Dissertations / Theses: 'MAPS pathway'

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Eglen, Stephen. "Modelling the development of the retinogeniculate pathway." Thesis, University of Sussex, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360522.

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Momin, Amin Altaf. "Application of bioinformatics in studies of sphingolipid biosynthesis." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34842.

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The studies in this dissertation demonstrate that the gene expression pathway maps are useful tools to notice alteration in different branches of sphingolipid biosynthesis pathway based on microarray and other transcriptomic analysis. To facilitate the integrative analysis of gene expression and sphingolipid amounts, updated pathway maps were prepared using an open access visualization tool, Pathvisio v1.1. The datasets were formatted using Perl scripts and visualized with the aid of color coded pathway diagrams. Comparative analysis of transcriptomics and sphingolipid alterations from experimental studies and published literature revealed 72.8 % correlation between mRNA and sphingolipid differences (p-value < 0.0001 by the Fisher's exact test).The high correlation between gene expression differences and sphingolipid alterations highlights the application of this tool to evaluate molecular changes associate with sphingolipid alterations as well as predict differences in specific metabolites that can be experimentally verified using sensitive approaches such as mass spectrometry. In addition, bioinformatics sequence analysis was used to identify transcripts for sphingolipid biosynthesis enzyme 3-ketosphinganine reductase, and homology modeling studies helped in the evaluation of a cell line defective in sphingolipid metabolism due to mutation in the enzyme serine palmitoyltransferase, the first enzyme of de novo biosynthesis pathway. Hence, the combination of different bioinformatics approaches, including protein and DNA sequence analysis, structure modeling and pathway diagrams can provide valuable inputs for biochemical and molecular studies of sphingolipid metabolism.

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Grieco, Luca. "Modélisation et analyse des dérégulations tumorales du réseau MAPK chez l'homme." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4011.

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Le réseau des MAPK est composé de pathways de signalisation fermement entrecroisés impliqués dans le cancer. Toutefois, les mécanismes précis qui sous-tendent son influence sur l'équilibre entre la prolifération et la mort cellulaire demeurent insaisissablesDes données publiques ont été intégrés dans une carte de réactions détaillée, représentant l'influence du réseau des MAPKs sur la décision du destin cellulaire. Cette carte a ensuite été utilisée pour des analyses informatiques spécifiquesTout d'abord, les dynamiques du réseau des MAPKs dans les cancers de la vessie ont été analysés.Un modèle Booléen a été construit, représentant la réponse du réseau aux inputs d'intérêt.Les résultats de simulations systématiques ont été trouvés globalement cohérents avec des données publiques, et ont permis de déchiffrer les principaux événements qui sous-tendent les différents comportements observés dans le cancerEnsuite, la carte a été exploitée pour réanalyser des données publiques d'expression de gènes, avec l'objectif d'identifier les principaux acteurs de la transduction des signaux prolifératifs, dans des types cellulaires spécifiques.Des analyses du réseaux et des calculs statistiques ont conduit à l'identification de régions dérégulées dans le réseau des MAPKs, et à la délinéation de points d'intervention optimales dans cinq stades du cancer de la vessie et dans quatre sous-types de lymphome TL'ensemble de ces résultats a conduit à la formulation de nouvelles hypothèses concernant le fonctionnement du réseau des MAPKs dans différents états pathologiques, et à la sélection de composants cibles qui pourraient être envisagées pour le développement de nouveaux traitements
MAPK network consists of tightly interconnected signalling pathways. Although several studies established the involvement of this network in cancer deregulations, the precise mechanisms underlying its influence on the balance between cell proliferation and death remain elusive.Public data were integrated into a detailed reaction map, accounting for the influence of MAPK network on cell fate decision. This map was then used for computational analyses addressing specific cancer-related questions.First, the dynamics of MAPK network in bladder cancers were analysed. A Boolean model was built, accounting for the response of the network to selected inputs. The results of systematic simulations were found globally coherent with published data. Based on in silico experiments, the main events underlying different observed cancer cell behaviours were then deciphered.Next, the MAPK reaction map was exploited to reanalyse public high-throughput gene expression data. The goal was to identify key actors for the transduction of proliferative signals, in specific cell types. Network analyses and statistical computations led to the identification of deregulated MAPK network regions, and to the delineation of optimal intervention points aimed at blocking the proliferative signals transduced from such regions. This approach was used to study five different tumour stages and four different subtypes of T-cell lymphoma.Altogether, these results led to the formulation of novel hypotheses concerning the functioning of MAPK network in different pathological conditions, and to the selection of target components that might be considered for the development of novel treatments

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Reppucci, Christina Jean. "The functional forebrain circuitry of fear-cue inhibited feeding in food-deprived rats: Evidence from complementary pathway tracing and Fos induction maps studies." Thesis, Boston College, 2015. http://hdl.handle.net/2345/bc-ir:104569.

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Thesis advisor: Gorica D. Petrovich
The drive to eat, like most motivated behaviors, is controlled by both intrinsic signals from the body as well as extrinsic signals from the environment. Although these factors often act in concert, in some instances environmental cues can override the body’s homeostatic signals. Prior work investigating the ability of learned cues to promote overeating in the absence of hunger identified a critical forebrain network composed of the amygdala, medial prefrontal cortex (mPFC), and lateral hypothalamus (LHA). We hypothesized that a similar forebrain network may also be critical when learned fear-cues inhibit eating despite hunger. The amygdala, mPFC and LHA are each anatomically and functionally positioned to influence feeding, and evidence suggests they could work together to support the fear-cue’s ability to inhibit feeding by overriding homeostatic hunger signals triggered by food-deprivation. Prior anatomical work identified direct pathways between these three large, heterogeneous regions; however, less is known about the organization of the underlying circuitries, especially between distinct nuclei and/or subdivisions that comprise these structures. Study 1 used a dual retrograde tract tracing design to map the topographical organization of the connections between the amygdala, mPFC, and LHA in detail, and to determine whether amygdalar pathways to the mPFC and to LHA originated from the same or different neurons. We found evidence for multiple, topographically organized, direct pathways from the amygdala to the LHA, and separate pathways from the amygdala to areas of the mPFC that send direct projections to the LHA. Importantly, nearly all amygdalar projections to the mPFC and to the LHA originated from different neurons, suggesting that amygdala and amygdala-mPFC processing influence the LHA independently. Study 2 used immediate early gene induction to map the patterns of functional activation within this amygdala-prefrontal-lateral hypothalamic network during the expression of fear-cue inhibited feeding behavior, and to assess whether these patterns were similar in males and females. We found differential activation across the network, and activation patterns related to the presentation of fear-cues, the presence of food-related cues, and the amount of food consumed were associated within distinct cell groups in the amygdala, mPFC, and LHA. Together, the studies presented in this dissertation provide anatomical and functional maps for future interrogation of the circuitry underlying fear-cue inhibited feeding
Thesis (PhD) — Boston College, 2015
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Psychology

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Jost, Mousseau Coline. "Propagation et toxicité de la superoxide dismutase 1 dans la Sclérose Latérale Amyotrophique modélisée par des neurones moteurs dérivés de cellules souches pluripotentes induites." Electronic Thesis or Diss., Sorbonne université, 2024. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2024SORUS275.pdf.

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La sclérose latérale amyotrophique (SLA) est une maladie neurodégénérative rapidement fatale et sans traitement curatif, qui entraîne la mort des neurones moteurs (MN) via des mécanismes encore mal identifiés. La dégénérescence des MN provoque une paralysie progressive, qui débute localement avant d'atteindre l'ensemble des muscles squelettiques. La progression de la paralysie ne semble pas suivre un schéma aléatoire, mais se propage en suivant le tractus nerveux. On peut donc faire l'hypothèse que la mort des MN pourrait impliquer la propagation de déterminants pathologiques toxiques. Parmi les nombreux gènes causaux de la SLA, il a été montré que plusieurs d'entre eux codent pour des protéines ayant un domaine ou des propriétés prion-like. C'est le cas du gène codant pour la superoxyde dismutase 1 (SOD1), qui est la deuxième cause génétique de SLA. Il a été montré que des mutations de SOD1 engendraient la formation de protéines mal repliées (misSOD1), capables de transmettre leur mauvaise conformation à d'autres protéines SOD1. Cependant, à ce jour, il n'existe aucune étude sur la sécrétion de SOD1 et misSOD1 dans des MN humains et dans un contexte proche des conditions physiologiques des patients. Ainsi, mes travaux de thèse ont eu pour objectif d'étudier l'expression et la sécrétion des protéines SOD1 dans des MN dérivés de cellules souches pluripotentes induites (iPSC) de sujets contrôles et de patients mutés SOD1, et d'analyser les voies possibles de la sécrétion de ces protéines. Dans un premier temps, j'ai différencié des iPSC en MN spinaux et j'ai montré que misSOD1 s'accumulait dans les MN mutants. J'ai ensuite montré que SOD1 était sécrétée à la fois par des MN contrôles et des MN mutés, mais la voie classique médiée par le réticulum endoplasmique et l'appareil de Golgi ne semblait pas impliquée. J'ai aussi observé que les MN sécrétaient des exosomes mais que ceux-ci ne contenaient apparemment pas SOD1. Dans un second temps, je me suis intéressée à une voie de sécrétion non conventionnelle spécifique aux protéines mal repliées : la voie MAPS (Misfolded-Associated Protein Secretion), majoritairement étudiée dans la sécrétion de l'α-synucléine. Cette voie est initiée par la deubiquitinase USP19 qui redirige les protéines mal repliées destinées à une dégradation protéasome par déubiquitination. La protéine chaperonne DNAJC5 forme ensuite des cargos avec les protéines déubiquitinées, qui sont alors dirigés par l'intermédiaire de différents organites, vers la membrane pour être sécrétés. J'ai montré que misSOD1 colocalisait avec DNAJC5 dans les MN SOD1 mutés, suggérant un rôle de la voie MAPS dans la sécrétion de SOD1. Pour confirmer cela, des vecteurs lentiviraux ont été produits pour transduire les MN et moduler l'expression de USP19. La surexpression de USP19 n'a pas affecté les colocalisations misSOD1-DNAJC5, tandis que sa diminution a réduit le nombre de colocalisations. En réalisant une analyse transcriptomique sur les MN transduits, j'ai observé que seulement 30 gènes étaient dérégulés lors de la surexpression de USP19. Cependant, en diminuant USP19, plus de 3000 gènes étaient dérégulés et sept voies étaient significativement dérégulées dont la voie de sécrétion protéique, suggérant l'importance de USP19 dans cette voie. Les perspectives de cette étude incluent d'explorer la propagation de la misSOD1 dans des cocultures entre des MN contrôles et mutants, pour investiguer l'importance de USP19 et de la voie MAPS dans la propagation. En conclusion, mes travaux ont montré que SOD1 était sécrétée par des MN de patients mutés SOD1 et que la voie MAPS pourrait être impliquée pour que les MN en souffrance se débarrassent des protéines mal repliées. Pouvoir moduler la sécrétion de SOD1 pourrait représenter une cible thérapeutique prometteuse pour ralentir la progression de la SLA, mais un équilibre devra être trouvé pour permettre de limiter à la fois la toxicité intracellulaire et la propagation des protéines toxiques
Amyotrophic lateral sclerosis (ALS) is a rapidly fatal neurodegenerative disease with no curative treatment, leading to the death of motor neurons (MN) through mechanisms that are still poorly understood. The degeneration of MN causes progressive paralysis, which begins focally before affecting all skeletal muscles. The progression of paralysis does not follow a random pattern but spreads along the nerve tract. Therefore, it can be hypothesized that the death of MN could involve the propagation of toxic pathological determinants from one cell to another.Among the many causal genes of ALS, several have been shown to code for proteins with a prion-like domain or properties. This is the case for the gene coding for superoxide dismutase 1 (SOD1), which is the second most common genetic cause of ALS. It has been demonstrated that mutations in SOD1 result in misfolded proteins (misSOD1) capable of transmitting their misfolded conformation to other SOD1 proteins. However, to date, there are no studies on the secretion of SOD1 and misSOD1 in MN under conditions close to the physiological context of patients. Therefore, the aim of my thesis work was to study the expression and secretion of SOD1 and misSOD1 in MN derived from induced pluripotent stem cells (iPSCs) from control subjects and SOD1-mutated patients and to analyze the possible pathways of these proteins' secretion. First, I differentiated iPSCs into spinal MN and showed that misSOD1 accumulated in mutant MN. I then showed that SOD1 was secreted by both control and mutant MN, but the classical pathway mediated by the endoplasmic reticulum and Golgi apparatus did not seem to be involved. I also observed that MN secreted exosomes, but they apparently did not contain SOD1. In the second phase, I focused on an unconventional secretion pathway specific to misfolded proteins: the MAPS pathway (Misfolded-Associated Protein Secretion), which has mainly been studied in the context of α-synuclein secretion. This pathway is initiated by the deubiquitinase USP19, which redirects misfolded proteins destined for proteasomal degradation by deubiquitination. The chaperone protein DNAJC5 then forms cargos with the deubiquitinated proteins, which are progressively directed via different organelles to the membrane for secretion. I showed that misSOD1 colocalized with the DNAJC5 protein in SOD1 mutant MN, suggesting a role for the MAPS pathway in SOD1 secretion. To confirm this, lentiviral vectors were produced to transduce the MN and modulate USP19 expression. Overexpression of USP19 did not change the number of colocalizations between misSOD1 and DNAJC5; however, decreasing USP19 reduced these colocalizations, suggesting the involvement of the MAPS pathway in misSOD1 secretion. By performing RNA sequencing on transduced MN, I observed that only 30 genes were deregulated with USP19 overexpression. However, with USP19 downregulation, 1758 and 1410 genes were respectively upregulated and downregulated. Seven pathways were significantly deregulated, including the protein secretion pathway, suggesting the importance of USP19 in protein secretion. The perspectives of this study include exploring the propagation of misSOD1 in cocultures between control and mutant MN to investigate the importance of USP19 and the MAPS pathway in propagation. In conclusion, my work has shown that SOD1 is secreted by MN from SOD1-mutated patients and that traditional secretion pathways are not involved, in contrast to the MAPS pathway. Therefore, the ability to modulate SOD1 secretion could represent a promising therapeutic target for slowing the progression of ALS

