1
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Wong LH, Tremethick DJ. Multifunctional histone variants in genome function. Nat Rev Genet 2024:10.1038/s41576-024-00759-1. [PMID: 39138293 DOI: 10.1038/s41576-024-00759-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/18/2024] [Indexed: 08/15/2024]
Abstract
Histones are integral components of eukaryotic chromatin that have a pivotal role in the organization and function of the genome. The dynamic regulation of chromatin involves the incorporation of histone variants, which can dramatically alter its structural and functional properties. Contrary to an earlier view that limited individual histone variants to specific genomic functions, new insights have revealed that histone variants exert multifaceted roles involving all aspects of genome function, from governing patterns of gene expression at precise genomic loci to participating in genome replication, repair and maintenance. This conceptual change has led to a new understanding of the intricate interplay between chromatin and DNA-dependent processes and how this connection translates into normal and abnormal cellular functions.
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Affiliation(s)
- Lee H Wong
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - David J Tremethick
- The John Curtin School of Medical Research, The Australian National University, Canberra, Australian Capial Territory, Australia.
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2
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Salinas-Luypaert C, Fachinetti D. Canonical and noncanonical regulators of centromere assembly and maintenance. Curr Opin Cell Biol 2024; 89:102396. [PMID: 38981198 DOI: 10.1016/j.ceb.2024.102396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Revised: 06/10/2024] [Accepted: 06/15/2024] [Indexed: 07/11/2024]
Abstract
Centromeres are specialized chromosomal domains where the kinetochores assemble during cell division to ensure accurate transmission of the genetic information to the two daughter cells. The centromeric function is evolutionary conserved and, in most organisms, centromeres are epigenetically defined by a unique chromatin containing the histone H3 variant CENP-A. The canonical regulators of CENP-A assembly and maintenance are well-known, yet some of the molecular mechanisms regulating this complex process have only recently been unveiled. We review the most recent advances on the topic, including the emergence of new and unexpected factors that favor and regulate CENP-A assembly and/or maintenance.
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Affiliation(s)
- Catalina Salinas-Luypaert
- Institut Curie, PSL Research University, Sorbonne Université, CNRS, UMR 144 & UMR3664, 26 rue d'Ulm, 75005, Paris, France.
| | - Daniele Fachinetti
- Institut Curie, PSL Research University, Sorbonne Université, CNRS, UMR 144 & UMR3664, 26 rue d'Ulm, 75005, Paris, France.
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3
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Luna R, Gómez-González B, Aguilera A. RNA biogenesis and RNA metabolism factors as R-loop suppressors: a hidden role in genome integrity. Genes Dev 2024; 38:504-527. [PMID: 38986581 PMCID: PMC11293400 DOI: 10.1101/gad.351853.124] [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] [Indexed: 07/12/2024]
Abstract
Genome integrity relies on the accuracy of DNA metabolism, but as appreciated for more than four decades, transcription enhances mutation and recombination frequencies. More recent research provided evidence for a previously unforeseen link between RNA and DNA metabolism, which is often related to the accumulation of DNA-RNA hybrids and R-loops. In addition to physiological roles, R-loops interfere with DNA replication and repair, providing a molecular scenario for the origin of genome instability. Here, we review current knowledge on the multiple RNA factors that prevent or resolve R-loops and consequent transcription-replication conflicts and thus act as modulators of genome dynamics.
