128 results found
Cantone I, Dharmalingam G, Chan Y-W, et al., 2017, Allele-specific analysis of cell fusion-mediated pluripotent reprograming reveals distinct and predictive susceptibilities of human X-linked genes to reactivation, GENOME BIOLOGY, Vol: 18, ISSN: 1474-760X
BACKGROUND: Inactivation of one X chromosome is established early in female mammalian development and can be reversed in vivo and in vitro when pluripotency factors are re-expressed. The extent of reactivation along the inactive X chromosome (Xi) and the determinants of locus susceptibility are, however, poorly understood. Here we use cell fusion-mediated pluripotent reprograming to study human Xi reactivation and allele-specific single nucleotide polymorphisms (SNPs) to identify reactivated loci. RESULTS: We show that a subset of human Xi genes is rapidly reactivated upon re-expression of the pluripotency network. These genes lie within the most evolutionary recent segments of the human X chromosome that are depleted of LINE1 and enriched for SINE elements, predicted to impair XIST spreading. Interestingly, this cadre of genes displays stochastic Xi expression in human fibroblasts ahead of reprograming. This stochastic variability is evident between clones, by RNA-sequencing, and at the single-cell level, by RNA-FISH, and is not attributable to differences in repressive histone H3K9me3 or H3K27me3 levels. Treatment with the DNA demethylating agent 5-deoxy-azacytidine does not increase Xi expression ahead of reprograming, but instead reveals a second cadre of genes that only become susceptible to reactivation upon induction of pluripotency. CONCLUSIONS: Collectively, these data not only underscore the multiple pathways that contribute to maintaining silencing along the human Xi chromosome but also suggest that transcriptional stochasticity among human cells could be useful for predicting and engineering epigenetic strategies to achieve locus-specific or domain-specific human Xi gene reactivation.
Adlakha A, Armstrong-James D, Lenhard B, 2016, Effect of calcineurin inhibition on phenotypic maturation of dendritic cells in an in-vitro model of invasive aspergillosis in lung transplant recipients, Spring Meeting on Clinician Scientists in Training, Publisher: ELSEVIER SCIENCE INC, Pages: 16-16, ISSN: 0140-6736
Adlakha A, Armstrong-James DAJ, Lenhard B, et al., 2016, CALCINEURIN INHIBITION IMPAIRS THE DENDRITIC CELL TRANSCRIPTIONAL RESPONSE TO ASPERGILLUS FUMIGATUS INFECTION IN LUNG TRANSPLANT RECIPIENTS, THORAX, Vol: 71, Pages: A1-A1, ISSN: 0040-6376
Cheung N, Fung TK, Zeisig BB, et al., 2016, Targeting Aberrant Epigenetic Networks Mediated by PRMT1 and KDM4C in Acute Myeloid Leukemia, CANCER CELL, Vol: 29, Pages: 32-48, ISSN: 1535-6108
Transcriptional deregulation plays a major role in acute myeloid leukemia, and therefore identification of epigenetic modifying enzymes essential for the maintenance of oncogenic transcription programs holds the key to better understanding of the biology and designing effective therapeutic strategies for the disease. Here we provide experimental evidence for the functional involvement and therapeutic potential of targeting PRMT1, an H4R3 methyltransferase, in various MLL and non-MLL leukemias. PRMT1 is necessary but not sufficient for leukemic transformation, which requires co-recruitment of KDM4C, an H3K9 demethylase, by chimeric transcription factors to mediate epigenetic reprogramming. Pharmacological inhibition of KDM4C/PRMT1 suppresses transcription and transformation ability of MLL fusions and MOZ-TIF2, revealing a tractable aberrant epigenetic circuitry mediated by KDM4C and PRMT1 in acute leukemia.
