Interspecies regulatory landscapes and elements revealed by novel joint systematic integration of human and mouse blood cell epigenomes.

Knowledge of locations and activities of -regulatory elements (CREs) is needed to decipher basic mechanisms of gene regulation and to understand the impact of genetic variants on complex traits. Previous studies identified candidate CREs (cCREs) using epigenetic features in one species, making comparisons difficult between species. In contrast, we conducted an interspecies study defining epigenetic states and identifying cCREs in blood cell types to generate regulatory maps that are comparable between species, using integrative modeling of eight epigenetic features jointly in human and mouse in our Validated Systematic Integration (VISION) Project.

Myeloid leukemia vulnerabilities embedded in long noncoding RNA locus .

The noncoding genome presents a largely untapped source of new biological insights, including thousands of long noncoding RNA (lncRNA) loci. While lncRNA dysregulation has been reported in myeloid malignancies, their functional relevance remains to be systematically interrogated. We performed CRISPRi screens of lncRNA signatures from normal and malignant hematopoietic cells and identified as a myeloid leukemia dependency.

Myo-differentiation reporter screen reveals NF-Y as an activator of PAX3-FOXO1 in rhabdomyosarcoma.

Recurrent chromosomal rearrangements found in rhabdomyosarcoma (RMS) produce the PAX3-FOXO1 fusion protein, which is an oncogenic driver and a dependency in this disease. One important function of PAX3-FOXO1 is to arrest myogenic differentiation, which is linked to the ability of RMS cells to gain an unlimited proliferation potential. Here, we developed a phenotypic screening strategy for identifying factors that collaborate with PAX3-FOXO1 to block myo-differentiation in RMS.

Interspecies regulatory landscapes and elements revealed by novel joint systematic integration of human and mouse blood cell epigenomes.

Knowledge of locations and activities of cis-regulatory elements (CREs) is needed to decipher basic mechanisms of gene regulation and to understand the impact of genetic variants on complex traits. Previous studies identified candidate CREs (cCREs) using epigenetic features in one species, making comparisons difficult between species. In contrast, we conducted an interspecies study defining epigenetic states and identifying cCREs in blood cell types to generate regulatory maps that are comparable between species, using integrative modeling of eight epigenetic features jointly in human and mouse in our Validated Systematic Integration (VISION) Project.

Gene silencing dynamics are modulated by transiently active regulatory elements.

Transcriptional enhancers have been extensively characterized, but cis-regulatory elements involved in acute gene repression have received less attention. Transcription factor GATA1 promotes erythroid differentiation by activating and repressing distinct gene sets. Here, we study the mechanism by which GATA1 silences the proliferative gene Kit during murine erythroid cell maturation and define stages from initial loss of activation to heterochromatinization.

CTCF blocks antisense transcription initiation at divergent promoters.

Transcription at most promoters is divergent, initiating at closely spaced oppositely oriented core promoters to produce sense transcripts along with often unstable upstream antisense transcripts (uasTrx). How antisense transcription is regulated and to what extent it is coordinated with sense transcription is not well understood. Here, by combining acute degradation of the multi-functional transcription factor CTCF and nascent transcription measurements, we find that CTCF specifically suppresses antisense but not sense transcription at hundreds of divergent promoters.

Circadian REV-ERBs repress to activate NAMPT-dependent NAD biosynthesis and sustain cardiac function.

The heart is a highly metabolic organ that uses multiple energy sources to meet its demand for ATP production. Diurnal feeding-fasting cycles result in substrate availability fluctuations which, together with increased energetic demand during the active period, impose a need for rhythmic cardiac metabolism. The nuclear receptors REV-ERBα and β are essential repressive components of the molecular circadian clock and major regulators of metabolism.

Dissection of neuronal splicing and implications for neurodegeneration in X-linked dystonia-parkinsonism.

X-linked dystonia-parkinsonism (XDP) is a monogenic neurodegenerative disorder of the basal ganglia, which presents as a combination of hyperkinetic movements and parkinsonian features. The underlying genetic mechanism involves the insertion of a SINE-VNTR-Alu retrotransposon within the gene. Interestingly, alterations of have been involved in multiple neurological diseases.

CTCF and transcription influence chromatin structure re-configuration after mitosis.

