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Yang JH, Hansen AS. Enhancer selectivity in space and time: from enhancer-promoter interactions to promoter activation. Nat Rev Mol Cell Biol 2024; 25:574-591. [PMID: 38413840 DOI: 10.1038/s41580-024-00710-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/30/2024] [Indexed: 02/29/2024]
Abstract
The primary regulators of metazoan gene expression are enhancers, originally functionally defined as DNA sequences that can activate transcription at promoters in an orientation-independent and distance-independent manner. Despite being crucial for gene regulation in animals, what mechanisms underlie enhancer selectivity for promoters, and more fundamentally, how enhancers interact with promoters and activate transcription, remain poorly understood. In this Review, we first discuss current models of enhancer-promoter interactions in space and time and how enhancers affect transcription activation. Next, we discuss different mechanisms that mediate enhancer selectivity, including repression, biochemical compatibility and regulation of 3D genome structure. Through 3D polymer simulations, we illustrate how the ability of 3D genome folding mechanisms to mediate enhancer selectivity strongly varies for different enhancer-promoter interaction mechanisms. Finally, we discuss how recent technical advances may provide new insights into mechanisms of enhancer-promoter interactions and how technical biases in methods such as Hi-C and Micro-C and imaging techniques may affect their interpretation.
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Affiliation(s)
- Jin H Yang
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Gene Regulation Observatory, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Koch Institute for Integrative Cancer Research, Cambridge, MA, USA
| | - Anders S Hansen
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Gene Regulation Observatory, Broad Institute of MIT and Harvard, Cambridge, MA, USA.
- Koch Institute for Integrative Cancer Research, Cambridge, MA, USA.
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2
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Milne TA. Chromatin and aberrant enhancer activity in KMT2A rearranged acute lymphoblastic leukemia. Curr Opin Genet Dev 2024; 86:102191. [PMID: 38579381 DOI: 10.1016/j.gde.2024.102191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 03/11/2024] [Accepted: 03/19/2024] [Indexed: 04/07/2024]
Abstract
To make a multicellular organism, genes need to be transcribed at the right developmental stages and in the right tissues. DNA sequences termed 'enhancers' are crucial to achieve this. Despite concerted efforts, the exact mechanisms of enhancer activity remain elusive. Mixed lineage leukemia (MLL or KMT2A) rearrangements (MLLr), commonly observed in cases of acute lymphoblastic leukemia (ALL) and acute myeloid leukemia, produce novel in-frame fusion proteins. Recent work has shown that the MLL-AF4 fusion protein drives aberrant enhancer activity at key oncogenes in ALL, dependent on the continued presence of MLL-AF4 complex components. As well as providing some general insights into enhancer function, these observations may also provide an explanation for transcriptional heterogeneity observed in MLLr patients.
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Affiliation(s)
- Thomas A Milne
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DS, UK.
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3
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Chan B, Rubinstein M. Activity-driven chromatin organization during interphase: Compaction, segregation, and entanglement suppression. Proc Natl Acad Sci U S A 2024; 121:e2401494121. [PMID: 38753513 PMCID: PMC11127048 DOI: 10.1073/pnas.2401494121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 04/17/2024] [Indexed: 05/18/2024] Open
Abstract
In mammalian cells, the cohesin protein complex is believed to translocate along chromatin during interphase to form dynamic loops through a process called active loop extrusion. Chromosome conformation capture and imaging experiments have suggested that chromatin adopts a compact structure with limited interpenetration between chromosomes and between chromosomal sections. We developed a theory demonstrating that active loop extrusion causes the apparent fractal dimension of chromatin to cross-over between two and four at contour lengths on the order of 30 kilo-base pairs. The anomalously high fractal dimension [Formula: see text] is due to the inability of extruded loops to fully relax during active extrusion. Compaction on longer contour length scales extends within topologically associated domains (TADs), facilitating gene regulation by distal elements. Extrusion-induced compaction segregates TADs such that overlaps between TADs are reduced to less than 35% and increases the entanglement strand of chromatin by up to a factor of 50 to several Mega-base pairs. Furthermore, active loop extrusion couples cohesin motion to chromatin conformations formed by previously extruding cohesins and causes the mean square displacement of chromatin loci during lag times ([Formula: see text]) longer than tens of minutes to be proportional to [Formula: see text]. We validate our results with hybrid molecular dynamics-Monte Carlo simulations and show that our theory is consistent with experimental data. This work provides a theoretical basis for the compact organization of interphase chromatin, explaining the physical reason for TAD segregation and suppression of chromatin entanglements which contribute to efficient gene regulation.
