The carboxyl-terminal fragment of osteopontin suppresses arginine-glycine-asparatic acid-dependent cell adhesion.
Osteopontin (OPN) is a secreted glycoprotein implicated in cell adhesion. It contains the arginine-glycine-asparatic acid (RGD) cell adhesive domain and the thrombin cleavage sequence. Although thrombin cleavage of OPN has been shown to be of physiological importance, the function of C-terminal OPN fragment cleaved by thrombin remains unknown. To determine its role, we performed cell adhesion assays using glutathione S-transferase-OPN fusion protein fragments and full-length OPN fusion protein. The N-terminal fragment containing RGD motif promoted enhanced adhesion of mouse and human fibroblasts by 2.9 and 2.8 folds in comparison with full-length OPN, respectively. The enhanced adhesion of both cells mediated by N-terminal fragment was significantly suppressed by addition of C-terminal fragment lacking RGD motif that has less cell adhesive property than full-length OPN. These results suggest that the C-terminal domain may play a pivotal role in regulating OPN functions by suppressing the RGD-dependent cell adhesion.
Takahashi
K
K
Department of Respiratory Medicine, Juntendo University, School of Medicine, Tokyo, Japan. k-m3540@ma.kcom.ne.jp
Takahashi
F
F
Tanabe
K K
KK
Takahashi
H
H
Fukuchi
Y
Y
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D002448:Cell Adhesion / Q000187:drug effects*; D002478:Cells, Cultured; D005347:Fibroblasts / Q000187:drug effects; D005982:Glutathione Transferase; D006801:Humans; D051379:Mice; D009842:Oligopeptides; D053495:Osteopontin; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology*; D011993:Recombinant Fusion Proteins / Q000494:pharmacology; D012795:Sialoglycoproteins / Q000737:chemistry / Q000494:pharmacology*
D009842:Oligopeptides; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; C506895:SPP1 protein, human; D012795:Sialoglycoproteins; C506896:Spp1 protein, mouse; D053495:Osteopontin; C047981:arginyl-glycyl-aspartic acid; D005982:Glutathione Transferase