Genome-wide RNA interference screening for the clock-related gene of ATP-binding cassette transporters in Drosophila melanogaster (Diptera: Drosophilidae)

ATP-binding cassette (ABC) transporters are widespread among organisms, and 56 genes encode ABC transporters in Drosophilamelanogaster (Meigen). Their functions are thought to be divergent. In this study, we examined whether there is a clock-related ABC transporter by performing genome-wide screening using tissue-specific RNA interference. We obtained five candidates when we used tim(UAS)-gal4, which expresses in virtually all clock-related cells. Because their phenotypes were principally reproducible even when we used pdf-gal4, which expresses in a subset of pacemaker neurons only, those transporters were presumed to function in pacemaker neurons. Those five candidates can be categorized into two groups according to the phenotype of the knockdown flies. In one group, CG9281 and CG15410 (E23), the circadian period of knockdown flies was altered. In the other group, CG5944, CG6052, and CG18633, some of the knockdown flies became arrhythmic whereas for others rhythmicity remained intact. Our results suggest that some ABC transporters that have a significant function in the Drosophila circadian system.