Transforming growth factor-beta1 modulates insulin-like growth factor binding protein-4 expression and proteolysis in cultured periosteal explants

Growth Horm IGF Res. 2010 Apr;20(2):81-6. doi: 10.1016/j.ghir.2009.06.002. Epub 2009 Aug 4.

Abstract

Objective: Periosteum is involved in bone growth and fracture healing and has been used as a cell source and tissue graft for tissue engineering and orthopedic reconstruction including joint resurfacing. Periosteum can be induced by transforming growth factor beta (TGF-beta) or insulin-like growth factor-I (IGF-I) alone or in combination to form cartilage. However, little is known about the interaction between IGF and TGF-beta signaling during periosteal chondrogenesis. The purpose of this study was to determine the effect of TGF-beta1 on IGF binding protein-4 (IGFBP-4) and the IGFBP-4 protease pregnancy-associated plasma protein-A (PAPP-A) expression in cultured periosteal explants.

Design: Periosteal explants from rabbits were cultured with or without TGF-beta1. IGFBP-4 and PAPP-A mRNA levels were determined by real-time quantitative PCR. Conditioned medium was analyzed for IGFBP-4 and PAPP-A protein levels and IGFBP-4 protease activity.

Results: TGF-beta1-treated explants contained lower IGFBP-4 mRNA levels throughout the culture period with a maximum reduction of 70% on day 5 of culture. Lower levels of IGFBP-4 protein were also detected in the conditioned medium from TGF-beta1-treated explants. PAPP-A mRNA levels were increased 1.6-fold, PAPP-A protein levels were increased threefold, and IGFBP-4 protease activity was increased 8.5-fold between 7 and 10days of culture (the onset of cartilage formation in this model) in conditioned medium from TGF-beta1-treated explants.

Conclusions: This study demonstrates that TGF-beta1 modulates the expression of IGFBP-4 and PAPP-A in cultured periosteal explants.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • Gene Expression Regulation / drug effects
  • Insulin-Like Growth Factor Binding Protein 4 / genetics*
  • Insulin-Like Growth Factor Binding Protein 4 / metabolism*
  • Organ Culture Techniques
  • Periosteum / drug effects*
  • Periosteum / metabolism*
  • Pregnancy-Associated Plasma Protein-A / genetics
  • Pregnancy-Associated Plasma Protein-A / metabolism
  • Protein Processing, Post-Translational / drug effects
  • RNA, Messenger / analysis
  • RNA, Messenger / metabolism
  • Rabbits
  • Time Factors
  • Transforming Growth Factor beta1 / pharmacology*
  • Transforming Growth Factor beta1 / physiology

Substances

  • Insulin-Like Growth Factor Binding Protein 4
  • RNA, Messenger
  • Transforming Growth Factor beta1
  • Pregnancy-Associated Plasma Protein-A