1
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Nocente MC, Mesihovic Karamitsos A, Drouineau E, Soleil M, Albawardi W, Dulary C, Ribierre F, Picaud H, Alibert O, Acker J, Kervella M, Aude JC, Gilbert N, Ochsenbein F, Chantalat S, Gérard M. cBAF generates subnucleosomes that expand OCT4 binding and function beyond DNA motifs at enhancers. Nat Struct Mol Biol 2024:10.1038/s41594-024-01344-0. [PMID: 38956169 DOI: 10.1038/s41594-024-01344-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 06/03/2024] [Indexed: 07/04/2024]
Abstract
The canonical BRG/BRM-associated factor (cBAF) complex is essential for chromatin opening at enhancers in mammalian cells. However, the nature of the open chromatin remains unclear. Here, we show that, in addition to producing histone-free DNA, cBAF generates stable hemisome-like subnucleosomal particles containing the four core histones associated with 50-80 bp of DNA. Our genome-wide analysis indicates that cBAF makes these particles by targeting and splitting fragile nucleosomes. In mouse embryonic stem cells, these subnucleosomes become an in vivo binding substrate for the master transcription factor OCT4 independently of the presence of OCT4 DNA motifs. At enhancers, the OCT4-subnucleosome interaction increases OCT4 occupancy and amplifies the genomic interval bound by OCT4 by up to one order of magnitude compared to the region occupied on histone-free DNA. We propose that cBAF-dependent subnucleosomes orchestrate a molecular mechanism that projects OCT4 function in chromatin opening beyond its DNA motifs.
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Affiliation(s)
- Marina C Nocente
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Anida Mesihovic Karamitsos
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Emilie Drouineau
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Manon Soleil
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Waad Albawardi
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Western General Hospital, Edinburgh, UK
| | - Cécile Dulary
- Université Paris-Saclay, CEA, Centre National de Recherche en Génomique Humaine (CNRGH), Evry, France
| | - Florence Ribierre
- Université Paris-Saclay, CEA, Centre National de Recherche en Génomique Humaine (CNRGH), Evry, France
| | - Hélène Picaud
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Olivier Alibert
- Université Paris-Saclay, CEA, Centre National de Recherche en Génomique Humaine (CNRGH), Evry, France
| | - Joël Acker
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Marie Kervella
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Jean-Christophe Aude
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Nick Gilbert
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Western General Hospital, Edinburgh, UK
| | - Françoise Ochsenbein
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Sophie Chantalat
- Université Paris-Saclay, CEA, Centre National de Recherche en Génomique Humaine (CNRGH), Evry, France
| | - Matthieu Gérard
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France.
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2
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Frenkel M, Raman S. Discovering mechanisms of human genetic variation and controlling cell states at scale. Trends Genet 2024; 40:587-600. [PMID: 38658256 DOI: 10.1016/j.tig.2024.03.010] [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: 02/24/2024] [Revised: 03/29/2024] [Accepted: 03/29/2024] [Indexed: 04/26/2024]
Abstract
Population-scale sequencing efforts have catalogued substantial genetic variation in humans such that variant discovery dramatically outpaces interpretation. We discuss how single-cell sequencing is poised to reveal genetic mechanisms at a rate that may soon approach that of variant discovery. The functional genomics toolkit is sufficiently modular to systematically profile almost any type of variation within increasingly diverse contexts and with molecularly comprehensive and unbiased readouts. As a result, we can construct deep phenotypic atlases of variant effects that span the entire regulatory cascade. The same conceptual approach to interpreting genetic variation should be applied to engineering therapeutic cell states. In this way, variant mechanism discovery and cell state engineering will become reciprocating and iterative processes towards genomic medicine.
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Affiliation(s)
- Max Frenkel
- Cellular and Molecular Biology Graduate Program, University of Wisconsin, Madison, WI, USA; Medical Scientist Training Program, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA; Department of Biochemistry, University of Wisconsin, Madison, WI, USA.
| | - Srivatsan Raman
- Department of Biochemistry, University of Wisconsin, Madison, WI, USA; Department of Bacteriology, University of Wisconsin, Madison, WI, USA; Department of Chemical and Biological Engineering, University of Wisconsin, Madison, WI, USA.
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3
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Stoeber S, Godin H, Xu C, Bai L. Pioneer factors: nature or nurture? Crit Rev Biochem Mol Biol 2024:1-15. [PMID: 38778580 DOI: 10.1080/10409238.2024.2355885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2024] [Accepted: 05/13/2024] [Indexed: 05/25/2024]
Abstract
Chromatin is densely packed with nucleosomes, which limits the accessibility of many chromatin-associated proteins. Pioneer factors (PFs) are usually viewed as a special group of sequence-specific transcription factors (TFs) that can recognize nucleosome-embedded motifs, invade compact chromatin, and generate open chromatin regions. Through this process, PFs initiate a cascade of events that play key roles in gene regulation and cell differentiation. A current debate in the field is if PFs belong to a unique subset of TFs with intrinsic "pioneering activity", or if all TFs have the potential to function as PFs within certain cellular contexts. There are also different views regarding the key feature(s) that define pioneering activity. In this review, we present evidence from the literature related to these alternative views and discuss how to potentially reconcile them. It is possible that both intrinsic properties, like tight nucleosome binding and structural compatibility, and cellular conditions, like concentration and co-factor availability, are important for PF function.
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Affiliation(s)
- Shane Stoeber
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
- Center for Eukaryotic Gene Regulation, The Pennsylvania State University, University Park, PA, USA
| | - Holly Godin
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
- Center for Eukaryotic Gene Regulation, The Pennsylvania State University, University Park, PA, USA
| | - Cheng Xu
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
- Center for Eukaryotic Gene Regulation, The Pennsylvania State University, University Park, PA, USA
| | - Lu Bai
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
- Center for Eukaryotic Gene Regulation, The Pennsylvania State University, University Park, PA, USA
- Department of Physics, The Pennsylvania State University, University Park, PA, USA
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4
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Cerneckis J, Cai H, Shi Y. Induced pluripotent stem cells (iPSCs): molecular mechanisms of induction and applications. Signal Transduct Target Ther 2024; 9:112. [PMID: 38670977 PMCID: PMC11053163 DOI: 10.1038/s41392-024-01809-0] [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: 07/28/2023] [Revised: 03/09/2024] [Accepted: 03/17/2024] [Indexed: 04/28/2024] Open
Abstract
The induced pluripotent stem cell (iPSC) technology has transformed in vitro research and holds great promise to advance regenerative medicine. iPSCs have the capacity for an almost unlimited expansion, are amenable to genetic engineering, and can be differentiated into most somatic cell types. iPSCs have been widely applied to model human development and diseases, perform drug screening, and develop cell therapies. In this review, we outline key developments in the iPSC field and highlight the immense versatility of the iPSC technology for in vitro modeling and therapeutic applications. We begin by discussing the pivotal discoveries that revealed the potential of a somatic cell nucleus for reprogramming and led to successful generation of iPSCs. We consider the molecular mechanisms and dynamics of somatic cell reprogramming as well as the numerous methods available to induce pluripotency. Subsequently, we discuss various iPSC-based cellular models, from mono-cultures of a single cell type to complex three-dimensional organoids, and how these models can be applied to elucidate the mechanisms of human development and diseases. We use examples of neurological disorders, coronavirus disease 2019 (COVID-19), and cancer to highlight the diversity of disease-specific phenotypes that can be modeled using iPSC-derived cells. We also consider how iPSC-derived cellular models can be used in high-throughput drug screening and drug toxicity studies. Finally, we discuss the process of developing autologous and allogeneic iPSC-based cell therapies and their potential to alleviate human diseases.
