反式转录激活因子-X连锁凋亡抵制蛋白融合蛋白对阿尔茨海默病模型大鼠Caspase-3表达与活性的抑制

摘要

Objective:To observe the expression and activity of Caspase-3 in the brain tissues from the Alzheimer's disease (AD) rat model induced by Aβ25-35 (amyloid beta,Aβ) injection into the brain in vivo,the effects of intervention with TATXIAP fusion protein on the Caspase-3 expression and activation in the AD rat model.Methods:SD rats were enrolled in the study and were equally and randomly divided into three groups:a saline control group,an AD model group and a treatment group.The AD model was induced by injection of Aβ25-35 into the bilateral hippocampus.After 6-week amyloid-β25-35 injection,the rats were injected with TAT-XIAP fusion protein twice a week for consecutive 4 weeks by intravenous injection.The rats were sacrificed 4 weeks after being treated with TAT-XIAP.The change of Caspase-3 expression and activity in the cerebral cortex and hippocampus was assayed by immunohistochemistry and RT-PCR.Results:In the AD model group,the level of caspase-3 mRNA was obviously increased in the cerebral cortex and hippocampus,was respectively 2.03 times and 1.72 times of that in the control group.Active Caspase-3 was located in the nucleus.The levels of active caspase-3 of the cerebral cortex and hippocampus in the AD model were increased,and were respectively 1.62 and 1.64 times of that in the control group.After the treatment with TAT-XIAP,the expressions and activity of Caspase-3 were decreased.Compared with the AD model,the expression levels of Caspase-3 of the cerebral cortex and hippocampus in the treatment group were decreased by 9 ％ and 44 ％ respectively; and the activity of Caspase-3 was decreased by 36 ％ and 28 ％.Conclusion:The results of the experiment indicate that Aβ25-35 could increase Caspase-3 mRNA expressions and activate Caspase-3; TAT-XIAP fusion protein could inhibit the expression and activation of Caspase-3 in AD model.%目的:探讨β-淀粉样蛋白25-35(Aβ25-35)海马内注射所致的阿尔茨海默病(AD)模型大鼠脑内Caspase-3表达与活性变化及反式转录激活因子-X连锁凋亡抵制蛋白(TAT-XIAP)融合蛋白的干预作用.方法:SD大鼠随机分为盐水对照组、AD模型组及治疗组,采用双侧海马内注射Aβ25-35建立AD模型,造模后6周尾静脉注射TAT-XIAP融合蛋白,连续给药4周后处死动物,通过RT-PCR和免疫组织化学研究AD大鼠大脑皮质与海马Caspase-3 mRNA表达及蛋白的活性变化,TATXIAP融合蛋白对上述作用的干预.结果:AD模型组大鼠大脑皮质与海马Caspase-3 mRNA表达上调,模型组大脑皮质和海马Caspase-3表达分别是对照组的2.03倍和1.72倍；活化的Caspase-3位于细胞核,AD模型组大鼠大脑皮质与海马Caspase-3蛋白活性增强,模型组大脑皮质和海马Caspase-3活性分别是对照组的1.62倍和1.64倍.应用TAT-XIAP融合蛋白后,大鼠皮质与海马Caspase-3表达与活性均降低；治疗组与模型组比较大脑皮质和海马Caspase-3表达分别下降了9％和44％,Caspase-3活性分别下降了36％和28％.结论:本实验结果表明Aβ25-35可上调Caspase-3 mRNA表达,活化Caspase-3；TAT-XIAP融合蛋白可抑制AD模型大鼠Caspase-3 mRNA的表达和活性.