1
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Bower G, Hollingsworth EW, Jacinto S, Clock B, Cao K, Liu M, Dziulko A, Alcaina-Caro A, Xu Q, Skowronska-Krawczyk D, Lopez-Rios J, Dickel DE, Bardet AF, Pennacchio LA, Visel A, Kvon EZ. Conserved Cis-Acting Range Extender Element Mediates Extreme Long-Range Enhancer Activity in Mammals. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.26.595809. [PMID: 38826394 PMCID: PMC11142232 DOI: 10.1101/2024.05.26.595809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
While most mammalian enhancers regulate their cognate promoters over moderate distances of tens of kilobases (kb), some enhancers act over distances in the megabase range. The sequence features enabling such extreme-distance enhancer-promoter interactions remain elusive. Here, we used in vivo enhancer replacement experiments in mice to show that short- and medium-range enhancers cannot initiate gene expression at extreme-distance range. We uncover a novel conserved cis-acting element, Range EXtender (REX), that confers extreme-distance regulatory activity and is located next to a long-range enhancer of Sall1. The REX element itself has no endogenous enhancer activity. However, addition of the REX to other short- and mid-range enhancers substantially increases their genomic interaction range. In the most extreme example observed, addition of the REX increased the range of an enhancer by an order of magnitude, from its native 71kb to 840kb. The REX element contains highly conserved [C/T]AATTA homeodomain motifs. These motifs are enriched around long-range limb enhancers genome-wide, including the ZRS, a benchmark long-range limb enhancer of Shh. Mutating the [C/T]AATTA motifs within the ZRS does not affect its limb-specific enhancer activity at short range, but selectively abolishes its long-range activity, resulting in severe limb reduction in knock-in mice. In summary, we identify a sequence signature globally associated with long-range enhancer-promoter interactions and describe a prototypical REX element that is necessary and sufficient to confer extreme-distance gene activation by remote enhancers.
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Affiliation(s)
- Grace Bower
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92967, USA
| | - Ethan W. Hollingsworth
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92967, USA
- Medical Scientist Training Program, University of California, Irvine, CA 92967, USA
| | - Sandra Jacinto
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92967, USA
| | - Benjamin Clock
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92967, USA
| | - Kaitlyn Cao
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92967, USA
| | - Mandy Liu
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92967, USA
| | - Adam Dziulko
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Ana Alcaina-Caro
- Centro Andaluz de Biología del Desarrollo (CABD), CSIC-Universidad Pablo de Olavide-Junta de Andalucía, Seville, 41013, Spain
| | - Qianlan Xu
- Department of Physiology and Biophysics, Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, University of California, Irvine, CA, USA
| | - Dorota Skowronska-Krawczyk
- Department of Physiology and Biophysics, Department of Ophthalmology, Center for Translational Vision Research, School of Medicine, University of California, Irvine, CA, USA
| | - Javier Lopez-Rios
- Centro Andaluz de Biología del Desarrollo (CABD), CSIC-Universidad Pablo de Olavide-Junta de Andalucía, Seville, 41013, Spain
| | - Diane E. Dickel
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Anaïs F. Bardet
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Université de Strasbourg, CNRS UMR7104, INSERM U1258, 67400 Illkirch, France
| | - Len A. Pennacchio
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, CA 94598, USA
- Comparative Biochemistry Program, University of California, Berkeley, CA 94720, USA
| | - Axel Visel
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, CA 94598, USA
- School of Natural Sciences, University of California, Merced, CA 95343, USA
| | - Evgeny Z. Kvon
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92967, USA
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2
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Wang H, Bienz M, Yan XX, Xu W. Structural basis of the interaction between BCL9-Pygo and LDB-SSBP complexes in assembling the Wnt enhanceosome. Nat Commun 2023; 14:3702. [PMID: 37349336 PMCID: PMC10287724 DOI: 10.1038/s41467-023-39439-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 06/14/2023] [Indexed: 06/24/2023] Open
Abstract
The Wnt enhanceosome is responsible for transactivation of Wnt-responsive genes and a promising therapeutic target for treatment of numerous cancers with Adenomatous Polyposis Coli (APC) or β-catenin mutations. How the Wnt enhanceosome is assembled remains poorly understood. Here we show that B-cell lymphoma 9 protein (BCL9), Pygopus (Pygo), LIM domain-binding protein 1 (LDB1) and single-stranded DNA-binding protein (SSBP) form a stable core complex within the Wnt enhanceosome. Their mutual interactions rely on a highly conserved N-terminal asparagine proline phenylalanine (NPF) motif of Pygo, through which the BCL9-Pygo complex binds to the LDB-SSBP core complex. Our crystal structure of a ternary complex comprising the N-terminus of human Pygo2, LDB1 and SSBP2 reveals a single LDB1-SSBP2 complex binding simultaneously to two Pygo2 molecules via their NPF motifs. These interactions critically depend on the NPF motifs which bind to a deep groove formed between LDB1 and SSBP2, potentially constituting a binding site for drugs blocking Wnt/β-catenin signaling. Analysis of human cell lines lacking LDB or Pygo supports the functional relevance of the Pygo-LDB1-SSBP2 interaction for Wnt/β-catenin-dependent transcription.
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Affiliation(s)
- Hongyang Wang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Mariann Bienz
- Medical Research Council Laboratory of Molecular Biology, CB2 0QH, Cambridge, United Kingdom
| | - Xiao-Xue Yan
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
| | - Wenqing Xu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China.
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3
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Afzal Z, Lange JJ, Nolte C, McKinney S, Wood C, Paulson A, De Kumar B, Unruh J, Slaughter BD, Krumlauf R. Shared retinoic acid responsive enhancers coordinately regulate nascent transcription of Hoxb coding and non-coding RNAs in the developing mouse neural tube. Development 2023; 150:dev201259. [PMID: 37102683 PMCID: PMC10233718 DOI: 10.1242/dev.201259] [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] [Accepted: 04/19/2023] [Indexed: 04/28/2023]
Abstract
Signaling pathways regulate the patterns of Hox gene expression that underlie their functions in the specification of axial identity. Little is known about the properties of cis-regulatory elements and underlying transcriptional mechanisms that integrate graded signaling inputs to coordinately control Hox expression. Here, we optimized a single molecule fluorescent in situ hybridization (smFISH) technique with probes spanning introns to evaluate how three shared retinoic acid response element (RARE)-dependent enhancers in the Hoxb cluster regulate patterns of nascent transcription in vivo at the level of single cells in wild-type and mutant embryos. We predominately detect nascent transcription of only a single Hoxb gene in each cell, with no evidence for simultaneous co-transcriptional coupling of all or specific subsets of genes. Single and/or compound RARE mutations indicate that each enhancer differentially impacts global and local patterns of nascent transcription, suggesting that selectivity and competitive interactions between these enhancers is important to robustly maintain the proper levels and patterns of nascent Hoxb transcription. This implies that rapid and dynamic regulatory interactions potentiate transcription of genes through combined inputs from these enhancers in coordinating the retinoic acid response.
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Affiliation(s)
- Zainab Afzal
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
- Anatomy and Cell Biology Department, Kansas University Medical Center, Kansas City, KS 66160, USA
| | - Jeffrey J. Lange
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Christof Nolte
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Sean McKinney
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Christopher Wood
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Ariel Paulson
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Bony De Kumar
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Jay Unruh
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | | | - Robb Krumlauf
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
- Anatomy and Cell Biology Department, Kansas University Medical Center, Kansas City, KS 66160, USA
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4
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Medlock-Lanier T, Clay KB, Roberts-Galbraith RH. Planarian LDB and SSDP proteins scaffold transcriptional complexes for regeneration and patterning. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.07.527523. [PMID: 36798167 PMCID: PMC9934679 DOI: 10.1101/2023.02.07.527523] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Sequence-specific transcription factors often function as components of large regulatory complexes. LIM-domain binding protein (LDB) and single-stranded DNA-binding protein (SSDP) function as core scaffolds of transcriptional complexes in animals and plants. Little is known about potential partners and functions for LDB/SSDP complexes in the context of tissue regeneration. In this work, we find that planarian LDB1 and SSDP2 promote tissue regeneration, with a particular function in mediolateral polarity reestablishment. We find that LDB1 and SSDP2 interact with one another and with characterized planarian LIM-HD proteins Arrowhead, Islet1, and Lhx1/5-1. SSDP2 and LDB1 also function with islet1 in polarity reestablishment and with lhx1/5-1 in serotonergic neuron maturation. Finally, we show new roles for LDB1 and SSDP2 in regulating gene expression in the planarian intestine and parenchyma; these functions may be LIM-HD-independent. Together, our work provides insight into LDB/SSDP complexes in a highly regenerative organism. Further, our work provides a strong starting point for identifying and characterizing potential binding partners of LDB1 and SSDP2 and for exploring roles for these proteins in diverse aspects of planarian physiology.
