Mechanisms of Prostacyclin signaling in Pulmonary Arterial Hypertension

肺动脉高压(PAH)的特征是肺动脉压、血管压力升高 内皮细胞的重塑和过度增殖。虽然这种疾病没有治愈或预防的方法， 较新的靶向治疗可以通过使用前列环素(PGI2)改变血管张力来改善结果 类似物，双重内皮素拮抗剂，或磷酸二酯酶-5抑制剂。生物多样性研究的最新进展 对PAH遗传异常的了解表明，修饰基因可能参与了 调解增加的敏感性和严重性。两个影响前列环素信号水平的基因， 前列环素合成酶(PGIs)和核受体PPARy在PAH患者中表达下调。 通过PPARy途径破坏PGI2信号导致细胞异常生长。我们的假设 建议PGI2可以通过PGIR或PPARy发出信号。我们假设通过PGIR发出的信号 PPARy刺激对血管张力的影响更显著，而PPARy刺激对血管的影响更显著 改建。该建议侧重于1)通过两个不同的 前列腺素I2受体逆转PAH血管内皮细胞重构的研究 (PPARy)或血管紧张性(PGIR)，2)PGI和基因在赋予 多环芳烃的易感性和发生严重多环芳烃的可能性增加，以及3)PGIs的机制 和PPARY在人类疾病中表达缺失。我们将使用两个复杂的小鼠建模系统 分析这两种受体在PAH发生发展中的相对作用。 我们的初步工作表明，近端PGIS启动子区域的序列变异会影响 启动子活性导致PGI低表达。我们将对家族中的PGIs启动子进行测序 肺动脉高压，特定的单倍型与疾病发生、严重程度和发病率的相关性。最后， 因为表观遗传沉默和染色体丢失是基因表达下调的常见机制- 在微观解剖中，我们将确定是否对PGIs或PPARy下调负责 用甲基化特异性聚合酶链式反应(MSP)和荧光原位杂交(FISH)检测PAH病变。特定的 目的1：探讨PGIs和PPARy途径对PAH易感性和严重程度的影响。特定的 目的2：确定PGIS启动子序列变异在相关原代细胞类型中的转录活性， 以及它们在特定人群中的频率和相关性。具体目标3：确定甲基化是否 沉默和/或等位基因丢失是PGIs和PPARy下调的原因。 相关性(请参阅说明)： 我们先前已经证明，血管张力和增殖的两个关键调节因子(PGI2和PGI2 PPAR-/)在疾病中表达下调。这个应用程序利用翻译小鼠建模来检查 对血管紧张素和重塑很重要的信号机制。此外，对慢性阻塞性肺疾病患者的研究 将进行PAH以检查遗传多态与疾病严重程度的关系，如 以及PGI2和PPARy的丢失机制。

Pulmonary Arterial Hypertension (PAH) is characterized by elevations in pulmonary artery pressure,vascular remodeling, and hyperproliferation of endothelial cells. While there is no cure or prevention for this disease, newer targetedtherapies can improve outcomes by altering vascular tone using prostacyclin (PGI2) analogues, dual endothelin antagonists, or phosphodiesterase - 5 inhibitors. Recent progress inthe understanding of genetic aberrations in PAH suggests that modifier genes are potentially involved in mediating increased susceptibility and severity. Two genes that affect the level of prostacyclin signaling, prostacyclin synthase (PGIS) and the nuclear receptor PPARy, are down-regulated in patients with PAH. Disruption of PGI2 signaling through the PPARy pathway leads to aberrant cell growth. Our hypothesis proposes that PGI2 can signal through either PGIR or PPARy. We hypothesize that signaling through PGIR results in more prominent effects on vascular tone while PPARy stimulation results in effects onvascular remodeling. This proposal focuses on 1) the effectiveness of augmenting signaling through the two different PGI2 receptors as a treatment to reverse remodeling of both smooth muscle and endothelial cells in PAH (PPARY) or vascular tone (PGIR), 2) the potential modifier gene role of the PGIS and gene in conferring a predisposition to PAH and an increased likelihood of developing severe PAH,and 3) the mechanism of PGIS and PPARy loss of expression in human disease. We will use two sophisticated murine modeling systems generated by our group to dissect the relative contribution of the two receptors to the development of PAH. Our preliminary work demonstrates that sequence variation in the proximal PGIS promoter region affects promoter activity leading to low PGIS expression. We will sequence the PGIS promoters from familial pulmonary hypertension, correlating specific haplotypes with disease on-set, severity, and morbidity. Finally, because epigenetic silencing and chromosomal loss are common mechanisms of gene expression down- regulation, we will determine if either is responsible for PGIS or PPARy down-regulation in micro-dissected PAH lesions using methylation specific PCR (MSP) and fluorescence in situ hybridization (FISH). Specific Aim 1: Delineate the contributions of PGIS and PPARy pathwaysto PAH susceptibility and severity. Specific Aim 2: Define transcriptional activity of PGIS promoter sequence variations in relevant primary cells types, and their frequency and correlation in a defined human population. Specific Aim 3: Determine if methylation silencing and/or allelic loss account for PGIS and PPARy down-regulation. RELEVANCE (See instructions): We have previously demonstrated that two critical modulators of vascular tone and proliferation (PGI2 and PPAR-/) are downregulated in disease. This application utilizes translational murine modeling to examine mechanisms of signaling important to vasculartone and remodeling. Furthermore, studies of patients with the PAH will be performed to examine the relationship of genetic polymorphisms and disease severity, as well as mechanisms of loss of PGI2 and PPARy.