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Hayran AB, Liabakk NB, Aas PA, Kusnierczyk A, Vågbø CB, Sarno A, Iveland TS, Chawla K, Zahn A, Di Noia JM, Slupphaug G, Kavli B. RPA guides UNG to uracil in ssDNA to facilitate antibody class switching and repair of mutagenic uracil at the replication fork. Nucleic Acids Res 2024; 52:784-800. [PMID: 38000394 PMCID: PMC10810282 DOI: 10.1093/nar/gkad1115] [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: 03/31/2023] [Revised: 10/27/2023] [Accepted: 11/06/2023] [Indexed: 11/26/2023] Open
Abstract
Activation-induced cytidine deaminase (AID) interacts with replication protein A (RPA), the major ssDNA-binding protein, to promote deamination of cytosine to uracil in transcribed immunoglobulin (Ig) genes. Uracil-DNA glycosylase (UNG) acts in concert with AID during Ig diversification. In addition, UNG preserves genome integrity by base-excision repair (BER) in the overall genome. How UNG is regulated to support both mutagenic processing and error-free repair remains unknown. UNG is expressed as two isoforms, UNG1 and UNG2, which both contain an RPA-binding helix that facilitates uracil excision from RPA-coated ssDNA. However, the impact of this interaction in antibody diversification and genome maintenance has not been investigated. Here, we generated B-cell clones with targeted mutations in the UNG RPA-binding motif, and analysed class switch recombination (CSR), mutation frequency (5' Ig Sμ), and genomic uracil in clones representing seven Ung genotypes. We show that the UNG:RPA interaction plays a crucial role in both CSR and repair of AID-induced uracil at the Ig loci. By contrast, the interaction had no significant impact on total genomic uracil levels. Thus, RPA coordinates UNG during CSR and pre-replicative repair of mutagenic uracil in ssDNA but is not essential in post-replicative and canonical BER of uracil in dsDNA.
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Affiliation(s)
- Abdul B Hayran
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Nina B Liabakk
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Per A Aas
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Anna Kusnierczyk
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
- PROMEC - Proteomics and Modomics Experimental Core Facility at NTNU and the Central Norway Regional Health Authority, NO-7491 Trondheim, Norway
| | - Cathrine B Vågbø
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
- PROMEC - Proteomics and Modomics Experimental Core Facility at NTNU and the Central Norway Regional Health Authority, NO-7491 Trondheim, Norway
| | - Antonio Sarno
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Tobias S Iveland
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
- Cancer Clinic, St. Olav's Hospital, Trondheim University Hospital, NO-7006 Trondheim, Norway
| | - Konika Chawla
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
- BioCore - Bioinformatics Core Facility at NTNU and the Central Norway Regional Health Authority, NO-7491 Trondheim, Norway
| | - Astrid Zahn
- Institut de Recherches Cliniques de Montréal, 110 Av des Pins Ouest, Montréal, QC H2W 1R7, Canada
| | - Javier M Di Noia
- Institut de Recherches Cliniques de Montréal, 110 Av des Pins Ouest, Montréal, QC H2W 1R7, Canada
- Département of Médicine, Université de Montréal H3C 3J7 Montréal, Québec, Canada
| | - Geir Slupphaug
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
- PROMEC - Proteomics and Modomics Experimental Core Facility at NTNU and the Central Norway Regional Health Authority, NO-7491 Trondheim, Norway
- Clinic of Laboratory Medicine, St. Olav's Hospital, Trondheim University Hospital, NO-7006 Trondheim, Norway
| | - Bodil Kavli
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
- Clinic of Laboratory Medicine, St. Olav's Hospital, Trondheim University Hospital, NO-7006 Trondheim, Norway
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2
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Bello A, Hirth G, Voigt S, Tepper S, Jungnickel B. Mechanism and regulation of secondary immunoglobulin diversification. Cell Cycle 2023; 22:2070-2087. [PMID: 37909747 PMCID: PMC10761156 DOI: 10.1080/15384101.2023.2275397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 10/20/2023] [Indexed: 11/03/2023] Open
Abstract
Secondary immunoglobulin diversification by somatic hypermutation and class switch recombination in B cells is instrumental for an adequate adaptive humoral immune response. These genetic events may, however, also introduce aberrations into other cellular genes and thereby cause B cell malignancies. While the basic mechanism of somatic hypermutation and class switch recombination is now well understood, their regulation and in particular the mechanism of their specific targeting to immunoglobulin genes is still rather mysterious. In this review, we summarize the current knowledge on the mechanism and regulation of secondary immunoglobulin diversification and discuss known mechanisms of physiological targeting to immunoglobulin genes and mistargeting to other cellular genes. We summarize open questions in the field and provide an outlook on future research.
