Hsp90 Mediates eNOS and Vascular Function

描述(由申请人提供)：本申请的总体目标是确定热休克蛋白90(Hsp9O)介导内皮型一氧化氮合酶(ENOS)功能的机制，以指导内皮生物学和血管生理学。该实验室最近的报告表明，eNOS完全能够产生一氧化氮(.NO)和超氧阴离子(O2-)。当用格尔达霉素(GA)阻断Hsp9O的构象变化时，eNOS在激活时产生O2-。当内皮细胞培养和分离的加压微血管被血管抑素预处理时，它们似乎也通过eNOS依赖的机制产生O2，将平衡从NO转移到O2，从而损害血管扩张。这些数据表明，Hsp90的相互作用决定了哪些自由基物种是由eNOS产生的。Angiostatin和GA均可诱导eNOS激活状态的改变，这由eNOS和与eNOS相关的Hsp90上的磷酸化eNOS(S1179)水平所定义。其他旨在确定eNOS磷酸化状态的研究表明，Hsp90与eNOS的相互作用可能保护或促进eNOS上另一个位点的丝氨酸磷酸化。由于eNOS上磷酸丝氨酸的存在与O2呈负相关，因此该位点可能通过引导自由基物种的产生来影响eNOS的功能。关于O2的产生，Hsp90与eNOS相互作用的信号转导机制尚不清楚。由于内皮细胞中NO和O2的平衡介导了许多功能，如内皮细胞的增殖和血管扩张，了解Angiostatin和GA如何改变调控eNOS功能的信号通路，对于了解血管生成机制以发展新的胶状血管和增加血管扩张以预防缺血性心脏病至关重要。这些研究的发现可能会与动脉粥样硬化、高血压和糖尿病相关的血管疾病的中介机制相关，并提供新的理解。

DESCRIPTION (provided by the applicant): The overall goal of this application is to determine the mechanisms by which heat shock protein 90 (Hsp9O) mediates endothelial nitric oxide synthase (eNOS) function to direct endothelial biology and vascular physiology. Recent reports from this laboratory demonstrate that eNOS is fully capable of generating both nitric oxide (.NO) and superoxide anion (O2-). When conformational changes in Hsp9O are blocked with geldanamycin (GA) eNOS generates O2- upon activation. When endothelial cultures and isolated pressurized microvessels are pre-treated with angiostatin they also appear to generate O2 about by an eNOS-dependent mechanism to shift the balance from .NO towards O2 about which impairs vasodilation. These data suggest that Hsp90 interactions direct which radical species is generated by eNOS. Both angiostatin and GA induce altered states of eNOS activation as defined by the levels of phospho-eNOS (S1179) on eNOS and Hsp90 associated with eNOS. Additional studies aimed at determining the phosphorylation state of eNOS suggest that Hsp90 interactions with eNOS may protect or promote serine phosphorylation at another site on eNOS. As the presence of phosphoserine on eNOS inversely correlates with O2 about this site may influence the function of eNOS by directing radical species generation. The signal transduction mechanisms governing Hsp90 interactions with eNOS with respect to O2 about generation remain unknown. As the balance of .NO and O2 about in the endothelium mediate many functions, endothelial proliferation and vasodilation, understanding how angiostatin and GA alter signaling pathways governing eNOS function is central to understanding the mechanisms governing angiogenesis for developing new collatoral vessels and increasing vasodilation to prevent ischemic heart disease. Findings from these studies will probably be relevant to and provide new understanding of mechanisms mediating vascular disease related to atherogenesis, hypertension and diabetes