title: Internalization of large double-membrane intercellular vesicles by a clathrin-dependent endocytic process.
abstract: Beyond its well-documented role in vesicle endocytosis, clathrin has also been implicated in the internalization of large particles such as viruses, pathogenic bacteria, and even latex beads. We have discovered an additional clathrin-dependent endocytic process that results in the internalization of large, double-membrane vesicles at lateral membranes of cells that are coupled by gap junctions (GJs). GJ channels bridge apposing cell membranes to mediate the direct transfer of electrical currents and signaling molecules from cell to cell. Here, we report that entire GJ plaques, clusters of GJ channels, can be internalized to form large, double-membrane vesicles previously termed annular gap junctions (AGJs). These internalized AGJ vesicles subdivide into smaller vesicles that are degraded by endo/lysosomal pathways. Mechanistic analyses revealed that clathrin-dependent endocytosis machinery-components, including clathrin itself, the alternative clathrin-adaptor Dab2, dynamin, myosin-VI, and actin are involved in the internalization, inward movement, and degradation of these large, intercellular double-membrane vesicles. These findings contribute to the understanding of clathrin's numerous emerging functions.
authors.affiliation: Department of Biological Sciences, Lehigh University, Bethlehem, PA 18015, USA.
authors.forename: Michelle
authors.initials: M
authors.lastname: Piehl
authors.forename: Corinna
authors.initials: C
authors.lastname: Lehmann
authors.forename: Anna
authors.initials: A
authors.lastname: Gumpert
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Denizot
authors.forename: Dominique
authors.initials: D
authors.lastname: Segretain
authors.forename: Matthias M
authors.initials: MM
authors.lastname: Falk
mesh_terms: D008841:Actin Cytoskeleton / Q000737:chemistry / Q000378:metabolism; D048868:Adaptor Proteins, Signal Transducing / Q000032:analysis / Q000378:metabolism; D000818:Animals; D051017:Apoptosis Regulatory Proteins; D002478:Cells, Cultured; D002966:Clathrin / Q000032:analysis / Q000378:metabolism*; D018031:Connexin 43 / Q000378:metabolism; D003593:Cytoplasm / Q000737:chemistry / Q000378:metabolism; D034281:Dynamins / Q000032:analysis / Q000378:metabolism; D004705:Endocytosis; D017629:Gap Junctions / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D007425:Intracellular Membranes / Q000737:chemistry / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000032:analysis / Q000378:metabolism; D011755:Pyrophosphatases / Q000032:analysis / Q000378:metabolism; D022161:Transport Vesicles / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D025521:Tumor Suppressor Proteins
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; D002966:Clathrin; D018031:Connexin 43; C102885:DAB2 protein, human; D025521:Tumor Suppressor Proteins; C089785:myosin VI; C019950:CTPase; D011755:Pyrophosphatases; D018995:Myosin Heavy Chains; D034281:Dynamins