Cancer Research Program, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia.
Stem Cells. 2011 Oct;29(10):1611-9. doi: 10.1002/stem.706.
Recent characterization of mammary stem and progenitor cells has improved our understanding of the transcriptional network that coordinates mammary development; however, little is known about the mechanisms that enforce lineage commitment and prevent transdifferentiation in the mammary gland. The E-twenty six transcription factor Elf5 forces the differentiation of mammary luminal progenitor cells to establish the milk producing alveolar lineage. Methylation of the Elf5 promoter has been proposed to act as a lineage gatekeeper during embryonic development. We used bisulphite sequencing to investigate in detail whether Elf5 promoter methylation plays a role in lineage commitment during mammary development. An increase in Elf5 expression was associated with decreasing Elf5 promoter methylation in differentiating HC11 mammary cells. Similarly, purified mammary epithelial cells from mice had increased Elf5 expression and decreased promoter methylation during pregnancy. Finally, analysis of epithelial subpopulations revealed that the Elf5 promoter is methylated and silenced in the basal, stem cell-containing population relative to luminal cells. These results demonstrate that Elf5 promoter methylation is lineage-specific and developmentally regulated in the mammary gland in vivo, and suggest that loss of Elf5 methylation specifies the mammary luminal lineage, while continued Elf5 methylation maintains the stem cell and myoepithelial lineages.
最近对乳腺干/祖细胞的特征描述提高了我们对协调乳腺发育的转录网络的理解；然而，对于在乳腺中强制谱系决定和防止转分化的机制却知之甚少。E 盒结合因子 Elf5 迫使乳腺腔前体细胞分化，从而建立产奶的肺泡谱系。有人提出，Elf5 启动子的甲基化在胚胎发育过程中充当谱系门控。我们使用亚硫酸氢盐测序来详细研究 Elf5 启动子甲基化是否在乳腺发育过程中的谱系决定中起作用。在分化的 HC11 乳腺细胞中，Elf5 表达的增加与 Elf5 启动子甲基化的减少有关。同样，在怀孕期间，从小鼠中分离出的纯化乳腺上皮细胞中 Elf5 的表达增加，启动子甲基化减少。最后，对上皮亚群的分析表明，Elf5 启动子在基底细胞中被甲基化并沉默，相对于腔细胞。这些结果表明，Elf5 启动子甲基化在体内乳腺中是谱系特异性和发育调控的，并表明 Elf5 甲基化的丧失指定了乳腺腔谱系，而持续的 Elf5 甲基化维持了干细胞和肌上皮谱系。
