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Aljahani A, Mauksch C, Oudelaar AM. The relationship between nucleosome positioning and higher-order genome folding. Curr Opin Cell Biol 2024; 89:102398. [PMID: 38991477 DOI: 10.1016/j.ceb.2024.102398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2024] [Revised: 05/23/2024] [Accepted: 06/18/2024] [Indexed: 07/13/2024]
Abstract
Eukaryotic genomes are organized into 3D structures, which range from small-scale nucleosome arrays to large-scale chromatin domains. These structures have an important role in the regulation of transcription and other nuclear processes. Despite advances in our understanding of the properties, functions, and underlying mechanisms of genome structures, there are many open questions about the interplay between these structures across scales. In particular, it is not well understood if and how 1D features of nucleosome arrays influence large-scale 3D genome folding patterns. In this review, we discuss recent studies that address these questions and summarize our current understanding of the relationship between nucleosome positioning and higher-order genome folding.
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Affiliation(s)
- Abrar Aljahani
- Max Planck Institute for Multidisciplinary Sciences, Genome Organization and Regulation, Göttingen, Germany; University of Göttingen, Göttingen, Germany
| | - Clemens Mauksch
- Max Planck Institute for Multidisciplinary Sciences, Genome Organization and Regulation, Göttingen, Germany; University of Göttingen, Göttingen, Germany
| | - A Marieke Oudelaar
- Max Planck Institute for Multidisciplinary Sciences, Genome Organization and Regulation, Göttingen, Germany.
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Oberbeckmann E, Oudelaar AM. Genome organization across scales: mechanistic insights from in vitro reconstitution studies. Biochem Soc Trans 2024; 52:793-802. [PMID: 38451192 PMCID: PMC11088924 DOI: 10.1042/bst20230883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 02/19/2024] [Accepted: 02/27/2024] [Indexed: 03/08/2024]
Abstract
Eukaryotic genomes are compacted and organized into distinct three-dimensional (3D) structures, which range from small-scale nucleosome arrays to large-scale chromatin domains. These chromatin structures play an important role in the regulation of transcription and other nuclear processes. The molecular mechanisms that drive the formation of chromatin structures across scales and the relationship between chromatin structure and function remain incompletely understood. Because the processes involved are complex and interconnected, it is often challenging to dissect the underlying principles in the nuclear environment. Therefore, in vitro reconstitution systems provide a valuable approach to gain insight into the molecular mechanisms by which chromatin structures are formed and to determine the cause-consequence relationships between the processes involved. In this review, we give an overview of in vitro approaches that have been used to study chromatin structures across scales and how they have increased our understanding of the formation and function of these structures. We start by discussing in vitro studies that have given insight into the mechanisms of nucleosome positioning. Next, we discuss recent efforts to reconstitute larger-scale chromatin domains and loops and the resulting insights into the principles of genome organization. We conclude with an outlook on potential future applications of chromatin reconstitution systems and how they may contribute to answering open questions concerning chromatin architecture.
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Affiliation(s)
- Elisa Oberbeckmann
- Department of Molecular Biology, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077 Göttingen, Germany
| | - A. Marieke Oudelaar
- Genome Organization and Regulation, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077 Göttingen, Germany
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Themistoklis K, Christoforos N. Spatial Organization of Gene Expression in Systems of Cellular Differentiation and Autoimmune Diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1423:225-233. [PMID: 37525048 DOI: 10.1007/978-3-031-31978-5_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/02/2023]
Abstract
The importance of the spatial distribution of genes and gene regulation areas in an organism's genome has seen an increased interest in studies in the fields of genetics and epigenetics.This work attempts to apply an already established pipeline for topological and functional analysis of gene expression on a system of cell differentiation of mice embryonic cells exposed to TCF3.The analysis includes a separation of genes in different categories based on their expression's behavior over time, the functional analysis in overexpressed and underexpressed genes, the identification of domains of focal regulation/deregulation, and a network analysis between genes and functional categories in different time points.The results show two major transition points regarding the up- and downregulation in gene expression. Considering the enrichment pathways, apart from those related to development and morphogenesis, a couple more chromosomal regions show behaviors worthy of further examination.
