title: Feeding status regulates the polyubiquitination step of the ubiquitin-proteasome-dependent proteolysis in rainbow trout (Oncorhynchus mykiss) muscle.
abstract: In mammals, the ubiquitin-proteasome proteolytic pathway is a major route of protein degradation and has been shown to be regulated by the feeding status via the protein kinase B (PKB)-Forkehead box-O transcription factor signaling pathway-mediated transcription regulation of atrophy-related ubiquitin ligases, atrogin1 and muscle RING finger 1. In contrast, in rainbow trout (Oncorhynchus mykiss), the activity of the proteasome in muscle was not affected during starvation-induced muscle degradation. The aim of this study was therefore to explore the molecular basis for this lack of induction of this proteolytic route during starvation. In this study, rainbow trout were food deprived for 7 and 14 d, refed ad libitum, and the effect of the nutritional status was assessed on the different steps involved in the regulation of the ubiquitin-proteasome system in muscle. We observed that starvation reduced the phosphorylation of PKB and enhanced the expression of atrogin1 in muscle, whereas refeeding led to the opposite effects. The level of polyubiquitinated proteins in muscle increased to over 2 times the initial value on d 0 after 14 d of starvation and decreased significantly at 12 h after refeeding, but there were no major changes in the activity of the main proteasomal peptidases (chymotrypsin-like and trypsin-like). Altogether, these results indicate that in rainbow trout muscle, the polyubiquitination step of the ubiquitin-proteasome route is regulated by the feeding status similarly to what is observed in mammals.
authors.affiliation: INRA, UMR1067 Nutrition Aquaculture et Génomique, F-64310 Saint-Pée-sur-Nivelle, France. seiliez@st-pee.inra.fr
authors.forename: Iban
authors.initials: I
authors.lastname: Seiliez
authors.forename: Stéphane
authors.initials: S
authors.lastname: Panserat
authors.forename: Sandrine
authors.initials: S
authors.lastname: Skiba-Cassy
authors.forename: Aurélie
authors.initials: A
authors.lastname: Fricot
authors.forename: Christiane
authors.initials: C
authors.lastname: Vachot
authors.forename: Sadasivam
authors.initials: S
authors.lastname: Kaushik
authors.forename: Sophie
authors.initials: S
authors.lastname: Tesseraud
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D004032:Diet / Q000662:veterinary; D005508:Food Deprivation / Q000502:physiology*; D005786:Gene Expression Regulation; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism*; D017686:Oncorhynchus mykiss / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D044843:SKP Cullin F-Box Protein Ligases / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D025801:Ubiquitin / Q000378:metabolism*
chemical_list: D009124:Muscle Proteins; D011506:Proteins; D025801:Ubiquitin; D044843:SKP Cullin F-Box Protein Ligases; D051057:Proto-Oncogene Proteins c-akt; D046988:Proteasome Endopeptidase Complex