Effect of dexamethasone on the expression of atrogin-1/MAFbx in chick skeletal muscle.
Expression of atrogin-1/MAFbx, a muscle-specific E3 ubiquitin ligase, is high under catabolic conditions, that result in muscle atrophy. Messenger RNA (mRNA) expression of atrogin-1/MAFbx is increased by the glucocorticoid dexamethasone in mammalian skeletal muscle. This study investigated the effects of dexamethasone on expression of atrogin-1/MAFbx in skeletal muscle of neonatal chicks and in chick myotubes. Chicks were given a single intraperitoneal injection of dexamethasone at a concentration of 10 mg/kg body weight. Twenty-four hours after dexamethasone administration, the Pectoralis muscle weight of chicks was decreased. mRNA expression of atrogin-1/MAFbx in skeletal muscle of chicks was significantly increased by dexamethasone administration. Expression of other proteolytic-related genes (20S proteasome C2 subunit, m-calpain large subunit, and cathepsin B) in skeletal muscle of chicks was not increased by dexamethasone administration. Chick myotubes were incubated with dexamethasone (1, 10 or 100 µmol/L) for 6 h. Expression of atrogin-1/MAFbx mRNA in chick myotubes was increased in the presence of all concentrations of dexamethasone. However, expression of other proteolytic-related genes (20S proteasome C2 subunit, m-calpain large subunit and cathepsin B) in chick myotubes was not affected by dexamethasone treatment. These results indicate that dexamethasone enhances atrogin-1/MAFbx expression in chick skeletal muscle, resulting in increased muscle atrophy.
Animal Physiology and Nutrition Division, NARO Institute of Livestock and Grassland Science, Tsukuba, Japan.
Kazuki
K
Nakashima
Animal Physiology and Nutrition Division, NARO Institute of Livestock and Grassland Science, Tsukuba, Japan.
Aiko
A
Ishida
Department of Biochemical Science and Technology, Faculty of Agriculture, Kagoshima University, Kagoshima, Japan.
Daichi
D
Ijiri
Department of Biochemical Science and Technology, Faculty of Agriculture, Kagoshima University, Kagoshima, Japan.
Akira
A
Ohtsuka
D000818:Animals; D001284:Atrophy; D002645:Chickens / Q000235:genetics* / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D009124:Muscle Proteins / Q000235:genetics* / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology; D009929:Organ Size / Q000187:drug effects / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism*; D044843:SKP Cullin F-Box Protein Ligases / Q000235:genetics* / Q000378:metabolism*
D009124:Muscle Proteins; D012333:RNA, Messenger; D003907:Dexamethasone; C440907:FBXO32 protein, human; D044843:SKP Cullin F-Box Protein Ligases
atrogin-1/MAFbx; chick myotubes; dexamethasone; proteolytic-related genes; skeletal muscle