Received 2002-03-20 Accepted 2002-08-13
This work was supported by the National
Natural Science Foundation of China
(No.39600171, 39730190)
*Corresponding author. Tel:
+86-023-68752340-8205; E-mail: liuliu@mail.tmmu.com.cn
ATP浓度和缺氧暴露对大鼠脑线粒体RNA和蛋白质体外合成的影响
柳君泽*, 高文祥, 蔡明春, 曹利飞, 孙秉庸
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,
全军高原生理与高原病重点实验室, 重庆 400038
摘要: 本文探讨介质中ATP浓度和急、慢性缺氧暴露对大鼠脑线粒体内RNA和蛋白质合成的影响。用差速离心法分离正常和低压舱模拟4000 m高原急性连续缺氧暴露3 d和慢性连续缺氧暴露40 d大鼠脑线粒体, 用体外无细胞(cell-free in vitro) 3H-UTP和3H-Leucine掺入法分别测定线粒体RNA和蛋白质合成活性。结果显示, 大鼠急性缺氧暴露后大脑皮质线粒体RNA体外合成活性降低40%, 蛋白质合成活性降低60%; 慢性缺氧暴露后线粒体RNA和蛋白质合成活性分别为对照的72%和76%; ATP对正常大鼠脑线粒体RNA以及蛋白质的体外合成活性的影响均呈双相性, 大于或小于1 mmol/L均可产生不同程度的抑制效应。结果提示, 缺氧可在转录和翻译两个水平上影响脑线粒体mtDNA的表达, 而慢性缺氧暴露时, 线粒体半自主性功能的改善可能是机体对缺氧适应的细胞机制之一; ATP对脑线粒体内转录和翻译活性的调节是一种经济有效的反馈调节方式。
关键词: 线粒体; 缺氧; ATP; 线粒体RNA合成; 线粒体蛋白质合成
学科分类号: R364.4;
R329.24
Effects of ATP concentration and hypoxia
exposure on RNA and protein synthesis activity in isolated mitochondria from
rat brain
Liu
Jun-Ze*, Gao Wen-Xiang, Cai Ming-Chun, Cao Li-Fei, Sun Bing-Yong
Department
of Pathophysiology,
Abstract: To explore the effects of ATP
concentration in the medium and hypoxia exposure on mitochondrial DNA
expression at transcriptionl and translationl level, rats were exposed to hypobaric
chamber simulating 4000 m above sea level for 3 days (acute hypoxia) or 40 days
(chronic hypoxia). Cerebral cortex mitochondria were isolated from control and
hypoxia exposure rats by centrifugation program. The activities of
intramitochondrial RNA and protein synthesis were measured respectively by the
methods of incorporation of 3H-UTP or 3H-Leucine in a cell-free system in vitro
in isolated organelle. The effect of different ATP concentration in medium on
incorporation activity of mitochondria from control rat brains was observed.
The results showed that there was a 40% reduction in RNA synthesis and a 60%
inhibition in protein synthesis in isolated mitochondria in vitro in acute
hypoxia exposure compared to control. But in chronic hypoxia exposure, the
inhibitions of RNA synthesis and protein synthesis were both alleviated, being
72% and 76% of the normoxic control, respectively. Furthermore, the effect of
ATP concentration in medium on mitochondrial RNA and protein synthesis in vitro
showed two phases. The mitochondrial RNA and protein synthesis were inhibited
when ATP concentration was either above or below 1 mmol/L in the incubation
medium. These results indicate that hypoxia exposure affects the expression of
mtDNA on both transcription and translation levels. It also suggests that the
improvement of mitochondrial semi-automation during chronic hypoxia exposure be
perhaps at least one of the cellular mechanisms of body adaptation to hypoxia.
The regulation of ATP in mitochondrial RNA and protein synthesis is therefore
an economic and effective mode of regulation.
Key words: mitochondria; hypoxia; ATP;
mitochondrial RNA synthesis; mitochondrial protein synthesis