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，与线粒体代谢的神秘抑制有关。铁硫（Fe-S）簇是促进线粒体呼吸的假体基团，由Fe-S组装蛋白ISCU和FXN （frataxin）调节。然而，Fe-S簇在包括PH在内的大多数人类疾病中的作用尚不清楚。我们发现缺氧诱导的microRNA-210抑制ISCU，促进Fe-S缺乏、肺血管代谢失调和PH。我们还发现FXN在PH中下调，并受miR-130/301家族/PPARγ调节轴的控制。我们假设Fe-S缺乏，特别是在肺血管内皮中，是PH的关键致病关键，是遗传和获得性疾病触发的共同趋同点。我们计划对啮齿动物和人类进行体内研究，描绘新的基于铁的PH起源-即缺氧和人类ISCU和FXN遗传缺陷对ISCU/FXN的基于微rna的协调调节。具体目标:1)确定miR-130/301家族是否通过抑制FXN和Fe-S的表达来控制PH。在缺氧小鼠PH模型和培养的患病小鼠肺血管内皮细胞中，结合新的生物物理方法来测量Fe-S水平，我们将验证miR-130/301家族下调FXN以抑制Fe-S生物发生和线粒体呼吸从而促进PH的假设。这些发现将确定miR-130/301依赖的FXN控制是miR-210/ISCU轴代谢功能障碍和PH整体控制的关键补充。2)确定miR-210和miR-130/301的上调是否共同促进Fe-S集群表达的更强下调和更严重的PH表现比单独使用miRNA更明显。使用上述模型系统，我们将检验miR-210和miR-130/301的上调共同促进Fe-S完整性更强的下调和PH严重程度的增加的假设。3)确定人类ISCU和FXN突变是否直接促进PH。为了评估人类FXN或ISCU基因缺乏而无缺氧时的PH，我们计划进行高级心肺运动试验。我们还将生成/研究患者特异性诱导多能干细胞，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硫缺乏的PH风险，指导临床护理并巩固这种范式在人类中的相关性。

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.