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Perez-Perez D, Santos-Argumedo L, Rodriguez-Alba JC, Lopez-Herrera G. Analysis of LRBA pathogenic variants and the association with functional protein domains and clinical presentation. Pediatr Allergy Immunol 2024; 35:e14179. [PMID: 38923448 DOI: 10.1111/pai.14179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 05/29/2024] [Accepted: 06/07/2024] [Indexed: 06/28/2024]
Abstract
LRBA is a cytoplasmic protein that is ubiquitously distributed. Almost all LRBA domains have a scaffolding function. In 2012, it was reported that homozygous variants in LRBA are associated with early-onset hypogammaglobulinemia. Since its discovery, more than 100 pathogenic variants have been reported. This review focuses on the variants reported in LRBA and their possible associations with clinical phenotypes. In this work LRBA deficiency cases reported more than 11 years ago have been revised. A database was constructed to analyze the type of variants, age at onset, clinical diagnosis, infections, autoimmune diseases, and cellular and immunoglobulin levels. The review of cases from 2012 to 2023 showed that LRBA deficiency was commonly diagnosed in patients with a clinical diagnosis of Common Variable Immunodeficiency, followed by enteropathy, neonatal diabetes mellitus, ALPS, and X-linked-like syndrome. Most cases show early onset of presentation at <6 years of age. Most cases lack protein expression, whereas hypogammaglobulinemia is observed in half of the cases, and IgG and IgA levels are isotypes reported at low levels. Patients with elevated IgG levels exhibited more than one autoimmune manifestation. Patients carrying pathogenic variants leading to a premature stop codon show a severe phenotype as they have an earlier onset of disease presentation, severe autoimmune manifestations, premature death, and low B cells and regulatory T cell levels. Missense variants were more common in patients with low IgG levels and cytopenia. This work lead to the conclusion that the type of variant in LRBA has association with disease severity, which leads to a premature stop codon being the ones that correlates with severe disease.
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Affiliation(s)
- D Perez-Perez
- Doctorate Program in Biological Sciences, Autonomous National University of Mexico, Mexico City, Mexico
- Immunodeficiencies Laboratory, National Institute of Pediatrics (INP), Mexico City, Mexico
| | - L Santos-Argumedo
- Biomedicine Department, Center for Research and Advanced Studies of the National Polytechnic Institute (CINVESTAV), Mexico City, Mexico
| | - J C Rodriguez-Alba
- Neuroimmunology and Neurooncology Unit, The National Institute of Neurology and Neurosurgery (NINN), Mexico City, Mexico
- Medicine and Surgery Faculty, Autonomous University Benito Juarez from Oaxaca, Oaxaca, Mexico
| | - G Lopez-Herrera
- Immunodeficiencies Laboratory, National Institute of Pediatrics (INP), Mexico City, Mexico
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2
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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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3
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Del Pozo-Yauner L, Herrera GA, Perez Carreon JI, Turbat-Herrera EA, Rodriguez-Alvarez FJ, Ruiz Zamora RA. Role of the mechanisms for antibody repertoire diversification in monoclonal light chain deposition disorders: when a friend becomes foe. Front Immunol 2023; 14:1203425. [PMID: 37520549 PMCID: PMC10374031 DOI: 10.3389/fimmu.2023.1203425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Accepted: 06/20/2023] [Indexed: 08/01/2023] Open
Abstract
The adaptive immune system of jawed vertebrates generates a highly diverse repertoire of antibodies to meet the antigenic challenges of a constantly evolving biological ecosystem. Most of the diversity is generated by two mechanisms: V(D)J gene recombination and somatic hypermutation (SHM). SHM introduces changes in the variable domain of antibodies, mostly in the regions that form the paratope, yielding antibodies with higher antigen binding affinity. However, antigen recognition is only possible if the antibody folds into a stable functional conformation. Therefore, a key force determining the survival of B cell clones undergoing somatic hypermutation is the ability of the mutated heavy and light chains to efficiently fold and assemble into a functional antibody. The antibody is the structural context where the selection of the somatic mutations occurs, and where both the heavy and light chains benefit from protective mechanisms that counteract the potentially deleterious impact of the changes. However, in patients with monoclonal gammopathies, the proliferating plasma cell clone may overproduce the light chain, which is then secreted into the bloodstream. This places the light chain out of the protective context provided by the quaternary structure of the antibody, increasing the risk of misfolding and aggregation due to destabilizing somatic mutations. Light chain-derived (AL) amyloidosis, light chain deposition disease (LCDD), Fanconi syndrome, and myeloma (cast) nephropathy are a diverse group of diseases derived from the pathologic aggregation of light chains, in which somatic mutations are recognized to play a role. In this review, we address the mechanisms by which somatic mutations promote the misfolding and pathological aggregation of the light chains, with an emphasis on AL amyloidosis. We also analyze the contribution of the variable domain (VL) gene segments and somatic mutations on light chain cytotoxicity, organ tropism, and structure of the AL fibrils. Finally, we analyze the most recent advances in the development of computational algorithms to predict the role of somatic mutations in the cardiotoxicity of amyloidogenic light chains and discuss the challenges and perspectives that this approach faces.
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Affiliation(s)
- Luis Del Pozo-Yauner
- Department of Pathology, University of South Alabama-College of Medicine, Mobile, AL, United States
| | - Guillermo A. Herrera
- Department of Pathology, University of South Alabama-College of Medicine, Mobile, AL, United States
| | | | - Elba A. Turbat-Herrera
- Department of Pathology, University of South Alabama-College of Medicine, Mobile, AL, United States
- Mitchell Cancer Institute, University of South Alabama-College of Medicine, Mobile, AL, United States
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4
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Vlasevska S, Garcia-Ibanez L, Duval R, Holmes A, Jahan R, Cai B, Kim A, Mo T, Basso K, Soni R, Bhagat G, Dalla-Favera R, Pasqualucci L. KMT2D acetylation by CREBBP reveals a cooperative functional interaction at enhancers in normal and malignant germinal center B cells. Proc Natl Acad Sci U S A 2023; 120:e2218330120. [PMID: 36893259 PMCID: PMC10089214 DOI: 10.1073/pnas.2218330120] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 01/26/2023] [Indexed: 03/11/2023] Open
Abstract
Heterozygous inactivating mutations of the KMT2D methyltransferase and the CREBBP acetyltransferase are among the most common genetic alterations in B cell lymphoma and co-occur in 40 to 60% of follicular lymphoma (FL) and 30% of EZB/C3 diffuse large B cell lymphoma (DLBCL) cases, suggesting they may be coselected. Here, we show that combined germinal center (GC)-specific haploinsufficiency of Crebbp and Kmt2d synergizes in vivo to promote the expansion of abnormally polarized GCs, a common preneoplastic event. These enzymes form a biochemical complex on select enhancers/superenhancers that are critical for the delivery of immune signals in the GC light zone and are only corrupted upon dual Crebbp/Kmt2d loss, both in mouse GC B cells and in human DLBCL. Moreover, CREBBP directly acetylates KMT2D in GC-derived B cells, and, consistently, its inactivation by FL/DLBCL-associated mutations abrogates its ability to catalyze KMT2D acetylation. Genetic and pharmacologic loss of CREBBP and the consequent decrease in KMT2D acetylation lead to reduced levels of H3K4me1, supporting a role for this posttranslational modification in modulating KMT2D activity. Our data identify a direct biochemical and functional interaction between CREBBP and KMT2D in the GC, with implications for their role as tumor suppressors in FL/DLBCL and for the development of precision medicine approaches targeting enhancer defects induced by their combined loss.
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Affiliation(s)
- Sofija Vlasevska
- Institute for Cancer Genetics, Columbia University, New York, NY10032
| | | | - Romain Duval
- Institute for Cancer Genetics, Columbia University, New York, NY10032
| | - Antony B. Holmes
- Institute for Cancer Genetics, Columbia University, New York, NY10032
| | - Rahat Jahan
- Institute for Cancer Genetics, Columbia University, New York, NY10032
| | - Bowen Cai
- Institute for Cancer Genetics, Columbia University, New York, NY10032
| | - Andrew Kim
- Institute for Cancer Genetics, Columbia University, New York, NY10032
| | - Tongwei Mo
- Institute for Cancer Genetics, Columbia University, New York, NY10032
| | - Katia Basso
- Institute for Cancer Genetics, Columbia University, New York, NY10032
- Department of Pathology and Cell Biology, Columbia University, New York, NY10032
| | - Rajesh K. Soni
- Proteomics and Macromolecular Crystallography Shared Resource, Columbia University, New York, NY10032
- Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY10032
| | - Govind Bhagat
- Department of Pathology and Cell Biology, Columbia University, New York, NY10032
- Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY10032
| | - Riccardo Dalla-Favera
- Institute for Cancer Genetics, Columbia University, New York, NY10032
- Department of Pathology and Cell Biology, Columbia University, New York, NY10032
- Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY10032
- Department of Genetics and Development, Columbia University, New York, NY10032
- Department of Microbiology and Immunology, Columbia University, New York, NY10032
| | - Laura Pasqualucci
- Institute for Cancer Genetics, Columbia University, New York, NY10032
- Department of Pathology and Cell Biology, Columbia University, New York, NY10032
- Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY10032
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5
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Role of Protein Kinase A Activation in the Immune System with an Emphasis on Lipopolysaccharide-Responsive and Beige-like Anchor Protein in B Cells. Int J Mol Sci 2023; 24:ijms24043098. [PMID: 36834508 PMCID: PMC9962394 DOI: 10.3390/ijms24043098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Revised: 01/13/2023] [Accepted: 01/17/2023] [Indexed: 02/08/2023] Open
Abstract
Cyclic AMP-dependent protein kinase A (PKA) is a ubiquitous enzymatic complex that is involved in a broad spectrum of intracellular receptor signaling. The activity of PKA depends on A-kinase anchoring proteins (AKAPs) that attach to PKAs close to their substrates to control signaling. Although the relevance of PKA-AKAP signaling in the immune system is evident in T cells, its relevance in B and other immune cells remains relatively unclear. In the last decade, lipopolysaccharide-responsive and beige-like anchor protein (LRBA) has emerged as an AKAP that is ubiquitously expressed in B and T cells, specifically after activation. A deficiency of LRBA leads to immune dysregulation and immunodeficiency. The cellular mechanisms regulated by LRBA have not yet been investigated. Therefore, this review summarizes the functions of PKA in immunity and provides the most recent information regarding LRBA deficiency to deepen our understanding of immune regulation and immunological diseases.
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Abstract
The AID/APOBEC polynucleotide cytidine deaminases have historically been classified as either DNA mutators or RNA editors based on their first identified nucleic acid substrate preference. DNA mutators can generate functional diversity at antibody genes but also cause genomic instability in cancer. RNA editors can generate informational diversity in the transcriptome of innate immune cells, and of cancer cells. Members of both classes can act as antiviral restriction factors. Recent structural work has illuminated differences and similarities between AID/APOBEC enzymes that can catalyse DNA mutation, RNA editing or both, suggesting that the strict functional classification of members of this family should be reconsidered. As many of these enzymes have been employed for targeted genome (or transcriptome) editing, a more holistic understanding will help improve the design of therapeutically relevant programmable base editors. In this Perspective, Pecori et al. provide an overview of the AID/APOBEC cytidine deaminase family, discussing key structural features, how they contribute to viral and tumour evolution and how they can be harnessed for (potentially therapeutic) base-editing purposes.
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Shilova ON, Tsyba DL, Shilov ES. Mutagenic Activity of AID/APOBEC Deaminases in Antiviral Defense and Carcinogenesis. Mol Biol 2022; 56:46-58. [PMID: 35194245 PMCID: PMC8852905 DOI: 10.1134/s002689332201006x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 04/23/2021] [Accepted: 06/01/2021] [Indexed: 01/02/2023]
Abstract
Proteins of the AID/APOBEC family are capable of cytidine deamination in nucleic acids forming uracil. These enzymes are involved in mRNA editing, protection against viruses, the introduction of point mutations into DNA during somatic hypermutation, and antibody isotype switching. Since these deaminases, especially AID, are potent mutagens, their expression, activity, and specificity are regulated by several intracellular mechanisms. In this review, we discuss the mechanisms of impaired expression and activation of AID/APOBEC proteins in human tumors and their role in carcinogenesis and tumor progression. Also, the diagnostic and potential therapeutic value of increased expression of AID/APOBEC in different types of tumors is analyzed. We assume that in the case of solid tumors, increased expression of endogenous deaminases can serve as a marker of response to immunotherapy since multiple point mutations in host DNA could lead to amino acid substitutions in tumor proteins and thereby increase the frequency of neoepitopes.
