes de alterar positivamente o resultado final. Além disso, torna-se necessário entender os equilíbrios líquido-líquido formados com as misturas e estudar os equilíbrios líquido-vapor envolvidos nas destilações necessárias para a purificação do biodiesel. Tais dados não são encontrados na literatura atualmente e inviabilizam a construção de plantas virtuais e a realização de simulações computacionais. Assim, o presente projeto visa apresentar uma caracterização de sistemas envolvidos na purificação do biodiesel, permitindo obter dados de equilíbrios líquido-líquido e líquido-vapor em sistemas contendo etanol, glicerol, biodiesel de óleo de soja (Bio-OS), biodiesel de óleo de mamona ( Bio-OM ), água e catalisador
Abstract: There are several concerns that have driven investment in new production processes for alternative energy sources: concern over the depletion of limited supplies of oil, dependence on the Brazilian market of foreign funds, call for renewable raw materials and environmental concerns (Protocol Kyoto). Among the alternatives to fossil fuels, biodiesel appears as a promising alternative. Biodiesel can be defined as a mono-alkyl ester of fatty acids derived from renewable sources such as vegetable oils and animal fats obtained through transesterification process, which occurs in the transformation of triacylglycerols into smaller molecules of fatty acid esters, yielding as a byproduct glycerol (or glycerin). Biodiesel is registered with the Environmental Protection Agency (EPA-USA) as fuel and fuel additive and can be used at 100% (B100), mixed with petroleum diesel, for example, 20% (B20) or in a low proportion (1-5%) as an additive, which makes their use possible without any modification in conventional engines. Numerous studies have been developed by testing different oils, processes and final mixtures, but for proper assessment of this work, it is necessary to characterize the product and recognize the differences present in the raw materials that can positively change the outcome. Moreover, it is necessary to understand the liquid-liquid equilibria formed with the mixtures and to study the vapor-liquid equilibria involved in distillation required for the purification of biodiesel. Such data are not found in the open literature and currently hinder the construction of virtual plants and conducting computer simulations. Thus, this project aims to present a characterization of systems involved in the purification of biodiesel, allowing to get data from liquid-liquid equilibria and vapor-liquid systems containing ethanol, glycerol, biodiesel from soybean oil ( Bio-SO) and biodiesel from castor oil ( Bio-CO), water and catalyst (NaOH)
Doutorado
Desenvolvimento de Processos Químicos
Doutor em Engenharia Química
25
Ao, Hei Sio. "Investigation of Cis and Trans-acting Transcriptional Regulatory Factors and Signaling Pathways of Parkin." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/33368.
Повний текст джерелаАнотація:
Parkin gene is associated with the development of autosomal recessive juvenile parkinsonism (Kitada et al., 1998) which is a common form of familial Parkinson’s disease (Klein and Schlossmacher, 2006). Since Parkin has multiple cell protective effects, increasing the expression level of Parkin in the brain might be able to rescue cells in danger, which in turn might prevent or slow down the development of Parkinson’s disease (Ulusoy and Kirik, 2008).
In order to increase Parkin expression, it is important to understand the transcriptional mechanisms regulating Parkin expression (Maston et al., 2006). Since human Parkin is very big (~1.4 Mb) (Asakawa et al., 2001), in this study we use the smaller Fugu parkin gene, which is an ortholog of human Parkin (Yu et al., 2005), to search for the transcriptional factors and signaling pathways regulating Parkin expression. We have cloned vertebrate constructs that allow for the monitoring of an entire genomic Fugu parkin gene tagged with a reporter (eGFP or luciferase) in mammalian cells; and have established cellular model for studying the expression.
According to the “TRANSFAC” transcription factor database, as well as “TFBIND” and “TFSEARCH” softwares (Wingender et al., 1996; Heinemeyer et al., 1998; Heinemeyer et al., 1999; Tsunoda and Takagi, 1999; Akiyama 1995), potential Nrf2 binding sites are conserved in the promoters of mammalian parkin (including human Parkin and mouse parkin) and in Fugu parkin. In this study, we could not find a link between the presence of the potential Nrf2 binding site(s) in the parkin promoter and the up-regulation of parkin; and we could not find an association between the Nrf2 pathway activation and the induction of parkin under the specific experimental conditions.
26
Ebisine, Kimimuepigha. "Dual regulation of transcription factor Nrf2 by Keap1 and the beta-TrCP/GSK-3 in cancer." Thesis, University of Dundee, 2019. https://discovery.dundee.ac.uk/en/studentTheses/20338051-4e92-417e-aeb1-4cd3dc86eda4.
Повний текст джерелаАнотація:
Cancer is one of the foremost causes of death worldwide with about 14.1 million new incidences and 8.2 cancer related deaths occurring globally. NF-E2 p45-related factor 2 (Nrf2), a cap-'n'-collar basic leucine zipper (CNC-bZIP) transcription factor, prevents carcinogenesis through expression of genes that ensure the excretion, enzymatic modification, and repair of oxidative damage in cells containing the antioxidant response element (ARE) in their promoter region. Beyond providing cytoprotection against oxidative stress and xenobiotics, Nrf2 pays a role in maintaining basic physiological processes such as energy metabolism and cell cycle regulation. Whilst Nrf2 plays a pivotal role in preventing degenerative and inflammatory disease, upregulation of Nrf2 promotes tumourigenesis in cancerous cells. Therefore, understanding the mechanisms controlling Nrf2 activity is important in translational medicine. Nrf2 is regulated by proteasomal degradation by Kelch-like ECH-associated protein 1 (Keap1) an E3 ubiquitin ligase substrate adaptor protein that recruits of cullin-3 (Cul3) to Nrf2 via its Neh2 domain. Nrf2 is also negatively regulated by phosphorylation by glycogen synthase kinase-3 (GSK-3) causing β-transducin repeat-containing protein (β-TrCP) to ubiquitinate Nrf2 by Skp1-Cul1-F-box (SCF) ubiquitin ligase through the Neh6 domain of Nrf2. Several research groups have shown that induction of ARE-driven genes can be regulated by phosphoinositide 3- kinase- protein kinase B (PI3K-Akt/PKB) signalling pathway. The ability of tert-butylhydroquinone (tBHQ), 1-[2-cyano-3,12-dioxooleana-1,9(11)-diene-28-oyl]imidazole (CDDO-Im), diethyl maleate (DEM), curcumin, carnosol, ferulic acid and sulforaphane (SFN) to activate Nrf2-target genes in a Keap1-dependent or Keap1-independent manner was tested. It was discovered that all compounds, except for SFN, activate Nrf2-target genes in a Keap1-independent manner, inhibiting GSK-3 and functioning through the Neh6 domain of Nrf2. Analysis of the involvement of PI3K-Akt/PKB pathway in Nrf2 activation revealed that regulation of Nrf2 through the PI3K-Akt/PKB pathway is independent of Keap1 but dependent on GSK-3. Also, it was shown that tBHQ, DEM, CDDO-Im, curcumin, ferulic acid directly decreased phosphatase and tensin homolog (PTEN) activity, thereby preventing formation of the phosphodegron in the Neh6 domain of Nrf2. With increased Nrf2 levels reported in various cancers including lung cancer, leading to the progression of these cancers, Nrf2 can be seen as a double-edged sword. Loss-of-function somatic mutations in KEAP1 as well as somatic mutation in NFE2L2 has been reported in several human cancers playing a role in the development of such cancer. Using short hairpin RNA (shRNA) and the CRISPR/Cas9 system to generate stable Nrf2 knockdown A549 and H460 cells, the second part of this thesis investigated biochemical and physiological changes that occur, when the Nrf2 is genetically downregulated, and further on to determine what mechanism(s) is responsible for decreased cell proliferation in tumours. The findings obtained confirm that downregulation of Nrf2 from the human non-small lung adenocarcinoma epithelial cell line A549 and H460, in which Nrf2 is upregulated though somatic mutations in KEAP1, results in decreased cell proliferation. Analysis of the genes involved in NADPH generation and pentose phosphate pathway (PPP) show that decrease in Nrf2 caused a decrease in the expression of genes involved in PPP. Although knockdown of Nrf2 resulted in a decrease in cell proliferation, it was shown that this decrease was not as a result of cell death. Nrf2 is able to control cell proliferation by induction of metabolic reprogramming geared towards favoring anabolic pathways and influencing the PPP as well as provide energy source required for cell proliferation.