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Affiliation(s)
- Jonas Cerneckis
- Department of Neurodegenerative Diseases, Beckman Research Institute of City of Hope, Duarte, CA, 91010, USA
- Irell & Manella Graduate School of Biological Sciences, Beckman Research Institute of City of Hope, Duarte, CA, 91010, USA
| | - Hongxia Cai
- Department of Neurodegenerative Diseases, Beckman Research Institute of City of Hope, Duarte, CA, 91010, USA
| | - Yanhong Shi
- Department of Neurodegenerative Diseases, Beckman Research Institute of City of Hope, Duarte, CA, 91010, USA.
- Irell & Manella Graduate School of Biological Sciences, Beckman Research Institute of City of Hope, Duarte, CA, 91010, USA.
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5
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Lian T, Guan R, Zhou BR, Bai Y. Structural mechanism of synergistic targeting of the CX3CR1 nucleosome by PU.1 and C/EBPα. Nat Struct Mol Biol 2024; 31:633-643. [PMID: 38267599 DOI: 10.1038/s41594-023-01189-z] [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: 10/30/2022] [Accepted: 11/23/2023] [Indexed: 01/26/2024]
Abstract
Pioneer transcription factors are vital for cell fate changes. PU.1 and C/EBPα work together to regulate hematopoietic stem cell differentiation. However, how they recognize in vivo nucleosomal DNA targets remains elusive. Here we report the structures of the nucleosome containing the mouse genomic CX3CR1 enhancer DNA and its complexes with PU.1 alone and with both PU.1 and the C/EBPα DNA binding domain. Our structures reveal that PU.1 binds the DNA motif at the exit linker, shifting 17 bp of DNA into the core region through interactions with H2A, unwrapping ~20 bp of nucleosomal DNA. C/EBPα binding, aided by PU.1's repositioning, unwraps ~25 bp of entry DNA. The PU.1 Q218H mutation, linked to acute myeloid leukemia, disrupts PU.1-H2A interactions. PU.1 and C/EBPα jointly displace linker histone H1 and open the H1-condensed nucleosome array. Our study unveils how two pioneer factors can work cooperatively to open closed chromatin by altering DNA positioning in the nucleosome.
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Affiliation(s)
- Tengfei Lian
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
| | - Ruifang Guan
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Bing-Rui Zhou
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Yawen Bai
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
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6
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Barral A, Zaret KS. Pioneer factors: roles and their regulation in development. Trends Genet 2024; 40:134-148. [PMID: 37940484 PMCID: PMC10873006 DOI: 10.1016/j.tig.2023.10.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 10/06/2023] [Accepted: 10/06/2023] [Indexed: 11/10/2023]
Abstract
Pioneer factors are a subclass of transcription factors that can bind and initiate opening of silent chromatin regions. Pioneer factors subsequently regulate lineage-specific genes and enhancers and, thus, activate the zygotic genome after fertilization, guide cell fate transitions during development, and promote various forms of human cancers. As such, pioneer factors are useful in directed cell reprogramming. In this review, we define the structural and functional characteristics of pioneer factors, how they bind and initiate opening of closed chromatin regions, and the consequences for chromatin dynamics and gene expression during cell differentiation. We also discuss emerging mechanisms that modulate pioneer factors during development.
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Affiliation(s)
- Amandine Barral
- Institute for Regenerative Medicine and Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, 3400 Civic Boulevard, Philadelphia, PA 19104, USA
| | - Kenneth S Zaret
- Institute for Regenerative Medicine and Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, 3400 Civic Boulevard, Philadelphia, PA 19104, USA.
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7
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Kondoh H. Molecular Basis of Cell Reprogramming into iPSCs with Exogenous Transcription Factors. Results Probl Cell Differ 2024; 72:193-218. [PMID: 38509259 DOI: 10.1007/978-3-031-39027-2_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
A striking discovery in recent decades concerning the transcription factor (TF)-dependent process was the production of induced pluripotent stem cell (iPSCs) from fibroblasts by the exogenous expression of the TF cocktail containing Oct3/4 (Pou5f1), Sox2, Klf4, and Myc, collectively called OSKM. How fibroblast cells can be remodeled into embryonic stem cell (ESC)-like iPSCs despite high epigenetic barriers has opened a new essential avenue to understanding the action of TFs in developmental regulation. Two forerunning investigations preceded the iPSC phenomenon: exogenous TF-mediated cell remodeling driven by the action of MyoD, and the "pioneer TF" action to preopen chromatin, allowing multiple TFs to access enhancer sequences. The process of remodeling somatic cells into iPSCs has been broken down into multiple subprocesses: the initial attack of OSKM on closed chromatin, sequential changes in cytosine modification, enhancer usage, and gene silencing and activation. Notably, the OSKM TFs change their genomic binding sites extensively. The analyses are still at the descriptive stage, but currently available information is discussed in this chapter.
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Affiliation(s)
- Hisato Kondoh
- Osaka University, Suita, Osaka, Japan
- Biohistory Research Hall, Takatsuki, Osaka, Japan
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8
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Bulyk ML, Drouin J, Harrison MM, Taipale J, Zaret KS. Pioneer factors - key regulators of chromatin and gene expression. Nat Rev Genet 2023; 24:809-815. [PMID: 37740118 DOI: 10.1038/s41576-023-00648-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/02/2023] [Indexed: 09/24/2023]
Affiliation(s)
- Martha L Bulyk
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
| | - Jacques Drouin
- Laboratoire de génétique moléculaire, Institut de recherches cliniques de Montréal (IRCM), Montreal, Quebec, Canada.
- Département de Biochimie, Université de Montréal, Montreal, Quebec, Canada.
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada.
| | - Melissa M Harrison
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI, USA.
| | - Jussi Taipale
- Department of Biochemistry, University of Cambridge, Cambridge, UK.
- Applied Tumour Genomics Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
| | - Kenneth S Zaret
- Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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9
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Lee SW, Frankston CM, Kim J. Epigenome editing in cancer: Advances and challenges for potential therapeutic options. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2023; 383:191-230. [PMID: 38359969 DOI: 10.1016/bs.ircmb.2023.10.001] [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: 02/17/2024]
Abstract
Cancers are diseases caused by genetic and non-genetic environmental factors. Epigenetic alterations, some attributed to non-genetic factors, can lead to cancer development. Epigenetic changes can occur in tumor suppressors or oncogenes, or they may contribute to global cell state changes, making cells abnormal. Recent advances in gene editing technology show potential for cancer treatment. Herein, we will discuss our current knowledge of epigenetic alterations occurring in cancer and epigenetic editing technologies that can be applied to developing therapeutic options.
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Affiliation(s)
- Seung-Won Lee
- Cancer Early Detection Advanced Research Center, Knight Cancer Institute, Oregon Health & Science University, Portland, OR, United States; Department of Molecular and Medical Genetics, School of Medicine, Oregon Health & Science University, Portland, OR, United States
| | - Connor Mitchell Frankston
- Cancer Early Detection Advanced Research Center, Knight Cancer Institute, Oregon Health & Science University, Portland, OR, United States; Biomedical Engineering Graduate Program, Department of Biomedical Engineering, School of Medicine, Oregon Health & Science University, Portland, OR, United States
| | - Jungsun Kim
- Cancer Early Detection Advanced Research Center, Knight Cancer Institute, Oregon Health & Science University, Portland, OR, United States; Department of Molecular and Medical Genetics, School of Medicine, Oregon Health & Science University, Portland, OR, United States; Cancer Biology Research Program, Knight Cancer Institute, Oregon Health & Science University, Portland, OR, United States.
