Loop Interrupted: Dysfunctional Chromatin Relations in Neurological Diseases

The majority of genetic variants for psychiatric disorders have been found within non-coding genomic regions. Physical interactions of gene promoters with distant regulatory elements carrying risk alleles may explain how the latter affect gene expression. Recently, whole genome maps of long-range chromosomal contacts from human postmortem brains have been integrated with gene sequence and chromatin accessibility data to decipher disease-specific alterations in chromatin architecture. Cell culture and rodent models provide a causal link between chromatin conformation, long-range chromosomal contacts, gene expression, and disease phenotype. Here, we give an overview of the techniques used to study chromatin contacts and their limitations in brain research. We present evidence for three-dimensional genome changes in physiological brain function and assess how its disturbance contributes to psychiatric disorders. Lastly, we discuss remaining questions and future research directions with a focus on clinical applications.

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Three-Dimensional Genome Organization in Breast and Gynecological Cancers: How Chromatin Folding Influences Tumorigenic Transcriptional Programs

Cells ◽

10.3390/cells11010075 ◽

2021 ◽

Vol 11 (1) ◽

pp. 75

Author(s):

Stephanie I. Nuñez-Olvera ◽

Jonathan Puente-Rivera ◽

Rosalio Ramos-Payán ◽

Carlos Pérez-Plasencia ◽

Yarely M. Salinas-Vera ◽

...

Keyword(s):

Gene Expression ◽

Protein Function ◽

Three Dimensional ◽

Gene Mutations ◽

Regulatory Elements ◽

Specific Gene ◽

Gene Promoters ◽

Nucleotide Polymorphisms ◽

Non Coding Rnas ◽

Insulator Elements

A growing body of research on the transcriptome and cancer genome has demonstrated that many gynecological tumor-specific gene mutations are located in cis-regulatory elements. Through chromosomal looping, cis-regulatory elements interact which each other to control gene expression by bringing distant regulatory elements, such as enhancers and insulators, into close proximity with promoters. It is well known that chromatin connections may be disrupted in cancer cells, promoting transcriptional dysregulation and the expression of abnormal tumor suppressor genes and oncogenes. In this review, we examine the roles of alterations in 3D chromatin interactions. This includes changes in CTCF protein function, cancer-risk single nucleotide polymorphisms, viral integration, and hormonal response as part of the mechanisms that lead to the acquisition of enhancers or super-enhancers. The translocation of existing enhancers, as well as enhancer loss or acquisition of insulator elements that interact with gene promoters, is also revised. Remarkably, similar processes that modify 3D chromatin contacts in gene promoters may also influence the expression of non-coding RNAs, such as long non-coding RNAs (lncRNAs) and microRNAs (miRNAs), which have emerged as key regulators of gene expression in a variety of cancers, including gynecological malignancies.

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Androgen receptor: acting in the three-dimensional chromatin landscape of prostate cancer cells

Hormone Molecular Biology and Clinical Investigation ◽

10.1515/hmbci.2010.055 ◽

2011 ◽

Vol 5 (1) ◽

Author(s):

Harri Makkonen ◽

Jorma J. Palvimo

Keyword(s):

Prostate Cancer ◽

Androgen Receptor ◽

Cancer Cells ◽

Binding Sites ◽

Target Genes ◽

Three Dimensional ◽

Regulatory Elements ◽

Gene Promoters ◽

Loop Formation ◽

Prostate Cancer Cells

AbstractAndrogen receptor (AR) acts as a hormone-controlled transcription factor that conveys the messages of both natural and synthetic androgens to the level of genes and gene programs. Defective AR signaling leads to a wide array of androgen insensitivity disorders, and deregulated AR function, in particular overexpression of AR, is involved in the growth and progression of prostate cancer. Classic models of AR action view AR-binding sites as upstream regulatory elements in gene promoters or their proximity. However, recent wider genomic screens indicate that AR target genes are commonly activated through very distal chromatin-binding sites. This highlights the importance of long-range chromatin regulation of transcription by the AR, shifting the focus from the linear gene models to three-dimensional models of AR target genes and gene programs. The capability of AR to regulate promoters from long distances in the chromatin is particularly important when evaluating the role of AR in the regulation of genes in malignant prostate cells that frequently show striking genomic aberrations, especially gene fusions. Therefore, in addition to the mechanisms of DNA loop formation between the enhancer bound ARs and the transcription apparatus at the target core promoter, the mechanisms insulating distally bound ARs from promiscuously making contacts and activating other than their normal target gene promoters are critical for proper physiological regulation and thus currently under intense investigation. This review discusses the current knowledge about the AR action in the context of gene aberrations and the three-dimensional chromatin landscape of prostate cancer cells.

