1
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Li Q, Fan J, Zhou Z, Ma Z, Che Z, Wu Y, Yang X, Liang P, Li H. AID-induced CXCL12 upregulation enhances castration-resistant prostate cancer cell metastasis by stabilizing β-catenin expression. iScience 2023; 26:108523. [PMID: 38162032 PMCID: PMC10755053 DOI: 10.1016/j.isci.2023.108523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 11/14/2023] [Accepted: 11/20/2023] [Indexed: 01/03/2024] Open
Abstract
Prostate cancer (PCa) is one of the most common malignant diseases of urinary system and has poor prognosis after progression to castration-resistant prostate cancer (CRPC), and increased cytosine methylation heterogeneity is associated with the more aggressive phenotype of PCa cell line. Activation-induced cytidine deaminase (AID) is a multifunctional enzyme and contributes to antibody diversification. However, the dysregulation of AID participates in the progression of multiple diseases and related with certain oncogenes through demethylation. Nevertheless, the role of AID in PCa remains elusive. We observed a significant upregulation of AID expression in PCa samples, which exhibited a negative correlation with E-cadherin expression. Furthermore, AID expression is remarkably higher in CRPC cells than that in HSPC cells, and AID induced the demethylation of CXCL12, which is required to stabilize the Wnt signaling pathway executor β-catenin and EMT procedure. Our study suggests that AID drives CRPC metastasis by demethylation and can be a potential therapeutic target for CRPC.
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Affiliation(s)
- Qi Li
- Department of Urology, Renmin Hospital of Wuhan University, Wuhan, Hubei Province, China
- Department of Urology, TianYou Hospital affiliated to Wuhan University of Science & Technology, Wuhan, Hubei Province, China
| | - Jinfeng Fan
- Department of Urology, the First Affiliated Hospital of Hainan Medical College, Haikou, Hainan Province, China
| | - Zhiyan Zhou
- Department of Urology, the First Affiliated Hospital of Hainan Medical College, Haikou, Hainan Province, China
| | - Zhe Ma
- The First Hospital of Tsinghua University, Beijing, China
| | - Zhifei Che
- Department of Urology, the First Affiliated Hospital of Hainan Medical College, Haikou, Hainan Province, China
| | - Yaoxi Wu
- Department of Urology, the First Affiliated Hospital of Hainan Medical College, Haikou, Hainan Province, China
| | - Xiangli Yang
- Department of Urology, TianYou Hospital affiliated to Wuhan University of Science & Technology, Wuhan, Hubei Province, China
| | - Peiyu Liang
- Department of Urology, the First Affiliated Hospital of Hainan Medical College, Haikou, Hainan Province, China
| | - Haoyong Li
- Department of Urology, Renmin Hospital of Wuhan University, Wuhan, Hubei Province, China
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2
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Leeman-Neill RJ, Song D, Bizarro J, Wacheul L, Rothschild G, Singh S, Yang Y, Sarode AY, Gollapalli K, Wu L, Zhang W, Chen Y, Lauring MC, Whisenant DE, Bhavsar S, Lim J, Swerdlow SH, Bhagat G, Zhao Q, Berchowitz LE, Lafontaine DLJ, Wang J, Basu U. Noncoding mutations cause super-enhancer retargeting resulting in protein synthesis dysregulation during B cell lymphoma progression. Nat Genet 2023; 55:2160-2174. [PMID: 38049665 PMCID: PMC10703697 DOI: 10.1038/s41588-023-01561-1] [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: 05/24/2023] [Accepted: 10/09/2023] [Indexed: 12/06/2023]
Abstract
Whole-genome sequencing of longitudinal tumor pairs representing transformation of follicular lymphoma to high-grade B cell lymphoma with MYC and BCL2 rearrangements (double-hit lymphoma) identified coding and noncoding genomic alterations acquired during lymphoma progression. Many of these transformation-associated alterations recurrently and focally occur at topologically associating domain resident regulatory DNA elements, including H3K4me3 promoter marks located within H3K27ac super-enhancer clusters in B cell non-Hodgkin lymphoma. One region found to undergo recurrent alteration upon transformation overlaps a super-enhancer affecting the expression of the PAX5/ZCCHC7 gene pair. ZCCHC7 encodes a subunit of the Trf4/5-Air1/2-Mtr4 polyadenylation-like complex and demonstrated copy number gain, chromosomal translocation and enhancer retargeting-mediated transcriptional upregulation upon lymphoma transformation. Consequently, lymphoma cells demonstrate nucleolar dysregulation via altered noncoding 5.8S ribosomal RNA processing. We find that a noncoding mutation acquired during lymphoma progression affects noncoding rRNA processing, thereby rewiring protein synthesis leading to oncogenic changes in the lymphoma proteome.
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Affiliation(s)
- Rebecca J Leeman-Neill
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY, USA
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY, USA
| | - Dong Song
- SIAT-HKUST Joint Laboratory of Cell Evolution and Digital Health, Shenzhen-Hong Kong Collaborative Innovation Research Institute, Shenzhen, China
- Division of Life Science, Department of Chemical and Biological Engineering, and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Jonathan Bizarro
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY, USA
| | - Ludivine Wacheul
- RNA Molecular Biology, Fonds de la Recherche Scientifique (F.R.S./FNRS), Université libre de Bruxelles (ULB), Biopark Campus, Gosselies, Belgium
| | - Gerson Rothschild
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY, USA
| | - Sameer Singh
- Institut für Medizinische Physik und Biophysik, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Yang Yang
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong SAR, China
| | - Aditya Y Sarode
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY, USA
| | - Kishore Gollapalli
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY, USA
| | - Lijing Wu
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY, USA
| | - Wanwei Zhang
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY, USA
| | - Yiyun Chen
- Division of Life Science, Department of Chemical and Biological Engineering, and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Hong Kong SAR, China
| | - Max C Lauring
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY, USA
| | - D Eric Whisenant
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY, USA
| | - Shweta Bhavsar
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Junghyun Lim
- Department of Pharmacy, School of Pharmacy and Institute of New Drug Development, Jeonbuk National University, Jeonju, Republic of Korea
| | - Steven H Swerdlow
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Govind Bhagat
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY, USA
| | - Qian Zhao
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong SAR, China
| | - Luke E Berchowitz
- Department of Genetics and Development, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY, USA
| | - Denis L J Lafontaine
- RNA Molecular Biology, Fonds de la Recherche Scientifique (F.R.S./FNRS), Université libre de Bruxelles (ULB), Biopark Campus, Gosselies, Belgium
| | - Jiguang Wang
- SIAT-HKUST Joint Laboratory of Cell Evolution and Digital Health, Shenzhen-Hong Kong Collaborative Innovation Research Institute, Shenzhen, China.
- Division of Life Science, Department of Chemical and Biological Engineering, and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Hong Kong SAR, China.
- Hong Kong Center for Neurodegenerative Diseases, InnoHK, Hong Kong SAR, China.
| | - Uttiya Basu
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York City, NY, USA.
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3
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Caballero M, Koren A. The landscape of somatic mutations in lymphoblastoid cell lines. CELL GENOMICS 2023; 3:100305. [PMID: 37388907 PMCID: PMC10300552 DOI: 10.1016/j.xgen.2023.100305] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 02/03/2023] [Accepted: 03/28/2023] [Indexed: 07/01/2023]
Abstract
Somatic mutations have important biological ramifications while exerting substantial rate, type, and genomic location heterogeneity. Yet, their sporadic occurrence makes them difficult to study at scale and across individuals. Lymphoblastoid cell lines (LCLs), a model system for human population and functional genomics, harbor large numbers of somatic mutations and have been extensively genotyped. By comparing 1,662 LCLs, we report that the mutational landscape of the genome varies across individuals in terms of the number of mutations, their genomic locations, and their spectra; this variation may itself be modulated by somatic trans-acting mutations. Mutations attributed to the translesion DNA polymerase η follow two different modes of formation, with one mode accounting for the hypermutability of the inactive X chromosome. Nonetheless, the distribution of mutations along the inactive X chromosome appears to follow an epigenetic memory of the active form.
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Affiliation(s)
- Madison Caballero
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Amnon Koren
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
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4
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Ocsenas O, Reimand J. Chromatin accessibility of primary human cancers ties regional mutational processes and signatures with tissues of origin. PLoS Comput Biol 2022; 18:e1010393. [PMID: 35947558 PMCID: PMC9365152 DOI: 10.1371/journal.pcbi.1010393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Accepted: 07/15/2022] [Indexed: 11/19/2022] Open
Abstract
Somatic mutations in cancer genomes are associated with DNA replication timing (RT) and chromatin accessibility (CA), however these observations are based on normal tissues and cell lines while primary cancer epigenomes remain uncharacterised. Here we use machine learning to model megabase-scale mutation burden in 2,500 whole cancer genomes and 17 cancer types via a compendium of 900 CA and RT profiles covering primary cancers, normal tissues, and cell lines. CA profiles of primary cancers, rather than those of normal tissues, are most predictive of regional mutagenesis in most cancer types. Feature prioritisation shows that the epigenomes of matching cancer types and organ systems are often the strongest predictors of regional mutation burden, highlighting disease-specific associations of mutational processes. The genomic distributions of mutational signatures are also shaped by the epigenomes of matched cancer and tissue types, with SBS5/40, carcinogenic and unknown signatures most accurately predicted by our models. In contrast, fewer associations of RT and regional mutagenesis are found. Lastly, the models highlight genomic regions with overrepresented mutations that dramatically exceed epigenome-derived expectations and show a pan-cancer convergence to genes and pathways involved in development and oncogenesis, indicating the potential of this approach for coding and non-coding driver discovery. The association of regional mutational processes with the epigenomes of primary cancers suggests that the landscape of passenger mutations is predominantly shaped by the epigenomes of cancer cells after oncogenic transformation.
