Targeting Novel BMPR2 modifiers in Pulmonary Hypertension with Repurposed Drugs

 描述（由申请人提供：我们目前主要使用血管扩张剂治疗肺动脉高压（PAH）与逆转导致肺血管阻力增加和右心衰竭的肺动脉闭塞性血管病的需要之间存在根本性差距。骨形态发生蛋白受体2（BMPR 2）信号传导越来越多地被认为是PAH的关键途径和潜在的主开关，BMPR 2表达减少与血管细胞增殖和闭塞性血管病变有关。因此，该提案的总体目标是开发新的疗法，以通过增加BMPR 2表达的新途径来逆转闭塞性血管病变。PAH患者中BMPR 2下调的机制尚不清楚。增加BMPR 2信号转导的策略在实验性肺动脉高压中显示出希望，但大多数方法在临床应用之前仍然面临许多障碍。因此，鉴定可以与再利用药物一起利用以增加BMPR 2表达的BMPR 2修饰基因将是改善PAH的有希望的策略，具有明确的治疗转化途径。我们的建议有三个重要的部分，这是由我们的三个具体目标所代表的：首先，我们将专注于新的BMPR 2修饰基因，脆性组氨酸三联体（FHIT）和淋巴细胞特异性蛋白酪氨酸激酶（LCK），我们在siRNA高表达筛选（HTS）中鉴定，不仅在PAH中功能重要，而且在PAH转录组数据库的荟萃分析中高度代表。我们的初步研究结果表明，FHIT和LCK的表达减少导致BMPR 2 mRNA表达减少，肺血管细胞功能受损。我们对肺动脉高压患者肺组织、内皮细胞和免疫细胞的研究表明，FHIT和LCK在肺动脉高压中表达下调，并改变家族性肺动脉高压的疾病发生率。其次，我们将确定如何FHIT和LCK调节BMPR 2的表观遗传和转录水平上使用候选人和无偏的分析方法。第三，我们将确定一种增加FHIT的药物，Enzaelectin，是否逆转人类血管细胞和实验性肺动脉高压的异常表型，从而为治疗转化提供一条明确的道路。我们的方法有三个创新方面：（1）概念上，我们将通过调节两种以前在PAH中未描述过的新基因来靶向BMPR 2表达;（2）技术上，我们使用了一种新的siRNA高表达筛选，该筛选尚未用于鉴定PAH中的BMPR 2修饰基因;和（3）靶向，我们将重新利用现有的药物，这不仅节省时间和费用，而且可以加快临床采用这些药物，因为监管机构提供了已知的安全和毒性信息。我们提出的研究对PAH领域的贡献非常重要，因为它利用新的途径通过重新利用以前未与受体或PAH相关的药物来调节BMPR 2基因表达。

 DESCRIPTION (provided by applicant: There is a fundamental gap between our current treatment for Pulmonary Arterial Hypertension (PAH) with primarily vasodilators, and the need to reverse the occlusive vasculopathy of pulmonary arteries that results in increased pulmonary vascular resistance and right heart failure. Increasingly, Bone Morphogenetic Protein Receptor 2 (BMPR2) signaling is recognized as a key pathway and potential master switch in PAH with reduced BMPR2 expression implicated in vascular cell proliferation and occlusive vasculopathy. The overall goal of this proposal thus is to develop new therapies to reverse the occlusive vasculopathy by novel pathways that increase BMPR2 expression. The mechanism by which BMPR2 is downregulated in PAH patients is not known. Strategies to increase BMPR2 signaling have shown promise in experimental pulmonary hypertension yet most approaches still face many obstacles before they can be used clinically. Thus, identifying BMPR2 modifier genes that could be harnessed with repurposed drugs to increase BMPR2 expression would be a promising strategy to improve PAH with a clear path to therapeutic translation. Our proposal has three significant parts, which are represented by our three specific aims: First, we will focus on novel BMPR2 modifier genes, Fragile Histidine Triad (FHIT) and Lymphocyte specific protein tyrosine Kinase (LCK) that we identified in an siRNA High Throughput Screen (HTS) and that are not only functionally important in PAH but also highly represented in a meta-analysis of PAH transcriptomic databases. Our strong preliminary data showed that decreased expression of FHIT and LCK resulted in reduced BMPR2 mRNA expression and impaired function of pulmonary vascular cells. Our studies on human PAH lung tissue, endothelial as well as immune cells suggested that FHIT and LCK are downregulated in PAH and modify disease penetrance in familial PAH. Second, we will determine how FHIT and LCK regulate BMPR2 on the epigenetic and transcriptional level using candidate and unbiased profiling assay approaches. Third, we will determine whether a drug that increases FHIT, Enzastaurin, reverses the abnormal phenotype of human vascular cells and experimental pulmonary hypertension, thus offering a clear path to a therapeutic translation. Three innovative aspects underlie our approach: (1) conceptually, we will target BMPR2 expression by modulating two novel genes that have not been describe in PAH before (2) technically, we used a novel siRNA high Throughput Screen that has not been used to identify BMPR2 modifier genes in PAH and (3) pharmacologically, we will repurpose existing drugs which not only saves time and expense but can speed their adoption in the clinic because of known safety and toxicity information from regulatory agencies. The contribution of our proposed research is highly significant to the field o PAH, as it utilizes novel pathways to regulate BMPR2 gene expression by repurposing drugs not previously linked to either the receptor or to PAH.