N 6 -methyladenosine (m 6 A) is the most prevalent posttranscriptional modification in eukaryotic mRNAs. Dynamic and reversible m 6 A modification regulates gene expression to control cellular processes and diverse biological functions. Growing evidence indicated that m 6 A modification is involved in Abbreviations: 3 0 UTRs, 3 0 -untranslated regions; 5 0 UTRs, 5 0 -untranslated regions; A, adenosine; ALKBH5, AlkB homolog 5; carRNA, chromatinassociated regulatory RNA; CCR4-NOT, carbon catabolite repressor 4-negative on TATA-less; CD4, cluster of differentiation 4; CIRBP, cold-inducible RNA binding protein; circ0000730, circular RNA 0000730; circHIPK2, circular RNA homeodomain interacting protein kinase 2; circNF1-419, circular RNA neurofibromin 1-419; circNSUN2, circular RNA NOP2/Sun RNA methyltransferase 2; circRNA, circular RNA; COVID-19, Corona Virus Disease 2019; CRISPR-Cas, clustered regularly interspaced short palindromic repeats and their associated proteins;

N6-methyladenosine (m6A) is the most abundant internal modification that widely participates in various immune and inflammatory responses; however, its regulatory mechanisms in the inflammation of liver induced by lipopolysaccharide in piglets remain largely unknown. In the present study, piglets were intraperitoneally injected with 80 μg/kg LPS or an equal dose of sterile saline. Results indicated that LPS administration increased activities of serum alanine aminotransferase (ALT), induced M1 macrophage polarization and promoted secretion of inflammatory cytokines, and finally led to hepatic lesions in piglets. The NOD1/NF-κB signaling pathway was activated in the livers of the LPS group. Moreover, the total m6A level was significantly elevated after LPS treatment. MeRIP-seq showed that 1166 and 1344 transcripts contained m6A methylation in control and LPS groups, respectively. The m6A methylation sites of these transcripts mainly distributes in the 5′ untranslated region (5′UTR), the coding sequence (CDS), and the 3′ untranslated region (3′UTR). Interestingly, these genes were mostly enriched in the NF-κB signaling pathway, and LPS treatment significantly changed the m6A modification in NOD1, RIPK2, NFKBIA, NFKBIB, and TNFAIP3 mRNAs. In addition, knockdown of METTL3 or overexpression of FTO both changed gene levels in the NOD1/NF-κB pathway, suggesting that activation of this pathway was regulated by m6A RNA methylation. Moreover, the alteration of m6A RNA methylation profile may be associated with the increase of reactive oxygen species (ROS), HIF-1α, and MAT2A. In conclusion, LPS activated the NOD1/NF-κB pathway at post-transcriptional regulation through changing m6A RNA methylation, and then promoted the overproduction of proinflammatory cytokines, ultimately resulting in liver inflammation and damage.