Protein-coupled receptors control vascular smooth muscle cell proliferation via pp60(c-src) and p21(ras)

The binding of vasoactive peptides to their respective G protein-coupled receptors has been implicated in the pathogenesis of vascular smooth muscle cell proliferation, leading to the development of hypertension, arteriosclerosis, and restenosis after vascular injury. We previously showed that the cytosolic tyrosine kinase pp60(c-src) is crucial for angiotensin II (ANG II)-induced activation of the protooncogene p21(ras). Therefore, we investigated the role of pp60(c-src) and p21(ras) in rat aortic smooth muscle cell proliferation induced by several G protein-coupled receptors. ANG II, endothelin-1, or thrombin increased cell proliferation and DNA synthesis. Electroporation of anti-pp60(c-src) antibodies into cells abolished proliferation in response to these G protein-coupled receptor ligands but not in response to platelet-derived growth factor-BE (PDGF-BB). In contrast, electroporation of anti-p21(ras) antibody completely blocked DNA synthesis and cell proliferation in response to ANG II, endothelin-l, thrombin, and PDGF-BB. Our data indicate that the pp60(c-src) tyrosine kinase is necessary and specific for vascular smooth muscle cell proliferation and DNA synthesis in response to G protein-coupled receptors but not classic growth factor receptors.