Abstract TP302: Circular RNAs Methylation Patterns Positively Correlated With Their Expression Level in the Post-Stroke Brain

Circular RNAs (circRNAs), a novel subgroup of noncoding RNAs derived from reverse splicing of various genes, have emerged as potential regulators of transcription and translation. Recent findings indicate that methylation of adenosine (m ⁶ A; N6-methyladenosine) in various RNA types might govern their levels by modulating their degradation as well as functional roles. This study investigated the spatiotemporal correlation of methylation patterns of circRNAs with their abundance in the post-stroke brain. Adult male C57BL/6J mice were subjected to transient middle cerebral artery occlusion, and m ⁶ A methylation in circRNAs was profiled using immunoprecipitated methylated RNAs with microarrays in the peri-infarct cortex at 6h, 12h, and 24h of post-reperfusion. Computational analysis was employed to identify the change in m ⁶ A levels and evaluate the correlation between expression and methylation patterns. We noted that most circRNAs that alter their levels following ischemic stroke are transcribed from the exonic regions of all chromosomes. While most genes generate a single circRNA, a unique situation occurs with the gene Rn45s, giving rise to a minimum of 30 circRNAs within the brain. Interestingly, following the stroke, the overall m ⁶ A levels of circRNAs displayed notable alterations. Moreover, the percentage shift in circRNA m ⁶ A levels increased from 6h to 24h of reperfusion, with some circRNAs, including mmu_circRNA_32433, demonstrating an increase of >40% at the 24h reperfusion. More significantly, many cerebral circRNAs that displayed increased expression also showed elevated m ⁶ A methylation following stroke. The increased m ⁶ A methylation suggests potential stabilization and altered function of circRNAs in the post-stroke brain.