Role of SIN3a in the epigenetic regulation of the Bone Morphogenetic Protein Receptor Type 2 in pulmonary arterial hypertension

项目摘要 PAH是一种致命的疾病，其特征是远端肺血管的进行性重塑。 导致肺血管阻力和肺动脉压升高，这可能导致严重的 并发症，如右心衰竭，最终死亡。越来越多的证据表明，内皮细胞 功能障碍是导致血管细胞不受控制的增殖的PAH的首要触发因素之一 肺血管重塑和闭塞。PAH最常见的发病机制之一 是血管细胞中骨形态发生蛋白2型受体(BMPR2)信号的改变。这个 由突变或表达缺失引起的BMPR2功能丧失与严重的血流动力学有关 PAH患者的概况和不良结局。多项研究指出，肺内皮细胞是细胞类型 这是受PAH中BMPR2缺失的影响最严重的。然而，潜在的分子机制 BMPR2表达的调节及其相关的PAH样表型在很大程度上仍不清楚。我们的团队已经 最近发现SIN3a在BMPR2启动子的DNA和组蛋白甲基化中起核心作用 肺血管平滑肌细胞与肺动脉高压的发病机制。然而，表观遗传和转录 SIN3a调控PAEC中BMPR2基因的机制尚不清楚。 建议揭示SIN3a在肺内皮细胞功能障碍中的作用 我们在这方面的目标 在PAH中，确定 BMPR2在PAEC中表达调控的下游机制及其治疗评价 修饰SIN3a基因在PAH动物模型中的作用我们的初步数据显示SIN3a是 从PAH患者中分离的hPAEC表达显著下调。在体外，我们观察到SIN3a沉默 下调BMPR2的表达和信号转导，同时促进PAEC的增殖和迁移。 从机制上，我们发现了SIN3a调节hPAECs中BMPR2水平的一条新的分子途径。 我们的数据表明，SIN3a过表达通过抑制Zust Homolog 2的增强子上调FOXK2 (EZH2)介导组蛋白在FOXK2启动子中的甲基化。最终，SIN3a过度表达增加 FOXK2与BMPR2启动子结合并上调hPAECs中BMPR2水平。基于这些发现， 我们推测SIN3a的缺失损害了PAEC中BMPR2的表达，触发了内皮细胞 PAH中的功能障碍和血管重塑。在这个提案中，我们的假设将通过追求 目的1)探讨SIN3a在血管内皮细胞功能障碍中的作用 BMPR2在PAH-hPAEC中调控的分子机制目的2)阐明这些影响 采用双重方法研究SIN3a缺乏症在血管内皮细胞和血管内皮细胞中的PAH起始。目标 3)评价SIN3a modRNA对PAH临床前模型的治疗效果。定义监管机构 PAH中BMPR2表达缺失的机制将具有重要意义。最后，恢复 利用SIN3a修饰的RNA在肺组织中表达SIN3a可能是治疗PAH的一种新策略。

Project Summary PAH is a fatal disease characterized by the progressive remodeling of the distal pulmonary vascular arteries, resulting in elevated pulmonary vascular resistance and pulmonary artery pressure, which may lead to serious complications, such as right heart failure, and ultimately death. Accumulating evidence indicates that endothelial dysfunction is one of the first triggers in PAH that leads to uncontrolled proliferation of vascular cells, vascular remodeling, and occlusion of the pulmonary blood vessels. One of the most common pathomechanisms in PAH is the alteration of the Bone Morphogenetic Protein Type 2 Receptor (BMPR2) signaling in vascular cells. The loss of BMPR2 function, induced by mutation or a loss of expression, is associated with a severe hemodynamic profile and poor outcomes in PAH patients. Multiple studies point to the pulmonary endothelium as the cell type that is most critically impacted by BMPR2 loss in PAH. However, the molecular mechanisms underlying the regulation of BMPR2 expression and its associated PAH-like phenotype remain largely unknown. Our group has recently shown that SIN3a plays a central role in the DNA and histone methylation of the BMPR2 promoter in pulmonary artery smooth muscle cells and the pathogenesis of PAH. However, the epigenetic and transcriptional mechanisms by which SIN3a regulates the BMPR2 gene in PAEC remain to be elucidated. proposal are to uncover the role of SIN3a in the pulmonary endothelial dysfunction Our objectives in this in PAH, identify the downstream mechanisms underlying the regulation of BMPR2 expression in PAEC, and evaluate the therapeutic effects of modified mRNA encoding SIN3a in animal models of PAH. Our preliminary data showed that SIN3a is significantly downregulated in hPAEC isolated from PAH patients. In vitro, we observed that SIN3a silencing downregulates BMPR2 expression and signaling while potentiating PAEC proliferation and migration. Mechanistically, we discovered a novel molecular pathway by which SIN3a modulates BMPR2 levels in hPAECs. Our data showed that SIN3a overexpression upregulates FOXK2 by repressing Enhancer of Zeste Homolog 2 (EZH2)-mediated histone methylation in the FOXK2 promoter. Ultimately, SIN3a overexpression increases FOXK2 binding to the BMPR2 promoter and upregulates BMPR2 levels in hPAECs. Based upon these findings, we hypothesize that the loss of SIN3a impairs BMPR2 expression in PAEC, triggers endothelial dysfunction and vascular remodeling in PAH. In this proposal, our hypothesis will be tested by pursuing the following three specific aims: Aim 1) To investigate the role of SIN3a in endothelial cell dysfunction and decipher the molecular mechanism underlying the regulation of BMPR2 in PAH-hPAEC. Aim 2) To elucidate the effects of SIN3a deficiency in the onset of PAH in smooth muscle cells and endothelial cells using a dual approach. Aim 3) To evaluate the therapeutic efficacy of SIN3a modRNA in preclinical models of PAH. Defining the regulatory mechanisms underlying the loss of BMPR2 expression in PAH will be of great relevance. Finally, restoring the expression of SIN3a in the lungs using SIN3a modified RNA might be a new promising strategy for treating PAH.