scholarly journals Cohesin promotes stochastic domain intermingling to ensure proper regulation of boundary-proximal genes

2019 ◽  
Author(s):  
Jennifer M. Luppino ◽  
Daniel S. Park ◽  
Son C. Nguyen ◽  
Yemin Lan ◽  
Zhuxuan Xu ◽  
...  
Keyword(s):  
Mechanistic Explanation ◽  
Regulatory Elements ◽  
Chromosome Conformation ◽  
Regulatory Domains ◽  
Domain Interactions ◽  
Topologically Associated Domains ◽  
Self Association ◽  
Cornelia De Lange ◽  
Transcriptional Bursting ◽  
And Function

AbstractThe mammalian genome can be segmented into thousands of topologically associated domains (TADs) based on chromosome conformation capture studies, such as Hi-C. TADs have been proposed to act as insulated neighborhoods, spatially sequestering and insulating the enclosed genes and regulatory elements through chromatin looping and self-association. Recent results indicate that inter-TAD interactions can also occur, suggesting boundaries may be semi-permissible. However, the nature, extent, and function, if any, of these inter-TAD interactions remains unclear. Here, we combine super-and high-resolution microscopy with Oligopaint technology to precisely quantify the interaction frequency within and between neighboring domains in human cells. We find that intermingling across domain boundaries is a widespread feature of the human genome, with varying levels of interactions across different loci that correlate with their differing boundary strengths by Hi-C. Moreover, we find that cohesin depletion, which is known to abolish TADs at the population-average level, does not induce ectopic interactions but instead reduces both intra- and inter-domain interactions to a similar extent. Reduced chromatin intermixing due to cohesin loss affects domain incorporation and transcriptional bursting frequencies of genes close to architectural boundaries, potentially explaining the gene expression changes observed in the cohesinopathy Cornelia de Lange syndrome. Together, our results provide a mechanistic explanation for stochastic domain intermingling, arguing that cohesin partially bypasses boundaries to promote alternating incorporation of boundary-proximal genes into neighboring regulatory domains.

scholarly journals Functional properties of the Su(Hw) complex are determined by its regulatory environment and multiple interactions on the Su(Hw) protein platform

2019 ◽  
Vol 23 (2) ◽  
pp. 168-173
Author(s):  
L. S. Melnikova ◽  
M. V. Kostyuchenko ◽  
V. V. Molodina ◽  
P. G. Georgiev ◽  
A. K. Golovnin
Keyword(s):  
Dna Binding ◽  
Genomic Structure ◽  
Regulatory Elements ◽  
Regulatory Processes ◽  
Insulator Proteins ◽  
Topologically Associated Domains ◽  
Regulation Of Activity ◽  
Dependent Protein ◽  
And Function ◽  
Multiple Interactions

The Su(Hw) protein was first identified as a DNA-binding component of an insulator complex in Drosophila. Insulators are regulatory elements that can block the enhancer-promoter communication and exhibit boundary activity. Some insulator complexes contribute to the higher-order organization of chromatin in topologically associated domains that are fundamental elements of the eukaryotic genomic structure. The Su(Hw)-dependent protein complex is a unique model for studying the insulator, since its basic structural components affecting its activity are already known. However, the mechanisms involving this complex in various regulatory processes and the precise interaction between the components of the Su(Hw) insulators remain poorly understood. Our recent studies reveal the fine mechanism of formation and function of the Su(Hw) insulator. Our results provide, for the first time, an example of a high complexity of interactions between the insulator proteins that are required to form the (Su(Hw)/Mod(mdg4)-67.2/CP190) complex. All interactions between the proteins are to a greater or lesser extent redundant, which increases the reliability of the complex formation. We conclude that both association with CP190 and Mod(mdg4)-67.2 partners and the proper organization of the DNA binding site are essential for the efficient recruitment of the Su(Hw) complex to chromatin insulators. In this review, we demonstrate the role of multiple interactions between the major components of the Su(Hw) insulator complex (Su(Hw)/Mod(mdg4)-67.2/CP190) in its activity. It was shown that Su(Hw) may regulate the enhancer–promoter communication via the newly described insulator neutralization mechanism. Moreover, Su(Hw) participates in direct regulation of activity of vicinity promoters. Finally, we demonstrate the mechanism of organization of “insulator bodies” and suggest a model describing their role in proper binding of the Su(Hw) complex to chromatin.

scholarly journals Seeing the forest through the trees: prioritising potentially functional interactions from Hi-C

