Pregnancy-associated alterations in DNA methylation patterns of mammary epithelial stem cells [inhibitor study]

Mammary gland development and luminal differentiation occur largely postnatally during puberty and pregnancy. To explore the role of DNA methylation in luminal cell differentiation and pregnancy-induced changes, we determined the genome-wide DNA methylation and gene expression profiles of mammary epithelial stem, luminal progenitor, and mature luminal cells at different reproductive stages. We found that pregnancy had the most significant effects on stem cells, inducing a distinct epigenetic state that remained stable through life. Integrated analysis of gene expression, DNA methylation, and histone modification profiles revealed cell type and reproductive stage-specific changes in molecular signatures. We also identified p27 and TGF signaling as key regulators of luminal progenitor cell proliferation based on their expression patterns and by the use of explant cultures. Our results suggest relatively minor changes in DNA methylation during luminal cell differentiation as compared to the significant effects of pregnancy on mammary epithelial stem cells.

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Huh SJ, Clement K, Jee D, Merlini A, Choudhury S, Maruyama R, Yoo R, Chytil A, Boyle P, Ran FA, Moses HL, Barcellos-Hoff MH, Jackson-Grusby L, Meissner A, Polyak K