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Bhattacharya M, Lyda SF, Lei EP. Chromatin insulator mechanisms ensure accurate gene expression by controlling overall 3D genome organization. Curr Opin Genet Dev 2024; 87:102208. [PMID: 38810546 DOI: 10.1016/j.gde.2024.102208] [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: 02/02/2024] [Revised: 04/24/2024] [Accepted: 05/13/2024] [Indexed: 05/31/2024]
Abstract
Chromatin insulators are DNA-protein complexes that promote specificity of enhancer-promoter interactions and maintain distinct transcriptional states through control of 3D genome organization. In this review, we highlight recent work visualizing how mammalian CCCTC-binding factor acts as a boundary to dynamic DNA loop extrusion mediated by cohesin. We also discuss new studies in both mammals and Drosophila that elucidate biological redundancy of chromatin insulator function and interplay with transcription with respect to topologically associating domain formation. Finally, we present novel concepts in spatiotemporal regulation of chromatin insulator function during differentiation and development and possible consequences of disrupted insulator activity on cellular proliferation.
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Affiliation(s)
- Mallika Bhattacharya
- Nuclear Organization and Gene Expression Section, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Savanna F Lyda
- Nuclear Organization and Gene Expression Section, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA; Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, USA; Biological Sciences Graduate Program, University of Maryland, College Park, USA
| | - Elissa P Lei
- Nuclear Organization and Gene Expression Section, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA.
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2
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Kiefer L, Gaudin S, Rajkumar SM, Servito GIF, Langen J, Mui MH, Nawsheen S, Canzio D. Tuning cohesin trajectories enables differential readout of the Pcdhα cluster across neurons. Science 2024; 385:eadm9802. [PMID: 39052779 DOI: 10.1126/science.adm9802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 05/16/2024] [Indexed: 07/27/2024]
Abstract
Expression of Protocadherin (Pcdh) genes is critical to the generation of neuron identity and wiring of the nervous system. Pcdhα genes are arranged in clusters and exhibit a range of expression profiles, from stochastic to deterministic. Because Pcdhα promoters have high sequence identity and share distal enhancers, how distinct neurons choose which gene to express remains unclear. We show that the interplay between multiple enhancers, epigenetics, and genome folding orchestrates differential readouts of the locus across neurons. The probability of Pcdhα promoter choice depends on enhancer/promoter encounters catalyzed by cohesin, whose extrusion trajectories determine the likelihood that an individual promoter can "escape" heterochromatin-mediated silencing. We propose that tunable locus-specific regulatory elements and cell type-specific cohesin activity underlie the generation of cellular diversity by Pcdh genes.
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Affiliation(s)
- Lea Kiefer
- Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA 94158, USA
- Department of Neurology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Simon Gaudin
- Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA 94158, USA
- Department of Neurology, University of California, San Francisco, San Francisco, CA 94158, USA
- Department of Biology, Ecole Normale Supérieure de Lyon, 69432 Lyon, France
| | - Sandy M Rajkumar
- Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA 94158, USA
- Department of Neurology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Gabrielle Isabelle F Servito
- Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA 94158, USA
- Department of Neurology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Jennifer Langen
- Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA 94158, USA
- Department of Neurology, University of California, San Francisco, San Francisco, CA 94158, USA
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Michael H Mui
- Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA 94158, USA
- Department of Neurology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Shayra Nawsheen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Daniele Canzio
- Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA 94158, USA
- Department of Neurology, University of California, San Francisco, San Francisco, CA 94158, USA
- Chan-Zuckerberg Biohub Investigator, San Francisco, San Francisco, CA 94158, USA
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3
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Condemi L, Mocavini I, Aranda S, Di Croce L. Polycomb function in early mouse development. Cell Death Differ 2024:10.1038/s41418-024-01340-3. [PMID: 38997437 DOI: 10.1038/s41418-024-01340-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 06/25/2024] [Accepted: 07/02/2024] [Indexed: 07/14/2024] Open
Abstract
Epigenetic factors are crucial for ensuring proper chromatin dynamics during the initial stages of embryo development. Among these factors, the Polycomb group (PcG) of proteins plays a key role in establishing correct transcriptional programmes during mouse embryogenesis. PcG proteins are classified into two complexes: Polycomb repressive complex 1 (PRC1) and PRC2. Both complexes decorate histone proteins with distinct post-translational modifications (PTMs) that are predictive of a silent transcriptional chromatin state. In recent years, a critical adaptation of the classical techniques to analyse chromatin profiles and to study biochemical interactions at low-input resolution has allowed us to deeply explore PcG molecular mechanisms in the very early stages of mouse embryo development- from fertilisation to gastrulation, and from zygotic genome activation (ZGA) to specific lineages differentiation. These advancements provide a foundation for a deeper understanding of the fundamental role Polycomb complexes play in early development and have elucidated the mechanistic dynamics of PRC1 and PRC2. In this review, we discuss the functions and molecular mechanisms of both PRC1 and PRC2 during early mouse embryo development, integrating new studies with existing knowledge. Furthermore, we highlight the molecular functionality of Polycomb complexes from ZGA through gastrulation, with a particular focus on non-canonical imprinted and bivalent genes, and Hox cluster regulation.
