DEAD-box RNA helicases eIF4A and Ded1 are believed to promote translation initiation by resolving mRNA secondary structures that impede ribosome attachment at the mRNA 5' end or subsequent scanning of the 5'UTR, but whether they perform distinct functions or act redundantly in vivo is poorly understood. We compared the effects of mutations in Ded1 or eIF4A on global translational efficiencies (TEs) in yeast by ribosome footprint profiling. Despite similar reductions in bulk translation, inactivation of a cold-sensitive Ded1 mutant substantially reduced the TEs of >600 mRNAs, whereas inactivation of a temperature-sensitive eIF4A mutant yielded <40 similarly impaired mRNAs. The broader requirement for Ded1 did not reflect more pervasive secondary structures at low temperature, as inactivation of temperature-sensitive and cold-sensitive ded1 mutants gave highly correlated results. Interestingly, Ded1-dependent mRNAs exhibit greater than average 5'UTR length and propensity for secondary structure, implicating Ded1 in scanning though structured 5' UTRs. Reporter assays confirmed that cap- distal stem-loop insertions increase dependence on Ded1 but not eIF4A for efficient translation. While only a small fraction of mRNAs is strongly dependent on eIF4A, this dependence is significantly correlated with requirements for Ded1 and 5'UTR features characteristic of Ded1- dependent mRNAs. Our findings suggest that Ded1 is critically required to promote scanning through secondary structures within 5'UTRs; and while eIF4A cooperates with Ded1 in this function, it also promotes a step of initiation common to virtually all yeast mRNAs. Overall design: We compared the effects of mutations in Ded1 or eIF4A on global translational efficiencies (TEs) in yeast by ribosome footprint profiling.The study includes 32 samples, comprised of 16 mRNA-Seq samples and 16 ribosome footprint profiling samples, derived from biological replicates of 3 mutant strains, ded1-cs, ded1-ts and tif1-ts, and the corresponding wild-type strains. The tif1-ts mutant and its wild-type counterpart were analyzed at 30°C and 37°C.
Functional interplay between DEAD-box RNA helicases Ded1 and Dbp1 in preinitiation complex attachment and scanning on structured mRNAs in vivo.
Subject
View SamplesSpermatogonia expressing the highest levels of ID4 (ID4-GFP Bright) represent a population highly enriched for spermatogonial stem cells (SSC) while those expressing lower levels (ID4-GFP Dim) are the putative immediate progenitors. Comparing the transcriptome of these populations can provide insight into the SSC to progenitor transition. Overall design: Comparison of transcriptomes of ID4-GFP Bright and ID4-GFP Dim spermatogonia from postnatal day 8 mouse pups
ID4 levels dictate the stem cell state in mouse spermatogonia.
Specimen part, Subject
View SamplesSpinal muscular atrophy (SMA) is one of the most common inherited forms of neurological disease leading to infant mortality. Patients exhibit selective loss of lower motor neurons resulting in muscle weakness, paralysis, and often death. Although patient fibroblasts have been used extensively to study SMA, motor neurons have a unique anatomy and physiology which may underlie their vulnerability to the disease process. Here we report the generation of induced pluripotent stem (iPS) cells from skin fibroblast samples taken from a child with SMA. These cells expanded robustly in culture, maintained the disease genotype, and generated motor neurons that showed selective deficits compared to those derived from the childs unaffected mother. This is the first study to show human iPS cells can be used to model the specific pathology seen in a genetically inherited disease. As such, it represents a promising resource to study disease mechanisms, screen novel drug compounds, and develop new therapies.
Induced pluripotent stem cells from a spinal muscular atrophy patient.
No sample metadata fields
View SamplesE4bp4 is essential for the development of natural killer (NK) cells. We sought to identify downstream targets of E4bp4 by comparing mRNA expression in wild type vs. E4bp4 knockout
The transcription factor E4bp4/Nfil3 controls commitment to the NK lineage and directly regulates Eomes and Id2 expression.
Specimen part
View SamplesGoal of this study is differential gene expression between wild type and Toddler mutant during early zebrafish embryogenesis Overall design: Four timepoints - 4 hours post fertilization (hpf), 5 hpf, 6 hpf, and 7 hpf; one replicate of wild type at each time point, one replicate Toddler mutant at each time point
Toddler signaling regulates mesodermal cell migration downstream of Nodal signaling.
No sample metadata fields
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Genome-wide characterization reveals complex interplay between TP53 and TP63 in response to genotoxic stress.
Treatment
View SamplesIn response to genotoxic stress the TP53 tumour suppressor activates target gene expression to induce cell cycle arrest or apoptosis depending on the extent of DNA damage. These canonical activities can be repressed by TP63 in normal stratifying epithelia to maintain proliferative capacity or drive proliferation of squamous cell carcinomas, where TP63 is frequently overexpressed/amplified. Here we use ChIP-sequencing, integrated with microarray analysis, to define the genome wide interplay between TP53 and TP63 in response to genotoxic stress in normal cells. We reveal that TP53 and TP63 bind to overlapping, but distinct cistromes of sites through utilization of distinctive consensus motifs and that TP53 is constitutively bound to a number of sites. We demonstrate that cisplatin and adriamycin elicit distinct effects on TP53 and TP63 binding events, through which TP53 can induce or repress transcription of an extensive network of genes by direct binding and/or modulation of TP63 activity. Collectively, this results in a global TP53 dependent repression of cell cycle progression, mitosis and DNA damage repair concomitant with activation of anti-proliferative and pro-apoptotic canonical target genes. Further analyses reveals that in the absence of genotoxic stress TP63 plays an important role in maintaining expression of DNA repair genes, loss of which results in defective repair
Genome-wide characterization reveals complex interplay between TP53 and TP63 in response to genotoxic stress.