Cvetesic N, Dulic M, Bilus M, et al., 2016, Naturally Occurring Isoleucyl-tRNA Synthetase without tRNA-dependent Pre-transfer Editing, JOURNAL OF BIOLOGICAL CHEMISTRY, Vol: 291, Pages: 8618-8631, ISSN: 0021-9258
Isoleucyl-tRNA synthetase (IleRS) is unusual among aminoacyl-tRNA synthetases in having a tRNA-dependent pre-transfer editing activity. Alongside the typical bacterial IleRS (such as Escherichia coli IleRS), some bacteria also have the enzymes (eukaryote-like) that cluster with eukaryotic IleRSs and exhibit low sensitivity to the antibiotic mupirocin. Our phylogenetic analysis suggests that the ileS1 and ileS2 genes of contemporary bacteria are the descendants of genes that might have arisen by an ancient duplication event before the separation of bacteria and archaea. We present the analysis of evolutionary constraints of the synthetic and editing reactions in eukaryotic/eukaryote-like IleRSs, which share a common origin but diverged through adaptation to different cell environments. The enzyme from the yeast cytosol exhibits tRNA-dependent pre-transfer editing analogous to E. coli IleRS. This argues for the presence of this proofreading in the common ancestor of both IleRS types and an ancient origin of the synthetic site-based quality control step. Yet surprisingly, the eukaryote-like enzyme from Streptomyces griseus IleRS lacks this capacity; at the same time, its synthetic site displays the 10(3)-fold drop in sensitivity to antibiotic mupirocin relative to the yeast enzyme. The discovery that pre-transfer editing is optional in IleRSs lends support to the notion that the conserved post-transfer editing domain is the main checkpoint in these enzymes. We substantiated this by showing that under error-prone conditions S. griseus IleRS is able to rescue the growth of an E. coli lacking functional IleRS, providing the first evidence that tRNA-dependent pre-transfer editing in IleRS is not essential for cell viability.
Haberle V, Lenhard B, Haberle V, et al., 2016, Promoter architectures and developmental gene regulation, SEMINARS IN CELL & DEVELOPMENTAL BIOLOGY, Vol: 57, Pages: 11-23, ISSN: 1084-9521
Core promoters are minimal regions sufficient to direct accurate initiation of transcription and are crucial for regulation of gene expression. They are highly diverse in terms of associated core promoter motifs, underlying sequence composition and patterns of transcription initiation. Distinctive features of promoters are also seen at the chromatin level, including nucleosome positioning patterns and presence of specific histone modifications. Recent advances in identifying and characterizing promoters using next-generation sequencing-based technologies have provided the basis for their classification into functional groups and have shed light on their modes of regulation, with important implications for transcriptional regulation in development. This review discusses the methodology and the results of genome-wide studies that provided insight into the diversity of RNA polymerase II promoter architectures in vertebrates and other Metazoa, and the association of these architectures with distinct modes of regulation in embryonic development and differentiation.
Kolder ICRM, van der Plas-Duivesteijn SJ, Tan G, et al., 2016, A full-body transcriptome and proteome resource for the European common carp, BMC GENOMICS, Vol: 17, ISSN: 1471-2164
BACKGROUND: The common carp (Cyprinus carpio) is the oldest, most domesticated and one of the most cultured fish species for food consumption. Besides its economic importance, the common carp is also highly suitable for comparative physiological and disease studies in combination with the animal model zebrafish (Danio rerio). They are genetically closely related but offer complementary benefits for fundamental research, with the large body mass of common carp presenting possibilities for obtaining sufficient cell material for advanced transcriptome and proteome studies. RESULTS: Here we have used 19 different tissues from an F1 hybrid strain of the common carp to perform transcriptome analyses using RNA-Seq. For a subset of the tissues we also have performed deep proteomic studies. As a reference, we updated the European common carp genome assembly using low coverage Pacific Biosciences sequencing to permit high-quality gene annotation. These annotated gene lists were linked to zebrafish homologs, enabling direct comparisons with published datasets. Using clustering, we have identified sets of genes that are potential selective markers for various types of tissues. In addition, we provide a script for a schematic anatomical viewer for visualizing organ-specific expression data. CONCLUSIONS: The identified transcriptome and proteome data for carp tissues represent a useful resource for further translational studies of tissue-specific markers for this economically important fish species that can lead to new markers for organ development. The similarity to zebrafish expression patterns confirms the value of common carp as a resource for studying tissue-specific expression in cyprinid fish. The availability of the annotated gene set of common carp will enable further research with both applied and fundamental purposes.
Mathelier A, Fornes O, Arenillas DJ, et al., 2016, JASPAR 2016: a major expansion and update of the open-access database of transcription factor binding profiles, NUCLEIC ACIDS RESEARCH, Vol: 44, Pages: D110-D115, ISSN: 0305-1048
JASPAR (http://jaspar.genereg.net) is an open-access database storing curated, non-redundant transcription factor (TF) binding profiles representing transcription factor binding preferences as position frequency matrices for multiple species in six taxonomic groups. For this 2016 release, we expanded the JASPAR CORE collection with 494 new TF binding profiles (315 in vertebrates, 11 in nematodes, 3 in insects, 1 in fungi and 164 in plants) and updated 59 profiles (58 in vertebrates and 1 in fungi). The introduced profiles represent an 83% expansion and 10% update when compared to the previous release. We updated the structural annotation of the TF DNA binding domains (DBDs) following a published hierarchical structural classification. In addition, we introduced 130 transcription factor flexible models trained on ChIP-seq data for vertebrates, which capture dinucleotide dependencies within TF binding sites. This new JASPAR release is accompanied by a new web tool to infer JASPAR TF binding profiles recognized by a given TF protein sequence. Moreover, we provide the users with a Ruby module complementing the JASPAR API to ease programmatic access and use of the JASPAR collection of profiles. Finally, we provide the JASPAR2016 R/Bioconductor data package with the data of this release.
