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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Characterization of the endocytic pathways regulating riboflavin (vitamin B2) absorption and trafficking in human epithelial cells

Foraker, Amy Beth 08 March 2007 (has links)
No description available.
32

THE ROLE OF CAVEOLAE IN THE FORMATION OF ABDOMINAL AORTIC ANEURYSMS

Crawford, Kevin John January 2015 (has links)
Abdominal aortic aneurysm (AAA) is a major cardiovascular disease and involves enhancement of renin-angiotensin system and recruitment/activation of inflammatory factors such as matrix metalloproteases (MMP's). Caveolae has been shown to play a role in a number of different cardiovascular diseases through different mechanisms including regulation of oxidative stress, inflammation and degradation of extracellular matrix components through MMP's. In addition, endothelial cell caveolae are known to localize the Ang-II (AT1) receptor and regulate renin-angiotensin signaling. Based on these findings, we evaluated the role of caveolae in AAA formation in the murine model. Here, eight week old mice were co-infused with Ang-II and BAPN, a lysyl oxidase inhibitor, to induce AAA. We found that mice lacking the main structural protein of caveolae, caveolin-1, did not develop AAA compared to WT animals in spite of hypertensive blood pressures measured by telemetry in both groups. This finding suggests that intact Ang-II signaling remains in place in caveolin-1 knockout mice. To begin to address the underlying mechanism by which caveolae contributes to AAA, we measured the level of oxidative stress and MMP's in aneurysms. We found an increased expression of MMP-2 and MMP-9 in vessels of WT mice displaying aneurysms. This increase in expression was not observed in Cav-1 knockout mice. Furthermore, KO mice showed less oxidative stress then their WT counterparts as assessed by anti-nitrotyrosine staining. Next we examined the characteristics of early AAA formation in wild-type mice. We found caveolae associated proteins, endothelial nitric oxide synthase (eNOS) and NADPH oxidase 2 (Nox2), were upregulated in early AAA formation, particularly in the endothelium. Also, Vascular Cell Adhesion Molecule (VCAM) was upregulated in the endothelium. However, macrophage infiltration and MMP-2 activation was not observed in early AAA development. In order to elucidate the role of endothelial caveolae in the formation of AAA, we induced AAA, as previously described, in endothelial specific cav-1 knockout mice. Preliminarily findings show endothelial specific knockout mice do not form AAA as compared to their WT littermates. In conclusion, caveolae appears to play a critical role in the formation of AAA in mice via oxidative stress, and recruitment and/or activation of MMPs, specifically MMP-2 and MMP-9. Early markers of AAA formation include VCAM, NOX2, eNOS, and protein nitration. Also, preliminary results indicate that endothelial specific knockout mice do not develop AAA. / Cell Biology
33

Zielgene der RAS-Onkoprotein-abhängigen Signaltransduktion / Identifizierung und Charakterisierung von Klasse II Tumor-Suppressorgenen