Treatment
View SamplesAlthough many genes have been proposed to be involved in prostate carcinogenesis, no single gene or gene profile has shown to have prognostic value. The main challenge for clinical management is to distinguish slowly growing tumors from those that will relapse. In this study, we compared expression profiles of 18 prostate samples (7 with Gleason 6, 8 with Gleason 7 and 3 with Gleason score equal or higher than 8) and 5 non-neoplastic prostate samples, using the GeneChip Human Exon Array 1.0 ST of Affymetrix. Microarray analysis revealed 99 genes showing statistically significant differences among tumors with Gleason score 6, 7 and 8. In addition, mRNA expression of 29 selected genes was analyzed by qRT-PCR with microfluidic cards in an extended series of 30 prostate tumors. From these, 29 were selected to be validated and the differential expression of 18 of them (62%) was independently confirmed by quantitative real-time RT-PCR (14 upregulated and 4 downregulated in higher Gleason scores) in the extended series. This list was further narrowed down to 12 genes that were differentially expressed in tumors with Gleason score of 6-7 vs 8. Finally, the protein levels of two genes from the 12-gene signature (SEC14L1 and TCEB1) were additionally validated by immunohistochemistry. Strong protein levels of both genes were correlated with Gleason score, stage, and PSA progression.
A 12-gene expression signature is associated with aggressive histological in prostate cancer: SEC14L1 and TCEB1 genes are potential markers of progression.
Specimen part
View SamplesIn order to determine BCL6 target genes an EBV negative Burkitt's lymphoma cell line, DG75, was stably transfected with a tetracycline transactivator and tight doxycycline responsive expression of GFP was established. The endogenous BCL6 genes of this cell line were disrupted by homologous recombination and a BCL6 cDNA downstream of tetracycline responsive elements (TRE) was inserted to produce Bcl6-/-:tetBCL6-HA cells. Westerns demonstrated doxycycline dependent BCL6 expression.Bcl6-/-:tet. BCL6-HA cells (clone AB7) were either grown without doxycycline (control) or with 1 ug/ml doxycycline for 16, 48 or 96 hours. Total RNA was extracted using RNeasy minipreps (Qiagen) and concentration and quality were checked on the NanoDrop ND- 1000 spectrophotometer (NanoDrop Technologies, USA) and the RNA Nano 6000 kit (Agilent Technologies) on a 2100 Bioanalyzer (Agilent Technologies). One hundred ng of total RNA was processed with the GeneChip Eukaryotic Whole Transcript Sense Target Labelling Assay kit (Affymetrix) according to the manufacturer's details. Hybridisation and scanning of GeneChips was carried out at the CSC/IC Microarray Centre, MRC Clinical Sciences Centre Imperial College London and data analysis by Bioinformatics Support Service, Imperial College London. Briefly, pre- processing of data was performed using GeneSpring GX 10.0.2 software (Agilent Technologies) which applied the "Exon RMA16" algorhithm to the data set. Exon RMA16 performs background correction, quantile normalisation, median polish summarisation and variance stabilisation of 16. In background correction, intensity values of each individual array are corrected for non-specific binding by subtracting the average signal intensity of the area between spots from each probe set. Normalisation is required so multiple chips can be compared to each other. Quantile normalisation adjusts the distribution of probe intensity of each array analysed and so that the distribution of probe intensities for each array in a set of arrays is the same. Probe summarisation refers to the conversion of probe level values (there are approximately 26 probes per gene on each GeneChip) to a single probe set expression value. Variance stabilisation of 16 refers to the addition of the value 16 to the expression values. By increasing the expression value, the variance of the data set is reduced and the distribution (defined by its mean and its variance) is stabilised.
Synthetic Lethal Screen Demonstrates That a JAK2 Inhibitor Suppresses a BCL6-dependent IL10RA/JAK2/STAT3 Pathway in High Grade B-cell Lymphoma.
Cell line
View SamplesTo provide more evidence of the specificity of the RNase activity of GhoS, we performed a whole-transcriptome study for the production of GhoS vs. an empty plasmid so that we could investigate all of the cells transcripts for cleavage with GhoS, in vivo (i.e., BW25113/pCA24N-ghoS vs. BW25113/pCA24N with 1 mM IPTG induction of ghoS for 90 min). Under these conditions, only 20 genes were found to be repressed by more than 4-fold; there were no induced genes. These GhoS-repressed genes were all involved in the biosynthesis/transport of purines and pyrimidines; among them, pyrI was most highly repressed (-20 fold). These results suggest that GhoS selectively cleaves only a few cellular targets.
A new type V toxin-antitoxin system where mRNA for toxin GhoT is cleaved by antitoxin GhoS.
Specimen part, Treatment
View Samples