Caveolar Defects Underlie the Genetic Origins of PAH

描述（由申请人提供）：肺动脉高压（PAH）是一种所有年龄段的致命疾病。它对女性的影响不成比例，目前的治疗对长期生存的影响微乎其微，可能是因为它忽视了发病机制。从发现BMPR2突变是与多环芳烃相关的主要基因开始，我们已经花了大量的精力来理解多环芳烃发病机制的核心遗传机制和途径。随着我们的PAH家族（FPAH）的大队列研究，其中大多数都有骨形态发生蛋白受体2 （BMPR2）突变[60个家族]，我们构建了一个BMPR2突变小鼠模型（R899X），它概括了PAH。通过检查症状前BMPR2突变的PAH患者和我们的小鼠模型，我们已经能够确定疾病发展之前的几个主要分子事件。其中值得注意的是对毒品走私的破坏。然而，这些事件中哪些是疾病发展的核心，哪些是旁观者尚未确定。此外，不依赖bmpr2形式的多环芳烃的分子基础尚未阐明。为了解决这个问题，我们采用了全外显子组测序方法来研究没有PAH遗传病因的PAH患者。该分析发现了一个与人类多环芳烃相关的新基因，CAV1，这是一种对小泡形成很重要的膜蛋白。重要的是，肺泡在多种细胞类型的质膜中大量存在，并与包括BMPR2在内的多种信号通路相关，而Cav1缺失的小鼠没有肺泡，表现出肺血管功能障碍。基于CAV1和BMPR2突变的趋同，我们提出了我们的假设，即小泡缺陷代表了PAH遗传基础的共同机制。为了验证这一假设，我们联合了经验丰富的基础科学家和内科科学家，并建议在细胞、小鼠模型和人类患者中进行研究。在Aim 1中，我们将在体外细胞中验证假设，即小泡蛋白-1和BMPR2突变会破坏小泡运输，随后在细胞水平上失调小泡依赖的信号通路。在Aim 2中，我们将在小鼠中验证假设，即硝化，张力和运输的小窝依赖性缺陷是多环芳烃发展的核心。最后，在Aim 3中，我们将验证CAV1或BMPR2种系突变的人类受试者在腔泡结构和内皮功能方面存在缺陷的假设，这与PAH的外显率和严重程度有关。这些研究将为PAH的核心通路的细胞和分子发病机制提供新的基本认识，并将为PAH的有效治疗的未来转化开发提供希望，这是这一悲惨疾病所急需的。

DESCRIPTION (provided by applicant): Pulmonary Arterial Hypertension (PAH) is a lethal disease of all ages. It affects women disproportionately and current therapy has marginal impact on longterm survival, perhaps because it neglects pathogenesis. We have focused considerable effort in understanding the central genetic mechanisms and pathways that contribute to PAH pathogenesis, beginning with our discovery of the association of BMPR2 mutations as the major gene associated with PAH. Along with our large cohort of families with PAH (FPAH), most of whom have mutation in bone morphogenetic protein receptor 2 (BMPR2) [60 families], we constructed a Bmpr2 mutation mouse model (R899X) which recapitulates PAH. Through examination of presymptomatic BMPR2 mutant PAH patients and our mouse model, we have been able to identify several major molecular events which precede development of disease. Notable among these is disruption of trafficking of caveolae. However, which of these events are central to disease development and which are bystanders has not yet been determined. Further, the molecular basis for BMPR2-independent forms of PAH has yet to be elucidated. To address this issue, we undertook a whole-exome sequencing approach to study PAH patients without previous genetic etiology for PAH. This analysis identified a novel gene associated with human PAH, caveolin-1 (CAV1), a membrane protein important for the formation of caveolae. Importantly, caveolae are abundant in plasma membrane of multiple cell types in the lung, and have been linked to multiple signaling pathways, including BMPR2, while Cav1 null mice have no caveolae and exhibit pulmonary vascular dysfunction. Based on this convergence of CAV1 and BMPR2 mutations, we developed our hypothesis that defects in caveolae represent a common mechanism underlying the genetic basis of PAH. To test this hypothesis, we have aligned experienced basic scientists and physician scientists, and propose to carry out studies in cells, mouse models, and human patients. In Aim 1 we will test the hypothesis, in cells in vitro, that caveolin-1 and BMPR2 mutations disrupt caveolae trafficking, subsequently dysregulating caveolae-dependent signaling pathways at the cellular level. In Aim 2 we will test the hypothesis, in mice, that caveolae-dependent defects in nitration, tone, and trafficking are central to the development of PAH. Finally, in Aim 3 we will test the hypothesis that human subjects with germline mutations in CAV1 or BMPR2 have defects in caveolar structure and endothelial function, which associate with PAH penetrance and severity. These investigations will provide new basic understanding about cell and molecular pathogenesis of pathways central to PAH, and will provide promise for the future translational development of effective therapy for PAH, which is greatly needed for this tragic disease. PUBLIC HEALTH RELEVANCE: In this new project we align experienced basic and physician scientists with the goal to understand the functions of pathways which we have shown are integral in the pathogenesis of Pulmonary Arterial Hypertension (PAH). Using our large cohort of patients, as well as unique cell and animal models, we will test our hypothesis that defects in caveolae represent a common mechanism underlying the molecular basis of PAH.