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Qin Y, Meng FL. Taming AID mutator activity in somatic hypermutation. Trends Biochem Sci 2024:S0968-0004(24)00077-X. [PMID: 38614818 DOI: 10.1016/j.tibs.2024.03.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2023] [Revised: 03/05/2024] [Accepted: 03/19/2024] [Indexed: 04/15/2024]
Abstract
Activation-induced cytidine deaminase (AID) initiates somatic hypermutation (SHM) by introducing base substitutions into antibody genes, a process enabling antibody affinity maturation in immune response. How a mutator is tamed to precisely and safely generate programmed DNA lesions in a physiological process remains unsettled, as its dysregulation drives lymphomagenesis. Recent research has revealed several hidden features of AID-initiated mutagenesis: preferential activity on flexible DNA substrates, restrained activity within chromatin loop domains, unique DNA repair factors to differentially decode AID-caused lesions, and diverse consequences of aberrant deamination. Here, we depict the multifaceted regulation of AID activity with a focus on emerging concepts/factors and discuss their implications for the design of base editors (BEs) that install somatic mutations to correct deleterious genomic variants.
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Affiliation(s)
- Yining Qin
- Key Laboratory of RNA Science and Engineering, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences; Shanghai 200031, China
| | - Fei-Long Meng
- Key Laboratory of RNA Science and Engineering, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences; Shanghai 200031, China.
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2
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Lauring MC, Basu U. Somatic hypermutation mechanisms during lymphomagenesis and transformation. Curr Opin Genet Dev 2024; 85:102165. [PMID: 38428317 DOI: 10.1016/j.gde.2024.102165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 01/31/2024] [Accepted: 02/02/2024] [Indexed: 03/03/2024]
Abstract
B cells undergoing physiologically programmed or aberrant genomic alterations provide an opportune system to study the causes and consequences of genome mutagenesis. Activated B cells in germinal centers express activation-induced cytidine deaminase (AID) to accomplish physiological somatic hypermutation (SHM) of their antibody-encoding genes. In attempting to diversify their immunoglobulin (Ig) heavy- and light-chain genes, several B-cell clones successfully optimize their antigen-binding affinities. However, SHM can sometimes occur at non-Ig loci, causing genetic alternations that lay the foundation for lymphomagenesis, particularly diffuse large B-cell lymphoma. Thus, SHM acts as a double-edged sword, bestowing superb humoral immunity at the potential risk of initiating disease. We refer to off-target, non-Ig AID mutations - that are often but not always associated with disease - as aberrant SHM (aSHM). A key challenge in understanding SHM and aSHM is determining how AID targets and mutates specific DNA sequences in the Ig loci to generate antibody diversity and non-Ig genes to initiate lymphomagenesis. Herein, we discuss some current advances regarding the regulation of AID's DNA mutagenesis activity in B cells.
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Affiliation(s)
- Max C Lauring
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York 10032, USA.
| | - Uttiya Basu
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York 10032, USA.
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3
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Bahat A, Itzhaki E, Weiss B, Tolmasov M, Tsoory M, Kuperman Y, Brandis A, Shurrush KA, Dikstein R. Lowering mutant huntingtin by small molecules relieves Huntington's disease symptoms and progression. EMBO Mol Med 2024; 16:523-546. [PMID: 38374466 PMCID: PMC10940305 DOI: 10.1038/s44321-023-00020-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 11/21/2023] [Accepted: 12/07/2023] [Indexed: 02/21/2024] Open
Abstract
Huntington's disease (HD) is an incurable inherited disorder caused by a repeated expansion of glutamines in the huntingtin gene (Htt). The mutant protein causes neuronal degeneration leading to severe motor and psychological symptoms. Selective downregulation of the mutant Htt gene expression is considered the most promising therapeutic approach for HD. We report the identification of small molecule inhibitors of Spt5-Pol II, SPI-24 and SPI-77, which selectively lower mutant Htt mRNA and protein levels in HD cells. In the BACHD mouse model, their direct delivery to the striatum diminished mutant Htt levels, ameliorated mitochondrial dysfunction, restored BDNF expression, and improved motor and anxiety-like phenotypes. Pharmacokinetic studies revealed that these SPIs pass the blood-brain-barrier. Prolonged subcutaneous injection or oral administration to early-stage mice significantly delayed disease deterioration. SPI-24 long-term treatment had no side effects or global changes in gene expression. Thus, lowering mutant Htt levels by small molecules can be an effective therapeutic strategy for HD.
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Affiliation(s)
- Anat Bahat
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, 76100, Israel.
| | - Elad Itzhaki
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Benjamin Weiss
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Michael Tolmasov
- The Mina & Everard Goodman Faculty of Life-Sciences and The Leslie & Susan Gonda Multidisciplinary Brain Research Center Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Michael Tsoory
- Department of Veterinary Resources, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Yael Kuperman
- Department of Veterinary Resources, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Alexander Brandis
- Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Khriesto A Shurrush
- The Nancy and Stephen Grand Israel National Center for Personalized Medicine, The Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Rivka Dikstein
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, 76100, Israel.
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Weischedel J, Higgins L, Rogers S, Gramalla-Schmitz A, Wyrzykowska P, Borgoni S, MacCarthy T, Chahwan R. Modular cytosine base editing promotes epigenomic and genomic modifications. Nucleic Acids Res 2024; 52:e8. [PMID: 37994786 PMCID: PMC10810192 DOI: 10.1093/nar/gkad1118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 10/06/2023] [Accepted: 11/06/2023] [Indexed: 11/24/2023] Open
Abstract
Prokaryotic and eukaryotic adaptive immunity differ considerably. Yet, their fundamental mechanisms of gene editing via Cas9 and activation-induced deaminase (AID), respectively, can be conveniently complimentary. Cas9 is an RNA targeted dual nuclease expressed in several bacterial species. AID is a cytosine deaminase expressed in germinal centre B cells to mediate genomic antibody diversification. AID can also mediate epigenomic reprogramming via active DNA demethylation. It is known that sequence motifs, nucleic acid structures, and associated co-factors affect AID activity. But despite repeated attempts, deciphering AID's intrinsic catalytic activities and harnessing its targeted recruitment to DNA is still intractable. Even recent cytosine base editors are unable to fully recapitulate AID's genomic and epigenomic editing properties. Here, we describe the first instance of a modular AID-based editor that recapitulates the full spectrum of genomic and epigenomic editing activity. Our 'Swiss army knife' toolbox will help better understand AID biology per se as well as improve targeted genomic and epigenomic editing.
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Affiliation(s)
- Julian Weischedel
- Institute of Experimental Immunology, University of Zurich, Zurich 8057, Switzerland
| | - Laurence Higgins
- Living Systems Institute, University of Exeter, Exeter EX4 4QD, UK
| | - Sally Rogers
- Living Systems Institute, University of Exeter, Exeter EX4 4QD, UK
| | - Anna Gramalla-Schmitz
- Institute of Experimental Immunology, University of Zurich, Zurich 8057, Switzerland
| | - Paulina Wyrzykowska
- Institute of Experimental Immunology, University of Zurich, Zurich 8057, Switzerland
| | - Simone Borgoni
- Institute of Experimental Immunology, University of Zurich, Zurich 8057, Switzerland
| | - Thomas MacCarthy
- Department of Applied Mathematics & Statistics, Stony Brook University, NY 11794-3600, USA
| | - Richard Chahwan
- Institute of Experimental Immunology, University of Zurich, Zurich 8057, Switzerland
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Zhou JZ, Huang B, Pei B, Sun GW, Pawlitz MD, Zhang W, Li X, Hokynar KC, Yao F, Perera MLW, Wei S, Zheng S, Polin LA, Poulik JM, Ranki A, Krohn K, Cunningham-Rundles C, Yang N, Bhagwat AS, Yu K, Peterson P, Kisand K, Vuong BQ, Cerutti A, Chen K. A Germinal Center Checkpoint of AIRE in B Cells Limits Antibody Diversification. bioRxiv 2024:2024.01.10.574926. [PMID: 38260362 PMCID: PMC10802573 DOI: 10.1101/2024.01.10.574926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
In response to antigens, B cells undergo affinity maturation and class switching mediated by activation-induced cytidine deaminase (AID) in germinal centers (GCs) of secondary lymphoid organs, but uncontrolled AID activity can precipitate autoimmunity and cancer. The regulation of GC antibody diversification is of fundamental importance but not well understood. We found that autoimmune regulator (AIRE), the molecule essential for T cell tolerance, is expressed in GC B cells in a CD40-dependent manner, interacts with AID and negatively regulates antibody affinity maturation and class switching by inhibiting AID function. AIRE deficiency in B cells caused altered antibody repertoire, increased somatic hypermutations, elevated autoantibodies to T helper 17 effector cytokines and defective control of skin Candida albicans. These results define a GC B cell checkpoint of humoral immunity and illuminate new approaches of generating high-affinity neutralizing antibodies for immunotherapy.
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Affiliation(s)
- Jordan Z Zhou
- Department of Obstetrics and Gynecology, Wayne State University, Detroit, MI 48201, USA
- Center for Molecular Medicine and Genetics, Wayne State University, Detroit, MI 48201, USA
- These authors contributed equally
| | - Bihui Huang
- Department of Obstetrics and Gynecology, Wayne State University, Detroit, MI 48201, USA
- The Seventh Affiliated Hospital of Sun Yat-Sen University, Shenzhen, Guangdong 518107, China
- These authors contributed equally
| | - Bo Pei
- Department of Obstetrics and Gynecology, Wayne State University, Detroit, MI 48201, USA
| | - Guang Wen Sun
- School of Applied Science, Republic Polytechnic, Singapore 738984, Singapore
| | - Michael D Pawlitz
- Department of Obstetrics and Gynecology, Wayne State University, Detroit, MI 48201, USA
| | - Wei Zhang
- Beijing Genomics Institute (BGI)-Shenzhen, Guangdong 518083, China
| | - Xinyang Li
- Beijing Genomics Institute (BGI)-Shenzhen, Guangdong 518083, China
| | - Kati C Hokynar
- Department of Virology, University of Helsinki, Helsinki 00029, Finland
| | - Fayi Yao
- Department of Obstetrics and Gynecology, Wayne State University, Detroit, MI 48201, USA
- Center for Molecular Medicine and Genetics, Wayne State University, Detroit, MI 48201, USA
| | | | - Shanqiao Wei
- Department of Chemistry, Wayne State University, Detroit, MI 48202, USA
| | - Simin Zheng
- School of Biological Sciences, Nanyang Technological University, Singapore 636921, Singapore
| | - Lisa A Polin
- Barbara Ann Karmanos Cancer Institute, Department of Oncology, Wayne State University, Detroit, MI 48201, USA
| | - Janet M Poulik
- Department of Pathology, Children's Hospital of Michigan, Detroit, MI 48201, USA
| | - Annamari Ranki
- Department of Dermatology and Allergic Diseases, University of Helsinki and Helsinki University Hospital, Helsinki 00250, Finland
| | - Kai Krohn
- Helsinki University Hospital Research Institute, Biomedicum, Helsinki 00290, Finland
| | | | - Naibo Yang
- Beijing Genomics Institute (BGI)-Shenzhen, Guangdong 518083, China
- Complete Genomics Inc., Mountain View, California 94043, USA
| | - Ashok S Bhagwat
- Department of Chemistry, Wayne State University, Detroit, MI 48202, USA
- Department of Biochemistry, Microbiology and Immunology, Wayne State University, Detroit, MI 48201, USA
| | - Kefei Yu
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
| | - Pärt Peterson
- Department of Molecular Pathology, Institute of Biomedicine and Translational Medicine, University of Tartu, Tartu 50411, Estonia
| | - Kai Kisand
- Department of Molecular Pathology, Institute of Biomedicine and Translational Medicine, University of Tartu, Tartu 50411, Estonia
| | - Bao Q Vuong
- Department of Biology, City College of New York, New York, NY 10031, USA
| | - Andrea Cerutti
- Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- Mucosal Immunology Studies Team, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Maryland 20892, USA
| | - Kang Chen
- Department of Obstetrics and Gynecology, Wayne State University, Detroit, MI 48201, USA
- School of Biological Sciences, Nanyang Technological University, Singapore 636921, Singapore
- Lead Contact
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6
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Jaiswal A, Roy R, Tamrakar A, Singh AK, Kar P, Kodgire P. Activation-induced cytidine deaminase an antibody diversification enzyme interacts with chromatin modifier UBN1 in B-cells. Sci Rep 2023; 13:19615. [PMID: 37949972 PMCID: PMC10638239 DOI: 10.1038/s41598-023-46448-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 11/01/2023] [Indexed: 11/12/2023] Open
Abstract
Activation-induced cytidine deaminase (AID) is the key mediator of antibody diversification in activated B-cells by the process of somatic hypermutation (SHM) and class switch recombination (CSR). Targeting AID to the Ig genes requires transcription (initiation and elongation), enhancers, and its interaction with numerous factors. Furthermore, the HIRA chaperon complex, a regulator of chromatin architecture, is indispensable for SHM. The HIRA chaperon complex consists of UBN1, ASF1a, HIRA, and CABIN1 that deposit H3.3 onto the DNA, the SHM hallmark. We explored whether UBN1 interacts with AID using computational and in-vitro experiments. Interestingly, our in-silico studies, such as molecular docking and molecular dynamics simulation results, predict that AID interacts with UBN1. Subsequently, co-immunoprecipitation and pull-down experiments established interactions between UBN1 and AID inside B-cells. Additionally, a double immunofluorescence assay confirmed that AID and UBN1 were co-localized in the human and chicken B-cell lines. Moreover, proximity ligation assay studies validated that AID interacts with UBN1. Ours is the first report on the interaction of genome mutator enzyme AID with UBN1. Nevertheless, the fate of interaction between UBN1 and AID is yet to be explored in the context of SHM or CSR.
