Department of Clinical Laboratory Investigation, Graduate School of Medicine, Shinshu University, Matsumoto, Japan.
Laboratory of Clinical Chemistry and Immunology, Department of Biomedical Laboratory Sciences, School of Health Sciences, Shinshu University, 3-1-1 Asahi, Matsumoto, 390-8621, Japan.
Int J Hematol. 2020 Sep;112(3):331-340. doi: 10.1007/s12185-020-02919-5. Epub 2020 Jun 19.
We identified two heterozygous dysfibrinogenemias, Bβp.Gly45Cys (Kyoto VII; K-VII) and Bβp.Arg74Cys (Iida II; I-II). The impairment of polymerization of Bβp.G45C has been well analyzed; however, that of Bβp.R74C has not. Thus, we compared fibrin polymerization between these variants. To determine the structural and functional characterization of purified fibrinogens, we performed immunoblotting analysis, kinetic analyses of fibrinopeptide A and B release, and thrombin- or batroxobin-catalyzed fibrin or fibrin monomer polymerization. Immunoblotting analysis showed that both variant fibrinogens had variant fibrinogen-albumin complexes and variant fibrinogen multimers, and the amounts of fibrinogen-albumin complexes with fibrinogen K-VII was more than with fibrinogen I-II. Moreover, fibrinopeptide B release from fibrinogen K-VII was about 50% of the control, whereas the others were normal. The maximum slopes of polymerization for variant fibrinogens were reduced, but fibrinogen K-VII was reduced more than fibrinogen I-II. The present study demonstrated that both Bβp.G45C and Bβp.R74C variants showed the presence of variant fibrinogen-albumin complexes and variant fibrinogen multimers, and polymerization of Bβp.G45C was impaired more than Bβp.R74C. Our study and several previous reports concerning the clinical phenotype of both variants suggested the risks of bleeding for patients with Bβp.G45C and thrombosis for patients with Bβp.R74C.
我们鉴定了两种杂合的纤维蛋白原血症，Bβp.Gly45Cys（京都 VII 型；K-VII）和 Bβp.Arg74Cys（饭田 II 型；I-II）。Bβp.G45C 的聚合障碍已得到很好的分析；然而，Bβp.R74C 的聚合障碍尚未得到分析。因此，我们比较了这些变体的纤维蛋白聚合。为了确定纯化纤维蛋白原的结构和功能特征，我们进行了免疫印迹分析、纤维肽 A 和 B 释放的动力学分析以及凝血酶或巴斯德菌蛋白酶催化的纤维蛋白或纤维蛋白单体聚合。免疫印迹分析表明，两种变体纤维蛋白原均具有变体纤维蛋白原-白蛋白复合物和变体纤维蛋白原多聚体，并且具有纤维蛋白原 K-VII 的纤维蛋白原-白蛋白复合物的量多于纤维蛋白原 I-II。此外，纤维蛋白原 K-VII 的纤维肽 B 释放量约为对照的 50%，而其他则正常。变体纤维蛋白原的聚合最大斜率降低，但纤维蛋白原 K-VII 的降低程度大于纤维蛋白原 I-II。本研究表明，Bβp.G45C 和 Bβp.R74C 变体均存在变体纤维蛋白原-白蛋白复合物和变体纤维蛋白原多聚体，并且 Bβp.G45C 的聚合受到的影响大于 Bβp.R74C。我们的研究和之前几项关于这两种变体的临床表型的报告表明，Bβp.G45C 患者存在出血风险，Bβp.R74C 患者存在血栓形成风险。