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Affiliation(s)
- Amanda Bello
- Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
| | - Gianna Hirth
- Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
| | - Stefanie Voigt
- Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
| | - Sandra Tepper
- Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
| | - Berit Jungnickel
- Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
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3
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Schrader CE, Williams T, Pechhold K, Linehan EK, Tsuchimoto D, Nakabeppu Y. APE2 Promotes AID-Dependent Somatic Hypermutation in Primary B Cell Cultures That Is Suppressed by APE1. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2023; 210:1804-1814. [PMID: 37074207 PMCID: PMC10234595 DOI: 10.4049/jimmunol.2100946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 03/29/2023] [Indexed: 04/20/2023]
Abstract
Somatic hypermutation (SHM) is necessary for Ab diversification and involves error-prone DNA repair of activation-induced cytidine deaminase-induced lesions in germinal center (GC) B cells but can also cause genomic instability. GC B cells express low levels of the DNA repair protein apurinic/apyrimidinic (AP) endonuclease (APE)1 and high levels of its homolog APE2. Reduced SHM in APE2-deficient mice suggests that APE2 promotes SHM, but these GC B cells also exhibit reduced proliferation that could impact mutation frequency. In this study, we test the hypothesis that APE2 promotes and APE1 suppresses SHM. We show how APE1/APE2 expression changes in primary murine spleen B cells during activation, impacting both SHM and class-switch recombination (CSR). High levels of both APE1 and APE2 early after activation promote CSR. However, after 2 d, APE1 levels decrease steadily with each cell division, even with repeated stimulation, whereas APE2 levels increase with each stimulation. When GC-level APE1/APE2 expression was engineered by reducing APE1 genetically (apex1+/-) and overexpressing APE2, bona fide activation-induced cytidine deaminase-dependent VDJH4 intron SHM became detectable in primary B cell cultures. The C terminus of APE2 that interacts with proliferating cell nuclear Ag promotes SHM and CSR, although its ATR-Chk1-interacting Zf-GRF domain is not required. However, APE2 does not increase mutations unless APE1 is reduced. Although APE1 promotes CSR, it suppresses SHM, suggesting that downregulation of APE1 in the GC is required for SHM. Genome-wide expression data compare GC and cultured B cells and new models depict how APE1 and APE2 expression and protein interactions change during B cell activation and affect the balance between accurate and error-prone repair during CSR and SHM.
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Affiliation(s)
- Carol E. Schrader
- Department of Microbiology and Physiological Systems, Program in Immunology and Microbiology, UMassChan Medical School, Worcester, MA 01655
| | - Travis Williams
- Department of Microbiology and Physiological Systems, Program in Immunology and Microbiology, UMassChan Medical School, Worcester, MA 01655
| | - Klaus Pechhold
- Department of Microbiology and Physiological Systems, Program in Immunology and Microbiology, UMassChan Medical School, Worcester, MA 01655
| | - Erin K. Linehan
- Department of Microbiology and Physiological Systems, Program in Immunology and Microbiology, UMassChan Medical School, Worcester, MA 01655
| | - Daisuke Tsuchimoto
- Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University, Higashi-ku, Fukuoka 812-8582, Japan
| | - Yusaku Nakabeppu
- Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, Kyushu University, Higashi-ku, Fukuoka 812-8582, Japan
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4
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Shen HM, Wuerffel R, Cantillo JF, Priyadarshi S, Lei X, Liang J, Wu YL, Kenter AL. Loop extrusion promotes an alternate pathway for isotype switching. Cell Rep 2021; 37:110059. [PMID: 34818547 PMCID: PMC8979556 DOI: 10.1016/j.celrep.2021.110059] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 07/22/2021] [Accepted: 11/03/2021] [Indexed: 01/02/2023] Open
Abstract
Class-switch recombination (CSR) involves replacement of the Cμ
constant region with another downstream CH region. CSR is initiated
by activation-induced cytidine deaminase (AID)-mediated DNA breaks that are
targeted to transcriptionally active switch (S) regions. S region promoters
(Prs) direct synapsis by associating with the Eμ and 3′Eα
enhancers that jointly anchor a chromatin loop. We report that asymmetric loop
extrusion allows 3′Eα to track along the locus and form Pr-Pr-E
interactions that mediate CSR between downstream S regions, followed by
switching to donor Sμ. This alternative pathway bypasses sequential
switching and creates immunoglobulin (Ig)E+ B cells in the absence of
IgG1 expression. Based on the analysis of diagnostic CSR products in B cell
subsets, we identify a BCR-negative cell intermediate that is pivotal to
efficient CSR. Shen et al. report that 3′Eα tracks along the Igh locus via
unidirectional loop extrusion to form germline transcript promoter (Pr)-Pr-E
interactions that mediate an alternative CSR pathway. B cell intermediates of
CSR are identified, which are AID-dependent, surface BCR-negative, and in the
G1 phase of the cell cycle.
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Affiliation(s)
- Hong Ming Shen
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612-7344, USA
| | - Robert Wuerffel
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612-7344, USA
| | - Jose F Cantillo
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612-7344, USA
| | - Saurabh Priyadarshi
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612-7344, USA
| | - Xue Lei
- Department of Bioengineering, University of Illinois Colleges of Engineering and Medicine, Chicago, IL 60612-7344, USA
| | - Jie Liang
- Department of Bioengineering, University of Illinois Colleges of Engineering and Medicine, Chicago, IL 60612-7344, USA
| | - Yee Ling Wu
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL 60153, USA
| | - Amy L Kenter
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612-7344, USA.
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5
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Osma-Garcia IC, Capitan-Sobrino D, Mouysset M, Bell SE, Lebeurrier M, Turner M, Diaz-Muñoz MD. The RNA-binding protein HuR is required for maintenance of the germinal centre response. Nat Commun 2021; 12:6556. [PMID: 34772950 PMCID: PMC8590059 DOI: 10.1038/s41467-021-26908-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 10/22/2021] [Indexed: 11/09/2022] Open
Abstract
The germinal centre (GC) is required for the generation of high affinity antibodies and immunological memory. Here we show that the RNA binding protein HuR has an essential function in GC B cells to sustain the GC response. In its absence, the GC reaction and production of high-affinity antibody is severely impaired. Mechanistically, HuR affects the transcriptome qualitatively and quantitatively. The expression and splicing patterns of hundreds of genes are altered in the absence of HuR. Among these genes, HuR is required for the expression of Myc and a Myc-dependent transcriptional program that controls GC B cell proliferation and Ig somatic hypermutation. Additionally, HuR regulates the splicing and abundance of mRNAs required for entry into and transition through the S phase of the cell cycle, and it modulates a gene signature associated with DNA deamination protecting GC B cells from DNA damage and cell death.