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Affiliation(s)
- Ankit Jaiswal
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology, Indore, Madhya Pradesh, 453 552, India
| | - Rajarshi Roy
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology, Indore, Madhya Pradesh, 453 552, India
| | - Anubhav Tamrakar
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology, Indore, Madhya Pradesh, 453 552, India
| | - Amit Kumar Singh
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology, Indore, Madhya Pradesh, 453 552, India
| | - Parimal Kar
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology, Indore, Madhya Pradesh, 453 552, India
| | - Prashant Kodgire
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology, Indore, Madhya Pradesh, 453 552, India.
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7
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Bello A, Hirth G, Voigt S, Tepper S, Jungnickel B. Mechanism and regulation of secondary immunoglobulin diversification. Cell Cycle 2023; 22:2070-2087. [PMID: 37909747 PMCID: PMC10761156 DOI: 10.1080/15384101.2023.2275397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 10/20/2023] [Indexed: 11/03/2023] Open
Abstract
Secondary immunoglobulin diversification by somatic hypermutation and class switch recombination in B cells is instrumental for an adequate adaptive humoral immune response. These genetic events may, however, also introduce aberrations into other cellular genes and thereby cause B cell malignancies. While the basic mechanism of somatic hypermutation and class switch recombination is now well understood, their regulation and in particular the mechanism of their specific targeting to immunoglobulin genes is still rather mysterious. In this review, we summarize the current knowledge on the mechanism and regulation of secondary immunoglobulin diversification and discuss known mechanisms of physiological targeting to immunoglobulin genes and mistargeting to other cellular genes. We summarize open questions in the field and provide an outlook on future research.
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Affiliation(s)
- Amanda Bello
- Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
| | - Gianna Hirth
- Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
| | - Stefanie Voigt
- Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
| | - Sandra Tepper
- Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
| | - Berit Jungnickel
- Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
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8
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Lee JY, Chou NL, Yu YR, Shih HA, Lin HW, Lee CK, Chang MS. PHRF1 promotes the class switch recombination of IgA in CH12F3-2A cells. PLoS One 2023; 18:e0285159. [PMID: 37540725 PMCID: PMC10403053 DOI: 10.1371/journal.pone.0285159] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 04/14/2023] [Indexed: 08/06/2023] Open
Abstract
PHRF1 is an E3 ligase that promotes TGF-β signaling by ubiquitinating a homeodomain repressor TG-interacting factor (TGIF). The suppression of PHRF1 activity by PML-RARα facilitates the progression of acute promyelocytic leukemia (APL). PHRF1 also contributes to non-homologous end-joining in response to DNA damage by linking H3K36me3 and NBS1 with DNA repair machinery. However, its role in class switch recombination (CSR) is not well understood. In this study, we report the importance of PHRF1 in IgA switching in CH12F3-2A cells and CD19-Cre mice. Our studies revealed that Crispr-Cas9 mediated PHRF1 knockout and shRNA-silenced CH12F3-2A cells reduced IgA production, as well as decreased the amounts of PARP1, NELF-A, and NELF-D. The introduction of PARP1 could partially restore IgA production in PHRF1 knockout cells. Intriguingly, IgA, as well as IgG1, IgG2a, and IgG3, switchings were not significantly decreased in PHRF1 deficient splenic B lymphocytes isolated from CD19-Cre mice. The levels of PARP1 and NELF-D were not decreased in PHRF1-depleted primary splenic B cells. Overall, our findings suggest that PHRF1 may modulate IgA switching in CH12F3-2A cells.
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Affiliation(s)
- Jin-Yu Lee
- Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
| | - Nai-Lin Chou
- Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
| | - Ya-Ru Yu
- Graduate Institute of Immunology, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Hsin-An Shih
- Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
| | - Hung-Wei Lin
- Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
| | - Chine-Kuo Lee
- Graduate Institute of Immunology, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Mau-Sun Chang
- Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
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9
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Conn VM, Gabryelska M, Toubia J, Kirk K, Gantley L, Powell JA, Cildir G, Marri S, Liu R, Stringer BW, Townley S, Webb ST, Lin H, Samaraweera SE, Bailey S, Moore AS, Maybury M, Liu D, Colella AD, Chataway T, Wallington-Gates CT, Walters L, Sibbons J, Selth LA, Tergaonkar V, D'Andrea RJ, Pitson SM, Goodall GJ, Conn SJ. Circular RNAs drive oncogenic chromosomal translocations within the MLL recombinome in leukemia. Cancer Cell 2023; 41:1309-1326.e10. [PMID: 37295428 DOI: 10.1016/j.ccell.2023.05.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 03/03/2023] [Accepted: 05/03/2023] [Indexed: 06/12/2023]
Abstract
The first step of oncogenesis is the acquisition of a repertoire of genetic mutations to initiate and sustain the malignancy. An important example of this initiation phase in acute leukemias is the formation of a potent oncogene by chromosomal translocations between the mixed lineage leukemia (MLL) gene and one of 100 translocation partners, known as the MLL recombinome. Here, we show that circular RNAs (circRNAs)-a family of covalently closed, alternatively spliced RNA molecules-are enriched within the MLL recombinome and can bind DNA, forming circRNA:DNA hybrids (circR loops) at their cognate loci. These circR loops promote transcriptional pausing, proteasome inhibition, chromatin re-organization, and DNA breakage. Importantly, overexpressing circRNAs in mouse leukemia xenograft models results in co-localization of genomic loci, de novo generation of clinically relevant chromosomal translocations mimicking the MLL recombinome, and hastening of disease onset. Our findings provide fundamental insight into the acquisition of chromosomal translocations by endogenous RNA carcinogens in leukemia.
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Affiliation(s)
- Vanessa M Conn
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia; Centre for Cancer Biology, SA Pathology & University of South Australia, Adelaide, SA 5000, Australia
| | - Marta Gabryelska
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia
| | - John Toubia
- Centre for Cancer Biology, SA Pathology & University of South Australia, Adelaide, SA 5000, Australia; ACRF Cancer Genomics Facility, SA Pathology, Adelaide, SA 5000, Australia
| | - Kirsty Kirk
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia
| | - Laura Gantley
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia
| | - Jason A Powell
- Centre for Cancer Biology, SA Pathology & University of South Australia, Adelaide, SA 5000, Australia; Adelaide Medical School, Faculty of Health and Medical Sciences, the University of Adelaide, Adelaide, SA 5000, Australia
| | - Gökhan Cildir
- Centre for Cancer Biology, SA Pathology & University of South Australia, Adelaide, SA 5000, Australia
| | - Shashikanth Marri
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia
| | - Ryan Liu
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia
| | - Brett W Stringer
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia
| | - Scott Townley
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia
| | - Stuart T Webb
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia
| | - He Lin
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia
| | - Saumya E Samaraweera
- Centre for Cancer Biology, SA Pathology & University of South Australia, Adelaide, SA 5000, Australia
| | - Sheree Bailey
- Health and Biomedical Innovation, Clinical and Health Sciences, University of South Australia, Adelaide, SA 5000, Australia
| | - Andrew S Moore
- Child Health Research Centre, the University of Queensland, Brisbane, QLD 4101, Australia; Oncology Service, Children's Health Queensland Hospital and Health Service, Brisbane, QLD 4101, Australia
| | - Mellissa Maybury
- Child Health Research Centre, the University of Queensland, Brisbane, QLD 4101, Australia
| | - Dawei Liu
- Centre for Cancer Biology, SA Pathology & University of South Australia, Adelaide, SA 5000, Australia
| | - Alex D Colella
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia; Flinders Omics Facility, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia
| | - Timothy Chataway
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia; Flinders Omics Facility, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia
| | - Craig T Wallington-Gates
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia; Centre for Cancer Biology, SA Pathology & University of South Australia, Adelaide, SA 5000, Australia; Adelaide Medical School, Faculty of Health and Medical Sciences, the University of Adelaide, Adelaide, SA 5000, Australia; Flinders Medical Centre, Bedford Park, SA 5042, Australia
| | - Lucie Walters
- Adelaide Rural Clinical School, Faculty of Health and Medical Sciences, the University of Adelaide, Adelaide, SA 5000, Australia
| | - Jane Sibbons
- Adelaide Microscopy, Division of Research and Innovation, University of Adelaide, Adelaide, SA 5000, Australia
| | - Luke A Selth
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia; Freemasons Centre for Male Health and Wellbeing, Flinders University, Bedford Park, SA 5042, Australia
| | - Vinay Tergaonkar
- Laboratory of NFκB Signalling, Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A(∗)STAR), 61 Biopolis Drive, Proteos, Singapore 138673, Republic of Singapore
| | - Richard J D'Andrea
- Centre for Cancer Biology, SA Pathology & University of South Australia, Adelaide, SA 5000, Australia
| | - Stuart M Pitson
- Centre for Cancer Biology, SA Pathology & University of South Australia, Adelaide, SA 5000, Australia; Adelaide Medical School, Faculty of Health and Medical Sciences, the University of Adelaide, Adelaide, SA 5000, Australia
| | - Gregory J Goodall
- Centre for Cancer Biology, SA Pathology & University of South Australia, Adelaide, SA 5000, Australia; Adelaide Medical School, Faculty of Health and Medical Sciences, the University of Adelaide, Adelaide, SA 5000, Australia
| | - Simon J Conn
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia; Centre for Cancer Biology, SA Pathology & University of South Australia, Adelaide, SA 5000, Australia.
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10
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Costea J, Schoeberl UE, Malzl D, von der Linde M, Fitz J, Gupta A, Makharova M, Goloborodko A, Pavri R. A de novo transcription-dependent TAD boundary underpins critical multiway interactions during antibody class switch recombination. Mol Cell 2023; 83:681-697.e7. [PMID: 36736317 DOI: 10.1016/j.molcel.2023.01.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 11/04/2022] [Accepted: 01/09/2023] [Indexed: 02/05/2023]
Abstract
Interactions between transcription and cohesin-mediated loop extrusion can influence 3D chromatin architecture. However, their relevance in biology is unclear. Here, we report a direct role for such interactions in the mechanism of antibody class switch recombination (CSR) at the murine immunoglobulin heavy chain locus (Igh). Using Tri-C to measure higher-order multiway interactions on single alleles, we find that the juxtaposition (synapsis) of transcriptionally active donor and acceptor Igh switch (S) sequences, an essential step in CSR, occurs via the interaction of loop extrusion complexes with a de novo topologically associating domain (TAD) boundary formed via transcriptional activity across S regions. Surprisingly, synapsis occurs predominantly in proximity to the 3' CTCF-binding element (3'CBE) rather than the Igh super-enhancer, suggesting a two-step mechanism whereby transcription of S regions is not topologically coupled to synapsis, as has been previously proposed. Altogether, these insights advance our understanding of how 3D chromatin architecture regulates CSR.
