Mechanotransduction and YAP/TAZ Signaling in Pulmonary Arterial Hypertension

项目总结/摘要： 肺动脉高压（PAH）的特征是肺动脉高压患者肺内的 肺动脉内皮细胞（PAEC）、平滑肌细胞（PASMC）和外膜成纤维细胞（PAAF） 导致肺血管阻力的进行性增加，并最终导致右心衰竭和死亡。 最近的研究表明，肺动脉（PA）僵硬与死亡率增加有关， PAH患者;然而，参与PA硬化发病机制和进展的机制， PAH尚未完全阐明。我们已经发现，远端血管基质硬化的发展早期， 肺动脉高压（PH）模型，并触发局部机械生物学反馈回路， 血管重塑并加速疾病进展。这些发现表明PA刚度不是 这仅仅是血管壁病理变化的结果，但其本身可以驱动异常的细胞行为。 我们已经确定雅普和TAZ是刚度依赖性PASMC和PAEC的关键调节因子 PAH中的机械活化。我们的初步研究结果表明，通过雅普/TAZ驱动的机械信号转导 通过抑制环氧合酶（考克斯）-2-衍生的前列腺素类产生的血管细胞活化， 骨形态发生蛋白（BMP）信号传导。PASMC和PAEC中雅普/TAZ的沉默消除了刚度- 增殖、基质沉积和牵引力产生的依赖性增加，以及补救抑制 前列腺素的产生和BMP信号传导。此外，PASMC过表达突变TAZ， 与细胞核组成性地结合，考克斯-2衍生的前列腺素类产生和BMP 导致过度增殖性重塑表型的信号传导。我们假设雅普/TAZ被激活， 机械环境驱动前重塑细胞反应和促进基质硬化， 通过抑制PAH中的前列腺素类产生和BMP信号传导的不良反馈回路。在目标1中，我们 研究雅普/TAZ在调节考克斯-2依赖性前列腺素产生和血管生成中的作用。 对PAH基质硬化的反应。我们将确定雅普/TAZ依赖性抑制的机制 考克斯-2和调节僵硬依赖性收缩和基质合成在人PASMC，PAEC， 和PAAF。在目的2中，我们将研究雅普/TAZ控制TGF-！BMP依赖 Smad信号传导，抑制Id 1表达，并调节PAH中BMP信号传导的细胞生长反应。 我们将确定雅普/TAZ活性对细胞增殖、凋亡抵抗和迁移的影响， 来自有和无BMPR 2突变的PAH患者的PASMC、PAEC和PAAF。在目标3中，我们将确定 雅普/TAZ的失活是否阻止PA硬化，减弱血管重塑，并阻止右心房的收缩， 我们将使用小鼠模型和药理学方法， 调节雅普/TAZ活性并评估雅普/TAZ失活对PA硬化、血流动力学 PH模型中的RV功能障碍、血管重塑以及前列腺素和BMP通路的调节。

PROJECT SUMMARY/ABSTRACT: Pulmonary arterial hypertension (PAH) is characterized by excessive proliferation of apoptosis-resistant pulmonary artery endothelial cells (PAEC), smooth muscle cells (PASMC), and adventitial fibroblasts (PAAF) leading to progressive increases in pulmonary vascular resistance, and ultimately right heart failure and death. Recent studies suggest that pulmonary arterial (PA) stiffness is associated with increased mortality in patients with PAH; however, the mechanisms involved in the pathogenesis and progression of PA stiffening in PAH have yet to be fully elucidated. We have discovered that distal vascular matrix stiffening develops early in models of pulmonary hypertension (PH) and triggers a local mechanobiological feedback loop that amplifies vascular remodeling and accelerates disease progression. These findings suggest that PA stiffness is not merely a consequence of pathologic changes in the vessel wall, but can itself drive abnormal cellular behavior. We have identified YAP and TAZ as pivotal regulators of stiffness-dependent PASMC and PAEC mechanoactivation in PAH. Our preliminary findings suggest that mechanosignaling via YAP/TAZ drives vascular cell activation through suppression of cyclooxygenase (COX)-2-derived prostanoid production and bone morphogenetic protein (BMP) signaling. Silencing of YAP/TAZ in PASMC and PAEC abrogates stiffness- dependent increases in proliferation, matrix deposition, and traction force generation, and rescues suppression of prostanoid production and BMP signaling. Moreover, PASMC overexpressing a mutant TAZ that localizes constitutively to the nucleus have a dramatic reduction in COX-2-derived prostanoid production and BMP signaling leading to a hyperproliferative remodeling phenotype. We hypothesize that YAP/TAZ are activated by the mechanical environment to drive pro-remodeling cellular responses and promote matrix stiffening in an adverse feedback loop via suppression of prostanoid production and BMP signaling in PAH. In Aim 1, we will investigate the role that YAP/TAZ play in regulating COX-2-dependent prostaglandin production and vascular responses to matrix stiffening in PAH. We will determine the mechanisms of YAP/TAZ-dependent suppression of COX-2 and regulation of stiffness-dependent contractility and matrix synthesis in human PASMC, PAEC, and PAAF. In Aim 2, we will examine the mechanisms by which YAP/TAZ control TGF-! and BMP-dependent Smad signaling, suppress Id1 expression, and regulate cellular growth responses to BMP signaling in PAH. We will determine the impact of YAP/TAZ activity on proliferation, apoptosis resistance, and migration in PASMC, PAEC, and PAAF from PAH patients with and without BMPR2 mutations. In Aim 3, we will determine whether inactivation of YAP/TAZ arrests PA stiffening, attenuates vascular remodeling, and prevents right ventricular (RV) dysfunction in experimental PH. We will use murine models and pharmacologic approaches to modulate YAP/TAZ activity and assess the effects of YAP/TAZ inactivation on PA stiffening, hemodynamics, RV dysfunction, vascular remodeling, and regulation of the prostanoid and BMP pathways in models of PH.