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Sakai Y, Kuwahara K. Carcinogenesis caused by transcription-coupled DNA damage through GANP and other components of the TREX-2 complex. Pathol Int 2024; 74:103-118. [PMID: 38411330 DOI: 10.1111/pin.13415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Revised: 02/05/2024] [Accepted: 02/10/2024] [Indexed: 02/28/2024]
Abstract
Perturbation of genes is important for somatic hypermutation to increase antibody affinity during B-cell immunity; however, it may also promote carcinogenesis. Previous studies have revealed that transcription is an important process that can induce DNA damage and genomic instability. Transciption-export-2 (TREX-2) complex, which regulates messenger RNA (mRNA) nuclear export, has been studied in the budding yeast Saccharomyces cerevisiae; however, recent studies have started investigating the molecular function of the mammalian TREX-2 complex. The central molecule in the TREX-2 complex, that is, germinal center-associated nuclear protein (GANP), is closely associated with antibody affinity maturation as well as cancer etiology. In this review, we focus on carcinogenesis, lymphomagenesis, and teratomagenesis caused by transcription-coupled DNA damage through GANP and other components of the TREX-2 complex. We review the basic machinery of mRNA nuclear export and transcription-coupled DNA damage. We then briefly describe the immunological relationship between GANP and the affinity maturation of antibodies. Finally, we illustrate that the aberrant expression of the components of the TREX-2 complex, especially GANP, is associated with the etiology of various solid tumors, lymphomas, and testicular teratoma. These components serve as reliable predictors of cancer prognosis and response to chemotherapy.
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Affiliation(s)
- Yasuhiro Sakai
- Department of Tumor Pathology, Hamamatsu University School of Medicine, Shizuoka, Japan
- Department of Joint Research Laboratory of Clinical Medicine, Fujita Health University School of Medicine, Aichi, Japan
| | - Kazuhiko Kuwahara
- Department of Diagnostic Pathology, Kindai University Hospital, Osaka, Japan
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2
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Liu B, Jing Z, Zhang X, Chen Y, Mao S, Kaundal R, Zou Y, Wei G, Zang Y, Wang X, Lin W, Di M, Sun Y, Chen Q, Li Y, Xia J, Sun J, Lin CP, Huang X, Chi T. Large-scale multiplexed mosaic CRISPR perturbation in the whole organism. Cell 2022; 185:3008-3024.e16. [PMID: 35870449 DOI: 10.1016/j.cell.2022.06.039] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 04/23/2022] [Accepted: 06/20/2022] [Indexed: 12/13/2022]
Abstract
Here, we report inducible mosaic animal for perturbation (iMAP), a transgenic platform enabling in situ CRISPR targeting of at least 100 genes in parallel throughout the mouse body. iMAP combines Cre-loxP and CRISPR-Cas9 technologies and utilizes a germline-transmitted transgene carrying a large array of individually floxed, tandemly linked gRNA-coding units. Cre-mediated recombination triggers expression of all the gRNAs in the array but only one of them per cell, converting the mice to mosaic organisms suitable for phenotypic characterization and also for high-throughput derivation of conventional single-gene perturbation lines via breeding. Using gRNA representation as a readout, we mapped a miniature Perturb-Atlas cataloging the perturbations of 90 genes across 39 tissues, which yields rich insights into context-dependent gene functions and provides a glimpse of the potential of iMAP in genome decoding.
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Affiliation(s)
- Bo Liu
- Gene Editing Center, School of Life Sciences and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Zhengyu Jing
- Gene Editing Center, School of Life Sciences and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xiaoming Zhang
- Gene Editing Center, School of Life Sciences and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yuxin Chen
- Gene Editing Center, School of Life Sciences and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Shaoshuai Mao
- Gene Editing Center, School of Life Sciences and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Ravinder Kaundal
- Department of Immunobiology, Yale University Medical School, New Haven, CT 06520, USA
| | - Yan Zou
- Gene Editing Center, School of Life Sciences and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Ge Wei
- Gene Editing Center, School of Life Sciences and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Ying Zang
- Gene Editing Center, School of Life Sciences and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xinxin Wang
- Gene Editing Center, School of Life Sciences and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Wenyang Lin
- Gene Editing Center, School of Life Sciences and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Minghui Di
- Gene Editing Center, School of Life Sciences and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yiwen Sun
- Gene Editing Center, School of Life Sciences and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Qin Chen
- Gene Editing Center, School of Life Sciences and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yongqin Li
- Gene Editing Center, School of Life Sciences and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Jing Xia
- Gene Editing Center, School of Life Sciences and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Jianlong Sun
- Gene Editing Center, School of Life Sciences and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Chao-Po Lin
- Gene Editing Center, School of Life Sciences and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xingxu Huang
- Gene Editing Center, School of Life Sciences and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Tian Chi
- Gene Editing Center, School of Life Sciences and Technology, ShanghaiTech University, Shanghai 201210, China; Department of Immunobiology, Yale University Medical School, New Haven, CT 06520, USA.
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3
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Wang W, Wang L, Zha B. The roles of STAT6 in regulating B cell fate, activation, and function. Immunol Lett 2021; 233:87-91. [PMID: 33662403 DOI: 10.1016/j.imlet.2021.02.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 02/22/2021] [Accepted: 02/24/2021] [Indexed: 02/07/2023]
Abstract
Signal transducers and activators of transcription (STATs) family of proteins are the key signal molecules in the JAK-STAT classical activation pathway of cell biology. STAT6, as a member of the STATs family, is principally activated by IL-4 and IL-13. In addition to Th2 cell differentiation, it plays a crucial role in promoting the development, differentiation, and class switching of B cells. STAT6 deficiency leads to impaired immune function, decreased glycolysis, and morphological changes in B cells, which will help develop various diseases. In this review, we will systematically summarize the major findings of how STAT6 regulates B cells to reveal the potential of STAT6 in treating human diseases.
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Affiliation(s)
- Wei Wang
- Department of Endocrinology and Metabolism, Shanghai Fifth People's Hospital, Fudan University, Shanghai, 200240, China
| | - Luman Wang
- Department of Endocrinology and Metabolism, Shanghai Fifth People's Hospital, Fudan University, Shanghai, 200240, China; Department of Immunology, School of Basic Medical Sciences, and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Bingbing Zha
- Department of Endocrinology and Metabolism, Shanghai Fifth People's Hospital, Fudan University, Shanghai, 200240, China.
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4
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Sakai Y, Phimsen S, Okada S, Kuwahara K. The critical role of germinal center-associated nuclear protein in cell biology, immunohematology, and hematolymphoid oncogenesis. Exp Hematol 2020; 90:30-38. [PMID: 32827560 DOI: 10.1016/j.exphem.2020.08.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 08/14/2020] [Accepted: 08/16/2020] [Indexed: 11/16/2022]
Abstract
Germinal center-associated nuclear protein (GANP) is a unique and multifunctional protein that plays a critical role in cell biology, neurodegenerative disorders, immunohematology, and oncogenesis. GANP is an orthologue of Saccharomyces Sac3, one of the components of the transcription export 2 (TREX-2) complex and a messenger RNA (mRNA) nuclear export factor. GANP is widely conserved in all mammals, including humans. Although GANP was originally discovered as a molecule upregulated in the germinal centers of secondary lymphoid follicles in peripheral lymphoid organs, it is expressed ubiquitously in many tissues. It serves numerous functions, including making up part of the mammalian TREX-2 complex; mRNA nuclear export via nuclear pores; prevention of R-loop formation, genomic instability, and hyper-recombination; and B-cell affinity maturation. In this review, we first overview the extensive analyses that have revealed the basic functions of GANP and its ancestor molecule Sac3, including mRNA nuclear export and regulation of R-loop formation. We then describe how aberrant expression of GANP is significantly associated with cancer development. Moreover, we discuss a crucial role for GANP in B-cell development, especially affinity maturation in germinal centers. Finally, we illustrate that overexpression of GANP in B cells leads to lymphomagenesis resembling Hodgkin lymphoma derived from germinal center B cells, and that GANP may be involved in transdifferentiation of B cells to macrophages, which strongly affects Hodgkin lymphomagenesis.
