title: Role of Ca2+ and protein kinase C in shear stress-induced actin depolymerization and endothelin 1 gene expression.
abstract: Vascular endothelial cells adapt to changes in blood flow by altering the cell architecture and by producing various substances. We have previously reported that low shear stress induces endothelin 1 (ET-1) expression in endothelial cells and that this induction is mediated by depolymerization of actin fiber. In the present study, we examined the role of Ca2+ and protein kinase C (PKC) in shear stress-induced actin depolymerization and subsequent ET-1 gene expression. Exposure of cultured porcine aortic endothelial cells to low shear stress (5 dyne/cm2) for 3 hours increased the ratio of G-actin to total actin from 54 +/- 0.8% to 80 +/- 1.0%. This shear stress-induced actin depolymerization was completely blocked by chelation of extracellular Ca2+ with EGTA and partially inhibited by intracellular Ca2+ chelation with the tetraacetoxymethyl ester of BAPTA (BAPTA/AM). Pretreatment with staurosporine, a PKC inhibitor, or desensitization of PKC by treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA) for 24 hours also resulted in partial inhibition of shear stress-induced actin depolymerization. Although PKC activation by TPA mildly increased G-actin content, the effect of TPA and shear stress on actin depolymerization was not additive. Moreover, shear stress-induced ET-1 gene expression was inhibited by EGTA, BAPTA/AM, and staurosporine to a degree similar to the inhibition of actin depolymerization. In contrast, ET-1 gene expression induced by cytochalasin B, an actin-disrupting agent, was not affected by staurosporine.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Third Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Morita
authors.forename: H
authors.initials: H
authors.lastname: Kurihara
authors.forename: K
authors.initials: K
authors.lastname: Maemura
authors.forename: M
authors.initials: M
authors.lastname: Yoshizumi
authors.forename: R
authors.initials: R
authors.lastname: Nagai
authors.forename: Y
authors.initials: Y
authors.lastname: Yazaki
mesh_terms: D000199:Actins / Q000032:analysis / Q000187:drug effects / Q000378:metabolism*; D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D015152:Blotting, Northern; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D016232:Endothelins / Q000235:genetics*; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D015870:Gene Expression; D007202:Indicators and Reagents; D010703:Phorbol Esters / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D019311:Staurosporine; D013314:Stress, Mechanical; D013552:Swine
chemical_list: D000199:Actins; D000470:Alkaloids; D002614:Chelating Agents; D016232:Endothelins; D007202:Indicators and Reagents; D010703:Phorbol Esters; D012333:RNA, Messenger; D004533:Egtazic Acid; D011493:Protein Kinase C; D019311:Staurosporine; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D002118:Calcium