Nepal C, Coolen M, Hadzhiev Y, et al., 2016, Transcriptional, post-transcriptional and chromatin-associated regulation of pri-miRNAs, pre-miRNAs and moRNAs, NUCLEIC ACIDS RESEARCH, Vol: 44, Pages: 3070-3081, ISSN: 0305-1048
MicroRNAs (miRNAs) play a major role in the post-transcriptional regulation of target genes, especially in development and differentiation. Our understanding about the transcriptional regulation of miRNA genes is limited by inadequate annotation of primary miRNA (pri-miRNA) transcripts. Here, we used CAGE-seq and RNA-seq to provide genome-wide identification of the pri-miRNA core promoter repertoire and its dynamic usage during zebrafish embryogenesis. We assigned pri-miRNA promoters to 152 precursor-miRNAs (pre-miRNAs), the majority of which were supported by promoter associated post-translational histone modifications (H3K4me3, H2A.Z) and RNA polymerase II (RNAPII) occupancy. We validated seven miR-9 pri-miRNAs by in situ hybridization and showed similar expression patterns as mature miR-9. In addition, processing of an alternative intronic promoter of miR-9-5 was validated by 5' RACE PCR. Developmental profiling revealed a subset of pri-miRNAs that are maternally inherited. Moreover, we show that promoter-associated H3K4me3, H2A.Z and RNAPII marks are not only present at pri-miRNA promoters but are also specifically enriched at pre-miRNAs, suggesting chromatin level regulation of pre-miRNAs. Furthermore, we demonstrated that CAGE-seq also detects 3'-end processing of pre-miRNAs on Drosha cleavage site that correlates with miRNA-offset RNAs (moRNAs) production and provides a new tool for detecting Drosha processing events and predicting pre-miRNA processing by a genome-wide assay.
Tan G, Lenhard B, Tan G, et al., 2016, TFBSTools: an R/bioconductor package for transcription factor binding site analysis, BIOINFORMATICS, Vol: 32, Pages: 1555-1556, ISSN: 1367-4803
UNLABELLED: : The ability to efficiently investigate transcription factor binding sites (TFBSs) genome-wide is central to computational studies of gene regulation. TFBSTools is an R/Bioconductor package for the analysis and manipulation of TFBSs and their associated transcription factor profile matrices. TFBStools provides a toolkit for handling TFBS profile matrices, scanning sequences and alignments including whole genomes, and querying the JASPAR database. The functionality of the package can be easily extended to include advanced statistical analysis, data visualization and data integration. AVAILABILITY AND IMPLEMENTATION: The package is implemented in R and available under GPL-2 license from the Bioconductor website (http://bioconductor.org/packages/TFBSTools/). CONTACT: email@example.com SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.
Adlakha AG, Armstrong-James DPH, Lenhard B, et al., 2015, CALCINEURIN INHIBITION IMPAIRS PHENOTYPIC MATURATION OF DENDRITIC CELLS IN A IN VITRO MODEL OF INVASIVE ASPERGILLOSIS IN LUNG TRANSPLANT RECIPIENTS, Winter Meeting of the British-Thoracic-Society, Publisher: BMJ PUBLISHING GROUP, Pages: A48-A49, ISSN: 0040-6376
Danks GB, Raasholm M, Campsteijn C, et al., 2015, Trans-Splicing and Operons in Metazoans: Translational Control in Maternally Regulated Development and Recovery from Growth Arrest, MOLECULAR BIOLOGY AND EVOLUTION, Vol: 32, Pages: 585-599, ISSN: 0737-4038
Polycistronic mRNAs transcribed from operons are resolved via the trans-splicing of a spliced-leader (SL) RNA. Trans-splicing also occurs at monocistronic transcripts. The phlyogenetically sporadic appearance of trans-splicing and operons has made the driving force(s) for their evolution in metazoans unclear. Previous work has proposed that germline expression drives operon organization in Caenorhabditis elegans, and a recent hypothesis proposes that operons provide an evolutionary advantage via the conservation of transcriptional machinery during recovery from growth arrested states. Using a modified cap analysis of gene expression protocol we mapped sites of SL trans-splicing genome-wide in the marine chordate Oikopleura dioica. Tiled microarrays revealed the expression dynamics of trans-spliced genes across development and during recovery from growth arrest. Operons did not facilitate recovery from growth arrest in O. dioica. Instead, we found that trans-spliced transcripts were predominantly maternal. We then analyzed data from C. elegans and Ciona intestinalis and found that an enrichment of trans-splicing and operon gene expression in maternal mRNA is shared between all three species, suggesting that this may be a driving force for operon evolution in metazoans. Furthermore, we found that the majority of known terminal oligopyrimidine (TOP) mRNAs are trans-spliced in O. dioica and that the SL contains a TOP-like motif. This suggests that the SL in O. dioica confers nutrient-dependent translational control to trans-spliced mRNAs via the TOR-signaling pathway. We hypothesize that SL-trans-splicing provides an evolutionary advantage in species that depend on translational control for regulating early embryogenesis, growth and oocyte production in response to nutrient levels.
