title: Real-time analysis of very late antigen-4 affinity modulation by shear.
abstract: Shear promotes endothelial recruitment of leukocytes, cell activation, and transmigration. Mechanical stress on cells caused by shear can induce a rapid integrin conformational change and activation, followed by an increase in binding to the extracellular matrix. The molecular mechanism of increased avidity is unknown. We have shown previously that the affinity of the alpha(4)beta(1) integrin, very late antigen-4 (VLA-4), measured with an LDV-containing small molecule, varies with cellular avidity, measured from cell disaggregation rates. In this study, we measured in real time affinity changes of VLA-4 in response to shear. The resulting affinity was comparable with the state mediated by receptor signaling and corresponded in time with intracellular Ca(2+) responses. Ca(2+) ionophores and N,N'-[1,2-ethanediyl-bis(oxy-2,1-phenylene)]bis[N-[2-[(acetyloxy)methoxy]-2-oxoethyl]]-, bis[(acetyloxy)methyl]ester demonstrate that the affinity regulation of VLA-4 in the presence of shear was related to Ca(2+) signaling. Pertussis toxin treatment implicates G(i) in an unknown pathway that connects shear, Ca(2+) elevation, VLA-4 affinity, and cell avidity.
authors.affiliation: Department of Pathology and Cancer Research and Treatment Center, University of New Mexico, Albuquerque, New Mexico 87131, USA.
authors.forename: Gordon J
authors.initials: GJ
authors.lastname: Zwartz
authors.forename: Alexandre
authors.initials: A
authors.lastname: Chigaev
authors.forename: Denise C
authors.initials: DC
authors.lastname: Dwyer
authors.forename: Terry D
authors.initials: TD
authors.lastname: Foutz
authors.forename: Bruce S
authors.initials: BS
authors.lastname: Edwards
authors.forename: Larry A
authors.initials: LA
authors.lastname: Sklar
mesh_terms: D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D002138:Calibration; D002465:Cell Movement; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D005434:Flow Cytometry; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism; D006801:Humans; D039041:Integrin alpha4beta1 / Q000737:chemistry*; D007476:Ionophores / Q000737:chemistry / Q000494:pharmacology; D007700:Kinetics; D008024:Ligands; D008954:Models, Biological; D037342:Pertussis Toxin / Q000494:pharmacology; D011485:Protein Binding; D011487:Protein Conformation; D015398:Signal Transduction; D013314:Stress, Mechanical; D013696:Temperature; D013997:Time Factors; D014162:Transfection; D020298:U937 Cells
chemical_list: D039041:Integrin alpha4beta1; D007476:Ionophores; D008024:Ligands; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D004533:Egtazic Acid; D037342:Pertussis Toxin; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D002118:Calcium