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Maddison, Louise. "Experimental and theoretical modelling of the MAPK pathway." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/experimental-and-theoretical-modelling-of-the-mapk-pathway(46773da5-85dd-4a3f-8e6c-e3559ba04f46).html.

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The MAPK pathway plays a crucial role in regulating cellular response to external stimuli. Binding of growth factors and other mitogenic signals to cell surface receptors initiates a phosphorylation-dependent relay of protein activation, resulting in altered transcription, ultimately regulating cell proliferation and differentiation. Signalling through this pathway is regulated by the coordinated function of specific protein kinases and protein phosphatases. As perturbation of this signalling system is often associated with diseases such as cancer, modelling is a useful means to help understand the outcomes that may result following changes in component levels or activity. The determination of absolute quantification data, in copies per cell, for proteins of the MAPK pathway will allow the expansion of and improved accuracy within predictive models. The strategy used within this thesis is based on the established technique of stable isotope dilution, generating isotopically labelled peptides using the QconCAT methodology. Recombinant DNA techniques were used to generate artificial concatamers of large numbers of tryptic peptides as quantification standards. A QconCAT, LM1, of 49 KDa (29 tryptic peptides), corresponding to the scaffold proteins was designed and built to encode two peptides per protein. A second QconCAT, LM2, of 58 KDa (34 tryptic peptides), encoded peptides from the dual-specificity phosphatases (DUSPs) and substrates. Quantification was performed using ultra performance liquid chromatography coupled to mass spectrometry. A selected reaction monitoring (SRM) approach was employed where the most intense y-ions per peptide were selected either from experimental data or predictions in silico. Using the ratio of the signal for the light:heavy isotopologues, the amount of light isotopologue can be inferred, allowing copies per cell quantifications to be established. Native peptides were present below the lower limit of quantification, and therefore the upper bounds of copies per cell were obtained for the three cell lines; colon cancer cells HCT 116 (K-Ras mutant) and HT-29 (B-Raf mutant) and a control cell line of HEK-293. Finally, mathematical modelling was undertaken to explore the mass-action kinetics of a three component scaffold signalling molecule. It was found that the optimal scaffold concentration is between the lowest and second lowest concentration of signalling protein.

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Cabrerizo, Benito Yolanda. "Studies on a PKC-PLD-MAPK pathway." Thesis, University College London (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399767.

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Kotwaliwale, Ashwin. "Frameworks for Modeling MAPK Pathways." Thesis, Open University, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520778.

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Rui, Hongliang. "Regulation of MAPK/JNK signaling pathway and TGF-beta signaling pathway by axin /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?BICH%202004%20RUI.

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Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2004.
CD-ROM contains electronic versons of the thesis in pdf and word format. Includes bibliographical references (leaves 129-151). Also available in electronic version. Access restricted to campus users.

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Anastasaki, Korina. "MAPK pathway : a role in development, disease and behaviour." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5955.

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Mutations in the RAS-RAF-MEK-ERK (MAPK) pathway give rise to a range of developmental disorders collectively referred to as the RASopathies. De novo germline mutations in patients suffering from these syndromes promote similar phenotypes, which include heart abnormalities, characteristic facial features, cutaneous malformations, gastrointestinal malfunctions, failure to thrive and a spectrum of mental retardation. Although many RASopathies patients show a propensity to develop early-onset benign and malignant tumours, Cardio-faciocutaneous (CFC) syndrome patients do not seem to share this predisposition, with the exception of an increased number of naevi. CFC syndrome is caused by mutations in BRAF, MEK1 or MEK2, with the majority of patients harbouring BRAF mutations. Intriguingly, both kinase-activating and kinase-impaired mutations have been identified in CFC patients. Here, I use the zebrafish system to address the activity of the CFC syndrome alleles and the MAPK pathway in a developmental context and test the potential of small molecule inhibitors to restore normal development. I established an assay for the activity of CFC, melanoma and engineered BRAF and MEK human mutated alleles in vivo. Using zebrafish as an animal model organism, a panel of 31 mutant and wild-type BRAF, MEK1 and MEK2 alleles were expressed in early zebrafish embryos to assess their role in development. Irrespective of the predicted kinase activity, all embryos expressing BRAF and MEK mutant alleles reproducibly manifested the cell movement phenotype during gastrulation. Consistent with aberrant fibroblast growth factor (FGF) signalling and defective gastrulation, in situ hybridisation against convergence-extension markers showed misregulated convergence-extension movement patterns in CFC zebrafish embryos. Finally, I performed whole embryo RNA expression microarrays to identify genes regulated downstream of the CFC mutations, and I discuss the potential for a possible link to some of the phenotypes associated with a CFC zebrafish model. I established that the CFC, BRAF and MEK mutant embryos are sensitive to inhibition of MEK signalling by small molecules. Importantly, a time-window of treatment was identified which was sufficient to restore normal gastrulation movements and to prevent the developmental side effects promoted by the inhibitors at later stages of development. In order to begin considering the therapeutic potential of small molecules in developmental disorders (at least in our model system), the effect of low concentrations of the inhibitors in the normal formation of diverse tissues was thoroughly examined during zebrafish development. From these studies, I identified a concentration of MEK inhibitor that could be administered in a continuous fashion to prevent CFC-associated cell movement defects during gastrulation, without additional later developmental defects. Finally, I addressed the role of MEK-ERK signalling in a specific behavioural phenotype in zebrafish. Many RASopathies patients suffer from mental retardation and experience learning and attention difficulties. Research in our laboratory has identified a novel zebrafish behaviour induced by enhanced cAMP signalling, where the zebrafish seek shaded areas in their environment and exhibit frequent defensive shoaling behaviour. I used western blotting to establish that enhanced cAMP signalling activates the MAPK signalling pathway and, in collaboration with members our laboratory, that this phenotype can be suppressed by administration of the PD325901 MEK inhibitor. While we do not yet know the effect of CFC syndrome mutations on this behaviour, we suggest that altered MEK-ERK signalling may underlie important features of vertebrate behaviour.

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Sutton, Katrina Maria. "Regulation of HIF-1 by MAPK pathway and phosphorylation." Thesis, Institute of Cancer Research (University Of London), 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416446.

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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.

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Gurgis, Fadi. "Targeting the p38 MAPK-MK2 pathway for glioblastoma therapy." Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/15943.

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Glioblastoma is the most lethal and prevalent form of brain cancer. Its therapy is not only limited in its choices but also in extending life expectancies of patients. Identification of genetic aberrations driving tumour growth and progression have leveraged our understanding of the inherent complexity of this cancer. Cell cycle dysregulation, apoptotic resistance and inflammatory tumour microenvironment have emerged as key processes that surmount glioblastoma therapy success. Due to their vast involvement in hallmark phenotypes of tumour biology, kinases are becoming important drug targets in oncology. The p38 mitogen-activated protein kinase (MAPK) and its downstream MAPK-activated protein kinase 2 (MK2) regulate a myriad of signalling pathways influencing inflammation, cell death, differentiation and motility that allow cells to respond to external cues. Recent evidence suggests that these kinases could contribute to tumourigenesis and chemotherapy resistance. This thesis aims to investigate whether targeting the p38 MAPK-MK2 pathway is a viable therapeutic approach for glioblastoma therapy and to elucidate the contribution of these kinases to pathophysiology of the disease. Data presented herein describes how MK2 mediates EGFRvIII oncogene-induced inflammation. Opposing roles of p38 MAPK and MK2 in cell cycle progression and survival of glioblastoma cells are revealed for the first time with important implications for temozolomide chemotherapy response. Moreover, we provide evidence that selective targeting of MK2 is a promising strategy to circumvent the pro-tumourigenic contribution of this pathway in glioblastoma. Finally, this thesis discloses in vitro characterisation of commercially available MK2 inhibitor denoted CMPD1 and highlights the importance of target validation for kinase inhibitors before advancing to clinical/research settings. Structural analogues of CMPD1 with potential for glioblastoma therapy have been identified.

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Konieczkowski, David Joseph. "Systematic approaches to overcoming limitations of MAPK pathway inhibition in melanoma." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:11094.

