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GSE36939
Homo sapiens
16 Downloadable Samples
Affymetrix Human Gene 1.0 ST Array (hugene10st)
Description
The mechanisms regulating breast cancer differentiation state are poorly understood. Of particular interest are molecular regulators controlling the highly aggressive and poorly differentiated traits of basal-like breast carcinomas. Here we show that the Polycomb factor EZH2 maintains the differentiation state of basal-like breast cancer cells, and promotes the expression of progenitor-associated and basal-lineage genes. Specifically, EZH2 regulates the composition of basal-like breast cancer cell populations by promoting a bi-lineage differentiation state, in which cells co-express basal- and luminal-lineage markers. We show that human basal-like breast cancers contain a subpopulation of bi-lineage cells, and that EZH2-deficient cells give rise to tumors with a decreased proportion of such cells. Bi-lineage cells express genes that are active in normal luminal progenitors, and possess increased colony formation capacity, consistent with a primitive differentiation state. We found that GATA3, a driver of luminal differentiation, performs a function opposite to EZH2, acting to suppress bi-lineage identity and luminal progenitor gene expression. GATA3 levels increase upon EZH2 silencing, leading to the observed decrease in bi-lineage cell numbers. Our findings reveal a novel role for EZH2 in controlling basal-like breast cancer differentiation state and intra-tumoral cell composition.
Publication Title
EZH2 promotes a bi-lineage identity in basal-like breast cancer cells.
Sample Metadata Fields
Specimen part, Cell line, Treatment
View Samples- Homo sapiens
- 6 Downloadable Samples
Illumina HiSeq 2000
Description
The NEET proteins mitoNEET (mNT) and nutrient-deprivation autophagy factor-1 (NAF-1) are required for cancer cell proliferation and resistance to oxidative stress. MitoNEET and NAF-1 are also implicated in a number of other human pathologies including diabetes, neurodegeneration and heart disease, as well as in development, differentiation and aging. Previous studies suggested that mNT and NAF-1 could function in the same pathway in cancer cells, preventing the over-accumulation of iron and reactive oxygen species (ROS) in mitochondria. Nevertheless, it is unknown whether these two proteins interact in cells, and how they mediate their function. Here we demonstrate, using yeast two-hybrid, in vivo bimolecular fluorescence complementation (BiFC), direct coupling analysis (DCA), RNA- sequencing, ROS and iron imaging, and single and double shRNA lines with suppressed mNT, NAF-1 and mNT/NAF-1 expression, that mNT and NAF-1 interact in cancer cells and function in the same cellular pathway. We further show using an in vitro cluster transfer assay that mNT can transfer its clusters to NAF-1. Our study suggests that mNT and NAF-1 could function as part of an iron-sulfur (2Fe-2S) cluster relay to maintain the levels of iron and Fe-S clusters under control in the mitochondria of cancer cells, thereby preventing the activation of apoptosis and/or autophagy and thus promoting rapid cellular proliferation. Overall design: Examination of the effect of suppression of mNT in the breast cancer cell line MCF-7. Two sample types were analyzed, MCF-7 suppressed for mNT and MCF-7 Empty vector control, three replicates for each.
Publication Title
Interactions between mitoNEET and NAF-1 in cells.
Sample Metadata Fields
Specimen part, Cell line, Subject
View Samples- Homo sapiens
- 6 Downloadable Samples
- IlluminaHiSeq2000
Description
Nutrient autophagy factor 1 (NAF-1) is an iron-sulfur protein found on the outer mitochondrial membrane and the ER. Recent studies highlighted an important role for NAF-1 in regulating autophagy via interaction with BCL-2. We recently reported that the level of NAF-1 is elevated in cancer cells and that NAF-1 is required for tumor growth. Here we report that shRNA suppression of NAF-1 results in the activation of apoptosis in xenograft tumors and cancer cells grown in culture. Suppression of NAF-1 resulted in a depletion in the cytosolic iron pool, facilitated uptake of iron, and accumulation of iron and ROS in mitochondria, a shift to glycolysis and glutaminolysis, and the activation of cellular stress pathways associated with HIF1a, AMPK and mTOR. Suppression of NAF-1 in breast cancer cells appears therefore to reduce their tumorigenicity by interfering with cellular iron distribution and energy metabolism resulting in the activation of apoptosis. Overall design: Examination of the effect of suppression of NAF-1 in the breast cancer cell line MCF-7. Two sample types were analyzed, MCF-7 suppressed for NAF-1 and MCF-7 Empty vector control, three replicates for each.
Publication Title
Activation of apoptosis in NAF-1-deficient human epithelial breast cancer cells.
Sample Metadata Fields
No sample metadata fields
View Samples- Saccharomyces cerevisiae
- 29 Downloadable Samples
- Affymetrix Yeast Genome S98 Array (ygs98)
Description
Addition of 3 new arrays made from carbon limited chemostat of CENPK113-7D and 3 new arrays made from aerobic carbon limited chemostat of CENPK113-7D Complmentary data to the data of the serie GSE1723.
