Mechanisms of Prostacyclin signaling in Pulmonary Arterial Hypertension

肺动脉高压（PAH）的特征在于肺动脉压力、血管压力和肺动脉压力的升高。 重塑和内皮细胞过度增殖。虽然没有治愈或预防这种疾病， 新的靶向治疗可以通过使用前列环素（PGI 2）改变血管张力来改善预后 类似物、双重内皮素拮抗剂或磷酸二酯酶-5抑制剂。最近的进展 对PAH中遗传畸变的理解表明，修饰基因可能参与了PAH的发生， 介导增加的易感性和严重性。两个影响前列环素信号水平的基因， 前列环素合酶（PGIS）和核受体PPARy在PAH患者中下调。 通过PPARy途径破坏PGI 2信号传导导致异常细胞生长。我们的假设 提出PGI 2可以通过PGIR或PPARy发出信号。我们假设通过PGIR的信号传导 导致对血管张力的更显著的作用，而PPARy刺激导致对血管张力的作用， 重塑该提议集中于1）通过两种不同的通信协议增强信令的有效性。 PGI 2受体作为逆转PAH中平滑肌和内皮细胞重塑的治疗 （PPARY）或血管张力（PGIR），2）PGIS和基因在赋予血管张力方面的潜在修饰基因作用 PAH易感性和发生重度PAH的可能性增加，以及3）PGIS的机制 和人疾病中的PPARy表达缺失。我们将使用两个复杂的小鼠建模系统 我们的小组所产生的，以解剖的相对贡献的两个受体的发展PAH。 我们的初步工作表明，近端PGIS启动子区的序列变异影响了PGIS基因的表达。 启动子活性导致低PGIS表达。我们将对家族性PGIS启动子进行测序， 肺动脉高压，将特定单倍型与疾病发作、严重程度和发病率相关联。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， 调节，我们将确定是否负责PGIS或PPARy下调在显微解剖的 使用甲基化特异性PCR（MSP）和荧光原位杂交（FISH）检测PAH病变。具体 目的1：阐明PGIS和PPARy通路对PAH易感性和严重程度的作用。具体 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 沉默和/或等位基因丢失导致PGIS和PPARy下调。 相关性（参见说明）： 我们以前已经证明了血管张力和增殖的两个关键调节剂（PGI 2和PGI 3）， PPAR-1）在疾病中下调。本申请利用翻译鼠模型来检查 对血管紧张素和重塑重要的信号传导机制。此外，对患有 将进行PAH检查，以检查遗传多态性与疾病严重程度的关系， 以及PGI 2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.