27
Wongpaiboonwattana, Wikrom. "The regulation of mouse embryonic stem cell differentiation by Nrf2." Thesis, University of Dundee, 2017. https://discovery.dundee.ac.uk/en/studentTheses/7d0c02fe-07bc-4f2c-8c15-03d23d788840.
Повний текст джерелаАнотація:
Embryonic stem (ES) cell maintenance and differentiation are dynamic processes controlled by various intrinsic and extrinsic factors. Identifying these factors will enhance the understanding about developmental process and improve the application of stem cells in clinic. Previous studies highlight a shift between non-oxidative and oxidative energy metabolism to play roles during differentiation. Oxidative metabolism is a major source of reactive oxygen species (ROS) which is regulated by a cytoprotective transcription factor, Nuclear factor erythroid 2-related factor 2 (Nrf2). Therefore, this study investigate relationship between metabolism, ROS, and Nrf2 during mouse ES cell differentiation. In vitro models representing early lineage differentiation were used. By measuring metabolic profiles, ROS, and Nrf2 levels from the models, Nrf2 was found related to pluripotency and ROS. However, relationship among metabolism and Nrf2 or ROS could not be detected. Gain- and loss-of-function experiments by pharmacological activator, short hairpin RNA knockdown, and CRISPR-Cas9 genome editing showed that Nrf2 could promote pluripotency and inhibit differentiation, especially during early differentiation toward neural lineage. This study suggested a new player in transcription control that governs pluripotency and differentiation.
28
Torrente, Fernandez Laura. "An autoregulatory loop between NRF2 and HIPK2 shapes cytoprotective responses." Thesis, University of Dundee, 2017. https://discovery.dundee.ac.uk/en/studentTheses/2a797f28-04f5-4cd5-9a9b-fee2fe25c999.
Повний текст джерела
29
Lim, Pei Jin. "Interactions between the Nrf2 antioxidant response and mammalian iron homeostasis." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:c6516835-43c1-45bd-86b1-532116e36aa8.
Повний текст джерелаАнотація:
Iron is an essential micronutrient as it contributes to the oxygen-carrying capacity of blood and is a cofactor for many enzymes. However, excess iron is toxic as it promotes the formation of reactive oxygen species (ROS), which react with and alter the functions of biomolecules. Moreover, there is no regulated iron excretion mechanism from our body. Hence, iron homeostasis is tightly regulated by the hormone hepcidin that restricts iron absorption and controls iron distribution in the body. Accumulation of iron in the liver increases the expression of bone morphogenetic protein-6 (Bmp6), which induces hepcidin synthesis via Bmp responsive elements in the hepcidin promoter. The mechanism by which excess iron is 'sensed', leading to increased Bmp6, is unknown. Since excess iron induces oxidative stress, we hypothesized that Bmp6 expression is upregulated during iron-overload via the Nrf2-driven antioxidant response pathway. Nrf2 is a transcriptional activator that is activated by oxidative stimuli and binds to antioxidant responsive elements (AREs) to induce the expression of a battery of ARE-regulated antioxidant genes. Bach1 is a transcriptional repressor that binds AREs and suppresses gene expression. Haem can induce the degradation of Bach1 and derepress the expression of ARE-regulated genes. In this thesis, we demonstrated the simultaneous induction of Bmp6 and classical Nrf2/ARE-driven genes in mice and cell lines by iron and hemin (haem-chloride). ChIP-sequencing analyses showed binding of Nrf2 to a conserved ARE within intron 1 of Bmp6. The antioxidant mitoTEMPO blunted the activation of Nrf2 and upregulation of Bmp6 by iron. Furthermore, siRNA-mediated knockdown of Nrf2 decreased basal Bmp6 expression and inhibited the upregulation of Bmp6 by iron in vitro, whereas knockdown of Bach1 increased Bmp6 expression. Similarly, the upregulation of Bmp6 and hepcidin expression was blunted or completely abrogated in several models of iron overloading in Nrf2-knockout mice. Nrf2-knockout mice were more prone to iron accumulation and susceptible to oxidative stress-induced liver damage. Deletion of Nrf2 in Hfe-knockout haemochromatosis mice, and a SNP associated with reduced NRF2 expression in HFE-hereditary haemochromatosis patients, worsened the iron accumulation phenotype; conversely, pharmacological activation of Nrf2 upregulated the Bmp6/hepcidin axis and alleviated iron accumulation and oxidative stress in Hfe-knockout mice. In summary, Nrf2 links cellular and systemic iron homeostasis, is required for the upregulation of Bmp6 by iron, and is an important modifier and therapeutic target for iron overload disorders.
30
Lo, Shih-Ching. "Regulation of Nrf2 by a keap1-dependent E3 ubiquitin ligase." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4699.
Повний текст джерелаАнотація:
Thesis (Ph.D.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 11, 2009) Includes bibliographical references.
31
Tyle, Robert. "Metoder för att etablera fri station : En jämförelsestudie av GNSS-etableringar och traditionell etablering." Thesis, Karlstads universitet, Institutionen för miljö- och livsvetenskaper, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-55235.
Повний текст джерелаАнотація:
Syftet med detta examensarbete är att jämföra kvaliteten som erhålls vid olika typer av fri stationsetablering. Tre olika metoder har jämförts vilka är etablering mot kända stompunkter (traditionell metod), etablering mot GNSS-bestämda punkter med snabb metod och etablering mot GNSS-bestämda punkter med långsam metod. Den snabba metoden går ut på att mäta in en punkt med fem (5) positionsbestämmelser med GNSS samtidigt som totalstationen mäter in punkten som ett bakåtobjekt. Varje punkt behöver då besökas endast en gång. Den långsamma metoden går ut på att mäta in alla punkter som ska användas som bakåtobjekt med tjugo (20) positionsbestämmelser med GNSS, för att därefter mäta in dem med totalstation. Varje bakåtobjekt måste då besökas två gånger. Arbetet utfördes i Arvika kommun. Tre stompunkter användes som huvudsakliga bakåtobjekt. Dessa punkter användes som bakåtobjekt för att jämföra kvaliteten på GNSS-mätningarna relativt de sanna koordinaterna på stompunkterna vilka hämtas från respektive punktbeskrivning. Olika antal bakåtobjekt mättes in med GNSS för att undersöka hur kvaliteten förändrades i takt med att fler bakåtobjekt tillkom. Fri stationsetablering genomfördes i varje metod med tre, fem och sju bakåtobjekt. Det gjordes tre mätomgångar för att kunna jämföra mätningarna med varandra. Slutsatser som dras är att vid uppdatering av primärkartan räcker det med att använda den snabba GNSS-metoden tillsammans med tre bakåtobjekt för att uppnå tillfredsställande kvalitet. Vid finutsättning bör den långsamma metoden med fem bakåtobjekt användas istället. Arbetet beskriver även teorin bakom GNSS-tekniken och fri station.The purpose of this degree project is to compare the quality obtained from different types of free station establishment. Three different methods have been compared. The methods are establishing towards control points (traditional method), establishing towards GNSSdetermined points with a fast method and establishing towards GNSS-determined points with a slow method. The fast method is to measure a point with five (5) positions with GNSS while the total station measures the point as backsights simultaneously. Using this method each point needs to be visited only once. The slow method is to first measure all points to be used as backsights with 20 positions with GNSS, then return to each point and measure them with the total station. Each point must then be visited twice. Three control points in the city of Arvika were used as backsights. It was also those points that were measured with GNSS to compare the quality of GNSS measurements relative to their "true" coordinates extracted from the point description. Different number of backsights were used to investigate how the quality changed as more backsights were added. Free station establishment was performed with each method using three, five and seven backward objects. Three measuring rounds were made to compare the measurements in each round with each other. Conclusions drawn are that, when updating the primary chart, it is sufficient to use the fast GNSS method along with three backsights to achieve satisfactory quality, but in construction measuring where the quality needs to be very high the slow method with five backsights should be used instead. The work also describes the theory behind GNSS technology and free station.
