Messenger RNA levels in eukaryotes are balanced by two consecutive regulatory layers. Primary, transcriptional regulation at the level of chromatin and secondary, post-transcriptional regulation of the initial transcript in the cytoplasm. Each layer is individually studied in mechanistic detail, while integration of both processes is required to quantify the individual contribution to steady-state RNA levels. Here we show that chromatin features are sufficient to model transcription rate but with different sensitivities in dividing versus post mitotic cells. In both cases chromatin derived transcript levels explains over 80% of variance in measured RNA level enabling to separate transcription from different post-transcriptional processes. By further inclusion of measurements of mRNA half-life and micro RNA expression data we identify a low quantitative contribution of RNA decay by either micro RNA or general differential turnover to final mRNA levels. Together this establishes a chromatin based quantitative model for the contribution of transcriptional and posttranscriptional processes to steady-state levels of messenger RNA.
Chromatin measurements reveal contributions of synthesis and decay to steady-state mRNA levels.
Specimen part, Disease, Treatment, Time
View SamplesThe role of infection in erythropoietic dysfunction is poorly understood. In children with P. falciparum malaria, the by-product of hemoglobin digestion in infected red cells (hemozoin) is associated with the severity of anemia which is independent of circulating levels of the inflammatory cytokine tumor necrosis alpha (TNF-alpha). To gain insight into the common and specific effects of TNF-alpha and hemozoin on erythropoiesis, we studied the gene expression profile of purified primary erythroid cultures exposed to either TNF-alpha (10ng/ml) or to hemozoin (12.5microgram/ml heme units) for 24 hours. Perturbed gene function was assessed using co-annotation of associated gene ontologies and expression of selected genes representative of the profile observed was confirmed by real time PCR (rtPCR). The changes in gene expression induced by each agent were largely distinct; many of the genes significantly modulated by TNF-alpha were not affected by hemozoin.
Distinct mechanisms of inadequate erythropoiesis induced by tumor necrosis factor alpha or malarial pigment.
Specimen part
View SamplesErythropoiesis in mammals replenishes the circulating red blood cell (RBC) pool from hematopoietic stem/progenitor cells (HSPCs). Two distinct erythropoietic programs have been described. In the first trimester, hematopoietic precursors in the fetal yolk sac follow a primitive pattern of erythropoiesis. However, in the second trimester, hematopoietic stem cells (HSCs) from the fetal liver and later from the bone marrow differentiate by a definitive program of erythropoiesis to yield enucleated erythrocytes. RBCs can also be derived from human induced pluripotent stem cells (hiPSCs) and can express many of the red cell proteins required for normal erythrocyte function, presaging in vitro RBC production for clinical use. However, expansion and enucleation from hiPSCs is less efficient than with erythroblasts (EBs) derived from adult or cord blood progenitors. We hypothesized that substantial differential gene expression during erythroid development from hiPSCs compared to that from adult blood or cord blood precursors could account for these hitherto unexplained differences in proliferation and enucleation. We have therefore grown EBs from human adult and cord blood progenitors and from hiPSCs. Gene expression during erythroid culture from each erythroblast source was analyzed using algorithms designed to cluster co-expressed genes in an unsupervised manner and the function of differentially expressed genes explored by gene ontology. Using these methods we identify specific patterns of gene regulation for adult- and cord- derived EBs, regardless of the medium used, that are substantially distinct from those observed during the differentiation of EBs from hiPSC progenitors which largely follows a pattern of primitive erythropoiesis.
Distinct gene expression program dynamics during erythropoiesis from human induced pluripotent stem cells compared with adult and cord blood progenitors.
