1
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Mina ED, 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.
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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.
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2
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Jiao J, Lv Z, Wang Y, Fan L, Yang A. The off-target effects of AID in carcinogenesis. Front Immunol 2023; 14:1221528. [PMID: 37600817 PMCID: PMC10436223 DOI: 10.3389/fimmu.2023.1221528] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 07/10/2023] [Indexed: 08/22/2023] Open
Abstract
Activation-induced cytidine deaminase (AID) plays a crucial role in promoting B cell diversification through somatic hypermutation (SHM) and class switch recombination (CSR). While AID is primarily associated with the physiological function of humoral immune response, it has also been linked to the initiation and progression of lymphomas. Abnormalities in AID have been shown to disrupt gene networks and signaling pathways in both B-cell and T-cell lineage lymphoblastic leukemia, although the full extent of its role in carcinogenesis remains unclear. This review proposes an alternative role for AID and explores its off-target effects in regulating tumorigenesis. In this review, we first provide an overview of the physiological function of AID and its regulation. AID plays a crucial role in promoting B cell diversification through SHM and CSR. We then discuss the off-target effects of AID, which includes inducing mutations of non-Igs, epigenetic modification, and the alternative role as a cofactor. We also explore the networks that keep AID in line. Furthermore, we summarize the off-target effects of AID in autoimmune diseases and hematological neoplasms. Finally, we assess the off-target effects of AID in solid tumors. The primary focus of this review is to understand how and when AID targets specific gene loci and how this affects carcinogenesis. Overall, this review aims to provide a comprehensive understanding of the physiological and off-target effects of AID, which will contribute to the development of novel therapeutic strategies for autoimmune diseases, hematological neoplasms, and solid tumors.
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Affiliation(s)
- Junna Jiao
- School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, Henan, China
| | - Zhuangwei Lv
- School of Forensic Medicine, Xinxiang Medical University, Xinxiang, Henan, China
| | - Yurong Wang
- School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, Henan, China
| | - Liye Fan
- School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, Henan, China
| | - Angang Yang
- Henan Key Laboratory of Immunology and Targeted Therapy, School of Laboratory Medicine, Xinxiang Medical University, Xinxiang, Henan, China
- The State Key Laboratory of Cancer Biology, Department of Biochemistry and Molecular Biology, Fourth Military Medical University, Xi'an, Shaanxi, China
- Henan Collaborative Innovation Center of Molecular Diagnosis and Laboratory Medicine, School of Laboratory Medicine, Xinxiang Medical University, Xinxiang, Henan, China
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3
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Conn VM, Gabryelska M, Toubia J, Kirk K, Gantley L, Powell JA, Cildir G, Marri S, Liu R, Stringer BW, Townley S, Webb ST, Lin H, Samaraweera SE, Bailey S, Moore AS, Maybury M, Liu D, Colella AD, Chataway T, Wallington-Gates CT, Walters L, Sibbons J, Selth LA, Tergaonkar V, D'Andrea RJ, Pitson SM, Goodall GJ, Conn SJ. Circular RNAs drive oncogenic chromosomal translocations within the MLL recombinome in leukemia. Cancer Cell 2023; 41:1309-1326.e10. [PMID: 37295428 DOI: 10.1016/j.ccell.2023.05.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 03/03/2023] [Accepted: 05/03/2023] [Indexed: 06/12/2023]
Abstract
The first step of oncogenesis is the acquisition of a repertoire of genetic mutations to initiate and sustain the malignancy. An important example of this initiation phase in acute leukemias is the formation of a potent oncogene by chromosomal translocations between the mixed lineage leukemia (MLL) gene and one of 100 translocation partners, known as the MLL recombinome. Here, we show that circular RNAs (circRNAs)-a family of covalently closed, alternatively spliced RNA molecules-are enriched within the MLL recombinome and can bind DNA, forming circRNA:DNA hybrids (circR loops) at their cognate loci. These circR loops promote transcriptional pausing, proteasome inhibition, chromatin re-organization, and DNA breakage. Importantly, overexpressing circRNAs in mouse leukemia xenograft models results in co-localization of genomic loci, de novo generation of clinically relevant chromosomal translocations mimicking the MLL recombinome, and hastening of disease onset. Our findings provide fundamental insight into the acquisition of chromosomal translocations by endogenous RNA carcinogens in leukemia.
