Tesi sul tema "Septimus"
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Dickerhof-Borello, Elisabeth. "Ein liber septimus für das Corpus iuris canonici : der Versuch einer nachtridentinischen Kompilation /". Köln : Böhlau, 2002. http://catalogue.bnf.fr/ark:/12148/cb400510838.
Testo completoHaynes, I. P. "The Romanization of the alae and cohortes of the Roman imperial army from Augustus to Septimus Severus". Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358502.
Testo completoHjersing, Charlotte. "Representations of Clarissa and Septimus in Virginia Woolf’s Mrs Dalloway : A deconstructive approach combined with aspects of feminist and psychoanalytical criticism". Thesis, Högskolan Dalarna, Engelska, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:du-4172.
Testo completoBen, Aros Mohamed. "Les développements architecturaux à Leptis Magna pendant l'époque sévérienne (193 – 235)". Thesis, Paris 4, 2013. http://www.theses.fr/2013PA040008.
Testo completoLeptis Magna has played a vital role in the history of North Africa.This role is based on the economic data of the city and the good management of its elites who are opened the policy of Romanization by adopting the Roman customs and patterns of Roman architecture. Among elites, most famous are those of the family Septimii which allowed his child, Septimius Severus, came to the throne in 193 AD. Under the reign of this emperor, Leptis Magna reached its peak of prosperity and became the Rome of Africa by setting up a massive constructions program: “The Severan Buildings” are the subject of this study. The choice of this subject is essentially justified by the importance of planning lepcitain characteristics at the Severan period, which generated abundant work in multiple languages. Now an assessment is necessary to highlight the importance and originality of this Severan phase: both for the city itself as well as for imperial ideology, which is conveyed brilliantly. We will try here to know why Septimius Severus gave his full attention to build these magnificent buildings in a short period. Perhaps because it was his hometown? Or was the town an advantageous asset for Rome? The beauty of these great monuments dating from the Roman era requires a historical and scientific research in the urban fabric: To know their operation and their role in Roman society; to study their aesthetic components and to find the common points between them, also to measure the amplitude of the artistic production and its relationships with the political and economic development of the city
Boubakar, Leila. "Rôle des Septines dans la transmission de traits morphologiques au cours de la neurogenèse des ganglions des racines dorsales". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1139.
Testo completoNeurite formation is a crucial step of neuronal differentiation. However, the mechanisms that determine how and at which position neurites emerge in the soma are still poorly understood. We postulated that a molecular polarity could prefigure the morphological differentiation, with some molecules that could accumulate at the future site of axon initiation. Interestingly, such molecular polarity has been evidenced in the contest of yeast budding, with bud forming at specific position relatively to the previous bud site. Genome-wide screen identified hundreds of proteins that control bud site location. Among the vertebrate molecules homologous to those involved in budding site selection, we selected the Septins as promising candidates. These GTP-ases form filaments that act as diffusion barriers and molecular scaffolds. We investigated the contribution of Septins to axon initiation using the chick dorsal root ganglion (DRG) neurons as a model. Monitoring of cell morphology in nascent ganglia indicates that DRG neurons form a single axon at the ventral pole and a second one at the dorsal pole and that these axons seem to emerge directly after their last division. This suggests that two initiation sites are selected at opposite pole of the soma.We found that Septins homologous with those controlling budding are expressed in the early DRG developmental stages. My analyses by time-lapse video-microscopy showed that Septin7 accumulate at the site of axon emergence, just before or during its formation.We observed that a pharmacological inhibitor and a dominant-negative construct block axon formation both in vitro and in vivo respectively. Furthermore, blocking Septin function leads to the appearance of uncommon round or sea urchin-like neurons. Thus, Septins appear to regulate early step of morphological differentiation of DRG neurons, possibly by controlling axon initiation site selection
Sales, Elisa Morandé. "Estudos estruturais do processo de agregação entre proteínas amilóides em solução". Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-06082012-170235/.
Testo completoSeptins are proteins from the GTP-binding family and participate in cell division cycle performing functions such as secretion and cytoskeletal division. They can also be found in neurodegenerative conditions as Alzheimer\'s and Parkinson\'s diseases and some kinds of cancer as leukemia, lymphoma and solid tumors. In this work, we investigated the influence of temperature and concentration on the septin 2 GTPase domain (SEPT2G) aggregation using dynamic light scattering (DLS) and small angle x-ray scattering (SAXS). DLS results revealed the protein aggregation kinetic is around seconds for temperatures above 25ºC. SAXS data of the protein at 0.5 mg/mL showed that SEPT2G is a dimer in aqueous solution at 4_C and this condition is kept stable for approximately one hour of experimental observation. At 15ºC, SAXS results revealed the coexistence of three populations in solution composed by 88% of dimers, 10% of cylinder-like smaller aggregates (protofibrils) and 2% of aggregates bigger than the technique detection. After 30 minutes there is a preferential rearrangement of dimers into very large aggregates which contribution on the scattering curve becomes 8%. At 25ºC, the dimers percentage decreases to 70% with a contribution of circa 30% of bigger aggregates, even at the beginning of data acquisition. At temperatures of 37ºC and 45ºC, dimers and very large aggregates coexist in solution since the beginning of data acquisition, which equilibrium quickly shifts in such a way that after 20 minutes of observation the solution is mostly composed by very large aggregates, indented as amyloid structures by the thioflavine fluorescence technique, which intercalates in the cross- structures. At 1 mg/mL and 4ºC, the protein was stable over 1 hour of observation where an equilibrium of dimers (93%) and elongated structures (composed by approximately 80 monomers) in solution takes place. Increasing the temperature to 15ºC, most of the protein remains dimeric. On the other hand, at 25ºC the very large aggregates contribution is around 30% coexisting with dimers and oligomers. At 37ºC and 45ºC there is the formation of large aggregates, similar to what was observed at 0.5 mg/mL. In conclusion, our SAXS results indicated that the aggregation process of SEPT2G in solution may follow different pathways depending on concentration and temperature.
Martins, Carla Silva. "Análise das interfaces de interação septina-septina". Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-14092017-144809/.
Testo completoSeptins belong to a family of GTP binding proteins and are found in several eucaryotes, participating in different cytoskeletal cell processes. The septins have a central GTP binding domain (G domain) flanked by an amino-terminal and a carboxy-terminal regions. The septins are characterized by the ability to interact with each other forming heterocomplexes which polymerize themselves, forming filaments. The only solved structure of a septin complex is a hexamer, formed by two subunits of three different human septins: SEPT7-SEPT6-SEPT2- SEPT2-SEPT6-SEPT7. This structure revealed that the filament arrangement involves conserved interaction between G domains, being the remainder of the structure disordered in the crystal. Moreover, two types of interface alternate along the filament were shown, socalled G interfaces (which include the nucleotide binding region of the two subunits) and NC interfaces (which include the N- and C- terminal regions of G domain). Plenty of evidences suggest that C-terminal regions of the protein are the main responsible for the selection of the correct interaction partner to assembly of heterocomplexes. In this context, it was sought to evaluate the importance of the C-terminal regions in the selection of the partnerships SEPT6 and SEPT7 to form the NC interface, against the G domain. For this, a chimerical septin was designed so that contains the G-domain of SEPT2 and the C-terminal of SEPT6, creating SEPT2G6C. The SEPT7GC, SEPT6GC, SEPT2GC and SEPT2G6C proteins were expressed and purified individually. Thermal stability and protein-protein affinity analysis of the pairs indicated that the chimera was able to interact with SEPT7GC, forming the heterodimer SEPT7GC-SEPT2G6C, which, however, did not show as stable as the physiological heterodimer. The importance of nucleotide binding to the interaction through G interface was also evaluated and, for that, SEPT2 mutants on GTP-domain were constructed, SEPT2T78M and SEPT2D185N, whose important residues in the hydrolysis and linking of nucleotide, respectively, were changed. Oligomerization analysis by size exclusion chromatography showed a shift in the elution volume of proteins expressed alone and coexpressed with SEPT6, indicating that the complexation of proteins to form G interface depends on the nucleotide binding, but not on its hydrolysis. Finally, the thermal and structural stability and the propensity to amyloid formation of heterodimer SEPT6G-SEPT2G were evaluated, which showed greater structural stability when compared to SEPT2 homodimers, but still exhibited alteration of its structure to a state that was able to bind Thioflavin-T, suggesting amyloid formation. However, this was observed at temperatures around 30 ºC above that observed for the homodimer, confirming the greater conformational stability of the heterodimer and suggesting that the formation of G interface with the right partner can be an important factor of the amyloid filament prevention at physiological temperatures.
Souza, Tatiana de Arruda Campos Brasil de. "Estudos funcionais e estruturais das septinas humanas 6, 8 e 10". [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/316870.
