m(6)A mRNA Methylation Was Associated With Gene Expression and Lipid Metabolism in Liver of Broilers Under Lipopolysaccharide Stimulation

Hepatic inflammation is always accompanied with abnormal lipid metabolism. Whether N-6-methyladenosine (m(6)A) mRNA methylation affects irregular inflammatory lipid level is unclear. Here, the m(6)A modification patterns in chicken liver at the acute stage of LPS-stimulated inflammation and at the normal state were explored via m(6)A and RNA sequencing and bioinformatics analysis. A total of 7,815 m(6)A peaks distributed in 5,066 genes were identified in the normal chicken liver and were mostly located in the CDS, 3 ' UTR region, and around the stop codon. At 2 h after the LPS intraperitoneal injection, the m(6)A modification pattern changed and showed 1,200 different m(6)A peaks. The hyper- and hypo-m(6)A peaks were differentially located, with the former mostly located in the CDS region and the latter in the 3 ' UTR and in the region near the stop codon. The hyper- or hypo-methylated genes were enriched in different GO ontology and pathways. Co-analysis revealed a significantly positive relationship between the fold change of m(6)A methylation level and the relative fold change of mRNA expression. Moreover, computational prediction of protein-protein interaction (PPI) showed that genes with altered m(6)A methylation and mRNA expression levels were clustered in processes involved in lipid metabolism, immune response, DNA replication, and protein ubiquitination. CD18 and SREBP-1 were the two hub genes clustered in the immune process and lipid metabolism, respectively. Hub gene AGPAT2 was suggested to link the immune response and lipid metabolism clusters in the PPI network. This study presented the first m(6)A map of broiler chicken liver at the acute stage of LPS induced inflammation. The findings may shed lights on the possible mechanisms of m(6)A-mediated lipid metabolism disorder in inflammation.