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10
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Nair S, Ameen M, Sundaram L, Pampari A, Schreiber J, Balsubramani A, Wang YX, Burns D, Blau HM, Karakikes I, Wang KC, Kundaje A. Transcription factor stoichiometry, motif affinity and syntax regulate single-cell chromatin dynamics during fibroblast reprogramming to pluripotency. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.04.560808. [PMID: 37873116 PMCID: PMC10592962 DOI: 10.1101/2023.10.04.560808] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Ectopic expression of OCT4, SOX2, KLF4 and MYC (OSKM) transforms differentiated cells into induced pluripotent stem cells. To refine our mechanistic understanding of reprogramming, especially during the early stages, we profiled chromatin accessibility and gene expression at single-cell resolution across a densely sampled time course of human fibroblast reprogramming. Using neural networks that map DNA sequence to ATAC-seq profiles at base-resolution, we annotated cell-state-specific predictive transcription factor (TF) motif syntax in regulatory elements, inferred affinity- and concentration-dependent dynamics of Tn5-bias corrected TF footprints, linked peaks to putative target genes, and elucidated rewiring of TF-to-gene cis-regulatory networks. Our models reveal that early in reprogramming, OSK, at supraphysiological concentrations, rapidly open transient regulatory elements by occupying non-canonical low-affinity binding sites. As OSK concentration falls, the accessibility of these transient elements decays as a function of motif affinity. We find that these OSK-dependent transient elements sequester the somatic TF AP-1. This redistribution is strongly associated with the silencing of fibroblast-specific genes within individual nuclei. Together, our integrated single-cell resource and models reveal insights into the cis-regulatory code of reprogramming at unprecedented resolution, connect TF stoichiometry and motif syntax to diversification of cell fate trajectories, and provide new perspectives on the dynamics and role of transient regulatory elements in somatic silencing.
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Affiliation(s)
- Surag Nair
- Department of Computer Science, Stanford University, Stanford, CA, USA
| | - Mohamed Ameen
- Department of Cancer Biology, Stanford University, Stanford, CA, USA
- Cardiovascular Institute, Stanford University, Stanford, CA, USA
- Department of Dermatology, Stanford University, Stanford, CA, USA
- Program in Epithelial Biology, Stanford University, Stanford, CA, USA
| | | | - Anusri Pampari
- Department of Computer Science, Stanford University, Stanford, CA, USA
| | - Jacob Schreiber
- Department of Genetics, Stanford University, Stanford, CA, USA
| | | | - Yu Xin Wang
- Baxter Laboratory for Stem Cell Biology, Stanford University, Stanford, CA, USA
| | - David Burns
- Baxter Laboratory for Stem Cell Biology, Stanford University, Stanford, CA, USA
| | - Helen M Blau
- Baxter Laboratory for Stem Cell Biology, Stanford University, Stanford, CA, USA
- Department of Microbiology and Immunology, Stanford University, Stanford, CA, USA
| | - Ioannis Karakikes
- Cardiovascular Institute, Stanford University, Stanford, CA, USA
- Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA
| | - Kevin C Wang
- Department of Dermatology, Stanford University, Stanford, CA, USA
- Program in Epithelial Biology, Stanford University, Stanford, CA, USA
- Veterans Affairs Palo Alto Healthcare System, Palo Alto, CA, USA
| | - Anshul Kundaje
- Department of Computer Science, Stanford University, Stanford, CA, USA
- Department of Genetics, Stanford University, Stanford, CA, USA
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11
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Maresca M, van den Brand T, Li H, Teunissen H, Davies J, de Wit E. Pioneer activity distinguishes activating from non-activating SOX2 binding sites. EMBO J 2023; 42:e113150. [PMID: 37691488 PMCID: PMC10577566 DOI: 10.15252/embj.2022113150] [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: 11/25/2022] [Revised: 07/17/2023] [Accepted: 07/22/2023] [Indexed: 09/12/2023] Open
Abstract
Genome-wide transcriptional activity involves the binding of many transcription factors (TFs) to thousands of sites in the genome. Pioneer TFs are a class of TFs that maintain open chromatin and allow non-pioneer TFs access to their target sites. Determining which TF binding sites directly drive transcription remains a challenge. Here, we use acute protein depletion of the pioneer TF SOX2 to establish its functionality in maintaining chromatin accessibility. We show that thousands of accessible sites are lost within an hour of protein depletion, indicating rapid turnover of these sites in the absence of the pioneer factor. To understand the relationship with transcription, we performed nascent transcription analysis and found that open chromatin sites that are maintained by SOX2 are highly predictive of gene expression, in contrast to all other SOX2 binding sites. We use CRISPR-Cas9 genome editing in the Klf2 locus to functionally validate a predicted regulatory element. We conclude that the regulatory activity of SOX2 is exerted mainly at sites where it maintains accessibility and that other binding sites are largely dispensable for gene regulation.
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Affiliation(s)
- Michela Maresca
- Division of Gene RegulationThe Netherlands Cancer InstituteAmsterdamThe Netherlands
| | - Teun van den Brand
- Division of Gene RegulationThe Netherlands Cancer InstituteAmsterdamThe Netherlands
| | - Hangpeng Li
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of MedicineUniversity of OxfordOxfordUK
| | - Hans Teunissen
- Division of Gene RegulationThe Netherlands Cancer InstituteAmsterdamThe Netherlands
| | - James Davies
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of MedicineUniversity of OxfordOxfordUK
| | - Elzo de Wit
- Division of Gene RegulationThe Netherlands Cancer InstituteAmsterdamThe Netherlands
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12
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Lian T, Guan R, Zhou BR, Bai Y. Structural mechanism of synergistic targeting of the CX3CR1 nucleosome by PU.1 and C/EBPα. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.25.554718. [PMID: 37790476 PMCID: PMC10542146 DOI: 10.1101/2023.08.25.554718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Pioneer transcription factors are vital for cell fate changes. PU.1 and C/EBPα work together to regulate hematopoietic stem cell differentiation. However, how they recognize in vivo nucleosomal DNA targets remain elusive. Here we report the structures of the nucleosome containing the mouse genomic CX3CR1 enhancer DNA and its complexes with PU.1 alone and with both PU.1 and the C/EBPα DNA binding domain. Our structures reveal that PU.1 binds the DNA motif at the exit linker, shifting 17 bp of DNA into the core region through interactions with H2A, unwrapping ~20 bp of nucleosomal DNA. C/EBPα binding, aided by PU.1's repositioning, unwraps ~25 bp entry DNA. The PU.1 Q218H mutation, linked to acute myeloid leukemia, disrupts PU.1-H2A interactions. PU.1 and C/EBPα jointly displace linker histone H1 and open the H1-condensed nucleosome array. Our study unveils how two pioneer factors can work cooperatively to open closed chromatin by altering DNA positioning in the nucleosome.
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Affiliation(s)
- Tengfei Lian
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
- These authors equally contributed to this work
| | - Ruifang Guan
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
- These authors equally contributed to this work
| | - Bing-Rui Zhou
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yawen Bai
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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13
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Sinha KK, Bilokapic S, Du Y, Malik D, Halic M. Histone modifications regulate pioneer transcription factor cooperativity. Nature 2023; 619:378-384. [PMID: 37225990 PMCID: PMC10338341 DOI: 10.1038/s41586-023-06112-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 04/21/2023] [Indexed: 05/26/2023]
Abstract
Pioneer transcription factors have the ability to access DNA in compacted chromatin1. Multiple transcription factors can bind together to a regulatory element in a cooperative way, and cooperation between the pioneer transcription factors OCT4 (also known as POU5F1) and SOX2 is important for pluripotency and reprogramming2-4. However, the molecular mechanisms by which pioneer transcription factors function and cooperate on chromatin remain unclear. Here we present cryo-electron microscopy structures of human OCT4 bound to a nucleosome containing human LIN28B or nMATN1 DNA sequences, both of which bear multiple binding sites for OCT4. Our structural and biochemistry data reveal that binding of OCT4 induces changes to the nucleosome structure, repositions the nucleosomal DNA and facilitates cooperative binding of additional OCT4 and of SOX2 to their internal binding sites. The flexible activation domain of OCT4 contacts the N-terminal tail of histone H4, altering its conformation and thus promoting chromatin decompaction. Moreover, the DNA-binding domain of OCT4 engages with the N-terminal tail of histone H3, and post-translational modifications at H3K27 modulate DNA positioning and affect transcription factor cooperativity. Thus, our findings suggest that the epigenetic landscape could regulate OCT4 activity to ensure proper cell programming.
