Our goal is to understand how polarity complexes control the formation and the localization of adherens junctions (AJs) in epithelial cells. We aim at deciphering the role of Crumbs, a transmembrane protein, in the organization of the sub-apical acto-myosin cytoskeleton and in the remodeling of Adherens junctions in both Drosophila melanogaster in collaboration with the team of T. Lecuit and in human intestinal epithelial cells in culture and in organoids. We are developing with the team of PF. Lenne new optical and physical methods to study forces and Adherens junction organization.
We have shown that Crumbs, an apical protein polarity complex, controls the cortical accumulation of F-actin in the sub-apical area of epithelial cells. In the embryo, Crumbs is also essential for the restriction of E-cadherin, the main protein of AJs, by regulating the size and distribution of E-cadherin clusters, through Par-3. Another important finding is that while the role of Crumbs in the clustering and distribution of E-cadherin is conserved in the epithelium of the pupal wing the mechanisms involved are different from the ones used in the primary epithelium rising the possibility that AJ formation and organization relies on tissue specific mechanisms. Finally, we have shown for the first time that some polarity proteins are distributed asymmetrically in AJs with only one epithelial cell contributing to the accumulation on one side for example. This finding will lead us to revisit entirely the function of these proteins in the communication between epithelial cells.
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