1
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Bello A, Hirth G, Voigt S, Tepper S, Jungnickel B. Mechanism and regulation of secondary immunoglobulin diversification. Cell Cycle 2023; 22:2070-2087. [PMID: 37909747 PMCID: PMC10761156 DOI: 10.1080/15384101.2023.2275397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 10/20/2023] [Indexed: 11/03/2023] Open
Abstract
Secondary immunoglobulin diversification by somatic hypermutation and class switch recombination in B cells is instrumental for an adequate adaptive humoral immune response. These genetic events may, however, also introduce aberrations into other cellular genes and thereby cause B cell malignancies. While the basic mechanism of somatic hypermutation and class switch recombination is now well understood, their regulation and in particular the mechanism of their specific targeting to immunoglobulin genes is still rather mysterious. In this review, we summarize the current knowledge on the mechanism and regulation of secondary immunoglobulin diversification and discuss known mechanisms of physiological targeting to immunoglobulin genes and mistargeting to other cellular genes. We summarize open questions in the field and provide an outlook on future research.
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Affiliation(s)
- Amanda Bello
- Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
| | - Gianna Hirth
- Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
| | - Stefanie Voigt
- Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
| | - Sandra Tepper
- Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
| | - Berit Jungnickel
- Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University, Jena, Germany
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2
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Dreval K, Hilton LK, Cruz M, Shaalan H, Ben-Neriah S, Boyle M, Collinge B, Coyle KM, Duns G, Farinha P, Grande BM, Meissner B, Pararajalingam P, Rushton CK, Slack GW, Wong J, Mungall AJ, Marra MA, Connors JM, Steidl C, Scott DW, Morin RD. Genetic subdivisions of follicular lymphoma defined by distinct coding and noncoding mutation patterns. Blood 2023; 142:561-573. [PMID: 37084389 PMCID: PMC10644066 DOI: 10.1182/blood.2022018719] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 04/06/2023] [Accepted: 04/06/2023] [Indexed: 04/23/2023] Open
Abstract
Follicular lymphoma (FL) accounts for ∼20% of all new lymphoma cases. Increases in cytological grade are a feature of the clinical progression of this malignancy, and eventual histologic transformation (HT) to the aggressive diffuse large B-cell lymphoma (DLBCL) occurs in up to 15% of patients. Clinical or genetic features to predict the risk and timing of HT have not been described comprehensively. In this study, we analyzed whole-genome sequencing data from 423 patients to compare the protein coding and noncoding mutation landscapes of untransformed FL, transformed FL, and de novo DLBCL. This revealed 2 genetically distinct subgroups of FL, which we have named DLBCL-like (dFL) and constrained FL (cFL). Each subgroup has distinguishing mutational patterns, aberrant somatic hypermutation rates, and biological and clinical characteristics. We implemented a machine learning-derived classification approach to stratify patients with FL into cFL and dFL subgroups based on their genomic features. Using separate validation cohorts, we demonstrate that cFL status, whether assigned with this full classifier or a single-gene approximation, is associated with a reduced rate of HT. This implies distinct biological features of cFL that constrain its evolution, and we highlight the potential for this classification to predict HT from genetic features present at diagnosis.
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Affiliation(s)
- Kostiantyn Dreval
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer, Vancouver, BC, Canada
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
| | - Laura K. Hilton
- Centre for Lymphoid Cancer, BC Cancer, Vancouver, BC, Canada
| | - Manuela Cruz
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
| | - Haya Shaalan
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
| | | | - Merrill Boyle
- Centre for Lymphoid Cancer, BC Cancer, Vancouver, BC, Canada
| | - Brett Collinge
- Centre for Lymphoid Cancer, BC Cancer, Vancouver, BC, Canada
| | - Krysta M. Coyle
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
| | - Gerben Duns
- Centre for Lymphoid Cancer, BC Cancer, Vancouver, BC, Canada
| | - Pedro Farinha
- Centre for Lymphoid Cancer, BC Cancer, Vancouver, BC, Canada
| | | | | | - Prasath Pararajalingam
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
| | - Christopher K. Rushton
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
| | - Graham W. Slack
- Centre for Lymphoid Cancer, BC Cancer, Vancouver, BC, Canada
| | - Jasper Wong
- Centre for Lymphoid Cancer, BC Cancer, Vancouver, BC, Canada
| | - Andrew J. Mungall
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer, Vancouver, BC, Canada
| | - Marco A. Marra
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer, Vancouver, BC, Canada
| | | | | | - David W. Scott
- Centre for Lymphoid Cancer, BC Cancer, Vancouver, BC, Canada
| | - Ryan D. Morin
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer, Vancouver, BC, Canada
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
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3
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Arulraj T, Binder SC, Meyer-Hermann M. Investigating the Mechanism of Germinal Center Shutdown. Front Immunol 2022; 13:922318. [PMID: 35911680 PMCID: PMC9329532 DOI: 10.3389/fimmu.2022.922318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Accepted: 06/20/2022] [Indexed: 11/13/2022] Open
Abstract
Germinal centers (GCs) are transient structures where affinity maturation of B cells gives rise to high affinity plasma and memory cells. The mechanism of GC shutdown is unclear, despite being an important phenomenon maintaining immune homeostasis. In this study, we used a mathematical model to identify mechanisms that can independently promote contraction of GCs leading to shutdown. We show that GC shutdown can be promoted by antigen consumption by B cells, antigen masking by soluble antibodies, alterations in follicular dendritic cell (FDC) network area, modulation of immune complex cycling rate constants, alterations in T follicular helper signaling, increased terminal differentiation and reduced B cell division capacity. Proposed mechanisms promoted GC contraction by ultimately decreasing the number of B cell divisions and recycling cells. Based on the in-silico predictions, we suggest a combination of experiments that can be potentially employed by future studies to unravel the mechanistic basis of GC shutdown such as measurements of the density of pMHC presentation of B cells, FDC network size per B cell, fraction of cells expressing differentiation markers. We also show that the identified mechanisms differentially affect the efficiency of GC reaction estimated based on the quantity and quality of resulting antibodies.