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Metastatic melanoma is an aggressive, incurable cancer with historically few therapeutic options. The discovery that 60% of melanomas harbor the oncogenic BRAF_V600E mutation, which constitutively activates the MAPK pathway, has provided a promising new therapeutic axis. Although MAPK pathway inhibitor therapy has shown striking clinical results in BRAF_V600-mutant melanoma, this approach faces three limitations. First, 10-20% of BRAF_V600-mutant melanomas never achieve meaningful response to MAPK pathway inhibitor therapy (intrinsic resistance). Second, among BRAF_V600-mutant melanomas initially responding to MAPK pathway inhibitor therapy, relapse is universal (acquired resistance). Third, approximately 40% of melanomas lack BRAF_V600 mutations and so are not currently candidates for MAPK pathway inhibitor therapy. We sought to address each of these problems: by characterizing the phenomenon of intrinsic MAPK pathway inhibitor resistance, by finding ways to perturb mechanisms of acquired MAPK pathway inhibitor resistance, and by identifying novel dependencies in melanoma outside of the MAPK pathway. Intriguingly, the NF-kappa B pathway emerged as a common theme across these investigations. In particular, we establish that MAPK pathway inhibitor sensitive and resistant melanomas display distinct transcriptional signatures. Unlike most BRAF_V600-mutant melanomas, which highly express the melanocytic lineage transcription factor MITF, MAPK pathway inhibitor resistant lines display low MITF expression but high levels of NF-kappa B signaling. These divergent transcriptional states, which arise in melanocytes from aberrant MAPK pathway activation by BRAF_V600E, remain plastic and mutually antagonistic in established melanomas. Together, these results characterize a dichotomy between MITF and NF-kappa B cellular states as a determinant of intrinsic sensitivity versus resistance to MAPK pathway inhibitors in BRAF_V600-mutant melanoma. In separate investigations, we have shown that, NFKB1 p105, a member of the NF-kappa B family, intimately regulates levels of COT, a known effector of resistance to MAPK pathway inhibitors. Moreover, we have used shRNA screening to nominate particular nodes within the NF-kappa B pathway, including MYD88 and IRF3, as candidate melanoma lineage-specific dependencies. Cumulatively, although these studies use diverse approaches to investigate the limitations of MAPK pathway inhibitor therapy in melanoma, they converge in nominating the NF-kappa B pathway as a previously underappreciated feature of melanoma biology and suggest the relevance of this pathway for future investigation.

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Wang, Belinda. "Mechanisms of Resistance to MAPK Pathway Inhibition in RAS-Mutant Cancers." Thesis, Harvard University, 2016. http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493475.

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The RAS family of genes are among the most frequently mutated genes in human cancers, including nearly all pancreatic cancers, ~40% of colorectal cancers, and ~30% of lung cancers. Although most RAS-mutant cancers depend on RAS signaling for proliferation and survival, direct RAS inhibitors have not yet been developed for clinical use. An alternative approach to treating RAS-mutant cancers is to inhibit RAS effector pathways, such as the RAS-RAF-MEK-ERK (MAPK) pathway. However, while some patients with RAS-mutant cancers benefit clinically from MAPK pathway inhibition (MAPKi), most do not respond to this regimen. Moreover, of the patients who do respond, nearly all progress to secondary therapeutic resistance. In this work, we applied systematic gain- and loss-of-function (GOF and LOF) screening approaches to identify modifiers of MAPK pathway dependence. Using RAS- or BRAF-mutant pancreatic and lung cancer cell lines, we performed a genome scale open reading frame (ORF) screen and six genome scale CRISPR-Cas9 knockout screens to investigate mechanisms of resistance to MEK or BRAF inhibition. We found that the most potent GOF mediators of resistance were overexpression of components of the RTK-RAS-MAPK pathway, which restored MAPK signaling. Contrastingly, the majority of LOF events that mediated resistance to MAPKi were not direct regulators or effectors of the MAPK pathway. From our LOF screens, we identified KEAP1 and CIC as generalizable modulators of resistance to MAPKi in RAS-mutant cancers. We found that KEAP1 deletion mediates resistance through mechanisms orthogonal to the MAPK pathway, such as reducing oxidative stress and promoting anabolic metabolism. Conversely, CIC loss promotes resistance by partially restoring the transcriptional pathway downstream of ERK. Understanding mechanisms of intrinsic resistance can enable the identification of predictive biomarkers that improve patient selection for targeted therapy. In addition, identifying mechanisms of acquired resistance can inform the development of novel agents or combination therapy strategies. Our studies highlight the ability of systematic and comprehensive in vitro functional screens to identify clinically relevant mediators of resistance and to provide novel insights into well-studied pathways. While we selected specific genes for detailed mechanistic studies, other genes that were identified from our screens may contribute additional biological insights.
Medical Sciences

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Vergani, E. "BRAF AND MAPK PATHWAY MOLECULES FOR TARGETED THERAPY OF MALIGNANT MELANOMA." Doctoral thesis, Università degli Studi di Milano, 2012. http://hdl.handle.net/2434/173422.

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The clinical activity of the BRAF inhibitor PLX4032 (vemurafenib) in patients with BRAFV600E mutant melanoma is limited primarily by the development of resistance leading to tumor progression. Strategies to overcome primary and acquired resistance are required. In a panel of 27 genetically characterized patient-derived melanoma cell lines the sensitivity to PLX4032 was dependent on BRAFV600E and independent from other gene alterations that commonly occur in melanoma, such as CDKN2A, and mutations of TP53, PTEN loss, and BRAF and MITF gene amplification. To investigate the molecular basis underlying acquired resistance to BRAF inhibitor, PLX4032-resistant cells were derived from a high sensitive BRAFV600E melanoma cell line, and used as a model. The resistant variant line showed increased AKT and ERK phosphorylation and enhanced IGF-1R/PI3K signaling. Combined treatment with PLX4032 plus PI3K inhibitors resulted in significant cell growth inhibition by decreasing pAKT and pERK signaling. To explore molecular mechanisms underlying primary resistance two melanoma cell lines lacking sensitivity to PLX4032 were used as models. Resistance to PLX4032 was maintained after CRAF down-regulation by siRNA, indicating that CRAF is not involved in the activation of ERK in the resistant cell lines. Treatment with the MEK inhibitor UO126 inhibited cell growth and decreased ERK phosphorylation indicating alternative activation of MEK-ERK signaling. Genetic characterization by MLPA and analysis of pTyr signaling by MALDI-TOF mass spectrometry revealed the activation of MET and SRC signaling, associated with the amplification of MET and of CTNNB1 and CCND1 genes, respectively. Testing of co-inhibition of the MET, SRC and MAPK signaling pathways by the combined treatment with the MET inhibitor, SU11274 or the SRC inhibitor, BMS-354825 plus PLX4032 resulted in a significant inhibitory effect on melanoma cell proliferation, survival, migration and invasive capacity. These results support combinatorial approaches targeting MAPK pathway at different nodes and intercepting parallel signal transduction pathways as a strategy to override resistance to BRAF inhibitors.

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Åhlin, Mikaela. "Role of MKP-2 in crosstalk between MAPK pathways." Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-261777.

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Abnormalities in Mitogen Activated Protein Kinase (MAPK) signalling may affect the cells essential processes and influence the cell in acquiring traits to favour tumorigenic transformation and the progression of cancer. Deregulation of the MAPK pathways and uncontrolled crosstalk occurring in cancers may be caused by deregulation by MAP-kinase phosphatases (MKPs) that negatively regulates MAPKs by dephosphorylation. In this study, we were interested in the role of MKP-2 in MAPK-signalling pathways. MKP-2 is known to specifically dephosphorylate the MAP kinases Erk1/2, p38 and JNK. In this study, I was to elucidate key events leading to MKP-2 expression and the role of MKP-2 in regulating and balancing MAPK signaling. Also, I was to analyse the possible involvement of p53 in the deregulation of the MAPK pathways and its correlation with MKP-2 expression. In this report, I suggest a model where the Erk1/2 pathway in conjugation with p53 promote MKP-2 expression. I have also discovered a crosstalk between two different MAPK pathways, i.e between Erk1/2 and Erk5.

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18

Robins, Stephanie. "The p38 MAPK pathway in human airway smooth muscle: roles in asthma." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97233.

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The mitogen activated protein kinase (MAPK) signaling pathways play key roles in mediating inflammatory responses. Asthma is a disease characterized by excessive inflammation and the mainstay of treatment is the use of glucocorticoids which, among other effects, control the activity of p38 MAPK. Human airway smooth muscle (HASM) cells contribute to the pathology of asthma as they regulate bronchomotor tone, proliferate, migrate and secrete inflammatory cytokines. I investigated these processes in HASM using MAPK inhibitors and the glucocorticoid dexamethasone. Following TNFα stimulation, HASM cell production of GM-CSF, IL-1β, IL-33 and CXCL8 were ERK1/ERK2 dependent; all but CXCL8 were diminished by dexamethasone. Neutrophil migration in response to conditioned media from HASM cells was also ERK1/ERK2 dependent. CXCL12 displayed chemotactic activity for HASM which was shown to express the CXCR4 receptor. HASM migration was partially p38 MAPK dependent. These results highlight the potential for important and divergent roles for the MAPKs in HASM in refractory asthma.
L'asthme est une maladie inflammatoire dont les glucocorticoïdes constituent le principal traitement via le contrôle de la voie p38 MAPK. Les cellules musculaires lisses bronchiques (CLM) jouent un rôle clé dans la physiopathologie de l'asthme notamment dans le remodelage des voies aériennes via leur capacité à proliférer, migrer et sécréter des médiateurs inflammatoires. La stimulation des CLM avec du TNFα entraine une activation des voies MAPK ERK et p38, induisant l'expression des gènes GM-CSF, IL-1β, IL-33 et CXCL8. L'activation de la voie MAPK ERK est importante dans la migration des neutrophiles exposée à du milieu conditionné provenant de CLM stimulées par TNFα via son rôle sur l'expression de CXCL8. En contrepartie, la voie p38 MAPK joue un rôle important dans la migration des CLM en réponse à CXCL12, un chimiokine élevée dans les bronches de patients asthmatiques. Ces résultats ont mis en évidence un rôle important et divergeant des MAPKs dans les CLM dans la pathophysiologie de l'asthme sevère.

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19

Chetty, Vasu Nephi. "Necessary and Sufficient Informativity Conditions for Robust Network Reconstruction Using Dynamical Structure Functions." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3810.

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Dynamical structure functions were developed as a partial structure representation of linear time-invariant systems to be used in the reconstruction of biological networks. Dynamical structure functions contain more information about structure than a system's transfer function, while requiring less a priori information for reconstruction than the complete computational structure associated with the state space realization. Early sufficient conditions for network reconstruction with dynamical structure functions severely restricted the possible applications of the reconstruction process to networks where each input independently controls a measured state. The first contribution of this thesis is to extend the previously established sufficient conditions to incorporate both necessary and sufficient conditions for reconstruction. These new conditions allow for the reconstruction of a larger number of networks, even networks where independent control of measured states is not possible. The second contribution of this thesis is to extend the robust reconstruction algorithm to all reconstructible networks. This extension is important because it allows for the reconstruction of networks from real data, where noise is present in the measurements of the system. The third contribution of this thesis is a Matlab toolbox that implements the robust reconstruction algorithm discussed above. The Matlab toolbox takes in input-output data from simulations or real-life perturbation experiments and returns the proposed Boolean structure of the network. The final contribution of this thesis is to increase the applicability of dynamical structure functions to more than just biological networks by applying our reconstruction method to wireless communication networks. The reconstruction of wireless networks produces a dynamic interference map that can be used to improve network performance or interpret changes of link rates in terms of changes in network structure, enabling novel anomaly detection and security schemes.

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20

Hong, Xinyang. "The balancing effect between MAPK and NFκB pathways for the transcriptional regulation of Toll-like receptors." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:a9d64615-68b1-46eb-a2d3-4eb8d1827a27.

