CYP3C1, the first member of a new cytochrome P450 subfamily found in zebrafish (Danio rerio)

We report a new cytochrome P450 (CYP) subfamily CYP3C and the cloning through PCR from zebrafish (Danio rerio) of the first member, CYP3C1 (AY499002). The CYP3C1 gene is on Chromosome 3 with 13 ORF exons encoding a 505 amino acid protein which has 44–54% identities with mammalian and teleost CYP3A and CYP3B forms. As evidenced by spectral analysis, the CYP3C1 protein heterologously expressed in yeast is functional. In silico analysis identified, on the same region of the chromosome, three more genes encoding CYP3C1-like proteins that formed a clade with CYP3C1 in a phylogenetic tree. Using RT-PCR, the CYP3C1 mRNA was detected in 1–6 dpf embryo/larvae and in adult fish liver and seven extrahepatic tissues. Whole-mount in situ hybridization using a riboprobe demonstrated expression in the brain during 12–120 hpf. At the 120 hpf larval stage, CYP3C1 mRNA was also detected in the pharynx and gastrointestinal tract. TCDD, dexamethasone, and rifampicin, which up-regulated CYP3A65 mRNA in zebrafish larvae, did not alter the CYP3C1 transcript levels suggesting regulatory differences between CYP3A and CYP3C enzymes in this species.