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 EPCO-31. EPIGENOMIC INTRATUMORAL HETEROGENEITY OF GLIOBLASTOMA IN THREE-DIMENSIONAL SPACE

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii76-ii76
Author(s):  
Radhika Mathur ◽  
Sriranga Iyyanki ◽  
Stephanie Hilz ◽  
Chibo Hong ◽  
Joanna Phillips ◽  
...  
Keyword(s):  
Spatial Organization ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Spatial Location ◽  
Therapy Resistance ◽  
Regulatory Elements ◽  
Chromatin Accessibility ◽  
Intratumoral Heterogeneity ◽  
Tumor Evolution ◽  
Open Chromatin

Abstract Treatment failure in glioblastoma is often attributed to intratumoral heterogeneity (ITH), which fosters tumor evolution and generation of therapy-resistant clones. While ITH in glioblastoma has been well-characterized at the genomic and transcriptomic levels, the extent of ITH at the epigenomic level and its biological and clinical significance are not well understood. In collaboration with neurosurgeons, neuropathologists, and biomedical imaging experts, we have established a novel topographical approach towards characterizing epigenomic ITH in three-dimensional (3-D) space. We utilize pre-operative MRI scans to define tumor volume and then utilize 3-D surgical neuro-navigation to intra-operatively acquire 10+ samples representing maximal anatomical diversity. The precise spatial location of each sample is mapped by 3-D coordinates, enabling tumors to be visualized in 360-degrees and providing unprecedented insight into their spatial organization and patterning. For each sample, we conduct assay for transposase-accessible chromatin using sequencing (ATAC-Seq), which provides information on the genomic locations of open chromatin, DNA-binding proteins, and individual nucleosomes at nucleotide resolution. We additionally conduct whole-exome sequencing and RNA sequencing for each spatially mapped sample. Integrative analysis of these datasets reveals distinct patterns of chromatin accessibility within glioblastoma tumors, as well as their associations with genetically defined clonal expansions. Our analysis further reveals how differences in chromatin accessibility within tumors reflect underlying transcription factor activity at gene regulatory elements, including both promoters and enhancers, and drive expression of particular gene expression sets, including neuronal and immune programs. Collectively, this work provides the most comprehensive characterization of epigenomic ITH to date, establishing its importance for driving tumor evolution and therapy resistance in glioblastoma. As a resource for further investigation, we have provided our datasets on an interactive data sharing platform – The 3D Glioma Atlas – that enables 360-degree visualization of both genomic and epigenomic ITH.

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 Chromatin spatial organization of wild type and mutant peanuts reveals high-resolution genomic architecture and interaction alterations

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Xingguo Zhang ◽  
Manish K. Pandey ◽  
Jianping Wang ◽  
Kunkun Zhao ◽  
Xingli Ma ◽  
...  
Keyword(s):  
Spatial Organization ◽  
Gene Expression Regulation ◽  
Three Dimensional ◽  
Active Regions ◽  
Mutant Line ◽  
Binding Motif ◽  
Wild Type ◽  
3D Genome ◽  
Topologically Associated Domains ◽  
High Gene

Abstract Background Three-dimensional (3D) chromatin organization provides a critical foundation to investigate gene expression regulation and cellular homeostasis. Results Here, we present the first 3D genome architecture maps in wild type and mutant allotetraploid peanut lines, which illustrate A/B compartments, topologically associated domains (TADs), and widespread chromatin interactions. Most peanut chromosomal arms (52.3%) have active regions (A compartments) with relatively high gene density and high transcriptional levels. About 2.0% of chromosomal regions switch from inactive to active (B-to-A) in the mutant line, harboring 58 differentially expressed genes enriched in flavonoid biosynthesis and circadian rhythm functions. The mutant peanut line shows a higher number of genome-wide cis-interactions than its wild-type. The present study reveals a new TAD in the mutant line that generates different chromatin loops and harbors a specific upstream AP2EREBP-binding motif which might upregulate the expression of the GA2ox gene and decrease active gibberellin (GA) content, presumably making the mutant plant dwarf. Conclusions Our findings will shed new light on the relationship between 3D chromatin architecture and transcriptional regulation in plants.