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Toll-like receptors (TLR) are a family of pattern recognition receptors crucial for pathogen pattern recognition. Upon activation, TLRs induce innate immune responses such as cytokine production. However irregular TLR activities can provide fatal, hence fine tuning of the TLR induced responses are necessary. The TLR mediated immune responses are controlled by the positive/negative regulation of TLR signalling pathways, relocation of TLR proteins and modulation of TLR transcription. Systematic analyses of the agonist-induced transcriptional changes of TLRs were shown for the first time in my thesis. In my experiments, I have shown that each agonist induced a unique pattern of TLR transcription. Following PAM stimulation, mRNA levels of the cognate TLR1/2 increased whereas mRNA levels of the cross-regulating TLR4, 7/8/9 reduced in both cell lines and splenic macrophages from different mice strains. Through investigation of the signalling pathways responsible for mediating such TLR transcriptional changes, I then discovered the balancing effect between NFÎoB and MAPK signalling pathways. PAM induced TLR transcriptional changes were controlled by the additive and/or antagonistic interference between MAPK signalling cascades, ERK, JNK, P38 and NFÎoB signalling pathways. This was the first time that signalling synergy between MAPK and NFÎoB pathways were shown. Furthermore, PAM induced transcription of TLR1 and TLR8 may be partially regulated by the indirect feedback mediated by protein production. Importantly, the maintenance of the basal TLR mRNA expression also required activation of both MAPK and NFÎoB signalling pathways. In addition, signalling control for TLR transcription induced by different agonists (PAM vs. LPS) or in different species (chicken vs. mice) was compared. LPS induced transcriptional changes of the cross-regulating TLR1/2 and 3 but not the cognate TLR4 in RAW cells. The LPS induced TLR transcriptional changes required activation of a combination of MAPK and NFÎoB signalling pathways which shared both similarities and differences to the PAM induced signalling activation. In chicken, PAM induced more potent signalling activation, regulating the TLR transcriptional changes at a lower concentration than in mice. Overall, this thesis demonstrates that the transcriptional regulation of TLRs is complex, mediated by the coordination between MAPK and NFÎoB signalling pathways. These studies have significant implications in providing detailed insight of TLR transcriptional regulation which plays an important role in the regulation of TLR mediated innate immune responses. Please watch the following videos that I made for: A short introduction about TLR regulation - https://youtu.be/LTDdEZ3S97o A short explanation about TLR signalling - https://youtu.be/51IY5XhdJR8.

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21

Grossi, Valentina. "The p38alpha MAPK pathway : a key factor in colorectal cancer progression and treatment." Thesis, Open University, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.664279.

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Colorectal cancer (CRC) remains one of the most common malignancies in the world. Development of resistance to conventional therapies is frequently observed in advanced stages of the disease and frequently involves MAPK signaling. Recent studies identified p38a. MAPK as a mediator of resistance to irinotecan and 5-fluorouracil in CRC. Our genetic and pharmacologic studies revealed that p38a is required to maintain CRC cell metabolism, as its inhibition leads to Fox03A activation, autophagy, cell death, and tumor growth reduction both in vitro and in preclinical mouse models. Furthermore, our data show that p38 is activated in response to cisplatin treatment and mediates chemoresistance in HT29-xenografted tumors. MEKl inhibition has been found to reduce CRC cell proliferation in vitro and to decrease tumor growth in xenograft models and we recently reported that MEK-ERKl/2 inhibition is followed by over-activation of the p38 MAPK pathway. We found that p38a and MEK combined inhibition specifically induces apoptosis by enabling TR. Aa signaling propagation through t-Bid and caspase 3, and fosters cell death in CRC cells. Sorafenib is reported to inhibit nine protein kinases, including BRAF, VEGF and the DGF-out conformation state ofp38a. Our results show that the SB202190 (type I p38a inhibitor) and Sorafenib (type II p38a inhibitor) synergize at the molecular and biqlogical level enhancing tumor growth inhibition and induction of apoptosis in CRC both in vitro and in vivo. The combined use of SB202190 and PD0325901 (MEKl inhibitor), Sorafenib or Cisplatin significantly reduced tumor growth by inducing a higher degree of apoptosis compared to each single treatment. Our data validate in vivo the combined inhibition of the p38a. and ERK pathways or their association with chemotherapy as a promising approach to treat CRC. Moreover, they suggest that the phosphorylation status of p38 MAPK may be a marker of resistance in CRC.

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Angevine, Kristine R. "Menin Regulates Oxidative Stress Through Heme Oxygenase-1 and the p38 MAPK Pathway." University of Toledo Health Science Campus / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=mco1352301888.

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23

Sollome, James Jerome. "Heregulin Activates a Novel HER2/HER3-MTK1-GIT1/ERK1/2 MAPK Signaling Pathway." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/315554.

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Human MAP3K4 (MTK1) functions upstream of mitogen activated protein kinases (MAPKs). In the studies presented herein, MTK1 is shown to be required for human epidermal growth factor receptor 2/3 (HER2/HER3)-heregulin beta1 (HRG) induced extracellular acidification and cell migration in MCF-7 breast cancer cells. Furthermore, it was shown that HRG stimulation leads to association of MTK1 with tyrosine phosphorylated HER3 in MCF-7 and T-47D breast cancer cells. The MTK1/HER3 association was dependent on HER2 activation and was decreased by pre-treatment with the HER2 inhibitor, lapatinib. Furthermore, HER2 does not directly associate with MTK1, but phosphorylates HER3 transiently. MTK1 also has a role in the ERK1/2 MAPK signaling pathway in response to heregulin (HRG) stimulation in T-47D and MCF-7 breast cancer cells. In addition to MTK1, Shc, Grb2 and GIT1 proteins are all involved in the ERK1/2 MAPK pathway in response to growth factor stimulation. MTK1 was also shown to associate with activated ERK1/2, GIT1, Shc, Grb2 and p85 of PI3K in response to heregulin stimulation. ERK1/2 kinase activity is involved in aberrant signaling that leads breast cancer progression. GIT1 is a scaffolding protein that is linked to growth factor mediated ERK1/2 signaling in cell migration. Moreover, we also identify the actin interacting region (AIR) on MTK1 and disruption of actin cytoskeletal polymerization with cytochalasin D inhibited the interaction between HER3 and MTK1, indicating that f-actin (which is needed for cell migration) is required for the MTK1/HER3 association. Additionally, HRG stimulation leads to extracellar acidification that is independent of cellular proliferation. HRG induced extracellular acidification is significantly inhibited when MTK1 is knocked down in MCF-7 cells. Similarly, pre-treatment with lapatinib significantly decreased HRG induced extracellular acidification. Extracellular acidification is linked with cancer cell migration. We performed scratch assays that show HRG induced cell migration in MCF-7 cells. Knockdown of MTK1 significantly inhibited HRG induced cell migration. Furthermore, pre-treatment with lapatinib also significantly decreased cell migration. Cell migration is required for cancer cell metastasis, which is the major cause of cancer patient mortality. We identify MTK1 in the HER2/HER3-HRG mediated extracellular acidification and cell migration pathway in breast cancer cells.

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24

Tamburrino, Federica <1980&gt. "I disordini del pathway RAS-MAPK o Rasopatie: aspetti diagnostici, clinici e terapeutici." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7435/4/Tamburrino_Federica_Tesi.pdf.

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Le “RASopatie” includono un gruppo di patologie congenito-malformative a trasmissione autosomica-dominante causate da mutazioni eterozigoti germinali in geni che codificano per proteine del pathway RAS-MAPKinasi. Sono caratterizzate da dismorfismi faciali, iposomia, cardiopatia congenita, anomalie ectodermiche e scheletriche, coinvolgimento cognitivo e suscettibilità tumorale. La bassa statura è uno dei principali elementi distintivi sul quale si può agire sotto il profilo terapeutico, mediante somministrazione di Ormone della Crescita biosintetico (GH). In questo studio è stato analizzato l’andamento accrescitivo in un ampio gruppo di 88 pazienti affetti da Rasopatia con diagnosi molecolare confermata. Sono stati valutati: distribuzione per genotipo, prevalenza delle caratteristiche fenotipiche e correlazione genotipo-fenotipo sull’intero gruppo di studio ed in particolare andamento accrescitivo spontaneo, proporzioni corporee, sviluppo puberale, e dati di statura finale (FH) in 33 soggetti, di cui 16 trattati con GH per deficit secretivo (GHD). Valutati inoltre efficacia e sicurezza della terapia con GH, definito il rischio oncologico e quantificato il coinvolgimento psico-cognitivo. 33 pazienti hanno mostrato GHD e sono stati trattati con GH per 6,8 ± 4,8 anni. Prima dell’ inizio della terapia, la velocità di crescita era - 2.6 ± 1.3 SDS e i livelli basali di IGF1 pari a - 2.0 ± 1.1 SDS. La terapia con GH a lungo termine, iniziata precocemente durante l’infanzia, ha determinato un guadagno staturale positivo rispetto ai pazienti non trattati (+1,3 SDS), normalizzando la FH per gli standards di condizione ma non per la popolazione generale e il Target staturale parentale. Il timing di sviluppo puberale ha influenzato negativamente lo scatto di crescita puberale. 1/88 soggetti, non sottoposta a terapia con GH, ha sviluppato neoplasia. Sono emersi ritardo mentale (41.1%), deficit visuo-spaziali (41.8%), ADHD (38.8%), anomalie del SNC (24.4%) e anomalie del tracciato elettroencefalografico (6.7%).
RASopathies are developmental disorders caused by heterozygous germline mutations in genes encoding proteins in the RAS-MAPK signaling pathway. These conditions share facial dysmorphism, failure to thrive, congenital heart disease, ectodermal, and skeletal anomalies, variable cognitive involvement, and susceptibility to certain malignancies as major characteristics. This study analized clinical features, growth trend and body proportions in 88 patients affected by RASopathies with molecularly confirmed diagnosis, and FH reached in 33, including 16 treated with GH therapy for proven GH deficiency. Clinically, 69 patients (78.4%) had a diagnosis of Noonan syndrome (NS), seven of NS/Loose anagen hair (8.0%), six of CFC syndrome (6.8%), and two of Costello syndrome, Noonan syndrome with multiple lentigines (NSML) and Legius syndrome. Among them, 52 (59.1%) had PTPN11 mutations, while the other genotypes were less than 10%. Most patients were born at term, after a physiological pregnancy and presented regular neonatal adaptation. 75.9% patients had cardiac anomalies and 20.2% needed surgery for cardiac involvement. Thirty-three patients showed GH deficiency after pharmacological tests, and were GH-treated for an average period of 6.8±4.8 years. Before starting therapy, HV was -2.6±1.3 SDS, and mean basal IGF1 levels were -2.0±1.1 SDS. Long-term GH therapy, starting early during childhood, resulted in a positive height response compared with untreated patients (1.3 SDS in terms of height-gain), normalizing FH for Ranke standards but not for general population and Target Height. The delayed pubertal development and the inadequate pubertal catch-up growth could explain the impaired FH. Our patients on GH-therapy benefitted from the pharmacological treatment if started in pre-puberty and given for a long time. Probably, the prepubertal start of GH-treatment could compensate the lack of a pubertal growth. 1/88 patient had cancer, but she didn’t received GH. The patients presented cognitive impairment (41.1%), ADHD (38.8%), SNC anomalies (24.4%) and EEG alterations (6.7%).

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25

Tamburrino, Federica <1980&gt. "I disordini del pathway RAS-MAPK o Rasopatie: aspetti diagnostici, clinici e terapeutici." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7435/.

