Heme Oxygenase Regulation of Eicosanoid Biosynthesis

描述（由申请人提供）：我们打算研究血管血红素加氧酶（HO）同工酶（HO-1, HO-2）在正常和高血压大鼠肾血管的调节中的作用。HO-1和HO-2催化血红素分解为一氧化碳（CO），一种血管舒张剂和抗凋亡因子，以及胆绿素/胆红素，一种对抗氧化应激损伤的抗氧化剂。我们已经获得证据表明HO-1是内皮细胞防御的关键因子；它的活性可以改善血管功能，改善遗传性和实验性高血压。我们假设HO-1的过度表达导致血管紧张素II （Ang II）介导的氧化应激持续下降。此外，通过减少HO-1和/或HO-2表达来抑制HO活性可能会产生内皮功能障碍；即内皮细胞脱落、氧化剂产生、炎症分子的表达和血管对压力激动剂的反应性增加。这些假设将通过分子遗传探针（逆转录病毒/慢病毒载体）在遗传和实验性高血压模型中进行体外和体内验证，即：1)靶向HO-1和HO-2表达，确定它们在保护内皮免受Ang ii诱导损伤中的作用并探索它们的作用机制；2)确定选择性改变HO-1转基因大鼠和HO-2敲除小鼠HO-1或HO-2表达的基因干预对内皮功能的影响；3)研究HO-1过表达是否能保护SHR和肾血管病变中的内皮功能并减轻高血压的发生。如果是这样，将寻求作用机制；4)确定HO-1靶向内皮是否足以抵消Ang ii诱导的血管损伤。这一提议将首次允许在相对正常的情况下深入分析HO-1和HO-2的功能，而无需对生殖系进行操作。如果预期的HO系统的有益血管作用是正确的，那么这些发现可能应用于基于基因靶向治疗高血压和心血管疾病的创新疗法的开发。

DESCRIPTION (provided by applicant): We intend to investigate the participation of vascular heme oxygenase (HO) isoenzymes (HO-1, HO-2) in the regulation of the renal vasculature in normotensive and hypertensive rats. HO-1 and HO-2 catalyze the breakdown of heme to carbon monoxide (CO), a vasodilator and antiapoptotic factor, and biliverdin/bilirubin, antioxidants that act to countervail oxidative stress injury. We have obtained evidence that HO-1 is key factor to the defense of the endothelium; its activity improves vascular function and ameliorates both genetic and experimental forms of hypertension. We hypothesize that overexpression of HO-1 leads to a persistent decrease in angiotensin II (Ang II)-mediated oxidative stress. Further, suppression of HO activity by diminishing HO-1 and/or HO-2 expression should produce endothelial dysfunction; namely, endothelial cell sloughing, oxidant generation, expression of inflammatory molecules and increased vascular reactivity to pressor agonists. These hypotheses will be tested in vitro and in vivo in models of genetic and experimental hypertension with molecular genetic probes (retroviral/lentiviral vectors), namely: 1) Targeting HO-1 and HO-2 expression to define their roles and to explore their mechanisms of action in protecting the endothelium from Ang II-induced injury; 2) Determining the effect of genetic interventions, which selectively alter HO-1 or HO-2 expression on endothelial function in HO-1 transgenic rats and HO-2 knockout mice; 3) Examining whether overexpression of HO-1 protects endothelial function and attenuates the development of hypertension in the SHR and in renovascular lesions. If so, the mechanism of action will be sought; 4) Determining whether targeting of the endothelium with HO-1 is sufficient to offset Ang II-induced vascular injury. This proposal will allow, for the first time, an in-depth analysis of the function of HO-1 and HO-2 in a relatively normal setting, without germ line manipulation. If the anticipated beneficial vascular actions of the HO system are correct, then these findings may be applied to the development of innovative therapies based on gene targeting for the treatment of hypertension and cardiovascular disease.