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Affiliation(s)
| | - Kendall B Clay
- Neuroscience Program, University of Georgia, Athens, GA, USA
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5
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Bharti M, Bajpai A, Rautela U, Manzar N, Ateeq B, Sinha P. Human ERG oncoprotein represses a Drosophila LIM domain binding protein-coding gene Chip. Proc Natl Acad Sci U S A 2023; 120:e2211189119. [PMID: 36595681 PMCID: PMC9926275 DOI: 10.1073/pnas.2211189119] [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: 06/29/2022] [Accepted: 10/24/2022] [Indexed: 01/05/2023] Open
Abstract
Human ETS Related Gene, ERG, a master transcription factor, turns oncogenic upon its out-of-context activation in diverse developmental lineages. However, the mechanism underlying its lineage-specific activation of Notch (N), Wnt, or EZH2-three well-characterized oncogenic targets of ERG-remains elusive. We reasoned that deep homology in genetic tool kits might help uncover such elusive cancer mechanisms in Drosophila. By heterologous gain of human ERG in Drosophila, here we reveal Chip, which codes for a transcriptional coactivator, LIM-domain-binding (LDB) protein, as its novel target. ERG represses Drosophila Chip via its direct binding and, indirectly, via E(z)-mediated silencing of its promoter. Downregulation of Chip disrupts LIM-HD complex formed between Chip and Tailup (Tup)-a LIM-HD transcription factor-in the developing notum. A consequent activation of N-driven Wg signaling leads to notum-to-wing transdetermination. These fallouts of ERG gain are arrested upon a simultaneous gain of Chip, sequestration of Wg ligand, and, alternatively, loss of N signaling or E(z) activity. Finally, we show that the human LDB1, a homolog of Drosophila Chip, is repressed in ERG-positive prostate cancer cells. Besides identifying an elusive target of human ERG, our study unravels an underpinning of its lineage-specific carcinogenesis.
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Affiliation(s)
- Mahima Bharti
- Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, India, 208016
| | - Anjali Bajpai
- Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, India, 208016
- Mehta Family Center for Engineering in Medicine, Indian Institute of Technology Kanpur, India, 208016
| | - Umanshi Rautela
- Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, India, 208016
- National Institute of Immunology, India, 110067
| | - Nishat Manzar
- Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, India, 208016
| | - Bushra Ateeq
- Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, India, 208016
- Mehta Family Center for Engineering in Medicine, Indian Institute of Technology Kanpur, India, 208016
| | - Pradip Sinha
- Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, India, 208016
- Mehta Family Center for Engineering in Medicine, Indian Institute of Technology Kanpur, India, 208016
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6
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Kyrchanova OV, Bylino OV, Georgiev PG. Mechanisms of enhancer-promoter communication and chromosomal architecture in mammals and Drosophila. Front Genet 2022; 13:1081088. [PMID: 36531247 PMCID: PMC9751008 DOI: 10.3389/fgene.2022.1081088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 11/18/2022] [Indexed: 12/03/2022] Open
Abstract
The spatial organization of chromosomes is involved in regulating the majority of intranuclear processes in higher eukaryotes, including gene expression. Drosophila was used as a model to discover many transcription factors whose homologs play a key role in regulation of gene expression in mammals. According to modern views, a cohesin complex mostly determines the architecture of mammalian chromosomes by forming chromatin loops on anchors created by the CTCF DNA-binding architectural protein. The role of the cohesin complex in chromosome architecture is poorly understood in Drosophila, and CTCF is merely one of many Drosophila architectural proteins with a proven potential to organize specific long-range interactions between regulatory elements in the genome. The review compares the mechanisms responsible for long-range interactions and chromosome architecture between mammals and Drosophila.
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7
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Diacou R, Nandigrami P, Fiser A, Liu W, Ashery-Padan R, Cvekl A. Cell fate decisions, transcription factors and signaling during early retinal development. Prog Retin Eye Res 2022; 91:101093. [PMID: 35817658 PMCID: PMC9669153 DOI: 10.1016/j.preteyeres.2022.101093] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 06/02/2022] [Accepted: 06/03/2022] [Indexed: 12/30/2022]
Abstract
The development of the vertebrate eyes is a complex process starting from anterior-posterior and dorso-ventral patterning of the anterior neural tube, resulting in the formation of the eye field. Symmetrical separation of the eye field at the anterior neural plate is followed by two symmetrical evaginations to generate a pair of optic vesicles. Next, reciprocal invagination of the optic vesicles with surface ectoderm-derived lens placodes generates double-layered optic cups. The inner and outer layers of the optic cups develop into the neural retina and retinal pigment epithelium (RPE), respectively. In vitro produced retinal tissues, called retinal organoids, are formed from human pluripotent stem cells, mimicking major steps of retinal differentiation in vivo. This review article summarizes recent progress in our understanding of early eye development, focusing on the formation the eye field, optic vesicles, and early optic cups. Recent single-cell transcriptomic studies are integrated with classical in vivo genetic and functional studies to uncover a range of cellular mechanisms underlying early eye development. The functions of signal transduction pathways and lineage-specific DNA-binding transcription factors are dissected to explain cell-specific regulatory mechanisms underlying cell fate determination during early eye development. The functions of homeodomain (HD) transcription factors Otx2, Pax6, Lhx2, Six3 and Six6, which are required for early eye development, are discussed in detail. Comprehensive understanding of the mechanisms of early eye development provides insight into the molecular and cellular basis of developmental ocular anomalies, such as optic cup coloboma. Lastly, modeling human development and inherited retinal diseases using stem cell-derived retinal organoids generates opportunities to discover novel therapies for retinal diseases.
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Affiliation(s)
- Raven Diacou
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Prithviraj Nandigrami
- Department of Systems and Computational Biology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Andras Fiser
- Department of Systems and Computational Biology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Wei Liu
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Ruth Ashery-Padan
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Ales Cvekl
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA; Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
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8
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Popay TM, Dixon JR. Coming full circle: on the origin and evolution of the looping model for enhancer-promoter communication. J Biol Chem 2022; 298:102117. [PMID: 35691341 PMCID: PMC9283939 DOI: 10.1016/j.jbc.2022.102117] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 05/26/2022] [Accepted: 05/27/2022] [Indexed: 11/05/2022] Open
Abstract
In mammalian organisms, enhancers can regulate transcription from great genomic distances. How enhancers affect distal gene expression has been a major question in the field of gene regulation. One model to explain how enhancers communicate with their target promoters, the chromatin looping model, posits that enhancers and promoters come in close spatial proximity to mediate communication. Chromatin looping has been broadly accepted as a means for enhancer–promoter communication, driven by accumulating in vitro and in vivo evidence. The genome is now known to be folded into a complex 3D arrangement, created and maintained in part by the interplay of the Cohesin complex and the DNA-binding protein CTCF. In the last few years, however, doubt over the relationship between looping and transcriptional activation has emerged, driven by studies finding that only a modest number of genes are perturbed with acute degradation of looping machinery components. In parallel, newer models describing distal enhancer action have also come to prominence. In this article, we explore the emergence and development of the looping model as a means for enhancer–promoter communication and review the contrasting evidence between historical gene-specific and current global data for the role of chromatin looping in transcriptional regulation. We also discuss evidence for alternative models to chromatin looping and their support in the literature. We suggest that, while there is abundant evidence for chromatin looping as a major mechanism for enhancer function, enhancer–promoter communication is likely mediated by more than one mechanism in an enhancer- and context-dependent manner.
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Affiliation(s)
- Tessa M Popay
- Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Jesse R Dixon
- Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
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9
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Abstract
Enhancers control the establishment of spatiotemporal gene expression patterns throughout development. Over the past decade, the development of new technologies has improved our capacity to link enhancers with their target genes based on their colocalization within the same topological domains. However, the mechanisms that regulate how enhancers specifically activate some genes but not others within a given domain remain unclear. In this Review, we discuss recent insights into the factors controlling enhancer specificity, including the genetic composition of enhancers and promoters, the linear and 3D distance between enhancers and their target genes, and cell-type specific chromatin landscapes. We also discuss how elucidating the molecular principles of enhancer specificity might help us to better understand and predict the pathological consequences of human genetic, epigenetic and structural variants.
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Affiliation(s)
- Tomás Pachano
- Institute of Biomedicine and Biotechnology of Cantabria (IBBTEC), CSIC/Universidad de Cantabria/SODERCAN, Albert Einstein 22, 39011 Santander, Spain
| | - Endika Haro
- Institute of Biomedicine and Biotechnology of Cantabria (IBBTEC), CSIC/Universidad de Cantabria/SODERCAN, Albert Einstein 22, 39011 Santander, Spain
| | - Alvaro Rada-Iglesias
- Institute of Biomedicine and Biotechnology of Cantabria (IBBTEC), CSIC/Universidad de Cantabria/SODERCAN, Albert Einstein 22, 39011 Santander, Spain
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10
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Andrieu-Soler C, Soler E. Erythroid Cell Research: 3D Chromatin, Transcription Factors and Beyond. Int J Mol Sci 2022; 23:ijms23116149. [PMID: 35682828 PMCID: PMC9181152 DOI: 10.3390/ijms23116149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 05/19/2022] [Accepted: 05/20/2022] [Indexed: 02/04/2023] Open
Abstract
Studies of the regulatory networks and signals controlling erythropoiesis have brought important insights in several research fields of biology and have been a rich source of discoveries with far-reaching implications beyond erythroid cells biology. The aim of this review is to highlight key recent discoveries and show how studies of erythroid cells bring forward novel concepts and refine current models related to genome and 3D chromatin organization, signaling and disease, with broad interest in life sciences.
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Affiliation(s)
| | - Eric Soler
- IGMM, Université Montpellier, CNRS, 34093 Montpellier, France;
- Laboratory of Excellence GR-Ex, Université de Paris, 75015 Paris, France
- Correspondence:
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11
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Liu Y, Ding B, Zheng L, Xu P, Liu Z, Chen Z, Wu P, Zhao Y, Pan Q, Guo Y, Wang W, Wei W. Regulatory elements can be essential for maintaining broad chromatin organization and cell viability. Nucleic Acids Res 2022; 50:4340-4354. [PMID: 35390162 PMCID: PMC9071426 DOI: 10.1093/nar/gkac197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 03/03/2022] [Accepted: 03/15/2022] [Indexed: 11/14/2022] Open
Abstract
Increasing evidence shows that promoters and enhancers could be related to 3D chromatin structure, thus affecting cellular functions. Except for their roles in forming canonical chromatin loops, promoters and enhancers have not been well studied regarding the maintenance of broad chromatin organization. Here, we focused on the active promoters/enhancers predicted to form many 3D contacts with other active promoters/enhancers (referred to as hotspots) and identified dozens of loci essential for cell growth and survival through CRISPR screening. We found that the deletion of an essential hotspot could lead to changes in broad chromatin organization and the expression of distal genes. We showed that the essentiality of hotspots does not result from their association with individual genes that are essential for cell viability but rather from their association with multiple dysregulated non-essential genes to synergistically impact cell fitness.
