Won Doyon, Zhu Su-Ning, Chen Mian, Teichert Anouk-Martine, Fish Jason E, Matouk Charles C, Bonert Michael, Ojha Matadial, Marsden Philip A, Cybulsky Myron I
Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.
Am J Pathol. 2007 Nov;171(5):1691-704. doi: 10.2353/ajpath.2007.060860.
Atherosclerosis develops in distinct regions of the arterial tree. Defining patterns and mechanisms of endothelial cell gene expression in different regions of normal arteries is key to understanding the initial molecular events in atherogenesis. In this study, we demonstrated that the expression of endothelial nitric-oxide synthase (eNOS), an atheroprotective gene, and its phosphorylation on Ser(1177), a marker of activity, were lower in regions of the normal mouse aorta that are predisposed to atherosclerosis. The same expression pattern was observed in mouse strains that are both susceptible and resistant to atherosclerosis, and the topography of eNOS expression was inverse to p65, the main nuclear factor-kappaB subunit. Modeling of disturbed and uniform laminar flow in vitro reproduced the expression patterns of eNOS and p65 that were found in vivo. Heterogeneous nuclear RNA expression and RNA polymerase II chromosome immunoprecipitation studies demonstrated that regulation of transcription contributed to increased eNOS expression in response to shear stress. In vivo, the transcription of eNOS was reduced in regions of the mouse aorta predisposed to atherosclerosis, as defined by reporter gene expression in eNOS promoter-beta-galactosidase reporter transgenic mice. These data suggest that disturbed hemodynamic patterns found at arterial branches and curvatures uniquely modulate endothelial cell gene expression by regulating transcription, potentially explaining why these regions preferentially develop atherosclerosis when risk factors such as hypercholesterolemia are introduced.
动脉粥样硬化在动脉树的不同区域发展。明确正常动脉不同区域内皮细胞基因表达的模式和机制是理解动脉粥样硬化发生初始分子事件的关键。在本研究中，我们证明了内皮型一氧化氮合酶（eNOS）（一种具有抗动脉粥样硬化作用的基因）的表达及其在Ser(1177)位点的磷酸化（活性标志物）在正常小鼠主动脉中易于发生动脉粥样硬化的区域较低。在对动脉粥样硬化易感和有抗性的小鼠品系中均观察到相同的表达模式，且eNOS表达的拓扑结构与主要核因子-κB亚基p65相反。体外对紊乱和均匀层流的模拟再现了体内发现的eNOS和p65的表达模式。异质核RNA表达和RNA聚合酶II染色体免疫沉淀研究表明，转录调控有助于eNOS表达在剪切应力作用下增加。在体内，如通过eNOS启动子-β-半乳糖苷酶报告基因转基因小鼠中的报告基因表达所定义，在小鼠主动脉易于发生动脉粥样硬化的区域eNOS的转录减少。这些数据表明，在动脉分支和弯曲处发现的紊乱血流模式通过调节转录独特地调节内皮细胞基因表达，这可能解释了为何当引入高胆固醇血症等危险因素时这些区域优先发生动脉粥样硬化。
