lncRNA GAS5调控自噬在脓毒症性心肌损伤中的作用

Sepsis is a common and critical disease which seriously threatens human health. The primary reason for its high mortality is the dysfunction of important organs induced by sepsis, such as heart and lung. Our preparatory experiment found that long noncoding RNA GAS5 showed exceptional high expression in the myocardium of septic mice and the serum samples from patients with sepsis. In view of GAS5 is known as a negative regulator of autophagy, and previous studies have suggested that the activation of autophagy is able to inhibit sepsis-induced myocardial damage, we propose the following hypothesis: sepsis → high expression of GAS5→inhibition of autophagy in cardiomyocytes and mitophagy→incapacity to eliminate the damaged cardiomyocytes and mitochondria→aggravation of mitochondrial damage and oxidative stress → sepsis-induced myocardial injury. We planned to observe whether high or low expression of GAS5 can regulate cellular autophagy and mitophagy in cultured murine cardiomyocytes; whether the inhibition of autophagy and mitophagy leads to mitochondrial damage and oxidative stress, and explore the potential signaling pathways that GAS5 may regulate autophagy and mitophagy. In murine sepsis model, we further verify the effects of abnormal high expression of GAS5 on myocardial autophagy and mitophagy, mitochondrial damage and oxidative stress, and myocardial injury. This study will preliminary elucidate the effects of GAS5 on septic myocardial injury and its potential regulatory mechanisms, so as to provide a new target to improve the prognosis of sepsis.

脓毒症是严重威胁人类健康的常见危重疾病，其死亡率高企的根本原因在于脓毒症诱发的心、肺等重要脏器功能障碍。我们的预实验发现长链非编码RNA GAS5在脓毒症小鼠心肌组织和脓毒症患者血清均呈现异常高表达。鉴于GAS5具有负向调控自噬的功能，而以往的研究表明激活自噬能够抑制脓毒症性心肌损害，我们提出如下假说：脓毒症→GAS5异常高表达→抑制心肌细胞和线粒体自噬→受损心肌细胞及其线粒体清除受阻→加剧线粒体损伤和氧化应激→脓毒症性心肌损伤。为此，我们拟在小鼠心肌细胞观察GAS5过表达和低表达能否调控细胞及线粒体自噬，抑制自噬是否加剧线粒体损伤和氧化应激，并探讨GAS5调控自噬可能的信号通路；在小鼠脓毒症模型进一步验证GAS5异常高表达对心肌细胞和线粒体自噬，对线粒体损伤和氧化应激以及心肌损伤的影响。本研究将初步阐明GAS5对脓毒症性心肌损伤的影响及其潜在的调控机制，为提高脓毒症患者的预后提供新靶标。

脓毒症是严重威胁人类健康的常见危重疾病，其死亡率高企的根本原因在于脓毒症诱发的心、肺等重要脏器功能障碍。本研究在脓毒症心肌损伤动物模型证明lncRNA GAS 5呈现LPS浓度依赖的高表达，且主要在心肌细胞核内表达，脓毒症的发生与心肌细胞自噬和线粒体自噬均相关。应用腺病毒载体和Smart Silencer对心肌细胞中GAS 5进行的过表达和干扰的研究表明，GAS 5过表达时，p-AMPK的表达水平明显降低，p-mTOR和p-AKT的表达量明显升高，因而心肌细胞的自噬得到抑制。但对于线粒体自噬相关蛋白PINK1，GAS 5却没有表现出相应的调控作用。GAS5干扰明显抑制了LPS孵育导致的心肌细胞炎症介质水平上升，显著改善了LPS导致的ATP下降的趋势，减轻了LPS诱导的心肌细胞氧化应激反应，而GAS5过表达则加重了炎症介质释放，ATP的浓度下降以及氧化应激水平。透射电镜也表明LPS孵育的心肌细胞导致线粒体损伤严重，但GAS5干扰可以显著减轻脓毒症过程中的线粒体损伤。因而本研究初步阐明了GAS5通过抑制心肌细胞自噬而减轻脓毒症所致的线粒体损伤，为提高脓毒症，尤其是合并脓毒症性心肌损伤等多脏器功能不全患者的临床疗效提供新靶标。