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Affiliation(s)
- Yasuhiro Sakai
- Department of Diagnostic Pathology, Fujita Health University School of Medicine, Toyoake, Japan.
| | - Suchada Phimsen
- Department of Biochemistry, Faculty of Medical Science, Naresuan University, Phitsanulok, Thailand
| | - Seiji Okada
- Division of Hematopoiesis, Joint Research Center for Retroviral Infection, Kumamoto University, Kumamoto, Japan
| | - Kazuhiko Kuwahara
- Department of Diagnostic Pathology, Fujita Health University School of Medicine, Toyoake, Japan.
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5
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Sakai Y, Rezano A, Okada S, Ohtsuki T, Kawashima Y, Tsukamoto T, Suzuki M, Kohara M, Takeya M, Sakaguchi N, Kuwahara K. A Novel Cytological Model of B-Cell/Macrophage Biphenotypic Cell Hodgkin Lymphoma in Ganp-Transgenic Mice. Cancers (Basel) 2020; 12:cancers12010204. [PMID: 31947626 PMCID: PMC7017268 DOI: 10.3390/cancers12010204] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Revised: 01/09/2020] [Accepted: 01/11/2020] [Indexed: 11/20/2022] Open
Abstract
Hodgkin lymphoma (HL) is one of the most difficult neoplasms in terms of cytopathological research owing to the lack of established cytological murine models. Although HL is believed to be of lymphoid germinal center B-cell origin, HL cells exhibit unique biphenotypic characteristics of B cells and macrophages. B-cell/macrophage biphenotypic cells have also been identified in the spleen of Lyn-deficient mice. Moreover, Lyn-targeting germinal center-associated nuclear protein (GANP)-transgenic mice (Ig-ganpTg mice) spontaneously develop a lymphoid tumor. We aimed to investigate whether the lymphoid tumor developed in Ig-ganpTg mice exhibit biphenotypic characteristics of B cells/macrophages that correspond to human HL. Here, we demonstrated GANP overexpression in human HL cells and found that it may regulate transdifferentiation between B cells and macrophages. We also demonstrated that tumors were comparable with B-cell/macrophage biphenotypic Hodgkinoid lymphomas. The tumor cells expressed macrophage-related F4/80, CD68, and CD204 as well as cytoplasmic B220 and µ-/κ-chains; in addition, these cells exhibited phagocytic activity. These cells also expressed transcripts of CD30; c-fms; and the cytokines monocyte chemoattractant protein (MCP)-1, MCP-5, RANTES, tumor necrosis factor-α and thrombopoietin associated with macrophages as well as granulocyte/macrophage colony-stimulating factor, interleukin (IL)-4, IL-10, IL-12, and IL-13. Ig-ganpTg mice represent a novel cytological model for the study of cytopathological etiology and oncogenesis of HL.
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Affiliation(s)
- Yasuhiro Sakai
- Department of Diagnostic Pathology, Fujita Health University School of Medicine, Aichi 470-1192, Japan; (Y.S.); (Y.K.); (T.T.)
| | - Andri Rezano
- Department of Biomedical Sciences, Division of Cell Biology, Faculty of Medicine, Universitas Padjadjaran, West Java 45363, Indonesia;
| | - Seiji Okada
- Division of Hematopoiesis, Joint Research Center for Retroviral Infection, Kumamoto University, Kumamoto 860-0811, Japan;
| | - Takahiro Ohtsuki
- Department of Microbiology and Cell Biology, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan; (T.O.); (M.K.)
| | - Yoshiaki Kawashima
- Department of Diagnostic Pathology, Fujita Health University School of Medicine, Aichi 470-1192, Japan; (Y.S.); (Y.K.); (T.T.)
| | - Tetsuya Tsukamoto
- Department of Diagnostic Pathology, Fujita Health University School of Medicine, Aichi 470-1192, Japan; (Y.S.); (Y.K.); (T.T.)
| | - Motoshi Suzuki
- Department of Molecular Oncology, Fujita Health University School of Medicine, Aichi 470-1192, Japan;
| | - Michinori Kohara
- Department of Microbiology and Cell Biology, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan; (T.O.); (M.K.)
| | - Motohiro Takeya
- Department of Cell Pathology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan;
| | - Nobuo Sakaguchi
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan;
| | - Kazuhiko Kuwahara
- Department of Diagnostic Pathology, Fujita Health University School of Medicine, Aichi 470-1192, Japan; (Y.S.); (Y.K.); (T.T.)
- Correspondence: ; Tel.: +81-562-93-2319; Fax: +81-562-95-3761
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6
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Sedghi M, Moslemi AR, Cabrera-Serrano M, Ansari B, Ghasemi M, Baktashian M, Fattahpour A, Tajsharghi H. Recessive Charcot-Marie-Tooth and multiple sclerosis associated with a variant in MCM3AP. Brain Commun 2019; 1:fcz011. [PMID: 32954258 PMCID: PMC7425404 DOI: 10.1093/braincomms/fcz011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 07/17/2019] [Accepted: 07/18/2019] [Indexed: 01/09/2023] Open
Abstract
Variants in MCM3AP, encoding the germinal-centre associated nuclear protein, have been associated with progressive polyneuropathy with or without intellectual disability and ptosis in some cases, and with a complex phenotype with immunodeficiency, skin changes and myelodysplasia. MCM3AP encoded protein functions as an acetyltransferase that acetylates the replication protein, MCM3, and plays a key role in the regulation of DNA replication. In this study, we report a novel variant in MCM3AP (p.Ile954Thr), in a family including three affected individuals with characteristic features of Charcot-Marie-Tooth neuropathy and multiple sclerosis, an inflammatory condition of the central nervous system without known genetic cause. The affected individuals were homozygous for a missense MCM3AP variant, located at the Sac3 domain, which was predicted to affect conserved amino acid likely important for the function of the germinal-centre associated nuclear protein. Our data support further expansion of the clinical spectrum linked to MCM3AP variant and highlight that MCM3AP should be considered in patients with accompaniment of recessive motor axonal Charcot-Marie-Tooth neuropathy and multiple sclerosis.
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Affiliation(s)
- Maryam Sedghi
- Medical Genetics Laboratory, Alzahra University Hospital, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Ali-Reza Moslemi
- Department of Pathology, Sahlgrenska University Hospital, Gothenburg University, Gothenburg, Sweden
| | - Macarena Cabrera-Serrano
- Department of Neurology, Hospital Universitario Virgen del Rocio, Sevilla, Spain.,Instituto de Biomedicina de Sevilla, Universidad de Sevilla, Sevilla, Spain
| | - Behnaz Ansari
- Department of neurology, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Majid Ghasemi
- Department of neurology, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Mojtaba Baktashian
- Medical Genetics Laboratory, Alzahra University Hospital, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Ali Fattahpour
- Radiology Resident, Department of Radiology, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Homa Tajsharghi
- Division of Biomedicine, School of Health Science, University of Skovde, SE-541 28 Skovde, Sweden
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7
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Boller S, Li R, Grosschedl R. Defining B Cell Chromatin: Lessons from EBF1. Trends Genet 2018; 34:257-269. [PMID: 29336845 DOI: 10.1016/j.tig.2017.12.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 12/14/2017] [Accepted: 12/19/2017] [Indexed: 12/11/2022]
Abstract
Hematopoiesis is regulated by signals from the microenvironment, transcription factor networks, and changes of the epigenetic landscape. Transcription factors interact with and shape chromatin to allow for lineage- and cell type-specific changes in gene expression. During B lymphopoiesis, epigenetic regulation is observed in multilineage progenitors in which a specific chromatin context is established, at the onset of the B cell differentiation when early B cell factor 1 (EBF1) induces lineage-specific changes in chromatin, during V(D)J recombination and after antigen-driven activation of B cells and terminal differentiation. In this review, we discuss the epigenetic changes underlying B cell differentiation, focusing on the role of transcription factor EBF1 in B cell lineage priming.