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Gene-regulatory elements may change the amount, timing, or location of gene expression, cis-Regulation therapy platforms might become a gene therapy to treat many genetic diseases

10.31219/osf.io/xc5a2 ◽

2021 ◽

Author(s):

Moataz Dowaidar

Keyword(s):

Gene Expression ◽

Genetic Diseases ◽

Regulatory Elements ◽

Tissue Type ◽

Gene Promoters ◽

Expression Levels ◽

Cis Regulation ◽

Gene Regulatory Elements ◽

Gene Regulatory ◽

Gene Expression Levels

Changes in gene expression levels above or below a particular threshold may have a dramatic impact on phenotypes, leading to a wide spectrum of human illnesses. Gene-regulatory elements, also known as cis-regulatory elements (CREs), may change the amount, timing, or location (cell/tissue type) of gene expression, whereas mutations in a gene's coding sequence may result in lower or higher gene expression levels resulting in protein loss or gain. Loss-of-function mutations in both genes produce recessive human illness, while haploinsufficient mutations in 65 genes are also known to be deleterious due to function gain, according to the ClinVar1 and ClinGen3 databases. CREs are promoters living near to a gene's transcription start site and switching it on at predefined times, places, and levels. Other distal CREs, like enhancers and silencers, are temporal and tissue-specific control promoters. Enhancers activate promoters, commonly referred to as "promoters," whereas silencers turn them off. Insulators also restrict promiscuous interactions between enhancers and gene promoters. Systematic genomic approaches can help understand the cis-regulatory circuitry of gene expression by highly detecting and functionally defining these CREs. This includes the new use of CRISPR–CRISPR-associated protein 9 (CRISPR–Cas9) and other editing approaches to discover CREs. Cis-Regulation therapy (CRT) provides many promises to heal human ailments. CRT may be used to upregulate or downregulate disease-causing genes due to lower or higher levels of expression, and it may also be used to precisely adjust the expression of genes that assist in alleviating disease features. CRT may employ proteins that generate epigenetic modifications like methylation, histone modification, or gene expression regulation looping. Weighing CRT's advantages and downsides against alternative treatment methods is crucial. CRT platforms might become a practical technique to treat many genetic diseases that now lack treatment alternatives if academics, patient communities, clinicians, regulators and industry work together.

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Control of BMP gene expression by long-range regulatory elements

Cytokine & Growth Factor Reviews ◽

10.1016/j.cytogfr.2009.10.011 ◽

2009 ◽

Vol 20 (5-6) ◽

pp. 509-515 ◽

Cited By ~ 29

Author(s):

Steven Pregizer ◽

Douglas P. Mortlock

Keyword(s):

Gene Expression ◽

Long Range ◽

Regulatory Elements

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Plant Soft Rot Development and Regulation from the Viewpoint of Transcriptomic Profiling

Plants ◽

10.3390/plants9091176 ◽

2020 ◽

Vol 9 (9) ◽

pp. 1176

Author(s):

Ivan Tsers ◽

Vladimir Gorshkov ◽

Natalia Gogoleva ◽

Olga Parfirova ◽

Olga Petrova ◽

...

Keyword(s):

Gene Expression ◽

Plant Cell Wall ◽

Soft Rot ◽

Regulatory Elements ◽

Plant Responses ◽

Gene Promoters ◽

Rna Seq ◽

Induced Plant Responses ◽

Regulatory Systems ◽

Genome Level

Soft rot caused by Pectobacterium species is a devastating plant disease poorly characterized in terms of host plant responses. In this study, changes in the transcriptome of tobacco plants after infection with Pectobacterium atrosepticum (Pba) were analyzed using RNA-Seq. To draw a comprehensive and nontrivially itemized picture of physiological events in Pba-infected plants and to reveal novel potential molecular “players” in plant–Pba interactions, an original functional gene classification was performed. The classifications present in various databases were merged, enriched by “missed” genes, and divided into subcategories. Particular changes in plant cell wall-related processes, perturbations in hormonal and other regulatory systems, and alterations in primary, secondary, and redox metabolism were elucidated in terms of gene expression. Special attention was paid to the prediction of transcription factors (TFs) involved in the disease’s development. Herewith, gene expression was analyzed within the predicted TF regulons assembled at the whole-genome level based on the presence of particular cis-regulatory elements (CREs) in gene promoters. Several TFs, whose regulons were enriched by differentially expressed genes, were considered to be potential master regulators of Pba-induced plant responses. Differential regulation of genes belonging to a particular multigene family and encoding cognate proteins was explained by the presence/absence of the particular CRE in gene promoters.

