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Balint E, Unk I. For the Better or for the Worse? The Effect of Manganese on the Activity of Eukaryotic DNA Polymerases. Int J Mol Sci 2023; 25:363. [PMID: 38203535 PMCID: PMC10779026 DOI: 10.3390/ijms25010363] [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: 12/08/2023] [Revised: 12/22/2023] [Accepted: 12/24/2023] [Indexed: 01/12/2024] Open
Abstract
DNA polymerases constitute a versatile group of enzymes that not only perform the essential task of genome duplication but also participate in various genome maintenance pathways, such as base and nucleotide excision repair, non-homologous end-joining, homologous recombination, and translesion synthesis. Polymerases catalyze DNA synthesis via the stepwise addition of deoxynucleoside monophosphates to the 3' primer end in a partially double-stranded DNA. They require divalent metal cations coordinated by active site residues of the polymerase. Mg2+ is considered the likely physiological activator because of its high cellular concentration and ability to activate DNA polymerases universally. Mn2+ can also activate the known DNA polymerases, but in most cases, it causes a significant decrease in fidelity and/or processivity. Hence, Mn2+ has been considered mutagenic and irrelevant during normal cellular function. Intriguingly, a growing body of evidence indicates that Mn2+ can positively influence some DNA polymerases by conferring translesion synthesis activity or altering the substrate specificity. Here, we review the relevant literature focusing on the impact of Mn2+ on the biochemical activity of a selected set of polymerases, namely, Polβ, Polλ, and Polµ, of the X family, as well as Polι and Polη of the Y family of polymerases, where congruous data implicate the physiological relevance of Mn2+ in the cellular function of these enzymes.
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Affiliation(s)
| | - Ildiko Unk
- Institute of Genetics, HUN-REN Biological Research Centre Szeged, H-6726 Szeged, Hungary;
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2
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Lerner LK, Bonte D, Le Guillou M, Mohammad MM, Kasraian Z, Sarasin A, Despras E, Aoufouchi S. Expression of Constitutive Fusion of Ubiquitin to PCNA Restores the Level of Immunoglobulin A/T Mutations During Somatic Hypermutation in the Ramos Cell Line. Front Immunol 2022; 13:871766. [PMID: 35432321 PMCID: PMC9010874 DOI: 10.3389/fimmu.2022.871766] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 03/11/2022] [Indexed: 12/05/2022] Open
Abstract
Somatic hypermutation (SHM) of immunoglobulin (Ig) genes is a B cell specific process required for the generation of specific and high affinity antibodies during the maturation of the immune response against foreign antigens. This process depends on the activity of both activation-induced cytidine deaminase (AID) and several DNA repair factors. AID-dependent SHM creates the full spectrum of mutations in Ig variable (V) regions equally distributed at G/C and A/T bases. In most mammalian cells, deamination of deoxycytidine into uracil during S phase induces targeted G/C mutagenesis using either direct replication of uracils or TLS mediated bypass, however only the machinery of activated B lymphocytes can generate A/T mutagenesis around AID-created uracils. The molecular mechanism behind the latter remains incompletely understood to date. However, the lack of a cellular model that reproduces both G/C and A/T mutation spectra constitutes the major hurdle to elucidating it. The few available B cell lines used thus far to study Ig SHM indeed undergo mainly G/C mutations, that make them inappropriate or of limited use. In this report, we show that in the Ramos cell line that undergoes constitutive G/C-biased SHM in culture, the low rate of A/T mutations is due to an imbalance in the ubiquitination/deubiquitination reaction of PCNA, with the deubiquitination reaction being predominant. The inhibition of the deubiquitinase complex USP1-UAF1 or the expression of constitutive fusion of ubiquitin to PCNA provides the missing clue required for DNA polymerase η recruitment and thereafter the introduction of A/T base pair (bp) mutations during the process of IgV gene diversification. This study reports the establishment of the first modified human B cell line that recapitulates the mechanism of SHM of Ig genes in vitro.
