The effect of glypican-1 glycosaminoglycan chains on turkey myogenic satellite cell proliferation, differentiation, and fibroblast growth factor 2 responsiveness.
The glypicans are a family of cell-surface heparan sulfate proteoglycans consisting of a core protein covalently attached with glycosaminoglycans (GAG). Only glypican-1 is expressed in skeletal muscle and increases in expression during myoblast differentiation. Previous studies have suggested that glypican-1 influences fibroblast growth factor 2 (FGF2) signaling pathway by its heparan sulfate chains. Fibroblast growth factor 2 is a potent stimulator of muscle cell proliferation and an intense inhibitor of differentiation. To investigate the functional contribution of each GAG chain attachment site, a turkey glypican-1 full length cDNA (1,650 bp, Gen-Bank accession number AY551002) was cloned into the pCMS-EGFP vector and mutated at 2 or all 3 potential GAG attachment sites at Ser(483), Ser(485), and Ser(487) to obtain 1-chain and no-chain mutants, respectively. The unmutated glypican-1, 1-chain, and no-chain mutants, and the pCMS-EGFP vector without an insert were transfected into turkey myogenic satellite cells. The transfected cell cultures were assayed for cell proliferation, differentiation, and FGF2 responsiveness. The overexpression of glypican-1 increased FGF2 responsiveness during proliferation compared with the 1-chain, no-chain mutants, and the pCMS-EGFP vector without an insert, but there was no significant interaction between FGF2 and glypican-1. The overexpression of glypican-1 also increased differentiation but did not affect proliferation when compared with the 1-chain, no-chain mutants, and the pCMS-EGFP vector without an insert. To support the overexpression data, glypican-1 expression was reduced using a small interfering RNA against turkey glypican-1. Inhibition of glypican-1 expression decreased myogenic satellite cell proliferation, differentiation, and FGF2 responsiveness during proliferation. These data indicate that glypican-1 function requires the GAG chain attachment sites for myogenic satellite cell FGF2 responsiveness during proliferation and to affect the process of differentiation.
Zhang
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X
Department of Animal Sciences, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster Ohio 44691, USA.
Liu
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C
Nestor
K E
KE
McFarland
D C
DC
Velleman
S G
SG
D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D049109:Cell Proliferation; D002478:Cells, Cultured; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D053673:Glypicans / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008297:Male; D016297:Mutagenesis, Site-Directed; D034622:RNA Interference; D032496:Satellite Cells, Skeletal Muscle / Q000187:drug effects* / Q000378:metabolism*; D014422:Turkeys / Q000378:metabolism*
D053673:Glypicans; D016222:Fibroblast Growth Factor 2