核酸内切酶G在帕金森病大鼠脑组织中的表达及意义

Expression and Significance of Endonuclease-G in Brain Tissue of Rats with Parkinson's Disease

目的:探讨核酸内切酶G(Endo-G)介导的非Caspase依赖性细胞凋亡在帕金森病(PD)发生发展中的作用和分子机制。方法:30只SPF级雄性SD大鼠均分为PD模型组(PD组)和对照组(Ctrl组),PD组大鼠右侧纹状体注射6-羟多巴胺(6-OHDA)诱导建立单侧损毁的PD大鼠模型,Ctrl组大鼠注射生理盐水;采用免疫组化实验观察大鼠黑质内酪氨酸羟化酶(TH)的变化以及核酸内切酶G(Endo-G)在黑质中的分布,计算Endo-G核转移细胞率;采用蛋白印迹实验(Western Bolt)检测Endo-G在黑质线粒体和细胞核中的表达量。结果:Ctrl组TH染色阳性神经元结构完整,PD模型组大鼠损毁侧黑质部位TH染色阳性细胞很难见完整的神经元结构;与Ctrl组比较,PD大鼠模型组损毁侧(右侧)黑质线粒体中Endo-G表达量明显降低(P<0.05),而细胞核中Endo-G表达量明显升高(P<0.05);Ctrl组大鼠Endo-G核转移细胞率低于PD组(P<0.05)。结论:在6-OHDA诱导的PD大鼠模型中,Endo-G自线粒体转位至细胞核,提示非Caspase依赖性细胞凋亡通路可能介导PD大鼠黑质多巴胺能神经元的变形和丢失。

Objective:To explore the role and molecular mechanism of caspase-independent apoptosis mediated by endonuclease G(Endo-G)in the development of Parkinson's disease(PD).Methods:Thirty male SPF SD rats were divided into PD model group(PD group)and control group(Ctrl group).The rats in PD group were injected with 6-hydroxydopamine(6-OHDA)into the right striatum to establish PD model,while rats in the Ctrl group were injected with saline.Immunohistochemical(IHC)staining was used to observe the changes of tyrosine hydroxylase(TH)and Endo-G distribution in the substantia nigra.The transfer rate of Endo-G into nuclei was calculated in the substantia nigra.Western blot was used to detect the expression of Endo-G in mitochondria and nuclei in the substantia nigra.Results:The TH-positive neurons had complete neuronal structures in the Ctrl group,while the TH-positive neurons barely had complete neuronal structure in the substantia nigra of the PD model group.When compared with the Ctrl group,mitochondrial Endo-G expression was significantly reduced in PD group(P<0.05),while Endo-G expression was significantly increased in the nuclei(P<0.05);the transfer rate of Endo-G into nuclei was lower in Ctrl group than in PD group(P<0.05).Conclusion:In 6-OHDA-induced PD model,the translocation of Endo-G from mitochondria to the nuclei suggests that the Caspase-independent apoptosis pathway may mediate the deformation and loss of dopaminergic neurons in substantia nigra.