Nakashima Kazuki, Ishida Aiko
Division of Animal Metabolism and Nutrition, Institute of Livestock and Grassland Science, NARO, Tsukuba 305-0901, Japan.
J Poult Sci. 2018;55(4):257-262. doi: 10.2141/jpsa.0170196. Epub 2018 Mar 25.
Autophagy, an intracellular bulk protein degradation system in skeletal muscle, is increased under catabolic conditions resulting in muscle atrophy. This study aimed to investigate the effects of insulin, insulin-like growth factor (IGF)-I, and amino acids on autophagy (LC3-II content and expression of autophagy-related genes) in chick myotubes. Chick myotubes were incubated with insulin (1 g/m), IGF-I (100 ng/m), and amino acids for 3 h. The LC3-II content, an index of autophagosome formation, and mRNA expression of LC3B and GABARAPL1 were significantly decreased by insulin. The LC3-II content, but not mRNA expression of autophagy-related genes, was also significantly decreased by IGF-I. The LC3-II content and LC3B mRNA level were also significantly decreased by amino acids. The mRNA expression of atrogin-1/MAFbx, a muscle-specific ubiquitin ligase, was also significantly decreased by insulin, IGF-I, and amino acids in chick myotubes. These results indicated that insulin, IGF-I, and amino acids regulate autophagy as well as the ubiquitin-proteasome proteolytic pathway in chick myotubes.
自噬是骨骼肌中的一种细胞内大量蛋白质降解系统，在分解代谢条件下会增强，导致肌肉萎缩。本研究旨在探讨胰岛素、胰岛素样生长因子（IGF）-I和氨基酸对鸡肌管自噬（LC3-II含量及自噬相关基因表达）的影响。将鸡肌管用胰岛素（1 μg/ml）、IGF-I（100 ng/ml）和氨基酸孵育3小时。胰岛素显著降低了自噬体形成指标LC3-II的含量以及LC3B和GABARAPL1的mRNA表达。IGF-I也显著降低了LC3-II的含量，但未降低自噬相关基因的mRNA表达。氨基酸同样显著降低了LC3-II的含量和LC3B的mRNA水平。鸡肌管中的肌肉特异性泛素连接酶atrogin-1/MAFbx的mRNA表达也因胰岛素、IGF-I和氨基酸而显著降低。这些结果表明，胰岛素、IGF-I和氨基酸在鸡肌管中既调节自噬，也调节泛素-蛋白酶体蛋白水解途径。