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Affiliation(s)
- Oliver Ocsenas
- Computational Biology Program, Ontario Institute for Cancer Research, Toronto, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, Canada
| | - Jüri Reimand
- Computational Biology Program, Ontario Institute for Cancer Research, Toronto, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
- * E-mail:
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5
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Tarsalainen A, Maman Y, Meng FL, Kyläniemi MK, Soikkeli A, Budzynska P, McDonald JJ, Šenigl F, Alt FW, Schatz DG, Alinikula J. Ig Enhancers Increase RNA Polymerase II Stalling at Somatic Hypermutation Target Sequences. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2022; 208:143-154. [PMID: 34862258 PMCID: PMC8702490 DOI: 10.4049/jimmunol.2100923] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 10/20/2021] [Indexed: 01/03/2023]
Abstract
Somatic hypermutation (SHM) drives the genetic diversity of Ig genes in activated B cells and supports the generation of Abs with increased affinity for Ag. SHM is targeted to Ig genes by their enhancers (diversification activators [DIVACs]), but how the enhancers mediate this activity is unknown. We show using chicken DT40 B cells that highly active DIVACs increase the phosphorylation of RNA polymerase II (Pol II) and Pol II occupancy in the mutating gene with little or no accompanying increase in elongation-competent Pol II or production of full-length transcripts, indicating accumulation of stalled Pol II. DIVAC has similar effect also in human Ramos Burkitt lymphoma cells. The DIVAC-induced stalling is weakly associated with an increase in the detection of ssDNA bubbles in the mutating target gene. We did not find evidence for antisense transcription, or that DIVAC functions by altering levels of H3K27ac or the histone variant H3.3 in the mutating gene. These findings argue for a connection between Pol II stalling and cis-acting targeting elements in the context of SHM and thus define a mechanistic basis for locus-specific targeting of SHM in the genome. Our results suggest that DIVAC elements render the target gene a suitable platform for AID-mediated mutation without a requirement for increasing transcriptional output.
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Affiliation(s)
- Alina Tarsalainen
- Unit of Infections and Immunity, Institute of Biomedicine, University of Turku, 20520 Turku, Finland
| | - Yaakov Maman
- The Azrieli Faculty of Medicine, Bar Ilan University, Safed, 1311502, Israel
| | - Fei-Long Meng
- Department of Genetics, Harvard Medical School and Program in Cellular and Molecular Medicine, HHMI, Boston Children’s Hospital, Boston, MA 02115, USA.,Current address: State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Minna K. Kyläniemi
- Unit of Infections and Immunity, Institute of Biomedicine, University of Turku, 20520 Turku, Finland,Current address: Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20520 Turku, Finland
| | - Anni Soikkeli
- Unit of Infections and Immunity, Institute of Biomedicine, University of Turku, 20520 Turku, Finland
| | - Paulina Budzynska
- Unit of Infections and Immunity, Institute of Biomedicine, University of Turku, 20520 Turku, Finland
| | - Jessica J. McDonald
- Department of Immunobiology, Yale School of Medicine, New Haven, CT 06511, USA,Current address: The Annenberg Public Policy Center, Philadelphia, PA 19104-3806, USA
| | - Filip Šenigl
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, 142 20 Praha 4, Czech Republic
| | - Frederic W. Alt
- Department of Genetics, Harvard Medical School and Program in Cellular and Molecular Medicine, HHMI, Boston Children’s Hospital, Boston, MA 02115, USA
| | - David G. Schatz
- Department of Immunobiology, Yale School of Medicine, New Haven, CT 06511, USA,Correspondence should be addressed to and
| | - Jukka Alinikula
- Unit of Infections and Immunity, Institute of Biomedicine, University of Turku, 20520 Turku, Finland,Correspondence should be addressed to and
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6
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The role of HIRA-dependent H3.3 deposition and its modifications in the somatic hypermutation of immunoglobulin variable regions. Proc Natl Acad Sci U S A 2021; 118:2114743118. [PMID: 34873043 DOI: 10.1073/pnas.2114743118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/27/2021] [Indexed: 12/17/2022] Open
Abstract
The H3.3 histone variant and its chaperone HIRA are involved in active transcription, but their detailed roles in regulating somatic hypermutation (SHM) of immunoglobulin variable regions in human B cells are not yet fully understood. In this study, we show that the knockout (KO) of HIRA significantly decreased SHM and changed the mutation pattern of the variable region of the immunoglobulin heavy chain (IgH) in the human Ramos B cell line without changing the levels of activation-induced deaminase and other major proteins known to be involved in SHM. Except for H3K79me2/3 and Spt5, many factors related to active transcription, including H3.3, were substantively decreased in HIRA KO cells, and this was accompanied by decreased nascent transcription in the IgH locus. The abundance of ZMYND11 that specifically binds to H3.3K36me3 on the IgH locus was also reduced in the HIRA KO. Somewhat surprisingly, HIRA loss increased the chromatin accessibility of the IgH V region locus. Furthermore, stable expression of ectopic H3.3G34V and H3.3G34R mutants that inhibit both the trimethylation of H3.3K36 and the recruitment of ZMYND11 significantly reduced SHM in Ramos cells, while the H3.3K79M did not. Consistent with the HIRA KO, the H3.3G34V mutant also decreased the occupancy of various elongation factors and of ZMYND11 on the IgH variable and downstream switching regions. Our results reveal an unrecognized role of HIRA and the H3.3K36me3 modification in SHM and extend our knowledge of how transcription-associated chromatin structure and accessibility contribute to SHM in human B cells.
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7
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Yu W, Lu L, Ji X, Qian Q, Lin X, Wang H. Recent Advances on Possible Association Between the Periodontal Infection of Porphyromonas gingivalis and Central Nervous System Injury. J Alzheimers Dis 2021; 84:51-59. [PMID: 34487050 DOI: 10.3233/jad-215143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Chronic periodontitis caused by Porphyromonas gingivalis (P. gingivalis) infection generally lasts for a lifetime. The long-term existence and development of P. gingivalis infection gradually aggravate the accumulation of inflammatory signals and toxic substances in the body. Recent evidence has revealed that P. gingivalis infection may be relevant to some central nervous system (CNS) diseases. The current work collects information and tries to explore the possible relationship between P. gingivalis infection and CNS diseases, including the interaction or pathways between peripheral infection and CNS injury, and the underlying neurotoxic mechanisms.
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Affiliation(s)
- Wenlei Yu
- School of Basic Medical Sciences, Hangzhou Normal University, Hangzhou, China.,Laboratory of Aging and Cancer Biology of Zhejiang Province, Hangzhou Normal University, Hangzhou, China
| | - Linjie Lu
- School of Basic Medical Sciences, Hangzhou Normal University, Hangzhou, China.,Laboratory of Aging and Cancer Biology of Zhejiang Province, Hangzhou Normal University, Hangzhou, China
| | - Xintong Ji
- School of Basic Medical Sciences, Hangzhou Normal University, Hangzhou, China.,Laboratory of Aging and Cancer Biology of Zhejiang Province, Hangzhou Normal University, Hangzhou, China
| | - Qiwei Qian
- School of Basic Medical Sciences, Hangzhou Normal University, Hangzhou, China.,Laboratory of Aging and Cancer Biology of Zhejiang Province, Hangzhou Normal University, Hangzhou, China
| | - Xiaohan Lin
- School of Basic Medical Sciences, Hangzhou Normal University, Hangzhou, China
| | - Huanhuan Wang
- School of Basic Medical Sciences, Hangzhou Normal University, Hangzhou, China.,Laboratory of Aging and Cancer Biology of Zhejiang Province, Hangzhou Normal University, Hangzhou, China
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8
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Role of Dot1L and H3K79 methylation in regulating somatic hypermutation of immunoglobulin genes. Proc Natl Acad Sci U S A 2021; 118:2104013118. [PMID: 34253616 DOI: 10.1073/pnas.2104013118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Somatic hypermutation (SHM) and class-switch recombination (CSR) of the immunoglobulin (Ig) genes allow B cells to make antibodies that protect us against a wide variety of pathogens. SHM is mediated by activation-induced deaminase (AID), occurs at a million times higher frequency than other mutations in the mammalian genome, and is largely restricted to the variable (V) and switch (S) regions of Ig genes. Using the Ramos human Burkitt's lymphoma cell line, we find that H3K79me2/3 and its methyltransferase Dot1L are more abundant on the V region than on the constant (C) region, which does not undergo mutation. In primary naïve mouse B cells examined ex vivo, the H3K79me2/3 modification appears constitutively in the donor Sμ and is inducible in the recipient Sγ1 upon CSR stimulation. Knockout and inhibition of Dot1L in Ramos cells significantly reduces V region mutation and the abundance of H3K79me2/3 on the V region and is associated with a decrease of polymerase II (Pol II) and its S2 phosphorylated form at the IgH locus. Knockout of Dot1L also decreases the abundance of BRD4 and CDK9 (a subunit of the P-TEFb complex) on the V region, and this is accompanied by decreased nascent transcripts throughout the IgH gene. Treatment with JQ1 (inhibitor of BRD4) or DRB (inhibitor of CDK9) decreases SHM and the abundance of Pol II S2P at the IgH locus. Since all these factors play a role in transcription elongation, our studies reinforce the idea that the chromatin context and dynamics of transcription are critical for SHM.
