The Annexin 2 Stress Response in Vascular Cells

在发达国家，动脉粥样硬化是心血管疾病的主要原因。在这种混乱中， 内皮细胞获得促凝血特性，而激活的平滑肌细胞和巨噬细胞 积聚在动脉壁上。本项目的总体目标将是了解 在血管细胞表面，由纤溶酶启动的基于膜联蛋白2(A2)的蛋白水解级联反应。A2是一种 主要纤溶原受体表达于内皮细胞、活化的平滑肌细胞和 巨噬细胞。A2使纤溶酶的生成加快了几个数量级，并发挥了核心作用 在定向的血管细胞迁移和基质重塑中，通过激活额外的下游 蛋白酶。初步数据表明，A2向细胞表面的移位是一个主要的机制，通过 哪些血管细胞(内皮细胞、平滑肌细胞和巨噬细胞)上调细胞表面 蛋白水解性。在这个提案中，我们将阐明控制A2转运的分子途径 以响应压力和/或对血管细胞的损伤。在此之前，我们演示了A2 通过非经典的高尔基体/内质膜从细胞质隔间输出到细胞表面 短暂热应激启动的网织非依赖性途径。我们发现这种受调控的反应 需要A2结合蛋白p11(S100A10)的参与，从而使src样激酶- 介导的酪氨酸-23磷酸化开关，启动易位反应。在建议的 研究中，我们将研究[1]内皮细胞、平滑肌细胞和 巨噬细胞将A2转移到细胞表面以响应损伤，[2]三磷酸腺苷结合盒的作用 转运蛋白A1(ABCA1)在这一过程中，[3]A2结合蛋白p11在A2中的特定作用 易位，以及[4]A2转运在体内血管损伤反应中的意义。这些 研究将利用体外培养系统和转基因小鼠的组合方法 模型，包括我们实验室创建的A2和p11-Null。我们将继续与 项目III和项目V中的研究人员利用他们在生长因子信号传递研究中的专业知识 和胆固醇转运蛋白机制。

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 macrophages accumulate in the arterial wall. The overall objective of this project will be to understand the regulation of the annexin 2 (A2)-based proteolytic cascade, initiated by plasmin, on the surface of vascular cells. A2 is a major profibrinolytic receptor expressed on endothelial cells, activated smooth muscle cells, and macrophages. A2 accelerates plasmin generation by several orders of magnitude, and plays a central role in directed vascular cell migration and matrix remodeling, through the activation of additional downstream proteases. Preliminary data suggest that translocation of A2 to the cell surface is a primary mechanism by which vascular cells (endothelial cells, smooth muscle cells, and macrophages) upregulate cell surface proteolytic activity. In this proposal, we will elucidate the molecular pathways that govern the transport of A2 to the cell surface in response to stress and/or injury to vascular cells. Previously, we demonstrated that A2 is exported from a cytoplasmic compartment to the cell surface through a non-classical, Golgi/endoplasmic reticulum-independent pathway initiated by brief heat stress. We showed that this regulated response requires 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 proposed studies, we will examine [1] the mechanism by which endothelial cells, smooth muscle cells, and macrophages translocate A2 to the cell surface in response to injury, [2] the role of the ATP binding cassette transporter A1 (ABCA1) in this process, [3] the specific role of the A2-binding protein, p11, in A2 translocation, and [4] the significance of A2 transport in the response to vascular injury in vivo. These studies will utilize combined approaches involving in vitro culture systems and genetically modified mouse models, including A2 and p11 -nulls created in our laboratory. We will continue to collaborate with investigators in Projects III and V to capitalize on their expertise in the study of the growth factor signalling and cholesterol transporter mechanisms.