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Affiliation(s)
- Ines C Osma-Garcia
- Toulouse Institute for Infectious and Inflammatory Diseases (Infinity), Inserm UMR1291, CNRS UMR5051, University Paul Sabatier, CHU Purpan, Toulouse, France
| | - Dunja Capitan-Sobrino
- Toulouse Institute for Infectious and Inflammatory Diseases (Infinity), Inserm UMR1291, CNRS UMR5051, University Paul Sabatier, CHU Purpan, Toulouse, France
| | - Mailys Mouysset
- Toulouse Institute for Infectious and Inflammatory Diseases (Infinity), Inserm UMR1291, CNRS UMR5051, University Paul Sabatier, CHU Purpan, Toulouse, France
| | - Sarah E Bell
- Immunology Program, The Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT, UK
| | - Manuel Lebeurrier
- Toulouse Institute for Infectious and Inflammatory Diseases (Infinity), Inserm UMR1291, CNRS UMR5051, University Paul Sabatier, CHU Purpan, Toulouse, France
| | - Martin Turner
- Immunology Program, The Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT, UK.
| | - Manuel D Diaz-Muñoz
- Toulouse Institute for Infectious and Inflammatory Diseases (Infinity), Inserm UMR1291, CNRS UMR5051, University Paul Sabatier, CHU Purpan, Toulouse, France. .,Immunology Program, The Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT, UK.
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6
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The unique biology of germinal center B cells. Immunity 2021; 54:1652-1664. [PMID: 34380063 DOI: 10.1016/j.immuni.2021.07.015] [Citation(s) in RCA: 77] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 04/08/2021] [Accepted: 07/15/2021] [Indexed: 12/16/2022]
Abstract
Germinal center (GC) B cells are the source of the high-affinity, class-switched antibodies required for protective immunity. The unique biology of GC B cells involves iterative rounds of antibody gene somatic hypermutation coupled to multiple selection and differentiation pathways. Recent advances in areas such as single cell and gene editing technologies have shed new light upon these complex and dynamic processes. We review these findings here and integrate them into the current understanding of GC B cell replication and death, the retention of high-affinity and class-switched B cells in the GC, and differentiation into plasma and memory cell effectors. We also discuss how the biology of GC responses relates to vaccine effectiveness and outline current and future challenges in the field.
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7
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Zhang Y, Davis L, Maizels N. Pathways and signatures of mutagenesis at targeted DNA nicks. PLoS Genet 2021; 17:e1009329. [PMID: 33857147 PMCID: PMC8078790 DOI: 10.1371/journal.pgen.1009329] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 04/27/2021] [Accepted: 03/16/2021] [Indexed: 12/19/2022] Open
Abstract
Nicks are the most frequent form of DNA damage and a potential source of mutagenesis in human cells. By deep sequencing, we have identified factors and pathways that promote and limit mutagenic repair at a targeted nick in human cells. Mutations were distributed asymmetrically around the nick site. BRCA2 inhibited all categories of mutational events, including indels, SNVs and HDR. DNA2 and RPA promoted resection. DNA2 inhibited 1 bp deletions but contributed to longer deletions, as did REV7. POLQ stimulated SNVs. Parallel analysis of DSBs targeted to the same site identified similar roles for DNA2 and POLQ (but not REV7) in promoting deletions and for POLQ in stimulating SNVs. Insertions were infrequent at nicks, and most were 1 bp in length, as at DSBs. The translesion polymerase REV1 stimulated +1 insertions at one nick site but not another, illustrating the potential importance of sequence context in determining the outcome of mutagenic repair. These results highlight the potential for nicks to promote mutagenesis, especially in BRCA-deficient cells, and identify mutagenic signatures of DNA2, REV1, REV3, REV7 and POLQ.
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Affiliation(s)
- Yinbo Zhang
- Department of Immunology, University of Washington Medical School, Seattle, Washington, United States of America
| | - Luther Davis
- Department of Immunology, University of Washington Medical School, Seattle, Washington, United States of America
| | - Nancy Maizels
- Department of Immunology, University of Washington Medical School, Seattle, Washington, United States of America
- Department of Biochemistry, University of Washington Medical School, Seattle, Washington, United States of America
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8
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Sutcu HH, Matta E, Ishchenko AA. Role of PARP-catalyzed ADP-ribosylation in the Crosstalk Between DNA Strand Breaks and Epigenetic Regulation. J Mol Biol 2019:S0022-2836(19)30719-3. [PMID: 31866292 DOI: 10.1016/j.jmb.2019.12.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 11/29/2019] [Accepted: 12/05/2019] [Indexed: 12/12/2022]
Abstract
Covalent linkage of ADP-ribose units to proteins catalyzed by poly(ADP-ribose) polymerases (PARPs) plays important signaling functions in a plethora of cellular processes including DNA damage response, chromatin organization, and gene transcription. Poly- and mono-ADP-ribosylation of target macromolecules are often responsible both for the initiation and for coordination of these processes in mammalian cells. Currently, the number of cellular targets for ADP-ribosylation is rapidly expanding, and the molecular mechanisms underlying the broad substrate specificity of PARPs present enormous interest. In this review, the roles of PARP-mediated modifications of protein and nucleic acids, the readers of ADP-ribosylated structures, and the origin and function of programmed DNA strand breaks in PARP activation, transcription regulation, and DNA demethylation are discussed.