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9
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Senigl F, Maman Y, Dinesh RK, Alinikula J, Seth RB, Pecnova L, Omer AD, Rao SSP, Weisz D, Buerstedde JM, Aiden EL, Casellas R, Hejnar J, Schatz DG. Topologically Associated Domains Delineate Susceptibility to Somatic Hypermutation. Cell Rep 2020; 29:3902-3915.e8. [PMID: 31851922 PMCID: PMC6980758 DOI: 10.1016/j.celrep.2019.11.039] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 06/26/2019] [Accepted: 11/08/2019] [Indexed: 12/26/2022] Open
Abstract
Somatic hypermutation (SHM) introduces point mutations into immunoglobulin (Ig) genes but also causes mutations in other parts of the genome. We have used lentiviral SHM reporter vectors to identify regions of the genome that are susceptible (“hot”) and resistant (“cold”) to SHM, revealing that SHM susceptibility and resistance are often properties of entire topologically associated domains (TADs). Comparison of hot and cold TADs reveals that while levels of transcription are equivalent, hot TADs are enriched for the cohesin loader NIPBL, super-enhancers, markers of paused/stalled RNA polymerase 2, and multiple important B cell transcription factors. We demonstrate that at least some hot TADs contain enhancers that possess SHM targeting activity and that insertion of a strong Ig SHM-targeting element into a cold TAD renders it hot. Our findings lead to a model for SHM susceptibility involving the cooperative action of cis-acting SHM targeting elements and the dynamic and architectural properties of TADs. Senigl et al. show that genome susceptibility to somatic hypermutation (SHM) is confined within topologically associated domains (TADs) and is linked to markers of strong enhancers and stalled transcription and high levels of the cohesin loader NIPBL. Insertion of an ectopic SHM targeting element renders an entire TAD susceptible to SHM.
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Affiliation(s)
- Filip Senigl
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083, 14220 Prague 4, Czech Republic.
| | - Yaakov Maman
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Ravi K Dinesh
- Department of Immunobiology, Yale School of Medicine, 300 Cedar Street, Box 208011, New Haven, CT 06520-8011, USA
| | - Jukka Alinikula
- Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, 20520 Turku, Finland
| | - Rashu B Seth
- Department of Immunobiology, Yale School of Medicine, 300 Cedar Street, Box 208011, New Haven, CT 06520-8011, USA
| | - Lubomira Pecnova
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083, 14220 Prague 4, Czech Republic
| | - Arina D Omer
- Center for Genome Architecture, Baylor College of Medicine, Houston, TX 77030, USA
| | - Suhas S P Rao
- Center for Genome Architecture, Baylor College of Medicine, Houston, TX 77030, USA
| | - David Weisz
- Center for Genome Architecture, Baylor College of Medicine, Houston, TX 77030, USA
| | | | - Erez Lieberman Aiden
- Center for Genome Architecture, Baylor College of Medicine, Houston, TX 77030, USA; Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA
| | - Rafael Casellas
- Lymphocyte Nuclear Biology, NIAMS, NIH, Bethesda, MD 20892, USA; Center of Cancer Research, NCI, NIH, Bethesda, MD 20892, USA
| | - Jiri Hejnar
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083, 14220 Prague 4, Czech Republic
| | - David G Schatz
- Department of Immunobiology, Yale School of Medicine, 300 Cedar Street, Box 208011, New Haven, CT 06520-8011, USA.
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10
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Oudinet C, Braikia FZ, Dauba A, Khamlichi AA. Mechanism and regulation of class switch recombination by IgH transcriptional control elements. Adv Immunol 2020; 147:89-137. [PMID: 32981636 DOI: 10.1016/bs.ai.2020.06.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Class switch recombination (CSR) plays an important role in humoral immunity by generating antibodies with different effector functions. CSR to a particular antibody isotype is induced by external stimuli, and occurs between highly repetitive switch (S) sequences. CSR requires transcription across S regions, which generates long non-coding RNAs and secondary structures that promote accessibility of S sequences to activation-induced cytidine deaminase (AID). AID initiates DNA double-strand breaks (DSBs) intermediates that are repaired by general DNA repair pathways. Switch transcription is controlled by various regulatory elements, including enhancers and insulators. The current paradigm posits that transcriptional control of CSR involves long-range chromatin interactions between regulatory elements and chromatin loops-stabilizing factors, which promote alignment of partner S regions in a CSR centre (CSRC) and initiation of CSR. In this review, we focus on the role of IgH transcriptional control elements in CSR and the chromatin-based mechanisms underlying this control.
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Affiliation(s)
- Chloé Oudinet
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, Toulouse, France; Institut de Pharmacologie et de Biologie Structurale, CNRS, Université Paul Sabatier, Toulouse, France
| | - Fatima-Zohra Braikia
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, Toulouse, France; Institut de Pharmacologie et de Biologie Structurale, CNRS, Université Paul Sabatier, Toulouse, France
| | - Audrey Dauba
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, Toulouse, France; Institut de Pharmacologie et de Biologie Structurale, CNRS, Université Paul Sabatier, Toulouse, France
| | - Ahmed Amine Khamlichi
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, Toulouse, France; Institut de Pharmacologie et de Biologie Structurale, CNRS, Université Paul Sabatier, Toulouse, France.
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11
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Feng Y, Seija N, Di Noia JM, Martin A. AID in Antibody Diversification: There and Back Again. Trends Immunol 2020; 41:586-600. [PMID: 32434680 PMCID: PMC7183997 DOI: 10.1016/j.it.2020.04.009] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 04/16/2020] [Accepted: 04/20/2020] [Indexed: 01/01/2023]
Abstract
Activation-Induced cytidine Deaminase (AID) initiates affinity maturation and isotype switching by deaminating deoxycytidines within immunoglobulin genes, leading to somatic hypermutation (SHM) and class switch recombination (CSR). AID thus potentiates the humoral response to clear pathogens. Marking the 20th anniversary of the discovery of AID, we review the current understanding of AID function. We discuss AID biochemistry and how error-free forms of DNA repair are co-opted to prioritize mutagenesis over accuracy during antibody diversification. We discuss the regulation of DNA double-strand break (DSB) repair pathways during CSR. We describe genomic targeting of AID as a multilayered process involving chromatin architecture, cis- and trans-acting factors, and determining mutagenesis – distinct from AID occupancy at loci that are spared from mutation. Subverted base excision repair (BER) and mismatch repair (MMR) pathways act concertedly to generate antibody sequence diversity during SHM. In CSR, DNA DSBs are repaired by the nonhomologous end-joining pathway involving the 53BP1–Rif1–Shieldin axis, and by an alternative end-joining pathway involving HMCES (5-Hydroxymethylcytosine binding, ES-cell-specific) that binds and protects resected DSB ends. Genomic targeting of AID appears to be multilayered, with inbuilt redundancy, but robust enough to ensure that most of the genome is spared from AID activity. Cis elements and genome topology act together with trans-acting factors involved in transcription and RNA processing to determine AID activity at specific Ig regions. Other loci sharing genomic and transcriptional features with the Ig are collaterally targeted during SHM and CSR.
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Affiliation(s)
- Yuqing Feng
- Department of Immunology, University of Toronto, Toronto, ON, Canada
| | - Noé Seija
- Institute de Recherches Cliniques de Montréal, Montréal, QC, Canada; Molecular Biology Programs, Department of Medicine, University of Montreal, Montréal, QC, Canada
| | - Javier M Di Noia
- Institute de Recherches Cliniques de Montréal, Montréal, QC, Canada; Molecular Biology Programs, Department of Medicine, University of Montreal, Montréal, QC, Canada.
| | - Alberto Martin
- Department of Immunology, University of Toronto, Toronto, ON, Canada.
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12
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Jiao J, Lv Z, Zhang P, Wang Y, Yuan M, Yu X, Otieno Odhiambo W, Zheng M, Zhang H, Ma Y, Ji Y. AID assists DNMT1 to attenuate BCL6 expression through DNA methylation in diffuse large B-cell lymphoma cell lines. Neoplasia 2020; 22:142-153. [PMID: 32062068 PMCID: PMC7021553 DOI: 10.1016/j.neo.2020.01.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 01/21/2020] [Accepted: 01/23/2020] [Indexed: 02/07/2023] Open
Abstract
The BCL6 proto-oncogene encodes a transcriptional repressor, which is required for germinal centers (GCs) formation and lymphomagenesis. Previous studies have been reported that the constitutive expression of BCL6 leads to diffuse large B cell lymphoma (DLBCL) through activation-induced cytidine deaminase (AID) mediated chromosomal translocations and mutations. However, other DLBCLs (45%) without structural variants were characterized by abnormally high level of BCL6 expression through an unknown mechanism. Herein, we report that deficiency in AID or methyltransferase 1 (DNMT1) triggers high level of BCL6 expression. AID-DNMT1 complex binds to −0.4 kb −0 kb region of BCL6 promoter and contributes to generate BCL6 methylation which results in inhibition of BCL6 expression. The proteasome pathway inhibitor MG132 induces accumulation of AID and DNMT1, causes decreased BCL6 expression, and leads to cell apoptosis and tumor growth inhibition in DLBCL cell xenograft mice. These findings propose mechanistic insight into an alternative cofactor role of AID in assisting DNMT1 to maintain BCL6 methylation, thus suppress BCL6 transcription in DLBCL. This novel mechanism will provide a new drug selection in the therapeutic approach to DLBCL in the future.
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Affiliation(s)
- Junna Jiao
- Department of Pathogenic Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Centre, Xi'an, Shaanxi, China; Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an, Shaanxi, China
| | - Zhuangwei Lv
- Department of Pathogenic Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Centre, Xi'an, Shaanxi, China; Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an, Shaanxi, China
| | - Ping Zhang
- Department of Pathogenic Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Centre, Xi'an, Shaanxi, China; Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an, Shaanxi, China
| | - Yang Wang
- Department of Pathogenic Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Centre, Xi'an, Shaanxi, China; Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an, Shaanxi, China
| | - Meng Yuan
- Department of Pathogenic Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Centre, Xi'an, Shaanxi, China; Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an, Shaanxi, China
| | - Xiaozhuo Yu
- Department of Pathogenic Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Centre, Xi'an, Shaanxi, China; Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an, Shaanxi, China
| | - Woodvine Otieno Odhiambo
- Department of Pathogenic Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Centre, Xi'an, Shaanxi, China; Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an, Shaanxi, China
| | - Mingzhe Zheng
- Department of Pathogenic Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Centre, Xi'an, Shaanxi, China; Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an, Shaanxi, China
| | - Hua Zhang
- Department of Pathogenic Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Centre, Xi'an, Shaanxi, China; Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an, Shaanxi, China
| | - Yunfeng Ma
- Department of Pathogenic Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Centre, Xi'an, Shaanxi, China; Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an, Shaanxi, China
| | - Yanhong Ji
- Department of Pathogenic Biology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Centre, Xi'an, Shaanxi, China; Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an, Shaanxi, China.