Testo completoTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-15T21:46:33Z (GMT). No. of bitstreams: 1 Souza_TatianadeArrudaCamposBrasilde_D.pdf: 2667585 bytes, checksum: 67a64b614fe46e32c061e0f43f20406e (MD5) Previous issue date: 2010
Resumo: Para que a divisão celular ocorra é necessário que uma célula passe por algumas etapas que possibilitem esta divisão. Ao conjunto destes processos denomina-se ciclo celular. A regulação espacial e temporal destes processos é fundamental para a preservação celular e do material genético. Falha neste processo pode levar à morte celular ou a alterações genéticas causando divisão desregulada e crescimento de tumores. Dentre diversas proteínas envolvidas no ciclo celular, encontram-se as septinas. Até o momento, foram encontrados em humanos 14 diferentes genes para septinas. Septinas são proteínas ligadoras de GTP, primeiramente caracterizadas em leveduras, que estão associadas a eventos biológicos importantes em eucariotos. Neste trabalho foram selecionadas três septinas humanas para estudos funcionais e estruturais: septina 6, septina 8 e septina 10. Nossos resultados deram origem a três artigos que descrevem: I) estratégias de clonagem, expressão, purificação e caracterização preliminar da septina humana 8; II) a capacidade das septinas 2, 6, 8 e 11 em ligar e hidrolisar GTP, mas com diferentes níveis de atividade GTPásica, sendo a septina 2 humana capaz de hidrolizar GTP mais rapidamente que as demais septinas e III) a interação entre a septina 10 humana e a proteína Promyelocytic leukemia zinc finger (PLZF), cuja expressão em linhagens celulares hematopoiéticas resultam na supressão do crescimento e interrupção do ciclo celular. A interação da septina 10 com a proteína PLZF foi confirmada in vitro por experimento de pull-down e a localização celular da septina 10 mostra que esta septina é expressa no citoplasma da célula. Além disso, resultados preliminares mostram a relação da ligação de GTP e formação de filamentos pela septina 6 e diversas estratégias para a cristalização das septinas estudadas como: microseeding, streak-seeding, variações de pH, precipitantes e aditivos, metilação de lisinas e screening de tampões, cujos resultados não foram satisfatórios para a resolução de uma estrutura de septina humana
Abstract: A cell passes through some steps to enable for cell division and all these processes are called Cell Cycle. The spatial and temporal regulation of this process is crucial to maintaining cellular and genetic material. Failure in this process can lead to cell death or genetic changes causing division and unregulated growth of tumors. Among several proteins involved in cell cycle, there are the septins. To date, 14 different human genes coding for septins were found. Septins are GTP binding proteins first characterized in yeast, which are associated with important biological events in eukaryotes. In this study we selected three human septins to study functionally and structurally: septin 6, septin 8 and septin 10. Our results led to three articles that describe: i) strategies for cloning, expression, purification and preliminary characterization of human septin 8; ii) the ability of septin 2, 6, 8 and 11 to bind and hydrolyze GTP, but with different levels GTPase activity, human septin 2 is capable of hydrolyzing GTP faster than the other septins and III) the interaction between the human septin 10 and promyelocytic leukemia zinc finger protein (PLZF), whose expression in hematopoietic cell lines results in growth suppression and cell cycle arrest. The interaction between septin 10 and PLZF was confirmed by in vitro pull down assay and the cellular localization of septin 10 shows that this septin is expressed in the cell cytoplasm. Furthermore, our studies preliminary results show the relation of GTP binding and filament formation of the septin 6 and several strategies for the crystallization of septins as micro-seeding, streak-seeding, variations in pH, precipitants and additives, methylation of lysine and screening of buffers, but the results were not satisfactory for the resolution of a human septin structure
Doutorado
Genetica de Microorganismos
Doutor em Genetica e Biologia Molecular
Morais, Sinara Teixeira do Brasil. "Estudos estruturais da SEPT8 e análise de suas interações com SEPT5 e SEPT7". Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-05082014-082458/.
Testo completoSeptins are GTP-binding proteins that interact with each other to form heterocomplexes, which form filaments and higher order structures. These filaments are important for cytokinesis and may be involved in other cellular processes such as the determination of cell polarity and cytoskeleton reorganization. The septins, initially discovered in Saccharomyces cerevisiae, have also been identified in fungi, green algae, mammals but not in plants. Typically, septins have three structural domains comprising a central GTP binding domain flanked by a variable N-terminal and a C-terminal which can contain coiled-coil structures. This work sought to characterize the GTP-binding domain of the human septin 8 (SEPT8G) through biophysical studies. Accordingly, SEPT8G was efficiently produced in E. coli, and its dimeric state in solution was confirmed by size exclusion chromatography. Compared to other septins previously reported, the dimeric SEPT8G presented itself as an apo-protein. GTPase activity assays were performed, confirming the inability of this septin to hidrolyse GTP. Additionally, thermal stability analyses by Circular Dichroism showed that the presence of the magnesium ion leads to a decrease of structural stability. Considering previous results of septins interactions from yeast two-hybrid experiments, we have analyzed the interaction between the septins 7, 8 and subsequently among septins 5, 7 and 8. Co-purification of the complex formed by the septins 7 and 8 showed to be dependent on the complete SEPT7 C-terminal region so that, when absent, the interaction was significantly impaired. The obtained complex formed by septins 5/7/8 contained the three proteins in soluble and equimolar fractions, providing a new septin heterocomplex for functional and structural studies.
Castro, Danielle Karoline Silva do Vale. "Reconhecimento molecular de septinas: estudos da interface entre SEPT7 e SEPT12". Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/75/75133/tde-04122018-135816/.
Testo completoThe septin family of proteins is characterized by their ability to bind guanine nucleotides and associate into filaments. Several biological functions have been reported for these filaments and their dissociation may be related to pathologies. Human septin is 12 specifically expressed in testes and has been identified in filaments that form the sperm annulus, whose integrity is related to its morphology. Although many studies have been reported, the molecular and physiological bases of septin filament function and self-assembly have yet to be completely elucidated. This study aims to obtain structural information for the nucleotide binding domain of SEPT12 (SEPT12G), the SEPT12GT89M mutant and the SEPT7-SEPT12 heterodimer. Expression of these proteins was performed in E. coli Rosetta(DE3) strain using the pET28a (+) and pETDuet-1 expression vectors. Purification was performed by affinity and size exclusion chromatography. The SEPT12G protein was submitted to an evaluation of its oligomeric state, intrinsic fluorescence, nucleotide content, GTPase activity and thermal transition. The oligomeric state and nucleotide content of SEPT7-SEPT12 was also evaluated. Crystallization assays were performed for all proteins. Data collection on line I24 of the Diamond Light Source (Didcot, England) resulted in high-resolution data sets for SET12G and SEPT12GT89M but only low resolution data for the SEPT7NGc. Biophysical studies showed that SEPT12G was obtained in its native form or, in other words, capable of binding and hydrolyzing GTP and that the purified heterodimer presented both proteins. The crystallographic structures were solved by molecular replacement allowing the identification of features characteristics of the group I septins (SEPT3, SEPT9 and SEPT12). The structure also confirmed that all the proteins of this group are able to form two different NC interfaces: open and closed. In addition, it reinforced the observation that the α5\' helix assumes a different orientation, whose function has not yet been clarified, but without doubt is a characteristic of this group which may be related to anchoring the polybasic regions whilst in the open conformation. The SEPT12T89M mutant crystal structure shows that the first shell coordination of the Mg2+ ion is altered, leading to an interruption of the universal switch mechanism and a consequent lack of catalytic activity. Finally, structural studies of the interaction between SEPT12 and SEPT7 were not possible, since all attempts resulted in crystals containing only SEPT7. This may be a consequence of SEPT12 precipitation or the crystallization condition used, destabilizing the heterodimeric interface.
Zeraik, Ana Eliza. "Caracterização estrutural e funcional de septinas de Schistosoma mansoni". Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-03012014-142505/.
