title: Undernutrition regulates the expression of a novel splice variant of myostatin and insulin-like growth factor 1 in ovine skeletal muscle.
abstract: Undernutrition suppresses the growth of skeletal muscles and alters the expression of insulin-like growth factor 1 (IGF1), a key mitogen, and myostatin, a potent inhibitor of myogenesis. These changes can explain, at least in part, the reduced growth of skeletal muscles in underfed lambs. We have recently identified a myostatin splice variant (MSV) that binds to and antagonizes the canonical signaling of myostatin. In the present study, we hypothesized that the expression of MSV would be reduced in conjunction with myostatin and IGF1 in response to underfeeding in skeletal muscles of sheep. Young growing ewes were fed either ad libitum or an energy-restricted diet (30% of maintenance requirements) for 28 d. This regime of underfeeding resulted in a 24% reduction in body mass (P < 0.001) and a 36% reduction in the mass of the semitendinosus muscles relative to controls (P < 0.001) by day 28. The concentrations of MSV and IGF1 messenger RNA (mRNA) were reduced (both P < 0.001), but myostatin mRNA was not altered in semitendinosus muscles. Unlike the reduced expression of mRNA, the abundance of MSV protein was increased (P < 0.05) and there was no change in the abundance of myostatin protein. Our results suggest that undernutrition for 28 d decreases the signaling of myostatin by increasing the abundance of MSV protein. Although this action may reduce the growth inhibitory activity of myostatin, it cannot prevent the loss of growth of skeletal muscles during undernutrition.
authors.affiliation: AgResearch Ltd, Ruakura Research Centre, Hamilton 3240, New Zealand. Electronic address: frank.jeanplong@gmail.com.
authors.forename: F
authors.initials: F
authors.lastname: Jeanplong
authors.affiliation: AgResearch Ltd, Ruakura Research Centre, Hamilton 3240, New Zealand; Department of Sport and Exercise Science, University of Auckland, Auckland, New Zealand.
authors.forename: C C
authors.initials: CC
authors.lastname: Osepchook
authors.affiliation: AgResearch Ltd, Ruakura Research Centre, Hamilton 3240, New Zealand.
authors.forename: S J
authors.initials: SJ
authors.lastname: Falconer
authors.affiliation: Department of Sport and Exercise Science, University of Auckland, Auckland, New Zealand.
authors.forename: H K
authors.initials: HK
authors.lastname: Smith
authors.affiliation: AgResearch Ltd, Ruakura Research Centre, Hamilton 3240, New Zealand; Liggins Institute, University of Auckland, Auckland, New Zealand.
authors.forename: J J
authors.initials: JJ
authors.lastname: Bass
authors.affiliation: AgResearch Ltd, Ruakura Research Centre, Hamilton 3240, New Zealand.
authors.forename: C D
authors.initials: CD
authors.lastname: McMahon
authors.affiliation: AgResearch Ltd, Ruakura Research Centre, Hamilton 3240, New Zealand.
authors.forename: J M
authors.initials: JM
authors.lastname: Oldham
mesh_terms: D000818:Animals; D005260:Female; D005508:Food Deprivation; D005786:Gene Expression Regulation / Q000502:physiology; D007334:Insulin-Like Growth Factor I / Q000032:analysis / Q000235:genetics*; D044342:Malnutrition / Q000662:veterinary*; D018482:Muscle, Skeletal / Q000737:chemistry / Q000378:metabolism*; D055435:Myostatin / Q000032:analysis / Q000235:genetics*; D020033:Protein Isoforms / Q000032:analysis / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D012756:Sheep / Q000378:metabolism; D012757:Sheep Diseases / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D055435:Myostatin; D020033:Protein Isoforms; D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I
keywords: IGF1; MSV; Myostatin; Nutrition; Sheep; Skeletal muscle