Disruption of cytoskeletal structures mediates shear stress-induced endothelin-1 gene expression in cultured porcine aortic endothelial cells.
Hemodynamic shear stress alters the architecture and functions of vascular endothelial cells. We have previously shown that the synthesis of endothelin-1 (ET-1) in endothelial cells is increased by exposure to shear stress. Here we examined whether shear stress-induced alterations in cytoskeletal structures are responsible for increases in ET-1 synthesis in cultured porcine aortic endothelial cells. Exposure of endothelial cells to 5 dyn/cm2 of low shear stress rapidly increased monomeric G-actin contents within 5 min without changing total actin contents. The ratio of G- to total actin, 54 +/- 0.8% in quiescent endothelial cells, increased to 87 +/- 4.2% at 6 h and then decreased. Following the disruption of filamentous (F)-actin into G-actin, ET-1 mRNA levels in endothelial cells also increased within 30 min and reached a peak at 6 h. The F-actin stabilizer, phalloidin, abolished shear stress-induced increases in ET-1 mRNA; however, it failed to inhibit increases in ET-1 mRNA secondary to other stimulants. This indicates that shear stress-induced increases in ET-1 mRNA levels may be mediated by the disruption of actin fibers. Furthermore, increases in ET-1 gene expression can be induced by actin-disrupting agents, cytochalasin B and D. Another cytoskeleton-disrupting agent, colchicine, which inhibits dimerization of tubulin, did not affect the basal level of ET-1 mRNA. However, colchicine completely inhibited shear stress- and cytochalasin B-induced increases in ET-1 mRNA levels. These results suggest that shear stress-induced ET-1 gene expression in endothelial cells is mediated by the disruption of actin cytoskeleton and this induction is dependent on the integrity of microtubules.
Morita
T
T
Third Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Japan.
Kurihara
H
H
Maemura
K
K
Yoshizumi
M
M
Yazaki
Y
Y
D000199:Actins / Q000378:metabolism; D000818:Animals; D001013:Aorta, Thoracic; D015152:Blotting, Northern; D002478:Cells, Cultured; D003078:Colchicine / Q000494:pharmacology*; D003571:Cytochalasin B / Q000494:pharmacology; D003599:Cytoskeleton / Q000187:drug effects / Q000502:physiology*; D016232:Endothelins / Q000096:biosynthesis*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D015870:Gene Expression / Q000187:drug effects; D007700:Kinetics; D010590:Phalloidine / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism*; D013314:Stress, Mechanical; D013552:Swine
D000199:Actins; D016232:Endothelins; D012333:RNA, Messenger; D010590:Phalloidine; D003571:Cytochalasin B; D003078:Colchicine