title: Elevated cyclin D1 expression is governed by plasma IGF-1 through Ras/Raf/MEK/ERK pathway in rumen epithelium of goats supplying a high metabolizable energy diet.
abstract: The objective of this study was to explore the underlying mechanism of insulin-like growth factor 1 (IGF-1)-caused cell proliferation of rumen epithelium in goats fed a high metabolizable energy (ME) diet. In this study, young goats were fed either a low ME [LL, n = 9, ME: 0.57 MJ/kg(0.75) /day] or high ME [HL, n = 9, ME: 1.00 MJ/(kg(0.75) /day)] diet for 42 day. The time duration of G1 -phase was shortened as a result of enhanced expression of cyclin D1 mRNA in the HL group (p < 0.05). It was suggested that a high ME diet promoted cell transition from G0 /G1 to S-phase via cyclin D1. The level of phosphorylation of ERK was higher in HL than LL group (p < 0.05). In cell culture, the ERK was phosphorylated by IGF-1 treatment. The proliferative effects of insulin-like growth factor 1 (IGF-1, 25 ng/ml) on [(3) H] thymidine (TdR) incorporation into DNA and on cyclin D1 protein expression of rumen epithelial cells were inhibited by PPP (the inhibitor of type 1 IGF receptor) (p < 0.05) and ERK inhibitor (p < 0.05) in vitro. Thus, IGF-1 up-regulated cyclin D1 expression and accelerated G1 -phase progression in the cell cycle through Ras/Raf/MEK/ERK pathway in rumen epithelium of goats.
authors.affiliation: Lab of Animal Physiology and Biochemistry, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China; Jiangsu Animal Husbandry & Veterinary College, Nanjing, China.
authors.forename: J
authors.initials: J
authors.lastname: Lu
authors.forename: H
authors.initials: H
authors.lastname: Zhao
authors.forename: J
authors.initials: J
authors.lastname: Xu
authors.forename: L
authors.initials: L
authors.lastname: Zhang
authors.forename: L
authors.initials: L
authors.lastname: Yan
authors.forename: Z
authors.initials: Z
authors.lastname: Shen
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D004032:Diet / Q000662:veterinary; D002149:Energy Intake; D004848:Epithelium / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D006041:Goats / Q000502:physiology*; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000502:physiology; D008297:Male; D012417:Rumen / Q000378:metabolism*; D048490:raf Kinases / Q000235:genetics / Q000378:metabolism*; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D007334:Insulin-Like Growth Factor I; D048490:raf Kinases; D018631:ras Proteins
keywords: cell cycle; goat; pathway; proliferation; rumen