Ghrelin通过miR-208家族调控UCP2表达改善心衰心肌代谢重构的机制研究

Energy metabolisc disorder plays a role in cardiac function deterioration and may become the new target for treatment of heart failure. The growth hormone–releasing peptide ghrelin could regulate energy metabolism. Our previous studies have found that ghrelin could inhibit myocardial remodeling by down-regulating Ang II type 1 (AT1) receptor expression. Myocardial remodeling could be significantly attenuated by down-regulating the expression of mitochondrial uncoupling protein 2 (UCP2), which was found to be a regulator of myocardial energy metabolism. By high-throughput sequencing, microRNA-208 was found to be expressed differently in myocardial tissue between heart failure and normal rats. Moreover, studies have shown that miR-208 was involved in myocardial remodeling through regulating the AT1 receptor. There for, we assume that ghrelin improves the energy metabolism disorders mediated by AT1 receptor via regulate the UCP2 expression through miR-208. In this study, the rat model of heart failure will be established and the primary rat cardiomyocytes will be cultured, gene silencing, gene overexpression and other methods will be used to explore the relationship of miR-208 family members and the UCP2 expression, and the influence on myocardial metabolic remodeling. Silencing specific genes with siRNA or application specific blocker will be used to clear the readjustment of ghrelin receptors (GHSR1a/GHS - R1b) and PI3K/Akt pathway on miR-208, which will further reveal the anti-heart failure mechanisms of ghrelin.

能量代谢紊乱是心功能不断恶化的因素并可能成为新的治疗靶点，Ghrelin是调节能量代谢的促生长激素释放多肽。我们前期研究发现Ghrelin可通过下调AT1受体抑制心肌重构；下调影响能量代谢的线粒体内膜解偶联蛋白2 (UCP2)可改善心肌重构；我们还在心衰心肌的高通量测序中发现miRNA-208存在差异性表达，且有研究表明其可通过AT1受体参与心肌重构。我们假设Ghrelin可通过miRNA-208家族调控UCP2并改善由AT1受体介导的能量代谢紊乱。我们将建立动物实验模型及细胞实验，采用基因沉默/过表达等方法探究心衰心肌miRNA-208家族成员与UCP2下调的关系及对心肌代谢重构的影响，通过细胞转染沉默相关基因及特异性阻断剂明确Ghrelin受体（GHSR1a/GHS-R1b）及受体后PI3K/Akt通路对miRNA-208家族的调控作用，进一步揭示ghrelin的抗心衰作用。

能量代谢紊乱是心功能不断恶化的因素并可能成为新的治疗靶点，Ghrelin是调节能量代谢的促生长激素释放多肽。我们前期研究发现Ghrelin可抑制心肌重构；下调影响能量代谢的线粒体内膜解偶联蛋白2 (UCP2)可改善心肌重构；我们还在心衰心肌的高通量测序中发现miRNA-208存在差异性表达。然而，上述三者之间的关系尚不明确。本研究通过构建心梗后心衰大鼠模型及体外心肌细胞模型，深入探讨了心衰患者miR-208b-5p的表达水平；探讨了Ghrelin对心衰不同时期心功能的影响；探讨了上调miR-208a-3p 及下调miR-208b-5p对心梗后4周心功能的影响；探讨了Ghrelin对心衰不同时期心肌梗死面积的影响；探讨了Ghrelin对心肌代谢及UCP2的影响；探讨了Ghrelin 对 miR-208a-3p 及miR-208b-5p表达的影响；明确了Ghrelin对心肌细胞凋亡的影响；阐明了Ghrelin改善心梗后心衰大鼠心功能的可能机制：可通过上调Ghrelin受体GHSR-1a及GHSR-1b表达，进而上调miR-208a-3p 及miR-208b-5p表达，改善心梗后心衰心肌代谢、抑制心梗后心衰大鼠心肌细胞凋亡。以上问题的阐明，对阐明心衰机制、寻找治疗心衰的新靶点具有重要意义。.本课题取得成果如下：项目资助已发表SCI论文12篇（尚有2篇待发表），核心论文3篇；本课题已培养博士研究生9名，其中4名已毕业，5名仍在读，预计2020年6月答辩；培养硕士研究生5名，均已取得硕士学位。课题负责人以本课题的研究成果作为心衰网络调控机制的一部分，于2016年度申报并获得吉林省科学技术进步奖一等奖。此外，在本课题成果的支持下，课题负责人于2016年度获得国家发改委资助500万元，建立吉林省心血管重大疾病精准医学分子生物学实验中心，单位配套经费：2500万元。

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