Haberle V, Forrest ARR, Hayashizaki Y, et al., 2015, CAGEr: precise TSS data retrieval and high-resolution promoterome mining for integrative analyses, NUCLEIC ACIDS RESEARCH, Vol: 43, Pages: e51-e51, ISSN: 0305-1048
Cap analysis of gene expression (CAGE) is a high-throughput method for transcriptome analysis that provides a single base-pair resolution map of transcription start sites (TSS) and their relative usage. Despite their high resolution and functional significance, published CAGE data are still underused in promoter analysis due to the absence of tools that enable its efficient manipulation and integration with other genome data types. Here we present CAGEr, an R implementation of novel methods for the analysis of differential TSS usage and promoter dynamics, integrated with CAGE data processing and promoterome mining into a first comprehensive CAGE toolbox on a common analysis platform. Crucially, we provide collections of TSSs derived from most published CAGE datasets, as well as direct access to FANTOM5 resource of TSSs for numerous human and mouse cell/tissue types from within R, greatly increasing the accessibility of precise context-specific TSS data for integrative analyses. The CAGEr package is freely available from Bioconductor at http://www.bioconductor.org/packages/release/bioc/html/CAGEr.html.
Harmston N, Baresic A, Lenhard B, et al., 2015, The mystery of extreme non-coding conservation (vol 368, 20130021, 2013), Publisher: ROYAL SOC
Harmston N, Ing-Simmons E, Perry M, et al., 2015, GenomicInteractions: An R/Bioconductor package for manipulating and investigating chromatin interaction data, BMC GENOMICS, Vol: 16, ISSN: 1471-2164
BACKGROUND: Precise quantitative and spatiotemporal control of gene expression is necessary to ensure proper cellular differentiation and the maintenance of homeostasis. The relationship between gene expression and the spatial organisation of chromatin is highly complex, interdependent and not completely understood. The development of experimental techniques to interrogate both the higher-order structure of chromatin and the interactions between regulatory elements has recently lead to important insights on how gene expression is controlled. The ability to gain these and future insights is critically dependent on computational tools for the analysis and visualisation of data produced by these techniques. RESULTS AND CONCLUSION: We have developed GenomicInteractions, a freely available R/Bioconductor package designed for processing, analysis and visualisation of data generated from various types of chromosome conformation capture experiments. The package allows the easy annotation and summarisation of large genome-wide datasets at both the level of individual interactions and sets of genomic features, and provides several different methods for interrogating and visualising this type of data. We demonstrate this package's utility by showing example analyses performed on interaction datasets generated using Hi-C and ChIA-PET.
Ing-Simmons E, Seitan VC, Faure AJ, et al., 2015, Spatial enhancer clustering and regulation of enhancer-proximal genes by cohesin, GENOME RESEARCH, Vol: 25, Pages: 504-513, ISSN: 1088-9051
In addition to mediating sister chromatid cohesion during the cell cycle, the cohesin complex associates with CTCF and with active gene regulatory elements to form long-range interactions between its binding sites. Genome-wide chromosome conformation capture had shown that cohesin's main role in interphase genome organization is in mediating interactions within architectural chromosome compartments, rather than specifying compartments per se. However, it remains unclear how cohesin-mediated interactions contribute to the regulation of gene expression. We have found that the binding of CTCF and cohesin is highly enriched at enhancers and in particular at enhancer arrays or "super-enhancers" in mouse thymocytes. Using local and global chromosome conformation capture, we demonstrate that enhancer elements associate not just in linear sequence, but also in 3D, and that spatial enhancer clustering is facilitated by cohesin. The conditional deletion of cohesin from noncycling thymocytes preserved enhancer position, H3K27ac, H4K4me1, and enhancer transcription, but weakened interactions between enhancers. Interestingly, ∼ 50% of deregulated genes reside in the vicinity of enhancer elements, suggesting that cohesin regulates gene expression through spatial clustering of enhancer elements. We propose a model for cohesin-dependent gene regulation in which spatial clustering of enhancer elements acts as a unified mechanism for both enhancer-promoter "connections" and "insulation."
