Loss of age-associated increase in m ⁶ A-modified RNA contributes to GABAergic dysregulation in Alzheimer’s disease

Dysregulated RNA metabolism is a significant feature of Alzheimer’s disease (AD), yet how post-transcriptional RNA modifications like N ⁶ -methyladenosine (m ⁶ A) are altered in AD is unknown. Here, we performed d eamination a djacent to R NA modification targets (DART-seq) on human dorsolateral prefrontal cortices to assess changes in m ⁶ A with nucleotide resolution. In non-AD brains, m ⁶ A sites increased with age, predominantly within the 3′UTR of transcripts encoding tripartite synapse proteins. In contrast, AD brains lost the age-associated m ⁶ A site increase and exhibited global hypomethylation of transcripts, including MAPT and APP . Hypomethylated genes involved with GABAergic signaling, glutamate transport, and ubiquitin-mediated proteolysis exhibited reduced expression, connecting m ⁶ A to synaptic excitotoxicity and disrupted proteostasis in AD. Site-specific m ⁶ A levels were linked with GABRA1 expression and protein levels, but this relationship was abolished in AD. Our findings provide insight into post-transcriptional mechanisms of dysregulated RNA metabolism in AD that are related to aging and GABAergic regulation.