To see the other types of publications on this topic, follow the link: Kinases mark.
Dissertations / Theses on the topic 'Kinases mark'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Kinases mark.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
La, Carbona Stéphanie. "Étude fonctionnelle de la protéine Kin1, une kinase de la famille KIN-1/PAR-1/MARK, chez "Schizosaccharomyces pombe"." Rennes 1, 2005. http://www.theses.fr/2005REN1S110.
Full textAbstract:
La protéine Kin1 de "Schizosaccharomyces pombe" appartient à la famille de kinases KIN-1/PAR-1/MARK. Nous avons montré que Kin1 est impliquée dans l'organisation de la nouvelle extrémité après la cytodiérèse, la séparation cellulaire, la polarisation complète du cytosquelette d'actine en interphase et le positionnement du site de division cellulaire. La protéine GFP-Kin1 surexprimée se localise au cortex cellulaire sur un ou deux pôles. Pour cela, le motif KA1 en C-terminal, la région médiane et l'activité kinase sont requis. La protéine Kin1-myc exprimée à un niveau endogène se localise aux pôles mais aussi au milieu de cellules en mitose. Cela dépend de la formation d'un anneau d'actine compact. L'homologue structural humain de Kin1 C-TAK1, se localise sur le cortex des cellules de S. Pombe mais pas de façon polarisée. Enfin, nous avons montré un rôle coopératif entre Kin1 et la kinase Pom1 (famille DYRK) dans la formation de l'anneau d'actine en mitose et dans la division cellulaire.
2
Kragelj, Jaka. "Structure and dynamics of intrinsically disordered regions of MAPK signalling proteins." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENV060/document.
Full textAbstract:
Les voies de transduction du signal cellulaire permettent aux cellules de répondre aux signaux de l'environnement et de les traiter. Les voies de transduction de kinases MAP (MAPK) sont bien conservées dans toutes les cellules eucaryotes et sont impliquées dans la régulation de nombreux processus cellulaires importants. Les régions intrinsèquement désordonnées (RID), présentes dans de nombreuses MAPK, n'étaient pas encore structurellement caractérisées. Les RID de MAPK sont particulièrement importantes car elles contiennent des motifs de liaison qui contrôlent les interactions entre les protéines MAPK elles-mêmes et aussi entre les protéines MAPK et d'autres protéines contenant les mêmes motifs. La résonance magnétique nucléaire (RMN) en combinaison avec d'autres techniques biophysiques a été utilisée pour étudier les RID de kinase des voies de transduction du signal MAPK. La spectroscopie RMN est bien adaptée pour l'étude des protéines intrinsèquement désordonnées à l'échelle atomique. Les déplacements chimiques et couplages dipolaires résiduels peuvent être utilisés conjointement avec des méthodes de sélection d'ensemble pour étudier la structure résiduelle dans les RID. La relaxation de spin nucléaire nous renseigne sur les mouvements rapides. Des titrations par RMN et des techniques de spectroscopie d'échange peuvent être utilisées pour surveiller la cinétique d'interactions protéine-protéine. Cette étude contribuera à la compréhension du rôle des RID dans les voies de transduction du signal cellulaire<br>Protein signal transduction pathways allow cells respond to and process signals from the environment. A group of such pathways, called mitogen-activated protein kinase (MAPK) signal transduction pathways, is well conserved in all eukaryotic cells and is involved in regulating many important cell processes. Long intrinsically disordered region (IDRs), present in many MAPKs, have remained structurally uncharacterised. The IDRs of MAPKs are especially important as they contain docking-site motifs which control the interactions between MAPK proteins themselves and also between MAPKs and other interacting proteins containing the same motifs. Nuclear magnetic resonance (NMR) spectroscopy in combination with other biophysical techniques was used to study IDRs of MAPKs. NMR spectroscopy is well suited for studying intrinsically disordered proteins (IDPs) at atomic-level resolution. NMR observables, such as for example chemical shifts and residual dipolar couplings, can be used together with ensemble selection methods to study residual structure in IDRs. Nuclear spin relaxation informs us about fast pico-nanosecond motions. NMR titrations and exchange spectroscopy techniques can be used to monitor kinetics of protein-protein interactions. The mechanistic insight into function of IDRs and motifs will contribute to understanding of how signal transduction pathways work
3
Aoidi, Rifdat. "Étude du rôle de la voie ERK/MAPK dans le développement embryonnaire chez la souris." Doctoral thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/27476.
Full textAbstract:
Tableau d'honneur de la Faculté des études supérieures et postdoctorales, 2016-2017<br>Les mammifères possèdent deux MAP kinases kinases (MEK1 et MEK2), impliquées dans l’activation de la voie ERK/MAPK essentielle pour la différenciation, la prolifération et la survie cellulaire. Le premier objectif de cette thèse était de déterminer si les fonctions des kinases MEK1 et MEK2 sont redondantes durant le développement embryonnaire. Les souris Mek1-/- meurent à mi-gestation d’une malformation du placenta. Les souris Mek2-/- ne présentent aucun phénotype majeur, suggérant que ces deux protéines ont des rôles différents. Cependant, la plupart des mutants Mek1+/-Mek2+/- meurent pendant la gestation d’un sous-développement du placenta, indiquant que Mek1 et Mek2 ont chacun un rôle dans le développement des tissus extraembryonnaires. À ce jour aucune évidence claire ne permet de statuer sur la redondance fonctionnelle de MEK1 et MEK2. Afin de vérifier la spécificité fonctionnelle de Mek1 et Mek2, nous avons généré au laboratoire un allèle « knockin », exprimant l’ADNc de Mek2 sous contrôle du locus Mek1 (Mek12). L’analyse de ces souris a révélé la redondance fonctionnelle entre MEK1 et MEK2. L’analyse de combinaisons alléliques de Mek a démontré qu’une expression minimale de protéines MEK est cruciale pour le développement embryonnaire et la survie. Le second objectif de cette thèse était de caractériser les mutants Mp1. Les protéines d’échafaudage permettent de moduler l’activité de la voie ERK/MAPK et facilitent la transmission rapide du signal. Parmi les protéines d’échafaudage connues, seule MP1 (Mek Partner 1) a été identifiée comme étant un partenaire spécifique de MEK1 et ERK1. Cette spécificité suggère que MP1 pourrait contribuer à la différence d’activation de MEK1 et MEK2 en spécifiant le signal qui passe par Mek1. Afin d’étudier le rôle de Mp1 au cours du développement chez la souris, nous avons généré des souris Mp1-/-. L’analyse de ces mutants indique que le gène Mp1 est essentiel pour la survie et que sa fonction est nécessaire suite à la post-implantation. La dérégulation de la voie ERK/MAPK dans le développement chez l’homme a aussi des conséquences phénotypiques. Au cours des dernières années, une classe de syndromes a été caractérisée : Les « Rasophaties ». Ces syndromes partagent des caractéristiques communes qui sont, une mutation dans des gènes de la voie ERK/MAPK, une dysmorphologie cranio-faciale, des malformations cardiaques et cutanées ainsi qu’un retard mental. Parmi les mutations de la voie ERK/MAPK qui ont été identifiées, une mutation ponctuelle dans le gène Mek1 (Mek1Y130C) cause le syndrome Cardio-Facio-Cutané (CFC). Le dernier objectif de cette thèse était de générer un modèle animal pour le CFC portant la mutation Mek1Y130C. Les souris portant l’allèle Mek1Y130C présentent les phénotypes associés au CFC (i.e sténose pulmonaire, dysmorphologie cranio-faciale et défauts neurologiques).<br>Mammals possess two MAP kinase kinase (MEK1 and MEK2), involved in ERK/MAPK pathway. This pathway is essential for proliferation, differentiation and cell survival. The first objective of my thesis was to determinate if MEK1 and MEK2 kinases are redundant during embryonic development. Mek1-/- mice die at embryonic day E10.5 due to placental defects, whereas Mek2-/- mice survive with a normal lifespan suggesting that MEK1 possesses functions not shared by MEK2. However, most Mek1+/-Mek2+/- embryos also die from placental defects, indicating that both Mek genes contribute to placental development. To date, no clear evidence on MEK1 and MEK2 redundancy has been provided. To assess the functional specificity of the Mek1 and Mek2 genes, we produced a Mek1-knockin allele in which the Mek2 coding sequences were placed under the control of Mek1 regulatory sequences. Analyzing these mice allowed us to demonstrate that MEK1 and MEK2 can substitute for each other and that a minimal amount of MEK is critical for placenta development and embryo survival. The second objective of my thesis was to characterize Mp1 mutants. Scaffold proteins modulate MAPK pathway by providing spatial and temporal specificity. Among known ERK/MAPK scaffold proteins, only MP1 (Mek Partner 1) is specific to MEK1 and ERK1, raising the question of the specificity of MP1 in the regulation of ERK/MAPK pathway via MEK1. In order to investigate Mp1 function in vivo, we generated Mp1 knock-out mice. Analyzing these mice enable us to suggest that Mp1 is required for embryonic development and is essential during post-implantation. Deregulation of Ras/MAPK pathway also causes developmental phenotypes in human. During the last decade, a new class of syndromes, which share common phenotypes such as mutations in Ras/MAPK pathway, cranio-facial dysmorphology, cardiac and cutaneous malformations and neurological delay has been described and named Rasophaties. Among the DNA mutations found in rasopathies, the Mek1 mutation, Mek1Y130C, causes cardio-facio-cutaneous syndrome (CFC). The last objective of my thesis was to generate a mouse model of CFC, with the Mek1Y130C mutation. I found that mice carrying the Mek1Y130C mutation partially recapitulate CFC syndrome (i.e pulmonary stenosis, crani-facial dysmophia and neurological defects).
4
Chen, Xi. "The role of PI3K and ERK/MAPK signal transduction cascades in long-term memory formation /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/6248.
Full text
5
Li, Xiaoyu. "Regulation of the kinase MARK from Rattus norvegicus (Berkenhout, 1769) activation by MARKK and inhibition by PAK5 /." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=980208378.
Full text
6
Timm, Thomas. "Reinigung und Charakterisierung einer MARK-aktivierenden Kinase." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=969477872.
Full text
7
Pang, Wei Wei. "The role of mitochondria in regulating MAPK signalling pathways during oxidative stress." University of Western Australia. School of Biomedical, Biomolecular and Chemical Sciences, 2006. http://theses.library.uwa.edu.au/adt-WU2007.0026.
Full textAbstract:
[Truncated abstract] Reactive oxygen species (ROS) have been implicated to play a major role in many pathological conditions including heart attack and stroke. Their ability to modulate the extracellular signal-regulated protein kinase (ERK) and c-Jun Nterminal kinase (JNK) signalling pathways, thereby influencing cellular response has been well-documented. Recent studies implicate a central role for mitochondria in ERK and JNK activation by ROS although the mechanisms remained unresolved. Using Jurkat T-lymphocyte as a cell model, this study demonstrated increased mitochondrial ROS production as a result of decreased mitochondrial complex activities mediated by hydrogen peroxide treatment. This is the first study to show that mitochondria are not essential for activating ERKs, however damaged mitochondria producing ROS can be expected to cause sustained ERK activation . . . This study revealed that JNK and its upstream kinases MKK4, MKK7 and ASK1 are associated with the mitochondria. Furthermore, findings from this study imply that JNK resides in the mitochondrial matrix. This study is the first to demonstrate that mitochondrial JNK can be activated in a cell-free environment by signals originating from the mitochondria. Experimental work using isolated mitochondria demonstrated that mitochondrial JNK can be activated by ROS generated from the mitochondria themselves. Flavin-containing proteins appear to be the main sources of mitochondrial-ROS which signal through redoxsensitive proteins to activate mitochondrial JNK.
8
Mahan, Kristin Lynn. "Circadian oscillation of MAPK activity and cAMP in the hippocampus : implications for memory persistence /." Thesis, Connect to this title online; UW restricted, 2008. http://hdl.handle.net/1773/6304.
Full text
9
Borysov, Sergiy I. "B-Raf is an essential component of the mitotic machinery critical for activation of MAPK signaling during mitosis in Xenopus egg extracts." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001759.
Full text
10
McCarthy, Pierre C. "Regulation of MyD88 signalling by MAPK activated kinases." Thesis, University of Dundee, 2015. https://discovery.dundee.ac.uk/en/studentTheses/ba214a96-e0d3-460e-8230-5931096601a2.
Full text
11
Rice, Kevin M. "Effects of aging on pressure-induced MAPK activation in the rat aorta." Huntington, WV : [Marshall University Libraries], 2005. http://www.marshall.edu/etd/descript.asp?ref=526.
Full text
12
Lachance, Gabriel. "Implication de la MAPK kinase kinase DLK dans la différenciation des kératinocytes." Mémoire, Université de Sherbrooke, 2009. http://savoirs.usherbrooke.ca/handle/11143/4823.