Sers, christine 02 October 2003 (has links)
Die Entstehung und Progression maligner Tumoren ist ein mehrstufiger Prozeß, der auf einer Vielzahl genetischer Alterationen beruht. Essentielle Schritte sind die Aktivierung von Proto-Onkogenen und die Inaktivierung von Tumor-Suppressorgenen. Infolge dessen können die Zellen unabhängig von externen Wachstumssignalen ungebremst proliferieren, die Apoptose wird gehemmt, die Angiogenese wird aktiviert, und es kommt schließlich zur Metastasierung. Zu den bekanntesten Proto-Onkogenen, die in humanen Tumoren aktiviert werden, gehören die RAS Gene. Sie sind in einer Vielzahl von Tumoren mutiert und führen zu einer Stimulation der Proliferation. Um den Einfluß aktivierter RAS Onkogene auf die Regulation der Genexpression zu untersuchen wurden Genexpressionsprofile in Zellkultur-Modellen und humanen Tumoren erstellt. In einem Fibroblasten- und einem Epithelzell-basierten System konnten mehrere hundert, RAS-abhängig differenziell exprimierte Genen identifiziert werden. Aufgrund der bekannten Funktionen ihrer Genprodukte spielen sie eine wichtige Rolle im Verlust der Zellzyklus-Kontrolle, der Kontrolle der Signalübertragung, in der Angiogenese-Induktion sowie in der Invasion und damit Metastasierung. Die Zusammenhänge zwischen der Aktivierung bestimmter Signalkaskaden wie z.B. Raf-Mek-Erk oder PI-3K und der Expression von definierten Genmustern wurden hergestellt. Weiterhin konnte mit Hilfe von Microarray Analysen eine Vielzahl potentieller Tumormarker und Zielgene für therapeutische Intervention im Ovarialkarzinom identifiziert werden. Die Rolle der KlasseII Tumorsuppressor Gene Caveolin-1 und H-REV107-1 in humanen Ovarialkarzinomen wurde detailliert untersucht und ihre Rolle in der Regulation des Zellüberlebens nachgewiesen. Caveolin-1, ein negativer Regulator der RAS-abhängigen Signalübertragung, wird in über 80% der untersuchten humanen Ovarialkarzinome gehemmt. Hierbei spielen epigenetische Mechanismen eine Rolle, die jedoch nicht Caveolin-1 selbst, sondern einen unbekannten Regulator des Caveolin-1 Gens betreffen. Das H-REV107-1 Gen, ein Wachstumsregulator mit unbekannter Funktion wird in ca. 50% der untersuchten Ovarialkarzinome nicht mehr exprimiert. Ähnlich wie bei Caveolin-1, führt eine gezielte Expression des Gens in Tumorzellen zur Apoptose. Die Suche nach Interaktionspartnern des H-REV107-1 Gens führte zur Identifizierung der ubiquitär exprimierten Phosphatase2A (PP2A). Die Bindung zwischen H-REV107-1 und PP2A wurde weiter charakterisiert und ihre Rolle in der H-REV107-1 vermittelten Apoptose analysiert. / Development and progression of human tumours is a multistep process depending on numerous genetic alterations. Essentiell steps herein are the mutational activation of oncogenes and the inactivation of tumour suppressor genes. As a result of these alterations, the cells acquire the potential of unlimited growth independent of external growth factor signals, apoptosis is diminished, angiogenesis is stimulated and finally metastasis can occur. Among the best known proto-oncogenes, mutated in a number of human tumours, are the RAS genes. To investigate the role of RAS oncogenes in transformation-related transcriptional alterations, expressionsprofiling was performed from cell culture models and human tumours. Several hundred genes were identified to be de-regulated in a RAS-dependent manner in a fibroblast and an epithelial cell-based model. The protein products encoded by these genes play important roles in the loss of cell cycle control, control of signal transduction, angiogenesis induction as well as invasion and metastasis. Groups of de-regulated genes could be assigned to distinct signaling pathways such as the Raf-Mek-Erk or the PI-3 kinase dependent pathways. In addition, a number of potential tumour markers and potential target structures for therapeutic intervention were identified in ovarian carcinomas with the help of microarray studies. The role of the class II tumor suppressor genes Caveolin-1 and H-REV107-1 in human ovarian carcinomas was further investigated and their role in the regulation of cell survival was demonstrated. Caveolin-1, a negative regulator of RAS-dependent signal transduction, is supressed in more than 80% of the ovarian carcinomas analysed. This suppression is mediated by epigenetic mechanisms which due not target Caveolin-1 itself but an unknown regulator of the Caveolin-1 gene. The H-Rev107-1 gene, a growth regulator with unknown function, is no longer expressed in nearly 50% of the ovarian carcinomas analysed. Similar to Caveolin-1, also re-expression of H-REV107-1 results in apoptosis in the tumour cells. The search for proteins interacting with H-REV107-1 led to the identification of the ubiquitously expressed phosphatase 2A (PP2A). The interaction between H-REV107-1 and PP2A was further characterised and its role in the H-REV107-1 mediated apoptosis investigated.
34

Nerve Growth Factor Signaling from Membrane Microdomain to Nucleus : Differential Regulation by Caveolins