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Affiliation(s)
- Theinmozhi Arulraj
- Department of Systems Immunology, Braunschweig Integrated Centre of Systems Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Sebastian C. Binder
- Department of Systems Immunology, Braunschweig Integrated Centre of Systems Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Michael Meyer-Hermann
- Department of Systems Immunology, Braunschweig Integrated Centre of Systems Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Institute for Biochemistry, Biotechnology and Bioinformatics, Technische Universität Braunschweig, Braunschweig, Germany
- *Correspondence: Michael Meyer-Hermann,
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4
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Böttcher K, Braunschmidt K, Hirth G, Schärich K, Klassert TE, Stock M, Sorgatz J, Fischer-Burkart S, Ullrich S, Frankenberger S, Kritsch D, Kosan C, Küppers R, Strobl LJ, Slevogt H, Zimber-Strobl U, Jungnickel B. Context-dependent regulation of immunoglobulin mutagenesis by p53. Mol Immunol 2021; 138:128-136. [PMID: 34392111 DOI: 10.1016/j.molimm.2021.08.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 07/22/2021] [Accepted: 08/04/2021] [Indexed: 10/20/2022]
Abstract
p53 plays a major role in genome maintenance. In addition to multiple p53 functions in the control of DNA repair, a regulation of DNA damage bypass via translesion synthesis has been implied in vitro. Somatic hypermutation of immunoglobulin genes for affinity maturation of antibody responses is based on aberrant translesion polymerase action and must be subject to stringent control to prevent genetic alterations and lymphomagenesis. When studying the role of p53 in somatic hypermutation in vivo, we found altered translesion polymerase-mediated A:T mutagenesis in mice lacking p53 in all organs, but notably not in mice with B cell-specific p53 inactivation, implying that p53 functions in non-B cells may alter mutagenesis in B cells. During class switch recombination, when p53 prevents formation of chromosomal translocations, we in addition detected a B cell-intrinsic role for p53 in altering G:C and A:T mutagenesis. Thus, p53 regulates translesion polymerase activity and shows differential activity during somatic hypermutation versus class switch recombination in vivo. Finally, p53 inhibition leads to increased somatic hypermutation in human B lymphoma cells. We conclude that loss of p53 function may promote genetic instability via multiple routes during antibody diversification in vivo.
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Affiliation(s)
- Katrin Böttcher
- Department of Cell Biology, Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University Jena, Jena, Germany.
| | - Kerstin Braunschmidt
- Department of Cell Biology, Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University Jena, Jena, Germany; Institute of Clinical Molecular Biology, Helmholtz Center Munich, German Research Center for Environmental Health, Munich, Germany.
| | - Gianna Hirth
- Department of Cell Biology, Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University Jena, Jena, Germany.
| | - Karsten Schärich
- Department of Cell Biology, Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University Jena, Jena, Germany.
| | - Tilman E Klassert
- Host Septomics, ZIK Septomics, Jena University Hospital, Jena, Germany.
| | - Magdalena Stock
- Host Septomics, ZIK Septomics, Jena University Hospital, Jena, Germany.
| | - Janine Sorgatz
- Department of Cell Biology, Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University Jena, Jena, Germany.
| | - Sabine Fischer-Burkart
- Institute of Clinical Molecular Biology, Helmholtz Center Munich, German Research Center for Environmental Health, Munich, Germany.
| | - Steffen Ullrich
- Department of Cell Biology, Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University Jena, Jena, Germany.
| | - Samantha Frankenberger
- Institute of Clinical Molecular Biology, Helmholtz Center Munich, German Research Center for Environmental Health, Munich, Germany
| | - Daniel Kritsch
- Department of Cell Biology, Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University Jena, Jena, Germany; Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University Jena, Jena, Germany.
| | - Christian Kosan
- Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University Jena, Jena, Germany.
| | - Ralf Küppers
- Institute of Cell Biology (Cancer Research), University of Duisburg-Essen, Medical School, Essen, Germany.
| | - Lothar J Strobl
- Department of Gene Vectors, Helmholtz Center Munich, German Research Center for Environmental Health, Munich, Germany.
| | - Hortense Slevogt
- Host Septomics, ZIK Septomics, Jena University Hospital, Jena, Germany.
| | - Ursula Zimber-Strobl
- Department of Gene Vectors, Helmholtz Center Munich, German Research Center for Environmental Health, Munich, Germany.
| | - Berit Jungnickel
- Department of Cell Biology, Institute of Biochemistry and Biophysics, Faculty of Biological Sciences, Friedrich Schiller University Jena, Jena, Germany; Institute of Clinical Molecular Biology, Helmholtz Center Munich, German Research Center for Environmental Health, Munich, Germany.