Full textAbstract:
Ce projet de maîtrise s'inscrit dans un effort de recherche visant à caractériser le rôle de la protéine dual leucine zipper-bearing kinase (DLK) dans la peau. Plusieurs données ont été générées par les travaux combinés de notre laboratoire avec le laboratoire d'organogénèse expérimentale (LOEX). Lorsque surexprimée dans des cellules en culture, DLK induit la différenciation spontanée des cellules de l'épiderme, les kératinocytes. Dans ces conditions, DLK active une protéine centrale dans la différenciation des kératinocytes; la transglutaminase de type 1 (TGM1). Récemment, l'étude de l'épiderme des souris knockouts pour le gène DLK a montré l'importance de cette kinase dans la formation de la couche cornée de la peau murine. Nous avons utilisé l'approche de l'ARN à interférence afin d'étudier spécifiquement la fonction de DLK dans la différenciation des kératinocytes normaux en culture. L'approche développée sur ce modèle a été transposée sur un modèle de peaux reconstruites in vitro . La mise au point de la technique des ARN interférents ciblant l'ARNm de DLK dans les kératinocytes a été faite à partir d'une lignée de carcinome spinocellulaire cutané. La diminution de l'expression de DLK par des ARN interférents dans ce modèle induit la fragmentation de l'ADN et l'arrêt du cycle cellulaire. L'apoptose est observée par le clivage du substrat des caspases, la protéine poly-ADP-ribose polymerase (PARP), spécifiquement lorsque DLK est déplétée dans les cellules cancéreuses. La mort cellulaire est corrélée avec la diminution des protéines Hsp70 et RelA, deux facteurs reconnus pour leur rôle positif sur la survie dans les kératinocytes. La surexpression de deux mutants sans activité kinase de DLK a corroboré les résultats obtenus avec le knockdown de DLK et suggère que l'activité de DLK protège les cellules de l'apoptose. Dans ces kératinocytes transformés, DLK a un rôle pro-survie qui n'est pas observé dans des kératinocytes normaux ou dans des fibroblastes normaux provenant du derme. La diminution de l'expression de DLK par l'ARN à interférence dans les kératinocytes normaux humains (NHK) a confirmé son rôle important dans la différenciation. Les NHK déplétés de DLK on une morphologie ressemblant aux kératinocytes non-différenciés. Les NHK qui expriment un shRNA ciblant la forme humaine de DLK, contrairement aux NHK infectées par le vecteur vide ou un shRNA contre la forme murine de DLK, ont très peu de jonctions adhérentes de type desmosome. Cela se traduit par un détachement plus rapide du feuillet de kératinocytes déplétées de DLK lorsque traitées à la trypsine comparativement aux cellules contrôles. La surexpression de DLK induit d'environ 50 % l'activité transglutaminase et à l'inverse, par l'approche de l'ARN à interférence, la déplétion de DLK fait diminuer de 30 % l'activité transglutaminase dans les NHK différenciées. Aussi, la diminution de l'expression de DLK induit la fragmentation de l'ADN des NHK comme le faisait la surexpression de DLK. Au niveau moléculaire, les shRNA ciblant la forme humaine de DLK n'induisent pas le clivage de la PARP, n'affectent pas la protéine pro-survie Akt1 et n'ont pas non plus d'effet significatif sur la phosphorylation des MAPK. Cependant, la sous-unité RelA du facteur de transcription est moins exprimée dans les NHK très différenciés lorsque DLK est déplétée. Globalement, ces résultats suggèrent que DLK est importante pour la différenciation des kératinocytes en favorisant la formation des jonctions adhérentes de type desmosome et en activant la TGM1 qui polymérise certaines protéines desomosomales. Certains résultats indiquent que DLK pourrait aussi réguler une partie de la cascade de NF-?B, une voie de signalisation importante pour la transition entre l'arrêt de croissance et la différenciation dans les kératinocytes. Finalement, l'infection des épidermes reconstruits in vitro avec des shRNA dirigés contre DLK a confirmé l'importance de la protéine dans l'adhérence des cellules de l'épiderme et dans la formation de la couche cornée. En effet dans ce modèle, le knockdown de DLK amène un détachement du feuillet de cellules différenciées de la couche non différenciée. Lorsque les cellules de l'épiderme sont infectées par deux shRNA différents ciblant la forme humaine de DLK, il n'y pas de couche cornée formée, tandis que les cellules infectées par un vecteur vide ou un shRNA ciblant la forme murine de DLK produisent une couche cornée normale. Tous ces résultats supportent le rôle prépondérant de DLK dans l'épiderme.
13
Stead, Rebecca. "Novel roles for the MAPK-interacting serine threonine kinases (Mnks)." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/358973/.
Full textAbstract:
The mitogen activated protein kinase (MAPK)-interacting serine threonine kinases (Mnks) are components of the MEK/ERK and p38MAPK signalling pathways. Research has focused on the role of the Mnks in tumorigenesis, inflammatory signalling cascades and translation of inflammatory cytokines. The physiological roles of these kinases are still not well understood and their functions have yet to be fully elucidated. This prompted the work presented in this study where the roles of the Mnks have been investigated in the phenomenon of rapamycin-induced eIF4E phosphorylation and the role of the Mnks in glucose and lipid metabolism. Increased eIF4E phosphorylation has been correlated with tumorigenesis and a potential anti-cancer therapy, rapamycin, increases eIF4E phosphorylation in cancer cells. The increase in eIF4E phosphorylation is caused by mTORC1 inhibition-dependent increases in Mnk2a activity. The Mnks are enriched in tissues important for glucose metabolism and here a role for the Mnks has been established in insulin signalling. Investigation revealed that the Mnks phosphorylate IRS1 at 5 sites resulting in its stabilization by impairing its proteasome-mediated degradation. The consequence of Mnk1/2 double knockout in mice is glucose intolerance due to reduced IRS1 protein in white adipose tissue. The incidence of type 2 diabetes as a result of obesity is rising rapidly but the mechanisms responsible are as yet not fully understood. Evidence presented in a patent suggests the Mnks may play a role in lipid metabolism and insulin sensitivity. This inspired research presented here showing Mnk2-KO mice exhibit a lack of weight gain when fed high fat diets. Interestingly the Mnk2-KO mice were resistant to severe diet-induced insulin resistance. This appears to be related to a reduction in chronic inflammation usually associated with high fat diet feeding.
14
Cheung, Po Yan. "Interaction between MKK6 and p150 glued dynactin is required for microtubule-mediated p38 MAPK activation /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?BICH%202002%20CHEUNG.
Full textAbstract:
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002.<br>On t.p. glued is superscript. Includes bibliographical references (leaves 84-94). Also available in electronic version. Access restricted to campus users.
15
Krayem, Mohammad. "MAPK pathway as a target for therapy in melanoma." Doctoral thesis, Universite Libre de Bruxelles, 2015. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209067.
Full text
16
Lefort, Natalie. "Rôle de l'AMP-kinase dans l'activation de la p38 MAPK et du transport du glucose induits par la contraction musculaire." Thesis, Université Laval, 2007. http://www.theses.ulaval.ca/2007/24650/24650.pdf.
Full text
17
Cagnol, Sébastien. "Contrôle de la mort cellulaire par la voie des MAPK 1/3 (ERK 2/1)." Nice, 2005. http://www.theses.fr/2005NICE4033.
Full textAbstract:
La mort cellulaire programmée ou apoptose est un mécanisme conservé chez les eucaryotes multicellulaires qui contribue au développement embryonnaire et à l'homéostasie cellulaire des organismes. Dans les cellules vivantes, l'activité des protéases qui exécutent le programme de mort cellulaire, les caspases, est contrôlée par des signaux de survie provenant de l'environnement cellulaire. Les caspases initiatrices de l'apoptose régulée par l'environnement, la caspase 9 et la caspase 8 sont activées respectivement par l'apoptosome et par les récepteurs de mort. Les signaux environnementaux, parmi lesquels le contact avec la matrice extracellulaire ou la présence de facteurs de croissance, activent des voies de signalisation contrôlant la machinerie de mort cellulaire. La voie des MAPK1/3 est une voie de signalisation contrôlée par le proto-oncogènes Ras et comportant les kinases Raf, MEK1/2 et MAPK1/3 (ERK2/1 ou p42/p44). La voie des MAPK1/3, qui est impliquée dans la prolifération et la différentiation cellulaire, joue un rôle essentiel dans la survie cellulaire. L'objectif de cette thèse a été de caractériser les mécanismes moléculaires impliqués dans le contrôle de la mort cellulaire par la voie des MAPK1/3. Ce travail est basé sur l'utilisation d'une forme active et inductible de la kinase Raf-1 (DRaf-1:ER) dont l'activation forte et prolongée correspond à une induction pathologique de la voie des MAPK1/3. Nous avons montré que, selon le type cellulaire, l'activation de DRaf-1:ER favorise la survie ou la mort cellulaire. Dans les cellules fibroblastiques CCL39, l'activation de DRaf-1:ER protège de la mort cellulaire mitochondriale induite par la privation en sérum du milieu de culture. Dans ces conditions, nous avons montré que la stimulation de DRaf-1 :ER bloque l'activation de la caspase-9 mais n'empêche pas la délocalisation du cytochrome c, la multimérisation d'APAF1 ni le recrutement de la procaspase 9 dans l'apoptosome. Ce mécanisme post mitochondrial de protection contre la mort cellulaire dépend de la néo-synthèse des protéines et nécessite une activité continue de la kinase MEK. A l'inverse, dans les cellules HEK 293 issues de rein embryonnaire et présentant des caractéristiques neuronales, nous avons montré que l'activation soutenue de la voie des MAPK1/3 par DRaf1-ER induit une mort cellulaire massive. Celle-ci est caractérisée par l'activation des caspases et la fragmentation de l'ADN. La mort cellulaire est détectée plus de 24 heures après l'activation de DRaf1-ER, elle est maximale à 48h. L'induction de la mort cellulaire ne requière la synthèse protéique que durant la phase précoce d'activation mais nécessite l'activité continue du module MEK/MAPK. La mort cellulaire résulte de l'activation de la caspase 8 et n'implique pas la voie mitochondriale, elle est caractérisée par une vacuolisation importante du cytoplasme des cellules qui l'apparente à une forme particulière d'apoptose. L'inactivation des fonctions du récepteur fas et de son adaptateur FADD indique que le processus d'activation de la caspase 8 est indépendant de la voie des récepteurs de mort. L'ensemble de ces travaux apporte des connaissances nouvelles sur le contrôle de la mort cellulaire par la voie Raf/MAPK1/3. Nous avons montré que la voie de signalisation peut, selon le contexte cellulaire, favoriser la survie cellulaire ou induire la mort. Dans les deux cas, le contrôle de la mort cellulaire dépend à la fois de la synthèse protéique et de mécanismes post-traductionnels. Les mécanismes moléculaires affectés par l'activation prolongée des MAPK1/3 seraient impliqués aussi bien dans la résistance des cellules tumorales aux traitements proapoptotiques que dans le développement des maladies neurodégénératives<br>Programmed cell death or"apoptosis"is an evolutionary conserved feature of multicellular organisms necessary for normal development and tissue homeostasis. In living cells, the activity of the proteases that execute the apoptotic cell death program, the caspases, is controlled by survival signals emanating from the cellular environment. The regulatory components of the caspase cascade, caspase 9 and caspase 8, are activated respectively by the apoptosome and by death receptors. Survival signals elicited by extracellular matrix or growth factors activate signaling pathways that control the cell death machinery. The MAPK1/3 signaling pathway is a kinase cascade comprising Raf, MEK1/2 and MAPK1/3 (ERK1/2 or p42/p44 MapKinases) regulated by the proto-oncogene Ras. The MAPK1/3 pathway is implicated in cell proliferation and differentiation and plays an essential role in cell survival. This thesis objective was to characterize the molecular mechanisms involved in the control of cell death by MAPK1/3 pathway. This study relies on the use of an inducible form of Raf-1 kinase (DRaf-1:ER) those strong and persistent activation leads to a pathological induction of MAPK1/3 activity. We have been able to show that, depending on the cell type, DRaf-1:ER activation favors cell survival or induces cell death. In the lung fibroblastic cell line CCL39, DRaf-1:ER activation prevents cell death induced by serum withdrawal from the tissue culture medium. Under this experimental setting, we could show that DRaf-1:ER stimulation inhibits caspase 9 activation but did not prevent cytochrome c release, APAF1 oligomerization and caspase 9 recruitment in the apoptosome. This novel mechanism of cell death inhibition at a post-mitochondrial level requires ongoing protein synthesis and continuous MEK kinase activity. In HEK293, an embryonic kidney cell line that bares properties of neuronal lineage cells, sustained activation of the MAPK1/3 pathway in response to DRaf-1:ER induces massive cell death. Cell death is characterized by caspases activation and DNA fragmentation. It is a slow process, detectable more than 24 hours after DRaf-1:ER stimulation and maximal at 48 hours. Cell death induction needs protein synthesis only during the early stage of activation but requires a continuous activity of the MEK/MAPK module. Cell death results from caspase 8 activation and does not require the mitochondrial pathway of apoptosis. It is characterized by the formation of vacuoles in the cytoplasm that evoke paraptosis, a particular form of apoptosis. Functional inactivation of the death receptor Fas or its adaptator FADD indicates that the activation process of caspase 8 is independent of the death receptor pathway. Altogether, these results extend our understanding on the role of the Raf/MAPk pathway in the control of cell death. We have shown that in different cellular context, this signaling pathway can either promote cell survival or induce cell death. In both cases, cell death control requires protein synthesis and post-traductionnal modifications. Molecular mechanisms that respond to prolonged MAPK1/3 activation could be involved in tumor resistance to proapoptotic treatments as well as in the development of neurodegenerative diseases
18
Montagner, Alexandra. "Etude de la phosphotyrosine phosphatase SHP2 : régulation de la voie mitogène Ras/MAPK et implication physiopathologique." Toulouse 3, 2006. http://www.theses.fr/2006TOU30114.