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Affiliation(s)
- Haser H Sutcu
- Groupe «Réparation de l'ADN», Equipe Labellisée par la Ligue Nationale contre le Cancer, CNRS UMR 8200, Univ. Paris-Sud, Université Paris-Saclay, Villejuif, F-94805, France; Gustave Roussy, Université Paris-Saclay, Villejuif, F-94805, France
| | - Elie Matta
- Groupe «Réparation de l'ADN», Equipe Labellisée par la Ligue Nationale contre le Cancer, CNRS UMR 8200, Univ. Paris-Sud, Université Paris-Saclay, Villejuif, F-94805, France; Gustave Roussy, Université Paris-Saclay, Villejuif, F-94805, France
| | - Alexander A Ishchenko
- Groupe «Réparation de l'ADN», Equipe Labellisée par la Ligue Nationale contre le Cancer, CNRS UMR 8200, Univ. Paris-Sud, Université Paris-Saclay, Villejuif, F-94805, France; Gustave Roussy, Université Paris-Saclay, Villejuif, F-94805, France.
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9
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Stewart I, Radtke D, Phillips B, McGowan SJ, Bannard O. Germinal Center B Cells Replace Their Antigen Receptors in Dark Zones and Fail Light Zone Entry when Immunoglobulin Gene Mutations are Damaging. Immunity 2019; 49:477-489.e7. [PMID: 30231983 PMCID: PMC6162340 DOI: 10.1016/j.immuni.2018.08.025] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2017] [Revised: 04/23/2018] [Accepted: 08/28/2018] [Indexed: 12/15/2022]
Abstract
Adaptive immunity involves the development of bespoke antibodies in germinal centers (GCs) through immunoglobulin somatic hypermutation (SHM) in GC dark zones (DZs) and clonal selection in light zones (LZs). Accurate selection requires that cells fully replace surface B cell receptors (BCRs) following SHM, but whether this happens before LZ entry is not clear. We found that most GC B cells degrade pre-SHM receptors before leaving the DZ, and that B cells acquiring crippling mutations during SHM rarely reached the LZ. Instead, apoptosis was triggered preferentially in late G1, a stage wherein cells with functional BCRs re-entered cell cycle or reduced surface expression of the chemokine receptor CXCR4 to enable LZ migration. Ectopic expression of the anti-apoptotic gene Bcl2 was not sufficient for cells with damaging mutations to reach the LZ, suggesting that BCR-dependent cues may actively facilitate the transition. Thus, BCR replacement and pre-screening in DZs prevents the accumulation of clones with non-functional receptors and facilitates selection in the LZ.
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Affiliation(s)
- Isabelle Stewart
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Daniel Radtke
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Bethan Phillips
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Simon J McGowan
- Computational Biology Research Group, MRC Weatherall Institute of Molecular Medicinex, University of Oxford, Oxford, OX3 9DS, UK
| | - Oliver Bannard
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK.
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10
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Pilzecker B, Jacobs H. Mutating for Good: DNA Damage Responses During Somatic Hypermutation. Front Immunol 2019; 10:438. [PMID: 30915081 PMCID: PMC6423074 DOI: 10.3389/fimmu.2019.00438] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 02/19/2019] [Indexed: 11/13/2022] Open
Abstract
Somatic hypermutation (SHM) of immunoglobulin (Ig) genes plays a key role in antibody mediated immunity. SHM in B cells provides the molecular basis for affinity maturation of antibodies. In this way SHM is key in optimizing antibody dependent immune responses. SHM is initiated by targeting the Activation-Induced Cytidine Deaminase (AID) to rearranged V(D)J and switch regions of Ig genes. The mutation rate of this programmed mutagenesis is ~10-3 base pairs per generation, a million-fold higher than the non-AID targeted genome of B cells. AID is a processive enzyme that binds single-stranded DNA and deaminates cytosines in DNA. Cytosine deamination generates highly mutagenic deoxy-uracil (U) in the DNA of both strands of the Ig loci. Mutagenic processing of the U by the DNA damage response generates the entire spectrum of base substitutions characterizing SHM at and around the initial U lesion. Starting from the U as a primary lesion, currently five mutagenic DNA damage response pathways have been identified in generating a well-defined SHM spectrum of C/G transitions, C/G transversions, and A/T mutations around this initial lesion. These pathways include (1) replication opposite template U generates transitions at C/G, (2) UNG2-dependent translesion synthesis (TLS) generates transversions at C/G, (3) a hybrid pathway comprising non-canonical mismatch repair (ncMMR) and UNG2-dependent TLS generates transversions at C/G, (4) ncMMR generates mutations at A/T, and (5) UNG2- and PCNA Ubiquitination (PCNA-Ub)-dependent mutations at A/T. Furthermore, specific strand-biases of SHM spectra arise as a consequence of a biased AID targeting, ncMMR, and anti-mutagenic repriming. Here, we review mammalian SHM with special focus on the mutagenic DNA damage response pathways involved in processing AID induced Us, the origin of characteristic strand biases, and relevance of the cell cycle.
