Heme Oxygenase Regulation of Eicosanoid Biosynthesis

描述(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)在正常血压和高血压大鼠肾血管调节中的作用。HO-1和HO-2催化血红素分解为一氧化碳(CO)，一氧化碳是血管扩张剂和抗凋亡因子，胆绿素/胆红素是抗氧化剂，可对抗氧化应激损伤。我们已经获得证据表明，HO-1是保护内皮的关键因素；它的活性改善了血管功能，改善了高血压的遗传性和实验性形式。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减少。此外，通过减少HO-1和/或HO-2的表达来抑制HO活性应该会导致内皮功能障碍，即内皮细胞塌陷，氧化剂的产生，炎症分子的表达，以及血管对升压激动剂的反应性增加。这些假说将通过分子遗传学探针(逆转录病毒/慢病毒载体)在体内外进行验证，即：1)靶向HO-1和HO-2的表达以确定其在血管紧张素转换酶II诱导的内皮损伤中的作用，并探讨其在血管紧张素转换酶II诱导的内皮损伤中的作用机制；2)确定选择性改变HO-1或HO-2基因表达对高血压大鼠和HO-2基因敲除小鼠血管内皮细胞功能的影响；3)检测HO-1过表达是否能保护SHR及肾血管病变的内皮功能，延缓高血压的发展。如果是，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。这项提议将首次允许在相对正常的环境中深入分析HO-1和HO-2的功能，而不需要对生殖系进行操纵。如果HO系统预期的有益血管作用是正确的，那么这些发现可能被应用于基于基因靶向的高血压和心血管疾病治疗的创新疗法的开发。

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.