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Affiliation(s)
- Leticia K. Lerner
- Centre National de la Recherche Scientifique UMR 9019, B Cell and Genome Plasticity Team, Villejuif, France
- Gustave Roussy, Villejuif, France
- Université Paris-Saclay, Orsay, France
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Dorine Bonte
- Centre National de la Recherche Scientifique UMR 9019, B Cell and Genome Plasticity Team, Villejuif, France
- Gustave Roussy, Villejuif, France
- Université Paris-Saclay, Orsay, France
| | - Morwenna Le Guillou
- Centre National de la Recherche Scientifique UMR 9019, B Cell and Genome Plasticity Team, Villejuif, France
- Gustave Roussy, Villejuif, France
- Université Paris-Saclay, Orsay, France
| | - Mahwish Mian Mohammad
- Centre National de la Recherche Scientifique UMR 9019, B Cell and Genome Plasticity Team, Villejuif, France
- Gustave Roussy, Villejuif, France
- Université Paris-Saclay, Orsay, France
- Sorbonne Université, Paris, France
| | - Zeinab Kasraian
- Centre National de la Recherche Scientifique UMR 9019, B Cell and Genome Plasticity Team, Villejuif, France
- Gustave Roussy, Villejuif, France
- Université Paris-Saclay, Orsay, France
| | - Alain Sarasin
- Centre National de la Recherche Scientifique UMR 9019, B Cell and Genome Plasticity Team, Villejuif, France
- Gustave Roussy, Villejuif, France
- Université Paris-Saclay, Orsay, France
| | - Emmanuelle Despras
- Centre National de la Recherche Scientifique UMR 9019, B Cell and Genome Plasticity Team, Villejuif, France
- Gustave Roussy, Villejuif, France
- Université Paris-Saclay, Orsay, France
| | - Said Aoufouchi
- Centre National de la Recherche Scientifique UMR 9019, B Cell and Genome Plasticity Team, Villejuif, France
- Gustave Roussy, Villejuif, France
- Université Paris-Saclay, Orsay, France
- Sorbonne Université, Paris, France
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3
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Stalling of Eukaryotic Translesion DNA Polymerases at DNA-Protein Cross-Links. Genes (Basel) 2022; 13:genes13020166. [PMID: 35205211 PMCID: PMC8872012 DOI: 10.3390/genes13020166] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 01/15/2022] [Accepted: 01/16/2022] [Indexed: 02/05/2023] Open
Abstract
DNA-protein cross-links (DPCs) are extremely bulky adducts that interfere with replication. In human cells, they are processed by SPRTN, a protease activated by DNA polymerases stuck at DPCs. We have recently proposed the mechanism of the interaction of DNA polymerases with DPCs, involving a clash of protein surfaces followed by the distortion of the cross-linked protein. Here, we used a model DPC, located in the single-stranded template, the template strand of double-stranded DNA, or the displaced strand, to study the eukaryotic translesion DNA polymerases ζ (POLζ), ι (POLι) and η (POLη). POLι demonstrated poor synthesis on the DPC-containing substrates. POLζ and POLη paused at sites dictated by the footprints of the polymerase and the cross-linked protein. Beyond that, POLζ was able to elongate the primer to the cross-link site when a DPC was in the template. Surprisingly, POLη was not only able to reach the cross-link site but also incorporated 1–2 nucleotides past it, which makes POLη the most efficient DNA polymerase on DPC-containing substrates. However, a DPC in the displaced strand was an insurmountable obstacle for all polymerases, which stalled several nucleotides before the cross-link site. Overall, the behavior of translesion polymerases agrees with the model of protein clash and distortion described above.
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4
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McIntyre J. Polymerase iota - an odd sibling among Y family polymerases. DNA Repair (Amst) 2019; 86:102753. [PMID: 31805501 DOI: 10.1016/j.dnarep.2019.102753] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 11/18/2019] [Accepted: 11/19/2019] [Indexed: 12/14/2022]
Abstract
It has been two decades since the discovery of the most mutagenic human DNA polymerase, polymerase iota (Polι). Since then, the biochemical activity of this translesion synthesis (TLS) enzyme has been extensively explored, mostly through in vitro experiments, with some insight into its cellular activity. Polι is one of four members of the Y-family of polymerases, which are the best characterized DNA damage-tolerant polymerases involved in TLS. Polι shares some common Y-family features, including low catalytic efficiency and processivity, high infidelity, the ability to bypass some DNA lesions, and a deficiency in 3'→5' exonucleolytic proofreading. However, Polι exhibits numerous properties unique among the Y-family enzymes. Polι has an unusual catalytic pocket structure and prefers Hoogsteen over Watson-Crick pairing, and its replication fidelity strongly depends on the template; further, it prefers Mn2+ ions rather than Mg2+ as catalytic activators. In addition to its polymerase activity, Polι possesses also 5'-deoxyribose phosphate (dRP) lyase activity, and its ability to participate in base excision repair has been shown. As a highly error-prone polymerase, its regulation is crucial and mostly involves posttranslational modifications and protein-protein interactions. The upregulation and downregulation of Polι are correlated with different types of cancer and suggestions regarding the possible function of this polymerase have emerged from studies of various cancer lines. Nonetheless, after twenty years of research, the biological function of Polι certainly remains unresolved.
