Effect of glypican-1 covalently attached chains on turkey myogenic satellite cell proliferation, differentiation, and...

Glypican-1 is a cell membrane heparan sulfate proteoglycan that is composed of a core protein and covalently attached glycosaminoglycan (GAG) chains and N-linked glycosylated (N-glycosylated) chains. The glypican-1 GAG chains are required for cell differentiation and responsiveness to fibroblast growth factor 2 (FGF2). The role of glypican-1 N-glycosylated chains in regulating cell activities has not been reported. The objective of the current study was to investigate the role of glypican-1 N-glycosylated chains and the interaction between N-glycosylated and GAG chains in turkey myogenic satellite cell proliferation, differentiation, and FGF2 responsiveness. The wild-type turkey glypican-1 and turkey glypican-1 with mutated GAG chain attachment sites were cloned into the pCMS-EGFP mammalian expression vector and were used as templates to generate glypican-1 N-glycosylated 1-chain and no-chain mutants with or without GAG chains by site-directed mutagenesis. The wild-type glypican-1 and all glypican-1 N-glycosylated 1-chain and no-chain mutants with or without GAG chains were transfected into turkey myogenic satellite cells. Cell proliferation, differentiation, and FGF2 responsiveness were measured. The overexpression of glypican-1 N-glycosylated 1-chain and no-chain mutants without GAG chains increased cell proliferation and differentiation compared with the wild-type glypican-1 but not the glypican-1 N-glycosylated mutants with GAG chains attached. Cells overexpressing glypican-1 N-glycosylated mutants with or without GAG chains increased cell responsiveness to FGF2 compared with wild-type glypican-1. These data suggest that glypican-1 N-glycosylated chains and GAG chains are critical in regulating turkey myogenic satellite cell proliferation, differentiation, and responsivness to FGF2.