PCAF对血管损伤修复的作用及机制研究

The proliferation and migration of vascular smooth muscle cells after endothelial injury are the pivotal process for the initiation and development of vascular neointimal hyperplasia. p300/CBP-associated factor (PCAF), a transcriptional coactivator with histone acetyltransferase activity, is involved in the cell differentiation, apoptosis and tumorigenesis. However, the roles of PCAF in vascular neointimal hyperplasia and re-endothelialization post injury are unknown. Our previous data showed that PCAF participated in the proliferation and migration of vascular smooth muscle cells and neointimal hyperplasia after vascular injury. Hence, the present project will up-regulate and down-regulate the expression of PCAF, with immunohistochemistry and molecular biological technologies, to explore (1) the effect and related molecular mechanism of PCAF on proliferation, migration and phenotypic switching of vascular smooth muscle cells in vitro; (2) the effect and related molecular mechanism of PCAF on biological function of vascular endothelial cells in vitro; (3) the effect and related molecular mechanism of PCAF on vascular neointimal formation and re-endothelialization post injury in an animal model. The project will further elucidate the molecular mechanism of PCAF on vascular neointimal formation and re-endothelialization after vascular injury, and PCAF could be a therapeutic target for the prevention and treatment of neointimal hyperplasia-related vascular disease.

血管内皮损伤后平滑肌细胞增殖和迁移是新生内膜增生发生发展的重要过程。p300/CBP相关因子（PCAF）是一种转录辅激活子，具有组蛋白乙酰基转移酶活性，参与细胞分化、凋亡和肿瘤发生等过程。目前对于PCAF是否参与血管损伤后新生内膜增生和再内皮化尚无报道。本课题组前期实验表明，PCAF与血管平滑肌细胞增殖和迁移以及血管损伤后新生内膜增生有关。在此基础上，本项目拟通过上调和下调PCAF表达，采用组织化学和分子生物学等技术，在离体细胞和整体动物两个水平探讨：（1）PCAF对血管平滑肌细胞增殖、迁移及表型转化的作用及其分子机制；（2）PCAF对内皮细胞生物学功能的影响及其分子机制；（3）PCAF对血管新生内膜增生和血管损伤后再内皮化的影响及其机制。力图阐明PCAF对血管损伤后内膜新生和再内皮化的根本机制，为防治内膜增生相关疾病提供新的分子靶点。

PCAF参与了血管损伤后新生内膜增生和再内皮化的过程。本课题通过血管平滑肌细胞（VSMCs）和人脐静脉内皮细胞（HUVECs）的体外培养，结合大鼠颈动脉球囊损伤模型的体内实验，并运用现代分子生物学技术，对PCAF参与血管损伤后新生内膜增生和再内皮化的分子生物学机制进行了初步研究。首先通过VSMCs实验验证了下调PCAF后可抑制VSMCs增殖和迁移；同时通过Western blot、Q-PCR、ELISA等实验证明了其与PCAF下调后抑制细胞内NF-κB介导的炎症反应有关。通过HUVECs实验验证了下调PCAF表达，对HUVECs增殖、NO合成等生物学功能不产生抑制作用，而对HUVECs的炎症反应产生抑制作用。同时在颈动脉球囊损伤实验中，证实了大鼠颈总动脉球囊损伤后新生内膜形成与PCAF表达增强有关；下调PCAF表达可显著减少大鼠颈总动脉球囊损伤后新生内膜形成，NF-κB p65表达，细胞增殖及迁移，并促进损伤血管再内皮化。综上所述，本研究阐明了PCAF对血管损伤后修复过程的作用及其相关机制，为临床防治动脉粥样硬化及血管损伤相关疾病提供新的目标。