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Affiliation(s)
- Sören Boller
- Department of Cellular and Molecular Immunology, Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany
| | - Rui Li
- Department of Cellular and Molecular Immunology, Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany
| | - Rudolf Grosschedl
- Department of Cellular and Molecular Immunology, Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany.
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8
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Methot S, Di Noia J. Molecular Mechanisms of Somatic Hypermutation and Class Switch Recombination. Adv Immunol 2017; 133:37-87. [DOI: 10.1016/bs.ai.2016.11.002] [Citation(s) in RCA: 165] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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9
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Verkoczy L. Humanized Immunoglobulin Mice: Models for HIV Vaccine Testing and Studying the Broadly Neutralizing Antibody Problem. Adv Immunol 2017; 134:235-352. [PMID: 28413022 PMCID: PMC5914178 DOI: 10.1016/bs.ai.2017.01.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A vaccine that can effectively prevent HIV-1 transmission remains paramount to ending the HIV pandemic, but to do so, will likely need to induce broadly neutralizing antibody (bnAb) responses. A major technical hurdle toward achieving this goal has been a shortage of animal models with the ability to systematically pinpoint roadblocks to bnAb induction and to rank vaccine strategies based on their ability to stimulate bnAb development. Over the past 6 years, immunoglobulin (Ig) knock-in (KI) technology has been leveraged to express bnAbs in mice, an approach that has enabled elucidation of various B-cell tolerance mechanisms limiting bnAb production and evaluation of strategies to circumvent such processes. From these studies, in conjunction with the wealth of information recently obtained regarding the evolutionary pathways and paratopes/epitopes of multiple bnAbs, it has become clear that the very features of bnAbs desired for their function will be problematic to elicit by traditional vaccine paradigms, necessitating more iterative testing of new vaccine concepts. To meet this need, novel bnAb KI models have now been engineered to express either inferred prerearranged V(D)J exons (or unrearranged germline V, D, or J segments that can be assembled into functional rearranged V(D)J exons) encoding predecessors of mature bnAbs. One encouraging approach that has materialized from studies using such newer models is sequential administration of immunogens designed to bind progressively more mature bnAb predecessors. In this review, insights into the regulation and induction of bnAbs based on the use of KI models will be discussed, as will new Ig KI approaches for higher-throughput production and/or altering expression of bnAbs in vivo, so as to further enable vaccine-guided bnAb induction studies.
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Affiliation(s)
- Laurent Verkoczy
- Duke University Human Vaccine Institute, Duke University School of Medicine, Durham, NC, United States.
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10
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Sakaguchi N, Maeda K. Germinal Center B-Cell-Associated Nuclear Protein (GANP) Involved in RNA Metabolism for B Cell Maturation. Adv Immunol 2016; 131:135-86. [PMID: 27235683 DOI: 10.1016/bs.ai.2016.02.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Germinal center B-cell-associated nuclear protein (GANP) is upregulated in germinal center B cells against T-cell-dependent antigens in mice and humans. In mice, GANP depletion in B cells impairs antibody affinity maturation. Conversely, its transgenic overexpression augments the generation of high-affinity antigen-specific B cells. GANP associates with AID in the cytoplasm, shepherds AID into the nucleus, and augments its access to the rearranged immunoglobulin (Ig) variable (V) region of the genome in B cells, thereby precipitating the somatic hypermutation of V region genes. GANP is also upregulated in human CD4(+) T cells and is associated with APOBEC3G (A3G). GANP interacts with A3G and escorts it to the virion cores to potentiate its antiretroviral activity by inactivating HIV-1 genomic cDNA. Thus, GANP is characterized as a cofactor associated with AID/APOBEC cytidine deaminase family molecules in generating diversity of the IgV region of the genome and genetic alterations of exogenously introduced viral targets. GANP, encoded by human chromosome 21, as well as its mouse equivalent on chromosome 10, contains a region homologous to Saccharomyces Sac3 that was characterized as a component of the transcription/export 2 (TREX-2) complex and was predicted to be involved in RNA export and metabolism in mammalian cells. The metabolism of RNA during its maturation, from the transcription site at the chromosome within the nucleus to the cytoplasmic translation apparatus, needs to be elaborated with regard to acquired and innate immunity. In this review, we summarize the current knowledge on GANP as a component of TREX-2 in mammalian cells.
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Affiliation(s)
- N Sakaguchi
- WPI Immunology Frontier Research Center (IFReC), Osaka University, Suita, Osaka, Japan; Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.
| | - K Maeda
- WPI Immunology Frontier Research Center (IFReC), Osaka University, Suita, Osaka, Japan; Laboratory of Host Defense, Research Institute for Microbial Diseases, Osaka University, Suita, Japan
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11
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Kuwahara K, Yamamoto-Ibusuki M, Zhang Z, Phimsen S, Gondo N, Yamashita H, Takeo T, Nakagata N, Yamashita D, Fukushima Y, Yamamoto Y, Iwata H, Saya H, Kondo E, Matsuo K, Takeya M, Iwase H, Sakaguchi N. GANP protein encoded on human chromosome 21/mouse chromosome 10 is associated with resistance to mammary tumor development. Cancer Sci 2016; 107:469-77. [PMID: 26749495 PMCID: PMC4832866 DOI: 10.1111/cas.12883] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 12/16/2015] [Accepted: 01/06/2016] [Indexed: 12/14/2022] Open
Abstract
Human chromosome 21 is known to be associated with the high risk of hematological malignancy but with resistance to breast cancer in the study of Down syndrome. In human cancers, we previously observed the significant alterations of the protein expression encoded by the ganp/MCM3AP gene on human chromosome 21q22.3. Here, we investigated GANP protein alterations in human breast cancer samples (416 cases) at various stages by immunohistochemical analysis. This cohort study clearly showed that expression of GANP is significantly decreased in human breast cancer cases with poor prognosis as an independent risk factor (relapse-free survival, hazard ratio = 2.37, 95% confidence interval, 1.27-4.42, P = 0.007 [univariate analysis]; hazard ratio = 2.70, 95% confidence interval, 1.42-5.13, P = 0.002 [multivariate analysis]). To investigate whether the altered GANP expression is associated with mammary tumorigenesis, we created mutant mice that were conditionally deficient in the ganp/MCM3AP gene using wap-cre recombinase transgenic mice. Mammary gland tumors occurred at a very high incidence in female mammary gland-specific GANP-deficient mice after severe impairment of mammary gland development during pregnancy. Moreover, tumor development also occurred in female post parous GANP-heterodeficient mice. GANP has a significant role in the suppression of DNA damage caused by estrogen in human breast cancer cell lines. These results indicated that the GANP protein is associated with breast cancer resistance.