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Heltzel JMH, Gearhart PJ. What Targets Somatic Hypermutation to the Immunoglobulin Loci? Viral Immunol 2019; 33:277-281. [PMID: 31770070 DOI: 10.1089/vim.2019.0149] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
One of the most profound enigmas in B cell biology is how activation-induced deaminase (AID) is targeted to a very small region of DNA in the immunoglobulin loci. Two specific regions are singled out: the variable region of 2 kb that contains rearranged genes on the heavy, κ light, and λ light chain loci, and the switch region of ∼4 kb that contains an extensive stretch of G:C rich DNA on the heavy chain locus. Transcription is required for AID recruitment; however, many genes are also highly transcribed and do not undergo the catastrophic mutagenesis that occurs in variable and switch regions. The DNA sequences of these regions cause RNA polymerase II to accumulate for an extended distance of 2-4 kb. The stalled polymerases then recruit the transcription cofactor Spt5, and AID, which deaminates cytosines to uracils in exposed transcription bubbles. Thus, the immunoglobulin loci are unique in that a favorable combination of DNA sequences and 3' transcription enhancers make them the perfect storm for AID-induced somatic hypermutation.
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Affiliation(s)
- Justin M H Heltzel
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
| | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, USA
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14
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Singh AK, Jaiswal A, Kodgire P. AID preferentially targets the top strand in nucleosome sequences. Mol Immunol 2019; 112:198-205. [DOI: 10.1016/j.molimm.2019.05.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Revised: 04/29/2019] [Accepted: 05/31/2019] [Indexed: 02/06/2023]
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15
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Non-canonical DNA/RNA structures during Transcription-Coupled Double-Strand Break Repair: Roadblocks or Bona fide repair intermediates? DNA Repair (Amst) 2019; 81:102661. [PMID: 31331819 DOI: 10.1016/j.dnarep.2019.102661] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Although long overlooked, it is now well understood that DNA does not systematically assemble into a canonical double helix, known as B-DNA, throughout the entire genome but can also accommodate other structures including DNA hairpins, G-quadruplexes and RNA:DNA hybrids. Notably, these non-canonical DNA structures form preferentially at transcriptionally active loci. Acting as replication roadblocks and being targeted by multiple machineries, these structures weaken the genome and render it prone to damage, including DNA double-strand breaks (DSB). In addition, secondary structures also further accumulate upon DSB formation. Here we discuss the potential functions of pre-existing or de novo formed nucleic acid structures, as bona fide repair intermediates or repair roadblocks, especially during Transcription-Coupled DNA Double-Strand Break repair (TC-DSBR), and provide an update on the specialized protein complexes displaying the ability to remove these structures to safeguard genome integrity.
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16
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Supek F, Lehner B. Scales and mechanisms of somatic mutation rate variation across the human genome. DNA Repair (Amst) 2019; 81:102647. [PMID: 31307927 DOI: 10.1016/j.dnarep.2019.102647] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Cancer genome sequencing has revealed that somatic mutation rates vary substantially across the human genome and at scales from megabase-sized domains to individual nucleotides. Here we review recent work that has both revealed the major mutation biases that operate across the genome and the molecular mechanisms that cause them. The default mutation rate landscape in mammalian genomes results in active genes having low mutation rates because of a combination of factors that increase DNA repair: early DNA replication, transcription, active chromatin modifications and accessible chromatin. Therefore, either an increase in the global mutation rate or a redistribution of mutations from inactive to active DNA can increase the rate at which consequential mutations are acquired in active genes. Several environmental carcinogens and intrinsic mechanisms operating in tumor cells likely cause cancer by this second mechanism: by specifically increasing the mutation rate in active regions of the genome.
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Affiliation(s)
- Fran Supek
- Genome Data Science, Institut de Recerca Biomedica (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028, Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys 23, 08010 Barcelona, Spain.
| | - Ben Lehner
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys 23, 08010 Barcelona, Spain; Systems Biology Program, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Doctor Aiguader 88, 08003 Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain
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17
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Wang Y, Feng W, Liu P. Genomic pattern of intratumor heterogeneity predicts the risk of progression in early stage diffuse large B-cell lymphoma. Carcinogenesis 2019; 40:1427-1434. [PMID: 31220210 DOI: 10.1093/carcin/bgz068] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 03/21/2019] [Accepted: 04/06/2019] [Indexed: 12/12/2022] Open
Abstract
Abstract
Intratumor heterogeneity (ITH) plays an important role in tumor development, metastases, recurrence and has impact on clinical diagnosis, therapeutic responses. In this study, we used mutant-allele tumor heterogeneity (MATH) through whole-exome sequencing data to evaluate ITH in early stage diffuse large B-cell lymphoma (DLBCL). A discovery set of 22 patients and a validation set of 35 patients with primary DLBCL which staged I or II were chosen from The Cancer Genome Atlas database and The Gene Index Project database, respectively. Then patients were divided into low and high MATH score groups according to the median expression level. As a result, higher MATH score displayed an increasing risk of progression compared with lower MATH score both in the discovery set (P = 0.045) and the validation set (P = 0.025). Further, the genomic pattern according to MATH demonstrated that mutation rates of immunoglobulin lambda locus, B-cell translocation gene and membrane-associated guanylate kinase were the sites with the highest mutation rate. Moreover, Gene enrichment analysis showed that immunoglobulin lambda constant 2 (IGLC2) which belongs to immunoglobulin lambda locus was only enriched in high MATH group. Besides, BTG2 and Caspase recruitment domain-containing protein 11 were cancer driver genes which listed on the top three high rate of mutation. Our study revealed the prognostic value of MATH and relevant genomic pattern in early stage DLBCL. Potential mechanisms on genetic level of how genomic aberration influence the ITH of DLBCL are provided. MATH based on whole genome sequencing may be feasible for deciding clinical treatment of DLBCL patients in the future researches.
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Affiliation(s)
- Yue Wang
- Department of Hematology, Zhongshan Hospital, Shanghai, China
| | - Wanjing Feng
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
- Department of Medical Oncology, Fudan University Shanghai Cancer Center, Shanghai, China
| | - Peng Liu
- Department of Hematology, Zhongshan Hospital, Shanghai, China
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18
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Yeap LS, Meng FL. Cis- and trans-factors affecting AID targeting and mutagenic outcomes in antibody diversification. Adv Immunol 2019; 141:51-103. [PMID: 30904133 DOI: 10.1016/bs.ai.2019.01.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Antigen receptor diversification is a hallmark of adaptive immunity which allows specificity of the receptor to particular antigen. B cell receptor (BCR) or its secreted form, antibody, is diversified through antigen-independent and antigen-dependent mechanisms. During B cell development in bone marrow, BCR is diversified via V(D)J recombination mediated by RAG endonuclease. Upon stimulation by antigen, B cell undergo somatic hypermutation (SHM) to allow affinity maturation and class switch recombination (CSR) to change the effector function of the antibody. Both SHM and CSR are initiated by activation-induced cytidine deaminase (AID). Repair of AID-initiated lesions through different DNA repair pathways results in diverse mutagenic outcomes. Here, we focus on discussing cis- and trans-factors that target AID to its substrates and factors that affect different outcomes of AID-initiated lesions. The knowledge of mechanisms that govern AID targeting and outcomes could be harnessed to elicit rare functional antibodies and develop ex vivo antibody diversification approaches with diversifying base editors.
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Affiliation(s)
- Leng-Siew Yeap
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
| | - Fei-Long Meng
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China.
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19
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Schuhmacher B, Bein J, Rausch T, Benes V, Tousseyn T, Vornanen M, Ponzoni M, Thurner L, Gascoyne R, Steidl C, Küppers R, Hansmann ML, Hartmann S. JUNB, DUSP2, SGK1, SOCS1 and CREBBP are frequently mutated in T-cell/histiocyte-rich large B-cell lymphoma. Haematologica 2018; 104:330-337. [PMID: 30213827 PMCID: PMC6355500 DOI: 10.3324/haematol.2018.203224] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 09/07/2018] [Indexed: 12/24/2022] Open
Abstract
T-cell/histiocyte-rich large B-cell lymphoma is a rare aggressive lymphoma showing histopathological overlap with nodular lymphocyte-predominant Hodgkin lymphoma. Despite differences in tumor microenvironment and clinical behavior, the tumor cells of both entities show remarkable similarities, suggesting that both lymphomas might represent a spectrum of the same disease. To address this issue, we investigated whether these entities share mutations. Ultra-deep targeted resequencing of six typical and 11 histopathological variants of nodular lymphocyte-predominant Hodgkin lymphoma, and nine cases of T-cell/histiocyte-rich large B-cell lymphoma revealed that genes recurrently mutated in nodular lymphocyte-predominant Hodgkin lymphoma are affected by mutations at similar frequencies in T-cell/histiocyte-rich large B-cell lymphoma. The most recurrently mutated genes were JUNB, DUSP2, SGK1, SOCS1 and CREBBP, which harbored mutations more frequently in T-cell/histiocyte-rich large B-cell lymphoma and the histopathological variants of nodular lymphocyte-predominant Hodgkin lymphoma than in its typical form. Mutations in JUNB, DUSP2, SGK1 and SOCS1 were highly enriched for somatic hypermutation hotspot sites, suggesting an important role of aberrant somatic hypermutation in the generation of these somatic mutations and thus in the pathogenesis of both lymphoma entities. Mutations in JUNB are generally rarely observed in malignant lymphomas and thus are relatively specific for nodular lymphocyte-predominant Hodgkin lymphoma and T-cell/histiocyte-rich large B-cell lymphoma at such high frequencies (5/17 and 5/9 cases with JUNB mutations, respectively). Taken together, the findings of the present study further support a close relationship between T-cell/histiocyte-rich large B-cell lymphoma and nodular lymphocyte-predominant Hodgkin lymphoma by showing that they share highly recurrent genetic lesions.