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Affiliation(s)
- Rosa Luna
- Andalusian Center of Molecular Biology and Regenerative Medicine (CABIMER), Universidad de Sevilla-Spanish National Research Council (CSIC), 41092 Seville, Spain
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
| | - Belén Gómez-González
- Andalusian Center of Molecular Biology and Regenerative Medicine (CABIMER), Universidad de Sevilla-Spanish National Research Council (CSIC), 41092 Seville, Spain
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
| | - Andrés Aguilera
- Andalusian Center of Molecular Biology and Regenerative Medicine (CABIMER), Universidad de Sevilla-Spanish National Research Council (CSIC), 41092 Seville, Spain;
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
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4
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Yoon J, Hwang Y, Yun H, Chung JM, Kim S, Kim G, Lee Y, Lee B, Kang HC. LC3B drives transcription-associated homologous recombination via direct interaction with R-loops. Nucleic Acids Res 2024; 52:5088-5106. [PMID: 38412240 PMCID: PMC11109984 DOI: 10.1093/nar/gkae156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 02/15/2024] [Accepted: 02/19/2024] [Indexed: 02/29/2024] Open
Abstract
Exploring the connection between ubiquitin-like modifiers (ULMs) and the DNA damage response (DDR), we employed several advanced DNA damage and repair assay techniques and identified a crucial role for LC3B. Notably, its RNA recognition motif (RRM) plays a pivotal role in the context of transcription-associated homologous recombination (HR) repair (TA-HRR), a particular subset of HRR pathways. Surprisingly, independent of autophagy flux, LC3B interacts directly with R-loops at DNA lesions within transcriptionally active sites via its RRM, promoting TA-HRR. Using native RNA immunoprecipitation (nRIP) coupled with high-throughput sequencing (nRIP-seq), we discovered that LC3B also directly interacts with the 3'UTR AU-rich elements (AREs) of BRCA1 via its RRM, influencing its stability. This suggests that LC3B regulates TA-HRR both proximal to and distal from DNA lesions. Data from our LC3B depletion experiments showed that LC3B knockdown disrupts end-resection for TA-HRR, redirecting it towards the non-homologous end joining (NHEJ) pathway and leading to chromosomal instability, as evidenced by alterations in sister chromatid exchange (SCE) and interchromosomal fusion (ICF). Thus, our findings unveil autophagy-independent functions of LC3B in DNA damage and repair pathways, highlighting its importance. This could reshape our understanding of TA-HRR and the interaction between autophagy and DDR.
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Affiliation(s)
- Junghyun Yoon
- Department of Physiology, Ajou University School of Medicine, Suwon, Gyeonggi 16499, Republic of Korea
- Department of Biomedical Sciences, Ajou University School of Medicine, Suwon, Gyeonggi 16499, Republic of Korea
| | - Yiseul Hwang
- Department of Physiology, Ajou University School of Medicine, Suwon, Gyeonggi 16499, Republic of Korea
- Department of Biomedical Sciences, Ajou University School of Medicine, Suwon, Gyeonggi 16499, Republic of Korea
| | - Hansol Yun
- Department of Physiology, Ajou University School of Medicine, Suwon, Gyeonggi 16499, Republic of Korea
- Department of Biomedical Sciences, Ajou University School of Medicine, Suwon, Gyeonggi 16499, Republic of Korea
| | - Jee Min Chung
- Department of Physiology, Ajou University School of Medicine, Suwon, Gyeonggi 16499, Republic of Korea
- Department of Biomedical Sciences, Ajou University School of Medicine, Suwon, Gyeonggi 16499, Republic of Korea
| | - Soyeon Kim
- Department of Physiology, Ajou University School of Medicine, Suwon, Gyeonggi 16499, Republic of Korea
- Department of Biomedical Sciences, Ajou University School of Medicine, Suwon, Gyeonggi 16499, Republic of Korea
| | - Gyeongmin Kim
- Department of Physiology, Ajou University School of Medicine, Suwon, Gyeonggi 16499, Republic of Korea
- Department of Biomedical Sciences, Ajou University School of Medicine, Suwon, Gyeonggi 16499, Republic of Korea
| | - Yeji Lee
- Department of Physiology, Ajou University School of Medicine, Suwon, Gyeonggi 16499, Republic of Korea
- Department of Biomedical Sciences, Ajou University School of Medicine, Suwon, Gyeonggi 16499, Republic of Korea
| | - Byoung Dae Lee
- Department of Neuroscience, Kyung Hee University, Seoul 02447; Department of Physiology, Kyung Hee University School of Medicine, Seoul 02447, Republic of Korea