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Affiliation(s)
- Brian Chan
- Department of Biomedical Engineering, Duke University, Durham, NC27708
| | - Michael Rubinstein
- Department of Biomedical Engineering, Duke University, Durham, NC27708
- Thomas Lord Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC27708
- Department of Physics, Duke University, Durham, NC27708
- Department of Chemistry, Duke University, Durham, NC27708
- World Premier International Research Center Initiative–Institute for Chemical Reaction Design and Discovery, Hokkaido University, Sapporo001-0021, Japan
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4
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Daniel B, Chen AY, Sandor K, Zhang W, Miao Z, Lareau CA, Yost KE, Chang HY, Satpathy AT. Regulation of immune signal integration and memory by inflammation-induced chromosome conformation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.29.582872. [PMID: 38496446 PMCID: PMC10942375 DOI: 10.1101/2024.02.29.582872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
3-dimensional (3D) genome conformation is central to gene expression regulation, yet our understanding of its contribution to rapid transcriptional responses, signal integration, and memory in immune cells is limited. Here, we study the molecular regulation of the inflammatory response in primary macrophages using integrated transcriptomic, epigenomic, and chromosome conformation data, including base pair-resolution Micro-Capture C. We demonstrate that interleukin-4 (IL-4) primes the inflammatory response in macrophages by stably rewiring 3D genome conformation, juxtaposing endotoxin-, interferon-gamma-, and dexamethasone-responsive enhancers in close proximity to their cognate gene promoters. CRISPR-based perturbations of enhancer-promoter contacts or CCCTC-binding factor (CTCF) boundary elements demonstrated that IL-4-driven conformation changes are indispensable for enhanced and synergistic endotoxin-induced transcriptional responses, as well as transcriptional memory following stimulus removal. Moreover, transcriptional memory mediated by changes in chromosome conformation often occurred in the absence of changes in chromatin accessibility or histone modifications. Collectively, these findings demonstrate that rapid and memory transcriptional responses to immunological stimuli are encoded in the 3D genome.
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Affiliation(s)
- Bence Daniel
- Department of Pathology, Stanford University, Stanford, CA, USA
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA, USA
- Gladstone-UCSF Institute of Genomic Immunology, San Francisco, CA, USA
- These authors contributed equally to this work
- Present address: Department of Microchemistry, Proteomics, Lipidomics and Next Generation Sequencing, Genentech, South San Francisco, CA, USA
| | - Andy Y. Chen
- Department of Pathology, Stanford University, Stanford, CA, USA
- Department of Bioengineering, Stanford University, Stanford, CA, USA
- Gladstone-UCSF Institute of Genomic Immunology, San Francisco, CA, USA
- These authors contributed equally to this work
| | - Katalin Sandor
- Department of Pathology, Stanford University, Stanford, CA, USA
- Gladstone-UCSF Institute of Genomic Immunology, San Francisco, CA, USA
- These authors contributed equally to this work
| | - Wenxi Zhang
- Department of Pathology, Stanford University, Stanford, CA, USA
- Gladstone-UCSF Institute of Genomic Immunology, San Francisco, CA, USA
| | - Zhuang Miao
- Department of Pathology, Stanford University, Stanford, CA, USA
- Gladstone-UCSF Institute of Genomic Immunology, San Francisco, CA, USA
| | - Caleb A. Lareau
- Department of Pathology, Stanford University, Stanford, CA, USA
- Gladstone-UCSF Institute of Genomic Immunology, San Francisco, CA, USA
- Present address: Computational and Systems Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Kathryn E. Yost
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA, USA
- Present address: Whitehead Institute for Biomedical Research, Cambridge, MA, USA
| | - Howard Y. Chang
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA, USA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Ansuman T. Satpathy
- Department of Pathology, Stanford University, Stanford, CA, USA
- Parker Institute for Cancer Immunotherapy, San Francisco, CA, USA
- Gladstone-UCSF Institute of Genomic Immunology, San Francisco, CA, USA
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5
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Meeussen JVW, Lenstra TL. Time will tell: comparing timescales to gain insight into transcriptional bursting. Trends Genet 2024; 40:160-174. [PMID: 38216391 PMCID: PMC10860890 DOI: 10.1016/j.tig.2023.11.003] [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: 09/13/2023] [Revised: 11/27/2023] [Accepted: 11/27/2023] [Indexed: 01/14/2024]
Abstract
Recent imaging studies have captured the dynamics of regulatory events of transcription inside living cells. These events include transcription factor (TF) DNA binding, chromatin remodeling and modification, enhancer-promoter (E-P) proximity, cluster formation, and preinitiation complex (PIC) assembly. Together, these molecular events culminate in stochastic bursts of RNA synthesis, but their kinetic relationship remains largely unclear. In this review, we compare the timescales of upstream regulatory steps (input) with the kinetics of transcriptional bursting (output) to generate mechanistic models of transcription dynamics in single cells. We highlight open questions and potential technical advances to guide future endeavors toward a quantitative and kinetic understanding of transcription regulation.
