硫氧还原蛋白对血管内皮功能的重要作用和机制探讨

Vascular endothelial cell injury and dysfunction play contribute to the development and progression of cardiovascular diseases. The endogenous nitric oxide (NO) synthase inhibitor asymmetrical dimethylarginine (ADMA) is a potent independent risk predictor for various cardiovascular diseases. We have found that dimethylarginine dimethylaminohydrolase-1 (DDAH1) is the critical enzyme for ADMA degradation, and DDAH1 plays an important role in regulating vascular NO bioavailability, vascular endothelial injury repair and vessel dilation. Our preliminary studies demonstrate that DDAH1 is a member of a protein complex that also includes eNOS, peroxiredoxin-1, and sulfiredoxin (Srx, an enzyme that protects peroxiredoxin from inactivation). One fascinating finding is that DDAH1 binding to peroxiredoxin-1 and Srx is dramatically increased by oxidative stress such as H2O2 treatment. We hypothesize that Srx plays an important role in protecting DDAH1 and peroxiredoxin-1 function, thereby optimizing eNOS-derived NO production, and minimizing eNOS derived superoxide anion generation. We will use novel gene deficient mouse strains in combination with in vitro studies to examine the important roles and the underlying molecular mechanism of Srx1 in regulating vascular endothelial DDAH1 activity, NO bioavailability, eNOS uncoupling and endothelial function. The proposed studies will provide unique new knowledge defining the previously unexplored molecular pathways by which Srx and its binding proteins regulate vascular NO production and oxidative stress.

血管内皮细胞损伤和功能紊乱对心血管疾病发生发展具有重要作用。内源性一氧化氮合酶抑制剂ADMA 是多种心血管疾病的独立致病危险因子。我们前期工作证实二甲基精氨酸二甲胺水解酶1（DDAH1）对组织内ADMA的降解具有核心作用。DDAH1对维护血管内皮细胞eNOS活性和内皮修复具有重要作用。DDAH1是一种氧化应激敏感酶，我们前期工作同时发现DDAH1可与Prx1、eNOS和硫氧还原蛋白（Srx）结合成一个蛋白复合体，可降低H2O2诱导的氧化应激。我们认为硫氧还原蛋白Srx对于抑制血管内皮细胞eNOS解偶联导致的氧自由基产生，保护DDAH1酶活力，提高NO生物可利用率及维持血管内皮功能正常具有重要作用。我们将利用相应基因敲除动物和体外培养的内皮细胞，在动物、细胞和分子等水平深入研究Srx在维持血管内皮损伤后修复和血管再生的作用及其作用机制。

血管内皮细胞损伤和功能紊乱是诸多心血管疾病发生的病理基础。硫氧还原蛋白Srx与Prx1/DDAH1/eNOS结合形成一个功能协助聚合体，协同有效地控制内皮细胞局部微环境内的过氧化物和ADMA水平，得以创造一个良好的维持血管内皮功能的微环境。我们的研究发现DDAH1表达增加可提高其与Srx和Prx蛋白间的相互作用，而降低DDHA1的表达则减弱这种蛋白间的相互作用。细胞水平改变Srx的表达，可影响内皮细胞增殖、迁移、氧化应激、细胞损伤以及ADMA和NO水平。利用Srx基因敲除小鼠，采用颈动脉损伤模型和后肢缺血模型研究发现，Srx的缺失减弱内皮损伤再修复和内皮功能维持。本研究对于我们深入了解血管内皮氧化应激、NO可利用率降低和血管内皮功能异常及失稳态的过程和机理，有助于从预防血管稳态失衡中的过程中寻找调控手段，发掘新的血管损伤性疾病的干预靶点。在本项目的支持下，我们进行了CD40参与肺脏炎症调节左心衰至右心室肥厚和衰竭发展的作用机制研究，结果发现，CD40敲除导致心衰小鼠肺脏血小板过度活化与聚集，可能在心衰晚期凝血系统显著活化和血栓形成风险增加等方面起关键作用。