1
|
Della Mina E, Jackson KJL, Crawford AJI, Faulks ML, Pathmanandavel K, Acquarola N, O'Sullivan M, Kerre T, Naesens L, Claes K, Goodnow CC, Haerynck F, Kracker S, Meyts I, D'Orsogna LJ, Ma CS, Tangye SG. A Novel Heterozygous Variant in AICDA Impairs Ig Class Switching and Somatic Hypermutation in Human B Cells and is Associated with Autosomal Dominant HIGM2 Syndrome. J Clin Immunol 2024; 44:66. [PMID: 38363477 PMCID: PMC10873450 DOI: 10.1007/s10875-024-01665-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2023] [Accepted: 01/21/2024] [Indexed: 02/17/2024]
Abstract
B cells and their secreted antibodies are fundamental for host-defense against pathogens. The generation of high-affinity class switched antibodies results from both somatic hypermutation (SHM) of the immunoglobulin (Ig) variable region genes of the B-cell receptor and class switch recombination (CSR) which alters the Ig heavy chain constant region. Both of these processes are initiated by the enzyme activation-induced cytidine deaminase (AID), encoded by AICDA. Deleterious variants in AICDA are causal of hyper-IgM syndrome type 2 (HIGM2), a B-cell intrinsic primary immunodeficiency characterised by recurrent infections and low serum IgG and IgA levels. Biallelic variants affecting exons 2, 3 or 4 of AICDA have been identified that impair both CSR and SHM in patients with autosomal recessive HIGM2. Interestingly, B cells from patients with autosomal dominant HIGM2, caused by heterozygous variants (V186X, R190X) located in AICDA exon 5 encoding the nuclear export signal (NES) domain, show abolished CSR but variable SHM. We herein report the immunological and functional phenotype of two related patients presenting with common variable immunodeficiency who were found to have a novel heterozygous variant in AICDA (L189X). This variant led to a truncated AID protein lacking the last 10 amino acids of the NES at the C-terminal domain. Interestingly, patients' B cells carrying the L189X variant exhibited not only greatly impaired CSR but also SHM in vivo, as well as CSR and production of IgG and IgA in vitro. Our findings demonstrate that the NES domain of AID can be essential for SHM, as well as for CSR, thereby refining the correlation between AICDA genotype and SHM phenotype as well as broadening our understanding of the pathophysiology of HIGM disorders.
Collapse
Affiliation(s)
- Erika Della Mina
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW, 2010, Australia
- School of Clinical Medicine, Faculty of Medicine and Health, UNSW Sydney, Sydney, Australia
| | - Katherine J L Jackson
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW, 2010, Australia
| | - Alexander J I Crawford
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW, 2010, Australia
| | - Megan L Faulks
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW, 2010, Australia
| | - Karrnan Pathmanandavel
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW, 2010, Australia
- School of Clinical Medicine, Faculty of Medicine and Health, UNSW Sydney, Sydney, Australia
| | - Nicolino Acquarola
- Department of Clinical Immunology and PathWest, Fiona Stanley Hospital, Murdoch, WA, Australia
| | - Michael O'Sullivan
- Department of Clinical Immunology and PathWest, Fiona Stanley Hospital, Murdoch, WA, Australia
- Department of Immunology, Perth Children's Hospital, Perth, WA, Australia
| | - Tessa Kerre
- Department of Hematology, Department of Internal Medicine and Pediatrics, Ghent University, Ghent, Belgium
- Center for Primary Immunodeficiency Ghent (CPIG), Jeffrey Modell Diagnosis and Research Center, ERN Rita Network Center, Ghent University Hospital, Ghent, Belgium
| | - Leslie Naesens
- Center for Primary Immunodeficiency Ghent (CPIG), Jeffrey Modell Diagnosis and Research Center, ERN Rita Network Center, Ghent University Hospital, Ghent, Belgium
- Primary Immunodeficiency Research Lab, Department of Internal Medicine and Pediatrics, Ghent University, Ghent, Belgium
| | - Karlien Claes
- Center for Primary Immunodeficiency Ghent (CPIG), Jeffrey Modell Diagnosis and Research Center, ERN Rita Network Center, Ghent University Hospital, Ghent, Belgium
- Primary Immunodeficiency Research Lab, Department of Internal Medicine and Pediatrics, Ghent University, Ghent, Belgium
| | - Christopher C Goodnow
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW, 2010, Australia
- School of Clinical Medicine, Faculty of Medicine and Health, UNSW Sydney, Sydney, Australia
| | - Filomeen Haerynck
- Center for Primary Immunodeficiency Ghent (CPIG), Jeffrey Modell Diagnosis and Research Center, ERN Rita Network Center, Ghent University Hospital, Ghent, Belgium
- Primary Immunodeficiency Research Lab, Department of Internal Medicine and Pediatrics, Ghent University, Ghent, Belgium
| | - Sven Kracker
- Laboratory of Human Lymphohematopoiesis, INSERM UMR 1163, Imagine Institute, 75015, Paris, France
- Université Paris Cité, 75015, Paris, France
| | - Isabelle Meyts
- Inborn Errors of Immunity, Department of Microbiology, Immunology and Transplantation, KU Leuven, Louvain, Belgium
- Pediatric Immunodeficiency, Department of Pediatrics, University Hospitals Leuven, Louvain, Belgium
| | - Lloyd J D'Orsogna
- Department of Clinical Immunology and PathWest, Fiona Stanley Hospital, Murdoch, WA, Australia
- School of Medicine, University of Western Australia, Nedlands, WA, Australia
| | - Cindy S Ma
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW, 2010, Australia
- School of Clinical Medicine, Faculty of Medicine and Health, UNSW Sydney, Sydney, Australia
| | - Stuart G Tangye
- Garvan Institute of Medical Research, 384 Victoria St, Darlinghurst, NSW, 2010, Australia.
- School of Clinical Medicine, Faculty of Medicine and Health, UNSW Sydney, Sydney, Australia.
| |
Collapse
|
2
|
Skrekas C, Limeta A, Siewers V, David F. Targeted In Vivo Mutagenesis in Yeast Using CRISPR/Cas9 and Hyperactive Cytidine and Adenine Deaminases. ACS Synth Biol 2023; 12:2278-2289. [PMID: 37486333 PMCID: PMC10443040 DOI: 10.1021/acssynbio.2c00690] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Indexed: 07/25/2023]
Abstract
Directed evolution is a preferred strategy to improve the function of proteins such as enzymes that act as bottlenecks in metabolic pathways. Common directed evolution approaches rely on error-prone PCR-based libraries where the number of possible variants is usually limited by cellular transformation efficiencies. Targeted in vivo mutagenesis can advance directed evolution approaches and help to overcome limitations in library generation. In the current study, we aimed to develop a high-efficiency time-controllable targeted mutagenesis toolkit in the yeast Saccharomyces cerevisiae by employing the CRISPR/Cas9 technology. To that end, we fused the dCas9 protein with hyperactive variants of adenine and cytidine deaminases aiming to create an inducible CRISPR-based mutagenesis tool targeting a specific DNA sequence in vivo with extended editing windows and high mutagenesis efficiency. We also investigated the effect of guide RNA multiplexing on the mutagenesis efficiency both phenotypically and on the DNA level.
Collapse
Affiliation(s)
- Christos Skrekas
- Department
of Life Sciences, Chalmers University of
Technology, Gothenburg SE-41296, Sweden
| | - Angelo Limeta
- Department
of Life Sciences, Chalmers University of
Technology, Gothenburg SE-41296, Sweden
| | - Verena Siewers
- Department
of Life Sciences, Chalmers University of
Technology, Gothenburg SE-41296, Sweden
- Novo
Nordisk Foundation Center for Biosustainability, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Florian David
- Department
of Life Sciences, Chalmers University of
Technology, Gothenburg SE-41296, Sweden
| |
Collapse
|
3
|
Çakan E, Gunaydin G. Activation induced cytidine deaminase: An old friend with new faces. Front Immunol 2022; 13:965312. [PMID: 36405752 PMCID: PMC9670734 DOI: 10.3389/fimmu.2022.965312] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 10/10/2022] [Indexed: 11/25/2022] Open
Abstract
Activation induced cytidine deaminase (AID) protein is a member of APOBEC family. AID converts cytidine to uracil, which is a key step for somatic hypermutation (SHM) and class switch recombination (CSR). AID also plays critical roles in B cell precursor stages, removing polyreactive B cells from immune repertoire. Since the main function of AID is inducing point mutations, dysregulation can lead to increased mutation load, translocations, disturbed genomic integrity, and lymphomagenesis. As such, expression of AID as well as its function is controlled strictly at various molecular steps. Other members of the APOBEC family also play crucial roles during carcinogenesis. Considering all these functions, AID represents a bridge, linking chronic inflammation to carcinogenesis and immune deficiencies to autoimmune manifestations.
Collapse
Affiliation(s)
- Elif Çakan
- Hacettepe University School of Medicine, Sihhiye, Ankara, Turkey
| | - Gurcan Gunaydin
- Department of Basic Oncology, Hacettepe University Cancer Institute, Sihhiye, Ankara, Turkey
- *Correspondence: Gurcan Gunaydin,
| |
Collapse
|
4
|
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] [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.
Collapse
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
| |
Collapse
|
5
|
Dirks J, Haase G, Cantaert T, Frey L, Klaas M, Rickert CH, Girschick H, Meffre E, Morbach H. A Novel AICDA Splice-Site Mutation in Two Siblings with HIGM2 Permits Somatic Hypermutation but Abrogates Mutational Targeting. J Clin Immunol 2022; 42:771-782. [PMID: 35246784 PMCID: PMC9166864 DOI: 10.1007/s10875-022-01233-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 02/14/2022] [Indexed: 11/29/2022]
Abstract
Hyper-IgM syndrome type 2 (HIGM2) is a B cell intrinsic primary immunodeficiency caused by mutations in AICDA encoding activation-induced cytidine deaminase (AID) which impair immunoglobulin class switch recombination (CSR) and somatic hypermutation (SHM). Whereas autosomal-recessive AID-deficiency (AR-AID) affects both CSR and SHM, the autosomal-dominant form (AD-AID) due to C-terminal heterozygous variants completely abolishes CSR but only partially affects SHM. AR-AID patients display enhanced germinal center (GC) reactions and autoimmune manifestations, which are not present in AD-AID, suggesting that SHM but not CSR regulates GC reactions and peripheral B cell tolerance. Herein, we describe two siblings with HIGM2 due to a novel homozygous AICDA mutation (c.428-1G > T) which disrupts the splice acceptor site of exon 4 and results in the sole expression of a truncated AID variant that lacks 10 highly conserved amino acids encoded by exon 4 (AID-ΔE4a). AID-ΔE4a patients suffered from defective CSR and enhanced GC reactions and were therefore indistinguishable from other AR-AID patients. However, the AID-ΔE4a variant only partially affected SHM as observed in AD-AID patients. In addition, AID-ΔE4a but not AD-AID patients revealed impaired targeting of mutational hotspot motives and distorted mutational patterns. Hence, qualitative defects in AID function and altered SHM rather than global decreased SHM activity may account for the disease phenotype in these patients.
Collapse
Affiliation(s)
- Johannes Dirks
- Pediatric Immunology, University Childrens' Hospital Würzburg, Würzburg, Germany
| | - Gabriele Haase
- Pediatric Immunology, University Childrens' Hospital Würzburg, Würzburg, Germany
| | - Tineke Cantaert
- Immunology Unit, Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Lea Frey
- Institute of Pathology, Würzburg University, Würzburg, Germany
| | - Moritz Klaas
- Pediatric Rheumatology, Vivantes Hospital Friedrichshain, Berlin, Germany
| | | | - Hermann Girschick
- Pediatric Rheumatology, Vivantes Hospital Friedrichshain, Berlin, Germany
- German Center for Growth and Development "DEUZWEG", Berlin, Germany
| | - Eric Meffre
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT, USA
| | - Henner Morbach
- Pediatric Immunology, University Childrens' Hospital Würzburg, Würzburg, Germany.
