Involvement of AhR/ARNT in tolerance to deltamethrin by regulating the expression of TcGSTs6 in Tribolium castaneum.

It is well known that the transcription factors aryl hydrocarbon receptor (AhR) and aryl hydrocarbon receptor nuclear translocator (ARNT) play important roles in the detoxification of xenobiotic compounds including insecticides. In this study, TcAhR and TcARNT were cloned from Tribolium castaneum. RT-qPCR analysis revealed that TcAhR and TcARNT were highly expressed in brain and epidermis of female adults and upregulated after exposure of the adults to deltamethrin. Knockdown of TcAhR and TcARNT increased the susceptibility of T. castaneum to deltamethrin and decreased the enzymatic activity of Glutathione S-transferase (GST). Consistently, knockdown of TcAhR and TcARNT led to the downregulation of TcGSTs6 and suppressed the induction of TcGSTs6 by deltamethrin treatment. Increased susceptibility of T. castaneum to deltamethrin was also observed after knockdown of TcGSTs6. Further dual-luciferase reporter assay revealed that co-overexpression of TcAhR and TcARNT in Sf9 cells significantly enhanced the promoter activity of TcGSTs6. These results provided insights into the function of insect AhR and ARNT as well as the regulatory mechanisms of insect GSTs.