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Affiliation(s)
- Vanessa M Conn
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia; Centre for Cancer Biology, SA Pathology & University of South Australia, Adelaide, SA 5000, Australia
| | - Marta Gabryelska
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia
| | - John Toubia
- Centre for Cancer Biology, SA Pathology & University of South Australia, Adelaide, SA 5000, Australia; ACRF Cancer Genomics Facility, SA Pathology, Adelaide, SA 5000, Australia
| | - Kirsty Kirk
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia
| | - Laura Gantley
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia
| | - Jason A Powell
- Centre for Cancer Biology, SA Pathology & University of South Australia, Adelaide, SA 5000, Australia; Adelaide Medical School, Faculty of Health and Medical Sciences, the University of Adelaide, Adelaide, SA 5000, Australia
| | - Gökhan Cildir
- Centre for Cancer Biology, SA Pathology & University of South Australia, Adelaide, SA 5000, Australia
| | - Shashikanth Marri
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia
| | - Ryan Liu
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia
| | - Brett W Stringer
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia
| | - Scott Townley
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia
| | - Stuart T Webb
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia
| | - He Lin
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia
| | - Saumya E Samaraweera
- Centre for Cancer Biology, SA Pathology & University of South Australia, Adelaide, SA 5000, Australia
| | - Sheree Bailey
- Health and Biomedical Innovation, Clinical and Health Sciences, University of South Australia, Adelaide, SA 5000, Australia
| | - Andrew S Moore
- Child Health Research Centre, the University of Queensland, Brisbane, QLD 4101, Australia; Oncology Service, Children's Health Queensland Hospital and Health Service, Brisbane, QLD 4101, Australia
| | - Mellissa Maybury
- Child Health Research Centre, the University of Queensland, Brisbane, QLD 4101, Australia
| | - Dawei Liu
- Centre for Cancer Biology, SA Pathology & University of South Australia, Adelaide, SA 5000, Australia
| | - Alex D Colella
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia; Flinders Omics Facility, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia
| | - Timothy Chataway
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia; Flinders Omics Facility, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia
| | - Craig T Wallington-Gates
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia; Centre for Cancer Biology, SA Pathology & University of South Australia, Adelaide, SA 5000, Australia; Adelaide Medical School, Faculty of Health and Medical Sciences, the University of Adelaide, Adelaide, SA 5000, Australia; Flinders Medical Centre, Bedford Park, SA 5042, Australia
| | - Lucie Walters
- Adelaide Rural Clinical School, Faculty of Health and Medical Sciences, the University of Adelaide, Adelaide, SA 5000, Australia
| | - Jane Sibbons
- Adelaide Microscopy, Division of Research and Innovation, University of Adelaide, Adelaide, SA 5000, Australia
| | - Luke A Selth
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia; Freemasons Centre for Male Health and Wellbeing, Flinders University, Bedford Park, SA 5042, Australia
| | - Vinay Tergaonkar
- Laboratory of NFκB Signalling, Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A(∗)STAR), 61 Biopolis Drive, Proteos, Singapore 138673, Republic of Singapore
| | - Richard J D'Andrea
- Centre for Cancer Biology, SA Pathology & University of South Australia, Adelaide, SA 5000, Australia
| | - Stuart M Pitson
- Centre for Cancer Biology, SA Pathology & University of South Australia, Adelaide, SA 5000, Australia; Adelaide Medical School, Faculty of Health and Medical Sciences, the University of Adelaide, Adelaide, SA 5000, Australia
| | - Gregory J Goodall
- Centre for Cancer Biology, SA Pathology & University of South Australia, Adelaide, SA 5000, Australia; Adelaide Medical School, Faculty of Health and Medical Sciences, the University of Adelaide, Adelaide, SA 5000, Australia
| | - Simon J Conn
- Flinders Health and Medical Research Institute, College of Medicine & Public Health, Flinders University, Bedford Park, SA 5042, Australia; Centre for Cancer Biology, SA Pathology & University of South Australia, Adelaide, SA 5000, Australia.
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4
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Inflammation accelerates BCR-ABL1+ B-ALL development through upregulation of AID. Blood Adv 2022; 6:4060-4072. [PMID: 35816360 PMCID: PMC9278295 DOI: 10.1182/bloodadvances.2021005017] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 05/03/2022] [Indexed: 11/20/2022] Open
Abstract
Inflammatory stimulation promotes BCR-ABL1+ B-ALL disease progression by upregulating AID. Combination of imatinib and Hsp90 inhibitors significantly delays the inflammation-induced progression of BCR-ABL1+ B-ALL.
