The Ets transcription factor Elf5 specifies mammary alveolar cell fate - PubMed (original) (raw)

. 2008 Mar 1;22(5):581-6.

doi: 10.1101/gad.1614608.

Matthew J Naylor, Marie-Liesse Asselin-Labat, Katrina D Blazek, Margaret Gardiner-Garden, Heidi N Hilton, Michael Kazlauskas, Melanie A Pritchard, Lewis A Chodosh, Peter L Pfeffer, Geoffrey J Lindeman, Jane E Visvader, Christopher J Ormandy

Affiliations

The Ets transcription factor Elf5 specifies mammary alveolar cell fate

Samantha R Oakes et al. Genes Dev. 2008.

Abstract

Hormonal cues regulate mammary development, but the consequent transcriptional changes and cell fate decisions are largely undefined. We show that knockout of the prolactin-regulated Ets transcription factor Elf5 prevented formation of the secretory epithelium during pregnancy. Conversely, overexpression of Elf5 in an inducible transgenic model caused alveolar differentiation and milk secretion in virgin mice, disrupting ductal morphogenesis. CD61+ luminal progenitor cells accumulated in Elf5-deficient mammary glands and were diminished in glands with Elf5 overexpression. Thus Elf5 specifies the differentiation of CD61+ progenitors to establish the secretory alveolar lineage during pregnancy, providing a link between prolactin, transcriptional events, and alveolar development.

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Figures

Figure 1.

Figure 1.

Deletion of Elf5 results in failed alveolar differentiation. (A) Mammary gland morphology from wild-type (left panels) and Elf5−/− (right panels) mammary transplants collected from virgin (top third), 12.5-dpc (middle third), and 1-d-post-partum (bottom third) hosts. Low-power (bottom) and high-power (top left) whole-mounts and mammary epithelium stained with an antibody against milk proteins (brown, top right) counterstained with haematoxylin are illustrated. (B) The percentage of cells stained positive for an antibody against the proliferation antigen Ki67 in mammary transplants with wild type (black bars) and Elf5−/− (white bars) epithelium collected at 4.5 and 6.5 dpc. (C) Representative Western blot of phosphorylated Erk (pErk) and Erk (Erk) protein levels in Elf5−/− and wild-type mammary transplants at 4.5 dpc.

Figure 2.

Figure 2.

Forced Elf5 expression drives alveolar cell differentiation in virgin ductal epithelium and TEBs. (A) Dark-field images showing EGFP expression in mammary whole-mounts from 9-wk-old control Tg mice (Tg − Dox) and Tg mice after 3 wk of Dox treatment (Tg + Dox). Robust EGFP expression was observed in TEBs at the ends of the epithelium and the distended ducts closest to the nipple (ducts). (B) Relative expression of Elf5 mRNA in 9-wk-old wild-type (black bars) and Tg (white bars) treated with Dox for 3 wk, and wild-type mice at 12.5 dpc (12.5, patterned bars). (C) Relative expression of Elf5, βCasein, and Wap mRNA in 9-wk-old wild-type (black bars) and Tg (white bars) mice treated for 3 wk with Dox. (D) βCasein (βCsn) and βActin (βAct) protein levels in 9-wk-old wild-type (black bars) and Tg (white bars) mice after 3 wk of Dox treatment. (E) Mammary whole-mount morphology from Dox-treated wild-type (left panels) and Tg (right panels) mice collected after 3 wk (low power, top row; high power, second row). Alveolar buds from ducts from Tg mice are illustrated (black arrows). (Third row) TEBs stained with an antibody against milk proteins (milk). (Third row, insets) Milk expression in the ducts proximal to the nipple is also illustrated. The expression of βCatenin (βCat, Cy2 green) and Zo1 (Cy3, red) in the TEBs from 9-wk wild-type and Tg mice treated with Dox for 3 wk, counterstained with ToPro3 for nuclei (blue). (White arrows) Aberrant alveolar buds.

Figure 3.

Figure 3.

Forced Elf5 expression results in precocious milk secretion during pregnancy. (A) Relative expression of Elf5, βCasein, and Wap mRNA in wild-type (black bars) or Tg (white bars) mammary glands collected from 12.5-dpc mice after Dox treatment from 3 wk prior to the observation of a vaginal plug. (B) βCasein (βCas) and βActin (βAct) protein expression from wild-type and Tg mammary glands collected at 12.5 dpc in mice treated with Dox from 3 wk prior to the observation of a vaginal plug.

Figure 4.

Figure 4.

Elf5 drives the differentiation of luminal progenitor cells. (A) Representative FACS profile showing the expression of CD61 in Lin−CD24+CD29lo cells in Elf5+/+ and Elf5−/− glands in 12.5-dpc mice. (Dashed line) IgG Isotype control. (B) Bar graph depicting the percentage of luminal progenitor cells in wild-type (black bars) and Elf5−/− (white bars) glands in virgin, 12.5-dpc, and 18.5-dpc animals. (C) Bar graph depicting the percentage of luminal progenitor cells in wild-type (black bars) and Elf5+/− (patterned bars) glands in 12.5-dpc and 18.5-dpc mice. (D) Representative FACS profile showing the expression of CD61 in Lin−CD24+CD29lo cells in 10-wk-old wild-type and Tg mice after 4 wk of Dox treatment. (Dashed line) IgG Isotype control. (E) Bar graph showing the percentage of luminal progenitor cells in 10-wk-old wild-type (black bar) and Tg (white bar) mice after 4 wk of Dox treatment. (F) Colony formation capacity of the MaSC-enriched population (CD29hiCD61+; top panel), the progenitor population (CD29loCD61+; middle panel) and the mature luminal population (CD29loCD61−; bottom panel) freshly isolated from 10-wk-old wild-type and Tg mice after 4 wk of Dox treatment. (G) Relative expression of Elf5 (black bars) and Gata3 (white bars) mRNA in CD61+ luminal progenitor and CD61− mature luminal cells isolated from virgin, 12.5-dpc, and 18.5-dpc mice. (ND) Not detected.

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