Stabilization of ERK-Phosphorylated METTL3 by USP5 Increases m6A Methylation

N-6-methyladenosine (m(6)A) is the most abundant mRNA modification and is installed by the METTL3-METTL14-WTAP methyltransferase complex. Although the importance of m(6)A methylation in mRNA metabolism has been well documented recently, regulation of the m(6)A machinery remains obscure. Through a genome-wide CRISPR screen, we identify the ERK pathway and USP5 as positive regulators of the m6A deposition. We find that ERK phosphorylates METTL3 at S43/S50/S525 and WTAP at S306/S341, followed by deubiquitination by USP5, resulting in stabilization of the m(6)A methyltransferase complex. Lack of METTL3/WTAP phosphorylation reduces decay of m(6)A-labeled pluripotent factor transcripts and traps mouse embryonic stem cells in the pluripotent state. The same phosphorylation can also be found in ERKactivated human cancer cells and contribute to tumorigenesis. Our study reveals an unrecognized function of ERK in regulating m(6)A methylation.