Dynamics of RNA m5C modification during brain development

Post-transcriptional RNA modifications have been recognized as key regulators of neuronal differentiation and synapse development in the mammalian brain. While distinct sets of 5-methylcytosine (m5C) modified mRNAs have been detected in neuronal cells and brain tissues, no study has been performed to characterize methylated mRNA profiles in the developing brain. Here, together with regular RNA-seq, we performed transcriptome-wide bisulfite sequencing to compare RNA cytosine methylation patterns in neural stem cells (NSCs), cortical neuronal cultures, and brain tissues at three postnatal stages. Among 501 m5C sites identified, approximately 6% are consistently methylated across all five conditions. Compared to m5C sites identified in NSCs, 96% of them were hypermethylated in neurons and enriched for genes involved in positive transcriptional regulation and axon extension. In addition, brains at the early postnatal stage demonstrated substantial changes in both RNA cytosine methylation and gene expression of RNA cytosine methylation readers, writers, and erasers. Furthermore, differentially methylated transcripts were significantly enriched for genes regulating synaptic plasticity. Alto-gether, this study provides a brain epitranscriptomic dataset as a new resource and lays the foundation for further investigations into the role of RNA cytosine methylation during brain development.

Automated summary

Post-transcriptional RNA modifications play a crucial role in neuronal differentiation and synapse development in the mammalian brain. In this study, the researchers characterized the methylation profiles of mRNA in the developing brain, identifying m5C sites that are consistently methylated across different conditions. They found that the majority of these methylated sites are hypermethylated in neurons compared to NSCs, and are associated with genes involved in positive transcriptional regulation and axon extension. Furthermore, there were significant changes in RNA cytosine methylation and the expression of related genes during early postnatal brain development, with differentially methylated transcripts enriched for genes regulating synaptic plasticity.