RBM4 regulates M1 macrophages polarization through targeting STAT1-mediated glycolysis.

M1/M2 macrophages polarization play important roles in regulating tissue homeostasis. Recently, RNA-binding motif 4 (RBM4) has been reported to modulate the proliferation and expression of inflammatory factors in HeLa cells. However, whether RBM4 is involved in regulating macrophage polarization and inflammatory factor expression are still unknown. In this study, RAW264.7, a mouse macrophage cell line, were stimulated with interferon γ (IFN-γ) or interleukin-4 (IL-4) to induce M1/M2 macrophages polarization. We found that IFN-γ, but not IL-4, stimulation decreased RBM4 expression in macrophages, and RBM4 overexpression inhibits IFN-γ-induced M1 macrophage polarization. Furthermore, RNA-Sequencing, protein immunoprecipitation accompanied with mass spectrometry, and extracellular acidification rate analysis showed that RBM4 suppresses IFN-γ-induced M1 macrophage polarization though inhibiting glycolysis. Moreover, RBM4 knockdown promoted IFN-γ-induced signal transducer and activator of transcription 1 (STAT1) activation via increasing STAT1 mRNA stability, leading to the increase of glycolysis-related gene transcripts regulated by STAT1. Finally, we find that RBM4 interacts with YTH N6-methyladenosine RNA binding protein 2 (YTHDF2) to degrade m6A modified STAT1 mRNA, thereby regulating glycolysis and M1 macrophage polarization. Collectively, the current study firstly reports that RBM4 regulates M1 macrophages polarization through targeting STAT1-mediated glycolysis and shows that RBM4 is a possible candidate for regulating macrophage M1 polarization and inflammatory responses.