Active N6-Methyladenine demethylation by DMAD regulates gene expression by modulating the binding dynamics of Polycomb protein in neurons

A Ten-Eleven Translocation (TET) ortholog has been identified as a DNA N6-Methyladenine (6mA) demethylase (DMAD) in Drosophila. However, the molecular roles of 6mA and DMAD remain largely unexplored. Through genome-wide 6mA and transcriptome profiling, we found that 6mA may serve as a repressive epigenetic mark on a group of genes involved in neurodevelopment and neuronal functions. Mechanistically, DMAD coordinates with Trithorax-related complex protein Wds to maintain active transcription by dynamically demethylating intragenic 6mA. Accumulation of 6mA by depleting DMAD recruits Polycomb protein Pc as 6mA reader and contributes to transcriptional repression. Our findings define an epigenetic role for 6mA and suggest that active 6mA demethylation by DMAD plays important roles in fly CNS function by coordinating additional epigenetic mechanisms. Overall design: Examine the role of DMAD and 6mA DNA modification in Drosophila neuronal functions