Testo completoSeptins belong to the GTPase family of proteins and are involved in a variety of cellular processes. We have identified four genes encoding septins in Schistosoma mansoni, one of the main causative agents of schistosomiasis, these genes were named SmSept5, SmSept10, SmSept7.1 e SmSept7.2. The aim of this study was to clone the cDNA of these genes in order to subject the resulting proteins to a set of biophysical and functional studies. Biophysical characterizations were undertaken with SmSEPT5 and SmSEPT10 because of the higher solubility of these proteins, which were dimeric in solution and stable over a wide range of pH, although increasing temperatures promoted the aggregation of these proteins. The nucleotide binding assays revealed that both were capable of binding GTP and GDP, although only SmSEPT5 presented GTPase activity. Mg2+ has shown to be essential for GTP binding in both proteins while GDP binding was independent of this cofactor. Crystallization assays with the GTPase domain of SmSEPT10 have resulted in crystals of high quality and consequently high resolution structures were obtained: 1.9 Å to the GDP bound form and 2.1 Å to the GTP bound form, the best resolution achieved to date for any septin member. The sobreposition of the structures obtained enabled us to observe a strand slippage in β3 strand suggesting that it might be part of an activation mechanism involved in the association of these proteins to membranes. A coexpression system was produced, in which SmSEPT5, SmSEPT10 and SmSEPT7.2 were coexpressed and copurified. These proteins were able to assemble into heterocomplexes that further polymerize into filaments. Functional studies performed with a drug (FCF) that affects the dynamics of septin filaments have resulted in a reversible paralysis phenotype in the parasite. Immunolocalization experiments revealed the colocalization of septins and actin in muscular structures of the parasite, suggesting that the interaction of septin and actin filaments might have an important role in the motor activity of the parasite. The immunolocalization also revealed the presence of septins in the ephitelial plates of miracidia, germ cells of miracidia and sporocysts and protonephridia of cercariae. The results presented here constitute the first description of septins in phatyhelmintes and enabled us the establishment of structural and functional relaltionships among septins from S. mansoni and analogous septin complexes in other organisms, contributing to elucidate the function of this family of proteins.
Silva, Sabrina Matos de Oliveira da. "Estudos de aspectos estruturais importantes na montagem de filamentos de septinas humanas". Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/75/75133/tde-11102016-133148/.
Testo completoSeptins belong to a highly conserved family of guanine nucleotide binding proteins, capable of forming filaments. Despite their importance for several critical cellular events including cell division, little information is available about their molecular functions and the mechanism which leads to the formation of hetero-oligomers. The aim of this thesis was the cloning, co-expression and crystallization of septins and their complexes (SEPT9-SEPT11-SEPT7; SEPT2-SEPT6-SEPT7-SEPT9; SEPT4-SEPT6-SEPT7 and SEPT4-SEPT8-SEPT7), followed by comparative structural analysis. The cDNAs coding for the proteins SEPT9, SEPT6, SEPT2, SEPT11, SEPT8, SEPT4, SEPT9GCα0 (residues 262-568) and SEPT9GC (residues 279-568) were successfully cloned into transferable or expression vectors. The best characterized complex was that composed of SEPT2-SEPT6-SEPT7-SEPT9GCα0, which was confirmed by LC-MS/MS analysis after triptic digestion, unveiling the in vitro production of a tetrameric septin complex. Additionally, we characterized the hetero-dimer formed by SEPT7NGc-SEPT9GC. However, the most fully investigated proteins were the constructs SEPT9GCα0 and SEPT9GC which were studied individually for biophysical and structural characterizations. SEPT9GCα0 was highly unstable contrasting with SEPT9GC that was efficiently produced and characterized. The presence of the oligomeric state of SEPT9GC (monomer) was confirmed by molecular exclusion chromatography. The protein was produced in the apo form and was capable of hydrolyzing GTP. The affinity of SEPT9GC for GDP and GTPγS nucleotides was evaluated by Isothermal Titration Calorimetry (ITC) revealing that SEPT9GC has a higher affinity for GTPγS, with a Kd of 25.9 µM, which is dependent on the presence of Mg2+. Crystallization studies of this protein were performed, obtaining high quality crystals of protein complexes with GDP and GTPγS. Interestingly, the structure of the complex of SEPT9GC with the nucleotide GTPγS was obtained by soaking a previously grown crystal of the GDP complex. This is the first report of the application of this method for septins. Finally, we have obtained three sets of crystallographic data, two for SEPT9GC-GDP, at resolutions of 2.8 Å and 2.1 Å, and one set of data for SEPT9GC-GTPγS at 2.8 Å. Among the main characteristics observed in the SEPT9GC structure is the NC interface responsible for filament polymerization, which is shown to vary according to the type of bound nucleotide, with foreshortening of the filament in the presence of GTPγS. This indicates communication between consecutive G and NC interfaces along the filament. The conformational change at the interface involves the rearrangement of residues which are highly conserved in all septins as well as several which are SEPT9 group specific and may have implications for filament assembly and membrane association.
Denis, Pierre. "Les polyarthrites septiques". Clermont-Ferrand 1, 1988. http://www.theses.fr/1988CLF13005.
Testo completoMarques, Ivo de Almeida. "Estudos estruturais de septinas: explorando interações entre subunidades de filamentos de septinas humanas". Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-09122010-101622/.
Testo completoSeptins are a conserved family of cytoskeletal proteins belonging to the superclass of the Ploop-GTPases, involved in various cellular processes. In humans, some septins are also linked to cases of pathology. Their sequences are divided into three domains: an N-terminal domain, a GTPase domain and a C-terminal domain, which usually is predicted to form a coiled coil. The main feature of the family is the ability of its members to form filaments composed of different septins. In 2007, Sirajuddin et al presented the first and only crystal structure of acomplex of septins, formed by septins 2, 6 and 7. Although the C-terminal domains were present, they showed no electron density, indicating disorder. Thus, this structure provides little structural information concerning their nature. Currently, there are four septin structures deposited in the PDB: the 2/6/7 complex and three structures of SEPT2 lacking the Cterminal domain . Based on the absence of structural information at atomic resolution about the C-terminal domains and the low quality of the few existing structures we set out to characterize both biochemically and structurally the C-terminal domains of selected human septins as well as to obtain the crystal structure of SEPT3-GC (a construct containing the GTPase and C-terminal domains). It is noteworthy that SEPT3 belongs to the only group of septins that are predicted to lack the C-terminal coiled coil and for which no crystal structure is available. We have expressed and purified the C-terminal domains of SEPT2, SEPT6 and SEPT7 (SEPT2-C, SEPT6-C and SEPT7-C). We show that they form homo-dimers and that SEPT6-C and SEPT7-C form a hetero-dimer (KD 15.8 nM), SEPT67-C. Both SEPT6-C and SEPT7-C were unstable, but SEPT67-C and SEPT2-C (KD 4 μM) were both stable at high concentrations. NMR measurements showed that SEPT2-C has two dynamically different regions, a central one which is -helical, and two extremities which are unstructured. Constructs were designed for the central regions of the C-terminal domains of septins 2, 4, 6 and 7 (SEPT2-CC, SEPT4-CC, SEPT6-CC and SEPT7-CC). We have obtained crystals of SEPT2-CC, SEPT4-CC and SEPT6-CC and have solved the structure of SEPT4-CC which unexpectedly is observed to form an anti-parallel coiled coil. We use this observation to propose, for the first time, a possible mechanism for the formation of cross-links between septin filaments. Crystals were obtained for SEPT3-GC its structure solved at 2.9 Å. We observe that SEPT3-GC forms filaments in the crystal, employing the same two interfaces previously described for other structures. We compare the structure obtained with those from the literature and observe significant differences in some regions of the molecule as well as differences in the relative orientation of the subunits. It should be noted that the structure of SEPT4-CC is the first structure of a septin coiled coil and that the structure of SEPT3-GC is the first structure of a septin from group I. In conclusion, this study presentsm results which will assist in the understanding of this intriguing protein family, including observations pertinent to filament formation and cross-linking.
Arbizzani, Federica. "Régulation de la cytokinèse par les lipides membranaires et les septines chez la levure S. pombe". Thesis, Paris Sciences et Lettres (ComUE), 2019. https://tel.archives-ouvertes.fr/tel-02887503.