Specimen part
View SamplesMitochondria are vital due to their principal role in energy production via oxidative phosphorylation (OXPHOS)1. Mitochondria carry their own genome (mtDNA) encoding critical genes involved in OXPHOS, therefore, mtDNA mutations cause fatal or severely debilitating disorders with limited treatment options. 2. Clinical manifestations of mtDNA disease vary based on mutation type and heteroplasmy levels i.e. presence of mutant and normal mtDNA within each cell. 3,4. We evaluated therapeutic concepts of generating genetically corrected pluripotent stem cells for patients with mtDNA mutations. We initially generated multiple iPS cell lines from a patient with mitochondrial encephalomyopathy and stroke-like episodes (MELAS) caused by a heteroplasmic 3243A>G mutation and a patient with Leigh disease carrying a homoplasmic 8993T>G mutation (Leigh-iPS). Due to spontaneous mtDNA segregation in proliferating fibroblasts, isogenic MELAS iPS cell lines were recovered containing exclusively wild type (wt) mtDNA with normal metabolic function. As expected, all iPS cells from the patient with Leigh disease were affected. Using somatic cell nuclear transfer (SCNT; Leigh-NT1), we then simultaneously replaced mutated mtDNA and generated pluripotent stem cells from the Leigh patient fibroblasts. In addition to reversing to a normal 8993G>T, oocyte derived donor mtDNA (human haplotype D4a) in Leigh-NT1 differed from the original haplotype (F1a) at a additional 47 nucleotide sites. Leigh-NT1 cells displayed normal metabolic function compared to impaired oxygen consumption and ATP production in Leigh-iPS cells or parental fibroblasts (Leigh-fib). We conclude that natural segregation of heteroplasmic mtDNA allows the generation of iPS cells with exclusively wild type mtDNA. Moreover, SCNT offers mitochondrial gene replacement strategy for patients with homoplasmic mtDNA disease. Overall design: Duplicate cDNA libraries of fibroblasts from a Leigh patient and a MELAS patient, two sendai produced iPSC lines from the Leigh patient and three sendai produced iPSC lines from the MELAS patient, three fibroblasts lines produced by differentiating three iPS Leigh patient iPSC lines to fibroblasts, two somatic cell nuclear transfer produced NT-ESC lines from the Leigh patient, two fibroblast lines produced by differentiating two Leigh patient NT-ESC lines, four fibroblasts lines produced by differentiating four MELAS patient iPSC lines with the mutation to fibroblasts, four fibroblast lines produced by differentiating two IVF-ESC lines without mutated mtDNA genomes, four fibroblast lines produced by differentiating two somatic cell nuclear transfer NT-ESC lines without mutated mtDNA genomes, and four fibroblasts lines produced by differentiating two MELAS patient iPSC lines without the mutation to fibroblasts. The sequence reads were mapped to hg19 reference genome and hits that passed quality filters were analyzed for differential expression.
Metabolic rescue in pluripotent cells from patients with mtDNA disease.
No sample metadata fields
View SamplesTuberculosis (TB) is responsible for the majority of mortality and morbidity associated with infectious diseases worldwide. The characterization of exact molecular components of immune response associated with protection against TB may help design more effective therapeutic interventions. In this study, we aimed to characterize the immune signature of memory T cells associated with latent infection with Mycobacterium tuberculosis. Transcriptomic profiling using RNA sequencing was performed on memory CD4 and CD8 T cells isolated from individuals with latent tuberculosis, as well as from tuberculosis negative healthy controls. Overall, we found specific gene signatures in each cell subset that could successfully discriminate between individuals with latent tuberculosis and healthy controls. Overall design: RNA-sequencing of sorted memory CD4 and CD8 T cells from cryopreserved PBMC of 10 subjects with latent tuberculosis infection and 10 tuberculosis negative healthy controls
Circulating T cell-monocyte complexes are markers of immune perturbations.
Disease, Disease stage, Subject
View SamplesGrowth and patterning of the face relies on several small buds of tissue, the facial prominences, which surround the primitive mouth. Beginning around E10 of mouse development the prominences undergo rapid growth and morphogenesis. By E11.5 the medial nasal prominences are in close apposition in the midline, as are the maxillary and medial nasal prominences on either side of the developing face. Subsequently, by E12.5 the nasal and maxillary prominences fuse to form a continuous shelf at the front of the face - the primary palate. Individual prominences are associated with specific developmental processes, and this is reflected by patterns of differential gene expression that give the prominences their unique identities. Thus, only the mandibular and maxillary prominences give rise to dentition while the frontonasal prominence has a unique role in olfaction, and the mandibular prominence in taste. We used microarrays to detail the differential gene expression program in each of the mandibular, maxillary, and frontonasal prominences during the key developmental timepoints of E10.0 through E12.5.
Spatial and temporal analysis of gene expression during growth and fusion of the mouse facial prominences.
Specimen part
View SamplesWe mated mice with floxed alleles of both Apc and Pten, to mice with floxed alleles for Arid1a, to obtain female mice with both copies of all three genes floxed. At 7 to 8 weeks of age the right ovarian bursal cavites of the mice were injected with 50 million plaque-forming units of adenovirus expressing Cre recombinase, which causes the floxed genes to be knocked out. Tumor tissue from 3 mice for each group was obtained at necropsy, RNA purified, and targets for Affymetrix arrays synthesized from the mRNAs. We used Affymetrix Mouse Genome 430 2.0 arrays, which hold 45101 probe-sets. Raw data was processed with Robust Multi-array Average algorithm (RMA). Data is log2-transformed transcript abundance estimates. We performed T-tests to compare the 3 vs 3 arrays. We supply a supplementary excel workbook that holds the same data as the data matrix file, but also holds the probe-set annotation at the time we analyzed the data, and some very simple statistical calculations, which select subsets of the probe-sets as differentially expressed. Consumers should consider obtaining more up-to-date probe-set annotation for the array platform. We have also supplied a second supplementary tar archive holding software and files to 1) perform permutation testing of the probe-set selection in order to estimate false discovery rates for the probe-sets we selected as differentially expressed, 2) perform enrichment testing of GO terms, and 3) to perform enrichment testing of KEGG pathways and 3000 curated gene sets from version 4 of the Molecular Signatures Database (MSigDB). The software is in "C".
Arid1a inactivation in an Apc- and Pten-defective mouse ovarian cancer model enhances epithelial differentiation and prolongs survival.
Sex
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