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很小，可能是因为它忽略了发病机制。我们已经集中了相当大的努力，了解中央遗传机制和途径，有助于PAH的发病机制，开始与我们的BMPR 2突变的关联发现与PAH相关的主要基因。沿着我们的PAH（FPAH）大家族队列，其中大多数具有骨形态发生蛋白受体2（BMPR 2）突变[60个家族]，我们构建了一个重现PAH的Bmpr 2突变小鼠模型（R899 X）。通过对症状前BMPR 2突变PAH患者和我们的小鼠模型的检查，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，打击了caveolae的贩运。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，PAH的BMPR 2非依赖性形式的分子基础尚未阐明。为了解决这一问题，我们采用全外显子组测序方法来研究既往无PAH遗传病因的PAH患者。这项分析确定了一个新的基因与人类PAH，小窝蛋白-1（CAV 1），膜蛋白的形成小窝的重要。重要的是，小窝在肺中多种细胞类型的质膜中丰富，并且与多种信号传导途径（包括BMPR 2）相关，而Cav 1敲除小鼠没有小窝并表现出肺血管功能障碍。基于CAV 1和BMPR 2突变的这种融合，我们提出了我们的假设，即小窝缺陷代表了PAH遗传基础的共同机制。为了验证这一假设，我们将经验丰富的基础科学家和医生科学家联系起来，并建议在细胞、小鼠模型和人类患者中进行研究。在目标1中，我们将在体外细胞中测试假设，即小窝蛋白-1和BMPR 2突变破坏小窝运输，随后在细胞水平上失调小窝依赖性信号通路。在目标2中，我们将在小鼠中检验这一假设，即硝化、张力和运输中的小窝依赖性缺陷对PAH的发展至关重要。最后，在目标3中，我们将检验以下假设：CAV 1或BMPR 2发生种系突变的人类受试者存在与PAH发病率和严重程度相关的小窝结构和内皮功能缺陷。这些研究将为PAH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有效治疗的未来转化发展提供希望，这是这种悲惨疾病所急需的。

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.