- Center for Rare Diseases - Reference Center Northern Bavaria (ZESE), Würzburg, Germany.
| |
Collapse
|
6
|
Jaiswal A, Singh AK, Tamrakar A, Kodgire P. Unfolding the Role of Splicing Factors and RNA Debranching in AID Mediated Antibody Diversification. Int Rev Immunol 2020; 40:289-306. [PMID: 32924658 DOI: 10.1080/08830185.2020.1815725] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Activated B-cells diversify their antibody repertoire via somatic hypermutation (SHM) and class switch recombination (CSR). SHM is restricted to the variable region, whereas, CSR is confined to the constant region of immunoglobulin (Ig) genes. Activation-induced cytidine deaminase (AID) is a crucial player in the diversification of antibodies in the activated B-cell. AID catalyzes the deamination of cytidine (C) into uracil (U) at Ig genes. Subsequently, low fidelity repair of U:G mismatches may lead to mutations. Transcription is essential for the AID action, as it provides a transient single-strand DNA substrate. Since splicing is a co-transcriptional event, various splicing factors or regulators influence the transcription. Numerous splicing factors are known to regulate the AID targeting, function, Ig transcription, and AID splicing, which eventually influence antibody diversification processes. Splicing regulator SRSF1-3, a splicing isoform of serine arginine-rich splicing factor (SRSF1), and CTNNBL1, a spliceosome interacting factor, interact with AID and play a critical role in SHM. Likewise, a splicing regulator polypyrimidine tract binding protein-2 (PTBP2) and the debranching enzyme (DBR1) debranches primary switch transcripts which later forms G-quadruplex structures, and the S region guide RNAs direct AID to S region DNA. Moreover, AID shows several alternate splicing isoforms, like AID devoid of exon-4 (AIDΔE4) that is expressed in various pathological conditions. Interestingly, RBM5, a splicing regulator, is responsible for the skipping of AID exon 4. In this review, we discuss the role and significance of splicing factors in the AID mediated antibody diversification.
Collapse
Affiliation(s)
- Ankit Jaiswal
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Indore, Madhya Pradesh, India
| | - Amit Kumar Singh
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Indore, Madhya Pradesh, India
| | - Anubhav Tamrakar
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Indore, Madhya Pradesh, India
| | - Prashant Kodgire
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Indore, Madhya Pradesh, India
| |
Collapse
|
7
|
Fadlallah J, Chentout L, Boisson B, Pouliet A, Masson C, Morin F, Durandy A, Casanova JL, Oksenhendler E, Kracker S. From Dysgammaglobulinemia to Autosomal-Dominant Activation-Induced Cytidine Deaminase Deficiency: Unraveling an Inherited Immunodeficiency after 50 Years. J Pediatr 2020; 223:207-211.e1. [PMID: 32423680 DOI: 10.1016/j.jpeds.2020.03.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 02/17/2020] [Accepted: 03/12/2020] [Indexed: 01/16/2023]
Abstract
The genetic investigation of a family presenting with a dominant form of hyper IgM syndrome published in 1963 and 1975 revealed a R190X nonsense mutation in activation-induced cytidine deaminase. This report illustrates the progress made over 6 decades in the characterization of primary immunodeficiencies, from immunochemistry to whole-exome sequencing.
Collapse
Affiliation(s)
- Jehane Fadlallah
- Department of Clinical Immunology, Saint-Louis Hospital, Assistance Publique-Hôpitaux de Paris, and Paris Diderot University, Paris, France.
| | - Loic Chentout
- Human Lymphohematopoiesis Laboratory, Institut Imagine, Inserm U1163, Paris Descartes Sorbonne, Paris Cite University, Paris, France
| | - Bertrand Boisson
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, Inserm U1163, Paris, France; St. Giles Laboratory of Human Genetics of Infectious Diseases, The Rockefeller University, New York, NY
| | - Aurore Pouliet
- Genomics Core Facility, Institut Imagine, Inserm U1163, Paris Descartes Sorbonne, Paris Cite University, Paris, France
| | - Cecile Masson
- Bioinformatics Facility, Institut Imagine, Inserm U1163, Paris Descartes Sorbonne, Paris Cite University, Paris, France
| | - Florence Morin
- Immunology and Histocompatibility Laboratory, Saint-Louis Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Anne Durandy
- Human Lymphohematopoiesis Laboratory, Institut Imagine, Inserm U1163, Paris Descartes Sorbonne, Paris Cite University, Paris, France
| | - Jean-Laurent Casanova
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, Inserm U1163, Paris, France; St. Giles Laboratory of Human Genetics of Infectious Diseases, The Rockefeller University, New York, NY; Howard Hughes Medical Institute, New York, NY; Rockefeller University and Rockefeller University Hospital, New York, NY; Pediatric Immunology and Hematology Unit, Necker Hospital for Sick Children, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Eric Oksenhendler
- Department of Clinical Immunology, Saint-Louis Hospital, Assistance Publique-Hôpitaux de Paris, and Paris Diderot University, Paris, France
| | - Sven Kracker
- Human Lymphohematopoiesis Laboratory, Institut Imagine, Inserm U1163, Paris Descartes Sorbonne, Paris Cite University, Paris, France
| |
Collapse
|
8
|
Delviks-Frankenberry KA, Desimmie BA, Pathak VK. Structural Insights into APOBEC3-Mediated Lentiviral Restriction. Viruses 2020; 12:E587. [PMID: 32471198 PMCID: PMC7354603 DOI: 10.3390/v12060587] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 05/22/2020] [Accepted: 05/24/2020] [Indexed: 01/18/2023] Open
Abstract
Mammals have developed clever adaptive and innate immune defense mechanisms to protect against invading bacterial and viral pathogens. Human innate immunity is continuously evolving to expand the repertoire of restriction factors and one such family of intrinsic restriction factors is the APOBEC3 (A3) family of cytidine deaminases. The coordinated expression of seven members of the A3 family of cytidine deaminases provides intrinsic immunity against numerous foreign infectious agents and protects the host from exogenous retroviruses and endogenous retroelements. Four members of the A3 proteins-A3G, A3F, A3H, and A3D-restrict HIV-1 in the absence of virion infectivity factor (Vif); their incorporation into progeny virions is a prerequisite for cytidine deaminase-dependent and -independent activities that inhibit viral replication in the host target cell. HIV-1 encodes Vif, an accessory protein that antagonizes A3 proteins by targeting them for polyubiquitination and subsequent proteasomal degradation in the virus producing cells. In this review, we summarize our current understanding of the role of human A3 proteins as barriers against HIV-1 infection, how Vif overcomes their antiviral activity, and highlight recent structural and functional insights into A3-mediated restriction of lentiviruses.
Collapse
Affiliation(s)
| | | | - Vinay K. Pathak
- Viral Mutation Section, HIV Dynamics and Replication Program, National Cancer Institute at Frederick, Frederick, MD 21702, USA; (K.A.D.-F.); (B.A.D.)
| |
Collapse
|
9
|
RNA-binding motifs of hnRNP K are critical for induction of antibody diversification by activation-induced cytidine deaminase. Proc Natl Acad Sci U S A 2020; 117:11624-11635. [PMID: 32385154 DOI: 10.1073/pnas.1921115117] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Activation-induced cytidine deaminase (AID) is the key enzyme for class switch recombination (CSR) and somatic hypermutation (SHM) to generate antibody memory. Previously, heterogeneous nuclear ribonucleoprotein K (hnRNP K) was shown to be required for AID-dependent DNA breaks. Here, we defined the function of major RNA-binding motifs of hnRNP K, GXXGs and RGGs in the K-homology (KH) and the K-protein-interaction (KI) domains, respectively. Mutation of GXXG, RGG, or both impaired CSR, SHM, and cMyc/IgH translocation equally, showing that these motifs were necessary for AID-dependent DNA breaks. AID-hnRNP K interaction is dependent on RNA; hence, mutation of these RNA-binding motifs abolished the interaction with AID, as expected. Some of the polypyrimidine sequence-carrying prototypical hnRNP K-binding RNAs, which participate in DNA breaks or repair bound to hnRNP K in a GXXG and RGG motif-dependent manner. Mutation of the GXXG and RGG motifs decreased nuclear retention of hnRNP K. Together with the previous finding that nuclear localization of AID is necessary for its function, lower nuclear retention of these mutants may worsen their functional deficiency, which is also caused by their decreased RNA-binding capacity. In summary, hnRNP K contributed to AID-dependent DNA breaks with all of its major RNA-binding motifs.
Collapse
|
10
|
Islam H, Kobayashi M, Honjo T. Apurinic/apyrimidinic endonuclease 1 (APE1) is dispensable for activation-induced cytidine deaminase (AID)-dependent somatic hypermutation in the immunoglobulin gene. Int Immunol 2020; 31:543-554. [PMID: 30877298 DOI: 10.1093/intimm/dxz028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Accepted: 03/14/2019] [Indexed: 12/13/2022] Open
Abstract
Activation-induced cytidine deaminase (AID) initiates DNA breakage in the variable (V) and switch (S) regions of the immunoglobulin gene, which results in somatic hypermutation (SHM) and class switch recombination (CSR), respectively. Apurinic/apyrimidinic endonuclease 1 (APE1) has been shown to be important for CSR, and is supposed to cleave at abasic sites when AID-dependently deaminated cytidine is removed by uracil DNA glycosylase. However, APE1 is unexpectedly dispensable for SHM in the S region and translocation between immunoglobulin heavy chain (IgH) and c-myc genes in the mouse B lymphoma cell line, CH12F3-2A. This suggested that APE1 is not involved in AID-dependent DNA breakage, but rather, in DNA repair. In order to investigate detailed molecular mechanisms underlying APE1's involvement in CSR and SHM, we measured apurinic/apyrimidinic (AP) sites via aldehyde reactive probe labeling. Results indicated that the frequencies of AP sites in the S regions were not different between APE1-/-/-CH12F3-2A and wild-type CH12F3-2A cells. To carry out similar experiments in SHM of the V region, we generated an APE1 knockout (APE1-/-) human Burkitt's lymphoma cell line, and compared SHM between APE1-proficient and -deficient BL2 lymphoma cells. SHM frequencies in the V regions of APE1-/-BL2 and APE1-proficient cells were also similar. Taken together, we showed that AID does not induce AP sites in the S region of the IgH gene, and that APE1 is not necessary for SHM in the V and S regions; however, it is required for DNA repair following DNA breakage in CSR.
Collapse
Affiliation(s)
- Helena Islam
- Immunology and Genomic Medicine, Graduate School of Medicine, Kyoto University, Yoshida-Konoe cho, Sakyo-ku, Kyoto, Japan
| | - Maki Kobayashi
- Immunology and Genomic Medicine, Graduate School of Medicine, Kyoto University, Yoshida-Konoe cho, Sakyo-ku, Kyoto, Japan
| | - Tasuku Honjo
- Immunology and Genomic Medicine, Graduate School of Medicine, Kyoto University, Yoshida-Konoe cho, Sakyo-ku, Kyoto, Japan
| |
Collapse
|
11
|
Yu K, Lieber MR. Current insights into the mechanism of mammalian immunoglobulin class switch recombination. Crit Rev Biochem Mol Biol 2019; 54:333-351. [PMID: 31509023 PMCID: PMC6856442 DOI: 10.1080/10409238.2019.1659227] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 08/13/2019] [Accepted: 08/20/2019] [Indexed: 12/12/2022]
Abstract
Immunoglobulin (Ig) class switch recombination (CSR) is the gene rearrangement process by which B lymphocytes change the Ig heavy chain constant region to permit a switch of Ig isotype from IgM to IgG, IgA, or IgE. At the DNA level, CSR occurs via generation and joining of DNA double strand breaks (DSBs) at intronic switch regions located just upstream of each of the heavy chain constant regions. Activation-induced deaminase (AID), a B cell specific enzyme, catalyzes cytosine deaminations (converting cytosines to uracils) as the initial DNA lesions that eventually lead to DSBs and CSR. Progress on AID structure integrates very well with knowledge about Ig class switch region nucleic acid structures that are supported by functional studies. It is an ideal time to review what is known about the mechanism of Ig CSR and its relation to somatic hypermutation. There have been many comprehensive reviews on various aspects of the CSR reaction and regulation of AID expression and activity. This review is focused on the relation between AID and switch region nucleic acid structures, with a particular emphasis on R-loops.
Collapse
Affiliation(s)
- Kefei Yu
- Michigan State University, Department of Microbiology & Molecular Genetics, 5175 Biomedical Physical Sciences, East Lansing, MI 48824
| | - Michael R. Lieber
- USC Norris Comprehensive Cancer Ctr., Departments of Pathology, of Molecular Microbiology & Immunology, of Biochemistry & Molecular Biology, and of the Section of Molecular & Computational Biology within the Department of Biological Sciences, 1441 Eastlake Ave., NTT5428, Los Angeles, CA 90089-9176
| |
Collapse
|
12
|
Leeman-Neill RJ, Lim J, Basu U. The Common Key to Class-Switch Recombination and Somatic Hypermutation: Discovery of AID and Its Role in Antibody Gene Diversification. THE JOURNAL OF IMMUNOLOGY 2019; 201:2527-2529. [PMID: 30348657 DOI: 10.4049/jimmunol.1801246] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Rebecca J Leeman-Neill
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032; and.,Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032
| | - Junghyun Lim
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032; and
| | - Uttiya Basu
- Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032; and
| |
Collapse
|
13
|
Abstract
Class switch recombination (CSR) generates isotype-switched antibodies with distinct effector functions essential for mediating effective humoral immunity. CSR is catalyzed by activation-induced deaminase (AID) that initiates DNA lesions in the evolutionarily conserved switch (S) regions at the immunoglobulin heavy chain (Igh) locus. AID-initiated DNA lesions are subsequently converted into DNA double stranded breaks (DSBs) in the S regions of Igh locus, repaired by non-homologous end-joining to effect CSR in mammalian B lymphocytes. While molecular mechanisms of CSR are well characterized, it remains less well understood how upstream signaling pathways regulate AID expression and CSR. B lymphocytes express multiple receptors including the B cell antigen receptor (BCR) and co-receptors (e.g., CD40). These receptors may share common signaling pathways or may use distinct signaling elements to regulate CSR. Here, we discuss how signals emanating from different receptors positively or negatively regulate AID expression and CSR.
