血栓调节蛋白（TM）质或量的异常与血栓形成有着潜在生物学联系。然而TM基因变异引起的血栓形成鲜有研究，lectin区域天然突变未见报道，lectin结构域的完整功能有待探索。申请人在3个易栓症家系发现TM-lectin区新突变376G>T，体外实验提示突变TM辅助激活蛋白C的活性降至56.2%，推断突变引起126位小体积酸性氨基酸D置换为大体积非极性氨基酸Y，使lectin区的电荷富集特性和功能改变，引起血液高凝状态。本项目拟从该突变入手，利用既往建立的大型静脉血栓DNA样本库，采用生物大分子相互作用等技术和定点突变的小鼠模型，研究D126Y的人群分布与血栓风险，阐述突变对凝血、纤溶、炎症途径的影响，明确lectin区的功能；进而合成TM-lectin-EGF区的抗栓肽段，用于小鼠静脉血栓的防治。本项目有望揭示TM-lectin区天然优势突变及其引起血栓形成的机制，为抗血栓治疗提供新思路。

It is biologically reasonable that the quality or quantity abnormity of the thrombomodulin is linked to thrombosis. However, few studies have focused on thrombosis caused by thrombomodulin gene variants. Moreover, there is no report on natural mutations in the lectin-like domain of thrombomodulin. The complete functions of the lectin-like domain are still unknown. Recently, we identified a novel c.376G>T mutation in 3 unrelated thrombophilia pedigrees. In vitro experiments showed that the antigen level in the surface of the HEK293 cell lines of the mutant is comparable to that of the wild-type TM. Nevertheless, the thrombin-cofactor activity of protein C activation of the mutant decreased to 56.2%. We hypothesized that the mutation could lead to a Asp126Tyr substitution, and changes in the charge enrichment feature and the conformation of the lectin-like domain. Thus, the mutation will cause a hypercoagulable state, by impairing the thrombomodulin-based protein C or TAFI activation, and HMGB1 inactivation. In this project, by employing the established thrombosis DNA sample bank, the SPR and other methods, and point-mutation mice model, we intend to investigate the prevalence and the risk for venous thrombosis of this predominant TM D126Y mutation, the consequence on the coagulation, fibrinolysis, and inflammation, in order to understand the functions of the lectin-like domain. In addition, we designed a new strategy for anti-thrombotic therapy, using a recombinant TM only containing the lectin-like and EGF domains. This project will reveal the molecular mechanisms of thrombosis caused by the natural D126Y mutation, and provide new directions for more effective prevention and treatment of thrombotic diseases.