Full textAbstract:
Cette thèse s’inscrit dans la compréhension des mécanismes moléculaires conduisant à l’activation de la voie Ras/MAPK par le facteur de croissance épidermique. L’activation de cette voie de signalisation nécessite la phosphorylation de tyrosine régulée par des tyrosine kinases (PTK) et phosphatases (PTP). Bien que les PTP soient considérées comme des régulateurs négatifs de l’activation des voies de signalisation, certaines en sont de véritables activateurs. Ainsi, la tyrosine phosphatase SHP2 joue un rôle crucial dans l’activation de la voie de Ras. Nos travaux ont permis de démontrer que SHP2 régule négativement le recrutement d’un inhibiteur de Ras, p120RasGAP permettant ainsi le maintien de son activation. Nous avons étudié les caractéristiques biochimiques et fonctionnelles de mutants de SHP2 identifiés dans le syndrome LEOPARD. Ce travail a montré que ces mutants induisent une diminution de l’activité phosphatase de l’enzyme mais qu’ils ont un comportement hétérogène<br>This work aims to understand the molecular mechanisms leading to the Ras/MAPK pathway induced by Epidermal Growth Factor. The activation of this signalling pathway requires tyrosine phosphorylation event, a process regulated by the tyrosine kinases (PTK) and phosphatases (PTP). If most of the PTP are implicated in the downregulation of signalling pathways, some of them are real activators as the PTPase SHP2 which plays a positive role in the Ras activation. We have shown that an important role of SHP2 in this activation is to regulate the recruitment of RasGAP, a Ras inhibitor, from signalling complexes so as to sustain its activation. In the second part of this work we have studied the biochemical and functional features of LEOPARD mutations of SHP2. This study has demonstrated that LEOPARD mutants display a reduced PTP activity both in vitro and in vivo and we have observed heterogeneity between the different mutants
19
Chansard, Mathieu Simonneaux Valérie Fukuhara Chiaki. "MAPK implications in the biological rhythms of suprachiasmatic nuclei and peripheral oscillators Rôle des MAPK dans les rythmes biologiques des noyaux suprachiasmatiques et des oscillateurs périphériques /." Strasbourg : Université Louis Pasteur, 2007. http://eprints-scd-ulp.u-strasbg.fr:8080/793/01/Chansard2007.pdf.
Full textAbstract:
Thèse de doctorat : Neurosciences : Strasbourg 1 : 2007. Thesis : Neurosciences : Morehouse school of medicine (Atlanta) : 2007.<br>Thèse soutenue en co-tutelle. Titre provenant de l'écran-titre. Bibliogr. p. 203-228.
20
Gutierrez, Prat Núria. "Molecular basis of p38a MAPK signaling." Doctoral thesis, Universitat de Barcelona, 2018. http://hdl.handle.net/10803/663438.
Full textAbstract:
Cells often need to respond to damaging internal and external stimuli. One of the pathways that is frequently activated by stress stimuli involves activation of the kinase p38alpha, which can phosphorylate different substrates, including MK2.
Experiments using purified proteins have shown that non-phosphorylated p38alpha and MK2 can form a tight complex, in which structural constraints impede the interaction of both kinases with effectors and regulators.
It is therefore critical to understand how the interaction between p38alpha and MK2 is regulated to ensure that they can release from each other and phosphorylate the required substrates that mediate their functions. Here, we show that in cells under homeostatic conditions, endogenous p38alpha and MK2 form a stable complex that is disrupted upon phosphorylation of both proteins.
The separation of the two kinases causes MK2 destabilization and degradation by the proteasome in a MDM2-dependent manner. Depending on the intensity of the stimuli, p38alpha and MK2 undergo different fates. Transient stimulation leads to complex separation and MK2 degradation followed by increased MK2 expression, and the eventual reassembly of the p38alpha:MK2 complex.
On the contrary, in cells exposed to strong stimuli that lead to sustained p38alpha activation, as it is often the case with stress, both kinases remain phosphorylated, cannot bind to each other and eventually become destabilized, being unable to recover the steady state.
Taken together, our results illustrate a new mechanism of p38alpha signaling regulation based on the p38alpha:MK2 complex dynamics, which may have implications for different processes regulated by p38alpha and MK2 signaling.
21
Garcia, Josefina. "Etude des mécanismes d'activation : rôle et cibles de MAPK de type ERK au cours de la différenciation mégacaryocytaire induite par la TPO." Paris 5, 2003. http://www.theses.fr/2003PA05S001.
Full textAbstract:
La thrombopoi͏̈étine et son récepteur, Mpl, jouent un rôle majeur dans la survie et la prolifération des progéniteurs hématopoi͏̈étiques multipotentiels, l'expansion de la lignée mégacaryocytaire et la formation de plaquettes. L'étude de lignées cellulaires exprimant Mpl établies au laboratoire (UT7-Mpl), ainsi que celle de mégacaryocytes normaux, ont permis de montrer que ce sont des différences quantitatives dans l'intensité et la durée du signal, et non l'activation en soi des MAPK (Mitogen Activated Protein Kinases) de type ERK qui jouent un rôle primordial dans la décision de la cellule UT7-Mpl à différencier vers une voie donnée ou à proliférer en réponse à une cytokine. L'objectif principal de mon projet de thèse était de comprendre 1) comment les MAP kinases sont activées par la TPO et 2) comment elles participent à la différenciation et/ou prolifération des précurseurs mégacaryocytaires en cherchant leurs substrats spécifiques dans ces cellules. En ce qui concerne le mécanisme d'activation de ERK par la TPO, nos travaux préalables ont montré que le mutant de Mpl, MplDelta3, n'est plus capable d'induire la maturation mégacaryocytaire et active le MAPK de façon transitoire. Nous avons donc cherché à comprendre comment la région Delta3 de Mpl participe au signal MAPK, en tentant d'identifier les voies de signalisation qu'elle active. L'identification de ces voies de signalisation constitue une étape vers la compréhension des mécanismes moléculaires régulant la mégacaryopoi͏̈èse. Nous avons montré que le signal MAPK induit par la TPO est le produit de deux vagues d'activation, l'une précoce et transitoire dépendante de Ras/Raf-1 et l'autre, ayant lieu tardivement mais persistant à long terme, impliquant Rap1/B-Raf. C'est pour cette dernière vague de signalisation que la présence de la région Delta3 semble cruciale. .<br>Thrombopoietin and its receptor play a major role in survival and proliferation of multipotent hematopoietic progenitors, in the expansion of megakaryocytic lignage and in platelet formation. The study of megakaryocytic cell lines expressing the TPO receptor established in the laboratory (UT7-Mpl) and of normal human megakaryocytes, have shown that : it is the quantitative differences in the intensity and duration of the signal and not the actual activation of ERK MAPK (Mitogen Activated Protein Kinases) that play an essential role in the decision by the cell to differentiate into a given pathway or to proliferate in reponse to a cytokine. The main project of this thesis was to understand 1) how are MAPKs activated by TPO and 2) how do they participate in the differentiation and/or proliferation of megakaryocytic precursors by searching their specific substrates in these cells. .
22
Kadiri, Maleck. "Rôle des MAPK dans la migration des lymphocytes Th17 à travers le collagène tridimensionnel (3D)." Master's thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/27767.
Full textAbstract:
La migration des lymphocytes T à travers la matrice extracellulaire (MEC) est un évènement clé dans la réponse immune adaptative et dans les maladies inflammatoires. Bien que les mécanismes de migration trans-endothéliale soient bien étudiés, ceux impliqués dans la migration à travers la MEC du tissu interstitiel sont encore peu connus. Au laboratoire, on s'intéresse aux lymphocytes Th17 du fait de leur rôle important dans le développement des maladies auto-immunes. Nous avons récemment montré que le récepteur à domaine discoïdine de type 1 (DDR1), qui lie le collagène, est important pour la migration des Th17 à travers le collagène de type I et également in vivo dans le modèle de la poche d'air. Par ailleurs DDR1 active la voie Rho/ROCK/MAPK/ERK qui est essentielle à la motilité des Th17. Dans cette étude, nous avons investigué l'implication des voies MAPK p38 et JNK dans la migration des lymphocytes Th17 à travers le collagène de type I qui est le constituant majeur de la MEC du tissu interstitiel. Nous avons trouvé que la voie p38 est nécessaire à la migration des Th17 à travers le collagène tridimensionnel (3D), et que cette voie est activée par le récepteur DDR1. Ainsi, ces résultats suggèrent que la voie DDR1/MAPK p38 pourrait constituer une cible thérapeutique importante pour le traitement des maladies auto-immunes dépendantes des lymphocytes Th17.
23
Kim, Jin Ah. "Le rôle du MAPK (Mitogen-Activated Protein Kinase) et CDKs dans la phase G2/M." Université Joseph Fourier (Grenoble), 2008. http://www.theses.fr/2008GRE10172.
Full textAbstract:
Les points de contrôle du cycle cellulaire assurent la stabilité du génome en retardant la progression du cycle en réponse à des stress ou des dommages causés sur l'ADN. Le point de contrôle de la phase G2 régule l'entrée des cellules en mitose, tandis que le point de contrôle de la formation des fuseaux mitotiques prévient l'entrée en anaphase, jusqu'à ce que les chromosomes soient correctement alignés. Au cours de ma thèse, je me suis intéressée à l'étude des Rôle de MAPKs (Mitogen-Activated Protein Kinases) et de la protéine P21 qui est un inhibiteur de cdk (cyclin dependent kinase), dans les phases G2 et M. Les MAPKs sont d'importants médiateurs dans les réponses cellulaires induites par une grande variété de stimuli extracellulaires. Nos résultats ont montré que trois protéines membres des MAPKs ont des effets différents sur les points de contrôle G2 et de formation des fuseaux. Les protéines ERKs (extracelluar signal-regulated kinases) n'ont pas de rôle dans la progression de la phase G2 à la phase M, mais interviennent dans la régulation du point de contrôle de formation des fuseaux, et ce, en inhibant l'activité du complexe APC. Les kinases p38 et JNK (c-Jun N-terminal kinase) régulent la progression G2-M mais de façon opposée. L'inhibition de JNK et l'activation de p38 entraînent un retard des cellules en G2 par l'inactivation de cdc2. En outre, nous avons trouvé que c'est uniquement l'inhibition de JNK et non p38 qui mène à l'instabilité génomique. Les cellules accomplissent plusieurs cycles de réplication de l'ADN non accompagnés de mitose, conduisant ainsi à une augmentation de la ploïdie de la cellule. Ce phénomène est probablement dû par un recrutement inapproprié des MCMs (minichromosome maintenance) au niveau de la chromatine pendant la phase G2. Il Y a certainement une activité dépendante de la kinase cdk2 qui permet probablement à la réplication de se faire. Dans le cas de dommage persistant du fuseau mitotique, malgré que le checkpoint est toujours actif, les cellules finissent finalement par sortir de la mitose sans ségrégation chromosomique et sans cytodiérèse. Il en résulte l'apparition de cellules tétraploïdes qui sont dans une pseudo G 1 phase. Dans ce processus appelé "adaptation" or "slippage" les cellules sortent de la mitose alors que le checkpoint est toujours actif. Les causes de ce cet adaptation or slippage sont en général pas bien connus. Au cours de ma thèse, je me suis intéressée aussi à l'étude de ce phénomène. Mes résultats montrent que le complexe APC/C est actif dans ces cellules effectuant ce slippage et que cet activation est dépendante de p2I. Mes résultats montrent que l'inhibition des cdk par p21 déstabilise l'interaction Mad2-Cdc20, qui à son tour va activer APC/C<br>Cell cycle checkpoints ensure genomic stability by delaying cell cycle progression in response to stress or DNA damage. G2 checkpoint guards entry into mitosis while the spindle checkpoint prevents ce Ils from entering anaphase until ail chromosomes are properly aligned. Ln this reports, we studied the role of MAPKs (Mitogen-Activated Protein Kinases) and the cdk inhibitor, p21 in G2 and M phase. MAPKs are important mediators of cellular responses to a variety of extracellular stimuli. Previous reports have shown that MAPK cascade is essential for entry into mitosis. Our results show that three MAPK members have different effects on G2 and M phase. ERKs (extracelluar signal-regulated kinases) do not have an effect on G2 to M progression but they regulate the spindle checkpoint by inhibiting APC activity. We also found that p38 and JNKs (c¬ Jun N-terminal Kinases) regulate G2-M transition. P38 activation delays cells in G2. The G2 delay by p38 involves activation of MAPKAPK2 and inactivation of cdc2. The G2 delay by inhibition of JNKs involves cdk2 activation and cdc2 inactivation. Inhibition of JNK activity in G2 cells leads to genomic instability. Cells undergo multiple round of DNA replication without undergoing mitosis resulting in an increase in DNA ploidy. This is probably due to inappropriate loading of MCMs (minichromosome maintenance) on chromatin during G2. The presence of Cdk2 activity in G2 may lead polyploidy in JNK inhibited condition
24
Ip, Koon-ching. "Role of G[alpha]-interacting protein (GAIP) in modulation of MAPK pathways /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?BICH%202008%20IP.