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Affiliation(s)
- O. N. Shilova
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
| | - D. L. Tsyba
- Pavlov First State Medical University, 197022 St. Petersburg, Russia
- Sirius University of Science and Technology, 354340 Sochi, Russia
| | - E. S. Shilov
- Faculty of Biology, Moscow State University, 119234 Moscow, Russia
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Liu J, Zhou J, Zhao S, Xu X, Li CJ, Li L, Shen T, Hunt PW, Zhang R. Differential responses of abomasal transcriptome to Haemonchus contortus infection between Haemonchus-selected and Trichostrongylus-selected merino sheep. Parasitol Int 2022; 87:102539. [PMID: 35007764 DOI: 10.1016/j.parint.2022.102539] [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: 04/14/2021] [Revised: 12/16/2021] [Accepted: 01/04/2022] [Indexed: 10/19/2022]
Abstract
Haemonchus contortus is the most prevalent and pathogenic gastrointestinal nematode infecting sheep and goats. The two CSIRO sheep resource flocks, the Haemonchus-selected flock (HSF) and Trichostrongylus-selected flock (TSF) were developed for research on host resistance or susceptibility to gastrointestinal nematode infection. A recent study focused on the gene expression differences between resistant and susceptible sheep within each flock, with lymphatic and gastrointestinal tissues. To identify features in the host transcriptome and understand the molecular differences underlying host resistance to H. contortus between flocks with different selective breeding and genetic backgrounds, we compared the abomasal transcriptomic responses of the resistant or susceptible animals between HSF and TSF flocks. A total of 11 and 903 differentially expressed genes were identified in the innate infection treatment in HSF and TSF flocks between resistant and susceptible sheep respectively, while 52 and 485 genes were identified to be differentially expressed in the acquired infection treatment, respectively. Among them, 294 genes had significantly different gene expression levels between HSF and TSF flock animals within the susceptible sheep by both the innate and acquired infections. Moreover, similar expression patterns of the 294 genes were observed, with 273 genes more highly expressed in HSF and 21 more highly expressed in the TSF within the abomasal transcriptome of the susceptible animals. Gene ontology enrichment of the differentially expressed genes identified in this study predicted the likely differing function between the two flock's susceptible lines in response to H. contortus infection. Nineteen pathways were significantly enriched in both the innate and adaptive immune responses in susceptible animals, which indicated that these pathways likely contribute to the host resistance development to H. contortus infection in susceptible sheep. Biological networks built for the set of genes differentially abundant in susceptible animals identified hub genes of PRKG1, PRKACB, PRKACA, and ITGB1 for the innate immune response, and CALM2, MYL1, COL1A1, ITGB1 and ITGB3 for the adaptive immune response, respectively. Our results offered a quantitative snapshot of host transcriptomic changes induced by H. contortus infection between flocks with different selective breeding and genetic backgrounds and provided novel insights into molecular mechanisms of host resistance.
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Affiliation(s)
- Jing Liu
- College of Life Science, Hubei Key Laboratory of Edible Wild Plants Conservation & Utilization, Huangshi Biomedicine Industry and Technology Research Institute Company Limited, Hubei Normal University, Huangshi, Hubei 435002, China
| | - Jiachang Zhou
- College of Life Science, Hubei Key Laboratory of Edible Wild Plants Conservation & Utilization, Huangshi Biomedicine Industry and Technology Research Institute Company Limited, Hubei Normal University, Huangshi, Hubei 435002, China
| | - Si Zhao
- College of Life Science, Hubei Key Laboratory of Edible Wild Plants Conservation & Utilization, Huangshi Biomedicine Industry and Technology Research Institute Company Limited, Hubei Normal University, Huangshi, Hubei 435002, China; International Medical School, Hebei Foreign Studies University, Shijiazhuang, Hebei 050096, China
| | - Xiangdong Xu
- College of Life Science, Hubei Key Laboratory of Edible Wild Plants Conservation & Utilization, Huangshi Biomedicine Industry and Technology Research Institute Company Limited, Hubei Normal University, Huangshi, Hubei 435002, China
| | - Cong-Jun Li
- United States Department of Agriculture, Agriculture Research Service (USDA-ARS), Animal Genomics and Improvement Laboratory, Beltsville, MD 20705, USA.
| | - Li Li
- College of Life Science, Hubei Key Laboratory of Edible Wild Plants Conservation & Utilization, Huangshi Biomedicine Industry and Technology Research Institute Company Limited, Hubei Normal University, Huangshi, Hubei 435002, China
| | - Tingbo Shen
- College of Life Science, Hubei Key Laboratory of Edible Wild Plants Conservation & Utilization, Huangshi Biomedicine Industry and Technology Research Institute Company Limited, Hubei Normal University, Huangshi, Hubei 435002, China
| | - Peter W Hunt
- CSIRO Agriculture and Food, Armidale, NSW, Australia.
| | - Runfeng Zhang
- College of Life Science, Hubei Key Laboratory of Edible Wild Plants Conservation & Utilization, Huangshi Biomedicine Industry and Technology Research Institute Company Limited, Hubei Normal University, Huangshi, Hubei 435002, China.
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9
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USP10 regulates B cell response to SARS-CoV-2 or HIV-1 nanoparticle vaccines through deubiquitinating AID. Signal Transduct Target Ther 2022; 7:7. [PMID: 34983926 PMCID: PMC8724756 DOI: 10.1038/s41392-021-00858-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 11/28/2021] [Accepted: 12/07/2021] [Indexed: 12/13/2022] Open
Abstract
Activation-induced cytidine deaminase (AID) initiates class-switch recombination and somatic hypermutation (SHM) in antibody genes. Protein expression and activity are tightly controlled by various mechanisms. However, it remains unknown whether a signal from the extracellular environment directly affects the AID activity in the nucleus where it works. Here, we demonstrated that a deubiquitinase USP10, which specifically stabilizes nuclear AID protein, can translocate into the nucleus after AKT-mediated phosphorylation at its T674 within the NLS domain. Interestingly, the signals from BCR and TLR1/2 synergistically promoted this phosphorylation. The deficiency of USP10 in B cells significantly decreased AID protein levels, subsequently reducing neutralizing antibody production after immunization with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or human immunodeficiency virus type 1 (HIV-1) nanoparticle vaccines. Collectively, we demonstrated that USP10 functions as an integrator for both BCR and TLR signals and directly regulates nuclear AID activity. Its manipulation could be used for the development of vaccines and adjuvants.
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10
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King JJ, Borzooee F, Im J, Asgharpour M, Ghorbani A, Diamond CP, Fifield H, Berghuis L, Larijani M. Structure-Based Design of First-Generation Small Molecule Inhibitors Targeting the Catalytic Pockets of AID, APOBEC3A, and APOBEC3B. ACS Pharmacol Transl Sci 2021; 4:1390-1407. [PMID: 34423273 PMCID: PMC8369683 DOI: 10.1021/acsptsci.1c00091] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Indexed: 12/12/2022]
Abstract
![]()
Activation-induced
cytidine deaminase (AID) initiates antibody
diversification by mutating immunoglobulin loci in B lymphocytes.
AID and related APOBEC3 (A3) enzymes also induce genome-wide mutations
and lesions implicated in tumorigenesis and tumor progression. The
most prevalent mutation signatures across diverse tumor genomes are
attributable to the mistargeted mutagenic activities of AID/A3s. Thus,
inhibiting AID/A3s has been suggested to be of therapeutic benefit.
We previously used a computational-biochemical approach to gain insight
into the structure of AID’s catalytic pocket, which resulted
in the discovery of a novel type of regulatory catalytic pocket closure
that regulates AID/A3s that we termed the “Schrodinger’s
CATalytic pocket”. Our findings were subsequently confirmed
by direct structural studies. Here, we describe our search for small
molecules that target the catalytic pocket of AID. We identified small
molecules that inhibit purified AID, AID in cell extracts, and endogenous
AID of lymphoma cells. Analogue expansion yielded derivatives with
improved potencies. These were found to also inhibit A3A and A3B,
the two most tumorigenic siblings of AID. Two compounds exhibit low
micromolar IC50 inhibition of AID and A3A, exhibiting the
strongest potency for A3A. Docking suggests key interactions between
their warheads and residues lining the catalytic pockets of AID, A3A,
and A3B and between the tails and DNA-interacting residues on the
surface proximal to the catalytic pocket opening. Accordingly, mutants
of these residues decreased inhibition potency. The chemistry and
abundance of key stabilizing interactions between the small molecules
and residues within and immediately outside the catalytic pockets
are promising for therapeutic development.
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Affiliation(s)
- Justin J King
- Department of Molecular Biology and Biochemistry, Faculty of Science, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada.,Program in immunology and Infectious Diseases, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3 V6, Canada
| | - Faezeh Borzooee
- Department of Molecular Biology and Biochemistry, Faculty of Science, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada.,Program in immunology and Infectious Diseases, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3 V6, Canada
| | - Junbum Im
- Program in immunology and Infectious Diseases, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3 V6, Canada.,BC Cancer Research/Terry Fox Labs, University of British Columbia, Vancouver, British Columbia BC V5Z 1L3, Canada
| | - Mahdi Asgharpour
- Department of Molecular Biology and Biochemistry, Faculty of Science, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada.,Program in immunology and Infectious Diseases, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3 V6, Canada
| | - Atefeh Ghorbani
- Department of Molecular Biology and Biochemistry, Faculty of Science, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada.,Program in immunology and Infectious Diseases, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3 V6, Canada
| | - Cody P Diamond
- Program in immunology and Infectious Diseases, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3 V6, Canada
| | - Heather Fifield
- Program in immunology and Infectious Diseases, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3 V6, Canada
| | - Lesley Berghuis
- Program in immunology and Infectious Diseases, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3 V6, Canada
| | - Mani Larijani
- Department of Molecular Biology and Biochemistry, Faculty of Science, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada.,Program in immunology and Infectious Diseases, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3 V6, Canada
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Kim EN, Nabende WY, Jeong H, Hahn D, Jeong GS. The Marine-Derived Natural Product Epiloliolide Isolated from Sargassum horneri Regulates NLRP3 via PKA/CREB, Promoting Proliferation and Anti-Inflammatory Effects of Human Periodontal Ligament Cells. Mar Drugs 2021; 19:388. [PMID: 34356813 PMCID: PMC8304756 DOI: 10.3390/md19070388] [Citation(s) in RCA: 3] [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: 05/12/2021] [Revised: 07/02/2021] [Accepted: 07/05/2021] [Indexed: 12/11/2022] Open
Abstract
Currently, periodontitis treatment relies on surgical operations, anti-inflammatory agents, or antibiotics. However, these treatments cause pain and side effects, resulting in a poor prognosis. Therefore, in this study, we evaluated the impact of the compound epiloliolide isolated from Sargassum horneri on the recovery of inflammatory inhibitors and loss of periodontal ligaments, which are essential treatment strategies for periodontitis. Here, human periodontal ligament cells stimulated with PG-LPS were treated with the compound epiloliolide, isolated from S. horneri. In the results of this study, epiloliolide proved the anti-inflammatory effect, cell proliferation capacity, and differentiation potential of periodontal ligament cells into osteoblasts, through the regulation of the PKA/CREB signaling pathway. Epiloliolide effectively increased the proliferation and migration of human periodontal ligament cells without cytotoxicity and suppressed the protein expression of proinflammatory mediators and cytokines, such as iNOS, COX-2, TNF-α, IL-6, and IL-1β, by downregulating NLRP3 activated by PG-LPS. Epiloliolide also upregulated the phosphorylation of PKA/CREB proteins, which play an important role in cell growth and proliferation. It was confirmed that the anti-inflammatory effect in PG-LPS-stimulated large cells was due to the regulation of PKA/CREB signaling. We suggest that epiloliolide could serve as a potential novel therapeutic agent for periodontitis by inhibiting inflammation and restoring the loss of periodontal tissue.
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Affiliation(s)
- Eun-Nam Kim
- College of Pharmacy, Keimyung University, 1095 Dalgubeol-daero, Daegu 42601, Korea;
| | - Woguti Yvonne Nabende
- School of Food Science and Biotechnology, College of Agriculture and Life Sciences, Kyungpook National University, Daegu 41566, Korea; (W.Y.N.); (H.J.)
| | - Hyeyoon Jeong
- School of Food Science and Biotechnology, College of Agriculture and Life Sciences, Kyungpook National University, Daegu 41566, Korea; (W.Y.N.); (H.J.)
| | - Dongyup Hahn
- School of Food Science and Biotechnology, College of Agriculture and Life Sciences, Kyungpook National University, Daegu 41566, Korea; (W.Y.N.); (H.J.)
