Abstract
Phosphine (PH3) is a toxin commonly used for pest control. Its toxicity is attributed primarily to its ability to induce oxidative damage. Our previous work showed that phosphine could disrupt the cell antioxidant defence system by inhibiting expression of the catalase gene in Drosophila melanogaster (DmCAT). However, the exact mechanism of this inhibition remains unclear. Here, we implemented a luciferase reporter assay driven by the DmCAT promoter in D. melanogaster S2 cells and showed that this reporter could be inhibited by phosphine treatment. A minimal fragment of the promoter (-94 to 0 bp), which contained a DNA replication-related element (DRE) consensus motif (-78 to -85 bp), was sufficient for phosphine-mediated reporter inhibition, suggesting the involvement of the transcription factor DREF. Furthermore, phosphine treatment led to a reduction in DREF expression and consequent repression of DmCAT transcription. Our results provide new insights on the molecular mechanism of phosphine-mediated catalase inhibition. Phosphine treatment leads to reduced levels of the transcription factor DREF, a positive regulator of the DmCAT gene, thereby resulting in the repression of DmCAT at transcriptional level.