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Affiliation(s)
- Kazuhiko Kuwahara
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan.,Division of Immunology, Aichi Cancer Center Research Institute, Nagoya, Japan
| | - Mutsuko Yamamoto-Ibusuki
- Department of Breast and Endocrine Surgery, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Zhenhuan Zhang
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan.,Department of Breast and Endocrine Surgery, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Suchada Phimsen
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Naomi Gondo
- Division of Immunology, Aichi Cancer Center Research Institute, Nagoya, Japan
| | - Hiroko Yamashita
- Division of Breast and Endocrine Surgery, Hokkaido University Hospital, Sapporo, Japan
| | - Toru Takeo
- Division of Reproductive Engineering, Center for Animal Resources and Development, Kumamoto University, Kumamoto, Japan
| | - Naomi Nakagata
- Division of Reproductive Engineering, Center for Animal Resources and Development, Kumamoto University, Kumamoto, Japan
| | - Daisuke Yamashita
- Division of Oncological Pathology, Aichi Cancer Center Research Institute, Nagoya, Japan
| | - Yoshimi Fukushima
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Yutaka Yamamoto
- Division of Immunology, Aichi Cancer Center Research Institute, Nagoya, Japan
| | - Hiroji Iwata
- Department of Breast Oncology, Aichi Cancer Center Hospital, Nagoya, Japan
| | - Hideyuki Saya
- Division of Gene Regulation, Institute for Advanced Medical Research, Graduate School of Medicine, Keio University, Tokyo, Japan
| | - Eisaku Kondo
- Division of Oncological Pathology, Aichi Cancer Center Research Institute, Nagoya, Japan.,Department of Cellular and Molecular Pathology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Keitaro Matsuo
- Division of Molecular Medicine, Aichi Cancer Center Research Institute, Nagoya, Japan
| | - Motohiro Takeya
- Department of Cell Pathology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Hirotaka Iwase
- Department of Breast and Endocrine Surgery, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Nobuo Sakaguchi
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan.,Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.,WPI Immunology Frontier Research Center, Osaka University, Osaka, Japan
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12
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Kitabatake M, Soma M, Zhang T, Kuwahara K, Fukushima Y, Nojima T, Kitamura D, Sakaguchi N. JNK regulatory molecule G5PR induces IgG autoantibody-producing plasmablasts from peritoneal B1a cells. THE JOURNAL OF IMMUNOLOGY 2015; 194:1480-8. [PMID: 25601926 DOI: 10.4049/jimmunol.1401127] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Peritoneal B1a cells expressing CD5 and CD11b generate autoantibody-producing precursors in autoimmune-prone mice. Previous studies show reduced JNK signaling in peritoneal B1a cells of female New Zealand Black mice and an abnormal increase of protein phosphatase 2A subunit G5PR that regulates BCR-mediated JNK signaling as a cause of autoimmunity. To investigate the mechanism regulating B1a differentiation into autoantibody-secreting plasmablasts (PBs), we applied an in vitro culture system that supports long-term growth of germinal center (GC) B cells (iGB) with IL-4, CD40L, and BAFF. Compared with spleen B2 cells, B1a cells differentiated into GC-like B cells, but more markedly into PBs, and underwent class switching toward IgG1. During iGB culture, B1a cells expressed GC-associated aicda, g5pr, and bcl6, and markedly PB-associated prdm1, irf4, and xbp1. B1a-derived iGB cells from New Zealand Black × New Zealand White F1 mice highly differentiated into autoantibody-secreting PBs in vitro and localized to the GC area in vivo. In iGB culture, JNK inhibitor SP600125 augmented the differentiation of C57BL/6 B1a cells into PBs. Furthermore, B1a cells from G5PR transgenic mice markedly differentiated into IgM and IgG autoantibody-secreting PBs. In conclusion, JNK regulation is critical to suppress autoantibody-secreting PBs from peritoneal B1a cells.
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Affiliation(s)
- Masahiro Kitabatake
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan
| | - Miho Soma
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan
| | - Tianli Zhang
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan
| | - Kazuhiko Kuwahara
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan
| | - Yoshimi Fukushima
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan
| | - Takuya Nojima
- Division of Molecular Biology, Research Institute for Biomedical Sciences, Tokyo University of Science, Chiba 278-0022, Japan; and
| | - Daisuke Kitamura
- Division of Molecular Biology, Research Institute for Biomedical Sciences, Tokyo University of Science, Chiba 278-0022, Japan; and
| | - Nobuo Sakaguchi
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan;
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13
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Randall KL. Generating humoral immune memory following infection or vaccination. Expert Rev Vaccines 2014; 9:1083-93. [DOI: 10.1586/erv.10.103] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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14
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Matthews AJ, Zheng S, DiMenna LJ, Chaudhuri J. Regulation of immunoglobulin class-switch recombination: choreography of noncoding transcription, targeted DNA deamination, and long-range DNA repair. Adv Immunol 2014; 122:1-57. [PMID: 24507154 PMCID: PMC4150736 DOI: 10.1016/b978-0-12-800267-4.00001-8] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Upon encountering antigens, mature IgM-positive B lymphocytes undergo class-switch recombination (CSR) wherein exons encoding the default Cμ constant coding gene segment of the immunoglobulin (Ig) heavy-chain (Igh) locus are excised and replaced with a new constant gene segment (referred to as "Ch genes", e.g., Cγ, Cɛ, or Cα). The B cell thereby changes from expressing IgM to one producing IgG, IgE, or IgA, with each antibody isotype having a different effector function during an immune reaction. CSR is a DNA deletional-recombination reaction that proceeds through the generation of DNA double-strand breaks (DSBs) in repetitive switch (S) sequences preceding each Ch gene and is completed by end-joining between donor Sμ and acceptor S regions. CSR is a multistep reaction requiring transcription through S regions, the DNA cytidine deaminase AID, and the participation of several general DNA repair pathways including base excision repair, mismatch repair, and classical nonhomologous end-joining. In this review, we discuss our current understanding of how transcription through S regions generates substrates for AID-mediated deamination and how AID participates not only in the initiation of CSR but also in the conversion of deaminated residues into DSBs. Additionally, we review the multiple processes that regulate AID expression and facilitate its recruitment specifically to the Ig loci, and how deregulation of AID specificity leads to oncogenic translocations. Finally, we summarize recent data on the potential role of AID in the maintenance of the pluripotent stem cell state during epigenetic reprogramming.
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Affiliation(s)
- Allysia J Matthews
- Immunology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, USA; Immunology and Microbial Pathogenesis Program, Weill Cornell Graduate School of Medical Sciences, New York, New York, USA
| | - Simin Zheng
- Immunology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, USA; Immunology and Microbial Pathogenesis Program, Weill Cornell Graduate School of Medical Sciences, New York, New York, USA
| | - Lauren J DiMenna
- Immunology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, USA; Immunology and Microbial Pathogenesis Program, Weill Cornell Graduate School of Medical Sciences, New York, New York, USA
| | - Jayanta Chaudhuri
- Immunology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, USA; Immunology and Microbial Pathogenesis Program, Weill Cornell Graduate School of Medical Sciences, New York, New York, USA.
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15
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GANP regulates recruitment of AID to immunoglobulin variable regions by modulating transcription and nucleosome occupancy. Nat Commun 2013; 4:1830. [PMID: 23652018 PMCID: PMC3674236 DOI: 10.1038/ncomms2823] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 03/28/2013] [Indexed: 11/14/2022] Open
Abstract
Somatic hypermutation in B cells is initiated by activation-induced cytidine deaminase-catalyzed C→U deamination at immunoglobulin variable regions. Here we investigate the role of the germinal centre-associated nuclear protein (GANP) in enhancing the access of activation-induced cytidine deaminase (AID) to immunoglobulin variable regions. We show that the nuclear export factor GANP is involved in chromatin modification at rearranged immunoglobulin variable loci, and its activity requires a histone acetyltransferase domain. GANP interacts with the transcription stalling protein Spt5 and facilitates RNA Pol-II recruitment to immunoglobulin variable regions. Germinal centre B cells from ganp-transgenic mice showed a higher AID occupancy at the immunoglobulin variable region, whereas B cells from conditional ganp-knockout mice exhibit a lower AID accessibility. These findings suggest that GANP-mediated chromatin modification promotes transcription complex recruitment and positioning at immunoglobulin variable loci to favour AID targeting. The affinity of antibodies for their targets is enhanced by somatic hypermutation, in which the cytidine deaminase AID is recruited to immunoglobulin variable region genes in B cells. Here the authors show that the nuclear protein GANP has an important role in this process by modifying chromatin structure and enhancing AID recruitment.
