Light Chain of Factor VIII Is Sufficient for Accelerating Cleavage of von Willebrand Factor by ADAMTS13 Metalloprotease

• Published in: The Journal of biological chemistry Vol. 287; no. 39; pp. 32459 - 32466
• Main Authors: Cao, Wenjing, Sabatino, Denise E., Altynova, Ekaterina, Lange, Amy M., Casina, Veronica C., Camire, Rodney M., Zheng, X.Long
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 21.09.2012; American Society for Biochemistry and Molecular Biology
• Subjects: ADAM Proteins - chemistry; ADAM Proteins - genetics; ADAM Proteins - metabolism; ADAMTS13; ADAMTS13 Protein; Animals; Cricetinae; Enzyme Catalysis; Enzymology; Factor VIII; Factor VIII - chemistry; Factor VIII - genetics; Factor VIII - metabolism; HEK293 Cells; Hemophilia A; Hemostasis; Homeostasis - physiology; Humans; Mice; Mouse Model; Protein Structure, Tertiary; Proteolysis; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; von Willebrand Factor; von Willebrand Factor - chemistry; von Willebrand Factor - genetics; von Willebrand Factor - metabolism; ADAMTS13; Hemostasis; Enzyme Catalysis; Factor VIII; von Willebrand Factor; Hemophilia A; Mouse Model
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M112.390690

We previously demonstrated that coagulation factor VIII (FVIII) accelerates proteolytic cleavage of von Willebrand factor (VWF) by Adisintegrin and metalloprotease with thrombospondin type 1 repeats (ADAMTS13) under fluid shear stress. In this study, the structural elements of FVIII required for the rate-enhancing effect and the biological relevance of this cofactor activity are determined using a murine model. An isolated light chain of human FVIII (hFVIII-LC) increases proteolytic cleavage of VWF by ADAMTS13 under shear in a concentration-dependent manner. The maximal rate-enhancing effect of hFVIII-LC is ∼8-fold, which is comparable with human full-length FVIII and B-domain deleted FVIII (hFVIII-BDD). The heavy chain (hFVIII-HC) and the light chain lacking the acidic (a3) region (hFVIII-LCΔa3) have no effect in accelerating VWF proteolysis by ADAMTS13 under the same conditions. Although recombinant hFVIII-HC and hFVIII-LCΔa3 do not detectably bind immobilized VWF, recombinant hFVIII-LC binds VWF with high affinity (KD, ∼15 nm). Moreover, ultra-large VWF multimers accumulate in the plasma of fVIII−/− mice after hydrodynamic challenge but not in those reconstituted with either hFVIII-BDD or hFVIII-LC. These results suggest that the light chain of FVIII, which is not biologically active for clot formation, is sufficient for accelerating proteolytic cleavage of VWF by ADAMTS13 under fluid shear stress and (patho) physiological conditions. Our findings provide novel insight into the molecular mechanism of how FVIII regulates VWF homeostasis. Background: The structural component of FVIII required for regulating VWF proteolysis is not fully understood. Results: A light chain of FVIII appears to be sufficient for accelerating the cleavage of VWF by ADAMTS13 in vitro and in vivo. Conclusion: Proteolytic cleavage of VWF can be regulated by the FVIII light chain. Significance: The findings provide insight into the structure-function relationship of FVIII in maintaining VWF homeostasis.