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Le “RASopatie” includono un gruppo di patologie congenito-malformative a trasmissione autosomica-dominante causate da mutazioni eterozigoti germinali in geni che codificano per proteine del pathway RAS-MAPKinasi. Sono caratterizzate da dismorfismi faciali, iposomia, cardiopatia congenita, anomalie ectodermiche e scheletriche, coinvolgimento cognitivo e suscettibilità tumorale. La bassa statura è uno dei principali elementi distintivi sul quale si può agire sotto il profilo terapeutico, mediante somministrazione di Ormone della Crescita biosintetico (GH). In questo studio è stato analizzato l’andamento accrescitivo in un ampio gruppo di 88 pazienti affetti da Rasopatia con diagnosi molecolare confermata. Sono stati valutati: distribuzione per genotipo, prevalenza delle caratteristiche fenotipiche e correlazione genotipo-fenotipo sull’intero gruppo di studio ed in particolare andamento accrescitivo spontaneo, proporzioni corporee, sviluppo puberale, e dati di statura finale (FH) in 33 soggetti, di cui 16 trattati con GH per deficit secretivo (GHD). Valutati inoltre efficacia e sicurezza della terapia con GH, definito il rischio oncologico e quantificato il coinvolgimento psico-cognitivo. 33 pazienti hanno mostrato GHD e sono stati trattati con GH per 6,8 ± 4,8 anni. Prima dell’ inizio della terapia, la velocità di crescita era - 2.6 ± 1.3 SDS e i livelli basali di IGF1 pari a - 2.0 ± 1.1 SDS. La terapia con GH a lungo termine, iniziata precocemente durante l’infanzia, ha determinato un guadagno staturale positivo rispetto ai pazienti non trattati (+1,3 SDS), normalizzando la FH per gli standards di condizione ma non per la popolazione generale e il Target staturale parentale. Il timing di sviluppo puberale ha influenzato negativamente lo scatto di crescita puberale. 1/88 soggetti, non sottoposta a terapia con GH, ha sviluppato neoplasia. Sono emersi ritardo mentale (41.1%), deficit visuo-spaziali (41.8%), ADHD (38.8%), anomalie del SNC (24.4%) e anomalie del tracciato elettroencefalografico (6.7%).
RASopathies are developmental disorders caused by heterozygous germline mutations in genes encoding proteins in the RAS-MAPK signaling pathway. These conditions share facial dysmorphism, failure to thrive, congenital heart disease, ectodermal, and skeletal anomalies, variable cognitive involvement, and susceptibility to certain malignancies as major characteristics. This study analized clinical features, growth trend and body proportions in 88 patients affected by RASopathies with molecularly confirmed diagnosis, and FH reached in 33, including 16 treated with GH therapy for proven GH deficiency. Clinically, 69 patients (78.4%) had a diagnosis of Noonan syndrome (NS), seven of NS/Loose anagen hair (8.0%), six of CFC syndrome (6.8%), and two of Costello syndrome, Noonan syndrome with multiple lentigines (NSML) and Legius syndrome. Among them, 52 (59.1%) had PTPN11 mutations, while the other genotypes were less than 10%. Most patients were born at term, after a physiological pregnancy and presented regular neonatal adaptation. 75.9% patients had cardiac anomalies and 20.2% needed surgery for cardiac involvement. Thirty-three patients showed GH deficiency after pharmacological tests, and were GH-treated for an average period of 6.8±4.8 years. Before starting therapy, HV was -2.6±1.3 SDS, and mean basal IGF1 levels were -2.0±1.1 SDS. Long-term GH therapy, starting early during childhood, resulted in a positive height response compared with untreated patients (1.3 SDS in terms of height-gain), normalizing FH for Ranke standards but not for general population and Target Height. The delayed pubertal development and the inadequate pubertal catch-up growth could explain the impaired FH. Our patients on GH-therapy benefitted from the pharmacological treatment if started in pre-puberty and given for a long time. Probably, the prepubertal start of GH-treatment could compensate the lack of a pubertal growth. 1/88 patient had cancer, but she didn’t received GH. The patients presented cognitive impairment (41.1%), ADHD (38.8%), SNC anomalies (24.4%) and EEG alterations (6.7%).

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26

LUBRANO, SIMONE. "Yeast S. cerevisiae as a tool to study BRAFV600E kinase isoforms." Doctoral thesis, Università di Siena, 2018. http://hdl.handle.net/11365/1040150.

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BRAFV600E causes an altered regulation of the MAPK pathway (mitogen-activated protein kinase or RAS / RAF / MEK / ERK pathway), involved in cell division and differentiation. This mutation consists of the substitution of a valine with glutamic acid at position 600 (V600E), resulting in a change in conformation, responsible for a constitutive activation of the protein, even in the presence of a low level of RAS, its activator. In this work we have demonstrated, for the first time, that hBRAFV600E kinase activity is preserved and can be studied in yeast. Indeed, hBRAFV600E complements the activity of MAPKKK kinases belonging to the osmotic stress (HOG) pathway and is toxic in yeast strains deleted for phosphatases of the same pathway. Moreover, we have demonstrated that a yeast genetic context allows the one-by-one analysis of the 3 BRAF protein isoforms that always coexist in human cells (BRAF-Ref, BRAF-X1 and BRAF-X2). In addition, we provide experimental evidence that yeast can be used to perform high throughput screenings and identify new BRAFV600E functional interactors. In fact, two screenings have been performed in this model system, one using a cDNA Library and another one taking advantage of the Yeast Deletion Pool collection. The screening performed with the cDNA library, deriving from HeLa cells, was performed in a yeast strain deleted for two phosphates PTC1 and PTP3. ~105 transformed cells have been screened. We obtained 16 complete CDS, 13 out of 16 have been validated using the spot assay. Among them, we found the Small Integral Membrane Protein 10 (SMIM10), a protein of unknown function that has been further characterized because of its different expression levels in human melanoma cell lines with mutated BRAF as compared to those with wild type (wt) BRAF. Interestingly, SMIM10 overexpression causes a dramatic decrease in the levels of BRAFV600E both in yeast and in human cells. These results suggest that SMIM10 is a negative functional interactors (FI) of BRAFV600E with a possible oncosuppressive role. The second screening was performed using the Yeast Deletion Pool, a pool of yeast S. cerevisiae clones, that has a deletion in non-essential genes (4,741 clones). Each clone is identifiable by means of two specific DNA sequences called "barcodes". 4 Through the use of the yeast deletion pool, it is possible to identify functional interactors of proteins related to diseases which do not have homologous counterparts in yeast, such as BRAF. As a result of this screening, we have identified 9 genes affecting the fitness of cells expressing BRAFV600E-X1/Ref, compared to cells transformed with the empty vector. Four out of nine affected the fitness with both isoforms. Interestingly, among deleted genes altering the fitness of BRAFV600E expressing cells when deleted, there are RAS, a SWI/SNF remodeling factor and Arf2 (GTPase). The addition of salt to the growth of the YDP highlighted differences between the two isoforms. In fact, while the comparison pYES2-BRAFV600E-Ref versus pYES2-BRAFV600E-Ref + NaCl showed differences in 4 clones, the comparison of pYES2-BRAFV600E-X1 versus pYES2-BRAFV600E-X1+ NaCl showed differences in 21 clones. Among them, an ABC transporter, a Rho GTPase, and a subunit of TORC2 membrane-associated complex have been found. Finally, this work has yielded a list of modulators of BRAFV600E to be further characterized experimentally and eventually translated into innovative therapeutic strategies that could be used in addition to the existing BRAF inhibitors.

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Han, Sung-Jun. "Études sur les voies de signalisation de la réponse immunitaire dans Drosophila melanogaster et Anopheles gambiae." Paris 6, 2002. http://www.theses.fr/2002PA066174.

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28

Denley, Simon M. "The role of the systemic inflammatory response, the JAK STAT pathway and the MAPK pathway in the prognosis of resectable pancreatic cancer." Thesis, University of Glasgow, 2008. http://theses.gla.ac.uk/523/.

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Pancreatic cancer is a devastating disease with a five year survival of only 2-3%. Only 10-15% of patients have resectable disease at presentation and the only potential cure is major surgery with adjuvant chemotherapy. The outcomes of surgery are disappointing with a median survival of only15-17 months and operative mortality and morbidity figures of 5-10% and 40% respectively. This abysmal prognosis is likely due to the highly aggressive nature of the tumour, its resistance to adjuvant therapy, its late presentation and the likely presence of micro-metastases not detectable at staging or surgery. A pre-operative systemic inflammatory response (as measured by CRP) is known to be associated with a poor prognosis in a number of cancers including pancreatic cancer. The reasons behind this poor prognosis are not yet known. The main driver of plasma CRP levels is the cytokine IL-6, known to be elevated in the plasma of patients with pancreatic cancer. This thesis hypothesises that upregulation of two IL-6-dependent pathways, the JAK STAT and MAPK pathways is responsible for the poor prognosis associated with an inflammatory response in pancreatic cancer. Both of these pathways are known to be involved in cellular growth, differentiation and apoptosis and when activated they may confer a growth or survival advantage to tumour cells. The aims of this thesis were to establish the prognostic role of a systemic inflammatory response in resectable pancreatic cancer in both a retrospective and prospective cohort and establish whether increased protein expression in either the JAK STAT or MAPK pathways is associated with a poor prognosis in the same retrospective cohort. A retrospective database of 148 patients who had undergone Whipple resection for either pancreatic cancer (PC) or non-pancreatic peri-ampullary cancer (NPPC) was created with pre-operative CRP values and survival data. The author then created tissue micro-arrays (TMA’s) with both tumour and normal pancreatic duct tissue from each of the 148 patients in the retrospective cohort and carried out immunohistochemistry on 12 antibodies known to be crucial in IL-6 signalling (6 in the JAK STAT and 6 in the MAPK pathways). Following staining the author scored each of the antibodies using the weighted histoscore to allow analysis of antigen expression. During the period of research the author also created a prospective database of 36 patients who underwent surgery for either PC or NPPC. Plasma was stored pre-operatively from each of the patients and this was later thawed and using an ELISA kit another research fellow (JL) was able to establish plasma levels of IL-6 in the prospective cohort. On univariate analysis a raised pre-operative CRP was associated with poorer survival, 374 days versus 618 days (p=0.0001) in the retrospective PC group only. On multivariate analysis, only pre-operative CRP retained statistical significance amongst those factors shown to be significant on univariate analysis (P=0.009). In the prospective group, patients with low levels of IL-6 had a median survival of 799 days, against a median survival of 537 days in those with high plasma IL-6 levels (P=0.002) when all 36 patients were analysed together. On analysis of protein expression, no significant relationship between increased expression and poor survival was seen for any of the 12 proteins analysed. The results from this thesis confirm that a pre-operative inflammatory response is associated with poor survival in patients with resectable pancreatic cancer. Raised plasma levels of IL-6 are also associated with poorer survival in similar patients. However, the poor prognosis appears to be via a JAK STAT/ MAPK independent mechanism. Other possible explanations for this poor prognosis including the connection between inflammation and cachexia and other important inflammatory proteins such as NF-κB and SOCS are explored in the discussion of this thesis.

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Tang, Jing Yan. "Calycosin promotes angiogenesis involving estrogen receptor and mitogen-activated protein kinase (MAPK) signaling pathway." Thesis, University of Macau, 2009. http://umaclib3.umac.mo/record=b2158133.

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30

Sharp, Leslie L. "Studies on the role of the erk MAPK pathway in thymocyte lineage commitment decisions /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1999. http://wwwlib.umi.com/cr/ucsd/fullcit?p9944213.

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31

Luisi, Pierre 1985. "Positive selection in humans : from singles to interaction maps." Doctoral thesis, Universitat Pompeu Fabra, 2014. http://hdl.handle.net/10803/286921.