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Stavropoulou A, Tassios E, Kalyva M, Georgoulopoulos M, Vakirlis N, Iliopoulos I, Nikolaou C. Distinct chromosomal “niches” in the genome of Saccharomyces cerevisiae provide the background for genomic innovation and shape the fate of gene duplicates. NAR Genom Bioinform 2022; 4:lqac086. [PMID: 36381424 PMCID: PMC9661399 DOI: 10.1093/nargab/lqac086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Revised: 10/20/2022] [Accepted: 10/25/2022] [Indexed: 11/15/2022] Open
Abstract
Nearly one third of Saccharomyces cerevisiae protein coding sequences correspond to duplicate genes, equally split between small-scale duplicates (SSD) and whole-genome duplicates (WGD). While duplicate genes have distinct properties compared to singletons, to date, there has been no systematic analysis of their positional preferences. In this work, we show that SSD and WGD genes are organized in distinct gene clusters that occupy different genomic regions, with SSD being more peripheral and WGD more centrally positioned close to centromeric chromatin. Duplicate gene clusters differ from the rest of the genome in terms of gene size and spacing, gene expression variability and regulatory complexity, properties that are also shared by singleton genes residing within them. Singletons within duplicate gene clusters have longer promoters, more complex structure and a higher number of protein–protein interactions. Particular chromatin architectures appear to be important for gene evolution, as we find SSD gene-pair co-expression to be strongly associated with the similarity of nucleosome positioning patterns. We propose that specific regions of the yeast genome provide a favourable environment for the generation and maintenance of small-scale gene duplicates, segregating them from WGD-enriched genomic domains. Our findings provide a valuable framework linking genomic innovation with positional genomic preferences.
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Affiliation(s)
- Athanasia Stavropoulou
- Medical School, University of Crete , Heraklion 70013, Greece
- Computational Genomics Group, Biomedical Sciences Research Center “Alexander Fleming” , Athens 16672, Greece
| | - Emilios Tassios
- Medical School, University of Crete , Heraklion 70013, Greece
- Computational Genomics Group, Biomedical Sciences Research Center “Alexander Fleming” , Athens 16672, Greece
| | - Maria Kalyva
- European Bioinformatics Institute, EMBL-EBI, Wellcome Genome Campus , Hinxton, Cambridgeshire, CB10 1SD, UK
| | | | - Nikolaos Vakirlis
- Computational Genomics Group, Biomedical Sciences Research Center “Alexander Fleming” , Athens 16672, Greece
| | | | - Christoforos Nikolaou
- Computational Genomics Group, Biomedical Sciences Research Center “Alexander Fleming” , Athens 16672, Greece
- Hellenic Open University , Patras 26335, Greece
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Kantidze OL, Razin SV. Weak interactions in higher-order chromatin organization. Nucleic Acids Res 2020; 48:4614-4626. [PMID: 32313950 PMCID: PMC7229822 DOI: 10.1093/nar/gkaa261] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 03/30/2020] [Accepted: 04/03/2020] [Indexed: 12/20/2022] Open
Abstract
The detailed principles of the hierarchical folding of eukaryotic chromosomes have been revealed during the last two decades. Along with structures composing three-dimensional (3D) genome organization (chromatin compartments, topologically associating domains, chromatin loops, etc.), the molecular mechanisms that are involved in their establishment and maintenance have been characterized. Generally, protein-protein and protein-DNA interactions underlie the spatial genome organization in eukaryotes. However, it is becoming increasingly evident that weak interactions, which exist in biological systems, also contribute to the 3D genome. Here, we provide a snapshot of our current understanding of the role of the weak interactions in the establishment and maintenance of the 3D genome organization. We discuss how weak biological forces, such as entropic forces operating in crowded solutions, electrostatic interactions of the biomolecules, liquid-liquid phase separation, DNA supercoiling, and RNA environment participate in chromosome segregation into structural and functional units and drive intranuclear functional compartmentalization.