Inflammation contributes to the initiation and disease progression of several lymphoid malignancies. BCR-ABL1-positive B-cell acute lymphoblastic leukemia (BCR-ABL1+ B-ALL) is triggered by the malignant cloning of immature B cells promoted by the BCR-ABL1 fusion gene. However, it is unclear whether the mechanism driving the disease progression of BCR-ABL1+ B-ALL involves inflammatory stimulation. Here, we evaluate BCR-ABL1+ B-ALL cells’ response to inflammatory stimuli lipopolysaccharide (LPS) in vitro and in vivo. The results indicate that LPS promotes cell growth and genomic instability in cultured BCR-ABL1+ B-ALL cells and accelerates the BCR-ABL1+ B-ALL development in a mouse model. We show that the LPS-induced upregulation of activation-induced deaminase (AID) is required for the cell growth and disease progression of BCR-ABL1+ B-ALL. Moreover, AID modulates the expression of various genes that are dominated by suppressing apoptosis genes and upregulating DNA damage-repair genes. These genes lead to facilitation for BCR-ABL1+ B-ALL progression. The heat shock protein 90 (Hsp90) inhibitors significantly reduce AID protein level and delay the disease progression of BCR-ABL1+ B-ALL upon inflammatory stimulation. The present data demonstrate the causative role of AID in the development and progression of BCR-ABL1+ B-ALL during inflammation, thus highlighting potential therapeutic targets.
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5
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Shilova ON, Tsyba DL, Shilov ES. Mutagenic Activity of AID/APOBEC Deaminases in Antiviral Defense and Carcinogenesis. Mol Biol 2022; 56:46-58. [PMID: 35194245 PMCID: PMC8852905 DOI: 10.1134/s002689332201006x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 04/23/2021] [Accepted: 06/01/2021] [Indexed: 01/02/2023]
Abstract
Proteins of the AID/APOBEC family are capable of cytidine deamination in nucleic acids forming uracil. These enzymes are involved in mRNA editing, protection against viruses, the introduction of point mutations into DNA during somatic hypermutation, and antibody isotype switching. Since these deaminases, especially AID, are potent mutagens, their expression, activity, and specificity are regulated by several intracellular mechanisms. In this review, we discuss the mechanisms of impaired expression and activation of AID/APOBEC proteins in human tumors and their role in carcinogenesis and tumor progression. Also, the diagnostic and potential therapeutic value of increased expression of AID/APOBEC in different types of tumors is analyzed. We assume that in the case of solid tumors, increased expression of endogenous deaminases can serve as a marker of response to immunotherapy since multiple point mutations in host DNA could lead to amino acid substitutions in tumor proteins and thereby increase the frequency of neoepitopes.
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Affiliation(s)
- O. N. Shilova
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
| | - D. L. Tsyba
- Pavlov First State Medical University, 197022 St. Petersburg, Russia
- Sirius University of Science and Technology, 354340 Sochi, Russia
| | - E. S. Shilov
- Faculty of Biology, Moscow State University, 119234 Moscow, Russia
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6
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USP10 regulates B cell response to SARS-CoV-2 or HIV-1 nanoparticle vaccines through deubiquitinating AID. Signal Transduct Target Ther 2022; 7:7. [PMID: 34983926 PMCID: PMC8724756 DOI: 10.1038/s41392-021-00858-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 11/28/2021] [Accepted: 12/07/2021] [Indexed: 12/13/2022] Open
Abstract
Activation-induced cytidine deaminase (AID) initiates class-switch recombination and somatic hypermutation (SHM) in antibody genes. Protein expression and activity are tightly controlled by various mechanisms. However, it remains unknown whether a signal from the extracellular environment directly affects the AID activity in the nucleus where it works. Here, we demonstrated that a deubiquitinase USP10, which specifically stabilizes nuclear AID protein, can translocate into the nucleus after AKT-mediated phosphorylation at its T674 within the NLS domain. Interestingly, the signals from BCR and TLR1/2 synergistically promoted this phosphorylation. The deficiency of USP10 in B cells significantly decreased AID protein levels, subsequently reducing neutralizing antibody production after immunization with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or human immunodeficiency virus type 1 (HIV-1) nanoparticle vaccines. Collectively, we demonstrated that USP10 functions as an integrator for both BCR and TLR signals and directly regulates nuclear AID activity. Its manipulation could be used for the development of vaccines and adjuvants.
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7
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Tepper S, Jeschke J, Böttcher K, Schmidt A, Davari K, Müller P, Kremmer E, Hemmerich P, Pfeil I, Jungnickel B. PARP activation promotes nuclear AID accumulation in lymphoma cells. Oncotarget 2017; 7:13197-208. [PMID: 26921193 PMCID: PMC4914351 DOI: 10.18632/oncotarget.7603] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 01/12/2016] [Indexed: 12/20/2022] Open
Abstract
Activation-induced cytidine deaminase (AID) initiates immunoglobulin diversification in germinal center B cells by targeted introduction of DNA damage. As aberrant nuclear AID action contributes to the generation of B cell lymphoma, the protein's activity is tightly regulated, e.g. by nuclear/cytoplasmic shuttling and nuclear degradation. In the present study, we asked whether DNA damage may affect regulation of the AID protein. We show that exogenous DNA damage that mainly activates base excision repair leads to prevention of proteasomal degradation of AID and hence its nuclear accumulation. Inhibitor as well as knockout studies indicate that activation of poly (ADP-ribose) polymerase (PARP) by DNA damaging agents promotes both phenomena. These findings suggest that PARP inhibitors influence DNA damage dependent AID regulation, with interesting implications for the regulation of AID function and chemotherapy of lymphoma.