Collapse
Affiliation(s)
- Zhangguo Chen
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States.
| | - Jing H Wang
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States.
| |
Collapse
|
14
|
Al Ismail A, Husain A, Kobayashi M, Honjo T, Begum NA. Depletion of recombination-specific cofactors by the C-terminal mutant of the activation-induced cytidine deaminase causes the dominant negative effect on class switch recombination. Int Immunol 2019; 29:525-537. [PMID: 29136157 DOI: 10.1093/intimm/dxx061] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 11/08/2017] [Indexed: 12/11/2022] Open
Abstract
Activation-induced cytidine deaminase (AID) is essential for class-switch recombination (CSR) and somatic hypermutation (SHM) of immunoglobulin genes. Studies on in vitro mutagenized AID as well as its mutations in human patients with hyper-IgM (HIGM)-syndrome type II revealed that C-terminal AID mutations were defective in CSR whereas their DNA cleavage and SHM activities remained intact. The C-terminal mutants of AID were speculated to exert the dominant negative effect on wild-type (WT) AID whereas its mechanism remains unknown. We generated the JP41 (R190X) mutation in one allele and a null mutation on the other allele in a mouse B cell line (CH12F3-2A) using CRISPR/Cas9 genome-editing tools and studied the effect of JP41 expression on the function of exogenously introduced WT AID fused with estrogen receptor (AIDER) in AIDJP41/∆/AIDER CH12F3-2A cells. We found that JP41 expression strongly suppressed not only CSR but also Igh/c-Myc chromosomal translocations by AIDER. We showed that the dominant negative effect is not evident at the DNA cleavage step but obvious at both deletional and inversional recombination steps. We also confirmed the dominant negative effect of other C-terminal mutants, JP8Bdel (R183X) and P20 (34-aa insertion at residue 182) in AID-deficient spleen B cells. Finally, we showed that the expression of JP41 reduced the binding of AIDER with its cofactors (hnRNP L, SERBP1 and hnRNP U). Together, these data indicate that dominant negative effect of JP41 on CSR is likely due to the depletion of the CSR-specific RNA-binding proteins from WT AID.
Collapse
Affiliation(s)
- Azza Al Ismail
- Department of Immunology and Genomic Medicine, Graduate School of Medicine, Kyoto University, Yoshida-Konoe cho, Sakyo-ku, Kyoto, Japan
| | - Afzal Husain
- Department of Immunology and Genomic Medicine, Graduate School of Medicine, Kyoto University, Yoshida-Konoe cho, Sakyo-ku, Kyoto, Japan
| | - Maki Kobayashi
- Department of Immunology and Genomic Medicine, Graduate School of Medicine, Kyoto University, Yoshida-Konoe cho, Sakyo-ku, Kyoto, Japan
| | - Tasuku Honjo
- Department of Immunology and Genomic Medicine, Graduate School of Medicine, Kyoto University, Yoshida-Konoe cho, Sakyo-ku, Kyoto, Japan
| | - Nasim A Begum
- Department of Immunology and Genomic Medicine, Graduate School of Medicine, Kyoto University, Yoshida-Konoe cho, Sakyo-ku, Kyoto, Japan
| |
Collapse
|
15
|
Zaprazna K, Reblova K, Svobodova V, Radova L, Bystry V, Baloun J, Durechova K, Tom N, Loja T, Buresova M, Stranska K, Oltova A, Doubek M, Atchison ML, Trbusek M, Malcikova J, Pospisilova S. Activation-induced deaminase and its splice variants associate with trisomy 12 in chronic lymphocytic leukemia. Ann Hematol 2018; 98:423-435. [PMID: 30368590 DOI: 10.1007/s00277-018-3520-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2018] [Accepted: 10/09/2018] [Indexed: 11/26/2022]
Abstract
Activation-induced cytidine deaminase (AID) is a mutator enzyme essential for somatic hypermutation (SHM) and class switch recombination (CSR) during effective adaptive immune responses. Its aberrant expression and activity have been detected in lymphomas, leukemias, and solid tumors. In chronic lymphocytic leukemia (CLL) increased expression of alternatively spliced AID variants has been documented. We used real-time RT-PCR to quantify the expression of AID and its alternatively spliced transcripts (AIDΔE4a, AIDΔE4, AIDivs3, and AIDΔE3E4) in 149 CLL patients and correlated this expression to prognostic markers including recurrent chromosomal aberrations, the presence of complex karyotype, mutation status of the immunoglobulin heavy chain variable gene, and recurrent mutations. We report a previously unappreciated association between higher AID transcript levels and trisomy of chromosome 12. Functional analysis of AID splice variants revealed loss of their activity with respect to SHM, CSR, and induction of double-strand DNA breaks. In silico modeling provided insight into the molecular interactions and structural dynamics of wild-type AID and a shortened AID variant closely resembling AIDΔE4, confirming its loss-of-function phenotype.
Collapse
MESH Headings
- Aged
- Alternative Splicing
- Animals
- Chromosomes, Human, Pair 12/enzymology
- Chromosomes, Human, Pair 12/genetics
- Computer Simulation
- Cytidine Deaminase/biosynthesis
- Cytidine Deaminase/chemistry
- Cytidine Deaminase/genetics
- Female
- Gene Expression Regulation, Enzymologic
- Gene Expression Regulation, Neoplastic
- Humans
- Leukemia, Lymphocytic, Chronic, B-Cell/enzymology
- Leukemia, Lymphocytic, Chronic, B-Cell/genetics
- Leukemia, Lymphocytic, Chronic, B-Cell/pathology
- Male
- Mice
- Mice, Knockout
- Middle Aged
- Models, Biological
- Molecular Dynamics Simulation
- Neoplasm Proteins/biosynthesis
- Neoplasm Proteins/chemistry
- Neoplasm Proteins/genetics
- Trisomy/genetics
- Trisomy/pathology
Collapse
Affiliation(s)
- Kristina Zaprazna
- Central European Institute of Technology, Center of Molecular Medicine, Masaryk University, Kamenice 5/A35, 625 00, Brno, Czech Republic.
| | - Kamila Reblova
- Central European Institute of Technology, Center of Molecular Medicine, Masaryk University, Kamenice 5/A35, 625 00, Brno, Czech Republic
| | - Veronika Svobodova
- Central European Institute of Technology, Center of Molecular Medicine, Masaryk University, Kamenice 5/A35, 625 00, Brno, Czech Republic
| | - Lenka Radova
- Central European Institute of Technology, Center of Molecular Medicine, Masaryk University, Kamenice 5/A35, 625 00, Brno, Czech Republic
| | - Vojtech Bystry
- Central European Institute of Technology, Center of Molecular Medicine, Masaryk University, Kamenice 5/A35, 625 00, Brno, Czech Republic
| | - Jiri Baloun
- Central European Institute of Technology, Center of Molecular Medicine, Masaryk University, Kamenice 5/A35, 625 00, Brno, Czech Republic
| | - Kristina Durechova
- Department of Internal Medicine - Hematology and Oncology, Faculty of Medicine, Masaryk University and University Hospital Brno, Brno, Czech Republic
| | - Nikola Tom
- Central European Institute of Technology, Center of Molecular Medicine, Masaryk University, Kamenice 5/A35, 625 00, Brno, Czech Republic
| | - Tomas Loja
- Central European Institute of Technology, Center of Molecular Medicine, Masaryk University, Kamenice 5/A35, 625 00, Brno, Czech Republic
| | - Martina Buresova
- Central European Institute of Technology, Center of Molecular Medicine, Masaryk University, Kamenice 5/A35, 625 00, Brno, Czech Republic
- Department of Internal Medicine - Hematology and Oncology, Faculty of Medicine, Masaryk University and University Hospital Brno, Brno, Czech Republic
| | - Kamila Stranska
- Central European Institute of Technology, Center of Molecular Medicine, Masaryk University, Kamenice 5/A35, 625 00, Brno, Czech Republic
- Department of Internal Medicine - Hematology and Oncology, Faculty of Medicine, Masaryk University and University Hospital Brno, Brno, Czech Republic
| | - Alexandra Oltova
- Department of Internal Medicine - Hematology and Oncology, Faculty of Medicine, Masaryk University and University Hospital Brno, Brno, Czech Republic
| | - Michael Doubek
- Central European Institute of Technology, Center of Molecular Medicine, Masaryk University, Kamenice 5/A35, 625 00, Brno, Czech Republic
- Department of Internal Medicine - Hematology and Oncology, Faculty of Medicine, Masaryk University and University Hospital Brno, Brno, Czech Republic
| | - Michael L Atchison
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Martin Trbusek
- Department of Internal Medicine - Hematology and Oncology, Faculty of Medicine, Masaryk University and University Hospital Brno, Brno, Czech Republic
| | - Jitka Malcikova
- Central European Institute of Technology, Center of Molecular Medicine, Masaryk University, Kamenice 5/A35, 625 00, Brno, Czech Republic
- Department of Internal Medicine - Hematology and Oncology, Faculty of Medicine, Masaryk University and University Hospital Brno, Brno, Czech Republic
| | - Sarka Pospisilova
- Central European Institute of Technology, Center of Molecular Medicine, Masaryk University, Kamenice 5/A35, 625 00, Brno, Czech Republic.
- Department of Internal Medicine - Hematology and Oncology, Faculty of Medicine, Masaryk University and University Hospital Brno, Brno, Czech Republic.
| |
Collapse
|
16
|
Patel B, Banerjee R, Samanta M, Das S. Diversity of Immunoglobulin (Ig) Isotypes and the Role of Activation-Induced Cytidine Deaminase (AID) in Fish. Mol Biotechnol 2018; 60:435-453. [PMID: 29704159 DOI: 10.1007/s12033-018-0081-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The disparate diversity in immunoglobulin (Ig) repertoire has been a subject of fascination since the emergence of prototypic adaptive immune system in vertebrates. The carboxy terminus region of activation-induced cytidine deaminase (AID) has been well established in tetrapod lineage and is crucial for its function in class switch recombination (CSR) event of Ig diversification. The absence of CSR in the paraphyletic group of fish is probably due to changes in catalytic domain of AID and lack of cis-elements in IgH locus. Therefore, understanding the arrangement of Ig genes in IgH locus and functional facets of fish AID opens up new realms of unravelling the alternative mechanisms of isotype switching and antibody diversity. Further, the teleost AID has been recently reported to have potential of catalyzing CSR in mammalian B cells by complementing AID deficiency in them. In that context, the present review focuses on the recent advances regarding the generation of diversity in Ig repertoire in the absence of AID-regulated class switching in teleosts and the possible role of T cell-independent pathway involving B cell activating factor and a proliferation-inducing ligand in activation of CSR machinery.
Collapse
Affiliation(s)
- Bhakti Patel
- Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology, Rourkela, Odisha, 769 008, India
| | - Rajanya Banerjee
- Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology, Rourkela, Odisha, 769 008, India
| | - Mrinal Samanta
- Immunology Laboratory, Fish Health Management Division, ICAR-Central Institute of Freshwater Aquaculture, Kausalyaganga, Bhubaneswar, Odisha, 751 002, India
| | - Surajit Das
- Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology, Rourkela, Odisha, 769 008, India.
| |
Collapse
|
17
|
Song S, Matthias PD. The Transcriptional Regulation of Germinal Center Formation. Front Immunol 2018; 9:2026. [PMID: 30233601 PMCID: PMC6134015 DOI: 10.3389/fimmu.2018.02026] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Accepted: 08/16/2018] [Indexed: 12/19/2022] Open
Abstract
Germinal centers (GCs) are essential structures of the humoral immune response, which form in the periphery in response to T cell dependent antigens. During the GC reaction, B cells undergo critical differentiation steps, which ultimately lead to the generation of antibodies with altered effector function and higher affinity for the selected antigen. Remarkably, many of the B cell tumors have their origin in the GCs; thus, understanding how the formation of these structures is regulated or deregulated is of high medical importance. This review gives an overview of the transcription factors that have been linked to the generation of GCs, and of their roles in the process.