Testo completoCell division is an essential process required for the proliferation of unicellular organisms, for the development of multicellular organisms, as well as for cell renewal within tissues and organs. Defective control of cell division can either lead to cell death, or to cell hyper-proliferation and contribute to cancer progression. Cell division is therefore under the control of very tight regulatory mechanisms. In animals and fungi, its final step, cytokinesis, requires an acto-myosin-based contractile ring that constricts to promote sister cell cleavage. Modifications in the lipid composition of the plasma membrane take place during cell division, with functional impact on cytokinesis.Fission yeast is a simple single cell eukaryotic organism which has been extensively used to study cell division because of its stereotyped rode shape, easy genetics and short generation time. In particular, this model system has proved very powerful for the molecular dissection of contractile ring assembly. However remarkably little is known on how membrane lipids regulate contractile ring assembly. In the first part of my PhD, my objective was to study how lipids could regulate contractile ring positioning in fission yeast. I have combined fission yeast genetics with live-cell imaging of contractile ring assembly from precursor nodes to understand how ergosterol levels affect division plane positioning. I have found that increased ergosterol levels prevent F-actin assembly from cytokinetic precursor nodes by the formin Cdc12, avoiding their compaction into a medially placed contractile ring. Since the stability of F-actin cables was not altered altogether and the phenotype could be partially rescued by inhibition of the Arp2/3 complex which competes with formins, we propose that increasing ergosterol levels in the plasma membrane may inhibit the activity of the formin Cdc12.In addition to the contractile ring, cytokinesis involves an additional component of the cytoskeleton, the septins, which form filaments at the division site. Septins are a family of conserved GTP binding proteins whose deletion leads to cytokinetic defects. They also serve as scaffolds for protein-protein interactions and/or as diffusion barriers for protein compartmentalization in cytokinesis and beyond. In fission yeast, in contrast to budding yeast, septins are late at the division site and are only involved in late stages of cytokinesis, to promote sister cell separation. In the second part of my PhD, I decided to explore the dynamic behavior of septins and decipher how they are regulated. Using live cell imaging and precise cell cycle timers, I have identified a new step in the recruitment of septin to the cell cortex in the proximity of the contractile acto-myosin ring, in a broad meshwork that then compacts into a tight ring. I have also found evidence that the anillin-like protein Mid2 is necessary to promote this compaction and may act as a bundler for septin filaments. However, analysis of mutants blocked in mitosis shows that this protein is not sufficient to accomplish this task. Moreover, I have determined that high Cdk activity allows septins and Mid2 initial recruitment and assembly, but the SIN pathway also plays a role in promoting their recruitment at the cell middle and is then required to drive their compactio. Additionally, I have found that PIP2 levels influence not only the amount of septins and Mid2 filaments associated at the medial cortex together with their compaction but also the timing of septin recruitment to the division site. This demonstrates that septin assembly relies on complex regulations coordinated by the cell cycle machinery
VIGNAUX, FRANCOIS. "Les thrombophlebites cerebrales septiques". Angers, 1991. http://www.theses.fr/1991ANGE1096.
Testo completoRodrigues, Nathalia de Campos. "Estudos estruturais do domínio GTPase isolado da septina humana SEPT4 e estrutura cristalográfica da Glutationa -S- Transferase de Xylella fastidiosa". Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-05122008-152844/.
Testo completoThe septins are a conserved family of guanine nucleotides-binding and hetero-filament forming. proteins. In mammals they are involved in a variety of cellular processes, such as cytokinesis, exocytosis, and vesicle trafficking. SEPT4 has been reported to accumulate in tau-based filamentous deposits and cytoplasmic inclusions in Alzheimers and Parkinsons diseases respectively. Sept4 is unique in its association with the aberrant protein depositions in both types of diseases. Further studies on the biochemical, structural properties and physiological functions of Sept4 may therefore provide important insights into the common mechanism underlying diverse neurodegenerative disorders. Thermal unfolding of the GTPase domain of SEPT4 (SEPT4-G) revealed an unfolding intermediary which rapidly aggregates into amyloid-like fibers under physiological conditions. In this study, the kinetic analysis of aggregation of SEPT4-G was monitored using extrinsic fluorescence and circular dichroism spectroscopy. The aggregates have the ability to bind specific dyes such as Thioflavin-T (ThT), suggesting that they are amyloid in nature. Fibrils formation was monitored by the increase in ThT emission and electron microscopy as a function of temperature, pH, metal ions and protein concentration. Glutathione S-transferases (GSTs) form a group of multifunctional isoenzymes that catalyze the glutathione-dependent conjugation and reduction reactions involved in the cellular detoxification of xenobiotic and endobiotic compounds. GST from Xylella fastidiosa (XfGST) was crystallized by the vapour-diffusion method and its crystallography structure was solved for molecular replacement and refined. Afterwards, sequential and structural analyses were carried out for XfGST and others GSTs.
Mendonça, Déborah Cezar. "Automontagem de filamentos de septinas estudada por microscopia eletrônica". Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-04062018-115405/.
Testo completoSeptins are GTPases that appear to be a novel component of the cytoskeleton. These proteins interact with each other to form filamentous heterocomplexes and high order structures which are important for cytokinesis and a variety of other cellular processes. There are many mechanistic aspects of these proteins that are not fully understood, including how the heterocomplexes correctly assemble. In humans, there are 13 genes encoding septins, classified in four groups based on primary structure. The SEPT7-SEPT6-SEPT2-SEPT2-SEPT6-SEPT7 hexameric complex was the best characterized, with a crystalline structure solved at 4 Å. According to Kinoshita´s Rules, the septins of this complex can be replaced in this arrangement by others belonging to the same group. In this work, we used transmission electron microscopy with single particle analysis to study two septin complexes. One of the complexes studied in this project is composed of three human septins, for which there is currently no structural information available. The SEPT5-SEPT6-SEPT7 complex was heterologously expressed in E. coli and purified at high salt concentration to avoid polymerization. Single particle analysis of negatively stained samples showed the presence of elongated particles of approximately 25 nm in length. To locate SEPT5 in the complex, a fusion with MBP (Maltose Binding Protein) and immunoblotting with anti-SEPT5 monoclonal antibody was performed, concluding that SEPT5 is located at the end of the hexameric complex. However, SEPT5 belongs to the same group as SEPT2, which was reported to be located in the center of the hexamer. This result allowed for a new discussion on the way that septins form heterocomplexes and also, on how the sensitivity of the NC interface in related to salt concentration, analogous to that observed in the heterocomplex of Saccharomyces cerevisiae. A Ciona intestinalis complex including SEPT2, SEPT6, SEPT7 and SEPT9, also expressed heterologously in E. coli, was prepared by negative staining. The single particle analysis of the collected images showed an apparently hexameric heterocomplex, although an octamer was expected due to the presence of the four different septins, one belonging to each of the four groups. The results of this work represent advances in the understanding of the formation of septin heterocomplexes and how these proteins interact with each other during assembly.
Macêdo, Joci Neuby Alves. "Estudos estruturais e funcionais de septinas humanas: a ligação e hidrólise de GTP por SEPT3 e a busca de parceiros funcionais de SEPT1, SEPT5 e SEPT7". Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-28092010-155704/.
Testo completoSeptins are proteins that belong to the superfamily of GTPases, which were initially identified in Saccharomyces cerevisiae, and then in higher eukaryotes, except plants. These proteins are involved in a variety of cellular processes such as chromosome segregation, cell polarity, membrane dynamics, vesicle trafficking, exocytosis, apoptosis, among others. Mutations or changes in the expression of septins have been associated with various cancers and neurological diseases. Aiming to provide functional information about these proteins, the human septins 1, 5 and 7 were used as baits in yeast two-hybrid assay in order to identify their protein partners. After screening cDNA libraries from human leukocytes and fetal brain, the protein partners predominantly found were septins from others groups. The septin-septin interactions involved the GTP binding domain. Others non-septins interactors have also been identified in the libraries and were functionally related to endocytosis, the regulation of the GTPase activity, intracellular trafficking, sumoylation, maintenance of metaphase plate and centrosome maturation. Some of these functions are new and were related to the septins for the first time. This work also focused on the biophysical characterization of the septins 3 and 5 (SEPT3 and SEPT5). Many different protocols were developed aiming to obtain homogeneous samples of SEPT5, but were not successful. On the other hand, recombinant SEPT3, without the amino-terminal domain (SEPT3GC), was produced in a homogeneous form in E. coli. SEPT3GC is monomeric in solution as confirmed by size exclusion chromatography and small-angle X-ray scattering (SAXS). Also, SEPT3GC has shown to be active and able to hydrolyze GTP in vitro. The SEPT3GC affinity by GTPγS and GDP were evaluated by isothermal titration calorimetry (ITC). The KD for GTPγS was about 5,43 μM and it was observed to be Mg2+ dependent. The binding to GDP was not detectable. SEPT3GC aggregates induced by temperature were able to bind the thioflavin-T fluorescent probe, suggesting an amyloid nature for such structures.
Sales, Elisa Morandé. "Estudo das interações proteína-proteína, proteína-membranas e proteína-agentes desnaturantes por espalhamento de raios-X a baixos ângulos". Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-22052018-152931/.