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From Darwin’s Origin of the Species to the recent wealth in genomic data, many biologists have focused their research on understanding how natural selection has shaped the variability among and within species. Although theoretical and empirical advances have been remarkable, most biological mechanisms underlying the molecular basis of human adaptation remain to be elucidated. The selectionist view of adaptation accounted for the bias towards independent gene evolution. Most published studies aiming at detecting positive selection using either polymorphism or divergence data have been performed using a gene-candidate or a genome-wide scan approach, as described in the two first articles presented here. However, gene evolution is largely influenced by the biological context in which the encoded protein performs its intrinsic function(s). The phenotype, not the genotype, is at the interface with natural selection. Thus, in order to understand gene evolution, and particularly when considering adaptive selection, it is crucial to reduce the gap between genotype and phenotype. Genes and proteins do not act in isolation, but rather interact one with others in order to perform a given biological function. Therefore, when studying natural selection at molecular level one promising framework is to consider gene networks, as described in the two last articles of the present thesis. Analyses of gene networks describing the Insulin/TOR transduction signalling cascade and the whole protein-protein physical interaction map hold very striking results. Namely, genes acting at the core of both networks, thus having either more effect on a given phenotype or more pleiotropic effects within the organism, are more likely to be targeted by recent positive selection, as inferred using polymorphism data.
Desde el “Origen de las Especies” de Darwin a la reciente revoluci´on gen´omica, muchos bi´ologos han centrado su investigaci´on en la comprensi ´on de c´omo la selecci´on natural ha dado forma a la variabilidad entre y dentro de las especies. Aunque, los avances te´oricos y emp´ıricos han sido notables, la mayor´ıa de los mecanismos biol´ogicos que subyacen a las bases moleculares de la adaptaci´on biol´ogica a´un no est´an suficientemente esclarecidos. La visi´on seleccionista de adaptaci´on marc´o el sesgo de los estudios evolutivos hacia el an´alisis de genes individuales. La mayor´ıa de estudios publicados destinados a la detecci´on de la selecci´on positiva utilizando datos de polimorfismo o de divergencia se han realizado utilizando un gen candidato o un enfoque de exploraci´on gen´omica, como se describe en los dos primeros art´ıculos presentados en la presente tesis. Sin embargo, la evoluci´on de genes est´a muy condicionada por el contexto biol´ogico en el que cada gen realiza su funci´on intr´ınseca, siendo el fenotipo, y no el genotipo, su materia primaria. Por lo tanto, a fin de comprender la evoluci´on de genes, y en particular cuando se considera la evoluci´on adaptativa, es crucial reducir la brecha entre el genotipo y el fenotipo. Los genes y las prote´ınas no act´uan de manera aislada, sino que interact´uan entre s´ı con el fin de realizar una funci´on biol´ogica determinada. Por lo tanto, un marco prometedor al estudiar la selecci´on natural a nivel molecular seria considerar las redes de genes, como se describe en los dos ´ultimos art´ıculos de la presente tesis. Los an´alisis de los datos de polimorfismo gen´etico, tanto de los genes que componen la v´ıa de la insulina, c´omo de los todos los genes descritos en los mapas f´ısicos de interacci´on prote´ına-prote´ına tienen resultados muy sorprendentes: los genes que act´uan en el n´ucleo de ambas redes, teniendo as´ı m´as efecto sobre un determinado fenotipo o m´as efectos ple´otropicos dentro del organismo, tienen m´as probabilidades de ser el blanco de la selecci´on positiva reciente.

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32

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.

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[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.

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Lundegaard, Pia Rengtved. "Chemical genetics in zebrafish : modulation of cAMP and MAPK pathways in behaviour." Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/23456.

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The prevalence of stress and anxiety disorders in modern society is increasing, but the development of new treatments decreasing due to high research costs and low success rates in clinical trials. The latest type of compounds introduced to treat anxiety and depression was the specific serotonin reuptake inhibitors (SSRI), which was introduced in 1987. Since then, no new class of compounds have been introduced, suggesting that the need to find alternative targets in treating mental disorders is needed. In this thesis I have used the zebrafish as a model organism to study the modulation of behaviours through intracellular signalling pathways, known to be involved in learning, memory and anxiety. First, using the pro-convulsant compound, pentylenetetrazole (PTZ), an automated tracking system was established to quantify and analyse swimming behaviour in larvae zebrafish. Pentylenetetrazole induces seizures in zebrafish at high concentrations, however this thesis identifies that the combination of a low level of PTZ and subjecting the fish to alternating cycles of light and dark induced a reversed response to light and dark. A group of compounds with known anti-seizure effects were subsequently screened, which found that a combinational treatment with diazepam and two types of neurosteroids reversed the PTZ-induced light dark response. Secondly, using the same automated analysis setup, the effect of cAMP modulators was studied on behaviour in zebrafish larvae. Our lab has previously established that Rolipram, a PDE4 inhibitor, causes anxiety thigmotaxis in zebrafish larvae. In this thesis we treated zebrafish larvae with Rolipram and other compounds modulating cAMP, which greatly increased the swimming activity, which was reversed by subsequently treating with PD0325901. To test if the pharmacological modulation of cAMP-levels through the inhibition of other PDEs would lead to increased locomotor activity, a small library of PDE inhibitors was screened, and 4 compounds were identified that caused an increase in locomotion – three of these compounds were PDE4-inhibitors. Finally, by using two behavioural assays, I found that in adult fish Rolipram cause anxiety-like phenotypes, which is also reversible by MAPK-inhibition.

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34

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.

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35

Rathore, Moeez Ghani. "Metabolic pathways and their function in leukemogenesis : the role of MAPK ERK5." Thesis, Montpellier 1, 2012. http://www.theses.fr/2012MON1T022/document.

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Les cellules cancéreuses utilisent une glycolyse anaérobie pour générer l'ATP au lieu de la phosphorylation oxydative. Cette spécificité métabolique offre certains avantages aux cellules cancéreuses: une prolifération rapide et une évasion immune qui implique la sous-régulation de l'expression du CMH-I à la surface des cellules, phénomène lié au changement métabolique. Dans nos expériences, nous forçons les cellules leucémiques à produire de l'énergie par phosphorylation oxydative en les incubant avec de la glutamine comme source d'énergie en absence de glucose. La respiration ainsi forcée induit une augmentation de la transcription et de l'expression du CMH-I. Ce changement de métabolisme induit aussi une augmentation de l'expression de MAPK ERK5 et son accumulation dans les mitochondries. ERK5 intervient dans les changements de l'expression du CMH-I et du métabolisme. La sur-régulation du CMH-I induite par la respiration est bloquée dans les cellules leucémiques exprimant le shRNA shERK5. ERK5 régule la transcription de l'histone désacétylase de classe III Sirtuin 1 par l'activation de sa cible MEF2, ayant pour conséquence la liaison de MEF2 au promoteur de SIRT1. La régulation transcriptionnelle de SIRT1 induite par ERK5 intervient dans la réponse antioxydante des cellules leucémiques, et la sous-régulation d'ERK5 affecte cette réponse antioxydante. L'augmentation du métabolisme de la glutamine observée dans les cellules leucémiques est initiée par la glutaminase (GLS), enzyme qui est le facteur limitant de la vitesse du métabolisme de la glutamine. miR-23a cible l'ARN messager de GLS et inhibe l'expression de GLS. Le milieu glutamine induit la translocation de p65 dans le noyau, qui mène à une augmentation de l'activité transcriptionnelle de p65. NF-KB p65 inhibe l'expression de miR-23a en amenant HDAC4 sur le promoteur de miR-23a. Cela permet aux cellules leucémiques d'augmenter l'utilisation de la glutamine en tant que source alternative de carbone. Ainsi, la respiration forcée dans les cellules leucémiques contrôle l'expression du CMH-I, la réponse antioxydante et facilite la prolifération tumorale
Cancer cells have anaerobic-like glycolysis to generate ATPs instead of oxidative phosphorylation. This specific metabolism provides advantages to cancer cells: rapid growth and immune evasion, which involves downregulation of MHC-I at the cell surface and it is linked to metabolic change. In our experiments, we force leukemic cells to produce energy by oxidative phosphorylation by incubating them with glutamine as an energy source in the absence of glucose. The forced respiration increases MHC-I transcription and protein level. This change of metabolism also leads to increase MAPK ERK5 expression and accumulation in mitochondria. ERK5 mediates changes in both MHC-I and metabolism. The respiration-induced upregulation of MHC-I is blocked in leukemic cells stably expressing short hairpin ERK5 (shERK5). ERK5 transcriptionally regulates the class III histone deacetylase Sirtuin 1 through activation of its target MEF2 and subsequently MEF2 binding to SIRT1 promoter. The ERK5-induced transcriptional regulation of SIRT1 mediates the antioxidant response in leukemic cells and downregulation of ERK5 impairs the antioxidant response. The increased glutamine metabolism found in leukemic cells is initiated by glutaminase (GLS), a rate limiting enzyme for glutamine metabolism. miR-23a targets GLS mRNA and inhibits GLS expression. The glutamine medium induces p65 translocation to the nucleus that leads to increase p65 transcriptional activity. NF-KB p65 inhibits miR-23a expression by bringing HDAC4 to the miR-23a promoter. This allows leukemic cells to increase the use of glutamine as an alternative source of carbon. Thus, forcing respiration in leukemic cells controls MHC-I expression, antioxidant response and facilitate tumor growth

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36

Li, Weiling. "Genetic changes in melanoma progression." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5595.

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Melanoma is a highly aggressive tumour with a poor prognosis for patients with advanced disease because it is resistant to current therapies. Therefore, the development of novel strategies for melanoma treatment is important. The characterization of the molecular mechanisms underlying melanoma proliferation, progression, and survival could help the development of novel targeted melanoma treatments. The MAPK and PI3K pathways both play important roles in melanoma progression. In the MAPK pathway, DUSP6, which acts as a phosphatase to negatively control the activation of ERK1/2, is involved in the development of human cancers. The MAPK pathway also regulates expression of the DNA repair gene ERCC1 following EGF treatment. ERCC1 is essential for nucleotide excision repair, which is one of the major systems for removal of cisplatin induced DNA lesions. The aims of this project were: 1, to investigate the molecular changes in our immortal mouse melanocyte cell lines that were needed for them to form tumours in a xenograft model; 2, to investigate whether the MAPK pathway regulates ERCC1 following cisplatin treatment and protects melanoma cells from death. Through comparison of the RAS/RAF/MEK/ERK (MAPK) and the PI3K/AKT (AKT) signalling pathways between our immortal mouse melanocyte cell lines and their tumour derivatives in our xenograft model, we identified a molecularly distinct subtype of mouse melanoma characterized by reduced ERK and AKT activity and increased expression of DUSP6. Functional analyses employing ectopic overexpression indicated that increased expression of DUSP6 enhanced anchorage independent growth ability and invasive ability in our mouse melanocytes, suggesting that increased DUSP6 expression may contribute to melanoma formation in the xenograft assay. We also demonstrated that higher expression of p-ERK suppressed invasion, but not anchorage independent growth, in our subtype of mouse melanoma by enforced expression of constitutively active MEK1 and MEK2. In addition, the role of DUSP6 in classical human melanoma was investigated in this Genetic changes in melanoma progression study. Inhibition of anchorage independent growth and invasion were observed after exogenous expression of DUSP6 in human melanoma cells. This suggested that DUSP6 played different roles in classic human melanoma than in our distinct subtype of mouse melanoma. Our study also investigated the phosphorylation level of ERK1/2 and the mRNA and protein level of ERCC1 and its partner XPF in the human melanoma cell line following cisplatin treatment. Significant increases in expression of p-ERK, ERCC1 and XPF were found in cisplatin treated cells. Moreover, a MEK inhibitor inhibited ERCC1 induction by cisplatin, but did not significantly affect XPF induction. This suggested that the MAPK pathway was involved in regulation of ERCC1 but not XPF. Furthermore, the DUSP6 level decreased after cisplatin treatment and overexpression of DUSP6 inhibited ERCC1 and XPF induction and reduced resistance to cisplatin. DUSP6 seems to play a crucial role in resistance of melanoma to cisplatin. In addition, a novel larger ERCC1 transcript was identified in human cell lines and was found to be upregulated by cisplatin. The ratio of larger ERCC1 transcript relative to the normal ERCC1 transcript increased following cisplatin treatment. The functions of this larger ERCC1 transcript in cisplatin resistance deserve further study.

