title: Higher insulin sensitivity in EDL muscle of rats fed a low-protein, high-carbohydrate diet inhibits the caspase-3 and ubiquitin-proteasome proteolytic systems but does not increase protein synthesis.
abstract: Compared with the extensor digitorum longus (EDL) muscle of control rats (C), the EDL muscle of rats fed a low-protein, high-carbohydrate diet (LPHC) showed a 36% reduction in mass. Muscle mass is determined by the balance between protein synthesis and proteolysis; thus, the aim of this work was to evaluate the components involved in these processes. Compared with the muscle from C rats, the EDL muscle from LPHC diet-fed rats showed a reduction (34%) in the in vitro basal protein synthesis and a 22% reduction in the in vitro basal proteolysis suggesting that the reduction in the mass can be associated with a change in the rate of the two processes. Soon after euthanasia, in the EDL muscles of the rats fed the LPHC diet for 15days, the activity of caspase-3 and that of components of the ubiquitin-proteasome system (atrogin-1 content and chymotrypsin-like activity) were decreased. The phosphorylation of p70(S6K) and 4E-BP1, proteins involved in protein synthesis, was also decreased. We observed an increase in the insulin-stimulated protein content of p-Akt. Thus, the higher insulin sensitivity in the EDL muscle of LPHC rats seemed to contribute to the lower proteolysis in LPHC rats. However, even with the higher insulin sensitivity, the reduction in p-E4-BP1 and p70(S6K) indicates a reduction in protein synthesis, showing that factors other than insulin can have a greater effect on the control of protein synthesis.
authors.affiliation: Department of Chemistry, Federal University of Mato Grosso, Cuiabá, Mato Grosso, Brazil.
authors.forename: Maísa Pavani
authors.initials: MP
authors.lastname: Dos Santos
authors.affiliation: Department of Chemistry, Federal University of Mato Grosso, Cuiabá, Mato Grosso, Brazil.
authors.forename: Emanuele
authors.initials: E
authors.lastname: Batistela
authors.affiliation: Department of Chemistry, Federal University of Mato Grosso, Cuiabá, Mato Grosso, Brazil.
authors.forename: Mayara Peron
authors.initials: MP
authors.lastname: Pereira
authors.affiliation: Department of Biochemistry and Immunology, School of Medicine, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Silvia
authors.initials: S
authors.lastname: Paula-Gomes
authors.affiliation: Department of Biochemistry and Immunology, School of Medicine, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Neusa Maria
authors.initials: NM
authors.lastname: Zanon
authors.affiliation: Department of Biochemistry and Immunology, School of Medicine, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Isis do Carmo
authors.initials: Ido C
authors.lastname: Kettelhut
authors.affiliation: Faculty of Sport and Health Sciences, University of St Mark and St John, Plymouth, United Kingdom.
authors.forename: Christina
authors.initials: C
authors.lastname: Karatzaferi
authors.affiliation: Department of Chemistry, Federal University of Mato Grosso, Cuiabá, Mato Grosso, Brazil.
authors.forename: Claudia Marlise Balbinotti
authors.initials: CM
authors.lastname: Andrade
authors.affiliation: Department of Chemistry, Federal University of Mato Grosso, Cuiabá, Mato Grosso, Brazil.
authors.forename: Suélem Aparecida
authors.initials: SA
authors.lastname: de França
authors.affiliation: Department of Clinical Analysis, School of Pharmaceutical Sciences, São Paulo State University, Presidente Prudente, São Paulo, Brazil.
authors.forename: Amanda Martins
authors.initials: AM
authors.lastname: Baviera
authors.affiliation: Department of Chemistry, Federal University of Mato Grosso, Cuiabá, Mato Grosso, Brazil. Electronic address: nairhonda@terra.com.br.
authors.forename: Nair Honda
authors.initials: NH
authors.lastname: Kawashita
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism*; D000070601:Diet, Carbohydrate Loading / Q000009:adverse effects*; D018753:Diet, Protein-Restricted / Q000009:adverse effects*; D015536:Down-Regulation; D005528:Foot; D007333:Insulin Resistance; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D024510:Muscle Development; D018482:Muscle, Skeletal / Q000201:enzymology / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D014176:Protein Biosynthesis; D011499:Protein Processing, Post-Translational; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism; D059748:Proteolysis; D011897:Random Allocation; D017208:Rats, Wistar; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000235:genetics / Q000378:metabolism; D054875:Ubiquitination
chemical_list: D002352:Carrier Proteins; C499526:Eif4ebp1 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D010750:Phosphoproteins; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D017027:Protein Tyrosine Phosphatases; C505410:Casp3 protein, rat; D053148:Caspase 3; D046988:Proteasome Endopeptidase Complex
keywords: Extensor digitorum longus; Growing rats; Insulin sensitivity; Low-protein, high-carbohydrate diet; Protein synthesis; Proteolytic pathways