缺氧对人冠状动脉平滑肌细胞中瘦素表达的分子调控
Molecular regulation of the expression of leptin by hypoxia in human coronary artery smooth muscle cells.
作者信息
Chiu Chiung-Zuan, Wang Bao-Wei, Shyu Kou-Gi
机构信息
School of Medicine, College of Medicine, Fu-Jen Catholic University, New Taipei, Taiwan.
Division of Cardiology, Shin-Kong Wu Ho-Su Memorial Hospital, 95 Wen- Chang Road, Taipei, Taiwan.
出版信息
J Biomed Sci. 2015 Jan 9;22(1):5. doi: 10.1186/s12929-014-0109-8.
BACKGROUND
Leptin, produced mainly by white adipose tissue, is a hormone that promotes vascular smooth muscle cell (VSMC) migration and proliferation, a process involved in the pathophysiology of atherosclerosis. Leptin expression in human coronary artery smooth cell (HCASMC) is induced by hypoxia. However, our understanding of the process of atherosclerosis in HCASMC is only emerging. Since the mechanisms by which hypoxia regulates leptin in HCASMC are as yet unknown, this study aims to investigate the mechanics of molecular regulation of leptin expression in HCASMC under hypoxia. We subjected cultured HCASMCs to hypoxia for varying periods of time. Through use of different signal pathway inhibitors, we were able to sort out and identify the pathway through which hypoxia-induced leptin expression occurs.
RESULTS
Leptin mRNA and protein levels increased after 2.5% hypoxia for 2-to-4 hours, with earlier expression of angiotensin II (AngII) and reactive oxygen species (ROS). The addition before hypoxia of the c-Jun N-terminal kinase (JNK) pathway inhibitor (SP600125), JNK small interfering RNA (siRNA), AngII receptor blockers (ARBs; losartan), or N-acetyl-L-cysteine (NAC, an ROS scavenger), had the effect of inhibiting JNK phosphorylation and leptin expression. Gel shift assay and luciferase promoter study showed that leptin/activator protein 1 (AP-1) binding and transcriptional activity to the leptin promoter increased after hypoxia, and SP600125, JNK siRNA, losartan, and NAC abolished the binding and transcriptional activity induced by hypoxia. The use of SP600125, JNK siRNA, losartan, and NAC effectively inhibited the binding and transcriptional activity induced by hypoxia. Migration and proliferation, ROS generation, and the presence of leptin in the nuclei of HCASMCs also increased under hypoxia.
CONCLUSION
Hypoxia in HCASMCs increases leptin expression through the induction of AngII, ROS, and the JNK pathway to enhance atherosclerosis in HCASMCs.
背景
瘦素主要由白色脂肪组织产生，是一种促进血管平滑肌细胞（VSMC）迁移和增殖的激素，这一过程参与动脉粥样硬化的病理生理学。人冠状动脉平滑肌细胞（HCASMC）中的瘦素表达由缺氧诱导。然而，我们对HCASMC中动脉粥样硬化过程的理解才刚刚开始。由于缺氧调节HCASMC中瘦素的机制尚不清楚，本研究旨在探讨缺氧条件下HCASMC中瘦素表达的分子调控机制。我们将培养的HCASMC置于不同时间段的缺氧环境中。通过使用不同的信号通路抑制剂，我们能够梳理并确定缺氧诱导瘦素表达的途径。
结果
在2.5%缺氧2至4小时后，瘦素mRNA和蛋白水平升高，同时血管紧张素II（AngII）和活性氧（ROS）表达提前。在缺氧前添加c-Jun氨基末端激酶（JNK）通路抑制剂（SP600125）、JNK小干扰RNA（siRNA）、AngII受体阻滞剂（ARBs；氯沙坦）或N-乙酰-L-半胱氨酸（NAC，一种ROS清除剂），具有抑制JNK磷酸化和瘦素表达的作用。凝胶迁移实验和荧光素酶启动子研究表明，缺氧后瘦素/激活蛋白1（AP-1）与瘦素启动子的结合及转录活性增加，而SP600125、JNK siRNA、氯沙坦和NAC消除了缺氧诱导的结合及转录活性。使用SP600125、JNK siRNA、氯沙坦和NAC可有效抑制缺氧诱导的结合及转录活性。在缺氧条件下，HCASMC的迁移和增殖、ROS生成以及细胞核中瘦素的存在也增加。
结论
HCASMC中的缺氧通过诱导AngII、ROS和JNK通路增加瘦素表达，从而增强HCASMC中的动脉粥样硬化。
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