title: Enzymatically catalyzed disulfide exchange is required for platelet adhesion to collagen via integrin alpha2beta1.
abstract: Integrin alpha2beta1 is the principal adhesive receptor for collagen but platelets also adhere through glycoprotein VI (GPVI). Integrin alphaIIbbeta3 may augment platelet adhesion. We have shown that disulfide exchange is necessary for platelet adhesion to fibrinogen, fibronectin, and collagen. However 2 questions remained: (1) Can activated alphaIIbbeta3 explain the observed role of disulfide exchange in adhesion to collagen, or is this role common to other integrins? (2) Is disulfide dependence specific to the integrin receptors or shared with GPVI? To discriminate adhesive functions of alpha2beta1 from those of alphaIIbbeta3 we used Glanzmann platelets and alphaIIbbeta3-specific antibodies applied to normal platelets. To resolve adhesive events mediated by alpha2beta1 from those of GPVI we used synthetic peptides specific to each receptor. We addressed direct integrin ligation using purified alpha2beta1 and recombinant I domain. We observed the following: adhesion to the alpha2beta1-specific peptide was disulfide-exchange dependent and protein disulfide isomerase (PDI) mediated; membrane-impermeant thiol blockers inhibited alpha2beta1, but not GPVI mediated, adhesion; direct blockade of PDI revealed that it is involved in adhesion through alpha2beta1 but not GPVI; and purified alpha2beta1, but not recombinant I domain, depended on free thiols for ligation. These data suggest that the enzymatically catalyzed adhesion-associated reorganization of disulfide bonds is common to members of the integrin family and specific to this family.
authors.affiliation: The Coagulation Laboratory, Rabin Medical Center-Beilinson Campus, Zabotinski St, Petah-Tiqva 49100, Israel. jlahav@netvision.net.il
authors.forename: Judith
authors.initials: J
authors.lastname: Lahav
authors.forename: Eveline M
authors.initials: EM
authors.lastname: Wijnen
authors.forename: Oded
authors.initials: O
authors.lastname: Hess
authors.forename: Samir W
authors.initials: SW
authors.lastname: Hamaia
authors.forename: Delia
authors.initials: D
authors.lastname: Griffiths
authors.forename: Michael
authors.initials: M
authors.lastname: Makris
authors.forename: C Graham
authors.initials: CG
authors.lastname: Knight
authors.forename: David W
authors.initials: DW
authors.lastname: Essex
authors.forename: Richard W
authors.initials: RW
authors.lastname: Farndale
mesh_terms: D002731:4-Chloromercuribenzenesulfonate / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000906:Antibodies / Q000494:pharmacology; D001414:Bacitracin / Q000494:pharmacology; D002352:Carrier Proteins / Q000378:metabolism; D002384:Catalysis; D003094:Collagen / Q000378:metabolism*; D003432:Cross-Linking Reagents / Q000378:metabolism; D004220:Disulfides / Q000378:metabolism*; D004228:Dithionitrobenzoic Acid / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006801:Humans; D038982:Integrin alpha2beta1 / Q000737:chemistry / Q000378:metabolism*; D008024:Ligands; D010455:Peptides / Q000378:metabolism; D010879:Piperazines / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D010973:Platelet Adhesiveness / Q000502:physiology*; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000276:immunology / Q000378:metabolism; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D019704:Protein Disulfide-Isomerases / Q000037:antagonists & inhibitors / Q000276:immunology; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013439:Sulfhydryl Reagents / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D000906:Antibodies; D002352:Carrier Proteins; D003432:Cross-Linking Reagents; D004220:Disulfides; C090662:GR 144053; D038982:Integrin alpha2beta1; D008024:Ligands; D010455:Peptides; D010879:Piperazines; D010880:Piperidines; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D010980:Platelet Membrane Glycoproteins; D011994:Recombinant Proteins; D013438:Sulfhydryl Compounds; D013439:Sulfhydryl Reagents; C435908:collagen-related peptide; C098341:platelet membrane glycoprotein VI; D001414:Bacitracin; D002731:4-Chloromercuribenzenesulfonate; D003094:Collagen; D004228:Dithionitrobenzoic Acid; D019704:Protein Disulfide-Isomerases