Testo completoIn this work we have used small-angle x-ray scattering (SAXS) to study four systems of biological interest. We aim to investigate the self aggregation of proteins and protein complexes that would form amyloid fibers; protein/protein interaction, simulating high concentrations; protein/cell-membrane interaction, simulating extracellular matrix vesicles (MVs) from biomineralizing systems; and protein/denaturating-agents interactions. On the case of amyloid formation, we have investigated the aggregation of G-domain of septin-6 (SEPT6G) and the protein complex formed with G-domain of septin-2 (SEPT2G-SEPT6G). At temperatures lower than 15°C, both SEPT6G and SEPT2G-SEPT6G were found predominantly as dimers. At 25°C, SEPT2G-SEPT6G heterodimer is still stable while aggregates of SEPT6G grow. Both coexist in solutions of SEPT2G-SEPT6G dimers, with the percentage of dimers decreasing the higher the temperature. As for the study of MVs, we have shown that DPPC and DPPC:DPPS (9:1) liposomal mimetics have the same structural characteristics at the absence or presence of Calcium. The interaction with human annexin V protein (A5), related to biomineralization processes, affects the model membrane by the creation of nanopores. The addition of tissue-nonspecific alkaline phosphatase (TNAP) does not change the structural properties of the proteoliposome when A5 is present. The addition of SDS surfactant (30 mM) does not alters the conformation of bovine serum albumin (BSA), and we have observed the formation of SDS micelles coexisting with free protein in solution. The addition of 50 mM of SDS, on the other hand, induces the partial unraveling of the protein, as seen by the analysis of SAXS data via the pearl necklace\'\' model. The effect of adding 3M and 8M urea is, respectively, the partial and total unraveling of BSA, with ensuing aggregation of the protein dependent on the temperature (T > 30°C). The introduction of SDS 6mM promotes further unraveling in proteins that were previously partially unraveled by urea. The resulting effective potential for the interaction between BSA and lysozyme at total concentration of 100mg/ml and 7.0 pH has been obtained from the analysis of SAXS curves. In order to obtain this result we have used a simplified analysis (first order approximation) in which were considered the effective potentials for the interactions between BSA-BSA, lysozyme-lysozyme and lysozyme-BSA. We have varied the BSA:LISO molar ratio up to 1:42. At the studied pH, BSA has a surface residual charge of -11e, and lysozyme has +9e. As we changed the BSA:LISO molar ratio, we have found two regimens for the resulting effective potential: i) up to BSA:LISO 1:2, the effective charge of the system is virtually zero and the resulting potential is attractive; and ii) for BSA:LISO between 1:3 and 1:42 the effective charge increases, and the resulting potential is repulsive. Therefore, both lysozyme and BSA coexist without forming aggregates, by a delicate balance of attractive and repulsive forces.
Faty, Mamadou. "Septines : fonctions et organisation structurale". Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAJ107.
Testo completoSeptins form a family of GTPases conserved in fungi and animal cells [Kinoshita etal., 2003]. During cell division, they localize at cytokinesis sites and are essential for this process in budding yeast, Drosophila embryos and cultured mammalian cells [Fatyet al., 2002].In budding yeasts, septins, composed of parallel networks of filaments [Byers et al.,1976], form a mother-daughter neck ring. This ring is closely associated with the plasma membrane and constitutes a scaFold for the recruitment of myosin II and other cytokinetic factors at the future cleavage site [Longtine et al., 2003]. In addition, the septin ring contributes to the formation of a lateral diffusion barrier on the plasma membrane, which helps maintain the factors of cell polarity in the bud [Barral et al.,2000; Takizawa et al., 2000].In metazoans, septins are also required for compartmentalization of the cellular cortex [Schmidt et al., 2004; Joo et al., 2005] and are involved in a myriad of cellular processes, including assembly and orientation of the polar body of the spindle [Kusch etal., 2002; Spiliotis et al., 2005], exocytosis and vesicular transport [Hsu et al., 1998;Beites et al., 1999], cell migration [Finger et al., 2003], and apoptosis [Larisch et al.,2000; Gottfried et al., 2004].[...]The set of results presented highlights the molecular arrangement of the monomersin the septin complex and suggests that the septin complexes assemble in filaments and higher order structures at the bud neck in Saccharomyces cerevisiae. Thus, wepropose that septins form the fourth component of the cytoskeleton
Kattani, Narimane Al. "Effet de la combinaison de l'hypertension et de l'infarctus du myocarde sur la physiopathologie du choc septique : mise au point d'un modèle animal expérimental mimant le phénotype des patients septiques". Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0176.
Testo completoSeptic shock is considered as the most common cause of death among patients admitted in medical intensive care units. Mortality remains very high (50%) despite advances in physiopathological knowledge of this disease. In fact, most experimental studies are often conducted on young and healthy animals, whereas it is well established that the incidence and mortality rates dramatically increase with age. The goal of this study was to evaluate the effect of the combination of two diseases (hypertension and myocardial infarction) in a septic rat model, on cardiovascular function, cell survival and the inflammatory response. Therefore, we used normotensive Wistar-Kyoto rats (WKY) and Spontaneously Hypertensive Rats (SHR) in which myocardial infarction was induced by left coronary descending artery ligation, followed or not by cecal ligation and perforation-induced sepsis. Our results showed that the polypathological SHR rats in which a myocardial infarction and sepsis were induced, exhibited a significant decrease in cardiac and hemodynamic parameters compared to WKY rats that have sepsis (CLP) only. Indeed, cardiac output, mean arterial pressure and ejection fraction were reduced by 70%, 60% and 67% respectively in the polypathological SHR rats versus the WKY rats with sepsis. We observed also that the vascular hyporeactivity in the polypathological SHR rats was higher than for the WKY CLP rats. A mesure of gene expression level of alpha1 adrenergic receptor shows a relatively low expression level in the rats from SHR IDM CLP rats compared to WKY CLP that could explain the observed vasodilation. The protein level of caspase3 and 8, Pp38 and proteins involved in apoptosis, is upregulated in SHR IDM CLP rats compared to WKY CLP rats. However, the polypathological SHR rats show a significant decrease in the expression of eNOS and Akt protein compared to WKY CLP rats. The combination of hypertension with myocardial infarct is associated with higher sensitivity of the rats to sepsis. The polypathological SHR rats developed a severe heart failure compared to WKY rats having sepsis only. Our animal model, the polypathological SHR rats is very close to observed clinical situations in intensive care units. This model could serve as a good candidate for pre-clinical studies
Friedl, Raimund. "Der Konkubinat im kaizerzeitlichen Rom : von Augustus bis Septimius Severus /". Stuttgart : F. Steiner, 1996. http://catalogue.bnf.fr/ark:/12148/cb376196441.
Testo completoGOVINDARAJU, SOPHIE. "Arthrites septiques dans la polyarthrite rhumatoide". Reims, 1992. http://www.theses.fr/1992REIMM055.
Testo completoLauney, Yoann. "Dysfonction hépatique septique : rôle des catécholamines". Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1B023.
Testo completoSevere sepsis is a major health problem. Its high mortality rate over the world is the result of a dysregulated host response to sepsis including an exaggerated inflammation response and immune suppression. Septic shock is the most severe expression of sepsis, including cardiovascular failure and other organ failure. The liver, a major organ involved in the defense and stress response induced by sepsis may also be a victim of this inflammatory response to infection. A hepatocellular dysfunction (HCD) can develop and evolve to the organ failure. In this case, the liver failure is associated with poor prognosis in septic shock in the early course of sepsis. Here, we have shown in a large prospective cohort of patients with septic shock that the HCD was associated with long-term mortality. Despite a better understanding of the pathophysiology of sepsis, especially liver changes, the impact of treatment used during septic shock, such as catecholamines (epinephrine, norepinephrine), remains unknown. The preliminary work of our team had demonstrated the proinflammatory effect of adrenaline on a hepatocyte culture model. In this work, we studied the influence of hepatocyte environment especially Küpffer cells. Thus, we used a co-culture model including hepatocytes (HepaRG) and macrophages (differentiated THP1 PMA) stimulated by lipopolysaccharide (LPS) and / or adrenaline. The gene expression and the cytokine profile analysis allowed to identify adrenaline as a factor able to shift the immune response to a proinflammatory state even if macrophages developed an anti-inflammatory response, indicating a deleterious effect of adrenaline on liver defense mechanisms
Sala, Fernanda Angélica. "Estudo da interação entre domínios C-terminais de septinas humanas: implicação na formação e estabilidade do filamento". Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/75/75133/tde-10082015-140053/.
Testo completoSeptins comprise a conserved protein family that binds guanidine nucleotide and forms heterofilaments. In structural terms they have a common organization: a central GTPase domain, a N-terminal domain and a C-terminal domain, this last one is predicted to form coiled coil structures. Currently, the human septin heterocomplex best characterized (SEPT2/SEPT6/SEPT7) reveals the importance of the GTPase domain in filament assembly, however the absence of electron density for the C-terminal domains makes its function still unknown. Studies with mammals septins, and of others organisms like C. elegans and S. cerevisea suggests that some septins groups (e.g. II e IV in mammals) interact via its C-terminal domains and this could act in a determinative way to correct filament assembly. In this way, this project aimed to study the homo/heterotypical affinity for the C-terminal domains of human septins belonging to groups II (SEPT6C/8C/10C/11C) e IV (SEPT7C), investigating whether this domain contributes with the preference of septins to interact with proteins of different groups during assembly of the heterofilament. The C-terminal domains were expressed in E. coli and purificated. It was carried out studies using analytical ultracentrifugation and circular dichroism spectropolarimetry tecniques which allowed identification of major affinity and stability in the heterotypical association compared to homotypical. It was measured apparent dissociation constants for homodimers of low µM range while for heterodimers our group\'s data shows dissociation constants in the nM range. To understand at atomic level the factors responsible for this significant preference in the C-terminal domains interaction between groups II and IV was performed molecular modelling studies and analysis of the primary sequence. These analysis suggests the presence of a high number of charged residues in position a of the coiled coil as responsible for selectivity. Consequently, the heterodimer would be therefore favoured because of the minor repulsive effect coming from the staggered of charged residues in a. Thus, these results indicate the crucial or cooperative action of C-terminal domains in preferential organization of septins during filament assembly, favouring the NC interface between septins of groups II and IV.
