RRBS (reduced representation bisulfite sequencing) analysis of hepatocyte-specific STAT5a/STAT5b Knockout (STAT5ab-KO) mouse liver to identify differentially methylated regions (DMRs)

The impact of STAT5 on liver DNA methylation was assessed by performing RRBS analysis on male and female mouse liver with a hepatocyte-specific loss of STAT5a and STAT5b. Extensive changes in CpG-methylation were seen in STAT5-deficient liver, where sex differences were abolished at 88% of ~1,500 sex-differentially methylated regions, largely due to increased DNA methylation upon STAT5 loss. STAT5-dependent CpG-hypomethylation was rarely found at proximal promoters of STAT5-dependent genes. Rather, STAT5 primarily regulated the methylation of distal enhancers, where STAT5 deficiency induced widespread hypermethylation at genomic regions enriched for accessible chromatin, enhancer histone marks (H3K4me1, H3K27ac), STAT5 binding, and DNA motifs for STAT5 and other transcription factors implicated in liver sex differences. Thus, the sex-dependent binding of STAT5 to liver chromatin is closely linked to the sex-dependent demethylation of distal regulatory elements linked to STAT5-dependent genes important for liver sex bias. Overall design: Liver genomic DNA was isolated from livers of individual male and female control and hepatocyte-specific STAT5ab-KO mice and subjected to RRBS analysis