Project description:Elf5, an epithelial-specific Ets transcription factor, plays a crucial role in the pregnancy-associated development of the mammary gland. However, the molecular mechanisms employed by Elf5 to exert its effects on the mammary gland are largely unknown. Transcript profiling was used to investigate the transcriptional changes that occur as a result of Elf5 haploinsufficiency. We show that the development of the Elf5+/- gland is delayed at a transcriptional and morphological level, due to the delayed increase in Elf5 protein in these glands. We also identify a number of potential Elf5 target genes, including Mucin 4, whose expression, is directly regulated by the binding of Elf5 to an Ets-binding site within its promoter. We identify novel transcriptional targets of Elf5 and show that Muc4 is a direct target of Elf5, further elucidating the mechanisms through which Elf5 regulates proliferation and differentiation in the mammary gland.
Project description:Elf5, an epithelial-specific Ets transcription factor, plays a crucial role in the pregnancy-associated development of the mammary gland. However, the molecular mechanisms employed by Elf5 to exert its effects on the mammary gland are largely unknown. Transcript profiling was used to investigate the transcriptional changes that occur as a result of Elf5 haploinsufficiency. We show that the development of the Elf5+/- gland is delayed at a transcriptional and morphological level, due to the delayed increase in Elf5 protein in these glands. We also identify a number of potential Elf5 target genes, including Mucin 4, whose expression, is directly regulated by the binding of Elf5 to an Ets-binding site within its promoter. We identify novel transcriptional targets of Elf5 and show that Muc4 is a direct target of Elf5, further elucidating the mechanisms through which Elf5 regulates proliferation and differentiation in the mammary gland. We used Compugen 22,000 oligo arrays from the Adelaide Microarray Centre to determine the transcriptional effects of the loss of one Elf5 allele on mammary gland development. We examined Elf5+/+ and Elf5+/- mammary glands over 5 timepoints of mammary gland development in three experiments. Each experiment used the pooled RNA of 2 mice, resulting in a total of 6 individual mice at each timepoint per genotype. Replica 1 of each condition was labelled with the one fluorophore, and replicas 2 and 3 with the other fluorophore. A common reference design was used for this experiment. RNA extracted from eight pooled 17.5dpc C57BL/6 mouse embryos was used as the reference sample. In total, we performed 30 micraoarray hybridisations, examining 5 timepoints of mammary gland development in 2 genotypes (Elf5+/+ and Elf5+/-). This experiment was repeated with a total of three biological replicates.
Project description:We developed conditional knockout mice where the transcription factor Elf5 (also called ESE-2) is deleted in the mammary glands. Loss of Elf5 results in block in alveologenesis and epithelial differentiation defects. Mammary gland samples from Elf5 knockout and wild type animals were analyzed for global transcriptome changes.
Project description:We developed conditional knockout mice where the transcription factor Elf5 (also called ESE-2) is deleted in the mammary glands. Loss of Elf5 results in block in alveologenesis and epithelial differentiation defects. Mammary gland samples from Elf5 knockout and wild type animals were analyzed for global transcriptome changes. We used microarrays to performing transcriptional profiling of Elf5KO and control mammary glands at Lac1 (Lactation day 1)
Project description:Super-enhancers comprise of dense transcription factor platforms highly enriched for active chromatin marks. A paucity of functional data led us to investigate their role in the mammary gland, an organ characterized by exceptional gene regulatory dynamics during pregnancy. ChIP-Seq for the master regulator STAT5, the glucocorticoid receptor, H3K27ac and MED1, identified 440 mammary-specific super-enhancers, half of which were associated with genes activated during pregnancy. We interrogated the Wap super-enhancer, generating mice carrying mutations in STAT5 binding sites within its three constituent enhancers. Individually, only the most distal site displayed significant enhancer activity. However, combinatorial mutations showed that the 1,000-fold gene induction relied on all enhancers. Disabling the binding sites of STAT5, NFIB and ELF5 in the proximal enhancer incapacitated the entire super-enhancer, suggesting an enhancer hierarchy. The identification of mammary-specific super-enhancers and the mechanistic exploration of the Wap locus provide insight into the complexity of cell-specific and hormone-regulated genes. ChIP-Seq for STAT5A, GR, H3K27ac, MED1, NFIB, ELF5, RNA Pol II, and H3K4me3 in wild type (WT) mammary tissues at day one of lactation (L1), and ChIP-Seq for STAT5A, GR, H3K27ac, MED1, NFIB, ELF5, and H3K4me3 in WT mammary tissues at day 13 of pregnancy (p13). ChIP-Seq for STAT5A, GR, H3K27a in Wap-delE1a, -delE1b, -delE1c, -delE2 and -delE3 mutant mammary tissues at L1, and ChIP-Seq for NFIB and ELF5 in Wap-delE1b and -delE1c mutant mammary tissues at L1. ChIP-Seq for H3K4me3 in mammary-epthelial cells at p13 and L1. DNase-seq in WT mammary tissues at L1 and DNase-seq in Wap-delE1a, -delE1c, and -delE3 mutant mammary tissues at L1.
Project description:The ets transcription factor ELF5 specifies the differentiation of mammary progenitor cells to establish the milk-secreting lineage. ER- and poor prognosis basal breast cancers arise from this progenitor cell and these cancers express high levels of Elf5. Knockdown of ELF5 expression in basal breast cancer cell lines, or forced expression in luminal breast cancer cell lines, resulted in reduced cell proliferation. Transcript profiling and chromatin immunoprecipitation revealed that the transcriptional activity of ELF5 specified the gene expression patterns that distinguish basal from luminal breast cancer, including suppression of FOXA1, GATA3 and ER, key estrogen-action genes. Tamoxifen treatment of luminal MCF7 cells upregulated Elf5 expression and cells that acquired resistance to Tamoxifen became dependent on ELF5 for proliferation. ELF5 is a regulator of breast cancer cell proliferation, transcriptionally specifies the basal molecular subtype and is utilised by ER+ breast cancer cells to escape proliferative arrest caused by Tamoxifen. ChIP-Seq using an antibody to ELF5, in T47D breast carcinoma cell lines
Project description:Elf5 (or ESE-2) is an ETS transcription factor that is abundantly expressed in the mammary epithelium, where it plays a critical role in dictating cell fate and lineage choices. These changes are in part mediated by alterations in the expression and activity of critical components of the Jak/Stat pathway. While the biological function of Elf5 in mammary gland development has been well characterized, its role in breast cancer remains to be elucidated. Here we show that loss of Elf5 leads to features associated with epithelial-mesenchymal transition (EMT) in the mouse mammary gland during pregnancy and lactation. These cellular changes in Elf5-null mammary epithelia are also reflected at the molecular level by the global enrichment of EMT-related gene signatures. ELF5 is expressed in higher level in weakly metastatic breast cancer cells that retained epithelial features compared to highly metastatic cells with mesenchymal features. ELF5 knockdown in T47D breast cancer cells resulted in EMT and increased migration. Conversely, ectopic expression of Elf5 revert mesenchymal-like MDA-MB-231 cells and its lung-tropic variant LM2 to an epithelial phenotype, with reduced migration, invasion and lung metastatic abilities. Finally, we showed that Elf5 binds directly to the promoter of the EMT transcriptional factor Snail2 (Slug) and repress its expression. Taken together, these data established a novel function for Elf5 in inhibiting EMT in normal mammary epithelium and in breast cancer through direct targeting of Snail2. This SuperSeries is composed of the SubSeries listed below.