title: Shear-induced disulfide bond formation regulates adhesion activity of von Willebrand factor.
abstract: von Willebrand factor (VWF) is the largest multimeric adhesion ligand circulating in blood. Its adhesion activity is related to multimer size, with the ultra-large forms freshly released from the activated endothelial cells being most active, capable of spontaneously binding to platelets. In comparison, smaller plasma forms circulating in blood bind platelets only under high fluid shear stress or induced by modulators. The structure-function relationships that distinguish the two types of VWF multimers are not known. In this study, we demonstrate that some of the plasma VWF multimers contain surface-exposed free thiols. Physiological and pathological levels of shear stresses (50 and 100 dynes/cm(2)) promote the formation of disulfide bonds utilizing these free thiols. The shear-induced thiol-disulfide exchange increases VWF binding to platelets. The thiol-disulfide exchange involves some or all of nine cysteine residues (Cys(889), Cys(898), Cys(2448), Cys(2451), Cys(2490), Cys(2491), Cys(2453), Cys(2528), and Cys(2533)) in the D3 and C domains as determined by mass spectrometry of the tryptic VWF peptides. These results suggest that the thiol-disulfide state may serve as an important structural determinant of VWF adhesion activity and can be modified by fluid shear stress.
authors.affiliation: Section of Thrombosis Research, Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA.
authors.forename: Hiuwan
authors.initials: H
authors.lastname: Choi
authors.forename: Khatira
authors.initials: K
authors.lastname: Aboulfatova
authors.forename: Henry J
authors.initials: HJ
authors.lastname: Pownall
authors.forename: Richard
authors.initials: R
authors.lastname: Cook
authors.forename: Jing-fei
authors.initials: JF
authors.lastname: Dong
mesh_terms: D001792:Blood Platelets / Q000378:metabolism; D003545:Cysteine / Q000737:chemistry / Q000378:metabolism; D004220:Disulfides / Q000737:chemistry* / Q000378:metabolism; D042783:Endothelial Cells / Q000378:metabolism; D006801:Humans; D008024:Ligands; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary / Q000502:physiology; D033081:Shear Strength; D013314:Stress, Mechanical; D013329:Structure-Activity Relationship; D014841:von Willebrand Factor / Q000737:chemistry* / Q000378:metabolism
chemical_list: D004220:Disulfides; D008024:Ligands; D010455:Peptides; D014841:von Willebrand Factor; D003545:Cysteine