Mass spectrometry analysis of METTL3 phosphorylation in extracellular growth factor signaling

A fundamental facet of cell signaling is the conversion of extracellular signals into adaptive transcriptional responses. The role of RNA modifications in this process is poorly understood. We found that epidermal growth factor (EGF) promotes ERK-dependent phosphorylation of the m6A writer enzyme METTL3 at serine-43. Serine-43 phosphorylation increased METTL3-mediated methylation of the small nuclear RNA 7SK. Here we performed of phosphorylation mass spectrometry based on Data independent acquisition (DIA) of Hela cells stimulated with EGF in the absence or presence of the inhibitor U0126. Additionally, we validated known interactions between the 7SK-associated protein LARP7. Our findings establish a novel function for the m6A modification in converting growth-factor signaling events to a transcriptional elongation regulatory response via an RNA-methylation-dependent switch mediated by ERK signaling.