Inhibitory effects of MLDG-containing heterodimeric disintegrins reveal distinct structural requirements for interaction of the integrin alpha 9beta 1 with VCAM-1, tenascin-C, and osteopontin.
The integrin alpha9beta1 is expressed on epithelial cells, smooth muscle cells, skeletal muscle, and neutrophils and recognizes at least three distinct ligands: vascular cell adhesion molecule 1 (VCAM-1), tenascin-C, and osteopontin. The alpha9 subunit is structurally similar to the integrin alpha4 subunit, and alpha9beta1 and alpha4beta1 both recognize VCAM-1 as a ligand. We therefore examined whether the disintegrin EC3, which we have recently shown specifically inhibits the binding of alpha4 integrins to ligands, would also be a functional inhibitor of alpha9beta1. EC3 and a novel heterodimeric disintegrin that we identified, EC6, both were potent inhibitors of alpha9beta1-mediated adhesion to VCAM-1 and of neutrophil migration across tumor necrosis factor-activated endothelial cells. A peptide containing a novel MLDG motif shared by both of these disintegrins also inhibited alpha9beta1- and alpha4beta1-mediated adhesion to VCAM-1. Surprisingly though, concentrations of EC3 that completely inhibited adhesion of alpha9-transfected cells to VCAM-1 had little or no effect on adhesion to either of the other alpha9beta1 ligands, osteopontin and tenascin-C. Furthermore, peptides AEIDGIEL and SVVYGLR, which we have previously shown inhibit binding of alpha9beta1-expressing cells to tenascin-C and osteopontin, respectively, had no effect on adhesion to VCAM-1. These data suggest that there are structurally distinct requirements for interactions of the alpha9beta1 integrin with VCAM-1 and the extracellular matrix ligands osteopontin and tenascin-C.
Marcinkiewicz
C
C
Sol Sherry Thrombosis Research Center, Department of Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA.
Taooka
Y
Y
Yokosaki
Y
Y
Calvete
J J
JJ
Marcinkiewicz
M M
MM
Lobb
R R
RR
Niewiarowski
S
S
Sheppard
D
D
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002448:Cell Adhesion / Q000187:drug effects; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects; D019281:Dimerization; D019483:Disintegrins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects; D006801:Humans; D016023:Integrins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D020556:Neutrophil Infiltration / Q000187:drug effects; D009504:Neutrophils / Q000166:cytology / Q000187:drug effects; D053495:Osteopontin; D010446:Peptide Fragments / Q000494:pharmacology; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D012795:Sialoglycoproteins / Q000378:metabolism*; D013379:Substrate Specificity; D019063:Tenascin / Q000378:metabolism*; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism*; D014757:Viper Venoms / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*
D019483:Disintegrins; C119089:EC3 protein, Echis carinatus; C415464:EC6 protein, Echis carinatus sochureki; D016023:Integrins; D010446:Peptide Fragments; C506895:SPP1 protein, human; D012795:Sialoglycoproteins; D019063:Tenascin; D019010:Vascular Cell Adhesion Molecule-1; D014757:Viper Venoms; C113256:integrin alpha 9 beta 1; D053495:Osteopontin