32
Håkansson, Linn, and Elenore Herrström. "Transformerade koordinater i referenssystemet SWEREF 99." Thesis, Högskolan Väst, Avdelningen för data-, elektro- och lantmäteriteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-8923.
Повний текст джерелаАнотація:
Sverige är uppbyggt av fastigheter och en fastighet avgränsas med hjälp av punkter, exempelvis dubb i berg eller rör i mark. Fastighetsgränsers fysiska läge stämmer inte alltid överens med koordinaterna i referenssystemet, vilket resulterar i avvikelser. Genom åren har flera referenssystem använts och vid varje byte genomförs en transformation mellan till- och frånsystemet. Idag är SWEREF 99 det mest tillämpade referenssystemet i Sverige vid mätning i plan. Syftet med studien var att utreda gränspunkter och stompunkter i del av området Ammenäs, Uddevalla kommun. Frågor som besvaras är: Hur väl stämmer de angivna, transformerade, koordinaterna i referenssystemet SWEREF 99 med gränspunkters och stompunkters fysiska läge? Vad kan vara orsaken till eventuella avvikelser? Påverkar eventuella avvikelser detpraktiska arbetet och vad kan de ge för effekter samt går det att komma till rätta med dem? Genom studien har både kvalitativ och kvantitativ metod tillämpats. Den kvalitativa metoden har används för faktainsamling, både via litteratur och genom intervjuer samt mailkontakt med personal på Uddevalla kommun. Den kvantitativa metoden användes för inmätning av fastighetsgränser och stompunkter. Insamlad mätdata jämfördes med de angivna koordinaterna i referenssystemet SWEREF 99. Resultatet har visat att avvikelser finns mellan de fysiska gränspunkterna och de angivnakoordinaterna i referenssystemet SWEREF 99. Stompunkterna i området stämmer dock väl överens med referenssystemet och därför kan det uteslutas att stompunkterna i systemet gett upphov till gränsernas avvikelser. Under studien har det framkommit att spänningar existerade redan under 1940-talet och de har sedan följt med i de olika referenssystemsbyten som gjorts genom åren. Spänningar kan uppkomma vid sammankoppling av olika stomnät och ge upphov till avvikelser vid mätning. Stomnätet i området är etablerat efter att de första fastigheterna bildades. Inför transformationen till SWEREF 99 utfördes stödmätning endast på stompunkterna, sålunda har alla gränspunkter transformerats tillsammans med punkterna. För att komma tillrätta med gränsernas avvikelser krävs en ny transformation där stödmätning görs även på gränspunkter. Då avvikelserna inte påverkar det praktiska arbetet i Ammenäs finns dock inga planer på att en sådan process ska genomföras för området.Sweden is made up of properties and a property is bounded by means of markings, such as stud in rock or pipes in the ground. The physical location of a property's bounds does not always correspond with the coordinates in the reference system, resulting in discrepancies. Through the years, several reference systems has been used, and with each change implemented, a transformation between the old and the new system is done. Today SWEREF 99 is the most applied reference system in Sweden when measuring in the plane.The purpose of this study was to investigate the boundary markers and reference points in part of the area of Ammenäs in Uddevalla municipality. Questions to be answered is: How well does the physical boundary markers and the reference points correspond with the transformed coordinates in the reference system SWEREF 99? What can be the cause ofdifferences? How do deviations affect the practical work with ordinances in the area and how can these be overcome? Through the study, both qualitative and quantitative methodology were applied. The qualitative method has been used for fact collection, both through literature and through interviews and e-mail contact with staff at Uddevalla municipality. The quantitative method was used for the measurement of property boundaries and reference points. Collected data were compared with the coordinates in the reference system SWEREF 99. The results have shown discrepancies between the physical boundary markers and the transformed coordinates in the reference system SWEREF 99. Reference points in the area are consistent with the reference system. The gist of the result is that reference points in part of the area has not given rise to the boundary deviations. The study has revealed that discrepancies existed already in the 1940s, the deviations have since followed in the different reference system changes made over the years. Discrepancies can occur at the interconnection of different core networks and can cause differences in the measurement. The reference network was established in the area after the first properties were formed. Before the SWEREF transition only support measurement on the reference points was performed. To deal with the discrepancies, a new transformation which also supports measurements at boundary markings are needed. Since the deviations do not affect the practical work in Ammenäs, such a process will not take place.
33
Wheeler, Joel. "USING SOUTHERN BLOTTING AND NON-RADIOACTIVE PROBE HYBRIDIZATION AS A TOOL TO MEASURE 2’,3’-DIDEOXYCYTIDINE INDUCED MITOCHONDRIAL DNA DEPLETION IN HUMAN CELL LINES." OpenSIUC, 2019. https://opensiuc.lib.siu.edu/theses/2637.
Повний текст джерелаАнотація:
Mitochondria are membrane bound organelles important for energy production in respiring cells through the process of oxidative phosphorylation. They have their own multi-copied mitochondrial DNA (mtDNA) genome separate from that in the nucleus that is needed for mitochondria to function properly and can exist in both wild type and mutant forms in the same cell. The integrity of the mtDNA is therefore of vital importance for the survival of the organism and as such understanding the mechanisms of mtDNA maintenance is relevant to human health and disease. This study employs a Southern blotting and non-radioactive probe method to examine various aspects of mtDNA maintenance. Restriction endonuclease mapping utilizing mtDNA-specific and nuclear DNA-specific digoxigenin (DIG)-labeled probes was performed to show that the synthesized probes are indeed specific for their target sequences. The DIG-labeled probes were used to quantitate mtDNA content from different DNA isolation methods. Whole-cell DNA extraction was found to yield higher levels of mtDNA compared to a commercially available spin-column kit. Next, Southern blots were used to analyze mtDNA copy number as well as mtDNA depletion in the hepatocarcinoma-derived cell line HepaRG following exposure to the nucleoside reverse transcriptase inhibitor 2’,3’-dideoxycytidine (ddC), a known mitochondrial toxicant. In comparison to proliferative HepaRG differentiated HepaRG contained about 2-fold more mtDNA. Relative to untreated control cells, proliferating HepaRG exposed to ddC had greater than a 96% reduction in mtDNA and had decreased cellular viability. Differentiated HepaRG cell viability was not affected after 13 days of ddC treatment; however, significant mtDNA depletion was observed. We estimate that differentiated HepaRG mtDNA depletion occurs quickly at about 20 molecules per hour.
34
Lister, Adam. "The role of the Nrf2/Keap1 pathway in health and disease." Thesis, University of Liverpool, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.540019.
Повний текст джерела
35
Abdullah, Azman. "The role of Nrf2 in the regulation of liver protein expression." Thesis, University of Liverpool, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440774.