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5
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Arulraj T, Binder SC, Robert PA, Meyer-Hermann M. Germinal Centre Shutdown. Front Immunol 2021; 12:705240. [PMID: 34305944 PMCID: PMC8293096 DOI: 10.3389/fimmu.2021.705240] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 06/24/2021] [Indexed: 12/24/2022] Open
Abstract
Germinal Centres (GCs) are transient structures in secondary lymphoid organs, where affinity maturation of B cells takes place following an infection. While GCs are responsible for protective antibody responses, dysregulated GC reactions are associated with autoimmune disease and B cell lymphoma. Typically, ‘normal’ GCs persist for a limited period of time and eventually undergo shutdown. In this review, we focus on an important but unanswered question – what causes the natural termination of the GC reaction? In murine experiments, lack of antigen, absence or constitutive T cell help leads to premature termination of the GC reaction. Consequently, our present understanding is limited to the idea that GCs are terminated due to a decrease in antigen access or changes in the nature of T cell help. However, there is no direct evidence on which biological signals are primarily responsible for natural termination of GCs and a mechanistic understanding is clearly lacking. We discuss the present understanding of the GC shutdown, from factors impacting GC dynamics to changes in cellular interactions/dynamics during the GC lifetime. We also address potential missing links and remaining questions in GC biology, to facilitate further studies to promote a better understanding of GC shutdown in infection and immune dysregulation.
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Affiliation(s)
- Theinmozhi Arulraj
- Department of Systems Immunology, Braunschweig Integrated Centre of Systems Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Sebastian C Binder
- Department of Systems Immunology, Braunschweig Integrated Centre of Systems Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Philippe A Robert
- Department of Systems Immunology, Braunschweig Integrated Centre of Systems Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany.,Department of Immunology, University of Oslo, Oslo, Norway
| | - Michael Meyer-Hermann
- Department of Systems Immunology, Braunschweig Integrated Centre of Systems Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany.,Institute for Biochemistry, Biotechnology and Bioinformatics, Technische Universität Braunschweig, Braunschweig, Germany
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6
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Abstract
Antigen recognition by the B cell receptor (BCR) is a physiological trigger for reactivation of Epstein-Barr virus (EBV) and can be recapitulated in vitro by cross-linking of surface immunoglobulins. Previously, we identified a subset of EBV microRNAs (miRNAs) that attenuate BCR signal transduction and subsequently dampen lytic reactivation in B cells. The roles of host miRNAs in the EBV lytic cycle are not completely understood. Here, we profiled the small RNAs in reactivated Burkitt lymphoma cells and identified several miRNAs, such as miR-141, that are induced upon BCR cross-linking. Notably, EBV encodes a viral miRNA, miR-BART9, with sequence homology to miR-141. To better understand the functions of these two miRNAs, we examined their molecular targets and experimentally validated multiple candidates commonly regulated by both miRNAs. Targets included B cell transcription factors and known regulators of EBV immediate-early genes, leading us to hypothesize that these miRNAs modulate kinetics of the lytic cascade in B cells. Through functional assays, we identified roles for miR-141 and EBV miR-BART9 and one specific target, FOXO3, in progression of the lytic cycle. Our data support a model whereby EBV exploits BCR-responsive miR-141 and further mimics activity of this miRNA family via a viral miRNA to promote productive lytic replication. IMPORTANCE EBV is a human pathogen associated with several malignancies. A key aspect of lifelong virus persistence is the ability to switch between latent and lytic replication modes. The mechanisms governing latency, reactivation, and progression of the lytic cycle are only partly understood. This study reveals that specific miRNAs can act to support the EBV lytic phase following BCR-mediated reactivation triggers. Furthermore, this study identifies a role for FOXO3, commonly suppressed by both host and viral miRNAs, in modulating progression of the EBV lytic cycle.
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7
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Zhang J, Shi Y, Zhao M, Hu H, Huang H. Activation-induced cytidine deaminase overexpression in double-hit lymphoma: potential target for novel anticancer therapy. Sci Rep 2020; 10:14164. [PMID: 32843697 PMCID: PMC7447639 DOI: 10.1038/s41598-020-71058-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 07/29/2020] [Indexed: 12/12/2022] Open
Abstract
Activation-induced cytidine deaminase (AID) is one kind of the mutant enzymes, which target regulating the immunoglobulin (Ig) gene in Burkitt's lymphoma to initiate class switch recombination (CSR), resulting in c-Myc chromosomal translocation. However, it is not clear that whether AID induces c-Myc/IgH translocation in double-hit lymphoma (DHL) with c-Myc gene translocation. In this study, the AID in DHL tissues and classical diffuse large b-cell lymphoma (DLBCL) tissues were compared. The results suggested that AID is of important value in predicting DHL, stronger CSR of AID was observed in DHL patients, which exhibited AID overexpression and c-Myc gene translocation of DHL after CSR induction. It is concluded that AID directly induces CSR in DHL and may result in c-Myc gene translocation. Targeting AID may be a good treatment regimen for DHL.
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MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Cytidine Deaminase/biosynthesis
- Cytidine Deaminase/genetics
- Cytidine Deaminase/physiology
- Enzyme Induction/drug effects
- Female
- Gene Expression Regulation, Neoplastic/drug effects
- Genes, bcl-2
- Genes, myc
- Humans
- Immunoglobulin Class Switching/genetics
- Immunoglobulin Isotypes/biosynthesis
- Immunoglobulin Isotypes/blood
- Immunoglobulin Isotypes/genetics
- Kaplan-Meier Estimate
- Ki-67 Antigen/genetics
- Lipopolysaccharides/pharmacology
- Lymphoma, Large B-Cell, Diffuse/drug therapy
- Lymphoma, Large B-Cell, Diffuse/enzymology
- Lymphoma, Large B-Cell, Diffuse/genetics
- Lymphoma, Large B-Cell, Diffuse/mortality
- Male
- Middle Aged
- Molecular Targeted Therapy
- Neoplasm Proteins/biosynthesis
- Neoplasm Proteins/genetics
- Neoplasm Proteins/physiology
- Prognosis
- Proto-Oncogene Proteins c-bcl-6/genetics
- Translocation, Genetic
- Up-Regulation/drug effects
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Affiliation(s)
- Jingcheng Zhang
- Bone Marrow Transplantation Center, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310003, Zhejian, People's Republic of China
- Department of Hematology, Jinhua Hospital of Zhejiang University (Jinhua Municipal Central Hospital), Jinhua, 321100, Zhejiang, People's Republic of China
| | - Yifen Shi
- Department of Hematology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325000, People's Republic of China
| | - Mingzhe Zhao
- Department of Hematology, Jinhua Hospital of Zhejiang University (Jinhua Municipal Central Hospital), Jinhua, 321100, Zhejiang, People's Republic of China
| | - Huixian Hu
- Department of Hematology, Jinhua Hospital of Zhejiang University (Jinhua Municipal Central Hospital), Jinhua, 321100, Zhejiang, People's Republic of China.