Publication Title
Exploiting combinatorial cultivation conditions to infer transcriptional regulation.
Sample Metadata Fields
No sample metadata fields
View Samples- Saccharomyces cerevisiae
- 23 Downloadable Samples
- Affymetrix Yeast Genome S98 Array (ygs98)
Description
The goal of this study was to study this interaction by analyzing genome-wide transcriptional responses to four different nutrient-limitation regimes under aerobic and anaerobic conditions in chemostat cultures of S. cerevisiae. This two-dimensional approach resulted in a new, robust set of anaerobic and aerobic signature transcripts for S. cerevisiae, as well as to a refinement of previous reports on nutrient-responsive genes. Moreover, the identification of genes regulated both by nutrient and oxygen availability provided new insight in cross-regulated network and hierarchy in the control of gene expression.
Publication Title
Two-dimensional transcriptome analysis in chemostat cultures. Combinatorial effects of oxygen availability and macronutrient limitation in Saccharomyces cerevisiae.
Sample Metadata Fields
No sample metadata fields
View Samples- Saccharomyces cerevisiae
- 12 Downloadable Samples
- Affymetrix Yeast Genome S98 Array (ygs98)
Description
In contrast to batch cultivation, chemostat cultivation allows the identification of carbon source responses without interference by carbon-catabolite repression, accumulation of toxic products, and differences in specific growth rate. This study focuses on the yeast Saccharomyces cerevisiae, grown in aerobic, carbon-limited chemostat cultures. Genome-wide transcript levels and in vivo fluxes were compared for growth on two sugars, glucose and maltose, and for two C2-compounds, ethanol and acetate. In contrast to previous reports on batch cultures, few genes (180 genes) responded to changes of the carbon source by a changed transcript level. Very few transcript levels were changed when glucose as the growth-limiting nutrient was compared with maltose (33 transcripts), or when acetate was compared with ethanol (16 transcripts). Although metabolic flux analysis using a stoichiometric model revealed major changes in the central carbon metabolism, only 117 genes exhibited a significantly different transcript level when sugars and C2-compounds were provided as the growthlimiting nutrient. Despite the extensive knowledge on carbon source regulation in yeast, many of the carbon source-responsive genes encoded proteins with unknown or incompletely characterized biological functions. In silico promoter analysis of carbon source-responsive genes confirmed the involvement of several known transcriptional regulators and suggested the involvement of additional regulators. Transcripts involved in the glyoxylate cycle and gluconeogenesis showed a good correlation with in vivo fluxes. This correlation was, however, not observed for other important pathways, including the pentose-phosphate pathway, tricarboxylic acid cycle, and, in particular, glycolysis. These results indicate that in vivo fluxes in the central carbon metabolism of S. cerevisiae grown in steadystate, carbon-limited chemostat cultures are controlled to a large extent via post-transcriptional mechanisms.
Publication Title
Role of transcriptional regulation in controlling fluxes in central carbon metabolism of Saccharomyces cerevisiae. A chemostat culture study.
Sample Metadata Fields
No sample metadata fields
View Samples- Saccharomyces cerevisiae
- 4 Downloadable Samples
- Illumina HiSeq 2500
Description
As a result of ancestral whole genome and small-scale duplication events, the genome of Saccharomyces cerevisiae's, and of many eukaryotes, still contain a substantial fraction of duplicated genes. In all investigated organisms, metabolic pathways, and more particularly glycolysis, are specifically enriched for functionally redundant paralogs. In ancestors of the Saccharomyces lineage, the duplication of glycolytic genes is purported to have played an important role leading to S. cerevisiae current lifestyle favoring fermentative metabolism even in the presence of oxygen and characterized by a high glycolytic capacity. In modern S. cerevisiae, the 12 glycolytic reactions leading to the biochemical conversion from glucose to ethanol are encoded by 27 paralogs. In order to experimentally explore the physiological role of this genetic redundancy, a yeast strain with a minimal set of 14 paralogs was constructed (MG strain). Remarkably, a combination of quantitative, systems approach and of semi-quantitative analysis in a wide array of growth environments revealed the absence of phenotypic response to the cumulative deletion of 13 glycolytic paralogs. This observation indicates that duplication of glycolytic genes is not a prerequisite for achieving the high glycolytic fluxes and fermentative capacities that are characteristic for S. cerevisiae and essential for many of its industrial applications and argues against gene dosage effects as a means for fixing minor glycolytic paralogs in the yeast genome. MG was carefully designed and constructed to provide a robust, prototrophic platform for quantitative studies, and is made available to the scientific community. Overall design: The goals of the present study are to experimentally explore genetic redundancy in yeast glycolysis by cumulative deletion of minor paralogs and to provide a new experimental platform for fundamental yeast research by constructing a yeast strain with a functional 'minimal glycolysis'. To this end, we deleted 13 minor paralogs, leaving only the 14 major paralogs for the S. cerevisiae glycolytic pathway. The cumulative impact of deleting all minor paralogs was investigated by two complementary approaches. A first, quantitative analysis focused on the impact on glycolytic flux under a number of controlled cultivation conditions that, in wild-type strains, result in different glycolytic fluxes. These quantitative growth studies were combined with transcriptome, enzyme-activity and intracellular metabolite assays to capture potential small phenotypic effects. A second, semi-quantitative characterization explored the phenotype of the 'minimal glycolysis' strain under a wide array of experimental conditions to identify potential context-dependent phenotypes
Publication Title
The Genetic Makeup and Expression of the Glycolytic and Fermentative Pathways Are Highly Conserved Within the <i>Saccharomyces</i> Genus.
