The Arg98Trp mutation in human VKORC1 causing VKCFD2 disrupts a di-arginine-based ER retention motif
The Arg98Trp mutation in human VKORC1 causing VKCFD2 disrupts a di-arginine-based ER retention motif
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DOI：
10.1182/blood-2013-12-545988
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发表时间：
2014-08-21
期刊：
影响因子：
20.3
通讯作者：
Oldenburg, Johannes
中科院分区：
文献类型：
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作者：
Czogalla, Katrin J.;Biswas, Arijit;Oldenburg, Johannes
维生素K 2，3-环氧化物还原酶复合体1(VKORC1)是一种定位于内质网(ER)膜上的酶。VKORC1催化维生素K 2，3-环氧化物还原为维生素K和维生素K对苯二酚，后者是所有维生素K依赖(VKD)蛋白质的伽玛-羧基酶所必需的。到目前为止，只有1个人类VKORC1突变，p.Arg98Trp，已知会导致VKD凝血因子2型联合缺乏症(VKCFD2)，这是一种在3个无关家系中报道的疾病表型。VKCFD2患者由于伽玛-羧化VKD凝血因子水平降低而出现自发性出血发作。每天补充超生理维生素K可以恢复VKCFD2患者的凝血，并导致血清中维生素K2，3-环氧化物水平升高，这表明补充的维生素K在体内是减少的。虽然p.Arg98Trp突变导致维生素K2，3-环氧化物还原酶活性降低，但这种病理生理的分子机制尚不清楚。使用原位电子显微镜分析和共聚焦显微镜相结合的方法，我们首次证明了VKORC1：P.Arg98Trp破坏了二精氨酸ER保留基序，导致20%的ER共定位。因此，VKORC1通过细胞质量控制系统退出ER膜，并导致观察到的VKCFD2表型。
Vitamin K 2,3-epoxide reductase complex subunit 1 (VKORC1) is an enzyme localized to the endoplasmic reticulum (ER) membrane. VKORC1 catalyzes the reduction of vitamin K 2,3-epoxide to vitamin K and to vitamin K hydroquinone, the latter required by the enzyme gamma-carboxylase for gamma-carboxylation of all vitamin K-dependent (VKD) proteins. Until now, only 1 human VKORC1 mutation, p.Arg98Trp, is known to cause combined deficiency of VKD clotting factors type 2 (VKCFD2), a disease phenotype reported in 3 unrelated families. VKCFD2 patients suffer from spontaneous bleeding episodes because of decreased levels of gamma-carboxylated VKD clotting factors. Daily supraphysiological vitamin K supplementation restores clotting for VKCFD2 patients and results in high serum levels of vitamin K 2,3-epoxide, suggesting that supplemented vitamin K is reduced in vivo. Although the p. Arg98Trp mutation results in reduced vitamin K 2,3-epoxide reductase activity, the molecular mechanism underlying this pathophysiology is unknown. Using a combination of in silico analysis and confocal microscopy, we demonstrate for the first time that VKORC1: p. Arg98Trp disrupts a di-arginine ER retention motif resulting in 20% ER colocalization only. As a consequence, VKORC1 exits the ER membrane by cellular quality control systems and results in the observed VKCFD2 phenotype.