miRNA-199a-3p对模拟失重导致心肌重塑的调控作用及机制研究

Studies on the mechanisms of post-flight cardiovascular deconditioning and its countermeasures have important theoretical and practical implications to fully unravel the cardiovascular effects of microgravity. Mounting evidence has indicated that virtually all aspects of cardiac function and adaptation are under the control of the microRNA (miRNA) network. Our previous research showed that simulated-microgravity lead to cardiac remodeling and function declining, and in the early stage of recovery, remodeling is more intensified. Western blot demonstrated that the phosphorylation level of AMPK was decreased, so did the mRNA level of LKB1, which is the kinase of AMPK and the target of miR-199a-3p. We also found that hindlimb unloading (HU) led to upregulation of miR-199a-3p in heart; and the miRNA continued to increase following hindlimb reloading (HR) for 7 days, and recovered following HR for 14 days, which implied that miR-199a-3p may be involved in the regulation of cardiac remodeling that caused by HU and HR. In this project, we will explore the regulation mechanism of miR-199a-3p in weightless-induced cardiac remodeling. This study will promote us to understand the mechanisms of cardiac remodeling induced by spaceflight and develop countermeasures against physiological problems during weightlessness.

航天飞行后心血管失调的机理及其对抗措施问题的解决，首先要了解失重状态下及负荷恢复后心肌重塑发生的分子机制。microRNA作为基因转录后调控的关键分子在心肌重塑的调控中发挥重要作用。我们前期研究发现尾吊模拟失重导致小鼠心肌重塑、功能下降，而去除尾吊负荷恢复初期心肌重塑进一步加剧，其中代谢通路关键信号AMPK的磷酸化水平明显下降，其上游激酶LKB1的mRNA水平明显下降。预实验结果显示，能够靶向Lkb1 的miR-199a-3p在尾吊及恢复的小鼠心脏组织中表达明显升高，与尾吊模拟失重及负荷恢复导致的心肌重塑高度相关。因而本项目从人体卧床变化的循环miRNA入手，结合小鼠尾吊及恢复模型，研究miR-199a-3p对模拟失重及负荷恢复导致心肌重塑的调控作用及机制，为航天飞行后心血管失调的机理及其对抗措施问题的研究提供新的思路和研究基础。

解析失重状态下心肌重塑发生的分子机制，对航天飞行后心血管失调的机理及其对抗措施问题的解决至关重要。microRNA作为基因转录后调控的关键分子在心肌重塑的调控中发挥重要作用。预实验结果显示，能够靶向Lkb1 的miR-199a-3p在尾吊小鼠心脏组织中表达明显升高，与尾吊模拟失重导致的心肌重塑高度相关。我们前期研究发现尾吊模拟失重导致小鼠心肌重塑、功能下降，其中代谢通路关键信号AMPK的磷酸化水平明显下降，其上游激酶LKB1的mRNA水平明显下降。因而本项目从人体卧床变化的循环miRNA入手，结合小鼠尾吊模型，研究miR-199a-3p对模拟失重导致心肌重塑的调控作用及机制。通过构建心肌特异性miR-199a-3p转基因小鼠并进行尾吊，利用小动物心脏超声、Western blot、Q-PCR、组织病理学染色等手段对小鼠心脏结构、功能和分子指标进行分析，我们发现miR-199a-3p适量过表达对正常状态下的心脏无明显影响，能够有效对抗尾吊模拟失重导致的心肌重塑，而miR-199a-3p大量过表达则会造成心肌重塑、功能下降；miR-199a-3p可通过靶向Lkb1调控AMPK活性，影响心肌代谢进而调控心肌功能。利用腺病毒包裹心肌特异表达的miR-199a-3p能够有效对抗尾吊模拟失重导致的心肌重塑。本研究为航天飞行后心血管失调的机理及其对抗措施问题的研究提供新的思路和研究基础。