The canonical Wnt signaling pathway is critical for myogenesis and can induce muscle progenitors to switch from proliferation to differentiation; how Wnt signals integrate with muscle specific regulatory factors in this process is poorly understood. We previously demonstrated that the Barx2 homeobox protein promotes differentiation in cooperation with the muscle regulatory factor (MRF) MyoD. Pax7, another important muscle homeobox factor represses differentiation. We now identify Barx2,MyoD,and Pax7 as novel components of the Wnt effector complex, providing a new molecular pathway for regulation of muscle progenitor differentiation. Canonical Wnt signaling induces Barx2 expression in muscle progenitors and perturbation of Barx2 leads to misregulation of Wnt target genes. Barx2 activates two endogenous Wnt target promoters as well as the Wnt reporter gene TOPflash, the latter synergistically with MyoD. Moreover, Barx2 interacts with the core Wnt effectors ß-catenin and TCF, is recruited to TCF/LEF sites, and promotes recruitment of ß-catenin. In contrast, Pax7 represses the Wnt reporter gene and antagonizes the activating effect of Barx2. Pax7 also binds ß-catenin suggesting that Barx2 and Pax7 may compete for interaction with the core Wnt effector complex. Overall, the data show for the first time that Barx2, Pax7, and MRFs can act as direct transcriptional effectors of Wnt signals in myoblasts and that Barx2 and Wnt signaling participate in a regulatory loop. We propose that antagonism between Barx2 and Pax7 in regulation of Wnt signaling may help mediate the switch from myoblast proliferation to differentiation. Overall design: RNA-Seq analyses was used to characterize gene expression in primary myoblasts from wild-type and Barx2 knockout mice.
Barx2 and Pax7 have antagonistic functions in regulation of wnt signaling and satellite cell differentiation.
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View SamplesDiurnal temperature cycling is an intrinsic characteristic of many exposed microbial ecosystems. However, its influence on yeast physiology and transcriptome has not been studied in detail. In this study, 24-h sinoidal temperature cycles, oscillating between 12 and 30C, were imposed on anaerobic, glucose-limited chemostat cultures of Saccharomyces cerevisiae. After three diurnal temperature cycles (DTC), concentrations of glucose, and extracellular metabolites, as well as CO2-production rates showed regular, reproducible circadian rhytms. DTC also led to waves of transcriptional activation and repression, which involved one sixth of the yeast genome. A substantial fraction of these DTC-responsive genes appeared to primarily respond to changes in glucose concentration. Elimination of known glucose-responsive genes revealed overrepresentation of previously identified temperature-responsive genes as well as genes involved in cell cycle and de novo purine biosynthesis. Analyses of budding index and flow cytomery demonstrated that DTC led to a partial synchronization of the cell cycle of the yeast populations in the chemostat cultures, which was lost upon release from DTC. Comparison of DTC results with data from steady-state cultures showed that DTC was sufficiently slow to allow S. cerevisiae chemostat cultures to almost completely acclimatize their transcriptome and physiology at the DTC temperature maximum, and to approach acclimation at the DTC temperature minimum.
Physiological and transcriptional responses of anaerobic chemostat cultures of Saccharomyces cerevisiae subjected to diurnal temperature cycles.
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View SamplesIn this study we addressed subclonal evolutionary process after treatment and subsequent relapse in multiple myeloma (MM) in a cohort of 24 MM patients treated either with conventional chemotherapy or with the proteasome inhibitor, bortezomib. Because MM is a highly heterogeneous disease coupled with a large number of DNA copy number alterations (CNAs) and loss of heterozygosity (LOH), we focused our study on the secondary genetic events: 1q21 gain, NF-kB activating mutations, RB1 and TP53 deletions, that seem to reflect progression. By using genome-wide high resolution SNP arrays we identified subclones with nonlinear complex evolutionary histories in a third of patients with myeloma, the relapse clone apparently derived from a minor subclone at diagnosis. Such reordering of the spectrum of genetic lesions during therapy is likely to reflect selection of genetically distinct subclones not initially competitive against the dominant population that survived chemotherapy, thrived and acquired new anomalies. In addition we found that emergence of minor subclones at relapse was significantly associated with bortezomib treatment. Altogether, these data support the idea of new strategy of future clinical trials in MM that would combine targeted therapy and subpopulations control to eradicate all myeloma subclones in order to obtain long-term remission.
Minor clone provides a reservoir for relapse in multiple myeloma.
Specimen part, Disease, Cell line, Subject
View SamplesSeries GSE25262 patients on expression side.
Minor clone provides a reservoir for relapse in multiple myeloma.
