GSE202386
Identification of m6A-mediated changes in mouse liver after exposure to polychlorinated biphenyls (PCB126 and Aroclor1260) and high fat diet
Exposure to polychlorinated biphenyls (PCBs) has been associated with liver injury in human cohorts and with nonalcoholic steatohepatitis (NASH) in mice fed a high fat diet (HFD). N(6)-methyladenosine (m6A) modification of mRNA regulates transcript fate, but the contribution of m6A modification on regulation of transcription in PCB-induced steatosis and fibrosis is unknown. This study tested the hypothesis that PCB and HFD exposure alters the levels of m6A modification in transcripts that play a role in NASH in vivo. Male C57Bl6/J mice were fed a HFD (12 wks.) and administered a single oral dose of Aroclor1260, PCB126, or Aroclor1260 + PCB126. Genome-wide identification of m6A peaks was accomplished by m6A mRNA immunoprecipitation sequencing (m6A-RIP) and the mRNA transcriptome identified by RNA-seq. Exposure of HFD-fed mice to Aroclor1260 decreased the number of m6A peaks and m6A-containing genes relative to HFD control whereas PCB126 or the combination of Aroclor1260+PCB126 increased m6A modification frequency. ~ 41% of genes had one m6A peak and ~49% had 2-4 m6A peaks. 117 m6A peaks were common in the four experimental groups. The Aroclor1260 + PCB126 exposure group showed the highest number (52) of m6A-peaks. qRT-PCR confirmed enrichment of m6A-containing fragments of the Apob transcript with PCB exposure. Integrated analysis of m6A-RIP-seq and mRNA-seq identified 242 differentially expressed genes (DEGs) with increased or reduced number of m6A peaks. Comparative pathway analysis identified “Immune response: IL-6-induced acute-phase response in hepatocytes” in the Aroclor1260 + PCB126 samples, consistent with steatohepatitis in human PCB epidemiological studies. These data show that PCB exposure in HFD-fed mice alters the m6A landscape offering an additional layer of regulation of gene expression affecting a subset of gene responses in NASH. Overall design: Male C57Bl/6J mice were fed a HFD (42% kCal from fat) and treated with Aroclor 1260, PCB 126, and the combination of Aroclor 1260 + PCB 126 for 12 weeks. Livers were harvested and snap frozen. RNAs isolated were subjected to MeRIP m6A Assay with the Magna MeRIP™ m6A Kit (Millipore, Catalog No. 17-10499). 44 samples, 4 treatment groups, 5 replicates for each group, Input and m6A IP for each sample, plus 1 Ctrl IgG IP for each group were sequenced.