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Nagase M, Sakamoto M, Amekura S, Akiba S, Kashiba M, Yokoyama K, Yamamoto Y, Fujisawa A. Riboflavin compounds show NAD(P)H dependent quinone oxidoreductase-like quinone reducing activity. J Clin Biochem Nutr 2023; 73:52-60. [PMID: 37534093 PMCID: PMC10390810 DOI: 10.3164/jcbn.22-140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 02/01/2023] [Indexed: 08/04/2023] Open
Abstract
NAD(P)H-dependent quinone oxidoreductase (NQO) is an essential enzyme in living organisms and cells protecting them from oxidative stress. NQO reduces coenzyme Q (CoQ) using NAD(P)H as an electron donor. In the present study, we searched for coenzyme Q10 reducing activity from fractions of gel filtration-fractionated rat liver homogenate. In addition to the large-molecular-weight fraction containing NQO, CoQ10 reducing activity was also detected in a low-molecular-weight fraction. Furthermore, dicumarol, a conventional inhibitor of NQO1 (DT diaphorase), did not inhibit the reduction but quercetin did, suggesting that the activity was not due to NQO1. After further purification, the NADH-dependent CoQ10-reducing compound was identified as riboflavin. Riboflavin is an active substituent of other flavin compounds such as FAD and FMN. These flavin compounds also reduced not only CoQ homologues but also vitamin K homologues in the presence of NADH. The mechanism was speculated to work as follows: NADH reduces flavin compounds to the corresponding reduced forms, and subsequently, the reduced flavin compounds immediately reduce bio-quinones. Furthermore, the flavin-NADH system reduces CoQ10 bound with saposin B, which is believed to function as a CoQ transfer protein in vivo. This flavin-dependent CoQ10 reduction, therefore, may function in aqueous phases such as the cell cytosol and bodily fluids.
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Affiliation(s)
- Midori Nagase
- School of Bioscience and Biotechnology, Tokyo University of Technology, 1404-1 Katakura-cho, Hachioji, Tokyo 192-0982, Japan
| | - Miku Sakamoto
- School of Bioscience and Biotechnology, Tokyo University of Technology, 1404-1 Katakura-cho, Hachioji, Tokyo 192-0982, Japan
| | - Sakiko Amekura
- School of Bioscience and Biotechnology, Tokyo University of Technology, 1404-1 Katakura-cho, Hachioji, Tokyo 192-0982, Japan
| | - Sayaka Akiba
- School of Bioscience and Biotechnology, Tokyo University of Technology, 1404-1 Katakura-cho, Hachioji, Tokyo 192-0982, Japan
| | - Misato Kashiba
- School of Bioscience and Biotechnology, Tokyo University of Technology, 1404-1 Katakura-cho, Hachioji, Tokyo 192-0982, Japan
| | - Kenji Yokoyama
- School of Bioscience and Biotechnology, Tokyo University of Technology, 1404-1 Katakura-cho, Hachioji, Tokyo 192-0982, Japan
| | - Yorihiro Yamamoto
- School of Bioscience and Biotechnology, Tokyo University of Technology, 1404-1 Katakura-cho, Hachioji, Tokyo 192-0982, Japan
| | - Akio Fujisawa
- School of Bioscience and Biotechnology, Tokyo University of Technology, 1404-1 Katakura-cho, Hachioji, Tokyo 192-0982, Japan
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Zhu S, Huang J, Xu R, Wang Y, Wan Y, McNeel R, Parker E, Kolson D, Yam M, Webb B, Zhao C, Sigado J, Du J. Isocitrate dehydrogenase 3b is required for spermiogenesis but dispensable for retinal viability. J Biol Chem 2022; 298:102387. [PMID: 35985423 PMCID: PMC9478456 DOI: 10.1016/j.jbc.2022.102387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 08/08/2022] [Accepted: 08/10/2022] [Indexed: 12/02/2022] Open
Abstract
Isocitrate dehydrogenase 3 (IDH3) is a key enzyme in the mitochondrial tricarboxylic acid (TCA) cycle, which catalyzes the decarboxylation of isocitrate into α-ketoglutarate and concurrently converts NAD+ into NADH. Dysfunction of IDH3B, the β subunit of IDH3, has been previously correlated with retinal degeneration and male infertility in humans, but tissue-specific effects of IDH3 dysfunction are unclear. Here, we generated Idh3b-KO mice and found that IDH3B is essential for IDH3 activity in multiple tissues. We determined that loss of Idh3b in mice causes substantial accumulation of isocitrate and its precursors in the TCA cycle, particularly in the testes, whereas the levels of the downstream metabolites remain unchanged or slightly increased. However, the Idh3b-KO mice did not fully recapitulate the defects observed in humans. Global deletion of Idh3b only causes male infertility but not retinal degeneration in mice. Our investigation showed that loss of Idh3b causes an energetic deficit and disrupts the biogenesis of acrosome and flagellum, resulting in spermiogenesis arrestment in sperm cells. Together, we demonstrate that IDH3B controls its substrate levels in the TCA cycle, and it is required for sperm mitochondrial metabolism and spermiogenesis, highlighting the importance of the tissue-specific function of the ubiquitous TCA cycle.
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Affiliation(s)
- Siyan Zhu
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV 26506; Department of Biochemistry, West Virginia University, Morgantown, WV 26506; Department of Pharmaceutical and Pharmacological Science, West Virginia University, Morgantown, WV 26506
| | - Jiancheng Huang
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV 26506; Department of Biochemistry, West Virginia University, Morgantown, WV 26506; Eye Institute, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China; NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences, and Shanghai Key Laboratory of Visual Impairment and Restoration (Fudan University), Shanghai, China
| | - Rong Xu
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV 26506; Department of Biochemistry, West Virginia University, Morgantown, WV 26506
| | - Yekai Wang
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV 26506; Department of Biochemistry, West Virginia University, Morgantown, WV 26506
| | - Yiming Wan
- Department of Biomedical Engineering Department, Stony Brook University, Stony Brook, NY 11794
| | - Rachel McNeel
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV 26506; Department of Biochemistry, West Virginia University, Morgantown, WV 26506
| | - Edward Parker
- Department of Ophthalmology, University of Washington, Seattle, WA 98109
| | - Douglas Kolson
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV 26506
| | - Michelle Yam
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV 26506; Department of Biochemistry, West Virginia University, Morgantown, WV 26506
| | - Bradley Webb
- Department of Biochemistry, West Virginia University, Morgantown, WV 26506
| | - Chen Zhao
- Eye Institute, Eye & ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China; NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences, and Shanghai Key Laboratory of Visual Impairment and Restoration (Fudan University), Shanghai, China
| | - Jenna Sigado
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV 26506; Department of Biochemistry, West Virginia University, Morgantown, WV 26506
| | - Jianhai Du
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV 26506; Department of Biochemistry, West Virginia University, Morgantown, WV 26506.
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