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Affiliation(s)
- Bas Pilzecker
- Division of Tumor Biology & Immunology, The Netherlands Cancer Institute, Amsterdam, Netherlands
| | - Heinz Jacobs
- Division of Tumor Biology & Immunology, The Netherlands Cancer Institute, Amsterdam, Netherlands
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11
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Activation-induced deaminase (AID) localizes to the nucleus in brief pulses. PLoS Genet 2019; 15:e1007968. [PMID: 30811383 PMCID: PMC6411215 DOI: 10.1371/journal.pgen.1007968] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 03/11/2019] [Accepted: 01/16/2019] [Indexed: 11/19/2022] Open
Abstract
Activation-induced deaminase (AID) converts C to U and 5-methyl-C to T. These mutagenic activities are critical to immunoglobulin (Ig) gene diversification and epigenetic reprogramming, but they must be tightly controlled to prevent compromising cell fitness. AID acts in the nucleus but localizes predominately to the cytoplasm. To address this apparent paradox, we have carried out time-lapse imaging of AID in single living B cells and fibroblasts. We demonstrate that AID enters the nucleus in brief (30 min) pulses, evident in about 10% of cells in the course of a single cell cycle (24 hr imaging). Pulses do not depend on AID catalytic activity, but they are coordinated with nuclear accumulation of P53. Pulsing may protect cells from pathologic consequences of excess exposure to AID, or enable AID to synchronize its activity with transcription of genes that are AID targets or with nuclear entry of factors that act at sites of AID-catalyzed DNA deamination to promote Ig gene diversification or epigenetic reprogramming.
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12
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Fukuda M, Sakaue-Sawano A, Shimura C, Tachibana M, Miyawaki A, Shinkai Y. G9a-dependent histone methylation can be induced in G1 phase of cell cycle. Sci Rep 2019; 9:956. [PMID: 30700744 PMCID: PMC6354049 DOI: 10.1038/s41598-018-37507-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 12/07/2018] [Indexed: 12/19/2022] Open
Abstract
Epigenetic information (epigenome) on chromatin is crucial for the determination of cellular identity and for the expression of cell type-specific biological functions. The cell type-specific epigenome is maintained beyond replication and cell division. Nucleosomes of chromatin just after DNA replication are a mixture of old histones with the parental epigenome and newly synthesized histones without such information. The diluted epigenome is mostly restored within one cell cycle using the epigenome on the parental DNA and nucleosomes as replication templates. However, many important questions about the epigenome replication process remain to be clarified. In this study, we investigated the model system comprising of dimethylated histone H3 lysine 9 (H3K9me2) and its regulation by the lysine methyltransferase G9a. Using this epigenome model system, we addressed whether H3K9me2 can be induced in specific cell cycle stages, especially G1. Using cell cycle-specific degrons, we achieved G1 or late G1-to M phases specific accumulation of exogenous G9a in G9a deficient cells. Importantly, global levels of H3K9me2 were significantly recovered by both cell types. These data indicate that H3K9me2 may be plastic and inducible, even in the long-living, terminally-differentiated, post-mitotic, G0-G1 cell population in vivo. This knowledge is valuable in designing epigenome-manipulation-based treatments for diseases.
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Affiliation(s)
- Mikiko Fukuda
- Cellular Memory Laboratory, RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Asako Sakaue-Sawano
- Laboratory for Cell Function Dynamics, RIKEN Center for Brain Science, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Chikako Shimura
- Cellular Memory Laboratory, RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Makoto Tachibana
- Institute of Advanced Medical Sciences, Tokushima University, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan.,Experimental Research Center for Infectious Diseases, Institute for Virus Research, Kyoto University, 53 Shogoin, Kawara-cho, Sakyo-ku, Kyoto, 606-8597, Japan
| | - Atsushi Miyawaki
- Laboratory for Cell Function Dynamics, RIKEN Center for Brain Science, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Yoichi Shinkai
- Cellular Memory Laboratory, RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
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13
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Mu Y, Zelazowska MA, McBride KM. Phosphorylation promotes activation-induced cytidine deaminase activity at the Myc oncogene. J Exp Med 2017; 214:3543-3552. [PMID: 29122947 PMCID: PMC5716038 DOI: 10.1084/jem.20170468] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 08/16/2017] [Accepted: 09/26/2017] [Indexed: 12/31/2022] Open
Abstract
The molecular mechanisms that regulate AID mutator activity at off-target genes are not well characterized. Mu et al. show AID phosphorylation dynamically controls activity at Myc and other sites. Pharmacological induction of AID phosphorylation leads to increased mutations, double strand breakss and translocations. Activation-induced cytidine deaminase (AID) is a mutator enzyme that targets immunoglobulin (Ig) genes to initiate antibody somatic hypermutation (SHM) and class switch recombination (CSR). Off-target AID association also occurs, which causes oncogenic mutations and chromosome rearrangements. However, AID occupancy does not directly correlate with DNA damage, suggesting that factors beyond AID association contribute to mutation targeting. CSR and SHM are regulated by phosphorylation on AID serine38 (pS38), but the role of pS38 in off-target activity has not been evaluated. We determined that lithium, a clinically used therapeutic, induced high AID pS38 levels. Using lithium and an AID-S38 phospho mutant, we compared the role of pS38 in AID activity at the Ig switch region and off-target Myc gene. We found that deficient pS38 abated AID chromatin association and CSR but not mutation at Myc. Enhanced pS38 elevated Myc translocation and mutation frequency but not CSR or Ig switch region mutation. Thus, AID activity can be differentially targeted by phosphorylation to induce oncogenic lesions.
