Prostacyclin Synthase and Receptors in Pulmonary Arterial Hypertension

描述（由申请人提供）：肺动脉高压（PAH）的特征是肺动脉压升高、血管重构和内皮细胞过度增殖。虽然目前还没有治愈或预防这种疾病的治疗方法，但新的靶向治疗可以通过使用前列环素（PGI2）类似物、双重内皮素拮抗剂或磷酸二酯酶- 5抑制剂改变血管张力来改善结果。最近对多环芳烃遗传畸变的了解表明，这是一种复杂的疾病，修饰基因可能参与介导易感性和严重程度的增加。影响前列环素信号水平的两个基因，前列环素合成酶（PGIS）和核受体PPAR？，在PAH患者中是下调的。通过PPAR破坏PGI2信号？通路导致异常细胞生长。我们的假设提出PGI2可以通过PGIR或PPAR发出信号。我们假设通过PGIR的信号传导对血管张力（右心室压力、右心室肥大）的影响更为显著，而PPAR？刺激对血管重塑的影响更大。本文提出的研究重点是1)通过两种不同的PGI2受体增强信号传导的有效性，作为逆转PAH （PPAR?）或血管张力（pir）中平滑肌和内皮细胞重塑的治疗方法，2)PGIS和基因在赋予PAH易感和增加发生严重PAH的可能性方面的潜在修饰基因作用，以及3)PGIS和PPAR？在人类疾病中丧失表达。我们将使用我们小组生成的两种复杂的小鼠模型系统来解剖这两种受体对多环芳烃发展的相对贡献。我们提出的临床前大鼠研究确定了使用PGI2类似物和PPAR？激动剂可能很快转化为人体联合药物试验。我们的初步工作表明，近端PGIS启动子区域的序列变化影响启动子活性，导致PGIS低表达，从而建立了PAH的易感性。我们将对家族性肺动脉高压的PGIS启动子进行测序，将特定的单倍型与疾病的发病、严重程度和发病率联系起来。最后，由于表观遗传沉默和染色体丢失是基因表达下调的常见机制，我们将确定PGIS或PPAR是其中之一。甲基化特异性PCR （MSP）和荧光原位杂交（FISH）技术在PAH微解剖病变中的下调作用。具体目标1：描述PGIS和PPAR的贡献？多环芳烃易感性和严重性的途径。特定目标2：定义相关原代细胞类型中PGIS启动子序列变异的转录活性，以及它们在特定人群中的频率和相关性。特定目标3：确定甲基化沉默和/或等位基因丢失是否与PGIS和PPAR相关？在严重PAH患者的微解剖病变中下调。

DESCRIPTION (provided by applicant): 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 preventative treatment for this disease at present, newer targeted therapies can improve outcomes by altering vascular tone using prostacyclin (PGI2) analogues, dual endothelin antagonists, or phosphodiesterase - 5 inhibitors. Recent progress in the understanding of genetic aberrations in PAH suggests that it is a complex disorder and 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 PPAR?, are down- regulated in patients with PAH. Disruption of PGI2 signaling through the PPAR? pathway leads to aberrant cell growth. Our hypothesis proposes that PGI2 can signal through either PGIR or PPAR?. We hypothesize that signaling through PGIR results in more prominent effects on vascular tone (RV pressures, RV hypertrophy) while PPAR? stimulation results in more effects on vascular remodeling. The research proposed here 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 (PPAR?) 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 PPAR? 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 proposed pre-clinical rat studies establish the effectiveness of a combinatorial treatment using a PGI2 analogue and a PPAR? agonist may quickly translate in to a human combined drug trial. Our preliminary work demonstrates that sequence variation in the proximal PGIS promoter region affects promoter activity leading to low PGIS expression, thus establishing a predisposition to PAH. 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 PPAR? 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 PPAR? pathways to 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 PPAR? down- regulation in micro-dissected lesions from patients with severe PAH. PUBLIC HEALTH RELEVANCE: Pulmonary Arterial Hypertension (PAH) is a very serious lung disease in which blood pressure in the lung's pulmonary artery increases making the heart work harder to pump blood into the lung. PAH is very rare with an annual incidence of 1 to 2 per million and occurs more often in women. While there is no cure or preventative treatment, newer targeted therapies can improve outcomes. This project will help us understand how current treatments are reducing the changes in the pulmonary artery that lead to the high blood pressure and may lead to newer therapies that are more effective in controlling the progression and severity of PAH.