Transient Focal Ischemia Significantly Alters the MA Epitranscriptomic Tagging of RNAs in the Brain

Background and Purpose- Adenosine in many types of RNAs can be converted to mA (N-methyladenosine) which is a highly dynamic epitranscriptomic modification that regulates RNA metabolism and function. Of all organs, the brain shows the highest abundance of mA methylation of RNAs. As recent studies showed that mA modification promotes cell survival after adverse conditions, we currently evaluated the effect of stroke on cerebral mA methylation in mRNAs and lncRNAs. Methods- Adult C57BL/6J mice were subjected to transient middle cerebral artery occlusion. In the peri-infarct cortex, mA levels were measured by dot blot analysis, and transcriptome-wide mA changes were profiled using immunoprecipitated methylated RNAs with microarrays (44 122 mRNAs and 12 496 lncRNAs). Gene ontology analysis was conducted to understand the functional implications of mA changes after stroke. Expression of mA writers, readers, and erasers was also estimated in the ischemic brain. Results- Global mA levels increased significantly at 12 hours and 24 hours of reperfusion compared with sham. While 139 transcripts (122 mRNAs and 17 lncRNAs) were hypermethylated, 8 transcripts (5 mRNAs and 3 lncRNAs) were hypomethylated (>5-fold compared with sham) in the ischemic brain at 12 hours reperfusion. Inflammation, apoptosis, and transcriptional regulation are the major biological processes modulated by the poststroke differentially mA methylated mRNAs. The mA writers were unaltered, but the mA eraser (fat mass and obesity-associated protein) decreased significantly after stroke compared with sham. Conclusions- This is the first study to show that stroke alters the cerebral mA epitranscriptome, which might have functional implications in poststroke pathophysiology. Visual Overview- An online visual overview is available for this article.