The discovery of significant heterogeneity in the self-renewal durability of adult haematopoietic stem cells (HSCs) has challenged our understanding of the molecules involved in population maintenance throughout life. Gene expression studies in bulk populations are difficult to interpret since multiple HSC subtypes are present and HSC purity is typically less than 50% of the input cell population. Numerous groups have therefore turned to studying gene expression profiles of single HSCs, but again these studies are limited by the purity of the input fraction and an inability to directly ascribe a molecular program to a durable self-renewing HSC. Here we combine single cell functional assays with flow cytometric index sorting and single cell gene expression assays to gain the first insight into the gene expression program of HSCs that possess durable self-renewal. This approach can be used in other stem cell systems and sets the stage for linking key molecules with defined cellular functions. Overall design: single-cell RNA-Seq of haematopoietic stem cells
Combined Single-Cell Functional and Gene Expression Analysis Resolves Heterogeneity within Stem Cell Populations.
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View SamplesA universal feature of the response to stress and nutrient limitation is transcriptional upregulation of genes encoding proteins important for survival. Interestingly, under many of these conditions overall protein synthesis levels are reduced, thereby dampening the stress response at the level of protein expression. For example, during glucose starvation in yeast, translation is rapidly and reversibly repressed, yet transcription of many stress- and glucose-repressed genes is increased. Using ribosome profiling and microscopy, we found that this transcriptionally upregulated gene set consists of two classes: (1) one producing mRNAs that are preferentially translated during glucose limitation and are diffusely localized in the cytoplasm – this class includes many heat shock protein mRNAs; and (2) another producing mRNAs that are poorly translated during glucose limitation, have high rates of translation initiation, and are concentrated in foci that co-localize with P bodies and stress granules – this class is enriched for glucose metabolism mRNAs. Remarkably, the information specifying differential localization and translation of these two classes of mRNAs is encoded in the promoter sequence – promoter responsiveness to heat shock factor (Hsf1) specifies diffuse cytoplasmic localization and preferential translation upon glucose starvation, whereas different promoter elements upstream of genes encoding poorly translated glucose metabolism mRNAs direct these mRNAs to RNA granules under glucose starvation. Thus, promoter sequences and transcription factor binding can influence not only mRNA levels, but also subcellular localization of mRNAs and the efficiency with which they are translated, enabling cells to tailor protein production to environmental conditions. Overall design: Examination of mRNA translation in S. cerevisiae upon glucose starvation.
Promoter sequences direct cytoplasmic localization and translation of mRNAs during starvation in yeast.
Cell line, Treatment, Subject
View SamplesIn S. cerevisiae, the phosphate starvation (PHO) responsive transcription factors Pho4 and Pho2 are jointly required for induction of phosphate response genes and survival in phosphate starvation conditions. In the related human commensal and pathogen C. glabrata, Pho4 is required but Pho2 is dispensable for survival in phosphate-limited conditions and is only partially required for inducing the phosphate response genes. This reduced dependence on Pho2 evolved in C. glabrata and closely related species. Pho4 orthologs that are less dependent on Pho2 induce more genes when introduced into the S. cerevisiae background, and Pho4 in C. glabrata both binds to more sites and induces more genes with expanded functional roles compared to Pho4 in S. cerevisiae. We used RNA-seq to profile the transcriptome of wild type and mutants of Pho4 / Pho2, or Pho4 ortholog swap in S. cerevisiae, to identify genes induced by Pho4 or its orthologs in S. cerevisiae background. Overall design: The goal is to identify genes induced by each of the eight Pho4 orthologs in the S. cerevisiae background, either with or without S. cerevisiae Pho2 (ScPho2) and with the negative regulator of Pho4, Pho80, deleted. Pairwise comparisons such as that between a S. cerevisiae strain carrying Pho4 from C. glabrata (CgPho4) and a pho4? strain, both in the pho80? ScPHO2 background, will identify genes induced by CgPho4 in the presence of ScPho2. For each strain, two biological replicates, i.e. the same genotype grown, collected and processed separately, were analyzed by RNA-seq.
Evolution of reduced co-activator dependence led to target expansion of a starvation response pathway.
Subject
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 SamplesStudies have reported opposing effects of high-fat diet and mechanical stimulation on lineage commitment of the bone marrow stem cells. Yet, how the bone marrow modulates its gene expression in response to the combined effects of mechanical loading and a high-fat diet has not yet been addressed. We investigated whether early-life voluntary physical activity can modulate the effects of a high-fat diet on body composition, bone phenotype and bone marrow gene expression in male Sprague Dawley rats. We show that early-life high-fat diet positively affected body weight, total fat percentage and bone mass indices. In the bone marrow, early-life high-fat diet resulted in adipocyte hypertrophy and a pro-inflammatory and pro-adipogenic gene expression profile. Crucially, the bone marrow of the rats that undertook wheel exercise while on a high-fat diet retained a memory of the early-life exercise. This memory lasted at least 60 days after the cessation of the voluntary exercise and was manifest by: 1) the bone marrow adipocyte size of the exercised rats not exhibiting hypertrophy; and 2) genes associated with mature adipocyte function being down-regulated. Our results are consistent with the marrow adipose tissue having a unique and long-lasting response to high-fat feeding in the presence or absence of exercise. Overall design: Eighty male SD rats were randomised at weaning into : chow-fed group (C-SED) or a high-fat fed group. The high-fat fed group was further divided into three sub-groups: the high-fat sedentary (HF-SED) group, the high-fat late-exercise (HF-LEX) group, and the high-fat early-exercise (HF-EEX) group. At day 120-123, the animals were culled and total RNA was extracted from the bone marrow of the femur. The RNA was sequenced using Illumina Hiseq4000 technology. Differential gene expression analysis was carried out using Tuxedo suite of bioinformatic tools.