Collapse
Affiliation(s)
- Shuang Song
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.,Faculty of Sciences, University of Basel, Basel, Switzerland
| | - Patrick D Matthias
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.,Faculty of Sciences, University of Basel, Basel, Switzerland
| |
Collapse
|
18
|
Wang R, Zhang X, Ding H, Qiao Y, Han X, Geng W, Guan G, Cui H, Zhao B, Wu Y, Liang G, Shang H. AID recruits the RNA exosome to degrade HIV-1 nascent transcripts through interaction with the Tat-P-TEFb-TAR RNP complex. FEBS Lett 2018; 592:284-294. [PMID: 29266200 DOI: 10.1002/1873-3468.12954] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 10/31/2017] [Accepted: 11/17/2017] [Indexed: 01/11/2023]
Abstract
Activation-induced cytidine deaminase (AID), a member of the APOBEC family that induces antibody diversification, has been shown to inhibit the replication of hepatitis B virus, Kaposi's sarcoma-associated herpesvirus, and retro-transposons. However, whether AID can inhibit human immunodeficiency virus 1 (HIV-1) replication remains unclear. Here, we report that AID impairs the synthesis of HIV-1 components by interacting with the complex of Tat. This interaction recruits the RNA exosome to degrade the nascent HIV-1 transcript. AID also targets the HIV-1-integrated genome via the Tat-P-TEFb-TAR complex. Thus, we propose a novel function for AID as an adaptor protein that represses viral transcription. Our findings provide insights into developing anti-HIV therapeutics and understanding how host cells restrict integrated virus replication.
Collapse
Affiliation(s)
- Ruixuan Wang
- Key Laboratory of AIDS Immunology of the National Health and Family Planning Commission, Department of Laboratory Medicine, China Medical University, Shenyang, China
| | - Xiaowei Zhang
- The Core Laboratory for Public Health Science and Practice, China Medical University, Shenyang, China
| | - Haibo Ding
- Key Laboratory of AIDS Immunology of the National Health and Family Planning Commission, Department of Laboratory Medicine, China Medical University, Shenyang, China
| | - Ying Qiao
- The Core Laboratory for Public Health Science and Practice, China Medical University, Shenyang, China
| | - Xiaoxu Han
- Key Laboratory of AIDS Immunology of the National Health and Family Planning Commission, Department of Laboratory Medicine, China Medical University, Shenyang, China
| | - Wenqing Geng
- Key Laboratory of AIDS Immunology of the National Health and Family Planning Commission, Department of Laboratory Medicine, China Medical University, Shenyang, China
| | - Gefei Guan
- Department of Neurosurgery, The First Affiliated Hospital, China Medical University, Shenyang, China
| | - Hualu Cui
- Key Laboratory of AIDS Immunology of the National Health and Family Planning Commission, Department of Laboratory Medicine, China Medical University, Shenyang, China
| | - Bin Zhao
- Key Laboratory of AIDS Immunology of the National Health and Family Planning Commission, Department of Laboratory Medicine, China Medical University, Shenyang, China
| | - Yuntao Wu
- National Center for Biodefense and Infectious Diseases, Department of Molecular and Microbiology, George Mason University, Manassas, VA, USA
| | - Guoxin Liang
- Key Laboratory of AIDS Immunology of the National Health and Family Planning Commission, Department of Laboratory Medicine, China Medical University, Shenyang, China
| | - Hong Shang
- Key Laboratory of AIDS Immunology of the National Health and Family Planning Commission, Department of Laboratory Medicine, China Medical University, Shenyang, China
| |
Collapse
|
19
|
Liu X, Meng FL. Generation of Genomic Alteration from Cytidine Deamination. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1044:49-64. [DOI: 10.1007/978-981-13-0593-1_5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
|
20
|
|
21
|
Meng X, Yang B, Suen WC. Prospects for modulating the CD40/CD40L pathway in the therapy of the hyper-IgM syndrome. Innate Immun 2017; 24:4-10. [PMID: 29132233 DOI: 10.1177/1753425917739681] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The critical role of the CD40/CD40L pathway in B-cell proliferation, immunoglobulin (Ig) isotype switching and germinal center formation has been studied and described extensively in previous literature. Interruption of the CD40/CD40L signal causes hyper-IgM (HIGM) syndrome, which has been classified and recognized as a group of rare inherited immune deficiency disorders. Defects in CD40 and CD40L interactions or in downstream signaling molecules, including activation-induced cytidine deaminase, uracyl-DNA-glycosylase, NF-κB and DNA repair enzymes, result in an increased level of serum IgM and a significantly decreased or absent level of IgA, IgG and IgE that is accompanied by severe recurrent infections and autoimmune diseases. Many genetic defects in HIGM have been identified and, as a result, it is possible for patients to be definitively diagnosed by gene sequencing and to delineate the immunological features of the patients. Modifying the CD40/CD40L signaling pathway may offer the possibility of restoring the normal serum Ab production and curing the immunodeficiency. Hematopoietic stem cell transplantation has achieved a high rate of success using a sibling donor. In addition, successful examples of treating other immunodeficiencies using gene therapy indicated that there was a possibility of eradicating HIGM with this approach. In this review, we summarize the current drugs and a variety of therapeutic approaches for the treatment of the HIGM syndrome by interfering with the defective CD40/CD40L pathway.
Collapse
Affiliation(s)
- Xiangxue Meng
- 1 Sunshine Lake Pharma Co., Ltd, Dongguan 523867, PR China
| | - Bin Yang
- 2 Institute of Biomedicine & National Engineering Research Center of Genetic Medicine, College of Life Science and Technology, Jinan University, PR China
| | - Wen-Chen Suen
- 1 Sunshine Lake Pharma Co., Ltd, Dongguan 523867, PR China
| |
Collapse
|
22
|
de la Morena MT. Clinical Phenotypes of Hyper-IgM Syndromes. THE JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY-IN PRACTICE 2017; 4:1023-1036. [PMID: 27836054 DOI: 10.1016/j.jaip.2016.09.013] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 09/21/2016] [Accepted: 09/23/2016] [Indexed: 02/05/2023]
Abstract
The primary immunodeficiency (PID) diseases comprise a heterogeneous group of inherited disorders of immune function. Technical advancements in whole-genome, whole-exome, and RNA-sequencing have seen the explosion of genetic discoveries in the field of PIDs. The present review aims to focus on a group of immunodeficiency disorders associated with elevated levels of IgM (hyper IgM; HIGM) and provides a clinical differential diagnosis. Most patients present for evaluation of immunodeficiency due to recurrent infections, and laboratory studies show either a clear isolated elevation of serum immunoglobulin M (IgM) with low or absent IgG, IgA, and IgE. Alternatively, IgM levels may be normal or moderately elevated while other serum immunoglobulins are reported below the norms for age but not absent. Mechanistically, these disorders are recognized as defects in immunoglobulin (Ig) class switch recombination (CSR). Importantly, to safeguard genetic stability, CSR utilizes elements of the DNA repair machinery including multi-protein complexes involved in mismatch repair (MMR). Therefore, it is not uncommon for defects in the DNA repair machinery, to present with laboratory findings of HIGM. This review will discuss clinical phenotypes associated with congenital defects associated with HIGM. Clinical manifestations, relevant immunologic testing, inheritance pattern, molecular diagnosis, presumed pathogenesis, and OMIM number, when annotated are compiled. Accepted therapeutic options, when available, are reviewed for each condition discussed.
Collapse
Affiliation(s)
- M Teresa de la Morena
- Division of Allergy and Immunology, Department of Pediatrics and Internal Medicine, University of Texas, Southwestern Medical Center, Dallas, Texas.
| |
Collapse
|
23
|
Choudhary M, Tamrakar A, Singh AK, Jain M, Jaiswal A, Kodgire P. AID Biology: A pathological and clinical perspective. Int Rev Immunol 2017; 37:37-56. [PMID: 28933967 DOI: 10.1080/08830185.2017.1369980] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Activation-induced cytidine deaminase (AID), primarily expressed in activated mature B lymphocytes in germinal centers, is the key factor in adaptive immune response against foreign antigens. AID is responsible for producing high-affinity and high-specificity antibodies against an infectious agent, through the physiological DNA alteration processes of antibody genes by somatic hypermutation (SHM) and class-switch recombination (CSR) and functions by deaminating deoxycytidines (dC) to deoxyuridines (dU), thereby introducing point mutations and double-stranded chromosomal breaks (DSBs). The beneficial physiological role of AID in antibody diversification is outweighed by its detrimental role in the genesis of several chronic immune diseases, under non-physiological conditions. This review offers a comprehensive and better understanding of AID biology and its pathological aspects, as well as addresses the challenges involved in AID-related cancer therapeutics, based on various recent advances and evidence available in the literature till date. In this article, we discuss ways through which our interpretation of AID biology may reflect upon novel clinical insights, which could be successfully translated into designing clinical trials and improving patient prognosis and disease management.
Collapse
Affiliation(s)
- Meenal Choudhary
- a Centre for Biosciences and Biomedical Engineering , Indian Institute of Technology Indore , Simrol , Indore , Madhya Pradesh , India
| | - Anubhav Tamrakar
- a Centre for Biosciences and Biomedical Engineering , Indian Institute of Technology Indore , Simrol , Indore , Madhya Pradesh , India
| | - Amit Kumar Singh
- a Centre for Biosciences and Biomedical Engineering , Indian Institute of Technology Indore , Simrol , Indore , Madhya Pradesh , India
| | - Monika Jain
- a Centre for Biosciences and Biomedical Engineering , Indian Institute of Technology Indore , Simrol , Indore , Madhya Pradesh , India
| | - Ankit Jaiswal
- a Centre for Biosciences and Biomedical Engineering , Indian Institute of Technology Indore , Simrol , Indore , Madhya Pradesh , India
| | - Prashant Kodgire
- a Centre for Biosciences and Biomedical Engineering , Indian Institute of Technology Indore , Simrol , Indore , Madhya Pradesh , India
| |
Collapse
|
24
|
Activation-induced cytidine deaminase targets SUV4-20-mediated histone H4K20 trimethylation to class-switch recombination sites. Sci Rep 2017; 7:7594. [PMID: 28790320 PMCID: PMC5548798 DOI: 10.1038/s41598-017-07380-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 06/28/2017] [Indexed: 11/22/2022] Open
Abstract
Activation-induced cytidine deaminase (AID) triggers antibody diversification in B cells by catalysing deamination and subsequently mutating immunoglobulin (Ig) genes. Association of AID with RNA Pol II and occurrence of epigenetic changes during Ig gene diversification suggest participation of AID in epigenetic regulation. AID is mutated in hyper-IgM type 2 (HIGM2) syndrome. Here, we investigated the potential role of AID in the acquisition of epigenetic changes. We discovered that AID binding to the IgH locus promotes an increase in H4K20me3. In 293F cells, we demonstrate interaction between co-transfected AID and the three SUV4-20 histone H4K20 methyltransferases, and that SUV4-20H1.2, bound to the IgH switch (S) mu site, is replaced by SUV4-20H2 upon AID binding. Analysis of HIGM2 mutants shows that the AID truncated form W68X is impaired to interact with SUV4-20H1.2 and SUV4-20H2 and is unable to bind and target H4K20me3 to the Smu site. We finally show in mouse primary B cells undergoing class-switch recombination (CSR) that AID deficiency associates with decreased H4K20me3 levels at the Smu site. Our results provide a novel link between SUV4-20 enzymes and CSR and offer a new aspect of the interplay between AID and histone modifications in setting the epigenetic status of CSR sites.
Collapse
|
25
|
Molecular characterization of AID-mediated reduction of hepatitis B virus transcripts. Virology 2017; 510:281-288. [PMID: 28779685 DOI: 10.1016/j.virol.2017.07.035] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 06/30/2017] [Accepted: 07/28/2017] [Indexed: 12/21/2022]
Abstract
Hepatitis B virus (HBV) is the major cause of liver cirrhosis and hepatocellular carcinoma. After entering a hepatocyte, HBV forms a nuclear viral episome and produces pregenomic (pg) RNA with a stem-loop structure called an epsilon, which acts to signal encapsidation. We previously demonstrated that TGF-β upregulates activation-induced cytidine deaminase (AID) expression in hepatocytes, which in turn downregulates HBV transcripts by recruiting the RNA exosome complex. The molecular mechanism underlying AID-mediated HBV RNA reduction remains largely unclear. Here we used a pgRNA reporter system having a reporter gene within pgRNA to identify sis- and trans-acting elements in AID-mediated HBV RNA reduction. We found that the epsilon RNA and C-terminus of AID are required for AID-mediated HBV RNA reduction. Importantly, this reduction was reproduced in a hydrodynamic HBV transfection mouse model. The molecular mechanism of AID-mediated HBV RNA reduction is discussed.