| | - Ho Chul Kang
- Department of Physiology, Ajou University School of Medicine, Suwon, Gyeonggi 16499, Republic of Korea
- Department of Biomedical Sciences, Ajou University School of Medicine, Suwon, Gyeonggi 16499, Republic of Korea
- Genomic Instability Research Center, Ajou University School of Medicine, Suwon, Gyeonggi 16499, Republic of Korea
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5
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Choudhury R, Venkateswaran Venkatasubramani A, Hua J, Borsò M, Franconi C, Kinkley S, Forné I, Imhof A. The role of RNA in the maintenance of chromatin domains as revealed by antibody-mediated proximity labelling coupled to mass spectrometry. eLife 2024; 13:e95718. [PMID: 38717135 PMCID: PMC11147508 DOI: 10.7554/elife.95718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Accepted: 04/26/2024] [Indexed: 06/04/2024] Open
Abstract
Eukaryotic chromatin is organized into functional domains, that are characterized by distinct proteomic compositions and specific nuclear positions. In contrast to cellular organelles surrounded by lipid membranes, the composition of distinct chromatin domains is rather ill described and highly dynamic. To gain molecular insight into these domains and explore their composition, we developed an antibody-based proximity biotinylation method targeting the RNA and proteins constituents. The method that we termed antibody-mediated proximity labelling coupled to mass spectrometry (AMPL-MS) does not require the expression of fusion proteins and therefore constitutes a versatile and very sensitive method to characterize the composition of chromatin domains based on specific signature proteins or histone modifications. To demonstrate the utility of our approach we used AMPL-MS to characterize the molecular features of the chromocenter as well as the chromosome territory containing the hyperactive X chromosome in Drosophila. This analysis identified a number of known RNA-binding proteins in proximity of the hyperactive X and the centromere, supporting the accuracy of our method. In addition, it enabled us to characterize the role of RNA in the formation of these nuclear bodies. Furthermore, our method identified a new set of RNA molecules associated with the Drosophila centromere. Characterization of these novel molecules suggested the formation of R-loops in centromeres, which we validated using a novel probe for R-loops in Drosophila. Taken together, AMPL-MS improves the selectivity and specificity of proximity ligation allowing for novel discoveries of weak protein-RNA interactions in biologically diverse domains.
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Affiliation(s)
- Rupam Choudhury
- Department of Molecular Biology, Biomedical Center Munich, Ludwig-Maximilians UniversityPlanegg-MartinsriedGermany
| | - Anuroop Venkateswaran Venkatasubramani
- Department of Molecular Biology, Biomedical Center Munich, Ludwig-Maximilians UniversityPlanegg-MartinsriedGermany
- Graduate School of Quantitative Biosciences (QBM), Ludwig-Maximilians-Universität MünchenMunichGermany
| | - Jie Hua
- Department of Molecular Biology, Biomedical Center Munich, Ludwig-Maximilians UniversityPlanegg-MartinsriedGermany
| | - Marco Borsò
- Protein Analysis Unit, Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians, University (LMU) MunichPlanegg-MartinsriedGermany
| | - Celeste Franconi
- Chromatin Structure and Function group, Department of Computational Molecular Biology, Max Planck Institute for Molecular GeneticsBerlinGermany
| | - Sarah Kinkley
- Chromatin Structure and Function group, Department of Computational Molecular Biology, Max Planck Institute for Molecular GeneticsBerlinGermany
| | - Ignasi Forné
- Protein Analysis Unit, Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians, University (LMU) MunichPlanegg-MartinsriedGermany
| | - Axel Imhof
- Department of Molecular Biology, Biomedical Center Munich, Ludwig-Maximilians UniversityPlanegg-MartinsriedGermany
- Protein Analysis Unit, Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians, University (LMU) MunichPlanegg-MartinsriedGermany
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6
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Lay MA, Thompson VF, Adelakun AD, Schwartz JC. Ewing Sarcoma Related protein 1 recognizes R-loops by binding DNA forks. Biopolymers 2024; 115:e23576. [PMID: 38511874 PMCID: PMC11127786 DOI: 10.1002/bip.23576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2024] [Revised: 03/07/2024] [Accepted: 03/08/2024] [Indexed: 03/22/2024]