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Affiliation(s)
- Yunxiang Mu
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, TX
| | - Monika A Zelazowska
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, TX
| | - Kevin M McBride
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, TX
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14
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Sakaue-Sawano A, Yo M, Komatsu N, Hiratsuka T, Kogure T, Hoshida T, Goshima N, Matsuda M, Miyoshi H, Miyawaki A. Genetically Encoded Tools for Optical Dissection of the Mammalian Cell Cycle. Mol Cell 2017; 68:626-640.e5. [DOI: 10.1016/j.molcel.2017.10.001] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 08/16/2017] [Accepted: 09/29/2017] [Indexed: 11/25/2022]
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15
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Bahjat M, Guikema JEJ. The Complex Interplay between DNA Injury and Repair in Enzymatically Induced Mutagenesis and DNA Damage in B Lymphocytes. Int J Mol Sci 2017; 18:ijms18091876. [PMID: 28867784 PMCID: PMC5618525 DOI: 10.3390/ijms18091876] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Revised: 08/24/2017] [Accepted: 08/29/2017] [Indexed: 11/25/2022] Open
Abstract
Lymphocytes are endowed with unique and specialized enzymatic mutagenic properties that allow them to diversify their antigen receptors, which are crucial sensors for pathogens and mediators of adaptive immunity. During lymphocyte development, the antigen receptors expressed by B and T lymphocytes are assembled in an antigen-independent fashion by ordered variable gene segment recombinations (V(D)J recombination), which is a highly ordered and regulated process that requires the recombination activating gene products 1 & 2 (RAG1, RAG2). Upon activation by antigen, B lymphocytes undergo additional diversifications of their immunoglobulin B-cell receptors. Enzymatically induced somatic hypermutation (SHM) and immunoglobulin class switch recombination (CSR) improves the affinity for antigen and shape the effector function of the humoral immune response, respectively. The activation-induced cytidine deaminase (AID) enzyme is crucial for both SHM and CSR. These processes have evolved to both utilize as well as evade different DNA repair and DNA damage response pathways. The delicate balance between enzymatic mutagenesis and DNA repair is crucial for effective immune responses and the maintenance of genomic integrity. Not surprisingly, disturbances in this balance are at the basis of lymphoid malignancies by provoking the formation of oncogenic mutations and chromosomal aberrations. In this review, we discuss recent mechanistic insight into the regulation of RAG1/2 and AID expression and activity in lymphocytes and the complex interplay between these mutagenic enzymes and DNA repair and DNA damage response pathways, focusing on the base excision repair and mismatch repair pathways. We discuss how disturbances of this interplay induce genomic instability and contribute to oncogenesis.
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Affiliation(s)
- Mahnoush Bahjat
- Department of Pathology, Academic Medical Center, University of Amsterdam; Lymphoma and Myeloma Center Amsterdam (LYMMCARE), Amsterdam 1105 AZ, The Netherlands.
| | - Jeroen E J Guikema
- Department of Pathology, Academic Medical Center, University of Amsterdam; Lymphoma and Myeloma Center Amsterdam (LYMMCARE), Amsterdam 1105 AZ, The Netherlands.
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16
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Kawaguchi Y, Nariki H, Kawamoto N, Kanehiro Y, Miyazaki S, Suzuki M, Magari M, Tokumitsu H, Kanayama N. SRSF1-3 contributes to diversification of the immunoglobulin variable region gene by promoting accumulation of AID in the nucleus. Biochem Biophys Res Commun 2017; 485:261-266. [DOI: 10.1016/j.bbrc.2017.02.097] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 02/19/2017] [Indexed: 01/06/2023]
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17
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Girelli Zubani G, Zivojnovic M, De Smet A, Albagli-Curiel O, Huetz F, Weill JC, Reynaud CA, Storck S. Pms2 and uracil-DNA glycosylases act jointly in the mismatch repair pathway to generate Ig gene mutations at A-T base pairs. J Exp Med 2017; 214:1169-1180. [PMID: 28283534 PMCID: PMC5379981 DOI: 10.1084/jem.20161576] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 12/19/2016] [Accepted: 01/26/2017] [Indexed: 11/06/2022] Open
Abstract
Girelli Zubani et al. show that the Pms2 component of the mismatch repair complex and multiple uracil glycosylases contribute, each with a distinct strand bias, to enlarge the Ig gene mutation spectrum from G-C to A-T bases. During somatic hypermutation (SHM) of immunoglobulin genes, uracils introduced by activation-induced cytidine deaminase are processed by uracil-DNA glycosylase (UNG) and mismatch repair (MMR) pathways to generate mutations at G-C and A-T base pairs, respectively. Paradoxically, the MMR-nicking complex Pms2/Mlh1 is apparently dispensable for A-T mutagenesis. Thus, how detection of U:G mismatches is translated into the single-strand nick required for error-prone synthesis is an open question. One model proposed that UNG could cooperate with MMR by excising a second uracil in the vicinity of the U:G mismatch, but it failed to explain the low impact of UNG inactivation on A-T mutagenesis. In this study, we show that uracils generated in the G1 phase in B cells can generate equal proportions of A-T and G-C mutations, which suggests that UNG and MMR can operate within the same time frame during SHM. Furthermore, we show that Ung−/−Pms2−/− mice display a 50% reduction in mutations at A-T base pairs and that most remaining mutations at A-T bases depend on two additional uracil glycosylases, thymine-DNA glycosylase and SMUG1. These results demonstrate that Pms2/Mlh1 and multiple uracil glycosylases act jointly, each one with a distinct strand bias, to enlarge the immunoglobulin gene mutation spectrum from G-C to A-T bases.
