低氧训练中过表达血红素加氧酶1促进小鼠骨骼肌线粒体的生物合成

Overexpression of heme oxygenase-1 promotes biosynthesis of skeletal muscle mitochondria during hypoxia training in mice

背景:近年对低氧训练机制的研究主要围绕低氧训练对机体血液系统的调节作用展开,但结果具有两面性,提示还有非血液系统调节机制。目的:探讨血红素加氧酶1在低氧训练中对小鼠骨骼肌线粒体含量及生物合成的调节作用。方法:SPF级8周龄雄性过表达血红素加氧酶1转基因小鼠20只,野生型小鼠20只,由兰州大学医学院提供。2种小鼠分别被随机分为2组(共4组):野生小鼠低氧静息组、野生小鼠低氧训练组、转基因小鼠低氧静息组和转基因小鼠低氧训练组。低氧训练组小鼠在青海大学基础医学研究中心进行跑台运动(速度20 m/min,坡度5°,60 min/d,5 d/周,共4周)。各组小鼠均于末次训练结束3 d后行速度20 m/min,坡度5°持续跑台运动并记录各组小鼠力竭运动时间,电镜检测骨骼肌线粒体数量,JC-1荧光探针检测线粒体膜电位,萤光素酶发光法检测线粒体ATP合成活性,Western blot检测骨骼肌血红素加氧酶1、COX Ⅳ和PGC-1α蛋白表达量。结果与结论:①与野生小鼠低氧静息组相比,野生小鼠低氧训练组和转基因小鼠低氧训练组力竭运动时间增加,线粒体数目略有增多,线粒体膜电位和ATP合成增加,血红素加氧酶1、COX Ⅳ和PGC-1α蛋白表达量增加;②与野生小鼠低氧训练组相比,转基因小鼠低氧训练组力竭运动时间明显增加,线粒体数目显著增多,线粒体膜电位和ATP合成增加,COX Ⅳ和PGC-1α蛋白表达量显著增加;③结果说明,血红素加氧酶1在低氧训练中具有延长小鼠力竭运动时间的作用,其机制可能与增加骨骼肌线粒体数量和生物合成有关。

BACKGROUND: Studies on hypoxic training concentrate on the regulatory role of hypoxic training in blood system, but the results have dual characteristics, revealing its regulatory role in non-blood system. OBJECTIVE: To investigate the regulation of heme oxygenase-1 in mitochondria and biosynthesis in mouse skeletal muscle during hypoxic training. METHODS: Twenty male 8-week-old overexpression heme oxygenase-1 transgenic mice and 20 wild-type mice, SPF grade were provided by School of Medicine of Lanzhou University. The two species were randomly divided into four groups: wild-type mice hypoxia control, wild-type mice hypoxia training, transgenic mice control and transgenic mice hypoxia training groups. The mice in the hypoxia training groups underwent treadmill running(20 m/min, slope 5°, 60 min/d, 5 d/week, for 4 weeks) at Basic Medical Research Center of Qinghai University. The treadmill running was undergone in each group at 3 days after final training, and the exhaustive exercise time was recorded. The number of mitochondria in skeletal muscle was detected by electron microscope. Mitochondrial membrane potential was determined using JC-1 fluorescent probe. ATP synthesis capacity was determined using a bioluminescence technique. The protein expression of heme oxygenase-1, cytochrome C oxidase Ⅳ and peroxisome proliferator-activated receptor gamma cofactor 1 alpha was detected by western blot assay. RESULTS AND CONCLUSION:(1) Compared with the wild-type mice hypoxia control group, the exhausted exercise time extended in the wild-type mice hypoxia training and transgenic mice hypoxia training groups, the number of mitochondria was slightly increased, the membrane potential and ATP synthesis capacity were elevated, and protein expression levels of heme oxygenase-1, cytochrome C oxidase Ⅳ and peroxisome proliferator-activated receptor gamma cofactor 1 alpha were significantly increased.(2) Compared with the wild-type mice hypoxia training group, the exhausted exercise time in the transgenic mice hypoxia training group was significantly increased, the number of mitochondria was significantly increased, the membrane potential and ATP synthesis capacity were significantly elevated, and protein expression levels of heme oxygenase-1, cytochrome C oxidase Ⅳ and peroxisome proliferator-activated receptor gamma cofactor 1 alpha were significantly increased.(3) These results indicate that heme oxygenase-1 has the effect of prolonging exhaustion time in hypoxic training. The mechanism may be related to the promotion of mitochondrial number and biosynthesis.