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16
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Cunningham CN, Schmidt CA, Schramm NJ, Gaylord MR, Resendes KK. Human TREX2 components PCID2 and centrin 2, but not ENY2, have distinct functions in protein export and co-localize to the centrosome. Exp Cell Res 2013; 320:209-18. [PMID: 24291146 DOI: 10.1016/j.yexcr.2013.11.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 11/15/2013] [Accepted: 11/19/2013] [Indexed: 11/15/2022]
Abstract
TREX-2 is a five protein complex, conserved from yeast to humans, involved in linking mRNA transcription and export. The centrin 2 subunit of TREX-2 is also a component of the centrosome and is additionally involved in a distinctly different process of nuclear protein export. While centrin 2 is a known multifunctional protein, the roles of other human TREX-2 complex proteins other than mRNA export are not known. In this study, we found that human TREX-2 member PCID2 but not ENY2 is involved in some of the same cellular processes as those of centrin 2 apart from the classical TREX-2 function. PCID2 is present at the centrosome in a subset of HeLa cells and this localization is centrin 2 dependent. Furthermore, the presence of PCID2 at the centrosome is prevalent throughout the cell cycle as determined by co-staining with cyclins E, A and B. PCID2 but not ENY2 is also involved in protein export. Surprisingly, siRNA knockdown of PCID2 delayed the rate of nuclear protein export, a mechanism distinct from the effects of centrin 2, which when knocked down inhibits export. Finally we showed that co-depletion of centrin 2 and PCID2 leads to blocking rather than delaying nuclear protein export, indicating the dominance of the centrin 2 phenotype. Together these results represent the first discovery of specific novel functions for PCID2 other than mRNA export and suggest that components of the TREX-2 complex serve alternative shared roles in the regulation of nuclear transport and cell cycle progression.
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Affiliation(s)
- Corey N Cunningham
- Westminster College, Department of Biology, 319 South Market Street, New Wilmington, PA 16172, USA
| | - Casey A Schmidt
- Westminster College, Department of Biology, 319 South Market Street, New Wilmington, PA 16172, USA
| | - Nathaniel J Schramm
- Westminster College, Department of Biology, 319 South Market Street, New Wilmington, PA 16172, USA
| | - Michelle R Gaylord
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California - San Diego, 9500 Gilman Drive, #0347, La Jolla, CA 92093-0347, USA
| | - Karen K Resendes
- Westminster College, Department of Biology, 319 South Market Street, New Wilmington, PA 16172, USA.
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17
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Erratum to: The role of activation-induced deaminase in antibody diversification and genomic instability. Immunol Res 2013. [DOI: 10.1007/s12026-013-8432-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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18
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Wang JH. The role of activation-induced deaminase in antibody diversification and genomic instability. Immunol Res 2013; 55:287-97. [PMID: 22956489 DOI: 10.1007/s12026-012-8369-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
More than a decade ago, activation-induced deaminase (AID) was identified as the initiator for somatic hypermutation (SHM) and class switch recombination (CSR). Since then, tremendous progress has been achieved toward elucidating how AID functions. AID targets the highly repetitive switch regions of the immunoglobulin heavy chain (IgH) locus to induce DNA double-strand breaks (DSBs), which can be rejoined, leading to switch of constant regions of antibody. When targeting to variable region exons of IgH and IgL loci, AID predominantly induces point mutations, termed SHM, resulting in increased affinity of antibody for antigen. While SHM and CSR enhance antibody diversity, AID-initiated DSBs and mutations may predispose B cells to carcinogenesis. This review focuses on the mechanisms that provide the specificity of AID targeting to Ig loci and the role of AID in genomic instability.
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Affiliation(s)
- Jing H Wang
- Integrated Department of Immunology, University of Colorado School of Medicine and National Jewish Health, Denver, CO 80206, USA.
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19
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Phimsen S, Kuwahara K, Nakaya T, Ohta K, Suda T, Rezano A, Kitabatake M, Vaeteewoottacharn K, Okada S, Tone S, Sakaguchi N. Selective cell death of p53-insufficient cancer cells is induced by knockdown of the mRNA export molecule GANP. Apoptosis 2012; 17:679-90. [PMID: 22395445 DOI: 10.1007/s10495-012-0711-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Cancer cells often contain p53 abnormalities that impair cell-cycle checkpoint progression and cause resistance to various anti-cancer treatments. DNA damage occurs at actively transcribed genes during G1-phase in yeast cells that have a deficient mRNA export capacity. Here, we show that germinal center-associated nuclear protein (GANP), a homologue of yeast Sac3 that is involved in mRNA export, is indispensable for ensuring the stability of human genomic DNA and that GANP knockdown causes apoptosis and necrosis of p53-insufficient cancer cells. Ganp small interfering RNA (siGanp)-induced DNA damage, accompanied by a decrease in the number of cells in S-phase, caused late apoptosis and necrosis in p53-insufficient cancer cells through both caspase-dependent and -independent mechanisms. siGanp effectively induced DNA damage leading to cell death in p53-insufficient cancer cells in vitro and protect the growth of cancer cells transplanted into immunocompromized mice, suggesting that siGanp has potential as a selective treatment for p53-insufficient cancer cells.
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Affiliation(s)
- Suchada Phimsen
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Honjo, Japan
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20
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Kuwahara K, Nakaya T, Phimsen S, Toda T, Kitabatake M, Kaji T, Takemori T, Watanabe T, Sakaguchi N. Lyn Signaling To Upregulate GANP Is Critical for the Survival of High-Affinity B Cells in Germinal Centers of Lymphoid Organs. THE JOURNAL OF IMMUNOLOGY 2012; 189:3472-9. [DOI: 10.4049/jimmunol.1200649] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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21
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Vuong BQ, Chaudhuri J. Combinatorial mechanisms regulating AID-dependent DNA deamination: interacting proteins and post-translational modifications. Semin Immunol 2012; 24:264-72. [PMID: 22771392 DOI: 10.1016/j.smim.2012.05.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Accepted: 05/18/2012] [Indexed: 10/28/2022]
Abstract
Protective humoral immune responses result from immunoglobulin (Ig) diversification reactions that proceed through programmed DNA double-strand breaks and mutations in developing or mature B cells. While primary Ig diversity is dependent on V(D)J recombination and the RAG proteins, secondary diversification is achieved through class switch recombination (CSR) and somatic hypermutation (SHM), which require AID (activation induced deaminase). Because aberrant AID activity can result in mutations in non-Ig loci and DNA translocations between the Ig locus and non-Ig genes, the activity of AID must be stringently regulated. AID mRNA expression is regulated transcriptionally by cytokine stimulation and post-transcriptionally by miRNAs. AID activity is regulated by post-translational modifications, subcellular localization, and interaction with other proteins. All of these molecular mechanisms have evolved to specifically induce AID-dependent mutations and DNA double-strand breaks at the Ig loci to promote maximal Ig gene diversification while limiting the access of this mutator to non-Ig regions.
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Affiliation(s)
- Bao Q Vuong
- Immunology Program, Memorial Sloan-Kettering Cancer Center, Gerstner Sloan-Kettering Graduate School, 1275 York Avenue, New York, NY 10065, United States.
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22
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Wickramasinghe VO, Stewart M, Laskey RA. GANP enhances the efficiency of mRNA nuclear export in mammalian cells. Nucleus 2012; 1:393-6. [PMID: 21326821 DOI: 10.4161/nucl.1.5.12351] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Revised: 04/27/2010] [Accepted: 04/28/2010] [Indexed: 11/19/2022] Open
Abstract
Nuclear export of mRNPs is mediated by transport factors such as NXF1 that bind mRNPs and mediate their translocation through the central channel of nuclear pores (NPC) using transient interactions with FG-nucleoporins. A number of nuclear factors enhance the efficiency of this process by concentrating mRNPs at the nuclear face of the pores. Although this enhancement has been explored mainly with the yeast TREX-2 complex, recent work has indicated that mammalian cells employ GANP (Germinal-centre Associated Nuclear Protein) for efficient mRNP nuclear export and for efficient recruitment of NXF1-containing mRNPs to NPCs. GANP is constructed from several domains that show local homology to FG-nucleoporins, the yeast mRNA export factor Sac3p and the mammalian MCM3 acetyltransferase. Whereas yeast TREX-2 is located primarily at nuclear pores, some GANP is located in the nuclear interior in addition to that found at the pores. GANP depletion inhibits bulk mRNA export, resulting in retention of mRNPs and NXF1 in punctate foci within the nucleoplasm, consistent with GANP's being an integral component of the mammalian mRNA export machinery. Here, we discuss the model for GANP function presented in our recent paper and its implications for the mechanism of mRNA export in mammalian cells.