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Affiliation(s)
- Ying Liu
- Biomedical Pioneering Innovation Center, Beijing Advanced Innovation Center for Genomics, Peking-Tsinghua Center for Life Sciences, Peking University Genome Editing Research Center, State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Bo Ding
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0359, USA
| | - Lina Zheng
- Bioinformatics and Systems Biology Program, University of California, San Diego, La Jolla, CA 92093-0359, USA
| | - Ping Xu
- Biomedical Pioneering Innovation Center, Beijing Advanced Innovation Center for Genomics, Peking-Tsinghua Center for Life Sciences, Peking University Genome Editing Research Center, State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Zhiheng Liu
- Biomedical Pioneering Innovation Center, Beijing Advanced Innovation Center for Genomics, Peking-Tsinghua Center for Life Sciences, Peking University Genome Editing Research Center, State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Zhao Chen
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0359, USA
| | - Peiyao Wu
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0359, USA
| | - Ying Zhao
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0359, USA
| | - Qian Pan
- Biomedical Pioneering Innovation Center, Beijing Advanced Innovation Center for Genomics, Peking-Tsinghua Center for Life Sciences, Peking University Genome Editing Research Center, State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Yu Guo
- Biomedical Pioneering Innovation Center, Beijing Advanced Innovation Center for Genomics, Peking-Tsinghua Center for Life Sciences, Peking University Genome Editing Research Center, State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Wei Wang
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0359, USA.,Bioinformatics and Systems Biology Program, University of California, San Diego, La Jolla, CA 92093-0359, USA.,Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093-0359, USA
| | - Wensheng Wei
- Biomedical Pioneering Innovation Center, Beijing Advanced Innovation Center for Genomics, Peking-Tsinghua Center for Life Sciences, Peking University Genome Editing Research Center, State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
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12
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Transcriptional Regulation and Implications for Controlling Hox Gene Expression. J Dev Biol 2022; 10:jdb10010004. [PMID: 35076545 PMCID: PMC8788451 DOI: 10.3390/jdb10010004] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/04/2022] [Accepted: 01/06/2022] [Indexed: 02/06/2023] Open
Abstract
Hox genes play key roles in axial patterning and regulating the regional identity of cells and tissues in a wide variety of animals from invertebrates to vertebrates. Nested domains of Hox expression generate a combinatorial code that provides a molecular framework for specifying the properties of tissues along the A–P axis. Hence, it is important to understand the regulatory mechanisms that coordinately control the precise patterns of the transcription of clustered Hox genes required for their roles in development. New insights are emerging about the dynamics and molecular mechanisms governing transcriptional regulation, and there is interest in understanding how these may play a role in contributing to the regulation of the expression of the clustered Hox genes. In this review, we summarize some of the recent findings, ideas and emerging mechanisms underlying the regulation of transcription in general and consider how they may be relevant to understanding the transcriptional regulation of Hox genes.
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13
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Consolidation and maintenance of long-term memory involve dual functions of the developmental regulator Apterous in clock neurons and mushroom bodies in the Drosophila brain. PLoS Biol 2021; 19:e3001459. [PMID: 34860826 PMCID: PMC8641882 DOI: 10.1371/journal.pbio.3001459] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 10/25/2021] [Indexed: 11/23/2022] Open
Abstract
Memory is initially labile but can be consolidated into stable long-term memory (LTM) that is stored in the brain for extended periods. Despite recent progress, the molecular and cellular mechanisms underlying the intriguing neurobiological processes of LTM remain incompletely understood. Using the Drosophila courtship conditioning assay as a memory paradigm, here, we show that the LIM homeodomain (LIM-HD) transcription factor Apterous (Ap), which is known to regulate various developmental events, is required for both the consolidation and maintenance of LTM. Interestingly, Ap is involved in these 2 memory processes through distinct mechanisms in different neuronal subsets in the adult brain. Ap and its cofactor Chip (Chi) are indispensable for LTM maintenance in the Drosophila memory center, the mushroom bodies (MBs). On the other hand, Ap plays a crucial role in memory consolidation in a Chi-independent manner in pigment dispersing factor (Pdf)-containing large ventral–lateral clock neurons (l-LNvs) that modulate behavioral arousal and sleep. Since disrupted neurotransmission and electrical silencing in clock neurons impair memory consolidation, Ap is suggested to contribute to the stabilization of memory by ensuring the excitability of l-LNvs. Indeed, ex vivo imaging revealed that a reduced function of Ap, but not Chi, results in exaggerated Cl− responses to the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) in l-LNvs, indicating that wild-type (WT) Ap maintains high l-LNv excitability by suppressing the GABA response. Consistently, enhancing the excitability of l-LNvs by knocking down GABAA receptors compensates for the impaired memory consolidation in ap null mutants. Overall, our results revealed unique dual functions of the developmental regulator Ap for LTM consolidation in clock neurons and LTM maintenance in MBs. A neurogenetic study using Drosophila reveals that the centrally expressed LIM-homeodomain transcription factor Apterous plays a crucial neuron-type-dependent role in two different memory processes - consolidation and maintenance of long-term memory.
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14
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Kyrchanova O, Georgiev P. Mechanisms of Enhancer-Promoter Interactions in Higher Eukaryotes. Int J Mol Sci 2021; 22:ijms22020671. [PMID: 33445415 PMCID: PMC7828040 DOI: 10.3390/ijms22020671] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 12/28/2020] [Accepted: 01/09/2021] [Indexed: 12/13/2022] Open
Abstract
In higher eukaryotes, enhancers determine the activation of developmental gene transcription in specific cell types and stages of embryogenesis. Enhancers transform the signals produced by various transcription factors within a given cell, activating the transcription of the targeted genes. Often, developmental genes can be associated with dozens of enhancers, some of which are located at large distances from the promoters that they regulate. Currently, the mechanisms underlying specific distance interactions between enhancers and promoters remain poorly understood. This review briefly describes the properties of enhancers and discusses the mechanisms of distance interactions and potential proteins involved in this process.
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15
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Zhai H, Zhang X, You Y, Lin L, Zhou W, Li C. SEUSS integrates transcriptional and epigenetic control of root stem cell organizer specification. EMBO J 2020; 39:e105047. [PMID: 32926464 PMCID: PMC7560201 DOI: 10.15252/embj.2020105047] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 08/12/2020] [Accepted: 08/14/2020] [Indexed: 11/09/2022] Open
Abstract
Proper regulation of homeotic gene expression is critical for stem cell fate in both plants and animals. In Arabidopsis thaliana, the WUSCHEL (WUS)-RELATED HOMEOBOX 5 (WOX5) gene is specifically expressed in a group of root stem cell organizer cells called the quiescent center (QC) and plays a central role in QC specification. Here, we report that the SEUSS (SEU) protein, homologous to the animal LIM-domain binding (LDB) proteins, assembles a functional transcriptional complex that regulates WOX5 expression and QC specification. SEU is physically recruited to the WOX5 promoter by the master transcription factor SCARECROW. Subsequently, SEU physically recruits the SET domain methyltransferase SDG4 to the WOX5 promoter, thus activating WOX5 expression. Thus, analogous to its animal counterparts, SEU acts as a multi-adaptor protein that integrates the actions of genetic and epigenetic regulators into a concerted transcriptional program to control root stem cell organizer specification.
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Affiliation(s)
- Huawei Zhai
- State Key Laboratory of Plant Genomics, National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Innovation Academy of Seed Design, Chinese Academy of Sciences, Beijing, China.,CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
| | - Xiaoyue Zhang
- State Key Laboratory of Plant Genomics, National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Innovation Academy of Seed Design, Chinese Academy of Sciences, Beijing, China
| | - Yanrong You
- State Key Laboratory of Plant Genomics, National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Innovation Academy of Seed Design, Chinese Academy of Sciences, Beijing, China
| | - Lihao Lin
- State Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Tai'an, Shandong Province, China
| | - Wenkun Zhou
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, China.,Frontier Science Center for Molecular Design and Breeding, China Agricultural University, Beijing, China
| | - Chuanyou Li
- State Key Laboratory of Plant Genomics, National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Innovation Academy of Seed Design, Chinese Academy of Sciences, Beijing, China.,CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, China
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16
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Melnikova LS, Georgiev PG, Golovnin AK. The Functions and Mechanisms of Action of Insulators in the Genomes of Higher Eukaryotes. Acta Naturae 2020; 12:15-33. [PMID: 33456975 PMCID: PMC7800606 DOI: 10.32607/actanaturae.11144] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 10/12/2020] [Indexed: 12/22/2022] Open
Abstract
The mechanisms underlying long-range interactions between chromatin regions and the principles of chromosomal architecture formation are currently under extensive scrutiny. A special class of regulatory elements known as insulators is believed to be involved in the regulation of specific long-range interactions between enhancers and promoters. This review focuses on the insulators of Drosophila and mammals, and it also briefly characterizes the proteins responsible for their functional activity. It was initially believed that the main properties of insulators are blocking of enhancers and the formation of independent transcription domains. We present experimental data proving that the chromatin loops formed by insulators play only an auxiliary role in enhancer blocking. The review also discusses the mechanisms involved in the formation of topologically associating domains and their role in the formation of the chromosomal architecture and regulation of gene transcription.
