SIK2通过Akt/mTOR转导途径调节细胞自噬对减轻心肌缺血/再灌注损伤的研究

SIK2 Regulates Autophagy Through Akt/mTOR Transduction Pathway to Reduce Myocardial Ischemia/Reperfusion Injury

目的探讨盐诱导激酶2(saltinduceskinase2,SIK2)对大鼠心肌缺血/再灌注损伤的调控作用,及对蛋白激酶B(proteinkinaseB,Akt)/哺乳动物雷帕霉素靶蛋白(mammaliantargetofrapamycin,mTOR)通路的影响。方法将15只SD雄性大鼠随机分为假手术组、模型组(心肌缺血/再灌注损伤模型)、SIK2抑制剂组(造模前24h给予10mg/kg博舒替尼),每组5只大鼠。采用超声仪检测大鼠心脏功能,苏木精-伊红(hematoxylin-eosin,HE)染色评估心肌组织病理学情况,透射电镜观察心肌细胞自噬情况,Westernblot检测心肌组织Akt/mTOR通路(SIK2、p-Akt、Akt、p-mTOR、mTOR)以及自噬(Beclin-1、LC3-Ⅱ/LC3-Ⅰ、p62)相关蛋白表达水平。结果3组大鼠左心室后壁厚度(leftventricular posteriorwall,LVPW)、室间隔(interventricularseptum,IVS)组间比较差异无统计学意义(P>0.05),SIK2抑制剂组左心室短轴缩短率(leftventricularfractionshort,LVFS)以及左心室射血分数(leftventricularejectionfractions,LVEF)均高于模型组、低于假手术组(P均<0.01),模型组LVFS、LVEF均低于假手术组(P均<0.01)。与假手术组比较,模型组心肌组织病理损伤明显,自噬小体明显增加,SIK2抑制剂组心肌组织病理损伤、心肌细胞自噬情况较模型组明显改善。SIK2抑制剂组Beclin-1、LC3-Ⅱ/LC3-Ⅰ蛋白表达量低于模型组、高于假手术组,p62蛋白表达量高于模型组、低于假手术组(P均<0.05)。3组大鼠Akt、mTOR表达水平差异无统计学意义(P均>0.05),SIK2抑制剂组SIK2水平高于假手术组、低于模型组,而p-Akt、p-mTOR水平高于模型组,模型组p-Akt、p-mTOR水平低于假手术组(P均<0.05)。结论抑制SIK2可减少心肌细胞异常自噬,改善心肌缺血/再灌注损伤,其作用机制可能与SIK2调控Akt/mTOR信号通路有关。

Objective To investigate the regulation of salt induces kinase 2(SIK2)on myocardial ischemia/reperfusion injury in rats and its effects on protein kinase B(Akt)/mammalian target of rapamycin(mTOR)pathway.Methods A total of 15 SD male rats were randomly divided into sham surgery group,model group(myocardial ischemia/reperfusion injury model)and SIK2 inhibition group(10 mg/kg bosutinib was given 24 hours before modeling),with 6 rats in each.Cardiac function was detected by ultrasound,myocardial histopathology was evaluated by hematoxylin-eosin(HE)staining,autophagy was observed by transmission electron microscopy,and expression levels of myocardial Akt/mTOR pathway(SIK2,p-Akt,Akt,p-mTOR,mTOR)and autophagy(Beclin-1,LC3-Ⅱ/LC3-Ⅰ,p62)related proteins were detected by Western blot.Results There was no significant difference in left ventricular posterior wall(LVPW)and interventricular septum(IVS)among the 3 groups(P<0.05),the left ventricular fraction short(LVFS)and left ventricular ejection fractions(LVEF)in the SIK2 inhibition group were higher than those in the model group and lower than those in the sham surgery group(all P<0.01),LVFS and LVEF in model group were lower than those in the sham surgery group(all P<0.01).Compared with the sham surgery group,the pathological injury of myocardial tissue were obvious and autophagy of myocardial cells significantly increased in the model group,while the pathological injury of myocardial tissue and autophagy of myocardial cells in the SIK2 inhibition group were significantly improved.The protein expression levels of Beclin-1,LC3-Ⅱ/LC3-Ⅰin SIK2 inhibition group were lower than those in model group and higher than those in sham surgery group,while the protein expression levels of p62 were higher than those in model group and lower than those in sham surgery group(all P<0.05).There was no significant difference in the expression levels of Akt and mTOR among the 3 groups(all P<0.05),the level of SIK2 in the SIK2 inhibition group was higher than that in the sham surgery group but lower than that in the model group,while the level of p-Akt and p-mTOR was higher than that in the model group,and the levels of p-Akt and p-mTOR in the model group were lower than those in the sham surgery group(all P<0.05).Conclusion Inhibition of SIK2 can reduce abnormal autophagy of myocardial cells and improve myocardial ischemia/reperfusion injury,its mechanism may be related to the regulation of Akt/mTOR signaling pathway by SIK2.