Distinct m⁶A and m¹A Responses to Neuronal Depolarization in Cortical Neurons

Area of Science:

• Neuroscience
• Molecular Biology
• Epigenetics

Background:

• Neuronal plasticity, essential for learning and memory, is regulated by RNA methylation.
• The distinct roles of N1-methyladenosine (m1A) and N6-methyladenosine (m6A) in activity-dependent neuronal regulation are not fully understood.

Purpose of the Study:

• To compare the dynamics of m1A and m6A in primary cortical neurons during KCl-induced depolarization.
• To elucidate the distinct mechanisms by which m1A and m6A regulate gene expression in response to neuronal activation.

Main Methods:

• Single-nucleotide resolution GLORI-seq and m1A MAP-seq were employed to profile m1A and m6A modifications.
• RNA sequencing (RNA-seq) was integrated to assess transcriptomic changes.
• RNA structure modeling was utilized to analyze the localization and functional implications of methylation sites.

Main Results:

• During neuronal activation, m1A levels remained stable, while m6A levels decreased.
• m1A preferentially localized to low-minimum free energy (MFE) RNA structures, correlating with elevated transcript expression.
• m6A site changes were not linked to transcriptional changes but were associated with translation-related RNA-binding proteins.

Conclusions:

• m1A enhances RNA output through structural encoding, particularly in loop regions.
• m6A modulates translation via dynamic RNA-binding protein interactions.
• These findings reveal a division of labor between m1A and m6A in coordinating epitranscriptomic responses during neuronal plasticity.