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11
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Surman SL, Jones BG, Penkert RR, Sealy RE, Marion T, Thomas PG, Neale G, Xu B, Hurwitz JL. How Estrogen, Testosterone, and Sex Differences Influence Serum Immunoglobulin Isotype Patterns in Mice and Humans. Viruses 2023; 15. [PMID: 36851695 DOI: 10.3390/v15020482] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 01/31/2023] [Accepted: 02/03/2023] [Indexed: 02/11/2023] Open
Abstract
Females often exhibit superior immune responses compared to males toward vaccines and pathogens such as influenza viruses and SARS-CoV-2. To help explain these differences, we first studied serum immunoglobulin isotype patterns in C57BL/6 male and female mice. We focused on IgG2b, an isotype that lends to virus control and that has been previously shown to be elevated in murine females compared to males. Improvements in IgG2b serum levels, and/or IgG2b ratios with other non-IgM isotypes, were observed when: (i) wildtype (WT) female mice were compared to estrogen receptor knockout mice (IgG2b, IgG2b/IgG3, IgG2b/IgG1, and IgG2b/IgA were all higher in WT mice), (ii) unmanipulated female mice were compared to ovariectomized mice (IgG2b/IgA was higher in unmanipulated animals), (iii) female mice were supplemented with estrogen in the context of an inflammatory insult (IgG2b and IgG2b/IgG3 were improved by estrogen supplementation), and (iv) male mice were supplemented with testosterone, a hormone that can convert to estrogen in vivo (IgG2b, IgG2b/IgG3, IgG2b/IgG1, and IgG2b/IgA were all improved by supplementation). We next examined data from three sets of previously described male and female human blood samples. In each case, there were higher IgG2 levels, and/or ratios of IgG2 with non-IgM isotypes, in human females compared to males. The effects of sex and sex hormones in the mouse and human studies were subtle, but frequent, suggesting that sex hormones represent only a fraction of the factors that influence isotype patterns. Examination of the gene loci suggested that upregulation of murine IgG2b or human IgG2 could be mediated by estrogen receptor binding to estrogen response elements and cytosine-adenine (CA) repeats upstream of respective Cγ genes. Given that murine IgG2b and human IgG2 lend to virus control, the isotype biases in females may be sufficient to improve outcomes following vaccination or infection. Future attention to sex hormone levels, and consequent immunoglobulin isotype patterns, in clinical trials are encouraged to support the optimization of vaccine and drug products for male and female hosts.
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12
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Abstract
PURPOSE OF REVIEW The development of cancer in patients with genetically determined inborn errors of immunity (IEI) is much higher than in the general population. The hallmarks of cancer are a conceptualization tool that can refine the complexities of cancer development and pathophysiology. Each genetic defect may impose a different pathological tumor predisposition, which needs to be identified and linked with known hallmarks of cancer. RECENT FINDINGS Four new hallmarks of cancer have been suggested, recently, including unlocking phenotypic plasticity, senescent cells, nonmutational epigenetic reprogramming, and polymorphic microbiomes. Moreover, more than 50 new IEI genes have been discovered during the last 2 years from which 15 monogenic defects perturb tumor immune surveillance in patients. SUMMARY This review provides a more comprehensive and updated overview of all 14 cancer hallmarks in IEI patients and covers aspects of cancer predisposition in novel genes in the ever-increasing field of IEI.
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13
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Haque F, Honjo T, Begum NA. XLID syndrome gene Med12 promotes Ig isotype switching through chromatin modification and enhancer RNA regulation. Sci Adv 2022; 8:eadd1466. [PMID: 36427307 PMCID: PMC9699684 DOI: 10.1126/sciadv.add1466] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The transcriptional coactivator Med12 regulates gene expression through its kinase module. Here, we show a kinase module-independent function of Med12 in CSR. Med12 is essential for super-enhancer activation by collaborating with p300-Jmjd6/Carm1 coactivator complexes. Med12 loss decreases H3K27 acetylation and eRNA transcription with concomitant impairment of AID-induced DNA breaks, S-S synapse formation, and 3'RR-Eμ interaction. CRISPR-dCas9-mediated enhancer activation reestablishes the epigenomic and transcriptional hallmarks of the super-enhancer and fully restores the Med12 depletion defects. Moreover, 3'RR-derived eRNAs are critical for promoting S region epigenetic regulation, synapse formation, and recruitment of Med12 and AID to the IgH locus. We find that XLID syndrome-associated Med12 mutations are defective in both 3'RR eRNA transcription and CSR, suggesting that B and neuronal cells may have cell-specific super-enhancer dysfunctions. We conclude that Med12 is essential for IgH 3'RR activation/eRNA transcription and plays a central role in AID-induced antibody gene diversification and genomic instability in B cells.
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Affiliation(s)
- Farazul Haque
- Department of Immunology and Genomic Medicine, Graduate School of Medicine, Kyoto University, Yoshida, Sakyo-Ku, Kyoto 606-8501, Japan
| | - Tasuku Honjo
- Department of Immunology and Genomic Medicine, Graduate School of Medicine, Kyoto University, Yoshida, Sakyo-Ku, Kyoto 606-8501, Japan
| | - Nasim A Begum
- Department of Immunology and Genomic Medicine, Graduate School of Medicine, Kyoto University, Yoshida, Sakyo-Ku, Kyoto 606-8501, Japan
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14
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Peycheva M, Neumann T, Malzl D, Nazarova M, Schoeberl UE, Pavri R. DNA replication timing directly regulates the frequency of oncogenic chromosomal translocations. Science 2022; 377:eabj5502. [DOI: 10.1126/science.abj5502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Chromosomal translocations result from the joining of DNA double-strand breaks (DSBs) and frequently cause cancer. However, the steps linking DSB formation to DSB ligation remain undeciphered. We report that DNA replication timing (RT) directly regulates lymphomagenic
Myc
translocations during antibody maturation in B cells downstream of DSBs and independently of DSB frequency. Depletion of minichromosome maintenance complexes alters replication origin activity, decreases translocations, and deregulates global RT. Ablating a single origin at
Myc
causes an early-to-late RT switch, loss of translocations, and reduced proximity with the immunoglobulin heavy chain (
Igh
) gene, its major translocation partner. These phenotypes were reversed by restoring early RT. Disruption of early RT also reduced tumorigenic translocations in human leukemic cells. Thus, RT constitutes a general mechanism in translocation biogenesis linking DSB formation to DSB ligation.
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Affiliation(s)
- Mihaela Peycheva
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter, 1030 Vienna, Austria
| | - Tobias Neumann
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter, 1030 Vienna, Austria
- Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, Vienna Biocenter, 1030 Vienna, Austria
| | - Daniel Malzl
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter, 1030 Vienna, Austria
| | - Mariia Nazarova
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter, 1030 Vienna, Austria
| | - Ursula E. Schoeberl
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter, 1030 Vienna, Austria
| | - Rushad Pavri
- Research Institute of Molecular Pathology (IMP), Vienna Biocenter, 1030 Vienna, Austria
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15
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Vlachiotis S, Abolhassani H. Transcriptional regulation of B cell class-switch recombination: the role in development of noninfectious complications. Expert Rev Clin Immunol 2022; 18:1145-1154. [DOI: 10.1080/1744666x.2022.2123795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- Stelios Vlachiotis
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | - Hassan Abolhassani
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
- Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, Iran
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16
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Tsukumo SI, Subramani PG, Seija N, Tabata M, Maekawa Y, Mori Y, Ishifune C, Itoh Y, Ota M, Fujio K, Di Noia JM, Yasutomo K. AFF3, a susceptibility factor for autoimmune diseases, is a molecular facilitator of immunoglobulin class switch recombination. Sci Adv 2022; 8:eabq0008. [PMID: 36001653 PMCID: PMC9401627 DOI: 10.1126/sciadv.abq0008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 07/08/2022] [Indexed: 06/15/2023]
Abstract
Immunoglobulin class switch recombination (CSR) plays critical roles in controlling infections and inflammatory tissue injuries. Here, we show that AFF3, a candidate gene for both rheumatoid arthritis and type 1 diabetes, is a molecular facilitator of CSR with an isotype preference. Aff3-deficient mice exhibit low serum levels of immunoglobulins, predominantly immunoglobulin G2c (IgG2c) followed by IgG1 and IgG3 but not IgM. Furthermore, Aff3-deficient mice show weak resistance to Plasmodium yoelii infection, confirming that Aff3 modulates immunity to this pathogen. Mechanistically, the AFF3 protein binds to the IgM and IgG1 switch regions via a C-terminal domain, and Aff3 deficiency reduces the binding of AID to the switch regions less efficiently. One AFF3 risk allele for rheumatoid arthritis is associated with high mRNA expression of AFF3, IGHG2, and IGHA2 in human B cells. These findings demonstrate that AFF3 directly regulates CSR by facilitating the recruitment of AID to the switch regions.
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Affiliation(s)
- Shin-ichi Tsukumo
- Department of Immunology and Parasitology, Graduate School of Medicine, Tokushima University, Tokushima, Japan
- Department of Interdisciplinary Research on Medicine and Photonics, Institute of Post-LED Photonics, Tokushima University, Tokushima, Japan
| | - Poorani Ganesh Subramani
- Institut de Recherches Cliniques de Montréal, Montréal, QC, Canada
- Department of Medicine and Division of Experimental Medicine, McGill University, Montréal, QC, Canada
| | - Noé Seija
- Institut de Recherches Cliniques de Montréal, Montréal, QC, Canada
- Molecular Biology Programs, Department of Medicine, University of Montreal, Montréal, QC, Canada
| | - Mizuho Tabata
- Department of Parasitology and Infectious Diseases, Gifu University Graduate School of Medicine, Gifu, Japan
| | - Yoichi Maekawa
- Department of Parasitology and Infectious Diseases, Gifu University Graduate School of Medicine, Gifu, Japan
| | - Yuya Mori
- Division of Pathogenesis and Disease Regulation, Department of Pathology, Shiga University of Medical Science, Shiga, Japan
| | - Chieko Ishifune
- Department of Immunology and Parasitology, Graduate School of Medicine, Tokushima University, Tokushima, Japan
| | - Yasushi Itoh
- Division of Pathogenesis and Disease Regulation, Department of Pathology, Shiga University of Medical Science, Shiga, Japan
| | - Mineto Ota
- Department of Allergy and Rheumatology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Department of Functional Genomics and Immunological Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Keishi Fujio
- Department of Allergy and Rheumatology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Javier M. Di Noia
- Institut de Recherches Cliniques de Montréal, Montréal, QC, Canada
- Department of Medicine and Division of Experimental Medicine, McGill University, Montréal, QC, Canada
- Molecular Biology Programs, Department of Medicine, University of Montreal, Montréal, QC, Canada
| | - Koji Yasutomo
- Department of Immunology and Parasitology, Graduate School of Medicine, Tokushima University, Tokushima, Japan
- Department of Interdisciplinary Research on Medicine and Photonics, Institute of Post-LED Photonics, Tokushima University, Tokushima, Japan
- The Research Cluster Program on Immunological Diseases, Tokushima University, Tokushima, Japan
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17
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Song A, Chen FX. The pleiotropic roles of SPT5 in transcription. Transcription 2022; 13:53-69. [PMID: 35876486 PMCID: PMC9467590 DOI: 10.1080/21541264.2022.2103366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Initially discovered by genetic screens in budding yeast, SPT5 and its partner SPT4 form a stable complex known as DSIF in metazoa, which plays pleiotropic roles in multiple steps of transcription. SPT5 is the most conserved transcription elongation factor, being found in all three domains of life; however, its structure has evolved to include new domains and associated posttranslational modifications. These gained features have expanded transcriptional functions of SPT5, likely to meet the demand for increasingly complex regulation of transcription in higher organisms. This review discusses the pleiotropic roles of SPT5 in transcription, including RNA polymerase II (Pol II) stabilization, enhancer activation, Pol II pausing and its release, elongation, and termination, with a focus on the most recent progress of SPT5 functions in regulating metazoan transcription.
