心力衰竭交感神经兴奋亢进新机制：下丘脑室旁核内源性miR-9的作用

Chronic heart failure (CHF) is characterized by sympathetic overactivity, which significantly increase CHF morbidity and mortality. The exact mechanisms of sympathetic overactivity in CHF are not known. miRNA research has made a remarkable progress in Alzheimer's Disease, however, the mechanism by which miRNA exacerbates CHF by increasing sympathetic activity remains unclear. The results of recent study in the present project show that the angiotensin type 1 (AT1) receptor expression, the transcription factors nuclear factor kappa B (NFKB) and miR-9 are upregulated, however, γ-aminobutyric acid type B receptor ,2 (GABBR2) and glutamic acid decarboxylase (GAD67) are downregulated in hypothalamic paraventricular nucleus in rats with CHF. GABBR2 and GAD67 related sympathetic overactivity in CHF are targets for miR-9(according to TargetScan ). Therefore, in the present study, we hypothesized that AT1 receptor expression significantly upregulated, then upregulated NFKB, which further result in activating miR-9 transcription, as a result, the expressions of GABBR2 and GAD67 are repressed by upregulated miR-9 in hypothalamic paraventricular nucleus, in turn, resulting in sympathetic overactivity, and finally aggravate CHF. This project intends to elucidate the mechanism by which miRNA exacerbates heart failure by increasing sympathetic activity by making use of miR-9 transgenic mice and molecular biological techniques (e.g. quantitative real-time PCR, western blot, and transient transfection, ect.). It will provides new tactics for clinical prevention and treatment of CHF.

交感神经过度兴奋可增加心衰发病率和病死率。目前心衰状态下交感神经过度兴奋的确切机制仍不明确，微小RNA(miR)在阿尔茨海默病中的研究取得重要进展，而miR在心衰状态下交感神经过度兴奋中的作用机制仍然不清楚。本课题前期结果显示心衰大鼠下丘脑室旁核AT1受体、核转录因子NFKB、miR-9表达上调，GABBR2和GAD67表达下调，根据TargetScan软件预测显示GABBR2和GAD67均是miR-9的靶点。因此本课题假设: 心衰后室旁核AT1受体上调，引起NFKB上调，NFKB正向调控miR-9 miR-9表达升高引起GABBR2和GAD67表达下降，导致交感神经过度兴奋，进一步加重心衰。本课题拟采用miR-9 转基因小鼠，应用Real-time PCR、Western blot、转染等分子生物学技术，阐明miR在心衰状态下交感神经过度兴奋中的作用机制，为临床心衰的防治提供新策略。

心血管疾病主要包括高血压、冠心病、充血性心力衰竭等。目前，心血管疾病仍然是人类生命的头号杀手。全世界每年有一千七百万人死于心血管疾病。毫无疑问，预防和治疗心血管疾病是医学与生物学的重大任务。交感神经系统过度激活在慢性心衰的发生、发展和并发症形成中起了极其重要的作用。药物阻滞、射频消融或切除交感神经导致多种副作用和并发症，疗效欠佳。迄今心衰交感神经兴奋亢进机制不详，微小核苷酸(miR)是否为心衰交感神经激活基因未见报道。本项目从慢性心衰的交感神经活动过度激活机制这一关键问题入手，应用多种先进研究方法，从整体、细胞和分子基因水平综合研究下丘脑室旁核(PVN)内致病基因miR介导慢性心衰交感神经过度激活的分子机制。本项目的研究结果首次揭示AT1受体、NFKB、HoxD10、GABRA1、GAD67、GABBR1、GABBR2蛋白和miR-9、miR-7b、miR-137基因表达的相关变化规律；首次发现PVN中AT1受体、miR-9、miR-7b和miR-137在慢性心衰交感神经过度激活中起重要作用，PVN中AT1受体、miR-9、miR-7b和miR-137是干预慢性心衰交感神经活动过度增强机制的重要靶点；首次证实PVN的AT1受体、miR-9、miR-7b和miR-137基因沉默对慢性心衰具有较好的治疗效果，不仅可以有效降低过度激活的交感神经活动，还可以改善慢性心衰的心脏功能；首次阐明miR-9、miR-7b和miR-137分别是机体心衰时心血管中枢整合作用失衡的重要内源性致病基因的机制；首次证实CHF时PVN内上调的miR-9、miR-7b和miR-137诱发中枢整合作用关键分子GABRA1、GAD67、GABBR1和GABBR2蛋白表达下调，从而导致交感神经激活，最终恶化CHF的假说；首次明确PVN 内ANG II 为CHF 发病始动因子；首次确证CHF 状态下PVN 内信号通路ANG II/AT1R/NFKB/miR-9/GAD67/GABBR2和ANG II/AT1R/HoxD10/miR-7b/GABBR1介导CHF大鼠交感神经激活作用。本课题从新的视角成功阐明了慢性心衰发生的分子机制，并为慢性心衰的防治提供新靶点。..