氯霉素处理对大鼠脑皮质细胞色素氧化酶亚基表达协调性的影响

Effect of CAP-administration on subunits expression of cytochrome oxidase in mitochondria from brain cortex of rats and its mechanism

目的 通过应用线粒体蛋白合成特异抑制剂氯霉素(CAP)处理后 ,观察大鼠脑皮质线粒体COX亚基Ⅰ和Ⅳ以及线粒体转录因子 (mtTFA)、核呼吸因子 1(NRF 1)等相关转录调控因子的基因表达改变 ,以了解在特异性阻断线粒体蛋白翻译后细胞核与线粒体基因组在转录与翻译水平上的变化 ,探讨mtDNA与nDNA组之间的相互关系。方法 成年♂Wistar系大鼠分为对照组和药物处理组 ,药物处理连续7d腹腔注射 0 5 %CAP ,10 0mg·kg-1,1次 / 12h。RT PCR分析脑组织COXI、COXIV、NRF 1及mtTFAmRNA水平 ,Westernblot分析脑组织线粒体COXI、COXIV及组织NRF 1蛋白。结果 CAP组脑线粒体COX亚基Ⅰ蛋白含量降低(P <0 0 5 ) ,COXⅣ /COXⅠ比值增高 ,COXImRNA水平以及COXIVmRNA与蛋白水平均无改变 (P >0 0 5 )。同时 ,mtTFA的mRNA以及NRF 1的mRNA及蛋白含量与对照组比较均无差异。结论 线粒体内COXⅠ蛋白水平的变化对mtDNA的转录不存在反馈调节机制 ,而且线粒体基因组对细胞核基因组也没有可观察到的反馈效应。

Aim To understand the changing aspects of CAP-administration on expression of cytochrome C oxidase(COX) subunits I and IV and their mechanisms regulated by gene expression encoded by mtDNA and nDNA. Methods Wistar rats were randomly divided into control and CAP groups, Rats were administrated CAP(100 mg·kg -1, intraperitoneal injection) every 12 hours for 7 days before sacrificed by decapitation. Rat brain was removed and the cerebral cortex mitochondria was isolated by centrifugation programme. The protein content of COX subunitⅠand Ⅳ in mitochondria and NRF-1 in cerebral tissues was detected by Western blot analysis. And mRNA state levels of COXⅠ, COXⅣ, mtTFA and NRF-1 in tissues were determined by RT-PCR.Results Compared with C group, a decreased protein content of COX subunitⅠand an elevated ratio of subunit Ⅳ/Ⅰwas observed in CAP group, The protein content of COX subunit Ⅳ and NRF-1 as well as COXⅠ,Ⅳ,NRF-1 and mtTFA mRNA state level was not unchanged between the two groups. Conclusion The change of content of COX subunitⅠprotein in mitochondria from cerebral cortex showed there is no regulation of feedback to mitochondrial and nuclear transcription. The nuclear genomes expression does not correspond to mitochondrial expression in CAP-administrated rats.