A Memory of Early Life Physical Activity Is Retained in Bone Marrow of Male Rats Fed a High-Fat Diet.
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View SamplesFull title: Genome-wide expression profiles of primary human small airway epithelial cells (SAECs) infected with different adenovirus mutants.
Heterochromatin silencing of p53 target genes by a small viral protein.
Specimen part
View SamplesIn the normal mouse the pituitary gonadotrophins determine development, maturation and physiological regulation of the testis with follicle-stimulating hormone (FSH) activating the Sertoli cell and luteinising hormone (LH) the Leydig cell. To look at the potential interaction of cell types within the testis following hormone stimulation we have investigated the effect of rFSH on testicular gene expression in the hypogonadal (hpg) male mouse. Due to a deletion in the gene encoding gonadotrophin-releasing hormone (GnRH), FSH and LH levels are at the lower limit of detection in the circulation and mice remain in a pre-pubertal state throughout life unless given exogenous hormone.
Effects of FSH on testicular mRNA transcript levels in the hypogonadal mouse.
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View SamplesMethods: Triplicate RNA samples from morphologically stage-matched embryos were sequenced to compare expression profiles over time. Strand-specific libraries were prepared using the TruSeq stranded total RNA-ribozero kit (Illumina) and 100-bp paired-end sequencing was performed to depth of 10 million reads per library on an Illumina HiSeq 2000. Methods: On average, 19 million 100 bp paired-end reads per library were generated. These were then adapter and quality trimmed using cutadapt and SolexaQA. Each sequencing data set was independently mapped to the zebrafish genome with a bowtie2 index generated from Danio_rerio.Zv9.70 (Ensembl) downloaded from Illumina's iGenomes collection. Zebrafish genome danRer7was used to provide known transcript annotations from Ensembl using TopHat2 (version 2.0.9) with the following options: “tophat2 --GTF genes.gtf --library-type fr-firststrand -p 24 --mate-inner-dist -8 --mate-std-dev 6 zv9” (on average, 75.38% reads mapped uniquely to the genome). Transcriptomes were assembled with Cufflinks (version 2.2.0) using options: 'cufflinks -p 32 --GTF genes.gtf' and differential expression analysis between control and knockdown embryos was performed using Cuffdiff. A FDR corrected p-value of 0.05 was applied as the cut off to identify differentially regulated transcripts Results: We could show that MO assisted depletion of Rad21 and CTCF affected the transcriptional profiles of embryos in different ways. Overall design: mRNA profiles of (2.5, 3.3, 4.5, 5.3, 10 hpf) wild type (WT) and morpholino depleted Rad21 MO (Rad21) and CTCF MO (CTCF) embryos were generated by deep sequencing, in triplicate, using Illumina HiSeq 2000.
Cohesin facilitates zygotic genome activation in zebrafish.
No sample metadata fields
View SamplesType 1 IFNs can conditionally activate all of the signal transducers and activators of transcription molecules (STATs), including STAT4. The best-characterized signaling pathways use STAT1, however, and type 1 IFN inhibition of cell proliferation is STAT1 dependent. We report that type 1 IFNs can basally stimulate STAT1- and STAT4- dependent effects in CD8 T cells, but that CD8 T cells responding to infections of mice with lymphocytic choriomenigitis virus have elevated STAT4 and lower STAT1 expression with significant consequences for modifying the effects of type 1 IFN exposure. The phenotype was associated with preferential type 1 IFN activation of STAT4 as compared to STAT1. Stimulation through the TCR induced elevated STAT4 expression, and STAT4 was required for peak expansion of antigen-specific CD8 T cells, low STAT1 levels, and resistance to type 1 IFN-mediated inhibition of proliferation. Thus, a mechanism is discovered for regulating the consequences of type 1 IFN exposure in CD8 T cells, with STAT4 acting as a key molecule in driving optimal antigen-specific responses and overcoming STAT1-dependent inhibition of proliferation.
Regulating type 1 IFN effects in CD8 T cells during viral infections: changing STAT4 and STAT1 expression for function.
Age, Specimen part, Treatment
View SamplesThe oncogenic mechanisms and tumour biology underpinning Clear Cell Sarcoma of Kidney (CCSK), the second commonest paediatric renal malignancy, are poorly understood and currently therapy depends heavily on Doxorubicin with cardiotoxic side-effects. Previously, we characterised the balanced t(10;17)(q22;p13) chromosomal translocation, identified at that time as the only recurrent genetic aberration in CCSK. This translocation results in an in-frame fusion of the YWHAE (encoding 14-3-3e) and NUTM2 genes, with a somatic incidence of 12%. Clinico-pathological features of that cohort suggested that this aberration might be associated with higher stage and grade disease. Since no primary CCSK cell line exists, we generated various stably transfected cell lines containing doxycycline-inducible HA-tagged-YWHAE-NUTM2, in order to study the effect of expressing this transcript. 14-3-3e-NUTM2-expressing cells exhibited significantly greater cell migration compared to mock-treated controls. Gene and protein expression studies conducted in parallel on this model system suggested dysregulation of signalling pathways as a basis to the migration changes. Importantly, by blocking these signalling pathways using anti-EGFR, anti-IGF1R and anti-PDGFa neutralising antibodies, the migratory advantage conferred by transcript expression was abrogated. These results support 14-3-3e-NUTM2 expression as a contributor to CCSK tumorigenesis and provide avenues for the exploration of novel therapeutic approaches in CCSK.
Dysregulated mitogen-activated protein kinase signalling as an oncogenic basis for clear cell sarcoma of the kidney.
Disease, Cell line
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