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Affiliation(s)
- Joseph V W Meeussen
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, Amsterdam 1066CX, The Netherlands
| | - Tineke L Lenstra
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, Amsterdam 1066CX, The Netherlands.
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6
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Abstract
Many cellular processes require large-scale rearrangements of chromatin structure. Structural maintenance of chromosomes (SMC) protein complexes are molecular machines that can provide structure to chromatin. These complexes can connect DNA elements in cis, walk along DNA, build and processively enlarge DNA loops and connect DNA molecules in trans to hold together the sister chromatids. These DNA-shaping abilities place SMC complexes at the heart of many DNA-based processes, including chromosome segregation in mitosis, transcription control and DNA replication, repair and recombination. In this Review, we discuss the latest insights into how SMC complexes such as cohesin, condensin and the SMC5-SMC6 complex shape DNA to direct these fundamental chromosomal processes. We also consider how SMC complexes, by building chromatin loops, can counteract the natural tendency of alike chromatin regions to cluster. SMC complexes thus control nuclear organization by participating in a molecular tug of war that determines the architecture of our genome.
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Affiliation(s)
- Claire Hoencamp
- Division of Cell Biology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Benjamin D Rowland
- Division of Cell Biology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
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7
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Crump NT, Smith AL, Godfrey L, Dopico-Fernandez AM, Denny N, Harman JR, Hamley JC, Jackson NE, Chahrour C, Riva S, Rice S, Kim J, Basrur V, Fermin D, Elenitoba-Johnson K, Roeder RG, Allis CD, Roberts I, Roy A, Geng H, Davies JOJ, Milne TA. MLL-AF4 cooperates with PAF1 and FACT to drive high-density enhancer interactions in leukemia. Nat Commun 2023; 14:5208. [PMID: 37626123 PMCID: PMC10457349 DOI: 10.1038/s41467-023-40981-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 08/18/2023] [Indexed: 08/27/2023] Open
Abstract
Aberrant enhancer activation is a key mechanism driving oncogene expression in many cancers. While much is known about the regulation of larger chromosome domains in eukaryotes, the details of enhancer-promoter interactions remain poorly understood. Recent work suggests co-activators like BRD4 and Mediator have little impact on enhancer-promoter interactions. In leukemias controlled by the MLL-AF4 fusion protein, we use the ultra-high resolution technique Micro-Capture-C (MCC) to show that MLL-AF4 binding promotes broad, high-density regions of enhancer-promoter interactions at a subset of key targets. These enhancers are enriched for transcription elongation factors like PAF1C and FACT, and the loss of these factors abolishes enhancer-promoter contact. This work not only provides an additional model for how MLL-AF4 is able to drive high levels of transcription at key genes in leukemia but also suggests a more general model linking enhancer-promoter crosstalk and transcription elongation.
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Affiliation(s)
- Nicholas T Crump
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK.
- Hugh and Josseline Langmuir Centre for Myeloma Research, Centre for Haematology, Department of Immunology and Inflammation, Imperial College London, London, W12 0NN, UK.
| | - Alastair L Smith
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Laura Godfrey
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Ana M Dopico-Fernandez
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Nicholas Denny
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Joe R Harman
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Joseph C Hamley
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Nicole E Jackson
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Catherine Chahrour
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Simone Riva
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Siobhan Rice
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Jaehoon Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 34141, South Korea
| | - Venkatesha Basrur
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, USA
| | - Damian Fermin
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, USA
| | - Kojo Elenitoba-Johnson
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Robert G Roeder
- Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, New York, NY, 10065, USA
| | - C David Allis
- Laboratory of Chromatin Biology and Epigenetics, The Rockefeller University, New York, NY, 10065, USA
| | - Irene Roberts
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
- Department of Paediatrics, University of Oxford, Oxford, OX3 9DU, UK
| | - Anindita Roy
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
- Department of Paediatrics, University of Oxford, Oxford, OX3 9DU, UK
| | - Huimin Geng
- Department of Laboratory Medicine, University of California, San Francisco, San Francisco, California, USA
| | - James O J Davies
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Thomas A Milne
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK.