Cabrejos, Diego Antonio Leonardo. "Especificidade na montagem de filamentos de Septinas: o caso da interface G entre SEPT5 e SEPT8". Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-27102016-102703/.
Testo completoSeptins are a conserved family of proteins that bind and hydrolyze GTP and form heterofilaments, rings and networks in order to carry out their functions. They have three structural domains: an N-terminal domain containing a polybasic sequence (for membrane binding), a nucleotide-binding (G) domain and a C-terminal domain including a sequence predicted to form a coiled-coil. In humans, 13 septins have been classified into four groups (I, II, III and IV) based on their amino acid sequences. The only structurally characterized filament described to date is formed by SEPT2-SEPT6-SEPT7, which reveals that the subunits interact through two different interfaces (G and NC). The structural determinants of correct filament assembly are poorly known, and this is limited by the complexity of purifying and crystallizing trimeric or tetrameric complexes. An alternative approach is to study a single filament interface (G or NC) on its own. Here, we aimed to study, using biophysical and structural approaches, the G interface formed between SEPT5 and SEPT8 to elucidate the factors relevant to determining its specificity. The GTPase domain of SEPT5 and SEPT8, were cloned into the bicistronic expression vector pET-Duet, co-expressed and co-purified. Studies to determine the oligomeric state and homogeneity of the complex were conducted using size exclusion chromatography, dynamic light scattering and analytical ultracentrifugation, revealing a monodisperse dimer for SEPT5-SEPT8(G). The complex elutes with an approximately equimolar mixture of bound nucleotides (GTP and GDP) whereas SEPT8(G) alone is shown to be unable to bind either. Furthermore, the complex has a greater thermostability than SEPT8(G), demonstrated by an increase of 5°C in Tm. In order to determine the structural determinants of specificity, crystallization trials were conducted and crystals of the SEPT5-SEPT8(G) complex were obtained, but these diffracted to only very low resolution. In the absence of a crystal structure, homology modeling was performed to analyze the potential G interfaces between different septin combinations. An interaction between characteristic amino acids (those which are unique to given septin group) was identified for the complex formed between group III septins (including SEPT5) and group II septins (including SEPT8). This interaction, between Phe131 (group II) and Thr19 (group III) may explain the specificity in the formation of a G interface between septins of these groups during filament formation and furthermore the importance of GTP bound to the group II septin. These observations allow us to propose for the first time a plausible explanation for relevance of the loss of catalytic activity by this septin group, an unexplained fact up until now. Mutation of the identified residues resulted in a change in the elution profile of the complex from the size exclusion column suggesting structural alterations in the mutants.
Froidevaux-Klipfel, Laurence. "Implication des septines recrutées sur les microtubules tyrosinés et polyglutamylés dans la résistance au taxol de cellules cancéreuses mammaires MDA-MB 231". Thesis, Paris 11, 2011. http://www.theses.fr/2011PA114850/document.
Testo completoBreast cancer remains the leading cause of women mortality in France, and chemoresistance emergence, in particular to taxanes, including paclitaxel (Taxol®), is an important limitation to the use of these molecules. As do many anticancer drugs, taxanes target microtubules (MTs), tubulin polymers involved in many cellular functions. These alternate between growing and shrinking stages, thus providing dynamic instability. By binding to beta-tubulin, Taxol stabilizes MTs and prevents successful mitosis, leading to apoptosis. Taxol resistance is a multifactorial process including mechanisms such as overexpression of drug efflux pumps (P-glycoprotein), mutations in the genes for alpha- and beta-tubulin or altered expression of MT-associated proteins (MAPs) like the MT-stabilizing MAP4 or the depolymerizing stathmin, therefore contributing to MT dynamics restoration.The current project relies on the use of the breast carcinoma cell line MDA-MB 231 made gradually resistant to 25nM of Taxol under blocking conditions of efflux pumps. To get a broader insight into the protein modifications from the MT environment associated with the chemoresistant phenotype, we compared the proteomic profiles of total MT fractions from Taxol-sensitive (Tv) and Taxol-resistant (T8) cells. Among the 112 differentially enriched proteins found in one of the two populations, we evidenced increased levels of betaIII and betaIV-tubulins, a slight increase and a decrease of molecular motors kinesin-1 and dynein, respectively, and the enrichment of several septins (SEPT2, 8, 9 and 11) in MT fractions of T8 cells. Septins are GTPases that associate into hetero-oligomeric complexes involved in cytokinesis and in MT and actin cytoskeleton organization. Recruitment of these candidate proteins on MTs of T8 cells has been validated by Western blot analysis (Froidevaux-Klipfel et al., 2011) and immunofluorescence experiments.In the literature, septins localize either on actin or MTs in mammalian cells. Interestingly, in our MDA-MB 231 cells, SEPT2 is recruited partially on actin stress fibers in sensitive Tv cells, whereas it colocalizes with MTs in T8 ones. Although actin depolymerization in Tv cells does not induce any shift towards MTs, this differential localization of septins on MTs of resistant cells could nevertheless participate in the chemoresistant phenotype.Furthermore, it has been described in the literature that SEPT2 binds to polyglutamylated MTs to facilitate vesicular transport to the plasma membrane of proteins implicated in cell polarization. Polyglutamylation is a post-translational modification allowing the formation of side-chains of several glutamate residues on alpha- or beta-tubulins, thus regulating interactions between MTs and MAPs. Our results show that septin accumulation on the MT network of T8 cells is associated with an increase in polyglutamylation but also tyrosination of tubulin. In addition, cell viability assays showed that partial inhibition by RNAi of septins as well as polyglutamylases and tubulin tyrosine-ligase, but also overexpression of enzymes responsible for tubulin deglutamylation, could restore Taxol sensitivity of T8 cells. By contrast, overexpression of enzymes responsible for tubulin polyglutamylation and tyrosination in Tv cells could induce Taxol resistance of sensitive Tv cells.The compilation of our results enables us to provide a new mechanism of Taxol resistance of the breast cancer cells MDA-MB 231: an increased level of alpha-tubulin tyrosination would induce the lengthening of polyglutamylated chains on the MT, resulting in a reduced binding of the stabilizing protein MAP4 as well as the recruitment of septins on MTs. These modifications would promote the recruitment of the rescue factor CLIP-170 and that of depolymerizing kinesins such as MCAK to the growing end of the MT of resistant T8 cells, leading to a restoration of MT dynamics, thus contributing to the emergence of the chemoresistant phenotype.These studies are essential to lay the basis for a new mechanism of Taxol resistance involving septins, and a causal relationship to tyrosination and polyglutamylation. Beyond, the search for these key modulations will be performed on Taxol sensitive and resistant breast cancers, from patients’ biopsies. Thus, it will be eventually possible to determine whether septins, tubulin tyrosination and polyglutamylation have a real functional importance in breast cancer resistance to Taxol
Rimmelé, Thomas. "Purification sanguine au cours du choc septique". Phd thesis, Université Claude Bernard - Lyon I, 2010. http://tel.archives-ouvertes.fr/tel-00809032.
Testo completoChauvet, Valérie. "Le choc septique : evaluation d'une strategie therapeutique". Aix-Marseille 2, 1990. http://www.theses.fr/1990AIX20830.
Testo completoGADAY, VERONIQUE. "Incidence des metastases septiques dans l'endocardite infectieuse". Lille 2, 1994. http://www.theses.fr/1994LIL2M131.
Testo completoLukas, Volker. "Rhetorik und literarischer "Kampf" Tertullians Streitschrift gegen Marcion als Paradigma der Selbstvergewisserung der Orthodoxie gegenüber der Häresie ; eine philologisch-theologische Analyse". Frankfurt, M. Berlin Bern Bruxelles New York, NY Oxford Wien Lang, 2007. http://d-nb.info/98731307X/04.
Testo completoTavernier, Benoît. "Mécanismes cellulaires de la dysfonction myocardique du choc septique". Lille 2, 2000. http://www.theses.fr/2000LIL2MT13.
Testo completoLanzoni, Paola. "Interação não canônica entre septinas: a análise da interação na interface G entre SEPT3 e septinas do grupo II". Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-12092017-083405/.
