title: Effect of recombinant porcine IGF-binding protein-3 on proliferation of embryonic porcine myogenic cell cultures in the presence and absence of IGF-I.
abstract: IGF-binding protein (IGFBP)-3 is produced by cultured porcine embryonic myogenic cell (PEMC) cultures and is secreted into the medium. Levels of secreted IGFBP-3 and IGFBP-3 mRNA are significantly reduced during differentiation and increase after differentiation is complete, suggesting that IGFBP-3 may play some role in myogenesis and/or in changes in myogenic cell proliferation that accompany differentiation. IGFBP-3 reportedly may either suppress or stimulate proliferation of cultured cells depending on cell type. Additionally, IGFBP-3 has been shown to affect proliferation via both IGF-dependent and IGF-independent mechanisms in some cell types but not all. Currently, the effect, if any, of IGFBP-3 on myogenic cell proliferation is not known. Consequently, the goal of this study was to assess the IGF-I-dependent and IGF-I-independent actions of recombinant porcine IGFBP-3 on proliferation of cultured porcine myogenic cells. To facilitate these investigations, we have expressed porcine IGFBP-3 in the baculovirus system, purified and characterized the expressed recombinant porcine IGFBP-3 (rpIGFBP-3), and produced and characterized an anti-porcine IGFBP-3 antibody that neutralizes the biological activity of porcine IGFBP-3. rpIGFBP-3 suppressed IGF-I-stimulated proliferation of PEMCs in a concentration-dependent manner with equimolar concentrations of IGF-I and rpIGFBP-3, resulting in complete suppression of IGF-I-stimulated proliferation. rpIGFBP-3 also suppressed Long-R3-IGF-I-stimulated proliferation of PEMC, indicating that rpIGFBP-3 possesses IGF-independent activity in this cell system. These data have established that IGFBP-3 has the potential to affect proliferation of PEMCs during critical periods of muscle development that may impact ultimate muscle mass achievable postnatally.
authors.affiliation: Animal Growth and Development Laboratory, Department of Animal Science, University of Minnesota, 348 ABLMS, 1354 Eckles Avenue, St Paul, Minnesota 55108, USA.
authors.forename: M S
authors.initials: MS
authors.lastname: Pampusch
authors.forename: E
authors.initials: E
authors.lastname: Kamanga-Sollo
authors.forename: M E
authors.initials: ME
authors.lastname: White
authors.forename: M R
authors.initials: MR
authors.lastname: Hathaway
authors.forename: W R
authors.initials: WR
authors.lastname: Dayton
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D016367:Baculoviridae; D019149:Bioreactors; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003864:Depression, Chemical; D007074:Immunoglobulin G / Q000494:pharmacology; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000276:immunology / Q000302:isolation & purification / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D018485:Muscle Fibers, Skeletal / Q000166:cytology; D032446:Myoblasts / Q000166:cytology* / Q000187:drug effects; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000494:pharmacology; D013552:Swine
chemical_list: D000911:Antibodies, Monoclonal; D007074:Immunoglobulin G; D018972:Insulin-Like Growth Factor Binding Protein 3; D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I