RNA editing is a post-transcriptional modification of pre-mRNA that results in increased diversity in transcriptomes and proteomes. It occurs in a wide variety of eukaryotic organisms and in some viruses. One of the most common forms of pre-mRNA editing is A-to-I editing, in which adenosine is deaminated to inosine, which is read as guanosine during translation. This phenomenon has been observed in numerous transcripts, including the mammalian 5-HT2C receptor, which can be edited at five distinct sites. Methods used to date to quantify 5-HT2C receptor editing are labor-intensive, expensive and provide limited information regarding the relative abundance of 5-HT2C receptor editing variants. Here, we present a novel, ultra high-throughput method to quantify 5-HT2C receptor editing, compare it to a more conventional method, and use it to assess the effect of a range of genetic and pharmacologic manipulations on 5-HT2C editing. We conclude that this new method is powerful and economical, and we provide evidence that alterations in 5-HT2C editing appear to be a result of regional changes in brain activity, rather than a mechanism to normalize 5-HT2C signaling