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Ning Liu ◽  
Wai Yee Low ◽  
Hamid Alinejad-Rokny ◽  
Stephen Pederson ◽  
Timothy Sadlon ◽  
...  
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Regulatory Elements ◽  
Valuable Insight ◽  
Gene Promoters ◽  
Chromosome Conformation ◽  
Functional Interactions ◽  
Topologically Associated Domains ◽  
Downstream Analysis ◽  
Drive Gene

AbstractEukaryotic genomes are highly organised within the nucleus of a cell, allowing widely dispersed regulatory elements such as enhancers to interact with gene promoters through physical contacts in three-dimensional space. Recent chromosome conformation capture methodologies such as Hi-C have enabled the analysis of interacting regions of the genome providing a valuable insight into the three-dimensional organisation of the chromatin in the nucleus, including chromosome compartmentalisation and gene expression. Complicating the analysis of Hi-C data, however, is the massive amount of identified interactions, many of which do not directly drive gene function, thus hindering the identification of potentially biologically functional 3D interactions. In this review, we collate and examine the downstream analysis of Hi-C data with particular focus on methods that prioritise potentially functional interactions. We classify three groups of approaches: structural-based discovery methods, e.g. A/B compartments and topologically associated domains, detection of statistically significant chromatin interactions, and the use of epigenomic data integration to narrow down useful interaction information. Careful use of these three approaches is crucial to successfully identifying potentially functional interactions within the genome.

scholarly journals High-resolution analysis of cis -acting regulatory networks at the α-globin locus

2013 ◽  
Vol 368 (1620) ◽  
pp. 20120361 ◽  
Author(s):  
Jim R. Hughes ◽  
Karen M. Lower ◽  
Ian Dunham ◽  
Stephen Taylor ◽  
Marco De Gobbi ◽  
...  
Keyword(s):  
High Resolution ◽  
Gene Cluster ◽  
Regulatory Networks ◽  
Single Gene ◽  
Regulatory Elements ◽  
Circular Chromosome ◽  
Chromosome Conformation ◽  
Cis Acting ◽  
High Resolution Analysis ◽  
Resolution Analysis

We have combined the circular chromosome conformation capture protocol with high-throughput, genome-wide sequence analysis to characterize the cis -acting regulatory network at a single locus. In contrast to methods which identify large interacting regions (10–1000 kb), the 4C approach provides a comprehensive, high-resolution analysis of a specific locus with the aim of defining, in detail, the cis -regulatory elements controlling a single gene or gene cluster. Using the human α-globin locus as a model, we detected all known local and long-range interactions with this gene cluster. In addition, we identified two interactions with genes located 300 kb (NME4) and 625 kb (FAM173a) from the α-globin cluster.

scholarly journals Extrachromosomal DNA: An Emerging Hallmark in Human Cancer

2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Sihan Wu ◽  
Vineet Bafna ◽  
Howard Y. Chang ◽  
Paul S. Mischel
Keyword(s):  
Human Cancer ◽  
Regulatory Elements ◽  
Annual Review ◽  
Publication Date ◽  
Cancer Evolution ◽  
Form And Function ◽  
Current State ◽  
Human Genes ◽  
Cancer Tumor ◽  
And Function

Human genes are arranged on 23 pairs of chromosomes, but in cancer, tumor-promoting genes and regulatory elements can free themselves from chromosomes and relocate to circular, extrachromosomal pieces of DNA (ecDNA). ecDNA, because of its nonchromosomal inheritance, drives high-copy-number oncogene amplification and enables tumors to evolve their genomes rapidly. Furthermore, the circular ecDNA architecture fundamentally alters gene regulation and transcription, and the higher-order organization of ecDNA contributes to tumor pathogenesis. Consequently, patients whose cancers harbor ecDNA have significantly shorter survival. Although ecDNA was first observed more than 50 years ago, its critical importance has only recently come to light. In this review, we discuss the current state of understanding of how ecDNAs form and function as well as how they contribute to drug resistance and accelerated cancer evolution. Expected final online publication date for the Annual Review of Pathology: Mechanisms of Disease, Volume 17 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

scholarly journals Origins and Function of VL30 lncRNA Packaging in Small Extracellular Vesicles: Implications for Cellular Physiology and Pathology

Biomedicines ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1742
Author(s):  
Stefania Mantziou ◽  
Georgios S. Markopoulos
Keyword(s):  
Extracellular Vesicles ◽  
Active Regions ◽  
Regulatory Elements ◽  
Binding Motif ◽  
Regulatory Sequences ◽  
Chromosomal Distribution ◽  
Non Coding Rna ◽  
Rna Biology ◽  
And Function