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Affiliation(s)
- Aixia Song
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, State Key Laboratory of Genetic Engineering and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, Province 200032, China
| | - Fei Xavier Chen
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, State Key Laboratory of Genetic Engineering and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, Province 200032, China
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18
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Pan X, Huang LF. Multi-omics to characterize the functional relationships of R-loops with epigenetic modifications, RNAPII transcription and gene expression. Brief Bioinform 2022; 23:6618633. [DOI: 10.1093/bib/bbac238] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 05/19/2022] [Accepted: 05/21/2022] [Indexed: 12/12/2022] Open
Abstract
Abstract
Abnormal accumulation of R-loops results in replication stress, genome instability, chromatin alterations and gene silencing. Little research has been done to characterize functional relationships among R-loops, histone marks, RNA polymerase II (RNAPII) transcription and gene regulation. We built extremely randomized trees (ETs) models to predict the genome-wide R-loops using RNAPII and multiple histone modifications chromatin immunoprecipitation (ChIP)-seq, DNase-seq, Global Run-On sequencing (GRO-seq) and R-loop profiling data. We compared the performance of ET models to multiple machine learning approaches, and the proposed ET models achieved the best and extremely robust performances. Epigenetic profiles are highly predictive of R-loops genome-widely and they are strongly associated with R-loop formation. In addition, the presence of R-loops is significantly correlated with RNAPII transcription activity, H3K4me3 and open chromatin around the transcription start site, and H3K9me1 and H3K9me3 around the transcription termination site. RNAPII pausing defects were correlated with 5′R-loops accumulation, and transcriptional termination defects and read-throughs were correlated with 3′R-loops accumulation. Furthermore, we found driver genes with 5′R-loops and RNAPII pausing defects express significantly higher and genes with 3′R-loops and read-through transcription express significantly lower than genes without R-loops. These driver genes are enriched with chromosomal instability, Hippo–Merlin signaling Dysregulation, DNA damage response and TGF-β pathways, indicating R-loops accumulating at the 5′ end of genes play oncogenic roles, whereas at the 3′ end of genes play tumor-suppressive roles in tumorigenesis.
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Affiliation(s)
- Xingxin Pan
- Division of Experimental Hematology and Cancer Biology , Brain Tumor Center, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229 , USA
| | - L Frank Huang
- Division of Experimental Hematology and Cancer Biology , Brain Tumor Center, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229 , USA
- Department of Pediatrics, University of Cincinnati College of Medicine , Cincinnati, OH 45229 , USA
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19
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Heltzel JHM, Maul RW, Yang W, Gearhart PJ. Promoter Proximity Defines Mutation Window for V H and V Κ Genes Rearranged to Different J Genes. J Immunol 2022; 208:2220-2226. [PMID: 35418469 PMCID: PMC9050841 DOI: 10.4049/jimmunol.2101002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 02/21/2022] [Indexed: 05/03/2023]
Abstract
Somatic hypermutation induced by activation-induced deaminase (AID) occurs at high densities between the Ig V gene promoter and intronic enhancer, which encompasses DNA encoding the rearranged V gene exon and J intron. It has been proposed that proximity between the promoter and enhancer defines the boundaries of mutation in V regions. However, depending on the J gene used, the distance between the promoter and enhancer is quite variable and may result in differential targeting around the V gene. To examine the effect of distance in mutation accumulation, we sequenced 320 clones containing different endogenous rearranged V genes in the IgH and Igκ loci from Peyer's patch B cells of mice. Clones were grouped by their use of different J genes. Distances between the V gene and enhancer ranged from ∼2.3 kb of intron DNA for rearrangements using J1, ∼2.0 kb for rearrangements using J2, ∼1.6 kb for rearrangements using J3 (H) or 4 (κ), and 1.1 kb for rearrangements using J4 (H) or 5 (κ). Strikingly, >90% of intron mutations occurred within 1 kb downstream of the J gene for both H and κ clones, regardless of which J gene was used. Thus, there is no evidence that the intron sequence or enhancer plays a role in determining the extent of mutation. The results indicate that V region intron mutations are targeted by their proximity to the promoter, suggesting they result from AID interactions with RNA polymerase II over a 1-kb region.
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Affiliation(s)
- Justin H M Heltzel
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD
| | - Robert W Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD
| | - William Yang
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD
| | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, MD
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20
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Xie X, Gan T, Rao B, Zhang W, Panchakshari RA, Yang D, Ji X, Cao Y, Alt FW, Meng FL, Hu J. C-terminal deletion-induced condensation sequesters AID from IgH targets in immunodeficiency. EMBO J 2022; 41:e109324. [PMID: 35471583 PMCID: PMC9156971 DOI: 10.15252/embj.2021109324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 04/07/2022] [Accepted: 04/08/2022] [Indexed: 11/09/2022] Open
Abstract
In activated B cells, activation-induced cytidine deaminase (AID) generates programmed DNA lesions required for antibody class switch recombination (CSR), which may also threaten genome integrity. AID dynamically shuttles between cytoplasm and nucleus, and the majority stays in the cytoplasm due to active nuclear export mediated by its C-terminal peptide. In immunodeficient-patient cells expressing mutant AID lacking its C-terminus, a catalytically active AID-delC protein accumulates in the nucleus but nevertheless fails to support CSR. To resolve this apparent paradox, we dissected the function of AID-delC proteins in the CSR process and found that they cannot efficiently target antibody genes. We demonstrate that AID-delC proteins form condensates both in vivo and in vitro, dependent on its N-terminus and on a surface arginine-rich patch. Co-expression of AID-delC and wild-type AID leads to an unbalanced nuclear AID-delC/AID ratio, with AID-delC proteins able to trap wild-type AID in condensates, resulting in a dominant-negative phenotype that could contribute to immunodeficiency. The co-condensation model of mutant and wild-type proteins could be an alternative explanation for the dominant-negative effect in genetic disorders.
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Affiliation(s)
- Xia Xie
- 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
| | - Tingting Gan
- The MOE Key Laboratory of Cell Proliferation and Differentiation, Genome Editing Research Center, School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Bing Rao
- 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
| | - Weiwei Zhang
- The MOE Key Laboratory of Cell Proliferation and Differentiation, Genome Editing Research Center, School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Rohit A Panchakshari
- Program in Cellular and Molecular Medicine, Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Dingpeng Yang
- 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
| | - Xiong Ji
- The MOE Key Laboratory of Cell Proliferation and Differentiation, Genome Editing Research Center, School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Yu Cao
- Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Frederick W Alt
- Program in Cellular and Molecular Medicine, Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - 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
| | - Jiazhi Hu
- The MOE Key Laboratory of Cell Proliferation and Differentiation, Genome Editing Research Center, School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
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21
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Lue JK, Downs-Canner S, Chaudhuri J. The role of B cells in the development, progression, and treatment of lymphomas and solid tumors. Adv Immunol 2022; 154:71-117. [PMID: 36038195 DOI: 10.1016/bs.ai.2022.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
B cells are integral components of the mammalian immune response as they have the ability to generate antibodies against an almost infinite array of antigens. Over the past several decades, significant scientific progress has been made in understanding that this enormous B cell diversity contributes to pathogen clearance. However, our understanding of the humoral response to solid tumors and to tumor-specific antigens is unclear. In this review, we first discuss how B cells interact with other cells in the tumor microenvironment and influence the development and progression of various solid tumors. The ability of B lymphocytes to generate antibodies against a diverse repertoire of antigens and subsequently tailor the humoral immune response to specific pathogens relies on their ability to undergo genomic alterations during their development and differentiation. We will discuss key transforming events that lead to the development of B cell lymphomas. Overall, this review provides a foundation for innovative therapeutic interventions for both lymphoma and solid tumor malignancies.
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Affiliation(s)
- Jennifer K Lue
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, United States.
| | - Stephanie Downs-Canner
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, United States.
| | - Jayanta Chaudhuri
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, United States.
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22
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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. J Immunol 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] [What about the content of this article? (0)] [Affiliation(s)] [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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23
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Sakhtemani R, Perera MLW, Hübschmann D, Siebert R, Lawrence M, Bhagwat A. OUP accepted manuscript. Nucleic Acids Res 2022; 50:5145-5157. [PMID: 35524550 PMCID: PMC9122604 DOI: 10.1093/nar/gkac296] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 04/08/2022] [Accepted: 04/29/2022] [Indexed: 12/04/2022] Open
Abstract
Activation-induced deaminase (AID) is a DNA-cytosine deaminase that mediates maturation of antibodies through somatic hypermutation and class-switch recombination. While it causes mutations in immunoglobulin heavy and light chain genes and strand breaks in the switch regions of the immunoglobulin heavy chain gene, it largely avoids causing such damage in the rest of the genome. To help understand targeting by human AID, we expressed it in repair-deficient Escherichia coli and mapped the created uracils in the genomic DNA using uracil pull-down and sequencing, UPD-seq. We found that both AID and the human APOBEC3A preferentially target tRNA genes and transcription start sites, but do not show preference for highly transcribed genes. Unlike A3A, AID did not show a strong replicative strand bias or a preference for hairpin loops. Overlapping uracilation peaks between these enzymes contained binding sites for a protein, FIS, that helps create topological domains in the E. coli genome. To confirm whether these findings were relevant to B cells, we examined mutations from lymphoma and leukemia genomes within AID-preferred sequences. These mutations also lacked replicative strand bias or a hairpin loop preference. We propose here a model for how AID avoids causing mutations in the single-stranded DNA found within replication forks.
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Affiliation(s)
- Ramin Sakhtemani
- Department of Chemistry, Wayne State University, Detroit, MI 48202, USA
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- Broad Institute of Massachusetts Institute of Technology and Harvard University, Cambridge, MA, USA
| | | | - Daniel Hübschmann
- Molecular Precision Oncology Program, National Center for Tumor Diseases, Heidelberg and German Cancer Research Center, Heidelberg, Germany
- Heidelberg Institute for Stem cell Technology and Experimental Medicine, Heidelberg, Germany
- German Cancer Consortium, Heidelberg, Germany
| | - Reiner Siebert
- Institute of Human Genetics, Ulm University and Ulm University Medical Center, Ulm, Germany
| | - Michael S Lawrence
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- Broad Institute of Massachusetts Institute of Technology and Harvard University, Cambridge, MA, USA
| | - Ashok S Bhagwat
- To whom correspondence should be addressed. Tel: +1 734 425 1749; Fax: +1 313 577 8822, 443;
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24
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Zhao H, Hartono SR, de Vera KMF, Yu Z, Satchi K, Zhao T, Sciammas R, Sanz L, Chédin F, Barlow J. Senataxin and RNase H2 act redundantly to suppress genome instability during class switch recombination. eLife 2022; 11:78917. [PMID: 36542058 PMCID: PMC9771370 DOI: 10.7554/elife.78917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 11/17/2022] [Indexed: 12/24/2022] Open
Abstract
Class switch recombination generates distinct antibody isotypes critical to a robust adaptive immune system, and defects are associated with autoimmune disorders and lymphomagenesis. Transcription is required during class switch recombination to recruit the cytidine deaminase AID-an essential step for the formation of DNA double-strand breaks-and strongly induces the formation of R loops within the immunoglobulin heavy-chain locus. However, the impact of R loops on double-strand break formation and repair during class switch recombination remains unclear. Here, we report that cells lacking two enzymes involved in R loop removal-senataxin and RNase H2-exhibit increased R loop formation and genome instability at the immunoglobulin heavy-chain locus without impacting its transcriptional activity, AID recruitment, or class switch recombination efficiency. Senataxin and RNase H2-deficient cells also exhibit increased insertion mutations at switch junctions, a hallmark of alternative end joining. Importantly, these phenotypes were not observed in cells lacking senataxin or RNase H2B alone. We propose that senataxin acts redundantly with RNase H2 to mediate timely R loop removal, promoting efficient repair while suppressing AID-dependent genome instability and insertional mutagenesis.
