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

项目摘要 该提案的总体目标是找到新的机制，表面活性蛋白A（SPA） 调节血管平滑肌细胞（SMC）表型调节。SMC从一个 除了新生内膜形成/血管重塑外， 在人类疾病如动脉粥样硬化的发展、术后再狭窄中起关键作用。 血管成形术或旁路术、糖尿病血管并发症、动脉病移植、哮喘和癌症。 调节SMC表型调节和新生内膜形成的机制尚不清楚 明白SPA的生理功能是由II型肺泡细胞分泌， 肺部表面张力最小然而，初步数据表明，SPA作为SMC的作用 表型调节剂在体内，SPA在中膜和新生内膜SMC中表达， 大鼠和小鼠颈动脉的机械损伤。导丝损伤诱导的内膜增生是 在SPA敲除小鼠中显著减弱。此外，SMC mRNA表达增加， 收缩基因和收缩SMC表型的关键调节因子，Myocardin和TGF-β1， 在分离自SPA敲除小鼠的SMC中观察到。此外，来自SPA敲除小鼠的SMC具有 增加Smad 3磷酸化，并且增加被TGF-β1中和抗体阻断。 SPA定位于SMC的细胞核中，提示其可能在SMC基因转录中起作用。 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蛋白减弱了它们的活性。因此，中心假设是， SPA通过细胞外（经血管壁）和细胞外（经血管壁）调节SMC表型调节和血管重塑。 调节TGF-β1信号传导）和细胞内（心肌素相关基因转录）机制。 采用原代培养的SMC，结合分子、细胞、 组织学方法，该建议将1）确定细胞外和细胞内的分子 SPA调节SMC表型调节的机制; 2）确定SPA是否是必需的 用于SMC表型调节/体内血管重塑。项目完成后将发现新的 调节SMC表型调节的机制，并提供了对SPA是否是一种 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。赞助商和赞助商制定的培训计划 在导师的实验室和密苏里州的大学杰出的环境将保障 顺利完成拟议的研究。

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.