Effects of Statins on Heme Oxygenase-1 Regulation

描述（由申请人提供）：抗氧化防御蛋白血红素加氧酶-1 （HO-1）近年来作为组织保护和抗炎作用的重要介质而出现。HO-1的细胞保护功能已在多种组织中得到证实，包括脉管系统、心脏、肾脏和神经元细胞。HO-1是一种诱导酶，它催化血红素的降解，导致胆红素、铁和一氧化碳（CO）的产生，这些都是生物活性产物。胆红素在生理浓度下具有很强的抗氧化作用。同样，CO也被证明具有抗凋亡和细胞保护作用，此外，还具有平滑肌松弛介质的功能。组织保护和平滑肌放松特性的独特组合使HO-1成为治疗妊娠期某些疾病的有趣靶点。研究表明，在怀孕期间，HO-1对于保持人类子宫处于放松状态至关重要。此外，胎盘HO-1水平的降低似乎与先兆子痫的高风险有关。因此，旨在适度增加组织HO-1表达的治疗策略可能对许多疾病状态有益，包括与妊娠和人类发育有关的疾病。然而，已知的HO-1诱导剂，如重金属或氧化应激介质，对组织有害，不适合用于治疗目的。HMG-CoA还原酶抑制剂，广泛用作降脂药物（他汀类药物），诱导HO-1表达，从而减少氧化应激。因此，他汀类药物或其衍生物可能在与HO-1表达不足相关的病理条件下具有治疗益处。在本项目中，我们将使用转基因（Tg）小鼠，其中转基因由HO-1启动子融合到荧光素酶报告基因中，研究他汀类药物依赖性HO-1在体内的诱导作用，特别是确定哪些器官和组织对HO-1表达增加做出反应。此外，我们将通过体内转染HO-1缺失突变体的小鼠，确定HO-1启动子中调节他汀类药物反应性的区域。他汀类药物的体内作用将通过两种无创检测来监测：全身CO排泄（胆红素生成指数）；生物发光成像（BLI），这是HO-1转录的指标。这些体内试验的数据将与体外HO-1和HO-2 mRNA和蛋白质水平以及总HO酶活性的测定相关联。这将是首次共同努力描绘HO-1作为他汀类药物的新治疗靶点和在HO-1表达不足的情况下（如先兆子痫和其他妊娠相关疾病）的保护作用介质的作用

DESCRIPTION (provided by applicant): The antioxidant defense protein heme oxygenase-1 (HO-1) has emerged in recent years as an important mediator of tissue protective and anti-inflammatory actions. Cytoprotective functions of HO-1 have been documented in a variety of tissues including the vasculature, heart, kidney, and neuronal cells. HO-1 is an inducible enzyme that catalyzes the degradation of heme, leading to the generation of bilirubin, iron, and carbon monoxide (CO), which are, in turn, all bioactive products. Bilirubin exerts strong antioxidant effects at physiological concentrations. CO has likewise been shown to produce anti-apoptotic and cytoprotective actions and, in addition, to function as a smooth muscle relaxing mediator. The unique combination of tissue protective and smooth muscle relaxing properties makes HO-1 an interesting target for treatment of certain disorders in pregnancy. It has been shown that HO-1 is crucial for keeping the human uterus in a relaxed state during pregnancy. Moreover, a reduced level of placental HO-1 seems to be associated with a higher risk for pre-eclampsia. Thus, therapeutic strategies aimed at moderately increasing tissue expression of HO-1 might be beneficial in a number of disease states including those related to pregnancy and human development. However, known inducers of HO-1, such as heavy metals or mediators of oxidative stress, are detrimental to tissues and not suitable for therapeutic purposes. HMG-CoA reductase inhibitors, widely used as lipid-lowering drugs (statins), induce HO-1 expression and, as a consequence reduce oxidative stress. Thus, statins or their derivatives might be of therapeutic benefit under pathological conditions associated with insufficient HO-1 expression. In this project, we will use transgenic (Tg) mice where the transgene consists of the HO-1 promoter fused to the luciferase reporter gene to study statin-dependent HO-1 induction in vivo, and, specifically, to determine which organs and tissues respond with increased HO-1 expression. Moreover, we will identify regions in the HO-1 promoter that regulate statin responsiveness by using mice transfected in vivo with HO-1-derived deletion mutants. The in vivo effects of statins will be monitored by two noninvasive assays: total body CO excretion, an index of bilirubin production; and bioluminescence imaging (BLI), an index of HO-1 transcription. Data from these in vivo assays will be correlated with in vitro assays of HO-1 and HO-2 mRNA and protein levels and total HO enzyme activity. This will be the first concerted effort to delineate the role of HO-1 as a novel therapeutic target for statins and mediator of protective effects under conditions of insufficient HO-1 expression such as pre-eclampsia and other pregnancy-related disorders