Divergent transcription, in which reverse-oriented transcripts occur upstream of eukaryotic promoters in regions devoid of annotated genes, has been suggested to be a general property of active promoters. Here we show that the human basal RNA polymerase II transcriptional machinery and core promoter are inherently unidirectional, and that reverse-oriented transcripts originate from their own cognate reverse-directed core promoters. In vitro transcription analysis and mapping of nascent transcripts in cells revealed that core promoters are unidirectional and that sequences at reverse start sites are similar to those of their forward counterparts. The use of DNase I accessibility to define proximal promoter borders revealed that about half of promoters are unidirectional and that these unidirectional promoters are depleted at their upstream edges of reverse core promoter sequences and their associated chromatin features. Divergent transcription is thus not an inherent property of the transcription process, but rather the consequence of the presence of both forward- and reverse-directed core promoters. Overall design: Using 5''-GRO-seq and GRO-seq to determine mechanisms of divergent transcription initiation
Human promoters are intrinsically directional.
No sample metadata fields
View SamplesTranscriptome analysis of adult hematopoietic stem cells (HSC) and their progeny has informed our understanding of blood differentiation and leukemogenesis, but a similarly transformative analysis of the embryonic origins of hematopoiesis is lacking. To address this issue, we acquired gene expression profiles of developing HSC purified from over 2500 dissected murine embryos and adult mice, and applied a network biology-based analysis to reconstruct the gene regulatory networks of sequential stages of HSC development. We found that embryonic hematopoietic elements clustered into three distinct transcriptional states characteristic of the definitive yolk sac, HSCs emerging from hemogenic endothelium, and definitive HSCs. We functionally validated several candidate transcriptional regulators of HSC ontogeny by morpholino-mediated knock-down in zebrafish embryos, confirming changes in the expression of HSC markers runx1 and c-myb in the aorta-gonads-mesonephros (AGM), the site of definitive HSC specification. Moreover, we found that HSCs derived from differentiating embryonic stem cells in vitro (ESC-HSC) most closely resemble definitive HSC, yet lack a signature indicative of specification by Notch signaling, which likely accounts for their deficient lymphoid development. Our analysis and accompanying web resource will accelerate the characterization of regulators of HSC ontogeny, facilitate efforts to direct hematopoietic differentiation and cell fate conversion, and serve as a model to study the origins of other adult stem cells.
The transcriptional landscape of hematopoietic stem cell ontogeny.
Specimen part
View SamplesNonsense-mediated mRNA decay (NMD) functions to degrade transcripts bearing premature stop codon (PTC) and is a crucial regulator of gene expression. NMD and the UPF3B gene have been implicated as the cause of various forms of intellectual disability (ID) and other neurological symptoms. Here, we reports three patients with global developmental delay carrying hemizygous deletions of the UPF2 gene, another important member of the NMD pathway and direct interacting partner of UPF3B. Overall design: Using RNA-SEQ on lymphoblastoid cells from UPF2 deletion patients, we identified 1009 differently expressed genes (DEGs). 38% of these DEGs overlapped with DEGs identified in UPF3B patients. More importantly, 95% of all DEGs in either UPF2 or UPF3B patients share the same trend of de-regulation. This demonstrates that the transcriptome deregulation in these two patient groups is similar and that UPF2 should be considered as a new candidate gene for ID in man. We expanded our inq`uiries and performed a comprehensive search for copy number variations (CNVs) encompassing all NMD genes in cohorts of ID patients and controls. We found that UPF2, UPF3A, Y14, SMG6 and EIF4A3 are frequently deleted and/or duplicated in ID patients. These CNVs are likely to be the root of the problems or to act as predisposing factors. Our results suggest that dosage imbalance of NMD factors is associated with ID and further emphasize the importance of NMD in normal learning and memory processes.
Contribution of copy number variants involving nonsense-mediated mRNA decay pathway genes to neuro-developmental disorders.