Full text
25
Lee, Jin Suk. "Role of phosphatases in controlling arabidopsis mapk signalling cascades." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/732.
Full textAbstract:
Plants possess integrated signalling networks that mediate the responses to various environmental conditions. Mitogen-activated protein kinases (MAPKs) constitute a highly conserved family of enzymes in eukaryotes, and in plants MAPK-based signal transduction modules regulate a large number of physiological processes, including responses to environmental stresses and phytohormones. Regulated dephosphorylation of active MAPKs is a key component of the control of MAPK signalling cascades, and in mammals, members of the MAPK phosphatase (MKP) sub-class of dual-specificity tyrosine phosphatases have been recognized as key players for inactivating MAPKs. Five MKP homologues are found in Arabidopsis thaliana, but only limited information is available concerning their properties and biological roles. Based on initial data derived from my reverse genetics and protein interaction studies of these five potential MKPs, as well as gene function information in the literature, I chose to focus on two putative Arabidopsis MKPs, AtMKP2 and Indole-3-Butyric Acid-response 5 (IBR5).
By using a combination of genetic and biochemical studies, I established that the previously uncharacterized MKP designated AtMKP2, participates in the regulation of cellular homeostasis in ozone-challenged tissue, and can influence the activation state of two MAPKs, MPK3 and MPK6. AtMKP2-suppressed plants displayed significantly prolonged MPK3 and MPK6 activation during ozone treatment, and recombinant AtMKP2 was able to dephosphorylate both phospho-MPK3 and phospho-MPK6 in vitro, providing direct evidence that AtMKP2 may target these oxidant-activated MAPKs.
A mutation in IBR5, one of the five potential AtMKPs, was previously reported to confer reduced sensitivity to auxin and ABA in Arabidopsis. My protein interaction studies demonstrated that IBR5 and MPK12 are physically coupled and that the C-terminus of MPK12 is essential for its interaction with IBR5. In vitro dephosphorylation assays indicated that recombinant phosphoMPK12 is efficiently dephosphorylated by IBR5. In transgenic plants with reduced expression of the MPK12 gene, root growth is hypersensitive to exogenous auxins, consistent with the lower auxin sensitivity reported for ibr5 mutants.
Taken together, my data demonstrate for the first time that both AtMKP2 and IBR5 are bona fide Arabidopsis MAPK phosphatases and that they serve as important regulators of oxidative stress and auxin signalling, respectively, in Arabidopsis.
26
Hsieh, Ricardo. "Melanoma primário da mucosa oral: estudo imunoistoquímico e molecular da via da MAPK." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/5/5133/tde-10092012-135829/.
Full textAbstract:
INTRODUÇÃO: O melanoma primário da cavidade oral é uma neoplasia agressiva, rara e originada a partir da proliferação de melanócitos malignos da mucosa. Ele representa aproximadamente de 0,2 a 8% de todos os melanomas. Estudos recentes apontam algumas vias moleculares tem sido encontradas por estarem envolvidas na patogenia dos melanomas. Dentre essas vias destaca-se a via proliferativa da MAPK (mitogen activated protein kinase), esta cascata de sinalização está envolvida no controle do crescimento celular, proliferação e migração, e tem sido relacionada com um papel importante no desenvolvimento e progressão do melanoma cutâneo. OBJETIVOS: Analisar a expressão proteica e mutação pontual dos componentes da via MAPK e correlacionar com os dados clínicos-histológicos. MATERIAL E MÉTODOS: Através da imunoistoquímica avaliar a expressão proteica dos anticorpos RAS; BRAF; MEK1; MEK2; ERK1 e ERK2 em 35 casos de melanomas orais organizados em matriz (TMA: Tissue Microarray) e através de pirosequenciamento avaliar a mutação pontual dos genes BRAF; NRAS; KRAS em 14 casos de melanomas orais. RESULTADOS: Idade dos pacientes entre 9 e 91 anos, sem predileção por sexo, 75% caucasianos, 71,42% acometeram o palato, 80% com aspecto histológico grau III. A análise da expressão proteica foi: RAS (28,57%); BRAF (82,85%); MEK1 (0%); MEK2 (51,43%); ERK1 (20%)e ERK2 (74,28%). Na análise molecular observamos mutações para BRAF (9/14 casos) e NRAS (2/14 casos). CONCLUSÃO: Todos os aspectos da via MAPK necessita de outras elucidações em melanomas de áreas foto-protegidas e melanomas de mucosa e comparando diferentes populações. Entretanto, os resultados deste presente estudo apontam importante alterações na cascata RAS-RAF-MEK-ERK e estes são indicadores de prognóstico ruim em melanomas primários da mucosa oral, independente da exposição solar<br>BACKGROUND: Primary melanoma of the oral cavity is an aggressive and rare neoplasm and originated from the proliferation of malignant melanocytes of the mucosa. It represents approximately 0.2 to 8% of all melanomas. Recent studies indicate some molecular pathways have been found to be involved in the pathogenesis of melanomas. Among these means there is a proliferative MAPK pathway (\"mitogen activated protein kinase\"), this signaling pathway is involved in controlling cell growth, proliferation and migration, and it has been associated with a role in the development and progression of melanoma skin. OBJECTIVES: To analyze protein expression and mutation of components of the MAPK pathway and to correlate with the clinical, histological data. MATERIALS AND METHODS: Using immunohistochemistry to evaluate the protein expression of RAS, BRAF, MEK1, MEK2, ERK1 and ERK2 antibodies in 35 cases of oral melanomas organized array (TMA: Tissue Microarray) and using pyrosequencing to assess the mutation of the BRAF, NRAS, KRAS in 14 cases of oral melanomas. RESULTS: Age of patients between 9 and 91 years, regardless of gender, 75% Caucasian, 71.42% in palate, 80% with histologic grade III. Analysis of protein expression was: RAS (28.57%); BRAF (82.85%); MEK1 (0%), MEK2 (51.43%); ERK1 (20%) and ERK2 (74.28%). Molecular analysis we found BRAF mutations (9/14 cases) and NRAS (2/14 cases). CONCLUSION: All aspects of the MAPK pathway requires further elucidation in melanomas of photo-protected areas and mucosal melanomas and comparing different populations. However, the results of this study indicate important changes in the cascade RAS-RAF-MEK-ERK and these are indicators of poor prognosis in primary melanomas of the oral mucosa, regardless of sun exposure
27
Delépine, Etienne. "Implication de la voie MAPK ERK5 et de la famille TORC dans l'expression de Cycline D1 et le cancer du sein." Montpellier 2, 2007. http://www.theses.fr/2007MON20219.
Full text
28
Renaud, Emilie. "Inhibition isoforme spécifique des fonctions de la MAPK p38α par des fragments d’anticorps". Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTT088.
Full textAbstract:
La MAPK p38α est une protéine clé de l’inflammation, également impliquée dans de nombreux processus liés au cancer. Les petites molécules chimiques inhibitrices de p38α bloquent son activité kinase par un mécanisme de compétition à l’ATP. En raison de la grande conservation du domaine kinase, la spécificité de la majorité de ces inhibiteurs n’est pas restreinte à la p38α et des effets « off-targets » ont été rapportés. Dans ce contexte, le projet de ma thèse a porté sur l’utilisation de fragments d’anticorps au format scFv comme nouvel outil de ciblage pharmacologique afin de définir une/des voie(s) alternative(s) d’inhibition de la p38α. Les fragments d’anticorps lient un motif antigénique avec une affinité et une spécificité élevées, tout comme les immunoglobulines classiques. Leur expression intracellulaire permet également le ciblage de protéines cytoplasmiques et l’étude de leurs fonctions dans des processus physiologiques et pathologiques. Nous avons sélectionné par phage display, à partir d’une banque de fragments d’anticorps, 5 scFv spécifiques de la MAPK p38α. Alors que tous ces scFv empêchent l’activation par phosphorylation de la p38α par MKK6, l’un d’entre eux agit directement sur l’enzyme pour inhiber totalement son activité kinase in vitro. Ce scFv possède un site de liaison et un mécanisme d’inhibition distincts des inhibiteurs pharmacologiques déjà décrits : bien qu’il ne cible pas le domaine kinase et n’empêche pas la fixation de l’ATP, le scFv se comporte comme un inhibiteur compétitif de l’hydrolyse de l’ATP. Ces résultats suggèrent un effet allostérique du scFv sur l’activité de la p38α et permettent de le caractériser comme un inhibiteur compétitif non conventionnel. La détermination de son épitope d‘interaction ainsi que la confirmation de sa fonctionnalité une fois exprimé dans le cytosol des cellules nous permettra de définir une voie alternative d'inhibition de la p38α et de valider notre approche de ciblage par l’utilisation de fragments d’anticorps.Ces données ouvrent de nouvelles perspectives de design d’inhibiteurs chimiques de la p38α de meilleure spécificité que ceux actuellement disponibles<br>MAPK p38α is a key protein in inflammation, but is also involved in many cancer-related processes. All the currently described chemical inhibitors of p38α inhibit its kinase activity by an ATP-competitive mechanism. Because of the high conservation of the ATP-binding pocket, the majority of these inhibitors are not specific to p38α and off-target effects have been reported. To identify alternative approaches to inhibit p38α MAPK, my thesis project focused on the use of scFv antibody fragments as a new highly specific pharmacological tool.Antibody fragments bind to an antigen with high affinity and specificity like conventional immunoglobulins. Their intracellular expression also allows to target cytoplasmic proteins and study the target functions in physiological and pathological processes. Using a naïve library of antibody fragments, we have selected by phage display five scFv specific of MAPK p38α isoform. While all these scFv inhibit the activation of p38α by MMK6, one of them also completely inhibits its kinase activity in vitro. This scFv has a binding site and a mechanism of inhibition distinct from the pharmacological inhibitors currently described: although it does not target the ATP-binding pocket and does not prevent ATP binding, it behaves like a competitive inhibitor of ATP hydrolysis. These results suggest an allosteric effect of this scFv on p38α activity and allow to characterize it as an unconventional competitive inhibitor. The determination of its epitope as well as the confirmation of its inhibitory activity once expressed in the cell cytosol will allow us to propose an alternative approach to target p38α function using antibody fragments.These data open up new perspectives for the design of more specific p38α chemical inhibitors than those currently available
29
Azzam, Diana Galil. "Extracellular signal regulated kinase/mitogen activated protein kinase (ERK/MAPK) regulation of the androgen receptor in breast cancer cells." University of Western Australia. School of Pathology and Laboratory Medicine, 2008. http://theses.library.uwa.edu.au/adt-WU2009.0024.