- Department of Integrative Biology, Kyungpook National University, Daegu 41566, Korea
| | - Gil-Saeng Jeong
- College of Pharmacy, Keimyung University, 1095 Dalgubeol-daero, Daegu 42601, Korea;
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12
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Oppezzo P, Navarrete M, Chiorazzi N. AID in Chronic Lymphocytic Leukemia: Induction and Action During Disease Progression. Front Oncol 2021; 11:634383. [PMID: 34041018 PMCID: PMC8141630 DOI: 10.3389/fonc.2021.634383] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 02/23/2021] [Indexed: 12/12/2022] Open
Abstract
The enzyme activation-induced cytidine deaminase (AID) initiates somatic hypermutation (SHM) and class switch recombination (CSR) of immunoglobulin (Ig) genes, critical actions for an effective adaptive immune response. However, in addition to the benefits generated by its physiological roles, AID is an etiological factor for the development of human and murine leukemias and lymphomas. This review highlights the pathological role of AID and the consequences of its actions on the development, progression, and therapeutic refractoriness of chronic lymphocytic leukemia (CLL) as a model disease for mature lymphoid malignancies. First, we summarize pertinent aspects of the expression and function of AID in normal B lymphocytes. Then, we assess putative causes for AID expression in leukemic cells emphasizing the role of an activated microenvironment. Thirdly, we discuss the role of AID in lymphomagenesis, in light of recent data obtained by NGS analyses on the genomic landscape of leukemia and lymphomas, concentrating on the frequency of AID signatures in these cancers and correlating previously described tumor-gene drivers with the presence of AID off-target mutations. Finally, we discuss how these changes could affect tumor suppressor and proto-oncogene targets and how they could be associated with disease progression. Collectively, we hope that these sections will help to better understand the complex paradox between the physiological role of AID in adaptive immunity and its potential causative activity in B-cell malignancies.
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Affiliation(s)
- Pablo Oppezzo
- Research Laboratory on Chronic Lymphocytic Leukemia, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | | | - Nicholas Chiorazzi
- The Karches Center for Oncology Research, The Feinstein Institutes for Medical Research, New York, NY, United States
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13
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Kuhny M, Forbes LR, Çakan E, Vega-Loza A, Kostiuk V, Dinesh RK, Glauzy S, Stray-Pedersen A, Pezzi AE, Hanson IC, Vargas-Hernandez A, Xu ML, Coban-Akdemir ZH, Jhangiani SN, Muzny DM, Gibbs RA, Lupski JR, Chinn IK, Schatz DG, Orange JS, Meffre E. Disease-associated CTNNBL1 mutation impairs somatic hypermutation by decreasing nuclear AID. J Clin Invest 2021; 130:4411-4422. [PMID: 32484799 DOI: 10.1172/jci131297] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 05/13/2020] [Indexed: 01/02/2023] Open
Abstract
Patients with common variable immunodeficiency associated with autoimmune cytopenia (CVID+AIC) generate few isotype-switched B cells with severely decreased frequencies of somatic hypermutations (SHMs), but their underlying molecular defects remain poorly characterized. We identified a CVID+AIC patient who displays a rare homozygous missense M466V mutation in β-catenin-like protein 1 (CTNNBL1). Because CTNNBL1 binds activation-induced cytidine deaminase (AID) that catalyzes SHM, we tested AID interactions with the CTNNBL1 M466V variant. We found that the M466V mutation interfered with the association of CTNNBL1 with AID, resulting in decreased AID in the nuclei of patient EBV-transformed B cell lines and of CTNNBL1 466V/V Ramos B cells engineered to express only CTNNBL1 M466V using CRISPR/Cas9 technology. As a consequence, the scarce IgG+ memory B cells from the CTNNBL1 466V/V patient showed a low SHM frequency that averaged 6.7 mutations compared with about 18 mutations per clone in healthy-donor counterparts. In addition, CTNNBL1 466V/V Ramos B cells displayed a decreased incidence of SHM that was reduced by half compared with parental WT Ramos B cells, demonstrating that the CTNNBL1 M466V mutation is responsible for defective SHM induction. We conclude that CTNNBL1 plays an important role in regulating AID-dependent antibody diversification in humans.
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Affiliation(s)
- Marcel Kuhny
- Department of Immunobiology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Lisa R Forbes
- Section of Pediatric Allergy, Immunology, and Rheumatology, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA.,William T. Shearer Texas Children's Hospital Center for Human Immunobiology, Houston, Texas, USA
| | - Elif Çakan
- Department of Immunobiology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Andrea Vega-Loza
- Department of Immunobiology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Valentyna Kostiuk
- Department of Immunobiology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Ravi K Dinesh
- Department of Immunobiology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Salomé Glauzy
- Department of Immunobiology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Asbjorg Stray-Pedersen
- Baylor-Hopkins Center for Mendelian Genomics, Houston, Texas, USA.,Institute of Clinical Medicine and.,Norwegian National Unit for Newborn Screening, Department of Pediatric and Adolescent Medicine, Oslo University Hospital, Oslo, Norway
| | - Ashley E Pezzi
- Department of Dermatology, Baylor College of Medicine, Houston, Texas, USA
| | - I Celine Hanson
- Section of Pediatric Allergy, Immunology, and Rheumatology, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Alexander Vargas-Hernandez
- Section of Pediatric Allergy, Immunology, and Rheumatology, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA.,William T. Shearer Texas Children's Hospital Center for Human Immunobiology, Houston, Texas, USA
| | - Mina LuQuing Xu
- Department of Pathology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Zeynep H Coban-Akdemir
- Baylor-Hopkins Center for Mendelian Genomics, Houston, Texas, USA.,Department of Molecular and Human Genetics and
| | - Shalini N Jhangiani
- Department of Molecular and Human Genetics and.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
| | - Donna M Muzny
- Department of Molecular and Human Genetics and.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
| | - Richard A Gibbs
- Baylor-Hopkins Center for Mendelian Genomics, Houston, Texas, USA.,Department of Molecular and Human Genetics and.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
| | - James R Lupski
- Baylor-Hopkins Center for Mendelian Genomics, Houston, Texas, USA.,Department of Molecular and Human Genetics and.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
| | - Ivan K Chinn
- Section of Pediatric Allergy, Immunology, and Rheumatology, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA.,William T. Shearer Texas Children's Hospital Center for Human Immunobiology, Houston, Texas, USA.,Baylor-Hopkins Center for Mendelian Genomics, Houston, Texas, USA
| | - David G Schatz
- Department of Immunobiology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Jordan S Orange
- Department of Pediatrics, College of Physicians and Surgeons of Columbia University, New York-Presbyterian Morgan Stanley Children's Hospital, New York, New York, USA
| | - Eric Meffre
- Department of Immunobiology, Yale University School of Medicine, New Haven, Connecticut, USA.,Section of Rheumatology, Allergy, and Clinical Immunology, Yale University School of Medicine, New Haven, Connecticut, USA
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14
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Abstract
MicroRNAs (miRNAs) represent RNA species found in serum. Many miRNAs were observed that were related to osteoporosis and osteopenia. However, expression and function analysis of miRNAs in postmenopausal osteoporosis (PMOP) remain unaddressed. We first compared the miRNA expression of blood samples in postmenopausal women with osteopenia or with osteoporosis via analysis of GSE64433. Bioinformatics analyses were conducted to get the key miRNAs and their functions and pathways. 331 miRNAs were being identified as differentially expressed miRNAs. Among these, 122 miRNA (36.86%) were up-regulated, and the remaining 209 miRNAs (63.14%) were down-regulated. 105 genes were predicted as the targets of these miRNAs. GO enrichment analysis results showed that the miRNAs mainly enriched in DNA binding, ATP binding, gene expression, regulation of the apoptotic process, chromatin binding, and protein kinase binding. KEGG enrichment analysis results demonstrated that the miRNAs mainly enriched in the TGF beta signaling pathway, wnt signaling pathway, JAK-STAT signaling pathway, and androgen receptor signaling pathway. This study identified the abundant differentially expressed miRNAs in the blood samples of postmenopausal women with osteopenia or with osteoporosis. This study may contribute to getting new diagnostic and therapeutic strategies for PMOP.
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Affiliation(s)
- Yulin Li
- Department of Orthopaedics, Tianjin Medical University General Hospital, Tianjin, P. R. China
| | - Zhongju Shi
- Department of Orthopaedics, Tianjin Medical University General Hospital, Tianjin, P. R. China
| | - Shiqing Feng
- Department of Orthopaedics, Tianjin Medical University General Hospital, Tianjin, P. R. China
- International Science and Technology Cooperation Base of Spinal Cord Injury, Tianjin Key Laboratory of Spine and Spinal Cord, Tianjin Medical University General Hospital, Tianjin, P. R. China
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15
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Jaiswal A, Singh AK, Tamrakar A, Kodgire P. Unfolding the Role of Splicing Factors and RNA Debranching in AID Mediated Antibody Diversification. Int Rev Immunol 2020; 40:289-306. [PMID: 32924658 DOI: 10.1080/08830185.2020.1815725] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Activated B-cells diversify their antibody repertoire via somatic hypermutation (SHM) and class switch recombination (CSR). SHM is restricted to the variable region, whereas, CSR is confined to the constant region of immunoglobulin (Ig) genes. Activation-induced cytidine deaminase (AID) is a crucial player in the diversification of antibodies in the activated B-cell. AID catalyzes the deamination of cytidine (C) into uracil (U) at Ig genes. Subsequently, low fidelity repair of U:G mismatches may lead to mutations. Transcription is essential for the AID action, as it provides a transient single-strand DNA substrate. Since splicing is a co-transcriptional event, various splicing factors or regulators influence the transcription. Numerous splicing factors are known to regulate the AID targeting, function, Ig transcription, and AID splicing, which eventually influence antibody diversification processes. Splicing regulator SRSF1-3, a splicing isoform of serine arginine-rich splicing factor (SRSF1), and CTNNBL1, a spliceosome interacting factor, interact with AID and play a critical role in SHM. Likewise, a splicing regulator polypyrimidine tract binding protein-2 (PTBP2) and the debranching enzyme (DBR1) debranches primary switch transcripts which later forms G-quadruplex structures, and the S region guide RNAs direct AID to S region DNA. Moreover, AID shows several alternate splicing isoforms, like AID devoid of exon-4 (AIDΔE4) that is expressed in various pathological conditions. Interestingly, RBM5, a splicing regulator, is responsible for the skipping of AID exon 4. In this review, we discuss the role and significance of splicing factors in the AID mediated antibody diversification.
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Affiliation(s)
- Ankit Jaiswal
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Indore, Madhya Pradesh, India
| | - Amit Kumar Singh
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Indore, Madhya Pradesh, India
| | - Anubhav Tamrakar
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Indore, Madhya Pradesh, India
| | - Prashant Kodgire
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Indore, Madhya Pradesh, India
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16
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Activation-induced cytidine deaminase: in sickness and in health. J Cancer Res Clin Oncol 2020; 146:2721-2730. [PMID: 32772231 DOI: 10.1007/s00432-020-03348-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 08/04/2020] [Indexed: 12/17/2022]
Abstract
Activation Induced cytidine Deaminase (AID) is an essential enzyme of the adaptive immune system. Its canonical activity is restricted to B lymphocytes, playing an essential role in the diversification of antibodies by enhancing specificity and changing affinity. This is possible through its DNA deaminase function, leading to mutations in DNA. In the last decade, AID has been assigned an additional function: that of a powerful DNA demethylator. Adverse cellular conditions such as chronic inflammation can lead to its deregulation and overexpression. It is an important driver of B-cell lymphoma due to its natural ability to modify DNA through deamination, leading to mutations and epigenetic changes. However, the deregulation of AID is not restricted to lymphoid cells. Recent findings have provided new insights into the role that this protein plays in the development of non-lymphoid cancers, with some research shedding light on novel AID-driven mechanisms of cellular transformation. In this review, we provide an updated narrative of the normal physiological functions of AID. Additionally, we review and discuss the recent research studies that have implicated AID in carcinogenesis in varying tissue types including lymphoid and non-lymphoid cancers. We review the mechanisms, whereby AID promotes carcinogenesis and highlight important areas of future research.