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Affiliation(s)
- Bianca Schuhmacher
- Dr. Senckenberg Institute of Pathology, Goethe University, Frankfurt am Main, Germany
| | - Julia Bein
- Dr. Senckenberg Institute of Pathology, Goethe University, Frankfurt am Main, Germany
| | - Tobias Rausch
- Genecore, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany.,Genome Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Vladimir Benes
- Genecore, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Thomas Tousseyn
- Department of Pathology, University Hospitals K.U. Leuven, Belgium
| | - Martine Vornanen
- Department of Pathology, Tampere University Hospital and University of Tampere, Finland
| | - Maurilio Ponzoni
- Unit of Lymphoid Malignancies, Department of Pathology, Scientific Institute San Raffaele, Milan, Italy
| | - Lorenz Thurner
- José Carreras Center for Immuno and Gene Therapy and Internal Medicine I, Saarland University Medical School, Homburg, Saar, Germany.,Department of Internal Medicine 2, Hospital of the J. W. Goethe University, Frankfurt am Main, Germany
| | - Randy Gascoyne
- Department of Pathology and Laboratory Medicine and the Centre for Lymphoid Cancer, British Columbia Cancer Agency, University of British Columbia, Vancouver, Canada
| | - Christian Steidl
- Department of Pathology and Laboratory Medicine and the Centre for Lymphoid Cancer, British Columbia Cancer Agency, University of British Columbia, Vancouver, Canada
| | - Ralf Küppers
- Institute of Cell Biology (Cancer Research), Faculty of Medicine, University of Duisburg-Essen, Essen, Germany.,Deutsches Konsortium für Translationale Krebsforschung (DKTK), Germany
| | - Martin-Leo Hansmann
- Dr. Senckenberg Institute of Pathology, Goethe University, Frankfurt am Main, Germany.,Reference and Consultant Center for Lymphoma and Lymph Node Diagnostics, Goethe University, Frankfurt am Main, Germany.,Frankfurt Institute of Advanced Studies, Frankfurt am Main, Germany
| | - Sylvia Hartmann
- Dr. Senckenberg Institute of Pathology, Goethe University, Frankfurt am Main, Germany .,Reference and Consultant Center for Lymphoma and Lymph Node Diagnostics, Goethe University, Frankfurt am Main, Germany
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20
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Ribeiro de Almeida C, Dhir S, Dhir A, Moghaddam AE, Sattentau Q, Meinhart A, Proudfoot NJ. RNA Helicase DDX1 Converts RNA G-Quadruplex Structures into R-Loops to Promote IgH Class Switch Recombination. Mol Cell 2018; 70:650-662.e8. [PMID: 29731414 PMCID: PMC5971202 DOI: 10.1016/j.molcel.2018.04.001] [Citation(s) in RCA: 113] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 03/02/2018] [Accepted: 03/30/2018] [Indexed: 12/20/2022]
Abstract
Class switch recombination (CSR) at the immunoglobulin heavy-chain (IgH) locus is associated with the formation of R-loop structures over switch (S) regions. While these often occur co-transcriptionally between nascent RNA and template DNA, we now show that they also form as part of a post-transcriptional mechanism targeting AID to IgH S-regions. This depends on the RNA helicase DDX1 that is also required for CSR in vivo. DDX1 binds to G-quadruplex (G4) structures present in intronic switch transcripts and converts them into S-region R-loops. This in turn targets the cytidine deaminase enzyme AID to S-regions so promoting CSR. Notably R-loop levels over S-regions are diminished by chemical stabilization of G4 RNA or by the expression of a DDX1 ATPase-deficient mutant that acts as a dominant-negative protein to reduce CSR efficiency. In effect, we provide evidence for how S-region transcripts interconvert between G4 and R-loop structures to promote CSR in the IgH locus.
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Affiliation(s)
| | - Somdutta Dhir
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, OX1 3RE Oxford, UK
| | - Ashish Dhir
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, OX1 3RE Oxford, UK
| | - Amin E Moghaddam
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, OX1 3RE Oxford, UK
| | - Quentin Sattentau
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, OX1 3RE Oxford, UK
| | - Anton Meinhart
- Department of Biomolecular Mechanisms, Max-Planck-Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - Nicholas J Proudfoot
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, OX1 3RE Oxford, UK.
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21
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Caldwell RB, Braselmann H, Heuer S, Schötz U, Zitzelsberger H. Gain-of-function analysis of cis-acting diversification elements in DT40 cells. Immunol Cell Biol 2018; 96:948-957. [PMID: 29665088 DOI: 10.1111/imcb.12158] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 04/09/2018] [Accepted: 04/09/2018] [Indexed: 02/02/2023]
Abstract
Activation-induced cytidine deaminase (AID) is required for the immunoglobulin diversification processes of somatic hypermutation, gene conversion and class-switch recombination. The targeting of AID's deamination activity is thought to be a combination of cis- and trans-acting elements, but has not been fully elucidated. Deletion analysis of putative proximal cis-regulatory motifs, while helpful, fails to identify additive versus cumulative effects, redundancy, and may create new motifs where none previously existed. In contrast, gain-of-function analysis can be more insightful with fewer of the same drawbacks and the output is a positive result. Here, we show five defined DNA regions of the avian Igλ locus that are sufficient to confer events of hypermutation to a target gene. In our analysis, the essential cis-targeting elements fully reconstituted diversification of a transgene under heterologous promotion in the avian B-cell line DT40. Furthermore, to the best of our knowledge two of the five regions we report on here have not previously been described as individually having an influence on somatic hypermutation.
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Affiliation(s)
- Randolph B Caldwell
- Department of Radiation Sciences - Research Unit Radiation Cytogenetics, Helmholtz Center Munich - German Research Center for Environmental Health (GmbH), Neuherberg, 85764, Germany
| | - Herbert Braselmann
- Department of Radiation Sciences - Research Unit Radiation Cytogenetics, Helmholtz Center Munich - German Research Center for Environmental Health (GmbH), Neuherberg, 85764, Germany
| | - Steffen Heuer
- Department of Radiation Sciences - Research Unit Radiation Cytogenetics, Helmholtz Center Munich - German Research Center for Environmental Health (GmbH), Neuherberg, 85764, Germany
| | - Ulrike Schötz
- Department of Radiotherapy and Radiooncology, Philipps-University Marburg, University Hospital Gießen and Marburg, Marburg, 35043, Germany
| | - Horst Zitzelsberger
- Department of Radiation Sciences - Research Unit Radiation Cytogenetics, Helmholtz Center Munich - German Research Center for Environmental Health (GmbH), Neuherberg, 85764, Germany.,Helmholtz Center Munich, Clinical Cooperation Group 'Personalized Radiotherapy of Head and Neck Cancer', Neuherberg, 85764, Germany.,Department of Radiotherapy and Radiation Oncology, Ludwig-Maximilians-Universitaet, University Hospital Munich, Munich, 81377, Germany
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22
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Álvarez-Prado ÁF, Pérez-Durán P, Pérez-García A, Benguria A, Torroja C, de Yébenes VG, Ramiro AR. A broad atlas of somatic hypermutation allows prediction of activation-induced deaminase targets. J Exp Med 2018; 215:761-771. [PMID: 29374026 PMCID: PMC5839764 DOI: 10.1084/jem.20171738] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 11/22/2017] [Accepted: 12/21/2017] [Indexed: 12/18/2022] Open
Abstract
Activation-induced deaminase (AID) initiates antibody diversification in germinal center (GC) B cells through the deamination of cytosines on immunoglobulin genes. AID can also target other regions in the genome, triggering mutations or chromosome translocations, with major implications for oncogenic transformation. However, understanding the specificity of AID has proved extremely challenging. We have sequenced at very high depth >1,500 genomic regions from GC B cells and identified 275 genes targeted by AID, including 30 of the previously known 35 AID targets. We have also identified the most highly mutated hotspot for AID activity described to date. Furthermore, integrative analysis of the molecular features of mutated genes coupled to machine learning has produced a powerful predictive tool for AID targets. We also have found that base excision repair and mismatch repair back up each other to faithfully repair AID-induced lesions. Finally, our data establish a novel link between AID mutagenic activity and lymphomagenesis.