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Affiliation(s)
- Giulia Girelli Zubani
- Institut Necker-Enfants Malades, Institut National de la Santé et de la Recherche Médicale U1151, Centre National de la Recherche Scientifique UMR 8253, Faculté de Médecine-Site Broussais, Université Paris Descartes, Sorbonne Paris Cité, 75014 Paris, France
| | - Marija Zivojnovic
- Institut Necker-Enfants Malades, Institut National de la Santé et de la Recherche Médicale U1151, Centre National de la Recherche Scientifique UMR 8253, Faculté de Médecine-Site Broussais, Université Paris Descartes, Sorbonne Paris Cité, 75014 Paris, France
| | - Annie De Smet
- Institut Necker-Enfants Malades, Institut National de la Santé et de la Recherche Médicale U1151, Centre National de la Recherche Scientifique UMR 8253, Faculté de Médecine-Site Broussais, Université Paris Descartes, Sorbonne Paris Cité, 75014 Paris, France
| | - Olivier Albagli-Curiel
- Institut Cochin, Institut National de la Santé et de la Recherche Médicale U1016, Centre National de la Recherche Scientifique UMR8104, Faculté de Médecine-Site Cochin, Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France
| | - François Huetz
- Institut Necker-Enfants Malades, Institut National de la Santé et de la Recherche Médicale U1151, Centre National de la Recherche Scientifique UMR 8253, Faculté de Médecine-Site Broussais, Université Paris Descartes, Sorbonne Paris Cité, 75014 Paris, France.,Département d'Immunologie, Institut Pasteur, 75015 Paris, France
| | - Jean-Claude Weill
- Institut Necker-Enfants Malades, Institut National de la Santé et de la Recherche Médicale U1151, Centre National de la Recherche Scientifique UMR 8253, Faculté de Médecine-Site Broussais, Université Paris Descartes, Sorbonne Paris Cité, 75014 Paris, France
| | - Claude-Agnès Reynaud
- Institut Necker-Enfants Malades, Institut National de la Santé et de la Recherche Médicale U1151, Centre National de la Recherche Scientifique UMR 8253, Faculté de Médecine-Site Broussais, Université Paris Descartes, Sorbonne Paris Cité, 75014 Paris, France
| | - Sébastien Storck
- Institut Necker-Enfants Malades, Institut National de la Santé et de la Recherche Médicale U1151, Centre National de la Recherche Scientifique UMR 8253, Faculté de Médecine-Site Broussais, Université Paris Descartes, Sorbonne Paris Cité, 75014 Paris, France
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18
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Risks at the DNA Replication Fork: Effects upon Carcinogenesis and Tumor Heterogeneity. Genes (Basel) 2017; 8:genes8010046. [PMID: 28117753 PMCID: PMC5295039 DOI: 10.3390/genes8010046] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 01/09/2017] [Accepted: 01/17/2017] [Indexed: 12/27/2022] Open
Abstract
The ability of all organisms to copy their genetic information via DNA replication is a prerequisite for cell division and a biological imperative of life. In multicellular organisms, however, mutations arising from DNA replication errors in the germline and somatic cells are the basis of genetic diseases and cancer, respectively. Within human tumors, replication errors additionally contribute to mutator phenotypes and tumor heterogeneity, which are major confounding factors for cancer therapeutics. Successful DNA replication involves the coordination of many large-scale, complex cellular processes. In this review, we focus on the roles that defects in enzymes that normally act at the replication fork and dysregulation of enzymes that inappropriately damage single-stranded DNA at the fork play in causing mutations that contribute to carcinogenesis. We focus on tumor data and experimental evidence that error-prone variants of replicative polymerases promote carcinogenesis and on research indicating that the primary target mutated by APOBEC (apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like) cytidine deaminases is ssDNA present at the replication fork. Furthermore, we discuss evidence from model systems that indicate replication stress and other cancer-associated metabolic changes may modulate mutagenic enzymatic activities at the replication fork.
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19
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Methot S, Di Noia J. Molecular Mechanisms of Somatic Hypermutation and Class Switch Recombination. Adv Immunol 2017; 133:37-87. [DOI: 10.1016/bs.ai.2016.11.002] [Citation(s) in RCA: 165] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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20
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Wang Q, Kieffer-Kwon KR, Oliveira TY, Mayer CT, Yao K, Pai J, Cao Z, Dose M, Casellas R, Jankovic M, Nussenzweig MC, Robbiani DF. The cell cycle restricts activation-induced cytidine deaminase activity to early G1. J Exp Med 2016; 214:49-58. [PMID: 27998928 PMCID: PMC5206505 DOI: 10.1084/jem.20161649] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 10/21/2016] [Accepted: 11/22/2016] [Indexed: 02/02/2023] Open
Abstract
Wang et al. show that antibody gene deamination by activation-induced cytidine deaminase (AID) is restricted to a short time window in early G1 as a result of AID’s transient nuclear localization and accessibility of the target sites. Activation-induced cytidine deaminase (AID) converts cytosine into uracil to initiate somatic hypermutation (SHM) and class switch recombination (CSR) of antibody genes. In addition, this enzyme produces DNA lesions at off-target sites that lead to mutations and chromosome translocations. However, AID is mostly cytoplasmic, and how and exactly when it accesses nuclear DNA remains enigmatic. Here, we show that AID is transiently in spatial contact with genomic DNA from the time the nuclear membrane breaks down in prometaphase until early G1, when it is actively exported into the cytoplasm. Consistent with this observation, the immunoglobulin (Igh) gene deamination as measured by uracil accumulation occurs primarily in early G1 after chromosomes decondense. Altering the timing of cell cycle–regulated AID nuclear residence increases DNA damage at off-target sites. Thus, the cell cycle–controlled breakdown and reassembly of the nuclear membrane and the restoration of transcription after mitosis constitute an essential time window for AID-induced deamination, and provide a novel DNA damage mechanism restricted to early G1.
