Insulin-like growth factor binding protein (IGFBP)-3 and IGFBP-5 mediate TGF-beta- and myostatin-induced suppression of proliferation in porcine embryonic myogenic cell cultures

Exp Cell Res. 2005 Nov 15;311(1):167-76. doi: 10.1016/j.yexcr.2005.09.003. Epub 2005 Oct 6.


We have previously shown that cultured porcine embryonic myogenic cells (PEMC) produce both insulin-like growth factor binding protein (IGFBP)-3 and IGFBP-5 and secrete these proteins into their media. Exogenously added recombinant porcine (rp) IGFBP-3 and rpIGFBP-5 act via IGF-dependent and IGF-independent mechanisms to suppress proliferation of PEMC cultures. Furthermore, immunoneutralization of endogenous IGFBP-3 and IGFBP-5 in the PEMC culture medium results in increased DNA synthesis rate suggesting that endogenous IGFBP-3 and IGFBP-5 suppress PEMC proliferation. TGF-beta superfamily members myostatin and TGF-beta1 have also been shown to suppress proliferation of myogenic cells, and treatment of cultured PEMC with either TGF-beta1 or myostatin significantly (P < 0.01) increases levels of IGFBP-3 and -5 mRNA. We have previously shown that immunoneutralization of IGFBP-3 decreases the proliferation-suppressing activity of TGF-beta1 and myostatin. Here, we show that immunoneutralization of IGFBP-5 also significantly (P < 0.05) decreases the DNA synthesis-suppressing activity of these molecules. Simultaneous immunoneutralization of both IGFBP-3 and IGFBP-5 in TGF-beta1 or myostatin-treated PEMC cultures restores Long-R3-IGF-I-stimulated DNA synthesis rates to 90% of the levels observed in control cultures receiving no TGF-beta1 or myostatin treatment (P < 0.05). Even though immunoneutralization of IGFBP-3 and -5 increased DNA synthesis rates in TGF-beta1 or myostatin-treated PEMC cultures, phosphosmad2 levels in these cultures were not affected. These findings strongly suggest that IGFBP-3 and IGFBP-5 affect processes downstream from receptor-mediated Smad phosphorylation that facilitate the ability of TGF-beta and myostatin to suppress proliferation of PEMC.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Antibodies, Monoclonal / pharmacology
  • Cell Proliferation / drug effects
  • Cells, Cultured
  • DNA / metabolism
  • Fetus
  • Humans
  • Insulin-Like Growth Factor Binding Protein 3 / physiology*
  • Insulin-Like Growth Factor Binding Protein 5 / physiology*
  • Myoblasts / cytology*
  • Myoblasts / drug effects
  • Myoblasts / metabolism*
  • Myostatin
  • Phosphorylation
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Smad2 Protein / metabolism
  • Swine
  • Transforming Growth Factor beta / pharmacology*
  • Transforming Growth Factor beta1


  • Antibodies, Monoclonal
  • Insulin-Like Growth Factor Binding Protein 3
  • Insulin-Like Growth Factor Binding Protein 5
  • MSTN protein, human
  • Myostatin
  • RNA, Messenger
  • Smad2 Protein
  • TGFB1 protein, human
  • Transforming Growth Factor beta
  • Transforming Growth Factor beta1
  • DNA