Epigenetic modifications are associated with inter-species gene expression variation in primates
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens Pan troglodytes Macaca mulatta
PROVIDER: GSE60269 | GEO | 2014/11/09
SECONDARY ACCESSION(S): PRJNA257893
REPOSITORIES: GEO
Similar Datasets
Project description:Dosage compensation in mammals occurs at two levels. In addition to balancing X-chromosome dosage between males and females via X-inactivation, mammals also balance dosage of Xs and autosomes. It has been proposed that X-autosome equalization occurs by upregulation of Xa (active X). To investigate the mechanism, we perform allele-specific ChIP-seq for chromatin epitopes and analyze RNA-seq data (SRA010053). The hypertranscribed Xa demonstrates enrichment of active chromatin marks relative to autosomes. We derive predictive models for relationships among Pol II, active mark densities and gene expression, and we suggest that Xa upregulation involves increased transcription initiation and elongation. Enrichment of active marks on Xa does not scale proportionally with transcription output, a disparity explained by nonlinear quantitative dependencies among active histone marks, Pol II occupancy and transcription. Notably, the trend of nonlinear upregulation also occurs on autosomes. Thus, Xa upregulation involves combined increases of active histone marks and Pol II occupancy, without invoking X-specific dependencies between chromatin states and transcription. Examination of 4 marks of active transcription (H3K4me3, H3K36me3, POL-II-S2P, POL-II-S5P) in a transformed female mouse embryonic fibroblast cell line (EY.T4).
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Project description:Variation in gene regulation is thought to have played an important role in the evolution of primates, and many studies have documented differences in mRNA expression levels across primate species. However, it is not yet known to what extent measurements of divergence in mRNA levels reflect divergence in protein expression levels, which are more directly tied to phenotypic differences. To address this question, we used high-resolution, quantitative mass spectrometry to collect thousands of protein expression measurements from human, chimpanzee, and rhesus macaque lymphoblastoid cell lines (LCLs). We also used RNA sequencing to collect transcript expression data from the same samples. Considering the two datasets jointly we found that there is much more inter-species divergence at the mRNA level than at the protein level. Remarkably, we found dozens of genes with significant expression differences between species at the mRNA level yet little or no difference in protein expression. Overall, our data suggest a much stronger evolutionary constraint on protein expression levels than on mRNA levels. We conclude that inter-species mRNA expression differences may often have limited functional consequences due to either buffering or compensatory changes in post-transcriptional or posttranslational regulation of proteins.
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Project description:It is unclear how epigenetic changes regulate the induction of erythroid-specific genes during terminal erythropoiesis. Here we use global mRNA sequencing (mRNA-seq) and chromatin immunoprecipitation coupled to high-throughput sequencing (CHIP-seq) to investigate the changes that occur in mRNA levels, RNA Polymerase II (Pol II) occupancy and multiple post-translational histone modifications when erythroid progenitors differentiate into late erythroblasts. Among genes induced during this developmental transition, there was an increase in the occupancy of Pol II, the activation marks H3K4me2, H3K4me3, H3K9Ac and H4K16Ac, and the elongation methylation mark H3K79me2. In contrast, genes that were repressed during differentiation showed relative decreases in H3K79me2 levels yet had levels of Pol II binding and active histone marks similar to those in erythroid progenitors. We also found that relative changes in histone modification levels-in particular, H3K79me2 and H4K16ac-were most predictive of gene expression patterns. Our results suggest that in terminal erythropoiesis both promoter and elongation-associated marks contribute to the induction of erythroid genes, while gene repression is marked by changes in histone modifications mediating Pol II elongation. Our data maps the epigenetic landscape of terminal erythropoiesis and suggests that control of transcription elongation regulates gene expression during terminal erythroid differentiation.
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Project description:Variation in gene regulation is thought to have played an important role in the evolution of primates, and many studies have documented differences in mRNA expression levels across primate species. However, it is not yet known to what extent measurements of divergence in mRNA levels reflect divergence in protein expression levels, which are more directly tied to phenotypic differences. To address this question, we used high-resolution, quantitative mass spectrometry to collect thousands of protein expression measurements from human, chimpanzee, and rhesus macaque lymphoblastoid cell lines (LCLs). We also used RNA sequencing to collect transcript expression data from the same samples. Considering the two datasets jointly we found that there is much more inter-species divergence at the mRNA level than at the protein level. Remarkably, we found dozens of genes with significant expression differences between species at the mRNA level yet little or no difference in protein expression. Overall, our data suggest a much stronger evolutionary constraint on protein expression levels than on mRNA levels. We conclude that inter-species mRNA expression differences may often have limited functional consequences due to either buffering or compensatory changes in post-transcriptional or posttranslational regulation of proteins. Gene expression patterns were compared between human, chimpanzee, and rhesus macaque lymphoblastoid cell lines (5 individuals from each species) using RNA-Seq. These gene expression patterns were also compared to protein expression patterns based on mass-spec data, which are available separately (see publication for details).
