A highly conserved A-to-I RNA editing event within the glutamate-gated chloride channel GluClα is necessary for olfactory-based behaviors in Drosophila

A-to-I RNA editing is an important cellular process that modifies genomically encoded information during transcription, to generate various RNA isoforms from a single DNA sequence. It involves the conversion of specific adenosines in the RNA sequence to inosines by ADAR proteins, resulting in their recognition as guanosines by cellular machinery, and as such plays a vital role in neuronal and immune functions. Given the widespread occurrence of A-to-I RNA editing events across the animal kingdom, with thousands to millions of editing sites found in the transcriptomes of organisms such as flies and humans, identifying the critical sites and understanding their in-vivo functions remains a challenging task. Here we show for the first time the physiological importance of a single editing site, found within the extracellular domain of the glutamate-gated chloride channel (GluCl), and bridge the gap between its evolutionary conservation across Drosophila species and its function in shaping the behavior of adult flies. We used genomic editing to ablate editing at this specific site, such that the endogenous channel harbors only the unedited version and used a battery of behavioral paradigms to analyze the effects on various features of adult behavior. We provide evidence that GluClunedited flies exhibit reduced olfactory responses to both appetitive and aversive odors, as well as impaired pheromone-dependent social interactions, and that editing of this site is required for proper processing of olfactory information in olfactory projection neurons. Our findings demonstrate that evolutionary conservation is a useful criterion to pinpoint which of the many editing events has the potential of having a function and pave the path for dissecting the link between RNA modification, neuronal physiology, and behavior.