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Affiliation(s)
- Ángel F Álvarez-Prado
- B Cell Biology Lab, Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain
| | - Pablo Pérez-Durán
- B Cell Biology Lab, Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain
| | - Arantxa Pérez-García
- B Cell Biology Lab, Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain
| | - Alberto Benguria
- Genomics Unit, Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain
| | - Carlos Torroja
- Bioinformatics Unit, Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain
| | - Virginia G de Yébenes
- B Cell Biology Lab, Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain
| | - Almudena R Ramiro
- B Cell Biology Lab, Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain
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23
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Boulianne B, Feldhahn N. Transcribing malignancy: transcription-associated genomic instability in cancer. Oncogene 2017; 37:971-981. [DOI: 10.1038/onc.2017.402] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 09/12/2017] [Accepted: 09/12/2017] [Indexed: 12/17/2022]
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24
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Chromatin reorganisation in Epstein-Barr virus-infected cells and its role in cancer development. Curr Opin Virol 2017; 26:149-155. [DOI: 10.1016/j.coviro.2017.08.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 08/07/2017] [Accepted: 08/17/2017] [Indexed: 11/23/2022]
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25
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Supek F, Lehner B. Clustered Mutation Signatures Reveal that Error-Prone DNA Repair Targets Mutations to Active Genes. Cell 2017; 170:534-547.e23. [PMID: 28753428 DOI: 10.1016/j.cell.2017.07.003] [Citation(s) in RCA: 120] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 05/17/2017] [Accepted: 07/05/2017] [Indexed: 02/07/2023]
Abstract
Many processes can cause the same nucleotide change in a genome, making the identification of the mechanisms causing mutations a difficult challenge. Here, we show that clustered mutations provide a more precise fingerprint of mutagenic processes. Of nine clustered mutation signatures identified from >1,000 tumor genomes, three relate to variable APOBEC activity and three are associated with tobacco smoking. An additional signature matches the spectrum of translesion DNA polymerase eta (POLH). In lymphoid cells, these mutations target promoters, consistent with AID-initiated somatic hypermutation. In solid tumors, however, they are associated with UV exposure and alcohol consumption and target the H3K36me3 chromatin of active genes in a mismatch repair (MMR)-dependent manner. These regions normally have a low mutation rate because error-free MMR also targets H3K36me3 chromatin. Carcinogens and error-prone repair therefore redistribute mutations to the more important regions of the genome, contributing a substantial mutation load in many tumors, including driver mutations.
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Affiliation(s)
- Fran Supek
- EMBL-CRG Systems Biology Unit, Centre for Genomic Regulation (CRG), the Barcelona Institute of Science and Technology, 08003 Barcelona, Spain; Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain; Division of Electronics, Rudjer Boskovic Institute, 10000 Zagreb, Croatia
| | - Ben Lehner
- EMBL-CRG Systems Biology Unit, Centre for Genomic Regulation (CRG), the Barcelona Institute of Science and Technology, 08003 Barcelona, Spain; Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain.
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26
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Rommel PC, Oliveira TY, Nussenzweig MC, Robbiani DF. RAG1/2 induces genomic insertions by mobilizing DNA into RAG1/2-independent breaks. J Exp Med 2017; 214:815-831. [PMID: 28179379 PMCID: PMC5339680 DOI: 10.1084/jem.20161638] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 11/09/2016] [Accepted: 12/12/2016] [Indexed: 11/23/2022] Open
Abstract
Rommel et al. reveal a novel RAG1/2-mediated insertion pathway, which has the potential to destabilize the lymphocyte genome and shares features with DNA insertions observed in human cancer. The RAG recombinase (RAG1/2) plays an essential role in adaptive immunity by mediating V(D)J recombination in developing lymphocytes. In contrast, aberrant RAG1/2 activity promotes lymphocyte malignancies by causing chromosomal translocations and DNA deletions at cancer genes. RAG1/2 can also induce genomic DNA insertions by transposition and trans-V(D)J recombination, but only few such putative events have been documented in vivo. We used next-generation sequencing techniques to examine chromosomal rearrangements in primary murine B cells and discovered that RAG1/2 causes aberrant insertions by releasing cleaved antibody gene fragments that subsequently reintegrate into DNA breaks induced on a heterologous chromosome. We confirmed that RAG1/2 also mobilizes genomic DNA into independent physiological breaks by identifying similar insertions in human lymphoma and leukemia. Our findings reveal a novel RAG1/2-mediated insertion pathway distinct from DNA transposition and trans-V(D)J recombination that destabilizes the genome and shares features with reported oncogenic DNA insertions.
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Affiliation(s)
- Philipp C Rommel
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065
| | - Thiago Y Oliveira
- 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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27
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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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Abstract
PURPOSE OF REVIEW Aggressive transformation, a frequent event in the natural history of follicular lymphoma, is associated with increased lymphoma-related mortality and yet the underlying biology remains poorly defined. This review outlines recent advances in our understanding of the genetic basis and evolutionary process leading to transformation. RECENT FINDINGS Both the antecedent indolent and transformed follicular lymphoma (tFL) arise through branched divergent evolution with tumors emerging from a founder precursor population, the common progenitor cell. Although the majority of tFLs maintain a germinal center B-cell gene expression signature, an activated B-cell-type (ABC-type) profile appears to predominate in BCL2-translocation negative cases. It does not appear that a single unifying genetic or epigenetic event promotes a fitter and more aggressive clone. SUMMARY Transformed follicular tumors are genetically heterogeneous perhaps reflecting the varying clinical behavior and outcomes of this disease event. Follicular lymphoma and tFL remain incurable tumors highlighted by our inability to eradicate the founder common progenitor cell population with current therapies. Progress has now been made in defining the genetic events and evolutionary pathways responsible for transformation. Although more research is required in predicting and understanding the biology of transformation, there are opportunities to improve outcomes by preferentially directing targeted therapies toward 'actionable' early and transformation-specific aberrations.
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Affiliation(s)
- Jessica Okosun
- aCentre for Haemato-Oncology, Barts Cancer Institute bDepartment of Haemato-oncology, St Bartholomew's Hospital, Barts Health NHS Trust, London, UK
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29
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Romanello M, Schiavone D, Frey A, Sale JE. Histone H3.3 promotes IgV gene diversification by enhancing formation of AID-accessible single-stranded DNA. EMBO J 2016; 35:1452-64. [PMID: 27220848 PMCID: PMC4883027 DOI: 10.15252/embj.201693958] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 04/25/2016] [Indexed: 11/30/2022] Open
Abstract
Immunoglobulin diversification is driven by activation‐induced deaminase (AID), which converts cytidine to uracil within the Ig variable (IgV) regions. Central to the recruitment of AID to the IgV genes are factors that regulate the generation of single‐stranded DNA (ssDNA), the enzymatic substrate of AID. Here, we report that chicken DT40 cells lacking variant histone H3.3 exhibit reduced IgV sequence diversification. We show that this results from impairment of the ability of AID to access the IgV genes due to reduced formation of ssDNA during IgV transcription. Loss of H3.3 also diminishes IgV R‐loop formation. However, reducing IgV R‐loops by RNase HI overexpression in wild‐type cells does not affect IgV diversification, showing that these structures are not necessary intermediates for AID access. Importantly, the reduction in the formation of AID‐accessible ssDNA in cells lacking H3.3 is independent of any effect on the level of transcription or the kinetics of RNAPII elongation, suggesting the presence of H3.3 in the nucleosomes of the IgV genes increases the chances of the IgV DNA becoming single‐stranded, thereby creating an effective AID substrate.
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Affiliation(s)
- Marina Romanello
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Davide Schiavone
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Alexander Frey
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Julian E Sale
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
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30
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Polevoda B, McDougall WM, Bennett RP, Salter JD, Smith HC. Structural and functional assessment of APOBEC3G macromolecular complexes. Methods 2016; 107:10-22. [PMID: 26988126 DOI: 10.1016/j.ymeth.2016.03.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 03/10/2016] [Accepted: 03/11/2016] [Indexed: 12/20/2022] Open
Abstract
There are eleven members in the human APOBEC family of proteins that are evolutionarily related through their zinc-dependent cytidine deaminase domains. The human APOBEC gene clusters arose on chromosome 6 and 22 through gene duplication and divergence to where current day APOBEC proteins are functionally diverse and broadly expressed in tissues. APOBEC serve enzymatic and non enzymatic functions in cells. In both cases, formation of higher-order structures driven by APOBEC protein-protein interactions and binding to RNA and/or single stranded DNA are integral to their function. In some circumstances, these interactions are regulatory and modulate APOBEC activities. We are just beginning to understand how macromolecular interactions drive processes such as APOBEC subcellular compartmentalization, formation of holoenzyme complexes, gene targeting, foreign DNA restriction, anti-retroviral activity, formation of ribonucleoprotein particles and APOBEC degradation. Protein-protein and protein-nucleic acid cross-linking methods coupled with mass spectrometry, electrophoretic mobility shift assays, glycerol gradient sedimentation, fluorescence anisotropy and APOBEC deaminase assays are enabling mapping of interacting surfaces that are essential for these functions. The goal of this methods review is through example of our research on APOBEC3G, describe the application of cross-linking methods to characterize and quantify macromolecular interactions and their functional implications. Given the homology in structure and function, it is proposed that these methods will be generally applicable to the discovery process for other APOBEC and RNA and DNA editing and modifying proteins.
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Affiliation(s)
- Bogdan Polevoda
- Department of Biochemistry and Biophysics, University of Rochester, School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | - William M McDougall
- Department of Biochemistry and Biophysics, University of Rochester, School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | - Ryan P Bennett
- OyaGen, Inc, Rochester BioVenture Center, 77 Ridgeland Road, Rochester, NY 14623, USA
| | - Jason D Salter
- OyaGen, Inc, Rochester BioVenture Center, 77 Ridgeland Road, Rochester, NY 14623, USA
| | - Harold C Smith
- Department of Biochemistry and Biophysics, University of Rochester, School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA; Wilmot Cancer Institute, 601 Elmwood Avenue, Rochester, NY 14642, USA; Center for RNA Biology, 601 Elmwood Avenue, Rochester, NY 14642, USA; OyaGen, Inc, Rochester BioVenture Center, 77 Ridgeland Road, Rochester, NY 14623, USA; Center for AIDS Research, 601 Elmwood Avenue, Rochester, NY 14642, USA.
