Distinct roles of androgen receptor, estrogen receptor alpha, and BCL6 in the establishment of sex-biased DNA methylation in mouse liver

Najla Alogayil,Jeffrey D Zajac,Varun S Venkatesh,Teruko Taketo,Kinuyo Ida,Anna K Naumova,Qinwei Kim-Wee Zhuang,Klara Bauermeister,Guillaume Bourque,Jose Hector Galvez,Akihide Kamiya,Rachel A Davey,Matthew L Chang

doi:10.1038/s41598-021-93216-6

Abstract

Sexual dimorphism in gene regulation, including DNA methylation, is the main driver of sexual dimorphism in phenotypes. However, the questions of how and when sex shapes DNA methylation remain unresolved. Recently, using mice with different combinations of genetic and phenotypic sex, we identified sex-associated differentially methylated regions (sDMRs) that depended on the sex phenotype. Focusing on a panel of validated sex-phenotype dependent male- and female-biased sDMRs, we tested the developmental dynamics of sex bias in liver methylation and the impacts of mutations in the androgen receptor, estrogen receptor alpha, or the transcriptional repressor Bcl6 gene. True hermaphrodites that carry both unilateral ovaries and contralateral testes were also tested. Our data show that sex bias in methylation either coincides with or follows sex bias in the expression of sDMR-proximal genes, suggesting that sex bias in gene expression may be required for demethylation at certain sDMRs. Global ablation of AR, ESR1, or a liver-specific loss of BCL6, all alter sDMR methylation, whereas presence of both an ovary and a testis delays the establishment of male-type methylation levels in hermaphrodites. Moreover, the Bcl6-LKO shows dissociation between expression and methylation, suggesting a distinct role of BCL6 in demethylation of intragenic sDMRs.

Highlights

DNA methylation plays major roles in gene regulation, genome organization and stability, and silencing of endogenous retroviruses and repeats
We chose a targeted approach focusing on a panel consisting of both male- and female-biased autosomal sex-associated differentially methylated regions (sDMRs) located within or close to genic regions, and with methylation levels depending on the sex phenotype, but not the sex-chromosome complement
We demonstrate that sex phenotype-dependent autosomal DNA methylation levels in the mouse liver depend on not one, but several factors, including AR, ESR1, and B cell leukemia/lymphoma 6 (BCL6)

Summary

Introduction

DNA methylation plays major roles in gene regulation, genome organization and stability, and silencing of endogenous retroviruses and repeats. Mice with liver-specific deletion of signal transducer and activator of transcription 5 (Stat5a and b) lose sex bias in the expression of nearly 60% of the s DEGs12,13. This loss of sex bias in expression is accompanied by hypermethylation of sDMRs that co-localize with STAT5-associated enhancer r egions[13]. Another potential downstream effector of GH-signaling, B cell leukemia/lymphoma 6 (BCL6) has been implicated in sex-biased expression, and Bcl[6] liver-specific knockouts show loss of sex-biased expression in male livers[14]. Several liver-specific TFs contribute to sex bias in gene regulation

Objectives

Methods

Results

Conclusion