title: Matrix-specific suppression of integrin activation in shear stress signaling.
abstract: Atherosclerotic plaque develops at sites of disturbed flow. We previously showed that flow activates endothelial cell integrins, which then bind to the subendothelial extracellular matrix (ECM), and, in cells on fibronectin or fibrinogen, trigger nuclear factor-kappaB activation. Additionally, fibronectin and fibrinogen are deposited into the subendothelial ECM at atherosclerosis-prone sites at early times. We now show that flow activates ECM-specific signals that establish patterns of integrin dominance. Flow induced alpha2beta1 activation in cells on collagen, but not on fibronectin or fibrinogen. Conversely, alpha5beta1 and alphavbeta3 are activated on fibronectin and fibrinogen, but not collagen. Failure of these integrins to be activated on nonpermissive ECM is because of active suppression by the integrins that are ligated. Protein kinase A is activated specifically on collagen and suppresses flow-induced alphavbeta3 activation. Alternatively, protein kinase Calpha is activated on fibronectin and mediates alpha2beta1 suppression. Thus, integrins actively cross-inhibit through specific kinase pathways. These mechanisms may determine cellular responses to complex extracellular matrices.
authors.affiliation: Department of Microbiology, University of Virginia, Charlottesville, VA 22908, USA.
authors.forename: A Wayne
authors.initials: AW
authors.lastname: Orr
authors.forename: Mark H
authors.initials: MH
authors.lastname: Ginsberg
authors.forename: Sanford J
authors.initials: SJ
authors.lastname: Shattil
authors.forename: Hans
authors.initials: H
authors.lastname: Deckmyn
authors.forename: Martin A
authors.initials: MA
authors.lastname: Schwartz
mesh_terms: D000818:Animals; D001808:Blood Vessels / Q000187:drug effects; D002417:Cattle; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism*; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D005353:Fibronectins / Q000378:metabolism; D038982:Integrin alpha2beta1 / Q000378:metabolism*; D039081:Integrin alpha5beta1 / Q000378:metabolism*; D039302:Integrin alphaVbeta3 / Q000378:metabolism*; D008954:Models, Biological; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013314:Stress, Mechanical; D016608:Talin / Q000378:metabolism
chemical_list: D005353:Fibronectins; D038982:Integrin alpha2beta1; D039081:Integrin alpha5beta1; D039302:Integrin alphaVbeta3; D018129:Phosphatidylinositol Phosphates; D016608:Talin; C060974:phosphatidylinositol 3,4,5-triphosphate; D016222:Fibroblast Growth Factor 2; D019869:Phosphatidylinositol 3-Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C