Cultured Porcine Myogenic Cells Produce Insulin-Like Growth Factor Binding Protein-3 (IGFBP-3) and Transforming Growth Factor Beta-1 Stimulates IGFBP-3 Production

Joan R. Hembree, Mary S. Pampusch, Fan Yang, Jennifer L. Causey, Marcia R. Hathaway, William R. Dayton

Research output: Contribution to journalArticlepeer-review

32 Scopus citations

Abstract

Insulin-like growth factor binding proteins (IGFBP) may act locally as autocrine or paracrine regulators of insulin-like growth factor activity in specific tissues such as muscle. Although secretion of IGFBP by cultured myogenic cell lines has been examined, little is known about secretion of IGFBP by primary myogenic cell cultures. This may be because primary myogenic cultures contain non-muscle cells (fibroblasts) that complicate interpretation of IGFBP determinations. We have circumvented this problem by subculturing nonfusing cells from extensively fused porcine myogenic cultures and comparing the IGFBP production of these nonfusing, porcine muscle-derived cells with that of primary porcine myogenic cell cultures. Immunoprecipitation with specific antibodies and 125I-IGF-I ligand blot analysis showed that myogenic cultures secreted IGFBP-3 (doublet band, 43 kDa and 39 kDa), IGFBP-2 (34 kDa), IGFBP-4 (30 and 24 kDa), and IGFBP-5 (30 and 28 kDa). Muscle-derived fibroblasts secreted no detectable IGFBP-3 but approximately 10 times more IGFBP-2 than did myogenic cell cultures. Treatment of myogenic cultures for 24 h with transforming growth factor (TGF) beta-1 caused a concentration-dependent increase in IGFBP-3 secretion with a maximum 1.5-fold increase occurring at .5 ng of TGF beta-1/mL. In contrast, TGF beta-1 treatment did not stimulate detectable IGFBP-3 secretion by muscle-derived fibroblast cultures. Northern analysis of total RNA using a porcine IGFBP-3 probe revealed that TGF beta-1 treatment resulted in a fourfold increase in the steady-state level of IGFBP-3 mRNA in myogenic cultures. Insulin-like growth factor binding protein-3 mRNA was not detectable in fibroblast cultures either before or after TGF beta-1 treatment. This is the first report of IGFBP-3 secretion by cultured myogenic cells.

Original languageEnglish (US)
Pages (from-to)1530-1540
Number of pages11
JournalJournal of animal science
Volume74
Issue number7
DOIs
StatePublished - Jul 1996

Keywords

  • Insulin-Like Growth Factor Binding Proteins
  • Muscles
  • Pigs
  • Transforming Growth Factor

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