RGD-CAP ((beta)ig-h3) enhances the spreading of chondrocytes and fibroblasts via integrin alpha(1)beta(1).
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.
Ohno
S
S
Department of Orthodontics, Hiroshima University School of Dentistry, Hiroshima 734-8553, Japan.
Noshiro
M
M
Makihira
S
S
Kawamoto
T
T
Shen
M
M
Yan
W
W
Kawashima-Ohya
Y
Y
Fujimoto
K
K
Tanne
K
K
Kato
Y
Y
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D002413:Cations, Divalent; D002448:Cell Adhesion / Q000187:drug effects; D018929:Cell Culture Techniques / Q000379:methods; D002455:Cell Division / Q000187:drug effects; D048429:Cell Size / Q000187:drug effects; D002642:Chick Embryo; D019902:Chondrocytes / Q000187:drug effects*; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000378:metabolism; D016326:Extracellular Matrix Proteins; D005347:Fibroblasts / Q000187:drug effects*; D005353:Fibronectins; D006801:Humans; D039222:Integrin alpha1beta1; D016023:Integrins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000235:genetics / Q000276:immunology / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology; D011817:Rabbits; D016212:Transforming Growth Factor beta; D000099222:betaIG-H3 Protein
D000911:Antibodies, Monoclonal; D002413:Cations, Divalent; D016326:Extracellular Matrix Proteins; D005353:Fibronectins; D039222:Integrin alpha1beta1; D016023:Integrins; D009363:Neoplasm Proteins; D010446:Peptide Fragments; D016212:Transforming Growth Factor beta; D000099222:betaIG-H3 Protein