The mechanistic role of surfactant protein A in smooth muscle cell phenotype modulation and vascular remodeling

项目总结 这项提案的总体目标是找到新的机制，使表面活性蛋白A(SPA) 调节血管平滑肌细胞(SMC)表型转换。SMC从 除新生内膜形成/血管重塑外，分化到去分化的表型 在人类疾病中起关键作用，如动脉粥样硬化的发展，术后再狭窄 血管成形术或搭桥手术、糖尿病血管并发症、动脉病变移植、哮喘和癌症。 SMC表型调节和新生内膜形成的调控机制不是很好 明白了。SPA的生理功能是由II型肺泡细胞分泌维持 肺部最小的表面张力。然而，初步数据表明，SPA作为SMC发挥了作用 表型调节剂。在活体内，SPA在大鼠的中膜和新生内膜中均有表达。 大鼠和小鼠颈动脉机械性损伤。钢丝损伤后血管内膜增生。 在SPA基因敲除小鼠中显著减弱。此外，SMC的mRNA表达增加 肌钙蛋白和转化生长因子-β-1是影响平滑肌细胞收缩表型的关键调控因子 在SPA基因敲除小鼠分离的SMC中观察到。此外，SPA基因敲除小鼠的SMC Smad3磷酸化增加，并被转化生长因子-β-1中和抗体阻断。 SPA定位于SMC的胞核，提示其可能在SMC基因转录中发挥作用。 事实上，SPA缺乏增加了平滑肌α-肌动蛋白和平滑肌22-α启动子的活性 而重组SPA蛋白则使其活性减弱。因此，中心假设是 SPA通过细胞外(VIA)调节SMC表型调节和血管重塑 调节转化生长因子-β1信号)和细胞内(Myocardin相关基因转录)机制。 利用原代培养的SMC，建立了分子、细胞和组织化学相结合的小鼠在体线损伤模型。 组织学方法，这项建议将1)确定细胞外和细胞内的分子 SPA调节SMC表型调节的机制；以及2)确定SPA是否是必需的 用于体内SMC表型调节/血管重塑。项目完成将揭开小说的面纱 调节SMC表型调节的机制，并提供对SPA是否是 治疗与常见血管疾病相关的血管损伤的潜在靶点 如糖尿病、再狭窄、动脉粥样硬化和癌症。赞助商和企业制定的培训计划 导师实验室和密苏里大学的卓越环境将保障 圆满完成拟议的研究。

PROJECT SUMMARY The overall goal of this proposal is to find novel mechanisms whereby surfactant protein A (SPA) regulates vascular smooth muscle cell (SMC) phenotype modulation. SMC transition from a differentiated to dedifferentiated phenotype in addition to neointima formation/vascular remodeling has a critical role in human diseases such as the development of atherosclerosis, restenosis after angioplasty or bypass, diabetic vascular complications, arteriopathy transplants, asthma and cancer. Mechanisms that regulate SMC phenotype modulation and neointima formation are not well understood. The physiological function of SPA is its secretion by type II alveolar cells to maintain minimal surface tension in the lungs. However, preliminary data indicate a role for SPA as a SMC phenotype modulator. In vivo, SPA was expressed in the medial and neointimal SMCs following mechanical injury in rat and mouse carotid arteries. The wire-injury induced intimal hyperplasia was dramatically attenuated in SPA knockout mice. Furthermore, increased mRNA expression of SMC contractile genes and key regulators for contractile SMC phenotype, Myocardin and TGF-β1 was observed in SMCs isolated from SPA knockout mice. Additionally, SMCs from SPA knockout mice had increased Smad3 phosphorylation and the increase was blocked by the TGF-β1 neutralizing antibody. SPA is localized in the nucleus of SMCs suggesting it may have a role in SMC gene transcription. Indeed, SPA deficiency increased smooth muscle α-actin and smooth muscle 22-α promoter activity whereas recombinant SPA protein attenuated their activities. Hence, the central hypothesis is that SPA regulates SMC phenotype modulation and vascular remodeling through both extracellular (via modulating TGF-β1 signaling) and intracellular (Myocardin-related gene transcription) mechanisms. Using primary culture of SMC, in vivo mouse wire injury models combined with molecular, cellular and histological approaches, this proposal will 1) determine the molecular extracellular and intracellular mechanisms by which SPA regulates SMC phenotypic modulation; and 2) determine if SPA is essential for SMC phenotype modulation/vascular remodeling in vivo. Project completion will uncover novel mechanisms regulating SMC phenotypic modulation and provide understanding into whether SPA is a potential target for therapy against vascular damage associated with common vascular diseases such as diabetes, restenosis, atherosclerosis and cancer. The training plan laid out by the sponsor and the outstanding environment in the mentor’s laboratory and at the University of Missouri will safeguard the successful completion of the proposed studies.