Clathrin dependent endocytosis of E-cadherin is regulated by the Arf6GAP isoform SMAP1

Exp Cell Res. 2008 Apr 15;314(7):1415-28. doi: 10.1016/j.yexcr.2007.11.006. Epub 2007 Nov 17.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ADP-Ribosylation Factors / metabolism*
  • Amino Acid Sequence
  • Animals
  • Biotinylation
  • Cadherins / metabolism*
  • Caveolins / metabolism
  • Cell Movement
  • Clathrin / metabolism*
  • Dogs
  • Endocytosis*
  • Epithelium / metabolism
  • GTPase-Activating Proteins / metabolism*
  • Membrane Proteins / chemistry
  • Membrane Proteins / metabolism*
  • Mesoderm / metabolism
  • Mice
  • Molecular Sequence Data
  • Protein Isoforms / metabolism
  • Protein Transport
  • Serum Albumin, Bovine / metabolism
  • Wound Healing

Substances

  • Cadherins
  • Caveolins
  • Clathrin
  • GTPase-Activating Proteins
  • Membrane Proteins
  • Protein Isoforms
  • Serum Albumin, Bovine
  • ADP-Ribosylation Factors
  • ADP-ribosylation factor 6