Collapse
|
26
|
Ito F, Fu Y, Kao SCA, Yang H, Chen XS. Family-Wide Comparative Analysis of Cytidine and Methylcytidine Deamination by Eleven Human APOBEC Proteins. J Mol Biol 2017; 429:1787-1799. [PMID: 28479091 DOI: 10.1016/j.jmb.2017.04.021] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Revised: 04/28/2017] [Accepted: 04/29/2017] [Indexed: 01/17/2023]
Abstract
Apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like (APOBEC) proteins are a family of cytidine deaminases involved in various important biological processes such as antibody diversification/maturation, restriction of viral infection, and generation of somatic mutations. Catalytically active APOBEC proteins execute their biological functions mostly through deaminating cytosine (C) to uracil on single-stranded DNA/RNA. Activation-induced cytidine deaminase, one of the APOBEC members, was reported to deaminate methylated cytosine (mC) on DNA, and this mC deamination was proposed to be involved in the demethylation of mC for epigenetic regulation. The mC deamination activity is later demonstrated for APOBEC3A (A3A) and more recently for APOBEC3B and APOBEC3H (A3H). Despite extensive studies on APOBEC proteins, questions regarding whether the rest of APOBEC members have any mC deaminase activity and what are the relative deaminase activities for each APOBEC member remain unclear. Here, we performed a family-wide analysis of deaminase activities on C and mC by using purified recombinant proteins for 11 known human APOBEC proteins under similar conditions. Our comprehensive analyses revealed that each APOBEC has unique deaminase activity and selectivity for mC. A3A and A3H showed distinctively high deaminase activities on C and mC with relatively high selectivity for mC, whereas six other APOBEC members showed relatively low deaminase activity and selectivity for mC. Our mutational analysis showed that loop-1 of A3A is responsible for its high deaminase activity and selectivity for mC. These findings extend our understanding of APOBEC family proteins that have important roles in diverse biological functions and in genetic mutations.
Collapse
Affiliation(s)
- Fumiaki Ito
- Molecular and Computational Biology Program, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Yang Fu
- Molecular and Computational Biology Program, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Shen-Chi A Kao
- Molecular and Computational Biology Program, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Hanjing Yang
- Molecular and Computational Biology Program, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Xiaojiang S Chen
- Molecular and Computational Biology Program, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA; Department of Chemistry, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA 90089, USA; Center of Excellence in NanoBiophysics, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA 90089, USA.
| |
Collapse
|
27
|
Pham P, Afif SA, Shimoda M, Maeda K, Sakaguchi N, Pedersen LC, Goodman MF. Activation-induced deoxycytidine deaminase: Structural basis for favoring WRC hot motif specificities unique among APOBEC family members. DNA Repair (Amst) 2017; 54:8-12. [PMID: 28388461 DOI: 10.1016/j.dnarep.2017.03.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 03/26/2017] [Indexed: 12/12/2022]
Affiliation(s)
- Phuong Pham
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, United States
| | - Samir A Afif
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, United States
| | - Mayuko Shimoda
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan; Laboratory of Host Defence, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita 565-0871, Japan; World Premier International Research Center Initiative, Immunology Frontier Research Center, Osaka University, 3-1 Yamada-oka, Suita 565-0871, Japan
| | - Kazuhiko Maeda
- Laboratory of Host Defence, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita 565-0871, Japan; World Premier International Research Center Initiative, Immunology Frontier Research Center, Osaka University, 3-1 Yamada-oka, Suita 565-0871, Japan
| | - Nobuo Sakaguchi
- World Premier International Research Center Initiative, Immunology Frontier Research Center, Osaka University, 3-1 Yamada-oka, Suita 565-0871, Japan; Tokyo Metropolitan Institute of Medical Science, 2-1-6, Kamikitazawa, Setagaya-ku, Tokyo, 156-8506, Japan
| | - Lars C Pedersen
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institute of Health, Research Triangle Park, NC 27709, United States
| | - Myron F Goodman
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, United States; Department of Chemistry, University of Southern California, Los Angeles, CA 90089, United States.
| |
Collapse
|
28
|
Kobayashi M, Takemoto M, Honjo T. The novel activation-induced deoxycytidine deaminase (AID) mutants, AIDv and AIDvΔ15 are defective in SHM and CSR. DNA Repair (Amst) 2017; 53:1-3. [PMID: 28292632 DOI: 10.1016/j.dnarep.2017.02.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 02/28/2017] [Indexed: 11/28/2022]
Affiliation(s)
- Maki Kobayashi
- Department of Immunology and Genomic Medicine, Graduate School of Medicine, Kyoto University, Japan
| | - Misao Takemoto
- Department of Immunology and Genomic Medicine, Graduate School of Medicine, Kyoto University, Japan
| | - Tasuku Honjo
- Department of Immunology and Genomic Medicine, Graduate School of Medicine, Kyoto University, Japan.
| |
Collapse
|
29
|
Fazel A, Kashef S, Aleyasin S, Harsini S, Karamizadeh Z, Zoghi S, Flores SK, Boztug K, Rezaei N. Novel AICDA mutation in a case of autosomal recessive hyper-IgM syndrome, growth hormone deficiency and autoimmunity. Allergol Immunopathol (Madr) 2017; 45:82-86. [PMID: 27789066 DOI: 10.1016/j.aller.2016.08.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 07/13/2016] [Accepted: 08/01/2016] [Indexed: 01/02/2023]
Abstract
BACKGROUND The Hyper-immunoglobulin M syndromes (HIGM) are a heterogeneous group of genetic disorders, which have been rarely reported to be associated with growth hormone deficiency (GHD). METHODS AND RESULTS A nine-year-old girl with recurrent urinary tract infections, diarrhoea, sinopulmonary infections, and failure to thrive since the age of six months had normal CD3+, CD4+, CD8+T lymphocytes, and CD19+B lymphocytes and natural killer (NK) cells, but extremely elevated IgM and significantly decreased IgG and IgA. In view of the patient's short stature, growth hormone evaluation was carried out and growth hormone deficiency established. The patient underwent Ig replacement therapy and received growth hormone therapy in addition to antibiotics and responded well. Furthermore, the patient developed benign cervical lymphadenopathy, as well as elevated erythrocyte sedimentation rate, positive autoantibodies to SSA-Ro, and severely dry eyes, which partially responded to both the punctate occlusion and systemic corticosteroids, at the age of seven years. Sequencing analysis of the exons from activation-induced cytidine deaminase (AICDA) gene revealed that the patient was homozygous for a single T to C transversion at position 455 in exon 4, which replaces a Valine with an Alanine. CONCLUSIONS To our knowledge, this is a new AICDA mutation, which has not been reported previously in HIGM. The mutation analysis could improve diagnosis of HIGM patients and also elaborating on the spectrum of AICDA mutations.
Collapse
Affiliation(s)
- A Fazel
- Allergy Research Center, Division of Pediatric Immunology and Allergy, Shiraz University of Medical Sciences, Shiraz, Iran
| | - S Kashef
- Allergy Research Center, Division of Pediatric Immunology and Allergy, Shiraz University of Medical Sciences, Shiraz, Iran.
| | - S Aleyasin
- Allergy Research Center, Division of Pediatric Immunology and Allergy, Shiraz University of Medical Sciences, Shiraz, Iran
| | - S Harsini
- Research Center for Immunodeficiencies, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran; Network of Immunity in Infection, Malignancy and Autoimmunity (NIIMA), Universal Scientific Education and Research Network (USERN), Tehran, Iran
| | - Z Karamizadeh
- Division of Pediatric Endocrinology, Shiraz University of Medical Sciences, Shiraz, Iran
| | - S Zoghi
- Network of Immunity in Infection, Malignancy and Autoimmunity (NIIMA), Universal Scientific Education and Research Network (USERN), Tehran, Iran; Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - S K Flores
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - K Boztug
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria; Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria
| | - N Rezaei
- Research Center for Immunodeficiencies, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran; Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; Primary Immunodeficiency Diseases Network (PIDNet), Universal Scientific Education and Research Network (USERN), Sheffield, UK.
| |
Collapse
|
30
|
Methot S, Di Noia J. Molecular Mechanisms of Somatic Hypermutation and Class Switch Recombination. Adv Immunol 2017; 133:37-87. [DOI: 10.1016/bs.ai.2016.11.002] [Citation(s) in RCA: 165] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
|
31
|
Abstract
Apolipoprotein B mRNA Editing Catalytic Polypeptide-like 1 or APOBEC1 was discovered in 1993 as the zinc-dependent cytidine deaminase responsible for the production of an in frame stop codon in apoB mRNA through modification of cytidine at nucleotide position 6666 to uridine. At the time of this discovery there was much speculation concerning the mechanism of base modification RNA editing which has been rekindled by the discovery of multiple C to U RNA editing events in the 3′ UTRs of mRNAs and the finding that other members of the APOBEC family while able to bind RNA, have the biological function of being DNA mutating enzymes. Current research is addressing the mechanism for these nucleotide modification events that appear not to adhere to the mooring sequence-dependent model for APOBEC1 involving the assembly of a multi protein containing editosome. This review will summarize our current understanding of the structure and function of APOBEC proteins and examine how RNA binding to them may be a regulatory mechanism.
Collapse
Affiliation(s)
- Harold C Smith
- a University of Rochester, School of Medicine and Dentistry , Department of Biochemistry and Biophysics , Rochester , NY , USA
| |
Collapse
|
32
|
Activation induced cytidine deaminase mutant (AID-His130Pro) from Hyper IgM 2 patient retained mutagenic activity on SHM artificial substrate. Mol Immunol 2016; 79:77-82. [PMID: 27716525 DOI: 10.1016/j.molimm.2016.09.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 09/27/2016] [Accepted: 09/29/2016] [Indexed: 01/01/2023]
Abstract
Activation induced cytidine deaminase (AID) is an essential enzyme for class switch recombination (CSR) and somatic hypermutation (SHM) during secondary immune response. Mutations in the AICDA gene are responsible for Hyper IgM 2 syndrome where both CSR and SHM or only CSR are affected. Indeed, triggering either of the two mechanisms requires the DNA deamination activity of AID. Besides, different domains of AID may be differentially involved in CSR and SHM through their interaction with specific cofactors. Herein, we studied the AID-induced SHM activity of the AID-His130Pro mutant identified in a patient with Hyper IgM 2 syndrome. AID mutagenic activity was monitored by the reversion of nonsense mutations of the EGFP gene assessed by flow cytometry. We found that the His130Pro mutation, which affects CSR, preserves AID mutagenic activity. Indeed, the His130 residue is located in a putative specific CSR region in the APOBEC-like domain, known to involve CSR specific cofactors that probably play a major role in AID physiological activities.
Collapse
|
33
|
Bastianello G, Arakawa H. A double-strand break can trigger immunoglobulin gene conversion. Nucleic Acids Res 2016; 45:231-243. [PMID: 27701075 PMCID: PMC5224512 DOI: 10.1093/nar/gkw887] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2016] [Revised: 09/22/2016] [Accepted: 09/26/2016] [Indexed: 12/23/2022] Open
Abstract
All three B cell-specific activities of the immunoglobulin (Ig) gene re-modeling system—gene conversion, somatic hypermutation and class switch recombination—require activation-induced deaminase (AID). AID-induced DNA lesions must be further processed and dissected into different DNA recombination pathways. In order to characterize potential intermediates for Ig gene conversion, we inserted an I-SceI recognition site into the complementarity determining region 1 (CDR1) of the Ig light chain locus of the AID knockout DT40 cell line, and conditionally expressed I-SceI endonuclease. Here, we show that a double-strand break (DSB) in CDR1 is sufficient to trigger Ig gene conversion in the absence of AID. The pattern and pseudogene usage of DSB-induced gene conversion were comparable to those of AID-induced gene conversion; surprisingly, sometimes a single DSB induced multiple gene conversion events. These constitute direct evidence that a DSB in the V region can be an intermediate for gene conversion. The fate of the DNA lesion downstream of a DSB had more flexibility than that of AID, suggesting two alternative models: (i) DSBs during the physiological gene conversion are in the minority compared to single-strand breaks (SSBs), which are frequently generated following DNA deamination, or (ii) the physiological gene conversion is mediated by a tightly regulated DSB that is locally protected from non-homologous end joining (NHEJ) or other non-homologous DNA recombination machineries.