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31
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Thomas-Claudepierre AS, Robert I, Rocha PP, Raviram R, Schiavo E, Heyer V, Bonneau R, Luo VM, Reddy JK, Borggrefe T, Skok JA, Reina-San-Martin B. Mediator facilitates transcriptional activation and dynamic long-range contacts at the IgH locus during class switch recombination. J Exp Med 2016; 213:303-12. [PMID: 26903242 PMCID: PMC4813673 DOI: 10.1084/jem.20141967] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 01/15/2016] [Indexed: 12/21/2022] Open
Abstract
Thomas-Claudepierre et al. report that mediator facilitates the long-range contacts between acceptor switch regions and the IgH locus enhancers during class switch recombination and their transcriptional activation. Immunoglobulin (Ig) class switch recombination (CSR) is initiated by the transcription-coupled recruitment of activation-induced cytidine deaminase (AID) to Ig switch regions (S regions). During CSR, the IgH locus undergoes dynamic three-dimensional structural changes in which promoters, enhancers, and S regions are brought to close proximity. Nevertheless, little is known about the underlying mechanisms. In this study, we show that Med1 and Med12, two subunits of the mediator complex implicated in transcription initiation and long-range enhancer/promoter loop formation, are dynamically recruited to the IgH locus enhancers and the acceptor regions during CSR and that their knockdown in CH12 cells results in impaired CSR. Furthermore, we show that conditional inactivation of Med1 in B cells results in defective CSR and reduced acceptor S region transcription. Finally, we show that in B cells undergoing CSR, the dynamic long-range contacts between the IgH enhancers and the acceptor regions correlate with Med1 and Med12 binding and that they happen at a reduced frequency in Med1-deficient B cells. Our results implicate the mediator complex in the mechanism of CSR and are consistent with a model in which mediator facilitates the long-range contacts between S regions and the IgH locus enhancers during CSR and their transcriptional activation.
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Affiliation(s)
- Anne-Sophie Thomas-Claudepierre
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67400 Illkirch, France Institut National de la Santé et de la Recherche Médicale, Unité 964, 67404 Illkirch, France Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7104, 67404 Illkirch, France Université de Strasbourg, 67400 Illkirch, France
| | - Isabelle Robert
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67400 Illkirch, France Institut National de la Santé et de la Recherche Médicale, Unité 964, 67404 Illkirch, France Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7104, 67404 Illkirch, France Université de Strasbourg, 67400 Illkirch, France
| | - Pedro P Rocha
- Department of Pathology, School of Medicine, New York University, New York, NY 10003
| | - Ramya Raviram
- Department of Pathology, School of Medicine, New York University, New York, NY 10003 Department of Biology, New York University, New York, NY 10003
| | - Ebe Schiavo
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67400 Illkirch, France Institut National de la Santé et de la Recherche Médicale, Unité 964, 67404 Illkirch, France Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7104, 67404 Illkirch, France Université de Strasbourg, 67400 Illkirch, France
| | - Vincent Heyer
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67400 Illkirch, France Institut National de la Santé et de la Recherche Médicale, Unité 964, 67404 Illkirch, France Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7104, 67404 Illkirch, France Université de Strasbourg, 67400 Illkirch, France
| | - Richard Bonneau
- Department of Biology, New York University, New York, NY 10003 Department of Computer Science, Courant Institute of Mathematical Sciences, New York, NY 10003 Simons Center for Data Analysis, New York, NY 10010
| | - Vincent M Luo
- Department of Pathology, School of Medicine, New York University, New York, NY 10003 Department of Biology, New York University, New York, NY 10003
| | - Janardan K Reddy
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60208
| | | | - Jane A Skok
- Department of Pathology, School of Medicine, New York University, New York, NY 10003 New York University Cancer Institute, New York University, New York, NY 10003
| | - Bernardo Reina-San-Martin
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67400 Illkirch, France Institut National de la Santé et de la Recherche Médicale, Unité 964, 67404 Illkirch, France Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7104, 67404 Illkirch, France Université de Strasbourg, 67400 Illkirch, France
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32
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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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33
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Zanotti KJ, Gearhart PJ. Antibody diversification caused by disrupted mismatch repair and promiscuous DNA polymerases. DNA Repair (Amst) 2016; 38:110-116. [PMID: 26719140 PMCID: PMC4740194 DOI: 10.1016/j.dnarep.2015.11.011] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 11/30/2015] [Indexed: 10/25/2022]
Abstract
The enzyme activation-induced deaminase (AID) targets the immunoglobulin loci in activated B cells and creates DNA mutations in the antigen-binding variable region and DNA breaks in the switch region through processes known, respectively, as somatic hypermutation and class switch recombination. AID deaminates cytosine to uracil in DNA to create a U:G mismatch. During somatic hypermutation, the MutSα complex binds to the mismatch, and the error-prone DNA polymerase η generates mutations at A and T bases. During class switch recombination, both MutSα and MutLα complexes bind to the mismatch, resulting in double-strand break formation and end-joining. This review is centered on the mechanisms of how the MMR pathway is commandeered by B cells to generate antibody diversity.
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Affiliation(s)
- Kimberly J Zanotti
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA.
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34
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Zan H, Casali P. Epigenetics of Peripheral B-Cell Differentiation and the Antibody Response. Front Immunol 2015; 6:631. [PMID: 26697022 PMCID: PMC4677338 DOI: 10.3389/fimmu.2015.00631] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 11/30/2015] [Indexed: 12/13/2022] Open
Abstract
Epigenetic modifications, such as histone post-translational modifications, DNA methylation, and alteration of gene expression by non-coding RNAs, including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), are heritable changes that are independent from the genomic DNA sequence. These regulate gene activities and, therefore, cellular functions. Epigenetic modifications act in concert with transcription factors and play critical roles in B cell development and differentiation, thereby modulating antibody responses to foreign- and self-antigens. Upon antigen encounter by mature B cells in the periphery, alterations of these lymphocytes epigenetic landscape are induced by the same stimuli that drive the antibody response. Such alterations instruct B cells to undergo immunoglobulin (Ig) class switch DNA recombination (CSR) and somatic hypermutation (SHM), as well as differentiation to memory B cells or long-lived plasma cells for the immune memory. Inducible histone modifications, together with DNA methylation and miRNAs modulate the transcriptome, particularly the expression of activation-induced cytidine deaminase, which is essential for CSR and SHM, and factors central to plasma cell differentiation, such as B lymphocyte-induced maturation protein-1. These inducible B cell-intrinsic epigenetic marks guide the maturation of antibody responses. Combinatorial histone modifications also function as histone codes to target CSR and, possibly, SHM machinery to the Ig loci by recruiting specific adaptors that can stabilize CSR/SHM factors. In addition, lncRNAs, such as recently reported lncRNA-CSR and an lncRNA generated through transcription of the S region that form G-quadruplex structures, are also important for CSR targeting. Epigenetic dysregulation in B cells, including the aberrant expression of non-coding RNAs and alterations of histone modifications and DNA methylation, can result in aberrant antibody responses to foreign antigens, such as those on microbial pathogens, and generation of pathogenic autoantibodies, IgE in allergic reactions, as well as B cell neoplasia. Epigenetic marks would be attractive targets for new therapeutics for autoimmune and allergic diseases, and B cell malignancies.
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Affiliation(s)
- Hong Zan
- Department of Microbiology and Immunology, University of Texas School of Medicine, UT Health Science Center , San Antonio, TX , USA
| | - Paolo Casali
- Department of Microbiology and Immunology, University of Texas School of Medicine, UT Health Science Center , San Antonio, TX , USA
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35
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Vaidyanathan B, Chaudhuri J. Epigenetic Codes Programing Class Switch Recombination. Front Immunol 2015; 6:405. [PMID: 26441954 PMCID: PMC4566074 DOI: 10.3389/fimmu.2015.00405] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 07/23/2015] [Indexed: 11/22/2022] Open
Abstract
Class switch recombination imparts B cells with a fitness-associated adaptive advantage during a humoral immune response by using a precision-tailored DNA excision and ligation process to swap the default constant region gene of the antibody with a new one that has unique effector functions. This secondary diversification of the antibody repertoire is a hallmark of the adaptability of B cells when confronted with environmental and pathogenic challenges. Given that the nucleotide sequence of genes during class switching remains unchanged (genetic constraints), it is logical and necessary therefore, to integrate the adaptability of B cells to an epigenetic state, which is dynamic and can be heritably modulated before, after, or even during an antibody-dependent immune response. Epigenetic regulation encompasses heritable changes that affect function (phenotype) without altering the sequence information embedded in a gene, and include histone, DNA and RNA modifications. Here, we review current literature on how B cells use an epigenetic code language as a means to ensure antibody plasticity in light of pathogenic insults.
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Affiliation(s)
- Bharat Vaidyanathan
- Immunology and Microbial Pathogenesis Program, Weill Cornell Graduate School , New York, NY , USA ; Immunology Program, Sloan Kettering Institute , New York, NY , USA
| | - Jayanta Chaudhuri
- Immunology and Microbial Pathogenesis Program, Weill Cornell Graduate School , New York, NY , USA ; Immunology Program, Sloan Kettering Institute , New York, NY , USA
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36
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Robbiani DF, Deroubaix S, Feldhahn N, Oliveira TY, Callen E, Wang Q, Jankovic M, Silva IT, Rommel PC, Bosque D, Eisenreich T, Nussenzweig A, Nussenzweig MC. Plasmodium Infection Promotes Genomic Instability and AID-Dependent B Cell Lymphoma. Cell 2015; 162:727-37. [PMID: 26276629 PMCID: PMC4538708 DOI: 10.1016/j.cell.2015.07.019] [Citation(s) in RCA: 116] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Revised: 04/20/2015] [Accepted: 06/02/2015] [Indexed: 02/06/2023]
Abstract
Chronic infection with Plasmodium falciparum was epidemiologically associated with endemic Burkitt's lymphoma, a mature B cell cancer characterized by chromosome translocation between the c-myc oncogene and Igh, over 50 years ago. Whether infection promotes B cell lymphoma, and if so by which mechanism, remains unknown. To investigate the relationship between parasitic disease and lymphomagenesis, we used Plasmodium chabaudi (Pc) to produce chronic malaria infection in mice. Pc induces prolonged expansion of germinal centers (GCs), unique compartments in which B cells undergo rapid clonal expansion and express activation-induced cytidine deaminase (AID), a DNA mutator. GC B cells elicited during Pc infection suffer widespread DNA damage, leading to chromosome translocations. Although infection does not change the overall rate, it modifies lymphomagenesis to favor mature B cell lymphomas that are AID dependent and show chromosome translocations. Thus, malaria infection favors mature B cell cancers by eliciting protracted AID expression in GC B cells. PAPERCLIP.