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Affiliation(s)
- Hongchang Zhao
- Department of Microbiology and Molecular Genetics, University of California, DavisDavisUnited States
| | - Stella R Hartono
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
| | | | - Zheyuan Yu
- Department of Microbiology and Molecular Genetics, University of California, DavisDavisUnited States,Graduate Group in Biostatistics, University of California, DavisDavisUnited States
| | - Krishni Satchi
- Department of Microbiology and Molecular Genetics, University of California, DavisDavisUnited States
| | - Tracy Zhao
- Department of Microbiology and Molecular Genetics, University of California, DavisDavisUnited States
| | - Roger Sciammas
- Center for Immunology and Infectious Diseases, University of California, DavisDavisUnited States
| | - Lionel Sanz
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
| | - Frédéric Chédin
- Department of Molecular and Cellular Biology, University of California, DavisDavisUnited States
| | - Jacqueline Barlow
- Department of Microbiology and Molecular Genetics, University of California, DavisDavisUnited States
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25
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Yu G, Zhang Y, Gupta V, Zhang J, MacCarthy T, Duan Z, Scharff MD. 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:e2114743118. [PMID: 34873043 DOI: 10.1073/pnas.2114743118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [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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26
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Abstract
The most common human lymphoid chromosomal translocations involve concurrent failures of the recombination activating gene (RAG) complex and Activation-Induced Deaminase (AID). These are two enzymes that are normally expressed for purposes of the two site-specific DNA recombination processes: V(D)J recombination and class switch recombination (CSR). First, though it is rare, a low level of expression of AID can introduce long-lived T:G mismatch lesions at 20-600 bp fragile zones. Second, the V(D)J recombination process can occasionally fail to rejoin coding ends, and this failure may permit an opportunity for Artemis:DNA-dependent kinase catalytic subunit (DNA-PKcs) to convert the T:G mismatch sites at the fragile zones into double-strand breaks. The 20-600 bp fragile zones must be, at least transiently, in a single-stranded DNA (ssDNA) state for the first step to occur, because AID only acts on ssDNA. Here we discuss the key DNA sequence features that lead to AID action at a fragile zone, which are (a) the proximity and density of strings of cytosine nucleotides (C-strings) that cause a B/A-intermediate DNA conformation; (b) overlapping AID hotspots that contain a methyl CpG (WRCG), which AID converts to a long-lived T:G mismatch; and (c) transcription, which, though not essential, favors increased ssDNA in the fragile zone. We also summarize chromosomal features of the focal fragile zones in lymphoid malignancies and discuss the clinical relevance of understanding the translocation mechanisms. Many of the key principles covered here are also relevant to chromosomal translocations in non-lymphoid somatic cells as well.
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Affiliation(s)
- Di Liu
- Department of Pathology & Laboratory Medicine, Department of Biochemistry & Molecular Biology, Department of Molecular Microbiology and Immunology, and Section of Computational Biology in the Department of Biological Sciences, USC Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Michael R Lieber
- Department of Pathology & Laboratory Medicine, Department of Biochemistry & Molecular Biology, Department of Molecular Microbiology and Immunology, and Section of Computational Biology in the Department of Biological Sciences, USC Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
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27
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Shen HM, Wuerffel R, Cantillo JF, Priyadarshi S, Lei X, Liang J, Wu YL, Kenter AL. Loop extrusion promotes an alternate pathway for isotype switching. Cell Rep 2021; 37:110059. [PMID: 34818547 PMCID: PMC8979556 DOI: 10.1016/j.celrep.2021.110059] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 07/22/2021] [Accepted: 11/03/2021] [Indexed: 01/02/2023] Open
Abstract
Class-switch recombination (CSR) involves replacement of the Cμ
constant region with another downstream CH region. CSR is initiated
by activation-induced cytidine deaminase (AID)-mediated DNA breaks that are
targeted to transcriptionally active switch (S) regions. S region promoters
(Prs) direct synapsis by associating with the Eμ and 3′Eα
enhancers that jointly anchor a chromatin loop. We report that asymmetric loop
extrusion allows 3′Eα to track along the locus and form Pr-Pr-E
interactions that mediate CSR between downstream S regions, followed by
switching to donor Sμ. This alternative pathway bypasses sequential
switching and creates immunoglobulin (Ig)E+ B cells in the absence of
IgG1 expression. Based on the analysis of diagnostic CSR products in B cell
subsets, we identify a BCR-negative cell intermediate that is pivotal to
efficient CSR. Shen et al. report that 3′Eα tracks along the Igh locus via
unidirectional loop extrusion to form germline transcript promoter (Pr)-Pr-E
interactions that mediate an alternative CSR pathway. B cell intermediates of
CSR are identified, which are AID-dependent, surface BCR-negative, and in the
G1 phase of the cell cycle.
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Affiliation(s)
- Hong Ming Shen
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612-7344, USA
| | - Robert Wuerffel
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612-7344, USA
| | - Jose F Cantillo
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612-7344, USA
| | - Saurabh Priyadarshi
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612-7344, USA
| | - Xue Lei
- Department of Bioengineering, University of Illinois Colleges of Engineering and Medicine, Chicago, IL 60612-7344, USA
| | - Jie Liang
- Department of Bioengineering, University of Illinois Colleges of Engineering and Medicine, Chicago, IL 60612-7344, USA
| | - Yee Ling Wu
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL 60153, USA
| | - Amy L Kenter
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612-7344, USA.
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28
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Aoi Y, Takahashi YH, Shah AP, Iwanaszko M, Rendleman EJ, Khan NH, Cho BK, Goo YA, Ganesan S, Kelleher NL, Shilatifard A. SPT5 stabilization of promoter-proximal RNA polymerase II. Mol Cell 2021; 81:4413-4424.e5. [PMID: 34480849 PMCID: PMC8687145 DOI: 10.1016/j.molcel.2021.08.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 06/28/2021] [Accepted: 08/03/2021] [Indexed: 01/02/2023]
Abstract
Based on in vitro studies, it has been demonstrated that the DSIF complex, composed of SPT4 and SPT5, regulates the elongation stage of transcription catalyzed by RNA polymerase II (RNA Pol II). The precise cellular function of SPT5 is not clear, because conventional gene depletion strategies for SPT5 result in loss of cellular viability. Using an acute inducible protein depletion strategy to circumvent this issue, we report that SPT5 loss triggers the ubiquitination and proteasomal degradation of the core RNA Pol II subunit RPB1, a process that we show to be evolutionarily conserved from yeast to human cells. RPB1 degradation requires the E3 ligase Cullin 3, the unfoldase VCP/p97, and a novel form of CDK9 kinase complex. Our study demonstrates that SPT5 stabilizes RNA Pol II specifically at promoter-proximal regions, permitting RNA Pol II release from promoters into gene bodies and providing mechanistic insight into the cellular function of SPT5 in safeguarding accurate gene expression.
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Affiliation(s)
- Yuki Aoi
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Yoh-Hei Takahashi
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Avani P Shah
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Marta Iwanaszko
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Emily J Rendleman
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Nabiha H Khan
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Byoung-Kyu Cho
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Proteomics Center of Excellence, Northwestern University, Evanston, IL 60611, USA
| | - Young Ah Goo
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Proteomics Center of Excellence, Northwestern University, Evanston, IL 60611, USA
| | - Sheetal Ganesan
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Neil L Kelleher
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Proteomics Center of Excellence, Northwestern University, Evanston, IL 60611, USA
| | - Ali Shilatifard
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
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29
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Dalloul I, Laffleur B, Dalloul Z, Wehbi B, Jouan F, Brauge B, Derouault P, Moreau J, Kracker S, Fischer A, Durandy A, Le Noir S, Cogné M. UnAIDed Class Switching in Activated B-Cells Reveals Intrinsic Features of a Self-Cleaving IgH Locus. Front Immunol 2021; 12:737427. [PMID: 34777346 PMCID: PMC8581400 DOI: 10.3389/fimmu.2021.737427] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 10/11/2021] [Indexed: 11/13/2022] Open
Abstract
Activation-induced deaminase (AID) is the major actor of immunoglobulin (Ig) gene diversification in germinal center B-cells. From its first description, it was considered as mandatory for class switch recombination (CSR), and this discovery initiated a long quest for all of the AID-interacting factors controlling its activity. The mechanisms focusing AID-mediated DNA lesions to given target sequences remain incompletely understood with regards the detailed characterization of optimal substrates in which cytidine deamination will lead to double strand breaks (DSBs) and chromosomal cleavage. In an effort to reconsider whether such CSR breaks absolutely require AID, we herein provide evidence, based on deep-sequencing approaches, showing that this dogma is not absolute in both human and mouse B lymphocytes. In activated B-cells from either AID-deficient mice or human AID-deficient patients, we report an intrinsic ability of the IgH locus to undergo "on-target" cleavage and subsequent synapsis of broken regions in conditions able to yield low-level CSR. DNA breaks occur in such conditions within the same repetitive S regions usually targeted by AID, but their repair follows a specific pathway with increased usage of microhomology-mediated repair. These data further demonstrate the role of AID machinery as not initiating de novo chromosomal cleavage but rather catalyzing a process which spontaneously initiates at low levels in an appropriately conformed IgH locus.
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Affiliation(s)
- Iman Dalloul
- Institut National de la Santé et de la Recherche Médicale (INSERM) U1262, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche (UMR) 7276, Limoges University, Limoges, France
| | - Brice Laffleur
- Institut National de la Santé et de la Recherche Médicale (INSERM) U 1236, Rennes1 University, Rennes, France
| | - Zeinab Dalloul
- Institut National de la Santé et de la Recherche Médicale (INSERM) U1262, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche (UMR) 7276, Limoges University, Limoges, France
| | - Batoul Wehbi
- Institut National de la Santé et de la Recherche Médicale (INSERM) U1262, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche (UMR) 7276, Limoges University, Limoges, France
| | - Florence Jouan
- Institut National de la Santé et de la Recherche Médicale (INSERM) U 1236, Rennes1 University, Rennes, France
| | - Baptiste Brauge
- Institut National de la Santé et de la Recherche Médicale (INSERM) U 1236, Rennes1 University, Rennes, France
| | - Paco Derouault
- Centre Hospitalier Universitaire (CHU) Dupuytren, Limoges, France
| | - Jeanne Moreau
- Institut National de la Santé et de la Recherche Médicale (INSERM) U1262, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche (UMR) 7276, Limoges University, Limoges, France
| | - Sven Kracker
- Institut National de la Santé et de la Recherche Médicale (INSERM) Unité Mixte de Recherche (UMR) 1163, Laboratory of Human Lympho-hematopoiesis, Imagine Institute, Université de Paris, Paris, France
| | - Alain Fischer
- Institut National de la Santé et de la Recherche Médicale (INSERM) Unité Mixte de Recherche (UMR) 1163, Laboratory of Human Lympho-hematopoiesis, Imagine Institute, Université de Paris, Paris, France
| | - Anne Durandy
- Institut National de la Santé et de la Recherche Médicale (INSERM) Unité Mixte de Recherche (UMR) 1163, Laboratory of Human Lympho-hematopoiesis, Imagine Institute, Université de Paris, Paris, France
| | - Sandrine Le Noir
- Institut National de la Santé et de la Recherche Médicale (INSERM) U1262, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche (UMR) 7276, Limoges University, Limoges, France
| | - Michel Cogné
- Institut National de la Santé et de la Recherche Médicale (INSERM) U1262, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche (UMR) 7276, Limoges University, Limoges, France
- Institut National de la Santé et de la Recherche Médicale (INSERM) U 1236, Rennes1 University, Rennes, France
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30
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Dauba A, Khamlichi AA. Long-Range Control of Class Switch Recombination by Transcriptional Regulatory Elements. Front Immunol 2021; 12:738216. [PMID: 34594340 PMCID: PMC8477019 DOI: 10.3389/fimmu.2021.738216] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 08/17/2021] [Indexed: 01/18/2023] Open
Abstract
Immunoglobulin class switch recombination (CSR) plays a crucial role in adaptive immune responses through a change of the effector functions of antibodies and is triggered by T-cell-dependent as well as T-cell-independent antigens. Signals generated following encounter with each type of antigen direct CSR to different isotypes. At the genomic level, CSR occurs between highly repetitive switch sequences located upstream of the constant gene exons of the immunoglobulin heavy chain locus. Transcription of switch sequences is mandatory for CSR and is induced in a stimulation-dependent manner. Switch transcription takes place within dynamic chromatin domains and is regulated by long-range regulatory elements which promote alignment of partner switch regions in CSR centers. Here, we review recent work and models that account for the function of long-range transcriptional regulatory elements and the chromatin-based mechanisms involved in the control of CSR.