Collapse
Affiliation(s)
- Giulia Bastianello
- IFOM - FIRC Institute of Molecular Oncology Foundation, Via Adamello 16, 20139 Milan, Italy.,Università degli Studi di Milano, Dipartimento di Bioscienze, Via Celoria 26, 20133 Milan, Italy
| | - Hiroshi Arakawa
- IFOM - FIRC Institute of Molecular Oncology Foundation, Via Adamello 16, 20139 Milan, Italy
| |
Collapse
|
34
|
Almejún MB, Campos BC, Patiño V, Galicchio M, Zelazko M, Oleastro M, Oppezzo P, Danielian S. Noninfectious complications in patients with pediatric-onset common variable immunodeficiency correlated with defects in somatic hypermutation but not in class-switch recombination. J Allergy Clin Immunol 2016; 139:913-922. [PMID: 27713077 DOI: 10.1016/j.jaci.2016.08.030] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 08/03/2016] [Accepted: 08/10/2016] [Indexed: 11/17/2022]
Abstract
BACKGROUND Common variable immunodeficiency (CVID) is a heterogeneous syndrome characterized by impaired immunoglobulin production and usually presents with a normal quantity of peripheral B cells. Most attempts aiming to classify these patients have mainly been focused on T- or B-cell phenotypes and their ability to produce protective antibodies, but it is still a major challenge to find a suitable classification that includes the clinical and immunologic heterogeneity of these patients. OBJECTIVE In this study we evaluated the late stages of B-cell differentiation in a heterogeneous population of patients with pediatric-onset CVID to clinically correlate and assess their ability to perform somatic hypermutation (SHM), class-switch recombination (CSR), or both. METHODS We performed a previously reported assay, the restriction enzyme hotspot mutation assay (IgκREHMA), to evaluate in vivo SHM status. We amplified switch regions from genomic DNA to investigate the quality of the double-strand break repairs in the class-switch recombination process in vivo. We also tested the ability to generate immunoglobulin germline and circle transcripts and to upregulate the activation-induced cytidine deaminase gene through in vitro T-dependent and T-independent stimuli. RESULTS Our results showed that patients could be classified into 2 groups according to their degree of SHM alteration. This stratification showed a significant association between patients of group A, severe alteration, and the presence of noninfectious complications. Additionally, 60% of patients presented with increased microhomology use at switched regions. In vitro activation revealed that patients with CVID behaved heterogeneously in terms of responsiveness to T-dependent stimuli. CONCLUSIONS The correlation between noninfectious complications and SHM could be an important tool for physicians to further characterize patients with CVID. This categorization would help to improve elucidation of the complex mechanisms involved in B-cell differentiation pathways.
Collapse
Affiliation(s)
- María Belén Almejún
- Servicio de Immunología y Reumatología, Hospital Nacional de Pediatría Prof. Dr Juan P. Garrahan, Buenos Aires, Argentina.
| | - Bárbara Carolina Campos
- Coordinación de Laboratorio, Hospital Nacional de Pediatría Prof. Dr Juan P. Garrahan, Buenos Aires, Argentina
| | - Virginia Patiño
- Unidad de Proteínas Recombinantes, Instituto Pasteur, Montevideo, Uruguay
| | - Miguel Galicchio
- Hospital de Niños Víctor J. Vilela, Rosario, Santa Fé, Argentina
| | - Marta Zelazko
- Servicio de Immunología y Reumatología, Hospital Nacional de Pediatría Prof. Dr Juan P. Garrahan, Buenos Aires, Argentina
| | - Matías Oleastro
- Servicio de Immunología y Reumatología, Hospital Nacional de Pediatría Prof. Dr Juan P. Garrahan, Buenos Aires, Argentina
| | - Pablo Oppezzo
- Unidad de Proteínas Recombinantes, Instituto Pasteur, Montevideo, Uruguay
| | - Silvia Danielian
- Servicio de Immunología y Reumatología, Hospital Nacional de Pediatría Prof. Dr Juan P. Garrahan, Buenos Aires, Argentina
| |
Collapse
|
35
|
Pham P, Afif SA, Shimoda M, Maeda K, Sakaguchi N, Pedersen LC, Goodman MF. Structural analysis of the activation-induced deoxycytidine deaminase required in immunoglobulin diversification. DNA Repair (Amst) 2016; 43:48-56. [PMID: 27258794 DOI: 10.1016/j.dnarep.2016.05.029] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 05/10/2016] [Indexed: 12/18/2022]
Abstract
Activation-induced deoxycytidine deaminase (AID) initiates somatic hypermutation (SHM) and class-switch recombination (CSR) by deaminating C→U during transcription of Ig-variable (V) and Ig-switch (S) region DNA, which is essential to produce high-affinity antibodies. Here we report the crystal structure of a soluble human AID variant at 2.8Å resolution that favors targeting WRC motifs (W=A/T, R=A/G) in vitro, and executes Ig V SHM in Ramos B-cells. A specificity loop extending away from the active site to accommodate two purine bases next to C, differs significantly in sequence, length, and conformation from APOBEC proteins Apo3A and Apo3G, which strongly favor pyrimidines at -1 and -2 positions. Individual amino acid contributions to specificity and processivity were measured in relation to a proposed ssDNA binding cleft. This study provides a structural basis for residue contributions to DNA scanning properties unique to AID, and for disease mutations in human HIGM-2 syndrome.
Collapse
Affiliation(s)
- Phuong Pham
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, United States
| | - Samir A Afif
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, United States
| | - Mayuko Shimoda
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto, 860-8556, Japan; Laboratory of Host Defence, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita, 565-0871, Japan; World Premier International Research Center Initiative, Immunology Frontier Research Center, Osaka University, 3-1 Yamada-oka, Suita, 565-0871, Japan
| | - Kazuhiko Maeda
- Laboratory of Host Defence, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita, 565-0871, Japan; World Premier International Research Center Initiative, Immunology Frontier Research Center, Osaka University, 3-1 Yamada-oka, Suita, 565-0871, Japan
| | - Nobuo Sakaguchi
- World Premier International Research Center Initiative, Immunology Frontier Research Center, Osaka University, 3-1 Yamada-oka, Suita, 565-0871, Japan; Tokyo Metropolitan Institute of Medical Science, 2-1-6, Kamikitazawa, Setagaya-ku, Tokyo, 156-8506, Japan
| | - Lars C Pedersen
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC, 27709, United States
| | - Myron F Goodman
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, United States; Department of Chemistry, University of Southern California, Los Angeles, CA 90089, United States.
| |
Collapse
|
36
|
Enrichment of rare variants in population isolates: single AICDA mutation responsible for hyper-IgM syndrome type 2 in Finland. Eur J Hum Genet 2016; 24:1473-8. [PMID: 27142677 PMCID: PMC5027683 DOI: 10.1038/ejhg.2016.37] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 02/12/2016] [Accepted: 03/15/2016] [Indexed: 01/21/2023] Open
Abstract
Antibody class-switch recombination and somatic hypermutation critically depend on the function of activation-induced cytidine deaminase (AID). Rare variants in its gene AICDA have been reported to cause autosomal recessive AID deficiency (autosomal recessive hyper-IgM syndrome type 2 (HIGM2)). Exome sequencing of a multicase Finnish family with an HIGM2 phenotype identified a rare, homozygous, variant (c.416T>C, p.(Met139Thr)) in the AICDA gene, found to be significantly enriched in the Finnish population compared with other populations of European origin (38.56-fold, P<0.001). The population history of Finland, characterized by a restricted number of founders, isolation and several population bottlenecks, has caused enrichment of certain rare disease-causing variants and losses of others, as part of a phenomenon called the Finnish Disease Heritage. Accordingly, rare founder mutations cause the majority of observed Finnish cases in these mostly autosomal recessive disorders that consequently are more frequent in Finland than elsewhere. Screening of all currently known Finnish patients with an HIGM2 phenotype showed them to be homozygous for p.(Met139Thr). All the Finnish p.(Met139Thr) carriers with available data on their geographic descent originated from the eastern and northeastern parts of Finland. They were observed to share more of their genome identity by descent (IBD) than Finns in general (P<0.001), and they all carried a 207.5-kb ancestral haplotype containing the variant. In conclusion, the identified p.(Met139Thr) variant is significantly enriched in Finns and explains all thus far found AID deficiencies in Finland.
Collapse
|
37
|
Nonaka T, Toda Y, Hiai H, Uemura M, Nakamura M, Yamamoto N, Asato R, Hattori Y, Bessho K, Minato N, Kinoshita K. Involvement of activation-induced cytidine deaminase in skin cancer development. J Clin Invest 2016; 126:1367-82. [PMID: 26974156 DOI: 10.1172/jci81522] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 02/04/2016] [Indexed: 01/30/2023] Open
Abstract
Most skin cancers develop as the result of UV light-induced DNA damage; however, a substantial number of cases appear to occur independently of UV damage. A causal link between UV-independent skin cancers and chronic inflammation has been suspected, although the precise mechanism underlying this association is unclear. Here, we have proposed that activation-induced cytidine deaminase (AID, encoded by AICDA) links chronic inflammation and skin cancer. We demonstrated that Tg mice expressing AID in the skin spontaneously developed skin squamous cell carcinoma with Hras and Trp53 mutations. Furthermore, genetic deletion of Aicda reduced tumor incidence in a murine model of chemical-induced skin carcinogenesis. AID was expressed in human primary keratinocytes in an inflammatory stimulus-dependent manner and was detectable in human skin cancers. Together, the results of this study indicate that inflammation-induced AID expression promotes skin cancer development independently of UV damage and suggest AID as a potential target for skin cancer therapeutics.
Collapse
|
38
|
Gitlin AD, von Boehmer L, Gazumyan A, Shulman Z, Oliveira TY, Nussenzweig MC. Independent Roles of Switching and Hypermutation in the Development and Persistence of B Lymphocyte Memory. Immunity 2016; 44:769-81. [PMID: 26944202 DOI: 10.1016/j.immuni.2016.01.011] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 12/16/2015] [Accepted: 01/20/2016] [Indexed: 01/11/2023]
Abstract
Somatic hypermutation (SHM) and class-switch recombination (CSR) increase the affinity and diversify the effector functions of antibodies during immune responses. Although SHM and CSR are fundamentally different, their independent roles in regulating B cell fate have been difficult to uncouple because a single enzyme, activation-induced cytidine deaminase (encoded by Aicda), initiates both reactions. Here, we used a combination of Aicda and antibody mutant alleles that separate the effects of CSR and SHM on polyclonal immune responses. We found that class-switching to IgG1 biased the fate choice made by B cells, favoring the plasma cell over memory cell fate without significantly affecting clonal expansion in the germinal center (GC). In contrast, SHM reduced the longevity of memory B cells by creating polyreactive specificities that were selected against over time. Our data define the independent contributions of SHM and CSR to the generation and persistence of memory in the antibody system.
Collapse
Affiliation(s)
- Alexander D Gitlin
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065 USA.
| | - Lotta von Boehmer
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065 USA
| | - Anna Gazumyan
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065 USA
| | - Ziv Shulman
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065 USA
| | - Thiago Y Oliveira
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065 USA
| | - Michel C Nussenzweig
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065 USA; Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065 USA.
| |
Collapse
|
39
|
Functional requirements of AID's higher order structures and their interaction with RNA-binding proteins. Proc Natl Acad Sci U S A 2016; 113:E1545-54. [PMID: 26929374 DOI: 10.1073/pnas.1601678113] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Activation-induced cytidine deaminase (AID) is essential for the somatic hypermutation (SHM) and class-switch recombination (CSR) of Ig genes. Although both the N and C termini of AID have unique functions in DNA cleavage and recombination, respectively, during SHM and CSR, their molecular mechanisms are poorly understood. Using a bimolecular fluorescence complementation (BiFC) assay combined with glycerol gradient fractionation, we revealed that the AID C terminus is required for a stable dimer formation. Furthermore, AID monomers and dimers form complexes with distinct heterogeneous nuclear ribonucleoproteins (hnRNPs). AID monomers associate with DNA cleavage cofactor hnRNP K whereas AID dimers associate with recombination cofactors hnRNP L, hnRNP U, and Serpine mRNA-binding protein 1. All of these AID/ribonucleoprotein associations are RNA-dependent. We propose that AID's structure-specific cofactor complex formations differentially contribute to its DNA-cleavage and recombination functions.