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Affiliation(s)
- Davide F Robbiani
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA.
| | - Stephanie Deroubaix
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Niklas Feldhahn
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Thiago Y Oliveira
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Elsa Callen
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Qiao Wang
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Mila Jankovic
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Israel T Silva
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Philipp C Rommel
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - David Bosque
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Tom Eisenreich
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - André Nussenzweig
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Michel C Nussenzweig
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA; Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA.
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Khair L, Baker RE, Linehan EK, Schrader CE, Stavnezer J. Nbs1 ChIP-Seq Identifies Off-Target DNA Double-Strand Breaks Induced by AID in Activated Splenic B Cells. PLoS Genet 2015; 11:e1005438. [PMID: 26263206 PMCID: PMC4532491 DOI: 10.1371/journal.pgen.1005438] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 07/10/2015] [Indexed: 01/03/2023] Open
Abstract
Activation-induced cytidine deaminase (AID) is required for initiation of Ig class switch recombination (CSR) and somatic hypermutation (SHM) of antibody genes during immune responses. AID has also been shown to induce chromosomal translocations, mutations, and DNA double-strand breaks (DSBs) involving non-Ig genes in activated B cells. To determine what makes a DNA site a target for AID-induced DSBs, we identify off-target DSBs induced by AID by performing chromatin immunoprecipitation (ChIP) for Nbs1, a protein that binds DSBs, followed by deep sequencing (ChIP-Seq). We detect and characterize hundreds of off-target AID-dependent DSBs. Two types of tandem repeats are highly enriched within the Nbs1-binding sites: long CA repeats, which can form Z-DNA, and tandem pentamers containing the AID target hotspot WGCW. These tandem repeats are not nearly as enriched at AID-independent DSBs, which we also identified. Msh2, a component of the mismatch repair pathway and important for genome stability, increases off-target DSBs, similar to its effect on Ig switch region DSBs, which are required intermediates during CSR. Most of the off-target DSBs are two-ended, consistent with generation during G1 phase, similar to DSBs in Ig switch regions. However, a minority are one-ended, presumably due to conversion of single-strand breaks to DSBs during replication. One-ended DSBs are repaired by processes involving homologous recombination, including break-induced replication repair, which can lead to genome instability. Off-target DSBs, especially those present during S phase, can lead to chromosomal translocations, deletions and gene amplifications, resulting in the high frequency of B cell lymphomas derived from cells that express or have expressed AID. Activation-induced cytidine deaminase (AID) is required for diversifying antibodies during immune responses, and it does this by introducing mutations and DNA breaks into antibody genes. How AID is targeted is not understood, and it induces chromosomal translocations, mutations, and double-strand breaks (DSBs) at sites other than antibody genes in activated B cells. To determine what makes an off-target DNA site a target for AID-induced DSBs, we identify and characterize hundreds of genome-wide DSBs induced by AID during B cell activation. Interestingly, many of the DSBs are within or adjacent to two types of tandemly repeated simple sequences, which have characteristics that might explain why they are targeted. We find that most of the DSBs are two-ended, consistent with their generation during G1 phase of the cell cycle, which is when AID induces DNA breaks in antibody genes. However, a minority is one-ended, consistent with replication encountering an AID-induced single-strand break, thereby creating a DSB. Both types of off-target DSBs, but especially those present during S phase of the cell cycle, lead to chromosomal translocations, deletions and gene amplifications that can promote B cell lymphomagenesis.
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Affiliation(s)
- Lyne Khair
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Richard E. Baker
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Erin K. Linehan
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Carol E. Schrader
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Janet Stavnezer
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- * E-mail:
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Chandra V, Bortnick A, Murre C. AID targeting: old mysteries and new challenges. Trends Immunol 2015; 36:527-35. [PMID: 26254147 DOI: 10.1016/j.it.2015.07.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 07/14/2015] [Accepted: 07/14/2015] [Indexed: 01/09/2023]
Abstract
Activation-induced cytidine deaminase (AID) mediates cytosine deamination and underlies two central processes in antibody diversification: somatic hypermutation and class-switch recombination. AID deamination is not exclusive to immunoglobulin loci; it can instigate DNA lesions in non-immunoglobulin genes and thus stringent checks are in place to constrain and restrict its activity. Recent findings have provided new insights into the mechanisms that target AID activity to specific genomic regions, revealing an involvement for noncoding RNAs associated with polymerase pausing and with enhancer transcription as well as genomic architecture. We review these findings and integrate them into a model for multilevel regulation of AID expression and targeting in immunoglobulin and non-immunoglobulin loci. Within this framework we discuss gaps in understanding, and outline important areas of further research.
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Affiliation(s)
- Vivek Chandra
- Department of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0377, USA
| | - Alexandra Bortnick
- Department of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0377, USA
| | - Cornelis Murre
- Department of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093-0377, USA.
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Blombery PA, Wall M, Seymour JF. The molecular pathogenesis of B-cell non-Hodgkin lymphoma. Eur J Haematol 2015; 95:280-93. [DOI: 10.1111/ejh.12589] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/18/2015] [Indexed: 12/17/2022]
Affiliation(s)
| | - Meaghan Wall
- Victorian Cancer Cytogenetics Service; St Vincent's Hospital Melbourne; University of Melbourne; Fitzroy Vic. Australia
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Abstract
The immunoglobulin diversification processes of somatic hypermutation and class switch recombination critically rely on transcription-coupled targeting of activation-induced cytidine deaminase (AID) to Ig loci in activated B lymphocytes. AID catalyzes deamination of cytidine deoxynucleotides on exposed single-stranded DNA. In addition to driving immunoglobulin diversity, promiscuous targeting of AID mutagenic activity poses a deleterious threat to genomic stability. Recent genome-wide studies have uncovered pervasive AID activity throughout the B cell genome. It is increasingly apparent that AID activity is frequently targeted to genomic loci undergoing early transcription termination where RNA exosome promotes the resolution of stalled transcription complexes via cotranscriptional RNA degradation mechanisms. Here, we review aspects and consequences of eukaryotic transcription that lead to early termination, RNA exosome recruitment, and ultimately targeting of AID mutagenic activity.
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Affiliation(s)
- Evangelos Pefanis
- Department of Microbiology & Immunology, College of Physicians and Surgeons, Columbia University, New York, USA.
| | - Uttiya Basu
- Department of Microbiology & Immunology, College of Physicians and Surgeons, Columbia University, New York, USA.
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Disruption of Transcriptional Coactivator Sub1 Leads to Genome-Wide Re-distribution of Clustered Mutations Induced by APOBEC in Active Yeast Genes. PLoS Genet 2015; 11:e1005217. [PMID: 25941824 PMCID: PMC4420506 DOI: 10.1371/journal.pgen.1005217] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 04/13/2015] [Indexed: 12/21/2022] Open
Abstract
Mutations in genomes of species are frequently distributed non-randomly, resulting in mutation clusters, including recently discovered kataegis in tumors. DNA editing deaminases play the prominent role in the etiology of these mutations. To gain insight into the enigmatic mechanisms of localized hypermutagenesis that lead to cluster formation, we analyzed the mutational single nucleotide variations (SNV) data obtained by whole-genome sequencing of drug-resistant mutants induced in yeast diploids by AID/APOBEC deaminase and base analog 6-HAP. Deaminase from sea lamprey, PmCDA1, induced robust clusters, while 6-HAP induced a few weak ones. We found that PmCDA1, AID, and APOBEC1 deaminases preferentially mutate the beginning of the actively transcribed genes. Inactivation of transcription initiation factor Sub1 strongly reduced deaminase-induced can1 mutation frequency, but, surprisingly, did not decrease the total SNV load in genomes. However, the SNVs in the genomes of the sub1 clones were re-distributed, and the effect of mutation clustering in the regions of transcription initiation was even more pronounced. At the same time, the mutation density in the protein-coding regions was reduced, resulting in the decrease of phenotypically detected mutants. We propose that the induction of clustered mutations by deaminases involves: a) the exposure of ssDNA strands during transcription and loss of protection of ssDNA due to the depletion of ssDNA-binding proteins, such as Sub1, and b) attainment of conditions favorable for APOBEC action in subpopulation of cells, leading to enzymatic deamination within the currently expressed genes. This model is applicable to both the initial and the later stages of oncogenic transformation and explains variations in the distribution of mutations and kataegis events in different tumor cells. Genomes of tumors are heavily enriched with mutations. Some of these mutations are distributed non-randomly, forming mutational clusters. Editing cytosine deaminases from APOBEC superfamily are responsible for the formation of many of these clusters. We have expressed APOBEC enzyme in diploid yeast cells and found that most of the mutations occur in the beginning of the active genes, where transcription starts. Clusters of mutations overlapped with promoters/transcription start sites. This is likely due to the weaker protection of ssDNA, an ultimate APOBEC deaminase enzyme target, in the beginning of the genes. This hypothesis was reinforced by the finding that inactivation of Sub1 transcription initiation factor, which is found predominantly in the regions of transcription initiation, leads to further increase in mutagenesis in the beginning of the genes. Interestingly, the total number of mutations in the genomes of Sub1-deficient clones did not change, despite the 100-fold decrease in frequency of mutants in a reporter gene. Thus, the drastic change in genome-wide distribution of mutations can be caused by inactivation of a single gene. We propose that the loss of ssDNA protection factors causes formation of mutation clusters in human cancer.
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