RGD-CAP ((beta)ig-h3) enhances the spreading of chondrocytes and fibroblasts via integrin alpha(1)beta(1)

Biochim Biophys Acta. 1999 Aug 12;1451(1):196-205. doi: 10.1016/s0167-4889(99)00093-2.


In previous studies, RGD-CAP (collagen-associated protein containing the RGD sequence) isolated from a collagen fiber-rich fraction of pig cartilage was found to be orthologous to human (beta)ig-h3, which is synthesized by lung adenocarcinoma cells in response to transforming growth factor-beta. In the present study, we examined the effect of recombinant chick RGD-CAP on the spreading of chondrocytes and fibroblasts using RGD-CAP-coated dishes. When rabbit articular chondrocytes, chick embryonic sternal chondrocytes, rabbit peritoneal fibroblasts or human MRC5 fibroblasts were seeded on plastic dishes coated with RGD-CAP, cell spreading was enhanced compared with that on control dishes (bovine serum albumin- or beta-galactosidase-coated dishes). The effect of RGD-CAP on the cell spreading required divalent cations (Mg(2+) or Mn(2+)), and was reduced by EDTA. Monoclonal antibodies (mAbs) to the human integrin alpha(1) or beta(1) subunit, but not to the alpha(2), alpha(3), alpha(5) or beta(2) subunits, suppressed the RGD-CAP-induced spreading of human MRC5 fibroblasts. In a parallel experiment, the mAb to the alpha(5) subunit, but not the mAb to the alpha(1) subunit, suppressed fibronectin-induced spreading of these cells. These findings suggest that RGD-CAP is a novel ligand for integrin alpha(1)beta(1) that dose not bind to the RGD motif. Accordingly, an RGD-CAP fragment, which carries a deletion in the C-terminal region containing the RGD motif, was still capable of stimulating cell spreading.

MeSH terms

  • Animals
  • Antibodies, Monoclonal / pharmacology
  • Cations, Divalent
  • Cell Adhesion / drug effects
  • Cell Culture Techniques / methods
  • Cell Division / drug effects
  • Cell Size / drug effects
  • Chick Embryo
  • Chondrocytes / drug effects*
  • Cloning, Molecular
  • Escherichia coli / metabolism
  • Extracellular Matrix Proteins*
  • Fibroblasts / drug effects*
  • Fibronectins
  • Humans
  • Integrin alpha1beta1
  • Integrins / chemistry
  • Integrins / immunology
  • Integrins / metabolism*
  • Neoplasm Proteins / genetics
  • Neoplasm Proteins / immunology
  • Neoplasm Proteins / pharmacology*
  • Peptide Fragments / pharmacology
  • Rabbits
  • Transforming Growth Factor beta*


  • Antibodies, Monoclonal
  • Cations, Divalent
  • Extracellular Matrix Proteins
  • Fibronectins
  • Integrin alpha1beta1
  • Integrins
  • Neoplasm Proteins
  • Peptide Fragments
  • Transforming Growth Factor beta
  • betaIG-H3 protein