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Affiliation(s)
- L. S. Melnikova
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, 119334 Russia
| | - P. G. Georgiev
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, 119334 Russia
| | - A. K. Golovnin
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, 119334 Russia
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17
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Structure and function of Pygo in organ development dependent and independent Wnt signalling. Biochem Soc Trans 2020; 48:1781-1794. [PMID: 32677664 DOI: 10.1042/bst20200393] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 06/22/2020] [Accepted: 06/24/2020] [Indexed: 11/17/2022]
Abstract
Pygo is a nuclear protein containing two conserved domains, NHD and PHD, which play important roles in embryonic development and carcinogenesis. Pygo was first identified as a core component of the Wnt/β-catenin signalling pathway. However, it has also been reported that the function of Pygo is not always Wnt/β-catenin signalling dependent. In this review, we summarise the functions of both domains of Pygo and show that their functions are synergetic. The PHD domain mainly combines with transcription co-factors, including histone 3 and Bcl9/9l. The NHD domain mainly recruits histone methyltransferase/acetyltransferase (HMT/HAT) to modify lysine 4 of the histone 3 tail (H3K4) and interacts with Chip/LIM-domain DNA-binding proteins (ChiLS) to form enhanceosomes to regulate transcriptional activity. Furthermore, we summarised chromatin modification differences of Pygo in Drosophila (dPygo) and vertebrates, and found that Pygo displayes a chromatin silencing function in Drosophila, while in vertebates, Pygo has a chromatin-activating function due to the two substitution of two amino acid residues. Next, we confirmed the relationship between Pygo and Bcl9/9l and found that Pygo-Bcl/9l are specifically partnered both in the nucleus and in the cytoplasm. Finally, we discuss whether transcriptional activity of Pygo is Wnt/β-catenin dependent during embryonic development. Available information indications that the transcriptional activity of Pygo in embryonic development is either Wnt/β-catenin dependent or independent in both tissue-specific and cell-specific-modes.
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18
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Bylino OV, Ibragimov AN, Shidlovskii YV. Evolution of Regulated Transcription. Cells 2020; 9:E1675. [PMID: 32664620 PMCID: PMC7408454 DOI: 10.3390/cells9071675] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 07/07/2020] [Accepted: 07/10/2020] [Indexed: 12/12/2022] Open
Abstract
The genomes of all organisms abound with various cis-regulatory elements, which control gene activity. Transcriptional enhancers are a key group of such elements in eukaryotes and are DNA regions that form physical contacts with gene promoters and precisely orchestrate gene expression programs. Here, we follow gradual evolution of this regulatory system and discuss its features in different organisms. In eubacteria, an enhancer-like element is often a single regulatory element, is usually proximal to the core promoter, and is occupied by one or a few activators. Activation of gene expression in archaea is accompanied by the recruitment of an activator to several enhancer-like sites in the upstream promoter region. In eukaryotes, activation of expression is accompanied by the recruitment of activators to multiple enhancers, which may be distant from the core promoter, and the activators act through coactivators. The role of the general DNA architecture in transcription control increases in evolution. As a whole, it can be seen that enhancers of multicellular eukaryotes evolved from the corresponding prototypic enhancer-like regulatory elements with the gradually increasing genome size of organisms.
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Affiliation(s)
- Oleg V. Bylino
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., 119334 Moscow, Russia; (O.V.B.); (A.N.I.)
| | - Airat N. Ibragimov
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., 119334 Moscow, Russia; (O.V.B.); (A.N.I.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., 119334 Moscow, Russia
| | - Yulii V. Shidlovskii
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., 119334 Moscow, Russia; (O.V.B.); (A.N.I.)
- I.M. Sechenov First Moscow State Medical University, 8, bldg. 2 Trubetskaya St., 119048 Moscow, Russia
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19
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Renko M, Fiedler M, Rutherford TJ, Schaefer JV, Plückthun A, Bienz M. Rotational symmetry of the structured Chip/LDB-SSDP core module of the Wnt enhanceosome. Proc Natl Acad Sci U S A 2019; 116:20977-20983. [PMID: 31570581 PMCID: PMC6800368 DOI: 10.1073/pnas.1912705116] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The Chip/LIM-domain binding protein (LDB)-single-stranded DNA-binding protein (SSDP) (ChiLS) complex controls numerous cell-fate decisions in animal cells, by mediating transcription of developmental control genes via remote enhancers. ChiLS is recruited to these enhancers by lineage-specific LIM-domain proteins that bind to its Chip/LDB subunit. ChiLS recently emerged as the core module of the Wnt enhanceosome, a multiprotein complex that primes developmental control genes for timely Wnt responses. ChiLS binds to NPFxD motifs within Pygopus (Pygo) and the Osa/ARID1A subunit of the BAF chromatin remodeling complex, which could synergize with LIM proteins in tethering ChiLS to enhancers. Chip/LDB and SSDP both contain N-terminal dimerization domains that constitute the bulk of their structured cores. Here, we report the crystal structures of these dimerization domains, in part aided by DARPin chaperones. We conducted systematic surface scanning by structure-designed mutations, followed by in vitro and in vivo binding assays, to determine conserved surface residues required for binding between Chip/LDB, SSDP, and Pygo-NPFxD. Based on this, and on the 4:2 (SSDP-Chip/LDB) stoichiometry of ChiLS, we derive a highly constrained structural model for this complex, which adopts a rotationally symmetrical SSDP2-LDB2-SSDP2 architecture. Integrity of ChiLS is essential for Pygo binding, and our mutational analysis places the NPFxD pockets on either side of the Chip/LDB dimer, each flanked by an SSDP dimer. The symmetry and multivalency of ChiLS underpin its function as an enhancer module integrating Wnt signals with lineage-specific factors to operate context-dependent transcriptional switches that are pivotal for normal development and cancer.
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Affiliation(s)
- Miha Renko
- Medical Research Council Laboratory of Molecular Biology, CB2 0QH Cambridge, United Kingdom
| | - Marc Fiedler
- Medical Research Council Laboratory of Molecular Biology, CB2 0QH Cambridge, United Kingdom
| | - Trevor J Rutherford
- Medical Research Council Laboratory of Molecular Biology, CB2 0QH Cambridge, United Kingdom
| | - Jonas V Schaefer
- Department of Biochemistry, University of Zurich, 8057 Zurich, Switzerland
| | - Andreas Plückthun
- Department of Biochemistry, University of Zurich, 8057 Zurich, Switzerland
| | - Mariann Bienz
- Medical Research Council Laboratory of Molecular Biology, CB2 0QH Cambridge, United Kingdom;
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20
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Enhancer long-range contacts: The multi-adaptor protein LDB1 is the tie that binds. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2019; 1862:625-633. [DOI: 10.1016/j.bbagrm.2019.04.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 04/03/2019] [Accepted: 04/05/2019] [Indexed: 11/20/2022]
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21
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Abstract
Developmental enhancers mediate on/off patterns of gene expression in specific cell types at particular stages during metazoan embryogenesis. They typically integrate multiple signals and regulatory determinants to achieve precise spatiotemporal expression. Such enhancers can map quite far-one megabase or more-from the genes they regulate. How remote enhancers relay regulatory information to their target promoters is one of the central mysteries of genome organization and function. A variety of contrasting mechanisms have been proposed over the years, including enhancer tracking, linking, looping, and mobilization to transcription factories. We argue that extreme versions of these mechanisms cannot account for the transcriptional dynamics and precision seen in living cells, tissues, and embryos. We describe emerging evidence for dynamic three-dimensional hubs that combine different elements of the classical models.
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Affiliation(s)
- Eileen E M Furlong
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, D-69117, Heidelberg, Germany.
| | - Michael Levine
- Lewis-Sigler Institute for Integrative Genomics, Princeton, NJ 08540, USA. .,Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
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22
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Abstract
A hundred years after Lhx2 ortholog apterous was identified as a critical regulator of wing development in Drosophila, LIM-HD gene family members have proved to be versatile and powerful components of the molecular machinery that executes the blueprint of embryogenesis across vertebrate and invertebrate species. Here, we focus on the spatio-temporally varied functions of LIM-homeodomain transcription factor LHX2 in the developing mouse forebrain. Right from its earliest known role in telencephalic and eye field patterning, to the control of the neuron-glia cell fate switch, and the regulation of axon pathfinding and dendritic arborization in late embryonic stages, LHX2 has been identified as a fundamental, temporally dynamic, always necessary, and often sufficient factor in a range of critical developmental phenomena. While Lhx2 mutant phenotypes have been characterized in detail in multiple brain structures, only recently have we advanced in our understanding of the molecular mechanisms by which this factor acts. Common themes emerge from how this multifunctional molecule controls a range of developmental steps in distinct forebrain structures. Examining these shared features, and noting unique aspects of LHX2 function is likely to inform our understanding of how a single factor can bring about a diversity of effects and play central and critical roles across systems and stages. The parallels in LHX2 and APTEROUS functions, and the protein complexes they participate in, offer insights into evolutionary strategies that conserve tool kits and deploy them to play new, yet familiar roles in species separated by hundreds of millions of years.
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Affiliation(s)
- Shen-Ju Chou
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Shubha Tole
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai 400005, India.
