Abstract 252: Is Vascular Disease a Result of Too Much Vascular Damage? Evidence for an Active Endogenous Plasma Membrane Repair System in Endothelial Cells

Abstract

Many studies have correlated vascular disease with excessive vascular damage. For instance, vascular endothelial cells (EC) at sites of arterial branching are exposed to turbulent flow, a highly atherogenic factor, whereas chronic hypertension accelerates endothelial dysfunction. At the molecular level, EC are routinely exposed to damaging oxidants, cholesterol and cigarette smoke chemicals. However, how the vascular endothelium ‘repairs’ after ‘damage’ was until recently unknown. Recently, we have shown that EC express FERLINS ‘repair’ proteins, documented to allow the fusion of lipid ‘patches’ to a damaged plasma membrane. Indeed, Dysferlin and Myoferlin mRNA and proteins were found to be highly expressed in every EC line and human/rodent blood vessel investigated. Proteomics analyses revealed that both Dysferlin and Myoferlin are caveolae/lipid raft resident proteins, well known to be rich in signaling proteins at the heart of laminar flow sensing/ mechanotransduction. In vitro, loss of Dysferlin and Myoferlin resulted in attenuated Platelet Endothelial Cellular Adhesion Molecule-1 (PECAM-1) and Vascular Endothelial Growth Factor Receptor-2 (VEGFR-2) expression, respectively, as well as blunted membrane repair following physical injury. In vivo, Dysferlin-null and Myoferlin-null mice show blunted angiogenic response in response to various stimuli. Together, these data clearly show that the vasculature has complex, endogenous physical repair machinery at the plasmalemma, that the lipid ‘patches’ likely contain transmembrane protein cargo, and that Ferlins clearly play a role in vascular homeostasis. Finally, recent preliminary data from our laboratory suggests that Dysferlin is highly overexpressed in human atherosclerotic sections, and that Dysferlin-null mice are more susceptible to cardiovascular disease that their WT counterparts, indicating a protective role for Ferlin-associated repair in the cardiovascular system.