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Project description:It is unclear how epigenetic changes regulate the induction of erythroid-specific genes during terminal erythropoiesis. Here we use global mRNA sequencing (mRNA-seq) and chromatin immunoprecipitation coupled to high-throughput sequencing (CHIP-seq) to investigate the changes that occur in mRNA levels, RNA Polymerase II (Pol II) occupancy and multiple post-translational histone modifications when erythroid progenitors differentiate into late erythroblasts. Among genes induced during this developmental transition, there was an increase in the occupancy of Pol II, the activation marks H3K4me2, H3K4me3, H3K9Ac and H4K16Ac, and the elongation methylation mark H3K79me2. In contrast, genes that were repressed during differentiation showed relative decreases in H3K79me2 levels yet had levels of Pol II binding and active histone marks similar to those in erythroid progenitors. We also found that relative changes in histone modification levels-in particular, H3K79me2 and H4K16ac-were most predictive of gene expression patterns. Our results suggest that in terminal erythropoiesis both promoter and elongation-associated marks contribute to the induction of erythroid genes, while gene repression is marked by changes in histone modifications mediating Pol II elongation. Our data maps the epigenetic landscape of terminal erythropoiesis and suggests that control of transcription elongation regulates gene expression during terminal erythroid differentiation. Mouse fetal liver cells are double-labeled for erythroid-specific TER119 and non erythroid-specific transferrin receptor (CD71) and then sorted by flow-cytometry. E14.5 fetal livers contain at least five distinct populations of cells (R1 through R5); as they progressively differentiate they gain TER119 and then gain and subsequently lose CD71. CFU-E cells and proerythroblasts make up the R1 population; R2 consists of proerythroblasts and early basophilic erythroblasts; R3 includes early and late basophilic erythroblasts; R4 is mostly polychromatophilic and orthochromatophilic erythroblasts; and R5 is comprised of late orthochromatophilic erythroblasts and reticulocytes. We have sorted for R2-R5 cells for RNA-seq experiment.
2011-09-13 | E-GEOD-32110 | biostudies-arrayexpress
Project description:Glucocorticoids (GCs) are steroid hormones widely used as pharmaceutical interventions, which act mainly by regulating gene expression levels. A large fraction of patients (~30%), especially those of African descent, show a weak response to treatment. To interrogate the contribution of variable transcriptional response to inter-ethnic differences, we measured in vitro lymphocyte GC sensitivity (LGS) and transcriptome-wide response to GCs in peripheral blood mononuclear cells (PBMCs) from African-American and European-American healthy donors. We found that transcriptional response after 8hrs treatment was significantly correlated with variation in LGS within and between populations. We found that NFKB1, a gene previously found to predict LGS within populations, was more strongly downregulated in European-Americans on average. NFKB1 could not completely explain population differences, however, and we found an additional 177 genes with population differences in the average log2 fold change (FDR<0.05), most of which also showed a weaker transcriptional response in AfricanAmericans. These results suggest that inter-ethnic differences in GC sensitivity reflect variation in transcriptional response at many genes, including regulators with large effects (e.g. NFKB1) and numerous other genes with smaller effects. Total RNA was obtained from paired aliquots of peripheral blood mononuclear cells treated with dexamethasone or vehicle (EtOH) for 8 and 24 hours.
2012-02-01 | E-GEOD-33649 | biostudies-arrayexpress
Project description:Dosage compensation in mammals occurs at two levels. In addition to balancing X-chromosome dosage between males and females via X-inactivation, mammals also balance dosage of Xs and autosomes. It has been proposed that X-autosome equalization occurs by upregulation of Xa (active X). To investigate the mechanism, we perform allele-specific ChIP-seq for chromatin epitopes and analyze RNA-seq data (SRA010053). The hypertranscribed Xa demonstrates enrichment of active chromatin marks relative to autosomes. We derive predictive models for relationships among Pol II, active mark densities and gene expression, and we suggest that Xa upregulation involves increased transcription initiation and elongation. Enrichment of active marks on Xa does not scale proportionally with transcription output, a disparity explained by nonlinear quantitative dependencies among active histone marks, Pol II occupancy and transcription. Notably, the trend of nonlinear upregulation also occurs on autosomes. Thus, Xa upregulation involves combined increases of active histone marks and Pol II occupancy, without invoking X-specific dependencies between chromatin states and transcription.
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