title: Effects of level of nutrient intake and age on mammalian target of rapamycin, insulin, and insulin-like growth factor-1 gene network expression in skeletal muscle of young Holstein calves.
abstract: The molecular mechanisms by which level of nutrient intake enhances skeletal muscle growth in young ruminants are not fully understood. We examined mammalian target of rapamycin (mTOR), insulin, and insulin-like growth factor-1 (IGF-1) gene network expression in semitendinosus muscle tissue of young male Holstein calves fed a conventional milk replacer plus conventional starter (CON) or an enhanced milk replacer plus high-protein starter (ENH) for 5 wk followed by a conventional starter or a high-protein starter until 10 wk of age. Feeding ENH led to greater concentration of plasma IGF-1 and leptin and greater carcass protein and fat mass throughout the study. Despite the greater plasma IGF-1 and protein mass at wk 5, calves fed ENH had lower expression of IGF1R, INSR, and RPS6KB1 but greater expression of IRS1 and PDPK1 in muscle tissue. Except for IGF1R expression, which did not differ at wk 10, these differences persisted at wk 10, suggesting a long-term effect of greater nutrient intake on physiological and molecular mechanisms. Components of mTOR complex (mTORC)1 and mTORC2 (RICTOR and RPTOR) and FOXO1 expression decreased by wk 10 regardless of diet. Overall, the present data revealed that greater nutrient intake throughout the milk-fed and early postweaning phase alters body mass composition partly by altering hormonal and molecular profiles of genes associated with glucose and amino acid signaling. Those networks may play a crucial role in coordinating neonatal muscle growth and metabolism in response to level of nutrient intake.
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China; Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana 61801.
authors.forename: P
authors.initials: P
authors.lastname: Wang
authors.affiliation: Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana 61801.
authors.forename: J K
authors.initials: JK
authors.lastname: Drackley
authors.affiliation: Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana 61801.
authors.forename: J A
authors.initials: JA
authors.lastname: Stamey-Lanier
authors.affiliation: Department of Animal Sciences, University of Missouri, Columbia 65211.
authors.forename: D
authors.initials: D
authors.lastname: Keisler
authors.affiliation: Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana 61801. Electronic address: jloor@illinois.edu.
authors.forename: J J
authors.initials: JJ
authors.lastname: Loor
mesh_terms: D000367:Age Factors; D000821:Animal Feed / Q000032:analysis; D000818:Animals; D002417:Cattle; D004032:Diet / Q000662:veterinary; D004044:Dietary Proteins / Q000008:administration & dosage; D002149:Energy Intake; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D053263:Gene Regulatory Networks; D005819:Genetic Markers; D013006:Growth Hormone / Q000097:blood; D007328:Insulin / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D011972:Receptor, Insulin / Q000235:genetics / Q000378:metabolism; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D020123:Sirolimus / Q000494:pharmacology*; D013002:Somatomedins; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D000077004:Tuberous Sclerosis Complex 1 Protein; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D004044:Dietary Proteins; D051858:Forkhead Transcription Factors; D005819:Genetic Markers; D007328:Insulin; D013002:Somatomedins; D000077004:Tuberous Sclerosis Complex 1 Protein; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D011972:Receptor, Insulin; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D058570:TOR Serine-Threonine Kinases; C448901:ribosomal protein S6 kinase, 70kD, polypeptide 1; D020123:Sirolimus
keywords: dairy calf; growth; metabolism; protein synthesis