Ishibashi M, Manning E, Shoubridge C, et al., 2015, Copy number variants in patients with intellectual disability affect the regulation of ARX transcription factor gene, HUMAN GENETICS, Vol: 134, Pages: 1163-1182, ISSN: 0340-6717
Protein-coding mutations in the transcription factor-encoding gene ARX cause various forms of intellectual disability (ID) and epilepsy. In contrast, variations in surrounding non-coding sequences are correlated with milder forms of non-syndromic ID and autism and had suggested the importance of ARX gene regulation in the etiology of these disorders. We compile data on several novel and some already identified patients with or without ID that carry duplications of ARX genomic region and consider likely genetic mechanisms underlying the neurodevelopmental defects. We establish the long-range regulatory domain of ARX and identify its brain region-specific autoregulation. We conclude that neurodevelopmental disturbances in the patients may not simply arise from increased dosage due to ARX duplication. This is further exemplified by a small duplication involving a non-functional ARX copy, but with duplicated enhancers. ARX enhancers are located within a 504-kb region and regulate expression specifically in the forebrain in developing and adult zebrafish. Transgenic enhancer-reporter lines were used as in vivo tools to delineate a brain region-specific negative and positive autoregulation of ARX. We find autorepression of ARX in the telencephalon and autoactivation in the ventral thalamus. Fluorescently labeled brain regions in the transgenic lines facilitated the identification of neuronal outgrowth and pathfinding disturbances in the ventral thalamus and telencephalon that occur when arxa dosage is diminished. In summary, we have established a model for how breakpoints in long-range gene regulation alter the expression levels of a target gene brain region-specifically, and how this can cause subtle neuronal phenotypes relating to the etiology of associated neuropsychiatric disease.
Naville M, Ishibashi M, Ferg M, et al., 2015, Long-range evolutionary constraints reveal cis-regulatory interactions on the human X chromosome, NATURE COMMUNICATIONS, Vol: 6, Pages: 6904-6904, ISSN: 2041-1723
Enhancers can regulate the transcription of genes over long genomic distances. This is thought to lead to selection against genomic rearrangements within such regions that may disrupt this functional linkage. Here we test this concept experimentally using the human X chromosome. We describe a scoring method to identify evolutionary maintenance of linkage between conserved noncoding elements and neighbouring genes. Chromatin marks associated with enhancer function are strongly correlated with this linkage score. We test >1,000 putative enhancers by transgenesis assays in zebrafish to ascertain the identity of the target gene. The majority of active enhancers drive a transgenic expression in a pattern consistent with the known expression of a linked gene. These results show that evolutionary maintenance of linkage is a reliable predictor of an enhancer's function, and provide new information to discover the genetic basis of diseases caused by the mis-regulation of gene expression.
Stadhouders R, Cico A, Stephen T, et al., 2015, Control of developmentally primed erythroid genes by combinatorial co-repressor actions, NATURE COMMUNICATIONS, Vol: 6, Pages: 8893-8893, ISSN: 2041-1723
How transcription factors (TFs) cooperate within large protein complexes to allow rapid modulation of gene expression during development is still largely unknown. Here we show that the key haematopoietic LIM-domain-binding protein-1 (LDB1) TF complex contains several activator and repressor components that together maintain an erythroid-specific gene expression programme primed for rapid activation until differentiation is induced. A combination of proteomics, functional genomics and in vivo studies presented here identifies known and novel co-repressors, most notably the ETO2 and IRF2BP2 proteins, involved in maintaining this primed state. The ETO2-IRF2BP2 axis, interacting with the NCOR1/SMRT co-repressor complex, suppresses the expression of the vast majority of archetypical erythroid genes and pathways until its decommissioning at the onset of terminal erythroid differentiation. Our experiments demonstrate that multimeric regulatory complexes feature a dynamic interplay between activating and repressing components that determines lineage-specific gene expression and cellular differentiation.