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17
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Moreno-Corona NC, Lopez-Ortega O, Flores Hermenegildo JM, Berron-Ruiz L, Rodriguez-Alba JC, Santos-Argumedo L, Lopez-Herrera G. Lipopolysaccharide-responsive beige-like anchor acts as a cAMP-dependent protein kinase anchoring protein in B cells. Scand J Immunol 2020; 92:e12922. [PMID: 32592188 DOI: 10.1111/sji.12922] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 05/15/2020] [Accepted: 06/21/2020] [Indexed: 01/04/2023]
Abstract
Lipopolysaccharide (LPS)-responsive beige-like anchor (LRBA) protein was initially described as a monogenetic cause for common variable immune deficiency, a syndrome characterized by low levels of B cells, defects in memory B cell differentiation and hypogammaglobulinaemia. LRBA was identified as an LPS up-regulated gene in B cells, macrophages and T cells. LRBA weighs 320 kDa and has 2863 amino acids. Its sequence contains multiple domains, suggesting that LRBA can act as a scaffolding protein. It contains two putative binding sites for cAMP-dependent kinase (PKA) regulatory subunits, suggesting this protein can act as A-kinase anchor protein (AKAP); however, physical interactions involving LRBA and PKA have not been demonstrated to date, and functional roles for such interactions are unexplored. In this work, we investigated physical interactions involving LRBA with regulatory subunits of PKA in human B cell lines and primary human B cells. PKA is a holoenzyme composed of two regulatory subunits, which can be RIα, RIβ, RIIα or RIIβ, and two catalytic subunits, Cα or Cβ. We co-immunoprecipitated LRBA using Ramos B cell lymphoma cells and observed that LRBA interacts with RIIβ. Interestingly, St-Ht31, an inhibitory peptide that disrupts AKAP interactions with regulatory subunits, reduced the amount of interacting protein. Furthermore, in primary human B cells, LRBA was induced after CD40L and IL-4 stimulation, and under such activation, we found that LRBA interacts with RIIα and RIIβ, suggesting that LRBA acts as an AKAP and binds RII subunits. Interestingly, we also identified that LRBA interacts with activation-induced cytidine deaminase in primary B cells, suggesting that it is involved in B cell function.
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Affiliation(s)
- Nidia Carolina Moreno-Corona
- Biomedicina Molecular, Centro de Investigacion y de Estudios Avanzados, Mexico City, Mexico.,Unidad de Investigacion en Inmunodeficiencias, Instituto Nacional de Pediatria, Mexico City, Mexico
| | - Orestes Lopez-Ortega
- Biomedicina Molecular, Centro de Investigacion y de Estudios Avanzados, Mexico City, Mexico
| | - Jose Mizael Flores Hermenegildo
- Biomedicina Molecular, Centro de Investigacion y de Estudios Avanzados, Mexico City, Mexico.,Unidad de Investigacion en Inmunodeficiencias, Instituto Nacional de Pediatria, Mexico City, Mexico
| | - Laura Berron-Ruiz
- Unidad de Investigacion en Inmunodeficiencias, Instituto Nacional de Pediatria, Mexico City, Mexico
| | - Juan Carlos Rodriguez-Alba
- Unidad de Citometria de Flujo, Instituto de Ciencias de la Salud, Universidad Veracruzana, Xalapa, Veracruz, Mexico
| | | | - Gabriela Lopez-Herrera
- Unidad de Investigacion en Inmunodeficiencias, Instituto Nacional de Pediatria, Mexico City, Mexico
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18
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Choi JE, Matthews AJ, Michel G, Vuong BQ. AID Phosphorylation Regulates Mismatch Repair-Dependent Class Switch Recombination and Affinity Maturation. THE JOURNAL OF IMMUNOLOGY 2020; 204:13-22. [PMID: 31757865 DOI: 10.4049/jimmunol.1900809] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 10/25/2019] [Indexed: 01/01/2023]
Abstract
Activation-induced cytidine deaminase (AID) generates U:G mismatches in Ig genes that can be converted into untemplated mutations during somatic hypermutation or DNA double-strand breaks during class switch recombination (CSR). Null mutations in UNG and MSH2 demonstrate the complementary roles of the base excision repair (BER) and mismatch repair pathways, respectively, in CSR. Phosphorylation of AID at serine 38 was previously hypothesized to regulate BER during CSR, as the AID phosphorylation mutant, AID(S38A), cannot interact with APE1, a BER protein. Consistent with these findings, we observe a complete block in CSR in AIDS38A/S38AMSH2-/- mouse B cells that correlates with an impaired mutation frequency at 5'Sμ. Similarly, somatic hypermutation is almost negligible at the JH4 intron in AIDS38A/S38AMSH2-/- mouse B cells, and, consistent with this, NP-specific affinity maturation in AIDS38A/S38AMSH2-/- mice is not significantly elevated in response to NP-CGG immunization. Surprisingly, AIDS38A/S38AUNG-/- mouse B cells also cannot complete CSR or affinity maturation despite accumulating significant mutations in 5'Sμ as well as the JH4 intron. These data identify a novel role for phosphorylation of AID at serine 38 in mismatch repair-dependent CSR and affinity maturation.
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Affiliation(s)
- Jee Eun Choi
- The City College of New York, The City University of New York, New York, NY 10031; and
| | - Allysia J Matthews
- The City College of New York, The City University of New York, New York, NY 10031; and
| | - Genesis Michel
- The City College of New York, The City University of New York, New York, NY 10031; and
| | - Bao Q Vuong
- The Graduate Center, The City University of New York, New York, NY 10016
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19
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Protein kinase A inhibits tumor mutator APOBEC3B through phosphorylation. Sci Rep 2019; 9:8307. [PMID: 31165764 PMCID: PMC6549188 DOI: 10.1038/s41598-019-44407-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 05/14/2019] [Indexed: 12/26/2022] Open
Abstract
APOBEC3B cytidine deaminase (A3B) catalyzes cytosine into uracil in single-strand DNA and induces C-to-T mutations in genomic DNA of various types of tumors. Accumulation of APOBEC signature mutations is correlated with a worse prognosis for patients with breast cancer or multiple myeloma, suggesting that A3B activity might be a cause of the unfavorable DNA mutations and clonal evolution in these tumors. Phosphorylation of conserved threonine residues of other cytidine deaminases, activation induced deaminase (AID) and APOBEC3G, inhibits their activity. Here we show that protein kinase A (PKA) physically binds to A3B and phosphorylates Thr214. In vitro deaminase assays and foreign DNA editing assays in cells confirm that phosphomimetic A3B mutants, T214D and T214E, completely lose deaminase activity. Molecular dynamics simulation of A3B phosphorylation reveals that Thr214 phosphorylation disrupts binding between the phospho-A3B catalytic core and ssDNA. These mutants still inhibit retroviral infectivity at least partially, and also retain full anti-retrotransposition activity. These results imply that PKA-mediated phosphorylation inhibits A3B mutagenic activity without destructing its innate immune functions. Therefore, PKA activation could reduce further accumulation of mutations in A3B overexpressing tumors.
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20
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Bansal M, He J, Peyton M, Kustagi M, Iyer A, Comb M, White M, Minna JD, Califano A. Elucidating synergistic dependencies in lung adenocarcinoma by proteome-wide signaling-network analysis. PLoS One 2019; 14:e0208646. [PMID: 30615629 PMCID: PMC6322741 DOI: 10.1371/journal.pone.0208646] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 11/20/2018] [Indexed: 12/26/2022] Open
Abstract
To understand drug combination effect, it is necessary to decipher the interactions between drug targets-many of which are signaling molecules. Previously, such signaling pathway models are largely based on the compilation of literature data from heterogeneous cellular contexts. Indeed, de novo reconstruction of signaling interactions from large-scale molecular profiling is still lagging, compared to similar efforts in transcriptional and protein-protein interaction networks. To address this challenge, we introduce a novel algorithm for the systematic inference of protein kinase pathways, and applied it to published mass spectrometry-based phosphotyrosine profile data from 250 lung adenocarcinoma (LUAD) samples. The resulting network includes 43 TKs and 415 inferred, LUAD-specific substrates, which were validated at >60% accuracy by SILAC assays, including "novel' substrates of the EGFR and c-MET TKs, which play a critical oncogenic role in lung cancer. This systematic, data-driven model supported drug response prediction on an individual sample basis, including accurate prediction and validation of synergistic EGFR and c-MET inhibitor activity in cells lacking mutations in either gene, thus contributing to current precision oncology efforts.
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Affiliation(s)
- Mukesh Bansal
- Psychogenics Inc., Paramus, New Jersey, United States of America
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America
| | - Jing He
- Department of Systems Biology, Columbia University, New York, NY, United States of America
- Center for Computational Biology and Bioinformatics (C2B2), Columbia University, New York, NY, United States of America
- Department of Biomedical Informatics (DBMI), Columbia University, New York, NY, United States of America
| | - Michael Peyton
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Manjunath Kustagi
- Department of Systems Biology, Columbia University, New York, NY, United States of America
| | - Archana Iyer
- Department of Systems Biology, Columbia University, New York, NY, United States of America
| | - Michael Comb
- Cell Signaling Technology, 3 Trask Lane, Danvers, MA, United States of America
| | - Michael White
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - John D. Minna
- Hamon Center for Therapeutic Oncology Research, Simmons Comprehensive Cancer Center, Departments of Pharmacology, and Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Andrea Califano
- Department of Systems Biology, Columbia University, New York, NY, United States of America
- Center for Computational Biology and Bioinformatics (C2B2), Columbia University, New York, NY, United States of America
- Department of Biomedical Informatics (DBMI), Columbia University, New York, NY, United States of America
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, United States of America
- Institute for Cancer Genetics, Columbia University, New York, NY, United States of America
- Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, United States of America
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21
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Nicolas L, Cols M, Choi JE, Chaudhuri J, Vuong B. Generating and repairing genetically programmed DNA breaks during immunoglobulin class switch recombination. F1000Res 2018; 7:458. [PMID: 29744038 PMCID: PMC5904731 DOI: 10.12688/f1000research.13247.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/09/2018] [Indexed: 01/03/2023] Open
Abstract
Adaptive immune responses require the generation of a diverse repertoire of immunoglobulins (Igs) that can recognize and neutralize a seemingly infinite number of antigens. V(D)J recombination creates the primary Ig repertoire, which subsequently is modified by somatic hypermutation (SHM) and class switch recombination (CSR). SHM promotes Ig affinity maturation whereas CSR alters the effector function of the Ig. Both SHM and CSR require activation-induced cytidine deaminase (AID) to produce dU:dG mismatches in the Ig locus that are transformed into untemplated mutations in variable coding segments during SHM or DNA double-strand breaks (DSBs) in switch regions during CSR. Within the Ig locus, DNA repair pathways are diverted from their canonical role in maintaining genomic integrity to permit AID-directed mutation and deletion of gene coding segments. Recently identified proteins, genes, and regulatory networks have provided new insights into the temporally and spatially coordinated molecular interactions that control the formation and repair of DSBs within the Ig locus. Unravelling the genetic program that allows B cells to selectively alter the Ig coding regions while protecting non-Ig genes from DNA damage advances our understanding of the molecular processes that maintain genomic integrity as well as humoral immunity.
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Affiliation(s)
- Laura Nicolas
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Montserrat Cols
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Jee Eun Choi
- Department of Biology, The City College of New York and The Graduate Center of The City University of New York, New York, NY, USA
| | - Jayanta Chaudhuri
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Bao Vuong
- Department of Biology, The City College of New York and The Graduate Center of The City University of New York, New York, NY, USA
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22
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Tepper S, Jeschke J, Böttcher K, Schmidt A, Davari K, Müller P, Kremmer E, Hemmerich P, Pfeil I, Jungnickel B. PARP activation promotes nuclear AID accumulation in lymphoma cells. Oncotarget 2017; 7:13197-208. [PMID: 26921193 PMCID: PMC4914351 DOI: 10.18632/oncotarget.7603] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 01/12/2016] [Indexed: 12/20/2022] Open
Abstract
Activation-induced cytidine deaminase (AID) initiates immunoglobulin diversification in germinal center B cells by targeted introduction of DNA damage. As aberrant nuclear AID action contributes to the generation of B cell lymphoma, the protein's activity is tightly regulated, e.g. by nuclear/cytoplasmic shuttling and nuclear degradation. In the present study, we asked whether DNA damage may affect regulation of the AID protein. We show that exogenous DNA damage that mainly activates base excision repair leads to prevention of proteasomal degradation of AID and hence its nuclear accumulation. Inhibitor as well as knockout studies indicate that activation of poly (ADP-ribose) polymerase (PARP) by DNA damaging agents promotes both phenomena. These findings suggest that PARP inhibitors influence DNA damage dependent AID regulation, with interesting implications for the regulation of AID function and chemotherapy of lymphoma.
