Competitive binding of vascular cell adhesion molecule-1 and the HepII/IIICS domain of fibronectin to the integrin alpha 4 beta 1
The integrin receptor alpha 4 beta 1 binds to two different ligands, the extracellular matrix glycoprotein fibronectin and the endothelial cell surface protein vascular cell adhesion molecule-1 (VCAM-1). Using probes derived from each ligand and a variety of cell adhesion and ligand-receptor binding...
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Veröffentlicht in: | The Journal of biological chemistry 1994-02, Vol.269 (6), p.4005-4011 |
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Sprache: | eng |
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Zusammenfassung: | The integrin receptor alpha 4 beta 1 binds to two different ligands, the extracellular matrix glycoprotein fibronectin and
the endothelial cell surface protein vascular cell adhesion molecule-1 (VCAM-1). Using probes derived from each ligand and
a variety of cell adhesion and ligand-receptor binding assays, we have investigated the relationship between the mechanisms
of fibronectin and VCAM-1 interaction with alpha 4 beta 1. CS1 peptide, which represents the dominant active site from the
HepII/IIICS recognition domain in fibronectin, was found to inhibit VCAM-1-dependent adhesion in three different assays: MOLT-4
T lymphoblastic leukaemia cell attachment to immobilized recombinant soluble VCAM-1 (rsVCAM-1), MOLT-4 cell attachment to
monolayers of VCAM-1-transfected COS-1 cells, and A375-SM melanoma cell spreading on immobilized rs VCAM-1. Half-maximal inhibition
required CS1 concentrations of 1.7-3.0 mg/ml, some 3-7-fold higher than that needed to autoinhibit adhesion to CS1-IgG conjugate.
Using a more sensitive solid-phase receptor-ligand binding assay, CS1 was found to be a potent inhibitor of the binding of
rsVCAM-1 to alpha 4 beta 1 (half-maximal inhibition at 13 micrograms/ml). In agreement with cell-based assays, severalfold
lower concentrations of CS1 were required to inhibit binding of recombinant HepII/IIICS region of fibronectin (half-maximal
inhibition at 3 micrograms/ml). VCAM-1-alpha 4 beta 1 binding was blocked not only by CS1 peptide but also by the recombinant
HepII/IIICS region of fibronectin. Kinetic analysis of CS1 inhibition of VCAM-1 binding revealed that it was directly competitive
in nature, indicating that VCAM-1 and fibronectin recognize either identical or spatially overlapping binding sites on alpha
4 beta 1. The implications of these results for the future design of VCAM-1 antagonists are discussed. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1016/S0021-9258(17)41734-0 |