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Affiliation(s)
- Justyna McIntyre
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, ul. Pawinskiego 5a, 02-106, Warsaw, Poland.
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5
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Yeap LS, Meng FL. Cis- and trans-factors affecting AID targeting and mutagenic outcomes in antibody diversification. Adv Immunol 2019; 141:51-103. [PMID: 30904133 DOI: 10.1016/bs.ai.2019.01.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Antigen receptor diversification is a hallmark of adaptive immunity which allows specificity of the receptor to particular antigen. B cell receptor (BCR) or its secreted form, antibody, is diversified through antigen-independent and antigen-dependent mechanisms. During B cell development in bone marrow, BCR is diversified via V(D)J recombination mediated by RAG endonuclease. Upon stimulation by antigen, B cell undergo somatic hypermutation (SHM) to allow affinity maturation and class switch recombination (CSR) to change the effector function of the antibody. Both SHM and CSR are initiated by activation-induced cytidine deaminase (AID). Repair of AID-initiated lesions through different DNA repair pathways results in diverse mutagenic outcomes. Here, we focus on discussing cis- and trans-factors that target AID to its substrates and factors that affect different outcomes of AID-initiated lesions. The knowledge of mechanisms that govern AID targeting and outcomes could be harnessed to elicit rare functional antibodies and develop ex vivo antibody diversification approaches with diversifying base editors.
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Affiliation(s)
- Leng-Siew Yeap
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
| | - Fei-Long Meng
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China.
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6
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Sakaguchi N, Maeda K. Germinal Center B-Cell-Associated Nuclear Protein (GANP) Involved in RNA Metabolism for B Cell Maturation. Adv Immunol 2016; 131:135-86. [PMID: 27235683 DOI: 10.1016/bs.ai.2016.02.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Germinal center B-cell-associated nuclear protein (GANP) is upregulated in germinal center B cells against T-cell-dependent antigens in mice and humans. In mice, GANP depletion in B cells impairs antibody affinity maturation. Conversely, its transgenic overexpression augments the generation of high-affinity antigen-specific B cells. GANP associates with AID in the cytoplasm, shepherds AID into the nucleus, and augments its access to the rearranged immunoglobulin (Ig) variable (V) region of the genome in B cells, thereby precipitating the somatic hypermutation of V region genes. GANP is also upregulated in human CD4(+) T cells and is associated with APOBEC3G (A3G). GANP interacts with A3G and escorts it to the virion cores to potentiate its antiretroviral activity by inactivating HIV-1 genomic cDNA. Thus, GANP is characterized as a cofactor associated with AID/APOBEC cytidine deaminase family molecules in generating diversity of the IgV region of the genome and genetic alterations of exogenously introduced viral targets. GANP, encoded by human chromosome 21, as well as its mouse equivalent on chromosome 10, contains a region homologous to Saccharomyces Sac3 that was characterized as a component of the transcription/export 2 (TREX-2) complex and was predicted to be involved in RNA export and metabolism in mammalian cells. The metabolism of RNA during its maturation, from the transcription site at the chromosome within the nucleus to the cytoplasmic translation apparatus, needs to be elaborated with regard to acquired and innate immunity. In this review, we summarize the current knowledge on GANP as a component of TREX-2 in mammalian cells.
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Affiliation(s)
- N Sakaguchi
- WPI Immunology Frontier Research Center (IFReC), Osaka University, Suita, Osaka, Japan; Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.
