Propolypeptide of von Willebrand factor is a novel ligand for very late antigen-4 integrin.
We have previously reported that propolypeptide of von Willebrand factor (pp-vWF) promotes melanoma cell adhesion in a beta1 integrin-dependent manner. In this report, we identified the alpha subunit of the cell adhesion receptor for pp-vWF as alpha4. Human leukemia cell lines that express alpha4beta1 integrin (very late antigen-4, VLA-4), but not cell lines which lack VLA-4, attached well to pp-vWF substrate and these adhesions were completely inhibited by anti-alpha4 integrin monoclonal antibody HP2/1. Adhesion of mouse melanoma expressing alpha4 integrin was also inhibited by anti-mouse alpha4 mAb PS/2. Furthermore, transfection of human alpha4 cDNA into alpha4(-) Chinese hamster ovary cells resulted in an acquisition of adhesive activity to pp-vWF, indicating that pp-vWF is a ligand for VLA-4 integrin. Using a recombinant fragment of pp-vWF, the cell attachment site was shown to be located within amino acid residues 376-455 of pp-vWF. A series of synthetic peptides covering this region were tested for the ability to promote cell attachment and a 15-residue peptide designated T2-15 (DCQDHSFSIVIETVQ, residues numbered 395-409) promoted VLA-4 dependent cell adhesion. The peptide was also capable of inhibiting cell adhesion to pp-vWF, suggesting that this sequence represents the cell attachment site. By affinity chromatography using peptide T2-15-Sepharose, it was found that alpha4beta1 integrin complex from extracts of surface iodinated B16 cells specifically bound to the peptide. These results strongly suggest that pp-vWF is a novel physiological ligand for VLA-4.
Isobe
T
T
Department of Biological Sciences, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226, Japan.
Hisaoka
T
T
Shimizu
A
A
Okuno
M
M
Aimoto
S
S
Takada
Y
Y
Saito
Y
Y
Takagi
J
J
D000818:Animals; D018926:Anti-Allergic Agents / Q000378:metabolism*; D002448:Cell Adhesion; D006224:Cricetinae; D006801:Humans; D039041:Integrin alpha4beta1; D019012:Integrin beta1 / Q000378:metabolism*; D016023:Integrins / Q000378:metabolism*; D051379:Mice; D010446:Peptide Fragments / Q000378:metabolism; D010449:Peptide Mapping; D011498:Protein Precursors / Q000378:metabolism*; D016201:Receptors, Lymphocyte Homing / Q000378:metabolism*; D016029:Receptors, Very Late Antigen / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured; D014841:von Willebrand Factor / Q000378:metabolism*
D018926:Anti-Allergic Agents; D039041:Integrin alpha4beta1; D019012:Integrin beta1; D016023:Integrins; D010446:Peptide Fragments; D011498:Protein Precursors; D016201:Receptors, Lymphocyte Homing; D016029:Receptors, Very Late Antigen; D011994:Recombinant Proteins; D014841:von Willebrand Factor; C067003:von Willebrand factor propolypeptide