MICU1在心肌缺血损伤中的保护作用

MICU1 protects against myocardial infarction injury

目的探讨线粒体钙离子摄入蛋白1(MICU1)在心肌缺血损伤中是否能够发挥保护作用及其相关机制。方法利用心肌点注射siRNA技术敲低心肌组织中的MICU1水平。48小时后,通过结扎小鼠冠状动脉前降支制备心肌梗死模型。结扎24小时后,利用western blot检测心肌组织中的MICU1含量;利用离子火焰法测定心肌细胞线粒体中Ca2+水平。结扎72小时后,利用JC-1试剂盒及ATP试剂盒分别检测心肌细胞线粒体膜电位及ATP水平;利用Caspase-3试剂盒测定心肌细胞凋亡水平;利用小动物超声检测小鼠心脏功能。结果缺血明显地降低了心肌细胞线粒体膜电位水平,并减少了线粒体ATP生成(均P<0.01)。同时缺血显著地增加了心肌细胞线粒体内Ca2+含量,并降低了线粒体中MICU1的表达(均P<0.01)。通过基因干预手段我们发现,MICU1的敲低明显加重了缺血诱导的线粒体Ca2+超载与线粒体功能抑制(均P<0.01)。另外,MICU1的缺失显著地增加了缺血诱导的心肌细胞凋亡与心功能损伤(均P<0.01)。结论 MICU1能够通过抑制线粒体Ca2+超载来减轻缺血后心肌损伤。

Objective To investigate whether MICU1（mitochondrial calcium uptake1）attenuates myocardial ischemia injury and underlying mechanism.Methods MICU1 Specific small interfering RNA（siRNA）was delivered through intramyocardial injection to knockdown MICU1 levels.After 48 hours,a mice model of myocardial infarction was induced by ligating left anterior descending branch of coronary artery.After 24hours＇ ligation,MICU1 levels were determined by western blot.The mitochondrial Ca^2＋contents measured via atomic absorption flame spectroscopy.After 72hours＇ ligation,mitochondrial membrane potential and ATP contents were detected by JC-1assay kit and ATP assay kit,respectively;cell apoptosis assessed by caspase-3activity assay and cardiac function determined by ultrasound.Results Mitochondrial membrane potential,ATP contents in mice subjected to myocardial infarction were decreased（P〈0.01）.Meanwhile,myocardial ischemia injury significantly increased mitochondrial Ca^2＋contents but decreased MICU1levels（P〈0.01）.With method of genetic intervention,we found that MICU1 deficiency exacerbated mitochondrial Ca^2＋overload and suppressed mitochondrial function（P〈0.01）.Furthermore,MICU1 deficiency aggravated mitochondrial ATP contents and cardiac function induced by ischemia（P〈0.01）.Conclusion MICU1 protects against myocardial ischemia injury induced by Ca2＋overload.