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Sex Differences in the Epigenome: A Cause or Consequence of Sexual Differentiation of the Brain?

Genes ◽

10.3390/genes10060432 ◽

2019 ◽

Vol 10 (6) ◽

pp. 432 ◽

Cited By ~ 9

Author(s):

Bruno Gegenhuber ◽

Jessica Tollkuhn

Keyword(s):

Gene Expression ◽

Sex Differences ◽

Sexual Differentiation ◽

Hormone Receptors ◽

Neurological Diseases ◽

Activity Patterns ◽

Regulatory Elements ◽

The Body ◽

Epigenetic Mechanism ◽

The Brain

Females and males display differences in neural activity patterns, behavioral responses, and incidence of psychiatric and neurological diseases. Sex differences in the brain appear throughout the animal kingdom and are largely a consequence of the physiological requirements necessary for the distinct roles of the two sexes in reproduction. As with the rest of the body, gonadal steroid hormones act to specify and regulate many of these differences. It is thought that transient hormonal signaling during brain development gives rise to persistent sex differences in gene expression via an epigenetic mechanism, leading to divergent neurodevelopmental trajectories that may underlie sex differences in disease susceptibility. However, few genes with a persistent sex difference in expression have been identified, and only a handful of studies have employed genome-wide approaches to assess sex differences in epigenomic modifications. To date, there are no confirmed examples of gene regulatory elements that direct sex differences in gene expression in the brain. Here, we review foundational studies in this field, describe transcriptional mechanisms that could act downstream of hormone receptors in the brain, and suggest future approaches for identification and validation of sex-typical gene programs. We propose that sexual differentiation of the brain involves self-perpetuating transcriptional states that canalize sex-specific development.

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Cell-Selective Regulation of CFTR Gene Expression: Relevance to Gene Editing Therapeutics

Genes ◽

10.3390/genes10030235 ◽

2019 ◽

Vol 10 (3) ◽

pp. 235 ◽

Cited By ~ 6

Author(s):

Hannah Swahn ◽

Ann Harris

Keyword(s):

Gene Expression ◽

Cystic Fibrosis ◽

Gene Editing ◽

Genetic Diseases ◽

3D Structure ◽

Three Dimensional ◽

Cell Types ◽

Regulatory Elements ◽

Cftr Gene ◽

Specific Expression

The cystic fibrosis transmembrane conductance regulator (CFTR) gene is an attractive target for gene editing approaches, which may yield novel therapeutic approaches for genetic diseases such as cystic fibrosis (CF). However, for gene editing to be effective, aspects of the three-dimensional (3D) structure and cis-regulatory elements governing the dynamic expression of CFTR need to be considered. In this review, we focus on the higher order chromatin organization required for normal CFTR locus function, together with the complex mechanisms controlling expression of the gene in different cell types impaired by CF pathology. Across all cells, the CFTR locus is organized into an invariant topologically associated domain (TAD) established by the architectural proteins CCCTC-binding factor (CTCF) and cohesin complex. Additional insulator elements within the TAD also recruit these factors. Although the CFTR promoter is required for basal levels of expression, cis-regulatory elements (CREs) in intergenic and intronic regions are crucial for cell-specific and temporal coordination of CFTR transcription. These CREs are recruited to the promoter through chromatin looping mechanisms and enhance cell-type-specific expression. These features of the CFTR locus should be considered when designing gene-editing approaches, since failure to recognize their importance may disrupt gene expression and reduce the efficacy of therapies.

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Hepatic gene expression patterns in thyroid hormone-treated hypothyroid rats

Journal of Molecular Endocrinology ◽

10.1677/jme.0.0310291 ◽

2003 ◽

Vol 31 (2) ◽

pp. 291-303 ◽

Cited By ~ 42

Author(s):

JM Weitzel ◽

S Hamann ◽

M Jauk ◽

M Lacey ◽

A Filbry ◽

...

Keyword(s):

Gene Expression ◽

Thyroid Hormone ◽

Expression Patterns ◽

Regulatory Elements ◽

Activation Mechanism ◽

Gene Expression Patterns ◽

Peroxisome Proliferator ◽

Gene Promoters ◽

Protein Levels

Thyroid hormone (T3) is essential for normal development, differentiation and metabolic balance. We have performed DNA microarray experiments using hepatic RNA from hypothyroid and T3-treated hypothyroid rats in order to characterize T3-induced gene expression patterns after various time points (6, 24 and 48 h after the administration of the hormone). Sixty-two of 4608 different genes displayed a reproducible T3-response, and cluster analysis divided these differentially regulated genes into six expression patterns. Thirty-six genes were not significantly regulated within the first 24 h. Transient transfection experiments of eight late-induced gene promoters failed to detect a thyroid hormone response element within their regulatory elements, suggesting an indirect activation mechanism(s). In search for an intermediate factor of T3 action, we examined whether various rather ubiquitous transcription factors, peroxisome proliferator-activated receptors (PPARs) and coactivators of the PPARgamma coactivator 1 family (PGC-1) are regulated by T3. Only PPARgamma and PERC/PGC-1beta exhibit a significant T3-response within the first 6 h after treatment, identifying these factors as candidate components for mediating the late-induced expression pattern. Regulation of early-induced genes within the first 6 h after administration of T3 on transcript levels correlates with altered protein levels after 24 and 48 h in vivo.

