Rayes J, Hommais A, Legendre P, Tout H, Veyradier A, Obert B, Ribba A S, Girma J P
INSERM U770 and Université Paris-Sud, Faculté de Médecine IFR93, Le Kremlin-Bicêtre, France.
J Thromb Haemost. 2007 Feb;5(2):321-8. doi: 10.1111/j.1538-7836.2007.02296.x. Epub 2006 Nov 1.
von Willebrand disease (VWD) type 2 is associated with mutations in von Willebrand factor (VWF) that affect its secretion, multimeric pattern, affinity for platelet receptors and clearance of the protein. While increased proteolysis by a disintegrin-like and metalloprotease with thrombospondin type 1 motifs-13 (ADAMTS-13) has been clearly established for VWF type 2A, only little is known about VWF types 2B and 2M in this regard.
Sensitivity of wild-type (WT) and mutated recombinant (r) VWF to proteolysis by ADAMTS-13 was investigated to better understand the role of this process in the pathophysiology of VWD.
We used human rADAMTS-13-WT to digest 11 full-length recombinant forms of VWF carrying molecular abnormalities identified in patients with VWD type 2A (E1638K and P1648S), type 2B (InsM1303, R1306W, R1308P and V1314F) and type 2M (G1324A, E1359K, K1362T, R1374H and I1425F).
Using low ionic strength conditions, all mutations induced increased proteolysis of rVWF by rADAMTS-13 as compared with rVWF-WT. The susceptibility of mutants decreased in the following order: type 2A > type 2B > type 2M > rVWF-WT. At physiological salt concentration (150 mm NaCl) the sensitivity of all rVWF to rADAMTS-13 was significantly decreased. However, type 2A and type 2B mutants still exhibited a significantly higher susceptibility to rADAMTS-13 than rVWF-WT, whereas type 2M mutants normalized.
Type 2M mutants and rVWF-WT exhibit a similar sensitivity to rADAMTS-13-mediated proteolysis, in agreement with the normal multimeric pattern in vivo. In VWD type 2B, the spontaneous binding to platelets and excessive degradation by ADAMTS-13 of VWF high-molecular-weight multimers may account for their clearance from plasma.
2型血管性血友病（VWD）与血管性血友病因子（VWF）的突变有关，这些突变会影响其分泌、多聚体模式、对血小板受体的亲和力以及该蛋白的清除。虽然已明确证实2A型VWF会因含Ⅰ型血小板反应蛋白基序的解整合素样金属蛋白酶13（ADAMTS - 13）导致蛋白水解增加，但在这方面，对于2B型和2M型VWF却知之甚少。
研究野生型（WT）和突变型重组（r）VWF对ADAMTS - 13蛋白水解的敏感性，以更好地理解这一过程在VWD病理生理学中的作用。
我们使用人重组ADAMTS - 13 - WT来消化11种全长重组形式的VWF，这些VWF携带在2A型（E1638K和P1648S）、2B型（InsM1303、R1306W、R1308P和V1314F）和2M型（G1324A、E1359K、K1362T、R1374H和I1425F）血管性血友病患者中鉴定出的分子异常。
在低离子强度条件下，与野生型重组VWF（rVWF - WT）相比，所有突变均导致ADAMTS - 13对重组VWF的蛋白水解增加。突变体的敏感性按以下顺序降低：2A型＞2B型＞2M型＞rVWF - WT。在生理盐浓度（150 mM NaCl）下，所有重组VWF对ADAMTS - 13的敏感性均显著降低。然而，2A型和2B型突变体对ADAMTS - 13的敏感性仍显著高于rVWF - WT，而2M型突变体则恢复正常。
2M型突变体和rVWF - WT对ADAMTS - 13介导的蛋白水解表现出相似的敏感性，这与体内正常的多聚体模式一致。在2B型血管性血友病中，VWF高分子量多聚体与血小板的自发结合以及被ADAMTS - 13过度降解可能是其从血浆中清除的原因。
