This proposal will examine the mechanisms by which heparan sulfates inhibit SMC and glomerular mesangial cell growth. SMC proliferation is a key event in the pathogenesis of arterio-sclerosis, and is the major cause of the high failure rate of many vascular surgical procedures. Restenosis occurs within 1-3 months in a large fraction (typically 15 to 30%) of the operated vessels, greatly limited the usefulness of these procedures. A hallmark of the restenosis process is intimal SMC hyperplasia during the first few weeks following surgery. The aberrant proliferation of GMC, a cell closely related to the SMC, plays an important role in the pathogenesis of glomerular nephrites. The working hypothesis of this proposal is that heparin inhibits SMC and GMC proliferation by binding to specific receptors on the cell surface, resulting in selective modulation of mitogenic pathways. This leads to altered transcription of specific growth-regulatory genes required for mitogenesis. Testing this hypothesis has been greatly aided by three powerful tools: a panel of heparin-resistant SMC, a series of active and inactive heparin analogs, and a set of highly sensitive radiolabeled, fluorescent, and biotinylated heparin probes. Using these tools, two major goals are proposed: 1)Examine mitogenic signaling pathways by identifying and characterizing the function of heparin-regulated phosphotyrosine, phosphoserine, and phosphothreonine proteins, and by analyzing the effect of heparin cytosolic and nuclear calcium transients; and 2) Analyze heparin-regulated genes involved in mitogenesis of SMC and GMC, using several independent approaches to compare mRNA from sensitive and resistant cells, and from sensitive cells treated with inactive heparin analogs. The function of two heparin-regulated genes already identified, serum- and glucocorticoid- regulated kinase (sgk) and heparin-induced CCN like protein (hicp), will also be examined. It is hoped that a detailed understanding of the mechanisms and molecules that regulate SMC proliferation will provide a therapeutic rational for controlling SMC hyperplasia following vascular surgery, and may provide important insights into the pathophysiological basis for atherogenesis. Similarly, parallel examination of GMC growth control should aid in developing treatments for glomerular nephritides and shed light on the pathogenic basis for hypertensive renal disease.
Showing the most recent 10 out of 16 publications
