title: Endocytosis of the apical junctional complex: mechanisms and possible roles in regulation of epithelial barriers.
abstract: Tight junctions (TJ) and adherens junctions (AJ) regulate cell-cell adhesion and barrier function of simple polarized epithelia. These junctions are positioned in the apical end of the lateral plasma membrane and form the so-called apical junctional complex (AJC). Although initially seen as purely structural features, the AJC is now known to play important roles in cell differentiation and proliferation. The AJC is a highly dynamic entity, undergoing rapid remodeling during normal epithelial morphogenesis and under pathologic conditions. There is growing evidence that remodeling of the AJC is mediated by internalization of junctional proteins. This review summarizes what is known about endocytic pathways, intracellular destinations and signaling cascades involved in internalization of AJC proteins. Potential biological roles for AJC endocytosis in maintaining functional apical junctions, reversible opening of epithelial barrier and disruption of intercellular adhesion are also discussed.
authors.affiliation: Epithelial Pathobiology Research Unit, Department of Pathology and Laboratory Medicine, Emory University, Room 115, 615 Michael Street, Atlanta, GA 30322, USA. aiivano@emory.edu
authors.forename: Andrei I
authors.initials: AI
authors.lastname: Ivanov
authors.forename: Asma
authors.initials: A
authors.lastname: Nusrat
authors.forename: Charles A
authors.initials: CA
authors.lastname: Parkos
mesh_terms: D015815:Cell Adhesion Molecules / Q000378:metabolism; D016764:Cell Polarity; D004705:Endocytosis; D004847:Epithelial Cells / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D007365:Intercellular Junctions / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D046912:Multiprotein Complexes
chemical_list: D015815:Cell Adhesion Molecules; D046912:Multiprotein Complexes