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Affiliation(s)
- Sandra Tepper
- Department of Cell Biology, Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine, Friedrich-Schiller University, 07745 Jena, Germany
| | - Julia Jeschke
- Department of Cell Biology, Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine, Friedrich-Schiller University, 07745 Jena, Germany.,Institute of Clinical and Molecular Biology, Helmholtz Center Munich, 81377 Munich, Germany
| | - Katrin Böttcher
- Department of Cell Biology, Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine, Friedrich-Schiller University, 07745 Jena, Germany
| | - Angelika Schmidt
- Department of Cell Biology, Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine, Friedrich-Schiller University, 07745 Jena, Germany
| | - Kathrin Davari
- Department of Cell Biology, Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine, Friedrich-Schiller University, 07745 Jena, Germany
| | - Peter Müller
- Department of Cell Biology, Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine, Friedrich-Schiller University, 07745 Jena, Germany
| | - Elisabeth Kremmer
- Institute of Molecular Immunology, Helmholtz Center Munich, 81377 Munich, Germany
| | - Peter Hemmerich
- Imaging Facility, Leibniz- Institute on Aging - Fritz Lipmann Institute, 07745 Jena, Germany
| | - Ines Pfeil
- Institute of Clinical and Molecular Biology, Helmholtz Center Munich, 81377 Munich, Germany
| | - Berit Jungnickel
- Department of Cell Biology, Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine, Friedrich-Schiller University, 07745 Jena, Germany.,Institute of Clinical and Molecular Biology, Helmholtz Center Munich, 81377 Munich, Germany
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8
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Laffleur B, Basu U, Lim J. RNA Exosome and Non-coding RNA-Coupled Mechanisms in AID-Mediated Genomic Alterations. J Mol Biol 2017; 429:3230-3241. [PMID: 28069372 DOI: 10.1016/j.jmb.2016.12.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 12/21/2016] [Accepted: 12/27/2016] [Indexed: 12/31/2022]
Abstract
The eukaryotic RNA exosome is a well-conserved protein complex with ribonuclease activity implicated in RNA metabolism. Various families of non-coding RNAs have been identified as substrates of the complex, underscoring its role as a non-coding RNA processing/degradation unit. However, the role of RNA exosome and its RNA processing activity on DNA mutagenesis/alteration events have not been investigated until recently. B lymphocytes use two DNA alteration mechanisms, class switch recombination (CSR) and somatic hypermutation (SHM), to re-engineer their antibody gene expressing loci until a tailored antibody gene for a specific antigen is satisfactorily generated. CSR and SHM require the essential activity of the DNA activation-induced cytidine deaminase (AID). Causing collateral damage to the B-cell genome during CSR and SHM, AID induces unwanted (and sometimes oncogenic) mutations at numerous non-immunoglobulin gene sequences. Recent studies have revealed that AID's DNA mutator activity is regulated by the RNA exosome complex, thus providing an example of a mechanism that relates DNA mutagenesis to RNA processing. Here, we review the emergent functions of RNA exosome during CSR, SHM, and other chromosomal alterations in B cells, and discuss implications relevant to mechanisms that maintain B-cell genomic integrity.
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Affiliation(s)
- Brice Laffleur
- Department of Microbiology and Immunology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Uttiya Basu
- Department of Microbiology and Immunology, College of Physicians and Surgeons, Columbia University, New York, NY, USA.
| | - Junghyun Lim
- Department of Microbiology and Immunology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
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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.
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Affiliation(s)
- Harold C Smith
- a University of Rochester, School of Medicine and Dentistry , Department of Biochemistry and Biophysics , Rochester , NY , USA
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10
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Mutations, kataegis and translocations in B cells: understanding AID promiscuous activity. Nat Rev Immunol 2016; 16:164-76. [PMID: 26898111 DOI: 10.1038/nri.2016.2] [Citation(s) in RCA: 128] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
As B cells engage in the immune response, they express activation-induced cytidine deaminase (AID) to initiate the hypermutation and recombination of immunoglobulin genes, which are crucial processes for the efficient recognition and disposal of pathogens. However, AID must be tightly controlled in B cells to minimize off-target mutations, which can drive chromosomal translocations and the development of B cell malignancies, such as lymphomas. Recent genomic and biochemical analyses have begun to unravel the mechanisms of how AID-mediated deamination is targeted outside immunoglobulin genes. Here, we discuss the transcriptional and topological features that are emerging as key drivers of AID promiscuous activity.