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Affiliation(s)
- Kalyan K Sinha
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Silvija Bilokapic
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Yongming Du
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Deepshikha Malik
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Mario Halic
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA.
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14
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Guan R, Lian T, Zhou BR, Wheeler D, Bai Y. Structural mechanism of LIN28B nucleosome targeting by OCT4. Mol Cell 2023; 83:1970-1982.e6. [PMID: 37327775 PMCID: PMC10276192 DOI: 10.1016/j.molcel.2023.05.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 03/31/2023] [Accepted: 05/19/2023] [Indexed: 06/18/2023]
Abstract
Pioneer transcription factors are essential for cell fate changes by targeting closed chromatin. OCT4 is a crucial pioneer factor that can induce cell reprogramming. However, the structural basis of how pioneer factors recognize the in vivo nucleosomal DNA targets is unknown. Here, we determine the high-resolution structures of the nucleosome containing human LIN28B DNA and its complexes with the OCT4 DNA binding region. Three OCT4s bind the pre-positioned nucleosome by recognizing non-canonical DNA sequences. Two use their POUS domains while the other uses the POUS-loop-POUHD region; POUHD serves as a wedge to unwrap ∼25 base pair DNA. Our analysis of previous genomic data and determination of the ESRRB-nucleosome-OCT4 structure confirmed the generality of these structural features. Moreover, biochemical studies suggest that multiple OCT4s cooperatively open the H1-condensed nucleosome array containing the LIN28B nucleosome. Thus, our study suggests a mechanism of how OCT4 can target the nucleosome and open closed chromatin.
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Affiliation(s)
- Ruifang Guan
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Tengfei Lian
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Bing-Rui Zhou
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - David Wheeler
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yawen Bai
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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15
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McCarthy RL, Zhang J, Zaret KS. Diverse heterochromatin states restricting cell identity and reprogramming. Trends Biochem Sci 2023; 48:513-526. [PMID: 36990958 PMCID: PMC10182259 DOI: 10.1016/j.tibs.2023.02.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 02/16/2023] [Accepted: 02/24/2023] [Indexed: 03/29/2023]
Abstract
Heterochromatin is defined as a chromosomal domain harboring repressive H3K9me2/3 or H3K27me3 histone modifications and relevant factors that physically compact the chromatin. Heterochromatin can restrict where transcription factors bind, providing a barrier to gene activation and changes in cell identity. While heterochromatin thus helps maintain cell differentiation, it presents a barrier to overcome during efforts to reprogram cells for biomedical purposes. Recent findings have revealed complexity in the composition and regulation of heterochromatin, and shown that transiently disrupting the machinery of heterochromatin can enhance reprogramming. Here, we discuss how heterochromatin is established and maintained during development, and how our growing understanding of the mechanisms regulating H3K9me3 heterochromatin can be leveraged to improve our ability to direct changes in cell identity.
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Affiliation(s)
- Ryan L McCarthy
- Institute for Regenerative Medicine, Penn Epigenetics Institute, Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jingchao Zhang
- Institute for Regenerative Medicine, Penn Epigenetics Institute, Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Kenneth S Zaret
- Institute for Regenerative Medicine, Penn Epigenetics Institute, Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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16
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Oses C, Francia MG, Verneri P, Vazquez Echegaray C, Guberman AS, Levi V. The dynamical organization of the core pluripotency transcription factors responds to differentiation cues in early S-phase. Front Cell Dev Biol 2023; 11:1125015. [PMID: 37215075 PMCID: PMC10192714 DOI: 10.3389/fcell.2023.1125015] [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: 12/15/2022] [Accepted: 04/21/2023] [Indexed: 05/24/2023] Open
Abstract
DNA replication in stem cells is a major challenge for pluripotency preservation and cell fate decisions. This process involves massive changes in the chromatin architecture and the reorganization of many transcription-related molecules in different spatial and temporal scales. Pluripotency is controlled by the master transcription factors (TFs) OCT4, SOX2 and NANOG that partition into condensates in the nucleus of embryonic stem cells. These condensates are proposed to play relevant roles in the regulation of gene expression and the maintenance of pluripotency. Here, we asked whether the dynamical distribution of the pluripotency TFs changes during the cell cycle, particularly during DNA replication. Since the S phase is considered to be a window of opportunity for cell fate decisions, we explored if differentiation cues in G1 phase trigger changes in the distribution of these TFs during the subsequent S phase. Our results show a spatial redistribution of TFs condensates during DNA replication which was not directly related to chromatin compaction. Additionally, fluorescence fluctuation spectroscopy revealed TF-specific, subtle changes in the landscape of TF-chromatin interactions, consistent with their particularities as key players of the pluripotency network. Moreover, we found that differentiation stimuli in the preceding G1 phase triggered a relatively fast and massive reorganization of pluripotency TFs in early-S phase. Particularly, OCT4 and SOX2 condensates dissolved whereas the lifetimes of TF-chromatin interactions increased suggesting that the reorganization of condensates is accompanied with a change in the landscape of TF-chromatin interactions. Notably, NANOG showed impaired interactions with chromatin in stimulated early-S cells in line with its role as naïve pluripotency TF. Together, these findings provide new insights into the regulation of the core pluripotency TFs during DNA replication of embryonic stem cells and highlight their different roles at early differentiation stages.
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Affiliation(s)
- Camila Oses
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Marcos Gabriel Francia
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Paula Verneri
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Camila Vazquez Echegaray
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Alejandra Sonia Guberman
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
- Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Valeria Levi
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
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17
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Sinha K, Bilokapic S, Du Y, Malik D, Halic M. Histone modifications regulate pioneer transcription factor binding and cooperativity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.14.532583. [PMID: 36993452 PMCID: PMC10055048 DOI: 10.1101/2023.03.14.532583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
Pioneer transcription factors have the ability to access DNA in compacted chromatin. Multiple transcription factors can bind together to a regulatory element in a cooperative way and cooperation between pioneer transcription factors Oct4 and Sox2 is important for pluripotency and reprogramming. However, the molecular mechanisms by which pioneer transcription factors function and cooperate remain unclear. Here we present cryo-EM structures of human Oct4 bound to a nucleosome containing human Lin28B and nMatn1 DNA sequences, which bear multiple binding sites for Oct4. Our structural and biochemistry data reveal that Oct4 binding induces changes to the nucleosome structure, repositions the nucleosomal DNA and facilitates cooperative binding of additional Oct4 and of Sox2 to their internal binding sites. The flexible activation domain of Oct4 contacts the histone H4 N-terminal tail, altering its conformation and thus promoting chromatin decompaction. Moreover, the DNA binding domain of Oct4 engages with histone H3 N-terminal tail, and posttranslational modifications at H3K27 modulate DNA positioning and affect transcription factor cooperativity. Thus, our data show that the epigenetic landscape can regulate Oct4 activity to ensure proper cell reprogramming.
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Affiliation(s)
- Kalyan Sinha
- Department of Structural Biology, St. Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Silvija Bilokapic
- Department of Structural Biology, St. Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Yongming Du
- Department of Structural Biology, St. Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Deepshikha Malik
- Department of Structural Biology, St. Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Mario Halic
- Department of Structural Biology, St. Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
- Corresponding author:
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18
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Xu JJ, Viny AD. Till SMARCA5 loss do nucleosomes part. Mol Cell 2023; 83:500-501. [PMID: 36804911 PMCID: PMC11104060 DOI: 10.1016/j.molcel.2023.01.022] [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: 01/23/2023] [Revised: 01/23/2023] [Accepted: 01/23/2023] [Indexed: 02/18/2023]
Abstract
In this issue of Molecular Cell, Bomber et al. demonstrate that acute loss of SMARCA5 in human cells leads to eviction of CTCF and an increase in nucleosome repeat length without direct impact on transcriptional activity.
