Abstracts
Résumé
La polarité, une des propriétés les plus importantes des épithéliums, se manifeste par la formation de deux domaines membranaires distincts, apical et basolatéral, dont les fonctions sont spécialisées. La formation, le maintien et les fonctions des tissus épithéliaux sont assurés par un canevas de protéines de surface connectées à des réseaux intracellulaires de molécules de structure et de signalisation organisant la polarité spécialisée du tissu, et contrôlant ses relations avec le milieu extérieur. Au sein de ces échafaudages moléculaires, les protéines à domaines PDZ (PSD95/Dlg/ZO-1) tiennent une place prépondérante en assurant l’assemblage et la distribution subcellulaire des acteurs de l’homéostasie épithéliale. Parmi celles-ci, les protéines de la famille LAP (LRR and PDZ) occupent le devant de la scène en raison de leur implication dans les étapes-clés de la différenciation épithéliale. De plus, l’étude de modèles génétiques invertébrés et vertébrés a notamment permis de mettre en exergue leur rôle central au cours du développement embryonnaire et de dévoiler, pour certaines protéines LAP, un rôle potentiel de suppresseur de tumeur.
Summary
Cell proliferation and cell differentiation are balanced processes required for the correct development and maintenance of tissues, including epithelial tissues. Disruption of this balance by downregulation or loss of function of gatekeepers of epithelial homeostasis may unleash tumor suppressing activities leading ultimately to tumorigenesis. Among the newcoming actors involved in epithelial cell polarity, recent data shed light on the crucial role played by the LAP (LRR And PDZ) protein family. LAP proteins assemble receptors, cytoplasmic adaptors and enzymes in multimolecular networks important for the different steps of epithelial differentiation : adhesion, building of tight junctions and trafficking of proteins along the secretory pathway. Furthermore, genetic studies in invertebrates and vertebrates have installed LAP proteins not only as crucial determinants for epithelial integrity but also as key regulators of cell proliferation and embryonic development.
Appendices
Références
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