Shunsuke Kon, Kenji Tanabe, Toshio Watanabe, Hisataka Sabe, Masanobu Satake
Department of Molecular Immunology, Institute of Development, Aging and Cancer, Graduate Schools of Life Science and Medicine, Tohoku University, Sendai 980-8575, Japan.
Experimental cell research 2008 Apr 15E-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.
Shunsuke Kon, Kenji Tanabe, Toshio Watanabe, Hisataka Sabe, Masanobu Satake. Clathrin dependent endocytosis of E-cadherin is regulated by the Arf6GAP isoform SMAP1. Experimental cell research. 2008 Apr 15;314(7):1415-28
PMID: 18331728
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