| | - K Maeda
- WPI Immunology Frontier Research Center (IFReC), Osaka University, Suita, Osaka, Japan; Laboratory of Host Defense, Research Institute for Microbial Diseases, Osaka University, Suita, Japan
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7
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Arbel-Eden A, Joseph-Strauss D, Masika H, Printzental O, Rachi E, Simchen G. Trans-Lesion DNA Polymerases May Be Involved in Yeast Meiosis. G3 (BETHESDA, MD.) 2013; 3:633-644. [PMID: 23550131 PMCID: PMC3618350 DOI: 10.1534/g3.113.005603] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Accepted: 02/09/2013] [Indexed: 12/14/2022]
Abstract
Trans-lesion DNA polymerases (TLSPs) enable bypass of DNA lesions during replication and are also induced under stress conditions. Being only weakly dependent on their template during replication, TLSPs introduce mutations into DNA. The low processivity of these enzymes ensures that they fall off their template after a few bases are synthesized and are then replaced by the more accurate replicative polymerase. We find that the three TLSPs of budding yeast Saccharomyces cerevisiae Rev1, PolZeta (Rev3 and Rev7), and Rad30 are induced during meiosis at a time when DNA double-strand breaks (DSBs) are formed and homologous chromosomes recombine. Strains deleted for one or any combination of the three TLSPs undergo normal meiosis. However, in the triple-deletion mutant, there is a reduction in both allelic and ectopic recombination. We suggest that trans-lesion polymerases are involved in the processing of meiotic double-strand breaks that lead to mutations. In support of this notion, we report significant yeast two-hybrid (Y2H) associations in meiosis-arrested cells between the TLSPs and DSB proteins Rev1-Spo11, Rev1-Mei4, and Rev7-Rec114, as well as between Rev1 and Rad30 We suggest that the involvement of TLSPs in processing of meiotic DSBs could be responsible for the considerably higher frequency of mutations reported during meiosis compared with that found in mitotically dividing cells, and therefore may contribute to faster evolutionary divergence than previously assumed.
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Affiliation(s)
- Ayelet Arbel-Eden
- Department of Genetics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
- Department of Medical Laboratory Sciences, Hadassah Academic College, Jerusalem 91010, Israel
| | | | - Hagit Masika
- Department of Genetics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Oxana Printzental
- Department of Genetics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Eléanor Rachi
- Department of Genetics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Giora Simchen
- Department of Genetics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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8
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Machida K. Tumor-initiating stem-like cells and drug resistance: carcinogenesis through Toll-like receptors, environmental factors, and virus. Drug Deliv Transl Res 2013; 3:152-64. [PMID: 25787983 PMCID: PMC10578060 DOI: 10.1007/s13346-012-0115-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Neoplasms contain distinct subpopulations of cells known as tumor-initiating stem-like cells (TICs) that have been identified as key drivers of tumor growth and malignant progression with drug resistance. Stem cells normally proliferate through self-renewing divisions in which the two daughter cells differ markedly in their proliferative potential, with one displaying the differentiation phenotypes and another retaining self-renewing activity. Therefore, understanding the molecular mechanisms of hepatocarcinogenesis will be required for the eventual development of improved therapeutic modalities for treating hepatocellular carcinoma (HCC). Hepatitis C virus (HCV) and hepatitis B virus is a major cause of HCC. Compelling epidemiologic evidence identifies obesity and alcohol as co-morbidity factors that can increase the risk of HCV patients for HCC, especially in alcoholics or obese patients. The mechanisms underlying liver oncogenesis, and how environmental factors contribute to this process, are not yet understood. The HCV-Toll-like receptor 4 (TLR4)-Nanog signaling network is established since alcohol/obesity-associated endotoxemia then activates TLR4 signaling, resulting in the induction of the stem cell marker Nanog expression and liver tumors. Liver TICs are highly sensitized to leptin and exposure of TICs to leptin increases the expression and activity of an intrinsic pluripotency-associated transcriptional network comprised of signal transducer and activator of transcription 3, SOX2, OCT4, and Nanog. Stimulation of the pluripotency network may have significant implications for hepatocellular oncogenesis via genesis and maintenance of TICs. It is important to understand how HCV induces liver cancer through genesis of TICs so that better prevention and treatment can be found. This article reviews the oncogenic pathways to generate TICs.
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Affiliation(s)
- Keigo Machida
- Department of Molecular Microbiology and Immunology, Research Center for ALPD and Cirrhosis, University of Southern California School of Medicine, 503C-HMR, Los Angeles, CA, 90033, USA,
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9
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The biochemistry of activation-induced deaminase and its physiological functions. Semin Immunol 2012; 24:255-63. [DOI: 10.1016/j.smim.2012.05.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 05/18/2012] [Indexed: 01/26/2023]
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10
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Makarova AV, Tarantul VZ, Gening LV. Evolution of DNA polymerase ι structure and function in eukaryotes. BIOCHEMISTRY (MOSCOW) 2011; 73:346-52. [DOI: 10.1134/s0006297908030176] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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11
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Abstract
DNA polymerases (Pols) act as key players in DNA metabolism. These enzymes are the only biological macromolecules able to duplicate the genetic information stored in the DNA and are absolutely required every time this information has to be copied, as during DNA replication or during DNA repair, when lost or damaged DNA sequences have to be replaced with "original" or "correct" copies. In each DNA repair pathway one or more specific Pols are required. A feature of mammalian DNA repair pathways is their redundancy. The failure of one of these pathways can be compensated by another one. However, several DNA lesions require a specific repair pathway for error free repair. In many tumors one or more DNA repair pathways are affected, leading to error prone repair of some kind of lesions by alternatives routes, thus leading to accumulation of mutations and contributing to genomic instability, a common feature of cancer cell. In this chapter, we present the role of each Pol in genome maintenance and highlight the connections between the malfunctioning of these enzymes and cancer progress.