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11
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He X, Li J, Wu J, Zhang M, Gao P. Associations between activation-induced cytidine deaminase/apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like cytidine deaminase expression, hepatitis B virus (HBV) replication and HBV-associated liver disease (Review). Mol Med Rep 2015; 12:6405-14. [PMID: 26398702 PMCID: PMC4626158 DOI: 10.3892/mmr.2015.4312] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 08/25/2015] [Indexed: 12/12/2022] Open
Abstract
The hepatitis B virus (HBV) infection is a major risk factor in the development of chronic hepatitis (CH) and hepa-tocellular carcinoma (HCC). The activation-induced cytidine deaminase (AID)/apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like (APOBEC) family of cytidine deaminases is significant in innate immunity, as it restricts numerous viruses, including HBV, through hypermutation-dependent and -independent mechanisms. It is important to induce covalently closed circular (ccc)DNA degradation by interferon-α without causing side effects in the infected host cell. Furthermore, organisms possess multiple mechanisms to regulate the expression of AID/APOBECs, control their enzymatic activity and restrict their access to DNA or RNA substrates. Therefore, the AID/APOBECs present promising targets for preventing and treating viral infections. In addition, gene polymorphisms of the AID/APOBEC family may alter host susceptibility to HBV acquisition and CH disease progression. Through G-to-A hypermutation, AID/APOBECs also edit HBV DNA and facilitate the mutation of HBV DNA, which may assist the virus to evolve and potentially escape from the immune responses. The AID/APOBEC family and their associated editing patterns may also exert oncogenic activity. Understanding the effects of cytidine deaminases in CH virus-induced hepatocarcinogenesis may aid with developing efficient prophylactic and therapeutic strategies against HCC.
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Affiliation(s)
- Xiuting He
- Department of Geriatrics, The First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China
| | - Jie Li
- Department of Geriatrics, The First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China
| | - Jing Wu
- Department of Geriatrics, The First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China
| | - Manli Zhang
- Department of Gastroenterology, The Second Branch of The First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China
| | - Pujun Gao
- Department of Hepatology, The First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China
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Li Q, Rao L, Zhang D, Xu Q. Expression features of DNA methylcytosine dioxygenase ten-eleven translocation 1 in human dental pulp cells. J Endod 2014; 40:1791-5. [PMID: 25179935 DOI: 10.1016/j.joen.2014.07.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 06/14/2014] [Accepted: 07/03/2014] [Indexed: 12/28/2022]
Abstract
INTRODUCTION Human dental pulp cells (hDPCs) can specifically generate reparative dentin under external stimuli, and numerous mechanisms are involved in their odontogenic differentiation process. Ten-eleven translocation 1 (TET1) is a recently discovered DNA dioxygenase that plays important roles in promoting DNA demethylation and transcriptional regulation. Although several studies regarding its effect on cell differentiation and proliferation have been conducted, the expression and function of TET1 have not yet been characterized in hDPCs. The purpose of this study was to explore the expression features of TET1 in hDPCs. METHODS Cellular TET1 localization in hDPCs was determined by immunofluorescence. The expression pattern of TET1 and its potential changes during odontogenic induction were confirmed using real-time quantitative polymerase chain reaction and Western blot analyses. RESULTS TET1 existed in both the cytoplasm and the nucleus of the hDPCs. During serial cell passaging, TET1 expression significantly increased until the 6th passage and then decreased from the 7th-9th passages (P < .05, n = 3). TET1 gene and protein expression increased during the odontogenic differentiation of the hDPCs in a time-dependent manner (P < .05, n = 3). CONCLUSIONS TET1 messenger RNA and protein were both present in the hDPCs. TET1 expression increased during early spontaneous differentiation and odontogenic induction.
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Affiliation(s)
- Qimeng Li
- Guanghua School of Stomatology and Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Lijia Rao
- Guanghua School of Stomatology and Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Deqian Zhang
- Guanghua School of Stomatology and Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Qiong Xu
- Guanghua School of Stomatology and Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China.
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Prohaska KM, Bennett RP, Salter JD, Smith HC. The multifaceted roles of RNA binding in APOBEC cytidine deaminase functions. WILEY INTERDISCIPLINARY REVIEWS-RNA 2014; 5:493-508. [PMID: 24664896 DOI: 10.1002/wrna.1226] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 02/13/2014] [Accepted: 02/13/2014] [Indexed: 01/06/2023]
Abstract
Cytidine deaminases have important roles in the regulation of nucleoside/deoxynucleoside pools for DNA and RNA synthesis. The APOBEC family of cytidine deaminases (named after the first member of the family that was described, Apolipoprotein B mRNA Editing Catalytic Subunit 1, also known as APOBEC1 or A1) is a fascinating group of mutagenic proteins that use RNA and single-stranded DNA (ssDNA) as substrates for their cytidine or deoxycytidine deaminase activities. APOBEC proteins and base-modification nucleic acid editing have been the subject of numerous publications, reviews, and speculation. These proteins play diverse roles in host cell defense, protecting cells from invading genetic material, enabling the acquired immune response to antigens and changing protein expression at the level of the genetic code in mRNA or DNA. The amazing power these proteins have for interphase cell functions relies on structural and biochemical properties that are beginning to be understood. At the same time, the substrate selectivity of each member in the family and their regulation remains to be elucidated. This review of the APOBEC family will focus on an open question in regulation, namely what role the interactions of these proteins with RNA have in editing substrate recognition or allosteric regulation of DNA mutagenic and host-defense activities.
