Stroke triggers dynamic m6A reprogramming of cerebral circular RNAs

We previously showed that stroke alters circular RNA (circRNA) expression profiles. Many circRNAs undergo epitranscriptomic modifications, particularly methylation of adenosine to form N⁶-methyladenosine (m⁶A). This modification significantly influences the circRNA metabolism and functionality. Hence, we currently evaluated if transient focal ischemia in adult C57BL/6J mice alters the m⁶A methylation of circRNAs. Changes in m⁶A were profiled in the peri-infarct cortex following immunoprecipitation coupled with microarrays. Correlation and gene ontology analyses were performed to understand the association of m⁶A changes with circRNA regulation and functional implications after stroke. Many circRNAs showed differential regulation (up or down) after stroke, and this change was highest at 24h of reperfusion. Notably, most circRNAs differentially regulated after stroke also exhibited temporal changes in m⁶A modification patterns. The majority of circRNAs that showed post-stroke differential m⁶A modifications were derived from protein-coding genes. Hyper-than hypomethylation of circRNAs was most prevalent after stroke. Gene ontology analysis of the host genes suggested that m⁶A-modified circRNAs might regulate functions such as synapse-related processes, indicating that m⁶A epitranscriptomic modification in circRNAs could potentially influence post-stroke synaptic pathophysiology.