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Affiliation(s)
- Audrey Dauba
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, Université Paul Sabatier, Toulouse, France
| | - Ahmed Amine Khamlichi
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, Université Paul Sabatier, Toulouse, France
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31
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Sobia P, Archary D. Preventive HIV Vaccines-Leveraging on Lessons from the Past to Pave the Way Forward. Vaccines (Basel) 2021; 9:vaccines9091001. [PMID: 34579238 PMCID: PMC8472969 DOI: 10.3390/vaccines9091001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 09/01/2021] [Accepted: 09/03/2021] [Indexed: 12/05/2022] Open
Abstract
Almost four decades on, since the 1980’s, with hundreds of HIV vaccine candidates tested in both non-human primates and humans, and several HIV vaccines trials later, an efficacious HIV vaccine continues to evade us. The enormous worldwide genetic diversity of HIV, combined with HIV’s inherent recombination and high mutation rates, has hampered the development of an effective vaccine. Despite the advent of antiretrovirals as pre-exposure prophylaxis and preventative treatment, which have shown to be effective, HIV infections continue to proliferate, highlighting the great need for a vaccine. Here, we provide a brief history for the HIV vaccine field, with the most recent disappointments and advancements. We also provide an update on current passive immunity trials, testing proof of the concept of the most clinically advanced broadly neutralizing monoclonal antibodies for HIV prevention. Finally, we include mucosal immunity, the importance of vaccine-elicited immune responses and the challenges thereof in the most vulnerable environment–the female genital tract and the rectal surfaces of the gastrointestinal tract for heterosexual and men who have sex with men transmissions, respectively.
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Affiliation(s)
- Parveen Sobia
- Centre for the AIDS Programme of Research in South Africa (CAPRISA), Nelson Mandela School of Medicine, University of KwaZulu-Natal, Durban 4001, South Africa;
| | - Derseree Archary
- Centre for the AIDS Programme of Research in South Africa (CAPRISA), Nelson Mandela School of Medicine, University of KwaZulu-Natal, Durban 4001, South Africa;
- Department of Medical Microbiology, University of KwaZulu-Natal, Durban 4001, South Africa
- Correspondence: ; Tel.: +27-(0)-31-655-0540
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32
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Ye R, Cao C, Xue Y. Enhancer RNA: biogenesis, function, and regulation. Essays Biochem 2020; 64:883-94. [PMID: 33034351 DOI: 10.1042/EBC20200014] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 09/02/2020] [Accepted: 09/23/2020] [Indexed: 12/30/2022]
Abstract
Enhancers are noncoding DNA elements that are present upstream or downstream of a gene to control its spatial and temporal expression. Specific histone modifications, such as monomethylation on histone H3 lysine 4 (H3K4me1) and H3K27ac, have been widely used to assign enhancer regions in mammalian genomes. In recent years, emerging evidence suggests that active enhancers are bidirectionally transcribed to produce enhancer RNAs (eRNAs). This finding not only adds a new reliable feature to define enhancers but also raises a fundamental question of how eRNAs function to activate transcription. Although some believe that eRNAs are merely transcriptional byproducts, many studies have demonstrated that eRNAs execute crucial tasks in regulating chromatin conformation and transcription activation. In this review, we summarize the current understanding of eRNAs from their biogenesis, functions, and regulation to their pathological significance. Additionally, we discuss the challenges and possible mechanisms of eRNAs in regulated transcription.
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33
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Duan Z, Baughn LB, Wang X, Zhang Y, Gupta V, MacCarthy T, Scharff MD, Yu G. Role of Dot1L and H3K79 methylation in regulating somatic hypermutation of immunoglobulin genes. Proc Natl Acad Sci U S A 2021; 118:e2104013118. [PMID: 34253616 DOI: 10.1073/pnas.2104013118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [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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Kasprzyk ME, Sura W, Dzikiewicz-Krawczyk A. Enhancing B-Cell Malignancies-On Repurposing Enhancer Activity towards Cancer. Cancers (Basel) 2021; 13:3270. [PMID: 34210001 PMCID: PMC8269369 DOI: 10.3390/cancers13133270] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 06/24/2021] [Accepted: 06/28/2021] [Indexed: 01/19/2023] Open
Abstract
B-cell lymphomas and leukemias derive from B cells at various stages of maturation and are the 6th most common cancer-related cause of death. While the role of several oncogenes and tumor suppressors in the pathogenesis of B-cell neoplasms was established, recent research indicated the involvement of non-coding, regulatory sequences. Enhancers are DNA elements controlling gene expression in a cell type- and developmental stage-specific manner. They ensure proper differentiation and maturation of B cells, resulting in production of high affinity antibodies. However, the activity of enhancers can be redirected, setting B cells on the path towards cancer. In this review we discuss different mechanisms through which enhancers are exploited in malignant B cells, from the well-studied translocations juxtaposing oncogenes to immunoglobulin loci, through enhancer dysregulation by sequence variants and mutations, to enhancer hijacking by viruses. We also highlight the potential of therapeutic targeting of enhancers as a direction for future investigation.
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35
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Bello A, Jungnickel B. Impact of Chk1 dosage on somatic hypermutation in vivo. Immunol Cell Biol 2021; 99:879-893. [PMID: 34042197 DOI: 10.1111/imcb.12480] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 04/19/2021] [Accepted: 05/24/2021] [Indexed: 12/14/2022]
Abstract
Checkpoint signaling in the context of a functional DNA damage response is crucial for the prevention of oncogenic transformation of cells. Our immune system, though, takes the risk of attenuated checkpoint responses during immunoglobulin diversification. B cells undergo continuous DNA damage and error-prone repair of their immunoglobulin genes during the process of somatic hypermutation. An accompanying attenuation of the DNA damage response via the ATR-Chk1 axis in B cells is believed to allow for a better DNA damage tolerance and for evasion of apoptosis, so as to ensure mutations to be passed on. We sought to determine whether the downregulation of Chk1 could also directly influence the process of hypermutation in vivo by altering the relative activity of error-prone DNA repair pathways. We analyzed the humoral response and the hypermutation process in mice whose B cells express reduced levels of the Chk1 protein. We found that Chk1 heterozygosity limits the accumulation of mutations in the immunoglobulin loci, likely by impacting on the survival of B cells as they accumulate DNA damage. Nevertheless, we unveiled an unanticipated role for Chk1 downregulation in favoring A/T mutagenesis at the antibody-variable regions during hypermutation. Even though immunoglobulin mutagenesis was found to be reduced, Chk1 signaling attenuation allows for sustained mutagenesis outside the immunoglobulin loci. Our study thus reveals that a proper Chk1 dosage is crucial for adequate somatic hypermutation in B cells.
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Affiliation(s)
- Amanda Bello
- Department of Cell Biology, Institute of Biochemistry and Biophysics, School of Biological Sciences, Friedrich Schiller University, Jena, Germany
| | - Berit Jungnickel
- Department of Cell Biology, Institute of Biochemistry and Biophysics, School of Biological Sciences, Friedrich Schiller University, Jena, Germany
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Begum NA, Haque F, Stanlie A, Husain A, Mondal S, Nakata M, Taniguchi T, Taniguchi H, Honjo T. Phf5a regulates DNA repair in class switch recombination via p400 and histone H2A variant deposition. EMBO J 2021; 40:e106393. [PMID: 33938017 PMCID: PMC8204862 DOI: 10.15252/embj.2020106393] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 03/15/2021] [Accepted: 03/22/2021] [Indexed: 11/09/2022] Open
Abstract
Antibody class switch recombination (CSR) is a locus-specific genomic rearrangement mediated by switch (S) region transcription, activation-induced cytidine deaminase (AID)-induced DNA breaks, and their resolution by non-homologous end joining (NHEJ)-mediated DNA repair. Due to the complex nature of the recombination process, numerous cofactors are intimately involved, making it important to identify rate-limiting factors that impact on DNA breaking and/or repair. Using an siRNA-based loss-of-function screen of genes predicted to encode PHD zinc-finger-motif proteins, we identify the splicing factor Phf5a/Sf3b14b as a novel modulator of the DNA repair step of CSR. Loss of Phf5a severely impairs AID-induced recombination, but does not perturb DNA breaks and somatic hypermutation. Phf5a regulates NHEJ-dependent DNA repair by preserving chromatin integrity to elicit optimal DNA damage response and subsequent recruitment of NHEJ factors at the S region. Phf5a stabilizes the p400 histone chaperone complex at the locus, which in turn promotes deposition of H2A variant such as H2AX and H2A.Z that are critical for the early DNA damage response and NHEJ, respectively. Depletion of Phf5a or p400 blocks the repair of both AID- and I-SceI-induced DNA double-strand breaks, supporting an important contribution of this axis to programmed as well as aberrant recombination.
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Affiliation(s)
- Nasim A Begum
- Department of Immunology and Genomic MedicineGraduate School of MedicineKyoto UniversityKyotoJapan
| | - Farazul Haque
- Department of Immunology and Genomic MedicineGraduate School of MedicineKyoto UniversityKyotoJapan
| | - Andre Stanlie
- Department of Immunology and Genomic MedicineGraduate School of MedicineKyoto UniversityKyotoJapan
- BioMedicine DesignPfizer Inc.CambridgeMAUSA
| | - Afzal Husain
- Department of Immunology and Genomic MedicineGraduate School of MedicineKyoto UniversityKyotoJapan
- Department of BiochemistryFaculty of Life SciencesAligarh Muslim UniversityAligarhIndia
| | - Samiran Mondal
- Department of Immunology and Genomic MedicineGraduate School of MedicineKyoto UniversityKyotoJapan
- Department of ChemistryRammohan CollegeKolkataIndia
| | - Mikiyo Nakata
- Department of Immunology and Genomic MedicineGraduate School of MedicineKyoto UniversityKyotoJapan
| | - Takako Taniguchi
- Division of Disease ProteomicsInstitute for Enzyme ResearchUniversity of TokushimaTokushimaJapan
| | - Hisaaki Taniguchi
- Division of Disease ProteomicsInstitute for Enzyme ResearchUniversity of TokushimaTokushimaJapan
| | - Tasuku Honjo
- Department of Immunology and Genomic MedicineGraduate School of MedicineKyoto UniversityKyotoJapan
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37
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Oppezzo P, Navarrete M, Chiorazzi N. AID in Chronic Lymphocytic Leukemia: Induction and Action During Disease Progression. Front Oncol 2021; 11:634383. [PMID: 34041018 PMCID: PMC8141630 DOI: 10.3389/fonc.2021.634383] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 02/23/2021] [Indexed: 12/12/2022] Open
Abstract
The enzyme activation-induced cytidine deaminase (AID) initiates somatic hypermutation (SHM) and class switch recombination (CSR) of immunoglobulin (Ig) genes, critical actions for an effective adaptive immune response. However, in addition to the benefits generated by its physiological roles, AID is an etiological factor for the development of human and murine leukemias and lymphomas. This review highlights the pathological role of AID and the consequences of its actions on the development, progression, and therapeutic refractoriness of chronic lymphocytic leukemia (CLL) as a model disease for mature lymphoid malignancies. First, we summarize pertinent aspects of the expression and function of AID in normal B lymphocytes. Then, we assess putative causes for AID expression in leukemic cells emphasizing the role of an activated microenvironment. Thirdly, we discuss the role of AID in lymphomagenesis, in light of recent data obtained by NGS analyses on the genomic landscape of leukemia and lymphomas, concentrating on the frequency of AID signatures in these cancers and correlating previously described tumor-gene drivers with the presence of AID off-target mutations. Finally, we discuss how these changes could affect tumor suppressor and proto-oncogene targets and how they could be associated with disease progression. Collectively, we hope that these sections will help to better understand the complex paradox between the physiological role of AID in adaptive immunity and its potential causative activity in B-cell malignancies.
