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Furukawa F, Aoyagi A, Sano K, Sameshima K, Goto M, Tseng YC, Ikeda D, Lin CC, Uchida K, Okumura SI, Yasumoto K, Jimbo M, Hwang PP. Gluconeogenesis in the extraembryonic yolk syncytial layer of the zebrafish embryo. PNAS Nexus 2024; 3:pgae125. [PMID: 38585339 PMCID: PMC10997050 DOI: 10.1093/pnasnexus/pgae125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 03/11/2024] [Indexed: 04/09/2024]
Abstract
Yolk-consuming (lecithotrophic) embryos of oviparous animals, such as those of fish, need to make do with the maternally derived yolk. However, in many cases, yolk possesses little carbohydrates and sugars, including glucose, the essential monosaccharide. Interestingly, increases in the glucose content were found in embryos of some teleost fishes; however, the origin of this glucose has been unknown. Unveiling new metabolic strategies in fish embryos has a potential for better aquaculture technologies. In the present study, using zebrafish, we assessed how these embryos obtain the glucose. We employed stable isotope (13C)-labeled substrates and injected them to the zebrafish embryos. Our liquid chromatography-mass spectrometry-based isotope tracking revealed that among all tested substrate, glutamate was most actively metabolized to produce glucose in the zebrafish embryos. Expression analysis for gluconeogenic genes found that many of these were expressed in the yolk syncytial layer (YSL), an extraembryonic tissue found in teleost fishes. Generation 0 (G0) knockout of pck2, a gene encoding the key enzyme for gluconeogenesis from Krebs cycle intermediates, reduced gluconeogenesis from glutamate, suggesting that this gene is responsible for gluconeogenesis from glutamate in the zebrafish embryos. These results showed that teleost YSL undergoes gluconeogenesis, likely contributing to the glucose supplementation to the embryos with limited glucose source. Since many other animal lineages lack YSL, further comparative analysis will be interesting.
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Affiliation(s)
- Fumiya Furukawa
- School of Marine Biosciences, Kitasato University, 1-15-1 Kitazato, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan
- Institute of Cellular and Organismic Biology, Academia Sinica, No. 128, Sec. 2, Nankang, Taipei 11529, Taiwan ROC
| | - Akihiro Aoyagi
- School of Marine Biosciences, Kitasato University, 1-15-1 Kitazato, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan
| | - Kaori Sano
- Department of Chemistry, Faculty of Science, Josai University, 1-1 Keyakidai, Sakado, Saitama 350-0295, Japan
| | - Keita Sameshima
- School of Marine Biosciences, Kitasato University, 1-15-1 Kitazato, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan
| | - Miku Goto
- School of Marine Biosciences, Kitasato University, 1-15-1 Kitazato, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan
| | - Yung-Che Tseng
- Institute of Cellular and Organismic Biology, Academia Sinica, No. 128, Sec. 2, Nankang, Taipei 11529, Taiwan ROC
| | - Daisuke Ikeda
- School of Marine Biosciences, Kitasato University, 1-15-1 Kitazato, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan
| | - Ching-Chun Lin
- Institute of Cellular and Organismic Biology, Academia Sinica, No. 128, Sec. 2, Nankang, Taipei 11529, Taiwan ROC
| | - Katsuhisa Uchida
- Department of Marine Biology and Environmental Sciences, Faculty of Agriculture, University of Miyazaki, 1-1 Gakuen Kibanadai-Nishi, Miyazaki 889-2192, Japan
| | - Sei-ichi Okumura
- School of Marine Biosciences, Kitasato University, 1-15-1 Kitazato, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan
| | - Ko Yasumoto
- School of Marine Biosciences, Kitasato University, 1-15-1 Kitazato, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan
| | - Mitsuru Jimbo
- School of Marine Biosciences, Kitasato University, 1-15-1 Kitazato, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan
| | - Pung-Pung Hwang
- Institute of Cellular and Organismic Biology, Academia Sinica, No. 128, Sec. 2, Nankang, Taipei 11529, Taiwan ROC
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