DNA damage activates a complex signaling network in cells that blocks cell cycle progression, recruits factors involved in DNA repair, and/or triggers programs that control senescence or programmed cell death. Alterations in chromatin structure are known to be important for the initiation and propagation of the DNA damage response, although the molecular details are unclear. We investigated the role of chromatin structure in the DNA damage response by monitoring multiple timedependent checkpoint signaling and response events with a high-content multiplex image-based RNAi screen of chromatin modifying and interacting genes. We discovered that Brd4, a double bromodomain-containing protein, functions as an endogenous inhibitor of DNA damage signaling by binding to acetylated histones at sites of open chromatin and altering chromatin accessibility. Loss of Brd4 or disruption of acetyl-lysine binding results in an increase in both the number and size of radiation-induced !H2AX nuclear foci while overexpression of a Brd4 splice isoform completely suppresses !H2AX formation, despite equivalent double strand break formation. Brd4 knock-down cells displayed altered chromatin structure, prolonged cell cycle checkpoint arrest and enhanced survival after irradiation, while overexpression of Brd4 isoform B results in enhanced radiationinduced lethality. Brd4 is the target of the t(15;19) chromosomal translocation in a rare form of cancer, NUT Midline Carcinoma. Acetyl lysine-bromodomain interactions of the Brd4-NUT fusion protein suppresses !H2AX foci in discrete nuclear compartments, rendering cells more radiosensitive, mimicking overexpression of Brd4 isoform B. NUT Midline Carcinoma is sensitive to radiotherapy, however tumor material from this rare cancer is scarce. We therefore investigated Brd4 expression in another human cancer commonly treated with radiotherapy, glioblastoma multiforme, and found that expression of Brd4 isoform B correlated specifically with treatment response to radiotherapy. These data implicate Brd4 as an endogenous insulator of DNA damage signaling through recognition of epigenetic modifications in chromatin and suggest that expression of the Brd4 in human cancer can modulate the clinical response to DNA-damaging cancer therapy.
The bromodomain protein Brd4 insulates chromatin from DNA damage signalling.
Cell line
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Transcriptome-wide miR-155 binding map reveals widespread noncanonical microRNA targeting.
Specimen part
View SamplesmicroRNAs (miRNAs) are essential components of gene regulation, but identification of miRNA targets remains a major challenge. Most target prediction and discovery relies on perfect complementarity of the miRNA seed to the 3 untranslated region (UTR). However, it is unclear to what extent miRNAs target sites without seed matches. Here, we performed a transcriptome-wide identification of the endogenous targets of a single miRNAmiR-155in a genetically controlled manner. We found that approximately forty percent of miR-155-dependent Argonaute binding occurs at sites without perfect seed matches. The majority of these non-canonical sites feature extensive complementarity to the miRNA seed with one mismatch. These non-canonical sites confer regulation of gene expression albeit less potently than canonical sites. Thus, non-canonical miRNA binding sites are widespread, often contain seed-like motifs, and can regulate gene expression, generating a continuum of targeting and regulation.
Transcriptome-wide miR-155 binding map reveals widespread noncanonical microRNA targeting.
Specimen part
View SamplesThe import of nuclear transcribed RNAs into mitochondria is an emerging area that presents tremendous opportunity to develop human metabolic therapeutics. However, our knowledge base is quite limited. Much remains to be discovered regarding specific RNA localization and mechanisms of import. In order to identify novel RNAs imported into mitochondria, all RNAs within the mitochondria were characterized using next generation sequencing technology. Several nuclear transcribed RNAs were found within mitochondrial RNA samples, including nuclear ribosomal RNAs, gamma satellite RNA and VL30 retroelement RNA. The presence of these RNAs within mitochondria coupled with RNA sequencing data (RNAseq) from other laboratories investigating mitochondrial RNA processing, lead us to hypothesize that nuclease treatment of mitoplasts is insufficient for removing contaminating cytoplasmic RNAs. In contrast to traditional methodology, mitochondrial import was evaluated by qRT-PCR after stepwise removal of the outer mitochondrial membrane and subsequent lysis of mitochondria. This allowed identification of RNAs lost from the mitochondria with the same kinetics as mtDNA-transcribed RNAs. This approach provided an improved evaluation of nuclear RNA enrichment within mitochondrial membranes in order to characterize nuclease protection and mitochondrial import and identify false-positive detection errors. qRT-PCR results confirmed the presence of VL30 retroelement RNA within mitochondria and question the hypothesis that the RNA component of RNase P is imported. These results illustrate a reliable approach for evaluating the presence of RNAs within mitochondria and open new avenues of investigation relating to mitochondrial RNA biology and in targeting mitochondrial based therapeutics. Overall design: RNA isolated from purified mitoplasts was sequenced on an Illumina Genome Analyzer IIx
Mitochondrially-imported RNA in drug discovery.