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Affiliation(s)
- Pablo Oppezzo
- Research Laboratory on Chronic Lymphocytic Leukemia, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | | | - Nicholas Chiorazzi
- The Karches Center for Oncology Research, The Feinstein Institutes for Medical Research, New York, NY, United States
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38
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Tang C, MacCarthy T. Characterization of DNA G-Quadruplex Structures in Human Immunoglobulin Heavy Variable (IGHV) Genes. Front Immunol 2021; 12:671944. [PMID: 34040612 PMCID: PMC8141862 DOI: 10.3389/fimmu.2021.671944] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 04/12/2021] [Indexed: 11/21/2022] Open
Abstract
Activation-induced deaminase (AID) is a key enzyme involved in antibody diversification by initiating somatic hypermutation (SHM) and class-switch recombination (CSR) of the Immunoglobulin (Ig) loci. AID preferentially targets WRC (W=A/T, R=A/G) hotspot motifs and avoids SYC (S=C/G, Y=C/T) coldspots. G-quadruplex (G4) structures are four-stranded DNA secondary structures with key functions in transcription, translation and replication. In vitro studies have shown G4s to form and bind AID in Ig switch (S) regions. Alterations in the gene encoding AID can further disrupt AID-G4 binding and reduce CSR in vivo. However, it is still unclear whether G4s form in the variable (V) region, or how they may affect SHM. To assess the possibility of G4 formation in human V regions, we analyzed germline human Ig heavy chain V (IGHV) sequences, using a pre-trained deep learning model that predicts G4 potential. This revealed that many genes from the IGHV3 and IGHV4 families are predicted to have high G4 potential in the top and bottom strand, respectively. Different IGHV alleles also showed variability in G4 potential. Using a high-resolution (G4-seq) dataset of biochemically confirmed potential G4s in IGHV genes, we validated our computational predictions. G4-seq also revealed variation between S and V regions in the distribution of potential G4s, with the V region having overall reduced G4 abundance compared to the S region. The density of AGCT motifs, where two AGC hotspots overlap on both strands, was roughly 2.6-fold greater in the V region than the Constant (C) region, which does not mutate despite having predicted G4s at similar levels. However, AGCT motifs in both V and C regions were less abundant than in S regions. In silico mutagenesis experiments showed that G4 potentials were generally robust to mutation, although large deviations from germline states were found, mostly in framework regions. G4 potential is also associated with higher mutability of certain WRC hotspots on the same strand. In addition, CCC coldspots opposite a predicted G4 were shown to be targeted significantly more for mutation. Our overall assessment reveals plausible evidence of functional G4s forming in the Ig V region.
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Affiliation(s)
- Catherine Tang
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY, United States
| | - Thomas MacCarthy
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY, United States.,Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY, United States
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39
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Alvarez-Gonzalez J, Yasgar A, Maul RW, Rieffer AE, Crawford DJ, Salamango DJ, Dorjsuren D, Zakharov AV, Jansen DJ, Rai G, Marugan J, Simeonov A, Harris RS, Kohli RM, Gearhart PJ. Small Molecule Inhibitors of Activation-Induced Deaminase Decrease Class Switch Recombination in B Cells. ACS Pharmacol Transl Sci 2021; 4:1214-1226. [PMID: 34151211 DOI: 10.1021/acsptsci.1c00064] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Indexed: 11/30/2022]
Abstract
Activation-induced deaminase (AID) not only mutates DNA within the immunoglobulin loci to generate antibody diversity, but it also promotes development of B cell lymphomas. To tame this mutagen, we performed a quantitative high-throughput screen of over 90 000 compounds to see if AID activity could be mitigated. The enzymatic activity was assessed in biochemical assays to detect cytosine deamination and in cellular assays to measure class switch recombination. Three compounds showed promise via inhibition of switching in a transformed B cell line and in murine splenic B cells. These compounds have similar chemical structures, which suggests a shared mechanism of action. Importantly, the inhibitors blocked AID, but not a related cytosine DNA deaminase, APOBEC3B. We further determined that AID was continually expressed for several days after B cell activation to induce switching. This first report of small molecules that inhibit AID can be used to gain regulatory control over base editors.
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Affiliation(s)
- Juan Alvarez-Gonzalez
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21224, United States
| | - Adam Yasgar
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20816, United States
| | - Robert W Maul
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21224, United States
| | - Amanda E Rieffer
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States.,Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, United States.,Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Daniel J Crawford
- Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Daniel J Salamango
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States.,Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, United States.,Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Dorjbal Dorjsuren
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20816, United States
| | - Alexey V Zakharov
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20816, United States
| | - Daniel J Jansen
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20816, United States
| | - Ganesha Rai
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20816, United States
| | - Juan Marugan
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20816, United States
| | - Anton Simeonov
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland 20816, United States
| | - Reuben S Harris
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States.,Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, United States.,Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota 55455, United States.,Howard Hughes Medical Institute, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Rahul M Kohli
- Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Patricia J Gearhart
- Laboratory of Molecular Biology and Immunology, National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21224, United States
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40
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Zheng S, Matthews AJ, Rahman N, Herrick-Reynolds K, Sible E, Choi JE, Wishnie A, Ng YK, Rhodes D, Elledge SJ, Vuong BQ. The uncharacterized SANT and BTB domain-containing protein SANBR inhibits class switch recombination. J Biol Chem 2021; 296:100625. [PMID: 33831416 PMCID: PMC8141524 DOI: 10.1016/j.jbc.2021.100625] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 03/26/2021] [Accepted: 03/31/2021] [Indexed: 01/21/2023] Open
Abstract
Class switch recombination (CSR) is the process by which B cells switch production from IgM/IgD to other immunoglobulin isotypes, enabling them to mount an effective immune response against pathogens. Timely resolution of CSR prevents damage due to an uncontrolled and prolonged immune response. While many positive regulators of CSR have been described, negative regulators of CSR are relatively unknown. Using an shRNA library screen targeting more than 28,000 genes in a mouse B cell line, we have identified a novel, uncharacterized protein of 82kD (KIAA1841, NM_027860), which we have named SANBR (SANT and BTB domain regulator of CSR), as a negative regulator of CSR. The purified, recombinant BTB domain of SANBR exhibited characteristic properties such as homodimerization and interaction with corepressor proteins, including HDAC and SMRT. Overexpression of SANBR inhibited CSR in primary mouse splenic B cells, and inhibition of CSR is dependent on the BTB domain while the SANT domain is largely dispensable. Thus, we have identified a new member of the BTB family that serves as a negative regulator of CSR. Future investigations to identify transcriptional targets of SANBR in B cells will reveal further insights into the specific mechanisms by which SANBR regulates CSR as well as fundamental gene regulatory activities of this protein.
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Affiliation(s)
- Simin Zheng
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA; NTU Institute of Structural Biology, Nanyang Technological University, Singapore, Singapore
| | - Allysia J Matthews
- Yale School of Medicine, Yale University, New Haven, Connecticut, USA; Department of Biology, The Graduate Center and The City College of New York, New York, New York, USA
| | - Numa Rahman
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | | | - Emily Sible
- Department of Biology, The Graduate Center and The City College of New York, New York, New York, USA
| | - Jee Eun Choi
- Department of Biology, The Graduate Center and The City College of New York, New York, New York, USA
| | - Alec Wishnie
- Department of Biology, The Graduate Center and The City College of New York, New York, New York, USA
| | - Yan Kee Ng
- NTU Institute of Structural Biology, Nanyang Technological University, Singapore, Singapore
| | - Daniela Rhodes
- NTU Institute of Structural Biology, Nanyang Technological University, Singapore, Singapore
| | - Stephen J Elledge
- Department of Genetics, Program in Virology, Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts, USA; Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Bao Q Vuong
- Department of Biology, The Graduate Center and The City College of New York, New York, New York, USA.
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41
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Chen XS. Insights into the Structures and Multimeric Status of APOBEC Proteins Involved in Viral Restriction and Other Cellular Functions. Viruses 2021; 13:497. [PMID: 33802945 DOI: 10.3390/v13030497] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 03/15/2021] [Accepted: 03/15/2021] [Indexed: 12/16/2022] Open
Abstract
Apolipoprotein B mRNA editing catalytic polypeptide-like (APOBEC) proteins belong to a family of deaminase proteins that can catalyze the deamination of cytosine to uracil on single-stranded DNA or/and RNA. APOBEC proteins are involved in diverse biological functions, including adaptive and innate immunity, which are critical for restricting viral infection and endogenous retroelements. Dysregulation of their functions can cause undesired genomic mutations and RNA modification, leading to various associated diseases, such as hyper-IgM syndrome and cancer. This review focuses on the structural and biochemical data on the multimerization status of individual APOBECs and the associated functional implications. Many APOBECs form various multimeric complexes, and multimerization is an important way to regulate functions for some of these proteins at several levels, such as deaminase activity, protein stability, subcellular localization, protein storage and activation, virion packaging, and antiviral activity. The multimerization of some APOBECs is more complicated than others, due to the associated complex RNA binding modes.
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Abstract
B cells constitute a main branch adaptive immune system. They mediate host defence through the production of high-affinity antibodies against an enormous diversity of foreign antigens. Remarkably, B cells undergo multiple types of somatic DNA mutation to achieve this effector function, including class switch recombination (CSR) and somatic hypermutation (SHM). These processes occur in response to antigen recognition and inflammatory signals, and require strict biological control at multiple levels. Transcription within the locus that encodes antibodies plays direct roles in CSR. Additional non-coding RNAs (ncRNAs), including both microRNAs (miRNAs) and long ncRNAs (lncRNAs), also play pivotal roles in B cell activation and terminal effector function through post-transcriptional gene regulation and chromatin remodelling, respectively.
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Affiliation(s)
- Eric J Wigton
- Department of Microbiology & Immunology, Sandler Asthma Basic Research Center, University of California San Francisco, San Francisco, CA, USA
| | - K Mark Ansel
- Department of Microbiology & Immunology, Sandler Asthma Basic Research Center, University of California San Francisco, San Francisco, CA, USA
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43
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Laffleur B, Lim J, Zhang W, Chen Y, Pefanis E, Bizarro J, Batista CR, Wu L, Economides AN, Wang J, Basu U. Noncoding RNA processing by DIS3 regulates chromosomal architecture and somatic hypermutation in B cells. Nat Genet 2021; 53:230-242. [PMID: 33526923 PMCID: PMC8011275 DOI: 10.1038/s41588-020-00772-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 12/21/2020] [Indexed: 01/30/2023]
Abstract
Noncoding RNAs are exquisitely titrated by the cellular RNA surveillance machinery for regulating diverse biological processes. The RNA exosome, the predominant 3' RNA exoribonuclease in mammalian cells, is composed of nine core and two catalytic subunits. Here, we developed a mouse model with a conditional allele to study the RNA exosome catalytic subunit DIS3. In DIS3-deficient B cells, integrity of the immunoglobulin heavy chain (Igh) locus in its topologically associating domain is affected, with accumulation of DNA-associated RNAs flanking CTCF-binding elements, decreased CTCF binding to CTCF-binding elements and disorganized cohesin localization. DIS3-deficient B cells also accumulate activation-induced cytidine deaminase-mediated asymmetric nicks, altering somatic hypermutation patterns and increasing microhomology-mediated end-joining DNA repair. Altered mutation patterns and Igh architectural defects in DIS3-deficient B cells lead to decreased class-switch recombination but increased chromosomal translocations. Our observations of DIS3-mediated architectural regulation at the Igh locus are reflected genome wide, thus providing evidence that noncoding RNA processing is an important mechanism for controlling genome organization.
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Affiliation(s)
- Brice Laffleur
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Junghyun Lim
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Department of Pharmacy, School of Pharmacy, Jeonbuk National University, Jeonju, South Korea
| | - Wanwei Zhang
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Yiyun Chen
- Division of Life Science, Department of Chemical and Biological Engineering, Center for Systems Biology and Human Health, and State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Hong Kong, China
| | - Evangelos Pefanis
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Regeneron Pharmaceuticals, Tarrytown, NY, USA
| | - Jonathan Bizarro
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Carolina R Batista
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Lijing Wu
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | | | - Jiguang Wang
- Division of Life Science, Department of Chemical and Biological Engineering, Center for Systems Biology and Human Health, and State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Hong Kong, China
| | - Uttiya Basu
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA.