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Burkitt, Wright Emma Mary Milborough. "De novo germline disorders of the Ras-MAPK pathway : clinical delineation, molecular diagnosis and pathogenesis." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/de-novo-germline-disorders-of-the-rasmapk-pathwayclinical-delineation-molecular-diagnosis-and-pathogenesis(9688dc20-7b1b-46f1-a638-b4d1809f430b).html.

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This work sought to investigate the clinical phenotypes and molecular basis of cardio-facio-cutaneous syndrome (CFC), a germline disorder of the Ras-MAPK pathway, like Noonan syndrome (NS) and neurofibromatosis type I, caused by mutations in genes encoding proteins that act within this signal transduction pathway. CFC is most commonly due to mutation in BRAF, and less commonly MAP2K1, MAP2K2 or KRAS. A proportion of patients currently have no mutation identified. Mutations and clinical features of patients with a molecular diagnosis of CFC were investigated, which demonstrated a wide range of causative mutations, and some unclassified variants. Both known and novel clinical features of CFC were identified. A strong association between severe contractures and the p.(Tyr130Cys) mutation in MAP2K1 was found, which has not previously been reported. In contrast to the large number of patients with a confirmed molecular diagnosis, several with a highly suggestive clinical phenotype have been found to have no mutationin any of the known CFC genes. The molecular basis of these presentations was investigated by conventional Sanger sequencing of candidate genes. Fourteen patients with the p.(Ser2Gly) mutation in SHOC2 were identified, with clinical presentations consistent with CFC, NS or CS. Target enrichment and massively parallel sequencing of selected genes was undertaken in ten patients. Mutations in known genes were identified in four patients (including the positive control). Candidate causative variants in novel genes were suggested in two further patients, one of which was confirmed on Sanger sequencing. Whole exome sequencing of patient-parent trios was also undertaken to identify de novo variants. Three trios were analysed, and in one patient with a clinical diagnosis of CFC, a frameshift mutation in NF1 was identified, which was confirmed by Sanger sequencing to be present and de novo. The molecular effects of CFC-associated mutations in BRAF on Ras-MAPK pathway signalling were studied in cell culture systems, using Western blotting for ERK1/2 phosphorylation, in vitro kinase assays and luciferase assays, to assess activity of downstream targets of the Ras-MAPK pathway. Altered pathway activity was demonstrated for novel variants that had not previously been characterised at the molecular level, which was in keeping with the findings of the effects of previously studied mutations. The cardiac phenotype in animal models of CFC, CS and NS/CFC was explored using expression microarrays to identify potentially important genes and pathways in the pathogenesis of hypertrophic cardiomyopathy (a progressive but potentially treatable disease feature) in these conditions. A signature of increased expression of Myh7, the embryonic form of myosin, was identified in the heart of the mouse model of CFC due to a B-Raf mutation at four weeks postnatal age, but comparative analysis suggested significant differences in either the mechanisms causing cardiac phenotypes, or the timescales over which these may exert their effects, in the three models. In summary, the most significant findings of this work were that SHOC2 mutation is a frequent cause of a severe NCFC presentation, and massively parallel sequencing can be an effective means of molecular investigation of this group of disorders. Novel features of CFC syndrome that were identified include severe contractures in association with p.(Tyr130Cys) mutations in MAP2K1. The analysis of mouse models of the NCFCs was hampered by heterogeneity within the expression microarray results, and low levels of expression of the H-Ras mutant allele in the mouse model of Costellosyndrome.

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38

Caccamise, Lauren M. "Regulation of a Differentiation MAPK Pathway by a Novel Integrated Signaling Network and Multiple Sensors." Thesis, State University of New York at Buffalo, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3725898.

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Filamentous growth is a cell differentiation program utilized by Saccharomyces cerevisiae to respond to nutrient limitation in the environment. This process is principally controlled by a mitogen-activated protein kinase (MAPK) pathway but is also impacted by a number of other pathways including Ras2p-cAMP-PKA, Target of Rapamycin, Rim101, and mitochondrial retrograde. Using a high-throughput genetic screening approach in conjunction with directed gene-deletion analysis, I have identified 97 new regulators of the filamentous growth MAPK pathway. These new regulators created new connections to the filamentous growth MAPK pathway as well as extended previously known connections. I have linked several of the pathways governing filamentous growth together as part of an integrated signaling network by showing that these pathways regulate each other’s transcriptional targets. This network indicates an intricate level of communication and coordination among these pathways that has not been previously appreciated. I show that proper coordination of the filamentous growth MAPK pathway is essential for proper morphogenesis and this is a potential reason for the many inputs used to control this response. The filamentous growth MAPK pathway is also regulated by three transmembrane proteins – Msb2p, Sho1p, and Opy2p. Here these three proteins are compared to determine that they have specific functions in regulating filamentous growth. The three proteins exhibit different localization patterns and rates of turnover from the plasma membrane. I show that the Rim101 pathway affects the filamentous growth MAPK pathway independently of the ESCRT pathway which shares components with the Rim101 pathway. Additionally, I have shown that overexpression of the arrestin protein Aly1p results in mislocalized Msb2p and diminished pathway activity.

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39

DI, BIASE ERIKA. "GM1 OLIGOSACCHARIDE ACCOUNTS FOR GM1 ROLE IN ENHANCING NEURONAL DEVELOPMENT ACTING ON TRKA-MAPK PATHWAY." Doctoral thesis, Università degli Studi di Milano, 2019. http://hdl.handle.net/2434/692335.

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Il ganglioside GM1 è un glicosfingolipide mono-sialilato presente nello strato esterno della membrana plasmatica cellulare ed è particolarmente abbondante nei neuroni. Numerosi studi in vitro e in vivo evidenziano il ruolo del GM1 non solo come componente strutturale ma anche come regolatore di diversi processi cellulari. Infatti, l'arricchimento di GM1 nei microdomini di membrana promuove il differenziamento e la protezione neuronale. Inoltre il contenuto di GM1 è essenziale per la sopravvivenza e il mantenimento dei neuroni. Nonostante vi siano numerose evidenze sugli effetti neuronotrofici mediati dal GM1, la conoscenza del meccanismo d'azione sottostante è scarsa. Recentemente, la catena oligosaccaridica del GM1 (oligoGM1) è stata identificata come responsabile delle proprietà neuritogeniche del ganglioside GM1 nelle cellule di neuroblastoma. Gli effetti mediati dall’oligoGM1 dipendono dal suo legame con il recettore specifico dell’ NGF, il TrkA, determinando così l'attivazione della via TrkA-MAPK. In questo contesto, il mio lavoro di dottorato mirava a confermare il ruolo dell’oligoGM1, come componente bioattiva dell’intero ganglioside GM1, capace di stimolare i processi di differenziaziamento e maturazione dei neuroni granulari cerebellari di topo. Come prima cosa, abbiamo eseguito analisi morfologiche in time -course sui neuroni primari coltivati in presenza o in assenza dei gangliosidi GM1 o GD1a (il quale rappresenta il diretto precursore catabolico del GM1), somministrati esogenamente. Abbiamo osservato che entrambi i gangliosidi aumentavano l’aggregazione e l'arborizzazione dei neuroni. Dopo successiva somministrazione dei rispettivi oligosaccaridi, abbiamo osservato che solo l’oligoGM1 favoriva la migrazione dei neuroni, mentre l’oligoGD1a non induceva nessun effetto discriminante rispetto alle cellule controllo. Questo risultato suggerisce l'importanza della specifica struttura saccaridica del GM1 nella mediazione degli effetti neuronotrofici del ganglioside. Quindi abbiamo caratterizzato biochimicamente l'effetto mediato dall’oligoGM1 nei neuroni e abbiamo osservato un più elevato tasso di fosforilazione delle proteine FAK e Src, le quali rappresentano i regolatori intracellulari chiave della motilità neuronale. Inoltre, in presenza dell’ oligoGM1 i neuroni granulari cerebellari mostravano un aumento del livello di marcatori neuronali specifici (ad es. β3-Tubulina, Tau, Neuroglicano C, Sinapsina), suggerendo uno stadio di maturazione più avanzato rispetto ai controlli. Inoltre, abbiamo scoperto che l'oligoGM1 accelera l'espressione del pattern di gangliosidi tipico dei neuroni maturi che è caratterizzato da alti livelli di gangliosidi complessi (cioè GM1, GD1a, GD1b e GT1b) e basso livello del ganglioside più semplice GM3. Per studiare il meccanismo d'azione dell'oligoGM1, abbiamo usato il suo derivato marcato con il trizio e abbiamo scoperto che l'oligoGM1 interagisce con la superficie cellulare senza entrare nelle cellule. Questa scoperta suggerisce la presenza di un bersaglio biologico sulla membrana plasmatica neuronale. È interessante notare che abbiamo riscontrato una precoce attivazione della via di segnalazione del TrkA associata alle MAP chinasi in seguito alla somministrazione dell’oligoGM1 nelle culture neuronali. Questo risultato suggerisce che questo evento rappresenti un punto di partenza degli effetti dell’ oligoGM1 nei neuroni. I nostri dati rivelano che gli effetti del ganglioside GM1 sul differenziamento e la maturazione neuronale sono mediati dalla sua porzione di oligosaccaride. Infatti, l’oligoGM1 interagisce con la superficie cellulare, innescando così l'attivazione di processi biochimici intracellulari che sono responsabili della migrazione neuronale, dell'emissione dei dendriti e della crescita degli assoni. Nel complesso, i nostri risultati sottolineano l'importanza dell’ oligoGM1 come un nuovo e promettente fattore neurotrofico.
The GM1 ganglioside is a mono-sialylated glycosphingolipid present in the outer layer of the cell plasma membrane and abundant in neurons. Numerous in vitro and in vivo studies highlight the role of GM1 not only as a structural component but also as a functional regulator. Indeed, GM1 enrichment in membrane microdomains promotes neuronal differentiation and protection, and the GM1 content is essential for neuronal survival and maintenance. Despite many lines of evidence on the GM1-mediated neuronotrophic effects, our knowledge on the underlying mechanism of action is scant. Recently, the oligosaccharide chain of GM1 (oligoGM1) has been identified as responsible for the neuritogenic properties of the GM1 ganglioside in neuroblastoma cells. The oligoGM1-mediated effects depend on its binding to the NGF specific receptor TrkA, thus resulting in the TrkA-MAPK pathway activation. In this context, my PhD work aimed to confirm the role of the oligoGM1, as the bioactive portion of the entire GM1 ganglioside, capable of enhancing the differentiation and maturation processes of mouse cerebellar granule neurons. First, we performed time course morphological analyses on mouse primary neurons plated in the presence or absence of exogenously administered gangliosides GM1 or GD1a (direct GM1 catabolic precursor). We found that both gangliosides increased neuron clustering and arborization, however only oligoGM1 and not oligoGD1a induced the same effects in prompting neuron migration. This result suggests the importance of the specific GM1 saccharide structure in mediating neuronotrophic effects. Then we characterized biochemically the oligoGM1-mediated effect in mouse primary neurons, and we observed a higher phosphorylation rate of FAK and Src proteins which are the intracellular key regulators of neuronal motility. Moreover, in the presence of oligoGM1 cerebellar granule neurons showed increased level of specific neuronal markers (e.g., β3-Tubulin, Tau, Neuroglycan C, Synapsin), suggesting an advanced stage of maturation compared to controls. In addition, we found that the oligoGM1 accelerates the expression of the typical ganglioside pattern of mature neurons which is characterized by high levels of complex gangliosides (i.e., GM1, GD1a, GD1b, and GT1b) and low level of the simplest one, the GM3 ganglioside. To study the mechanism of action of the oligoGM1, we used its tritium labeled derivative and we found that the oligoGM1 interacts with the cell surface without entering the cells. This finding suggests the presence of a biological target at the neuronal plasma membrane. Interestingly, we observed the TrkA-MAP kinase pathway activation as an early event underlying oligoGM1 effects in neurons. Our data reveal that the effects of GM1 ganglioside on neuronal differentiation and maturation are mediated by its oligosaccharide portion. Indeed, oligoGM1 interacts with the cell surface, thus triggering the activation of intracellular biochemical pathways that are responsible for neuronal migration, dendrites emission and axon growth. Overall, our results point out the importance of oligoGM1 as a new promising neurotrophic player.

