Mechanism of apoptosis in lung vascular smooth muscle

描述(申请人提供)：肺动脉高压的特征是肺血管阻力增加，部分原因是肺动脉壁增厚。血管厚度受平滑肌细胞(SMC)增殖和凋亡的影响。然而，调控肺血管SMC凋亡的机制尚未明确。缺乏这样的知识干扰了预防和/或治疗肺动脉高压的新策略的发展。我的长期目标是确定肺血管SMC的凋亡调节机制，以开发基于凋亡的治疗策略来减少血管厚度。这一竞争性更新应用的目的是具体评估主要的抗凋亡蛋白Bcl-xl的基因转录机制。中心假说是GATA-4调控Bclxl基因转录。这一假说建立在初步数据的基础上，它表明：(1)调控抗细胞凋亡异构体基因转录的bclx基因启动子区域在肺动脉SMC中是活跃的；(Ii)该区域含有肺特异性SMC调节因子GATA-4的结合部位；(Iii)调节肺动脉高压可改变GATA-4活性、Bclxl表达和细胞凋亡。这项研究的理论基础是，一旦了解了肺血管SMC凋亡的调控，它将导致可用于治疗肺动脉高压的新策略。我特别准备从事这项拟议的研究，因为我的实验室有研究细胞凋亡和基因调控的技术和试剂。本研究的目的主要有三个方面：1)研究正常和重塑的肺动脉平滑肌中Bclxl基因转录的调控；2)明确诱导Bclxl基因转录的机制；3)研究正常和重塑的肺动脉中Bclxl基因表达下调的机制和功能。这项拟议的工作具有创新性，因为它将使用腺病毒为基础的独特报告系统来研究新的凋亡机制。我期望GATA-4能调节Bclxl的表达，控制细胞的凋亡。这些结果将具有重要意义，因为它们有望提供治疗肺动脉高压的新药物。此外，这一结果将从根本上推动肺部生物学领域的发展。

DESCRIPTION (provided by applicant): Pulmonary hypertension is characterized by increased pulmonary vascular resistance, in part, due to thickening of pulmonary arterial walls. Vascular thickness is influenced by smooth muscle cell (SMC) proliferation and apoptosis. Mechanisms that regulate pulmonary vascular SMC apoptosis, however, have not been defined. Lack of such knowledge interferes with the development of new strategies to prevent and/or treat pulmonary hypertension. My long-range goal is to identify the mechanisms of apoptotic regulation in pulmonary vascular SMC to develop apoptosis-based therapeutic strategies to reduce vascular thickness. The objective of this competitive renewal application is to evaluate specifically the mechanism of gene transcription of a major anti-apoptotic protein Bcl-xL. The central hypothesis is that GATA-4 regulates Bcl-xL gene transcription. The hypothesis has been formulated on the basis of preliminary data, which suggest that i) the region of bcl-x gene promoter which regulates gene transcription of anti-apoptotic isoform Bcl-xL is active in pulmonary artery SMC, ii) this region contains binding sites for GATA-4 which is a pulmonary-specific SMC regulator, and iii) regulators of pulmonary hypertension alters GATA-4 activity, Bcl- xL expression, and apoptosis. The rationale for the proposed research is that, once knowledge of the regulation of pulmonary vascular SMC apoptosis has been obtained, it will lead to new strategies that can be used to treat pulmonary hypertension. I am uniquely prepared to undertake the proposed research because techniques and reagents to study apoptosis and gene regulation are available in my laboratory. The objective of the application will be accomplished by pursuing three specific aims: 1) Characterize the regulation of basal Bcl-xL gene transcription in smooth muscle from normal and remodeled pulmonary arteries, 2) Identify mechanisms for the induction of Bcl-xL gene transcription, and 3) Define the mechanisms and functions of downregulation of Bcl-xL expression in normal and remodeled pulmonary arteries. The proposed work is innovative because it will investigate novel apoptotic mechanisms using a unique adenovirus-based reporter system. It is my expectation that GATA-4 regulates Bcl-xL expression and controls apoptosis. These results will be significant because they are expected to provide new agents against pulmonary hypertension. In addition, the results will fundamentally advance the field of lung biology.