Tashima Yuko, Banno Fumiaki, Kita Toshiyuki, Matsuda Yasuyuki, Yanamoto Hiroji, Miyata Toshiyuki
Department of Molecular Pathogenesis, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan.
Laboratory of Neurology and Neurosurgery, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan.
PLoS One. 2017 Jul 7;12(7):e0180981. doi: 10.1371/journal.pone.0180981. eCollection 2017.
Plasminogen (Plg) is a precursor of plasmin that degrades fibrin. A race-specific A620T mutation in Plg, also known as Plg-Tochigi, originally identified in a patient with recurrent venous thromboembolism, causes dysplasminogenemia with reduced plasmin activity. The Plg-A620T mutation is present in 3-4% of individuals in East Asian populations, and as many as 50,000 Japanese are estimated to be homozygous for the mutant 620T allele. In the present study, to understand the changes of thrombotic phenotypes in individuals with the mutant 620T allele, we generated knock-in mice carrying the homozygous Plg-A622T mutation (PlgT/T), an equivalent to the A620T mutation in human Plg. PlgT/T mice grew normally but showed severely reduced plasmin activity activated by urokinase, equivalent to ~8% of that in wild-type mice. In vitro fibrin clot lysis in plasma was significantly slower in PlgT/T mice than in wild-type mice. However, all experimental models of electrolytic deep vein thrombosis, tissue factor-induced pulmonary embolism, transient focal brain ischaemic stroke, or skin-wound healing showed largely similar phenotypes between PlgT/T mice and wild-type mice. Protein S-K196E mutation (Pros1E/E) is a race-specific genetic risk factor for venous thromboembolism. Coexistence in mice of PlgT/T and Pros1E/E did not affect pulmonary embolism symptoms, compared with those in Pros1E/E mice. Hence, the present study showed that the Plg-A622T mutation, which confers ~8% plasmin activity, does not increase the risk of thrombotic diseases in mice under experimental thrombotic conditions and does not modify the thrombotic phenotype observed in Pros1E/E mice. PlgT/T mice can be used to investigate the potential pathophysiological impact of the Plg-A620T mutation.
纤溶酶原（Plg）是降解纤维蛋白的纤溶酶的前体。纤溶酶原中一种种族特异性的A620T突变，也称为纤溶酶原 - 枥木型，最初在一名复发性静脉血栓栓塞患者中发现，可导致纤溶酶原血症伴纤溶酶活性降低。纤溶酶原A620T突变在东亚人群中3% - 4%的个体中存在，估计多达50000名日本人是突变620T等位基因的纯合子。在本研究中，为了解携带突变620T等位基因个体的血栓形成表型变化，我们构建了携带纯合纤溶酶原A622T突变（PlgT/T）的基因敲入小鼠，该突变等同于人类纤溶酶原中的A620T突变。PlgT/T小鼠生长正常，但尿激酶激活的纤溶酶活性严重降低，相当于野生型小鼠的约8%。PlgT/T小鼠血浆中的体外纤维蛋白凝块溶解明显比野生型小鼠慢。然而，在电解性深静脉血栓形成、组织因子诱导的肺栓塞、短暂性局灶性脑缺血性中风或皮肤伤口愈合的所有实验模型中，PlgT/T小鼠和野生型小鼠之间表现出基本相似的表型。蛋白S - K196E突变（Pros1E/E）是静脉血栓栓塞的种族特异性遗传危险因素。与Pros1E/E小鼠相比，PlgT/T和Pros1E/E在小鼠中的共存并不影响肺栓塞症状。因此，本研究表明，赋予约8%纤溶酶活性的纤溶酶原A622T突变在实验性血栓形成条件下不会增加小鼠血栓性疾病的风险，也不会改变在Pros1E/E小鼠中观察到的血栓形成表型。PlgT/T小鼠可用于研究纤溶酶原A620T突变的潜在病理生理影响。
