Experience-Dependent Accumulation of N⁶-Methyladenosine in the Prefrontal Cortex Is Associated with Memory Processes in Mice

Abstract

The RNA modification N⁶-methyladenosine (m⁶A) influences mRNA stability and cell-type-specific developmental programming, and is highly abundant in the adult brain. However, it has not been determined whether m⁶A is dynamically regulated by experience. Based on transcriptome-wide profiling of m⁶A, we report that the level of m⁶A increases in the medial prefrontal cortex (mPFC) of mice in response to behavioral experience. The modulation was enriched near the stop codon of mRNAs, including genes related to neuronal plasticity. In primary cortical neurons, in vitro, modulation of m⁶A by the RNA demethylase FTO influenced the degradation profiles of a subset of transcripts with modulated sites. In vivo, the expression of Fto and the m⁶A methyltransferase, Mettl3 correlated with the observed increase in m⁶A levels post-training. Furthermore, targeted knockdown of FTO in the mPFC led to enhanced consolidation of cued fear memory. Thus, together with its role in early development, the dynamic regulation of m⁶A in the adult brain serves as an important epitranscriptomic mechanism associated with behavioral adaptation.

SIGNIFICANCE STATEMENT N⁶-methyladenosine (m⁶A) is the most prevalent internal modification on RNA, however, its cellular dynamics in vivo remains elusive. Here we provide the first demonstration of m⁶A upregulation in the mouse medial prefrontal cortex (mPFC) following behavioral training. Knocking down the m⁶A demethylase FTO in the mPFC, which increases total m⁶A level, results in enhanced consolidation of fear memory. Our findings suggest that m⁶A is regulated in an activity-dependent manner in the adult brain, and may function to fine-tune mRNA turnover during memory-related processes.