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Affiliation(s)
- Sandra Tepper
- Department of Cell Biology, Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine, Friedrich-Schiller University, 07745 Jena, Germany
| | - Julia Jeschke
- Department of Cell Biology, Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine, Friedrich-Schiller University, 07745 Jena, Germany.,Institute of Clinical and Molecular Biology, Helmholtz Center Munich, 81377 Munich, Germany
| | - Katrin Böttcher
- Department of Cell Biology, Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine, Friedrich-Schiller University, 07745 Jena, Germany
| | - Angelika Schmidt
- Department of Cell Biology, Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine, Friedrich-Schiller University, 07745 Jena, Germany
| | - Kathrin Davari
- Department of Cell Biology, Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine, Friedrich-Schiller University, 07745 Jena, Germany
| | - Peter Müller
- Department of Cell Biology, Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine, Friedrich-Schiller University, 07745 Jena, Germany
| | - Elisabeth Kremmer
- Institute of Molecular Immunology, Helmholtz Center Munich, 81377 Munich, Germany
| | - Peter Hemmerich
- Imaging Facility, Leibniz- Institute on Aging - Fritz Lipmann Institute, 07745 Jena, Germany
| | - Ines Pfeil
- Institute of Clinical and Molecular Biology, Helmholtz Center Munich, 81377 Munich, Germany
| | - Berit Jungnickel
- Department of Cell Biology, Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine, Friedrich-Schiller University, 07745 Jena, Germany.,Institute of Clinical and Molecular Biology, Helmholtz Center Munich, 81377 Munich, Germany
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23
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Mu Y, Zelazowska MA, McBride KM. Phosphorylation promotes activation-induced cytidine deaminase activity at the Myc oncogene. J Exp Med 2017; 214:3543-3552. [PMID: 29122947 PMCID: PMC5716038 DOI: 10.1084/jem.20170468] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 08/16/2017] [Accepted: 09/26/2017] [Indexed: 12/31/2022] Open
Abstract
The molecular mechanisms that regulate AID mutator activity at off-target genes are not well characterized. Mu et al. show AID phosphorylation dynamically controls activity at Myc and other sites. Pharmacological induction of AID phosphorylation leads to increased mutations, double strand breakss and translocations. Activation-induced cytidine deaminase (AID) is a mutator enzyme that targets immunoglobulin (Ig) genes to initiate antibody somatic hypermutation (SHM) and class switch recombination (CSR). Off-target AID association also occurs, which causes oncogenic mutations and chromosome rearrangements. However, AID occupancy does not directly correlate with DNA damage, suggesting that factors beyond AID association contribute to mutation targeting. CSR and SHM are regulated by phosphorylation on AID serine38 (pS38), but the role of pS38 in off-target activity has not been evaluated. We determined that lithium, a clinically used therapeutic, induced high AID pS38 levels. Using lithium and an AID-S38 phospho mutant, we compared the role of pS38 in AID activity at the Ig switch region and off-target Myc gene. We found that deficient pS38 abated AID chromatin association and CSR but not mutation at Myc. Enhanced pS38 elevated Myc translocation and mutation frequency but not CSR or Ig switch region mutation. Thus, AID activity can be differentially targeted by phosphorylation to induce oncogenic lesions.
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Affiliation(s)
- Yunxiang Mu
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, TX
| | - Monika A Zelazowska
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, TX
| | - Kevin M McBride
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, TX
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Choudhary M, Tamrakar A, Singh AK, Jain M, Jaiswal A, Kodgire P. AID Biology: A pathological and clinical perspective. Int Rev Immunol 2017; 37:37-56. [PMID: 28933967 DOI: 10.1080/08830185.2017.1369980] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Activation-induced cytidine deaminase (AID), primarily expressed in activated mature B lymphocytes in germinal centers, is the key factor in adaptive immune response against foreign antigens. AID is responsible for producing high-affinity and high-specificity antibodies against an infectious agent, through the physiological DNA alteration processes of antibody genes by somatic hypermutation (SHM) and class-switch recombination (CSR) and functions by deaminating deoxycytidines (dC) to deoxyuridines (dU), thereby introducing point mutations and double-stranded chromosomal breaks (DSBs). The beneficial physiological role of AID in antibody diversification is outweighed by its detrimental role in the genesis of several chronic immune diseases, under non-physiological conditions. This review offers a comprehensive and better understanding of AID biology and its pathological aspects, as well as addresses the challenges involved in AID-related cancer therapeutics, based on various recent advances and evidence available in the literature till date. In this article, we discuss ways through which our interpretation of AID biology may reflect upon novel clinical insights, which could be successfully translated into designing clinical trials and improving patient prognosis and disease management.
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Affiliation(s)
- Meenal Choudhary
- a Centre for Biosciences and Biomedical Engineering , Indian Institute of Technology Indore , Simrol , Indore , Madhya Pradesh , India
| | - Anubhav Tamrakar
- a Centre for Biosciences and Biomedical Engineering , Indian Institute of Technology Indore , Simrol , Indore , Madhya Pradesh , India
| | - Amit Kumar Singh
- a Centre for Biosciences and Biomedical Engineering , Indian Institute of Technology Indore , Simrol , Indore , Madhya Pradesh , India
| | - Monika Jain
- a Centre for Biosciences and Biomedical Engineering , Indian Institute of Technology Indore , Simrol , Indore , Madhya Pradesh , India
| | - Ankit Jaiswal
- a Centre for Biosciences and Biomedical Engineering , Indian Institute of Technology Indore , Simrol , Indore , Madhya Pradesh , India
| | - Prashant Kodgire
- a Centre for Biosciences and Biomedical Engineering , Indian Institute of Technology Indore , Simrol , Indore , Madhya Pradesh , India
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25
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Budzko L, Jackowiak P, Kamel K, Sarzynska J, Bujnicki JM, Figlerowicz M. Mutations in human AID differentially affect its ability to deaminate cytidine and 5-methylcytidine in ssDNA substrates in vitro. Sci Rep 2017. [PMID: 28634398 PMCID: PMC5478644 DOI: 10.1038/s41598-017-03936-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Activation-induced cytidine deaminase (AID) is known for its established role in antibody production. AID induces the diversification of antibodies by deaminating deoxycytidine (C) within immunoglobulin genes. The capacity of AID to deaminate 5-methyldeoxycytidine (5 mC) and/or 5-hydroxymethyldeoxycytidine (5 hmC), and consequently AID involvement in active DNA demethylation, is not fully resolved. For instance, structural determinants of AID activity on different substrates remain to be identified. To better understand the latter issue, we tested how mutations in human AID (hAID) influence its ability to deaminate C, 5 mC, and 5 hmC in vitro. We showed that each of the selected mutations differentially affects hAID’s ability to deaminate C and 5 mC. At the same time, we did not observe hAID activity on 5 hmC. Surprisingly, we found that the N51A hAID mutant, with no detectable activity on C, efficiently deaminated 5 mC, which may suggest different requirements for C and 5 mC deamination. Homology modeling and molecular dynamics simulations revealed that the pattern of enzyme-substrate recognition is one of the important factors determining enzyme activity on C and 5 mC. Consequently, we have proposed mechanisms that explain why wild type hAID more efficiently deaminates C than 5 mC in vitro and why 5 hmC is not deaminated.
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Affiliation(s)
- Lucyna Budzko
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznan, Poland
| | - Paulina Jackowiak
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznan, Poland
| | - Karol Kamel
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznan, Poland
| | - Joanna Sarzynska
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznan, Poland
| | - Janusz M Bujnicki
- Laboratory of Bioinformatics and Protein Engineering, International Institute of Molecular and Cell Biology in Warsaw, Trojdena 4, 02-109, Warsaw, Poland.,Laboratory of Bioinformatics, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614, Poznan, Poland
| | - Marek Figlerowicz
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704, Poznan, Poland. .,Institute of Computing Science, Poznan University of Technology, Piotrowo 3A, 60-965, Poznan, Poland.
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26
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Yan Q, Ahn SH, Medie FM, Sharma-Kuinkel BK, Park LP, Scott WK, Deshmukh H, Tsalik EL, Cyr DD, Woods CW, Yu CHA, Adams C, Qi R, Hansen B, Fowler VG. Candidate genes on murine chromosome 8 are associated with susceptibility to Staphylococcus aureus infection in mice and are involved with Staphylococcus aureus septicemia in humans. PLoS One 2017; 12:e0179033. [PMID: 28594911 PMCID: PMC5464679 DOI: 10.1371/journal.pone.0179033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 05/23/2017] [Indexed: 02/06/2023] Open
Abstract
We previously showed that chromosome 8 of A/J mice was associated with susceptibility to S. aureus infection. However, the specific genes responsible for this susceptibility are unknown. Chromosome substitution strain 8 (CSS8) mice, which have chromosome 8 from A/J but an otherwise C57BL/6J genome, were used to identify the genetic determinants of susceptibility to S. aureus on chromosome 8. Quantitative trait loci (QTL) mapping of S. aureus-infected N2 backcross mice (F1 [C8A] × C57BL/6J) identified a locus 83180780–88103009 (GRCm38/mm10) on A/J chromosome 8 that was linked to S. aureus susceptibility. All genes on the QTL (n~ 102) were further analyzed by three different strategies: 1) different expression in susceptible (A/J) and resistant (C57BL/6J) mice only in response to S. aureus, 2) consistently different expression in both uninfected and infected states between the two strains, and 3) damaging non-synonymous SNPs in either strain. Eleven candidate genes from the QTL region were significantly differently expressed in patients with S. aureus infection vs healthy human subjects. Four of these 11 genes also exhibited significantly different expression in S. aureus-challenged human neutrophils: Ier2, Crif1, Cd97 and Lyl1. CD97 ligand binding was evaluated within peritoneal neutrophils from A/J and C57BL/6J. CD97 from A/J had stronger CD55 but weaker integrin α5β1 ligand binding as compared with C57BL/6J. Because CD55/CD97 binding regulates immune cell activation and cytokine production, and integrin α5β1 is a membrane receptor for fibronectin, which is also bound by S. aureus, strain-specific differences could contribute to susceptibility to S. aureus. Down-regulation of Crif1 with siRNA was associated with increased host cell apoptosis among both naïve and S. aureus-infected bone marrow-derived macrophages. Specific genes in A/J chromosome 8, including Cd97 and Crif1, may play important roles in host defense against S. aureus.
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Affiliation(s)
- Qin Yan
- Division of Infectious Diseases & International Health, Department of Medicine, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Sun Hee Ahn
- Department of Biochemistry School of Dentistry, Chonnam National University, Bukgu, Gwangju, Korea
| | - Felix Mba Medie
- Division of Infectious Diseases & International Health, Department of Medicine, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Batu K. Sharma-Kuinkel
- Division of Infectious Diseases & International Health, Department of Medicine, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Lawrence P. Park
- Duke Global Health Institute, Duke University, Durham, North Carolina, United States of America
| | - William K. Scott
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami, Miami, Florida, United States of America
| | - Hitesh Deshmukh
- Department of Pediatrics, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Ephraim L. Tsalik
- Division of Infectious Diseases & International Health, Department of Medicine, Duke University School of Medicine, Durham, North Carolina, United States of America
- Emergency Medicine Service, Durham Veteran’s Affairs Medical Center, Durham, North Carolina, United States of America
- Duke Clinical Research Institute, Durham, North Carolina, United States of America
| | - Derek D. Cyr
- Duke Clinical Research Institute, Durham, North Carolina, United States of America
| | - Christopher W. Woods
- Division of Infectious Diseases & International Health, Department of Medicine, Duke University School of Medicine, Durham, North Carolina, United States of America
- Duke Clinical Research Institute, Durham, North Carolina, United States of America
- Section on Infectious Diseases, Durham Veteran’s Affairs Medical Center, Durham, North Carolina, United States of America
| | - Chen-Hsin Albert Yu
- Division of Infectious Diseases & International Health, Department of Medicine, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Carlton Adams
- Division of Infectious Diseases & International Health, Department of Medicine, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Robert Qi
- Division of Infectious Diseases & International Health, Department of Medicine, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Brenda Hansen
- Division of Infectious Diseases & International Health, Department of Medicine, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Vance G. Fowler
- Division of Infectious Diseases & International Health, Department of Medicine, Duke University School of Medicine, Durham, North Carolina, United States of America
- Duke Clinical Research Institute, Durham, North Carolina, United States of America
- * E-mail:
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27
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King JJ, Larijani M. A Novel Regulator of Activation-Induced Cytidine Deaminase/APOBECs in Immunity and Cancer: Schrödinger's CATalytic Pocket. Front Immunol 2017; 8:351. [PMID: 28439266 PMCID: PMC5382155 DOI: 10.3389/fimmu.2017.00351] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 03/10/2017] [Indexed: 12/20/2022] Open
Abstract
Activation-induced cytidine deaminase (AID) and its relative APOBEC3 cytidine deaminases boost immune response by mutating immune or viral genes. Because of their genome-mutating activities, AID/APOBECs are also drivers of tumorigenesis. Due to highly charged surfaces, extensive non-specific protein-protein/nucleic acid interactions, formation of polydisperse oligomers, and general insolubility, structure elucidation of these proteins by X-ray crystallography and NMR has been challenging. Hence, almost all available AID/APOBEC structures are of mutated and/or truncated versions. In 2015, we reported a functional structure for AID using a combined computational-biochemical approach. In so doing, we described a new regulatory mechanism that is a first for human DNA/RNA-editing enzymes. This mechanism involves dynamic closure of the catalytic pocket. Subsequent X-ray and NMR studies confirmed our discovery by showing that other APOBEC3s also close their catalytic pockets. Here, we highlight catalytic pocket closure as an emerging and important regulatory mechanism of AID/APOBEC3s. We focus on three sub-topics: first, we propose that variable pocket closure rates across AID/APOBEC3s underlie differential activity in immunity and cancer and review supporting evidence. Second, we discuss dynamic pocket closure as an ever-present internal regulator, in contrast to other proposed regulatory mechanisms that involve extrinsic binding partners. Third, we compare the merits of classical approaches of X-ray and NMR, with that of emerging computational-biochemical approaches, for structural elucidation specifically for AID/APOBEC3s.
