tailieunhanh - Báo cáo khoa học: Characterization and cDNA cloning of a clofibrate-inducible microsomal epoxide hydrolase in Drosophila melanogaster

In order to understand the roles of the epoxide hydrolases (EHs) in xenobiotic biotransformation in insects, we exam-ined the induction of EHs by exogenous compounds in Drosophila melangasterthird instar larvae. Among the chemicals tested, clofibrate, a phenoxyacetate hypolipider-mics drug, increased EH activity towardscis-stilbene oxide approximately twofold in larval whole-body homogenates. The same dose of clofibrate also induced glutathione S-transferase activity. | Eur. J. Biochem. 270 4696-4705 2003 FEBS 2003 doi Characterization and cDNA cloning of a clofibrate-inducible microsomal epoxide hydrolase in Drosophila melanogaster Kiyoko Taniai1 Ahmet B. Inceoglu2 Kenji Yukuhiro3 and Bruce D. Hammock2 1Insect Biotechnology and Sericology Department National Institute of Agrobiological Sciences Tsukuba Japan department of Entomology and Cancer Research Center University of California Davis CA USA 3Insect Genetics and Evolution Department National Institute of Agrobiological Sciences Tsukuba Japan In order to understand the roles of the epoxide hydrolases EHs in xenobiotic biotransformation in insects we examined the induction of EHs by exogenous compounds in Drosophila melangaster third instar larvae. Among the chemicals tested clofibrate a phenoxyacetate hypolipider-mics drug increased EH activity towards cis-stilbene oxide approximately twofold in larval whole-body homogenates. The same dose of clofibrate also induced glutathione S-transferase activity. The effect of clofibrate on EH induction was dose-dependent and the highest activity occurred with a 10 clofibrate application. Three other substrates conventionally used in EH assays trans-stilbene oxide trans-diphenylpropene oxide and juvenile hormone III were poorly hydrolysed by larval homogenates with or without clofibrate administration. Because the increased EH activity was localized predominantly in the microsomal fraction we synthesized degenerate oligonucleotide primers with sequences corresponding to conserved regions of known microsome EHs from mammals and insects in order to isolate the gene. The 1597 bp putative cDNA of D. melano-gaster microsomal EH DmEH obtained from a larval cDNA library encoded 463 amino acids in an open reading frame. Northern blot analysis showed that the transcription of DmEH was increased in larvae within 5 h of clofibrate treatment. Recombinant DmEH expressed in baculovirus hydrolysed cis-stilbene oxide 23