Full textAbstract:
[Truncated abstract] Androgens inhibit the growth of human breast tumours and have been successfully used to treat breast cancer in women. Expression of the androgen receptor (AR), which mediates androgen action, is upregulated in breast cancer cells and the AR is the most frequently expressed steroid hormone receptor in breast tumours. AR levels and activity are modulated by the activity of other signalling pathways, however interactions between the AR and signalling pathways and the consequent alterations to the androgen responsiveness of breast cancer cells are largely uncharacterised. The extracellular signal regulated kinase (ERK1/2) pathway is hyperactivated in ~30% of breast tumours and these tumours are often associated with low oestrogen receptor-a (ERa) levels, reduced responsiveness to antioestrogen therapies and an overall poorer prognosis. In this thesis, the MCF-7 human breast cancer cell line which expresses ERa, progesterone receptor (PR) and the AR, was used to investigate ERK1/2-mediated regulation of the AR and the androgen responsiveness of cells. Inhibition of ERK1/2 signalling was achieved by treatment of cells with U0126, an inhibitor of MEK1/2, the upstream activator of ERK1/2. Hyperactivation of ERK1/2 signalling was achieved by stably transfecting cells with a plasmid encoding a constitutively active form of the MEK1 protein (¿MEK1), resulting in the isolation of two clonal cell populations stably expressing ¿MEK1, ¿C3 and ¿6B, and a monoclonal cell line stably expressing the empty vector, MT3-1. Steady state AR mRNA levels, quantitated using real-time RT-PCR, were increased following U0126 treatment of MCF-7, MT3-1 and ¿6B cells. Conversely, treatment of cells with 10-8M 5a-dihydrotestosterone (DHT) for up to 72 hours decreased AR mRNA levels, indicating that ERK1/2 hyperactivation did not alter the androgenresponsiveness of AR mRNA. '...' Overall levels of AR phosphorylation were enhanced in ¿6B cells in the absence and presence of ligand, indicating that ERK1/2 hyperactivation either directly or indirectly induced receptor phosphorylation. The AR is localised in the cytoplasm in the absence of ligand and was more rapidly translocated to the nucleus in the presence of DHT in ¿C3 cells, an effect that was abrogated in the presence of U0126, thereby indicating an ERK1/2-specific mechanism. AR transcriptional activity, measured using androgen responsive reporter plasmids was not significantly altered in ¿6B cells in either the absence or presence of DHT, although the trend towards enhanced AR activity may be confirmed in future studies using optimised reporter assays. Consistent with the cell cycle regulatory functions of ERK1/2 signalling, proliferation of ¿C3 cells and ¿6B cells was increased in comparison to that of MT3-1 and MCF-7 cells. Treatment of ¿C3 cells and MCF-7 cells with 10-10 10-8M DHT produced similar inhibition of proliferation (~40%) during 8 days of culture, with no evidence of cytotoxicity. The results obtained in this thesis demonstrate that while ERK1/2 signalling regulates AR phosphorylation, processing and intracellular localisation, ERK1/2 hyperactivation in breast cancer cells does not inhibit the anti-proliferative effects of androgens. These findings support the development of tissue-specific androgenic treatments for breast tumours including poor prognosis tumours exhibiting ERK1/2 hyperactivation.
30
Malka, mahieu Hélène. "Implication du complexe d'initiation de la traduction eIF4F dans la résistance aux inhibiteurs de la voie des MAPK." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS236.
Full textAbstract:
Le mélanome métastatique est un des cancers les plus agressifs avec une croissance constante du nombre de nouveaux cas par an dans le monde.Deux mutations sont principalement à l’origine de ce cancer : BRAF(V600) et NRAS(Q61). Les principaux traitements sont des thérapies ciblant BRAF lui-même ou MEK, prescrites en monothérapie ou en combinaison. La moitié des patients répondent à ce traitement mais malheureusement rechutent dans les 6 mois à 1 an après le début du traitement. Les mécanismes de résistance décrits passent par une réactivation de la voie des MAPK, de la voie PI3K/Akt/mTOR ou par une dérégulation de l’apoptose.Les deux premières voies de signalisation permettent la régulation d’un complexe : le complexe d’initiation de la traduction eIF4F. Ce complexe est composé de 3 protéines : eIF4E, une protéine qui s’associe à la coiffe 7-methyl-guanosine, eIF4A une hélicase et eIF4G une protéine échafaudage dont un des rôles est de maintenir la cohésion de ce complexe.Le complexe eIF4F étant en aval de deux voies dérégulées dans le mélanome, le but de ma thèse a été de mettre en évidence une potentielle implication de ce complexe dans la résistance aux thérapies ciblant BRAF et MEK.Pour cela, dans un premier temps, nous avons traiter des lignées cellulaires de mélanome BRAF(V600) sensibles et résistantes aux anti-BRAF et anti-MEK. Nous avons ensuite quantifié les interactions eIF4E-eIF4G, synonymes d’activation du complexe eIF4F, et les interactions eIF4E-4EBP1, synonymes d’inhibition de la traduction par une technique de Proximity Ligation Assay (PLA). Ces expériences ont permis de conclure que les inhibiteurs de BRAF et de MEK induisaient une dissociation du complexe dans les lignées sensibles, alors qu’il reste maintenu dans les lignées résistantes. Ces résultats ont été confirmés sur des tumeurs de patients répondeurs et non répondeurs à ces mêmes traitements. Par la suite, nous avons reproduits ces expériences avec un panel de lignées cellulaires mutées en NRAS(Q61) et avons observé les mêmes résultats.Nous avons donc pu mettre en évidence l’implication du complexe eIF4F dans la résistance aux thérapies ciblant la voie des MAPK dans les mélanomes mutés en BRAF et en NRAS, mais également découvert une nouvelle cible thérapeutique potentielle.La seconde partie de cette thèse a consisté au test de plusieurs inhibiteurs connus et spécifiques d’eIF4A (silvestrol, flavaglines, hippuristanol, patéamine A) ou de l’interaction eIF4E-eIF4G (4EGI1). Tous ces inhibiteurs ont sensibilisé les lignées résistantes aux thérapies ciblées mais aucun ne pouvait être potentiellement utilisable en clinique.L’utilisation d’un vecteur bicistronique dans le cadre d’un criblage de drogue a permis d’identifier 4 flavaglines qui inhibent significativement le complexe d’initiation de la traduction. L’une d’entre elles (FL3) a été testé in vivo dans un modèle de xénogreffes issues de lignées cellulaires de mélanomes résistantes. Les résultats ont montré un effet synergique de cette drogue en combinaison avec le vemurafenib (anti-BRAF) ainsi qu’une inhibition de la croissance tumorale. En conclusion, nous avons identifié une nouvelle cible thérapeutique et un nouveau biomarqueur de résistance aux thérapies ciblées dans deux contextes mutationnels de mélanome différents : BRAF et NRAS<br>In BRAF(V600) or NRAS(Q61)-mutant tumours, most mechanisms of resistance to drugs that target the BRAF and/or MEK kinases rely on reactivation of the RAS–RAF–MEK–ERK mitogen-activated protein kinase (MAPK) signal transduction pathway or on activation of the alternative PI(3)K–AKT–mTOR pathway (which is ERK independent). These two pathways converge to regulate the formation of the eIF4F eukaryotic translation initiation complex. By using an in situ method to detect the eIF4E-eIF4G and eIF4E-4EBP1 interactions, we recently showed that the persistent formation of the eIF4F complex, comprising the eIF4E cap-binding protein, the eIF4G scaffolding protein and the eIF4A RNA helicase, is associated with resistance to anti-BRAF and/or anti-MEK in BRAF(V600)-mutant cancer cell lines. We next focused on NRAS-mutant cancer cell lines and found that this complex is also involved in the resistance to anti-MEK compounds. Strikingly, inhibiting the eIF4F complex in BRAF or NRAS-mutated cell lines is able to overcome resistance and to synergize with drugs targeting BRAF or MEK kinases. As a result, eIF4F appears to be a promising therapeutic target in a BRAF or NRAS-mutation context
31
Liu, Jia, and 劉佳. "Role of FBXO31 in regulating MAPK-mediated genotoxic stress response and cancer cell survival." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/205657.
Full textAbstract:
Esophageal cancer is the third most common digestive tract malignancy. Along with surgery, genotoxic drugs (e.g. cisplatin) and radiotherapy are the mainstays of treatment for this disease. Environmental factors and environmental stress-induced responses contribute to esophageal tumorigenesis and chemoresistance. Studying key molecules in stress-induced signal pathway can help unravel the underlying mechanisms and discover rational therapeutic targets.
Cyclin D1 is DNA damage response protein. Genotoxic stress induces rapid cyclin D1 degradation and the molecules mediating this response are cell-type dependent. The first part of this study investigated the changes of cyclin D1 expression in response to genotoxic stress in immortalized esophageal epithelial cells, which are experimental models commonly used to study the early events of cancer development. The results showed that cyclin D1 underwent rapid proteasomal degradation before p53-induced p21 accumulation, which substantiates that cyclin D1 plays a role in eliciting cell cycle arrest very early in the DNA damage response. FBXO31 and FBX4, two F-box proteins previously reported to mediate cyclin D1 degradation, were found to be accumulated and unchanged, respectively, after ionizing irradiation in immortalized esophageal epithelial cells and esophageal squamous cell carcinoma (ESCC) cell lines. Yet, knockdown of FBXO31 did not rescue rapid cyclin D1 degradation upon UV or ionizing irradiation. This led to the hypothesis that accumulation of FBXO31 may have novel functions beyond mediating cyclin D1 degradation in cells responding to genotoxic stress.
The second part of this study explored the function of FBXO31 in genotoxic stress response. The accumulation of FBXO31 in cancer cells after exposure to various genotoxic stresses was found to coincide with p38 deactivation, giving the clue that FBXO31 may negatively regulate this important pathway. Further studies revealed that knockdown of FBXO31 resulted in sustained activation of stress-activated MAPKs (SAPKs) p38 and JNK, as well as increase in UV-induced cell apoptosis, whereas overexpression of FBXO31 had opposite effects. The inhibitory role of FBXO31 on SAPK activation and apoptosis was confirmed by shRNA rescue experiments. Consistent with the observed anti-apoptotic effect, soft agar, colony formation and in vivo xenograft experiments showed that FBXO31 had oncogenic function in ESCC. Moreover, in vitro and in vivo results showed that knockdown of FBXO31 could sensitize ESCC cells to cisplatin treatment.
The mechanism underlying the inhibition of SAPKs by FBXO31 was investigated in the third part of this study. Co-immunoprecipitation results showed that FBXO31 could interact with MKK6 (a p38 activator), but not p38, JNK1, or other MAP2Ks. FBXO31 was found to be co-localized with MKK6 in the cytoplasm. Mapping of interaction domains of FBXO31 revealed that aa 115-240 and aa 351-475 were responsible for binding to MKK6. Further study found that binding of FBXO31 to MKK6 could facilitate the K48-linked polyubiquitination and degradation of MKK6.
Taken together, the results of this study showed that FBXO31 accumulation upon genotoxic stress can promote the degradation of MKK6 via K48-linked ubiquitination, thereby inhibiting SAPK activation and protecting cancer cells from genotoxic stress-induced apoptosis. FBXO31 may be a potentially useful therapeutic target to overcome chemoresistance in cancer therapy.<br>published_or_final_version<br>Anatomy<br>Doctoral<br>Doctor of Philosophy
32
Wu, Jheng-Yu. "Regulation of Extracellular Signal-Regulated Kinase by Histone Deacetylase 6." Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/6985.
Full textAbstract:
Extracellular signal-regulated kinases 1/2 (ERK1/2) are important kinases regulating cell proliferation and cell migration, and have been established as therapeutic targets for cancer treatment. Previously, we found that ERK1 phosphorylates histone deacetylase 6 (HDAC6) to regulate its enzymatic activity. However, whether HDAC6 reciprocally modulates ERK1 activity is unknown. Here, we have discovered that ERK1/2 are acetylated proteins and shown that HDAC6 manipulates ERK1’s kinase activity via deacetylation. We demonstrated that both ERK1 and ERK2 interact with HDAC6 physically. We showed that the acetylation level of GST-ERK1/2 increased in a dose- and time-dependent manner upon treatment with a pan-HDAC inhibitor, Trichostatin A. Furthermore, the treatment by HDAC6-specific inhibitor, ACY-1215, also increased the level of acetylated GST-ERK1/2. We also noted that ERK1/2 acetylation levels increased in HDAC6-knockout mouse embryonic fibroblasts and in HDAC6-knockdown A549 cell lines compared with controls. In addition, we determined that acetyltransferases CBP and p300 acetylate ERK1/2. We have identified novel acetylation sites located in ERK1 and ERK2 by mass-spectrometry analysis. Among these acetylation sites, ERK1 lysine 72 acetylation status is related to ERK1 phosphorylation. The acetylation-mimicking mutant exhibits a decreased kinase activity toward ELK1, while the deacetylation-mimicking mutant exhibits a similar level of kinase activity as the wild-type ERK1, suggesting that acetylation/deacetylation alters ERK1 enzymatic activities. Taken together, our results suggest that HDAC6 may regulate ERK1’s kinase activity via deacetylation of its lysine 72 residue.
33
Makarenko, Rostyslav. ""Adaptive mutations" in the S/MAPK pathways provide selective advantage in quiescent fission yeast." Electronic Thesis or Diss., Sorbonne université, 2019. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2019SORUS253.pdf.