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Affiliation(s)
- Qiao Wang
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065
| | - Kyong-Rim Kieffer-Kwon
- Genomics and Immunity, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892.,Center of Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Thiago Y Oliveira
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065
| | - Christian T Mayer
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065
| | - Kaihui Yao
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065
| | - Joy Pai
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065
| | - Zhen Cao
- Weill Cornell Medical College and Memorial Sloan-Kettering Cancer Center, New York, NY 10065
| | - Marei Dose
- Genomics and Immunity, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892.,Center of Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Rafael Casellas
- Genomics and Immunity, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892.,Center of Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Mila Jankovic
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065
| | - Michel C Nussenzweig
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065 .,Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065
| | - Davide F Robbiani
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065
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21
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Abstract
The AID/APOBEC family enzymes convert cytosines in single-stranded DNA to uracils, causing base substitutions and strand breaks. They are induced by cytokines produced during the body's inflammatory response to infections, and they help combat infections through diverse mechanisms. AID is essential for the maturation of antibodies and causes mutations and deletions in antibody genes through somatic hypermutation (SHM) and class-switch recombination (CSR) processes. One member of the APOBEC family, APOBEC1, edits mRNA for a protein involved in lipid transport. Members of the APOBEC3 subfamily in humans (APOBEC3A, APOBEC3B, APOBEC3C, APOBEC3D, APOBEC3F, APOBEC3G, and APOBEC3H) inhibit infections of viruses such as HIV-1, HBV, and HCV, and retrotransposition of endogenous retroelements through mutagenic and nonmutagenic mechanisms. There is emerging consensus that these enzymes can cause mutations in the cellular genome at replication forks or within transcription bubbles depending on the physiological state of the cell and the phase of the cell cycle during which they are expressed. We describe here the state of knowledge about the structures of these enzymes, regulation of their expression, and both the advantageous and deleterious consequences of their expression, including carcinogenesis. We highlight similarities among them and present a holistic view of their regulation and function.
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Affiliation(s)
- Sachini U Siriwardena
- Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States
| | - Kang Chen
- Department of Obstetrics and Gynecology, Wayne State University , Detroit, Michigan 48201, United States
- Mucosal Immunology Studies Team, National Institute of Allergy and Infectious Diseases, National Institutes of Health , Bethesda, Maryland 20892, United States
- Department of Immunology and Microbiology, Wayne State University School of Medicine , Detroit, Michigan 48201, United States
| | - Ashok S Bhagwat
- Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States
- Department of Immunology and Microbiology, Wayne State University School of Medicine , Detroit, Michigan 48201, United States
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22
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Activation induced cytidine deaminase mutant (AID-His130Pro) from Hyper IgM 2 patient retained mutagenic activity on SHM artificial substrate. Mol Immunol 2016; 79:77-82. [PMID: 27716525 DOI: 10.1016/j.molimm.2016.09.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 09/27/2016] [Accepted: 09/29/2016] [Indexed: 01/01/2023]
Abstract
Activation induced cytidine deaminase (AID) is an essential enzyme for class switch recombination (CSR) and somatic hypermutation (SHM) during secondary immune response. Mutations in the AICDA gene are responsible for Hyper IgM 2 syndrome where both CSR and SHM or only CSR are affected. Indeed, triggering either of the two mechanisms requires the DNA deamination activity of AID. Besides, different domains of AID may be differentially involved in CSR and SHM through their interaction with specific cofactors. Herein, we studied the AID-induced SHM activity of the AID-His130Pro mutant identified in a patient with Hyper IgM 2 syndrome. AID mutagenic activity was monitored by the reversion of nonsense mutations of the EGFP gene assessed by flow cytometry. We found that the His130Pro mutation, which affects CSR, preserves AID mutagenic activity. Indeed, the His130 residue is located in a putative specific CSR region in the APOBEC-like domain, known to involve CSR specific cofactors that probably play a major role in AID physiological activities.
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23
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Mutations, kataegis and translocations in B cells: understanding AID promiscuous activity. Nat Rev Immunol 2016; 16:164-76. [PMID: 26898111 DOI: 10.1038/nri.2016.2] [Citation(s) in RCA: 128] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
As B cells engage in the immune response, they express activation-induced cytidine deaminase (AID) to initiate the hypermutation and recombination of immunoglobulin genes, which are crucial processes for the efficient recognition and disposal of pathogens. However, AID must be tightly controlled in B cells to minimize off-target mutations, which can drive chromosomal translocations and the development of B cell malignancies, such as lymphomas. Recent genomic and biochemical analyses have begun to unravel the mechanisms of how AID-mediated deamination is targeted outside immunoglobulin genes. Here, we discuss the transcriptional and topological features that are emerging as key drivers of AID promiscuous activity.
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24
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Affiliation(s)
- Cristina Rada
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
- * E-mail:
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