*Department of Surgery and Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands †Institute for Molecular Medicine, Renal and Cardiovascular Section, University of Southern Denmark and Odense University Hospital, Odense, Denmark ‡Department of Biomedical Sciences and Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark §Diabetes NBEs and Obesity Biology, Novo Nordisk A/S, Måløv, Denmark.
Ann Surg. 2013 Nov;258(5):743-51; discussion 752-3. doi: 10.1097/SLA.0b013e3182a6aac0.
To study the role of microRNAs in hypertension-induced vascular pathology before the onset of symptoms of severe cardiovascular disease.
MicroRNAs play a crucial role in cardiovascular disease. However, microRNAs are often studied in full-blown cardiovascular disease models, not during development of cardiovascular pathology.
Angiotensin II was infused into healthy adult rats, inducing chronic hypertension, and microRNA expression profiles were obtained. The most prominently regulated microRNA, miR-487b, was further investigated, using primary cultures of rat aortic and human umbilical cord arterial cells.
MiR-487b is predicted to target insulin receptor substrate 1 (IRS1). IRS1 plays an important role in both insulin signaling and cell proliferation and survival. IRS1 mRNA and protein levels were downregulated in aortae of hypertensive rats. MiR-487b binds directly to both rat and human IRS1 3'UTR and inhibits reporter gene expression in vitro. In primary rat and human arterial adventitial fibroblasts, inhibition of miR-487b leads to upregulation of IRS1 expression. Upregulation of miR-487b had the opposite effect, confirming direct targeting of IRS1 by miR-487b.Immunohistochemistry of aortic cross sections and rt/qPCR analyses of the separate aortic wall layers showed that both IRS1 and miR-487b were present mainly in the adventitia and less or not at all in the intima and tunica media. IRS1 expression in adventitial fibroblasts was predominantly nuclear and nuclear IRS1 is known to have antiapoptotic effects. Indeed, inhibition of miR-487b protected adventitial fibroblasts, and also medial smooth muscle cells, against serum starvation-induced apoptosis and increased cell survival.
Angiotensin II-induced hypertension leads to upregulation of miR-487b, which targets IRS1. Via downregulation of IRS1, miR-487b can contribute to cell death and loss of adventitial and medial integrity during hypertension-induced vascular pathology.
在出现严重心血管疾病症状之前，研究微 RNA 在高血压引起的血管病变中的作用。
微 RNA 在心血管疾病中发挥着关键作用。然而，微 RNA 通常在心血管疾病的全面发病模型中进行研究，而不是在心血管病理发生发展过程中进行研究。
将血管紧张素 II 输注到健康成年大鼠体内，诱导慢性高血压，并获得微 RNA 表达谱。进一步研究了表达谱中最显著调节的微 RNA，miR-487b，使用大鼠主动脉和人脐带动脉细胞的原代培养物进行研究。
miR-487b 被预测为胰岛素受体底物 1（IRS1）的靶标。IRS1 在胰岛素信号转导和细胞增殖和存活中都起着重要作用。高血压大鼠主动脉中 IRS1mRNA 和蛋白水平下调。miR-487b 直接结合大鼠和人 IRS1 3'UTR，并在体外抑制报告基因表达。在原代大鼠和人动脉外膜成纤维细胞中，抑制 miR-487b 导致 IRS1 表达上调。上调 miR-487b 则产生相反的效果，从而证实 miR-487b 直接靶向 IRS1。主动脉横切片的免疫组织化学和对主动脉壁各层的 rt/qPCR 分析表明，IRS1 和 miR-487b 主要存在于外膜中，在内膜和中膜中很少或不存在。外膜成纤维细胞中 IRS1 的表达主要是核内的，已知核内 IRS1 具有抗凋亡作用。事实上，抑制 miR-487b 可保护外膜成纤维细胞，也可保护中膜平滑肌细胞免受血清饥饿诱导的凋亡并增加细胞存活。
血管紧张素 II 诱导的高血压导致 miR-487b 的上调，miR-487b 靶向 IRS1。通过下调 IRS1，miR-487b 可能导致高血压引起的血管病变过程中外膜和中膜细胞死亡和完整性丧失。
