title: Time-course changes in muscle protein degradation in heat-stressed chickens: Possible involvement of corticosterone and mitochondrial reactive oxygen species generation in induction of the ubiquitin-proteasome system.
abstract: Heat stress (HS) induces muscle protein degradation as well as production of mitochondrial reactive oxygen species (ROS). In the present study, to improve our understanding of how protein degradation is induced by HS treatment in birds, a time course analysis of changes in the circulating levels of glucocorticoid and N(τ)-methylhistidine, muscle proteolysis-related gene expression, and mitochondrial ROS generation, was conducted. At 25 days of age, chickens were exposed to HS conditions (33 °C) for 0, 0.5, 1 or 3 days. While no alteration in plasma N(τ)-methylhistidine concentration relative to that of the control group was observed in the 0.5 day HS group, the concentration was significantly higher in the 3-d HS treatment group. Plasma corticosterone concentrations increased in response to 0.5-d HS treatment, but subsequently returned to near-normal values. HS treatment for 0.5 days did not change the levels of μ-calpain, cathepsin B, or proteasome C2 subunit mRNA, but increased the levels of mRNA encoding atrogin-1 (P<0.05) and its transcription factor, forkhead box O3 (P=0.09). Under these hyperthermic conditions, mitochondrial superoxide production was significantly increased than that of thermoneutral control. Here, we show that HS-induced muscle protein degradation may be due to the activation of ubiquitination by atrogin-1, and that this process may involve mitochondrial ROS production as well as corticosterone secretion.
authors.affiliation: Animal Nutrition, Life Sciences, Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Miyagi, Sendai 981-8555, Japan.
authors.forename: Kyohei
authors.initials: K
authors.lastname: Furukawa
authors.affiliation: Animal Nutrition, Life Sciences, Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Miyagi, Sendai 981-8555, Japan. Electronic address: kmotoi@bios.tohoku.ac.jp.
authors.forename: Motoi
authors.initials: M
authors.lastname: Kikusato
authors.affiliation: Animal Nutrition, Life Sciences, Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Miyagi, Sendai 981-8555, Japan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Kamizono
authors.affiliation: Animal Nutrition, Life Sciences, Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Miyagi, Sendai 981-8555, Japan.
authors.forename: Masaaki
authors.initials: M
authors.lastname: Toyomizu
mesh_terms: D000818:Animals; D002154:Calpain / Q000235:genetics / Q000378:metabolism; D002645:Chickens / Q000378:metabolism; D003345:Corticosterone / Q000097:blood*; D018882:Heat Stress Disorders; D006358:Hot Temperature; D008297:Male; D008762:Methylhistidines / Q000097:blood; D008928:Mitochondria / Q000378:metabolism* / Q000473:pathology; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D059748:Proteolysis; D012333:RNA, Messenger / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D025801:Ubiquitin / Q000378:metabolism*
chemical_list: D008762:Methylhistidines; D009124:Muscle Proteins; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D025801:Ubiquitin; D002154:Calpain; C449002:mu-calpain; D046988:Proteasome Endopeptidase Complex; C028118:3-methylhistidine; D003345:Corticosterone
keywords: Atrogin-1; FoxO; N(τ)-methylhistidine; Oxidative stress; Superoxide