TSC2 Signaling in Pulmonary Arterial Hypertension

肺动脉高压(PAH)是一种进展性的致命性疾病，以肺血管重构为主要表现。 无主动脉(PA)、右室后负荷升高、右心衰竭和死亡。PA的关键组件 血管重塑是由于增殖增加和细胞凋亡受损而导致的进行性血管壁增厚。 肺血管平滑肌细胞(PAVSMC)。我们之前认为mTOR信令是一个关键 增殖/抗凋亡PAH PAVSMC的阳性调节因子和为临床提供临床前数据 试验测试mTOR抑制剂ABI-009用于PAH患者。最近，PAVSMC之间的双向串扰 细胞外基质(ECM)的组成和硬度是肺血管的关键调节因子 重塑和PAH。细胞外基质、mTOR支持的血管内皮细胞重塑与增殖的联系机制(S) 其他常驻PA细胞的情况尚不清楚，安全和易于转化的治疗方案仍有待于 下定决心。我们已经发现，生长抑制因子TSC2，mTOR复合体1的关键抑制因子，也是 作为机械传感器，与机械传感器YAP/TAZ、HYPER形成负双向串扰。 其在PAH中的激活促进ECM硬化和肺血管重塑。我们报告TSC2 PAH患者的PAVSMC缺乏，导致mTORC1、YAP/Taz激活，从而上调- 促进生存的mTORC2-Akt的调节，增加细胞外基质蛋白的增殖、存活和过量生产。 ECM由人PAH PAVSMC产生，激活mTORC1，上调YAP/Taz，mTORC2-Akt和 PAVSMC增殖，以及PAEC和PAAF生长。最后，Sirt1激活剂对TSC2的恢复 SRT2104下调YAP/Taz和mTORC1/2的表达，减少细胞外基质的产生，抑制细胞增殖和细胞周期调控。 诱导人PAH PAVSMC凋亡，降低SU5416/小鼠缺氧PH。在下一次资助期间 期间，我们建议阐明TSC2作为ECM-肺血管细胞间的关键协调者的作用。 行动和探索TSC2修复的好处，一种新的耐受性良好的药物与高翻译潜力- TIAL纠正mTOR和YAP/Taz网络的放松调控，逆转PA重构和PH。具体来说- Cally，我们将(1)批判性地测试TSC2的状态，它与YAP/Taz，mTORC1和2的关系，以及它在 肺血管内皮细胞增殖、存活、肺血管重塑和肺高压 来自PAH和健康人以及具有VSM特异性TSC2基因敲除的小鼠的细胞；(2)确定TSC2 PAVSMC的缺陷是由增加的基质硬度引起的，并通过YAP/Taz依赖的自我支持 ECM环，评价TSC2在细胞外基质重塑和细胞外基质依赖性增殖中的作用。 检测SRT2104修复TSC2是否抑制PAH PAVSMC增殖，诱导 细胞凋亡，减少病理性ECM的产生和随后的PAEC和PAAF的过度增殖，以及 逆转肺血管重塑和肺高压。拟议的研究将确定新的关键机制 肺血管重塑，为治疗干预提供新的重要分子靶点。

Pulmonary arterial hypertension (PAH), a progressive fatal disease, manifests by vascular remodeling of pulmo- nary arteries (PA), elevated right ventricular afterload, right heart failure and death. A key component of PA remodeling is the progressive vessel wall thickening due to increased proliferation and impaired apoptosis of pulmonary arterial vascular smooth muscle cells (PAVSMC). We previously identified mTOR signaling as a key positive regulator of proliferative/apoptosis-resistant PAH PAVSMC and provided pre-clinical data for a clinical trial to test mTOR inhibitor ABI-009 for patients with PAH. Recently, bi-directional cross-talk between PAVSMC and extracellular matrix (ECM) composition and stiffness was identified as a key regulator of pulmonary vascular remodeling and PAH. The mechanism(s) linking ECM, mTOR-supported PAVSMC remodeling, and proliferation of other resident PA cells are not known, and safe and easily translatable therapeutic options remain to be determined. We have found that growth suppressor TSC2, a key inhibitor of mTOR complex 1 (mTORC1), also acts as a mechanosensor and forms negative bi-directional cross-talk with mechanotransducers Yap/Taz, hyper- activation of which in PAH promotes ECM stiffening and pulmonary vascular remodeling. We report that TSC2 is deficient in PAVSMC from subjects with PAH, resulting in activation of mTORC1, Yap/Taz, consequent up- regulation of pro-survival mTORC2-Akt, increased proliferation, survival, and over-production of ECM proteins. ECM, produced by human PAH PAVSMC, activates mTORC1, and up-regulates Yap/Taz, mTORC2-Akt and PAVSMC proliferation, as well as growth of PAEC and PAAF. Last, the restoration of TSC2 by Sirt1 activator SRT2104 down-regulates both Yap/Taz and mTORC1/2, reduces ECM production, inhibits proliferation and in- duces apoptosis in human PAH PAVSMC, and reduces SU5416/hypoxia PH in mice. During the next funding period, we propose to elucidate the role of TSC2 as a critical coordinator of ECM-pulmonary vascular cell inter- actions and explore the benefits of TSC2 restoration by a novel well-tolerated drug with high translational poten- tial to correct deregulation of both mTOR and Yap/Taz networks, and reverse PA remodeling and PH. Specifi- cally, we will (1) critically test the status of TSC2, its relationship with Yap/Taz, mTORC1 and 2, and its role in PAVSMC proliferation, survival, pulmonary vascular remodeling and PH using de-identified lung tissues and cells from PAH and healthy subjects and mice with VSM-specific Tsc2 knockout; (2) determine whether TSC2 deficiency in PAVSMC is induced by increased matrix stiffness and self-supported via a Yap/Taz-dependent ECM loop, and evaluate the role of TSC2 in ECM remodeling and ECM-dependent proliferation of PAEC and PAAF; and (3) test whether restoration of TSC2 by SRT2104 suppresses PAH PAVSMC proliferation, induces apoptosis, reduces pathological ECM production and consequent hyper-proliferation of PAEC and PAAF, and reverses pulmonary vascular remodeling and PH. The proposed study will identify new critical mechanisms of pulmonary vascular remodeling and dissect new important molecular target for therapeutic intervention.