title: Nrf2/Maf-binding-site-containing functional Cyp6a2 allele is associated with DDT resistance in Drosophila melanogaster.
abstract: BACKGROUND
  Increased insecticide detoxification mediated by cytochrome P450s is a common mechanism of insecticide resistance. Although Cyp6a2 has been observed to be overexpressed in many 4,4'-dichlorodiphenyltrichloroethane (DDT)-resistant strains of Drosophila melanogaster, how Cyp6a2 is regulated and whether its overproduction confers DDT resistance remain elusive.
  
  
  RESULTS
  Molecular analysis identified five Cyp6a2 alleles (Cyp6a2(Canton) (-S-1) , Cyp6a2(Canton) (-S-2) , Cyp6a2(91-C) , Cyp6a2(91-R) and Cyp6a2(Wisconsin) (-) (WD) ) from four D. melanogaster strains, notably differing in the presence or absence of an intact Nrf2/Maf (a transcription factor) binding site in the 5'-promoter core region, a 'G1410' frameshift deletion mutation in the heme-binding region and a long terminal repeat (LTR) of transposable element 17.6 in the 3'-untranslated region (UTR). Linkage analysis confirmed that DDT resistance was genetically linked to a Nrf2/Maf-binding-site-containing, LTR-lacking functional allele of Cyp6a2 (Cyp6a2(91-R) ). The qRT-PCR results showed that overexpression of functional Cyp6a2 was consistently associated with DDT resistance. Luciferase reporter gene assays revealed that an intact Nrf2/Maf binding site in the 5'-promoter core region enhanced the constitutive transcription of Cyp6a2.
  
  
  CONCLUSIONS
  The results suggest that the Nrf2/Maf binding-site-containing functional Cyp6a2 allele is associated with DDT resistance in the D. melanogaster strains under study.
authors.affiliation: State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Wan
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.forename: Mei
authors.initials: M
authors.lastname: Li
authors.forename: Shunyi
authors.initials: S
authors.lastname: Zhu
authors.forename: Xianchun
authors.initials: X
authors.lastname: Li
authors.forename: Barry R
authors.initials: BR
authors.lastname: Pittendrigh
authors.forename: Xinghui
authors.initials: X
authors.lastname: Qiu
mesh_terms: D000818:Animals; D001483:Base Sequence; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics* / Q000378:metabolism; D000072472:Cytochrome P450 Family 6; D003634:DDT / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism; D004331:Drosophila melanogaster / Q000235:genetics* / Q000378:metabolism; D005260:Female; D007305:Insecticide Resistance / Q000235:genetics*; D007306:Insecticides / Q000378:metabolism*; D050977:Maf Transcription Factors / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D060888:Real-Time Polymerase Chain Reaction; D016415:Sequence Alignment
chemical_list: D029721:Drosophila Proteins; D007306:Insecticides; D050977:Maf Transcription Factors; D003577:Cytochrome P-450 Enzyme System; D003634:DDT; C109499:Cyp6a2 protein, Drosophila; D000072472:Cytochrome P450 Family 6
keywords: Cyp6a2; DDT resistance; Nrf2/Maf binding site; frameshift mutation; long terminal repeat; overexpression