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Abstract
In this review, I discuss the currently available experimental evidence concerning the molecular interactions of the activation-induced cytidine deaminase (AID) with transcription of its target genes. The basic question that underlies the transcription relationship is how the process of somatic hypermutation of Ig genes can be restricted to their variable (V) regions. This hallmark of SHM assures that high affinity antibodies can be created while the biological functions of their constant (C) region are undisturbed. I present a revised model of AID function in somatic hypermutation (SHM): In a B cell that produces AID protein and undergoes mutation of the V regions of the expressed Ig heavy and light chain genes, only some of the transcription complexes initiating at the active V-region promoters are associated with AID. When AID travels with the elongating RNA polymerase (pol), it attracts proteins that cause the pausing/stalling of pol and termination of transcription, followed by termination of SHM. This differential AID loading model would allow the mutating B cell to continue producing full-length Ig proteins that are required to avoid apoptosis by permitting the cell to assemble functional B cell receptors.
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Affiliation(s)
- Ursula Storb
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois, USA.
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Santos F, Peat J, Burgess H, Rada C, Reik W, Dean W. Active demethylation in mouse zygotes involves cytosine deamination and base excision repair. Epigenetics Chromatin 2013; 6:39. [PMID: 24279473 PMCID: PMC4037648 DOI: 10.1186/1756-8935-6-39] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 10/30/2013] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND DNA methylation in mammals is an epigenetic mark necessary for normal embryogenesis. During development active loss of methylation occurs in the male pronucleus during the first cell cycle after fertilisation. This is accompanied by major chromatin remodelling and generates a marked asymmetry between the paternal and maternal genomes. The mechanism(s) by which this is achieved implicate, among others, base excision repair (BER) components and more recently a major role for TET3 hydroxylase. To investigate these methylation dynamics further we have analysed DNA methylation and hydroxymethylation in fertilised mouse oocytes by indirect immunofluorescence (IF) and evaluated the relative contribution of different candidate factors for active demethylation in knock-out zygotes by three-dimensional imaging and IF semi-quantification. RESULTS We find two distinct phases of loss of paternal methylation in the zygote, one prior to and another coincident with, but not dependent on, DNA replication. TET3-mediated hydroxymethylation is limited to the replication associated second phase of demethylation. Analysis of cytosine deaminase (AID) null fertilised oocytes revealed a role for this enzyme in the second phase of loss of paternal methylation, which is independent from hydroxymethylation. Investigation into the possible repair pathways involved supports a role for AID-mediated cytosine deamination with subsequent U-G mismatch long-patch BER by UNG2 while no evidence could be found for an involvement of TDG. CONCLUSIONS There are two observable phases of DNA demethylation in the mouse zygote, before and coincident with DNA replication. TET3 is only involved in the second phase of loss of methylation. Cytosine deamination and long-patch BER mediated by UNG2 appear to independently contribute to this second phase of active demethylation. Further work will be necessary to elucidate the mechanism(s) involved in the first phase of active demethylation that will potentially involve activities required for early sperm chromatin remodelling.
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Habib O, Habib G, Do JT, Moon SH, Chung HM. Activation-induced deaminase-coupled DNA demethylation is not crucial for the generation of induced pluripotent stem cells. Stem Cells Dev 2013; 23:209-18. [PMID: 24083501 DOI: 10.1089/scd.2013.0337] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
DNA methylation constitutes a major obstacle in the reprogramming of cells to pluripotency. Although little is known regarding the molecular mechanisms of DNA demethylation, activation-induced deaminase (AID), which is known to function in antibody diversification, has been implicated in DNA demethylation through a base excision repair (BER)-mediated pathway. Here we comprehensively examine the plausibility of coupled AID-BER demethylation in the generation of induced pluripotent stem cells (iPSCs) and show that AID is dispensable for reprogramming cells into iPSCs. Additionally, the overexpression of AID and other factors involved in AID-coupled DNA demethylation does not increase the efficiency of reprogramming. Moreover, BER is not likely to play a role in this process. Our results indicate that the reactivation of key genes governing the pluripotency circuitry occurs through a mechanism that is independent of deamination-coupled demethylation.
