title: Effect of quality and quantity of dietary protein on 4E-BP1 and S6K1 phosphorylation of brains in aged rats.
abstract: We have shown that the rate of brain protein synthesis in aged rats depended on the quality and quantity of dietary protein consumed. The purpose of this study was to determine whether the quality and quantity of dietary protein affected the phosphorylation of eukaryotic initiation factor (eIF) 4E-binding protein 1 (4E-BP1) and ribosomal protein S6 kinase (S6K1) and regulated the brain protein synthesis. Two experiments were done on three groups of 24-wk-old male rats given diets containing 20% casein, 20% gluten, or 20% gelatin (Experiment 1), and 20% casein, 5% casein or 0% casein (Experiment 2) for 10 d. The phosphorylation of S6K1 in both the cerebral cortex and cerebellum, and the phosphorylation of 4E-BP1 in the cerebral cortex declined with a decrease of quality and quantity of dietary protein. The phosphorylation of 4E-BP1 in the cerebellum did not differ among groups. The results suggest that the ingestion of a higher quality and quantity of dietary protein stimulates the phosphorylation of 4E-BP1 and S6K1 in the brain and increases the brain protein synthesis in the aged rats.
authors.affiliation: Laboratory of Nutritional Biochemistry, School of Food and Nutritional Sciences, COE Program in the 21st Century, The University of Shizuoka, Suruga, Japan.
authors.forename: Miho
authors.initials: M
authors.lastname: Ohsumi
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Yoshizawa
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Hayase
authors.forename: Hidehiko
authors.initials: H
authors.lastname: Yokogoshi
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D004044:Dietary Proteins / Q000008:administration & dosage*; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D010770:Phosphotransferases / Q000378:metabolism*; D014176:Protein Biosynthesis; D051381:Rats; D017208:Rats, Wistar; D019893:Ribosomal Protein S6 Kinases / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D004044:Dietary Proteins; C499526:Eif4ebp1 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D010750:Phosphoproteins; D010770:Phosphotransferases; D019893:Ribosomal Protein S6 Kinases; C526901:Rps6kb1 protein, rat