Повний текст джерела
36
Deny, Ludovic. "Nouveaux inducteurs covalents de la voie de signalisation Keap1/Nrf2/ARE." Thèse, Université de Sherbrooke, 2016. http://hdl.handle.net/11143/9858.
Повний текст джерелаАнотація:
Le stress électrophile et oxydant est un souci grandissant pour la santé avec l'évolution de nos modes de vie. L'exposition aux ultraviolets, à la pollution, aux substances carcinogènes, à la fumée de cigarette et la pratique intensive d'activités sportives sont autant de causes de stress oxydant pour l'organisme. Ces dommages sont associés à plusieurs maladies et conditions pathologiques telles que cancers, diabètes, infections pulmonaires et maladies neurodégénératives.
L'élément de réponse antioxydant (ARE) est un des composants principaux des défenses de la cellule contre ce phénomène. Ce promoteur agit sous le contrôle de Nrf2 (Nuclear factor erythroid 2-related factor 2). Une stratégie populaire pour l'activation de ce mécanisme est l'utilisation d'inducteurs covalents. Ces molécules agissent par la formation de liens covalents avec les nombreux résidus cystéine de Keap1 (Kelch-like ECH-associated protein 1), une protéine chaperonne qui contrôle l'activité de Nrf2.
Cette thèse présente la synthèse, les propriétés biologiques et l'étude des relations structure-activité d'une librairie d'électrophiles capables d'induire la transcription des gènes cibles de la voie de signalisation Keap1/Nrf2/ARE. Le premier volet fait état de la comparaison d'une variété d'électrophiles simples pour étudier les préférences de la cible. Le deuxième volet montre que la présence d'une seconde fonction capable de piéger un résidu cystéine fournit des analogues très puissants.
37
Wille, Michael [Verfasser], and Jörn [Gutachter] Wilms. "NRTA - A Live View of Astronomy / Michael Wille ; Gutachter: Jörn Wilms." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2017. http://d-nb.info/1139171518/34.
Повний текст джерела
38
Shelton, Luke. "The physiological, pharmacological and toxicological roles of Nrf2 in the kidney." Thesis, University of Liverpool, 2015. http://livrepository.liverpool.ac.uk/2014505/.
Повний текст джерелаАнотація:
Nrf2 is a transcription factor that, under conditions of chemical stress, is able to evade its cytosolic repression and translocate to the nucleus to initiate the transcription of a battery of cytoprotective genes, such as those involved in the detoxication of xenobiotics. Nrf2 has previously been shown to afford protection against chronic and acute renal injury, yet, relatively little is known about the mechanism by which Nrf2 affords this protection, and the extent of its transcriptional roles in the kidney. This thesis seeks to further our understanding of the physiological, pharmacological and toxicological roles of Nrf2 in the kidney. Using an iTRAQ-based proteomic approach to quantify protein expression levels in the kidneys of Nrf2+/+ and Nrf2-/- mice, acutely treated with vehicle or the potent Nrf2 inducer CDDO-Me (3 mg/kg), we demonstrated that 189 proteins were differentially expressed in the Nrf2-/- mouse kidney, compared to Nrf2+/+, and 42 proteins were differentially expressed in the CDDO-Me treated Nrf2+/+ mouse kidney, compared to vehicle. The key finding was that the kidneys of Nrf2-/- mice are deficient in proteins that mediate cellular redox balance, the metabolism of a range of xenobiotics, and the regulation of core metabolic processes, including energy metabolism and the synthesis and recycling of amino acids. Functional demonstration of a reduction in energy metabolism was demonstrated by assessing total NADPH and GSH, of which Nrf2-/- mouse kidneys had 35% and 30% less than their Nrf2+/+ counterparts, respectively. A single acute dose of CDDO-Me failed to augment the expression of proteins, other than Nqo1, that were shown to be regulated by Nrf2 at the basal level in the mouse kidney, however qPCR analysis of these kidneys revealed that CDDO-Me has an effect at the transcriptional level which has not fully translated within the timeframe of this study. In summary, we have provided evidence that Nrf2 regulates the expression of an array of proteins that contribute to cell defence and the maintenance of homeostasis in the kidney, supporting current interest in Nrf2 as a novel therapeutic target in a number of renal diseases. MicroRNAs are a recently discovered RNA-regulatory element that show promise in their use as biomarkers of physiological and pathological events. In order to provide insight into the microRNAs under Nrf2 control in the kidney, we performed an unbiased microRNA array analysis on kidney homogenates from Nrf2+/+ and Nrf2-/- mice, treated with vehicle or CDDO-Me, and then validated several promising microRNA candidates using targeted qPCR analysis. Of particular note are miR-466h-3p, the expression of which was significantly increased in the CDDO-Me treated Nrf2+/+ mouse kidney and decreased in the Nrf2-/- mouse kidney, compared to their respective controls, and miR-28c and 144, which were both significantly decreased in the CDDO-Me treated Nrf2+/+ mouse kidney, and increased in the Nrf2-/- mouse kidney. This novel analysis represents the first step in characterising the renal Nrf2 microRNA-ome, which could reveal novel mechanisms of Nrf2 function and markers of its activity that could translate to the clinic. Recent interest in the use of CDDO-Me as a therapeutic intervention for late-stage chronic kidney disease has culminated in a phase III clinical trial (BEACON), which was subsequently terminated due to unforeseen adverse cardiac events, of which the cause has yet to be identified. In order to determine whether the drive to produce more potent Nrf2 inducers has inadvertently led to the generation of inherently more toxic compounds, the relationship between potency towards Nrf2 and toxicity was evaluated for CDDO-Me and related triterpenoids, and other classes of Nrf2 inducer. Using a rat H4IIE-ARE8L luciferase reporter cell line to determine in vitro therapeutic indices, it was discovered that within the compounds tested an increase in potency toward Nrf2 of four magnitudes results was associated with an increase in toxicity of only two magnitudes, resulting in a relative increase in in vitro safety. This data indicates that it is possible to generate potent Nrf2-inducers that are not inherently toxic, and suggests that therapeutic targeting of Nrf2 continues to hold promise as a novel treatment for a range of diseases. In summary, by using a proteomic approach we have identified an array of renal Nrf2-regulated proteins that contribute to various cytoprotective and metabolic processes in the kidney, supporting current interest in the therapeutic targeting of Nrf2 as treatment for renal disease. Additionally, the microRNAs under Nrf2 regulation in the kidney have also been identified, and represent the first step in fully characterising the Nrf2 microRNA-ome. Finally, it was shown that the drive to produce more potent Nrf2 inducers has not led to the generation of inherently more toxic compounds; indeed an increase in potency is associated with a relative increase in in vitro safety, suggesting that the targeting of Nrf2 is still a promising therapeutic route. Overall, the work presented in this thesis has furthered our understanding of the physiological, pharmacological and toxicological roles of Nrf2 in the kidney.
39
Olayanju, Adedamola Oladeji. "The pharmacological manipulation of the Nrf2 pathway and its therapeutic significance." Thesis, University of Liverpool, 2014. http://livrepository.liverpool.ac.uk/2035060/.
