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

项目概要 该提案的总体目标是找到表面活性剂蛋白 A (SPA) 的新机制 调节血管平滑肌细胞 (SMC) 表型调节。 SMC 从 除了新内膜形成/血管重塑之外，还分化为去分化表型 在动脉粥样硬化、术后再狭窄等人类疾病中发挥着至关重要的作用 血管成形术或搭桥术、糖尿病血管并发症、动脉病移植、哮喘和癌症。 调节 SMC 表型调节和新内膜形成的机制尚不完善 明白了。 SPA的生理功能是由II型肺泡细胞分泌以维持 肺部的表面张力最小。然而，初步数据表明 SPA 可以充当 SMC 的角色 表型调节剂。在体内，SPA 在内侧和新内膜 SMC 中表达，如下： 大鼠和小鼠颈动脉的机械损伤。钢丝损伤引起的内膜增生 在 SPA 敲除小鼠中显着减弱。此外，SMC的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 在从 SPA 敲除小鼠中分离的 SMC 中观察到。此外，来自 SPA 敲除小鼠的 SMC Smad3 磷酸化增加，并且这种增加被 TGF-β1 中和抗体阻断。 SPA 位于 SMC 的细胞核中，表明它可能在 SMC 基因转录中发挥作用。 事实上，SPA 缺乏会增加平滑肌 α-肌动蛋白和平滑肌 22-α 启动子的活性 而重组SPA蛋白则减弱了它们的活性。因此，中心假设是 SPA 通过细胞外（通过 调节 TGF-β1 信号传导）和细胞内（心肌素相关基因转录）机制。 利用SMC原代培养物，结合分子、细胞和分子生物学原理，建立体内小鼠丝线损伤模型。 组织学方法，该提案将 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 是否必要 用于体内 SMC 表型调节/血管重塑。项目完成将揭开新奇 调节 SMC 表型调节的机制，并帮助了解 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。主办方和主办方制定的培训计划 导师实验室和密苏里大学的优良环境将保障 成功完成拟议的研究。

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.