Circadian rhythm of RNA N6-methyladenosine and the role of cryptochrome.

Methylation of RNA N(6)-methyladenosine has fundamental cellular functions, including translation regulation, RNA export, and stem cells renewal. However, the regulation of RNA N(6)-methyladenosine methylation is poorly understood. Here, we observed a robust circadian rhythm in N(6)-methyladenosine modifications of RNA. Deficiency of core mammalian clock genes, cryptochromes, decreased the levels of N(6)-methyladenosine in RNA. Cryptochrome1/2 knockout mice had significantly lower N(6)-methyladenosine methylation of RNA and lost the circadian rhythm of N(6)-methyladenosine levels in RNA. Global analysis of the circadian methylomes of N(6)-methyladenosine in RNA revealed that gene transcription, translation regulation, and RNA metabolism were highly correlated with N(6)-methyladenosine oscillation. Our findings extended a fundamental link between the circadian rhythm and N(6)-methyladenosine modification of RNA and suggested that this link is critical in controlling post-transcriptional gene expression and RNA metabolism.