m1A and m6A modifications function cooperatively to facilitate rapid mRNA degradation

N6-Methyladenosine (m6A), the most abundant internal mRNA modification, affects multiple steps in gene expression. Mechanistically, the binding of YTHDF2 to m6A on mRNAs elicits rapid mRNA degradation by recruiting several RNA degrading enzymes. Here, we show that N1-methyladenosine (m1A), another type of RNA modification, accelerates rapid m6A RNA degradation. We identify HRSP12 as an RNA-binding protein that recognizes m1A. The binding of HRSP12 to m1A promotes efficient interaction of YTHDF2 with m6A, consequently facilitating endoribonucleolytic cleavage via the RNase P/MRP complex. Transcriptome-wide analyses also reveal that mRNAs harboring both m1A and m6A are downregulated in an HRSP12-dependent manner compared with mRNAs harboring m6A only. Accordingly, a subset of endogenous circular RNAs that harbor m6A and associate with YTHDF2 in an HRSP12-dependent manner is also subjected to m1A-facilitated rapid degradation. Together, our observations provide compelling evidence for crosstalk between different RNA modifications.