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Affiliation(s)
- Omer Habib
- 1 School of Medicine, Konkuk University , Seoul, South Korea
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Solubility-based genetic screen identifies RING finger protein 126 as an E3 ligase for activation-induced cytidine deaminase. Proc Natl Acad Sci U S A 2012; 110:1029-34. [PMID: 23277564 DOI: 10.1073/pnas.1214538110] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Protein-protein interactions are typically identified by either biochemical purification coupled to mass spectrometry or genetic approaches exemplified by the yeast two-hybrid assay; however, neither assay works well for the identification of cofactors for poorly soluble proteins. Solubility of a poorly soluble protein is thought to increase upon cofactor binding, possibly by masking otherwise exposed hydrophobic domains. We have exploited this notion to develop a high-throughput genetic screen to identify interacting partners of an insoluble protein fused to chloramphenicol acetyltransferase by monitoring the survival of bacteria in the presence of a drug. In addition to presenting proof-of-principle experiments, we apply this screen to activation-induced cytidine deaminase (AID), a poorly soluble protein that is essential for antibody diversification. We identify a unique cofactor, RING finger protein 126 (RNF126), verify its interaction by traditional techniques, and show that it has functional consequences as RNF126 is able to ubiquitylate AID. Our results underpin the value of this screening technique and suggest a unique form of AID regulation involving RNF126 and ubiquitylation.
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Activation-induced cytidine deaminase alters the subcellular localization of Tet family proteins. PLoS One 2012; 7:e45031. [PMID: 23028748 PMCID: PMC3444495 DOI: 10.1371/journal.pone.0045031] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 08/11/2012] [Indexed: 01/09/2023] Open
Abstract
Activation-induced cytidine deminase (Aid), a unique enzyme that deaminates cytosine in DNA, shuttles between the nucleus and the cytoplasm. A recent study proposed a novel function of Aid in active DNA demethylation via deamination of 5-hydroxymethylcytosine, which is converted from 5-methylcytosine by the Ten-eleven translocation (Tet) family of enzymes. In this study, we examined the effect of simultaneous expression of Aid and Tet family proteins on the subcellular localization of each protein. We found that overexpressed Aid is mainly localized in the cytoplasm, whereas Tet1 and Tet2 are localized in the nucleus, and Tet3 is localized in both the cytoplasm and the nucleus. However, nuclear Tet proteins were gradually translocated to the cytoplasm when co-expressed with Aid. We also show that Aid-mediated translocation of Tet proteins is associated with Aid shuttling. Here we propose a possible role for Aid as a regulator of the subcellular localization of Tet family proteins.
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Häsler J, Rada C, Neuberger MS. The cytoplasmic AID complex. Semin Immunol 2012; 24:273-80. [PMID: 22698843 DOI: 10.1016/j.smim.2012.05.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Accepted: 05/18/2012] [Indexed: 12/28/2022]
Abstract
Although AID fulfils its physiological function of diversifying antibody genes in the nucleus, most of the AID protein within the cell is found in a complex located in the cytoplasm. In this review, we summarize what is currently known about this cytoplasmic AID complex. Its size has been estimated to lie between 300 and 500kDa (sedimentation coefficient of 10-11S) and it comprises the abundant protein translation elongation factor 1α (eEF1A) as a major stoichiometric component. We speculate on the possible roles of this complex as well as of chaperones known to interact with AID in regulating the cytosolic retention of AID and its controlled release for import into the nucleus.
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Affiliation(s)
- Julien Häsler
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK.
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Orthwein A, Di Noia JM. Activation induced deaminase: how much and where? Semin Immunol 2012; 24:246-54. [PMID: 22687198 DOI: 10.1016/j.smim.2012.05.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Accepted: 05/18/2012] [Indexed: 11/28/2022]
Abstract
Activation induced deaminase (AID) plays a central role in adaptive immunity by initiating the processes of somatic hypermutation (SHM) and class switch recombination (CSR). On the other hand, AID also predisposes to lymphoma and plays a role in some autoimmune diseases, for which reasons AID expression and activity are regulated at various levels. Post-translational mechanisms regulating the amount and subcellular localization of AID are prominent in balancing AID physiological and pathological functions in B cells. Mechanisms regulating AID protein levels include stabilizing chaperones in the cytoplasm and proteins efficiently targeting AID to the proteasome within the nucleus. Nuclear export and cytoplasmic retention contribute to limit the amount of AID accessing the genome. Additionally, a number of factors have been implicated in AID active nuclear import. We review these intertwined mechanisms proposing two scenarios in which they could interact as a network or as a cycle for defining the optimal amount of AID protein. We also comparatively review the expression levels of AID necessary for its function during the immune response, present in different cancers as well as in those tissues in which AID has been implicated in epigenetic remodeling of the genome by demethylating DNA.
