IRAK4对心肌细胞凋亡的影响

Effects of IRAK4 on Myocardial Apoptosis

目的探讨白介素-1受体相关激酶-4(interleukin 1 receptor-associated kinase-4,IRAK-4)对心肌肥厚诱导的心肌细胞凋亡的影响。方法本研究采用野生型(C57)和IRAK4基因敲除型(heterozygous IRAK4 knockout,IRAK4 HET)两组小鼠,行胸主动脉缩窄术(aortic banding,AB)建立动物模型。术后4周取材,用TUNEL法检测心肌组织细胞凋亡水平,Western blot法检测Bcl-2、Bax、C-caspase-3的表达水平。观察IRAK4基因敲除对压力负荷诱导的小鼠心肌组织中心肌细胞凋亡的影响;采用H9C2细胞(对照组)和IRAK4过表达的H9C2细胞(pc DNA3.1-IRAK4),使用血管紧张素Ⅱ(AngⅡ)分别刺激0、15、30、60min,用Western blot法检测各组细胞中Bcl-2、Bax、C-caspase-3的表达水平;AngⅡ组和pc DNA3.1-IRAK4组细胞经AngⅡ刺激48h后,用TUNEL法检测心肌细胞凋亡水平。观察IRAK4过表达对AngⅡ诱导的心肌细胞凋亡的影响。结果 AB术后,与C57组小鼠相比,IRAK4 HET小鼠Bax、C-caspase-3蛋白表达水平显著增高,Bcl-2蛋白表达水平降低,心肌细胞凋亡水平明显增加;AngⅡ刺激后,与AngⅡ组细胞比较,PC DNA3.1-IRAK4组细胞Bcl-2的表达水平上调,Bax、C-caspase-3的表达水平下调,细胞凋亡数量明显降低。结论 IRAK4对心肌肥厚所诱导的心肌细胞凋亡具有保护作用。

Objective To observe the effect of Interleukin 1 receptor - associated kinase - 4 （ IRAK4 ） on myocadial apnptosis in- duced by cardiac hypertrophy. Methods Wild type C57 mice and heterozygous IRAK4 knockout mice（IRAK4 HET mice）were divided into two groups. Each group used aortic banding （AB） to establish animal models, observed the apoptosis of myocardial cells in each group after 4 weeks. The apoptosis of myocardial cells were tested by TUNEL method. The protein levels of Bcl - 2, Bax and C - caspase - 3 were detected by western blotting. We observed the effect of apoptosis in myocardial cells induced by pressure overload in het- erozygous IRAK4 knockout mice. In vitro studies were performed usiag H9C2 ceils （ Aug Ⅱ ） and IRAK4 - overexpressed H9C2 ceils（ pcD- NA3.1 - IRAK4）. The protein levels of Bcl - 2, Bax and C - caspase - 3 were detected by western blotting after angiotensin Ⅱ （Ang Ⅱ ） stimulation for 0, 15, 30, 60min, cardiac myocytes apoptosis was tested by TUNEL. We observed the effects of 1RAK4 - overexpres- sion on the apoptosis of myocardial cells induced by Ang Ⅱ . Results After aortic banding, the protein expression levels of Bax and C - caspase - 3 were significantly increased in IRAK4 HET mice compared with C57 group, while the protein expression levels of Bcl - 2 was evidently reduced, and the level of myocardial apoptosis was significantly increased. Compared with Ang Ⅱ group, the expression level of Bcl - 2 in PCDNA3. 1 - IRAK4 cells was up - regulated, the expression levels of C - caspase - 3 and Bax were down - regulated after stimulation of Ang Ⅱ , the apoptosis of PCDNA3.1 - IRAK4 cells was significantly decreased. Conclusion IRAK4 has protective effects on myocardium by preventing myocardial apoptosis induced by cardiac hypertrophy.