Division of Laboratory Medicine, Department of Pathology, The University of Alabama at Birmingham, Birmingham, Alabama, United States.
Thromb Haemost. 2019 Dec;119(12):1933-1946. doi: 10.1055/s-0039-1696713. Epub 2019 Sep 7.
Proteolytic cleavage of von Willebrand factor (VWF) by a plasma a disintegrin and metalloproteinase with a thrombospondin type 1 motifs, member 13 (ADAMTS13) is regulated by shear stress and binding of coagulation factor VIII, platelets or platelet glycoprotein 1b, and ristocetin to VWF.
Current study aims to identify novel VWF binding partners that may modulate VWF functions under physiological conditions.
A deoxyribonucleic acid aptamer-based affinity purification of VWF, followed by tandem mass spectrometry, functional, and binding assays was employed.
Apolipoprotein B100/low-density lipoprotein (apoB100/LDL) was identified as a novel VWF-binding partner. Purified apoB100/LDL was able to accelerate the proteolytic cleavage of VWF by ADAMTS13 under shear in a concentration-dependent manner. This rate-enhancing activity was dramatically reduced when apoB100/LDL was oxidized. More interestingly, the oxidized apoB100/LDL appeared to compete with native apoB100/LDL for its enhancing activity on VWF proteolysis under shear. As a control, a purified apoA1/high-density lipoprotein (apoA1/HDL) or apoB48 exhibited a minimal or no activity enhancing VWF proteolysis by ADAMTS13 under the same conditions. Both VWF and ADAMTS13 were able to bind native or oxidized apoB100/LDL with high affinities. No binding interaction was detected between VWF (or ADAMTS13) and apoA1/HDL (or apoB48). Moreover, apoB100/LDL but not its oxidized products inhibited the adhesion of platelets to ultra large VWF released from endothelial cells under flow. Finally, significantly reduced ratios of high to low molecular weight of VWF multimers with increased levels of plasma VWF antigen were detected in mice fed with high cholesterol diet.
These results indicate that apoB100/LDL may be a novel physiological regulator for ADAMTS13-VWF functions.
血管性血友病因子（VWF）的蛋白水解由血浆 a disintegrin 和金属蛋白酶与血小板反应素 1 型基序，成员 13（ADAMTS13）调控，受切应力调节，并结合凝血因子 VIII、血小板或血小板糖蛋白 1b 和瑞斯托菌素与 VWF 的结合。
本研究旨在鉴定新的 VWF 结合伴侣，这些伴侣可能在生理条件下调节 VWF 的功能。
采用基于脱氧核糖核酸适体的 VWF 亲和纯化，然后进行串联质谱、功能和结合测定。
载脂蛋白 B100/低密度脂蛋白（apoB100/LDL）被鉴定为一种新的 VWF 结合伴侣。在切应力下，纯化的 apoB100/LDL 能够以浓度依赖的方式加速 ADAMTS13 对 VWF 的蛋白水解。当 apoB100/LDL 氧化时，这种促进活性显著降低。更有趣的是，氧化的 apoB100/LDL 似乎与天然 apoB100/LDL 竞争，在切应力下增强其对 VWF 蛋白水解的活性。作为对照，纯化的 apoA1/高密度脂蛋白（apoA1/HDL）或 apoB48 在相同条件下对 ADAMTS13 介导的 VWF 蛋白水解几乎没有或没有促进活性。VWF 和 ADAMTS13 均能与天然或氧化的 apoB100/LDL 高亲和力结合。VWF（或 ADAMTS13）与 apoA1/HDL（或 apoB48）之间未检测到结合相互作用。此外，apoB100/LDL 但不是其氧化产物，可抑制血小板在流动条件下与内皮细胞释放的超大 VWF 的粘附。最后，在喂食高胆固醇饮食的小鼠中，检测到 VWF 抗原水平升高，高分子量 VWF 多聚体与低分子量 VWF 多聚体的比值显著降低。
这些结果表明，apoB100/LDL 可能是 ADAMTS13-VWF 功能的一种新的生理调节剂。
