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The Global ETD Search service is a free service for researchers
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Showing 41 to 48 of 48 (0.018 seconds)| 41 |
Régulation de l'apoptose des lymphocytes T par les protéines de la famille TSC-22DPepin, Aurelie 12 July 2011 (has links) (PDF)
Les protéines GILZ (Glucocorticoid-Induced Leucine Zipper) et TSC-22 (Transforming growth factor-beta Stimulated Clone-22) appartiennent à la famille de protéines TSC-22D (TSC-22 Domain). GILZ a été décrit précédemment comme étant induit au cours de la déprivation en interleukine-2 (IL-2) des lymphocytes de la lignée cellulaire CTLL-2, permettant ainsi de retarder leur apoptose. Le but de notre travail était de déterminer les rôles respectifs de GILZ et TSC-22 au cours de l'apoptose des cellules CTLL-2.Nos résultats ont permis de montrer que TSC-22 augmentait l'apoptose induite par la déprivation en IL-2 des cellules CTLL-2. Nous avons mis en évidence une augmentation de l'activation des caspases ainsi qu'une régulation positive de l'expression de BIM. Nous avons en outre montré que l'expression de GILZ, protéine anti-apoptotique, induite lors de la déprivation en IL-2, était régulée négativement en présence de TSC-22. Enfin, nous avons montré que l'expression de l'ARNm de gilz était régulée négativement par TSC-22, mais que la stabilité de son ARNm n'était pas modifiée.Notre travail a donc permis de montrer que TSC-22 accélère l'entrée en apoptose des lymphocytes T en régulant négativement l'expression de la protéine anti-apoptotique GILZ.
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Régulation transcriptionnelle du facteur de transcription spécifique des bâtonnets, NrlKautzmann, Marie Audrey 12 June 2012 (has links) (PDF)
La leucine zipper de la rétine neurale (Nrl) joue un rôle central dans le développement et l'homéostasie des bâtonnets en activant I'expression de gènes tels que le photopigment Rhodopsine. Nrl est aussi associé à la Rétinite Pigmentaire, faisant ainsi de ce gène un modèle intéressant pour la compréhension des programmes contrôlant le développement et I'homéostasie des photorécepteurs.Ce travail de thèse vise à caractériser les mécanismes régulateurs de I'expression de Nr/ au cours du développement rétinien. L'électroporation in vivo de vecteurs rapporteurs dans des rétines de souris en développement, a révélé des séquences minimales de promoteur Nr/ nécessaires à une expression spécifique dans les photorécepteurs. Nous avons identifié RORI3 comme facteur requis pour cette expression, et montré que les facteurs OTX2, CRX et CREB s'accrochent aussi directement à des régions régulatrices particulières du promoteur. Nous avons construit un virus adéno-associé (AAV) contenant un promoteur minimal Nrl de 0.3 kb, et montré qu'il est adapté à la délivrance de gène spécifiquement dans les photorécepteurs.Nous avons montré que NRL, CRX et NR2E3, les régulateurs principaux de la Rhodopsine, ont une expression rythmique au cours de 24 h, et que l'expression cyclique de Nr/ peut être due à l'activation par RORp, un composant l'horloge circadienne. Enfin, nous avons identifié un nouveau facteur de transcription, NonO, au niveau de la région du promoteur proximal de la Rhodopsine, qui en combinaison avec NRL et CRX, active le promoteur de la Rhodopsine. L'invalidation de NonO au cours du développement rétinien a prouvé son implication pour le développement et I'homéostasie des bâtonnets.
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Characterization of the BACH1 Helicase in the DNA Damage Response Pathway: a DissertationLitman, Rachel 15 February 2007 (has links)
DNA damage response pathways are a complicated network of proteins that function to remove and/or reverse DNA damage. Following genetic insult, a signal cascade is generated, which alerts the cell to the presence of damaged DNA. Once recognized, the damage is either removed or the damaged region is excised, and the original genetic sequence is restored. However, when these pathways are defective the cell is unable to effectively mediate the DNA damage response and the damage persists unrepaired. Thus, the proteins that maintain the DNA damage response pathway are critical in preserving genomic stability.
