Differentiating erythroid cells execute a unique gene expression program that insures synthesis of the appropriate proteome at each stage of maturation. Standard expression microarrays provide important insight into erythroid gene expression, but cannot detect qualitative changes in transcript structure, mediated by RNA processing, that alter structure and function of encoded proteins. We analyzed stage-specific changes in the late erythroid transcriptome via use of high resolution microarrays that detect altered expression of individual exons. Ten differentiation-associated changes in erythroblast splicing patterns were identified, including the previously known activation of protein 4.1R exon 16 splicing. Six new alternative splicing switches involving enhanced inclusion of internal cassette exons were discovered, as well as three changes in use of alternative first exons. All of these erythroid stage-specific splicing events represent activated inclusion of authentic annotated exons, suggesting they represent an active regulatory process rather than a general loss of splicing fidelity. The observation that three of the regulated transcripts encode RNA binding proteins (SNRP70, HNRPLL, MBNL2) may indicate significant changes in the RNA processing machinery of late erythroblasts. Together these results support the existence of a regulated alternative pre-mRNA splicing program that is critical for late erythroid differentiation.
Alternative pre-mRNA splicing switches modulate gene expression in late erythropoiesis.
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View SamplesHuman erythroblasts purified from cord blood were cultured in vitro and FACS-sorted into five highly purified populations representing distinct differentiation stages: proerythroblasts, early basophilic erythroblasts, late basophilic erythroblasts, polychromatophilic erythroblasts, and orthochromatophilic erythroblasts. The methods for culture and sorting experiments are given in Hu et al. 2013. For each RNA-seq library, RNA was isolated from 1x 106 sorted human erythroblasts using RNeasy Plus Mini kits (Qiagen). Libraries were then prepared using Illumina TruSeqTM RNA kits to obtain 50 nt reads. Collaborators at the New Your Blood Center were responsible for erythroblast culture, FACS purification of erythroblast populations, and acquisition of RNA-seq data. Collaborators at U.C. Berkeley and Lawrence Berkeley National Laboratory performed data analysis and experimental validation of alternative splicing in erythroblasts. Results: Differentiating erythroblasts execute a dynamic alternative splicing program that is enriched in genes affecting cell cycle, organelle organization, chromatin function, and RNA processing. Alternative splicing plays a major role in regulating gene expression to ensure synthesis of appropriate proteome at each stage as the cells remodel in preparation for production of mature red cells. Overall design: Erythroid differentiation stage-specific transcriptome analysis was performed by RNA-seq analysis of highly purified erythroblast populations
A dynamic alternative splicing program regulates gene expression during terminal erythropoiesis.
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View SamplesWe considered the possibility that removal of E2F4, as a key regulator of cellular quiescence, would cause systemic perturbations in the expression of E2F4 bound genes involved in cell cycle and proliferation. To test whether these pertubrations were reflected in the adult tissues' gene expression programs, we compared the gene expression profile of E2F4 double knockout mice to the gene expression found in identical tissues from E2F4 heterozygous littermates, that are phenotypically normal. We selected liver, testes, and kidney to profile by gene expression analysis, because two of these tissues are affected at some point during development when E2F4 is missing.
Cell cycle genes are the evolutionarily conserved targets of the E2F4 transcription factor.
Sex, Age, Specimen part, Disease, Disease stage, Subject
View SamplesRBFOX over-expression in 293T cells
Rbfox proteins regulate alternative mRNA splicing through evolutionarily conserved RNA bridges.
Disease, Cell line
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Integrative epigenome-wide analysis demonstrates that DNA methylation may mediate genetic risk in inflammatory bowel disease.
Sex, Age, Specimen part, Subject
View SamplesEpigenetic alterations may provide important insights into gene-environment interaction in inflammatory bowel disease (IBD). Here we observe epigenome-wide DNA methylation differences in 240 newly-diagnosed IBD cases and 190 controls. These include 439 differentially methylated positions (DMPs) and 5 differentially methylated regions (DMRs), which we study in detail using whole genome bisulphite sequencing. We replicate the top DMP (RPS6KA2) and DMRs (VMP1, ITGB2, TXK) in an independent cohort.
Integrative epigenome-wide analysis demonstrates that DNA methylation may mediate genetic risk in inflammatory bowel disease.
Sex, Age, Specimen part
View SamplesWe present primary results from the Sequencing Quality Control (SEQC) project, coordinated by the United States Food and Drug Administration. Examining Illumina HiSeq, Life Technologies SOLiD and Roche 454 platforms at multiple laboratory sites using reference RNA samples with built-in controls, we assess RNA sequencing (RNA-seq) performance for sequence discovery and differential expression profiling and compare it to microarray and quantitative PCR (qPCR) data using complementary metrics. At all sequencing depths, we discover unannotated exon-exon junctions, with >80% validated by qPCR. We find that measurements of relative expression are accurate and reproducible across sites and platforms if specific filters are used. In contrast, RNA-seq and microarrays do not provide accurate absolute measurements, and gene-specific biases are observed, for these and qPCR. Measurement performance depends on the platform and data analysis pipeline, and variation is large for transcriptlevel profiling. The complete SEQC data sets, comprising >100 billion reads (10Tb), provide unique resources for evaluating RNA-seq analyses for clinical and regulatory settings.
A comprehensive assessment of RNA-seq accuracy, reproducibility and information content by the Sequencing Quality Control Consortium.
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View SamplesHuntington's disease (HD) is an inherited neurodegenerative disorder caused by an expanded stretch of CAG trinucleotide repeats that results in neuronal dysfunction and death. We made induced pluripotent stem cell (iPSC) lines from HD patients and controls. Though no obvious effects of the CAG expansion on reprogramming or subsequent neural stem cell (NSC) production were seen, HD-NSCs showed CAG expansion-associated gene expression patterns and, upon differentiation, changes in electrophysiology, metabolism, cell adhesion, and ultimately an increased risk of cell death for both medium and longer CAG repeat expansions, with some deficits greater in cells from longer repeat HD NSCs. The HD180 lines were more vulnerable than control lines to cellular stressors and BDNF withdrawal using a range of assays across consortium laboratories. This HD iPSC collection represents a unique and well-characterized resource to elucidate disease mechanisms in HD and provides a novel human stem cell platform for screening new candidate therapeutics.
Induced pluripotent stem cells from patients with Huntington's disease show CAG-repeat-expansion-associated phenotypes.
Specimen part, Disease, Disease stage
View SamplesIn order to study parent-of-origin effects on gene expression, we performed RNAseq analysis (100bp single end reads) of 165 children who formed part of mother/father/child trios where genotype data was available from the HapMap and/or 1000 Genomes Projects. Based on phased genotypes at heterozygous SNP positions, we generated allelic counts for expression of the maternal and paternal alleles in each individual. This analysis reveals significant bias in the expression of the parental alleles for dozens of genes, including both previously known and novel imprinted transcripts. Overall design: This submission contains RNAseq data from 165 children from mother/father/child trios studied as part of the 1000 genomes and/or HapMap projects. We provide raw fastq format reads, and processed read counts per gene. Allelic count information can be provided by directly contacting the authors.
RNA-Seq in 296 phased trios provides a high-resolution map of genomic imprinting.
Specimen part, Cell line, Subject
View SamplesWe performed whole-genome gene expression profiling in Pik3cg-/- mice and subsequent gene ontology clustering of differentially expressed genes compared to wild type mice, in order to investigate the role of Pik3cg in platelet membrane biogenesis and blood coagulation.
Maps of open chromatin guide the functional follow-up of genome-wide association signals: application to hematological traits.
Sex, Specimen part
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