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8
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Oehler M, Geisser L, Diernfellner ACR, Brunner M. Transcription activator WCC recruits deacetylase HDA3 to control transcription dynamics and bursting in Neurospora. SCIENCE ADVANCES 2023; 9:eadh0721. [PMID: 37390199 PMCID: PMC10313174 DOI: 10.1126/sciadv.adh0721] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 05/25/2023] [Indexed: 07/02/2023]
Abstract
RNA polymerase II initiates transcription either randomly or in bursts. We examined the light-dependent transcriptional activator White Collar Complex (WCC) of Neurospora to characterize the transcriptional dynamics of the strong vivid (vvd) promoter and the weaker frequency (frq) promoter. We show that WCC is not only an activator but also represses transcription by recruiting histone deacetylase 3 (HDA3). Our data suggest that bursts of frq transcription are governed by a long-lived refractory state established and maintained by WCC and HDA3 at the core promoter, whereas transcription of vvd is determined by WCC binding dynamics at an upstream activating sequence. Thus, in addition to stochastic binding of transcription factors, transcription factor-mediated repression may also influence transcriptional bursting.
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Affiliation(s)
- Michael Oehler
- Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, D-60120 Heidelberg, Germany
| | - Leonie Geisser
- Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, D-60120 Heidelberg, Germany
| | - Axel C. R. Diernfellner
- Heidelberg University Biochemistry Center, Im Neuenheimer Feld 328, D-60120 Heidelberg, Germany
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9
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Alachkar N, Norton D, Wolkensdorfer Z, Muldoon M, Paszek P. Variability of the innate immune response is globally constrained by transcriptional bursting. Front Mol Biosci 2023; 10:1176107. [PMID: 37441161 PMCID: PMC10333517 DOI: 10.3389/fmolb.2023.1176107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 06/15/2023] [Indexed: 07/15/2023] Open
Abstract
Transcription of almost all mammalian genes occurs in stochastic bursts, however the fundamental control mechanisms that allow appropriate single-cell responses remain unresolved. Here we utilise single cell genomics data and stochastic models of transcription to perform global analysis of the toll-like receptor (TLR)-induced gene expression variability. Based on analysis of more than 2000 TLR-response genes across multiple experimental conditions we demonstrate that the single-cell, gene-by-gene expression variability can be empirically described by a linear function of the population mean. We show that response heterogeneity of individual genes can be characterised by the slope of the mean-variance line, which captures how cells respond to stimulus and provides insight into evolutionary differences between species. We further demonstrate that linear relationships theoretically determine the underlying transcriptional bursting kinetics, revealing different regulatory modes of TLR response heterogeneity. Stochastic modelling of temporal scRNA-seq count distributions demonstrates that increased response variability is associated with larger and more frequent transcriptional bursts, which emerge via increased complexity of transcriptional regulatory networks between genes and different species. Overall, we provide a methodology relying on inference of empirical mean-variance relationships from single cell data and new insights into control of innate immune response variability.
