Project description:N6-methyladenosine (m6A) is the most prevalent internal modification found in mammalian messenger and non-coding RNAs. The discoveries of functionally significant demethylases that reverse this methylation as well as the recently revealed m6A distributions in mammalian transcriptomes strongly indicate regulatory functions of this modification. Here we report the identification and characterization of the mammalian nuclear RNA N6-adenosine methyltransferase core (RNMTC) complex. Besides METTL3, a methyltransferase which was the only known component of RNMTC in the past, we discovered that a previously uncharacterized methyltransferase, METTL14, exhibits a N6-adenosine methyltransferase activity higher than METTL3. Together with WTAP, the third component that dramatically affects the cellular m6A level, these three proteins form the core complex that orchestrates m6A deposition on mammalian nuclear RNA. Biochemistry assays, imaging experiments, as well as transcriptome-wide analyses of the binding sites and their effects on m6A methylation support methylation function and reveal new insights of RNMTC. PAR-CLIP and m6A-seq in HeLa cells
Project description:Methylation of N6-adenosine (me6A) has been observed in rRNA, tRNA, snoRNA, lncRNA and mRNA (ref.), but not yet miRNA. Interestingly, many mRNAs contain miRNA-binding sites and me6A in their 3'-UTR, although they do not appear to overlap (Mayer). We have investigated whether adenosine methylation affects miRNA levels and whether miRNAs are methylated. Indeed, we have obtained evidence suggesting that miRNA can be methylated and that the steady state level of certain miRNAs is affected by the level of the 6meA demethylase FTO.