Full textAbstract:
La quiescence et la prolifération reflètent deux stades cellulaires fondamentalement différents, mais il existe très peu d'informations sur la manière dont les cellules maintiennent la stabilité de leur génome en quiescence. En utilisant des levures de fission privées d’azote comme modèle de quiescence, notre laboratoire a démontré que les cellules subissent non seulement les dommages de l’ADN aux indépendantes de la réplication linéairement avec le temps. Dans les travaux en cours, nous avons démontré que les mutations accumulées au cours de la phase d'arrêt de la croissance subissent un processus de sélection en quiescence similaire à celui observé chez E. coli. La sélection favorise les mutations qui affectent les fonctions des gènes des 3 voies de la MAP-kinase (mkh1, pek1, pmk1) et de la SAP-kinase (win1, wis1, sty1) et de leurs cibles en aval (pmc1, sgf73, tif452). Ces gènes sont impliqués dans la signalisation cellulaire centrale qui régule la prolifération, la différenciation et la mort cellulaire conservée chez toutes les espèces eucaryotes, de la levure à l'homme. Des mutations dans des composants de la voie S/MAPK ou dans ses régulateurs sont associées à de multiples maladies chez l'homme, dont certains cancers et une mort neuronale dégénérative en fonction de l'âge. Les cellules libèrent des traces d'azote lors de leur mort, ce qui déclenche l'entrée dans le cycle cellulaire des cellules encore en vie. Les cellules sauvages ne peuvent compléter un cycle et meurent, libérant davantage d'azote. Les mutants de la voie S/MAPK sont caractérisés par une capacité d'entrée dans le cycle différente en fonction de la concentration d'azote disponible ce qui entraine une résistance à la mort cellulaire<br>Quiescence and proliferation reflect two fundamentally different cellular stages, yet very limited information exists on how cells maintain their genome stability in quiescence. Using nitrogen-starved fission yeast as a model for quiescence, our laboratory has demonstrated that cells are not only subject to DNA damage in G0 but also accumulate replication-independent mutations linearly with time. In our current work, we have demonstrated that mutations accumulating in growth-arrested phase undergo a selection process in quiescence similar to that observed in E. coli. Selection favors mutations that affect functions of the genes of the MAP-kinase (mkh1, pek1, pmk1) and SAP-kinase pathways (win1, wis1, sty1), and their downstream targets (pmc1, sgf73, tif452). These genes represent core cellular signaling that regulates cell proliferation, cell differentiation, and cell death conserved among all eukaryotic species from yeast to human. Mutations in components of the S/MAPK pathways and their regulators are associated with multiple diseases in humans, primary cancer and degenerative neuronal death accumulated with ageing. In this work, we have demonstrated that wild-type cells dying in quiescence release traces of nitrogen that triggers the viable population to exit from quiescence. The wild-type cells are dying during their entry into S-phase releasing more nitrogen. Thus, mutants in the S/MAPK pathways are better scavengers and selection in quiescence is characterized by the ability of the mutant to resume cycling in quiescence coupled with a resistance to programed cell death
34
Catozzi, Simona. "Rétroactivité dans la transduction du signal : étude comparative des réponses en aval et en amont dans les cascades de signalisation." Thesis, Université Côte d'Azur (ComUE), 2016. http://www.theses.fr/2016AZUR4122/document.
Full textAbstract:
Les cellules communiquent avec leur environnement par l’intermédiaire d’un réseau de transduction du signal, leur permettant d’interpréter des signaux physico-chimiques et de produire des réponses appropriées. Ce mécanisme est orchestré par des cascades de signalisation, qui jouent le rôle d’émetteurs intracellulaires en transférant des stimuli biochimiques entre la membrane et le noyau. Il a été montré qu’une perturbation peut se propager en amont (et pas seulement en aval) d’une cascade par un phénomène appelé rétroactivité. Notre étude vise à comparer les conditions biochimiques qui favorisent un et/ou l’autre sens de signalisation dans des cascades linéaires. Au moyen d’approches analytiques et numériques, nous avons caractérisé les différents régimes de signalisation résultants, que nous avons résumés avec une représentation graphique compacte. Nous avons également développé le concept de profil d’activation d’une voie de signalisation qui est, pour un stimulus donné, la séquence des protéines activées à chaque niveau de la cascade à l’état stationnaire. Ces séquences correspondent à des morceaux d’orbites d’un système dynamique discret bidimensionnel. A partir de l’étude des portraits de phase, en fonction des paramètres biochimiques, nous avons étudié les propriétés de contraction/expansion autour des points fixes et de leurs bifurcations. Nous avons classifié les niveaux de cascade en trois types et examiné leur impact biologique au sein d’un réseau de signalisation. Cette méthode a également fourni une vision globale de l’interaction entre la signalisation en avant et rétroactive, et de l’amplification du signal le long du profil d’activation de la cascade<br>Living cells communicate with their external environment, by means of a signal transduction network, which allows them to interpret physico-chemical signals and produce appropriate responses. This complex machinery is orchestrated by signaling cascades, which play the role of intracellular transmitters, by transferring biochemical stimuli between cellular membrane and nucleus. It has been shown that a perturbation can propagate upstream (and not only downstream) a cascade, through a phenomenon called retroactivity. Our investigation aims to compare the biochemical conditions promoting one and/or the other direction of signaling in linear cascades. By means of analytical and numerical approaches, we have answered to this question, by characterizing the arising different signaling regimes, and we have designed a compact graphical representation to relay the gist of such conditions. We have also developed the concept of pathway activation profile which is, for a given stimulus, the sequence of activated proteins at each tier of the cascade, at steady state. Such sequences correspond to pieces of orbits of a two-dimensional discrete dynamical system. From the study of the possible phase portraits, as a function of the biochemical parameters, we focused on the contraction/expansion properties around the fixed points of this discrete map, and their bifurcations. We have deduced a classification of the cascade tiers into three main types, whose biological impact within a signaling network has been examined. This method also provided global insights about the interplay between forward and retroactive signaling, and how signal is amplified along the cascade activation profile
35
Lennmyr, Fredrik. "Signal Transduction in Focal Cerebral Ischemia : Experimental Studies on VEGF, MAPK and Src family kinases." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2002. http://publications.uu.se/theses/91-554-5267-1/.
Full text
36
Laurent, Anouchka. "Caracterisation et modélisation des pathologies lymphoides présentant des gains du chromosome 21." Thesis, Université de Paris (2019-....), 2019. http://www.theses.fr/2019UNIP7061.
Full textAbstract:
Les gains somatiques du chromosome 21 (+21) sont fréquemment observés dans les hémopathies, et les enfants atteints par le Syndrome de Down (DS, trisomie 21 constitutive) ont un risque plus élevé de développer des leucémies durant l’enfance. Ces observations indiquent que +21 participent au développement leucémique. Cependant, la trisomie 21 seule n’est pas suffisante. L'objectif de cette thèse a été de caractériser et modéliser les altérations génétiques coopérant avec les gains du chromosome 21. Un premier axe a permis d’étudier l’impact de la mutation activatrice JAK3A572V dans un modèle murin (knock-in au locus endogène) dans le développement d’un lymphome cutané à cellules T (CTCL). Croisé avec un modèle de trisomie 21 partiel (Ts1Rhr), la latence de ce CTCL est fortement réduite, indiquant une coopération oncogénique. Dans un deuxième axe, j'ai identifié une forte incidence des altérations activant de la voie RAS/MAPK dans les leucémies aiguës lymphoblastiques B pédiatriques (LAL-B) +21. J'ai démontré que la mutation KRASG12D coopère fonctionnellement avec la trisomie 21 dans le processus de transformation à la fois dans des modèles cellulaires murins et des cellules leucémiques humaines. J’ai également développé 20 modèles de xénogreffes pour tester l’efficacité du trametinib, un inhibiteur de la voie RAS/MAPK. Seul ou en combinaison avec des chimiothérapies conventionnelles (vincristine), j’ai montré que l’inhibition de la voie RAS/MAPK prolonge la survie de ces souris. Ces données indiquent que la caractérisation et le ciblage d’événements de coopération permettent de proposer de nouvelles stratégies thérapeutiques pour les leucémies pédiatriques avec +21<br>Somatic gains of chromosome 21 (+21) are hallmark of hematological malignancies, and children with Down Syndrome (DS, constitutive trisomy 21) are predisposed to develop leukemia. These observations strongly suggest that gains of chromosome 21 promote leukemia development; however, alone, it is not sufficient. The aim of my PhD work was to identify and functionally characterize the genetic alterations cooperating with +21. My first aim was focused on studying the impact of the JAK3A572V activating mutation in the development of cutaneous T cell lymphoma (CTCL), using a new knock-in model carrying this alteration at the endogenous locus. In this study, I showed that partial trisomy 21 (Ts1Rhr) cooperates with the JAK3A572V mutation to reduce the latency of this pathology, thus highlighting a mechanism of oncogenic cooperation. In a second aim, I identified a high incidence of genetic alterations leading to RAS/MAPK pathway activation in B cell leukemia samples carrying +21 (B-ALL+21). I have demonstrated that the KRASG12D mutation functionally cooperates with trisomy 21 in transformation process of both murine and human cellular models. In order to test new molecules to improve the treatment of LAL-B+21, I have also developed 20 xenograft models. Treatment of these models with trametinib, a RAS/MAPK pathway inhibitor, alone or in combination with conventional chemotherapies (vincristine), improve their survival. Together, these data indicate that characterizing and targeting cooperation events allow to propose novel therapeutic strategies in pediatric leukaemia with +21
37
Escoté, Miró Xavier. "Control of cell cycle progression by the last MAPK Hog1." Doctoral thesis, Universitat Pompeu Fabra, 2005. http://hdl.handle.net/10803/7186.
Full textAbstract:
Exposure of yeast to increases in extracellular osmolarity activates the stress-activated Hog1 MAP kinase, which is essential for cell survival upon osmotic stress. Activation of the Hog1 MAPK results in cell growth arrest, suggesting a possible role of the MAP kinase in the control of the cell cycle. Our results have shown that Hog1 activation resulted in accumulation of cells in the G1/S and G2/M transitions. At G1, Hog1 regulates the cell cycle progression by a dual mechanism that involves downregulation of G1 cyclin expression and direct targeting of the CDK-inhibitor protein Sic1. The MAPK interacts with Sic1, and phosphorylates a single residue of Sic1, which, in combination with the downregulation of cyclin expression, results in Sic1 stabilization and inhibition of cell cycle progression. Consistently, sic1_ cells, or cells containing a SIC1 allele mutated in the Hog1 phosphorylation site, are unable to arrest at G1 phase after Hog1 activation, and become sensitive to osmostress. Together, our data indicate that Sic1 is the molecular target for Hog1 that is required to modulate cell cycle progression in response to stress at G1. On the other hand, activation of the Hog1 MAPK also results in an increase of cells in the G2 phase. Arrested cells displayed down regulation of the Clb2-Cdc28 kinase activity and consequently enlarged buds, defects in spindle formation and orientation. These effects were prevented by deletion of the SWE1 gene. Thus, swe1Ä cells failed to arrest at G2, which resulted in a premature entry into mitosis and mislocalization of nuclei. Consistently, swe1Ä cells were osmosensitive. Swe1 degradation was reduced in response to activation of Hog1. Swe1 accumulation is mediated by the activity of the complex Hsl1-Hsl7. Hog1 phosphorylates a single residue at the regulatory domain of Hsl1, which leads to the mislocalization of Hsl7 from the bud neck, and consequent Swe1 accumulation. In addition, Hog1 downregulates G2 cyclin expression, reinforcing the inhibition of cell cycle progression at G2/M. These results indicate that Hog1 imposes a delay in critical phases of cell cycle progression necessary for proper cellular adaptation to new extracellular conditions.
38
Brixey, Rachel J. E. "Genetic analyses of MAP kinase signalling in mouse gonad development." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:54242de2-8e43-4cf2-ad12-d94a2c187c44.
Full textAbstract:
Sexual development begins with the process by which the bipotential gonads of the embryonic urogenital ridge develop into either testes or ovaries. In the mouse, sex determination occurs at around 11.5 dpc and depends on the presence or absence of the Y chromosome and the associated activity of the testis-determining gene, Sry, in supporting cell precursors. The mutually antagonistic male and female developmental pathways are regulated by many cellular and molecular processes, disruption of which can lead to disorders of sex development (DSDs). However, many of the molecular mechanisms regulating the differentiation of the two gonads are still unknown. The boygirl (byg) mutant was identified in an ENU-based forward genetic screen for embryos with gonadal abnormalities. On the C57BL/6J background, XY byg/byg homozygotes exhibited complete embryonic gonadal sex reversal. The defective gene in byg, Map3k4, is a component of the mitogen-activated protein (MAP) kinase signalling pathway and provides the first evidence for a function of this pathway in sex determination. This thesis describes experiments aimed at investigating the cellular and molecular basis of the sex reversal phenotype associated with the XY Map3k<sup>4byg/byg</sup> mutant. Cellular characterisations revealed a defect in male-specific proliferation at 11.5 dpc, which was attributed to a defect in Sry up-regulation. Elucidation of the downstream kinases activated by MAP3K4 during sex determination was attempted, with particular focus on identifying a role for p38α MAP kinase (MAPK). Using a conditional knockout approach, the function of p38α in Steroidogenic factor-1 (Sf1)-positive somatic cells was assessed. However, specific inactivation in these cells did not affect gonad development. Conditional inactivation of Map3k4 itself in these Sf1¬-positive cells also did not disrupt gonad development, suggesting that this pathway is either initiated in a different cell lineage or at an earlier stage than deletion driven by Sf1-Cre can disrupt. Conditional inactivation of p38α in the Müllerian duct mesenchyme and ovarian granulosa cells using Amhr2-Cre did reveal a function for p38α in female fertility, but did not disrupt embryonic sexual development. Gene knockdown in organ culture was attempted to determine a role for multiple p38 MAPKs in all cell types of the gonad. Therefore, this thesis details further characterisations of a novel signalling pathway important for the expression of Sry, focussing on the role of the p38 MAPKs.
