Acute myeloid leukemia (AML) is a heterogeneous disease in respect of molecular aberrations and prognosis. We used gene expression profiling of 562 patients treated in the German AMLCG 1999 trial to develop a gene signature that predicts survival in AML.
A 29-gene and cytogenetic score for the prediction of resistance to induction treatment in acute myeloid leukemia.
Age, Specimen part
View SamplesCardiac muscle differentiation in vivo is guided by sequential growth factor signals, including endoderm-derived diffusible factors, impinging on cardiogenic genes in the developing mesoderm. Previously, by RNA interference in AB2.2 mouse embryonic stem cells (mESCs), we identified the endodermal transcription factor Sox17 as essential for Mesp1 induction in primitive mesoderm and subsequent cardiac muscle differentiation. However, downstream effectors of Sox17 remained to be proven functionally. In this study, we used genome-wide profiling of Sox17-dependent genes in AB2.2 cells, RNA interference, chromatin immunoprecipitation, and luciferase reporter genes to dissect this pathway. Sox17 was required not only for Hhex (a second endodermal transcription factor) but also for Cer1, a growth factor inhibitor from endoderm that, like Hhex, controls mesoderm patterning in Xenopus toward a cardiac fate. Suppressing Hhex or Cer1 blocked cardiac myogenesis, although at a later stage than induction of Mesp1/2. Hhex was required but not sufficient for Cer1 expression. Over-expression of Sox17 induced endogenous Cer1 and sequence-specific transcription of a Cer1 reporter gene. Forced expression of Cer1 was sufficient to rescue cardiac differentiation in Hhex-deficient cells. Thus, Hhex and Cer1 are indispensable components of the Sox17 pathway for cardiopoiesis in mESCs, acting at a stage downstream from Mesp1/2.
Hhex and Cer1 mediate the Sox17 pathway for cardiac mesoderm formation in embryonic stem cells.
Cell line
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Childhood tolerance of severe influenza: a mortality analysis in mice.
Sex, Specimen part
View SamplesLimitation for amino acids is thought to regulate translation in mammalian cells primarily by signaling through the kinases mTORC1 and GCN2. We find that limitation for the amino acid arginine causes a selective loss of tRNA charging, which regulates translation through ribosome pausing at two of six arginine codons. Interestingly, limitation for leucine, an essential and abundant amino acid in protein, results in little or no ribosome pausing. Chemical and genetic perturbation of mTORC1 and GCN2 signaling revealed that their robust response to leucine limitation prevents ribosome pausing, while an insufficient response to arginine limitation led to loss of arginine tRNA charging and ribosome pausing. Codon-specific ribosome pausing decreased protein production and triggered premature ribosome termination without significantly reducing mRNA levels. Together, our results suggest that amino acids which are not optimally sensed by the mTORC1 and GCN2 pathways still regulate translation through an evolutionarily conserved mechanism based on synonymous codon usage. Overall design: Ribosome profiling was performed in HEK293T, HCT116, or HeLa cells during limitation for leucine or arginine for 3 or 6 hours to determine the effect of limiting single amino acid levels of ribosome elongation kinetics at the cognate codons. The same cell lines grown in nutrient-rich conditions were used as a control. These experiments were repeated in HEK293T cells with 250 nM Torin1, in cells stably expressing a flag-tagged wild-type or Q99L mutant RagB-GTPase or hrGFP, and in a GCN2 knockout cell line to determine the role of the mTORC1 and GCN2 pathways.
Translational Control through Differential Ribosome Pausing during Amino Acid Limitation in Mammalian Cells.
Cell line, Subject
View SamplesThe v-erbA oncogene belongs to a superfamily of transcription factors called nuclear receptors, which includes the retinoic acid receptors (RARs) responsible for mediating the effects of retinoic acid (RA). Nuclear receptors bind to specific DNA sequences in the promoter region of target genes and v-erbA is known to exert a dominant negative effect on the activity of the RARs. The repressor activity of v-erbA has been linked to the development of hepatocellular carcinoma (HCC) in a mouse model. We have used microarray analysis to identify genes differentially expressed in hepatocytes in culture (AML12 cells) stably transfected with v-erbA and exposed to RA. We have found that v-erbA can affect expression of RA-responsive genes. We have also identified a number of v-erbA-responsive genes that are known to be involved in carcinogenesis and which may play a role in the development of HCC.
Modulation of expression of RA-regulated genes by the oncoprotein v-erbA.
Specimen part, Cell line
View SamplesCerebral palsy is primarily an upper motor neuron disease that results in a spectrum of progressive movement disorders. Secondary to the neurological lesion, muscles from patients with cerebral palsy are often spastic and form debilitating contractures that limit range of motion and joint function. With no genetic component, the pathology of skeletal muscle in cerebral palsy is a response to aberrant neurological input in ways that are not fully understood. This study was designed to gain further understanding of the skeletal muscle response to cerebral palsy using microarrays and correlating the transcriptional data with functional measures. Hamstring biopsies from gracilis and semitendinosus muscles were obtained from a cohort of patients with cerebral palsy (n=10) and typically developing patients (n=10) undergoing surgery. Affymetrix HG-U133A 2.0 chips (n=40) were used and expression data was verified for 6 transcripts using quantitative real-time PCR, as well as for two genes not on the microarray. Chips were clustered based on their expression and those from patients with cerebral palsy clustered separately. Significant genes were determined conservatively based on the overlap of three summarization algorithms (n=1,398). Significantly altered genes were analyzed for over-representation among gene ontologies, transcription factors, pathways, microRNA and muscle specific networks. These results centered on an increase in extracellular matrix expression in cerebral palsy as well as a decrease in metabolism and ubiquitin ligase activity. The increase in extracellular matrix products was correlated with mechanical measures demonstrating the importance in disability. These data lay a framework for further studies and novel therapies.