During mitosis, transcription is globally attenuated and chromatin architecture is dramatically reconfigured. We exploited the M- to G1-phase progression to interrogate the contributions of the architectural factor CTCF and the process of transcription to genome re-sculpting in newborn nuclei. Depletion of CTCF during the M- to G1-phase transition alters short-range compartmentalization after mitosis.

Intrinsically disordered Meningioma-1 stabilizes the BAF complex to cause AML.

Meningioma-1 (MN1) overexpression in AML is associated with poor prognosis, and forced expression of MN1 induces leukemia in mice. We sought to determine how MN1 causes AML. We found that overexpression of MN1 can be induced by translocations that result in hijacking of a downstream enhancer.

Distinct properties and functions of CTCF revealed by a rapidly inducible degron system.

CCCTC-binding factor (CTCF) is a conserved zinc finger transcription factor implicated in a wide range of functions, including genome organization, transcription activation, and elongation. To explore the basis for CTCF functional diversity, we coupled an auxin-induced degron system with precision nuclear run-on. Unexpectedly, oriented CTCF motifs in gene bodies are associated with transcriptional stalling in a manner independent of bound CTCF.

Evolution of regulatory signatures in primate cortical neurons at cell-type resolution.

The human cerebral cortex contains many cell types that likely underwent independent functional changes during evolution. However, cell-type-specific regulatory landscapes in the cortex remain largely unexplored. Here we report epigenomic and transcriptomic analyses of the two main cortical neuronal subtypes, glutamatergic projection neurons and GABAergic interneurons, in human, chimpanzee, and rhesus macaque.

Recently Evolved Enhancers Emerge with High Interindividual Variability and Less Frequently Associate with Disease.

Mutations in non-coding regulatory DNA such as enhancers underlie a wide variety of diseases including developmental disorders and cancer. As enhancers rapidly evolve, understanding their function and configuration in non-human disease models can have important clinical applications. Here, we analyze enhancer configurations in tissues isolated from the common marmoset, a widely used primate model for human disease.

Hominin-specific regulatory elements selectively emerged in oligodendrocytes and are disrupted in autism patients.

Speciation is associated with substantial rewiring of the regulatory circuitry underlying the expression of genes. Determining which changes are relevant and underlie the emergence of the human brain or its unique susceptibility to neural disease has been challenging. Here we annotate changes to gene regulatory elements (GREs) at cell type resolution in the brains of multiple primate species spanning most of primate evolution.

Neuronal-specific microexon splicing of mRNA is directly regulated by SRRM4/nSR100.

Neuronal microexons represent the most highly conserved class of alternative splicing events and their timed expression shapes neuronal biology, including neuronal commitment and differentiation. The six-nt microexon 34' is included in the neuronal form of  mRNA, which encodes the largest subunit of the basal transcription factor TFIID. In this study, we investigate the tissue distribution of mRNA and protein and the mechanism responsible for its neuronal-specific splicing.

Mapping the Global Chromatin Connectivity Network for Sox2 Function in Neural Stem Cell Maintenance.

The SOX2 transcription factor is critical for neural stem cell (NSC) maintenance and brain development. Through chromatin immunoprecipitation (ChIP) and chromatin interaction analysis (ChIA-PET), we determined genome-wide SOX2-bound regions and Pol II-mediated long-range chromatin interactions in brain-derived NSCs. SOX2-bound DNA was highly enriched in distal chromatin regions interacting with promoters and carrying epigenetic enhancer marks.

The interdependence of gene-regulatory elements and the 3D genome.

Imaging studies, high-resolution chromatin conformation maps, and genome-wide occupancy data of architectural proteins have revealed that genome topology is tightly intertwined with gene expression. Cross-talk between gene-regulatory elements is often organized within insulated neighborhoods, and regulatory cues that induce transcriptional changes can reshape chromatin folding patterns and gene positioning within the nucleus. The cause-consequence relationship of genome architecture and gene expression is intricate, and its molecular mechanisms are under intense investigation.

Intracranial Aneurysm-Associated Single-Nucleotide Polymorphisms Alter Regulatory DNA in the Human Circle of Willis.

