N-methyladenosine-modified PIAS1 promotes microglia polarization to M1 by regulating PPARγ SUMOylation in Inflammatory Bowel Disease-associated hyperalgesia

Abstract

Abstract Background and Aims: Large number of nociceptive signals produced by intestinal inflammation are transmitted to the spinal dorsal horn, leading to microglia polarization, which is of great significance in mediating central sensitization. Emerging evidence indicate that m6A modification regulates a dynamic macrophage polarization. However, it remains unsolved to link polarization of microglia regulated by m6a modification to inflammatory bowel disease (IBD) associated hyperalgesia. Methods IBD-induced hyperalgesia was assessed by paw withdrawal mechanical threshold in a murine colitis model induced by dextran sulphate sodium (DSS). MeRIP sequence was performed on the LPS-treated primary microglia. The biological role and mechanism of m6A modified PIAS1 in microglia polarization and central sensitization were determined in vitro and in vivo. Results The level of m6A RNA was significantly increased in the spinal dorsal cord of colitis mice, accompanied by microglia polarization to M1-proinflammatory phenotype, and METTL3 was the main regulator involved in the abundant m6A RNA modification. Moreover, MeRIP sequence identified PIAS1 acts anti-inflammatory function though promoting PPARγ SUMOylation in regulating microglia polarization. Mechanistically, the m6A reader YTHDF2 directly recognized and bound to the m6A site on PIAS1 mRNA and reduced PIAS1 mRNA stability. Overexpression YTHDF2 decreased PIAS1 mRNA level and promoted the polarization to M1-phenotype in vitro. Finally, reduced m6A modification by specific downregulation METTL3 in microglia of the spinal dorsal horn contributes to alleviate IBD-associated hyperalgesia. Conclusions The mRNA stabilization of m6A-modified PIAS1-mediated PPARγ SUMOylation as the underlying mechanism through which METTL3 preserved M1-phenotype microglia contributes to IBD-associated hyperalgesia.