Transcriptional abnormalities of hamstring muscle contractures in children with cerebral palsy.
Sex, Age, Disease, Subject
View SamplesWe describe a novel quantitative cDNA expression profiling strategy, involving amplification of the majority of mouse transcriptome using a defined set of 44 heptamer primers. The amplification protocol allows for efficient amplification from as low as 50pg of mRNA and did not alter the expression of the transcripts even with 200 fold dilution of the minimum requirement of the starting material (10ng of mRNA) for standard RNA-seq protocols. We implemented our methodology on embryological lineage segregation, achieved by graded activation of Activin A/TGFß signaling in mouse embryonic stem cells (mESCs). The fold changes in transcript expression were in excellent agreement with quantitative RT-PCR and we observed a dynamic range spanning more than five orders of magnitude in RNA concentration with a reliable estimation of low abundant transcripts. Our transcriptome data identified key lineage markers, while the high sensitivity showed that novel lineage specific transcripts anticipate the differentiation of specific cell types. We compared our strategy with Std. RNA-seq (Mortazavi et al. 2008) and SMART-seq (Ramsköld et al. 2012). We also showed potential of our methodology to suppress the representation of highly expressing ribosomal transcripts. Overall design: Sequencing was performed on day 4 differentiating mouse ESCs treated for two days with 3 different dosages of Activin A (3ng/mL, 15ng/mL and 100ng/mL). The cells were also treated with SB-431542. Serial dilutions of mRNA derived Activin A(3ng/mL) samples were used to detemine the minimum amount of mRNA required to construct relaible sequencing library. SMARTseq libraries were prepared for both Activin A(3ng/mL) and Activin A(100ng/mL) samples. Three Different primer sets were designed to suppress the representaiton of Ribosomal transcripts.
Quantitative transcriptomics using designed primer-based amplification.
Specimen part, Treatment
View SamplesTranscriptomics data obtained from limiting amounts of mRNA is often noisy, providing primarily qualitative changes in transcript expressions. So far, technical variations arising out of the library preparation protocols have not been adequately characterized at reduced levels of mRNA. Here, we generated sequencing libraries from limiting amounts of mRNA using three amplification-based methods, viz. Smart-seq, DP-seq and CEL-seq, and demonstrated significant technical variations in these libraries. Reduction in mRNA levels led to inefficient amplification of the majority of low to moderately expressed transcripts. Furthermore, stochasticity in primer hybridization and/or enzyme incorporation was magnified during the amplification step resulting in significant distortions in fold changes of the transcripts. Consequently, the majority of the differentially expressed transcripts identified were either high-expressed and/or exhibited high fold changes. High technical variations, which were sequencing depth independent, ultimately masked subtle biological differences mandating the development of improved amplification-based strategies for quantitative transcriptomics from limiting amounts of mRNA. Overall design: Sequencing libraries were prepared from serial dilutions of mRNA, ranging from 1 ng to 25 pg, using three amplification-based methods, viz. Smart-seq, DP-seq and CEL-seq. The mRNA was derived from an in vitro model of lineage segregation achieved by modulating TGF beta signaling pathway in differentiating mouse embryonic stem cells.
Technical variations in low-input RNA-seq methodologies.
Specimen part, Subject
View SamplesHypoxia plays a key pathogenic role in the outcome of many pathologic conditions. To elucidate how organisms successfully adapt to hypoxia, a population of Drosophila melanogaster was generated, through an iterative selection process, that is able to complete its lifecycle at 4% O2, a level lethal to the starting parental population. Transcriptomic analysis of flies adapted for >200 generations was performed to identify pathways and processes that contribute to the adapted phenotype, comparing gene expression of three developmental stages with generation-matched control flies. A third group was included, hypoxia-adapted flies reverted to 21% O2 for five generations, to address the relative contributions of genetics and hypoxic environment to the gene expression differences. We identified the largest number of expression differences in 0.5-3 hr post-eclosion adult flies that were hypoxia-adapted and maintained in 4% O2, and found evidence that changes in Wnt signaling contribute to hypoxia tolerance in flies.
Wnt pathway activation increases hypoxia tolerance during development.
No sample metadata fields
View SamplesThe aim of this experiment is to determine the similarities and differences between gene expression profiles in HepaRG cells versus primary human hepatocytes, human liver, and the commonly used HepG2 cell.
A comparison of whole genome gene expression profiles of HepaRG cells and HepG2 cells to primary human hepatocytes and human liver tissues.
Sex, Specimen part, Cell line
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