Повний текст джерелаАнотація:
Nrf2 (Nuclear factor erythroid 2-related factor 2), a redox-sensitive transcription factor, plays a critical role in the regulation of cellular defence and contributes to a number of cellular processes. Nrf2 is regulated through an interplay of complex transcriptional and post-translational mechanisms that modulates its activity during cellular perturbations or other biological processes thereby ensuring cellular homeostasis is maintained through the orchestration of adaptive responses. However, there is mounting evidence that constitutive upregulation of the Nrf2 pathway drives the enhanced proliferation and chemoresistance of various cancers. Therefore, an ability to modulate the activity of the Nrf2 pathway holds promise as a therapeutic strategy in certain disease settings. The work presented in this thesis showed that CDDO-Me provoked the induction of the Nrf2 pathway in C57BL6J WT and Nrf2 KO mice and CD1 WT mice. Analysis of CDDO-Me induced gene expression changes in both WT and Nrf2 KO mice showed a significant increase in the relative mRNA levels of ARE-dependent genes in the livers of CDDO-Me treated WT animals. Notably, CDDO-Me also provoked the accumulation of Nrf2 and NQO1 in human PBMCs and PHHs demonstrating its translational relevance. The mechanism of action of CDDO-Me as an inducer of Nrf2 is poorly understood. It was shown here that CDDO-Me post-transcriptionally evoked concentration and time-dependent, accumulation of Nrf2 protein in Hepa1c1c7 cells. Furthermore, CDDO-Me was shown to stabilize Nrf2 protein independently of the modulation of protein kinases and other signalling pathways that are purported to regulate Nrf2 activity. The work here also provides in vitro insights into the molecular mechanism of Nrf2 inhibition by the quassinoid brusatol. Brusatol post-transcriptionally evoked concentration- and time-dependent, yet transient, depletion of basal and inducible protein levels of Nrf2 in Hepa-1c1c7 cells. Furthermore, the ability of brusatol to inhibit Nrf2 was not affected by siRNA depletion of Keap1. In keeping with the latter observation, brusatol induced the depletion of Nrf2 independently of the proteasome and autophagic degradation machineries. Thus, these findings indicate that brusatol exploits a previously unknown mechanism of Nrf2 degradation. By examining the molecular mechanisms underlying the activation of Nrf2 by CDDO-Me and its inhibition by brusatol, this work reveals novel aspects of regulation within this important cellular pathway, and informs the design of new pharmacological inducers and inhibitors, which hold promise as therapeutic agents in a number of diseases.
40
Marhenke, Silke [Verfasser]. "Die Rolle von Nrf2 und p21 in der Hepatokarzinogenese / Silke Marhenke." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover, 2010. http://d-nb.info/1008524727/34.
Повний текст джерела
41
Wille, Michael Verfasser], and Jörn [Gutachter] [Wilms. "NRTA - A Live View of Astronomy / Michael Wille ; Gutachter: Jörn Wilms." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2017. http://d-nb.info/1139171518/34.
Повний текст джерела
42
Serezino, Luís Henrique Damasceno. "Caracterização fisiológica e transcricional dos processos de aquisição e remobilização de nitrato em cana-de-açúcar (Saccharum spp.)." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/64/64133/tde-02022016-141558/.
Повний текст джерелаАнотація:
A expansão da área de cultivo da cana-de-açúcar (Saccharum spp.) para solos marginais e a necessidade de manutenção da alta produtividade tem levado a maior aplicação de fertilizantes nitrogenados na cultura. Esta prática, porém, incorre em altos custos financeiros e ambientais. Comparado a outras culturas, cana-de-açúcar possui baixa resposta a aplicação de fertilizantes nitrogenados, mas as causas desta baixa eficiência no uso de N (NUE) permanecem desconhecidas. Na tentativa de compreender os mecanismos envolvidos no NUE em cana-de-açúcar, este trabalho realizou a caracterização fisiológica dos processos de absorção de nitrato e remobilização de N por estudos de cinética de absorção e experimentos de translocação de 15N. Além disso, analisou-se o perfil de expressão de genes codificadores de transportadores de nitrato (NRTs - NITRATE TRANSPORTERS). Plantas da cultivar \'SP80-3280\' foram expostas à condições distintas de suplemento de N para investigar a regulação do processo de aquisição. Além de comprovar a menor eficiência da cana-de-açúcar na aquisição de nitrato quando comparada com amônio, foi demonstrada a presença de sistema de transporte de alta afinidade (HATS, High Affinity Transport System) para ambas as fontes de N presentes em raízes, induzido sob baixas concentrações externas de N e/ou sob baixo status de N na planta. Observou-se que amônio regula negativamente a absorção de nitrato, modulando a expressão dos genes envolvidos neste processo. Em plantas sob condições de deficiência de N (-N) foi verificada a regulação tardia do HATS responsável pela aquisição de nitrato. A ausência de correlação entre o influxo de 15N e acúmulo de transcritos de transportadores de nitrato sugere a existência de uma regulação pós-transcricional dos transportadores do HATS em raízes submetidas a provisão de nitrato. Para caracterizar o processo de remobilização, plantas foram submetidas a condições contrastantes de disponibilidade de N na tentativa de identificar o mecanismo pelo qual nitrato pode ser regulado durante este processo. Apesar da reduzida eficiência na aquisição e estoque de nitrato, cana-de-açúcar possui a capacidade de utilizar nitrato como fonte de N, e em condições suficientes de suplemento de N, nitrato e amônio são utilizados como fonte de N. Sob restrição de N, porém, nitrato apresenta maior fluxo em raízes e colmos, enquanto que amônio ainda permanece como fonte de N em folhas jovens devido a alteração no carregamento de nitrato no xilema. Todavia, o suplemento de nitrato a ser reduzido e assimilado em folhas parece ter origem no colmo. Portanto, a modulação da expressão dos transportadores NRT assegura a alocação de nitrato em cana-de-açúcar quando N é limitante em solosThe expansion of sugarcane (Saccharum spp.) cultivated area to marginal lands and the need to maintain high yield have led to increasing application of nitrogen fertilizers. However, this practice represents high economic and environmental costs. Compared to other crops, sugarcane displays a low response to N fertilization, but the causation of the low nitrogen use efficiency (NUE) remains unknown. To understand the mechanism involved in NUE, this study was carried out to conduct the physiological characterization of nitrate uptake and N remobilization in sugarcane by uptake kinetic analysis and translocation experiments using 15N. Further, the expression profile of genes encoding nitrate transporters (NRTs - NITRATE TRANSPORTERS) involved in both processes was determined. Plantlets of cultivar \'SP80-3280\' were exposed to various N supplement conditions to investigate the regulation of the uptake process. The lower efficiency in nitrate acquisition compared to ammonium was corroborated and extended for low N conditions. The occurrence in sugarcane roots of high affinity uptake systems (HATS, High Affinity Transport System) for both N sources,, induced at low external concentrations of N and/or low N status in the plant was confirmed. Ammonium negatively regulates nitrate uptake by modulating the expression of genes involved in this process. Plants under N deficiency (-N) exhibited a late regulation of HATS responsible for nitrate uptake. The lack of correlation between 15N influx and transcript accumulation of nitrate transporter genes suggests the existence of a post-transcriptional regulation of HATS in roots subjected to nitrate resupply. To characterize the remobilization process, plants were submitted to contrasting conditions of N availability to identify the mechanisms by which nitrate may be affected during this process. Despite the low efficiency of nitrate uptake and storage, sugarcane demonstrates the ability to use nitrate as N source. In N sufficient conditions (+N), ammonium and nitrate are used as N source. Under restriction of N, however, nitrate has increased flow in roots and stems, while ammonium remains as N source to young leaves by change in nitrate loading into the xylem. However, the source of the nitrate to be reduced and assimilated in leaves appears to be originated from the culm. Therefore, modulation of NRT transporters expression ensures nitrate allocation in sugarcane when N is limited in soils
43
Silva, Camila de Souza. "Equil?brio l?quido-vapor do sistema tern?rio etanol + ?gua + 1-etil-3-metil imidaz?lio cloreto: experimental e modelagem termodin?mica." Universidade Federal Rural do Rio de Janeiro, 2016. https://tede.ufrrj.br/jspui/handle/jspui/1784.