One essential DNA repair protein is the Breast Cancer Associated gene, BRCA1. BRCA1 is essential for mediating the DNA damage response, facilitating DNA damage repair, and activating key cell cycle checkpoints. Moreover, mutations in BRCA1 lead to a higher incidence of breast and ovarian cancer, highlighting the importance of BRCA1 as a tumor suppressor. In an effort to better understand how BRCA1 carried out these functions, researchers sought to identify additional BRCA1 interacting proteins. This led to the identification of several proteins including the BRCA1 Associated C-terminal Helicase, BACH1. Due to the direct interaction of BACH1 with a region of BRCA1 essential for DNA repair and tumor suppression, it was speculated that BACH1 may help support these BRCA1 function(s). In fact, initial genetic screenings confirmed that mutations in BACH1 correlated not only with hereditary breast cancer, but also with defects in DNA damage repair processes.
The initial correlation between BACH1 and cancer predisposition was further confirmed when mutations in BACH1 were identified in the cancer syndrome Fanconi anemia (FA) (complementation group FA-J), thus giving BACH1 its new name FANCJ. These findings supported a previously established link between the FA and BRCA pathways and between FA and DNA repair. In particular, we demonstrated that similar to other FA/BRCA proteins, suppression of FANCJ lead to a substantial decrease in homologous recombination and enhanced both the cellular sensitivity to DNA interstrand cross-linking agents and chromosomal instability. What remained unknown was specifically how FANCJ functioned and whether these functions were dependent on its interaction with BRCA1 or other associated partners. In fact, we identified that FANCJ interacted directly with the MMR protein MLH1. Moreover, we found that the FANCJ/BRCA1 interaction was not required to correct the cellular defects in FA-J cells, but rather that the FANCJ/MLH1 interaction was required. Although both the FA/BRCA and MMR pathways undoubtedly mediate the DNA damage response, there was no evidence to suggest that these pathways were linked, until recently. Our findings not only indicate a physical link between these pathways by protein-protein interaction, but also demonstrated a functional link.
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Regulation of BACH1/FANCJ Function in DNA Damage Repair: A DissertationXie, Jenny X. 11 August 2009 (has links)
The DNA damage response (DDR) pathway is a complicated network of interacting proteins that function to sense and remove DNA damage. Upon exposure to DNA damage, a signaling cascade is generated. The damage is either removed, restoring the original genetic sequence, or apoptosis is activated. In the absence of DDR, cells are unable to effectively process DNA damage. Unprocessed DNA damage can lead to chromosomal changes, gene mutations, and malignant transformation. Thus, the proteins involved in DDR are critical for maintaining genomic stability.
One essential DDR protein is the BRCA1 Associated C-terminal Helicase, BACH1. BACH1 was initially identified through its direct association with the BRCT domain of the Breast Cancer Associated Gene, BRCA1. Similar to BRCA1, germline mutations in BACH1were identified in patients with early onset breast cancer. Interestingly, the disease-associated mutations in BACH1 were shown to have altered helicase activity in vitro, providing a direct link between BACH1 helicase activity and disease development. The correlation between BACH1 and cancer predisposition was further confirmed by the identification of BACH1 as the cancer syndrome Fanconi anemia (FA) gene product, FANCJ. Similar to other FA proteins, suppression of FANCJ leads to decreased homologous recombination, enhanced sensitivity to DNA interstrand crosslinking (ICL) agents, and chromosomal instability.
In an effort to further understand the function of FANCJ in DDR, FANCJ was shown to directly associate with the mismatch repair (MMR) protein MLH1. This interaction is facilitated by lysines 141 and 142 within the helicase domain of FANCJ. Importantly, the FANCJ/MLH1 interaction is critical for ICL repair. Furthermore, in an attempt to dissect the binding site of FANCJ on MLH1, we discovered an HNPCC associated MLH1 mutation (L607H) that has intact mismatch repair, but lacks FANCJ interaction. In contrast to the MLH1 interaction, the FANCJ/BRCA1 interaction was not required for correcting the cellular defects in FANCJ null cells. Thus, in an effort to understand the functional significance of the FANCJ/BRCA1 interaction, we discovered that FANCJ promotes Pol η dependent translesion synthesis (TLS) bypass when uncoupled from BRCA1. In this thesis, we provide evidence suggesting that FANCJ and MLH1 are functionally linked and that the interaction of these proteins is critical for repair choice.