39
Zhan, Yu. "Mixed Lineage Kinase 3 Signaling in Ovarian Cancer and Neurofibromatosis-2." University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1310127039.
Full text
40
Satterfield, Erica. "The Role of Mitogen-activated Protein Kinases in the Regulation of Plant Development." VCU Scholars Compass, 2009. http://scholarscompass.vcu.edu/etd/1775.
Full textAbstract:
Mitogen-activated protein kinases are part of an evolutionarily conserved protein phosphorylation cascade which serves essential regulatory functions in eukaryotic organisms. Although the role of MAPKs in the regulation of a plant’s response to environmental stress and plant defense has been well established, very little is known about their role in the regulation of plant developmental processes. In order to examine the role of MAPKs in plant growth and development, a strong mammalian MAPK phosphatase (MKP-1), which is known to inactivate MAPKs in plants, was introduced into tobacco plants. In tobacco plants, MKP-1 overexpression altered plant responses to the phytohormones, ethylene and cytokinin. Tobacco plants expressing MKP-1 flowered earlier and senesced later than wild-type. Additionally, these plants exhibited similar floral morphology as flowers from ethylene-insensitive tobacco plants. These observed phenotypes seem to depend on the protein phosphatase activity, as transgenic lines expressing an inactive form of MKP-1 (MKPCS) did not show the same phenotypes. Furthermore, both tobacco and Arabidopsis MKP-1 transgenic plants exhibited increased shoot regeneration when compared to wild-type plants, suggesting increased cytokinin sensitivity. In an attempt to elucidate the mechanism by which MKP-1 affects plant growth and development, expression of selected genes were analyzed using RT-PCR. MKP-1 transformed tobacco plants exhibited downregulated expression of an ethylene biosynthesis gene (NtACO) and upregulated expression of a pathogenesis-related gene (PR-1b), similar to gene expression studies previously conducted in plants with increased production of cytokinin. The same MKP-1 transgenic plants also exhibited upregulated expression of the flowering time gene, FT. Results from this study indicate that constitutive expression of MKP-1 may interfere with ethylene-related MAPK pathways, which normally serves to restrict plant growth during times of environmental stress. The reduced responses to ethylene resulted in elevated sensitivity to cytokinin, promoting an enhanced shoot regeneration phenotype.
41
Tong, Ho-kwan. "Functional regulation of the forkhead box M1 transcription factor by Raf/MEK/MAPK signaling." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B37654597.
Full text
42
Tong, Ho-kwan, and 湯皓鈞. "Functional regulation of the forkhead box M1 transcription factor by Raf/MEK/MAPK signaling." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37654597.
Full text
43
Chansard, Mathieu. "MAPK implications in the biological rhythms of suprachiasmatic nuclei and peripheral oscillators." Université Louis Pasteur (Strasbourg) (1971-2008), 2007. https://publication-theses.unistra.fr/public/theses_doctorat/2007/CHANSARD_Mathieu_2007.pdf.
Full textAbstract:
Chez les Mammifères, l’horloge circadienne principale est située dans les noyaux suprachiasmatiques (NSC) de l’hypothalamus, et plusieurs oscillateurs existent à la périphérie. Un système afférent conduit l’information lumineuse aux NSC pour entraîner l’horloge à 24h, alors que des systèmes efférents, tels que la synthèse de la mélatonine par la pinéale, distribuent l’information temporelle au reste de l’organisme. Deux sous-familles de « mitogen-activated protein kinases » (MAPK) sont impliquées dans les mécanismes transcriptionnels et post-traductionnels qui définissent la période de 24h de l’horloge, et qui régulent l’« arylalkylamine N-acetyltransferase », une enzyme essentielle à la synthèse de la mélatonine. Nos résultats suggèrent qu’une autre sous-famille de MAPK, les JNK, est impliquée à deux niveaux du système circadien : l’horloge moléculaire en régulant la période, et un système efférent en participant à la transcription d’enzymes nécessaires à la synthèse de la mélatonine<br>Most living organisms have developed endogenous biological clocks to adapt to and anticipate daily and seasonal changes in the environment. In mammals, a main circadian clock is located within the suprachiasmatic nuclei (SCN) of the hypothalamus, and multiple oscillators exist in the periphery. Autoregulatory feedback loops, where clock proteins regulate their own rhythmic expression by inhibiting the transcription of their cognate genes, constitute the circadian molecular machinery. At the level of the SCN, an afferent system conveys the light information to the SCN to entrain the clock to 24 h, while efferent systems, including the synthesis of the pineal melatonin hormone, distribute the time information to the whole organism. Transcriptional and posttranslational regulations are critical to define the 24-h period of the molecular clockwork, and to regulate the arylalkylamine N-acetyltransferase, a key enzyme for the melatonin synthesis. Recent studies have suggest that two subfamilies of mitogen-activated protein kinases (MAPK), extracellular signal-regulated kinase 1/2 and p38MAPK, are involved in these transcriptional and post-translational regulations by phosphorylating target proteins. Little is known on the role of a third subfamily of MAPK, JNK, in the circadian system. The aim of this thesis was to investigate the potential regulatory functions of JNK isoforms in both the molecular clockwork and the melatonin synthesis. Our results demonstrate that JNK isoforms display distinct activation patterns in rat-1 fibroblasts: p46 kDa and p54 kDa isoforms are both acutely phosphorylated while only p46 kDa phosphorylation level is rhythmic over the circadian cycle. We showed that the activation level of JNK is critical to properly define the period of the clock in rat-1 cells. Also, we found that JNK activation determines the pace of the oscillations in the mouse SCN and some but not all peripheral tissues. In the rat pineal gland, we established that the transient cAMP-induced activation of JNK isoforms is also necessary for the cAMPinduced transcription of several genes including Aa-Nat. Besides, both JNK and p38MAPK activation contribute to the expression of Mkp-1, a MAPK phosphatase. Altogether, our results support a role for JNK isoforms at two levels of the circadian system: the molecular clockwork by regulating the period of the clock, and the efferent system by driving the transcription of enzymes that participate to the melatonin synthesis
44
Kulacz, Wojciech. "Regulation of Inverted Formin-1 (INF1) by Microtubule-Affinity Regulating Kinase 2 (MARK2)." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/22801.
Full textAbstract:
The actin and microtubule cytoskeleton plays a critical role in the establishment of cell polarity. Cell processes like mitosis and migration rely on the reorganization of the cytoskeleton to properly function. One driver of cell polarity is the formin, Inverted Formin-1 (INF1). INF1 is able to induce F-actin formation, activate the Serum Response Factor (SRF) pathway, stabilize microtubules, associate with microtubules, and disperse the Golgi body. Regulation of INF1 is unique, since it does not possess conserved formin regulatory domains. However, INF1 does possess many potential phosphorylation sites. In this study, we demonstrate that INF1’s ability to induce F-actin stress fibers and activate SRF is inhibited by Microtubule-Affinity Regulating Kinase 2 (MARK2). Inhibition of INF1’s actin polymerization activity by MARK2 likely occurs near INF1’s C-terminus. However, MARK2 was unable to inhibit INF1’s ability to stabilize microtubules, associate with microtubules, and disperse the Golgi. Furthermore, we show that INF1 overexpression is associated with primary cilium absence and in some cases, the presence of long cilia, suggesting that INF1 plays a role in primary cilium formation.
45
Jin, Jiawei. "Signalling regulation of cardiac hypertrophy by the mitogen activated protein kinase (MAPK) pathways." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/signalling-regulation-of-cardiac-hypertrophy-by-the-mitogen-activated-protein-kinase-mapk-pathways(028e5785-b25f-4459-9668-ad13a2885a40).html.
Full textAbstract:
Heart failure induced by cardiac hypertrophy is a cause of high mortality in the world and has been the fastest growing cardiovascular disease over the past decade. Cardiac hypertrophy is characterised as a reactive increase in cardiac mass growth with a complex of ventricular remodelling. It occurs initially as a compensatory response to an increased workload but eventually leads to cardiac dysfunction. An in-depth understanding of cardiac hypertrophy and the capacity to regulate it has profound clinical implications. The MAPK pathways provide an important connection between external stimuli and intracellular signals for cardiac hypertrophic response. At least four MAPK subfamilies have been identified: extracellular-regulated protein kinases 1 and 2 (ERK1/2), ERK5, c-Jun NH2-terminal protein kinases (JNKs) and p38 MAPKs. Mitogen-activated protein kinase kinase 4 (MKK4), a vital activator of JNK and p38 is implicated as an important mediator of hypertrophy. ERK5, an atypical MAPK, is also involved in both hypertrophic growth and cardiomyocyte survival. However, conflicting data have been yielded from previously-published studies, since the results are based entirely on experiments conducted in cultured cardiomyocytes or transgenic and conventional knockout mouse models. To elucidate their biological roles and underlying signalling mechanisms in hypertrophy, mice with a cardiomyocyte-specific deletion of MKK4 or ERK5 (MKK4cko and ERK5cko mice) were generated in the present study. In response to pathological hypertrophic stresses including pressure overload or isoprenaline stimulation, MKK4cko mice developed exacerbated pathological hypertrophy with increased cardiomyocyte apoptosis, impaired cardiac function and remarkably upregulated NFAT (nuclear factor of T-cell) transcriptional activity. However, MKK4cko mice exhibited a similar extent of swimming exercise-induced physiological hypertrophy compared with the controls. In response to pathological hypertrophic stimuli, ERK5cko mice were resistant to hypertrophic growth, foetal gene induction and ventricular fibrosis, which is associated with repressed activation of MEF2 (myocyte enhancer factor 2). ERK5 deficiency also caused a profound increase in cardiomyocyte apoptosis which accounted for the impaired cardiac function. In conclusion, the present study provides biological evidence that clarifies in vivo functions of MKK4 and ERK5 in hypertrophy. MKK4 acts a protective role against pathological hypertrophy through inhibiting NFAT signalling, but it is not necessary for the regulation of physiological hypertrophy. ERK5 is essential for pathological hypertrophic remodelling and cardiomyocyte survival and its function in hypertrophic remodelling is mediated through regulation of MEF2 activity. Taken together, these data presented in my thesis advances knowledge about biological functions of MAPK pathways in the heart.
46
Martínez, Cebrián Gerard 1992. "Identification of novel histone marks required for the transcriptional stress response." Doctoral thesis, Universitat Pompeu Fabra, 2019. http://hdl.handle.net/10803/668153.
Full textAbstract:
Upon environmental stresses such as temperature fluctuations or increases in osmolarity, yeast
Saccharomyces cerevisiae induces a transcriptional reprograming in order to survive and adapt to
the stress. Histone post-translational modifications are key regulatory elements known to modulate
transcription. By using a complete collection of histone mutants, we performed a high throughput
transcriptional screening to assess the histone residues required for a proper induction of stressresponsive fluorescent reporters upon heat and osmotic stress. From our screening, we could
extract general conclusions regarding the histone residues required for the stress-induced
transcription. We observed poor overlap between the residues necessary for heat and osmotic
stress. Results from the screening also suggested accessible and modifiable residues were more
prone to affect stress-induced transcription when mutated. Following such indications, we selected
the accessible and modifiable residues H4-S47 and H4-T30 as their mutation rendered
transcriptional defects upon osmotic and heat stress respectively. We validated and characterized
the extent of their transcriptional defects by northern blot and RNA sequencing. We also identified
and characterized Cla4 and Ste20 for H4-S47 and Ste11 for the H4-T30 as the putative kinases
phosphorylating these residues upon stress. In addition, the study of other residues identified in
the screening opens new possibilities to identify novel histone modifications relevant for the
transcriptional stress response.<br>Durant estressos ambientals, com ara fluctuacions de temperatura o augment de l'osmolaritat, el
llevat Saccharomyces cerevisiae indueix una reprogramació transcripcional per sobreviure i
adaptar-se a l'estrès. Les modificacions post-traduccionals d'histones són elements reguladors clau
coneguts per modular la transcripció. Utilitzant una col·lecció complet de mutants d'histona, vam
realitzar un cribratge transcripcional a gran escala per a avaluar els residus d'histona necessaris per
a una inducció adequada de senyalitzadors fluorescents que responen a estrès osmòtic i tèrmic. Del
nostre cribratge, vam poder extreure conclusions generals sobre els residus d'histona necessaris
per a la transcripció induïda per estrès. Vam observar poc solapament entre els residus necessaris
per l’estrès tèrmic i osmòtic. Els resultats del cribratge també suggereixen que els residus
accessibles i modificables, quan se’ls mutava, eren més propensos a afectar la transcripció induïda
per l'estrès. Seguint aquestes indicacions, vam seleccionar els residus accessibles i modificables
H4-S47 i H4-T30 ja que la seva mutació proporcionava defectes transcripcionals en estrès osmòtic
i tèrmic respectivament. Vam validar i caracteritzar l’extensió dels seus defectes transcripcionals
mitjançant norther blot i seqüenciació d’ARN. També vam identificar i caracteritzar Cla4 i Ste20
per a H4-S47 i Ste11 per a H4-T30 com a possibles quinases que fosforilen els dos residus en
estrès. A més, l'estudi d'altres residus identificats en el cribratge obre noves possibilitats per
identificar noves modificacions d'histona rellevants per a la resposta transcripcional en estrès.