Abstract
EWSR1 (Ewing Sarcoma Related protein 1) is an RNA binding protein that is ubiquitously expressed across cell lines and involved in multiple parts of RNA processing, such as transcription, splicing, and mRNA transport. EWSR1 has also been implicated in cellular mechanisms to control formation of R-loops, a three-stranded nucleic acid structure consisting of a DNA:RNA hybrid and a displaced single-stranded DNA strand. Unscheduled R-loops result in genomic and transcription stress. Loss of function of EWSR1 functions commonly found in Ewing Sarcoma correlates with high abundance of R-loops. In this study, we investigated the mechanism for EWSR1 to recognize an R-loop structure specifically. Using electrophoretic mobility shift assays (EMSA), we detected the high affinity binding of EWSR1 to substrates representing components found in R-loops. EWSR1 specificity could be isolated to the DNA fork region, which transitions between double- and single-stranded DNA. Our data suggests that the Zinc-finger domain (ZnF) with flanking arginine and glycine rich (RGG) domains provide high affinity binding, while the RNA recognition motif (RRM) with its RGG domains offer improved specificity. This model offers a rational for EWSR1 specificity to encompass a wide range in contexts due to the DNA forks always found with R-loops.
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Affiliation(s)
- Michelle A Lay
- Department of Pharmacology, University of Arizona, Tucson, Arizona, USA
- University of Arizona Cancer Center, University of Arizona, Tucson, Arizona, USA
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona, USA
| | - Valery F Thompson
- Department of Pharmacology, University of Arizona, Tucson, Arizona, USA
- University of Arizona Cancer Center, University of Arizona, Tucson, Arizona, USA
| | - Ajibola D Adelakun
- Department of Pharmacology, University of Arizona, Tucson, Arizona, USA
- University of Arizona Cancer Center, University of Arizona, Tucson, Arizona, USA
- Department of Pharmaceutical Sciences, University of Arizona, Tucson, Arizona, USA
| | - Jacob C Schwartz
- Department of Pharmacology, University of Arizona, Tucson, Arizona, USA
- University of Arizona Cancer Center, University of Arizona, Tucson, Arizona, USA
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7
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Johnson CN, Sojitra KA, Sohn EJ, Moreno-Romero AK, Baudin A, Xu X, Mittal J, Libich DS. Insights into Molecular Diversity within the FUS/EWS/TAF15 Protein Family: Unraveling Phase Separation of the N-Terminal Low-Complexity Domain from RNA-Binding Protein EWS. J Am Chem Soc 2024; 146:8071-8085. [PMID: 38492239 PMCID: PMC11156192 DOI: 10.1021/jacs.3c12034] [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] [Indexed: 03/18/2024]
Abstract
The FET protein family, comprising FUS, EWS, and TAF15, plays crucial roles in mRNA maturation, transcriptional regulation, and DNA damage response. Clinically, they are linked to Ewing family tumors and neurodegenerative diseases such as amyotrophic lateral sclerosis. The fusion protein EWS::FLI1, the causative mutation of Ewing sarcoma, arises from a genomic translocation that fuses a portion of the low-complexity domain (LCD) of EWS (EWSLCD) with the DNA binding domain of the ETS transcription factor FLI1. This fusion protein modifies transcriptional programs and disrupts native EWS functions, such as splicing. The exact role of the intrinsically disordered EWSLCD remains a topic of active investigation, but its ability to phase separate and form biomolecular condensates is believed to be central to EWS::FLI1's oncogenic properties. Here, we used paramagnetic relaxation enhancement NMR, microscopy, and all-atom molecular dynamics (MD) simulations to better understand the self-association and phase separation tendencies of the EWSLCD. Our NMR data and mutational analysis suggest that a higher density and proximity of tyrosine residues amplify the likelihood of condensate formation. MD simulations revealed that the tyrosine-rich termini exhibit compact conformations with unique contact networks and provided critical input on the relationship between contacts formed within a single molecule (intramolecular) and inside the condensed phase (intermolecular). These findings enhance our understanding of FET proteins' condensate-forming capabilities and underline differences between EWS, FUS, and TAF15.