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Affiliation(s)
- Livia Condemi
- Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology, Dr. Aiguader 88, 08003, Barcelona, Spain
| | - Ivano Mocavini
- Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology, Dr. Aiguader 88, 08003, Barcelona, Spain
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA, 01605, USA
| | - Sergi Aranda
- Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology, Dr. Aiguader 88, 08003, Barcelona, Spain
| | - Luciano Di Croce
- Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology, Dr. Aiguader 88, 08003, Barcelona, Spain.
- Universitat Pompeu Fabra (UPF), Barcelona, Spain.
- ICREA, Pg. Lluis Companys 23, 08010, Barcelona, Spain.
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4
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Liberali P, Schier AF. The evolution of developmental biology through conceptual and technological revolutions. Cell 2024; 187:3461-3495. [PMID: 38906136 DOI: 10.1016/j.cell.2024.05.053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Revised: 05/28/2024] [Accepted: 05/29/2024] [Indexed: 06/23/2024]
Abstract
Developmental biology-the study of the processes by which cells, tissues, and organisms develop and change over time-has entered a new golden age. After the molecular genetics revolution in the 80s and 90s and the diversification of the field in the early 21st century, we have entered a phase when powerful technologies provide new approaches and open unexplored avenues. Progress in the field has been accelerated by advances in genomics, imaging, engineering, and computational biology and by emerging model systems ranging from tardigrades to organoids. We summarize how revolutionary technologies have led to remarkable progress in understanding animal development. We describe how classic questions in gene regulation, pattern formation, morphogenesis, organogenesis, and stem cell biology are being revisited. We discuss the connections of development with evolution, self-organization, metabolism, time, and ecology. We speculate how developmental biology might evolve in an era of synthetic biology, artificial intelligence, and human engineering.
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Affiliation(s)
- Prisca Liberali
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland; University of Basel, Basel, Switzerland.
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Wellik DM. Hox genes and patterning the vertebrate body. Curr Top Dev Biol 2024; 159:1-27. [PMID: 38729674 DOI: 10.1016/bs.ctdb.2024.02.011] [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] [Indexed: 05/12/2024]
Abstract
The diversity of vertebrate body plans is dizzying, yet stunning for the many things they have in common. Vertebrates have inhabited virtually every part of the earth from its coldest to warmest climates. They locomote by swimming, flying, walking, slithering, or climbing, or combinations of these behaviors. And they exist in many different sizes, from the smallest of frogs, fish and lizards to giraffes, elephants, and blue whales. Despite these differences, vertebrates follow a remarkably similar blueprint for the establishment of their body plan. Within the relatively small amount of time required to complete gastrulation, the process through which the three germ layers, ectoderm, mesoderm, and endoderm are created, the embryo also generates its body axis and is simultaneously patterned. For the length of this axis, the genes that distinguish the neck from the rib cage or the trunk from the sacrum are the Hox genes. In vertebrates, there was evolutionary pressure to maintain this set of genes in the organism. Over the past decades, much has been learned regarding the regulatory mechanisms that ensure the appropriate expression of these genes along the main body axes. Genetic functions continue to be explored though much has been learned. Much less has been discerned on the identity of co-factors used by Hox proteins for the specificity of transcriptional regulation or what downstream targets and pathways are critical for patterning events, though there are notable exceptions. Current work in the field is demonstrating that Hox genes continue to function in many organs long after directing early patterning events. It is hopeful continued research will shed light on remaining questions regarding mechanisms used by this important and conserved set of transcriptional regulators.
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Affiliation(s)
- Deneen M Wellik
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, WI, United States.