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Affiliation(s)
- Jane Jialu Xu
- Columbia Stem Cell Initiative, Columbia University Irving Medical Center, New York, NY, USA; Department of Medicine, Division of Hematology & Oncology, Columbia University Irving Medical Center, New York, NY, USA
| | - Aaron D Viny
- Columbia Stem Cell Initiative, Columbia University Irving Medical Center, New York, NY, USA; Department of Medicine, Division of Hematology & Oncology, Columbia University Irving Medical Center, New York, NY, USA.
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19
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Malaga Gadea FC, Nikolova EN. Structural Plasticity of Pioneer Factor Sox2 and DNA Bendability Modulate Nucleosome Engagement and Sox2-Oct4 Synergism. J Mol Biol 2023; 435:167916. [PMID: 36495920 PMCID: PMC10184184 DOI: 10.1016/j.jmb.2022.167916] [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: 09/01/2022] [Revised: 12/01/2022] [Accepted: 12/01/2022] [Indexed: 12/12/2022]
Abstract
Pioneer transcription factors (pTFs) can bind directly to silent chromatin and promote vital transcriptional programs. Here, by integrating high-resolution nuclear magnetic resonance (NMR) spectroscopy with biochemistry, we reveal new structural and mechanistic insights into the interaction of pluripotency pTFs and functional partners Sox2 and Oct4 with nucleosomes. We find that the affinity and conformation of Sox2 for solvent-exposed nucleosome sites depend strongly on their position and DNA sequence. Sox2, which is partially disordered but becomes structured upon DNA binding and bending, forms a super-stable nucleosome complex at superhelical location +5 (SHL+5) with similar affinity and conformation to that with naked DNA. However, at suboptimal internal and end-positioned sites where DNA may be harder to deform, Sox2 favors partially unfolded and more dynamic states that are encoded in its intrinsic flexibility. Importantly, Sox2 structure and DNA bending can be stabilized by synergistic Oct4 binding, but only on adjacent motifs near the nucleosome edge and with the full Oct4 DNA-binding domain. Further mutational studies reveal that strategically impaired Sox2 folding is coupled to reduced DNA bending and inhibits nucleosome binding and Sox2-Oct4 cooperation, while increased nucleosomal DNA flexibility enhances Sox2 association. Together, our findings fit a model where the site-specific DNA bending propensity and structural plasticity of Sox2 govern distinct modes of nucleosome engagement and modulate Sox2-Oct4 synergism. The principles outlined here can potentially guide pTF site selection in the genome and facilitate interaction with other chromatin factors or chromatin opening in vivo.
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Affiliation(s)
- Fabiana C Malaga Gadea
- T.C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Evgenia N Nikolova
- T.C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218, USA.
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20
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B1 SINE-binding ZFP266 impedes mouse iPSC generation through suppression of chromatin opening mediated by reprogramming factors. Nat Commun 2023; 14:488. [PMID: 36717582 PMCID: PMC9887000 DOI: 10.1038/s41467-023-36097-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 01/13/2023] [Indexed: 01/31/2023] Open
Abstract
Induced pluripotent stem cell (iPSC) reprogramming is inefficient and understanding the molecular mechanisms underlying this inefficiency holds the key to successfully control cellular identity. Here, we report 24 reprogramming roadblock genes identified by CRISPR/Cas9-mediated genome-wide knockout (KO) screening. Of these, depletion of the predicted KRAB zinc finger protein (KRAB-ZFP) Zfp266 strongly and consistently enhances murine iPSC generation in several reprogramming settings, emerging as the most robust roadblock. We show that ZFP266 binds Short Interspersed Nuclear Elements (SINEs) adjacent to binding sites of pioneering factors, OCT4 (POU5F1), SOX2, and KLF4, and impedes chromatin opening. Replacing the KRAB co-suppressor with co-activator domains converts ZFP266 from an inhibitor to a potent facilitator of iPSC reprogramming. We propose that the SINE-KRAB-ZFP interaction is a critical regulator of chromatin accessibility at regulatory elements required for efficient cellular identity changes. In addition, this work serves as a resource to further illuminate molecular mechanisms hindering reprogramming.
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21
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Tan DS, Cheung SL, Gao Y, Weinbuch M, Hu H, Shi L, Ti SC, Hutchins AP, Cojocaru V, Jauch R. The homeodomain of Oct4 is a dimeric binder of methylated CpG elements. Nucleic Acids Res 2023; 51:1120-1138. [PMID: 36631980 PMCID: PMC9943670 DOI: 10.1093/nar/gkac1262] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 12/14/2022] [Accepted: 12/19/2022] [Indexed: 01/13/2023] Open
Abstract
Oct4 is essential to maintain pluripotency and has a pivotal role in establishing the germline. Its DNA-binding POU domain was recently found to bind motifs with methylated CpG elements normally associated with epigenetic silencing. However, the mode of binding and the consequences of this capability has remained unclear. Here, we show that Oct4 binds to a compact palindromic DNA element with a methylated CpG core (CpGpal) in alternative states of pluripotency and during cellular reprogramming towards induced pluripotent stem cells (iPSCs). During cellular reprogramming, typical Oct4 bound enhancers are uniformly demethylated, with the prominent exception of the CpGpal sites where DNA methylation is often maintained. We demonstrate that Oct4 cooperatively binds the CpGpal element as a homodimer, which contrasts with the ectoderm-expressed POU factor Brn2. Indeed, binding to CpGpal is Oct4-specific as other POU factors expressed in somatic cells avoid this element. Binding assays combined with structural analyses and molecular dynamic simulations show that dimeric Oct4-binding to CpGpal is driven by the POU-homeodomain whilst the POU-specific domain is detached from DNA. Collectively, we report that Oct4 exerts parts of its regulatory function in the context of methylated DNA through a DNA recognition mechanism that solely relies on its homeodomain.
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Affiliation(s)
- Daisylyn Senna Tan
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Shun Lai Cheung
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Ya Gao
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Maike Weinbuch
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China,Institute for Molecular Medicine, Ulm University, Ulm, Germany
| | - Haoqing Hu
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Liyang Shi
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
| | - Shih-Chieh Ti
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Andrew P Hutchins
- Shenzhen Key Laboratory of Gene Regulation and Systems Biology, Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
| | - Vlad Cojocaru
- STAR-UBB Institute, Babeş-Bolyai University, Cluj-Napoca, Romania,Computational Structural Biology Group, Utrecht University, The Netherlands,Max Planck Institute for Molecular Biomedicine, Münster, Germany
| | - Ralf Jauch
- To whom correspondence should be addressed. Tel: +852 3917 9511; Fax: +852 28559730;
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22
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Guan R, Lian T, Zhou BR, Bai Y. Structural mechanism of LIN28B nucleosome targeting by OCT4 for pluripotency. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.03.522631. [PMID: 36789416 PMCID: PMC9928048 DOI: 10.1101/2023.01.03.522631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Pioneer transcription factors are essential for cell fate changes by targeting closed chromatin. OCT4 is a crucial pioneer factor that can induce cell reprogramming. However, the structural basis of how pioneer factors recognize the in vivo nucleosomal DNA targets is unknown. Here, we determine the high-resolution structures of the nucleosome containing human LIN28B DNA and its complexes with the OCT4 DNA binding region. Three OCT4s bind the pre-positioned nucleosome by recognizing non-canonical DNA motifs. Two use their POUS domains by forming extensive hydrogen bonds. The other uses the POUS-loop-POUHD region; POUHD serves as a wedge to unwrap ∼25 base pair DNA. Biochemical studies suggest that multiple OCT4s cooperatively open the H1-condensed nucleosome array containing the LIN28B nucleosome. Our study suggests a mechanism whereby OCT4s target the LIN28B nucleosome by forming multivalent interactions with nucleosomal motifs, unwrapping nucleosomal DNA, evicting H1, and cooperatively open closed chromatin to initiate cell reprogramming.