Повний текст джерелаАнотація:
Submitted by Celso Magalhaes (celsomagalhaes@ufrrj.br) on 2017-06-14T14:33:49Z
No. of bitstreams: 1
2016 - Camila de Souza Silva.pdf: 1802766 bytes, checksum: 154ae702e6dbdd0afdc13fb202a08682 (MD5)Made available in DSpace on 2017-06-14T14:33:49Z (GMT). No. of bitstreams: 1 2016 - Camila de Souza Silva.pdf: 1802766 bytes, checksum: 154ae702e6dbdd0afdc13fb202a08682 (MD5) Previous issue date: 2016-08-02
Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES
Equilibrium data at low and high pressures are important to correct establish conditions of temperature and pressure for separation processes, and to supply the capacity of the solvent, the compositions of the phases and the selectivity of the solvent. The separation of ethanol-water system is of great importance for the industry due to numerous applications of anhydrous ethanol. In all of these applications, ethanol must be free of water and it is necessary to add a third component in the distillation to break the azeotrope. It can be add different solvents, as benzene, hexane, ethyleneglycol, salts, and, in the last years, many studies have been done with ionic liquids. So, the purpose of this work is to use an ionic liquid (1-ethyl-3-methylimidazolium chloride) as the third component, looking for the ethanol dehydration. Because of that, it was done a study to evaluate the effect of this ionic liquid in the liquid-vapor equilibrium behavior between water and ethanol. Experimental data were measured, in triplicate, under normal pressure, in an Othmer-type ebulliometer (300 mL of volume), with two condensers, and made of borosilicate glass. The sample analysis was done in a digital densimeter. The ionic liquid used was recovered from one solution to another, just by adding the required amount to complete each mass fraction. Experimental data was measured with ethanol-water solutions varying the molar concentrations from 0.2 to 0.99, and ionic liquid weight fraction masses from 5 to 60%, to evaluate the behavior of the equilibrium data of the ethanol+water+[emim][Cl] system. The experiments showed that [emim][Cl] with a minimum mass fraction of 20% is a promising solvent because it could ?break? the azeotrope between water and ethanol, and higher mass fraction of ionic liquid were better to enrich the vapor phase in ethanol. NRTL model was used to correlate experimental vapor-liquid equilibrium of the ternary system, estimating the binary parameters, applying the bubble point methodology. The deviations of temperature and vapor phase composition were 0.147 ?C and 0.049, respectively. The relative volatility was greater than 1 for the mass fractions from 20%. The activity coefficients decrease with the increase in the molar concentration of ethanol. Values of the excess Gibbs free energy show a positive deviation for all mass fractions worked, and the experimental data were consistent thermodynamically
Os dados de equil?brio a press?es baixas e elevadas s?o importantes para estabelecer as condi??es corretas de press?o e temperatura para os processos de separa??o e para fornecer a capacidade do solvente, as composi??es das fases e a seletividade do solvente. A separa??o do sistema etanol-?gua ? de grande import?ncia para a ind?stria devido a numerosas aplica??es do etanol anidro. Em todas essas aplica??es, o etanol deve ser livre de ?gua e, para isso, ? necess?rio adicionar um terceiro componente na destila??o para quebrar o aze?tropo. Podem ser adicionados diferentes solventes como o benzeno, hexano, etilenoglicol, sais e, nos ?ltimos anos, tem-se visto muitos estudos com l?quidos i?nicos. Com isso, o objetivo deste trabalho ? a utiliza??o de um l?quido i?nico (1-etil-3-metil imidaz?lio cloreto) como terceiro componente, visando a desidrata??o do etanol, al?m da avalia??o do efeito deste l?quido i?nico no comportamento do equil?brio l?quido-vapor entre a ?gua e o etanol. Os dados experimentais foram medidos, em triplicata, sob press?o normal, em um ebuli?metro tipo Othmer (300 mL de volume), com dois condensadores, feitos de vidro de borosilicato. As determina??es das amostras foram feitas em um dens?metro digital. Os dados foram medidos com solu??es de etanol-?gua em diferentes concentra??es molares (0,2 a 0,95), variando a fra??o m?ssica de l?quido i?nico de 0,05 a 0,60, para avaliar o comportamento dos dados de equil?brio do sistema etanol-?gua-[emim][Cl].Os resultados mostraram que o [emim][Cl] ? um solvente promissor, pois "quebra" o aze?tropo entre a ?gua e etanol a partir de 20% de l?quido i?nico, e a concentra??o de etanol na fase vapor foi maior com o aumento da fra??o m?ssica de LI.O modelo NRTL foi utilizado para correlacionar os dados experimentais de equil?brio, estimando-se os par?metros bin?rios, aplicando-se a metodologia do ponto de bolha. Os desvios em rela??o ? temperatura e a composi??o molar da fase vapor foram 0,147 ?C e 0,049, respectivamente. O l?quido i?nico, recuperado de uma solu??o para outra, passou por uma an?lise de RMN para avaliar se n?o houve altera??o na sua estrutura e, constatou-se que, ap?s ser recuperado, e novamente reutilizado, o solvente n?o perdeu as caracter?sticas originais. As volatilidades relativas foram superiores a 1 para as fra??es m?ssicas a partir de 20%, confirmando a quebra do aze?tropo. A energia livre de Gibbs em excesso apresentou valores que mostram um desvio positivo para todas as fra??es m?ssicas trabalhadas e os dados experimentais foram consistentes termodinamicamente
44
Petriello, Michael C. "ROLE OF CAVEOLIN-1 AND NRF2 IN NUTRITIONAL MODULATION OF PCB TOXICITY." UKnowledge, 2015. http://uknowledge.uky.edu/toxicology_etds/11.
Повний текст джерелаАнотація:
Cardiovascular disease is the leading cause of mortality in Western societies and is linked to multiple modifiable risk factors including lifestyle choices. Emerging evidence implicates exposure to persistent environmental pollutants, such as polychlorinated biphenyls (PCBs), as a risk factor for the development or progression of cardiovascular disease. To reduce disease risks, it is critical to identify sensible means of biomedically reducing the toxicity of persistent organic pollutants and related environmental stressors.
First, we tested a hypothesis that endothelial cell inflammation and subsequent cardiovascular toxicity initiated by coplanar PCBs is modulated by the crosstalk between caveolae and Nuclear factor (erythroid-derived 2)-like 2(Nrf2) related proteins. Caveolae are lipid-enriched organelles found abundantly in endothelial cells and are important mediators of endocytosis and signal transduction. Caveolin-1 (Cav-1), the major structural protein of caveolae, is known to bind and concentrate multiple proteins related to cardiovascular disease and PCB toxicity. Downregulation of Cav-1 protects against PCB-induced vascular toxicity, but possible mechanisms of this defense remain elusive. Studies using endothelial cells isolated from mice deficient in Cav-1 as well as in vitro silencing assays demonstrated that loss of Cav-1 increases available antioxidant enzymes by upregulating the antioxidant master controller Nrf2.
Nutritional interventions focused on diets high in bioactive food components, such as polyphenols or certain fatty acids, may prove to be effective at decreasing environmental pollutant induced diseases. To test the hypothesis that dietary intervention can sensitize Nrf2 and/or caveolae signaling pathways, leading to a more effective anti-inflammatory defense against PCB insults, mice were fed a green tea polyphenol enriched diet and challenged with coplanar PCB 126. Mice fed an enriched diet and exposed to PCBs exhibited lower levels of oxidative stress and higher levels of multiple Nrf2 target antioxidant enzymes. Also, in separate in vitro studies, pretreatment of endothelial cells with the endogenously formed nutrient metabolite, nitro-linoleic acid, altered caveolae and Nrf2 related proteins, resulting in a modified response to PCB exposure. Together, these data support the paradigm that nutritional modulation may be a sensible means of reducing disease risks associated with exposure to environmental pollutants.
