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SRP041039
Saccharomyces cerevisiae
37 Downloadable Samples
Illumina Genome Analyzer II, Illumina HiSeq 2000
Description
A 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.
Publication Title
Promoter sequences direct cytoplasmic localization and translation of mRNAs during starvation in yeast.
Sample Metadata Fields
Cell line, Treatment, Subject
View Samples- Saccharomyces cerevisiae
- 36 Downloadable Samples
- Illumina HiSeq 2000
Description
In 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.
Publication Title
Evolution of reduced co-activator dependence led to target expansion of a starvation response pathway.
Sample Metadata Fields
Subject
View Samples- Homo sapiens
- 34 Downloadable Samples
- Illumina HiSeq 2500
Description
Limitation 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.
Publication Title
Translational Control through Differential Ribosome Pausing during Amino Acid Limitation in Mammalian Cells.
Sample Metadata Fields
Cell line, Subject
View Samples- Homo sapiens
- 17 Downloadable Samples
Affymetrix Human Exon 1.0 ST Array [transcript (gene) version (huex10st)
Description
Full title: Genome-wide expression profiles of primary human small airway epithelial cells (SAECs) infected with different adenovirus mutants.
Publication Title
Heterochromatin silencing of p53 target genes by a small viral protein.
Sample Metadata Fields
Specimen part
View Samples- Mus musculus
- 25 Downloadable Samples
- Affymetrix Mouse Expression 430A Array (moe430a)
Description
Type 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.
Publication Title
Regulating type 1 IFN effects in CD8 T cells during viral infections: changing STAT4 and STAT1 expression for function.
Sample Metadata Fields
Age, Specimen part, Treatment
View Samples- Mus musculus
- 22 Downloadable Samples
- NextSeq 500
Description
Analysis of gene expression by astrocytes or non-astrocyte cells in spinal cord injury (SCI) lesions may lead to the identification of molecules that impact on axon regrowth. We conducted genome-wide RNA sequencing of (i) immunoprecipitated astrocyte-specific ribosome-associated RNA (ramRNA) from WT or STAT3-CKO astrocytes, and (ii) the non-precipitated (flow-through) RNA deriving from non-astrocyte cells in the same tissue samples 14 days following SCI. DOI: 10.1038/nature17623 Overall design: Young adult female mGFAP-Cre-RiboTag or mGFAP-Cre-RiboTag-STAT3-LoxP mice underwent severe crush SCI at thoracic level 10. 14 days following SCI, the central 3mm of the SCI lesion was extracted, homogenized and (i) astrocyte-specific ribosome-associated RNA (ramRNA) precipitated via a hemagglutinin (HA) tag targeted to either WT (n=4) or STAT3-CKO (n=3) astrocytes, and (ii) the non-precipitated (flow-through) RNA deriving from non-astrocyte cells in the same tissue samples. Sex and age-matched mGFAP-Cre-RiboTag mice served as uninjured controls (n=4).
Publication Title
Astrocyte scar formation aids central nervous system axon regeneration.
Sample Metadata Fields
Specimen part, Subject
View Samples- Mus musculus
- 12 Downloadable Samples
- Affymetrix Mouse Genome 430 2.0 Array (mouse4302)
Description
GM-CSF controls the development of granulocytes but little is known about the contribution of the downstream mediating transcription factor STAT5A/B. To elucidate this pathway, we generated mice lacking the Stat5a and 5b genes in blood cells. Peripheral neutrophils were decreased and administration of 5-FU and GM-CSF failed to induce granulopoiesis in Stat5a/b-mutant mice. GMPs were isolated and cultured with GM-CSF. Both the number and size of STAT5A/B-null colonies were reduced and GM-CSF-induced survival of mature STAT5A/B-null neutrophils was impaired. Time-lapse cinematography and single cell tracking of GMPs revealed that STAT5A/B-null cells were characterized by a longer generation time and an increased cell death. Gene expression profiling experiments suggested that STAT5A/B directs GM-CSF signaling through the regulation of cell survival genes.
Publication Title
The transcription factors STAT5A/B regulate GM-CSF-mediated granulopoiesis.