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Affiliation(s)
- Nissrin Alachkar
- Division of Immunology, Immunity to Infection and Respiratory Medicine, Lydia Becker Institute of Immunology and Inflammation, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom
| | - Dale Norton
- Division of Immunology, Immunity to Infection and Respiratory Medicine, Lydia Becker Institute of Immunology and Inflammation, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom
| | - Zsofia Wolkensdorfer
- Division of Immunology, Immunity to Infection and Respiratory Medicine, Lydia Becker Institute of Immunology and Inflammation, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom
| | - Mark Muldoon
- Department of Mathematics, University of Manchester, Manchester, United Kingdom
| | - Pawel Paszek
- Division of Immunology, Immunity to Infection and Respiratory Medicine, Lydia Becker Institute of Immunology and Inflammation, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom
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10
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Goychuk A, Kannan D, Chakraborty AK, Kardar M. Polymer folding through active processes recreates features of genome organization. Proc Natl Acad Sci U S A 2023; 120:e2221726120. [PMID: 37155885 PMCID: PMC10194017 DOI: 10.1073/pnas.2221726120] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2022] [Accepted: 04/02/2023] [Indexed: 05/10/2023] Open
Abstract
From proteins to chromosomes, polymers fold into specific conformations that control their biological function. Polymer folding has long been studied with equilibrium thermodynamics, yet intracellular organization and regulation involve energy-consuming, active processes. Signatures of activity have been measured in the context of chromatin motion, which shows spatial correlations and enhanced subdiffusion only in the presence of adenosine triphosphate. Moreover, chromatin motion varies with genomic coordinate, pointing toward a heterogeneous pattern of active processes along the sequence. How do such patterns of activity affect the conformation of a polymer such as chromatin? We address this question by combining analytical theory and simulations to study a polymer subjected to sequence-dependent correlated active forces. Our analysis shows that a local increase in activity (larger active forces) can cause the polymer backbone to bend and expand, while less active segments straighten out and condense. Our simulations further predict that modest activity differences can drive compartmentalization of the polymer consistent with the patterns observed in chromosome conformation capture experiments. Moreover, segments of the polymer that show correlated active (sub)diffusion attract each other through effective long-ranged harmonic interactions, whereas anticorrelations lead to effective repulsions. Thus, our theory offers nonequilibrium mechanisms for forming genomic compartments, which cannot be distinguished from affinity-based folding using structural data alone. As a first step toward exploring whether active mechanisms contribute to shaping genome conformations, we discuss a data-driven approach.
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Affiliation(s)
- Andriy Goychuk
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA02139
| | - Deepti Kannan
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA02139
| | - Arup K. Chakraborty
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA02139
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA02139
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA02139
- Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology and Harvard University, Cambridge, MA02139
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA02139
| | - Mehran Kardar
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA02139
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11
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Karpinska MA, Oudelaar AM. The role of loop extrusion in enhancer-mediated gene activation. Curr Opin Genet Dev 2023; 79:102022. [PMID: 36842325 DOI: 10.1016/j.gde.2023.102022] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 01/13/2023] [Accepted: 01/25/2023] [Indexed: 02/28/2023]
Abstract
Gene expression patterns in complex multicellular organisms are regulated by enhancers, which communicate with their target gene promoters in three-dimensional (3D) chromatin structures. Despite advances in our understanding of the mechanisms that organize mammalian genomes into compartments and topologically associating domains (TADs), it is not well understood how specific interactions between enhancers and promoters are controlled in this 3D context. In this review, we give an overview of recent evidence that shows that a process of loop extrusion plays an important role in the regulation of enhancer-promoter communication and discuss recent insights into the molecular mechanism by which loop extrusion contributes to enhancer-mediated gene activation.
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Affiliation(s)
- Magdalena A Karpinska
- Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany. https://twitter.com/@MagdalenaKarp
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12
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Cuartero S, Stik G, Stadhouders R. Three-dimensional genome organization in immune cell fate and function. Nat Rev Immunol 2022; 23:206-221. [PMID: 36127477 DOI: 10.1038/s41577-022-00774-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/04/2022] [Indexed: 11/09/2022]
Abstract
Immune cell development and activation demand the precise and coordinated control of transcriptional programmes. Three-dimensional (3D) organization of the genome has emerged as an important regulator of chromatin state, transcriptional activity and cell identity by facilitating or impeding long-range genomic interactions among regulatory elements and genes. Chromatin folding thus enables cell type-specific and stimulus-specific transcriptional responses to extracellular signals, which are essential for the control of immune cell fate, for inflammatory responses and for generating a diverse repertoire of antigen receptor specificities. Here, we review recent findings connecting 3D genome organization to the control of immune cell differentiation and function, and discuss how alterations in genome folding may lead to immune dysfunction and malignancy.
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Affiliation(s)
- Sergi Cuartero
- Josep Carreras Leukaemia Research Institute (IJC), Badalona, Spain. .,Germans Trias i Pujol Research Institute (IGTP), Badalona, Spain.
| | - Grégoire Stik
- Centre for Genomic Regulation (CRG), Institute of Science and Technology (BIST), Barcelona, Spain. .,Universitat Pompeu Fabra (UPF), Barcelona, Spain.
| | - Ralph Stadhouders
- Department of Pulmonary Medicine, Erasmus MC, University Medical Center, Rotterdam, The Netherlands. .,Department of Cell Biology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands.
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