Long non-coding RNAs (lncRNAs) have emerged during the post-genomic era as significant epigenetic regulators. Viral-like 30 elements (VL30s) are a family of mouse retrotransposons that are transcribed into functional lncRNAs. Recent data suggest that VL30 RNAs are efficiently packaged in small extracellular vesicles (SEVs) through an SEV enrichment sequence. We analysed VL30 elements for the presence of the distinct 26 nt SEV enrichment motif and found that SEV enrichment is an inherent hallmark of the VL30 family, contained in 36 full-length elements, with a widespread chromosomal distribution. Among them, 25 elements represent active, present-day integrations and contain an abundance of regulatory sequences. Phylogenetic analysis revealed a recent spread of SEV-VL30s from 4.4 million years ago till today. Importantly, 39 elements contain an SFPQ-binding motif, associated with the transcriptional induction of oncogenes. Most SEV-VL30s reside in transcriptionally active regions, as characterised by their distribution adjacent to candidate cis-regulatory elements (cCREs). Network analysis of SEV-VL30-associated genes suggests a distinct transcriptional footprint associated with embryonal abnormalities and neoplasia. Given the established role of VL30s in oncogenesis, we conclude that their potential to spread through SEVs represents a novel mechanism for non-coding RNA biology with numerous implications for cellular homeostasis and disease.

scholarly journals Correlated STORM-homoFRET Imaging: Applications to the Study of Membrane Receptor Self-Association and Clustering

2021 ◽  
Author(s):  
Amine Driouchi ◽  
Scott Gray-Owen ◽  
Christopher M Yip
Keyword(s):  
Spatial Distribution ◽  
Membrane Proteins ◽  
Complex Mixture ◽  
Cell Surface Receptor ◽  
Oligomeric State ◽  
Imaging Approach ◽  
Surface Receptor ◽  
A Cell ◽  
Self Association ◽  
And Function

Mapping the self-organization and spatial distribution of membrane proteins is key to understanding their function. We report here on a correlated STORM/homoFRET imaging approach for resolving the nanoscale distribution and oligomeric state of membrane proteins. Live cell homoFRET imaging of CEACAM1, a cell-surface receptor known to exist in a complex equilibrium between monomer and dimer/oligomer states, revealed highly heterogenous diffraction-limited structures on the surface of HeLa cells. Correlated super-resolved STORM imaging revealed that these structures comprised a complex mixture and spatial distribution of self-associated CEACAM1 molecules. This correlated approach provides a compelling strategy for addressing challenging questions about the interplay between membrane protein concentration, distribution, interaction, clustering, and function.

scholarly journals Spatial organization of transcript elongation and splicing kinetics

2021 ◽  
Author(s):  
Alyssa D. Casill ◽  
Adam J. Haimowitz ◽  
Brian Kosmyna ◽  
Charles C. Query ◽  
Kenny Ye ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Spatial Organization ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Regulatory Elements ◽  
Multiple Control ◽  
Pol Ii ◽  
Topologically Associated Domains ◽  
Transcript Elongation ◽  
Kinetics Of

SummaryThe organization of the genome in three-dimensional space has been shown to play an important role in gene expression. Specifically, facets of genomic interaction such as topologically associated domains (TADs) have been shown to regulate transcription by bringing regulatory elements into close proximity1. mRNA production is an intricate process with multiple control points including regulation of Pol II elongation and the removal of non-coding sequences via pre-mRNA splicing2. The connection between genomic compartments and the kinetics of RNA biogenesis and processing has been largely unexplored. Here, we measure Pol II elongation and splicing kinetics genome-wide using a novel technique that couples nascent RNA-seq with a mathematical model of transcription and co-transcriptional RNA processing. We uncovered multiple layers of spatial organization of these rates: the rate of splicing is coordinated across introns within individual genes, and both elongation and splicing rates are coordinated within TADs, as are alternative splicing outcomes. Overall, our work establishes that the kinetics of transcription and splicing are coordinated by the spatial organization of the genome and suggests that TADs are a major platform for coordination of alternative splicing.

scholarly journals Reorganization of chromosome architecture in replicative cellular senescence

2016 ◽  
Vol 2 (2) ◽  
pp. e1500882 ◽  
Author(s):  
Steven W. Criscione ◽  
Marco De Cecco ◽  
Benjamin Siranosian ◽  
Yue Zhang ◽  
Jill A. Kreiling ◽  
...  
Keyword(s):  
Cellular Senescence ◽  
Structural Model ◽  
Three Dimensional ◽  
Chromatin Accessibility ◽  
Genome Chromosome ◽  
Chromosome Conformation ◽  
Topologically Associated Domains ◽  
Chromosomal Architecture ◽  
Fundamental Biological Process ◽  
3D Architecture

