Role of Protein Kinase C in Attachment, Spreading, and Migration of Human Endothelial Cells

Abstract

Attachment, spreading, and migration of vascular endothelial cells (EC) are necessary for angiogenesis, reendothelialization of an injured artery, or seeding of a prosthetic graft. However, little is known about the signaling pathways that mediate these effects. Protein kinase C (PKC) is a ubiquitous intracellular messenger which we have previously shown to be necessary for EC proliferation (Kentet al.,1995,Circ. Res.77, 231–238). In this study, we investigate whether activation of PKC is necessary for EC attachment, spreading, and migration. Using human umbilical vein EC, we found that direct activation of PKC with the phorbol ester phorbol 12-myristate-13-acetate enhanced all three processes. Inhibition of PKC by the selective agent, chelerythrine, markedly diminished the ability of EC to attach, spread, and migrate. Depletion of intracellular PKC by downregulation (prolonged exposure of EC to phorbol ester) reduced EC attachment and migration; however, downregulation had no effect on endothelial spreading. PKC is a family of isotypes, each of which may control specific cellular functions. By Western blotting, we identified PKC alpha, beta, delta, epsilon, eta, theta, and zeta isotypes in human EC. Downregulation led to a significant reduction in the quantity of PKC alpha and epsilon. These data demonstrate that activation of PKC is both necessary and sufficient for attachment, spreading, and migration of human EC. An isotype of PKC that is susceptible to downregulation (either alpha and/or epsilon) is at least partially responsible for attachment and migration. Pharmacological activation of PKC may be used as a method to enhance reendothelialization.