The mechanism of atherogenesis is likely to involve a platelet-derived growth factor (PDGF) that stimulates smooth muscle cell proliferation in areas of platelet aggregation. The mitogenic action of PDGF is mediated by its interaction with specific receptor sites on the surface of smooth muscle cells and fibroblasts. The aim of this research is to elucidate the molecular mechanisms of PDGF action and define its significance in disease. This work will be used by the Investigator to develop fundamental research skills. The first phase of work will include formal courses in cell biology and biochemistry. The Investigator will also study tumor virology, a course that is relevant because of the homologies that exist between growth factors and oncogenic viruses. Phase I research aims include the purification and biochemical characterization of the PDGF receptor. Monoclonal antibodies to the receptor will then be raised using hybridoma techniques. The second phase of research will apply methods and reagents developed during Phase I to further characterize the PDGF receptor and to investigate its role in disease. Biosynthetic precursors of the receptor will be identified in pulse-chase experiments and variations in receptor location will be defined by electron microscopy. Receptor number, tyrosine kinase and topoisomerase activity will be measured in cultured skin fibroblasts taken from patients with atherosclerosis and other proliferative diseases. If functional abnormalities are detected, receptor structure and biosynthetic processing will be analyzed. Cultured fibroblasts will be subjected to S1 nuclease assay to detect PDGF-mediated activation of the c-myc gene. Finally, PDGF levels in the serum, plasma and platelets of patients with severe atherosclerosis will be determined using radioreceptor assays developed in Phase I. This research will add greatly to our understanding of the molecular biology of the PDGF receptor and will serve as a foundation for further independent research by the Investigator. A long term goal of the Investigator is the discovery of new modalities for the prevention and treatment of atherosclerosis.