Abstract
Piperonyl butoxide (PBO) is a commonly used insecticide synergist and cytochrome P450 (CYP) inhibitor. While its role in blocking xenobiotic metabolism is well established, we show here that PBO also triggers a unique transcriptional response in Drosophila melanogaster. This response includes genes classically associated with detoxification, such as Cyps, Gsts, and Ugts, as well as genes involved in lipid metabolism, revealing a novel physiological program that integrates detoxification with broader metabolic regulation. Unlike other xenobiotic exposures, the PBO-induced transcriptome does not resemble a classical stress response. This transcriptional induction is independent of genetic background, diet composition or microbiota, and is partially recapitulated by myristicin, another methylenedioxyphenyl compound. Fine-scale dissection combined with RT-qPCR reveals that PBO-inducible genes exhibit distinct spatial expression patterns across multiple tissues, including the gut, Malpighian tubules, and fat body. Although most PBO inducible genes show the highest basal expression in the digestive tract, approximately half are primarily induced in the digestive tract, whereas the others are predominantly induced in the fat body of the carcass. Using CRISPR-Mediated Integration Cassette Gal4 reporter lines, we visualized the cell-specific expression of two PBO-induced Cyps, Cyp4e2 and Cyp28a5, which display complementary and regionally restricted activation in the gut and carcass. We find that patterns of expression are maintained during induction by PBO. Our findings suggest that CYP inhibition by PBO triggers a novel, systemic transcriptional response that extends beyond xenobiotic detoxification and may reflect a broader disruption of metabolic homeostasis.