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23
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Sakaguchi N, Maeda K, Kuwahara K. Molecular mechanism of immunoglobulin V-region diversification regulated by transcription and RNA metabolism in antigen-driven B cells. Scand J Immunol 2011; 73:520-6. [PMID: 21388430 DOI: 10.1111/j.1365-3083.2011.02557.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The immune system produces specific antibodies (Ab) against any antigens (Ag) of exogenous and endogenous origins with a diverse repertoire of V-region specificities. The primary V-region repertoire is created by the rearrangement of immunoglobulin (Ig) V-region, D- and J-segments with the insertion of N- and P-sequences during early B cell differentiation. Recent studies revealed that secondary diversification of the IgV-region generated in the peripheral lymphoid organs plays a critical role in the generation of effective Ab production for protection from various pathogens. Naïve B cells that react with Ags initiate proliferation and differentiation in the follicular region and create the germinal centres (GCs), where activation-induced cytidine deaminase (AID)-dependent IgV-region somatic hypermutation (SHM) and class-switch recombination generate high-affinity and class-switched mature Ag-specific B cells. Our studies have discovered a 210-kDa nuclear protein, named GC-associated nuclear protein (GANP) that is up-regulated in GC B cells during the T cell-dependent (TD) immune responses. By studying mice with mutant forms of the ganp gene, we demonstrated that GANP is essential for the generation of high-affinity B cells against TD-Ag by affecting SHM at the IgV-regions. GANP is associated with AID in the cytoplasm and the GANP/AID complex is recruited to the nucleus, specifically, the chromatin, and targeted selectively to the IgV-region gene in B cells. GANP augments the access of AID towards IgV-regions in B cells. Here, we review the role of GANP in acquired immunity through the detailed analysis of the molecular mechanism generating SHM specifically at IgV-regions in B cells.
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Affiliation(s)
- N Sakaguchi
- Department of Immunology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan.
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24
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Bascove M, Guéguinou N, Schaerlinger B, Gauquelin‐Koch G, Frippiat J. Decrease in antibody somatic hypermutation frequency under extreme, extended spaceflight conditions. FASEB J 2011; 25:2947-55. [DOI: 10.1096/fj.11-185215] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Matthieu Bascove
- Faculty of Medicine, Development and ImmunogeneticsNancy‐UniversityVandœuvre‐lès‐NancyFrance
| | - Nathan Guéguinou
- Faculty of Medicine, Development and ImmunogeneticsNancy‐UniversityVandœuvre‐lès‐NancyFrance
| | - Bérénice Schaerlinger
- Faculty of Medicine, Development and ImmunogeneticsNancy‐UniversityVandœuvre‐lès‐NancyFrance
| | | | - Jean‐Pol Frippiat
- Faculty of Medicine, Development and ImmunogeneticsNancy‐UniversityVandœuvre‐lès‐NancyFrance
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25
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Wickramasinghe VO, McMurtrie PIA, Marr J, Amagase Y, Main S, Mills AD, Laskey RA, Takei Y. MCM3AP is transcribed from a promoter within an intron of the overlapping gene for GANP. J Mol Biol 2010; 406:355-61. [PMID: 21195085 PMCID: PMC3121959 DOI: 10.1016/j.jmb.2010.12.035] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Revised: 12/21/2010] [Accepted: 12/22/2010] [Indexed: 11/21/2022]
Abstract
MCM3 acetylase (MCM3AP) and germinal-centre associated nuclear protein (GANP) are transcribed from the same locus and are therefore confused in databases because the MCM3 acetylase DNA sequence is contained entirely within the much larger GANP sequence and the entire MCM3AP sequence is identical to the carboxy terminus of GANP. Thus, the MCM3AP and GANP genes are read in the same reading frame and MCM3AP is an N-terminally truncated region of GANP. However, we show here that MCM3AP and GANP are different proteins, occupying different locations in the cell and transcribed from different promoters. Intriguingly, a promoter for MCM3AP lies within an intron of GANP. This report is an interesting example in nature of two separate gene products from the same locus that perform two entirely different functions in the cell. Therefore, to avoid further confusion, they should now be referred to as separate but overlapping genes.
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26
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Nakaya T, Kuwahara K, Ohta K, Kitabatake M, Toda T, Takeda N, Tani T, Kondo E, Sakaguchi N. Critical Role of Pcid2 in B Cell Survival through the Regulation of MAD2 Expression. THE JOURNAL OF IMMUNOLOGY 2010; 185:5180-7. [DOI: 10.4049/jimmunol.1002026] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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27
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Maeda K, Singh SK, Eda K, Kitabatake M, Pham P, Goodman MF, Sakaguchi N. GANP-mediated recruitment of activation-induced cytidine deaminase to cell nuclei and to immunoglobulin variable region DNA. J Biol Chem 2010; 285:23945-53. [PMID: 20507984 DOI: 10.1074/jbc.m110.131441] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
AID (activation-induced cytidine deaminase) catalyzes transcription-dependent deamination of C --> U in immunoglobulin variable (IgV) regions to initiate somatic hypermutation (SHM) in germinal center B-cells. SHM is essential in generating high affinity antibodies. Here we show that when coexpressed with GANP (germinal center-associated nuclear protein) in COS-7 cells, AID is transported from the cytoplasm and concentrated in the nucleus. GANP forms a complex with AID in cotransfected cells in vivo and in vitro. We have isolated AID mutants that bind with reduced affinity to GANP compared with wild type AID. One of these mutants, AID (D143A) binds GANP with a 10-fold lower affinity compared with wild type AID yet retains substantial C-deamination activity in vitro. Mutant AID (D143A) remains localized predominantly in the cytoplasm when coexpressed with GANP. Exogenous expression of GANP in Ramos B-cells promotes binding of AID to IgV DNA and mRNA and increases SHM frequency. These data suggest that GANP may serve as an essential link required to transport AID to B-cell nuclei and to target AID to actively transcribed IgV regions.
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Affiliation(s)
- Kazuhiko Maeda
- Department of Immunology, Graduate School of Life Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan
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28
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Wickramasinghe VO, McMurtrie PIA, Mills AD, Takei Y, Penrhyn-Lowe S, Amagase Y, Main S, Marr J, Stewart M, Laskey RA. mRNA export from mammalian cell nuclei is dependent on GANP. Curr Biol 2009; 20:25-31. [PMID: 20005110 PMCID: PMC2869303 DOI: 10.1016/j.cub.2009.10.078] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2009] [Revised: 10/23/2009] [Accepted: 10/28/2009] [Indexed: 01/03/2023]
Abstract
Bulk nuclear export of messenger ribonucleoproteins (mRNPs) through nuclear pore complexes (NPCs) is mediated by NXF1. It binds mRNPs through adaptor proteins such as ALY and SR splicing factors and mediates translocation through the central NPC transport channel via transient interactions with FG nucleoporins. Here, we show that mammalian cells require GANP (germinal center-associated nuclear protein) for efficient mRNP nuclear export and for efficient recruitment of NXF1 to NPCs. Separate regions of GANP show local homology to FG nucleoporins, the yeast mRNA export factor Sac3p, and the mammalian MCM3 acetyltransferase. GANP interacts with both NXF1 and NPCs and partitions between NPCs and the nuclear interior. GANP depletion inhibits mRNA export, with retention of mRNPs and NXF1 in punctate foci within the nucleus. The GANP N-terminal region that contains FG motifs interacts with the NXF1 FG-binding domain. Overexpression of this GANP fragment leads to nuclear accumulation of both poly(A)(+)RNA and NXF1. Treatment with transcription inhibitors redistributes GANP from NPCs into foci throughout the nucleus. These results establish GANP as an integral component of the mammalian mRNA export machinery and suggest a model whereby GANP facilitates the transfer of NXF1-containing mRNPs to NPCs.