Specimen part, Disease
View SamplesThe present study aims to explore chemostat-based transcriptome analysis of mixed cultures by investigating interactions between the yeast S. cerevisiae and the lactic acid bacterium Lb. bulgaricus . S. cerevisiae and Lb. bulgaricus are both frequently encountered in kefir, a fermented dairy product (25). In the context of this study, this binary culture serves as a model for the many traditional food and beverage fermentation processes in which yeasts and lactic acid bacteria occur together (19,26-30). The design of the cultivation conditions was based on the observation that Lb. bulgaricus, but not S. cerevisiae, can use lactose as a carbon source for growth and that S. cerevisiae, but not Lb. bulgaricus, can grow on galactose that is released upon hydrolysis of lactose by the bacterial -galactosidase.
Transcriptome-based characterization of interactions between Saccharomyces cerevisiae and Lactobacillus delbrueckii subsp. bulgaricus in lactose-grown chemostat cocultures.
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View SamplesHuman aging is associated with loss of function and regenerative capacity. Human bone marrow derived mesenchymal stromal cells (hMSCs) are involved in tissue regeneration, evidenced by their capacity to differentiate into several lineages and therefore are considered the gold standard for cell-based regeneration therapy. Tissue maintenance and regeneration is dependent on stem cells and declines with age and aging is thought to influence therapeutic efficacy, therefore, more insight in the process of aging of hMSCs is of high interest. We, therefore, hypothesized that hMSCs might reflect signs of aging. In order to find markers for donor age, early passage hMSCs were isolated from bone marrow of 61 donors, with ages varying from 17-84, and clinical parameters, in vitro characteristics and microarray analysis were assessed. Although clinical parameters and in vitro performance did not yield reliable markers for aging since large donor variations were present, genome-wide microarray analysis resulted in a considerable list of genes correlating with human age. By comparing the transcriptional profile of aging in human with the one from rat, we discovered follistatin as a common marker for aging in both species. The gene signature presented here could be a useful tool for drug testing to rejuvenate hMSCs or for the selection of more potent, hMSCs for cell-based therapy.
A mesenchymal stromal cell gene signature for donor age.
Sex, Age
View SamplesZinc 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
Physiological and transcriptional responses of Saccharomyces cerevisiae to zinc limitation in chemostat cultures.
No sample metadata fields
View SamplesZinc 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.
Physiological and transcriptional responses of Saccharomyces cerevisiae to zinc limitation in chemostat cultures.
No sample metadata fields
View SamplesZinc 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
Physiological and transcriptional responses of Saccharomyces cerevisiae to zinc limitation in chemostat cultures.
No sample metadata fields
View SamplesAnalysis of p53 binding sites using multiplex enhancer reporter assays, ChIP-seq data and RNA-seq data. Transcription factors establish and maintain the specific transcriptome of a cell by binding to genomic regulatory regions, thereby regulating the transcription of their target genes. Like many transcription factors, the DNA sequence-specific binding preferences of p53 are known. However, it remains largely unclear what distinguishes functional enhancers from other bound genomic regions that have no regulatory activity. In addition, the genome is scattered with seemingly perfect recognition sequences that remain unoccupied. To disentangle the rules of genome-wide p53 binding, we employed two complementary techniques of multiplex enhancer-reporter assays, one using barcoded reporters and the other using enhancer self-transcription. We compared the activity of more than one thousand candidate p53 enhancers under loss and gain of p53 conditions and identified several hundred high-confidence p53-responsive enhancers. Strikingly, the large majority (99%) of these target enhancers can be characterized and distinguished from negative sequences by the occurrence of a single p53 binding site. By training a machine learning classifier on these data, and integrating the resulting genome-wide predictions with fifteen publicly available human p53 ChIP-seq data sets, we identified a consensus set of 1148 functional p53 binding sites in the human genome. Unexpectedly, this direct p53 cistrome is invariably used between cell types and experimental conditions, while differences between experiments can be largely attributed to indirect non-functional binding. Our data suggest that direct p53 enhancers function in a context-independent manner and do not contain obvious combinatorial complexity of binding sites for multiple transcription factors. They represent a class of unsophisticated cell-autonomous enhancers with a single binding site, distinct from complex developmental enhancers that integrate signals from multiple transcription factors. This suggests that context-dependent regulation of p53 target genes is not encoded in the p53 enhancer, but at different upstream or downstream layers of the cell''s gene regulatory network. Overall design: RNA-seq on MCF7 cells with p53 stable knockdown.
Multiplex enhancer-reporter assays uncover unsophisticated TP53 enhancer logic.
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