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23
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Werner K, Donow C, Pandur P. Chip/Ldb1 interacts with Tailup/islet1 to regulate cardiac gene expression inDrosophila. Genesis 2017; 55. [DOI: 10.1002/dvg.23030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 03/09/2017] [Accepted: 03/10/2017] [Indexed: 11/11/2022]
Affiliation(s)
- Kathrin Werner
- Institut für Biochemie und Molekulare Biologie; Albert-Einstein-Allee 11; 89081 Ulm Germany
| | - Cornelia Donow
- Institut für Biochemie und Molekulare Biologie; Albert-Einstein-Allee 11; 89081 Ulm Germany
| | - Petra Pandur
- Institut für Biochemie und Molekulare Biologie; Albert-Einstein-Allee 11; 89081 Ulm Germany
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24
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van Tienen LM, Mieszczanek J, Fiedler M, Rutherford TJ, Bienz M. Constitutive scaffolding of multiple Wnt enhanceosome components by Legless/BCL9. eLife 2017; 6:e20882. [PMID: 28296634 PMCID: PMC5352222 DOI: 10.7554/elife.20882] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 02/07/2017] [Indexed: 12/30/2022] Open
Abstract
Wnt/β-catenin signaling elicits context-dependent transcription switches that determine normal development and oncogenesis. These are mediated by the Wnt enhanceosome, a multiprotein complex binding to the Pygo chromatin reader and acting through TCF/LEF-responsive enhancers. Pygo renders this complex Wnt-responsive, by capturing β-catenin via the Legless/BCL9 adaptor. We used CRISPR/Cas9 genome engineering of Drosophila legless (lgs) and human BCL9 and B9L to show that the C-terminus downstream of their adaptor elements is crucial for Wnt responses. BioID proximity labeling revealed that BCL9 and B9L, like PYGO2, are constitutive components of the Wnt enhanceosome. Wnt-dependent docking of β-catenin to the enhanceosome apparently causes a rearrangement that apposes the BCL9/B9L C-terminus to TCF. This C-terminus binds to the Groucho/TLE co-repressor, and also to the Chip/LDB1-SSDP enhanceosome core complex via an evolutionary conserved element. An unexpected link between BCL9/B9L, PYGO2 and nuclear co-receptor complexes suggests that these β-catenin co-factors may coordinate Wnt and nuclear hormone responses.
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Affiliation(s)
| | | | - Marc Fiedler
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | | | - Mariann Bienz
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
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25
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Lee B, Lee S, Agulnick AD, Lee JW, Lee SK. Single-stranded DNA binding proteins are required for LIM complexes to induce transcriptionally active chromatin and specify spinal neuronal identities. Development 2016; 143:1721-31. [PMID: 26965372 DOI: 10.1242/dev.131284] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 03/01/2016] [Indexed: 01/01/2023]
Abstract
LIM homeodomain factors regulate the development of many cell types. However, transcriptional coactivators that mediate their developmental function remain poorly defined. To address these, we examined how two related NLI-dependent LIM complexes, which govern the development of spinal motor neurons and V2a interneurons, activate the transcription in the embryonic spinal cord. We found that single-stranded DNA-binding proteins are recruited to these LIM complexes via NLI, and enhance their transcriptional activation potential. Ssdp1 and Ssdp2 (Ssdp1/2) are highly expressed in the neural tube and promote motor neuron differentiation in the embryonic spinal cord and P19 stem cells. Inhibition of Ssdp1/2 activity in mouse and chick embryos suppresses the generation of motor neurons and V2a interneurons. Furthermore, Ssdp1/2 recruit histone-modifying enzymes to the motor neuron-specifying LIM complex and trigger acetylation and lysine 4 trimethylation of histone H3, which are well-established chromatin marks for active transcription. Our results suggest that Ssdp1/2 function as crucial transcriptional coactivators for LIM complexes to specify spinal neuronal identities during development.
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Affiliation(s)
- Bora Lee
- Neuroscience Section, Papé Family Pediatric Research Institute, Department of Pediatrics, Oregon Health & Science University, Portland, OR 97239, USA Department of Cell, Developmental Biology and Cancer Biology, Oregon Health and Science University, Portland, OR 97239, USA
| | - Seunghee Lee
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, Korea
| | | | - Jae W Lee
- Neuroscience Section, Papé Family Pediatric Research Institute, Department of Pediatrics, Oregon Health & Science University, Portland, OR 97239, USA Department of Cell, Developmental Biology and Cancer Biology, Oregon Health and Science University, Portland, OR 97239, USA
| | - Soo-Kyung Lee
- Neuroscience Section, Papé Family Pediatric Research Institute, Department of Pediatrics, Oregon Health & Science University, Portland, OR 97239, USA Department of Cell, Developmental Biology and Cancer Biology, Oregon Health and Science University, Portland, OR 97239, USA Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA
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26
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Krivega I, Dean A. Chromatin looping as a target for altering erythroid gene expression. Ann N Y Acad Sci 2016; 1368:31-9. [PMID: 26918894 DOI: 10.1111/nyas.13012] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 01/04/2016] [Accepted: 01/11/2016] [Indexed: 01/07/2023]
Abstract
The β-hemoglobinopathies are the most common monogenic disorders in humans, with symptoms arising after birth when the fetal γ-globin genes are silenced and the adult β-globin gene is activated. There is a growing appreciation that genome organization and the folding of chromosomes are key determinants of gene transcription. Underlying this function is the activity of transcriptional enhancers that increase the transcription of target genes over long linear distances. To accomplish this, enhancers engage in close physical contact with target promoters through chromosome folding or looping that is orchestrated by protein complexes that bind to both sites and stabilize their interaction. We find that enhancer activity can be redirected with concomitant changes in gene transcription. Both targeting the β-globin locus control region (LCR) to the γ-globin gene in adult erythroid cells by tethering and epigenetic unmasking of a silenced γ-globin gene lead to increased frequency of LCR/γ-globin contacts and reduced LCR/β-globin contacts. The outcome of these manipulations is robust, pancellular γ-globin transcription activation with a concomitant reduction in β-globin transcription. These examples show that chromosome looping may be considered a therapeutic target for gene activation in β-thalassemia and sickle cell disease.
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Affiliation(s)
- Ivan Krivega
- Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Ann Dean
- Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
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27
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Fiedler M, Graeb M, Mieszczanek J, Rutherford TJ, Johnson CM, Bienz M. An ancient Pygo-dependent Wnt enhanceosome integrated by Chip/LDB-SSDP. eLife 2015; 4:e09073. [PMID: 26312500 PMCID: PMC4571689 DOI: 10.7554/elife.09073] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 08/26/2015] [Indexed: 12/15/2022] Open
Abstract
TCF/LEF factors are ancient context-dependent enhancer-binding proteins that are activated by β-catenin following Wnt signaling. They control embryonic development and adult stem cell compartments, and their dysregulation often causes cancer. β-catenin-dependent transcription relies on the NPF motif of Pygo proteins. Here, we use a proteomics approach to discover the Chip/LDB-SSDP (ChiLS) complex as the ligand specifically binding to NPF. ChiLS also recognizes NPF motifs in other nuclear factors including Runt/RUNX2 and Drosophila ARID1, and binds to Groucho/TLE. Studies of Wnt-responsive dTCF enhancers in the Drosophila embryonic midgut indicate how these factors interact to form the Wnt enhanceosome, primed for Wnt responses by Pygo. Together with previous evidence, our study indicates that ChiLS confers context-dependence on TCF/LEF by integrating multiple inputs from lineage and signal-responsive factors, including enhanceosome switch-off by Notch. Its pivotal function in embryos and stem cells explain why its integrity is crucial in the avoidance of cancer.
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Affiliation(s)
- Marc Fiedler
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Michael Graeb
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Juliusz Mieszczanek
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Trevor J Rutherford
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Christopher M Johnson
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Mariann Bienz
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, United Kingdom
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28
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Caputo L, Witzel HR, Kolovos P, Cheedipudi S, Looso M, Mylona A, van IJcken WFJ, Laugwitz KL, Evans SM, Braun T, Soler E, Grosveld F, Dobreva G. The Isl1/Ldb1 Complex Orchestrates Genome-wide Chromatin Organization to Instruct Differentiation of Multipotent Cardiac Progenitors. Cell Stem Cell 2015; 17:287-99. [PMID: 26321200 DOI: 10.1016/j.stem.2015.08.007] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 07/08/2015] [Accepted: 08/06/2015] [Indexed: 01/21/2023]
Abstract
Cardiac stem/progenitor cells hold great potential for regenerative therapies; however, the mechanisms regulating their expansion and differentiation remain insufficiently defined. Here we show that Ldb1 is a central regulator of genome organization in cardiac progenitor cells, which is crucial for cardiac lineage differentiation and heart development. We demonstrate that Ldb1 binds to the key regulator of cardiac progenitors, Isl1, and protects it from degradation. Furthermore, the Isl1/Ldb1 complex promotes long-range enhancer-promoter interactions at the loci of the core cardiac transcription factors Mef2c and Hand2. Chromosome conformation capture followed by sequencing identified specific Ldb1-mediated interactions of the Isl1/Ldb1 responsive Mef2c anterior heart field enhancer with genes that play key roles in cardiac progenitor cell function and cardiovascular development. Importantly, the expression of these genes was downregulated upon Ldb1 depletion and Isl1/Ldb1 haplodeficiency. In conclusion, the Isl1/Ldb1 complex orchestrates a network for heart-specific transcriptional regulation and coordination in three-dimensional space during cardiogenesis.
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Affiliation(s)
- Luca Caputo
- Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Hagen R Witzel
- Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Petros Kolovos
- Department of Cell Biology, Erasmus Medical Center, 3015 CN Rotterdam, The Netherlands
| | - Sirisha Cheedipudi
- Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Mario Looso
- Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Athina Mylona
- Department of Cell Biology, Erasmus Medical Center, 3015 CN Rotterdam, The Netherlands; School of Human and Life Sciences, Canterbury Christ Church University, Canterbury, Kent CT1 1QU, UK
| | | | - Karl-Ludwig Laugwitz
- I. Medical Department, Cardiology, Klinikum rechts der Isar, Technical University, 81675 Munich, Germany
| | - Sylvia M Evans
- Department of Medicine, Skaggs School of Pharmacy, University of California, San Diego, La Jolla, CA 92093, USA
| | - Thomas Braun
- Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Eric Soler
- Department of Cell Biology, Erasmus Medical Center, 3015 CN Rotterdam, The Netherlands; Laboratory of Molecular Hematopoiesis, CEA/DSV/iRCM/LHM, INSERM UMR967, 92265 Fontenay-aux-Roses, France; Laboratory of Excellence GR-Ex, 75015, Paris, France
| | - Frank Grosveld
- Department of Cell Biology, Erasmus Medical Center, 3015 CN Rotterdam, The Netherlands
| | - Gergana Dobreva
- Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany; Medical Faculty, University of Frankfurt, 60590 Frankfurt am Main, Germany.