Andersson R, Gebhard C, Miguel-Escalada I, et al., 2014, An atlas of active enhancers across human cell types and tissues, NATURE, Vol: 507, Pages: 455-+, ISSN: 0028-0836
Enhancers control the correct temporal and cell-type-specific activation of gene expression in multicellular eukaryotes. Knowing their properties, regulatory activity and targets is crucial to understand the regulation of differentiation and homeostasis. Here we use the FANTOM5 panel of samples, covering the majority of human tissues and cell types, to produce an atlas of active, in vivo-transcribed enhancers. We show that enhancers share properties with CpG-poor messenger RNA promoters but produce bidirectional, exosome-sensitive, relatively short unspliced RNAs, the generation of which is strongly related to enhancer activity. The atlas is used to compare regulatory programs between different cells at unprecedented depth, to identify disease-associated regulatory single nucleotide polymorphisms, and to classify cell-type-specific and ubiquitous enhancers. We further explore the utility of enhancer redundancy, which explains gene expression strength rather than expression patterns. The online FANTOM5 enhancer atlas represents a unique resource for studies on cell-type-specific enhancers and gene regulation.
Regulated transcription controls the diversity, developmental pathways and spatial organization of the hundreds of cell types that make up a mammal. Using single-molecule cDNA sequencing, we mapped transcription start sites (TSSs) and their usage in human and mouse primary cells, cell lines and tissues to produce a comprehensive overview of mammalian gene expression across the human body. We find that few genes are truly 'housekeeping', whereas many mammalian promoters are composite entities composed of several closely separated TSSs, with independent cell-type-specific expression profiles. TSSs specific to different cell types evolve at different rates, whereas promoters of broadly expressed genes are the most conserved. Promoter-based expression analysis reveals key transcription factors defining cell states and links them to binding-site motifs. The functions of identified novel transcripts can be predicted by coexpression and sample ontology enrichment analyses. The functional annotation of the mammalian genome 5 (FANTOM5) project provides comprehensive expression profiles and functional annotation of mammalian cell-type-specific transcriptomes with wide applications in biomedical research.
Haberle V, Li N, Hadzhiev Y, et al., 2014, Two independent transcription initiation codes overlap on vertebrate core promoters, NATURE, Vol: 507, Pages: 381-+, ISSN: 0028-0836
A core promoter is a stretch of DNA surrounding the transcription start site (TSS) that integrates regulatory inputs and recruits general transcription factors to initiate transcription. The nature and causative relationship of the DNA sequence and chromatin signals that govern the selection of most TSSs by RNA polymerase II remain unresolved. Maternal to zygotic transition represents the most marked change of the transcriptome repertoire in the vertebrate life cycle. Early embryonic development in zebrafish is characterized by a series of transcriptionally silent cell cycles regulated by inherited maternal gene products: zygotic genome activation commences at the tenth cell cycle, marking the mid-blastula transition. This transition provides a unique opportunity to study the rules of TSS selection and the hierarchy of events linking transcription initiation with key chromatin modifications. We analysed TSS usage during zebrafish early embryonic development at high resolution using cap analysis of gene expression, and determined the positions of H3K4me3-marked promoter-associated nucleosomes. Here we show that the transition from the maternal to zygotic transcriptome is characterized by a switch between two fundamentally different modes of defining transcription initiation, which drive the dynamic change of TSS usage and promoter shape. A maternal-specific TSS selection, which requires an A/T-rich (W-box) motif, is replaced with a zygotic TSS selection grammar characterized by broader patterns of dinucleotide enrichments, precisely aligned with the first downstream (+1) nucleosome. The developmental dynamics of the H3K4me3-marked nucleosomes reveal their DNA-sequence-associated positioning at promoters before zygotic transcription and subsequent transcription-independent adjustment to the final position downstream of the zygotic TSS. The two TSS-defining grammars coexist, often physically overlapping, in core promoters of constitutively expressed genes to enable the
Mathelier A, Zhao X, Zhang AW, et al., 2014, JASPAR 2014: an extensively expanded and updated open-access database of transcription factor binding profiles, NUCLEIC ACIDS RESEARCH, Vol: 42, Pages: D142-D147, ISSN: 0305-1048
JASPAR (http://jaspar.genereg.net) is the largest open-access database of matrix-based nucleotide profiles describing the binding preference of transcription factors from multiple species. The fifth major release greatly expands the heart of JASPAR-the JASPAR CORE subcollection, which contains curated, non-redundant profiles-with 135 new curated profiles (74 in vertebrates, 8 in Drosophila melanogaster, 10 in Caenorhabditis elegans and 43 in Arabidopsis thaliana; a 30% increase in total) and 43 older updated profiles (36 in vertebrates, 3 in D. melanogaster and 4 in A. thaliana; a 9% update in total). The new and updated profiles are mainly derived from published chromatin immunoprecipitation-seq experimental datasets. In addition, the web interface has been enhanced with advanced capabilities in browsing, searching and subsetting. Finally, the new JASPAR release is accompanied by a new BioPython package, a new R tool package and a new R/Bioconductor data package to facilitate access for both manual and automated methods.