Yu, Lingli 30 November 2012 (has links) (PDF)
At the plasma membrane, both NGF receptors have been shown to localized to lipid rafts, specific subdomains that are enriched in cholesterol, sphingolipids and the presence of caveolin proteins (Cav1 and/or Cav2). The focus of this work is on this membrane microenvironment mediated modulation of NGF signaling which via two receptors: p75NTR and TrkA. In the present work we found that overexpression of Cav-1 in mouse dorsal root ganglia neurons significantly impacted neurite extension. Similarly, overexpression of Cav-1 in PC12 cells strongly inhibits their ability to grow neurites in response to NGF. It inhibits NGF signaling without, impairing transient MAPK pathway activation. Rather, it does so by sequestering NGF receptors in lipid rafts, which correlates with the cell surface localization of downstream effectors, and phosphorylated-Rsk2, resulting in the prevention of the phosphorylation of CREB. By contrast, overexpression of Cav-2 potentiates NGF induced differentiation, which is accompanied by sustained activation of downstream effectors, and standard internalization of the receptors. This differential effect could be due to the different localization of Caveolins, that modifies the microenvironment, thereby affecting NGF signaling. Furthermore, PC12 cells expressing the non-phosphorylatable Cav-1 mutant (S80V), neither TrkA trafficking or CREB phosphorylation are inhibited and the response resembles that observed in Cav-2 expressing PC12 cells. These studies underline the interplay between caveolins and NGF signalling, offering insight into the potential impact of Caveolin-1 and mutations thereof in certain cancers where NGF signaling is involved.
35

Focal adhesion kinase mediates caveolin-1 expression during epithelial to mesenchymal transition a novel pathway regulating aspects of cell motility in cancer /

Bailey, Kelly M. January 2008 (has links)
Thesis (Ph. D.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains x, 229 p. : ill. (some col.). Includes abstract. Includes bibliographical references.
36

MiR-199a-5p, un « fibromiR » amplificateur de la voie du TGF-beta dans la fibrose pulmonaire idiopathique / MiR-199a-5p is upregulated during fibrogenic response to tissue injury and mediates TGFbeta-induced lung fibroblast activation by targeting caveolin-1

Henaoui, Imène-Sarah 16 December 2013 (has links)
La Fibrose Pulmonaire idiopathique (FPI) est une maladie fibroproliférative pour laquelle il n’existe aucun traitement efficace. Les mécanismes à l’origine de cette pathologie sont méconnus et impliquent plusieurs types cellulaires et facteurs de croissance, comme le TGF-β responsable de la différenciation de fibroblastes en myofibroblastes. Pour mieux comprendre ces mécanismes physiopathologiques, nous nous sommes intéressés à l’implication des miARN dans ce processus. Une analyse par puces à ADN de l’ensemble des miARN modulés dans des échantillons pulmonaires de souris, résistantes ou sensibles à la fibrose pulmonaire induite par la bléomycine, nous a permis d’identifier miR-199a-5p comme le meilleur candidat associé à la fibrose pulmonaire mais aussi fibrose rénale et hépatique. J’ai ensuite démontré que l’expression de miR-199a-5p était induite par le TGF-β in vitro, et que sa surexpression ectopique induisait la différenciation des fibroblastes. Une combinaison d’approche in silico et expérimentale, m’a permis d’identifier la Cavéoline-1 (CAV-1) comme cible de ce miARN. La CAV-1 est impliquée dans la dégradation du récepteur TGF-β. Ainsi, l’inhibition de CAV-1 par miR-199a-5p constitue une boucle de rétrocontrôle positif exacerbant la voie TGF-β. De manière intéressante, l’inhibition de miR-199a-5p in vitro régule la différenciation, la prolifération et la migration des fibroblastes pulmonaires par le TGF-β. Par ailleurs, nos résultats précliniques indiquent que l’inhibition de ce miARN diminue les marqueurs de fibrose, permettant d’envisager le développement de nouvelles approches thérapeutiques dans le traitement de la FPI et d’autres maladies fibroprolifératives. / Idiopathic Pulmonary Fibrosis (IPF) is a fibroproliferative disease with poor prognosis and for which no effective treatment exists. The mechanisms of this disease remain poorly understood and involve numerous cell types and growth factors such as TGF-β, which leads to the activation of lung fibroblasts into myofibroblasts; the key cell type driving the fibrogenic process. In this context, we focused the involvement of miRNAs in fibrosis process. To identify miRNAs with potential roles in lung fibrogenesis, we performed a genome-wide assessment of miRNA expression in lungs from two different mouse strains known for their distinct susceptibility to lung fibrosis after bleomycin exposure. We identified miR- 199a-5p as the best candidate associated with lung fibrosis but also kidney and liver fibrosis. I observed that miR-199a-5p expression was induced upon TGF-β exposure, and that its ectopic expression was sufficient to promote the pathogenic activation of pulmonary fibroblasts. Using combination of targets miRNA prediction tools and a transcriptomic approach we identified the Caveolin-1 (CAV-1), a critical mediator of pulmonary fibrosis, as a specific target of miR-199a-5p. Thus, we shown that miR-199a-5p is a key effector of TGF-β signaling in lung fibroblasts by regulating CAV1. Interestingly, inhibition of miR-199a-5p in vitro prevents the differentiation, proliferation and migration of fibroblasts after TGF-β stimulation. Finally, our preclinical results indicate that inhibition of this miRNA decreases fibrosis markers. Thus, miR-199a-5p behaves as a major regulator of tissue fibrosis with therapeutic potency for the treatment of IPF and fibroproliferative diseases.
37