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Affiliation(s)
- Courtney N. Johnson
- Greehey Children’s Cancer Research Institute, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, United States
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, United States
| | - Kandarp A Sojitra
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843, United States
| | - Erich J. Sohn
- Greehey Children’s Cancer Research Institute, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, United States
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, United States
| | - Alma K. Moreno-Romero
- Greehey Children’s Cancer Research Institute, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, United States
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, United States
| | - Antoine Baudin
- Greehey Children’s Cancer Research Institute, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, United States
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, United States
| | - Xiaoping Xu
- Greehey Children’s Cancer Research Institute, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, United States
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, United States
| | - Jeetain Mittal
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843, United States
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
- Interdisciplinary Graduate Program in Genetics and Genomics, Texas A&M University, College Station, Texas 77843, United States
| | - David S. Libich
- Greehey Children’s Cancer Research Institute, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, United States
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, United States
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8
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Sundara Rajan S, Ebegboni VJ, Pichling P, Ludwig KR, Jones TL, Chari R, Tran A, Kruhlak MJ, Loncarek J, Caplen NJ. Endogenous EWSR1 Exists in Two Visual Modalities That Reflect Its Associations with Nucleic Acids and Concentration at Sites of Active Transcription. Mol Cell Biol 2024; 44:103-122. [PMID: 38506112 PMCID: PMC10986767 DOI: 10.1080/10985549.2024.2315425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Accepted: 02/02/2024] [Indexed: 03/21/2024] Open
Abstract
EWSR1 is a member of the FET family of nucleic acid binding proteins that includes FUS and TAF15. Here, we report the systematic analysis of endogenous EWSR1's cellular organization in human cells. We demonstrate that EWSR1, which contains low complexity and nucleic acid binding domains, is present in cells in faster and slower-recovering fractions, indicative of a protein undergoing both rapid exchange and longer-term interactions. The employment of complementary high-resolution imaging approaches shows EWSR1 exists in two visual modalities, a distributed state which is present throughout the nucleoplasm, and a concentrated state consistent with the formation of foci. Both EWSR1 visual modalities localize with nascent RNA. EWSR1 foci concentrate in regions of euchromatin, adjacent to protein markers of transcriptional activation, and significantly colocalize with phosphorylated RNA polymerase II. Our results contribute to bridging the gap between our understanding of the biophysical and biochemical properties of FET proteins, including EWSR1, their functions as transcriptional regulators, and the participation of these proteins in tumorigenesis and neurodegenerative disease.
