GLP-1经CaMKII/AMPK调控线粒体分裂减少心肌再灌注梗死的机制研究

Reperfusion infarction, namely lethal reperfusion injury, is a key risk factor that significantly impact the prognosis of patients with acute myocardial infarction. However, no effective therapy currently exists for reducing the size of reperfusion infarction in patients undergoing primary PCI. Opening of mPTP induced by mitochondrial fission plays important role in lethal reperfusion injury. The pleiotropic properties of GLP-1 render it specifically suited to protecting tissue against ischemia/reperfusion injury. Our previous clinical trials have showed GLP-1 reduces myocardial infarction size in patients with acute myocardial infarction undergoing primary PCI and improves their heart function. Our basic research showed effects of GLP-1 on preventing cardiomyocytes and endothelial cells against hypoxia/reoxygenation injury. GLP-1 attenuates intracellular calcium overload and protects mitochondrial function against oxidative stress. This project will investigate the mechanism through which GLP-1 exerts protective effect against reperfusion infarction through inhibiting mitochondrial fission and opening of mPTP via CaMKII/AMPK pathways, especially focus on the mechanism underlying the effects of GLP-1 on mitochondrial fission proteins (Drp1/Mff), p53/CypD and HK2/VDAC1. The project will provide more convincing evidences for GLP-1 to be used to prevent reperfusion infarction for patients with acute myocardial infarction and put new insights into the mechanism underlying reperfusion infarction.

再灌注梗死是影响急性心肌梗死患者预后的重要因素，目前临床上尚无有效防治措施。线粒体过度分裂促进mPTP开放是心肌细胞缺血再灌注死亡的重要机制。我们前期临床研究显示GLP-1有效减少急性心肌梗死患者再灌注治疗后的梗死面积、改善心功能；基础研究显示GLP-1有效减轻缺氧复氧后细胞钙超载、保护线粒体功能。在相关研究基础上，本项目将在整体、细胞、细胞器及分子水平着力明确GLP-1通过心肌细胞CaMKII/AMPK调控线粒体分裂、抑制线粒体mPTP开放从而减轻心肌再灌注梗死的机制，阐明GLP-1经CaMKII/AMPK对线粒体分裂蛋白（Drp1/Mff）的作用及机制，明确GLP-1对p53/CypD、HK2/VDAC1的调控作用。该研究将为GLP-1用于临床防治心肌再灌注梗死提供详实的理论依据，同时为进一步明确再灌注梗死的发生机制提供新视角。

心肌再灌注损伤是影响心梗患者预后的重要因素，在本课题的资助下，我们主要研究了心肌再灌注损伤的机制，探索了Ripk3加重心肌再灌注损伤的机制以及褪黑素保护心肌再灌注损伤的机制，明确了Ripk3在心肌再灌注损伤时表达增多，通过钙超载、氧化应激等机制促进血管内皮细胞再灌注损伤，内皮细胞功能下降，从而损伤心肌微循环；明确了Ripk3在IR损伤的小鼠心脏以及LPS和H2O2处理的心肌细胞中表达明显上调，较高的Ripk3水平与梗死面积扩大、心功能障碍、心肌细胞坏死加剧呈正相关；功能研究进一步表明，上调Ripk3诱发了内质网(ER)应激，并伴随着细胞内Ca2+水平和黄嘌呤氧化酶(XO)表达的增加；激活XO可提高细胞活性氧(ROS)，从而介导线粒体通透性过渡孔(mPTP)开放和心肌细胞坏死；基因敲除Ripk3可消除内质网应激，从而阻断钙过/XO/ROS/ mPTP通路，最终抑制心肌细胞坏死性凋亡；褪黑素则可抑制Ripk3上调，通过抑制Ripk3-PGAM5-CypD-mPTP减少内皮细胞坏死性凋亡，保护心肌微循环，从而减少心肌再灌注损伤。在结余经费的支持下，我们将继续探索线粒体损伤在心肌损伤中的作用及机制。