Identification and developmental expression of the full complement of Cytochrome P450 genes in Zebrafish

Abstract

BackgroundIncreasing use of zebrafish in drug discovery and mechanistic toxicology demands knowledge of cytochrome P450 (CYP) gene regulation and function. CYP enzymes catalyze oxidative transformation leading to activation or inactivation of many endogenous and exogenous chemicals, with consequences for normal physiology and disease processes. Many CYPs potentially have roles in developmental specification, and many chemicals that cause developmental abnormalities are substrates for CYPs. Here we identify and annotate the full suite of CYP genes in zebrafish, compare these to the human CYP gene complement, and determine the expression of CYP genes during normal development.ResultsZebrafish have a total of 94 CYP genes, distributed among 18 gene families found also in mammals. There are 32 genes in CYP families 5 to 51, most of which are direct orthologs of human CYPs that are involved in endogenous functions including synthesis or inactivation of regulatory molecules. The high degree of sequence similarity suggests conservation of enzyme activities for these CYPs, confirmed in reports for some steroidogenic enzymes (e.g. CYP19, aromatase; CYP11A, P450scc; CYP17, steroid 17a-hydroxylase), and the CYP26 retinoic acid hydroxylases. Complexity is much greater in gene families 1, 2, and 3, which include CYPs prominent in metabolism of drugs and pollutants, as well as of endogenous substrates. There are orthologous relationships for some CYP1 s and some CYP3 s between zebrafish and human. In contrast, zebrafish have 47 CYP2 genes, compared to 16 in human, with only two (CYP2R1 and CYP2U1) recognized as orthologous based on sequence. Analysis of shared synteny identified CYP2 gene clusters evolutionarily related to mammalian CYP2 s, as well as unique clusters.ConclusionsTranscript profiling by microarray and quantitative PCR revealed that the majority of zebrafish CYP genes are expressed in embryos, with waves of expression of different sets of genes over the course of development. Transcripts of some CYP occur also in oocytes. The results provide a foundation for the use of zebrafish as a model in toxicological, pharmacological and chemical disease research.

Hepatotoxicity by Acetaminophen and Amiodarone in Zebrafish Embryos

“…Transcript profiling by microarray and quantitative polymerase chain reactions have revealed that 94 zebrafish CYP genes, most of which are direct orthologs of human CYPs, are expressed in embryos during various time courses associated with development has further investigated the expression of several xenobiotic metabolizing genes similar to human (e.g., CYP1A, CYP2B6, CYP3A5, and UGT1A1) and functional metabolizing capacity using several classic CYP substrates over a time course of early development (i.e., from 24 to 96 hpf ). 2,8,9 Zebrafish has more relevance with a human which predicts the actual effects of chemical which deal with other mammalian models in rest of the assays. But many CYP enzymes behave differently in each mammalian model which acquires the usage of various genetic assessment techniques.…”

Highly potent visnagin derivatives inhibit Cyp1 and prevent doxorubicin cardiotoxicity

“…Human and mouse CYP1 enzymes are divided into 2 subfamilies: 1A1/1A2 and 1B1. Zebrafish CYP1 enzymes are divided into 4 subfamilies, 2 of which are homologous to those found in mammalian species: 1A, 1B1, 1C1/1C2 (may complement 1B1 activity in fish), and 1D1 (pseudogene in humans) (30). Although our initial genetic knockdown model suggests that Cyp1a is necessary for the development of cardiotoxicity, future studies will focus on the development of stable transgenic lines in zebrafish to address the role of each CYP1 family member and identify potential downstream metabolites that may contribute to the pathogenesis of DOX-induced cardiotoxicity.…”

Comparative Pharmacology and Toxicology of Pharmaceuticals in the Environment: Diphenhydramine Protection of Diazinon Toxicity in Danio rerio but Not Daphnia magna

“…This increase in sensitivity following DZN exposure is linked to rational molecular design of second generation OPs insecticides wherein metabolism to a more toxic oxon metabolite is responsible for elevated AChEI and thus toxicity. Biotransformation to the oxon metabolite of DZN occurs by cytochrome (CYP) P450 enzyme oxidation, yet expression and activity of CYP enzyme isoforms fluctuate in intensity and location over development (53)(54)(55). Additionally, an understanding of pharmaceutical metabolism in fish species is lacking (15,56,57); although some mammalian homologues have been identified, functional conservation has not yet been established for most CYPs (56).…”