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Wafer-level heterogeneous integration of MEMS actuatorsBraun, Stefan January 2010 (has links)
This thesis presents methods for the wafer-level integration of shape memory alloy (SMA) and electrostatic actuators to functionalize MEMS devices. The integration methods are based on heterogeneous integration, which is the integration of different materials and technologies. Background information about the actuators and the integration method is provided. SMA microactuators offer the highest work density of all MEMS actuators, however, they are not yet a standard MEMS material, partially due to the lack of proper wafer-level integration methods. This thesis presents methods for the wafer-level heterogeneous integration of bulk SMA sheets and wires with silicon microstructures. First concepts and experiments are presented for integrating SMA actuators with knife gate microvalves, which are introduced in this thesis. These microvalves feature a gate moving out-of-plane to regulate a gas flow and first measurements indicate outstanding pneumatic performance in relation to the consumed silicon footprint area. This part of the work also includes a novel technique for the footprint and thickness independent selective release of Au-Si eutectically bonded microstructures based on localized electrochemical etching. Electrostatic actuators are presented to functionalize MEMS crossbar switches, which are intended for the automated reconfiguration of copper-wire telecommunication networks and must allow to interconnect a number of input lines to a number of output lines in any combination desired. Following the concepts of heterogeneous integration, the device is divided into two parts which are fabricated separately and then assembled. One part contains an array of double-pole single-throw S-shaped actuator MEMS switches. The other part contains a signal line routing network which is interconnected by the switches after assembly of the two parts. The assembly is based on patterned adhesive wafer bonding and results in wafer-level encapsulation of the switch array. During operation, the switches in these arrays must be individually addressable. Instead of controlling each element with individual control lines, this thesis investigates a row/column addressing scheme to individually pull in or pull out single electrostatic actuators in the array with maximum operational reliability, determined by the statistical parameters of the pull-in and pull-out characteristics of the actuators. / QC20100729
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Lhx2 differentially regulates Sox9, Tcf4 and Lgr5 in hair follicle stem cells to promote epidermal regeneration after injuryMardaryev, Andrei N., Meier, N., Poterlowicz, Krzysztof, Sharov, A.A., Sharova, T.Y., Ahmed, Mohammed I., Rapisarda, Valentina, Lewis, Christopher J., Fessing, Michael Y., Ruenger, T.M., Bhawan, J., Werner, S., Paus, R., Botchkarev, Vladimir A. January 2011 (has links)
No / The Lhx2 transcription factor plays essential roles in morphogenesis and patterning of ectodermal derivatives as well as in controlling stem cell activity. Here, we show that during murine skin morphogenesis, Lhx2 is expressed in the hair follicle (HF) buds, whereas in postnatal telogen HFs Lhx2(+) cells reside in the stem cell-enriched epithelial compartments (bulge, secondary hair germ) and co-express selected stem cell markers (Sox9, Tcf4 and Lgr5). Remarkably, Lhx2(+) cells represent the vast majority of cells in the bulge and secondary hair germ that proliferate in response to skin injury. This is functionally important, as wound re-epithelization is significantly retarded in heterozygous Lhx2 knockout (+/-) mice, whereas anagen onset in the HFs located closely to the wound is accelerated compared with wild-type mice. Cell proliferation in the bulge and the number of Sox9(+) and Tcf4(+) cells in the HFs closely adjacent to the wound in Lhx2(+/-) mice are decreased in comparison with wild-type controls, whereas expression of Lgr5 and cell proliferation in the secondary hair germ are increased. Furthermore, acceleration of wound-induced anagen development in Lhx2(+/-) mice is inhibited by administration of Lgr5 siRNA. Finally, Chip-on-chip/ChIP-qPCR and reporter assay analyses identified Sox9, Tcf4 and Lgr5 as direct Lhx2 targets in keratinocytes. These data strongly suggest that Lhx2 positively regulates Sox9 and Tcf4 in the bulge cells, and promotes wound re-epithelization, whereas it simultaneously negatively regulates Lgr5 in the secondary hair germ and inhibits HF cycling. Thus, Lhx2 operates as an important regulator of epithelial stem cell activity in the skin response to injury.