Sample Metadata Fields
No sample metadata fields
View Samples- Mus musculus
- 6 Downloadable Samples
- Affymetrix Mouse Genome 430 2.0 Array (mouse4302)
Description
Follicular T helper cells (Tfh) are critical for providing help to B cells for germinal center (GC) formation. Mutations affecting SAP prevent GC formation due to defective T:B cell interactions, yet effects on Tfh cell differentiation remain unclear. We describe the in vitro differentiation of functionally competent Tfh-like cells that expressed IL-21, Tfh markers, and Bcl6, and rescued GC formation in SAP-deficient hosts substantially better than other T helper (Th) cells. SAP-deficient Tfh-like cells appeared virtually indistinguishable from wildtype, yet failed to support GCs in vivo. Interestingly, both Tfh-like and in vivo-derived Tfh cells could produce effector cytokines in response to polarizing conditions. Moreover, other Th cell populations could be reprogrammed to obtain Tfh characteristics. ChIP-Seq analyses revealed positive epigenetic markings on Tbx21, Gata3 and Rorc in Tfh-like and ex vivo Tfh cells, and Bcl6 in other Th cells, supporting the concept of plasticity between Tfh and other Th populations.
Publication Title
Functional and epigenetic studies reveal multistep differentiation and plasticity of in vitro-generated and in vivo-derived follicular T helper cells.
Sample Metadata Fields
Specimen part
View Samples- Mus musculus
- 75 Downloadable Samples
- NextSeq 500, Illumina HiSeq 2500
Description
IL-7 regulates homeostatic mechanisms that maintain the overall size of the T cell pool throughout life. We show that, under steady-state conditions, IL-7 signaling is principally mediated by activation of signal transducers and activators of transcription 5 (STAT5). In contrast, under lymphopenic conditions, there is a modulation of STAT1 expression resulting in an IL-7-dependent STAT1 and STAT5 activation. Consequently, the IL-7-induced transcriptome is altered with enrichment of IFN-stimulated genes (ISGs). Moreover, STAT1 overexpression was associated with reduced survival in CD4+ T cells undergoing lymphopenia-induced proliferation (LIP). We propose a model in which T cells undergoing LIP upregulate STAT1 protein, "switching on" an alternate IL-7-dependent program. This mechanism could be a physiological process to regulate the expansion and size of the CD4+ T cell pool. During HIV infection, the virus could exploit this pathway, leading to the homeostatic dysregulation of the T cell pools observed in these patients. Overall design: Sorted naive CD4 T and CD8 T cells from WT or STAT1 transgenic mice were stimulated for 90 minutes with IL-7 or IFNg. Additonally CD4 T cells from WT or STAT1 trangenic or IL7Ra449F transgenic mice were stimulated for overnight with IL-7 or IFNg or IFNa4. Up to four biological replicates tested for each condition.
Publication Title
IL-7-dependent STAT1 activation limits homeostatic CD4+ T cell expansion.
Sample Metadata Fields
Cell line, Subject
View Samples- Mus musculus
- 16 Downloadable Samples
- Affymetrix Mouse Genome 430 2.0 Array (mouse4302)
Description
STAT3, an essential transcription factor with pleiotropic functions, plays critical roles in the pathogenesis of autoimmunity. Despite recent data linking STAT3 with inflammatory bowel disease, exactly how it contributes to chronic intestinal inflammation is not known. Using a T cell transfer model of colitis we found that STAT3 expression in T cells was essential for the induction of both colitis and systemic inflammation. STAT3 was critical in modulating the balance of T helper 17 (Th17) and regulatory T (Treg) cells, as well as in promoting CD4+ T cell proliferation. We used chromatin immunoprecipitation and massive parallel sequencing (ChIP-Seq) to define the genome-wide targets of STAT3 in CD4+ T cells. We found that STAT3 bound to multiple genes involved in Th17 cell differentiation, cell activation, proliferation and survival, regulating both expression and epigenetic modifications. Thus, STAT3 orchestrates multiple critical aspects of T cell function in inflammation and homeostasis.
Publication Title
Diverse targets of the transcription factor STAT3 contribute to T cell pathogenicity and homeostasis.
Sample Metadata Fields
Specimen part
View Samples