Testo completoThe septins are accepted to be the fourth cytoskeleton component of the eukaryotic cells, after actin, myosin and intermediate filaments. They are filament forming proteins that are organized in fibers and rings, having a structural role in the cell. Humans express 13 septins, which are divided into 4 different groups according to their primary structure: group I (SEPT3, SEPT9, SEPT12); group II (SEPT6, SEPT8, SEPT10, SEPT11, SEPT14); group III (SEPT1, SEPT2, SEPT4, SEPT5) e group IV (SEPT7). SEPT13 was later characterized as a SEPT7 pseudogene. The best characterized filament is built up from SEPT2-SEPT6-SEPT7-SEPT9 (in this exact sequence), and is used as a basis for the description of the so-called canonical arrangement, which accepts that septins from the same group can occupy the same position within the filament. However yeast two-hybrid assays identified several unexpected interactions such as SEPT9-SEPT6 and SEPT9-SEPT8, raising the possibility that these could also exist in vivo. Furthermore, studies have shown the existence of interactions between group I and group II, and especially in the SEPT11-SEPT12, the interaction dissolves when a mutation in the G interface is inserted. The present work investigates the interaction between SEPT3, a group I septin, with all of those from group II. This interaction was studied through co-expression and co-purification methods using metal affinity chromatography, where only the SEPT3 contained the six histidines extention. This initial analysis showed that SEPT3 did not co-purify with all group II members, clearly pointing to variability in the affinity within group. Using this approach SEPT6, SEPT10 e SEPT14 showed no interaction with SEPT3, whilst SEPT8 and SEPT11 co-purified with SEPT3, but not in stoichiometric concentrations. For the SEPT3-SEPT8 and SEPT3-SEPT11 complexes, a second purification stage was performed using size exclusion chromatography, where a broad peak was observed corresponding to a molecular mass value which was intermediate between a dimer and a monomer. The same complexes, when evaluated by multiple angle light scattering revealed a variation in the molecular mass across the peak as it eluted. Such variation was compatible with elution of dimers at the beginning and monomers at the end. Studies for the SEPT3-SEPT8 interaction via analytical ultracentrifugation suggested a trend to associate in high protein concentration, consistent with the dissociation constant found by microscale thermophoresis, which was of the order of ten micromolar. The results raise questions concerning the physiological relevance of these complexes and reinforce the importance of further studies on the non-canonical assembly of septin complexes for cellular development.
Mattern, Torsten. "Gesims und Ornament : zur stadtrömischen Architektur von der Republik bis Septimius Severus /". Münster : Scriptorium, 2001. http://catalogue.bnf.fr/ark:/12148/cb41304240w.
Testo completoDirami, Thassadite. "Le transporteur anionique TAT1 (SLC26A8) : rôle physiologique et implication dans les asthénozoospermies humaines". Thesis, Paris 5, 2012. http://www.theses.fr/2012PA05T050/document.
Testo completoTAT1 (Testis Anion Transporter 1 ; SLC26A8) belongs to the SLC26 family of anion transporters, which is implicated in cellular homeostasis of different epithelia. TAT1 is exclusively expressed in male germ cells, in human and mouse. On mature spermatozoa, TAT1 is located at the annulus, a ring-shaped structure composed of different septins polymers (1, 4, 6, 7 and 12), at the junction of the midpiece (MP) and principal piece (PP) of the flagellum.The knock-out mouse model of Tat1 gene shows a male infertility by complete asthenozoospermia (lack of sperm motility) and capacitation defects combined with flagellar structural abnormalities (flagella bending, MP and PP disjunction and atrophy of the annulus). This model suggests that the TAT1 protein could fulfill structural roles in the annulus and during flagellum biogenesis. Moreover TAT1 displayind an anion transport activity, it could also be implicated in the control of sperm motility and capacitation by regulating anions exchannges, which are well known to be essential for both processes.Indeed, chloride, bicarbonate and calcium ions are involved in the activation of the cAMP/PKA pathway, controlling sperm motility and capacitation processes (i.e. maturation events occuring in the female genital tract and providing the spermatozoa an hyperactivation movement and the ability to interact with oocyte).Several publications have reported a physical and functionnal interaction between SLC26 family members and the chloride/bicarbonate CFTR channel (Cystic Fibrosis Transmembrane conductance Regulator), which mutations are responsible of cystic fibrosis. Interestingly, recent data showed CFTR expression in spermatozoa and its role in the regulation of chloride fluxes during capacitation. During my thesis, we tested TAT1 and CFTR cooperation; we showed that TAT1 can interact physically with CFTR and stimulate its anion transport activity, suggesting that in vivo they form a molecular complex involved in the regulation of chloride and bicarbonate fluxes during sperm capacitation.Like TAT1, several SLC26 family members have a tissue specific expression. Furthermore genetic mutations in several SLC26 members result in human pathology such as deafness, congenital chloride diarrhea and chondrodysplasia. According to the phenotype of the KO Tat1 mouse model and the role of SLC26 members in human pathology, TAT1 constitutes a good candidate for the search of genetic causes of human asthenozoospermia.During my thesis, the laboratory has set up, a research project aiming at identifying mutations in the TAT1 gene that are responsible for human asthenozoospermia.Sequencing of the TAT1 gene coding regions in a cohort of 147 infertile men presenting with asthenozoospermia allowed us to identify several new sequence variations in in the TAT1 gene. In vitro study of these variants shows that 3 of them are associated with protein instability and abrogate CFTR stimulation. Besides, patients sperm show important flagellar abnormalities in the midpiece, consistent with a role of TAT1 and its partners (septins) in flagellum biogenesis
Laviolle, Bruno. "Pharmacologie de la fludrocortisone dans le choc septique". Rennes 1, 2011. http://www.theses.fr/2011REN1B144.
Testo completoThe interest of low doses of hydrocortisone (HC) and fludrocortisone (FC) in the treatment of septic shock is controversial. We investigated the biological effects of the combination of HC+FC in septic shock, and the biological and hemodynamic effects of the two drugs, given alone or in combination, in healthy volunteers and in normal and endotoxemic rats. In septic shock patients, HC+FC induced the expected gluco- and mineralo-corticoid effects and these effects were observed simultaneously to the improvement of patient’s outcome. In healthy volunteers, using the same single doses than those used in septic shock, HC induced a more marked and earlier mineralo-corticoid effect than FC and induced transient hemodynamic effects whereas FC did not, and HC and FC decreased the pressor response to phenylephrine with additive effects. In rats, FC and HC increased blood pressure, this effect being more marked in endotoxemic than in normal rats, and modified the contractile response of mesenteric artery rings to phenylephrine, the direction and magnitude of these effects depending on the dose and experimental conditions (normal or endotoxemic animals). Our studies showed that FC could induce biological effects and modify vascular reactivity, in healthy volunteers and in normal and endotoxemic rats, in a similar way than HC. These effects depend on the dose and experimental conditions studied. Defining the optimal dose to be used in septic shock patients seems necessary before re-assessing its efficacy
Dias, Liliane Dane. "Avaliação da eficiência de vacinas contra Clostridium septicum". Universidade Federal de Minas Gerais, 2003. http://hdl.handle.net/1843/BUOS-8C4FGT.
Testo completoForam avaliadas quanto à eficiência 12 vacinas comerciais contra clostridioses, que continham toxóides e/ou bacterinas de Clostridium septicum, pelo teste de soroneutralização em camundongos a partir de soros de coelhos e bovinos vacinados e pelo teste de desafio direto em cobaias. As vacinas codificadas como T1, T 10 e T11 apresentaram, em coelhos, títulos de antitoxina alfa superiores ao nível mínimo de teste de 2,5 Ul/mL recomendado pelo controle deste produto e as vacinas T2 e T4 títulos de 2.0 e 2.5 Ul/mL. Resultados semelhantes foram obtidos nos soros de bovinos em relação às vacinas T1, T2, T4 e T10. A vacina T11 não foi testada em bovinos. Pelo método do desafio direto em cobaias, nenhuma vacina atendeu aos requisitos mínimos. As vacinas contra Clostridium septicum, em sua maioria, foram ineficientes em estimular resposta compatível com níveis de teste.
Hautbois, Corinne. "Granulomatose septique chronique mimant une maladie de Crohn". Montpellier 1, 2000. http://www.theses.fr/2000MON11003.
Testo completoBeber, Alexandre. "In vitro study of membrane remodeling and curvature sensing at the micrometric scale by budding yeast septins". Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS375.
