NDUFA13乙酰化促进OMA1/OPA1剪切介导急性心肌缺血再灌注损伤机制的研究

Reperfusion therapy can significantly improve the prognosis of acute myocardial infarction, however, the ischemia-reperfusion (I/R) injury significantly compromise the benefit of reperfusion therapy. Our preliminary experimental results found that OMA1/OPA1 cleavage induced damage of mitochondrial structure was the key contributing factor to the I/R injury, moreover, acetylation of fifth-amino lysine (K5) on NDUFA13 can initiate OMA1/OPA1 cleavage, but the exact mechanism remains unclear. Our recent experimental results found that NDUFA13-K5 acetylation prevented it from anchoring to mitochondrial inner membrane, and may subsequently induce H2O2 production and its physical interaction with PHB, thus, we propose a theoretical hypothesis: subcellular redistribution occur after NDUFA13-K5 acetylation, which in turn regulates H2O2 and PHB signaling pathways to promote OMA1/OPA1 cleavage. Based on virus-mediated transfection for expressing NDUFA13-K5Q and NDUFA13-K5R in neonatal cardiomyocytes, and based on Sirt3 (+/-) mice and Sirt3 (+/-) / Myh6 (Cre+) NDUFA13 (flox/-) transgenic mice, the above hypothesis will be validated at the molecular, cellular and animal levels, which provides new molecular targets to maintain mitochondrial structure to treat I/R injury in clinic.

再灌注治疗显著改善急性心肌梗死的预后，然而心肌缺血再灌注（I/R）损伤显著降低再灌注治疗带来的获益。我们前期发现OMA1/OPA1剪切造成的线粒体结构破坏是介导I/R损伤的关键因素，且NDUFA13上5号赖氨酸（K5）乙酰化促进OMA1/OPA1剪切启动，但确切机制不明。我们新近发现NDUFA13-K5乙酰化影响其线粒体内膜锚定，可能介导H2O2生成并与PHB相互作用，由此提出假说：NDUFA13-K5乙酰化修饰后其细胞定位发生改变，进而调控H2O2和PHB信号通路促进OMA1/OPA1剪切。基于NDUFA13-K5Q和NDUFA13-K5R病毒转染乳鼠心肌细胞，以及基于Sirt3（+/-）和Sirt3（+/-）/Myh6（Cre+）NDUFA13（flox/-）基因模型小鼠，本项目拟在分子、细胞和动物整体水平验证以上假说，为临床上以线粒体结构调节为切入点治疗I/R损伤提供新的干预靶点。

心肌缺血及心肌肥厚等心脏病理过程最终进展为心力衰竭，显著增加患者再住院率及死亡率。本项目主要研究心肌细胞在病理过程中线粒体结构破坏原因，尤其是线粒体脊重塑的具体原因，针对线粒体脊结构相关的PHB1/2聚合体展开研究，阐明其形成和破坏的确切机制，拟为线粒体脊结构调控提供新的干预靶点。 我们发现NDUFA13-K7乙酰化导致NDUFA13的线粒体亚定位发生改变，使得更多的NDUFA13转移至线粒体内外膜间质并与PHB1/2聚合体相互作用，进而促进了PHB1/2聚合体的破坏，随后导致PHB1/2聚合体依赖的针对OMA1的抑制作用的减弱，进而导致OPA1的过度剪切。总之，我们的研究在分子水平上详细分析了NDUFA13-K7乙酰化后调控PHB1/2聚合体形成，从而破坏线粒体形态功能的具体机制。因此，调控NDUFA13-K7乙酰化可以作为临床上预防心室重构和治疗心肌缺血再灌注的有效方式。