Nakashima Kazuki, Ishida Aiko, Shimamoto Saki, Ijiri Daichi, Ohtsuka Akira
Division of Animal Metabolism and Nutrition, Institute of Livestock and Grassland Science, NARO, Tsukuba 305-0901, Japan.
Department of Biochemical Science and Technology, Faculty of Agriculture, Kagoshima University, Kagoshima 890-0065, Japan.
J Poult Sci. 2017 Jul 25;54(3):247-252. doi: 10.2141/jpsa.0160141.
The expression of atrogin-1/MAFbx, a muscle-specific E3 ubiquitin ligase, is increased in catabolic conditions that result in muscle atrophy. The expression of atrogin-1/MAFbx mRNA is also decreased by the insulin-like growth factor-I (IGF-I) in mammalian skeletal muscle cell cultures. This study investigated the effect of IGF-I on the expression of atrogin-1/MAFbx in chicken skeletal muscle cell cultures. Chick myotubes were incubated with IGF-I for 1, 6, or 24 h. Protein content was increased by IGF-I (100 ng/m) and incubated for 24 h in chick myotubes. The expression of atrogin-1/MAFbx mRNA decreased in the presence of IGF-I (1, 10, and 100 ng/m) for 6 h in chick myotubes. The expression of the m-calpain large subunit and cathepsin B mRNA was not decreased by IGF-I. Phosphorylation of Akt and FOXO1 increased in the presence of IGF-I (100 ng/m) for 1 h in chick myotubes. These results indicate that IGF-I suppresses atrogin-1/MAFbx mRNA expression by phosphorylation of Akt and FOXO1, resulting in an increase in muscle growth in chick myotube cultures.
atrogin-1/MAFbx是一种肌肉特异性E3泛素连接酶，其表达在导致肌肉萎缩的分解代谢条件下会增加。在哺乳动物骨骼肌细胞培养物中，胰岛素样生长因子-I（IGF-I）也会降低atrogin-1/MAFbx mRNA的表达。本研究调查了IGF-I对鸡骨骼肌细胞培养物中atrogin-1/MAFbx表达的影响。将鸡肌管与IGF-I孵育1、6或24小时。IGF-I（100 ng/m）可增加鸡肌管中的蛋白质含量，并孵育24小时。在鸡肌管中，IGF-I（1、10和100 ng/m）存在6小时会使atrogin-1/MAFbx mRNA的表达降低。IGF-I不会降低m-钙蛋白酶大亚基和组织蛋白酶B mRNA的表达。在鸡肌管中，IGF-I（100 ng/m）存在1小时会使Akt和FOXO1的磷酸化增加。这些结果表明，IGF-I通过Akt和FOXO1的磷酸化抑制atrogin-1/MAFbx mRNA的表达，从而导致鸡肌管培养物中肌肉生长增加。
