Received 2002-01-28 Accepted 2002-09-28
This work was supported by the National Natural Science
Foundation of
in Tenth-five-year Program of the Chinese People's Liberation Army (No.01MB109)
缺氧对大鼠大脑皮质细胞色素氧化酶亚基Ⅰ、Ⅳ表达协同性的影响
谭小玲, 柳君泽, 曹利飞, 邓忠才, 李英和
第三军医大学高原军事医学系病理生理学与高原生理学教研室, 全军高原生理和高原病研究重点实验室, 重庆 400038
摘要: 本文探讨缺氧对细胞色素氧化酶(cytochrome oxidase, COX, 即complex Ⅳ)的mtDNA和nDNA编码亚基Ⅰ、 Ⅳ表达及其协同性的影响。实验用成年雄性Wistar大鼠随机分为对照组、 缺氧2、 5、 15和30 d组。缺氧大鼠于低压舱内模拟海拔5000 m连续减压。对照组大鼠于舱外同时喂养(舱外海拔高度为300 m)。用半定量逆转录-PCR法测定大脑皮质COXⅠ、 Ⅳ mRNA量, 用Western blot分析大脑皮质线粒体COXI、 Ⅳ蛋白量, 以两个亚基的蛋白量、 mRNA量的比值反映亚基表达的协同性。结果显示, 缺氧2、 5 d, COXⅠ mRNA增加, 缺氧15、 30 d时下降至对照水平。缺氧2、 5和15 d时, COX Ⅳ mRNA显著增加, 缺氧30 d时降低, 与对照组差异非常显著。COXⅣ、 Ⅰ mRNA比值在缺氧15 d时最高, 其它各缺氧组与对照组的差异无显著意义。各组COXⅠ、 Ⅳ蛋白量及其比值均无显著差异。上述结果表明, 缺氧可影响COXⅠ、 Ⅳ mRNA的表达及其协同性, 但对蛋白的表达及其协同性没有显著影响, 提示转录后调节是缺氧过程中线粒体内COXⅠ、 Ⅳ蛋白表达协同的主要机制。
关键词: 细胞色素氧化酶; 基因表达; 大脑皮质; 大鼠; 缺氧
中图分类号: Q426
Effects of hypoxic exposure
on coordinative expression of cytochrome oxidase subunitsⅠand
Ⅳ
in
rat cerebral cortex
TAN Xiao-Ling, LIU Jun-Ze, CAO Li-Fei, DENG Zhong-Cai, LI Ying-He
Department
of Pathophysiology,
University,
Abstract: This study was intended to evaluate the effects of hypoxic exposure on gene expression and coordination of cytochrome oxidase (COX) subunitsⅠ (COX Ⅰ) and Ⅳ (COX Ⅳ) encoded by mtDNA and nDNA respectively in rat cerebral cortex. Male Wistar rats were exposed to hypobaric chamber simulated high altitude at 5000 m for 2 (2 d), 5 (5 d), 15 (15 d) and 30 days (30 d). Control rats were fed outside the hypobaric chamber (the height was 300 m above sea level). Rats were sacrificed and mitochondria from cerebral cortex were isolated by differential centrifugation at each time point. COXⅠand COX Ⅳ proteins in isolated rat cerebral cortex mitochondria were detected by Western blot analysis and mRNA in the cerebral cortex by RT-PCR. The ratios of protein and mRNA were used to estimate the coordinative expression of two subunits. The results showed that COXⅠ mRNA increased significantly at 2 and 5 d, and decreased to the control level at 15 and 30 d; COXⅣ mRNA remarkably increased at 2, 5 and 15 d, and dropped to below the control level at 30 d; The mRNA ratio of COX Ⅳ to COX I reached a peak at 15 d, but showed no differences between other time points. The Western blot analysis of COX Ⅰand COX Ⅳ in isolated rat cerebral cortex mitochondria showed no obvious changes during hypoxic exposure. Our findings demonstrate that hypoxia can affect mRNA expression of COX Ⅰand COX Ⅳ and their coordination, while protein expression of both subunits are stable and coordinative. This study suggests that the expression of COX Ⅰand COX Ⅳ proteins during hypoxic exposure is coordinately regulated by post-transcriptional mechanisms.
Key words: cyochrome c oxidase; gene expressiom; cerebral cortex; rat; hypoxia