Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Genome-wide maps of histone modifications in male and female mouse liver

ABSTRACT: Here we map six chromatin modifications -- H3K4me1, H3K4me3, H3K27ac, H3K36me3, H3K9me3, and H3K27me3 -- genome-wide in male and female mouse liver in order to identify histone modifications that characterize sex-biased genes and sex-biased DNase hypersensitive sites and their regulation by plasma growth hormone (GH) profiles, which are sexually dimorphic. We find distinct mechanisms of regulation in male liver and female liver: sex-dependent K27me3-mediated repression is an important mechanism of repression of female-biased, but not of male-biased, genes, and a sex-dependent K4me1 distribution, suggesting nucleosome repositioning by pioneer factors, is observed at male-biased, but not female-biased, regulatory sites. STAT5-mediated activation is most strongly associated with sex-biased chromatin modifications, while BCL6-mediated repression primarily occurs in association with sex-independent chromatin modifications, both at binding sites and at target genes. These samples are part of a study on chromatin states in male and female mouse and their role in sex-biased liver gene expression (A Sugathan and DJ Waxman (2013) Molec Cell Biol). Examination of six different histone modifications in male and female mouse liver.

ORGANISM(S): Mus musculus

SUBMITTER: David Waxman

PROVIDER: E-GEOD-44571 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Sex-dependent pituitary growth hormone (GH) secretory patterns determine the sex-biased expression of >1,000 genes in mouse and rat liver, affecting lipid and drug metabolism, inflammation and disease. A fundamental biological question is how robust differential expression can be achieved for hundreds of sex-biased genes simply based on the GH input signal pattern: pulsatile GH stimulation in males vs. near-continuous GH exposure in females. STAT5 is an essential transcriptional mediator of the sex-dependent effects of GH in the liver, but the mechanisms that underlie its sex-dependent actions are obscure. Here we elucidate the dynamic, sex-dependent binding of STAT5 and the GH/STAT5-regulated repressor BCL6 to mouse liver chromatin, revealing the counteractive interplay between these two regulators of liver sex-specificity. Our findings establish a close correlation between sex-dependent STAT5 binding and sex-biased target gene expression. Moreover, sex-dependent STAT5 binding correlated positively with sex-biased DNase hypersensitivity and H3-K4me1 and H3-K4me3 (activating) marks, correlated negatively with sex-biased H3-K27me3 (repressive) marks, and was associated with sex-differentially enriched motifs for HNF6/CDP factors. Importantly, BCL6 binding was preferentially associated with repression of female-biased STAT5 targets in male liver. Furthermore, BCL6 and STAT5 common targets but not BCL6 unique targets showed strong enrichment for lipid and drug metabolism. These findings provide a comprehensive, genome-wide view of the mechanisms whereby these two GH-regulated transcription factors establish and maintain sex differences affecting liver physiology and disease. The approaches used here to characterize sex-dependent STAT5 and BCL6 binding can be applied to other condition-specific regulatory factors and binding sites and their interplay with co-operative chromatin-binding factors. Mouse livers were excised from individual male and female mice killed at either a peak of STAT5 binding activity, or during the growth hormone (GH) interpulse interval, when STAT5 activity is either low (females) or essentially undetectable (males). Sonicated, cross-linked liver nuclear chromatin was then used to identify STAT5 binding sites by ChIP-Seq.