Pascarella G, Lazarevic D, Plessy C, et al., 2014, NanoCAGE analysis of the mouse olfactory epithelium identifies the expression of vomeronasal receptors and of proximal LINE elements, FRONTIERS IN CELLULAR NEUROSCIENCE, Vol: 8, ISSN: 1662-5102
By coupling laser capture microdissection to nanoCAGE technology and next-generation sequencing we have identified the genome-wide collection of active promoters in the mouse Main Olfactory Epithelium (MOE). Transcription start sites (TSSs) for the large majority of Olfactory Receptors (ORs) have been previously mapped increasing our understanding of their promoter architecture. Here we show that in our nanoCAGE libraries of the mouse MOE we detect a large number of tags mapped in loci hosting Type-1 and Type-2 Vomeronasal Receptors genes (V1Rs and V2Rs). These loci also show a massive expression of Long Interspersed Nuclear Elements (LINEs). We have validated the expression of selected receptors detected by nanoCAGE with in situ hybridization, RT-PCR and qRT-PCR. This work extends the repertory of receptors capable of sensing chemical signals in the MOE, suggesting intriguing interplays between MOE and VNO for pheromone processing and positioning transcribed LINEs as candidate regulatory RNAs for VRs expression.
Sharma Y, Chilamakuri CSR, Bakke M, et al., 2014, Computational Characterization of Modes of Transcriptional Regulation of Nuclear Receptor Genes, PLOS ONE, Vol: 9, Pages: e88880-e88880, ISSN: 1932-6203
BACKGROUND: Nuclear receptors are a large structural class of transcription factors that act with their co-regulators and repressors to maintain a variety of biological and physiological processes such as metabolism, development and reproduction. They are activated through the binding of small ligands, which can be replaced by drug molecules, making nuclear receptors promising drug targets. Transcriptional regulation of the genes that encode them is central to gaining a deeper understanding of the diversity of their biochemical and biophysical roles and their role in disease and therapy. Even though they share evolutionary history, nuclear receptor genes have fundamentally different expression patterns, ranging from ubiquitously expressed to tissue-specific and spatiotemporally complex. However, current understanding of regulation in nuclear receptor gene family is still nascent. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we investigate the relationship between long-range regulation of nuclear receptor family and their known functionality. Towards this goal, we identify the nuclear receptor genes that are potential targets based on counts of highly conserved non-coding elements. We validate our results using publicly available expression (RNA-seq) and histone modification (ChIP-seq) data from the ENCODE project. We find that nuclear receptor genes involved in developmental roles show strong evidence of long-range mechanism of transcription regulation with distinct cis-regulatory content they feature clusters of highly conserved non-coding elements distributed in regions spanning several Megabases, long and multiple CpG islands, bivalent promoter marks and statistically significant higher enrichment of enhancer mark around their gene loci. On the other hand nuclear receptor genes that are involved in tissue-specific roles lack these features, having simple transcriptional controls and a greater variety of mechanisms for producing paralogs. We further examine the
Stadhouders R, Aktuna S, Thongjuea S, et al., 2014, HBS1L-MYB intergenic variants modulate fetal hemoglobin via long-range MYB enhancers, JOURNAL OF CLINICAL INVESTIGATION, Vol: 124, Pages: 1699-1710, ISSN: 0021-9738
Genetic studies have identified common variants within the intergenic region (HBS1L-MYB) between GTP-binding elongation factor HBS1L and myeloblastosis oncogene MYB on chromosome 6q that are associated with elevated fetal hemoglobin (HbF) levels and alterations of other clinically important human erythroid traits. It is unclear how these noncoding sequence variants affect multiple erythrocyte characteristics. Here, we determined that several HBS1L-MYB intergenic variants affect regulatory elements that are occupied by key erythroid transcription factors within this region. These elements interact with MYB, a critical regulator of erythroid development and HbF levels. We found that several HBS1L-MYB intergenic variants reduce transcription factor binding, affecting long-range interactions with MYB and MYB expression levels. These data provide a functional explanation for the genetic association of HBS1L-MYB intergenic polymorphisms with human erythroid traits and HbF levels. Our results further designate MYB as a target for therapeutic induction of HbF to ameliorate sickle cell and β-thalassemia disease severity.