| | - He Huang
- Bone Marrow Transplantation Center, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310003, Zhejian, People's Republic of China.
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8
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Tepper S, Mortusewicz O, Członka E, Bello A, Schmidt A, Jeschke J, Fischbach A, Pfeil I, Petersen-Mahrt SK, Mangerich A, Helleday T, Leonhardt H, Jungnickel B. Restriction of AID activity and somatic hypermutation by PARP-1. Nucleic Acids Res 2019; 47:7418-7429. [PMID: 31127309 PMCID: PMC6698665 DOI: 10.1093/nar/gkz466] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 05/13/2019] [Accepted: 05/16/2019] [Indexed: 12/20/2022] Open
Abstract
Affinity maturation of the humoral immune response depends on somatic hypermutation (SHM) of immunoglobulin (Ig) genes, which is initiated by targeted lesion introduction by activation-induced deaminase (AID), followed by error-prone DNA repair. Stringent regulation of this process is essential to prevent genetic instability, but no negative feedback control has been identified to date. Here we show that poly(ADP-ribose) polymerase-1 (PARP-1) is a key factor restricting AID activity during somatic hypermutation. Poly(ADP-ribose) (PAR) chains formed at DNA breaks trigger AID-PAR association, thus preventing excessive DNA damage induction at sites of AID action. Accordingly, AID activity and somatic hypermutation at the Ig variable region is decreased by PARP-1 activity. In addition, PARP-1 regulates DNA lesion processing by affecting strand biased A:T mutagenesis. Our study establishes a novel function of the ancestral genome maintenance factor PARP-1 as a critical local feedback regulator of both AID activity and DNA repair during Ig gene diversification.
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Affiliation(s)
- Sandra Tepper
- Department of Cell Biology, Institute of Biochemistry and Biophysics, School of Biology and Pharmacy, Friedrich Schiller University, 07745 Jena, Germany
| | - Oliver Mortusewicz
- Department of Biology II and Center for Integrated Protein Science Munich (CIPSM), Ludwig Maximilians University Munich, 82152 Planegg-Martinsried, Germany.,Science for Life Laboratory, Department of Oncology-Pathology, Karolinska Institutet, S-171 76 Stockholm, Sweden
| | - Ewelina Członka
- Department of Cell Biology, Institute of Biochemistry and Biophysics, School of Biology and Pharmacy, Friedrich Schiller University, 07745 Jena, Germany
| | - Amanda Bello
- Department of Cell Biology, Institute of Biochemistry and Biophysics, School of Biology and Pharmacy, Friedrich Schiller University, 07745 Jena, Germany
| | - Angelika Schmidt
- Department of Cell Biology, Institute of Biochemistry and Biophysics, School of Biology and Pharmacy, Friedrich Schiller University, 07745 Jena, Germany
| | - Julia Jeschke
- Department of Cell Biology, Institute of Biochemistry and Biophysics, School of Biology and Pharmacy, Friedrich Schiller University, 07745 Jena, Germany
| | - Arthur Fischbach
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Ines Pfeil
- Institute of Clinical Molecular Biology, Helmholtz Center Munich, German Research Center for Environmental Health, 81377 Munich, Germany
| | - Svend K Petersen-Mahrt
- DNA Editing in Immunity and Epigenetics, IFOM-Fondazione Instituto FIRC di Oncologia Molecolare, Milano, Italy
| | - Aswin Mangerich
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Thomas Helleday
- Science for Life Laboratory, Department of Oncology-Pathology, Karolinska Institutet, S-171 76 Stockholm, Sweden
| | - Heinrich Leonhardt
- Department of Biology II and Center for Integrated Protein Science Munich (CIPSM), Ludwig Maximilians University Munich, 82152 Planegg-Martinsried, Germany
| | - Berit Jungnickel
- Department of Cell Biology, Institute of Biochemistry and Biophysics, School of Biology and Pharmacy, Friedrich Schiller University, 07745 Jena, Germany.,Department of Biology, University of Konstanz, 78457 Konstanz, Germany
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9
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Li L, Zheng YL, Jiang C, Fang S, Zeng TT, Zhu YH, Li Y, Xie D, Guan XY. HN1L-mediated transcriptional axis AP-2γ/METTL13/TCF3-ZEB1 drives tumor growth and metastasis in hepatocellular carcinoma. Cell Death Differ 2019; 26:2268-2283. [PMID: 30778199 DOI: 10.1038/s41418-019-0301-1] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 01/25/2019] [Indexed: 12/13/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is one of the most aggressive malignancies and lacks targeted therapies. Here, we reported a novel potential therapeutic target hematological and neurological expressed 1 like (HN1L) in HCC. First, HCC tissue microarray analysis showed that HN1L was frequently up-regulated in cancer tissues than that in normal liver tissues, which significantly associated with tumor size, local invasion, distant metastases, and poor prognosis for HCC patients. Functional studies demonstrated that ectopic expression of HN1L could increase cell growth, foci formation in monolayer culture, colony formation in soft agar and tumorigenesis in nude mice. In addition, HN1L could also promote HCC metastasis by inducing epithelial-mesenchymal transition. Inversely, silencing HN1L expression with shRNA could effectively attenuate its oncogenic function. We further showed that HN1L transcriptionally up-regulated methyltransferase like 13 (METTL13) gene in an AP-2γ dependent manner, which promoted cell proliferation and metastasis by up-regulating TCF3 and ZEB1. Importantly, administration of lentivirus-mediated shRNA interfering HN1L expression could inhibit tumorigenesis and metastasis in mice. Collectively, HN1L-mediated transcriptional axis AP-2γ/METTL13/TCF3-ZEB1 promotes HCC growth and metastasis representing a promising therapeutic target in HCC treatment.