ACUTE REGULATION OF GLUT1 FUNCTION: THE ROLE OF DETERGENT-RESISTANT MEMBRANE DOMAINS

Rubin, Darrell 23 June 2004 (has links)
No description available.
38

Rôle des mouvements membranaires dans la régulation de la production endogène de glucose / Role of membrane movements in the regulation of endogenous glucose production

Chilloux, Julien 05 March 2012 (has links)
La production endogène de glucose est une fonction cruciale au maintien de l’homéostasie glucidique dont les 2 dernières étapes sont la production de glucose par la glucose-6-phosphatase (G6Pase) et la sortie du glucose hors de la cellule par le transporteur facilité GLUT2. Les mécanismes dépendants de mouvements membranaires régulant ces deux étapes ont été étudiés. La régulation de la G6Pase par l’AMPc dépend de mouvements membranaires. Cependant les mécanismes moléculaires de cette régulation restaient à caractériser. Nous avons étudié l’hypothèse d’une phosphorylation directe des sous-unités de la G6Pase par la PKA. La PKA est capable d’induire l’activité G6Pase. Cependant, aucune phosphorylation des sous-unités G6Pase n’a pu être mise en évidence par phosphorylation in vitro, mutations dirigées de sites potentiels de phosphorylation ou analyse par spectrométrie de masse. En absence de Glut2, le glucose produit de novo sort des hépatocytes par une voie dépendante de mouvements membranaires, dont le mécanisme moléculaire n’est pas caractérisé. Cette voie vésiculaire n’est pas impliquée dans la sortie du glucose glycogénolytique. À l’inverse, 50% du glucose néoglucogénique sort des hépatocytes par une voie vésiculaire, probablement dépendante de la cavéoline-1. Par microscopie confocale à fluorescence, nous avons montré que la G6Pase se déplace dans la cellule vers la membrane plasmique et co-localise avec une partie de la cavéoline1 cellulaire. Les vésicules composées de cavéoline-1 et contenant la G6Pase pourrait donc constituer un lien entre le réticulum endoplasmique, lieu de production du glucose et la membrane plasmique, lieu de libération du glucose / Endogenous glucose production is a crucial function to maintain glucose homeostasis whose last two steps are glucose production by glucose-6-phosphatase (G6Pase) and glucose output by GLUT2. Regulations of both steps depend on membrane movements. In this work, we characterized the mechanisms of these regulations. Regulation of G6Pase by cAMP depends on membrane movements; however the molecular mechanisms of this regulation still have to be characterized. We hypothesized that PKA directly phosphorylated G6Pase subunits. We showed that PKA was able to enhance G6Pase activity. However, no phosphorylation of G6Pase subunits was evidenced by in vitro phosphorylation, directed mutagenesis of potentiel phosphorylation sites or mass spectrometry. In the absence of Glut2, the gluconeogenic glucose produced by hepatocytes is released through a pathway depending on membrane movements, which has not been characterised yet. This vesicular pathway was not involved in the output of glycogenolytic glucose. However, half of gluconeogenic glucose was released through a vesicular pathway, probably depending on caveolin-1. By confocal microscopy, we showed that G6Pase moved in cells and co-localized in part with cellular caveolin-1. Caveolin-1 vesicles containing G6Pase could thus constitute a link between the endoplasmic reticulum, site of glucose production, and the plasma membrane, site of glucose output
39