47
Kramer, Bastian. "Identifizierung und Charakterisierung neuer Pathogenitätsfaktoren in einem MAPK-Signalweg des weizenpathogenen Pilzes Mycosphaerella graminicola." Duisburg Köln WiKu, 2009. http://d-nb.info/992415756/04.
Full text
48
Forés, Maresma Marta. "Mecanismo de acción del factor represor Capicua, un sensor de señales Ras/MAPK." Doctoral thesis, Universitat de Barcelona, 2017. http://hdl.handle.net/10803/406130.
Full textAbstract:
Las vías de señalización receptor tirosina quinasa (RTK) inducen múltiples respuestas biológicas, a menudo regulando la expresión de genes. La proteína HMG-box Capicua (Cic) es un represor transcripcional inactivado en respuesta a la señal RTK. Por su papel por debajo de las vías RTK, en humanos, el homólogo de Cic (CIC) está implicado en diferentes tipos de cáncer como oligodendroglioma y sarcomas de tipo Ewing-like.
Tanto en Drosophila como en mamíferos, Cic se expresa como dos isoformas, Cic-L y Cic-S, cuya significancia y mecanismo de acción no se conocen del todo bien. Ambas isoformas contienen un dominio HMG-box presuntamente responsable de su unión al ADN en los enhancers de sus genes diana; y un motivo C-terminal llamado C1 con una función desconocida, pero indispensable para la función de Cic. Además, en Cic-S hay otro motivo conservado al que hemos llamado N2 con una función desconocida. Durante esta tesis, hemos tratado de caracterizar la función molecular de diferentes dominios de Cic esenciales para su función con el objetivo de entender mejor el mecanismo de acción de Cic.
Hemos descubierto que la proteína Cic de Drosophila requiere del correpresor Gro en su función en el embrión temprano pero no durante otros estadios del desarrollo. El mecanismo dependiente de Gro requiere el motivo N2, único en la isoforma Cic-S, el cual es diferente a los motivos de interacción con Gro definidos hasta el momento. Nuestros datos indican que el motivo N2 apareció durante la aparición de los primeros dípteros, cuando la isoforma Cic-S evolucionó de la forma ancestral Cic-L. De acuerdo con esto, la isoforma Cic-L carece del motivo N2 y es completamente inactiva en el embrión de Drosophila, indicando que el motivo N2 aportó a Cic-S una nueva actividad dependiente de Gro en este tejido. Además, nuestros resultados implican que es improbable que las proteínas CIC de mamíferos actúen a través de Gro puesto que carecen del motivo N2, y han evolucionado independientemente de las formas Cic-S de dípteros.
Por otro lado, hemos estudiado la sensibilidad de Cic a las vías Ras/MAPK en Drosophila. La proteína Cic de Drosophila contiene un motivo llamado C2 el cual es responsable de la interacción de Cic con MAPK. Hemos visto que este motivo, el cual sólo se había estudiado en el contexto de la forma Cic-S, es esencial para la regulación de ambas isoformas. Además, hemos encontrado que Cic puede estar regulado de formas adicionales a la vía Ras/MAPK. En el disco imaginal de ala, Cic puede ser fosforilado y regulado de manera aditiva por la vía Ras/MAPK y por Minibrain y su proteína adaptadora Wings apart.
Por último, hemos caracterizado el modo de unión de Cic al ADN. Las proteínas HMG-box suelen unirse a ADN a través de este motivo, pero esta unión es relativamente débil y cada subfamilia HMG-box utiliza diferentes mecanismos para aumentar la afinidad y especificidad en su unión a ADN. Hemos visto que Cic emplea un nuevo mecanismo de unión a ADN que requiere del motivo distante C1. Ambos dominios son necesrios para la union a lugares octaméricos específicos en los enhancers de los genes diana de Cic, de modo que forman una estructura bipartita para una unión específica a ADN y este mecanismo opera tanto en Drosophila como en humanos. Finalmente el papel del motivo C1 en la unión a ADN explica el hecho de que este dominio esté frecuentemente mutado en oligodendroglioma, mientras que debe ser preservado cuando CIC actua como oncogén en las quimeras CIC-DUX4 que provocan sarcomas de tipo Ewing-Like.<br>RTK signaling pathways induce multiple biological responses by regulating the expression of downstream genes. The HMG-box protein Capicua (Cic) is a transcriptional repressor downregulated in response to RTK signaling.
In both Drosophila and mammals, Cic is expressed as two isoforms, Cic-S and Cic-L. Both isoforms contain two conserved domains: an HMG-box presumably responsible of binding to its target genes, and a C-terminal domain called C1 of unknown function.
We discovered that Drosophila Cic relies on the Groucho (Gro) corepressor during its function in the embryo, but not during other stages of development. This Gro-dependent mechanism requires the N2 motif, a short peptide unique to Cic-S, different from other previously defined Gro-interacting motifs. The N2 motif is an evolutionary innovation that originated within dipteran insects, as the Cic-S isoform evolved from an ancestral Cic-L form. Our results suggest that the N2 motif endowed Cic-S with a novel Gro-dependent activity that is obligatory in the Drosophila embryo.
We also investigated the regulation of Cic via phosphorylation, and we found that the C2 domain, the MAPK docking site of Cic, is important for both Cic-S and Cic-L isoforms. Moreover, we discover that in the imaginal wing disc, the phosphorylation by MAPK functions additively with the phosphorylation by Minibrain and Wings apart.
On the other hand, we characterize the DNA binding mechanism of Cic. It is known that HMG-box proteins bind DNA via their HMG-box. This binding is relatively weak and HMG-box factors employ distinct mechanisms for enhancing their affinity and specificity for DNA. We report that the mode of Cic DNA binding distinguishes it from other HMG-box factors. We find that the HMG-box of Cic does not bind DNA alone but instead requires the C1 motif. Both domains are strictly necessary for binding specific octameric sites and we suggest that they form a bipartite structure for sequence-specific binding. This binding mechanism operates throughout Drosophila development and in human cells. Finally, the key role of C1 in DNA binding also explains the fact that this domain is a hotspot for inactivating mutations in oligodendroglioma, while being preserved in oncogenic CIC-DUX4 fusion chimeras associated to Ewing-like sarcomas.
49
Ng, Dominic Chi Hiung. "Characterizing intracellular signaling mechanisms involved in the progression of cardiac hypertrophy and failure : involvement of JAK/STAT and MAPK pathways." University of Western Australia. Biochemistry and Molecular Biology Discipline Group, 2003. http://theses.library.uwa.edu.au/adt-WU2003.0032.
Full textAbstract:
[Truncated abstract] The innate ability of the heart to compensate for an increase in workload as a result of disease or injury, through an increase in size and mass is known as cardiac hypertrophy. The hypertrophy of the heart compensates for an increase in workload with an increase in cardiac output. However, excessive hypertrophy can result in cardiac dysfunction and substantially increases the risk of cardiac failure and mortality. The molecular mechanisms that regulate the development of cardiac hypertrophy and cardiac failure are not entirely understood. Traditionally, the G-protein Coupled Receptor (GPCR) and the downstream Mitogen-Activated Protein Kinase (MAPK) family of proteins have been implicated. However, elevated circulating and ventricular levels of several classes of cytokines also suggested that signaling by the downstream effectors of cytokine receptors, such as the Signal Transducers and Activators of Transcription (STATs), may be important. The aim of this thesis was, therefore, to characterize the involvement of MAPK and STAT pathways in regulating cardiac hypertrophy and cardiac failure. A function for MAPK and STAT signaling in regulating cardiac hypertrophy stimulated by the inflammatory cytokine IL-1Β was initially defined in primary cultures of neonatal rat cardiac myocytes. In this study, it was demonstrated that the chemical inhibition of ERK or p38MAPK was sufficient to inhibit IL-1Β-stimulated ANF expression. In contrast, simultaneous inhibition of both ERK and p38MAPK was required to ablate the hypertrophic morphology of cardiac myocytes treated with IL-1Β. These results demonstrated differential signaling from the MAPK isoforms in regulating the gene expression and morphological components of cardiac hypertrophy. In addition, it was revealed that IL-1Β treatment resulted in a delayed response (>60 min) in STAT3α tyrosine phosphorylation, which was subsequently shown to require the initial rapid activation of either ERK or p38MAPK. IL-1Β-stimulated STAT3 phosphorylation was also dependent on the de novo synthesis of secondary signaling molecules. The ablation of the STAT3 tyrosine phosphorylation by the inhibition of ERK or p38MAPK activity, correlated with the attenuation of IL-1Β-stimulated ANF expression, suggesting that signaling through STAT3α may be involved in regulating gene expression associated with IL-1Β cardiac hypertrophy
50
Coldefy, Maurin Anne-Sophie. "Implication des voies de signalisation des MAPK, ERK1/2 et p38, dans la dystrophie myotonique de type 1 (DM1)." Nice, 2006. http://www.theses.fr/2006NICE4059.
Full textAbstract:
Au cours de nos travaux de recherche, nous nous sommes principalement intéressés aux implications des voies de signalisation ERK1/2 et p38 dans la dystrophie myotonique de type ou DM1. La DM1 est la dystrophie musculaire la plus fréquente chez l’adulte. Cette pathologie multi-systémique atteint particulièrement les muscles squelettiques (myotonie, fonte musculaire progressive, altération de la différenciation musculaire). La DM1 est une maladie génétique à transmission autosomale dominante. Le défaut génétique est une insertion de triplets nucléotidiques CTG dans la région 3' non traduite du gène DMPK. Ce gène code pour une sérine/thréonine kinase, dont la fonction reste inconnue à ce jour. Les voies de signalisation des MAPK ERK1/2 et p38 jouent un rôle essentiel dans la transduction du signal et régulent de nombreuses fonctions cellulaires, notamment la différenciation musculaire. Nous avons montré que l'activation de ERK1/2 et p38 est significativement diminuée dans des biopsies de patients DM1. D’après nos études réalisées sur des souris transgéniques sur-exprimant ou invalidées pour le gène Dmpk, la diminution de l'activation de ERK1/2 et p38 ne semble pas corrélée à une diminution de l’expression de DMPK dans la DM1. Cependant, dans des cellules C2C12 exprimant des répétitions CUG en aval du gène de la GFP, l'activation de ERK1/2 et p38 est également diminuée. Ainsi, l’expression de transcrits contenant des triplets CUG répétés pourrait altérer l’activation des MAPK, ERK1/2 et p38, que nous avons observée dans la DM1. A ce jour, nous n’avons pu conclure sur un mécanisme précis d’altération des activations de ERK1/2 et p38 dans la DM1. Néanmoins, les outils que nous avons développés récemment et l’ensemble de nos résultats ouvrent de nouvelles perspectives pour une meilleure compréhension de l’implication des MAPK ERK1/2 et p38 dans la DM1, mais également de la régulation de Dmpk au cours de la différenciation musculaire<br>The aim of this work was to characterize a putative role of ERK1/2 and p38 MAPK in the myotonic dystrophy 1, called DM1. DM1, the most frequent dystrophy in adults, is a multi-systemic disorder which mainly affects skeletal muscles (myotonia, progressive wasting and weakness, delay in muscular differentiation). DM1 is an autosomal dominant inherited disease. The genetic mutation is an expansion of CTG trinucleotide repeats tract in the DMPK 3’ untranslated region. DMPK encodes a serine/threonine kinase but its function is still unknown. ERK1/2 and p38 MAPK signalling pathways play central and essential roles in cells physiology and are implicated in various cellular processes including muscular differentiation. We show that ERK1/2 and p38 activation is significantly diminished in muscular biopsies from DM1 patients. This diminished activation is not correlated with a diminution of DMPK expression in DM1, as we observed in transgenic mice, Dmpk knock-out or DMPK over-expressing mice. However, in C2C12 cells expressing CUG repeats in 3’ UTR of GFP, ERK1/2 and p38 activation is altered. In DM1, the diminution of ERK1/2 and p38 activation could be due to the expression of CUG repeats tract rather than to the decrease of DMPK expression. Our results and our recently developed molecular tools will enable us to further understand the implication of ERK1/2 and p38 MAPK in DM1 as well as Dmpk function in muscular differentiation