N6-methyladenosine (m6A) is a critical epitranscriptomic regulator of neuronal function. Cerebral ischemia induces m6A hypermethylation due to decreased expression of m6A demethylase fat mass and obesity-associated (FTO) protein. Previously, we showed that cerebral overexpression of FTO with an adeno-associated virus (AAV) 9 protects the post-stroke brain. We presently evaluated the mechanistic basis for FTO-dependent m6A demethylation in post-ischemic neuroprotection using the mice transient middle cerebral artery occlusion model of experimental stroke. Based on the bioinformatic predictions and m6A abundance, pro-apoptotic transcription factor Jun proto-oncogene (c-Jun) with 19 m6A sites was chosen as an exemplary target. FTO overexpression normalized the post-stroke m6A hypermethylation of c-Jun without altering its transcript levels. FTO-dependent m6A demethylation suppressed translation of c-Jun. Consequently, several c-Jun target genes are transcriptionally repressed, and the post-ischemic neuronal apoptosis is decelerated, as seen by decreased cleaved caspase-3 levels and TUNEL+ neurons in the FTO AAV9 treated group compared to the control AAV9 treated group. Moreover, replenishing c-Jun precluded the FTO-mediated post-stroke neuroprotection and functional recovery. Collectively, this study demonstrated that the FTO/m6A/c-Jun axis ameliorates post-stroke neuronal apoptosis and brain damage, leading to better functional outcomes.
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