title: Role of the transcriptional repressor mdGfi-1 in CYP6D1v1-mediated insecticide resistance in the house fly, Musca domestica.
abstract: Gfi-1 is a C(2)H(2)-type zinc finger protein that is a transcriptional repressor in vertebrates and has been implicated in control of CYP6D1 expression in house flies (Musca domestica). A 15 bp insert, which disrupts a putative mdGfi-1 binding site in the CYP6D1v1 promoter has been implicated as a cause of increased expression of CYP6D1, and thus insecticide resistance. Using electrophoretic mobility shift assays we demonstrate that the CYP6D1 promoter from susceptible strains binds mdGfi-1. The 15 bp insert that interrupts the mdGfi-1-binding site in insecticide-resistant strains reduces the amount of mdGfi-1 binding by 9- to 20-fold, consistent with the role of mdGfi-1 in resistance. Partial sequences of mdGfi-1 (spanning the first intron) from individual houseflies from 11 different strains revealed the presence of 23 alleles. There was no consistent difference in the mdGfi-1 alleles between susceptible and CYP6D1-mediated insecticide-resistant strains, indicating that mdGfi-1 alleles were not likely involved in resistance. Polymorphisms were used to map mdGfi-1 to autosome 1. Quantitative real time PCR (qRT-PCR) revealed Gfi-1 expression was higher in the thorax compared to the head and abdomen, and varied between life stages and between strains. However, similar levels of mdGfi-1 were detected in susceptible and resistant adults suggesting that altered levels of mdGfi-1 were not likely a cause of insecticide resistance. The significance of these results to understanding insecticide resistance is discussed.
authors.affiliation: Department of Entomology, Comstock Hall, Cornell University, Ithaca, NY 14853-0901, USA.
authors.forename: Jianwei
authors.initials: J
authors.lastname: Gao
authors.forename: Jeffrey G
authors.initials: JG
authors.lastname: Scott
mesh_terms: D000483:Alleles; D000818:Animals; D002874:Chromosome Mapping; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics* / Q000378:metabolism; D000072472:Cytochrome P450 Family 6; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation; D008040:Genetic Linkage; D006793:Houseflies / Q000187:drug effects* / Q000235:genetics* / Q000378:metabolism; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D007305:Insecticide Resistance / Q000235:genetics*; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D017422:Sequence Analysis, DNA
chemical_list: D019476:Insect Proteins; D012097:Repressor Proteins; D003577:Cytochrome P-450 Enzyme System; C092307:CYP6D1 protein, Musca domestica; D000072472:Cytochrome P450 Family 6