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Affiliation(s)
- Lei Li
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 510060, Guangzhou, China
| | - Yin-Li Zheng
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 510060, Guangzhou, China
| | - Chen Jiang
- Department of Pathology, Sun Yat-sen University Cancer Center, 510060, Guangzhou, China
| | - Shuo Fang
- Department of Clinical Oncology, The University of Hong Kong, 852, Hong Kong, China
| | - Ting-Ting Zeng
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 510060, Guangzhou, China
| | - Ying-Hui Zhu
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 510060, Guangzhou, China
| | - Yan Li
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 510060, Guangzhou, China
| | - Dan Xie
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 510060, Guangzhou, China
| | - Xin-Yuan Guan
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, 510060, Guangzhou, China. .,Department of Clinical Oncology, The University of Hong Kong, 852, Hong Kong, China.
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10
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Shannon-Lowe C, Rickinson AB, Bell AI. Epstein-Barr virus-associated lymphomas. Philos Trans R Soc Lond B Biol Sci 2017; 372:20160271. [PMID: 28893938 PMCID: PMC5597738 DOI: 10.1098/rstb.2016.0271] [Citation(s) in RCA: 247] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/09/2017] [Indexed: 02/06/2023] Open
Abstract
Epstein-Barr virus (EBV), originally discovered through its association with Burkitt lymphoma, is now aetiologically linked to a remarkably wide range of lymphoproliferative lesions and malignant lymphomas of B-, T- and NK-cell origin. Some occur as rare accidents of virus persistence in the B lymphoid system, while others arise as a result of viral entry into unnatural target cells. The early finding that EBV is a potent B-cell growth transforming agent hinted at a simple oncogenic mechanism by which this virus could promote lymphomagenesis. In reality, the pathogenesis of EBV-associated lymphomas involves a complex interplay between different patterns of viral gene expression and cellular genetic changes. Here we review recent developments in our understanding of EBV-associated lymphomagenesis in both the immunocompetent and immunocompromised host.This article is part of the themed issue 'Human oncogenic viruses'.
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Affiliation(s)
- Claire Shannon-Lowe
- Institute of Immunology and Immunotherapy, The Medical School, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Alan B Rickinson
- Institute of Immunology and Immunotherapy, The Medical School, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Andrew I Bell
- Institute for Cancer and Genomic Sciences, The Medical School, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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Burotto M, Berkovits A, Dunleavy K. Double hit lymphoma: from biology to therapeutic implications. Expert Rev Hematol 2016; 9:669-78. [PMID: 27166590 DOI: 10.1080/17474086.2016.1182858] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
INTRODUCTION Diffuse large B-cell lymphoma (DLBCL) is a molecularly heterogeneous disease defined by different cellular origins and mechanisms of oncogenic activation. Approximately 10% of DLBCL cases harbor a MYC rearrangement and this has been associated with a more aggressive clinical course following standard therapy. AREAS COVERED So-called 'double-hit lymphomas' (DHL) or 'triple hit lymphomas' (THL) occur when MYC is concurrently rearranged with BCL2 and/or BCL6. These tumors are characterized by high proliferation rate and a very poor outcome following standard R-CHOP (rituximab, cyclophosphamide, doxorubicin vincristine and prednisone) therapy, in most (though not all) studies that have looked at this. Though there is a paucity of published experience with other chemotherapy regimens, there is emerging evidence that more intensive approaches may improve outcome. Recently, there has been a lot of focus in the literature on 'double-expresser lymphomas' (DEL) with high MYC, BCL2 and/or BCL6 expression but typically without rearrangements of these genes. These DEL cases, have a poor outcome with R-CHOP and there is little consensus on how they should be approached. Expert commentary: This review will focus on the biology and treatment of DHL and DEL, discuss the outcome of these diseases with current standard as well as promising new approaches and conclude with a section on novel agents that are in development for these diseases.