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29
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Tangye SG, Tarlinton DM. Memory B cells: Effectors of long-lived immune responses. Eur J Immunol 2009; 39:2065-75. [DOI: 10.1002/eji.200939531] [Citation(s) in RCA: 178] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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30
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Ohta K, Kuwahara K, Zhang Z, Makino K, Komohara Y, Nakamura H, Kuratsu JI, Sakaguchi N. Decreased expression of germinal center-associated nuclear protein is involved in chromosomal instability in malignant gliomas. Cancer Sci 2009; 100:2069-76. [PMID: 19686285 DOI: 10.1111/j.1349-7006.2009.01293.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Malignant glioma (MG) is highly proliferative and invasive, with the malignant characteristics associated with aneuploidy and chromosomal instability (CIN). Here, we found that the level of germinal center-associated nuclear protein (GANP), a mammalian homologue of yeast Sac3, was markedly decreased in MGs with a poor prognosis; and thus we explored the effect of its decrease on cell-cycle progression of MG cell lines. Glioblastomas showed a significantly lower level of ganp mRNA than anaplastic astrocytomas, as measured by real-time reverse transcription-PCR, in 101 cases of adult MG. MGs of ganp(Low) expression displayed more malignant characteristics, with loss of heterozygosity on chromosome 10, epidermal growth factor receptor gene amplification, and significantly poorer prognosis than the ganp(High) group. Human diploid fibroblasts depleted of ganp mRNA by the RNA interference (RNAi) method showed a decreased percentage of S-phase cells and a cellular-senescence phenotype. MG cell lines harboring abnormalities of various cell-cycle checkpoint molecules displayed slippage of mitotic checkpoints and an increased proportion of hyperploid cells after ganp RNAi-treatment. These results suggest that GANP protects cells from cellular senescence caused by DNA damage and that a significant decrease in GANP expression leads to malignancy by generating hyperploidy and CIN.
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Affiliation(s)
- Kazutaka Ohta
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
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Iglesias-Ussel MD, Zavadil J, Scharff MD. Molecular characterization of hybridoma subclones spontaneously switching at high frequencies in vitro. J Immunol Methods 2009; 350:71-8. [PMID: 19619554 DOI: 10.1016/j.jim.2009.07.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 06/24/2009] [Accepted: 07/02/2009] [Indexed: 12/22/2022]
Abstract
The hybridoma technology allows the production of large quantities of specific antibodies of a single isotype. Since different isotypes have special effector functions and are distributed distinctively throughout the body, it is often useful to have a library of switch variants from the original monoclonal antibody. We have shown previously that forced expression of activation induced cytidine deaminase (AID) in hybridomas increased their very low frequency of class switch recombination (CSR) in vitro only approximately 7-13 fold. Since we had previously identified rare hybridoma subclones that spontaneously switched at more than 100 times higher frequencies, we have now examined those higher switching variants to search for ways to further increase the frequency of isotype switching in vitro. AID was not responsible for the approximately 100 fold increase in CSR, so we used whole-genome gene expression profiling to provide a platform for studying candidate molecular pathways underlying spontaneous CSR in hybridomas.
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Igarashi H, Kuwahara K, Yoshida M, Xing Y, Maeda K, Nakajima K, Sakaguchi N. GANP suppresses the arginine methyltransferase PRMT5 regulating IL-4-mediated STAT6-signaling to IgE production in B cells. Mol Immunol 2009; 46:1031-41. [DOI: 10.1016/j.molimm.2008.08.272] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2008] [Revised: 08/10/2008] [Accepted: 08/14/2008] [Indexed: 01/03/2023]
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Yoshida M, Kuwahara K, Shimasaki T, Nakagata N, Matsuoka M, Sakaguchi N. GANP suppresses DNA recombination, measured by direct-repeat beta-galactosidase gene construct, but does not suppress the type of recombination applying to immunoglobulin genes in mammalian cells. Genes Cells 2007; 12:1205-13. [PMID: 17903179 DOI: 10.1111/j.1365-2443.2007.01119.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Immunoglobulin V-region somatic hypermutation and C-region class-switch recombination are initiated by activation-induced cytidine deaminase (AID) in B-cells. AID-induced DNA damage at the immunoglobulin S-region is known to be repaired by non-homologous end-joining, but repair mechanisms at the V-region remain to be elucidated. In Saccharomyces cerevisiae, DNA homologous recombination is regulated by the expression of Sac3, involved in actin assembly, cell cycle transition and mRNA metabolism. Here, we demonstrate that the Sac3-homologue GANP suppresses DNA recombination in a direct-repeat beta-galactosidase gene construct in mammalian cells. Homozygous ganp gene knockout is embryonic lethal in mice. Embryonic fibroblasts immortalized from hetero-deficient ganp(+/-) mice showed more DNA recombination than wild-type. In contrast, over-expression of GANP suppressed either spontaneous DNA recombination or that caused by the introduction of aid cDNA into NIH3T3 cells (susceptible to I-sceI restriction enzyme cleavage but not to RAG-mediated immunoglobulin gene recombination). GANP suppresses the DNA recombination not only on the extrachromosomal DNA construct but also on the integrated DNA. The Sac3-homology portion is necessary for the suppressive activity, but the truncated carboxyl terminal MCM3-binding/acetylating region adversely augmented DNA recombination, acting as a dominant negative form. Expression of full-length GANP is critical for suppression of DNA hyper-recombination in mammalian cells.
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Affiliation(s)
- Mikoto Yoshida
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan
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Besson V, Brault V, Duchon A, Togbe D, Bizot JC, Quesniaux VFJ, Ryffel B, Hérault Y. Modeling the monosomy for the telomeric part of human chromosome 21 reveals haploinsufficient genes modulating the inflammatory and airway responses. Hum Mol Genet 2007; 16:2040-52. [PMID: 17591625 DOI: 10.1093/hmg/ddm152] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Monosomy 21 is a rare human disease due to gene dosage errors disturbing a variety of physiological and morphological systems including brain, skeletal, immune and respiratory functions. Most of the human condition corresponds to partial or mosaic monosomy suggesting that Monosomy 21 may be lethal. In order to search for dosage-sensitive genes involved in the human pathology, we generated by chromosomal engineering a monosomic mouse for the Prmt2-Col6a1 interval corresponding to the most telomeric part of human chromosome 21. Haploinsufficiency of the 13 genes, located in the 0.5 Mb genetic interval and conserved in man and mouse, caused apparently no morphological defect as observed in patients. However, monosomic mice displayed an enhanced inflammatory response after local intranasal lipopolysaccharide administration with enhanced recruitment of neutrophils and secretion of cytokines such as tumor necrosis factor-alpha (TNF-alpha), IL-1beta, IL-12p70 and IFN-gamma in the lung as well increased TNF-alpha production after systemic administration. Further analysis demonstrates that monosomic macrophages were involved and that a few genes, Prmt2, Pcnt2, Mcm3ap and Lss located in the region were candidate for the inflammatory response. Altogether, these results demonstrate the existence of dosage-sensitive genes in the Prmt2-Col6a1 region that control the inflammation and the lung function. Furthermore, they point out that similar partial Monosomies 21 in human might have eluded the diagnosis due to the very specific defects observed in this murine model.
