Iron-Sulfur Deficiency as a Critical Pathogenic Cause of Pulmonary Hypertension

描述(申请人提供)：肺动脉高压(PH)是一种致命的血管疾病，与神秘的线粒体代谢抑制有关。铁-硫(Fe-S)簇是促进线粒体呼吸的修复基团，受铁-S组装蛋白Iscu和Fxn(Frataxin)的调节。然而，铁-S簇在包括PH在内的大多数人类疾病中的作用尚不清楚。我们发现，低氧诱导的microRNA-210抑制ISCU，促进铁-S缺乏，肺血管代谢紊乱，以及PH。我们还发现，FXN在PH中下调，并受miR130/301家族/PPARγ调节轴的调控。我们推测，铁-S缺乏，特别是肺血管内皮细胞缺乏，是PH的关键致病关键因素，是遗传和获得性疾病触发因素的共同汇合点。我们计划在活体内研究啮齿动物和人类，描绘基于Fe-S的PH的新来源-即缺氧和人类Iscu和FXN的遗传缺陷对Iscu/FXN的协调MicroRNA调控。具体目的：1)确定miR-130/301家族是否抑制FXN和Fe-S的表达，从而控制PH。在缺氧性肺高压小鼠模型和培养的肺血管内皮细胞中，结合新的生物物理方法测定铁-S水平，我们将检验这一假设，即miR-130/301家族下调FXN，以抑制铁-S的生物发生和线粒体呼吸，从而促进肺高压。这些发现将确认依赖miR-130/301对FXN的控制是代谢功能障碍和PH总体控制中miR-210/ISCU轴的关键补充。2)确定miR-210和miR-130/301的共同上调是否比单独的miRNA更能促进Fe-S簇表达的下调和更严重的PH表现。使用上面的模型系统，我们将检验这一假设，即miR-210和miR-130/301的上调共同促进Fe-S完整性的下调和PH严重性的增加。这一结果对于制定针对PH患者的microRNAs协同治疗靶向的路线图将是非常有价值的。3)确定人类ISCU和FXN突变是否直接促进PH。为了评估没有缺氧的FXN或ISCU的人类遗传缺陷的PH，我们计划进行先进的心肺运动试验。我们还将生成/研究患者特定的可诱导多能干细胞，以确定突变如何控制肺血管功能。这种罕见的分子研究和患者测试的结合应该确定铁-S缺乏症的PH风险，指导临床护理，并巩固这一范例在人类中的相关性。 意义：这项提议结合了铁-S生物学的严谨专业知识和新技术进步，并提供了将机械发现直接转化为人类的难得机会。我们的目标是坚定地确立铁-S缺乏症是一种强大的、新的代谢性疾病来源，是PH的新治疗靶点，并为发现其他具有相似缺氧和代谢基础的疾病奠定基础。

DESCRIPTION (provided by applicant): Pulmonary hypertension (PH) is a deadly vascular disease linked to an enigmatic repression of mitochondrial metabolism. Iron-sulfur (Fe-S) clusters are prosthetic groups that promote mitochondrial respiration and are regulated by the Fe-S assembly proteins ISCU and FXN (frataxin). Yet, the roles of Fe-S clusters in most human diseases including PH are unknown. We found that hypoxia-induced microRNA-210 represses ISCU, promoting Fe-S deficiency, pulmonary vascular metabolic dysregulation, and PH. We also found that FXN is down-regulated in PH and is controlled by the miR-130/301 family/PPARγ regulatory axis. We hypothesize that Fe-S deficiency, particularly in pulmonary vascular endothelium, is a critical pathogenic lynchpin of PH and is a common convergence point of genetic and acquired disease triggers. We plan to study both rodents and humans in vivo, delineating novel Fe-S-based origins of PH - namely, the coordinated microRNA-based regulation of ISCU/FXN by hypoxia and human genetic deficiencies of ISCU and FXN. Specific Aims: 1) Determine whether the miR-130/301 family represses FXN and Fe-S expression in order to control PH. In a hypoxic mouse model of PH and cultured pulmonary vascular endothelial cells from diseased mice coupled with novel biophysical assays to measure Fe-S levels, we will test the hypothesis that the miR-130/301 family down-regulates FXN in order to repress Fe-S biogenesis and mitochondrial respiration and thus promote PH. Such findings would identify miR-130/301-dependent control of FXN as a critical complement to the miR-210/ISCU axis in metabolic dysfunction and in the overall control of PH. 2) Determine whether up-regulation of miR-210 and miR-130/301 together promotes more robust down- regulation of Fe-S cluster expression and more severe PH manifestation than either miRNA alone. Using the model systems above, we will test the hypothesis that up-regulation of miR-210 and miR-130/301 together promote more robust down-regulation of Fe-S integrity and increased PH severity. Results would be invaluable for developing a roadmap for synergistic therapeutic targeting of microRNAs in PH. 3) Determine whether mutations of ISCU and FXN in humans directly promote PH. To assess for PH in human genetic deficiency of FXN or ISCU without hypoxia, we plan advanced cardiopulmonary exercise tests. We will also generate/study patient-specific inducible pluripotent stem cells to determine how the mutations control pulmonary vascular function. This rare combination of molecular study and patient testing should define PH risk in Fe-S deficiency, guiding clinical care and solidifying this paradigm's relevance in humans. Significance: This proposal incorporates rigorous expertise and new technological advancements in Fe-S biology coupled with a rare opportunity to translate mechanistic findings directly to humans. We aim to firmly establish Fe-S deficiency as a powerful and novel metabolic disease origin, a new therapeutic target for PH, and a foundation for discovery in other diseases that share similar hypoxic and metabolic underpinnings.