PDGF system in vascular smooth muscle cell proliferation

Distinct genes encode alpha and beta PDGF receptors which differ in their abilities to be triggered by three dimeric forms of the PDGF molecule. Each receptor is able to independently couple with mitogenic signal transduction pathways, and both are capable of inducing a readily detectable chemotactic response. The vascular smooth muscle cells which express both types of PDGF receptor are mitogenic and chemotactic for PDGFs. Moreover, the alpha receptor is the preferred receptor for platelet PDGF AB as well as the PDGF-AA isoform which is ubiquitously produced in many cells forming atherosclerotic plaques including macrophages, endothelial cells and even arterial smooth muscle cells. The availability of specific PDGF isoforms and the relative expression of each receptor gene product appear to be the major determinants of the PDGF response. An understanding of the molecular mechanisms by which the expression of PDGF and their receptors on vascular smooth muscle will give greater insights as to how these gene products are involved in atherosclerosis.