GSE52016
EZH2 controls mammary differentiation independently of its methyltransferase activity through controlling genomic STAT5 access
Mammary development is characterized by the proliferation and progressive differentiation of alveolar epithelium during pregnancy, culminating in lactation. These processes are largely controlled by hormones through transcription factors. We now explore the contributions of histone methyltransferases, which establish H3K27me3 marks, in the temporally-regulated differentiation of mammary epithelium. Loss of EZH2, but not EZH1, resulted in precocious mammary differentiation, which was facilitated by STAT5 binding to specific target genes and their activation. Mammary stem cells were not compromised in the absence of EZH2. Genome-wide H3K27me3 patterns remained intact in the absence of EZH2. Mammary-specific loci were devoid of H3K27me3 marks in mammary progenitor and mature cells, suggesting no regulatory role for this repressive mark. Lastly, the combined absence of EZH1 and EZH2 inhibited the formation of alveoli. Taken together, EZH2 controls temporally-restricted differentiation of mammary epithelium through H3K27me3-independent mechanisms. Overall design: mRNA-seq and ChIP-seq in MMTV-Cre (Control), E1-/- (E1KO), E1+/-;E2f/f;control (E1+/-E2KO) and Ezh2f/f;control (E2KO) mammary gland tissues or MECs (purified mammary epithelial cells). H3K27me3 and STAT5 ChIP-seqs in mammary tissues at p13; H3K4me3 ChIP-seq in MECs (mammary epithelial cells) at p13; RNA-seqs at mature virgin (with/without prolactin injection), p13 and p18 mammary tissues.