Atherosclerosis is a major cause of cardiovascular disease in developed countries. In this disorder,endothelial cells acquire procoagulant properties, while activated smooth muscle cells and macrophagesaccumulate in the arterial wall. The overall objective of this project will be to understand the regulation of theannexin 2 (A2)-based proteolytic cascade, initiated by plasmin, on the surface of vascular cells. A2 is amajor profibrinolytic receptor expressed on endothelial cells, activated smooth muscle cells, andmacrophages. A2 accelerates plasmin generation by several orders of magnitude, and plays a central rolein directed vascular cell migration and matrix remodeling, through the activation of additional downstreamproteases. Preliminary data suggest that translocation of A2 to the cell surface is a primary mechanism bywhich vascular cells (endothelial cells, smooth muscle cells, and macrophages) upregulate cell surfaceproteolytic activity. In this proposal, we will elucidate the molecular pathways that govern the transport of A2to the cell surface in response to stress and/or injury to vascular cells. Previously, we demonstrated that A2is exported from a cytoplasmic compartment to the cell surface through a non-classical, Golgi/endoplasmicreticulum-independent pathway initiated by brief heat stress. We showed that this regulated responserequires the participation of the A2 binding protein, p11 (S100A10), which enables a src-like, kinase-mediated tyrosine-23 phosphorylation switch that initiates the translocation response. In the proposedstudies, we will examine [1] the mechanism by which endothelial cells, smooth muscle cells, andmacrophages translocate A2 to the cell surface in response to injury, [2] the role of the ATP binding cassettetransporter A1 (ABCA1) in this process, [3] the specific role of the A2-binding protein, p11, in A2translocation, and [4] the significance of A2 transport in the response to vascular injury in vivo. Thesestudies will utilize combined approaches involving in vitro culture systems and genetically modified mousemodels, including A2 and p11 -nulls created in our laboratory. We will continue to collaborate withinvestigators in Projects III and V to capitalize on their expertise in the study of the growth factor signallingand cholesterol transporter mechanisms.
Showing the most recent 10 out of 226 publications
