过表达Bax抑制子1(BI-1)通过内质网IRE1-JNK通路抑制蛛网膜下腔出血大鼠海马神经元凋亡

Over-expressed Bax inhibitor 1 (BI-1) inhibits apoptosis of hippocampal neurons via endoplasmic reticulum IRE1-JNK pathway in rats with subarachnoid hemorrhage

目的探讨慢病毒介导Bax抑制子1(BI-1)过表达对蛛网膜下腔出血(SAH)大鼠海马神经元保护作用以及与内质网膜蛋白肌醇酶1-c-Jun氨基末端激酶(IRE1-JNK)信号通路的关系。方法制备BI-1过表达慢病毒并经侧脑注射,24 h后采用血管内穿刺法建立SAH大鼠模型。于造模后24 h,对大鼠进行神经行为学评估和脑含水量检测,原位末端转移酶标记技术(TUNEL)观察大鼠海马神经元凋亡情况,Western blot法检测BI-1蛋白以及内质网应激标志蛋白葡萄糖调节蛋白78(GRP78)和IRE1蛋白水平。采用IRE1α特异性抑制剂KIRA6处理SAH后大鼠,Western blot法检测BI-1过表达对IRE1-JNK信号通路相关蛋白磷酸化的IRE1(p-IRE1)、磷酸化的JNK(p-JNK)及凋亡相关蛋白Bax、Bcl2和caspase-3蛋白水平的影响。结果过表达BI-1提高SAH模型大鼠的神经行为学评估得分,降低SAH模型大鼠的脑含水量和海马神经元凋亡率,并且BI-1过表达可以下调SAH后大鼠海马神经元中GRP78和IRE1蛋白水平。KIRA6处理和BI-1过表达均可抑制p-IRE1、p-JNK、Bax的表达和caspase-3的活化,促进Bcl2的表达。结论过表达BI-1可通过阻断IRE1-JNK通路抑制SAH后大鼠海马神经元凋亡。

Objective To investigate the protective effect of lentivirus-mediated BI-1 overexpression on hippocampal neurons in rats with subarachnoid hemorrhage（ SAH） and the relationship with endoplasmic reticulum IRE1-JNK signaling pathway.Methods The lentivirus solution of BI-1 over-expression was injected into the brain of rats 24 hours before SAH rat model was established by intravascular puncture method. At 24 hours after modeling,the brain water content and neurological score of the rats were measured. The apoptosis of hippocampal neurons was detected by TUNEL assay. Western blotting was used to detect the expressions of BI-1 protein and endoplasmic reticulum stress（ ERS） marker proteins GRP78 and IRE1.ERS in hippocampal neurons of the rats with SAH was intervened by IRE1α-specific inhibitor KIRA6,and then the protein expressions of p-IRE1,p-JNK,Bax,Bcl2 and caspase-3 were detected by Western blotting. Results BI-1 over-expression improved neurobehavioral score,decreased brain water content and hippocampal neuron apoptosis rate,and also down-regulated GRP78 and IRE1 protein levels in the rats with SAH. Both the interference of KIRA6 and the over-expression of BI-1 inhibited the expressions of p-IRE1, p-JNK, Bax and caspase-3, and promoted the expression of anti-apoptotic protein Bcl2.Conclusion Over-expression of BI-1 can inhibit the apoptosis of hippocampal neurons in rats with SAH by inhibiting the activation of ERS-mediated IRE1-JNK signaling pathway,thus ultimately attenuating the early brain injury fol owing SAH.