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Affiliation(s)
- Ruifang Guan
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.,These authors equally contributed to this work
| | - Tengfei Lian
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.,These authors equally contributed to this work
| | - Bing-Rui Zhou
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Yawen Bai
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.,Correspondence:
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23
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Abstract
Genomic DNA wraps around core histones to form nucleosomes, which provides steric constraints on how transcription factors (TFs) can interact with gene regulatory sequences. It is increasingly apparent that well-positioned, accessible nucleosomes are an inherent feature of active enhancers and can facilitate cooperative TF binding, referred to as nucleosome-mediated cooperativity. Thus, profiling chromatin and nucleosome properties (accessibility, positioning, and occupancy) on the genome is crucial to understand cell-type-specific gene regulation. Here we describe a simplified protocol to profile accessible nucleosomes in the mammalian genome using low-level and high-level micrococcal nuclease (MNase) digestion followed by genome-wide sequencing.
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Affiliation(s)
- Hee-Woong Lim
- Division of Biomedical Informatics, Cincinnati Children's Hospital Medical Center, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Makiko Iwafuchi
- Division of Developmental Biology, Center for Stem Cell & Organoid Medicine (CuSTOM), Cincinnati Children's Hospital Medical Center, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
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24
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Frederick MA, Williamson KE, Fernandez Garcia M, Ferretti MB, McCarthy RL, Donahue G, Luzete Monteiro E, Takenaka N, Reynaga J, Kadoch C, Zaret KS. A pioneer factor locally opens compacted chromatin to enable targeted ATP-dependent nucleosome remodeling. Nat Struct Mol Biol 2023; 30:31-37. [PMID: 36536103 PMCID: PMC10004348 DOI: 10.1038/s41594-022-00886-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 11/03/2022] [Indexed: 12/24/2022]
Abstract
To determine how different pioneer transcription factors form a targeted, accessible nucleosome within compacted chromatin and collaborate with an ATP-dependent chromatin remodeler, we generated nucleosome arrays in vitro with a central nucleosome containing binding sites for the hematopoietic E-Twenty Six (ETS) factor PU.1 and Basic Leucine Zipper (bZIP) factors C/EBPα and C/EBPβ. Our long-read sequencing reveals that each factor can expose a targeted nucleosome on linker histone-compacted arrays, but with different nuclease sensitivity patterns. The DNA binding domain of PU.1 binds mononucleosomes, but requires an additional intrinsically disordered domain to bind and open compacted chromatin. The canonical mammalian SWI/SNF (cBAF) remodeler was unable to act upon two forms of locally open chromatin unless cBAF was enabled by a separate transactivation domain of PU.1. cBAF potentiates the PU.1 DNA binding domain to weakly open chromatin in the absence of the PU.1 disordered domain. Our findings reveal a hierarchy by which chromatin is opened and show that pioneer factors can provide specificity for action by nucleosome remodelers.
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Affiliation(s)
- Megan A Frederick
- Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Institute for Immunology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Kaylyn E Williamson
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, USA
| | - Meilin Fernandez Garcia
- Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Max B Ferretti
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Ryan L McCarthy
- Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Greg Donahue
- Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Edgar Luzete Monteiro
- Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department of Biology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA, USA
| | - Naomi Takenaka
- Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Janice Reynaga
- Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Cigall Kadoch
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, USA
| | - Kenneth S Zaret
- Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
- Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
- Department Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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25
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Larcombe MR, Hsu S, Polo JM, Knaupp AS. Indirect Mechanisms of Transcription Factor-Mediated Gene Regulation during Cell Fate Changes. ADVANCED GENETICS (HOBOKEN, N.J.) 2022; 3:2200015. [PMID: 36911290 PMCID: PMC9993476 DOI: 10.1002/ggn2.202200015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Indexed: 06/18/2023]
Abstract
Transcription factors (TFs) are the master regulators of cellular identity, capable of driving cell fate transitions including differentiations, reprogramming, and transdifferentiations. Pioneer TFs recognize partial motifs exposed on nucleosomal DNA, allowing for TF-mediated activation of repressed chromatin. Moreover, there is evidence suggesting that certain TFs can repress actively expressed genes either directly through interactions with accessible regulatory elements or indirectly through mechanisms that impact the expression, activity, or localization of other regulatory factors. Recent evidence suggests that during reprogramming, the reprogramming TFs initiate opening of chromatin regions rich in somatic TF motifs that are inaccessible in the initial and final cellular states. It is postulated that analogous to a sponge, these transiently accessible regions "soak up" somatic TFs, hence lowering the initial barriers to cell fate changes. This indirect TF-mediated gene regulation event, which is aptly named the "sponge effect," may play an essential role in the silencing of the somatic transcriptional network during different cellular conversions.
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Affiliation(s)
- Michael R. Larcombe
- Department of Anatomy and Developmental BiologyMonash UniversityClaytonVictoria3168Australia
- Development and Stem Cells ProgramMonash Biomedicine Discovery InstituteClaytonVictoria3168Australia
- Australian Regenerative Medicine InstituteMonash UniversityClaytonVictoria3168Australia
| | - Sheng Hsu
- Department of Anatomy and Developmental BiologyMonash UniversityClaytonVictoria3168Australia
- Development and Stem Cells ProgramMonash Biomedicine Discovery InstituteClaytonVictoria3168Australia
- Australian Regenerative Medicine InstituteMonash UniversityClaytonVictoria3168Australia
| | - Jose M. Polo
- Department of Anatomy and Developmental BiologyMonash UniversityClaytonVictoria3168Australia
- Development and Stem Cells ProgramMonash Biomedicine Discovery InstituteClaytonVictoria3168Australia
- Australian Regenerative Medicine InstituteMonash UniversityClaytonVictoria3168Australia
- South Australian Immunogenomics Cancer Institute, Faculty of Health and Medical SciencesUniversity of AdelaideAdelaideSouth Australia5005Australia
- Adelaide Centre for Epigenetics, Faculty of Health and Medical SciencesUniversity of AdelaideAdelaideSouth Australia5005Australia
| | - Anja S. Knaupp
- Department of Anatomy and Developmental BiologyMonash UniversityClaytonVictoria3168Australia
- Development and Stem Cells ProgramMonash Biomedicine Discovery InstituteClaytonVictoria3168Australia
- Australian Regenerative Medicine InstituteMonash UniversityClaytonVictoria3168Australia
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26
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Pluta R, Aragón E, Prescott NA, Ruiz L, Mees RA, Baginski B, Flood JR, Martin-Malpartida P, Massagué J, David Y, Macias MJ. Molecular basis for DNA recognition by the maternal pioneer transcription factor FoxH1. Nat Commun 2022; 13:7279. [PMID: 36435807 PMCID: PMC9701222 DOI: 10.1038/s41467-022-34925-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 11/10/2022] [Indexed: 11/28/2022] Open
Abstract
Forkhead box H1 (FoxH1) is an essential maternal pioneer factor during embryonic development that binds to specific GG/GT-containing DNA target sequences. Here we have determined high-resolution structures of three FoxH1 proteins (from human, frog and fish species) and four DNAs to clarify the way in which FoxH1 binds to these sites. We found that the protein-DNA interactions extend to both the minor and major DNA grooves and are thus almost twice as extensive as those of other FOX family members. Moreover, we identified two specific amino acid changes in FoxH1 that allowed the recognition of GG/GT motifs. Consistent with the pioneer factor activity of FoxH1, we found that its affinity for nucleosomal DNA is even higher than for linear DNA fragments. The structures reported herein illustrate how FoxH1 binding to distinct DNA sites provides specificity and avoids cross-regulation by other FOX proteins that also operate during the maternal-zygotic transition and select canonical forkhead sites.