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Affiliation(s)
- Omar L Kantidze
- Institute of Gene Biology Russian Academy of Sciences, 119334 Moscow, Russia
| | - Sergey V Razin
- Institute of Gene Biology Russian Academy of Sciences, 119334 Moscow, Russia
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Monitoring the prolonged Tnf stimulation in space and time with topological-functional networks. Comput Struct Biotechnol J 2020; 18:220-229. [PMID: 32021663 PMCID: PMC6994266 DOI: 10.1016/j.csbj.2020.01.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 12/18/2019] [Accepted: 01/03/2020] [Indexed: 11/21/2022] Open
Abstract
Genes in linear proximity often share regulatory inputs, expression and evolutionary patterns, even in complex eukaryote genomes with extensive intergenic sequences. Gene regulation, on the other hand, is effected through the co-ordinated activation (or suppression) of genes participating in common biological pathways, which are often transcribed from distant loci. Existing approaches for the study of gene expression focus on the functional aspect, taking positional constraints into account only marginally. In this work we propose a novel concept for the study of gene expression, through the combination of topological and functional information into bipartite networks. Starting from genome-wide expression profiles, we define extended chromosomal regions with consistent patterns of differential gene expression and then associate these domains with enriched functional pathways. By analyzing the resulting networks in terms of size, connectivity and modularity we can draw conclusions on the way genome organization may underlie the gene regulation program. Implementation of this approach in a detailed RNASeq profiling of sustained Tnf stimulation of mouse synovial fibroblasts, allowed us to identify unexpected regulatory changes taking place in the cells after 24 h of stimulation. Bipartite network analysis suggests that the cytokine response set by Tnf, progresses through two distinct transitions. An early generalization of the inflammatory response, that is followed by a late shutdown of immune-related functions and the redistribution of expression to developmental and cell adhesion pathways and distinct chromosomal regions. We show that the incorporation of topological information may provide additional insights in the complex propagation of Tnf activation.
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Juárez-Reyes A, Castaño I. Chromatin architecture and virulence-related gene expression in eukaryotic microbial pathogens. Curr Genet 2018; 65:435-443. [PMID: 30443783 DOI: 10.1007/s00294-018-0903-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 10/30/2018] [Accepted: 11/10/2018] [Indexed: 12/19/2022]
Abstract
A fundamental question in biology is to understand how appropriate transcriptional regulation and dense packaging of the genetic material within the eukaryotic nucleus are achieved. The exquisite gene expression control and other metabolic processes of DNA require a highly complex, multilayered, three-dimensional architecture of the chromatin and its specific compartmentalization within the nucleus. Some of these architectural and sub-nuclear positioning mechanisms have been extensively co-opted by eukaryotic pathogens to keep fine expression control and expansion of virulence-related gene families in Plasmodium falciparum, Trypanosoma brucei and Candida glabrata. For example non-linear interactions between distant cis-acting regions and the formation of chromatin loops are required for appropriate regulation of the expression of virulence-related multi-gene families encoding cell surface proteins. These gene families are located near the chromosome ends and tethered to the nuclear periphery. Consequently, only one or very few genes of the family are expressed at a time. These genes are involved in antigenic variation in parasites and the generation of subpopulations of cells with diverse antigenic proteins at the surface in some pathogenic fungi, making them highly efficient pathogens.
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Affiliation(s)
- Alejandro Juárez-Reyes
- División de Biología Molecular, IPICYT, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José 2055, 78216, San Luis Potosí, SLP, Mexico
| | - Irene Castaño
- División de Biología Molecular, IPICYT, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José 2055, 78216, San Luis Potosí, SLP, Mexico.
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