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Critical Roles of the LIM Domains of Lhx3 in Recruiting Coactivators to the Motor Neuron-Specifying Isl1-Lhx3 Complex. Mol Cell Biol 2015; 35:3579-89. [PMID: 26260513 DOI: 10.1128/mcb.00335-15] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 08/03/2015] [Indexed: 11/20/2022] Open
Abstract
During spinal cord development, the LIM domains of the LIM homeodomain factor Lhx3 bind to either the LIM cofactor nuclear LIM interactor (NLI) or another LIM homeodomain factor, Isl1, assembling the tetrameric V2 interneuron-specifying Lhx3 complex (2NLI:2Lhx3) or the hexameric motor neuron-specifying Isl1-Lhx3 complex (2NLI:2Isl1:2Lhx3). However, the detailed molecular basis by which the Lhx3-LIM domains contribute to motor neuron specification still remains poorly understood. Here, we show that the Lhx3-LIM domains are essential for recruiting transcriptional coactivators to the Isl1-Lhx3 complex. Using a yeast genetic screening system, we identify Lhx3 point mutants that bind to NLI but not Isl1. Accordingly, these mutants fail to assemble the Isl1-Lhx3 complex. However, their interaction with coactivators is relatively intact, and they are fully functional in the Lhx3 complex and V2 interneuron specification. Interestingly, when these Lhx3 mutants are directly fused to Isl1, their transcriptional activity in the Isl1-Lhx3 complex is restored. We further show that this restoration reflects an unexpected role of the Lhx3-LIM domains, likely together with Isl1, to form an interaction interface for coactivators. Our results suggest that the Lhx3-LIM domains play critical roles in transactivation of the Isl1-Lhx3 complex by not only directing the assembly of the Isl1-Lhx3 complex but also recruiting coactivators to the complex.
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30
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Chip physically interacts with Notch and their stoichiometry is critical for Notch function in wing development and cell proliferation in Drosophila. Biochim Biophys Acta Gen Subj 2015; 1850:802-12. [DOI: 10.1016/j.bbagen.2014.12.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 12/15/2014] [Accepted: 12/27/2014] [Indexed: 12/17/2022]
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Abstract
Studies by cancer genome consortiums have identified frequent mutations in chromatin regulatory factors and histone proteins in human cancer, implicating them as major mediators in the pathogenesis of both hematological malignancies and solid tumors. Here, Morgan and Shilatifard review recent advances in our understanding of the role of chromatin in cancer, focusing on transcriptional regulatory complexes, enhancer-associated factors, histone point mutations, and alterations in heterochromatin-interacting factors. Changes in the pattern of gene expression play an important role in allowing cancer cells to acquire their hallmark characteristics, while genomic instability enables cells to acquire genetic alterations that promote oncogenesis. Chromatin plays central roles in both transcriptional regulation and the maintenance of genomic stability. Studies by cancer genome consortiums have identified frequent mutations in genes encoding chromatin regulatory factors and histone proteins in human cancer, implicating them as major mediators in the pathogenesis of both hematological malignancies and solid tumors. Here, we review recent advances in our understanding of the role of chromatin in cancer, focusing on transcriptional regulatory complexes, enhancer-associated factors, histone point mutations, and alterations in heterochromatin-interacting factors.
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Affiliation(s)
- Marc A Morgan
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
| | - Ali Shilatifard
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
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32
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Enhancer-bound LDB1 regulates a corticotrope promoter-pausing repression program. Proc Natl Acad Sci U S A 2015; 112:1380-5. [PMID: 25605944 DOI: 10.1073/pnas.1424228112] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Substantial evidence supports the hypothesis that enhancers are critical regulators of cell-type determination, orchestrating both positive and negative transcriptional programs; however, the basic mechanisms by which enhancers orchestrate interactions with cognate promoters during activation and repression events remain incompletely understood. Here we report the required actions of LIM domain-binding protein 1 (LDB1)/cofactor of LIM homeodomain protein 2/nuclear LIM interactor, interacting with the enhancer-binding protein achaete-scute complex homolog 1, to mediate looping to target gene promoters and target gene regulation in corticotrope cells. LDB1-mediated enhancer:promoter looping appears to be required for both activation and repression of these target genes. Although LDB1-dependent activated genes are regulated at the level of transcriptional initiation, the LDB1-dependent repressed transcription units appear to be regulated primarily at the level of promoter pausing, with LDB1 regulating recruitment of metastasis-associated 1 family, member 2, a component of the nucleosome remodeling deacetylase complex, on these negative enhancers, required for the repressive enhancer function. These results indicate that LDB1-dependent looping events can deliver repressive cargo to cognate promoters to mediate promoter pausing events in a pituitary cell type.
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33
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Enhancer biology and enhanceropathies. Nat Struct Mol Biol 2014; 21:210-9. [DOI: 10.1038/nsmb.2784] [Citation(s) in RCA: 220] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 02/06/2014] [Indexed: 12/18/2022]
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34
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Maksimenko O, Georgiev P. Mechanisms and proteins involved in long-distance interactions. Front Genet 2014; 5:28. [PMID: 24600469 PMCID: PMC3927085 DOI: 10.3389/fgene.2014.00028] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 01/25/2014] [Indexed: 12/28/2022] Open
Abstract
Due to advances in genome-wide technologies, consistent distant interactions within chromosomes of higher eukaryotes have been revealed. In particular, it has been shown that enhancers can specifically and directly interact with promoters by looping out intervening sequences, which can be up to several hundred kilobases long. This review is focused on transcription factors that are supposed to be involved in long-range interactions. Available data are in agreement with the model that several known transcription factors and insulator proteins belong to an abundant but poorly studied class of proteins that are responsible for chromosomal architecture.
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Affiliation(s)
- Oksana Maksimenko
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences Moscow, Russia
| | - Pavel Georgiev
- Department of the Control of Genetic Processes, Institute of Gene Biology, Russian Academy of Sciences Moscow, Russia
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35
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Ohno K, Sawada JI, Takiya S, Kimoto M, Matsumoto A, Tsubota T, Uchino K, Hui CC, Sezutsu H, Handa H, Suzuki Y. Silk gland factor-2, involved in fibroin gene transcription, consists of LIM homeodomain, LIM-interacting, and single-stranded DNA-binding proteins. J Biol Chem 2013; 288:31581-91. [PMID: 24022586 DOI: 10.1074/jbc.m113.514471] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
SGF-2 binds to promoter elements governing posterior silk gland-specific expression of the fibroin gene in Bombyx mori. We purified SGF-2 and showed that SGF-2 contains at least four gene products: the silkworm orthologues of LIM homeodomain protein Awh, LIM domain-binding protein (Ldb), a sequence-specific single-stranded DNA-binding protein (Lcaf), and the silk protein P25/fibrohexamerin (fhx). Using co-expression of these factors in Sf9 cells, Awh, Ldb, and Lcaf proteins were co-purified as a ternary complex that bound to the enhancer sequence in vitro. Lcaf interacts with Ldb as well as Awh through the conserved regions to mediate transcriptional activation in yeast. Misexpression of Awh in transgenic silkworms induces ectopic expression of the fibroin gene in the middle silk glands, where Ldb and Lcaf are expressed. Taken together, this study demonstrates that SGF-2 is a multisubunit activator complex containing Awh. Moreover, our results suggest that the Ldb·Lcaf protein complex serves as a scaffold to facilitate communication between transcriptional control elements.
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Affiliation(s)
- Kaoru Ohno
- From the National Institute for Basic Biology, 38 Nishigonaka, Myodaiji-cho, Okazaki 444-8585
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Abstract
LIM-domain proteins are a large family of proteins that are emerging as key molecules in a wide variety of human cancers. In particular, all members of the human LIM-domain-only (LMO) proteins, LMO1-4, which are required for many developmental processes, are implicated in the onset or the progression of several cancers, including T cell leukaemia, breast cancer and neuroblastoma. These small proteins contain two protein-interacting LIM domains but little additional sequence, and they seem to function by nucleating the formation of new transcriptional complexes and/or by disrupting existing transcriptional complexes to modulate gene expression programmes. Through these activities, the LMO proteins have important cellular roles in processes that are relevant to cancer such as self-renewal, cell cycle regulation and metastasis. These functions highlight the therapeutic potential of targeting these proteins in cancer.
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Affiliation(s)
- Jacqueline M Matthews
- School of Molecular Bioscience, The University of Sydney, New South Wales 2006, Australia. jacqui.matthews@ sydney.edu.au
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37
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Deng W, Lee J, Wang H, Miller J, Reik A, Gregory PD, Dean A, Blobel GA. Controlling long-range genomic interactions at a native locus by targeted tethering of a looping factor. Cell 2012; 149:1233-44. [PMID: 22682246 DOI: 10.1016/j.cell.2012.03.051] [Citation(s) in RCA: 491] [Impact Index Per Article: 40.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 03/05/2012] [Accepted: 03/30/2012] [Indexed: 11/19/2022]
Abstract
Chromatin loops juxtapose distal enhancers with active promoters, but their molecular architecture and relationship with transcription remain unclear. In erythroid cells, the locus control region (LCR) and β-globin promoter form a chromatin loop that requires transcription factor GATA1 and the associated molecule Ldb1. We employed artificial zinc fingers (ZF) to tether Ldb1 to the β-globin promoter in GATA1 null erythroblasts, in which the β-globin locus is relaxed and inactive. Remarkably, targeting Ldb1 or only its self-association domain to the β-globin promoter substantially activated β-globin transcription in the absence of GATA1. Promoter-tethered Ldb1 interacted with endogenous Ldb1 complexes at the LCR to form a chromatin loop, causing recruitment and phosphorylation of RNA polymerase II. ZF-Ldb1 proteins were inactive at alleles lacking the LCR, demonstrating that their activities depend on long-range interactions. Our findings establish Ldb1 as a critical effector of GATA1-mediated loop formation and indicate that chromatin looping causally underlies gene regulation.