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Affiliation(s)
- Justin J. King
- Immunology and Infectious Diseases Program, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, NL, Canada
| | - Mani Larijani
- Immunology and Infectious Diseases Program, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, NL, Canada
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28
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Common nonmutational NOTCH1 activation in chronic lymphocytic leukemia. Proc Natl Acad Sci U S A 2017; 114:E2911-E2919. [PMID: 28314854 DOI: 10.1073/pnas.1702564114] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Activating mutations of NOTCH1 (a well-known oncogene in T-cell acute lymphoblastic leukemia) are present in ∼4-13% of chronic lymphocytic leukemia (CLL) cases, where they are associated with disease progression and chemorefractoriness. However, the specific role of NOTCH1 in leukemogenesis remains to be established. Here, we report that the active intracellular portion of NOTCH1 (ICN1) is detectable in ∼50% of peripheral blood CLL cases lacking gene mutations. We identify a "NOTCH1 gene-expression signature" in CLL cells, and show that this signature is significantly enriched in primary CLL cases expressing ICN1, independent of NOTCH1 mutation. NOTCH1 target genes include key regulators of B-cell proliferation, survival, and signal transduction. In particular, we show that NOTCH1 transactivates MYC via binding to B-cell-specific regulatory elements, thus implicating this oncogene in CLL development. These results significantly extend the role of NOTCH1 in CLL pathogenesis, and have direct implications for specific therapeutic targeting.
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29
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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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30
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Abbott RK, Thayer M, Labuda J, Silva M, Philbrook P, Cain DW, Kojima H, Hatfield S, Sethumadhavan S, Ohta A, Reinherz EL, Kelsoe G, Sitkovsky M. Germinal Center Hypoxia Potentiates Immunoglobulin Class Switch Recombination. THE JOURNAL OF IMMUNOLOGY 2016; 197:4014-4020. [PMID: 27798169 DOI: 10.4049/jimmunol.1601401] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 09/16/2016] [Indexed: 11/19/2022]
Abstract
Germinal centers (GCs) are anatomic sites where B cells undergo secondary diversification to produce high-affinity, class-switched Abs. We hypothesized that proliferating B cells in GCs create a hypoxic microenvironment that governs their further differentiation. Using molecular markers, we found GCs to be predominantly hypoxic. Compared to normoxia (21% O2), hypoxic culture conditions (1% O2) in vitro accelerated class switching and plasma cell formation and enhanced expression of GL-7 on B and CD4+ T cells. Reversal of GC hypoxia in vivo by breathing 60% O2 during immunization resulted in reduced frequencies of GC B cells, T follicular helper cells, and plasmacytes, as well as lower expression of ICOS on T follicular helper cells. Importantly, this reversal of GC hypoxia decreased Ag-specific serum IgG1 and reduced the frequency of IgG1+ B cells within the Ag-specific GC. Taken together, these observations reveal a critical role for hypoxia in GC B cell differentiation.
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Affiliation(s)
- Robert K Abbott
- New England Inflammation and Tissue Protection Institute, Northeastern University, Boston, MA 02115;
| | - Molly Thayer
- New England Inflammation and Tissue Protection Institute, Northeastern University, Boston, MA 02115
| | - Jasmine Labuda
- New England Inflammation and Tissue Protection Institute, Northeastern University, Boston, MA 02115
| | - Murillo Silva
- New England Inflammation and Tissue Protection Institute, Northeastern University, Boston, MA 02115
| | - Phaethon Philbrook
- New England Inflammation and Tissue Protection Institute, Northeastern University, Boston, MA 02115
| | - Derek W Cain
- Department of Immunology and Human Vaccine Institute, Duke University, Durham, NC 27710
| | - Hidefumi Kojima
- Department of Immunology, Dokkyo Medical University School of Medicine, Tochigi 321-0293, Japan; and
| | - Stephen Hatfield
- New England Inflammation and Tissue Protection Institute, Northeastern University, Boston, MA 02115
| | - Shalini Sethumadhavan
- New England Inflammation and Tissue Protection Institute, Northeastern University, Boston, MA 02115
| | - Akio Ohta
- New England Inflammation and Tissue Protection Institute, Northeastern University, Boston, MA 02115
| | - Ellis L Reinherz
- Laboratory of Immunobiology, Department of Medical Oncology, Dana Farber Cancer Institute and Harvard Medical School, Boston, MA 02115
| | - Garnett Kelsoe
- Department of Immunology and Human Vaccine Institute, Duke University, Durham, NC 27710
| | - Michail Sitkovsky
- New England Inflammation and Tissue Protection Institute, Northeastern University, Boston, MA 02115
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31
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Li J, Hao L, Wu J, Zhang J, Su J. Linarin promotes osteogenic differentiation by activating the BMP-2/RUNX2 pathway via protein kinase A signaling. Int J Mol Med 2016; 37:901-10. [PMID: 26935542 PMCID: PMC4790673 DOI: 10.3892/ijmm.2016.2490] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Accepted: 02/02/2016] [Indexed: 01/24/2023] Open
Abstract
Linarin (LIN), a flavonoid which exerts both anti-inflammatory and antioxidative effects, has been found to promote osteogenic differentiation. However, the molecular mechanism of its effect on osteoblast differentiation was unclear. In the present study, LIN from Flos Chrysanthemi Indici (FCI) was isolated in order to investigate the underlying mechanisms of LIN on MC3T3-E1 cells (a mouse osteoblastic cell line) and the osteoprotective effect of LIN in mice which had undergone an ovariectomy (OVX). The results revealed that LIN enhanced osteoblast proliferation and differentiation in MC3T3-E1 cells dose-dependently, with enhanced alkaline phosphatase (ALP) activity and mineralization of extracellular matrix. LIN upregulated osteogenesis-related gene expression, including that of ALP, runt-related transcription factor 2 (RUNX2), osteocalcin (OCN), bone sialoprotein (BSP), and type I collagen (COL-I). Pretreatment with noggin, a bone morphogenetic protein-2 (BMP-2) antagonist, meant that LIN-induced gene expression levels of COL-1, ALP, OCN, BSP and RUNX2 were significantly reduced, as shown by RT-qPCR. Western blot analysis showed that LIN dose-dependently increased the protein levels of BMP-2 and RUNX2 and enhanced the phosphorylation of SMAD1/5. In addition, LIN dose-dependently upregulated protein kinase A (PKA) expression. H-89 (a PKA inhibitor) partially blocked the LIN-induced protein increase in BMP-2, p-SMAD1/5 and RUNX2. We noted that LIN preserved the trabecular bone microarchitecture of ovariectomized mice in vivo. Moreover, pretreatment with LIN significantly lowered serum levels of ALP and OCN in ovariectomized mice. Our data indicated that LIN induced the osteogenic differentiation and mineralization of MC3T3-E1 osteoblastic cells by activating the BMP-2/RUNX2 pathway through PKA signaling in vitro and protected against OVX-induced bone loss in vivo. The results strongly suggest that LIN is a useful natural alternative for the management of postmenopausal osteoporosis.
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Affiliation(s)
- Jia Li
- Shanghai Engineering Research Center of Tooth Restoration and Regeneration, Department of Prosthodontics, School of Stomatology, Tongji University, Shanghai 200072, P.R. China
| | - Lingyu Hao
- Shanghai Engineering Research Center of Tooth Restoration and Regeneration, Department of Prosthodontics, School of Stomatology, Tongji University, Shanghai 200072, P.R. China
| | - Junhua Wu
- Shanghai Engineering Research Center of Tooth Restoration and Regeneration, Department of Prosthodontics, School of Stomatology, Tongji University, Shanghai 200072, P.R. China
| | - Jiquan Zhang
- Ministry of Education, Engineering Research Center of Modern Preparation Technology of TCM, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, P.R. China
| | - Jiansheng Su
- Shanghai Engineering Research Center of Tooth Restoration and Regeneration, Department of Prosthodontics, School of Stomatology, Tongji University, Shanghai 200072, P.R. China
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32
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Le Q, Maizels N. Cell Cycle Regulates Nuclear Stability of AID and Determines the Cellular Response to AID. PLoS Genet 2015; 11:e1005411. [PMID: 26355458 PMCID: PMC4565580 DOI: 10.1371/journal.pgen.1005411] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 07/02/2015] [Indexed: 12/12/2022] Open
Abstract
AID (Activation Induced Deaminase) deaminates cytosines in DNA to initiate immunoglobulin gene diversification and to reprogram CpG methylation in early development. AID is potentially highly mutagenic, and it causes genomic instability evident as translocations in B cell malignancies. Here we show that AID is cell cycle regulated. By high content screening microscopy, we demonstrate that AID undergoes nuclear degradation more slowly in G1 phase than in S or G2-M phase, and that mutations that affect regulatory phosphorylation or catalytic activity can alter AID stability and abundance. We directly test the role of cell cycle regulation by fusing AID to tags that destabilize nuclear protein outside of G1 or S-G2/M phases. We show that enforced nuclear localization of AID in G1 phase accelerates somatic hypermutation and class switch recombination, and is well-tolerated; while nuclear AID compromises viability in S-G2/M phase cells. We identify AID derivatives that accelerate somatic hypermutation with minimal impact on viability, which will be useful tools for engineering genes and proteins by iterative mutagenesis and selection. Our results further suggest that use of cell cycle tags to regulate nuclear stability may be generally applicable to studying DNA repair and to engineering the genome.
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Affiliation(s)
- Quy Le
- Molecular and Cellular Biology Graduate Program, University of Washington School of Medicine, Seattle, Washington, United States of America
| | - Nancy Maizels
- Molecular and Cellular Biology Graduate Program, University of Washington School of Medicine, Seattle, Washington, United States of America
- Departments of Immunology, Biochemistry and Pathology, University of Washington School of Medicine, Seattle, Washington, United States of America
- * E-mail:
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33
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Frasca D, Diaz A, Romero M, Ferracci F, Blomberg BB. MicroRNAs miR-155 and miR-16 Decrease AID and E47 in B Cells from Elderly Individuals. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2015; 195. [PMID: 26223652 PMCID: PMC4546853 DOI: 10.4049/jimmunol.1500520] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Our research in the past few years has identified B cell-specific biomarkers able to predict optimal Ab responses in both young and elderly individuals. These biomarkers are activation-induced cytidine deaminase (AID), the enzyme of class switch recombination and somatic hypermutation; the transcription factor E47, crucial for AID expression; and the ability to generate optimal memory B cells. Moreover, we have found that the increased proinflammatory status of the elderly, both in sera and intrinsic to B cells, negatively impacts B cell function. We have now investigated whether particular inflammatory microRNAs (miRs) contribute to decreased E47 and AID in aged B cells. Our data indicate that E47 and AID mRNA stability is lower in stimulated B cells from elderly individuals. We measured the expression of two miRs crucial for class switch recombination, miR-155 and miR-16, in human unstimulated B cells from young and elderly individuals with the rationale that increases in these before stimulation would decrease E47/AID upon cell activation. We found these miRs and B cell-intrinsic inflammation upregulated in aged unstimulated B cells and negatively associated with AID in the same B cells after stimulation with CpG. We propose that the downregulation of AID in aged human B cells may occur through binding of miR-155 to the 3'-untranslated regions of AID mRNA and/or binding of miR-16 to the 3'-untranslated regions of E47 mRNA, as well as at the transcriptional level of less E47 for AID. Our results indicate novel molecular pathways leading to reduced B cell function with aging.
