DDAH1 effects on endogenous NOS inhibitors and vascular endothelial function

描述(申请人提供)：内源性一氧化氮合酶抑制物不对称二甲基精氨酸(ADMA)和Ng-单甲基-L-精氨酸(L-NMMA)是导致高血压、冠状动脉疾病、中风、糖尿病和动脉粥样硬化等心血管疾病的主要危险因素。这些内源性一氧化氮合酶抑制剂与L精氨酸竞争抑制一氧化氮合酶产生NO。ADMA和L-NMMA主要被二甲精氨酸二甲氨基水解酶(DDAH)清除，少量来自肾脏排泄。据报道，ADMA和L-NMMA都被DDAH1和DDAH2降解，但DDAH1和DDAH2的相对贡献一直存在争议。此外，DDAH1对血管功能的影响是否超出了对NO产生的调节，目前尚不清楚。利用本实验室建立的新的组织特异性DDAH1缺陷小鼠和全局DDAH1基因缺陷小鼠，我们的初步数据表明，DDAH1在降解内源性NOS抑制剂方面发挥着重要作用，并且分布在内皮细胞中的DDAH1在调节血管内皮细胞NO的产生和内皮细胞的生长和损伤修复方面发挥着重要作用。最有趣的是，我们的初步数据进一步表明，DDAH1还通过一种不依赖内源性NOS抑制剂降解的新的分子途径来调节内皮细胞的功能。基于这些新发现，我们建议检验两个假设。首先，我们假设DDAH1是降解ADMA和L-NMMA的主要酶。第二，我们假设DDAH1在降解ADMA和L-NMMA的作用之外还发挥着额外的作用，调节血管内皮细胞的生长和损伤修复。为了验证这些假设，我们产生了一个新的组织特异性内皮-DDAH1 KO(Endo-DDAH1 KO)小鼠品系和一个全球DDAH1 KO小鼠品系。建议的研究将利用体外和体内的方法，为内源性一氧化氮合酶抑制物的功能以及DDAH1维持血管内皮细胞生长和损伤修复的新的分子机制提供新的见解。 公众健康相关性：内源性一氧化氮合酶抑制物不对称二甲基精氨酸和L-单甲基-L精氨酸的积聚是导致高血压、冠状动脉疾病、中风、糖尿病和动脉粥样硬化等心血管疾病的主要危险因素。DDAH1降解ADMA和L-NMMA以增加一氧化氮的产生。拟议的研究将结合体外和体内的方法，为内源性一氧化氮合酶抑制物的功能以及DDAH1维持血管内皮细胞生长和损伤修复的新分子机制提供新的见解。

DESCRIPTION (provided by applicant): Accumulation of the endogenous NO synthase (NOS) inhibitors asymmetric dimethyl arginine (ADMA) and Ng-monomethyl-L-arginine (L-NMMA) is a major risk factor for cardiovascular diseases including hypertension, coronary artery disease, stroke, diabetes and atherosclerosis. These endogenous NOS inhibitors compete with L-arginine to inhibit NO production by NOS. ADMA and L-NMMA are eliminated principally by dimethylarginine dimethylaminohydrolase (DDAH) with a small contribution from renal excretion. It is reported that ADMA and L-NMMA are degraded by both DDAH1 and DDAH2, but the relative contributions of DDAH1 and DDAH2 have been controversial. Furthermore, whether DDAH1 can exert effects on vascular function beyond regulation of NO production is unknown. Using novel tissue specific DDAH1 deficient mice and global DDAH1 gene deficient mice generated in our laboratory, our preliminary data demonstrate that DDAH1 plays an essential role in degrading the endogenous NOS inhibitors, and that DDAH1 distributed in endothelial cells plays an important role in regulating vascular endothelial NO production and endothelial cell growth and injury repair. Most interestingly, our preliminary data further demonstrated that DDAH1 also regulates endothelial cell function through a novel molecular pathway independent of degradation the of endogenous NOS inhibitors. Based on these new findings, we propose to test two hypotheses. First, we hypothesize that DDAH1 is the principal enzyme responsible for degrading ADMA and L-NMMA. Second, we hypothesize that DDAH1 exerts additional actions beyond its role in degrading ADMA and L-NMMA that regulate vascular endothelial cell growth and injury repair. To test these hypotheses, we have generated a novel tissue specific endothelial-DDAH1 KO (endo-DDAH1 KO) mouse strain and a global DDAH1 KO mouse strain. The proposed studies will utilize in vitro and in vivo approaches to provide new insight into the function of the endogenous NOS inhibitors, as well as novel molecular mechanisms by which DDAH1 acts to maintain vascular endothelial cell growth and injury repair. PUBLIC HEALTH RELEVANCE: Accumulation of the endogenous nitric oxide synthase (NOS) inhibitors asymmetric dimethyl arginine (ADMA) and Ng-monomethyl-L-arginine (L-NMMA) is a major risk factor for cardiovascular diseases including hypertension, coronary artery disease, stroke, diabetes and atherosclerosis. DDAH1 degrades ADMA and L-NMMA to increase nitric oxide production. The proposed studies will integrate in vitro and in vivo approaches to provide new insight into the function of the endogenous NOS inhibitors, as well as novel molecular mechanisms by which DDAH1 acts to maintain vascular endothelial cell growth and injury repair.