A molecular mechanism to regulate neural-specific A-to-I editing during development

Using a combination of molecular and genomic approaches we uncover a molecular mechanism that regulates RNA editing in a neural- and development-specific manner. We de novo identified 570 A-to-i editing sites in adult neural RNA-seq data and 6202 sites from re-analyzing L1 neural RNA seq.Comparing editomes during development led to the identification of both neural transcripts that were edited only in one life-stage. The stage-specific editing is largely regulated by differential gene expression during neural development, and proper gene expression of nearly one-third of these differentially expressed genes is dependent on adr-2, the only known A-to-I editing enzyme in C. elegans. However, we also identified a subset of neural transcripts which are edited and expressed throughout development. Interestingly, despite a neural-specific downregulation of adr-2 during development, the majority of sites edited throughout development exhibit increased editing in adult neural cells. Biochemical data suggests that ADR-1, a deaminase deficient member of the Adenosine deaminase acting on RNA (ADAR) family is competing with ADR-2 for binding to specific transcripts early in development. Our data suggest a model where during neural development, ADR-2 levels overcome ADR-1 repression, resulting in increased ADR-2 binding and editing of specific transcripts. Together, our findings reveal tissue- and development-specific regulation of RNA editing and identify a molecular mechanism that regulates ADAR substrate recognition and editing efficiency. Overall design: High throughput sequencing of adult neural RNA-seq libraries and identification of A-to-I editing sites using SAILOR software