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Affiliation(s)
- Mauricio Burotto
- a Hemato-Oncology Service, Clinica Alemana de Santiago , School of Medicine Universidad del Desarrollo , Santiago , Chile
| | - Alejandro Berkovits
- a Hemato-Oncology Service, Clinica Alemana de Santiago , School of Medicine Universidad del Desarrollo , Santiago , Chile
| | - Kieron Dunleavy
- b Lymphoid Malignancies Branch, Center for Cancer Research , National Cancer Institute , Bethesda , MD , USA
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Dai X, Wu Y, Jia X, Chang Y, Wu H, Wang C, Chen H, Chen W, Huang Q, Wei W. hIgD promotes human Burkitt lymphoma Daudi cell proliferation by accelerated G1/S transition via IgD receptor activity. Immunol Res 2016; 64:978-87. [DOI: 10.1007/s12026-015-8777-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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13
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Davari K, Frankenberger S, Schmidt A, Tomi NS, Jungnickel B. Checkpoint kinase 2 is required for efficient immunoglobulin diversification. Cell Cycle 2015; 13:3659-69. [PMID: 25483076 DOI: 10.4161/15384101.2014.964112] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Maintenance of genome integrity relies on multiple DNA repair pathways as well as on checkpoint regulation. Activation of the checkpoint kinases Chk1 and Chk2 by DNA damage triggers cell cycle arrest and improved DNA repair, or apoptosis in case of excessive damage. Chk1 and Chk2 have been reported to act in a complementary or redundant fashion, depending on the physiological context. During secondary immunoglobulin (Ig) diversification in B lymphocytes, DNA damage is abundantly introduced by activation-induced cytidine deaminase (AID) and processed to mutations in a locus-specific manner by several error-prone DNA repair pathways. We have previously shown that Chk1 negatively regulates Ig somatic hypermutation by promoting error-free homologous recombination and Ig gene conversion. We now report that Chk2 shows opposite effects to Chk1 in the regulation of these processes. Chk2 inactivation in B cells leads to decreased Ig hypermutation and Ig class switching, and increased Ig gene conversion activity. This is linked to defects in non-homologous end joining and increased Chk1 activation upon interference with Chk2 function. Intriguingly, in the context of physiological introduction of substantial DNA damage into the genome during Ig diversification, the 2 checkpoint kinases thus function in an opposing manner, rather than redundantly or cooperatively.
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Key Words
- AID, activation-induced cytidine deaminase
- APE1, apurinic endonuclease 1
- ATM, ataxia telangiectasia mutated
- ATR, ataxia telangiectasia and rad3 related
- Chk, checkpoint kinase
- DNA repair
- HR, homologous recombination
- Ig, immunoglobulin
- MMR mismatch repair
- MMS, methyl methansulfonate
- NHEJ, non-homologous end joining
- UNG, uracil N-glycosilase
- checkpoint signaling
- germinal center
- immunoglobulin diversification
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Affiliation(s)
- Kathrin Davari
- a Department of Cell Biology; Institute of Biochemistry and Biophysics; Center for Molecular Biomedicine ; Friedrich-Schiller University Jena ; Jena , Germany
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Jiang X, Guo H, Wu J, He Q, Li Y, Wang M, Pan H, Li W, Wang J, Wang Q, Shen J, Ke Y, Zhou R. Critical role of SHP2 (PTPN11) signaling in germinal center-derived lymphoma. Haematologica 2014; 99:1834-45. [PMID: 25193962 DOI: 10.3324/haematol.2014.106401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Germinal center lymphoma is a heterogeneous human lymphoma entity. Here we report that constitutive activity of SHP2 (PTPN11) and its downstream kinase ERK is essential for the viability of germinal center lymphoma cells and disease progression. Mechanistically, SHP2/ERK inhibition impedes c-Myc transcriptional activity, which results in the repression of proliferative phenotype signatures of germinal center lymphoma. Furthermore, SHP2/ERK signaling is required to maintain the CD19/c-Myc loop, which preferentially promotes survival of a distinct subtype of germinal center lymphoma cells carrying the MYC/IGH translocation. These findings demonstrate a critical function for SHP2/ERK signaling upstream of c-Myc in germinal center lymphoma cells and provide a rationale for targeting SHP2 in the therapy of germinal center lymphoma.
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Affiliation(s)
- Xin Jiang
- Department of Pathology and Pathophysiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Honggang Guo
- Department of Pathology and Pathophysiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Jianguo Wu
- Department of Pathology and Pathophysiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Qiang He
- Department of Nephrology, Zhejiang Province People's Hospital, Hangzhou, China
| | - Yiqiao Li
- Department of Nephrology, Zhejiang Province People's Hospital, Hangzhou, China
| | - Miao Wang
- Department of Pathology, Basic Medical College, Capital Medical University, Beijing, China
| | - Hongyang Pan
- Central Laboratory, Epitomics (Hangzhou) Biotech Co. Ltd, Hangzhou, Zhejiang, China
| | - Wande Li
- Department of Biochemistry, Boston University School of Medicine, MA, USA
| | - Jinjie Wang
- Department of Pathology and Pathophysiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Qingqing Wang
- Department of Immunology, Zhejiang University School of Medicine, Hangzhou, China
| | - Jing Shen
- Department of Pathology and Pathophysiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Yuehai Ke
- Department of Pathology and Pathophysiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Ren Zhou
- Department of Pathology and Pathophysiology, Zhejiang University School of Medicine, Hangzhou, China
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Huang X, Sun Q, Fu H, Zhou X, Guan X, Wang J. Both c-Myc and Ki-67 expression are predictive markers in patients with extranodal NK/T-cell lymphoma, nasal type: a retrospective study in China. Pathol Res Pract 2014; 210:351-6. [PMID: 24642368 DOI: 10.1016/j.prp.2014.02.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 01/23/2014] [Accepted: 02/10/2014] [Indexed: 01/24/2023]
Abstract
Extranodal natural killer (NK)/T-cell lymphoma, nasal type (ENKTL) is an increasingly recognized disease entity of aggressive tumor progression. The objective of this study was to investigate the clinical and prognostic significance of c-Myc and Ki-67 expression in ENKTL. Immunohistochemistry for c-Myc and Ki-67 was performed on tissue sections from 53 patients diagnosed with ENKTL, and their correlation with clinicopathologic variables was assessed. We also made a comparison between c-Myc positive and negative ENKTL on proliferation index (PI); and analyzed relationship between expression of c-Myc and Ki-67 index. The survival was analyzed by Kaplan-Meier product-limit method. Positive expression of c-Myc was shown in 64.2% of the patients, and high expression of Ki-67 was found in 66%. The PI in c-Myc-positive tumor cell was significantly higher than that in c-Myc-negative ones (P=0.005). The positive correlation between c-Myc expression and Ki-67 index was also found (r=0.454, P=0.001). Patients of c-Myc expression were shown to be associated with unfavorable overall survival (OS) and decreased progression free survival (PFS) (P=0.000 and 0.013, respectively). High expression of Ki-67 was also shown to be correlated with worse OS and PFS (P=0.014 and 0.016, respectively). And patients expression of c-Myc+/Ki-67 high had the worst OS and PFS (P=0.002 and 0.027, respectively). c-Myc may play an important role in the carcinogenesis of NK/T cell lymphoma by promoting cell proliferation. Both c-Myc expression and Ki-67 high expression in ENKTL patients may be valuable indicators for predicting the survival of ENKTL patients.