Zuin J, Franke V, van IJcken WFJ, et al., 2014, A Cohesin-Independent Role for NIPBL at Promoters Provides Insights in CdLS, PLOS GENETICS, Vol: 10, Pages: e1004153-e1004153, ISSN: 1553-7404
The cohesin complex is crucial for chromosome segregation during mitosis and has recently also been implicated in transcriptional regulation and chromatin architecture. The NIPBL protein is required for the loading of cohesin onto chromatin, but how and where cohesin is loaded in vertebrate cells is unclear. Heterozygous mutations of NIPBL were found in 50% of the cases of Cornelia de Lange Syndrome (CdLS), a human developmental syndrome with a complex phenotype. However, no defects in the mitotic function of cohesin have been observed so far and the links between NIPBL mutations and the observed developmental defects are unclear. We show that NIPBL binds to chromatin in somatic cells with a different timing than cohesin. Further, we observe that high-affinity NIPBL binding sites localize to different regions than cohesin and almost exclusively to the promoters of active genes. NIPBL or cohesin knockdown reduce transcription of these genes differently, suggesting a cohesin-independent role of NIPBL for transcription. Motif analysis and comparison to published data show that NIPBL co-localizes with a specific set of other transcription factors. In cells derived from CdLS patients NIPBL binding levels are reduced and several of the NIPBL-bound genes have previously been observed to be mis-expressed in CdLS. In summary, our observations indicate that NIPBL mutations might cause developmental defects in different ways. First, defects of NIPBL might lead to cohesin-loading defects and thereby alter gene expression and second, NIPBL deficiency might affect genes directly via its role at the respective promoters.
Armant O, Maerz M, Schmidt R, et al., 2013, Genome-wide, whole mount in situ analysis of transcriptional regulators in zebrafish embryos, DEVELOPMENTAL BIOLOGY, Vol: 380, Pages: 351-362, ISSN: 0012-1606
Transcription is the primary step in the retrieval of genetic information. A substantial proportion of the protein repertoire of each organism consists of transcriptional regulators (TRs). It is believed that the differential expression and combinatorial action of these TRs is essential for vertebrate development and body homeostasis. We mined the zebrafish genome exhaustively for genes encoding TRs and determined their expression in the zebrafish embryo by sequencing to saturation and in situ hybridisation. At the evolutionary conserved phylotypic stage, 75% of the 3302 TR genes encoded in the genome are already expressed. The number of expressed TR genes increases only marginally in subsequent stages and is maintained during adulthood suggesting important roles of the TR genes in body homeostasis. Fewer than half of the TR genes (45%, n=1711 genes) are expressed in a tissue-restricted manner in the embryo. Transcripts of 207 genes were detected in a single tissue in the 24h embryo, potentially acting as regulators of specific processes. Other TR genes were expressed in multiple tissues. However, with the exception of certain territories in the nervous system, we did not find significant synexpression suggesting that most tissue-restricted TRs act in a freely combinatorial fashion. Our data indicate that elaboration of body pattern and function from the phylotypic stage onward relies mostly on redeployment of TRs and post-transcriptional processes.
Carvalho RH, Hou J, Haberle V, et al., 2013, Genomewide DNA Methylation Analysis Identifies Novel Methylated Genes in Non-Small-Cell Lung Carcinomas, JOURNAL OF THORACIC ONCOLOGY, Vol: 8, Pages: 562-573, ISSN: 1556-0864
INTRODUCTION: DNA methylation is part of the epigenetic regulatory mechanism present in all normal cells. It is tissue-specific and stably maintained throughout development, but often abnormally changed in cancer. Non-small-cell lung carcinoma (NSCLC) is the most deadly type of cancer, involving different tumor subtypes. This heterogeneity is a challenge for correct diagnosis and patient treatment. The stability and specificity make of DNA methylation a very suitable marker for epigenetic phenotyping of tumors. METHODS: To identify candidate markers for use in NSCLC diagnosis, we used genomewide DNA methylation maps that we had previously generated by MethylCap and next-generation sequencing and listed the most significant differentially methylated regions (DMRs). The 25 DMRs with highest significance in their methylation scores were selected. The methylation status of these DMRs was investigated in 61 tumors and matching control lung tissues by methylation-specific polymerase chain reaction. RESULTS: We found 12 novel DMRs that showed significant differences between tumor and control lung tissues. We also identified three novel DMRs for each of the two most common NSCLC subtypes, adenocarcinomas and squamous cell carcinomas. We propose a panel of five DMRs, composed of novel and known markers that exhibit high specificity and sensitivity to distinguish tumors from control lung tissues. CONCLUSION: Novel markers will aid the development of a highly specific epigenetic panel for accurate identification and subtyping of NSCLC tumors.
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