No sample metadata fields
View SamplesSingle-cell RNA sequencing has generated the first catalogs of transcriptionally defined neuronal subtypes of the brain. However, the cellular processes that contribute to neuronal subtype specification and transcriptional heterogeneity remain unclear. By comparing the gene expression profiles of a subset of single layer 6 corticothalamic neurons in somatosensory cortex, we show that transcriptional subtypes primarily reflect axonal projection pattern, laminar position within the cortex, and neuronal activity state. Pseudotemporal ordering of 1023 cellular responses to sensory manipulation demonstrates that changes in expression of activity-induced genes both reinforced cell-type identity and contributed to increased transcriptional heterogeneity within each cell type. This is due to cell-type biased choices of transcriptional states following manipulation of neuronal activity. These results reveal that axonal projection pattern, laminar position, and activity state define significant axes of variation that contribute both to the transcriptional identity of individual neurons and to the transcriptional heterogeneity within each neuronal subtype. Overall design: 1023 single cell RNA-Seq and 6 bulk RNA-seq
Variation in Activity State, Axonal Projection, and Position Define the Transcriptional Identity of Individual Neocortical Projection Neurons.
Sex, Specimen part, Cell line, Subject
View SamplesHuman genome-wide Affymetrix GeneChip arrays were used to compare the levels of gene expression in the peripheral blood mononuclear cells (PMBCs) of male patients with post-viral chronic fatigue (n=8) and male healthy control subjects (n=7). Patients and healthy subjects differed significantly in the level of expression of 366 genes. Analysis of the differentially expressed genes indicated functional implications in immune modulation, oxidative stress and apoptosis. Prototype biomarkers were identified on the basis of differential levels of gene expression and possible biological significance. Differential expression of key genes identified in this study offer an insight into the possible mechanism of chronic fatigue following infection. The representative biomarkers identified in this research appear promising as potential biomarkers for diagnosis and treatment.
A gene signature for post-infectious chronic fatigue syndrome.
No sample metadata fields
View SamplesPrevious studies identified a role for latent herpesvirus infection in cross-protection to infection and exacerbation of chronic inflammatory diseases. Here, we compared the gene expression signature from livers, spleens and brains of mice infected with wild-type gammaherpesvirus 68 (MHV68), a mutant virus defective in the establishment of latency (ORF73.stop) or mockulum. We identified over 600 genes differentially expressed in organs of mice latently infected with MHV68 and found distinct sets of genes linked to different pathways were altered in spleen compared to liver. Several of the most differentially expressed latency-specific genes (e.g. IFN, Cxcl9, Ccl5) are associated with known latency-specific phenotypes.
Latent gammaherpesvirus 68 infection induces distinct transcriptional changes in different organs.
Specimen part
View SamplesGenetic variation modulating risk of sporadic Parkinson's disease (PD) has been primarily explored through genome wide association studies (GWAS). However, like many other common genetic diseases, the impacted genes remain largely unknown. Here, we used single-cell RNA-seq to characterize dopaminergic (DA) neuron populations in the mouse brain at embryonic and early postnatal timepoints. These data facilitated unbiased identification of DA neuron subpopulations through their unique transcriptional profiles, including a novel postnatal neuroblast population and substantia nigra (SN) DA neurons. We use these population-specific data to develop a scoring system to prioritize candidate genes in all 49 GWAS intervals implicated in PD risk, including known PD genes and many with extensive supporting literature. As proof of principle, we confirm that the nigrostriatal pathway is compromised in Cplx1 null mice. Ultimately, this systematic approach establishes biologically pertinent candidates and testable hypotheses for sporadic PD, informing a new era of PD genetic research. Overall design: 473 single cell RNA-Seq samples from sorted mouse Th-eGFP+ dopaminergic neurons collected at two timepoints from three distinct brain regions.
Single-Cell RNA-Seq of Mouse Dopaminergic Neurons Informs Candidate Gene Selection for Sporadic Parkinson Disease.
Specimen part, Subject
View SamplesNote: non-normalized values and associated raw data cannot be located by the submitter
Maternal nutrition induces pervasive gene expression changes but no detectable DNA methylation differences in the liver of adult offspring.
Sex, Specimen part
View SamplesPURPOSE:
Unique gene expression profile based on pathologic response in epithelial ovarian cancer.
No sample metadata fields
View Samples