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Rekaik H, Duboule D. A CTCF-dependent mechanism underlies the Hox timer: relation to a segmented body plan. Curr Opin Genet Dev 2024; 85:102160. [PMID: 38377879 DOI: 10.1016/j.gde.2024.102160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 01/27/2024] [Accepted: 01/28/2024] [Indexed: 02/22/2024]
Abstract
During gastrulation, Hox genes are activated in a time-sequence that follows the order of the genes along their clusters. This property, which is observed in all animals that develop following a progressive rostral-to-caudal morphogenesis, is associated with changes in the chromatin structure and epigenetic profiles of Hox clusters, suggesting a process at least partly based on sequential gene accessibility. Here, we discuss recent work on this issue, as well as a possible mechanism based on the surprising conservation in both the distribution and orientation of CTCF sites inside vertebrate Hox clusters.
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Affiliation(s)
- Hocine Rekaik
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland; Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France. https://twitter.com/@hocine_Rekaik
| | - Denis Duboule
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland; Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France.
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Kawasaki K, Fukaya T. Regulatory landscape of enhancer-mediated transcriptional activation. Trends Cell Biol 2024:S0962-8924(24)00020-5. [PMID: 38355349 DOI: 10.1016/j.tcb.2024.01.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 12/21/2023] [Accepted: 01/22/2024] [Indexed: 02/16/2024]
Abstract
Enhancers are noncoding regulatory elements that instruct spatial and temporal specificity of gene transcription in response to a variety of intrinsic and extrinsic signals during development. Although it has long been postulated that enhancers physically interact with target promoters through the formation of stable loops, recent studies have changed this static view: sequence-specific transcription factors (TFs) and coactivators are dynamically recruited to enhancers and assemble so-called transcription hubs. Dynamic assembly of transcription hubs appears to serve as a key scaffold to integrate regulatory information encoded by surrounding genome and biophysical properties of transcription machineries. In this review, we outline emerging new models of transcriptional regulation by enhancers and discuss future perspectives.
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Affiliation(s)
- Koji Kawasaki
- Laboratory of Transcription Dynamics, Research Center for Biological Visualization, Institute for Quantitative Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Takashi Fukaya
- Laboratory of Transcription Dynamics, Research Center for Biological Visualization, Institute for Quantitative Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan; Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan.
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Li X, Levine M. What are tethering elements? Curr Opin Genet Dev 2024; 84:102151. [PMID: 38237456 DOI: 10.1016/j.gde.2023.102151] [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: 10/05/2023] [Revised: 12/19/2023] [Accepted: 12/19/2023] [Indexed: 02/12/2024]
Abstract
High-resolution Micro-C maps identified a specialized class of regulatory DNAs termed 'tethering elements' (TEs) in Drosophila. These 300-500-bp elements facilitate specific long-range genomic associations or loops. The POZ-containing transcription factor GAF (GAGA-associated factor) contributes to loop formation. Tether-tether interactions accelerate Hox gene activation by distal enhancers, and coordinate transcription of duplicated genes (paralogs) through promoter-promoter associations. Some TEs engage in ultra-long-range enhancer-promoter and promoter-promoter interactions (meta-loops) in the Drosophila brain. We discuss the basis for tether-tether specificity and speculate on the occurrence of similar elements in vertebrate genomes.
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Affiliation(s)
- Xiao Li
- Lewis-Sigler Institute, Department of Molecular Biology, Princeton University, Princeton, NJ 08540, USA. https://twitter.com/@XiaoLi5525
| | - Michael Levine
- Lewis-Sigler Institute, Department of Molecular Biology, Princeton University, Princeton, NJ 08540, USA.
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Frith TJR, Briscoe J, Boezio GLM. From signalling to form: the coordination of neural tube patterning. Curr Top Dev Biol 2023; 159:168-231. [PMID: 38729676 DOI: 10.1016/bs.ctdb.2023.11.004] [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] [Indexed: 05/12/2024]
Abstract
The development of the vertebrate spinal cord involves the formation of the neural tube and the generation of multiple distinct cell types. The process starts during gastrulation, combining axial elongation with specification of neural cells and the formation of the neuroepithelium. Tissue movements produce the neural tube which is then exposed to signals that provide patterning information to neural progenitors. The intracellular response to these signals, via a gene regulatory network, governs the spatial and temporal differentiation of progenitors into specific cell types, facilitating the assembly of functional neuronal circuits. The interplay between the gene regulatory network, cell movement, and tissue mechanics generates the conserved neural tube pattern observed across species. In this review we offer an overview of the molecular and cellular processes governing the formation and patterning of the neural tube, highlighting how the remarkable complexity and precision of vertebrate nervous system arises. We argue that a multidisciplinary and multiscale understanding of the neural tube development, paired with the study of species-specific strategies, will be crucial to tackle the open questions.
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Affiliation(s)
| | - James Briscoe
- The Francis Crick Institute, London, United Kingdom.
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