Characterization of a novel pesticide transporter and P-glycoprotein orthologues in <i>Drosophila melanogaster</i>

Abstract

Pesticides remain one of the most effective ways of controlling agricultural and public health insects, but much is still unknown regarding how these compounds reach their targets. Specifically, the role of ABC transporters in pesticide absorption and excretion is poorly understood, especially compared to the detailed knowledge about mammalian systems. Here, we present a comprehensive characterization of pesticide transporters in the model insect <i>Drosophila melanogaster</i>. An RNAi screen was performed, which knocked down individual ABCs in specific epithelial tissues and examined the subsequent changes in sensitivity to the pesticides spinosad and fipronil. This implicated a novel ABC drug transporter, <i>CG4562,</i> in spinosad transport, but also highlighted the P-glycoprotein orthologue <i>Mdr65</i> as the most impactful ABC in terms of chemoprotection. Further characterization of the P-glycoprotein family was performed via transgenic overexpression and immunolocalization, finding that <i>Mdr49</i> and <i>Mdr50</i> play enigmatic roles in pesticide toxicology perhaps determined by their different subcellular localizations within the midgut. Lastly, transgenic <i>Drosophila</i> lines expressing P-glycoprotein from the major malaria vector <i>Anopheles gambiae</i> were used to establish a system for <i>in vivo</i> characterization of this transporter in non-model insects. This study provides the basis for establishing <i>Drosophila</i> as a model for toxicology research on drug transporters.