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The Rtg1 and Rtg3 proteins are novel transcription factors regulated by the yeast hog1 mapk upon osmotic stressNoriega Esteban, Núria 27 February 2009 (has links)
La adaptación de la levadura Saccharomyces cerevisiae a condiciones de alta osmolaridad está mediada por la vía de HOG ((high-osmolarity glycerol). La activación de esta vía induce una serie de respuestas que van a permitir la supervivencia celular en respuesta a estrés. La regulación génica constituye una respuesta clave para dicha supervivencia. Se han descrito cinco factores de transcripción regulados por Hog1 en respuesta a estrés osmótico. Sin embargo, éstos no pueden explicar la totalidad de los genes regulados por la MAPK Hog1. En el presente trabajo describimos cómo el complejo transcripcional formado por las proteínas Rtg1 y Rtg3 regula, a través de la quinasa Hog1, la expresión de un conjunto específico de genes. Hog1 fosforila Rtg1 y Rtg3, aunque ninguna de estas fosforilaciones son esenciales para regulación transcripcional en respuesta a estrés. Este trabajo también muestra cómo la deleción de proteínas RTG provoca osmosensibilidad celular, lo que indica que la integridad de la vía de RTG es esencial para la supervivencia celular frente a un estrés osmótico. / In Saccharomyces cerevisiae the adaptation to high osmolarity is mediated by the HOG (high-osmolarity glycerol) pathway, which elicits different cellular responses required for cell survival upon osmostress. Regulation of gene expression is a major adaptative response required for cell survival in response to osmotic stress. At least five transcription factors have been reported to be controlled by the Hog1 MAPK. However, they cannot account for the regulation of all of the genes under the control of the Hog1 MAPK. Here we show that the Rtg1/3 transcriptional complex regulates the expression of specific genes upon osmostress in a Hog1-dependent manner. Hog1 phosphorylates both Rtg1 and Rtg3 proteins. However, none of these phosphorylations are essential for the transcriptional regulation upon osmostress. Here we also show that the deletion of RTG proteins leads to osmosensitivity at high osmolarity, suggesting that the RTG-pathway integrity is essential for cell survival upon stress.
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SCF cdc4 regulates msn2 and msn4 dependent gene expression to counteract hog1 induced lethalityVendrell Arasa, Alexandre 16 January 2009 (has links)
L'activació sostinguda de Hog1 porta a una inhibició del creixement cel·lular. En aquest treball, hem observat que el fenotip de letalitat causat per l'activació sostinguda de Hog1 és parcialment inhibida per la mutació del complexe SCFCDC4. La inhibició de la mort causada per l'activació sostinguda de Hog1 depèn de la via d'extensió de la vida. Quan Hog1 s'activa de manera sostinguda, la mutació al complexe SCFCDC4 fa que augmenti l'expressió gènica depenent de Msn2 i Msn4 que condueix a una sobreexpressió del gen PNC1 i a una hiperactivació de la deacetilassa Sir2. La hiperactivació de Sir2 és capaç d'inhibir la mort causada per l'activació sostinguda de Hog1. També hem observat que la mort cel·lular causada per l'activació sostinguda de Hog1 és deguda a una inducció d'apoptosi. L'apoptosi induïda per Hog1 és inhibida per la mutació al complexe SCFCDC4. Per tant, la via d'extensió de la vida és capaç de prevenir l'apoptosi a través d'un mecanisme desconegut. / Sustained Hog1 activation leads to an inhibition of cell growth. In this work, we have observed that the lethal phenotype caused by sustained Hog1 activation is prevented by SCFCDC4 mutants. The prevention of Hog1-induced cell death by SCFCDC4 mutation depends on the lifespan extension pathway. Upon sustained Hog1 activation, SCFCDC4 mutation increases Msn2 and Msn4 dependent gene expression that leads to a PNC1 overexpression and a Sir2 deacetylase hyperactivation. Then, hyperactivation of Sir2 is able to prevent cell death caused by sustained Hog1 activation. We have also observed that cell death upon sustained Hog1 activation is due to an induction of apoptosis. The apoptosis induced by Hog1 is decreased by SCFCDC4 mutation. Therefore, lifespan extension pathway is able to prevent apoptosis by an unknown mechanism.
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