Expression of the yeast Cth2 protein stimulates degradation of mRNAs encoding proteins with Fe-dependent functions in metabolism, in iron storage and in other cellular processes. We demonstrate that in response to Fe deprivation, the Cth2-homologue, Cth1, stimulates specific degradation of mRNAs involved in mitochondrially localized activities that include respiration and amino acid biosynthesis. Furthermore, yeast cells grown under Fe deprivation accumulate mRNAs encoding proteins that function in glucose metabolism. These studies demonstrate a reprogramming of cellular metabolism during Fe-starvation dependent on the coordinated activities of two mRNA binding proteins.
Cooperation of two mRNA-binding proteins drives metabolic adaptation to iron deficiency.
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Induction of the nuclear receptor PPAR-γ by the cytokine GM-CSF is critical for the differentiation of fetal monocytes into alveolar macrophages.
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View SamplesTissue-resident macrophages comprise heterogeneous populations with unique functions and distinct gene expression signatures. While it has been established that they mostly originate from embryonic progenitors, the signals inducing a characteristic tissue-specific differentiation program remain unknown. Here we identify PPAR as the crucial transcription factor determining perinatal alveolar macrophage (AM) development and identity. Development of the fetal monocyte derived AM precursor was largely abrogated in CD11c-Cre/Ppargfl/fl mice. To reveal the underlying changes in gene expression, we performed microarray analysis of sorted WT and KO AM and pre-AM from 3 different timepoints.
Induction of the nuclear receptor PPAR-γ by the cytokine GM-CSF is critical for the differentiation of fetal monocytes into alveolar macrophages.
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View SamplesTissue-resident macrophages comprise heterogeneous populations with unique functions and distinct gene expression signatures. While it has been established that they mostly originate from embryonic progenitors, the signals inducing a characteristic tissue-specific differentiation program remain unknown. Here we identify PPAR as the crucial transcription factor determining perinatal alveolar macrophage (AM) development and identity. Development of the fetal monocyte derived AM precursor was largely abrogated in CD11c-Cre/Ppargfl/fl mice. To reveal the underlying changes in gene expression, we performed microarray analysis of sorted WT and KO AM and pre-AM from 3 different timepoints.
Induction of the nuclear receptor PPAR-γ by the cytokine GM-CSF is critical for the differentiation of fetal monocytes into alveolar macrophages.
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View SamplesThe organization of mammalian DNA replication is poorly understood. We have produced genome-wide high-resolution dynamic maps of the timing of replication in human erythroid, mesenchymal and embryonic stem cells using TimEX, a method that relies on gaussian convolution of massive, highly redundant determinations of DNA copy number variations during S phase obtained using either high-density oligonucleotide tiling arrays or massively-parallel sequencing to produce replication timing profiles. We show that in untransformed human cells, timing of replication is highly regulated and highly synchronous, and that many genomic segments are replicated in temporal transition regions devoid of initiation where replication forks progress unidirectionally from origins that can be hundreds of kilobases away. Absence of initiation in one transition region is shown at the molecular level by SMARD analysis. Comparison of ES and erythroid cells replication patterns revealed that these cells replicate about 20% of their genome in different quarter of S phase and that ES cells replicate a larger proportion of their genome in early S phase than erythroid cells. Importantly, we detected a strong inverse relationship between timing of replication and distance to the closest expressed gene. This relationship can be used to predict tissue specific timing of replication profiles from expression data and genomic annotations. We also provide evidence that early origins of replication are preferentially located near highly expressed genes, that mid firing origins are located near moderately expressed genes and that late firing origins are located far from genes.
Predictable dynamic program of timing of DNA replication in human cells.