Sample Metadata Fields
Cell line, Subject
View Samples- Saccharomyces cerevisiae
- 161 Downloadable Samples
- Affymetrix Yeast Genome S98 Array (ygs98)
Description
Background
Publication Title
Combinatorial effects of environmental parameters on transcriptional regulation in Saccharomyces cerevisiae: a quantitative analysis of a compendium of chemostat-based transcriptome data.
Sample Metadata Fields
No sample metadata fields
View Samples- Saccharomyces cerevisiae
- 1 Downloadable Sample
- Affymetrix Yeast Genome S98 Array (ygs98)
Description
Zinc is indispensable for the catalytic activity and structural stability of many proteins, and its deficiency can have severe consequences for microbial growth in natural and industrial environments. For example, Zn depletion in wort negatively affects beer fermentation and quality. Several studies have investigated yeast adaptation to low Zn supply, but were all performed in batch cultures, where specific growth rate depends on Zn availability. The transcriptional responses to growth-rate and Zn availability are then intertwined, which obscures result interpretation. In the present study, transcriptional responses of Saccharomyces cerevisiae to Zn availability were investigated at a fixed specific growth rate under Zn limitation and excess in chemostat culture. To investigate the context-dependency of this transcriptional response, yeast was grown under several chemostat regimes resulting in various carbon (glucose), nitrogen (ammonium) and oxygen supplies. A robust set of genes that responded consistently to Zn limitation was identified and enabled the definition of a Zn-specific Zap1 regulon comprising of 26 genes and characterized by a broader ZRE consensus (MHHAACCBYNMRGGT) than so far described. Most surprising was the Zn-dependent regulation of genes involved in storage carbohydrate metabolism. Their concerted down-regulation was physiologically relevant as revealed by a substantial decrease in glycogen and trehalose cellular content under Zn limitation. An unexpectedly large amount of genes were synergistically or antagonistically regulated by oxygen and Zn availability. This combinatorial regulation suggested a more prominent involvement of Zn in mitochondrial biogenesis and function than hitherto identified
Publication Title
Physiological and transcriptional responses of Saccharomyces cerevisiae to zinc limitation in chemostat cultures.
Sample Metadata Fields
No sample metadata fields
View Samples- Saccharomyces cerevisiae
- 5 Downloadable Samples
- Affymetrix Yeast Genome S98 Array (ygs98)
Description
Zinc is indispensable for the catalytic activity and structural stability of many proteins, and its deficiency can have severe consequences for microbial growth in natural and industrial environments. For example, Zn depletion in wort negatively affects beer fermentation and quality. Several studies have investigated yeast adaptation to low Zn supply, but were all performed in batch cultures, where specific growth rate depends on Zn availability. The transcriptional responses to growth-rate and Zn availability are then intertwined, which obscures result interpretation. In the present study, transcriptional responses of Saccharomyces cerevisiae to Zn availability were investigated at a fixed specific growth rate under Zn limitation and excess in chemostat culture. To investigate the context-dependency of this transcriptional response, yeast was grown under several chemostat regimes resulting in various carbon (glucose), nitrogen (ammonium) and oxygen supplies. A robust set of genes that responded consistently to Zn limitation was identified and enabled the definition of a Zn-specific Zap1 regulon comprising of 26 genes and characterized by a broader ZRE consensus (MHHAACCBYNMRGGT) than so far described. Most surprising was the Zn-dependent regulation of genes involved in storage carbohydrate metabolism. Their concerted down-regulation was physiologically relevant as revealed by a substantial decrease in glycogen and trehalose cellular content under Zn limitation. An unexpectedly large amount of genes were synergistically or antagonistically regulated by oxygen and Zn availability. This combinatorial regulation suggested a more prominent involvement of Zn in mitochondrial biogenesis and function than hitherto identified.
Publication Title
Physiological and transcriptional responses of Saccharomyces cerevisiae to zinc limitation in chemostat cultures.
Sample Metadata Fields
No sample metadata fields
View Samples