Tuesday, 19 November 2002

This presentation is part of : Display Presentations, Section B. Physiology, Biochemistry, Toxicology, and Molecular Biology

Conserved response element in the promoter of a substrate-inducible cytochrome P450 genes

Cynthia M. McDonnell1, Rebecca A. Petersen1, May R. Berenbaum1, and Mary A. Schuler2. (1) University of Illinois at Urbana-Champaign, Department of Entomology, 320 Morrill Hall, 505 S. Goodwin Ave, Urbana, IL, (2) University of Illinois at Urbana-Champaign, Cell & Structural Biology, 161 Edward R. Madigan Laboratory, 1201 W. Gregory Ave, Urbana, IL

Xanthotoxin, a linear furanocoumarin in the hostplants of the caterpillar Papilio polyxenes, activates transcription of the cytochrome P450 gene, CYP6B1, via a xenobiotic response element (XRE-Xan) in its promoter. XRE-AhR, a response element first identified in the mammalian xenobiotic response cascade, also resides in the promoter of CYP6B1 but its function is unknown. In mammals, XRE-AhR is activated by the heterodimer-forming proteins, AhR and ARNT. In Drosophila melanogaster, homologous proteins, spineless (Ss) with tango (Tgo) and single-minded (Sim) with Tgo, activate genes in the developmental regulatory cascade via two similar elements, XRE-AhR and CME, respectively. To determine if XRE-AhR acts in the regulation of CYP6B1, combinations of ss/tgo and sim/tgo expressible plasmids were cotransfected with a CYP6B1 promoter:CAT reporter plasmid into insect Sf9 cells. Treatment of the transfected cells with xanthotoxin in methanol (1 ug/ul) and methanol alone indicated that coexpression of the Ss and Tgo proteins significantly increased both constitutive and xanthotoxin-induced CAT activity above that detected in cells transfected with the CYP6B1:CAT construct alone. Coexpression of Sim and Tgo proteins demonstrated a more limited ability to increase CAT activity. These results parallel previous experiments in Drosophila indicating that the Ss/Tgo heterodimer binds XRE-AhR with greater efficiency than the Sim/Tgo heterodimer. Activation of detoxification genes by binding proteins involved in regulation of insect developmental genes suggests a common ancestor for both pathways co-opted for multiple functions.

Species 1: Lepidoptera Papilionidae Papilio polyxenes (black swallowtail)
Species 2: Diptera Drosophilidae Drosophila melanogaster (fruit fly)
Keywords: transcriptional regulation, aryl hydrocarbon

Back to Display Presentations, Section B. Physiology, Biochemistry, Toxicology, and Molecular Biology
Back to Posters
Back to The 2002 ESA Annual Meeting and Exhibition