Cell line, Subject
View SamplesThe severe acute respiratory syndrome (SARS) epidemic was characterized by increased pathogenicity in the elderly due to an early exacerbated innate host response. SARS-CoV is a zoonotic pathogen that entered the human population through an intermediate host like the palm civet. To prevent future introductions of zoonotic SARS-CoV strains and subsequent transmission into the human population, heterologous disease models are needed to test the efficacy of vaccines and therapeutics against both late human and zoonotic isolates. Here we show that both human and zoonotic SARS-CoV strains can infect cynomolgus macaques and resulted in radiological as well as histopathological changes similar to those seen in mild human cases. Viral replication was higher in animals infected with a late human phase isolate compared to a zoonotic isolate. Host responses to the three SARS-CoV strains were similar and only apparent early during infection with the majority of genes associated with interferon signalling pathways.This study characterizes critical disease models in the evaluation and licensure of therapeutic strategies against SARS-CoV for human use
Comparative pathogenesis of three human and zoonotic SARS-CoV strains in cynomolgus macaques.
Specimen part, Time
View SamplesMost human pre-mRNAs are spliced into linear molecules that retain the exon order defined by the genomic sequence. By deep sequencing of RNA from a variety of normal and malignant human cells, we found RNA transcripts from many human genes in which the exons were arranged in a non-canonical order. Statistical estimates and biochemical assays provided strong evidence that a substantial fraction of the spliced transcripts from hundreds of genes are circular RNAs. Our results suggest that a non-canonical mode of RNA splicing, resulting in a circular RNA isoform, is a widespread and perhaps general feature of the gene expression program in human cells. Overall design: 3 samples of non-malignant primary human leukocytes, one replicate each
Circular RNAs are the predominant transcript isoform from hundreds of human genes in diverse cell types.
Specimen part, Subject
View SamplesThe focus of this study was to identify changes in host gene expression induced by the transcription-dependent function of the viral AC2 protein, and induced by the interaction of AC2/C2 with SnRK1.2 (AtAKIN11).
Altered expression of Arabidopsis genes in response to a multifunctional geminivirus pathogenicity protein.
Age, Specimen part, Treatment
View SamplesThe molecular mechanisms regulating endothelial to hematopoietic transition (EHT) of hemogenic endothelium (HE) are poorly understood. Here we profile the transcriptional changes resulting from SOX7 overexpression during EHT Overall design: FLK1+ cells were sorted from day 3.5 iSox7 EBs and cultured in liquid blast media for 48hours. Dox was added for 6, 12 and 24 hours to induce SOX7 expression, before samples were harvested for RNAseq.
Interplay between SOX7 and RUNX1 regulates hemogenic endothelial fate in the yolk sac.
Specimen part, Treatment, Subject, Time
View SamplesThe RNA exosome is fundamental for the degradation of RNA in eukaryotic nuclei. Substrate targeting is facilitated by its co-factor Mtr4p/hMTR4, which links to RNA-binding protein adaptors. One such activity is the human Nuclear EXosome Targeting (NEXT) complex, composed of hMTR4, the Zn-finger protein ZCCHC8 and the RNA-binding factor RBM7. NEXT primarily targets early and unprocessed transcripts, demanding a rationale for how the nuclear exosome recognizes processed RNAs. Here, we describe the PolyA tail eXosome Targeting (PAXT) connection, comprising the hitherto uncharacterized ZFC3H1 Zn-knuckle protein as a central link between hMTR4 and the nuclear polyA binding protein PABPN1. Individual depletion of ZFC3H1 and PABPN1 results in the accumulation of common transcripts, that are generally both longer and more 3'polyadenylated than NEXT substrates. Importantly, ZFC3H1/PABPN1 and ZCCHC8/RBM7 contact hMTR4 in a mutually exclusive manner, revealing that the exosome targets nuclear transcripts of different maturation status by substituting its hMTR4-associating adaptors. Overall design: RNA from HeLa cells was analysed by next generation sequencing upon depletion of EGFP(control), RRP40, RBM7, ZCCHC8, PABPN1 and ZFC3H1. Both total and BrU RNA (one hour labeling) were collected for each condition in triplicates. The spike-in sequences used in the samples can be provided upon request.
