Abstract
While N6-methyladenosine (m6A) RNA modification is implicated in macrophage inflammatory responses, its regulatory mechanisms remain elusive. Our prior studies demonstrated that a deficiency in the immune adaptor protein ADAP promotes inflammation in TLR4-stimulated macrophages. Here, we show that ADAP binds to METTL3, and depletion of Mettl3 alleviates the hyperinflammation in Adap-/- macrophages, indicating METTL3 counteracts the anti-inflammatory function of ADAP in macrophages. Furthermore, LPS induces the METTL3-dependent m6A methylation of Spry1 mRNA in macrophages in the A6988 within the motif GGACU, which is further potentiated upon the depletion of ADAP. Moreover, this positive effect of ADAP deficiency on LPS-induced m6A methylation of Spry1 mRNA is dependent on IGF2BP2, which specifically binds to and stabilize the m6A modified Spry1 mRNA that contributes to an exacerbation of the inflammation in Adap-/- macrophages via NF-κB activation in macrophages. Together, our findings unveil a reciprocal inhibition between ADAP and METTL3 that fine-tunes the inflammatory responses of macrophages via modulation of the m6A methylation of Spry1 mRNA.