45
Schaap, M. C. A. "The biological evaluation of inhibitors of the Keap1-Nrf2 protein-protein interaction." Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1473105/.
Повний текст джерелаАнотація:
The Keap1-Nrf2 pathway has been identified as a key regulator of the cytoprotective response of cells when exposed to oxidative stress. The induction of detoxification gene products by increasing the activity of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) can be used as a chemopreventive approach to cancer treatment. Natural and synthetic agents can disrupt the interaction between the substrate adaptor protein Kelch-like ECH-associated protein 1 (Keap1) and Nrf2, which allows nuclear Nrf2 translocation and accumulation. The aim of this project was to characterize the behaviour of direct and indirect Nrf2 inducer molecules by applying several biological methods that were specifically optimised or developed for the Keap1-Nrf2 pathway. Potential inhibitors of the Keap1-Nrf2 complex were screened using a cellular NQO1 induction assay and an in vitro fluorescence polarisation (FP) assay for direct inhibitors. A novel in vitro Förster resonance energy transfer (FRET) assay was developed as an additional screening tool to identify Keap1 binding partners. Further biological evaluation was conducted with the most promising molecules using western blotting analysis and a new intracellular Nrf2 staining method for flow cytometry. The natural product and indirect Nrf2 inducer sulforaphane was used as a reference compound (NQO1 CD = 0.4 μM). From a library of Michael acceptor-containing cyclohexadienone analogues, a 3-chlorophenyl compound (6.49) was identified as a potent inducer (NQO1 CD = 1 μM). Stearoyl-capped Nrf2-derived peptides were potent inhibitors of the direct Keap1-Nrf2 protein-protein interaction and showed promising cell penetrating properties. Direct inhibitor small molecules included two bissulphonamide derivatives (7A4, NQO1 CD = 8 μM and 7B1, NQO1 CD = 4 μM) and a 1,2,3-triazole derivative (7C55, NQO1 CD = 0.6 μM) with FP IC50 values in the nano- to micromolar range. The selectivity of the compounds was assessed by revealing potential aryl hydrocarbon receptor (AhR) transcription factor cross-talk.
46
Rosen, Christian [Verfasser]. "Die Rolle des Transkriptionsfaktors Nrf2 bei der Myelinphagozytose und Remyelinisierung / Christian Rosen." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2013. http://d-nb.info/1047325632/34.
Повний текст джерела
47
Stolt, Claudia [Verfasser]. "Funktion von Nrf2 und Glutathion bei Infektionen mit Burkholderia pseudomallei / Claudia Stolt." Greifswald : Universitätsbibliothek Greifswald, 2016. http://d-nb.info/1085140997/34.
Повний текст джерела
48
Dayalan, Naidu Sharadha. "Regulation of transcription factors NRF2 and HSF1 in mediating cellular stress responses." Thesis, University of Dundee, 2016. https://discovery.dundee.ac.uk/en/studentTheses/5f608a60-884c-47cd-87e6-b70016e788bb.
Повний текст джерелаАнотація:
The KEAP1/NRF2/ARE pathway is at the forefront of cellular defense. Induction of this pathway is protective against various conditions of stress such as oxidative stress and exposure to electrophiles. Conversely, failure to upregulate the pathway leads to increased disease susceptibility and accelerated pathogenesis. Under basal conditions, transcription factor nuclear factor erythroid 2 p45-related factor 2 (NRF2) is targeted for ubiquitination and proteasomal degradation by a repressor protein Kelch-like (ECH)-associated protein (KEAP1), a substrate adaptor for Cullin 3-based E3 ubiquitin ligase. Inducers of the pathway chemically modify specific cysteines within KEAP1, leading to loss of repressor function, NRF2 accumulation and enhanced transcription of genes encoding a large network of cytoprotective proteins. The cyanoenones are the most potent NRF2 activators known. Cyanoenones bind to KEAP1 covalently and reversibly, and are suitable for chronic in vivo administration. However, the cysteine sensor for these compounds is unknown. Among the cysteine sensors of KEAP1, C151 in the BTB domain and C273 and C288 in the intervening region, are best characterized. In this study using KEAP1-knockout mouse embryonic fibroblasts (MEFs) rescued with wild-type (WT) KEAP1 or cysteine mutants, we tested a series of cyanoenones for their ability to modify specific cysteine sensors in KEAP1. We discovered that remarkably, all compounds of this class specifically target C151 regardless of their molecular shape or size. In addition, primary peritoneal macrophages (PMφ) derived from KEAP1C151S/C151S knock-in mice generated using the CRISPR/Cas9 technology, had higher LPS-induced inflammatory responses than cells from WT animals. Furthermore, at nanomolar concentrations, the tricyclic cyanoenone TBE-31 strongly suppresses LPS-induced inflammatory responses in primary PMφ cells, suggesting the potential for therapeutic use in inflammatory diseases. Another cytoprotective response is the heat shock response (HSR) which is activated when cells are exposed to stressors such as elevated temperatures, heavy metals and cytotoxic compounds. The HSR, mainly mediated by Heat Shock Factor 1 (HSF1), protects the integrity of the cellular proteome through the upregulation of a battery of genes involved in ameliorating proteotoxicity. Several small molecule activators of the KEAP1/NRF2/ARE pathway have been shown to activate HSR through the activation of HSF1. Work in this thesis focused on one such dual activator, the dietary agent phenethyl isothiocyanate (PEITC). We found that PEITC reacts with KEAP1 C151 to stabilize NRF2, and that it is able to activate the HSR by activating HSF1 through the inhibition of heat shock protein 90, the main negative regulator of HSF1. We further showed that PEITC activates p38 mitogen-activated protein kinases (MAPKs). In vitro, all members of the p38 MAPK family rapidly and stoichiometrically catalyze the phosphorylation of HSF1 on S326, a hallmark of HSF1 activation. The use of stable knockdown cell lines and inhibitors indicated that among the p38 MAPK, p38γ is the principal isoform responsible for the phosphorylation of HSF1 at S326 in cells. A protease-mass spectrometry approach confirmed S326 phosphorylation, and unexpectedly, revealed that p38 MAPKs also catalyze the phosphorylation of HSF1 at S303/307, previously known repressive post-translational modifications. Thus, we identified p38 MAPKs as highly efficient catalysts for the phosphorylation of HSF1. Furthermore, our findings suggest that the magnitude and persistence of activation of p38 MAPKs are important determinants of the extent and duration of the HSR. In order to investigate the physiological significance of HSF1 phosphorylation at S326, we used immunofluorescence and western blotting techniques. We found that mitotic cells have high levels of HSF1 pS326 compared to interphase cells. Interestingly, our studies revealed that phosphorylated HSF1 at S326 is concentrated at the midbody of telophase cells, suggesting a potential role for HSF1 during the late-stage of cell division. Further studies are needed to define the role(s) of the HSF1 pS326 during the cell cycle.
49
Taylor, Marlon D., and Marlon D. Taylor. "Sulforaphane Potentiates Non-Melanoma Skin Cancer in UVB-Treated Nrf2 Knockout Mice." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/622859.