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44
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Krasnopolsky S, Novikov A, Kuzmina A, Taube R. CRISPRi-mediated depletion of Spt4 and Spt5 reveals a role for DSIF in the control of HIV latency. Biochim Biophys Acta Gene Regul Mech 2020; 1864:194656. [PMID: 33333262 DOI: 10.1016/j.bbagrm.2020.194656] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 11/15/2020] [Accepted: 11/16/2020] [Indexed: 01/03/2023]
Abstract
Pivotal studies on the control of HIV transcription has laid the foundations for our understanding of how metazoan transcription is executed, and what are the factors that control this step. Part of this work established a role for DRB Sensitivity Inducing Factor (DSIF), consisting of Spt4 and Spt5, in promoting pause-release of RNA Polymerase II (Pol II) for optimal elongation. However, while there has been substantial progress in understanding the role of DSIF in mediating HIV gene transcription, its involvement in establishing viral latency has not been explored. Moreover, the effects of depleting Spt4 or Spt5, or simultaneously knocking down both subunits of DSIF have not been examined. In this study, we employed CRISPR interference (CRIPSRi) to knockdown the expression of Spt4, Spt5 or the entire DSIF complex, and monitored effects on HIV transcription and viral latency. Knocking down DSIF, or each of its subunits, inhibited HIV transcription, primarily at the step of Tat transactivation. This was accompanied by a decrease in promoter occupancy of Pol II and Cdk9, and to a lesser extent, AFF4. Interestingly, targeting the expression of one subunit of DSIF, reduced the protein stability of its counterpart partner. Moreover, depletion of Spt4, Spt5 or DSIF complex impaired cell growth, but did not cause cell death. Finally, knockdown of Spt4, Spt5 or DSIF, facilitated entry of HIV into latency. We conclude that each DSIF subunit plays a role in maintaining the stability of its other partner, achieving optimal function of the DSIF to enhance viral gene transcription.
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Affiliation(s)
- Simona Krasnopolsky
- The Shraga Segal Department of Microbiology Immunology and Genetics Faculty of Health Sciences, Ben-Gurion University of the Negev, Israel
| | - Alex Novikov
- The Shraga Segal Department of Microbiology Immunology and Genetics Faculty of Health Sciences, Ben-Gurion University of the Negev, Israel
| | - Alona Kuzmina
- The Shraga Segal Department of Microbiology Immunology and Genetics Faculty of Health Sciences, Ben-Gurion University of the Negev, Israel
| | - Ran Taube
- The Shraga Segal Department of Microbiology Immunology and Genetics Faculty of Health Sciences, Ben-Gurion University of the Negev, Israel.
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45
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Yewdell WT, Kim Y, Chowdhury P, Lau CM, Smolkin RM, Belcheva KT, Fernandez KC, Cols M, Yen WF, Vaidyanathan B, Angeletti D, McDermott AB, Yewdell JW, Sun JC, Chaudhuri J. A Hyper-IgM Syndrome Mutation in Activation-Induced Cytidine Deaminase Disrupts G-Quadruplex Binding and Genome-wide Chromatin Localization. Immunity 2020; 53:952-970.e11. [PMID: 33098766 DOI: 10.1016/j.immuni.2020.10.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 07/27/2020] [Accepted: 10/06/2020] [Indexed: 01/04/2023]
Abstract
Precise targeting of activation-induced cytidine deaminase (AID) to immunoglobulin (Ig) loci promotes antibody class switch recombination (CSR) and somatic hypermutation (SHM), whereas AID targeting of non-Ig loci can generate oncogenic DNA lesions. Here, we examined the contribution of G-quadruplex (G4) nucleic acid structures to AID targeting in vivo. Mice bearing a mutation in Aicda (AIDG133V) that disrupts AID-G4 binding modeled the pathology of hyper-IgM syndrome patients with an orthologous mutation, lacked CSR and SHM, and had broad defects in genome-wide AIDG133V chromatin localization. Genome-wide analyses also revealed that wild-type AID localized to MHCII genes, and AID expression correlated with decreased MHCII expression in germinal center B cells and diffuse large B cell lymphoma. Our findings indicate a crucial role for G4 binding in AID targeting and suggest that AID activity may extend beyond Ig loci to regulate the expression of genes relevant to the physiology and pathology of activated B cells.
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46
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Abstract
The transcription elongation factor Spt5 is conserved from bacteria to humans. In eukaryotes, Spt5 forms a complex with Spt4 and regulates processive transcription elongation. Recent studies on transcription elongation suggest different mechanistic roles in yeast versus mammals. Higher eukaryotes utilize Spt4-Spt5 (DSIF) to regulate promoter-proximal pausing, a transcription-regulatory mechanism that connects initiation to productive elongation. DSIF is a versatile transcription factor and has been implicated in both gene-specific regulation and transcription through nucleosomes. Future studies will further elucidate the role of DSIF in transcriptional dynamics and disentangle its inhibitory and enhancing activities in transcription.
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Affiliation(s)
- Tim-Michael Decker
- Department of Biochemistry, University of Colorado, 3415 Colorado Ave, Boulder, CO 80303, USA.
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47
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Obara EAA, Aguilar-Morante D, Rasmussen RD, Frias A, Vitting-Serup K, Lim YC, Elbæk KJ, Pedersen H, Vardouli L, Jensen KE, Skjoth-Rasmussen J, Brennum J, Tuckova L, Strauss R, Dinant C, Bartek J, Hamerlik P. SPT6-driven error-free DNA repair safeguards genomic stability of glioblastoma cancer stem-like cells. Nat Commun 2020; 11:4709. [PMID: 32948765 DOI: 10.1038/s41467-020-18549-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Accepted: 09/01/2020] [Indexed: 02/07/2023] Open
Abstract
Glioblastoma cancer-stem like cells (GSCs) display marked resistance to ionizing radiation (IR), a standard of care for glioblastoma patients. Mechanisms underpinning radio-resistance of GSCs remain largely unknown. Chromatin state and the accessibility of DNA lesions to DNA repair machineries are crucial for the maintenance of genomic stability. Understanding the functional impact of chromatin remodeling on DNA repair in GSCs may lay the foundation for advancing the efficacy of radio-sensitizing therapies. Here, we present the results of a high-content siRNA microscopy screen, revealing the transcriptional elongation factor SPT6 to be critical for the genomic stability and self-renewal of GSCs. Mechanistically, SPT6 transcriptionally up-regulates BRCA1 and thereby drives an error-free DNA repair in GSCs. SPT6 loss impairs the self-renewal, genomic stability and tumor initiating capacity of GSCs. Collectively, our results provide mechanistic insights into how SPT6 regulates DNA repair and identify SPT6 as a putative therapeutic target in glioblastoma. Cancer stem cells can evade treatment. Here, the authors perform an in vitro screen to identify proteins that are involved in protecting glioma cancer stem cells from therapy and find that SPT6 increases BRCA1 expression and drives error-free DNA repair, thereby ensuring the survival of the cells.
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48
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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49
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Yen WF, Sharma R, Cols M, Lau CM, Chaudhry A, Chowdhury P, Yewdell WT, Vaidyanathan B, Sun A, Coffre M, Pucella JN, Chen CC, Jasin M, Sun JC, Rudensky AY, Koralov SB, Chaudhuri J. Distinct Requirements of CHD4 during B Cell Development and Antibody Response. Cell Rep 2020; 27:1472-1486.e5. [PMID: 31042474 PMCID: PMC6527137 DOI: 10.1016/j.celrep.2019.04.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 03/15/2019] [Accepted: 04/01/2019] [Indexed: 11/21/2022] Open
Abstract
The immunoglobulin heavy chain (Igh) locus features a dynamic chromatin landscape to promote class switch recombination (CSR), yet the mechanisms that regulate this landscape remain poorly understood. CHD4, a component of the chromatin remodeling NuRD complex, directly binds H3K9me3, an epigenetic mark present at the Igh locus during CSR. We find that CHD4 is essential for early B cell development but is dispensable for the homeostatic maintenance of mature, naive B cells. However, loss of CHD4 in mature B cells impairs CSR because of suboptimal targeting of AID to the Igh locus. Additionally, we find that CHD4 represses p53 expression to promote B cell proliferation. This work reveals distinct roles for CHD4 in B cell development and CSR and links the H3K9me3 epigenetic mark with AID recruitment to the Igh locus. Yen et al. demonstrate that CHD4, a component of the NuRD remodeling complex, is essential for early B cell development, represses p53 expression in mature B cells, and influences the recruitment of AID to DNA during class switch recombination.
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Affiliation(s)
- Wei-Feng Yen
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA; Biochemistry, Cellular and Molecular Biology Program, Weill Graduate School of Medical Sciences, New York, NY, USA
| | - Rahul Sharma
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Montserrat Cols
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Colleen M Lau
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Ashutosh Chaudhry
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Priyanka Chowdhury
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA; Immunology and Microbial Pathogenesis Program, Weill Cornell Graduate School of Medical Sciences, New York, NY, USA
| | - William T Yewdell
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Bharat Vaidyanathan
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA; Immunology and Microbial Pathogenesis Program, Weill Cornell Graduate School of Medical Sciences, New York, NY, USA
| | - Amy Sun
- Department of Pathology, New York University School of Medicine, New York, NY, USA
| | - Maryaline Coffre
- Department of Pathology, New York University School of Medicine, New York, NY, USA
| | - Joseph N Pucella
- Gerstner Sloan Kettering Graduate School of Biomedical Sciences, New York, NY, USA
| | - Chun-Chin Chen
- Biochemistry, Cellular and Molecular Biology Program, Weill Graduate School of Medical Sciences, New York, NY, USA; Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Maria Jasin
- Biochemistry, Cellular and Molecular Biology Program, Weill Graduate School of Medical Sciences, New York, NY, USA; Gerstner Sloan Kettering Graduate School of Biomedical Sciences, New York, NY, USA; Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Joseph C Sun
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA; Immunology and Microbial Pathogenesis Program, Weill Cornell Graduate School of Medical Sciences, New York, NY, USA; Gerstner Sloan Kettering Graduate School of Biomedical Sciences, New York, NY, USA
| | - Alexander Y Rudensky
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA; Immunology and Microbial Pathogenesis Program, Weill Cornell Graduate School of Medical Sciences, New York, NY, USA; Gerstner Sloan Kettering Graduate School of Biomedical Sciences, New York, NY, USA; Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Sergei B Koralov
- Department of Pathology, New York University School of Medicine, New York, NY, USA
| | - Jayanta Chaudhuri
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA; Immunology and Microbial Pathogenesis Program, Weill Cornell Graduate School of Medical Sciences, New York, NY, USA; Gerstner Sloan Kettering Graduate School of Biomedical Sciences, New York, NY, USA.
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50
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Branton SA, Ghorbani A, Bolt BN, Fifield H, Berghuis LM, Larijani M. Activation-induced cytidine deaminase can target multiple topologies of double-stranded DNA in a transcription-independent manner. FASEB J 2020; 34:9245-9268. [PMID: 32437054 DOI: 10.1096/fj.201903036rr] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 04/20/2020] [Accepted: 04/24/2020] [Indexed: 12/30/2022]
Abstract
Activation-induced cytidine deaminase (AID) mutates immunoglobulin genes and acts genome-wide. AID targets robustly transcribed genes, and purified AID acts on single-stranded (ss) but not double-stranded (ds) DNA oligonucleotides. Thus, it is believed that transcription is the generator of ssDNA for AID. Previous cell-free studies examining the relationship between transcription and AID targeting have employed a bacterial colony count assay wherein AID reverts an antibiotic resistance stop codon in plasmid substrates, leading to colony formation. Here, we established a novel assay where kb-long dsDNA of varying topologies is incubated with AID, with or without transcription, followed by direct sequencing. This assay allows for an unselected and in-depth comparison of mutation frequency and pattern of AID targeting in the absence of transcription or across a range of transcription dynamics. We found that without transcription, AID targets breathing ssDNA in supercoiled and, to a lesser extent, in relaxed dsDNA. The most optimal transcription only modestly enhanced AID action on supercoiled dsDNA in a manner dependent on RNA polymerase speed. These data suggest that the correlation between transcription and AID targeting may reflect transcription leading to AID-accessible breathing ssDNA patches naturally occurring in de-chromatinized dsDNA, as much as being due to transcription directly generating ssDNA.
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Affiliation(s)
- Sarah A Branton
- Program in Immunology and Infectious Diseases, Department of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Atefeh Ghorbani
- Program in Immunology and Infectious Diseases, Department of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Brittany N Bolt
- Program in Immunology and Infectious Diseases, Department of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Heather Fifield
- Program in Immunology and Infectious Diseases, Department of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Lesley M Berghuis
- Program in Immunology and Infectious Diseases, Department of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Mani Larijani
- Program in Immunology and Infectious Diseases, Department of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada.,Department of Molecular Biology and Biochemistry, Faculty of Science, Simon Fraser University, Burnaby, BC, Canada
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