The B domain of coagulation factor VIII interacts with the asialoglycoprotein receptor

article
Background: Coagulation factor VIII (FVIII) is a heavily glycosylated heterodimeric plasma protein that consists of a heavy (domains A1-A2-B) and light chain (domains A3-C1-C2). It has been well established that the clearance of FVIII from the circulation involves mechanisms that are sensitive to the low-density lipoprotein receptor (LDLR) family antagonist receptor-associated protein (RAP), including LDLR-related protein. Because FVIII clearance in the presence of a bolus injection of RAP still occurs fairly efficient, also RAP-independent mechanisms are likely to be involved. Objectives: In the present study, we investigated the interaction of FVIII with the endocytic lectin asialoglycoprotein receptor (ASGPR) and the physiological relevance thereof. Methods and results: Surface plasmon resonance studies demonstrated that FVIII dose-dependently bound to ASGPR with high affinity (Kd ≈ 2 nM). FVIII subunits were different in that only the heavy chain displayed high-affinity binding to ASGPR. Studies employing a FVIII variant that lacks the B domain revealed that FVIII-ASGPR complex assembly is driven by structure elements within the B domain of the heavy chain. The FVIII heavy chain-ASGPR interaction required calcium ions and was inhibited by soluble D-galactose. Furthermore, deglycosylation of the FVIII heavy chain by endoglycosidase F completely abrogated the interaction with ASGPR. In clearance experiments in mice, the FVIII mean residence time was prolonged by the ASGPR-antagonist asialo-orosomucoid (ASOR). Conclusions: We conclude that asparagine-linked oligosaccharide structures of the FVIII B domain recognize the carbohydrate recognition domains of ASGPR and that an ASOR-sensitive mechanism, most likely ASGPR, contributes to the catabolism of coagulation FVIII in vivo. © 2005 International Society on Thrombosis and Haemostasis. Chemicals / CAS: blood clotting factor 8, 9001-27-8; calcium ion, 14127-61-8; galactose, 26566-61-0, 50855-33-9, 59-23-4; n acetyl beta glucosaminidase, 37278-88-9; calcium, 7440-70-2; Asialoglycoprotein Receptor; Calcium, 7440-70-2; Carbohydrates; Factor VIII, 9001-27-8; Galactose, 26566-61-0; Protein Subunits
TNO Identifier
239022
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ISSN
15387933
Source
Journal of Thrombosis and Haemostasis, 3(6), pp. 1257-1265.
Pages
1257-1265
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