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40

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.

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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.

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Miolli, Giulia Valentina. "Apple and strawberry MADS-box genes and their function in plant developmental pathways." Doctoral thesis, Università degli studi di Padova, 2014. http://hdl.handle.net/11577/3423840.

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The main role of MADS-box transcription factors in plant developmental processes has been well described in the model plant Arabidopsis thaliana. However, little is known about their function in crops of important agricultural and commercial value. Our study aims to investigate their role in two agronomical relevant Rosaceae crops: apple (Malus x domestica Borkh.) and strawberry (Fragaria vesca). Expression studies using qPCR and RNA seq have identified two apple Dormancy Associated MADS-box (DAM) genes. They group with the StMADS11 clade, and were named MdDAM1 and MdDAM2, the last one discovered ex novo. Real time expression studies in dormant buds collected during the chilling period and chromatin immunoprecipitation (ChIP) analyses confirmed that the genes are downregulated by exposure to cold and MdDAM1 is epigenetically repressed, as it has been demonstrated for Arabidopsis FLC and peach DAM genes. In parallel we worked on strawberry MADS-box genes of known function involved in flower development. We chose three MADS-box genes that are homologs of Arabidopsis PISTILLATA and AGAMOUS to perform gene expression and functional analysis using a RNA interference approach to obtain post-transcriptional gene silencing. The positive transgenic lines of each transformation were evaluated at the molecular and phenotypic level. Single gene mutants does not show altered flower phenotype, suggesting a different mechanism of flower development in strawberry, probably due to the peculiar flower structure.
Il ruolo fondamentale svolto dai fattori di trascrizione MADS-box nei diversi processi di sviluppo delle piante è stato descritto in dettaglio nell’organismo modello Arabidopsis thaliana. Tuttavia la loro funzione in colture di maggior valore agricolo e commerciale rimane da indagare. La presente ricerca si propone di comprendere il loro ruolo in due colture agronomicamente importanti appartenenti alle Rosacee: melo (Malus x domestica Borkh.) e fragola (Fragaria vesca). Studi dell’espressione genica attraverso Real time PCR e RNA-seq hanno permesso l’identificazione di due geni di melo appartenenti ai geni DAM (Dormancy Associated MADS-box). I due geni appartengono alla clade StMAD11 e sono stati denominati MdDAM1 e MdDAM2, quest’ultimo scoperto ex novo. Analisi di espressione con Real time PCR in gemme dormienti raccolte durante il periodo invernale e studi di immunoprecipitazione di cromatina (ChIP) hanno confermato che i geni sono silenziati in seguito all’espozione al freddo. Inoltre si è provato che solo MdDAM1 è epigeneticamente represso, come era stato in precedenza dimostrato in Arabidopsis per il gene FLC e in pesca per i geni DAM. In parallelo si è lavorato su alcuni geni MADS-box di fragola, di cui era nota la funzione, coinvolti nello sviluppo del fiore. Tra questi geni ne sono stati scelti tre, i probabili omologhi di PISTILLATA e AGAMOUS in Arabidopsis, per svolgere sia analisi di espressione, sia analisi funzionali che sfruttano l’approccio di RNA interference per ottenere silenziamento genico post-trascrizionale. Le linee transgeniche risultate positive sono state valutate a livello molecolare e fenotipico. Il silenziamento dei singoli geni non ha mostrato alterazioni nello sviluppo del fiore, suggerendo un diverso meccanismo coinvolto nello sviluppo del fiore in fragola, probabilmente a causa della sua particolare struttura.

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42

Liu, Boqi. "The gene regulatory network in the anterior neural plate border of ascidian embryos." Kyoto University, 2020. http://hdl.handle.net/2433/253119.

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43

FernaÌndez, Serra Montserrat. "Role of the MAPK signalling pathway in the epithelial mesenchyme transition in the sea urchin embryo." Thesis, Open University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.441145.

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44

Perera, Munasinhage Venura Lakshitha. "Metabolic profiling of plant disease : from data alignment to pathway predictions." Thesis, University of Exeter, 2011. http://hdl.handle.net/10036/3906.

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Understanding the complex metabolic networks present in organisms, through the use of high throughput liquid chromatography coupled mass spectrometry, will give insight into the physiological changes responding to stress. However the lack of a proper work flow and robust methodology hinders verifiable biological interpretation of mass profiling data. In this study a novel workflow has been developed. A novel Kernel based feature alignment algorithm, which outperformed Agilent’s Mass profiler and showed roughly a 20% increase in alignment accuracy, is presented for the alignment of mass profiling data. Prior to statistical analysis post processing of data is carried out in two stages, noise filtering is applied to consensus features which were aligned at a 50% or higher rate. Followed by missing value imputation a method was developed that outperforms both at model recovery and false positive detection. The use of parametric methods for statistical analysis is inefficient and produces a large number of false positives. In order to tackle this three non-parametric methods were considered. The histogram method for statistical analysis was found to yield the lowest false positive rate. Data is presented which was analysed using these methods to reveal metabolomic changes during plant pathogenesis. A high resolution time series dataset was produced to explore the infection of Arabidopsis thaliana by the (hemi) biotroph Pseudomonas syringe pv tomato DC3000 and its disarmed mutant DC3000hrpA, which is incapable of causing infection. Approximately 2000 features were found to be significant through the time series. It was also found that by 4h the plants basal defence mechanism caused the significant ‘up-regulation’ of roughly 400 features, of which 240 were found to be at a 4-fold change. The identification of these features role in pathogenesis is supported by the fact that of those features found to discriminate between treatments a number of pathways were identified which have previously been documented to be active due to pathogenesis

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Fourneaux, Benjamin. "Ciblage de la voie PI3K/mTOR dans les léiomyosarcomes : sensibilité et mécanismes de résistance." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0742/document.

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Les léiomyosarcomes (LMS) sont des tumeurs d’origine mésenchymateuse caractérisées par une différenciation musculaire lisse. La voie de signalisation PI3K/mTOR (qui contrôle la prolifération et la survie cellulaire) joue un rôle majeur dans le développement de ces tumeurs. De nos jours, cette voie est devenue une cible thérapeutique majeure en oncologie. Cette étude est la première qui évalue le bénéfice thérapeutique de l’inhibition de la voie PI3K/mTOR pour des patients atteint de LMS. Nous avons mis en évidence qu’une double inhibition de PI3K et mTOR est associée à une activité antitumorale supérieure à celle observée avec une inhibition de PI3K ou mTOR seule. Nous avons également montré que l’inhibition de la voie PI3K/mTOR est associée à une activation paradoxale de la voie MAPK et qu’un ciblage concomitant de cette voie est associé à une synergie antitumorale in vitro et in vivo. Afin de caractériser les mécanismes de résistance secondaire à l’inhibition de la voie PI3K/mTOR, nous avons développé in vitro et in vivo un modèle de résistance secondaire à l’inhibiteur double cible PI3K/mTOR. Nous avons notamment détecté une sous-population de cellules résistantes à l’inhibiteur et ayant des caractéristiques proches de celles des cellules souches. Nous avons mis en évidence que l’inhibition pharmacologique d’EZH2, une protéine cruciale du complexe Polycomb, permet de restaurer la sensibilité des modèles résistants. Ces résultats apportent de nouvelles perspectives thérapeutiques pour les patients atteints de LMS
Leiomyosarcomas (LMS) are tumors of mesenchymal origin characterized by a smooth cell differentiation. The PI3K/mTOR pathway has been shown to play a crucial role in the tumorigenesis of LMS. Several agents targeting this pathway are under clinical development for the treatment of solid tumors and hematological malignancies. We report here the first study evaluating its potential therapeutic benefit for patients with LMS. We have demonstrated that dual inhibition of PI3K and mTOR is associated with more effective antitumor activity than agents targeting PI3K or mTOR only. We have also shown that PI3K and mTOR inhibition is associated with a paradoxal activation of the MAPK pathway and that combined treatment with MEK inhibitor resulted in synergistic antitumor activity in vitro and in vivo. Moreover, we developed in vitro and in vivo resistant model to dual PI3K/mTOR inhibitor. Interestingly, we have found that a cancer stem cell-like subpopulation may be involved in treatment resistance. We have shown that pharmacological inhibition of EZH2, a crucial protein of the Polycomb complex, is able to reverse dual PI3K/mTOR inhibitor resistance in vitro and in vivo. These results provide new therapeutic strategies for patients with LMS

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46

Ovrén, Caroline. "Knockdown of the ERK pathway using siRNA in cultured chicken cardiomyocytes." Thesis, Linköpings universitet, Biologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-104567.

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The ancient South American birds called tinamous (Tinamidae) have the smallest hearts known among birds and their cardiomyocytes have previously been shown to express significantly lower levels of the mitogen-activated protein kinase ERK compared to the more modern chicken (Gallus gallus). ERK is a well-known mediator of growth signalling in the heart, especially in hypertrophy. The aim of this project was to assess the effect of ERK knockdown on proliferation in cultured chicken cardiomyocytes. By transfecting these cells with a lipoplexed siRNA, ERK mRNA levels were knocked down to approximately half (45%, SD: 27%) compared to cells transfected with a negative control siRNA. The knockdown was coupled with a decreased proliferative response to insulin-like growth factor 1 (IGF-1) and foetal bovine serum (FBS). In conclusion, the ERK pathway was confirmed to be instrumental also in proliferative signalling. The results also support the notion that ERK itself is the rate-limiting step of this MAPK cascade. The low native expression of ERK in tinamou cardiomyocytes is expected to impose a strict limit on proliferative growth in response to various stimuli in these hearts. The genetic changes leading to higher expression levels, and with it the potential for larger hearts, in modern birds would have led to greatly increased evolutionary fitness by way of an increased aerobic scope and the ability to sustain flight.

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47

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.

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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
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

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48

Mogensen, Christina Klarskov. "Release of bFGF from endotelial cells is mediated by protease induced HSP27 phosphorylation via p38-MAPK pathway." Diss., lmu, 2006. http://nbn-resolving.de/urn:nbn:de:bvb:19-51999.

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49

Belkind, Ori. "Physical systems : conceptual pathways between spacetime and matter /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/5703.

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50

Schmitt, Wolfgang Daniel. "Expression und Regulation der MAPK-Phosphatasen im Ovarialkarzinom." Doctoral thesis, [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=974669334.

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Dissertations / Theses on the topic 'MAPS pathway'

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