title: Prevention of IGF-1 and TGFbeta stimulated type II collagen and decorin expression by bFGF and identification of IGF-1 mRNA transcripts in articular chondrocytes.
abstract: OBJECTIVE
  the aim of this investigation was to establish whether the action of bFGF modulated the production of type II collagen, decorin and biglycan induced by IGF-1 or TGFbeta in porcine articular chondrocytes. In addition, the study would establish which multiple transcripts of IGF-1 were present in articular cartilage, and which growth factors influenced their expression.
  
  
  METHODS
  steady state levels of mRNA specific for IGF-1 and matrix proteins were extracted as total RNA from porcine articular chondrocytes and processed for Northern blot analysis. High-density cell monolayers were established in the presence of serum, then maintained in a serum-free state for up to 7 days with increasing doses of either IGF-1 or TGFbeta in the presence or absence of bFGF.
  
  
  RESULTS
  bFGF prevented the stimulation of type II collagen and decorin induced in the presence of IGF-1 or TGFbeta and up-regulated the production of biglycan in cultured chondrocytes without altering the gene expression of IGF-1. Four IGF-1 transcripts were found in cultured adherent chondrocytes, approximately 77% was present as a major 4.7kb transcript with lower levels of 7.6 (4%), 1.3 (11%) and 1.1 (8%) kb forms.
  
  
  CONCLUSIONS
  bFGF acts as an antagonist for the production of type II collagen and decorin and also acts as a strong inducer like IGF 1 and TGFbeta for the expression of biglycan in porcine cultured chondrocytes. The apparent lack of a dose and time effect on expression of the IGF-1 gene was surprising and may be due to the stability of the IGF-1 message.
authors.affiliation: Department of Matrix Biochemistry, Strangeways Research Laboratory, CB1, 8RN, Cambridge, UK. sonal@desai-abram.org
authors.forename: D
authors.initials: D
authors.lastname: Sonal
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000166:cytology / Q000378:metabolism; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D003094:Collagen / Q000235:genetics*; D058575:Decorin; D004305:Dose-Response Relationship, Drug; D016326:Extracellular Matrix Proteins; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects*; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000494:pharmacology*; D011509:Proteoglycans / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis*; D013552:Swine; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
chemical_list: D058575:Decorin; D016326:Extracellular Matrix Proteins; D011509:Proteoglycans; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D016222:Fibroblast Growth Factor 2; D007334:Insulin-Like Growth Factor I; D003094:Collagen