title: Clathrin dependent endocytosis of E-cadherin is regulated by the Arf6GAP isoform SMAP1.
abstract: E-cadherin is a central component of the adherens junction in epithelial cells and continuously undergoes endocytosis via clathrin-coated vesicles and/or caveolae depending on the cell type. In this study, we examined the role of SMAP1, a clathrin-interacting GTPase-activating protein (GAP) for the ADP-ribosylation factor 6 (Arf6) GTPase, in E-cadherin endocytosis. Mardin-Darby canine kidney (MDCK) epithelial cells were used as a model, and SMAP1 localized in the cytoplasm and along the adherens junction where E-cadherin was present. Next, activity of SMAP1 was compared with that of other Arf6GAPs (and/or an effector of Arf6-GTP), namely GIT1 and AMAP2/DDEF2. Overexpression of SMAP1 but not GIT1 nor AMAP2/DDEF2 strongly inhibited basal, as well as phorbolester-induced, internalization of E-cadherin. Notably, AMAP2/DDEF2 rather enhanced the caveolae-mediated incorporation of a membrane protein other than E-cadherin. Thus, in MDCK cells, E-cadherin appeared to be endocytosed solely through SMAP1-regulated clathrin-coated vesicles. Furthermore, MDCK cells overexpressing SMAP1 showed a reduced degree of cell migration compared to untransfected cells, as assessed by wound healing and Transwell assays, and this reduction in migration appeared to be due to the accumulation of E-cadherin at the adherens junction in cells overexpressing SMAP1. Collectively, SMAP1 likely represents a key Arf6GAP in clathrin dependent endocytosis of E-cadherin in MDCK cells. This activity of SMAP1 in E-cadherin turnover may be involved in epithelial organization and/or epithelial-mesenchymal transition.
authors.affiliation: Department of Molecular Immunology, Institute of Development, Aging and Cancer, Graduate Schools of Life Science and Medicine, Tohoku University, Sendai 980-8575, Japan.
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Kon
authors.forename: Kenji
authors.initials: K
authors.lastname: Tanabe
authors.forename: Toshio
authors.initials: T
authors.lastname: Watanabe
authors.forename: Hisataka
authors.initials: H
authors.lastname: Sabe
authors.forename: Masanobu
authors.initials: M
authors.lastname: Satake
mesh_terms: D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D019921:Biotinylation; D015820:Cadherins / Q000378:metabolism*; D022461:Caveolins / Q000378:metabolism; D002465:Cell Movement; D002966:Clathrin / Q000378:metabolism*; D004285:Dogs; D004705:Endocytosis; D004848:Epithelium / Q000378:metabolism; D020690:GTPase-Activating Proteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D008648:Mesoderm / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000378:metabolism; D021381:Protein Transport; D012710:Serum Albumin, Bovine / Q000378:metabolism; D014945:Wound Healing
chemical_list: D000089982:ADP-Ribosylation Factor 6; D015820:Cadherins; D022461:Caveolins; D002966:Clathrin; D020690:GTPase-Activating Proteins; D008565:Membrane Proteins; D020033:Protein Isoforms; D012710:Serum Albumin, Bovine; D020727:ADP-Ribosylation Factors; C000715727:Arf6 protein, mouse