ORCID Profile
0000-0001-8459-2557
Current Organisations
Beijing Normal University
,
University of North Carolina at Chapel Hill
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Publisher: Springer Science and Business Media LLC
Date: 14-02-2023
DOI: 10.1038/S41467-023-36446-8
Abstract: 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.
Publisher: Wiley
Date: 12-2021
DOI: 10.1111/FEBS.16291
Abstract: UbiA prenyltransferase domain‐containing protein‐1 (UBIAD1) is responsible for the biosynthesis of menaquinone‐4 (MK‐4), a cofactor for extrahepatic carboxylation of vitamin K‐dependent (VKD) proteins. Genetic variations of UBIAD1 are mainly associated with Schnyder corneal dystrophy (SCD), a disease characterized by abnormal accumulation of cholesterol in the cornea. Results from in vitro studies demonstrate that SCD‐associated UBIAD1 mutations are defective in MK‐4 biosynthesis. However, SCD patients do not exhibit typical phenotypes associated with defects of MK‐4 or VKD carboxylation. Here, we coupled UBIAD1’s biosynthetic activity of MK‐4 with VKD carboxylation in HEK293 cells that stably express a chimeric VKD reporter protein. The endogenous Ubiad1 gene in these cells was knocked out by CRISPR‐Cas9‐mediated genome editing. The effect of UBIAD1 mutations on MK‐4 biosynthesis and VKD carboxylation was evaluated in Ubiad1 ‐deficient reporter cells by determining the production of MK‐4 or by measuring the efficiency of reporter‐protein carboxylation. Our results show that the hot‐spot mutation N102S has a moderate impact on MK‐4 biosynthesis (retained ˜ 82% activity) but does not affect VKD carboxylation. However, the G186R mutation significantly affected both MK‐4 biosynthesis and VKD carboxylation. Other mutations exhibit varying degrees of effects on MK‐4 biosynthesis and VKD carboxylation. These results are consistent with in vivo results obtained from gene knock‐in mice and SCD patients. Our findings suggest that UBIAD1’s MK‐4 biosynthetic activity does not directly correlate with the phenotypes of SCD patients. The established cell‐based assays in this study provide a powerful tool for the functional studies of UBIAD1 in a cellular milieu.
Publisher: Elsevier BV
Date: 08-2019
Publisher: Wiley
Date: 25-01-2019
Publisher: Elsevier BV
Date: 03-2021
DOI: 10.1111/JTH.15209
Location: United States of America
No related grants have been discovered for Xuejie Chen.