Collapse
|
40
|
Individual substitution mutations in the AID C terminus that ablate IgH class switch recombination. PLoS One 2015; 10:e0134397. [PMID: 26267846 PMCID: PMC4534307 DOI: 10.1371/journal.pone.0134397] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 07/08/2015] [Indexed: 11/19/2022] Open
Abstract
Activation-induced cytidine deaminase (AID) is essential for class switch recombination (CSR) and somatic hypermutation (SHM) of Ig genes. The C terminus of AID is required for CSR but not for SHM, but the reason for this is not entirely clear. By retroviral transduction of mutant AID proteins into aid-/- mouse splenic B cells, we show that 4 amino acids within the C terminus of mouse AID, when individually mutated to specific amino acids (R190K, A192K, L196S, F198S), reduce CSR about as much or more than deletion of the entire C terminal 10 amino acids. Similar to ΔAID, the substitutions reduce binding of UNG to Ig Sμ regions and some reduce binding of Msh2, both of which are important for introducing S region DNA breaks. Junctions between the IgH donor switch (S)μ and acceptor Sα regions from cells expressing ΔAID or the L196S mutant show increased microhomology compared to junctions in cells expressing wild-type AID, consistent with problems during CSR and the use of alternative end-joining, rather than non-homologous end-joining (NHEJ). Unlike deletion of the AID C terminus, 3 of the substitution mutants reduce DNA double-strand breaks (DSBs) detected within the Sμ region in splenic B cells undergoing CSR. Cells expressing these 3 substitution mutants also have greatly reduced mutations within unrearranged Sμ regions, and they decrease with time after activation. These results might be explained by increased error-free repair, but as the C terminus has been shown to be important for recruitment of NHEJ proteins, this appears unlikely. We hypothesize that Sμ DNA breaks in cells expressing these C terminus substitution mutants are poorly repaired, resulting in destruction of Sμ segments that are deaminated by these mutants. This could explain why these mutants cannot undergo CSR.
Collapse
|
41
|
Bonaud A, Lechouane F, Le Noir S, Monestier O, Cogné M, Sirac C. Efficient AID targeting of switch regions is not sufficient for optimal class switch recombination. Nat Commun 2015; 6:7613. [PMID: 26146363 DOI: 10.1038/ncomms8613] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 05/26/2015] [Indexed: 02/07/2023] Open
Abstract
Antibody affinity maturation relies on activation-induced cytidine deaminase (AID)-dependent somatic hypermutation (SHM) of immunoglobulin (Ig) loci. Class switch recombination (CSR) can in parallel occur between AID-targeted, transcribed, spliced and repetitive switch (S) regions. AID thus initiates not only mutations but also double-strand breaks (DSBs). What governs the choice between those two outcomes remains uncertain. Here we explore whether insertion of transcribed intronic S regions in a locus (Igκ) strongly recruiting AID is sufficient for efficient CSR. Although strongly targeted by AID and carrying internal deletions, the knocked-in S regions only undergo rare CSR-like events. This model confirms S regions as exquisite SHM targets, extending AID activity far from transcription initiation sites, and shows that such spliced and repetitive AID targets are not sufficient by themselves for CSR. Beyond transcription and AID recruitment, additional IgH elements are thus needed for CSR, restricting this hazardous gene remodelling to IgH loci.
Collapse
Affiliation(s)
- Amélie Bonaud
- Immunology, CNRS UMR 7276, Centre Nationale de la Recherche Scientifique, Université de Limoges, Limoges 87025, France
| | - Fabien Lechouane
- Immunology, CNRS UMR 7276, Centre Nationale de la Recherche Scientifique, Université de Limoges, Limoges 87025, France
| | - Sandrine Le Noir
- Immunology, CNRS UMR 7276, Centre Nationale de la Recherche Scientifique, Université de Limoges, Limoges 87025, France
| | - Olivier Monestier
- Immunology, CNRS UMR 7276, Centre Nationale de la Recherche Scientifique, Université de Limoges, Limoges 87025, France
| | - Michel Cogné
- 1] Immunology, CNRS UMR 7276, Centre Nationale de la Recherche Scientifique, Université de Limoges, Limoges 87025, France. [2] Institut Universitaire de France, Paris 75000, France
| | - Christophe Sirac
- Immunology, CNRS UMR 7276, Centre Nationale de la Recherche Scientifique, Université de Limoges, Limoges 87025, France
| |
Collapse
|
42
|
Sawai Y, Kodama Y, Shimizu T, Ota Y, Maruno T, Eso Y, Kurita A, Shiokawa M, Tsuji Y, Uza N, Matsumoto Y, Masui T, Uemoto S, Marusawa H, Chiba T. Activation-Induced Cytidine Deaminase Contributes to Pancreatic Tumorigenesis by Inducing Tumor-Related Gene Mutations. Cancer Res 2015; 75:3292-301. [PMID: 26113087 DOI: 10.1158/0008-5472.can-14-3028] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Accepted: 05/13/2015] [Indexed: 11/16/2022]
Abstract
Pancreatic ductal adenocarcinoma (PDAC) develops via an accumulation of various gene mutations. The mechanism underlying the mutations in PDAC development, however, is not fully understood. Recent insight into the close association between the mutation pattern of various cancers and specific mutagens led us to investigate the possible involvement of activation-induced cytidine deaminase (AID), a DNA editing enzyme, in pancreatic tumorigenesis. Our immunohistochemical findings revealed AID protein expression in human acinar ductal metaplasia, pancreatic intraepithelial neoplasia, and PDAC. Both the amount and intensity of the AID protein expression increased with the progression from precancerous to cancerous lesions in human PDAC tissues. To further assess the significance of ectopic epithelial AID expression in pancreatic tumorigenesis, we analyzed the phenotype of AID transgenic (AID Tg) mice. Consistent with our hypothesis that AID is involved in the mechanism of the mutations underlying pancreatic tumorigenesis, we found precancerous lesions developing in the pancreas of AID Tg mice. Using deep sequencing, we also detected Kras and c-Myc mutations in our analysis of the whole pancreas of AID Tg mice. In addition, Sanger sequencing confirmed the presence of Kras, c-Myc, and Smad4 mutations, with the typical mutational footprint of AID in precancerous lesions in AID Tg mice separated by laser capture microdissection. Taken together, our findings suggest that AID contributes to the development of pancreatic precancerous lesions by inducing tumor-related gene mutations. Our new mouse model without intentional manipulation of specific tumor-related genes provides a powerful system for analyzing the mutations involved in PDAC.
Collapse
Affiliation(s)
- Yugo Sawai
- Department of Gastroenterology and Hepatology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Yuzo Kodama
- Department of Gastroenterology and Hepatology, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
| | - Takahiro Shimizu
- Department of Gastroenterology and Hepatology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Yuji Ota
- Department of Gastroenterology and Hepatology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Takahisa Maruno
- Department of Gastroenterology and Hepatology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Yuji Eso
- Department of Gastroenterology and Hepatology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Akira Kurita
- Department of Gastroenterology and Hepatology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Masahiro Shiokawa
- Department of Gastroenterology and Hepatology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Yoshihisa Tsuji
- Department of Gastroenterology and Hepatology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Norimitsu Uza
- Department of Gastroenterology and Hepatology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Yuko Matsumoto
- Department of Gastroenterology and Hepatology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Toshihiko Masui
- Department of Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Shinji Uemoto
- Department of Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Hiroyuki Marusawa
- Department of Gastroenterology and Hepatology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Tsutomu Chiba
- Department of Gastroenterology and Hepatology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| |
Collapse
|
43
|
Expression of activation-induced cytidine deaminase is associated with a poor prognosis of diffuse large B cell lymphoma patients treated with CHOP-based chemotherapy. J Cancer Res Clin Oncol 2015; 142:27-36. [PMID: 26077666 DOI: 10.1007/s00432-015-2001-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 06/10/2015] [Indexed: 01/22/2023]
Abstract
PURPOSE Activation-induced cytidine deaminase (AID) is involved in somatic hypermutation and class switch recombination processes in the antibody formation. The AID activity induces gene mutations and could be associated with transformation processes of B cells. Nevertheless, the relation between AID expression and the prognosis of B cell lymphoma patients remains uncharacterized. METHODS We examined expression levels of the AID gene in 89 lymph node specimens from lymphoma and non-lymphoma patients with Northern blot analysis and investigated an association with their survival. RESULTS The AID gene was preferentially expressed in B cell lymphoma in particular in diffuse large B cell lymphoma and follicular lymphoma. We confirmed AID protein expression in the mRNA-positive but not in the negative specimens with Western blot analysis and immunohistochemical staining. Survival of the patients treated with cyclophosphamide-/doxorubicin-/vincristine-/prednisone-based chemotherapy demonstrated that the prognosis of diffuse large B cell patients was unfavorable in the mRNA-positive group compared with the negative group, and that AID expression levels were correlated with the poor prognosis. In contrast, AID expression was not linked with the prognosis of follicular lymphoma patients. CONCLUSIONS AID expression is a predictive marker for an unfavorable outcome in DLBCL patients treated with the chemotherapy.
Collapse
|
44
|
Identification of DNA cleavage- and recombination-specific hnRNP cofactors for activation-induced cytidine deaminase. Proc Natl Acad Sci U S A 2015; 112:5791-6. [PMID: 25902538 DOI: 10.1073/pnas.1506167112] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Activation-induced cytidine deaminase (AID) is essential for antibody class switch recombination (CSR) and somatic hypermutation (SHM). AID originally was postulated to function as an RNA-editing enzyme, based on its strong homology with apolipoprotein B mRNA-editing enzyme, catalytic polypeptide 1 (APOBEC1), the enzyme that edits apolipoprotein B-100 mRNA in the presence of the APOBEC cofactor APOBEC1 complementation factor/APOBEC complementation factor (A1CF/ACF). Because A1CF is structurally similar to heterogeneous nuclear ribonucleoproteins (hnRNPs), we investigated the involvement of several well-known hnRNPs in AID function by using siRNA knockdown and clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9-mediated disruption. We found that hnRNP K deficiency inhibited DNA cleavage and thereby induced both CSR and SHM, whereas hnRNP L deficiency inhibited only CSR and somewhat enhanced SHM. Interestingly, both hnRNPs exhibited RNA-dependent interactions with AID, and mutant forms of these proteins containing deletions in the RNA-recognition motif failed to rescue CSR. Thus, our study suggests that hnRNP K and hnRNP L may serve as A1CF-like cofactors in AID-mediated CSR and SHM.
Collapse
|
45
|
Stavnezer J, Schrader CE. IgH chain class switch recombination: mechanism and regulation. THE JOURNAL OF IMMUNOLOGY 2015; 193:5370-8. [PMID: 25411432 DOI: 10.4049/jimmunol.1401849] [Citation(s) in RCA: 168] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
IgH class switching occurs rapidly after activation of mature naive B cells, resulting in a switch from expression of IgM and IgD to expression of IgG, IgE, or IgA; this switch improves the ability of Abs to remove the pathogen that induces the humoral immune response. Class switching occurs by a deletional recombination between two switch regions, each of which is associated with a H chain constant region gene. Class switch recombination (CSR) is instigated by activation-induced cytidine deaminase, which converts cytosines in switch regions to uracils. The uracils are subsequently removed by two DNA-repair pathways, resulting in mutations, single-strand DNA breaks, and the double-strand breaks required for CSR. We discuss several aspects of CSR, including how CSR is induced, CSR in B cell progenitors, the roles of transcription and chromosomal looping in CSR, and the roles of certain DNA-repair enzymes in CSR.
Collapse
Affiliation(s)
- Janet Stavnezer
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA 01605
| | - Carol E Schrader
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA 01605
| |
Collapse
|
46
|
Kracker S, Di Virgilio M, Schwartzentruber J, Cuenin C, Forveille M, Deau MC, McBride KM, Majewski J, Gazumyan A, Seneviratne S, Grimbacher B, Kutukculer N, Herceg Z, Cavazzana M, Jabado N, Nussenzweig MC, Fischer A, Durandy A. An inherited immunoglobulin class-switch recombination deficiency associated with a defect in the INO80 chromatin remodeling complex. J Allergy Clin Immunol 2015; 135:998-1007.e6. [PMID: 25312759 PMCID: PMC4382329 DOI: 10.1016/j.jaci.2014.08.030] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 07/31/2014] [Accepted: 08/05/2014] [Indexed: 11/29/2022]
Abstract
BACKGROUND Immunoglobulin class-switch recombination defects (CSR-D) are rare primary immunodeficiencies characterized by impaired production of switched immunoglobulin isotypes and normal or elevated IgM levels. They are caused by impaired T:B cooperation or intrinsic B cell defects. However, many immunoglobulin CSR-Ds are still undefined at the molecular level. OBJECTIVE This study's objective was to delineate new causes of immunoglobulin CSR-Ds and thus gain further insights into the process of immunoglobulin class-switch recombination (CSR). METHODS Exome sequencing in 2 immunoglobulin CSR-D patients identified variations in the INO80 gene. Functional experiments were performed to assess the function of INO80 on immunoglobulin CSR. RESULTS We identified recessive, nonsynonymous coding variations in the INO80 gene in 2 patients affected by defective immunoglobulin CSR. Expression of wild-type INO80 in patients' fibroblastic cells corrected their hypersensitivity to high doses of γ-irradiation. In murine CH12-F3 cells, the INO80 complex accumulates at Sα and Eμ regions of the IgH locus, and downregulation of INO80 as well as its partners Reptin and Pontin impaired CSR. In addition, Reptin and Pontin were shown to interact with activation-induced cytidine deaminase. Finally, an abnormal separation of sister chromatids was observed upon INO80 downregulation in CH12-F3 cells, pinpointing its role in cohesin activity. CONCLUSION INO80 deficiency appears to be associated with defective immunoglobulin CSR. We propose that the INO80 complex modulates cohesin function that may be required during immunoglobulin switch region synapsis.