Learning the inverse kinetics of an octopus-like manipulator in three-dimensional space

2015 ◽  
Vol 10 (3) ◽  
pp. 035006 ◽  
Author(s):  
M Giorelli ◽  
F Renda ◽  
M Calisti ◽  
A Arienti ◽  
G Ferri ◽  
...  
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Kinetics Of ◽  
Three Dimensional Space

scholarly journals Hi–C interaction graph analysis reveals the impact of histone modifications in chromatin shape

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Emre Sefer
Keyword(s):  
Histone Modifications ◽  
Spatial Organization ◽  
Three Dimensional ◽  
Cell Types ◽  
Interaction Graph ◽  
Chromosome Conformation ◽  
A Genome ◽  
Topologically Associated Domains ◽  
Wide Scale ◽  
The Impact

AbstractChromosome conformation capture experiments such as Hi–C map the three-dimensional spatial organization of genomes in a genome-wide scale. Even though Hi–C interactions are not biased towards any of the histone modifications, previous analysis has revealed denser interactions around many histone modifications. Nevertheless, simultaneous effects of these modifications in Hi–C interaction graph have not been fully characterized yet, limiting our understanding of genome shape. Here, we propose ChromatinCoverage and its extension TemporalPrizeCoverage methods to decompose Hi–C interaction graph in terms of known histone modifications. Both methods are based on set multicover with pairs, where each Hi–C interaction is tried to be covered by histone modification pairs. We find 4 histone modifications H3K4me1, H3K4me3, H3K9me3, H3K27ac to be significantly predictive of most Hi–C interactions across species, cell types and cell cycles. The proposed methods are quite effective in predicting Hi–C interactions and topologically-associated domains in one species, given it is trained on another species or cell types. Overall, our findings reveal the impact of subset of histone modifications in chromatin shape via Hi–C interaction graph.

scholarly journals Evolution of Genome-Organizing Long Non-coding RNAs in Metazoans

2020 ◽  
Vol 11 ◽  
Author(s):  
América Ramírez-Colmenero ◽  
Katarzyna Oktaba ◽  
Selene L. Fernandez-Valverde
Keyword(s):  
Spatial Organization ◽  
Gene Expression Regulation ◽  
Dimensional Space ◽  
Functional Characterization ◽  
Three Dimensional ◽  
Protein Coding ◽  
Chromatin Interactions ◽  
Non Coding Rnas ◽  
Regulatory Functions ◽  
Three Dimensional Space

Long non-coding RNAs (lncRNAs) have important regulatory functions across eukarya. It is now clear that many of these functions are related to gene expression regulation through their capacity to recruit epigenetic modifiers and establish chromatin interactions. Several lncRNAs have been recently shown to participate in modulating chromatin within the spatial organization of the genome in the three-dimensional space of the nucleus. The identification of lncRNA candidates is challenging, as it is their functional characterization. Conservation signatures of lncRNAs are different from those of protein-coding genes, making identifying lncRNAs under selection a difficult task, and the homology between lncRNAs may not be readily apparent. Here, we review the evidence for these higher-order genome organization functions of lncRNAs in animals and the evolutionary signatures they display.

Alternative splicing of protein 4.1R exon 16: ordered excision of flanking introns ensures proper splice site choice

Blood ◽  
2000 ◽  
Vol 95 (2) ◽  
pp. 692-699 ◽  
Author(s):  
Sherry L. Gee ◽  
Kazuko Aoyagi ◽  
Robert Lersch ◽  
Victor Hou ◽  
Michael Wu ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Splice Site ◽  
Messenger Rna ◽  
Spatial Organization ◽  
Regulatory Elements ◽  
Binding Domain ◽  
Alternative Exon ◽  
Actin Binding ◽  
Actin Binding Domain ◽  
Protein 4.1R

Alternative splicing plays a major role in regulating tissue-specific expression of cytoskeletal protein 4.1R isoforms. In particular, expression of the protein's functionally critical spectrin-actin binding domain, essential for maintenance of red cell membrane mechanical properties, is governed by a developmentally regulated splicing switch involving alternative exon 16. Using a model 3-exon 4.1R pre–messenger RNA (pre-mRNA), we explored the sequence requirements for excision of the introns flanking exon 16. These studies revealed that splicing of this alternative exon occurs preferentially in an ordered fashion. The first step is excision of the downstream intron to join exons 16 and 17, followed by excision of the upstream intron. Constructs designed to test the converse pathway were spliced less efficiently and with less fidelity, in part due to activation of a cryptic 5′ splice site in exon 16. This downstream-first model for ordered splicing is consistent with the hypothesis that regulated alternative splicing requires cooperation between multiple exonic and/or intronic regulatory elements whose spatial organization is critical for recruitment of appropriate splicing factors. Our results predict that exon 16 splicing is regulated at the first step—excision of the downstream intron—and that cells unable to catalyze this step will exhibit exon 16 skipping. In cells that include exon 16, adherence to an ordered pathway is important for efficient and accurate production of mature 4.1R mRNA encoding an intact spectrin-actin binding domain.

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