m⁶A mRNA Methylation Was Associated With Gene Expression and Lipid Metabolism in Liver of Broilers Under...

Hepatic inflammation is always accompanied with abnormal lipid metabolism. Whether N⁶-methyladenosine (m⁶A) mRNA methylation affects irregular inflammatory lipid level is unclear. Here, the m⁶A modification patterns in chicken liver at the acute stage of LPS-stimulated inflammation and at the normal state were explored via m⁶A and RNA sequencing and bioinformatics analysis. A total of 7,815 m⁶A 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 m⁶A modification pattern changed and showed 1,200 different m⁶A peaks. The hyper- and hypo-m⁶A 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 m⁶A methylation level and the relative fold change of mRNA expression. Moreover, computational prediction of protein-protein interaction (PPI) showed that genes with altered m⁶A 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 m⁶A map of broiler chicken liver at the acute stage of LPS induced inflammation. The findings may shed lights on the possible mechanisms of m⁶A-mediated lipid metabolism disorder in inflammation.