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Affiliation(s)
- Wulan Deng
- Division of Hematology, The Children's Hospital of Philadelphia, PA 19104, USA
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38
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Transcriptional activators and activation mechanisms. Protein Cell 2011; 2:879-88. [PMID: 22180087 DOI: 10.1007/s13238-011-1101-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Accepted: 08/22/2011] [Indexed: 10/14/2022] Open
Abstract
Transcriptional activators are required to turn on the expression of genes in a eukaryotic cell. Activators bound to the enhancer can facilitate either the recruitment of RNA polymerase II to the promoter or its elongation. This article examines a few selected issues in understanding activator functions and activation mechanisms.
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39
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Structural basis of simultaneous recruitment of the transcriptional regulators LMO2 and FOG1/ZFPM1 by the transcription factor GATA1. Proc Natl Acad Sci U S A 2011; 108:14443-8. [PMID: 21844373 DOI: 10.1073/pnas.1105898108] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The control of red blood cell and megakaryocyte development by the regulatory protein GATA1 is a paradigm for transcriptional regulation of gene expression in cell lineage differentiation and maturation. Most GATA1-regulated events require GATA1 to bind FOG1, and essentially all GATA1-activated genes are cooccupied by a TAL1/E2A/LMO2/LDB1 complex; however, it is not known whether FOG1 and TAL1/E2A/LMO2/LDB1 are simultaneously recruited by GATA1. Our structural data reveal that the FOG1-binding domain of GATA1, the N finger, can also directly contact LMO2 and show that, despite the small size (< 50 residues) of the GATA1 N finger, both FOG1 and LMO2 can simultaneously bind this domain. LMO2 in turn can simultaneously contact both GATA1 and the DNA-binding protein TAL1/E2A at bipartite E-box/WGATAR sites. Taken together, our data provide the first structural snapshot of multiprotein complex formation at GATA1-dependent genes and support a model in which FOG1 and TAL1/E2A/LMO2/LDB1 can cooccupy E-box/WGATAR sites to facilitate GATA1-mediated activation of gene activation.
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40
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Bronstein R, Segal D. Modularity of CHIP/LDB transcription complexes regulates cell differentiation. Fly (Austin) 2011; 5:200-5. [PMID: 21406967 DOI: 10.4161/fly.5.3.14854] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Transcription is the first step through which the cell operates, via its repertoire of transcription complexes, to direct cellular functions and cellular identity by generating the cell-specific transcriptome. The modularity of the composition of constituents of these complexes allows the cell to delicately regulate its transcriptome. In a recent study we have examined the effects of reducing the levels of specific transcription co-factors on the function of two competing transcription complexes, namely CHIP-AP and CHIP-PNR which regulate development of cells in the thorax of Drosophila. We found that changing the availability of these co-factors can shift the balance between these complexes leading to transition from utilization of CHIP-AP to CHIP-PNR. This is reflected in change in the expression profile of target genes, altering developmental cell fates. We propose that such a mechanism may operate in normal fly development. Transcription complexes analogous to CHIP-AP and CHIP-PNR exist in mammals and we discuss how such a shift in the balance between them may operate in normal mammalian development.
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Affiliation(s)
- Revital Bronstein
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
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41
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Dean A. In the loop: long range chromatin interactions and gene regulation. Brief Funct Genomics 2011; 10:3-10. [PMID: 21258045 DOI: 10.1093/bfgp/elq033] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Enhancers, silencer and insulators are DNA elements that play central roles in regulation of the genome that are crucial for development and differentiation. In metazoans, these elements are often separated from target genes by distances that can reach 100 Kb. How regulation can be accomplished over long distances has long been intriguing. Current data indicate that although the mechanisms by which these diverse regulatory elements affect gene transcription may vary, an underlying feature is the establishment of close contacts or chromatin loops. With the generalization of this principle, new questions emerge, such as how the close contacts are formed and stabilized and, importantly, how they contribute to the regulation of transcriptional output at target genes. This review will concentrate on examples where a functional role and a mechanistic understanding has been explored for loops formed between genes and their regulatory elements or among the elements themselves.
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Affiliation(s)
- Ann Dean
- Laboratory of Cellular and Developmental Biology, NIDDK, NIH, Building 50, Room 3154, 50 South Drive, MSC 8028, Bethesda, MD 20892, USA.
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42
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Zheng Q, Schaefer AM, Nonet ML. Regulation of C. elegans presynaptic differentiation and neurite branching via a novel signaling pathway initiated by SAM-10. Development 2010; 138:87-96. [PMID: 21115607 DOI: 10.1242/dev.055350] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Little is known about transcriptional control of neurite branching or presynaptic differentiation, events that occur relatively late in neuronal development. Using the Caenorhabditis elegans mechanosensory circuit as an in vivo model, we show that SAM-10, an ortholog of mammalian single-stranded DNA-binding protein (SSDP), functions cell-autonomously in the nucleus to regulate synaptic differentiation, as well as positioning of, a single neurite branch. PLM mechanosensory neurons in sam-10 mutants exhibit abnormal placement of the neurite branch point, and defective synaptogenesis, characterized by an overextended synaptic varicosity, underdeveloped synaptic morphology and disrupted colocalization of active zone and synaptic vesicles. SAM-10 functions coordinately with Lim domain-binding protein 1 (LDB-1), demonstrated by our observations that: (1) mutations in either gene show similar defects in PLM neurons; and (2) LDB-1 is required for SAM-10 nuclear localization. SAM-10 regulates PLM synaptic differentiation by suppressing transcription of prk-2, which encodes an ortholog of the mammalian Pim kinase family. PRK-2-mediated activities of SAM-10 are specifically involved in PLM synaptic differentiation, but not other sam-10 phenotypes such as neurite branching. Thus, these data reveal a novel transcriptional signaling pathway that regulates neuronal specification of neurite branching and presynaptic differentiation.
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Affiliation(s)
- Qun Zheng
- Department of Anatomy and Neurobiology, Washington University School of Medicine, 660 South Euclid Avenue, St Louis, MO 63110, USA
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43
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Building multifunctionality into a complex containing master regulators of hematopoiesis. Proc Natl Acad Sci U S A 2010; 107:20429-34. [PMID: 21059912 DOI: 10.1073/pnas.1007804107] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Developmental control mechanisms often use multimeric complexes containing transcription factors, coregulators, and additional non-DNA binding components. It is challenging to ascertain how such components contribute to complex function at endogenous loci. We analyzed the function of components of a complex containing master regulators of hematopoiesis (GATA-1 and Scl/TAL1) and the non-DNA binding components ETO2, the LIM domain protein LMO2, and the chromatin looping factor LDB1. Surprisingly, we discovered that ETO2 and LMO2 regulate distinct target-gene ensembles in erythroid cells. ETO2 commonly repressed GATA-1 function via suppressing histone H3 acetylation, although it also regulated methylation of histone H3 at lysine 27 at select loci. Prior studies defined multiple modes by which GATA-1 regulates target genes with or without the coregulator Friend of GATA-1 (FOG-1). LMO2 selectively repressed genes that GATA-1 represses in a FOG-1-independent manner. As LMO2 controls hematopoiesis, its dysregulation is leukemogenic, and its influence on GATA factor function is unknown, this mechanistic link has important biological and pathophysiological implications. The demonstration that ETO2 and LMO2 exert qualitatively distinct functions at endogenous loci illustrates how components of complexes containing master developmental regulators can impart the capacity to regulate unique cohorts of target genes, thereby diversifying complex function.
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44
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Bronstein R, Levkovitz L, Yosef N, Yanku M, Ruppin E, Sharan R, Westphal H, Oliver B, Segal D. Transcriptional regulation by CHIP/LDB complexes. PLoS Genet 2010; 6:e1001063. [PMID: 20730086 PMCID: PMC2921152 DOI: 10.1371/journal.pgen.1001063] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2009] [Accepted: 07/12/2010] [Indexed: 01/18/2023] Open
Abstract
It is increasingly clear that transcription factors play versatile roles in turning genes "on" or "off" depending on cellular context via the various transcription complexes they form. This poses a major challenge in unraveling combinatorial transcription complex codes. Here we use the powerful genetics of Drosophila combined with microarray and bioinformatics analyses to tackle this challenge. The nuclear adaptor CHIP/LDB is a major developmental regulator capable of forming tissue-specific transcription complexes with various types of transcription factors and cofactors, making it a valuable model to study the intricacies of gene regulation. To date only few CHIP/LDB complexes target genes have been identified, and possible tissue-dependent crosstalk between these complexes has not been rigorously explored. SSDP proteins protect CHIP/LDB complexes from proteasome dependent degradation and are rate-limiting cofactors for these complexes. By using mutations in SSDP, we identified 189 down-stream targets of CHIP/LDB and show that these genes are enriched for the binding sites of APTEROUS (AP) and PANNIER (PNR), two well studied transcription factors associated with CHIP/LDB complexes. We performed extensive genetic screens and identified target genes that genetically interact with components of CHIP/LDB complexes in directing the development of the wings (28 genes) and thoracic bristles (23 genes). Moreover, by in vivo RNAi silencing we uncovered novel roles for two of the target genes, xbp1 and Gs-alpha, in early development of these structures. Taken together, our results suggest that loss of SSDP disrupts the normal balance between the CHIP-AP and the CHIP-PNR transcription complexes, resulting in down-regulation of CHIP-AP target genes and the concomitant up-regulation of CHIP-PNR target genes. Understanding the combinatorial nature of transcription complexes as presented here is crucial to the study of transcription regulation of gene batteries required for development.
