ADAP-METTL3 modulates the inflammatory responses of macrophages via m6A modification of Spry1.

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.