Methylarginines and Vascular Injury

描述（由申请方提供）：本提案的长期目标是建立二甲基精氨酸二甲氨基水解酶（DDAH），即负责甲基精氨酸（MA）代谢的酶，作为血管功能和损伤反应的关键调节剂。改变的一氧化氮（NO）生物合成已经涉及再狭窄损伤的发病机制，并且似乎内源性一氧化氮合酶抑制剂ADMA和NMMA的积累是在这些条件下观察到的NO生成减少的原因。我们已经表明，在兔和大鼠球囊介导的再狭窄损伤模型中，血管DDAH表达显著降低，同时细胞MA水平增加。该建议的总体假设是DDAH表达/活性的丧失导致MA积累和NO生物利用度降低，随后NO向血管壁提供的抗增殖抗动脉粥样硬化性质丧失。为了检验该假设，我们将追求以下目标。在目标1中，我们将定义DDAH的调节如何影响甲基精氨酸水平和随后的NOS衍生的NO和超氧化物的产生。在目标2中，我们将确定DDAH在血管损伤中的调节及其在动脉重塑中的作用。这些研究将检查DDAH表达缺失对平滑肌细胞增殖、迁移和内皮再生的影响。此外，使用携带DDAH基因的腺相关病毒载体，我们将确定DDAH过表达是否可以调节血管重塑过程并改善血管功能。最终的目标是确定甲基精氨酸在动脉粥样硬化形成中的作用。由于DDAH受LDL调节，我们将研究DDAH过表达对高脂血症状态下动脉粥样硬化发生和发展的影响。我们相信，这个项目将建立DDAH作为一个重要组成部分，在血管损伤的反应，并可能作为一个新的治疗目标，在治疗血管增生性疾病。

DESCRIPTION (provided by applicant): The long term objective of this proposal is to establish Dimethylarginine Dimethylaminohydrolase (DDAH), the enzyme responsible for methylarginine (MA) metabolism, as a key regulator of vascular function and the response to injury. Altered nitric oxide (NO) biosynthesis has been implicated in the pathogenesis of restenosis injury and it appears that accumulation of the endogenous nitric oxide synthase inhibitors, ADMA and NMMA, are responsible for the reduced NO generation observed in these conditions. We have shown that in both rabbit and rat models of balloon- mediated restenosis injury, vascular DDAH expression is significantly decreased with a concomitant increase in cellular MA levels. The overall hypothesis of this proposal is that the loss of DDAH expression/activity results in MA accumulation and decreased NO bioavailabilty with subsequent loss of the anti-proliferative anti-atherogenic properties afforded to the vascular wall by NO. To test this hypothesis we will pursue the following aims. In aim 1, we will define how modulation of DDAH affects methylarginine levels and subsequent NOS-derived NO and superoxide generation. In aim 2, we will determine the modulation of DDAH in vascular injury and its role in arterial remodeling. These studies will examine the effects of loss of DDAH expression on smooth muscle cell proliferation, migration and endothelial regeneration. In addition, using an AAV vector carrying the DDAH gene, we will determine whether DDAH over expression can modulate the vascular remodeling process and improve vascular function. The final aim will determine the role methylarginines in atherogenesis. Because DDAH is regulated by LDL, we will study the effects of DDAH over expression on the initiation and progression of atherosclerosis in the hyperlipidemic state. We believe that this project will establish DDAH as a critical component in the vascular response to injury and may serve as a novel therapeutic target in the treatment of vasculoproliferative disorders.