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Affiliation(s)
- Soumya Sundara Rajan
- Functional Genetics Section, Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Vernon J. Ebegboni
- Functional Genetics Section, Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Patricio Pichling
- Functional Genetics Section, Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Katelyn R. Ludwig
- Functional Genetics Section, Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Tamara L. Jones
- Functional Genetics Section, Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Raj Chari
- Genome Modification Core, Laboratory Animal Sciences Program, Frederick National Lab for Cancer Research, Frederick, Maryland, USA
| | - Andy Tran
- CCR Confocal Microscopy Core Facility, Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Michael J. Kruhlak
- CCR Confocal Microscopy Core Facility, Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Jadranka Loncarek
- Centrosome Biology Section, Cancer Innovation Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Natasha J. Caplen
- Functional Genetics Section, Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
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9
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Lay MA, Thompson VF, Adelakun AD, Schwartz JC. Ewing Sarcoma Related protein 1 recognizes R-loops by binding DNA forks. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.20.576463. [PMID: 38293191 PMCID: PMC10827230 DOI: 10.1101/2024.01.20.576463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
EWSR1 (Ewing Sarcoma Related protein 1) is an RNA binding protein that is ubiquitously expressed across cell lines and involved in multiple parts of RNA processing, such as transcription, splicing, and mRNA transport. EWSR1 has also been implicated in cellular mechanisms to control formation of R-loops, a three-stranded nucleic acid structure consisting of a DNA:RNA hybrid and a displaced single-stranded DNA strand. Unscheduled R-loops result in genomic and transcription stress. Loss of function of EWSR1 functions commonly found in Ewing Sarcoma correlates with high abundance of R-loops. In this study, we investigated the mechanism for EWSR1 to recognize an R-loop structure specifically. Using electrophoretic mobility shift assays (EMSA), we detected the high affinity binding of EWSR1 to substrates representing components found in R-loops. EWSR1 specificity could be isolated to the DNA fork region, which transitions between double- and single-stranded DNA. Our data suggests that the Zinc-finger domain (ZnF) with flanking arginine and glycine rich (RGG) domains provide high affinity binding, while the RNA recognition motif (RRM) with its RGG domains offer improved specificity. This model offers a rational for EWSR1 specificity to encompass a wide range in contexts due to the DNA forks always found with R-loops.
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Affiliation(s)
- Michelle A Lay
- Department of Pharmacology, University of Arizona, Tucson, AZ 85724, USA
- University of Arizona Cancer Center, Tucson, AZ 85724, USA
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85724, USA
| | - Valery F Thompson
- Department of Pharmacology, University of Arizona, Tucson, AZ 85724, USA
- University of Arizona Cancer Center, Tucson, AZ 85724, USA
| | - Ajibola D Adelakun
- Department of Pharmacology, University of Arizona, Tucson, AZ 85724, USA
- University of Arizona Cancer Center, Tucson, AZ 85724, USA
- Department of Pharmaceutical Sciences, University of Arizona, Tucson, AZ 85724, USA
| | - Jacob C Schwartz
- Department of Pharmacology, University of Arizona, Tucson, AZ 85724, USA
- University of Arizona Cancer Center, Tucson, AZ 85724, USA
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10
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Johnson CN, Sojitra KA, Sohn EJ, Moreno-Romero AK, Baudin A, Xu X, Mittal J, Libich DS. Insights into Molecular Diversity within the FET Family: Unraveling Phase Separation of the N-Terminal Low Complexity Domain from RNA-Binding Protein EWS. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.27.564484. [PMID: 37961424 PMCID: PMC10634919 DOI: 10.1101/2023.10.27.564484] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
The FET family proteins, which includes FUS, EWS, and TAF15, are RNA chaperones instrumental in processes such as mRNA maturation, transcriptional regulation, and the DNA damage response. These proteins have clinical significance: chromosomal rearrangements in FET proteins are implicated in Ewing family tumors and related sarcomas. Furthermore, point mutations in FUS and TAF15 are associated with neurodegenerative conditions like amyotrophic lateral sclerosis and frontotemporal lobar dementia. The fusion protein EWS::FLI1, the causative mutation of Ewing sarcoma, arises from a genomic translocation that fuses the low-complexity domain (LCD) of EWS (EWSLCD) with the DNA binding domain of the ETS transcription factor FLI1. This fusion not only alters transcriptional programs but also hinders native EWS functions like splicing. However, the precise function of the intrinsically disordered EWSLCD is still a topic of active investigation. Due to its flexible nature, EWSLCD can form transient interactions with itself and other biomolecules, leading to the formation of biomolecular condensates through phase separation - a mechanism thought to be central to the oncogenicity of EWS::FLI1. In our study, we used paramagnetic relaxation enhancement NMR, analytical ultracentrifugation, light microscopy, and all-atom molecular dynamics (MD) simulations to better understand the self-association and phase separation tendencies of EWSLCD. Our aim was to elucidate the molecular events that underpin EWSLCD-mediated biomolecular condensation. Our NMR data suggest tyrosine residues primarily drive the interactions vital for EWSLCD phase separation. Moreover, a higher density and proximity of tyrosine residues amplify the likelihood of condensate formation. Atomistic MD simulations and hydrodynamic experiments revealed that the tyrosine-rich N and C-termini tend to populate compact conformations, establishing unique contact networks, that are connected by a predominantly extended, tyrosine-depleted, linker region. MD simulations provide critical input on the relationship between contacts formed within a single molecule (intramolecular) and inside the condensed phase (intermolecular), and changes in protein conformations upon condensation. These results offer deeper insights into the condensate-forming abilities of the FET proteins and highlights unique structural and functional nuances between EWS and its counterparts, FUS and TAF15.