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Affiliation(s)
- Daniela Frasca
- Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101
| | - Alain Diaz
- Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101
| | - Maria Romero
- Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101
| | - Franco Ferracci
- Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101
| | - Bonnie B Blomberg
- Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33101
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34
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Parp3 negatively regulates immunoglobulin class switch recombination. PLoS Genet 2015; 11:e1005240. [PMID: 26000965 PMCID: PMC4441492 DOI: 10.1371/journal.pgen.1005240] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 04/26/2015] [Indexed: 12/11/2022] Open
Abstract
To generate highly specific and adapted immune responses, B cells diversify their antibody repertoire through mechanisms involving the generation of programmed DNA damage. Somatic hypermutation (SHM) and class switch recombination (CSR) are initiated by the recruitment of activation-induced cytidine deaminase (AID) to immunoglobulin loci and by the subsequent generation of DNA lesions, which are differentially processed to mutations during SHM or to double-stranded DNA break intermediates during CSR. The latter activate the DNA damage response and mobilize multiple DNA repair factors, including Parp1 and Parp2, to promote DNA repair and long-range recombination. We examined the contribution of Parp3 in CSR and SHM. We find that deficiency in Parp3 results in enhanced CSR, while SHM remains unaffected. Mechanistically, this is due to increased occupancy of AID at the donor (Sμ) switch region. We also find evidence of increased levels of DNA damage at switch region junctions and a bias towards alternative end joining in the absence of Parp3. We propose that Parp3 plays a CSR-specific role by controlling AID levels at switch regions during CSR. During infections, B cells diversify the antibodies they produce by two mechanisms: somatic hypermutation (SHM) and class switch recombination (CSR). SHM mutates the regions encoding the antigen-binding site, generating high-affinity antibodies. CSR allows B cells to switch the class of antibody they produce (from IgM to IgA, IgG or IgE), providing novel effector functions. Together, SHM and CSR establish highly specific and pathogen-adapted antibody responses. SHM and CSR are initiated by the recruitment of the activation-induced cytidine deaminase (AID) enzyme to antibody genes. Once recruited, AID induces DNA lesions that are processed into mutations during SHM or chromosomal DNA breaks during CSR. These breaks activate multiple DNA repair proteins and are resolved by replacing the IgM gene segments by those encoding IgA, IgG or IgE. AID carries a significant oncogenic potential that needs to be controlled to preserve genome integrity. Nevertheless, the underlying mechanisms remain poorly understood. Here we show that Poly(ADP)ribose polymerase 3 (Parp3), an enzyme recently implicated in DNA repair, contributes to antibody diversification by negatively regulating CSR without affecting SHM. We show that Parp3 facilitates the repair of AID-induced DNA damage and controls AID levels on chromatin. We propose that Parp3 protects antibody genes from sustained AID-dependent DNA damage.
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AID expression increased by TNF-α is associated with class switch recombination of Igα gene in cancers. Cell Mol Immunol 2015; 13:484-91. [PMID: 25849121 DOI: 10.1038/cmi.2015.26] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 02/28/2015] [Accepted: 02/28/2015] [Indexed: 12/25/2022] Open
Abstract
Recently, immunoglobulins (Igs) were unexpectedly found to be expressed in epithelial cancers. Immunoglobulin class switching or class switch recombination (CSR) is a natural biological process that alters a B cell's production of antibodies (immunoglobulins) from one class to another. However, the mechanism of CSR of Ig genes in cancer is still unknown. Here, we confirmed by detecting the hallmark of CSR that the Igα gene in cancer underwent CSR. Then we focused on activation-induced cytidine deaminase (AID), a crucial factor for initiating CSR. Further studies using tumor necrosis factor (TNF)-α stimulation and specific inhibitor of NF-κB revealed that TNF-α could increase AID expression through NF-κB signaling. Finally, we demonstrated that AID could co-localize with protein kinase A and bind to the switching (Sα) region of the Igα gene. Overexpression of AID obviously enhanced Igα heavy chain expression and its binding ability to the Sα region. These findings indicated that TNF-α-induced AID expression is involved with CSR in cancer.
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36
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Sala C, Mattiuz G, Pietrobono S, Chicca A, Conticello SG. Splice variants of activation induced deaminase (AID) do not affect the efficiency of class switch recombination in murine CH12F3 cells. PLoS One 2015; 10:e0121719. [PMID: 25803053 PMCID: PMC4372541 DOI: 10.1371/journal.pone.0121719] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 02/18/2015] [Indexed: 12/11/2022] Open
Abstract
Activation Induced Deaminase (AID) triggers the antigen-driven antibody diversification processes through its ability to edit DNA. AID dependent DNA damage is also the cause of genetic alterations often found in mature B cell tumors. A number of splice variants of AID have been identified, for which a role in the modulation of its activity has been hypothesized. We have thus tested two of these splice variants, which we find catalytically inactive, for their ability to modulate the activity of endogenous AID in CH12F3 cells, a murine lymphoma cell line in which Class Switch Recombination (CSR) can be induced. In contrast to full-length AID, neither these splice variants or a catalytically impaired AID mutant affect the efficiency of Class Switch Recombination. Thus, while a role for these splice variants at the RNA level remains possible, it is unlikely that they exert any regulatory effect on the function of AID.
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Affiliation(s)
- Cesare Sala
- Core Research Laboratory—Istituto Toscano Tumori, Firenze, Italy
| | - Giorgio Mattiuz
- Core Research Laboratory—Istituto Toscano Tumori, Firenze, Italy
| | - Silvia Pietrobono
- Core Research Laboratory—Istituto Toscano Tumori, Firenze, Italy
- Department of Medical Biotechnologies, University of Siena, Siena, Italy
| | - Andrea Chicca
- Core Research Laboratory—Istituto Toscano Tumori, Firenze, Italy
| | - Silvestro G. Conticello
- Core Research Laboratory—Istituto Toscano Tumori, Firenze, Italy
- Department of Oncology—Azienda Ospedaliero-Universitaria Careggi, Firenze, Italy
- * E-mail:
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He S, Choi YH, Choi JK, Yeo CY, Chun C, Lee KY. Protein kinase A regulates the osteogenic activity of Osterix. J Cell Biochem 2014; 115:1808-15. [PMID: 24905700 DOI: 10.1002/jcb.24851] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 05/12/2014] [Indexed: 11/09/2022]
Abstract
Osterix belongs to the SP gene family and is a core transcription factor responsible for osteoblast differentiation and bone formation. Activation of protein kinase A (PKA), a serine/threonine kinase, is essential for controlling bone formation and BMP-induced osteoblast differentiation. However, the relationship between Osterix and PKA is still unclear. In this report, we investigated the precise role of the PKA pathway in regulating Osterix during osteoblast differentiation. We found that PKA increased the protein level of Osterix; PKA phosphorylated Osterix, increased protein stability, and enhanced the transcriptional activity of Osterix. These results suggest that Osterix is a novel target of PKA, and PKA modulates osteoblast differentiation partially through the regulation of Osterix.
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Affiliation(s)
- Siyuan He
- College of Pharmacy and Research Institute of Drug Development, Chonnam National University, Gwangju, Republic of Korea
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38
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Loss of Prkar1a leads to Bcl-2 family protein induction and cachexia in mice. Cell Death Differ 2014; 21:1815-24. [PMID: 25012505 DOI: 10.1038/cdd.2014.98] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 06/07/2014] [Accepted: 06/10/2014] [Indexed: 11/08/2022] Open
Abstract
Loss of function mutations in the Prkar1a gene are the cause of most cases of Carney complex disorder. Defects in Prkar1a are thought to cause hyper-activation of PKA signalling, which drives neoplastic transformation, and Prkar1a is therefore considered to be a tumour suppressor. Here we show that loss of Prkar1a in genetically modified mice caused transcriptional activation of several proapoptotic Bcl-2 family members and thereby caused cell death. Interestingly, combined loss of Bim and Prkar1a increased colony formation of fibroblasts in culture and promoted their growth as tumours in immune-deficient mice. Apart from inducing apoptosis, systemic deletion of Prkar1a caused cachexia with muscle loss, macrophage activation and increased lipolysis as well as serum triglyceride levels. Loss of single allele of Prkar1a did not enhance tumour development in a skin cancer model, but surprisingly, when combined with the loss of Bim, caused a significant delay in tumorigenesis and this was associated with upregulation of other BH3-only proteins, PUMA and NOXA. These results show that loss of Prkar1a can only promote tumorigenesis when Prkar1a-mediated apoptosis is somehow countered.
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Matthews AJ, Husain S, Chaudhuri J. Binding of AID to DNA does not correlate with mutator activity. THE JOURNAL OF IMMUNOLOGY 2014; 193:252-7. [PMID: 24879790 DOI: 10.4049/jimmunol.1400433] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The DNA deaminase activation-induced cytidine deaminase (AID) initiates somatic hypermutation (SHM) and class switch recombination (CSR) by deaminating cytidines to uridines at V region (V) genes and switch (S) regions. The mechanism by which AID is recruited to V genes and S region DNA is poorly understood. In this study, we used the CH12 B lymphoma line to demonstrate that, although S regions can efficiently recruit AID and undergo mutations and deletions, AID neither binds to nor mutates the V gene, thus clearly demonstrating intraimmunoglobulin locus specificity. Depletion of the RNA-binding protein polypyrimidine tract binding protein-2, previously shown to promote recruitment of AID to S regions, enables stable association of AID with the V gene. Surprisingly, AID binding to the V gene does not induce SHM. These results unmask a striking lack of correlation between AID binding and its mutator activity, providing evidence for the presence of factors required downstream of AID binding to effect SHM. Furthermore, our findings suggest that S regions are preferred targets for AID and, aided by polypyrimidine tract binding protein-2, act as "sinks" to sequester AID activity from other genomic regions.
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Affiliation(s)
- Allysia J Matthews
- Immunology Program, Memorial Sloan-Kettering Cancer Center, Gerstner Sloan-Kettering Graduate School, New York, NY 10065; andImmunology and Microbial Pathogenesis Program, Weill-Cornell Medical School, New York, NY 10065
| | - Solomon Husain
- Immunology Program, Memorial Sloan-Kettering Cancer Center, Gerstner Sloan-Kettering Graduate School, New York, NY 10065; andImmunology and Microbial Pathogenesis Program, Weill-Cornell Medical School, New York, NY 10065
| | - Jayanta Chaudhuri
- Immunology Program, Memorial Sloan-Kettering Cancer Center, Gerstner Sloan-Kettering Graduate School, New York, NY 10065; andImmunology and Microbial Pathogenesis Program, Weill-Cornell Medical School, New York, NY 10065
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40
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Shimamoto R, Amano N, Ichisaka T, Watanabe A, Yamanaka S, Okita K. Generation and characterization of induced pluripotent stem cells from Aid-deficient mice. PLoS One 2014; 9:e94735. [PMID: 24718089 PMCID: PMC3981863 DOI: 10.1371/journal.pone.0094735] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 03/18/2014] [Indexed: 12/15/2022] Open
Abstract
It has been shown that DNA demethylation plays a pivotal role in the generation of induced pluripotent stem (iPS) cells. However, the underlying mechanism of this action is still unclear. Previous reports indicated that activation-induced cytidine deaminase (Aid, also known as Aicda) is involved in DNA demethylation in several developmental processes, as well as cell fusion-mediated reprogramming. Based on these reports, we hypothesized that Aid may be involved in the DNA demethylation that occurs during the generation of iPS cells. In this study, we examined the function of Aid in iPS cell generation using Aid knockout (Aid−/−) mice expressing a GFP reporter under the control of a pluripotent stem cell marker, Nanog. By introducing Oct3/4, Sox2, Klf4 and c-Myc, Nanog-GFP-positive iPS cells could be generated from the fibroblasts and primary B cells of Aid−/− mice. Their induction efficiency was similar to that of wild-type (Aid+/+) iPS cells. The Aid−/− iPS cells showed normal proliferation and gave rise to chimeras, indicating their capacity for self-renewal and pluripotency. A comprehensive DNA methylation analysis showed only a few differences between Aid+/+ and Aid−/− iPS cells. These data suggest that Aid does not have crucial functions in DNA demethylation during iPS cell generation.
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Affiliation(s)
- Ren Shimamoto
- Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Naoki Amano
- Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Tomoko Ichisaka
- Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Akira Watanabe
- Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Shinya Yamanaka
- Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
- Gladstone Institute of Cardiovascular Disease, San Francisco, California, United States of America
| | - Keisuke Okita
- Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
- * E-mail:
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Vaidyanathan B, Yen WF, Pucella JN, Chaudhuri J. AIDing Chromatin and Transcription-Coupled Orchestration of Immunoglobulin Class-Switch Recombination. Front Immunol 2014; 5:120. [PMID: 24734031 PMCID: PMC3975107 DOI: 10.3389/fimmu.2014.00120] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 03/07/2014] [Indexed: 12/29/2022] Open
Abstract
Secondary diversification of the antibody repertoire upon antigenic challenge, in the form of immunoglobulin heavy chain (IgH) class-switch recombination (CSR) endows mature, naïve B cells in peripheral lymphoid organs with a limitless ability to mount an optimal humoral immune response, thus expediting pathogen elimination. CSR replaces the default constant (CH) region exons (Cμ) of IgH with any of the downstream CH exons (Cγ, Cε, or Cα), thereby altering effector functions of the antibody molecule. This process depends on, and is orchestrated by, activation-induced deaminase (AID), a DNA cytidine deaminase that acts on single-stranded DNA exposed during transcription of switch (S) region sequences at the IgH locus. DNA lesions thus generated are processed by components of several general DNA repair pathways to drive CSR. Given that AID can instigate DNA lesions and genomic instability, stringent checks are imposed that constrain and restrict its mutagenic potential. In this review, we will discuss how AID expression and substrate specificity and activity is rigorously enforced at the transcriptional, post-transcriptional, post-translational, and epigenetic levels, and how the DNA-damage response is choreographed with precision to permit targeted activity while limiting bystander catastrophe.