Efeitos do γ-orizanol e extrato hidroalcólico de Thuya occidentalis sobre linhagens de câncer de próstata responsivas e não-responsivas a andrógenos / Efeitos do gama-orizanol e extrato hidroalcólico de Thuya occidentalis sobre linhagens de câncer de próstata responsivas e não-responsivas a andrógenos

Hirsch, Gabriela Elisa January 2015 (has links)
O câncer de próstata é a segunda causa de morte entre homens no Brasil. É tipo um câncer de crescimento lento, podendo levar anos para o tumor atingir 1 cm3, porém, em alguns casos ele pode se espalhar pelo corpo, sendo o osso o principal sítio de metástase. No estágio de desenvolvimento do câncer conhecido como metástase, o principal tratamento consiste em terapia de restrição andrógena, levando as células prostáticas a pararem de proliferar, uma vez que elas crescem em resposta a presença de hormônios andrógenos, como a diidrotestosterona e testosterona. Porém, em alguns casos, as células proliferam mesmo na ausência de andrógenos e isto se deve a diversos fatores que, em geral, estão associados a mutações no receptor andrógeno e/ou alterações no metabolismo andrógeno. Quando isto acontece, os tratamentos disponíveis são menos efetivos e costumam falhar. Porém, estudos sugerem que o γ-orizanol, um fitoesterol extraído do óleo do farelo do arroz; e extratos amplamente utilizados na medicina popular, como o extrato hidroalcólico de Thuya occidentalis, poderiam atuar inibindo o desenvolvimento e progressão do câncer de próstata. Neste estudo, com o uso de abordagens bioquímicas e de biologia molecular, foi demonstrado que o tratamento com γ-orizanol diminui a viabilidade e biomassa celular em cultura, associado ao aumento da morte celular por apoptose e/ou necrose, em linhagens celulares responsivas (LNCaP) e não-responsivas a andrógenos (PC3 e DU145), além de aumentar a pERK1/2 em células LNCaP e DU145. O γ-orizanol também foi capaz de bloquear o ciclo celular em G2/M nas células PC3 e LNCaP e em G0/G1 nas células DU145. Estes efeitos foram ainda acompanhados por uma redução da expressão do gene e proteína caveolina-1- uma importante molécula envolvida no aumento da agressividade do câncer de próstata, e também, na progressão da doença para o fenótipo andrógeno resistente - nas células não-responsivas a andrógenos, e do gene PCGEM1 - gene específico da próstata regulado por andrógeno - nas células LNCaP e DU145. Ainda, γ-orizanol também mostrou capacidade de regular vários miRNAs - pequenas moléculas de RNA não codificantes de proteínas - envolvidos no controle de funções associadas ao desenvolvimento, progressão e invasão no câncer de próstata, como o miR16-1, miR19b-2, miR24b-1, miR24b-2, miR99a, miR133a-5p, miR182-5p, miR198 e miR222. O extrato hidroalcólico de Thuya occidentalis reduziu a viabilidade e biomassa celular nas linhagens responsiva (LNCaP) e não-responsivas (DU145 e PC3) a andrógenos, além de induzir parada do ciclo celular na fase G0/G1 nas células DU145 e aumentar a morte celular por apoptose e/ou necrose em todas as linhagens. Da mesma forma que o γ-orizanol, este extrato reduziu a expressão da caveolina-1 nas linhagens não-responsivas a andrógenos. Trabalhos anteriores mostram que o monoterpeno α-tujona é o principal composto ativo do extrato de Thuya occidentalis. Por cromatografia gasosa acoplada a detector de massas foi mostrada a existência de 0,0016 μg de α-tujona na dose de extrato usada neste estudo. No entanto, o tratamento com 0,0016μg de α-tujona foi efetivo somente sobre linhagem LNCaP, não tendo efeito sobre as outras linhagens estudadas, reforçando a hipótese da diferença de sensibilidade entre as linhagens responsivas e não responsivas a andrógeno e mostrando a contribuição de outros componentes do extrato nos efeitos observados neste estudo. Concluindo, estes resultados demonstram que tanto γ-orizanol como o extrato de Thuya occidentalis