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Candidate cancer driver mutations in superenhancers and long-range chromatin interaction networks

10.1101/236802 ◽

2017 ◽

Cited By ~ 4

Author(s):

Lina Wadi ◽

Liis Uusküla-Reimand ◽

Keren Isaev ◽

Shimin Shuai ◽

Vincent Huang ◽

...

Keyword(s):

Gene Expression ◽

Long Range ◽

Target Genes ◽

Tumor Biology ◽

Regulatory Elements ◽

Chromatin Interaction ◽

Driver Mutations ◽

Regulatory Regions ◽

Protein Coding ◽

Primary Tumors

AbstractA comprehensive catalogue of the mutations that drive tumorigenesis and progression is essential to understanding tumor biology and developing therapies. Protein-coding driver mutations have been well-characterized by large exome-sequencing studies, however many tumors have no mutations in protein-coding driver genes. Non-coding mutations are thought to explain many of these cases, however few non-coding drivers besides TERT promoter are known. To fill this gap, we analyzed 150,000 cis-regulatory regions in 1,844 whole cancer genomes from the ICGC-TCGA PCAWG project. Using our new method, ActiveDriverWGS, we found 41 frequently mutated regulatory elements (FMREs) enriched in non-coding SNVs and indels (FDR<0.05) characterized by aging-associated mutation signatures and frequent structural variants. Most FMREs are distal from genes, reported here for the first time and also recovered by additional driver discovery methods. FMREs were enriched in super-enhancers, H3K27ac enhancer marks of primary tumors and long-range chromatin interactions, suggesting that the mutations drive cancer by distally controlling gene expression through threedimensional genome organization. In support of this hypothesis, the chromatin interaction network of FMREs and target genes revealed associations of mutations and differential gene expression of known and novel cancer genes (e.g., CNNB1IP1, RCC1), activation of immune response pathways and altered enhancer marks. Thus distal genomic regions may include additional, infrequently mutated drivers that act on target genes via chromatin loops. Our study is an important step towards finding such regulatory regions and deciphering the somatic mutation landscape of the non-coding genome.

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BAP1 constrains pervasive H2AK119ub1 to control the transcriptional potential of the genome

10.1101/2020.11.13.381251 ◽

2020 ◽

Author(s):

Nadezda A. Fursova ◽

Anne H. Turberfield ◽

Neil P. Blackledge ◽

Emma L. Findlater ◽

Anna Lastuvkova ◽

...

Keyword(s):

Gene Expression ◽

Histone Modifications ◽

Transcription Initiation ◽

Target Genes ◽

Regulatory Elements ◽

Polycomb Group ◽

Gene Promoters ◽

Histone H2a ◽

Gene Regulatory Elements ◽

Gene Regulatory

AbstractHistone-modifying systems play fundamental roles in gene regulation and the development of multicellular organisms. Histone modifications that are enriched at gene regulatory elements have been heavily studied, but the function of modifications that are found more broadly throughout the genome remains poorly understood. This is exemplified by histone H2A mono-ubiquitylation (H2AK119ub1) which is enriched at Polycomb-repressed gene promoters, but also covers the genome at lower levels. Here, using inducible genetic perturbations and quantitative genomics, we discover that the BAP1 deubiquitylase plays an essential role in constraining H2AK119ub1 throughout the genome. Removal of BAP1 leads to pervasive accumulation of H2AK119ub1, which causes widespread reductions in gene expression. We show that elevated H2AK119ub1 represses gene expression by counteracting transcription initiation from gene regulatory elements, causing reductions in transcription-associated histone modifications. Furthermore, failure to constrain pervasive H2AK119ub1 compromises Polycomb complex occupancy at a subset of Polycomb target genes leading to their derepression, therefore explaining the original genetic characterisation of BAP1 as a Polycomb group gene. Together, these observations reveal that the transcriptional potential of the genome can be modulated by regulating the levels of a pervasive histone modification, without the need for elaborate gene-specific targeting mechanisms.

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