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Affiliation(s)
- Courtney N Johnson
- Greehey Children's Cancer Research Institute, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, United States
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, United States
| | - Kandarp A Sojitra
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843, United States
| | - Erich J Sohn
- Greehey Children's Cancer Research Institute, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, United States
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, United States
| | - Alma K Moreno-Romero
- Greehey Children's Cancer Research Institute, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, United States
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, United States
| | - Antoine Baudin
- Greehey Children's Cancer Research Institute, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, United States
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, United States
| | - Xiaoping Xu
- Greehey Children's Cancer Research Institute, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, United States
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, United States
| | - Jeetain Mittal
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843, United States
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
- Interdisciplinary Graduate Program in Genetics and Genomics, Texas A&M University, College Station, Texas 77843, United States
| | - David S Libich
- Greehey Children's Cancer Research Institute, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, United States
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, United States
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Rajan SS, Ebegboni VJ, Pichling P, Ludwig KR, Jones TL, Chari R, Tran A, Kruhlak MJ, Loncarek J, Caplen NJ. EWSR1's visual modalities are defined by its association with nucleic acids and RNA polymerase II. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.16.553246. [PMID: 37645932 PMCID: PMC10462028 DOI: 10.1101/2023.08.16.553246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
We report systematic analysis of endogenous EWSR1's cellular organization. We demonstrate that EWSR1, which contains low complexity and nucleic acid binding domains, is present in cells in faster and slower-recovering fractions, indicative of a protein undergoing both rapid exchange and longer-term interactions. The employment of complementary high-resolution imaging approaches shows EWSR1 exists in in two visual modalities, a distributed state which is present throughout the nucleoplasm, and a concentrated state consistent with the formation of foci. Both EWSR1 visual modalities localize with nascent RNA. EWSR1 foci concentrate in regions of euchromatin, adjacent to protein markers of transcriptional activation, and significantly colocalize with phosphorylated RNA polymerase II. Interestingly, EWSR1 and FUS, another FET protein, exhibit distinct spatial organizations. Our results contribute to bridging the gap between our understanding of the biophysical and biochemical properties of FET proteins, including EWSR1, their functions as transcriptional regulators, and the participation of these proteins in tumorigenesis and neurodegenerative disease.
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Affiliation(s)
- Soumya Sundara Rajan
- Functional Genetics Section, Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health MD 20892, USA
| | - Vernon J. Ebegboni
- Functional Genetics Section, Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health MD 20892, USA
| | - Patricio Pichling
- Functional Genetics Section, Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health MD 20892, USA
| | - Katelyn R. Ludwig
- Functional Genetics Section, Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health MD 20892, USA
| | - Tamara L. Jones
- Functional Genetics Section, Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health MD 20892, USA
| | - Raj Chari
- Genome Modification Core, Laboratory Animal Sciences Program at the Frederick National Lab for Cancer Research, Frederick, MD 21702, USA
| | - Andy Tran
- CCR Confocal Microscopy Core Facility, Laboratory of Cancer Biology and Genetics, Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Michael J. Kruhlak
- CCR Confocal Microscopy Core Facility, Laboratory of Cancer Biology and Genetics, Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Jadranka Loncarek
- Centrosome Biology Section, Cancer Innovation Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702 USA
| | - Natasha J. Caplen
- Functional Genetics Section, Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health MD 20892, USA
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