Light Chain of Factor VIII Is Sufficient for Accelerating Cleavage of von Willebrand Factor by ADAMTS13 Metalloprotease
Light Chain of Factor VIII Is Sufficient for Accelerating Cleavage of von Willebrand Factor by ADAMTS13 Metalloprotease
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DOI：
10.1074/jbc.m112.390690
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发表时间：
2012-09-21
影响因子：
4.8
通讯作者：
Zheng, X. Long
中科院分区：
文献类型：
--
作者：
Cao, Wenjing;Sabatino, Denise E.;Zheng, X. Long
我们之前证明了凝血因子VIII （FVIII）在流体剪切应力下加速了A崩解素和具有凝血反应蛋白1型重复序列（ADAMTS13）的金属蛋白酶对血管性血友病因子（VWF）的蛋白水解裂解。在本研究中，使用小鼠模型确定了FVIII的结构元件和该辅因子活性的生物学相关性。分离的人FVIII轻链（hFVIII-LC）在剪切作用下以浓度依赖的方式增加ADAMTS13对VWF的蛋白水解裂解。hFVIII-LC的最大速率增强效应接近8倍，与人全长FVIII和b结构域缺失的FVIII （hFVIII-BDD）相当。在相同条件下，重链（hFVIII-HC）和缺乏酸性（a3）区域的轻链（hFVIII-LC Delta a3）对ADAMTS13对VWF蛋白水解没有促进作用。虽然重组hFVIII-HC和hFVIII-LC Delta a3不能检测到与固定化VWF的结合，但重组hFVIII-LC以高亲和力（K-D，类似于15 nM）结合VWF。此外，在水动力刺激后，超大VWF多聚体在fVIII（-/-）小鼠血浆中积累，而在用hFVIII-BDD或hFVIII-LC重组的小鼠血浆中则没有。这些结果表明，在流体剪切应力和（病理）生理条件下，对凝块形成没有生物活性的FVIII轻链足以加速ADAMTS13对VWF的蛋白水解裂解。我们的发现为FVIII如何调节VWF稳态的分子机制提供了新的见解。
We previously demonstrated that coagulation factor VIII (FVIII) accelerates proteolytic cleavage of von Willebrand factor (VWF) by A disintegrin 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 similar to 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-LC Delta a3) have no effect in accelerating VWF proteolysis by ADAMTS13 under the same conditions. Although recombinant hFVIII-HC and hFVIII-LC Delta a3 do not detectably bind immobilized VWF, recombinant hFVIII-LC binds VWF with high affinity (K-D, similar to 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.