title: A novel cytochrome P450, zebrafish Cyp26D1, is involved in metabolism of all-trans retinoic acid.
abstract: Retinoid signaling is essential for development of vertebrate embryos, and its action is mainly through retinoic acid (RA) binding to its RA receptors and retinoid-X receptors, while the critical concentration and localization of RA in embryos are determined by the presence and activity of retinal dehydrogenases (for RA synthesis) and cytochrome P450 RAs (Cyp26s) (for degradation of RA). Previously, we identified a novel cyp26 gene (cyp26d1) in zebrafish that is expressed in hindbrain during early development. Using reverse-phase HPLC analyses, we show here that zebrafish Cyp26D1 expressed in 293T cells could metabolize all-trans RA, 9-cis RA, and 13-cis RA, but could not metabolize retinol or retinal. The metabolites of all-trans RA produced by Cyp26D1 were the same as that produced by Cyp26A1, which are mainly 4-hydroxy-all-trans-RA and 4-oxo-all-trans-RA. Performing mRNA microinjection into zebrafish embryos, we demonstrated that overexpression of Cyp26D1 in embryos not only caused the distance between rhombomere 5 and the first somite of the injected embryos to be shorter than control embryos but also resulted in left-right asymmetry of somitogenesis in the injected embryos. These alterations were similar to those caused by the overexpression of cyp26a1 in zebrafish embryos and to that which resulted from treating embryos with 1 microm 4-diethylamino-benzaldehyde (retinal dehydrogenase inhibitor), implying that cyp26d1 can antagonize RA activity in vivo. Together, our in vitro and in vivo results provided direct evidence that zebrafish Cyp26D1 is involved in RA metabolism.
authors.affiliation: Model Animal Research Center and State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Pukou District, Nanjing 210061, China.
authors.forename: Xingxing
authors.initials: X
authors.lastname: Gu
authors.forename: Fang
authors.initials: F
authors.lastname: Xu
authors.forename: Wei
authors.initials: W
authors.lastname: Song
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Wang
authors.forename: Ping
authors.initials: P
authors.lastname: Hu
authors.forename: Yumin
authors.initials: Y
authors.lastname: Yang
authors.forename: Xiang
authors.initials: X
authors.lastname: Gao
authors.forename: Qingshun
authors.initials: Q
authors.lastname: Zhao
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017124:Conserved Sequence; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000378:metabolism; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D012172:Retinaldehyde / Q000378:metabolism; D000072516:Retinoic Acid 4-Hydroxylase; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D014018:Tissue Distribution / Q000235:genetics; D014212:Tretinoin / Q000031:analogs & derivatives / Q000378:metabolism*; D014801:Vitamin A / Q000378:metabolism; D029961:Zebrafish Proteins / Q000378:metabolism*
chemical_list: D029961:Zebrafish Proteins; D014801:Vitamin A; C002202:4-oxoretinoic acid; D014212:Tretinoin; C019429:4-hydroxyretinoic acid; D003577:Cytochrome P-450 Enzyme System; C513559:cytochrome P-450 26D1, zebrafish; D000072516:Retinoic Acid 4-Hydroxylase; C000607085:cyp26a1 protein, zebrafish; D012172:Retinaldehyde