| description |
DNA methylation plays critical roles in the nervous system and has been traditionally considered to be restricted to CpG dinucleotides in metazoan genomes. Here we show that the single-base resolution neuronal DNA methylome from the adult mouse dentate gyrus consists of both CpG (~75%) and CpH (~25%) methylation (H = A/C/T). Neuronal CpH methylation is conserved in human brains, enriched in low CpG-density regions, depleted at protein-DNA interaction sites, and anti-correlated with gene expression. Functionally, both mCpGs and mCpHs can repress transcription in vitro and are recognized by MeCP2 in vivo. Unlike most CpG methylation, CpH methylation is established de novo during neuronal maturation and requires DNMT3A for active maintenance in post-mitotic neurons. These characteristics of CpH methylation suggest a significantly expanded proportion of the neuronal genome under cytosine methylation regulation and provide a new framework for understanding the roles of this key epigenetic modification in neuronal identity, maturation, plasticity and neurological disorders.Overall design: Three biological replicates (dentate gyrus samples from C57Black6 mice) were analyzed by mRNA-seq |