Annexin II expression during cardiovascular cell injury

心脏和血管内的血管细胞受到一系列信号的影响，这些信号诱导适应性反应以维持体内平衡。由于心肌细胞不能自我更新，心脏对生化、炎症、氧化或缺血应激的反应手段有限。膜联蛋白II是一种钙调节、磷脂结合的内皮细胞表面蛋白，作为内皮细胞衍生的组织纤溶酶原激活剂及其循环底物纤溶酶原的共受体。纯化的膜联蛋白II刺激纤溶酶产生的催化效率约60倍。我们已经开发了一种膜联蛋白II缺陷小鼠，并观察到这些动物发展为心肌功能受损的退行性心肌病。我们进一步观察到，在体外增殖的内皮细胞中，膜联蛋白II响应于应激通过非经典分泌途径输出到细胞表面。该项目的总体目标是了解膜联蛋白II在基线和细胞应激状态下心脏功能中的作用。我们推测膜联蛋白II可能通过维持心肌微血管循环的完整性而发挥重要的心脏保护作用。目的探讨膜联蛋白II缺乏对小鼠心血管系统的影响。使用我们最近开发的膜联蛋白II基因敲除小鼠，我们将研究膜联蛋白II缺乏可能导致心肌收缩力降低，心室结构异常和心律失常的机制。目的II将能够确定膜联蛋白II参与内皮细胞应激反应的机制。初步数据表明，热休克和其他内皮应激导致膜联蛋白II不依赖于蛋白质合成，快速释放到细胞表面，同时细胞表面纤溶活性增加。该输出过程不需要完整的内质网-高尔基体轴，并且被PD 98059抑制，PD 98059是一种阻断Erk 1/Erk 2 MAP激酶信号级联激活的试剂。我们计划阐明这种输出机制，并确定其对内皮细胞功能的影响。目的III，最后，将确定膜联蛋白II是否在体内心血管应激状态下具有心脏保护作用。已发现膜联蛋白II在患有心脏功能障碍的人类和动物的心脏中上调。使用肾上腺素能刺激、运动、热应激、生物力学损害或氧化剂诱导的急性、亚急性和慢性应激模型，我们将确定膜联蛋白II是否能防止心血管损害。

Vascular cells within the heart and blood vessels are subject to an array of signals which induces adaptive responses for the maintenance of homeostasis. Because cardiomyocytes are incapable of self-renewal, the heart possesses limited means of responding to biochemical, inflammatory, oxidative, or ischemic stresses. Annexin II is a calcium- regulated, phospholipid-binding endothelial cell surface protein that serves as a co-receptor for endothelial cell derived tissue plasminogen activator and its circulating substrate, plasminogen. Purified annexin II stimulates the catalytic efficiency of plasmin generation by approximately 60-fold. We have developed an annexin II-deficient mouse and observed that these animals develop a degenerative cardiomyopathy with impaired myocardial function. We have further observed that, in endothelial cells propagated in vitro, annexin II is exported to the cell surface via a non- classical secretion pathway in response to stress. The overall goal of this project is to understand the role of annexin II in cardiac function both at baseline and during states of cellular stress. We hypothesize that annexin II may play a critical cardioprotective role by maintaining the integrity of the myocardial microvascular circulation. Aim I will to determine the cardiovascular consequences of annexin II deficiency in mice. Using our recently developed annexin II knockout mouse, we will study the mechanism by which annexin II deficiency may lead to reduced myocardial contractility, abnormal ventricular architecture and cardiac arrthymia. Aim II will be able to determine the mechanism by which annexin II participates in the endothelial cell stress response. Preliminary data indicate that heat shock and other endothelial stresses lead to protein synthesis-independent, rapid release of annexin II to the cell surface with a concomitant increase in cell surface fibrinolytic activity. This export process does not require an intact endoplasmic reticulum-Golgi axis, and is inhibited by PD98059, , an agent that blocks activation of the Erk1/Erk2 MAP kinase signaling cascade. We plan to elucidate this export mechanism and to determine its effect on endothelial cell function. Aim III, finally, will e to determine whether annexin II is cardioprotective during cardiovascular stress states in vivo. Annexin II has been found to be up-regulated in the hearts of humans and animals with cardiac dysfunction. Using models of acute, subacute and chronic stress induced by adrenergic stimuli, exercise, heat stress, biome3chanical compromise, or oxidant agents, we will determine whether annexin II protects against cardiovascular compromise.