title: Myofibrillar proteolysis in chick myotubes during oxidative stress.
abstract: Changes in protein conformation and proteolysis in chick myotubes in response to the induction of oxidative stress by H2O2 treatment were studied. Myotubes were treated for 1 h with H2O2. After this treatment, the H2O2 was removed and the cells were cultured in serum-free medium for 6 and 24 h. Protein carbonyl content, as an index of protein modification, was increased at 6 and 24 h after H2O2 treatment. N(tau)-methylhistidine release, as an index of myofibrillar proteolysis, was also increased at 6 and 24 h after H2O2 treatment. Calpain and cathepsin (B+L and D) activities were increased at 24 but not 6 h after H2O2 treatment. Proteasome activity was increased at 6 and 24 h after H2O2 treatment. These results indicate that oxidative stress increased proteasome activity and caused an increase in myofibrillar proteolysis during short-term incubation, whereas it increased calpain, proteasome and cathepsin activities during long-term incubation, finally resulting in an increase of myofibrillar proteolysis in chick myotubes.
authors.affiliation: Nutrient Function Laboratory, Department of Animal Physiology and Nutrition, National Institute of Livestock and Grassland Science, Tsukuba, Ibaraki 305-0901, Japan. kaznaka@affrc.go.jp
authors.forename: Kazuki
authors.initials: K
authors.lastname: Nakashima
authors.forename: Itoko
authors.initials: I
authors.lastname: Nonaka
authors.forename: Shigehiko
authors.initials: S
authors.lastname: Masaki
mesh_terms: D000818:Animals; D002154:Calpain / Q000378:metabolism*; D002403:Cathepsins / Q000378:metabolism*; D002645:Chickens; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007700:Kinetics; D008762:Methylhistidines / Q000378:metabolism; D009097:Multienzyme Complexes / Q000378:metabolism*; D018485:Muscle Fibers, Skeletal / Q000187:drug effects / Q000201:enzymology*; D009210:Myofibrils / Q000378:metabolism*; D018384:Oxidative Stress; D046988:Proteasome Endopeptidase Complex; D017392:Thiobarbituric Acid Reactive Substances / Q000032:analysis
chemical_list: D008762:Methylhistidines; D009097:Multienzyme Complexes; D017392:Thiobarbituric Acid Reactive Substances; D006861:Hydrogen Peroxide; D002403:Cathepsins; D002154:Calpain; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex