miR-497下调MFN2缓解异丙基肾上腺素诱导的心肌损伤

miR-497 attenuates isoproterenol-induced myocardial injury by down-regulating expression of MFN2

目的探讨microRNA-497(miR-497)对异丙基肾上腺素诱导的心肌损伤的作用及机制。方法 30只雄性C57BL/6小鼠随机分为三组:对照组(每日背部皮下注射与模型组同剂量的生理盐水,持续10 d),模型组[每日背部皮下注射5 mg/kg的异丙基肾上腺素(ISO),持续10 d]及激动剂组(在注射ISO的同时给予心肌内注射100μl 10nmol的miR-497-5p激动剂),每组各10只。检测三组小鼠心功能[心率(HR)、左室收缩内压(LVESP)、左室舒张内压(LVEDP)、左室内压最大上升速率(±dp/dtmax)及心输出量(CO)]、心肌损伤[心肌肌钙蛋白T(c Tn-T)、心肌肌钙蛋白I(c Tn-I)、N-端脑利钠肽前体(NT-pro BNP)、肌酸激酶同工酶(CK-MB)及肌红蛋白(Mb)]等指标及心肌中线粒体融合蛋白2(MFN2)、Caspase-3、Fas、Bcl-2及Bax等的表达。结果模型组中LVESP、±dp/dtmax及CO的水平显著低于对照组(P <0. 05),LVEDP、Tn T、Tn I、NT-pro BNP、CK-MB及Mb水平高于对照组(P <0. 05)。而激动剂组的HR、LVESP、±dp/dtmax及CO的水平显著高于模型组(P <0. 05),LVEDP、TnT、TnI、NT-proBNP、CK-MB及Mb水平低于模型组(P <0. 05)。模型组中MFN2、Caspase-3、Fas及Bax的mRNA和蛋白的表达显著高于对照组(P <0. 05),Bcl-2的表达低于对照组(P <0. 05)。而激动剂组中MFN2、Caspase-3、Fas及Bax的表达显著低于模型组(P<0. 05),Bcl-2的表达高于模型组(P <0. 05)。结论 miR-497可改善异丙基肾上腺素诱导的小鼠心肌损伤,其机制与抑制MFN2表达并阻止心肌细胞凋亡有关。

Objective To investigate effects of miR-497 on myocardial injury.Methods 30 male C57BL/6 mice were randomized into 3 groups:control group(n=10)with subcutaneous saline injection,same dose as model group for 10 d;model group(n=10)with 5 mg/kg of subcutaneous isoproterenol injection for 10 d;and agonist group(n=10),same isoproterenol+intramyocardial injection of miR-497-5p 10 nmol in 100μl.Expressions of MFN2,Caspase-3,Fas,Bcl-2 and Bax in myocardium and indicators regarding cardiac function and myocardial injury were detected.Results Levels of LVESP,±dp/dtmax and CO in model group were significantly lower than in control group(P<0.05)while levels of LVEDP,TnT,TnI,NT-proBNP,CK-MB and Mb were higher than in control group(P<0.05).Levels of HR,LVESP,±dp/dtmax and CO in agonist group were significantly higher than in model group(P<0.05),while levels of LVEDP,TnT,TnI,NT-proBNP,CK-MB and Mb were lower than in model group(P<0.05).MFN2,Caspase-3,Fas and Bax expressions in model group were significantly higher than in control group(P<0.05)while Bcl-2 expression was lower than in control group(P<0.05).MFN2,Caspase-3,Fas and Bax expressions in agonist group were significantly lower than in model group(P<0.05),while Bcl-2 expression was higher than in model group(P<0.05).Conclusion MiR-497 can attenuate myocardial injury.The mechanism is related to MFN2 inhibition and cardiomyocyte apoptosis prevention.