Background And Purpose: Genome-wide association studies significantly link intracranial aneurysm (IA) to single-nucleotide polymorphisms (SNPs) in 6 genomic loci. To gain insight into the relevance of these IA-associated SNPs, we aimed to identify regulatory regions and analyze overall gene expression in the human circle of Willis (CoW), on which these aneurysms develop.

Methods: We performed chromatin immunoprecipitation and sequencing for histone modifications H3K4me1 and H3K27ac to identify regulatory regions, including distal enhancers and active promoters, in postmortem specimens of the human CoW.

Tomo-Seq Identifies SOX9 as a Key Regulator of Cardiac Fibrosis During Ischemic Injury.

Background: Cardiac ischemic injury induces a pathological remodeling response, which can ultimately lead to heart failure. Detailed mechanistic insights into molecular signaling pathways relevant for different aspects of cardiac remodeling will support the identification of novel therapeutic targets.

Methods: Although genome-wide transcriptome analysis on diseased tissues has greatly advanced our understanding of the regulatory networks that drive pathological changes in the heart, this approach has been disadvantaged by the fact that the signals are derived from tissue homogenates.

Circadian networks in human embryonic stem cell-derived cardiomyocytes.

Cell-autonomous circadian oscillations strongly influence tissue physiology and pathophysiology of peripheral organs including the heart, in which the circadian clock is known to determine cardiac metabolism and the outcome of for instance ischemic stress. Human pluripotent stem cells represent a powerful tool to study developmental processes , but the extent to which human embryonic stem (ES) cell-derived cardiomyocytes establish circadian rhythmicity in the absence of a systemic context is unknown. Here we demonstrate that while undifferentiated human ES cells do not possess an intrinsic functional clock, oscillatory expression of known core clock genes emerges spontaneously during directed cardiac differentiation.

Transcriptional Dynamics at Brain Enhancers: from Functional Specialization to Neurodegeneration.

Over the last decade, the noncoding part of the genome has been shown to harbour thousands of cis-regulatory elements, such as enhancers, that activate well-defined gene expression programs. Driven by the development of numerous techniques, many of these elements are now identified in multiple tissues and cell types, and their characteristics as well as importance in development and disease are becoming increasingly clear. Here, we provide an overview of the insights that were gained from the analysis of noncoding gene regulatory elements in the brain and describe their potential contribution to cell type specialization, brain function and neurodegenerative disease.

Epigenomic annotation of gene regulatory alterations during evolution of the primate brain.

Although genome sequencing has identified numerous noncoding alterations between primate species, which of those are regulatory and potentially relevant to the evolution of the human brain is unclear. Here we annotated cis-regulatory elements (CREs) in the human, rhesus macaque and chimpanzee genomes using chromatin immunoprecipitation followed by sequencing (ChIP-seq) in different anatomical regions of the adult brain. We found high similarity in the genomic positioning of rhesus macaque and human CREs, suggesting that the majority of these elements were already present in a common ancestor 25 million years ago.

Local compartment changes and regulatory landscape alterations in histone H1-depleted cells.

Background: Linker histone H1 is a core chromatin component that binds to nucleosome core particles and the linker DNA between nucleosomes. It has been implicated in chromatin compaction and gene regulation and is anticipated to play a role in higher-order genome structure. Here we have used a combination of genome-wide approaches including DNA methylation, histone modification and DNase I hypersensitivity profiling as well as Hi-C to investigate the impact of reduced cellular levels of histone H1 in embryonic stem cells on chromatin folding and function.

Large-scale identification of coregulated enhancer networks in the adult human brain.

Understanding the complexity of the human brain and its functional diversity remain a major challenge. Distinct anatomical regions are involved in an array of processes, including organismal homeostasis, cognitive functions, and susceptibility to neurological pathologies, many of which define our species. Distal enhancers have emerged as key regulatory elements that acquire histone modifications in a cell- and species-specific manner, thus enforcing specific gene expression programs.

Histone acetylation in astrocytes suppresses GFAP and stimulates a reorganization of the intermediate filament network.

Glial fibrillary acidic protein (GFAP) is the main intermediate filament in astrocytes and is regulated by epigenetic mechanisms during development. We demonstrate that histone acetylation also controls GFAP expression in mature astrocytes. Inhibition of histone deacetylases (HDACs) with trichostatin A or sodium butyrate reduced GFAP expression in primary human astrocytes and astrocytoma cells.