The rRNA m6A methyltransferase METTL5 is involved in pluripotency and developmental programmes

Covalent chemical modifications of cellular RNAs directly impact all biological processes. However, our mechanistic understanding of the enzymes catalysing these modifications, their substrates and biological functions remains vague. Here, we undertook a systematic screen to uncover new RNA methyltransferases. We demonstrate that the methyltransferase-like 5 (METTL5) protein catalyses m6A in 18S rRNA at position A1832. We report that absence of Mettl5 in mouse embryonic stem cells (mESCs) results in a changes gene expression, decrease in translation rate, spontaneous loss of pluripotency and compromised differentiation potential. Mice lacking METTL5 recapitulate symptoms of patients with METTL5 mutations, thereby providing a new mouse disease model. Overall, our work highlights the importance of m6A in rRNA in stemness, differentiation, development and diseases. polyA RNA profiles of wild type (WT) and Mettl5 -/- mESC cultured in Serum Lif were generated by deep sequencing, in triplicate, using Illumina TruSeq Stranded mRNA protocol