Collapse
Affiliation(s)
- Sven Kracker
- INSERM UMR 1163, The Human Lymphohematopoiesis Laboratory, Imagine Institute, Paris, France; Paris Descartes Sorbonne Paris Cité University, Imagine Institute, Paris, France
| | - Michela Di Virgilio
- Laboratory of Molecular Immunology, Howard Hughes Medical Institute, the Rockefeller University, New York, NY
| | - Jeremy Schwartzentruber
- Department of Human Genetics, McGill University and Genome Quebec Innovation Centre, Montreal, Quebec, Canada
| | - Cyrille Cuenin
- International Agency for Research on Cancer, F-69008 Lyon, Lyon, France
| | - Monique Forveille
- Center for Primary Immunodeficiencies, Hôpital Necker Enfants Malades, F-75015 Paris, Paris, France
| | - Marie-Céline Deau
- INSERM UMR 1163, The Human Lymphohematopoiesis Laboratory, Imagine Institute, Paris, France; Paris Descartes Sorbonne Paris Cité University, Imagine Institute, Paris, France
| | - Kevin M McBride
- Laboratory of Molecular Immunology, Howard Hughes Medical Institute, the Rockefeller University, New York, NY
| | - Jacek Majewski
- Department of Human Genetics, McGill University and Genome Quebec Innovation Centre, Montreal, Quebec, Canada
| | - Anna Gazumyan
- Laboratory of Molecular Immunology, Howard Hughes Medical Institute, the Rockefeller University, New York, NY
| | - Suranjith Seneviratne
- UCL Institute of Immunity and Transplantation, Royal Free London NHS Foundation Tust, London, United Kingdom
| | - Bodo Grimbacher
- UCL Institute of Immunity and Transplantation, Royal Free London NHS Foundation Tust, London, United Kingdom; Centre of Chronic Immunodeficiency, University Medical Center Freiburg and University of Freiburg, D-79106 Freiburg, Freiburg, Germany
| | - Necil Kutukculer
- Ege University Faculty of Medicine, Department of Pediatric Immunology, 35100 Bornova, Izmir, Turkey
| | - Zdenko Herceg
- International Agency for Research on Cancer, F-69008 Lyon, Lyon, France
| | - Marina Cavazzana
- INSERM UMR 1163, The Human Lymphohematopoiesis Laboratory, Imagine Institute, Paris, France; Paris Descartes Sorbonne Paris Cité University, Imagine Institute, Paris, France; Department of Biotherapy, AP-HP Hôpital Necker Enfants Malades, F-75015 Paris, Paris, France; Clinical Investigation Center (CIC)-Biotherapy GHU Ouest, INSERM-APHP (Assistance Publique des Hôpitaux de Paris), Paris, France
| | - Nada Jabado
- Department of Pediatrics, McGill University and McGill University Health Center, Montreal, Quebec, Canada
| | - Michel C Nussenzweig
- Laboratory of Molecular Immunology, Howard Hughes Medical Institute, the Rockefeller University, New York, NY
| | - Alain Fischer
- INSERM UMR 1163, The Human Lymphohematopoiesis Laboratory, Imagine Institute, Paris, France; Paris Descartes Sorbonne Paris Cité University, Imagine Institute, Paris, France; Department of Immunology and Hematology, Hôpital Necker Enfants Malades, F-75015 Paris, Paris, France; Collège de France, Paris, France
| | - Anne Durandy
- INSERM UMR 1163, The Human Lymphohematopoiesis Laboratory, Imagine Institute, Paris, France; Paris Descartes Sorbonne Paris Cité University, Imagine Institute, Paris, France; Department of Immunology and Hematology, Hôpital Necker Enfants Malades, F-75015 Paris, Paris, France.
| |
Collapse
|
47
|
Liang G, Liu G, Kitamura K, Wang Z, Chowdhury S, Monjurul AM, Wakae K, Koura M, Shimadu M, Kinoshita K, Muramatsu M. TGF-β suppression of HBV RNA through AID-dependent recruitment of an RNA exosome complex. PLoS Pathog 2015; 11:e1004780. [PMID: 25836330 PMCID: PMC4383551 DOI: 10.1371/journal.ppat.1004780] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 03/03/2015] [Indexed: 01/15/2023] Open
Abstract
Transforming growth factor (TGF)-β inhibits hepatitis B virus (HBV) replication although the intracellular effectors involved are not determined. Here, we report that reduction of HBV transcripts by TGF-β is dependent on AID expression, which significantly decreases both HBV transcripts and viral DNA, resulting in inhibition of viral replication. Immunoprecipitation reveals that AID physically associates with viral P protein that binds to specific virus RNA sequence called epsilon. AID also binds to an RNA degradation complex (RNA exosome proteins), indicating that AID, RNA exosome, and P protein form an RNP complex. Suppression of HBV transcripts by TGF-β was abrogated by depletion of either AID or RNA exosome components, suggesting that AID and the RNA exosome involve in TGF-β mediated suppression of HBV RNA. Moreover, AID-mediated HBV reduction does not occur when P protein is disrupted or when viral transcription is inhibited. These results suggest that induced expression of AID by TGF-β causes recruitment of the RNA exosome to viral RNP complex and the RNA exosome degrades HBV RNA in a transcription-coupled manner.
Collapse
Affiliation(s)
- Guoxin Liang
- Department of Molecular Genetics, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
- Department of Microbiology and Immunology, Columbia University, New York, New York, United States of America
| | - Guangyan Liu
- Department of Molecular Genetics, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
| | - Kouichi Kitamura
- Department of Molecular Genetics, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
| | - Zhe Wang
- Department of Molecular Genetics, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
- Division of Medical Oncology, Affiliated Zhongshan Hospital of Dalian University, Dalian, China
| | - Sajeda Chowdhury
- Department of Molecular Genetics, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
| | - Ahasan Md Monjurul
- Department of Molecular Genetics, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
| | - Kousho Wakae
- Department of Molecular Genetics, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
| | - Miki Koura
- Department of Molecular Genetics, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
| | - Miyuki Shimadu
- Department of Molecular Genetics, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
| | - Kazuo Kinoshita
- Evolutionary Medicine, Shiga Medical Center Research Institute, Moriyama, Japan
| | - Masamichi Muramatsu
- Department of Molecular Genetics, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
| |
Collapse
|
48
|
Sala C, Mattiuz G, Pietrobono S, Chicca A, Conticello SG. Splice variants of activation induced deaminase (AID) do not affect the efficiency of class switch recombination in murine CH12F3 cells. PLoS One 2015; 10:e0121719. [PMID: 25803053 PMCID: PMC4372541 DOI: 10.1371/journal.pone.0121719] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 02/18/2015] [Indexed: 12/11/2022] Open
Abstract
Activation Induced Deaminase (AID) triggers the antigen-driven antibody diversification processes through its ability to edit DNA. AID dependent DNA damage is also the cause of genetic alterations often found in mature B cell tumors. A number of splice variants of AID have been identified, for which a role in the modulation of its activity has been hypothesized. We have thus tested two of these splice variants, which we find catalytically inactive, for their ability to modulate the activity of endogenous AID in CH12F3 cells, a murine lymphoma cell line in which Class Switch Recombination (CSR) can be induced. In contrast to full-length AID, neither these splice variants or a catalytically impaired AID mutant affect the efficiency of Class Switch Recombination. Thus, while a role for these splice variants at the RNA level remains possible, it is unlikely that they exert any regulatory effect on the function of AID.
Collapse
Affiliation(s)
- Cesare Sala
- Core Research Laboratory—Istituto Toscano Tumori, Firenze, Italy
| | - Giorgio Mattiuz
- Core Research Laboratory—Istituto Toscano Tumori, Firenze, Italy
| | - Silvia Pietrobono
- Core Research Laboratory—Istituto Toscano Tumori, Firenze, Italy
- Department of Medical Biotechnologies, University of Siena, Siena, Italy
| | - Andrea Chicca
- Core Research Laboratory—Istituto Toscano Tumori, Firenze, Italy
| | - Silvestro G. Conticello
- Core Research Laboratory—Istituto Toscano Tumori, Firenze, Italy
- Department of Oncology—Azienda Ospedaliero-Universitaria Careggi, Firenze, Italy
- * E-mail:
| |
Collapse
|
49
|
Senger K, Hackney J, Payandeh J, Zarrin AA. Antibody Isotype Switching in Vertebrates. Results Probl Cell Differ 2015; 57:295-324. [PMID: 26537387 DOI: 10.1007/978-3-319-20819-0_13] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The humoral or antibody-mediated immune response in vertebrates has evolved to respond to diverse antigenic challenges in various anatomical locations. Diversification of the immunoglobulin heavy chain (IgH) constant region via isotype switching allows for remarkable plasticity in the immune response, including versatile tissue distribution, Fc receptor binding, and complement fixation. This enables antibody molecules to exert various biological functions while maintaining antigen-binding specificity. Different immunoglobulin (Ig) classes include IgM, IgD, IgG, IgE, and IgA, which exist as surface-bound and secreted forms. High-affinity autoantibodies are associated with various autoimmune diseases such as lupus and arthritis, while defects in components of isotype switching are associated with infections. A major route of infection used by a large number of pathogens is invasion of mucosal surfaces within the respiratory, digestive, or urinary tract. Most infections of this nature are initially limited by effector mechanisms such as secretory IgA antibodies. Mucosal surfaces have been proposed as a major site for the genesis of adaptive immune responses, not just in fighting infections but also in tolerating commensals and constant dietary antigens. We will discuss the evolution of isotype switching in various species and provide an overview of the function of various isotypes with a focus on IgA, which is universally important in gut homeostasis as well as pathogen clearance. Finally, we will discuss the utility of antibodies as therapeutic modalities.
Collapse
Affiliation(s)
- Kate Senger
- Department of Immunology, Genentech Inc., South San Francisco, CA, 94080, USA
| | - Jason Hackney
- Department of Bioinformatics, Genentech Inc., South San Francisco, CA, 94080, USA
| | - Jian Payandeh
- Department of Structural Biology, Genentech Inc., South San Francisco, CA, 94080, USA
| | - Ali A Zarrin
- Department of Immunology, Genentech Inc., South San Francisco, CA, 94080, USA.
| |
Collapse
|
50
|
Dahlberg CIM, He M, Visnes T, Torres ML, Cortizas EM, Verdun RE, Westerberg LS, Severinson E, Ström L. A novel mouse model for the hyper-IgM syndrome: a spontaneous activation-induced cytidine deaminase mutation leading to complete loss of Ig class switching and reduced somatic hypermutation. THE JOURNAL OF IMMUNOLOGY 2014; 193:4732-8. [PMID: 25252954 DOI: 10.4049/jimmunol.1401242] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We describe a spontaneously derived mouse line that completely failed to induce Ig class switching in vitro and in vivo. The mice inherited abolished IgG serum titers in a recessive manner caused by a spontaneous G → A transition mutation in codon 112 of the aicda gene, leading to an arginine to histidine replacement (AID(R112H)). Ig class switching was completely reconstituted by expressing wild-type AID. Mice homozygous for AID(R112H) had peripheral B cell hyperplasia and large germinal centers in the absence of Ag challenge. Immunization with SRBCs elicited an Ag-specific IgG1 response in wild-type mice, whereas AID(R112H) mice failed to produce IgG1 and had reduced somatic hypermutation. The phenotype recapitulates the human hyper-IgM (HIGM) syndrome that is caused by point mutations in the orthologous gene in humans, and the AID(R112H) mutation is frequently found in HIGM patients. The AID(R112H) mouse model for HIGM provides a powerful and more precise tool than conventional knockout strategies.
Collapse
Affiliation(s)
- Carin I M Dahlberg
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Minghui He
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Torkild Visnes
- Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden; and
| | - Magda Liz Torres
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Elena M Cortizas
- Division of Gerontology and Geriatric Medicine, Department of Medicine, Miller School of Medicine, University of Miami, Miami, FL 33136
| | - Ramiro E Verdun
- Division of Gerontology and Geriatric Medicine, Department of Medicine, Miller School of Medicine, University of Miami, Miami, FL 33136
| | - Lisa S Westerberg
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden;
| | - Eva Severinson
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden;
| | - Lena Ström
- Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden; and
| |
Collapse
|