Testo completoSeptins constitute a novel class of cytoskeletal proteins. Budding yeast septins self-assemble into non-polar filaments bound to the inner plasma membrane through specific interactions with L- α-phosphatidylinositol-4,5- bisphosphate (PI(4,5)P2). Septins localize at constriction sites during cytokinesis and impact membrane remodeling processes. We have analyzed a range of in vitro biomimetic tools to examine how yeast septins behave on curved and deformable membranes. In vitro assays using Giant Unilamellar Vesicles (GUVs) are relevant tools to reveal insights in proteins-lipids interactions, membrane mechanics and curvature sensitivity. GUVs doped with PI(4,5)P2 are challenging to prepare. We first optimized the incorporation of PI(4,5)P2 lipids into GUVs by probing the proteins-PI(4,5)P2 GUVs interactions. We show that the interaction between budding yeast septins and PI(4,5)P2 is more specific than using usual reporters (phospholipase C1). We have shown that electro-formation on platinum wires is the most appropriate method to achieve an optimal septin-lipid interaction. Besides, we have shown that PI(4,5)P2 GUVs have to be used within a few hours after their preparation. Indeed, over time, PI(4,5)P2 is expelled from the GUV membrane and the PI(4,5)P2 concentration in the bilayer decreases. Next, we analyzed how septins can control the mechanical properties of membranes and analyzed how membrane deformations could be induced by a specific curvature sensitivity of septins. Indeed, we have shown that septins reshape the membranes of Giant Unilamellar Vesicles with the formation of periodic spikes. We have shown that membrane deformations are associated to septin filament curvature arrangement preferences. When binding to bilayers supported on custom-designed periodic wavy patterns displaying positive and negative micrometric radii of curvatures, septin filaments remain straight and perpendicular to the curvature of the convex parts, while bending negatively to follow concave geometries. Based on these results, we propose a theoretical model that quantitatively describes the deformations and micrometric curvature sensitivity observed in vitro. The model captures the reorganizations of septin filaments throughout cytokinesis in vivo, providing mechanistic insights into cell division
Bruelle, Pascal. "Hémofiltration veino-veineuse séquentielle à haut débit et choc septique : étude de la tolérance hémodynamique induite par la première séance d'hémofiltration chez des malades en état de choc septique". Montpellier 1, 1990. http://www.theses.fr/1990MON11224.
Testo completoFIS, ISABELLE. "Arthrites septiques : etude retrospective ; 188 cas hospitalises de 1979 a 1988 dans le service de rhumatologie de clermont-ferrand". Clermont-Ferrand 1, 1989. http://www.theses.fr/1989CLF13821.
Testo completoPreiser, Jean-Charles. "Contribution à l'étude des altérations cardiovasculaires du choc septique". Doctoral thesis, Universite Libre de Bruxelles, 1996. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/212232.
Testo completoStiel, Laure. "L’activation des polynucléaires neutrophiles au cours du choc septique". Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAJ069.
Testo completoThis PhD thesis focused on the activation of polymorphonuclear granulocytes (PMNs) during septic shock. After an introduction including an overview on pathophysiology of septic shock, disseminated intravascular coagulation (DIC) and PMNs, original experimental and clinical data are reported. In a prospective study, we enrolled 100 patients and showed that neutrophils’ activation measured by neutrophil fluorescence using flow cytometry could represent an original biomarker of septic shock-induced DIC. Furthermore, we highlighted a mechanism of neutrophil’s activation: NETosis, through assessment of indirect serum’s markers associated specifically to DIC during septic shock. In order to confirm the relevance of this result, we reported a direct visualization of circulating NETs in blood of DIC-patients using immunofluorescence. Finally, we performed a proteomic study and identified some proteins involved in neutrophils’ activation during septic shock-induced DIC. Thus, PMN could represent an important actor of immunothrombosis’ deregulation during DIC, and could be considered as a potential therapeutic target
Galbois, Arnaud. "Etude du pronostic des malades cirrhotiques en choc septique". Paris 6, 2013. http://www.theses.fr/2013PA066328.
Testo completoIn this manuscript, we reassessed the actual outcome of cirrhotic patients admitted to intensive care units, in particular in those with septic shock. We found that this outcome dramatically improved, including for patients with septic shock, placed under mechanical ventilation or receiving renal replacement therapy. We identified that the organ failures scores better predict the outcome than the liver-specific scores. We performed a review of literature; the most recent studies are in accordance with our results in term of mortality rates and in term of accuracy of the different scores to predict the outcome in these particular patients. We also identified that, among the different organ failures, the coagulation failure, defined by the platelet level according to the SOFA score, was not associated with a worse outcome. Moreover, the organ failures better predict the outcome when assessed 3 days after the admission to the intensive care unit. Regarding cirrhotic patients with septic shock, we demonstrated that mottling and the decrease in StO2 in the knee area appear later in patients with cirrhosis than in patients without. Those signs assessed 6 hours after the admission, predict the mortality at day 14 with an excellent specificity, but a relatively low sensibility
Pfanzelter, Julia. "The role of septins during vaccinia virus spread". Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10042029/.
Testo completoLancel, Steve. "Dysfonction myocardique septique : un nouveau rôle pour les effecteurs de l'apoptose". Lille 2, 2005. http://www.theses.fr/2005LIL2S017.
Testo completoDespite numerous advances in medical treatment, infectious shock also called septic shock is associated with an extremely high mortality rate. Sepsis-induced myocardial dysfunction is greatly associated with a fatal outcome. Most of the sepsis-induced myocardial dysfunction has been attributed to the deleterious effects of mediators released during the inflammatory response. Apoptosis processes are also involved in the pathogenesis of sepsis-induced myocardial dysfunction. The first aim of our study was to characterize both an in vivo and an in vivo model of sepsis-induced myocardial dysfunction. First, in the in vivo model, we checked that NFkB-dependent pathways, which represent a hallmark of the inflammatory response, were activated. In the in vitro model, the use of sphingosine, a pro-apoptotic molecule, unravelled a possible link between apoptotic pathway activation and cardiac cell contractile dysfunction. These results required further studies in order to explain how apoptotic processes may lead to myocardial dysfunction. We showed that mitochondria and apoptotic proteases are rapidly activated. Interestingly, although effector caspases are not associated with terminal nuclear degradation and cell death these proteolytical enzymes lead to sarcomeric destruction and calcium homeostasis alterations. Such modifications are responsible for contractile dysfunction Thus, these new fundamental mechanisms could be useful to develop new therapeutic strategies in the human septic shock
Popa, Septimiu [Verfasser]. "Thermisch gespritzte Keramikschichten als Reiboberflächen von Leichtbau-Bremsscheiben / Septimiu Popa". Düren : Shaker, 2021. http://d-nb.info/1227824335/34.
Testo completoAlessandro, Fernando. "Estudos estruturais e bioquímicos das septinas 7 e 9 humanas". Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-14062010-163659/.
Testo completoProteins belonging to the septin family were originally discovered in 1971 through genetic studies of mutant cells. These proteins found in fungi and animals, but not in plants present, as their main characteristics, a conserved guanine nucleotide-binding domain (GTP) and they also form homo and hetero-oligomeric filaments that are highly organized structures. Phylogenetic and molecular studies in humans have identified 14 septins which are divided into 4 subfamilies (groups I, II, III and IV). These molecules associate with cell membranes, actin, cytoskeleton microtubules and they are related to a number of processes that take place in the cell cortex and that require spatial organization, such as cytokinesis, cell cycle, diffusion barrier formation and spindle alignment. Alterations in the expression of septins are associated with several types of tumors and with Parkinsons and Alzheimers diseases. In this work, with the goal of obtaining structural and biochemical information of human septins 7 and 9, the recombinants SEPT 7, SEPT 7G and SEPT 9G were expressed in E. coli. Analyses both in SDS-Page electroforesis and in native gel suggest that these proteins were purified successfully for they are soluble and homogeneous. GTpase activity has been verified in all of these recombinants, which shows that these proteins are present in native form and that additional molecules are not needed for this activity. It was possible to determine through different techniques such as molecular exclusion chromatography and SAXS that all the molecules in solution are grouped as dimeric form. Circular dichroism and fluorescence spectroscopic studies have determined both that such recombinants are formed by means of a mixture of &alfa; and β secondary structures and that the C and N-terminals increase the stability of proteins. Protein stability studies under different pH and temperature conditions show that the raise of the latter produces a greater molecular aggregation. Measurements of fluorescence emissions have indicated that the SEPT 7, SEPT 7G and SEPT 9G form structures of amyloid-like filaments found in many septins. Crystal structures of SEPT 7G have been obtained and, by means of the X-ray technique, a 3-D model of the protein has been determined with a resolution of 3.4o. It has been possible to predict, with molecular modeling studies, regions formed by loops that showed low electronic density in the GTPase crystallographic model. Therefore, it has been possible to add more structural information to this domain and to form the complete polypeptide without cuts.
PLOUVIER, FABIENNE. "Fonction ventriculaire droite et catecholamines au cours du choc septique". Lille 2, 1990. http://www.theses.fr/1990LIL2M260.
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