Повний текст джерелаАнотація:
Sulforaphane is a natural product found in cruciferous vegetables which is known to have many chemopreventive properties including the induction of apoptosis and the inhibition of inflammation, cellular proliferation, and reactive oxygen species (ROS) formation. The reduction of ROS activity by sulforaphane is likely linked to the activation of NF-E2 related factor-2 (Nrf2), a transcription factor involved in cytoprotection against ROS and electrophilic stress. The skin is particularly vulnerable to oxidative stress caused by ultraviolet (UV) light, which is an established complete carcinogen. Sulforaphane has been shown to reduce both chemical and UVB-induced skin carcinogenesis in mouse models. Suppression of DMBA/TPA-induced skin tumorigenesis by sulforaphane has been shown to be dependent upon Nrf2 activity. Additional studies have shown that genetic activation of Nrf2 can protect keratinocytes against UVB-induced ROS. Nrf2 has also been implicated in regulating inflammatory responses after UVB exposure in the skin. However, the role of Nrf2 in the antitumorigenic activity of sulforaphane in the context of UVB-induced skin tumors is not well understood. We therefore performed murine experiments in order to clarify whether sulforaphane requires Nrf2 in order to block UVB-induced non-melanoma skin cancer. Consistent with the literature, we observed that wildtype (WT) mice topically treated with sulforaphane were less susceptible to UVB-induced tumor incidence and tumor burden compared to the vehicle control WT group. However, Nrf2 KO mice treated with sulforaphane presented with significantly greater UVB-induced tumor incidence and burden compared to the WT sulforaphane group, suggesting that sulforaphane may potentiate tumorigenesis in the context of UVB exposure if Nrf2 is absent. We therefore performed acute in vivo and in vitro experiments using topical sulforaphane (as per the tumor experiment) to investigate why Nrf2 KO mice developed more tumors than WT mice during UVB and sulforaphane treatment. Topical treatment of SKH-1 mice with sulforaphane did result in slight reduction of UV-induced epidermal hyperplasia in wildtype mice which was not present in Nrf2 KO mice (trends were not significant). Surprisingly, while wildtype mice developed significantly more epidermal inflammation in our acute treatment model than did the Nrf2 KO strain (as measured by skin fold thickness), inflammation was not significantly influenced by topical sulforaphane treatment in either strain of mice. However, cell culture studies using primary mouse keratinocytes indicate that sulforaphane’s ability to block UVB-induced ROS is lost in Nrf2 KO cells. Taken together, our ROS data may strengthen the hypothesis that sulforaphane increases the oxidative stress of cells during UVB treatment in the absence of Nrf2.
50
Bryan, Holly. "Molecular investigation of Keap1-dependent regulation of the Nrf2 cell defence pathway." Thesis, University of Liverpool, 2014. http://livrepository.liverpool.ac.uk/2005540/.
Повний текст джерелаАнотація:
Mammalian cells have evolved highly regulated defence pathways, which are activated in response to stress. The transcription factor Nrf2 is activated in response to chemical and oxidative stress and induces the expression of antioxidants and detoxification enzymes. Nrf2 activity is regulated by its cysteine-rich repressor protein Keap1, which facilitates Nrf2 degradation. In the presence of electrophilic compounds and/or oxidative stress, Keap1-mediated repression of Nrf2 is hindered, allowing the nuclear localisation of Nrf2 and the up-regulation of cell defence gene expression. The dysregulation of the Nrf2 pathway has been associated with many disease pathologies, and is a promising therapeutic target. Furthering our understanding of the chemico-biological triggers for Nrf2 activation may inform the design of novel Nrf2-inducers with increased efficacy and reduced toxicity. The modification of one or more cysteine residues in Keap1 by electrophiles is believed to be central to Nrf2 activation. Therefore, the aims of the studies in this thesis were to investigate the chemical modification of Keap1 cysteine residues by Nrf2-inducers and identify novel Keap1 binding proteins, which may play a role in the regulation of Nrf2 activity. Previous work carried out in this lab identified cysteine residues in Keap1 that are covalently modified by a panel of Nrf2-inducing compounds in recombinant Keap1 protein and in cells. Additionally, Nrf2 can be induced by glutathione (GSH) depletion in the absence of Keap1 adduct formation. We hypothesised that GSH depletion permits reactive oxygen species (ROS) to accumulate and oxidise Keap1 cysteine residues, thereby inducing Nrf2. To address this, we treated Keap1-V5 expressing HEK293T cells with Nrf2-inducing compounds. We used liquid chromatography tandem mass spectrometry (LC-MS/MS) to investigate the ability of these compounds to form adducts with Keap1 cysteine residues, or induce reversible/irreversible redox modifications of these residues. We show that compounds which form covalent adducts with Keap1 and deplete GSH (i.e. 2,4-dinitrochlorobenzene) or do not deplete GSH (i.e. dexamethasone 2,1-mesylate) induce modifications of Keap1 that could be representative of oxidation. However compounds which do not form covalent adducts with Keap1 but cause oxidative stress (i.e. hydrogen peroxide), or GSH depletion (i.e. L-buthionine-sulfoximine), do not appear to cause oxidative-like modification of Keap1 cysteines. We therefore show that some Nrf2 inducers promote the formation of reversible and/or irreversible redox modifications of Keap1 which could be due to thiol oxidation, although this is not dependent on GSH depletion. To further explore the modification of Keap1 cysteine residues by Nrf2 inducers, we investigated the ability of triterpenoids (TPs) to modify Keap1. TPs, in particular methyl 2-cyano-3,12-dioxooleana-1,9(11)dien-28-oate (CDDO-Me), are potent inducers of Nrf2 and are potential therapeutic agents. However, the mechanism of Nrf2 activation by TPs has not been fully elucidated using LC-MS/MS. We identify key cysteine residues in Keap1 which are adducted by a chemically-tuned TP (CDDO-Epoxide) in recombinant Keap1 and in cells expressing Keap1-V5. Additionally, we use an in silico modelling approach to visualise the binding orientations of CDDO-Epoxide with key Keap1 cysteine residues. Correlating the potency of a panel of TPs towards the Nrf2 pathway with their in silico propensity to bind covalently to the identified residues showed no relationship. However, we show significant positive correlation between the potency of these TPs towards Nrf2 and their in silico propensity to bind non-covalently in two cysteine-containing pockets (Cys-273, -288) in Keap1. These data reveal the specific sites of interactions between potent TP Nrf2 inducers and Keap1, and highlight the non-covalent binding of Keap1 by electrophiles as a potential mechanism of Nrf2 activation. The function of Keap1 is regulated by interactions with binding partners, such as sequestosome1 (p62) which targets it for autophagic degradation, or PGAM5 which localises Keap1 to the mitochondria. We previously used an LC-MS/MS approach to identify p62 as a novel Keap1-binding partner in cells. Therefore, we reasoned that using the same experimental approach with a more sensitive MS system, we could identify additional Keap1-binding proteins. Specifically, we identified a large number of proteins that co-purified with Keap1-V5 from HEK293T cell lysates, of which 55 were found to contain a known Keap1 binding motif, such as the one found in Nrf2, p62 and PGAM5. Network analysis highlighted the potential link between Keap1/Nrf2 and the p53 cell survival pathway. We validated the LC-MS/MS data using a yeast 2-hybrid screen, which reveals HBS1L, RIC8A and PSMD3 as novel Keap1 binding partners, although the functional relevance of the interaction of these proteins with Keap1 requires further investigation. In summary, the data presented in this thesis demonstrates that whilst the covalent modification of Keap1 cysteines is an important aspect of Nrf2 induction, the oxidation of Keap1 thiols may be an alternative mechanism. We identify key cysteine residues in Keap1 covalently modified by a potent TP Nrf2 inducer in recombinant protein and cells, but show that non-covalent modification of Keap1 may be involved in the process of Nrf2 activation by this class of compound. It will be important in future studies to determine how the modification of Keap1 cysteine residues is translated to the activation of Nrf2. Additionally, we identify putative novel Keap1 binding partners which may serve to regulate the activity of the Nrf2 pathway. Overall, these findings expand our understanding of the chemical and molecular interactions that govern the activity of Nrf2, and will therefore contribute to the ongoing efforts to target this pathway as a novel therapeutic strategy in numerous diseases.