O-linked carbohydrate of recombinant von Willebrand factor influences ristocetin-induced binding to platelet glycoprotein 1b.

Abstract

By transfecting the full-length cDNA for human von Willebrand factor (vWf) into a line of Chinese hamster ovary cells with a defect in carbohydrate metabolism, we have prepared recombinant vWf specifically lacking 0-linked carbohydrates. We have compared this under-glycosylated protein to fully glycosylated recombinant vWf with respect to several structural and binding properties. vWf deficient in 0-linked glycans was synthesized, assembled into multimers, and secreted in an apparently normal manner and was not prone to degradation in the extracellular milieu. It did not differ from fully glycosylated vWf in ability to bind to heparin or to collagen type I but did interact less well with glycoprotein lb on formalin-fixed platelets. This decreased interaction was evidenced in both a lessened overall binding to platelets and in diminished capacity to promote platelet agglutination, in the presence of ristocetin. In contrast, no difference was seen in platelet binding in the presence of botrocetin. These data indicate a possible role for 0-linked carbohydrates in the vWf-glycoprotein lb interaction promoted by ristocetin and suggest that abnormalities in carbohydrate modification might contribute to the altered ristocetindependent reactivity between vWf and platelets described for some variant forms of von Willebrand disease. (J. Clin. Invest. 1992Invest. . 90:2258Invest. -2267

O-linked glycosylation of von Willebrand factor modulates the interaction with platelet receptor glycoprotein Ib under static and shear stress conditions

“…VWF lacking OLGs exhibited diminished reactivity with GPIb and ristocetininduced platelet agglutination but exhibited normal platelet binding potential in the presence of botrocetin. 18 Conversely, isolated VWF-A1 domain devoid of OLGs exhibited increased platelet aggregation potential. 20 There are also limited data regarding the Submitted February 9, 2012; accepted April 12, 2012.…”

“…16,17 VWF lacking O-glycans is synthesized, multimerized, secreted, and binds heparin and collagen type I in the same way as the fully glycosylated form. 18 We recently published a detailed study of the VWF O-glycome composition showing the presence of unusual disialosyl motifs and ABH-bearing core 2 structures. 19 However, the ability of VWF deficient in OLGs to interact with platelets has not been fully explored.…”

Re-establishment of VWF-dependent Weibel-Palade bodies in VWD endothelial cells

“…The VWF molecule is glycosylated, carbohydrate processed, and sulfated. 11,12 In the Golgi, VWF dimers form amino-terminal multimers, and propeptide is cleaved, presumably by the enzyme furin. 13 VWF is stored together with its propeptide in regulated secretory vesicles, Weibel-Palade bodies in endothelial cells and ␣-granules in megakaryocytes or platelets.…”

Sialyltransferase ST3Gal-IV operates as a dominant modifier of hemostasis by concealing asialoglycoprotein receptor ligands

“…Enzymatic elimination of multiple glycan structures, including sialic acid linkages, has been shown to alter VWF proteolytic degradation, platelet aggregation function, multimerization, and half-life in plasma (5)(6)(7)(8)(9)(10). These findings suggest the possibility that inherited genetic lesions in the pathways of glycan synthesis could modify the severity of VWD and may be directly responsible for VWD in some cases.…”