Characterizing ZC3H18, a Multi-domain Protein at the Interface of RNA Production and Destruction Decisions.
Specimen part, Subject
View SamplesThe Core Binding Factor (CBF) protein RUNX1 is a master regulator of definitive hematopoiesis, crucial for hematopoietic stem cell (HSC) emergence during ontogeny, which also plays vital roles in adult mice, in regulating the correct specification of numerous blood lineages. Akin to the other mammalian Runx genes, Runx1 has two promoters P1 (distal) and P2 (proximal) which generate distinct protein isoforms. The activities and specific relevance of these two promoters in adult hematopoiesis remain to be fully elucidated. Utilizing a dual reporter model, we demonstrate here that the distal P1 promoter is broadly active in adult hematopoietic stem and progenitor cell (HSPC) populations. By contrast, the activity of the proximal P2 promoter is more restricted and its upregulation, in both the immature Lineage- Sca1high cKithigh (LSK) and bipotential Pre-Megakaryocytic/Erythroid Progenitor (PreMegE) populations, coincides with a loss of erythroid specification. Accordingly, the PreMegE population can be prospectively separated into "pro-erythroid" and "pro-megakaryocyte" populations based on Runx1 P2 activity. Comparative gene expression analyses between Runx1 P2+ and P2- populations indicated that the level of CD34 expression could substitute for P2 activity to distinguish these two cell populations in wild type (WT) bone marrow (BM). Prospective isolation of these two populations will provide the opportunity to further investigate and define the molecular mechanisms involved in megakaryocytic/erythroid (Mk/Ery) cell fate decisions. Moreover, comparison of a RUNX1C null (KO) PreMegE to its WT counterpart demonstrated considerably enhanced erythroid specification at the expense of megakaryopoiesis in the absence of P1-specified RUNX1C expression. Overall design: mRNA profiles of wild type (WT), Runx1 P2-hCD4+ (P2+), Runx1 P2-hCD4- (P2-) and RUNX1C knockout (KO) bone marrow Pre-Megakaryocyte/Erythroid (PreMegE) progenitors were generated from young adult (12-16 weeks) mice by deep sequencing, in triplicate, using Illumina NextSeq 500.
RUNX1B Expression Is Highly Heterogeneous and Distinguishes Megakaryocytic and Erythroid Lineage Fate in Adult Mouse Hematopoiesis.
No sample metadata fields
View SamplesTermination of transcription is important for establishing gene punctuation marks. It is also critical for suppressing many of the pervasive transcription events occurring throughout eukaryotic genomes and coupling their RNA products to efficient decay. In human cells, the ARS2 protein has been implicated in such function as its depletion causes transcriptional read-through of selected gene terminators and because it physically interacts with the ribonucleolytic nuclear RNA exosome. Here, we study the role of ARS2 on transcription and RNA metabolism genome-wide. We show that ARS2 depletion negatively impacts levels of promoter-proximal RNA polymerase II (RNAPII) at protein-coding (pc) genes, Moreover, our results reveal a general role of ARS2 in transcription termination-coupled RNA turnover at short transcription units like snRNA-, replication dependent histone (RDH)-, promoter upstream transcript (PROMPT)- and enhancer RNA (eRNA)-loci. Depletion of the ARS2 interaction partner ZC3H18 mimics the ARS2 depletion, although to a milder extent, whereas depletion of the exosome core subunit RRP40 only impacts RNA abundance post-transcriptionally. Interestingly, ARS2 is also involved in transcription termination events within first introns of pc genes. Our work therefore establishes ARS2 as a general suppressor of pervasive transcription with the potential to regulate protein-coding gene expression. Overall design: RNA from HeLa cells was analysed by next generation sequencing upon depletion of EGFP(control), ARS2(SRRT), ZC3H18 and CBP80. Total RNA was collected for each condition in triplicates.
Characterizing ZC3H18, a Multi-domain Protein at the Interface of RNA Production and Destruction Decisions.
Specimen part, Subject
View Samples