title: JAM-A and aPKC: A close pair during cell-cell contact maturation and tight junction formation in epithelial cells.
abstract: Cell-cell adhesion plays a critical role in the formation of barrier-forming epithelia. The molecules which mediate cell-cell adhesion frequently act as signaling molecules by recruiting and/or assembling cytoplasmic protein complexes. Junctional Adhesion Molecule (JAM)-A interacts with the cell polarity protein PAR-3, a member of the PAR-3-aPKC-PAR-6 complex, which regulates the formation of cell-cell contacts and the development of tight junctions (TJs). In our recent study we found that JAM-A is localized at primordial, spot-like cell-cell junctions (pAJs) in a non-phosphorylated form. After the recruitment of the PAR-aPKC complex and its activation at pAJs, aPKC phosphorylates JAM-A at Ser285 to promote the maturation of immature junctions. In polarized epithelial cells, aPKC phosphorylates JAM-A selectively at the TJs to maintain the barrier function of TJs. Thus, through mutual regulation, JAM-A and aPKC form a functional unit that regulates the establishment of barrier-forming junctions in vertebrate epithelial cells.
authors.affiliation: Institute-associated Research Group: Cell adhesion and cell polarity; Institute of Medical Biochemistry; Center of Molecular Biology of Inflammation; University Muenster; Muenster, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Ebnet
keywords: JAM-A; PAR complex; aPKC; cell polarity; cell-cell contact; epithelial barrier; tight junction