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Affiliation(s)
- Alexandre Orthwein
- Institut de Recherches Cliniques de Montréal, Montréal, Québec, H2W 1R7, Canada
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Pone EJ, Xu Z, White CA, Zan H, Casali P. B cell TLRs and induction of immunoglobulin class-switch DNA recombination. Front Biosci (Landmark Ed) 2012; 17:2594-615. [PMID: 22652800 DOI: 10.2741/4073] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Toll-like receptors (TLRs) are a family of conserved pattern recognition receptors (PRRs). Engagement of B cell TLRs by microbe-associated molecular patterns (MAMPs) induces T-independent (TI) antibody responses and plays an important role in the early stages of T-dependent (TD) antibody responses before specific T cell help becomes available. The role of B cell TLRs in the antibody response is magnified by the synergy of B cell receptor (BCR) crosslinking and TLR engagement in inducing immunoglobulin (Ig) class switch DNA recombination (CSR), which crucially diversifies the antibody biological effector functions. Dual BCR/TLR engagement induces CSR to all Ig isotypes, as directed by cytokines, while TLR engagement alone induces marginal CSR. Integration of BCR and TLR signaling results in activation of the canonical and non-canonical NF-κB pathways, induction of activation-induced cytidine deaminase (AID) and germline transcription of IgH switch (S) regions. A critical role of B cell TLRs in CSR and the antibody response is emphasized by the emergence of several TLR ligands as integral components of vaccines that greatly boost humoral immunity in a B cell-intrinsic fashion.
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Affiliation(s)
- Egest J Pone
- Institute for Immunology, School of Medicine, University of California, Irvine, CA 92697-4120, USA
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22
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Orthwein A, Zahn A, Methot SP, Godin D, Conticello SG, Terada K, Di Noia JM. Optimal functional levels of activation-induced deaminase specifically require the Hsp40 DnaJa1. EMBO J 2011; 31:679-91. [PMID: 22085931 DOI: 10.1038/emboj.2011.417] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Accepted: 10/19/2011] [Indexed: 11/09/2022] Open
Abstract
The enzyme activation-induced deaminase (AID) deaminates deoxycytidine at the immunoglobulin genes, thereby initiating antibody affinity maturation and isotype class switching during immune responses. In contrast, off-target DNA damage caused by AID is oncogenic. Central to balancing immunity and cancer is AID regulation, including the mechanisms determining AID protein levels. We describe a specific functional interaction between AID and the Hsp40 DnaJa1, which provides insight into the function of both proteins. Although both major cytoplasmic type I Hsp40s, DnaJa1 and DnaJa2, are induced upon B-cell activation and interact with AID in vitro, only DnaJa1 overexpression increases AID levels and biological activity in cell lines. Conversely, DnaJa1, but not DnaJa2, depletion reduces AID levels, stability and isotype switching. In vivo, DnaJa1-deficient mice display compromised response to immunization, AID protein and isotype switching levels being reduced by half. Moreover, DnaJa1 farnesylation is required to maintain, and farnesyltransferase inhibition reduces, AID protein levels in B cells. Thus, DnaJa1 is a limiting factor that plays a non-redundant role in the functional stabilization of AID.
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Affiliation(s)
- Alexandre Orthwein
- Laboratory of Mechanisms of Genetic Diversity, Institut de Recherches Cliniques de Montréal, Montréal, Québec, Canada
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Smith HC, Bennett RP, Kizilyer A, McDougall WM, Prohaska KM. Functions and regulation of the APOBEC family of proteins. Semin Cell Dev Biol 2011; 23:258-68. [PMID: 22001110 DOI: 10.1016/j.semcdb.2011.10.004] [Citation(s) in RCA: 149] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 09/30/2011] [Accepted: 10/03/2011] [Indexed: 10/16/2022]
Abstract
APOBEC1 is a cytidine deaminase that edits messenger RNAs and was the first enzyme in the APOBEC family to be functionally characterized. Under appropriate conditions APOBEC1 also deaminates deoxycytidine in single-stranded DNA (ssDNA). The other ten members of the APOBEC family have not been fully characterized however several have deoxycytidine deaminase activity on ssDNAs. Despite the nucleic acid substrate preferences of different APOBEC proteins, a common feature appears to be their intrinsic ability to bind to RNA as well as to ssDNA. RNA binding to APOBEC proteins together with protein-protein interactions, post-translation modifications and subcellular localization serve as biological modulators controlling the DNA mutagenic activity of these potentially genotoxic proteins.
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Affiliation(s)
- Harold C Smith
- Department of Biochemistry and Biophysics, University of Rochester, School of Medicine and Dentistry, Rochester, NY 14642, USA.
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