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. We used microarrays to performing transcriptional profiling of Elf5KO and control mammary glands at Lac1 (Lactation day 1)
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: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 following subset Series: GSE32143: LM2 cell: infected with lentivirus to stably express Elf5 vs GFP GSE32144: MDA-MB-231 cell: infected with lentivirus to stably express mut-Elf5 vs WT-Elf5
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: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.
Project description:Here, we show that functional loss of a single gene is sufficient to confer constitutive milk protein production and protection against mammary tumor formation. Caveolin-3 (Cav-3), a muscle-specific caveolin-related gene, is highly expressed in striated and smooth muscle cells. We demonstrate that Cav-3 is also expressed in myoepithelial cells within the mammary gland. To determine if genetic ablation of Cav-3 expression affects adult mammary gland development, we next studied the phenotype(s) of Cav-3 (-/-) null mice. Interestingly, detailed analysis of Cav-3 (-/-) virgin mammary glands shows dramatic increases in ductal thickness, side-branching, and the development of extensive lobulo-alveolar hyperplasia, akin to the changes normally observed during pregnancy and lactation. Analysis by genome-wide expression profiling reveals the upregulation of gene transcripts associated with pregnancy/lactation, mammary stem cells, and human breast cancers, consistent with a constitutive lactogenic phenotype. The expression levels of three key transcriptional regulators of lactation, namely Elf5, Stat5a, and c-Myc are also significantly elevated. Experiments with pregnant mice directly show that Cav-3 (-/-) mice undergo precocious lactation. Finally, using orthotopic implantation of a transformed mammary cell line (known as Met-1), we demonstrate that virgin Cav-3 (-/-) mice are dramatically protected against mammary tumor formation. Interestingly, Cav-3 (+/-) mice also show similar protection, indicating that even reductions in Cav-3 levels are sufficient to render these mice resistant to tumorigenesis. Thus, Cav-3 (-/-) mice are a novel preclinical model to study the protective effects of a constitutive lactogenic microenviroment on mammary tumor onset and progression. Our current studies have broad implications for using the lactogenic micro-environment as a paradigm to discover new therapies for the prevention and/or treatment of human breast cancers. Most importantly, a lactation-based therapeutic strategy would provide a more natural and nontoxic approach to the development of novel anti-cancer therapies. Experiment Overall Design: All WT and Cav-3 knockout (KO) mice used in this study were in the FVB/N genetic background. 4-month old virgin female mice were utilized in a micro array study between 3 wildtype and 3 Caveolin-3 knock-out mammary glands.
Project description:Previously we have shown significant differences in lactation performance, mammary gland histology and expression profiles of mammary transcriptome during peak-lactation (lactation day 9; L9) between the ordinary CBA/CaH (CBA) and the superior QSi5 strains of mice. In the present study, we compared mammary gland histology between CBA and QSi5 at mid-pregnancy (pregnancy day 12; P12). We assessed lactation performance during the first 8 days of lactation of the 13th - 14th generation of the Advanced Intercross Line (AIL) (CBA X QSi5) mice. We utilized an integrative approach to analyzing mammary microarray expression profiles of CBA and QSi5 at P12 and CBA, AIL and QSi5 at L9. The inguinal mammary glands of CBA/CaH and QSi5 during mid-pregnancy (Pregnancy day 12; P12), and the glands of CBA/CaH, AIL and QSi5 during peak lactation (Lactation day 9; L9) were collected and total RNA was extracted for Affymetrix microarray (mouse genome 430 2) assay
Project description:Here, we show that functional loss of a single gene is sufficient to confer constitutive milk protein production and protection against mammary tumor formation. Caveolin-3 (Cav-3), a muscle-specific caveolin-related gene, is highly expressed in striated and smooth muscle cells. We demonstrate that Cav-3 is also expressed in myoepithelial cells within the mammary gland. To determine if genetic ablation of Cav-3 expression affects adult mammary gland development, we next studied the phenotype(s) of Cav-3 (-/-) null mice. Interestingly, detailed analysis of Cav-3 (-/-) virgin mammary glands shows dramatic increases in ductal thickness, side-branching, and the development of extensive lobulo-alveolar hyperplasia, akin to the changes normally observed during pregnancy and lactation. Analysis by genome-wide expression profiling reveals the upregulation of gene transcripts associated with pregnancy/lactation, mammary stem cells, and human breast cancers, consistent with a constitutive lactogenic phenotype. The expression levels of three key transcriptional regulators of lactation, namely Elf5, Stat5a, and c-Myc are also significantly elevated. Experiments with pregnant mice directly show that Cav-3 (-/-) mice undergo precocious lactation. Finally, using orthotopic implantation of a transformed mammary cell line (known as Met-1), we demonstrate that virgin Cav-3 (-/-) mice are dramatically protected against mammary tumor formation. Interestingly, Cav-3 (+/-) mice also show similar protection, indicating that even reductions in Cav-3 levels are sufficient to render these mice resistant to tumorigenesis. Thus, Cav-3 (-/-) mice are a novel preclinical model to study the protective effects of a constitutive lactogenic microenviroment on mammary tumor onset and progression. Our current studies have broad implications for using the lactogenic micro-environment as a paradigm to discover new therapies for the prevention and/or treatment of human breast cancers. Most importantly, a lactation-based therapeutic strategy would provide a more natural and nontoxic approach to the development of novel anti-cancer therapies.