Replicative cellular senescence is a fundamental biological process characterized by an irreversible arrest of proliferation. Senescent cells accumulate a variety of epigenetic changes, but the three-dimensional (3D) organization of their chromatin is not known. We applied a combination of whole-genome chromosome conformation capture (Hi-C), fluorescence in situ hybridization, and in silico modeling methods to characterize the 3D architecture of interphase chromosomes in proliferating, quiescent, and senescent cells. Although the overall organization of the chromatin into active (A) and repressive (B) compartments and topologically associated domains (TADs) is conserved between the three conditions, a subset of TADs switches between compartments. On a global level, the Hi-C interaction matrices of senescent cells are characterized by a relative loss of long-range and gain of short-range interactions within chromosomes. Direct measurements of distances between genetic loci, chromosome volumes, and chromatin accessibility suggest that the Hi-C interaction changes are caused by a significant reduction of the volumes occupied by individual chromosome arms. In contrast, centromeres oppose this overall compaction trend and increase in volume. The structural model arising from our study provides a unique high-resolution view of the complex chromosomal architecture in senescent cells.

scuteexpression inCalliphora vicinareveals an ancestral pattern of longitudinal stripes on the thorax of higher Diptera

Development ◽  
2002 ◽  
Vol 129 (3) ◽  
pp. 563-572 ◽  
Author(s):  
Daniela Pistillo ◽  
Nick Skaer ◽  
Pat Simpson
Keyword(s):  
Expression Pattern ◽  
Regulatory Elements ◽  
Calliphora Vicina ◽  
Transcriptional Activators ◽  
Gene Complex ◽  
Secondary Loss ◽  
Evolutionary Changes ◽  
Sensory Bristles ◽  
And Function ◽  
Bristle Patterns

In Drosophila the stereotyped arrangement of sensory bristles on the notum is determined by the tightly regulated control of transcription of the achaete-scute (ac-sc) genes which are expressed in small proneural clusters of cells at the sites of each future bristle. Expression relies on a series of discrete cis-regulatory elements present in the ac-sc gene complex that are the target of the transcriptional activators pannier (pnr) and the genes of the iroquois complex. Stereotyped bristle patterns are common among species of acalyptrate Schizophora such as Drosophila, and are thought to have derived from an ancestral pattern of four longitudinal rows extending the length of the scutum, through secondary loss of bristles. To investigate evolutionary changes in bristle patterns and ac-sc regulation by pnr, we have isolated homologues of these genes from Calliphora vicina, a species of calyptrate Schizophora separated from Drosophila by at least 100 million years. Calliphora vicina displays a pattern of four rows of bristles on the scutum resembling the postulated ancestral one. We find that sc in Calliphora is expressed in two longitudinal stripes on the medial scutum that prefigure the development of the rows of acrostichal and dorsocentral bristles. This result suggests that a stripe-like expression pattern of sc may be an ancestral feature and may have preceded the evolution of proneural clusters. The implications for the evolution of the cis-regulatory elements responsible for sc expression in the proneural clusters of Drosophila, and function of Pnr are discussed.

scholarly journals Technologies to study spatial genome organization: beyond 3C

2019 ◽  
Author(s):  
Nadine Übelmesser ◽  
Argyris Papantonis
Keyword(s):  
Genome Organization ◽  
Nuclear Organization ◽  
Three Dimensional ◽  
Nuclear Space ◽  
Chromosome Conformation ◽  
Novel Variants ◽  
Cell Processes ◽  
Systematic Biases ◽  
And Function ◽  
Spatial Genome Organization

Abstract The way that chromatin is organized in three-dimensional nuclear space is now acknowledged as a factor critical for the major cell processes, like transcription, replication and cell division. Researchers have been armed with new molecular and imaging technologies to study this structure-to-function link of genomes, spearheaded by the introduction of the ‘chromosome conformation capture’ technology more than a decade ago. However, this technology is not without shortcomings, and novel variants and orthogonal approaches are being developed to overcome these. As a result, the field of nuclear organization is constantly fueled by methods of increasing resolution and/or throughput that strive to eliminate systematic biases and increase precision. In this review, we attempt to highlight the most recent advances in technology that promise to provide novel insights on how chromosomes fold and function.

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