title: Association of Csk to VE-cadherin and inhibition of cell proliferation.
abstract: Vascular endothelial cadherin (VE-cadherin) mediates contact inhibition of cell growth in quiescent endothelial cell layers. Searching for proteins that could be involved in VE-cadherin signaling, we found the cytosolic C-terminal Src kinase (Csk), a negative regulator of Src family kinases. We show that Csk binds via its SH2 domain to the phosphorylated tyrosine 685 of VE-cadherin. VE-cadherin recruits Csk to cell contacts and both proteins can be co-precipitated from cell lysates of transfected cells and endothelial cells. Association of VE-cadherin and Csk in endothelial cells increased with increasing cell density. CHO cells expressing the tyrosine replacement mutant VE-cadherin-Y685F grow to higher cell densities than cells expressing wild-type VE-cadherin. Overexpression of Csk in these cells under an inducible promoter inhibits cell proliferation in the presence and absence of VE-cadherin, but not in the presence of VE-cadherin-Y685F. Reduction of Csk expression by RNA interference enhances endothelial cell proliferation. Our results suggest that the phosphorylated tyrosine residue 685 of VE-cadherin and probably the binding of Csk to this site are involved in inhibition of cell growth triggered by cell density.
authors.affiliation: Institute of Cell Biology, ZMBE, University of Münster, Münster, Germany.
authors.forename: Ulf
authors.initials: U
authors.lastname: Baumeister
authors.forename: Ruth
authors.initials: R
authors.lastname: Funke
authors.forename: Klaus
authors.initials: K
authors.lastname: Ebnet
authors.forename: Henrik
authors.initials: H
authors.lastname: Vorschmitt
authors.forename: Stefan
authors.initials: S
authors.lastname: Koch
authors.forename: Dietmar
authors.initials: D
authors.lastname: Vestweber
mesh_terms: D000818:Animals; D015703:Antigens, CD; D001665:Binding Sites; D016466:CHO Cells; D019556:COS Cells; D000081247:CSK Tyrosine-Protein Kinase; D015820:Cadherins / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D006224:Cricetinae; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D015723:Gene Library; D005982:Glutathione Transferase / Q000378:metabolism; D051379:Mice; D010766:Phosphorylation; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism; D019061:src-Family Kinases; D000099152:Cadherin 5
chemical_list: D015703:Antigens, CD; D000081247:CSK Tyrosine-Protein Kinase; D015820:Cadherins; D005982:Glutathione Transferase; D011505:Protein-Tyrosine Kinases; D034741:RNA, Small Interfering; D014443:Tyrosine; D019061:src-Family Kinases; D000099152:Cadherin 5