Holwerda Andrew M, Dirks Marlou L, Barbeau Pierre-Andre, Goessens Joy, Gijsen Annemie, van Loon Luc J C, Holloway Graham P
NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands.
Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Canada.
J Cachexia Sarcopenia Muscle. 2024 Oct;15(5):1811-1822. doi: 10.1002/jcsm.13532. Epub 2024 Jul 15.
Mitochondria represent key organelles influencing cellular homeostasis and have been implicated in the signalling events regulating protein synthesis.
We examined whether mitochondrial bioenergetics (oxidative phosphorylation and reactive oxygen species (HO) emission, ROS) measured in vitro in permeabilized muscle fibres represent regulatory factors for integrated daily muscle protein synthesis rates and skeletal muscle mass changes across the spectrum of physical activity, including free-living and bed-rest conditions: n = 19 healthy, young men (26 ± 4 years, 23.4 ± 3.3 kg/m) and following 12 weeks of resistance-type exercise training: n = 10 healthy older men (70 ± 3 years, 25.2 ± 2.1 kg/m). Additionally, we evaluated the direct relationship between attenuated mitochondrial ROS emission and integrated daily myofibrillar and sarcoplasmic protein synthesis rates in genetically modified mice (mitochondrial-targeted catalase, MCAT).
Neither oxidative phosphorylation nor HO emission were associated with muscle protein synthesis rates in healthy young men under free-living conditions or following 1 week of bed rest (both P > 0.05). Greater increases in GSSG concentration were associated with greater skeletal muscle mass loss following bed rest (r = -0.49, P < 0.05). In older men, only submaximal mitochondrial oxidative phosphorylation (corrected for mitochondrial content) was positively associated with myofibrillar protein synthesis rates during exercise training (r = 0.72, P < 0.05). However, changes in oxidative phosphorylation and HO emission were not associated with changes in skeletal muscle mass following training (both P > 0.05). Additionally, MCAT mice displayed no differences in myofibrillar (2.62 ± 0.22 vs. 2.75 ± 0.15%/day) and sarcoplasmic (3.68 ± 0.35 vs. 3.54 ± 0.35%/day) protein synthesis rates when compared with wild-type mice (both P > 0.05).
Mitochondrial oxidative phosphorylation and reactive oxygen emission do not seem to represent key factors regulating muscle protein synthesis or muscle mass regulation across the spectrum of physical activity.
线粒体是影响细胞稳态的关键细胞器，且与调节蛋白质合成的信号事件有关。
我们研究了在通透化肌纤维中体外测量的线粒体生物能量学（氧化磷酸化和活性氧（ROS）释放）是否代表日常肌肉蛋白质合成率和骨骼肌质量在包括自由生活和卧床休息等各种身体活动条件下变化的调节因素：19名健康年轻男性（26±4岁，体重指数23.4±3.3kg/m²）以及经过12周抗阻训练后的10名健康老年男性（70±3岁，体重指数25.2±2.1kg/m²）。此外，我们评估了转基因小鼠（线粒体靶向过氧化氢酶，MCAT）中线粒体ROS释放减弱与每日肌原纤维和肌浆蛋白合成率之间的直接关系。
在自由生活条件下或卧床休息1周后的健康年轻男性中，氧化磷酸化和ROS释放均与肌肉蛋白质合成率无关（P均>0.05）。卧床休息后，谷胱甘肽二硫化物（GSSG）浓度的更大升高与更大的骨骼肌质量损失相关（r = -0.49，P <0.05）。在老年男性中，仅次最大线粒体氧化磷酸化（校正线粒体含量后）与运动训练期间的肌原纤维蛋白合成率呈正相关（r = 0.72，P <0.05）。然而，氧化磷酸化和ROS释放的变化与训练后骨骼肌质量的变化无关（P均>0.05）。此外，与野生型小鼠相比，MCAT小鼠的肌原纤维（2.62±0.22 vs. 2.75±0.15%/天）和肌浆（3.68±0.35 vs. 3.54±0.35%/天）蛋白合成率无差异（P均>0.05）。
线粒体氧化磷酸化和活性氧释放似乎不是调节各种身体活动条件下肌肉蛋白质合成或肌肉质量调节的关键因素。
