title: Platelet glycoprotein Ibalpha forms catch bonds with human WT vWF but not with type 2B von Willebrand disease vWF.
abstract: Arterial blood flow enhances glycoprotein Ibalpha (GPIbalpha) binding to vWF, which initiates platelet adhesion to injured vessels. Mutations in the vWF A1 domain that cause type 2B von Willebrand disease (vWD) reduce the flow requirement for adhesion. Here we show that increasing force on GPIbalpha/vWF bonds first prolonged ("catch") and then shortened ("slip") bond lifetimes. Two type 2B vWD A1 domain mutants, R1306Q and R1450E, converted catch bonds to slip bonds by prolonging bond lifetimes at low forces. Steered molecular dynamics simulations of GPIbalpha dissociating from the A1 domain suggested mechanisms for catch bonds and their conversion by the A1 domain mutations. Catch bonds caused platelets and GPIbalpha-coated microspheres to roll more slowly on WT vWF and WT A1 domains as flow increased from suboptimal levels, explaining flow-enhanced rolling. Longer bond lifetimes at low forces eliminated the flow requirement for rolling on R1306Q and R1450E mutant A1 domains. Flowing platelets agglutinated with microspheres bearing R1306Q or R1450E mutant A1 domains, but not WT A1 domains. Therefore, catch bonds may prevent vWF multimers from agglutinating platelets. A disintegrin and metalloproteinase with a thrombospondin type 1 motif-13 (ADAMTS-13) reduced platelet agglutination with microspheres bearing a tridomain A1A2A3 vWF fragment with the R1450E mutation in a shear-dependent manner. We conclude that in type 2B vWD, prolonged lifetimes of vWF bonds with GPIbalpha on circulating platelets may allow ADAMTS-13 to deplete large vWF multimers, causing bleeding.
authors: Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104, USA.
authors: Tadayuki
authors: T
authors: Yago
authors: Jizhong
authors: J
authors: Lou
authors: Tao
authors: T
authors: Wu
authors: Jun
authors: J
authors: Yang
authors: Jonathan J
authors: JJ
authors: Miner
authors: Leslie
authors: L
authors: Coburn
authors: José A
authors: JA
authors: López
authors: Miguel A
authors: MA
authors: Cruz
authors: Jing-Fei
authors: JF
authors: Dong
authors: Larry V
authors: LV
authors: McIntire
authors: Rodger P
authors: RP
authors: McEver
authors: Cheng
authors: C
authors: Zhu
mesh_terms: D051722:ADAM Proteins / Q000378:metabolism; D000071120:ADAMTS13 Protein; D001792:Blood Platelets / Q000378:metabolism; D006801:Humans; D018625:Microscopy, Atomic Force; D008863:Microspheres; D008954:Models, Biological; D008968:Molecular Conformation; D009154:Mutation; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000235:genetics* / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D013314:Stress, Mechanical; D014842:von Willebrand Diseases / Q000235:genetics* / Q000378:metabolism; D014841:von Willebrand Factor / Q000235:genetics* / Q000378:metabolism*
chemical_list: D019038:Platelet Glycoprotein GPIb-IX Complex; D011994:Recombinant Proteins; D014841:von Willebrand Factor; D051722:ADAM Proteins; D000071120:ADAMTS13 Protein; C099604:ADAMTS13 protein, human