podem vir a ser agentes terapêuticos promissores no tratamento de câncer de próstata, não só por inibirem o crescimento celular, mas também e principalmente pela possibilidade de induzirem a recuperação da sensibilidade a andrógenos, aumentando as possibilidades de tratamento da doença. / Prostate cancer is the second cause of death among men in Brazil. It is a slowgrowing cancer and it may take years for tumor to reach 1 cm3, but in some cases it can spread throughout the body and the bone is the main site of metastasis. At this cancer stage known as metastasis, the principal treatment involves antiandrogen therapy, leading to prostate cells stop proliferating, because they grow in response to presence of androgens such as testosterone and dihydrotestosterone. However, in some cases, the cells can proliferate even in the absence of androgens and this fact occurs due to many factors and they are generally associated with mutations in the androgen receptor and/or alterations in androgen metabolism. In this stage, the treatments available are less effective and usually fail. However, studies suggest that γ-oryzanol, a phytosterol extracted of rice bran oil; and extracts widely used in folk medicine, as Thuya occidentalis hidroalcolic extract, could act inhibiting the development and progression of prostate cancer. In this study, using molecular biology and biochemical approaches we showed that γ- oryzanol treatment was able to decrease cell viability and biomass in culture, and this fact was linked to increased cell death by apoptosis and/or necrosis in androgen responsive (LNCaP) and unresponsive (DU145 and PC3) prostate cancer cell lines, besides increasing pERK1/2 in LNCaP and DU145 cells. γ- oryzanol was also able to cause cell cycle arrest at G2/M phase in LNCaP and PC3 cells and at G0/G1 phase in DU145 cells. These effects were also accompanied by a reduction in caveolin-1 gene and protein expression - an important molecule related to high aggressiveness in prostate cancer and also in the progression of the disease to androgen resistant phenotype - in androgen unresponsive cells, and also PCGEM1 gene - a prostate specific gene regulated by androgens - in LNCaP and DU145 cells. γ-oryzanol also showed ability to regulate several miRNAs - small non-coding RNA molecules - involved in the control of many functions associated with the development, progression and invasion of prostate cancer, such as miR16-1, miR19b-2, miR24b-1, miR24b-2, miR99a, miR133a-5p, miR182-5p, miR198 and miR222. Thuya occidentalis hidroalcolic extract also reduce cell viability and biomass in androgen responsive (LNCaP) and unresponsive (DU145 and PC3) cells, in addition to inducing cell cycle arrest at G0/G1 phase in DU145 cells and to increase apoptosis and/or necrosis cell death in all cell lines. The same way that γ-oryzanol, this extract reduced the caveolin-1 expression in androgen unresponsive prostate cancer cells. Prior studies showed that the monoterpene α-thujone is the main active compound in the T. occidentalis extract. By gas chromatography coupled to mass detector it was showed the existence of 0.0016 μg of α-thujone in extract dose used in this study. However, the treatment with 0.0016 μg of α-thujone was effective only on LNCaP cell line, having no effect on the other studied lines, supporting the hypothesis of difference in sensitivity between responsive and unresponsive cell lines and showing the contribution of other components in the effects caused by the extract, observed it this study. In conclusion, these results demonstrate that both γ-oryzanol as T. occidentalis extract may become promising therapeutic agents in treatment of prostate cancer, not only inhibit cell growth but also and manly by the possibility of inducing the recovery of androgen sensitivity, increasing the treatment chances of treatment this disease.
40

