Pin1 prolyl isomerase regulates endothelial nitric oxide synthase

描述（由申请人提供）：内皮源性一氧化氮（NO）调节心血管稳态的许多重要方面，血管NO生成的改变即使只有两倍，也会对正常血管生理和血管病理生理产生重大影响。一氧化氮在调节血管舒张状态，从而调节血压方面起着至关重要的作用。内皮释放的NO还可调节急性炎症相关的其他过程，包括血小板聚集、血小板和白细胞粘附内皮、血管平滑肌细胞增殖、内皮细胞凋亡、血管生成和血管渗漏。由于NO在这些过程中的关键作用，血管NO生成的异常被认为有助于某些血管疾病的发病机制，如动脉粥样硬化、糖尿病和高血压。一氧化氮是由内皮型一氧化氮合酶（eNOS）催化精氨酸氧化而合成的。因此，获得对eNOS酶的结构、功能和调控的详细了解显然是一个值得科学研究的目标。eNOS在翻译后受两种主要机制调控：蛋白质相互作用和磷酸化。目前还不清楚这两种不同的eNOS调节过程是如何相互关联的。然而，一段时间以来人们已经知道，eNOS中存在丝氨酸116的抑制性磷酸化位点（S116）。在基础条件下和暴露于促炎细胞因子后，内皮细胞中的这个位点被磷酸化。我们的初步数据提出了这样的假设：脯氨酸导向的eNOS S116位点磷酸化促进了Pin1脯氨酸异构酶的结合，Pin1诱导的构象变化抑制了eNOS活性。初步数据还表明，这一过程可能对动脉粥样硬化疾病起重要作用。因此，我们建议通过多种不同的方法来检验这些假设，包括纯化蛋白、培养内皮细胞、完整血管段和包括动物疾病模型在内的整个动物。这些研究将提供比目前存在的内皮细胞eNOS调控更完整的理解，这是基础科学家和临床医生都非常感兴趣的话题。

DESCRIPTION (provided by applicant): Endothelium-derived nitric oxide (NO) regulates many important aspects of cardiovascular homeostasis and alterations in vascular NO production of as little as two-fold can have major consequences in both normal vascular physiology and vascular pathophysiology. NO has a crucial role in regulation of the state of vasodilatation of blood vessels and hence in regulation of blood pressure. NO released from the endothelium also modulates other processes as well including platelet aggregation, platelet and leukocyte adhesion to the endothelium, vascular smooth muscle cell proliferation, endothelial cell apoptosis, angiogenesis, and vascular leakage involved in acute inflammation. Because of the key role of NO in each of these processes, abnormalities in vascular NO production are thought to contribute to the pathogenesis of certain vascular disorders such as those of atherosclerosis, diabetes, and hypertension. NO is synthesized in endothelial cells by oxidation of arginine catalyzed by the enzyme, endothelial nitric oxide synthase (eNOS). Obtaining a detailed understanding of the structure, function, and regulation of eNOS enzyme is thus clearly a worthy goal of scientific investigation. eNOS is regulated post-translationally by two primary mechanisms: protein-protein interactions and phosphorylation. Nothing is yet known about how these two different eNOS regulation processes are interrelated. What has been known for some time, however, is that there exists in eNOS an inhibitory phosphorylation site at serine 116 (S116). This site is phosphorylated in endothelial cells under basal conditions and after exposure to pro-inflammatory cytokines. Our preliminary data give rise to the hypothesis that proline-directed phosphorylation of eNOS at S116 promotes binding of the Pin1 prolyl isomerase and Pin1-induced conformational changes that suppress eNOS activity. Preliminary data also show that this process may make an important contribution to the disease of atherosclerosis. We therefore propose to test these hypotheses by a variety of different methods using purified proteins, cultured endothelial cells, intact blood vessel segments, and whole animals including animal disease models. These studies will provide a more complete understanding than currently exists of regulation of eNOS in endothelial cells, a topic of great interest to both basic scientists and clinicians.