PKC is required for activation of ROCK by RhoA in human endothelial cells.
Rho/Rho-kinase (ROCK) complex formation is the only proposed mechanism for ROCK activation. Rho/ROCK and PKC can exhibit a convergence of cellular effects such as suppression of endothelial nitric oxide synthase (eNOS) expression. We, therefore, investigated the role of PKC in RhoA/ROCK complex formation and activation linked to eNOS expression in cultured human umbilical vein endothelial cells. We showed that expression of constitutively active RhoA (Rho63) or ROCK (CAT) suppressed eNOS gene expression. This effect of Rho63 but not that of CAT was abolished by phorbol ester-sensitive PKC depletion. Accordingly, depletion or inhibition of PKC prevented ROCK activation by Rho63 without affecting RhoA/ROCK complex formation. Similarly, suppression of eNOS expression and activation of ROCK, but not RhoA by thrombin were prevented by PKC inhibition or depletion. These results indicate that RhoA/ROCK complex formation alone is not sufficient and PKC is required for RhoA-induced ROCK activation leading to eNOS gene suppression.
Vascular Biology, Department of Medicine, Division of Physiology, University of Fribourg, Rue du Musée 5, CH-1700 Fribourg, Switzerland.
Christine
C
Barandier
Xiu-Fen
XF
Ming
Sandro
S
Rusconi
Zhihong
Z
Yang
D000470:Alkaloids; D053119:Benzophenanthridines; D015536:Down-Regulation / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D046911:Macromolecular Substances; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III; D010617:Phenanthridines / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D013917:Thrombin / Q000378:metabolism; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
D000470:Alkaloids; D053119:Benzophenanthridines; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D046911:Macromolecular Substances; D010617:Phenanthridines; C016299:chelerythrine; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D011493:Protein Kinase C; D013917:Thrombin; D020742:rhoA GTP-Binding Protein