Changes in rat liver mitochondria with aging -: Lon protease-like activity and Nε-carboxymethyllysine accumulation in the matrix
Changes in rat liver mitochondria with aging -: Lon protease-like activity and Nε-carboxymethyllysine accumulation in the matrix
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DOI：
10.1046/j.1432-1033.2003.03598.x
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发表时间：
2003-05-01
期刊：
影响因子：
--
通讯作者：
Friguet, B
中科院分区：
文献类型：
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作者：
Bakala, H;Delaval, E;Friguet, B
衰老伴随着细胞功能的逐渐恶化。线粒体功能障碍和蛋白质损伤的积累被认为是导致这一过程的原因。本研究旨在探讨衰老对大鼠肝脏线粒体基质的影响。检测参与异常基质蛋白降解的Lon蛋白水解酶的活性，并用免疫化学方法监测氧化和糖氧化(N(Epsilon)-羧甲基赖氨酸，CML)产物的积累。通过测定呼吸链活性来评价线粒体的功能。老年(27个月)大鼠的线粒体表现出与成年(10个月)大鼠相同的耗氧率，而偶联效率没有任何变化。与此同时，ATP刺激的Lon蛋白酶活性(荧光肽释放)从10月龄大鼠(1.15+/-0.15FU.mug蛋白(-1).h(-1))显著下降到27月龄大鼠(0.59+/-0.08FU.mug蛋白(-1).h(-1))。在活性下降的同时，随着年龄的增长，氧化蛋白在基质中积累，而用ELISA法评估的CML修饰蛋白含量从10个月(11.71+/-0.61pmolCML.mug蛋白(-1))到27个月(17.81+/-1.83pmolCML.mug蛋白(-1))显著增加了52%。这些结果表明，有害的氧化和羧甲基化蛋白在基质中的积累伴随着Lon蛋白酶活性的丧失，可能影响衰老线粒体对额外压力的反应能力。
Aging is accompanied by a gradual deterioration of cell functions. Mitochondrial dysfunction and accumulation of protein damage have been proposed to contribute to this process. The present study was carried out to examine the effects of aging in mitochondrial matrix isolated from rat liver. The activity of Lon protease, an enzyme implicated in the degradation of abnormal matrix proteins, was measured and the accumulation of oxidation and glycoxidation (N (epsilon) -carboxymethyllysine, CML) products was monitored using immunochemical assays. The function of isolated mitochondria was assessed by measuring respiratory chain activity. Mitochondria from aged (27 months) rats exhibited the same rate of oxygen consumption as those from adult (10 months) rats without any change in coupling efficiency. At the same time, the ATP-stimulated Lon protease activity, measured as fluorescent peptides released, markedly decreased from 10-month-old rats (1.15 +/- 0.15 FU.mug protein(-1) .h(-1) ) to 27-month-old-rats (0.59 +/- 0.08 FU.mug protein(-1) .h(-1) ). In parallel with this decrease in activity, oxidized proteins accumulated in the matrix upon aging while the CML-modified protein content assessed by ELISA significantly increased by 52% from 10 months (11.71 +/- 0.61 pmol CML.mug protein(-1) ) to 27 months (17.81 +/- 1.83 pmol CML.mug protein(-1) ). These results indicate that the accumulation of deleterious oxidized and carboxymethylated proteins in the matrix concomitant with loss of the Lon protease activity may affect the ability of aging mitochondria to respond to additional stress.