KLF15基因敲除加重急性心肌梗死小鼠心肌损伤

KLF15 deficiency aggravates acute myocardial infarction injury in mice

目的:探讨Kruppel样因子15(Kruppel-likefactor 15,KLF15)基因在小鼠心肌梗死后对心肌损伤的作用。方法:冠状动脉左前降支结扎术建立小鼠心肌梗死模型。RT-qPCR检测心肌梗死术后0、1、3和7 d心脏组织中KLF15的mRNA表达变化。野生及KLF15基因敲除小鼠心肌梗死术后28 d,使用小动物心脏超声仪测定心功能变化,Masson染色比较梗死纤维瘢痕,麦胚凝集素(wheatgermagglutinin,WGA)染色评价心肌细胞肥大情况。分离心肌梗死术后3 d的心脏组织,使用RT-qPCR检测凋亡相关蛋白(Bax和Bcl-2)及促炎因子(IL-6和IL-1β)的mRNA表达变化,TUNEL染色评价细胞凋亡情况,Westernblot检测磷酸化p65水平。萤光素酶报告基因实验检测缺氧处理的H9C2心肌细胞中KLF15对核因子κB(nuclearfactor-κB,NF-κB)转录活性的调控。结果:心肌梗死术后1 d小鼠心脏组织中KLF15表达下降。术后28 d,与野生小鼠相比,KLF15基因敲除小鼠心功能显著下降,梗死纤维瘢痕面积增大,非梗死区心肌细胞代偿性肥大。术后3 d,KLF15基因敲除小鼠心脏组织中促凋亡蛋白Bax表达升高,抗凋亡蛋白Bcl-2表达降低,TUNEL阳性细胞核比例增多,促炎因子IL-6和IL-1β的mRNA水平升高,磷酸化p65水平升高。在H9C2细胞中过表达KLF15基因可抑制缺氧诱导的NF-κB转录活性。结论:KLF15通过抑制NF-κB活化介导的细胞凋亡及炎症在心肌梗死中发挥保护心肌的作用。

AIM:To explore the role of Kruppel-like factor 15(KLF15)gene in cardiac remodeling after myocardial infarction(MI).METHODS:The MI model of permanent ligation of left anterior descending coronary artery in mice was used.RT-qPCR was performed to detect KLF15 mRNA expression in hearts after MI surgery.At 28 d after MI injury,ultrasound was used to detect the cardiac function,Masson staining was performed to evaluate cardiac fibrosis,and wheat germ agglutinin(WGA)staining was used to measure cardiomyocyte size.At 3 d after MI injury,the mRNA levels of apoptosis-related proteins(Bax and Bcl-2)and inflammatory factors(IL-6 and IL-1β)were detected by RT-qPCR.TUNEL staining was performed to detect the apoptosis of cardiomyocytes.The level of phosphorylated p65 was detected by Western blot.The effect of KLF15 on nuclear factor-κB(NF-κB)transcriptional activity was detected by luciferase reporter assay.RESULTS:KLF15 was down-regulated in hearts at 1 d after MI injury.At 28 d after MI injury,compared with the WT mice,KLF15 KO mice showed decreased cardiac function,and increased scar fibrosis and cardiomyocyte size.At 3 d after MI injury,the mRNA level of pro-apoptotic protein Bax was up-regulated,while anti-apoptotic protein Bcl-2 was downregulated in KLF15 KO mice.The percentage of TUNEL-positive cells and the levels of inflammatory cytokines IL-6 and IL-1βwere higher in KLF15 KO mice than those in WT mice.Western blot and luciferase reporter assay showed that KLF15 inhibited hypoxia-induced NF-κB activation in vivo and in vitro.CONCLUSION:KLF15 protects against cardiomyocyte injury after MI through preventing NF-κB activation.