title: ADAMTS-13 rapidly cleaves newly secreted ultralarge von Willebrand factor multimers on the endothelial surface under flowing conditions.
abstract: Thrombotic thrombocytopenic purpura (TTP) is a devastating thrombotic disorder caused by widespread microvascular thrombi composed of platelets and von Willebrand factor (VWF). The disorder is associated with a deficiency of the VWF-cleaving metalloprotease, ADAMTS-13, with consequent accumulation of ultralarge (UL) VWF multimers in the plasma. ULVWF multimers, unlike plasma forms of VWF, attach spontaneously to platelet GP Ibalpha, a component of the GP Ib-IX-V complex. We have found that ULVWF multimers secreted from stimulated endothelial cells (ECs) remained anchored to the endothelial surface where platelets and Chinese hamster ovary cells expressing the GP Ib-IX-V complex attached to form long beads-on-a-string structures in the presence of fluid shear stresses in both the venous (2.5 dyne/cm(2)) and arterial (20 and 50 dyne/cm(2)) ranges. Although measurement of the activity of the ADAMTS-13 VWF-cleaving metalloprotease in vitro requires prolonged incubation of the enzyme with VWF under nonphysiologic conditions, EC-derived ULVWF strings with attached platelets were cleaved within seconds to minutes in the presence of normal plasma (containing approximately 100% ADAMTS-13 activity) or in the presence of partially purified ADAMTS-13. By contrast, the strings persisted for the entire period of perfusion (10 minutes) in the presence of plasma from patients with TTP containing 0% to 10% ADAMTS-13 activity. These results suggest that cleavage of EC-derived ULVWF multimers by ADAMTS-13 is a rapid physiologic process that occurs on endothelial cell surfaces.
authors.affiliation: Thrombosis Research Section, Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA. jfdong@bcm.tmc.edu
authors.forename: Jing-fei
authors.initials: JF
authors.lastname: Dong
authors.forename: Joel L
authors.initials: JL
authors.lastname: Moake
authors.forename: Leticia
authors.initials: L
authors.lastname: Nolasco
authors.forename: Aubrey
authors.initials: A
authors.lastname: Bernardo
authors.forename: Wendy
authors.initials: W
authors.lastname: Arceneaux
authors.forename: Corie N
authors.initials: CN
authors.lastname: Shrimpton
authors.forename: Alicia J
authors.initials: AJ
authors.lastname: Schade
authors.forename: Larry V
authors.initials: LV
authors.lastname: McIntire
authors.forename: Kazuo
authors.initials: K
authors.lastname: Fujikawa
authors.forename: José A
authors.initials: JA
authors.lastname: López
mesh_terms: D051722:ADAM Proteins; D000071120:ADAMTS13 Protein; D000328:Adult; D000818:Animals; D001792:Blood Platelets; D016466:CHO Cells; D016022:Case-Control Studies; D002448:Cell Adhesion; D006224:Cricetinae; D019281:Dimerization; D004730:Endothelium, Vascular / Q000737:chemistry / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008666:Metalloendopeptidases / Q000378:metabolism*; D018715:Microscopy, Video; D008875:Middle Aged; D010477:Perfusion; D011485:Protein Binding; D011697:Purpura, Thrombotic Thrombocytopenic / Q000201:enzymology*; D013314:Stress, Mechanical; D014471:Umbilical Veins; D014841:von Willebrand Factor / Q000378:metabolism*
chemical_list: D014841:von Willebrand Factor; D051722:ADAM Proteins; D008666:Metalloendopeptidases; D000071120:ADAMTS13 Protein; C099604:ADAMTS13 protein, human