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Affiliation(s)
- Xiaoyin Huang
- Department of Medical Oncology, Jinling Hospital, Medical School of Nanjing University, 305 Zhong Shan Road East, Nanjing, Jiangsu Province, People's Republic of China
| | - Qian Sun
- Department of Medical Oncology, Jinling Hospital, Medical School of Nanjing University, 305 Zhong Shan Road East, Nanjing, Jiangsu Province, People's Republic of China
| | - Haijin Fu
- Department of Medical Oncology, Jinling Hospital, Medical School of Nanjing University, 305 Zhong Shan Road East, Nanjing, Jiangsu Province, People's Republic of China
| | - Xiaojun Zhou
- Department of Pathology, Jinling Hospital, Medical School of Nanjing University, Nanjing, Jiangsu Province, People's Republic of China
| | - Xiaoxiang Guan
- Department of Medical Oncology, Jinling Hospital, Medical School of Nanjing University, 305 Zhong Shan Road East, Nanjing, Jiangsu Province, People's Republic of China.
| | - Jinghua Wang
- Department of Medical Oncology, Jinling Hospital, Medical School of Nanjing University, 305 Zhong Shan Road East, Nanjing, Jiangsu Province, People's Republic of China.
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Frankenberger S, Davari K, Fischer-Burkart S, Böttcher K, Tomi NS, Zimber-Strobl U, Jungnickel B. Checkpoint kinase 1 negatively regulates somatic hypermutation. Nucleic Acids Res 2014; 42:3666-74. [PMID: 24423870 PMCID: PMC3973322 DOI: 10.1093/nar/gkt1378] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Immunoglobulin (Ig) diversification by somatic hypermutation in germinal center B cells is instrumental for maturation of the humoral immune response, but also bears the risk of excessive or aberrant genetic changes. Thus, introduction of DNA damage by activation-induced cytidine deaminase as well as DNA repair by multiple pathways need to be tightly regulated during the germinal center response to prevent lymphomagenesis. In the present study, we show that DNA damage checkpoint signaling via checkpoint kinase 1 (Chk1) negatively regulates somatic hypermutation. Chk1 inhibition in human B cell lymphoma lines as well as inactivation of Chk1 alleles by gene targeting in DT40 B cells leads to increased somatic hypermutation. This is apparently due to changes in DNA repair pathways regulated by Chk1, such as a decreased homologous recombination efficiency that also leads to decreased Ig gene conversion in DT40. Our data show that Chk1 signaling plays a crucial role in regulation of Ig diversification and sheds unexpected light on potential origins of aberrant somatic hypermutation in B cell lymphomagenesis.
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Affiliation(s)
- Samantha Frankenberger
- Institute of Clinical and Molecular Biology, Helmholtz Center Munich, Marchioninistrasse 25, 81377 Munich, Germany, Department of Cell Biology, Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine, Friedrich-Schiller University Jena, Hans-Knoell-Strasse 2, 07745 Jena, Germany and Department of Gene Vectors, Helmholtz Center Munich, Marchioninistrasse 25, 81377 Munich, Germany
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Fernández D, Ortiz M, Rodríguez L, García A, Martinez D, Moreno de Alborán I. The proto-oncogene c-myc regulates antibody secretion and Ig class switch recombination. THE JOURNAL OF IMMUNOLOGY 2013; 190:6135-44. [PMID: 23690468 DOI: 10.4049/jimmunol.1300712] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The immune response involves the generation of Ab-secreting cells and memory B cells through a process called terminal B lymphocyte differentiation. This program requires the transcriptional repressor Blimp-1, which inhibits c-myc expression and terminates proliferation. Although the role of c-Myc in cell proliferation is well characterized, it is not known whether it has other functions in terminal differentiation. In this study, we show that c-Myc not only regulates cell proliferation, but it is also essential for Ab-secreting cell function and differentiation in vivo. c-Myc-deficient B lymphocytes hypersecrete IgM and do not undergo Ig class switch recombination (CSR). CSR has been previously linked to proliferation, and in this study we mechanistically link class switching and proliferation via c-Myc. We observed that c-Myc regulates CSR by transcriptionally activating the B cell-specific factor activation-induced cytidine deaminase. By linking cell proliferation and CSR, c-Myc is thus a critical component for a potent immune response.