Specimen part
View SamplesThe comparative advantages of RNA-Seq and microarrays in transcriptome profiling were evaluated in the context of a comprehensive study design. Gene expression data from Illumina RNA-Seq and Affymetrix microarrays were obtained from livers of rats exposed to 27 agents that comprised of seven modes of action (MOAs); they were split into training and test sets and verified with real time PCR. Overall design: 105 samples were selected from the DrugMatirx tissue/RNA bank that is now owned by the National Toxicology Program (NTP). The samples were split into 2 sets, training and test, to allow for the evaluation of classifiers derived from the data. There were 63 samples in the training set and 42 in the test set. Of the 63 samples in the training set 45 were derived from rats treated with test agent and 18 were control samples (3 sets of 6). 39 of the test set samples were derived from test agent treated animals and 6 were from vehicle and route matched controls. Five MOAs were represented in the training set and 4 MOAs were in the test set. Two of the MOAs were duplicated from the test set and two were without representation in the training set. For each test agent there were three rats treated, in accordance with the common practice in the field of toxicology. For each MOA there were three representative test agents to ensure adequate power for detecting the MOA signatures. 6 samples from the training set had duplicate libraries sequenced and duplicate sequencing runs for the first library. DrugMatrix, National Toxicology program (NTP) Sequencing was carried out in Dr. Charles Wang's Functional Genomics Core at City of Hope Comprehensive Cancer Center, Duarte, CA
Transcriptomic profiling of rat liver samples in a comprehensive study design by RNA-Seq.
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View SamplesDynamic binding of transcription factors to DNA elements specifies gene expression and cell fate, in both normal physiology and disease. To date, our understanding of mammalian gene regulation has been hampered by the difficulty of directly measuring in vivo binding of large numbers of transcription factors to DNA. Here, we develop a high-throughput indexed Chromatin ImmunoPrecipitation (iChIP) method coupled to massively parallel sequencing to systematically map protein-DNA interactions. We apply iChIP to reconstruct the physical regulatory landscape of a mammalian cell, by building genome-wide binding maps for 29 transcription factors (TFs) and chromatin marks at four time points following stimulation of primary dendritic cells (DCs) with pathogen components. Using over 180,000 TF-DNA interactions in these maps, we derive an initial dynamic physical model of a mammalian cell regulatory network. Our data demonstrates that transcription factors vary substantially in their binding dynamics, genomic localization, number of binding events, and degree of interaction with other factors. Further, many of the TF-DNA interactions at stimulus-activated genes are established during differentiation and maintained in a poised state. Functionally, the TFs are organized in a hierarchy of different types: Cell differentiation factors bind most of the genes and remain largely unchanged during the stimulation. A second set of TFs bind already in the un-stimulated and preferentially target induced genes. A third set consists of TF that bind mainly after the stimuli and target specific gene functions. Together these factors determine the magnitude and timing of stimulus induced gene expression. Our method, which allowed us to map routinely temporal binding profiles of dozens of TFs, provides a foundation for future understanding of the mammalian regulatory code. Overall design: A study of dynamic binding of transcription factors in an immune cell following pathogen stimulation
A high-throughput chromatin immunoprecipitation approach reveals principles of dynamic gene regulation in mammals.
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View Samplestreatment of mesenteric lymph nodes with soluble lymphotoxin-beta receptor for 0,1,2,3,27 and 35 days
Lymphotoxin-beta receptor-dependent genes in lymph node and follicular dendritic cell transcriptomes.
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View SamplesTwo human acute lymphoblastic leukemia cell lines (Molt-4 and CCRF-CEM) were treated with direct (A-769662) and indirect (AICAR) AMPK activators. Molt-4 and CCRF-CEM cells were obtained from ATCC (CRL-1582 and CCL-119). Control samples were used for the analysis of metabolic differences between cell lines. Therefore the data was analyzed in combination with, metabolomic data, and the genome-scale reconstruction of human metabolism. For experiments cells were grown in serum-free medium containing DMSO (0.67%) at a cell concentration of 5 x 105 cells/mL.
Prediction of intracellular metabolic states from extracellular metabolomic data.
Cell line, Treatment
View SamplesComparison of follicular dendritic cell-enriched versus -depleted splenocytes
Lymphotoxin-beta receptor-dependent genes in lymph node and follicular dendritic cell transcriptomes.
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