Nakashima Kazuki, Ishida Aiko
Institute of Livestock and Grassland Science, NARO, Tsukuba 305-0901, Japan.
J Poult Sci. 2023 Aug 11;60:2023022. doi: 10.2141/jpsa.2023022. eCollection 2023.
Abstracts: Skeletal muscles have a high demand for ATP, which is met largely through mitochondria oxidative phosphorylation. Autophagy is essential for the maintenance of skeletal muscle mass under catabolic conditions. This study investigated the effect of uncoupling mitochondrial oxidative phosphorylation on autophagy in chicken skeletal muscle. Chick myotubes were incubated with the mitochondrial uncoupler carbonyl cyanide m-chlorophenyl hydrazone (CCCP) at 25 μM for 3h. CCCP prevented the phosphorylation of p70 ribosomal S6 kinase 1 (Thr389), S6 ribosomal protein (Ser240/244), and eukaryotic translation initiation factor 4E-binding protein 1 (Thr37/46), which are the measures of the mechanistic target of rapamycin complex 1 (mTORC1) activity. CCCP significantly increased cytoplasmic and mitochondrial LC3-II content, which act as indices of index for autophagosome formation and mitophagy, respectively, but did not influence the expression of autophagy-related genes LC3B, GABARAPL1, and ATG12. Finally, surface sensing of translation method revealed that protein synthesis, a highly energy consuming process, was significantly decreased upon CCCP treatment. These results indicate that the uncoupling of mitochondrial oxidative phosphorylation stimulates autophagy and inhibits protein synthesis through mTORC1 signaling in chick myotube cultures.
骨骼肌对三磷酸腺苷（ATP）的需求量很高，这主要通过线粒体氧化磷酸化来满足。自噬对于在分解代谢条件下维持骨骼肌质量至关重要。本研究调查了线粒体氧化磷酸化解偶联对鸡骨骼肌自噬的影响。将鸡肌管与25μM的线粒体解偶联剂羰基氰化物间氯苯腙（CCCP）孵育3小时。CCCP抑制了p70核糖体S6激酶1（Thr389）、S6核糖体蛋白（Ser240/244）和真核翻译起始因子4E结合蛋白1（Thr37/46）的磷酸化，这些是雷帕霉素复合物1（mTORC1）活性的机制靶点的测量指标。CCCP显著增加了细胞质和线粒体中LC3-II的含量，它们分别作为自噬体形成和线粒体自噬的指标，但不影响自噬相关基因LC3B、GABARAPL1和ATG12的表达。最后，翻译表面传感方法显示蛋白质合成是一个高耗能过程，在CCCP处理后显著降低。这些结果表明，线粒体氧化磷酸化解偶联通过mTORC1信号通路刺激鸡肌管培养物中的自噬并抑制蛋白质合成。