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Affiliation(s)
- Vanessa Besson
- Institut de Tansgenose, Molecular Immunology and Embryology, Université Orléans, Férollerie, Orléans, France
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Kageshita T, Kuwahara K, Oka M, Ma D, Ono T, Sakaguchi N. Increased expression of germinal center-associated nuclear protein (GANP) is associated with malignant transformation of melanocytes. J Dermatol Sci 2006; 42:55-63. [PMID: 16431081 DOI: 10.1016/j.jdermsci.2005.12.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2005] [Revised: 12/12/2005] [Accepted: 12/15/2005] [Indexed: 10/25/2022]
Abstract
BACKGROUND Germinal center-associated nuclear protein (GANP) is a newly cloned molecule that is up-regulated in the germinal center B cells. Although GANP functions in the regulation of DNA repair during replication and survival of B cells, little is known about its expression in melanocytic cells. OBJECTIVES To investigate whether GANP and phosphorylated-GANP (P-GANP) are expressed in cultured human melanocytes and melanoma cells and in benign and malignant melanocytic lesions. In addition, we aim to determine whether GANP and P-GANP are associated with malignant transformation of melanocytic lineage. METHODS GANP and P-GANP expression in cultured melanocytic cells was analyzed by immunostaining and in vitro kinase assay. GANP and P-GANP expression in melanocytic lesions was analyzed by immunohistochemistry. RESULTS GANP and P-GANP were up-regulated in cultured melanoma cells compared to melanocytes. GANP and P-GANP were restricted to nucleus of melanocytes but co-expressed in cytoplasm of melanoma cells. On the other hand, GANP and P-GANP were widely expressed at various levels in melanocytic nevi and melanoma lesions with nuclear and cytoplasmic staining pattern. Melanoma cells showed a stronger intensity of GANP and P-GANP than melanocytic nevus cells, however the staining intensity in primary melanoma lesions was not associated with any clinicopathological variables. Cytoplasmic GANP and P-GANP expression was associated with MCM3 and Ki67 expression. CONCLUSIONS These data suggest, for the first time, that GANP and P-GANP are up-regulated in cultured melanoma cells compared to melanocytes and also they are widely expressed in benign and malignant melanocytic tumor cells.
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Affiliation(s)
- Toshiro Kageshita
- Department of Dermatology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan
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Kawatani Y, Igarashi H, Matsui T, Kuwahara K, Fujimura S, Okamoto N, Takagi K, Sakaguchi N. Cutting Edge: Double-Stranded DNA Breaks in theIgVRegion Gene Were Detected at Lower Frequency in Affinity-Maturation Impeded GANP−/−Mice. THE JOURNAL OF IMMUNOLOGY 2005; 175:5615-8. [PMID: 16237049 DOI: 10.4049/jimmunol.175.9.5615] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Double-stranded DNA breaks (DSBs) at the IgV region (IgV) genes might be involved in somatic hypermutation and affinity-maturation of the B cell receptor in response to T cell-dependent Ag. By ligation-mediated PCR, we studied IgV DSBs that occurred in mature germinal center B cells in response to nitrophenyl-chicken gamma-globulin in a RAG1-independent, Ag-dependent, and IgV-selective manner. We quantified their levels in GANP-deficient B cells that have impaired generation of high-affinity Ab. GANP-/- B cells showed a decreased level of DSBs with blunt ends than control B cells and, on the contrary, the ganp gene transgenic (GANPTg) B cells showed an increased level. These results suggested that the level of IgV DSBs in germinal center B cells is associated with GANP expression, which is presumably required for B cell receptor affinity maturation.
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Affiliation(s)
- Yousuke Kawatani
- Department of Immunology, Graduate School of Medicine, Kumamoto University, Japan
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Fujimura S, Xing Y, Takeya M, Yamashita Y, Ohshima K, Kuwahara K, Sakaguchi N. Increased expression of germinal center-associated nuclear protein RNA-primase is associated with lymphomagenesis. Cancer Res 2005; 65:5925-34. [PMID: 15994971 DOI: 10.1158/0008-5472.can-04-3259] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Lymphomas arise containing abnormalities of various differentiation stage-specific molecules. In the study reported here, we have shown abnormal up-regulation of germinal center B cell-associated GANP in various human lymphomas including mantle cell, diffuse large B cell, and Hodgkin lymphoma, by immunohistochemical analysis. To study the role of GANP in lymphomagenesis, we generated mutant mice (ganp-Tg) that express the transgenic ganp gene under immunoglobulin enhancer and promoter control. Ganp-Tg mice showed a high incidence of lymphomagenesis (29.5%) after aging with a non-B/non-T cell surface phenotype having slight CD45R/B220 expression and Ig transcripts of rearranged VH-DH-JH IgH loci. Lymphomas generated in ganp-Tg mice displayed similar pathologic characteristics to mouse reticulum cell neoplasm or Hodgkin lymphoma-like lesions. The VH sequences of individual mice showed that the tumors proliferated from a single clone or oligoclones, as is found in human diffuse large B-cell lymphomas and Hodgkin lymphoma. These results suggest that GANP overexpression is a causative factor in the generation of B lymphomas.
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Affiliation(s)
- Satoru Fujimura
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Honjo, Kumamoto, Japan
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Xing Y, Igarashi H, Wang X, Sakaguchi N. Protein phosphatase subunit G5PR is needed for inhibition of B cell receptor-induced apoptosis. ACTA ACUST UNITED AC 2005; 202:707-19. [PMID: 16129705 PMCID: PMC2212881 DOI: 10.1084/jem.20050637] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
B cell receptor (BCR) cross-linking induces B cell proliferation and sustains survival through the phosphorylation-dependent signals. We report that a loss of the protein phosphatase component G5PR increased the activation-induced cell death (AICD) and thus impaired B cell survival. G5PR associates with GANP, whose expression is up-regulated in mature B cells of the peripheral lymphoid organs. To study G5PR function, the G5pr gene was conditionally targeted with the CD19-Cre combination (G5pr−/− mice). The G5pr−/− mice had a decreased number of splenic B cells (60% of the controls). G5pr−/− B cells showed a normal proliferative response to lipopolysaccharide or anti-CD40 antibody stimulation but not to BCR cross-linking with or without IL-4 in vitro. G5pr−/− B cells did not show abnormalities in the BCR-mediated activation of Erks and NF-κB, cyclin D2 induction, or Akt activation. However, G5pr−/− B cells were sensitive to AICD caused by BCR cross-linking. This was associated with an increased depolarization of the mitochondrial membrane and the enhanced activation of c-Jun NH2-terminal protein kinase and Bim. These results suggest that G5PR is required for the BCR-mediated proliferation associated with the prevention of AICD in mature B cells.
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Affiliation(s)
- Yan Xing
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Japan
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Sakaguchi N, Kimura T, Matsushita S, Fujimura S, Shibata J, Araki M, Sakamoto T, Minoda C, Kuwahara K. Generation of high-affinity antibody against T cell-dependent antigen in the Ganp gene-transgenic mouse. THE JOURNAL OF IMMUNOLOGY 2005; 174:4485-94. [PMID: 15814669 DOI: 10.4049/jimmunol.174.8.4485] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Generation of high-affinity Ab is impaired in mice lacking germinal center-associated DNA primase (GANP) in B cells. In this study, we examined the effect of its overexpression in ganp transgenic C57BL/6 mice (Ganp(Tg)). Ganp(Tg) displayed normal phenotype in B cell development, serum Ig levels, and responses against T cell-independent Ag; however, it generated the Ab with much higher affinity against nitrophenyl-chicken gammaglobulin in comparison with C57BL/6. To further examine the affinity increase, we established hybridomas producing high-affinity mAbs and compared their affinities using BIAcore. C57BL/6 generated high-affinity anti-nitrophenyl mAbs (K(D) approximately 2.50 x 10(-7) M) of IgG1/lambda1 and contained the V(H)186.2 region with W33L mutation. Ganp(Tg) generated much higher affinity (K(D) > 1.57 x 10(-9) M) by usage of V(H)186.2 as well as noncanonical V(H)7183 regions. Ganp(Tg) also generated exceptionally high-affinity anti-HIV-1 (V3 peptide) mAbs (K(D) > 9.90 x 10(-11) M) with neutralizing activity. These results demonstrated that GANP is involved in V region alteration generating high-affinity Ab.
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Affiliation(s)
- Nobuo Sakaguchi
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Honjo, Kumamoto, Japan.
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