MicroRNA-424通过增加转录因子的表达减轻小鼠缺血性脑损伤

MicroRNA-424 increases the expression of transcriptional factors and reduces the ischemic brain injury in the mouse

目的研究microRNA-424(miR-424)对小鼠脑缺血后神经细胞凋亡及转录因子表达的影响。方法将制备的慢病毒Lenti-miR-424(109U/mL,8μL)通过脑室注射,7 d后采用大脑中动脉线栓闭塞(MCAO)的方法建立小鼠脑缺血模型,动物分4组:假手术组,假手术+miR-424慢病毒,MCAO模型组,MCAO+miR-424慢病毒处理组(n=6)。缺血8 h后取脑组织,石蜡切片进行TUNEL染色,观察神经细胞凋亡的情况;Western blot检测缺血脑组织中转录因子PU.1、低氧诱导因子-1a(hypoxia inducible factor-1a,HIF-1a)、凋亡相关蛋白p53的表达。结果TUNEL免疫荧光观察结果显示,miR-424可以减轻小鼠脑缺血后8 h的神经细胞凋亡;Western blot结果显示,在缺血前和缺血8 h后,miR-424对正常小鼠或MCAO模型脑组织中转录因子的调节趋势是相同的,均增加转录因子PU.1蛋白、HIF-1a蛋白、以及凋亡相关蛋白p53的表达。结论 miR-424可能通过增加小鼠脑组织转录因子PU.1和HIF-1a,以及凋亡相关蛋白p53的表达,从而减轻脑缺血后神经细胞的凋亡。

Objective To investigate the effect of mieroRNA-424 （miR-424） on neuronal apoptosis after cerebral ischemia in mice. Methods The lentiviral mediated overexpression of miR-424 （ 109 U/mL, 8 p.L） was injected into the lateral ventricle in mice for 7 d, then the middle carotid artery occlusion （MCAO） model was established, and the mice were divided into 4 groups： sham group, sham ＋ miR-424 group, MCAO model group and MCAO ＋ miR-424 group （ n = 6 ）. At 8 h after MCAO, the ischemic brain tissue was removed and paraffin sections were TUNEL-stained to observe the neuronal apoptosis, and the protein levels of transcription factor PU. 1, hypoxia inducible factor-la （ HIF-la）, apoptosis- related proteins p53 were detected by Western blot. Results The TUNEL immunofluorescence observation revealed that miR-424 reduced neuronal apoptosis at 8 h after cerebral ischemia in the mice. The Western blot showed that before ischemia and at 8 h after ischemia, miR-424 increased the levels of PU. 1, HIF-la and apoptotic protein p.53 in the normal .and MCAO model brain tissues, exhibiting the same effect on the expression of those three proteins. Conclusions miR-424 can reduce neuronal apoptosis after cerebral ischemia partly through increasing the expression of transcription factor PU. 1 and HIF-1 ct, as well as apoptosis-related proteins p53 in the brain tissue of mice.