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Affiliation(s)
- Radoslaw Pluta
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, 08028, Spain
| | - Eric Aragón
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, 08028, Spain
| | - Nicholas A Prescott
- Tri-Institutional PhD Program in Chemical Biology, New York, NY, USA
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Lidia Ruiz
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, 08028, Spain
| | - Rebeca A Mees
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, 08028, Spain
| | - Blazej Baginski
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, 08028, Spain
| | - Julia R Flood
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Pau Martin-Malpartida
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, 08028, Spain
| | - Joan Massagué
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Yael David
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
- Department of Pharmacology, Weill Cornell Medicine, New York, NY, 10065, USA
- Department of Physiology, Biophysics and Systems Biology, Weill Cornell Medicine, New York, NY, 10065, USA
| | - Maria J Macias
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, 08028, Spain.
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys 23, Barcelona, 08010, Spain.
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27
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Lo JHH, Edwards M, Langerman J, Sridharan R, Plath K, Smale ST. Oct4:Sox2 binding is essential for establishing but not maintaining active and silent states of dynamically regulated genes in pluripotent cells. Genes Dev 2022; 36:1079-1095. [PMID: 36418052 PMCID: PMC9744233 DOI: 10.1101/gad.350113.122] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 11/14/2022] [Indexed: 11/24/2022]
Abstract
Much has been learned about the mechanisms of action of pluripotency factors Oct4 and Sox2. However, as with other regulators of cell identity, little is known about the impact of disrupting their binding motifs in a native environment or the characteristics of genes they regulate. By quantitatively examining dynamic ranges of gene expression instead of focusing on conventional measures of differential expression, we found that Oct4 and Sox2 enhancer binding is strongly enriched near genes subject to large dynamic ranges of expression among cell types, with binding sites near these genes usually within superenhancers. Mutagenesis of representative Oct4:Sox2 motifs near such active, dynamically regulated genes revealed critical roles in transcriptional activation during reprogramming, with more limited roles in transcriptional maintenance in the pluripotent state. Furthermore, representative motifs near silent genes were critical for establishing but not maintaining the fully silent state, while genes whose transcript levels varied by smaller magnitudes among cell types were unaffected by nearby Oct4:Sox2 motifs. These results suggest that Oct4 and Sox2 directly establish both active and silent transcriptional states in pluripotent cells at a large number of genes subject to dynamic regulation during mammalian development, but are less important than expected for maintaining transcriptional states.
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Affiliation(s)
- Jerry Hung-Hao Lo
- Molecular Biology Institute, Immunology, and Molecular Genetics, University of California at Los Angeles, Los Angeles, California 90095, USA
- Broad Stem Cell Research Center, Immunology, and Molecular Genetics, University of California at Los Angeles, Los Angeles, California 90095, USA
- Department of Microbiology, Immunology, and Molecular Genetics, University of California at Los Angeles, Los Angeles, California 90095, USA
| | - Miguel Edwards
- Molecular Biology Institute, Immunology, and Molecular Genetics, University of California at Los Angeles, Los Angeles, California 90095, USA
- Broad Stem Cell Research Center, Immunology, and Molecular Genetics, University of California at Los Angeles, Los Angeles, California 90095, USA
- Department of Microbiology, Immunology, and Molecular Genetics, University of California at Los Angeles, Los Angeles, California 90095, USA
| | - Justin Langerman
- Molecular Biology Institute, Immunology, and Molecular Genetics, University of California at Los Angeles, Los Angeles, California 90095, USA
- Broad Stem Cell Research Center, Immunology, and Molecular Genetics, University of California at Los Angeles, Los Angeles, California 90095, USA
- Department of Microbiology, Immunology, and Molecular Genetics, University of California at Los Angeles, Los Angeles, California 90095, USA
| | - Rupa Sridharan
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, Wisconsin 53715, USA
| | - Kathrin Plath
- Molecular Biology Institute, Immunology, and Molecular Genetics, University of California at Los Angeles, Los Angeles, California 90095, USA
- Broad Stem Cell Research Center, Immunology, and Molecular Genetics, University of California at Los Angeles, Los Angeles, California 90095, USA
- Department of Biological Chemistry, University of California at Los Angeles, Los Angeles, California 90095, USA
| | - Stephen T Smale
- Molecular Biology Institute, Immunology, and Molecular Genetics, University of California at Los Angeles, Los Angeles, California 90095, USA
- Broad Stem Cell Research Center, Immunology, and Molecular Genetics, University of California at Los Angeles, Los Angeles, California 90095, USA
- Department of Microbiology, Immunology, and Molecular Genetics, University of California at Los Angeles, Los Angeles, California 90095, USA
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28
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Yaglova NV, Obernikhin SS, Nazimova SV, Timokhina EP, Yaglov VV. Changes in the Expression of Transcription Factor Oct4 during Postnatal Development of Adrenal Medulla. Bull Exp Biol Med 2022; 173:783-786. [DOI: 10.1007/s10517-022-05631-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Indexed: 11/11/2022]
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29
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MacCarthy CM, Huertas J, Ortmeier C, Vom Bruch H, Tan DS, Reinke D, Sander A, Bergbrede T, Jauch R, Schöler HR, Cojocaru V. OCT4 interprets and enhances nucleosome flexibility. Nucleic Acids Res 2022; 50:10311-10327. [PMID: 36130732 PMCID: PMC9561370 DOI: 10.1093/nar/gkac755] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 07/28/2022] [Accepted: 08/24/2022] [Indexed: 01/06/2023] Open
Abstract
Pioneer transcription factors are proteins that induce cellular identity transitions by binding to inaccessible regions of DNA in nuclear chromatin. They contribute to chromatin opening and recruit other factors to regulatory DNA elements. The structural features and dynamics modulating their interaction with nucleosomes are still unresolved. From a combination of experiments and molecular simulations, we reveal here how the pioneer factor and master regulator of pluripotency, Oct4, interprets and enhances nucleosome structural flexibility. The magnitude of Oct4’s impact on nucleosome dynamics depends on the binding site position and the mobility of the unstructured tails of nucleosomal histone proteins. Oct4 uses both its DNA binding domains to propagate and stabilize open nucleosome conformations, one for specific sequence recognition and the other for nonspecific interactions with nearby regions of DNA. Our findings provide a structural basis for the versatility of transcription factors in engaging with nucleosomes and have implications for understanding how pioneer factors induce chromatin dynamics.