Nerve Growth Factor Signaling from Membrane Microdomain to Nucleus : Differential Regulation by Caveolins / La signalisation du "Nerve Growth Factor" à partir de microdomaines membranaires jusqu'au noyau : Régulation différentiel par les Cavéolines

Yu, Lingli 30 November 2012 (has links)
Le NGF est reconnu, et le signal qu’il véhicule est donc médié, par deux récepteurs membranaires : p75NTR et TrkA. Il a été démontré qu’au niveau de la membrane, p75NTR et TrkA sont localisées dans les radeaux membranaires, des microdomaines caractérisés par la présence de protéines cavéolines (Cav-1 et/ou Cav-2). Dans le présent travail, nous avons constaté que la surexpression de Cav-1 dans les neurones des ganglions de la racine dorsale diminue l’extension des neurites. De la même manière, la surexpression de Cav-1 dans les cellules PC12 inhibe les réponses cellulaires déclenchées par l’exposition au NGF. L’activation des effecteurs situés en aval de TrkA n’est pas inhibée. L’expression de Cav-1 provoque une inhibition de la sortie du récepteur des radeaux accompagné par la rétention au niveau de la surface cellulaire, des effecteurs situés en aval incluant Rsk2 phosphorylé. Dans le même temps, la présence de formes phosphorylées de CREB n’est plus détectable. En revanche, la surexpression de Cav-2 potentialise la différenciation des cellules induite par le NGF, ce qui est associé à une activation prolongée des effecteurs situés en aval et à une internalisation des récepteurs. Ces différents effets pourraient être dû à la localisation des cavéolines, qui résulte en une perturbation du microenvironnement des cellules et donc de la signalisation du NGF. En outre, l’expression d’une Cav-1 mutée sur la sérine 80 (S80V) dans des cellules PC12, ne gêne ni le trafic ni la signalisation de TrkA. Au contraire elles se comportent de façon semblable à des cellules Cav-2. Ces études soulignent également le rôle potentiel de Cav-1 et ses mutations dans des cancers NGF-dépendantes. / At the plasma membrane, both NGF receptors have been shown to localized to lipid rafts, specific subdomains that are enriched in cholesterol, sphingolipids and the presence of caveolin proteins (Cav1 and/or Cav2). The focus of this work is on this membrane microenvironment mediated modulation of NGF signaling which via two receptors: p75NTR and TrkA. In the present work we found that overexpression of Cav-1 in mouse dorsal root ganglia neurons significantly impacted neurite extension. Similarly, overexpression of Cav-1 in PC12 cells strongly inhibits their ability to grow neurites in response to NGF. It inhibits NGF signaling without, impairing transient MAPK pathway activation. Rather, it does so by sequestering NGF receptors in lipid rafts, which correlates with the cell surface localization of downstream effectors, and phosphorylated-Rsk2, resulting in the prevention of the phosphorylation of CREB. By contrast, overexpression of Cav-2 potentiates NGF induced differentiation, which is accompanied by sustained activation of downstream effectors, and standard internalization of the receptors. This differential effect could be due to the different localization of Caveolins, that modifies the microenvironment, thereby affecting NGF signaling. Furthermore, PC12 cells expressing the non-phosphorylatable Cav-1 mutant (S80V), neither TrkA trafficking or CREB phosphorylation are inhibited and the response resembles that observed in Cav-2 expressing PC12 cells. These studies underline the interplay between caveolins and NGF signalling, offering insight into the potential impact of Caveolin-1 and mutations thereof in certain cancers where NGF signaling is involved.

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