ALOX12 mutation in a family with dominantly inherited bleeding diathesis
ALOX12 mutation in a family with dominantly inherited bleeding diathesis
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DOI：
10.1038/s10038-020-00887-6
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发表时间：
2021-02-10
影响因子：
3.5
通讯作者：
Hayasaka, Kiyoshi
中科院分区：
文献类型：
--
作者：
Mitsui, Tetsuo;Makino, Satoshi;Hayasaka, Kiyoshi
花生四烯酸（AA）级联在血小板聚集中起重要作用。从膜磷脂释放的AA通过环氧合酶（COX）途径代谢为血栓素A(2) （TXA(2)）或通过12s脂氧合酶（ALOX12）代谢为12-氢过氧二碳四烯酸（12-HPETE）。与众所周知的COX途径在血小板聚集中的作用相反，ALOX12的作用尚不清楚。alox12缺陷小鼠的血小板对adp诱导的聚集表现出更高的敏感性。然而，最近的证据强烈表明ALOX12在血小板聚集和钙信号传导中起着重要作用。12-HPETE增强凝血酶和凝血素诱导的血小板聚集和钙信号。ALOX12的抑制实验表明，受刺激的血小板聚集和钙信号传导降低。我们研究了一个家庭与显性遗传性出血素质使用下一代测序分析。血小板聚集研究显示先证者的血小板对ADP、TXA(2)模拟物U46619、胶原蛋白和AA的聚集反应有缺陷，TXA(2)受体对U46619的亲和力正常，U46619刺激对GTPase活性的诱导正常。然而，在U46619刺激下，肌醇1,4,5-三磷酸（IP3）的产生仅增加到对照组的30%，这表明磷脂酶c - β 2 （PLCB2）在TXA(2)受体下游的激活存在缺陷。家族成员PLCB2无突变，但ALOX12存在c.1946A >g （p.Tyr649Cys）杂合突变。受影响成员的血小板ALOX12活性下降到对照组的25-35%。我们的数据强烈表明，杂合的c.1946A > G ALOX12突变是一种致病突变；然而，ALOX12突变在血小板聚集中的发病机制还需要进一步的实验来证实。
The arachidonic acid (AA) cascade plays a significant role in platelet aggregation. AA released from membrane phospholipids is metabolized by cyclooxygenase (COX) pathway to thromboxane A(2) (TXA(2)) or by 12S-lipoxygenase (ALOX12) to 12-hydroperoxyeicosatetraenoic acid (12-HPETE). In contrast to a well-known role of the COX pathway in platelet aggregation, the role of ALOX12 is not well understood. Platelets of ALOX12-deficient mice exhibit increased sensitivity for ADP-induced aggregation. However, recent evidence strongly suggests a significant role of ALOX12 in platelet aggregation and calcium signaling. 12-HPETE potentiates thrombin- and thromboxane-induced platelet aggregation, and calcium signaling. Inhibition experiments of ALOX12 demonstrated decreased platelet aggregation and calcium signaling in stimulated platelets. We studied a family with a dominantly inherited bleeding diathesis using next-generation sequencing analysis. Platelet aggregation studies revealed that the proband's platelets had defective aggregation responses to ADP, TXA(2) mimetic U46619, collagen, and AA, normal affinity of TXA(2) receptor for U46619, and normal induction of GTPase activity upon stimulation with U46619. However, the production of inositol 1,4,5-triphosphate (IP3) was only increased up to 30% of the control upon U46619 stimulation, suggesting a defect in phospholipase C-beta 2 (PLCB2) activation downstream from TXA(2) receptors. Affected family members had no mutation of PLCB2, but had a heterozygous c.1946A > G (p.Tyr649Cys) mutation of ALOX12. ALOX12 activity in platelets from the affected members was decreased to 25-35% of the control. Our data strongly suggested that a heterozygous c.1946A > G ALOX12 mutation was a disease-causing mutation; however, further experiments are required to confirm the pathogenesis of ALOX12 mutation in platelet aggregation.