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Affiliation(s)
- Bharat Vaidyanathan
- Weill Cornell Graduate School of Medical Sciences , New York, NY , USA ; Immunology Program, Memorial Sloan Kettering Cancer Center, Gerstner Sloan Kettering Graduate School , New York, NY , USA
| | - Wei-Feng Yen
- Weill Cornell Graduate School of Medical Sciences , New York, NY , USA ; Immunology Program, Memorial Sloan Kettering Cancer Center, Gerstner Sloan Kettering Graduate School , New York, NY , USA
| | - Joseph N Pucella
- Immunology Program, Memorial Sloan Kettering Cancer Center, Gerstner Sloan Kettering Graduate School , New York, NY , USA
| | - Jayanta Chaudhuri
- Weill Cornell Graduate School of Medical Sciences , New York, NY , USA ; Immunology Program, Memorial Sloan Kettering Cancer Center, Gerstner Sloan Kettering Graduate School , New York, NY , USA
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42
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Desimmie BA, Delviks-Frankenberrry KA, Burdick RC, Qi D, Izumi T, Pathak VK. Multiple APOBEC3 restriction factors for HIV-1 and one Vif to rule them all. J Mol Biol 2014; 426:1220-45. [PMID: 24189052 PMCID: PMC3943811 DOI: 10.1016/j.jmb.2013.10.033] [Citation(s) in RCA: 158] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 10/25/2013] [Accepted: 10/28/2013] [Indexed: 12/11/2022]
Abstract
Several members of the APOBEC3 family of cellular restriction factors provide intrinsic immunity to the host against viral infection. Specifically, APOBEC3DE, APOBEC3F, APOBEC3G, and APOBEC3H haplotypes II, V, and VII provide protection against HIV-1Δvif through hypermutation of the viral genome, inhibition of reverse transcription, and inhibition of viral DNA integration into the host genome. HIV-1 counteracts APOBEC3 proteins by encoding the viral protein Vif, which contains distinct domains that specifically interact with these APOBEC3 proteins to ensure their proteasomal degradation, allowing virus replication to proceed. Here, we review our current understanding of APOBEC3 structure, editing and non-editing mechanisms of APOBEC3-mediated restriction, Vif-APOBEC3 interactions that trigger APOBEC3 degradation, and the contribution of APOBEC3 proteins to restriction and control of HIV-1 replication in infected patients.
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Affiliation(s)
- Belete A Desimmie
- Viral Mutation Section, HIV Drug Resistance Program, National Cancer Institute at Frederick, Frederick, MD 21702, USA
| | | | - Ryan C Burdick
- Viral Mutation Section, HIV Drug Resistance Program, National Cancer Institute at Frederick, Frederick, MD 21702, USA
| | - DongFei Qi
- Viral Mutation Section, HIV Drug Resistance Program, National Cancer Institute at Frederick, Frederick, MD 21702, USA
| | - Taisuke Izumi
- Viral Mutation Section, HIV Drug Resistance Program, National Cancer Institute at Frederick, Frederick, MD 21702, USA
| | - Vinay K Pathak
- Viral Mutation Section, HIV Drug Resistance Program, National Cancer Institute at Frederick, Frederick, MD 21702, USA.
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43
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Hu Y, Ericsson I, Doseth B, Liabakk NB, Krokan HE, Kavli B. Activation-induced cytidine deaminase (AID) is localized to subnuclear domains enriched in splicing factors. Exp Cell Res 2014; 322:178-92. [DOI: 10.1016/j.yexcr.2014.01.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 01/02/2014] [Accepted: 01/06/2014] [Indexed: 10/25/2022]
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44
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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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Abstract
In this review, I discuss the currently available experimental evidence concerning the molecular interactions of the activation-induced cytidine deaminase (AID) with transcription of its target genes. The basic question that underlies the transcription relationship is how the process of somatic hypermutation of Ig genes can be restricted to their variable (V) regions. This hallmark of SHM assures that high affinity antibodies can be created while the biological functions of their constant (C) region are undisturbed. I present a revised model of AID function in somatic hypermutation (SHM): In a B cell that produces AID protein and undergoes mutation of the V regions of the expressed Ig heavy and light chain genes, only some of the transcription complexes initiating at the active V-region promoters are associated with AID. When AID travels with the elongating RNA polymerase (pol), it attracts proteins that cause the pausing/stalling of pol and termination of transcription, followed by termination of SHM. This differential AID loading model would allow the mutating B cell to continue producing full-length Ig proteins that are required to avoid apoptosis by permitting the cell to assemble functional B cell receptors.
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Affiliation(s)
- Ursula Storb
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois, USA.
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Lam T, Thomas LM, White CA, Li G, Pone EJ, Xu Z, Casali P. Scaffold functions of 14-3-3 adaptors in B cell immunoglobulin class switch DNA recombination. PLoS One 2013; 8:e80414. [PMID: 24282540 PMCID: PMC3840166 DOI: 10.1371/journal.pone.0080414] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Accepted: 10/02/2013] [Indexed: 12/22/2022] Open
Abstract
Class switch DNA recombination (CSR) of the immunoglobulin heavy chain (IgH) locus crucially diversifies antibody biological effector functions. CSR involves the induction of activation-induced cytidine deaminase (AID) expression and AID targeting to switch (S) regions by 14-3-3 adaptors. 14-3-3 adaptors specifically bind to 5'-AGCT-3' repeats, which make up for the core of all IgH locus S regions. They selectively target the upstream and downstream S regions that are set to undergo S-S DNA recombination. We hypothesized that 14-3-3 adaptors function as scaffolds to stabilize CSR enzymatic elements on S regions. Here we demonstrate that all seven 14-3-3β, 14-3-3ε, 14-3-3γ, 14-3-3η, 14-3-3σ, 14-3-3τ and 14-3-3ζ adaptors directly interacted with AID, PKA-Cα (catalytic subunit) and PKA-RIα (regulatory inhibitory subunit) and uracil DNA glycosylase (Ung). 14-3-3 adaptors, however, did not interact with AID C-terminal truncation mutant AIDΔ(180-198) or AIDF193A and AIDL196A point-mutants (which have been shown not to bind to S region DNA and fail to mediate CSR). 14-3-3 adaptors colocalized with AID and replication protein A (RPA) in B cells undergoing CSR. 14-3-3 and AID binding to S region DNA was disrupted by viral protein R (Vpr), an accessory protein of human immunodeficiency virus type-1 (HIV-1), which inhibited CSR without altering AID expression or germline IH-CH transcription. Accordingly, we demonstrated that 14-3-3 directly interact with Vpr, which in turn, also interact with AID, PKA-Cα and Ung. Altogether, our findings suggest that 14-3-3 adaptors play important scaffold functions and nucleate the assembly of multiple CSR factors on S regions. They also show that such assembly can be disrupted by a viral protein, thereby allowing us to hypothesize that small molecule compounds that specifically block 14-3-3 interactions with AID, PKA and/or Ung can be used to inhibit unwanted CSR.
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Affiliation(s)
- Tonika Lam
- Institute for Immunology, School of Medicine and School of Biological Sciences, University of California Irvine, Irvine, California, United States of America
- Department of Microbiology and Immunology, School of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Lisa M. Thomas
- Institute for Immunology, School of Medicine and School of Biological Sciences, University of California Irvine, Irvine, California, United States of America
| | - Clayton A. White
- Institute for Immunology, School of Medicine and School of Biological Sciences, University of California Irvine, Irvine, California, United States of America
| | - Guideng Li
- Institute for Immunology, School of Medicine and School of Biological Sciences, University of California Irvine, Irvine, California, United States of America
| | - Egest J. Pone
- Institute for Immunology, School of Medicine and School of Biological Sciences, University of California Irvine, Irvine, California, United States of America
| | - Zhenming Xu
- Institute for Immunology, School of Medicine and School of Biological Sciences, University of California Irvine, Irvine, California, United States of America
- Department of Microbiology and Immunology, School of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Paolo Casali
- Institute for Immunology, School of Medicine and School of Biological Sciences, University of California Irvine, Irvine, California, United States of America
- Department of Microbiology and Immunology, School of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
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47
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A DNA break- and phosphorylation-dependent positive feedback loop promotes immunoglobulin class-switch recombination. Nat Immunol 2013; 14:1183-1189. [PMID: 24097111 DOI: 10.1038/ni.2732] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 09/04/2013] [Indexed: 12/16/2022]
Abstract
The ability of activation-induced cytidine deaminase (AID) to efficiently mediate class-switch recombination (CSR) is dependent on its phosphorylation at Ser38; however, the trigger that induces AID phosphorylation and the mechanism by which phosphorylated AID drives CSR have not been elucidated. Here we found that phosphorylation of AID at Ser38 was induced by DNA breaks. Conversely, in the absence of AID phosphorylation, DNA breaks were not efficiently generated at switch (S) regions in the immunoglobulin heavy-chain locus (Igh), consistent with a failure of AID to interact with the endonuclease APE1. Additionally, deficiency in the DNA-damage sensor ATM impaired the phosphorylation of AID at Ser38 and the interaction of AID with APE1. Our results identify a positive feedback loop for the amplification of DNA breaks at S regions through the phosphorylation- and ATM-dependent interaction of AID with APE1.
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Ying CY, Dominguez-Sola D, Fabi M, Lorenz IC, Hussein S, Bansal M, Califano A, Pasqualucci L, Basso K, Dalla-Favera R. MEF2B mutations lead to deregulated expression of the oncogene BCL6 in diffuse large B cell lymphoma. Nat Immunol 2013; 14:1084-92. [PMID: 23974956 PMCID: PMC3954820 DOI: 10.1038/ni.2688] [Citation(s) in RCA: 128] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 07/16/2013] [Indexed: 12/15/2022]
Abstract
MEF2B encodes a transcriptional activator and is mutated in ∼11% of diffuse large B cell lymphomas (DLBCLs) and ∼12% of follicular lymphomas (FLs). Here we found that MEF2B directly activated the transcription of the proto-oncogene BCL6 in normal germinal-center (GC) B cells and was required for DLBCL proliferation. Mutation of MEF2B resulted in enhanced transcriptional activity of MEF2B either through disruption of its interaction with the corepressor CABIN1 or by rendering it insensitive to inhibitory signaling events mediated by phosphorylation and sumoylation. Consequently, the transcriptional activity of Bcl-6 was deregulated in DLBCLs with MEF2B mutations. Thus, somatic mutations of MEF2B may contribute to lymphomagenesis by deregulating BCL6 expression, and MEF2B may represent an alternative target for blocking Bcl-6 activity in DLBCLs.
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Affiliation(s)
- Carol Y Ying
- Institute for Cancer Genetics, Columbia University, New York, New York, USA
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CREB-binding protein (CBP) regulates β-adrenoceptor (β-AR)-mediated apoptosis. Cell Death Differ 2013; 20:941-52. [PMID: 23579242 DOI: 10.1038/cdd.2013.29] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Catecholamines regulate the β-adrenoceptor/cyclic AMP-regulated protein kinase A (cAMP/PKA) pathway. Deregulation of this pathway can cause apoptotic cell death and is implicated in a range of human diseases, such as neuronal loss during aging, cardiomyopathy and septic shock. The molecular mechanism of this process is, however, only poorly understood. Here we demonstrate that the β-adrenoceptor/cAMP/PKA pathway triggers apoptosis through the transcriptional induction of the pro-apoptotic BH3-only Bcl-2 family member Bim in tissues such as the thymus and the heart. In these cell types, the catecholamine-mediated apoptosis is abrogated by loss of Bim. Induction of Bim is driven by the transcriptional co-activator CBP (CREB-binding protein) together with the proto-oncogene c-Myc. Association of CBP with c-Myc leads to altered histone acetylation and methylation pattern at the Bim promoter site. Our findings have implications for understanding pathophysiology associated with a deregulated neuroendocrine system and for developing novel therapeutic strategies for these diseases.
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Sun J, Rothschild G, Pefanis E, Basu U. Transcriptional stalling in B-lymphocytes: a mechanism for antibody diversification and maintenance of genomic integrity. Transcription 2013; 4:127-35. [PMID: 23584095 PMCID: PMC4042586 DOI: 10.4161/trns.24556] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
B cells utilize three DNA alteration strategies-V(D)J recombination, somatic hypermutation (SHM) and class switch recombination (CSR)-to somatically mutate their genome, thereby expressing a plethora of antibodies tailor-made against the innumerable antigens they encounter while in circulation. Of these three events, the single-strand DNA cytidine deaminase, Activation Induced cytidine Deaminase (AID), is responsible for SHM and CSR. Recent advances, discussed in this review article, point toward various components of RNA polymerase II "stalling" machinery as regulators of AID activity during antibody diversification and maintenance of B cell genome integrity.
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Affiliation(s)
- Jianbo Sun
- Department of Microbiology and Immunology; College of Physicians and Surgeons; Columbia University; New York, NY USA
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