Zhang Tao, Tian Feng, Wang Jing, Jing Jing, Zhou Shan-Shan, Chen Yun-Dai
Cell Physiol Biochem. 2015;37(4):1421-30. doi: 10.1159/000438511. Epub 2015 Oct 22.
BACKGROUND/AIMS: Endothelial cell injury and subsequent apoptosis play a key role in the development and pathogenesis of atherosclerosis, which is hallmarked by dysregulated lipid homeostasis, aberrant immunity and inflammation, and plaque-instability-associated coronary occlusion. Nevertheless, our understanding of the mechanisms underlying endothelial cell apoptosis is still limited. MicroRNA-429 (miR-29) is a known cancer suppressor that promotes cancer cell apoptosis. However, it is unknown whether miR-429 may be involved in the development of atherosclerosis through similar mechanisms. We addressed these questions in the current study.
We examined the levels of endothelial cell apoptosis in ApoE (-/-) mice suppled with high-fat diet (HFD), a mouse model for atherosclerosis (simplified as HFD mice). We analyzed the levels of anti-apoptotic protein Bcl-2 and the levels of miR-429 in the purified CD31+ endothelial cells from mouse aorta. Prediction of the binding between miR-429 and 3'-UTR of Bcl-2 mRNA was performed by bioinformatics analyses and confirmed by a dual luciferase reporter assay. The effects of miR-429 were further analyzed in an in vitro model using oxidized low-density lipoprotein (ox-LDL)-treated human aortic endothelial cells (HAECs).
HFD mice developed atherosclerosis in 12 weeks, while the control ApoE (-/-) mice that had received normal diet (simplified as NOR mice) did not. HFD mice had significantly lower percentage of endothelial cells and significantly higher percentage of mesenchymal cells in the aorta than NOR mice. Significantly higher levels of endothelial cell apoptosis were detected in HFD mice, resulting from decreases in Bcl-2 protein, but not mRNA. The decreases in Bcl-2 in endothelial cells were due to increased levels of miR-429, which suppressed the translation of Bcl-2 mRNA via 3'-UTR binding. These in vivo findings were reproduced in vitro on ox-LDL-treated HAECs.
Atherosclerosis-associated endothelial cell apoptosis may result from down regulation of Bcl-2, through increased miR-429 that binds and suppresses translation of Bcl-2 mRNA.
背景/目的：内皮细胞损伤及随后的凋亡在动脉粥样硬化的发生发展及发病机制中起关键作用，动脉粥样硬化的特征为脂质稳态失调、免疫和炎症异常以及与斑块不稳定相关的冠状动脉闭塞。然而，我们对内皮细胞凋亡潜在机制的理解仍然有限。微小RNA-429（miR-429）是一种已知的抑癌基因，可促进癌细胞凋亡。然而，miR-429是否可能通过类似机制参与动脉粥样硬化的发展尚不清楚。我们在本研究中探讨了这些问题。
我们检测了高脂饮食喂养的ApoE（-/-）小鼠（一种动脉粥样硬化小鼠模型，简称为高脂饮食小鼠）的内皮细胞凋亡水平。我们分析了从小鼠主动脉中纯化的CD31+内皮细胞中抗凋亡蛋白Bcl-2的水平以及miR-429的水平。通过生物信息学分析预测miR-429与Bcl-2 mRNA的3'-UTR之间的结合，并通过双荧光素酶报告基因测定进行验证。使用氧化低密度脂蛋白（ox-LDL）处理的人主动脉内皮细胞（HAECs）在体外模型中进一步分析了miR-429的作用。
高脂饮食小鼠在12周内发生了动脉粥样硬化，而接受正常饮食的对照ApoE（-/-）小鼠（简称为正常饮食小鼠）则未发生。与正常饮食小鼠相比，高脂饮食小鼠主动脉中内皮细胞的百分比显著降低，间充质细胞的百分比显著升高。在高脂饮食小鼠中检测到显著更高水平的内皮细胞凋亡，这是由于Bcl-2蛋白水平降低而非mRNA水平降低所致。内皮细胞中Bcl-2的降低是由于miR-429水平升高，miR-429通过3'-UTR结合抑制Bcl-2 mRNA的翻译。这些体内研究结果在体外ox-LDL处理的HAECs中得到了重现。
动脉粥样硬化相关的内皮细胞凋亡可能是由于Bcl-2下调所致，其机制是miR-429增加，miR-429结合并抑制Bcl-2 mRNA的翻译。