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Affiliation(s)
- David Fernández
- Departamento de Inmunología y Oncología, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Cientificas, Madrid E-28049, Spain
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Type I interferons directly down-regulate BCL-6 in primary and transformed germinal center B cells: differential regulation in B cell lines derived from endemic or sporadic Burkitt's lymphoma. Cytokine 2011; 57:360-71. [PMID: 22204827 DOI: 10.1016/j.cyto.2011.12.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Revised: 11/22/2011] [Accepted: 12/05/2011] [Indexed: 11/20/2022]
Abstract
Type I interferons (IFN) exert multiple effects on both the innate and adaptive immune system in addition to their antiviral and antiproliferative activities. Little is known, however about the direct effects of type I IFNs on germinal center (GC) B cells, the central components of adaptive B cell responses. We used Burkitt's lymphoma (BL) lines, as a model system of normal human GC B cells, to examine the effect of type I IFNs on the expression of BCL-6, the major regulator of the GC reaction. We show that type I IFNs, but not IFNγ, IL-2 and TNFα rapidly down-regulate BCL-6 protein and mRNA expression, in cell lines derived from endemic, but not from sporadic BL. IFNα-induced down-regulation is specific for BCL-6, independent of Epstein-Barr virus and is not accompanied by IRF-4 up-regulation. IFNα-induced BCL-6 mRNA down-regulation does not require de novo protein synthesis and is specifically inhibited by piceatannol. The proteasome inhibitor MG132 non-specifically prevents, while inhibitors of alternate type I IFN signaling pathways do not inhibit IFNα-induced BCL-6 protein downregulation. We validate our results with showing that IFNα rapidly down-regulates BCL-6 mRNA in purified mouse normal GC B cells. Our results identify type I IFNs as the first group of cytokines that can down-regulate BCL-6 expression directly in GC B cells.
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Abstract
Hematopoiesis is a process capable of generating millions of cells every second, as distributed in many cell types. The process is regulated by a number of transcription factors that regulate the differentiation along the distinct lineages and dictate the genetic program that defines each mature phenotype. Myc was first discovered as the oncogene of avian leukemogenic retroviruses; it was later found translocated in human lymphoma. From then on, evidence accumulated showing that c-Myc is one of the transcription factors playing a major role in hematopoiesis. The study of genetically modified mice with overexpression or deletion of Myc has shown that c-Myc is required for the correct balance between self-renewal and differentiation of hematopoietic stem cells (HSCs). Enforced Myc expression in mice leads to reduced HSC pools owing to loss of self-renewal activity at the expense of increased proliferation of progenitor cells and differentiation. c-Myc deficiency consistently results in the accumulation of HSCs. Other models with conditional Myc deletion have demonstrated that different lineages of hematopoietic cells differ in their requirement for c-Myc to regulate their proliferation and differentiation. When transgenic mice overexpress c-Myc or N-Myc in mature cells from the lymphoid or myeloid lineages, the result is lymphoma or leukemia. In agreement, enforced expression of c-Myc blocks the differentiation in several leukemia-derived cell lines capable of differentiating in culture. Not surprising, MYC deregulation is recurrently found in many types of human lymphoma and leukemia. Whereas MYC is deregulated by translocation in Burkitt lymphoma and, less frequently, other types of lymphoma, MYC is frequently overexpressed in acute lymphoblastic and myeloid leukemia, through mechanisms unrelated to chromosomal translocation, and is often associated with disease progression.
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Affiliation(s)
- M Dolores Delgado
- Departamento de Biología Molecular, Facultad de Medicina and Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria-CSIC, Santander, Spain
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Abstract
Apoptosis is crucial for immune system homeostasis, including selection and survival of long-lived antibody-forming cells and memory cells. The interactions between proapoptotic and pro-survival proteins of the Bcl-2 family are critical for this process. In this report, we show that expression of the proapoptotic BH3-only Bcl-2 family member Puma was selectively up-regulated on in vitro activation with antigens or mitogens of both human and mouse B cells. Puma expression coincided in vivo, with the prosurvival Bcl-2 family member Mcl-1 within the germinal centers and its expression correlates with the germinal center like phenotype of Burkitt lymphoma. Experiments performed in Puma-deficient mice revealed that Puma is essential for apoptosis of mitogen-activated B cells in vitro and for the control of memory B-cell survival. In conclusion, using both human and murine models, our data show that Puma has a major role in the T cell- dependent B-cell immune response. These data demonstrate that Puma is a major regulator of memory B lymphocyte survival and therefore a key molecule in the control of the immune response.
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CD300a is expressed on human B cells, modulates BCR-mediated signaling, and its expression is down-regulated in HIV infection. Blood 2011; 117:5870-80. [PMID: 21482706 DOI: 10.1182/blood-2010-09-310318] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The immunomodulatory receptor CD300a is expressed on human B cells. Naive B cells express very low levels of this receptor, whereas memory B cells and plasmablasts/cells express variable levels of CD300a. Germinal center B cells are negative for CD300a expression. Stimulation of naive B cells via B-cell receptor (BCR) and Toll-like receptor 9, along with T-cell help, failed to up-regulate CD300a cell surface expression despite the increased expression of the memory marker CD27 and the down-regulation of CD305. However, Toll-like receptor 9 stimulation alone significantly increased CD300a expression on memory B cells, whereas interleukin-4 and transforming growth factor-β1 act as negative regulators of CD300a expression on memory B cells. Coligation of BCR and CD300a inhibits Ca(2+) mobilization and nuclear factor of activated T cell transcriptional activity evoked by BCR ligation alone. Suppression of CD300a expression in primary B cells with siRNA resulted in increased BCR-mediated proliferation, thereby confirming the inhibitory capacity of CD300a. Finally, we show that CD300a expression levels are significantly down-regulated in the circulating B cells of HIV-infected patients. Altogether, these data demonstrate a novel mechanism for suppressing the activity of B cells and suggest a potential role for CD300a in the B-cell dysfunction observed in HIV-induced immunodeficiency.
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