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Affiliation(s)
- Caitlin M MacCarthy
- Department of Cellular and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany
| | - Jan Huertas
- Department of Cellular and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany.,Yusuf Hamied Department of Chemistry, University of Cambridge, UK
| | - Claudia Ortmeier
- Department of Cellular and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany
| | - Hermann Vom Bruch
- Department of Cellular and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany
| | - Daisylyn Senna Tan
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong SAR, China
| | - Deike Reinke
- Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Astrid Sander
- Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | | | - Ralf Jauch
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong SAR, China
| | - Hans R Schöler
- Department of Cellular and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany.,Medical Faculty, University of Münster, Germany
| | - Vlad Cojocaru
- Department of Cellular and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany.,Computational Structural Biology Group, University of Utrecht, The Netherlands.,STAR-UBB Institute, Babeş-Bolyai University, Cluj-Napoca, Romania
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30
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Yang MG, Ling E, Cowley CJ, Greenberg ME, Vierbuchen T. Characterization of sequence determinants of enhancer function using natural genetic variation. eLife 2022; 11:76500. [PMID: 36043696 PMCID: PMC9662815 DOI: 10.7554/elife.76500] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Accepted: 08/30/2022] [Indexed: 02/04/2023] Open
Abstract
Sequence variation in enhancers that control cell-type-specific gene transcription contributes significantly to phenotypic variation within human populations. However, it remains difficult to predict precisely the effect of any given sequence variant on enhancer function due to the complexity of DNA sequence motifs that determine transcription factor (TF) binding to enhancers in their native genomic context. Using F1-hybrid cells derived from crosses between distantly related inbred strains of mice, we identified thousands of enhancers with allele-specific TF binding and/or activity. We find that genetic variants located within the central region of enhancers are most likely to alter TF binding and enhancer activity. We observe that the AP-1 family of TFs (Fos/Jun) are frequently required for binding of TEAD TFs and for enhancer function. However, many sequence variants outside of core motifs for AP-1 and TEAD also impact enhancer function, including sequences flanking core TF motifs and AP-1 half sites. Taken together, these data represent one of the most comprehensive assessments of allele-specific TF binding and enhancer function to date and reveal how sequence changes at enhancers alter their function across evolutionary timescales.
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Affiliation(s)
- Marty G Yang
- Department of Neurobiology, Harvard Medical School, Boston, United States.,Program in Neuroscience, Harvard Medical School, Boston, United States
| | - Emi Ling
- Department of Neurobiology, Harvard Medical School, Boston, United States
| | | | | | - Thomas Vierbuchen
- Developmental Biology Program, Sloan Kettering Institute for Cancer Research, New York, United States.,Center for Stem Cell Biology, Sloan Kettering Institute for Cancer Research, New York, United States
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31
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Luzete-Monteiro E, Zaret KS. Structures and consequences of pioneer factor binding to nucleosomes. Curr Opin Struct Biol 2022; 75:102425. [PMID: 35863165 PMCID: PMC9976633 DOI: 10.1016/j.sbi.2022.102425] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 06/10/2022] [Accepted: 06/16/2022] [Indexed: 11/15/2022]
Abstract
Pioneer transcription factors are able to bind a partially exposed motif on the surface of a nucleosome, enabling the proteins to target sites in silent regions of chromatin that have been compacted by linker histone. The targeting of nucleosomal DNA by pioneer factors has been observed in vitro and in vivo, where binding can promote local nucleosome exposure that allows other transcription factors, nucleosome remodelers, and histone modifiers to engage the chromatin and elicit gene activation or further repression. Pioneer factors thereby establish new gene expression programs during cell fate changes that occur during embryonic development, regeneration, and cancer. Here, we review recent biophysical studies that reveal the structural features and strategies used by pioneer factors to accomplish nucleosome binding and the consequential changes to nucleosomes that can lead to DNA accessibility.
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Affiliation(s)
- Edgar Luzete-Monteiro
- Institute for Regenerative Medicine, Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, 9-131 SCTR, 3400 Civic Center Blvd., Philadelphia, PA 19104-5157, USA.,Department of Biology, School of Arts and Sciences, University of Pennsylvania, 433 S University Ave, Philadelphia, PA 19104-4544
| | - Kenneth S. Zaret
- Institute for Regenerative Medicine, Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, 9-131 SCTR, 3400 Civic Center Blvd., Philadelphia, PA 19104-5157, USA
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32
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Hörnblad A, Remeseiro S. Epigenetics, Enhancer Function and 3D Chromatin Organization in Reprogramming to Pluripotency. Cells 2022; 11:cells11091404. [PMID: 35563711 PMCID: PMC9105757 DOI: 10.3390/cells11091404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 04/13/2022] [Accepted: 04/19/2022] [Indexed: 12/22/2022] Open
Abstract
Genome architecture, epigenetics and enhancer function control the fate and identity of cells. Reprogramming to induced pluripotent stem cells (iPSCs) changes the transcriptional profile and chromatin landscape of the starting somatic cell to that of the pluripotent cell in a stepwise manner. Changes in the regulatory networks are tightly regulated during normal embryonic development to determine cell fate, and similarly need to function in cell fate control during reprogramming. Switching off the somatic program and turning on the pluripotent program involves a dynamic reorganization of the epigenetic landscape, enhancer function, chromatin accessibility and 3D chromatin topology. Within this context, we will review here the current knowledge on the processes that control the establishment and maintenance of pluripotency during somatic cell reprogramming.
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Affiliation(s)
- Andreas Hörnblad
- Umeå Centre for Molecular Medicine (UCMM), Umeå University, 901 87 Umeå, Sweden
- Correspondence: (A.H.); (S.R.)
| | - Silvia Remeseiro
- Umeå Centre for Molecular Medicine (UCMM), Umeå University, 901 87 Umeå, Sweden
- Wallenberg Centre for Molecular Medicine (WCMM), Umeå University, 901 87 Umeå, Sweden
- Correspondence: (A.H.); (S.R.)
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33
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Bakhmet EI, Tomilin AN. Key features of the POU transcription factor Oct4 from an evolutionary perspective. Cell Mol Life Sci 2021; 78:7339-7353. [PMID: 34698883 PMCID: PMC11072838 DOI: 10.1007/s00018-021-03975-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Revised: 09/16/2021] [Accepted: 10/12/2021] [Indexed: 01/06/2023]
Abstract
Oct4, a class V POU-domain protein that is encoded by the Pou5f1 gene, is thought to be a key transcription factor in the early development of mammals. This transcription factor plays indispensable roles in pluripotent stem cells as well as in the acquisition of pluripotency during somatic cell reprogramming. Oct4 has also been shown to play a role as a pioneer transcription factor during zygotic genome activation (ZGA) from zebrafish to human. However, during the past decade, several studies have brought these conclusions into question. It was clearly shown that the first steps in mouse development are not affected by the loss of Oct4. Subsequently, the role of Oct4 as a genome activator was brought into doubt. It was also found that the reprogramming of somatic cells into induced pluripotent stem cells (iPSCs) could proceed without Oct4. In this review, we summarize recent findings, reassess the role of Oct4 in reprogramming and ZGA, and point to structural features that may underlie this role. We speculate that pluripotent stem cells resemble neural stem cells more closely than previously thought. Oct4 orthologs within the POUV class hold key roles in genome activation during early development of species with late ZGA. However, in Placentalia, eutherian-specific proteins such as Dux overtake Oct4 in ZGA and endow them with the formation of an evolutionary new tissue-the placenta.
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Affiliation(s)
- Evgeny I Bakhmet
- Laboratory of the Molecular Biology of Stem Cells, Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia.
| | - Alexey N Tomilin
- Laboratory of the Molecular Biology of Stem Cells, Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia
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34
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Fu Y, Shan Y, Zhang M, Pei D. Phase separating cell fate. Cell Stem Cell 2021; 28:1677-1678. [PMID: 34624226 DOI: 10.1016/j.stem.2021.09.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
How master regulators such as Oct4 can shape 3D genome architecture during cell reprogramming remains poorly understood. In this issue of Cell Stem Cell, Wang et al. (2021) demonstrate that Oct4 undergoes phase separation to reconfigure TAD architecture for cell fate control.
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Affiliation(s)
- Yu Fu
- Laboratory of Cell Fate Control, School of Life Sciences, Westlake University, Hangzhou, China
| | - Yuanyue Shan
- Laboratory of Cell Fate Control, School of Life Sciences, Westlake University, Hangzhou, China
| | - Mingfeng Zhang
- Laboratory of Cell Fate Control, School of Life Sciences, Westlake University, Hangzhou, China
| | - Duanqing Pei
- Laboratory of Cell Fate Control, School of Life Sciences, Westlake University, Hangzhou, China.
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