title: Role of insulin-like growth factor binding protein (IGFBP)-3 in TGF-beta- and GDF-8 (myostatin)-induced suppression of proliferation in porcine embryonic myogenic cell cultures.
abstract: Both transforming growth factor (TGF-beta) and growth and development factor (GDF)-8 (myostatin) affect muscle differentiation by suppressing proliferation and differentiation of myogenic cells. In contrast, insulin-like growth factors (IGFs) stimulate both proliferation and differentiation of myogenic cells. In vivo, IGFs are found in association with a family of high-affinity insulin-like growth factor binding proteins (IGFBP 1-6) that affect their biological activity. Treatment of porcine embryonic myogenic cell (PEMC) cultures with either TGF-beta(1) or GDF-8 suppressed proliferation and increased production of IGFBP-3 protein and mRNA (P < 0.005). An anti-IGFBP-3 antibody that neutralizes the biological activity of IGFBP-3 reduced the ability of either TGF-beta(1) or GDF-8 to suppress PEMC proliferation (P < 0.005). However, this antibody did not affect proliferation rate in the presence of both TGF-beta(1) and GDF-8. These data show that IGFBP-3 plays a role in mediating the activity of either TGF-beta(1) or GDF-8 alone but not when both TGF-beta(1) and GDF-8 are present. In contrast to findings in T47D breast cancer cells, treatment of PEMC cultures with IGFBP-3 did not result in increased levels of phosphosmad-2. Since TGF-beta and GDF-8 are believed to play a significant role in regulating proliferation and differentiation of myogenic cells, our current data showing that IGFBP-3 plays a role in mediating the activity of these growth factors in muscle cell cultures strongly suggest that IGFBP-3 also may be involved in regulating these processes in myogenic cells.
mesh_terms: D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000187:drug effects / Q000378:metabolism; D025461:Feedback, Physiological / Q000187:drug effects / Q000502:physiology; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism*; D032446:Myoblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D055435:Myostatin; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D051899:Smad2 Protein; D034421:Sus scrofa; D015534:Trans-Activators / Q000187:drug effects / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism* / Q000494:pharmacology; D053773:Transforming Growth Factor beta1
chemical_list: D000906:Antibodies; D004268:DNA-Binding Proteins; D018972:Insulin-Like Growth Factor Binding Protein 3; D055435:Myostatin; D012333:RNA, Messenger; D051899:Smad2 Protein; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1