Post-transcriptional modulation of cytochrome P450s, Cyp6g1 and Cyp6g2, by miR-310s cluster is associated with DDT-resistant Drosophila melanogaster strain 91-R

Authors: SEONG, KEON MOOK - Michigan State University; Coates, Brad; PITTENDRIGH, BARRY - Michigan State University

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/10/2020
Publication Date: 9/1/2020
Citation: Seong, K., Coates, B.S., Pittendrigh, B.R. 2020. Post-transcriptional modulation of cytochrome P450s, Cyp6g1 and Cyp6g2, by miR-310s cluster is associated with DDT-resistant Drosophila melanogaster strain 91-R. Scientific Reports. 10.Article 14394. https://doi.org/10.1038/s41598-020-71250-0.
DOI: https://doi.org/10.1038/s41598-020-71250-0

Interpretive Summary: The evolution of resistance to chemical insecticides among pest arthropod populations can result in reduced efficacy of control measures used by producers, and cause a subsequent increase in levels of damage to agricultural commodities. These factors in turn lead to lower quantity and quality of agricultural output, as well as reduced producer profitability. An insecticide resistant strain from a model insect species (fruit fly) was used to identify associated genomic changes. This study demonstrated that a class of small cellular RNAs, microRNAs (miRNAs), are important regulators in the expression of genes that the fly utilizes to detoxify chemical insecticides. Specifically, the microinjection of miRNAs into adult flies changed the level of detoxification gene expression and the level of insecticide resistance. Furthermore, cell reporter assays validate computational predictions that miRNAs interact and lead to the degradation of transcripts for a subset of detoxification genes within tissue culture cells. This research demonstrates that microRNAs modify the expression of genes involved in the cellular detoxification of chemical insecticides, and may influence the capacity of resistant flies to detoxify insecticidal compounds. These data are important to university, government and industry scientists interested in determining the basis of insect population responses to control measures, and understanding how insects respond to selection pressure imposed by current insect control technologies will ultimately benefit producers.

Technical Abstract: MicroRNAs (miRNAs) are short noncoding RNAs involved in post-transcriptional regulation of gene expression. However, the role of miRNAs in mediating insecticide resistance remains largely unknown, even in the model species Drosophila melanogaster. A previous study demonstrated that miRNAs are differentially-expressed between dichlorodiphenyltrichloroethane (DDT)-susceptible 91-C and -resistant 91-R strains of D. melanogaster. Furthermore, the significantly lower expression of four miRNAs, miR-310, miR-311, miR-312, and miR-313 (collectively miR-310s), in 91-R compared to 91-C is inversely correlated with the expression level of transcripts encoding xenobiotic detoxification proteins and putative miR-310s seed regions in 3' untranslated regions (3'-UTRs). This current study, we further show that the microinjection of synthetic miR-310s mimics into 91-R flies results in the significant transcriptional repression of computationally-predicted endogenous target detoxification genes, Cyp6g1 and Cyp6g2, and a concomitant increase in DDT susceptibility. Additionally, co-transfection of Drosophila S2 cells with dual luciferase reporter constructs validated predictions that miR-310s bind to seed region in the 3' untranslated regions (3'-UTR) of both Cyp6g1 and Cyp6g2 in vivo. Findings in the current study provide empirical evidence for a link between reduced miRNA expression and an insecticidal resistance phenotype through reduced targeted post-transcriptional suppression of transcripts encoding proteins involved in xenobiotic detoxification. These insights are important for understanding the breadth of adaptive molecular changes that have contributed to responses to DDT selection in D. melanogaster.