Vitamin K is a vital micronutrient implicated in a variety of human diseases. Warfarin, a vitamin K antagonist, is the most commonly prescribed oral anticoagulant. Patients overdosed on warfarin can be rescued by administering high doses of vitamin K because of the existence of a warfarin-resistant vitamin K reductase. Despite the functional discovery of vitamin K reductase over eight decades ago, its identity remained elusive. Here, we report the identification of warfarin-resistant vitamin K reductase using a genome-wide CRISPR-Cas9 knockout screen with a vitamin K-dependent apoptotic reporter cell line. We find that ferroptosis suppressor protein 1 (FSP1), a ubiquinone oxidoreductase, is the enzyme responsible for vitamin K reduction in a warfarin-resistant manner, consistent with a recent discovery by Mishima et al. FSP1 inhibitor that inhibited ubiquinone reduction and thus triggered cancer cell ferroptosis, displays strong inhibition of vitamin K-dependent carboxylation. Intriguingly, dihydroorotate dehydrogenase, another ubiquinone-associated ferroptosis suppressor protein parallel to the function of FSP1, does not support vitamin K-dependent carboxylation. These findings provide new insights into selectively controlling the physiological and pathological processes involving electron transfers mediated by vitamin K and ubiquinone.
维生素K是一种重要的微量营养素,与多种人类疾病有关。华法林是最常被开具的口服抗凝药物,它是一种维生素K拮抗剂。因为存在一种抗华法林的维生素K还原酶,过量服用华法林的患者可以通过注射高剂量的维生素K来挽救。尽管维生素K还原酶的功能发现已经有八十多年的历史,但其身份仍然难以确定。在这里,我们报告了使用基因组范围的CRISPR-Cas9敲除筛选和一种维生素K依赖性的细胞凋亡报告基因株,鉴定了抗华法林的维生素K还原酶。我们发现铁死亡抑制蛋白1(FSP1),一种泛醌氧还蛋白,是负责以抗华法林的方式还原维生素K的酶,与Mishima等人最近的发现一致。抑制FSP1的抑制剂抑制泛醌还原,从而引发癌细胞的铁死亡,同时也强烈抑制维生素K依赖性的羧化。有趣的是,另一种与泛醌相关的铁死亡抑制蛋白——二氢乳酸脱氢酶,并不支持维生素K依赖性的羧化。这些发现为有选择地控制由维生素K和泛醌介导的电子转移所涉及的生理和病理过程提供了新的见解。