Snail/Rho-RalA/MT1-MMP信号通路对动脉粥样硬化斑块内血管生成的调节作用

The key characteristic of atherosclerosis is pathological angiogenesis (or neovascularization), the critical source of plaque hemorrhage and rupture and ultimately responsible for the sudden onset of myocardial infarction and stroke. It has been reported that Snail plays a critical role in controlling cardiovascular development during embryonic stage. However, the role of Snail in the regulation of pathological angiogenesis as well as the underlying molecular mechanisms remains unclear. To this end, we seek to determine whether endothelial cell-derived Snail exerts its functional role during pathological angiogenic progression through controlling MT1-MMP-mediated degradation of underlying basement membrane and the interstitial/stromal matrix. Using recently developed tamoxifen inducible Snail conditional knockout mice and MT1-MMP conditional knockout mice combined with ApoE-/- transgenic mice, we propose the following aims: 1) to study the regulatory function of Snail on the interaction between endothelial cell-matrix as well as the impact of deletion of Snail or MT1-MMP on neovascularization within atherosclerotic plaque; 2) to study the regulatory function of Snail on exocyst complex-dependent trafficking of MT1-MMP in endothelial cells as well as the underlying mechanisms; 3) to investigate the impact of administration of MT1-MMP blocking antibody or MT1-MMP RNAi recombinant viral vector on the stabilization of plaque as well as neovascularization within the plaque. These studies will provide an important theoretical basis for atherosclerosis tailored therapeutic strategy.

病理性血管生成是动脉粥样硬化斑块重要的病理学特征，其与斑块出血及破裂高度相关并最终导致急性心肌梗塞及中风的发生。研究表明，锌指转录因子Snail在胚胎心血管发育中有关键作用，而其在病理性血管生成中的作用及其分子机制仍不清楚。为此，本课题从调控血管生成的关键步骤着手，研究内皮源性Snail如何调控并通过膜型基质金属蛋白酶（MT1-MMP，MT1）降解血管基底膜及胞外基质，发挥其病理性血管生成调节的作用。应用新近构建的Snail、MT1条件性敲除小鼠合并ApoE-/-转基因小鼠，我们拟开展如下研究：1）Snail对内皮细胞-基质相互作用的调控及Snail、MT1基因敲除对粥样硬化斑块内血管生成的影响；2）Snail对MT1胞吐作用的调节及其作用机制；3）给予MT1中和抗体和RNA干扰重组病毒载体对斑块内血管生成及斑块稳定性的影响。本研究将为动脉粥样硬化疾病的针对性治疗策略提供重要的理论基础。

动脉粥样硬化是一种慢性进展的血管疾病，其发病机制复杂，斑块内血管发生和炎症反应是动脉粥样硬化疾病进展的关键因素。Snail是一种锌指转录因子，参与胚胎的发育和肿瘤形成中EMT过程。但是在动脉粥样硬化形成过程中的作用和机制尚且未知。在本项研究中，我们建立了内皮条件性敲除Snail的Apoe-/- 小鼠，并通过对转基因小鼠颈总动脉部分结扎并喂养高脂饲料成功建立动脉粥样硬化小鼠模型。我们发现，内皮特异性敲除Snail之后，动脉粥样硬化模型小鼠斑块中微血管密度减少，炎症反应降低，脂质沉积减少，平滑肌和胶原含量增加，说明内皮特异性敲除Snail之后能减缓动脉粥样硬化斑块的发病进程。随后我们对其机制进行了进一步研究，发现在内皮细胞中Snail能够从转录水平上促进炎症因子（CXCL10、CCL5）表达。从内皮细胞中敲除Snail后减少斑块内炎症因子表达和炎症细胞的数量。通过本项研究，我们鉴定了内皮源性Snail在动脉粥样硬化疾病进展中的作用和机制，发现Snail可以作为动脉粥样硬化的潜在治疗靶点。