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Affiliation(s)
- Revital Bronstein
- Department of Microbiology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Liron Levkovitz
- Department of Physiology and Pharmacology, Tel Aviv University, Tel Aviv, Israel
- Balvatnik School of Computer Science, Tel Aviv University, Tel Aviv, Israel
| | - Nir Yosef
- Balvatnik School of Computer Science, Tel Aviv University, Tel Aviv, Israel
| | - Michaela Yanku
- Department of Microbiology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Eytan Ruppin
- Department of Physiology and Pharmacology, Tel Aviv University, Tel Aviv, Israel
- Balvatnik School of Computer Science, Tel Aviv University, Tel Aviv, Israel
| | - Roded Sharan
- Balvatnik School of Computer Science, Tel Aviv University, Tel Aviv, Israel
| | - Heiner Westphal
- Section on Mammalian Molecular Genetics, Program in Genomics of Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Brian Oliver
- Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Daniel Segal
- Department of Microbiology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
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45
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Regulation of LIM-domain-binding 1 protein expression by ubiquitination of Lys134. Biochem J 2010; 429:127-36. [PMID: 20423330 DOI: 10.1042/bj20091461] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
LDB1 (LIM-domain-binding 1) is a cofactor that participates in formation of transcriptional regulatory complexes involving transcription factors containing LIM domains as well as other factors. The amount of LDB1 protein in cells has previously been shown to be modulated by RNF12 (RING finger protein 12). RNF12 is an E3 ubiquitin ligase that can target LDB1 for poly-ubiquitination and degradation via the proteasome. We find that in HEK (human embryonic kidney)-293 cells expression of RNF12 leads to mono-ubiquitination of LDB1 and increased levels of LDB1 protein. Mutagenesis studies identified Lys134 of LDB1 as the residue that is mono-ubiquitinated by RNF12. Mutation of Lys134 of LDB1 to arginine blocks the formation of mono-ubiquitinated LDB1 and surprisingly also increases LDB1 protein expression in HEK-293 cells. This leads to a model in which Lys134 of LDB1 can be either mono-ubiquitinated, leading to stabilization, or poly-ubiquitinated, leading to degradation by the proteasome pathway. We also find that ubiquitin-LDB1 fusion proteins are stabilized in HEK-293 cells, offering further evidence that mono-ubiquitination stabilizes LDB1 in these cells. Expression in Xenopus laevis embryos of an LDB1 protein in which Lys134 is replaced with arginine leads to enhanced expression of the mutant protein as compared with the wild-type protein. These findings provide evidence that modification of Lys134 can play a major role in regulating LDB1 expression.
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46
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Cross AJ, Jeffries CM, Trewhella J, Matthews JM. LIM Domain Binding Proteins 1 and 2 Have Different Oligomeric States. J Mol Biol 2010; 399:133-44. [DOI: 10.1016/j.jmb.2010.04.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Revised: 04/01/2010] [Accepted: 04/01/2010] [Indexed: 01/13/2023]
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47
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Bulger M, Groudine M. Enhancers: the abundance and function of regulatory sequences beyond promoters. Dev Biol 2010; 339:250-7. [PMID: 20025863 PMCID: PMC3060611 DOI: 10.1016/j.ydbio.2009.11.035] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Revised: 11/24/2009] [Accepted: 11/30/2009] [Indexed: 12/25/2022]
Abstract
Transcriptional control in mammals and Drosophila is often mediated by regulatory sequences located far from gene promoters. Different classes of such elements - particularly enhancers, but also locus control regions and insulators - have been defined by specific functional assays, although it is not always clear how these assays relate to the function of these elements within their native loci. Recent advances in genomics suggest, however, that such elements are highly abundant within the genome and may represent the primary mechanism by which cell- and developmental-specific gene expression is accomplished. In this review, we discuss the functional parameters of enhancers as defined by specific assays, along with the frequency with which they occur in the genome. In addition, we examine the available evidence for the mechanism by which such elements communicate or interact with the promoters they regulate.
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Affiliation(s)
- Michael Bulger
- Center for Pediatric Biomedical Research, Department of Pediatrics, University of Rochester, Rochester, NY, USA.
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48
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Soler E, Andrieu-Soler C, de Boer E, Bryne JC, Thongjuea S, Stadhouders R, Palstra RJ, Stevens M, Kockx C, van Ijcken W, Hou J, Steinhoff C, Rijkers E, Lenhard B, Grosveld F. The genome-wide dynamics of the binding of Ldb1 complexes during erythroid differentiation. Genes Dev 2010; 24:277-89. [PMID: 20123907 DOI: 10.1101/gad.551810] [Citation(s) in RCA: 197] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
One of the complexes formed by the hematopoietic transcription factor Gata1 is a complex with the Ldb1 (LIM domain-binding protein 1) and Tal1 proteins. It is known to be important for the development and differentiation of the erythroid cell lineage and is thought to be implicated in long-range interactions. Here, the dynamics of the composition of the complex-in particular, the binding of the negative regulators Eto2 and Mtgr1-are studied, in the context of their genome-wide targets. This shows that the complex acts almost exclusively as an activator, binding a very specific combination of sequences, with a positioning relative to transcription start site, depending on the type of the core promoter. The activation is accompanied by a net decrease in the relative binding of Eto2 and Mtgr1. A Chromosome Conformation Capture sequencing (3C-seq) assay also shows that the binding of the Ldb1 complex marks genomic interaction sites in vivo. This establishes the Ldb1 complex as a positive regulator of the final steps of erythroid differentiation that acts through the shedding of negative regulators and the active interaction between regulatory sequences.
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Affiliation(s)
- Eric Soler
- Department of Cell Biology, Erasmus Medical Center, 3015GE Rotterdam, The Netherlands.
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Bao F, Azhakanandam S, Franks RG. SEUSS and SEUSS-LIKE transcriptional adaptors regulate floral and embryonic development in Arabidopsis. PLANT PHYSIOLOGY 2010; 152:821-36. [PMID: 20007451 PMCID: PMC2815852 DOI: 10.1104/pp.109.146183] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2009] [Accepted: 12/04/2009] [Indexed: 05/19/2023]
Abstract
Multimeric protein complexes are required during development to regulate transcription and orchestrate cellular proliferation and differentiation. The Arabidopsis (Arabidopsis thaliana) SEUSS (SEU) gene encodes a transcriptional adaptor that shares sequence similarity with metazoan Lim domain-binding transcriptional adaptors. In Arabidopsis, SEU forms a physical complex with the LEUNIG transcriptional coregulator. This complex regulates a number of diverse developmental events, including proper specification of floral organ identity and number and the development of female reproductive tissues derived from the carpel margin meristem. In addition to SEU, there are three Arabidopsis SEUSS-LIKE (SLK) genes that encode putative transcriptional adaptors. To determine the functions of the SLK genes and to investigate the degree of functional redundancy between SEU and SLK genes, we characterized available slk mutant lines in Arabidopsis. Here, we show that mutations in any single SLK gene failed to condition an obvious morphological abnormality. However, by generating higher order mutant plants, we uncovered a degree of redundancy between the SLK genes and between SLK genes and SEU. We report a novel role for SEU and the SLK genes during embryonic development and show that the concomitant loss of both SEU and SLK2 activities conditions severe embryonic and seedling defects characterized by a loss of the shoot apical meristem. Furthermore, we demonstrate that SLK gene function is required for proper development of vital female reproductive tissues derived from the carpel margin. We propose a model that posits that SEU and SLK genes support organ development from meristematic regions through two different pathways: one that facilitates auxin response and thus organ initiation and a second that sustains meristematic potential through the maintenance of SHOOTMERISTEM-LESS and PHABULOSA expression.
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Roignant JY, Legent K, Janody F, Treisman JE. The transcriptional co-factor Chip acts with LIM-homeodomain proteins to set the boundary of the eye field in Drosophila. Development 2010; 137:273-81. [PMID: 20040493 DOI: 10.1242/dev.041244] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Development involves the establishment of boundaries between fields specified to differentiate into distinct tissues. The Drosophila larval eye-antennal imaginal disc must be subdivided into regions that differentiate into the adult eye, antenna and head cuticle. We have found that the transcriptional co-factor Chip is required for cells at the ventral eye-antennal disc border to take on a head cuticle fate; clones of Chip mutant cells in this region instead form outgrowths that differentiate into ectopic eye tissue. Chip acts independently of the transcription factor Homothorax, which was previously shown to promote head cuticle development in the same region. Chip and its vertebrate CLIM homologues have been shown to form complexes with LIM-homeodomain transcription factors, and the domain of Chip that mediates these interactions is required for its ability to suppress the eye fate. We show that two LIM-homeodomain proteins, Arrowhead and Lim1, are expressed in the region of the eye-antennal disc affected in Chip mutants, and that both require Chip for their ability to suppress photoreceptor differentiation when misexpressed in the eye field. Loss-of-function studies support the model that Arrowhead and Lim1 act redundantly, using Chip as a co-factor, to prevent retinal differentiation in regions of the eye disc destined to become ventral head tissue.
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Affiliation(s)
- Jean-Yves Roignant
- Kimmel Center for Biology and Medicine of the Skirball Institute, NYU School of Medicine, Department of Cell Biology, 540 First Avenue, New York, NY 10016, USA
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