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Affiliation(s)
- Emmanuele Crespan
- Istituto di Genetica Molecolare IGM-CNR, Consiglio Nazionale delle Ricerche, I-27100 Pavia, Italy
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12
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Poltoratsky V, Horton JK, Prasad R, Beard WA, Woodgate R, Wilson SH. Negligible impact of pol iota expression on the alkylation sensitivity of pol beta-deficient mouse fibroblast cells. DNA Repair (Amst) 2008; 7:830-3. [PMID: 18434259 DOI: 10.1016/j.dnarep.2008.02.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2007] [Revised: 02/26/2008] [Accepted: 02/28/2008] [Indexed: 12/16/2022]
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13
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Hida K, Hanes J, Ostermeier M. Directed evolution for drug and nucleic acid delivery. Adv Drug Deliv Rev 2007; 59:1562-78. [PMID: 17933418 DOI: 10.1016/j.addr.2007.08.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2007] [Accepted: 08/20/2007] [Indexed: 12/18/2022]
Abstract
Directed evolution is a term used to describe a variety of related techniques to rapidly evolve peptides and proteins into new forms that exhibit improved properties for specific applications. In this process, molecular biology techniques allow the creation of up to billions of mutants in a single experiment, which are then subjected to high-throughput screening to identify those with enhanced activity. Applications of directed evolution to drug and gene delivery have been recently described, including those that improve the effectiveness of therapeutic enzymes, targeting peptides and antibodies, and the effectiveness or tropism of viral vectors for use in gene therapy. This review first introduces fundamental concepts of directed evolution, and then discusses emerging applications in the field of drug and gene delivery.
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Affiliation(s)
- Kaoru Hida
- Department of Biomedical Engineering, The Johns Hopkins University, 3400 N. Charles St., Baltimore MD, 21218, USA
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Fowler JD, Suo Z. Biochemical, structural, and physiological characterization of terminal deoxynucleotidyl transferase. Chem Rev 2007; 106:2092-110. [PMID: 16771444 DOI: 10.1021/cr040445w] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jason D Fowler
- Department of Biochemistry, The Ohio State University, Columbus, Ohio 43210, USA
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Xu Z, Zan H, Pal Z, Casali P. DNA replication to aid somatic hypermutation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 596:111-27. [PMID: 17338180 PMCID: PMC3140876 DOI: 10.1007/0-387-46530-8_10] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
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16
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Kotani A, Kakazu N, Tsuruyama T, Okazaki IM, Muramatsu M, Kinoshita K, Nagaoka H, Yabe D, Honjo T. Activation-induced cytidine deaminase (AID) promotes B cell lymphomagenesis in Emu-cmyc transgenic mice. Proc Natl Acad Sci U S A 2007; 104:1616-20. [PMID: 17251349 PMCID: PMC1785248 DOI: 10.1073/pnas.0610732104] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Activation-induced cytidine deaminase (AID), which is essential to both class switch recombination and somatic hypermutation of the Ig gene, is expressed in many types of human B cell lymphoma/leukemia. AID is a potent mutator because it is involved in DNA breakage not only of Ig but also of other genes, including proto-oncogenes. Recent studies suggest that AID is required for chromosomal translocation involving cmyc and Ig loci. However, it is unclear whether AID plays other roles in tumorigenesis. We examined the effect of AID deficiency on the generation of surface Ig-positive B cell lymphomas in Emu-cmyc transgenic mice. Almost all lymphomas that developed in AID-deficient transgenic mice were pre-B cell lymphomas, whereas control transgenic mice had predominantly B cell lymphomas, indicating that AID is required for development of B but not pre-B cell lymphomas from cmyc overexpressing tumor progenitors. Thus, AID may play multiple roles in B cell lymphomagenesis.
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Affiliation(s)
- Ai Kotani
- Departments of *Immunology and Genomic Medicine and of
| | - Naoki Kakazu
- Department of Environmental and Preventive Medicine, Shimane University School of Medicine, Enya-Cho 89-1, Izumo City, Shimane 693-8501, Japan; and
| | - Tatsuaki Tsuruyama
- Pathology and Biology of Diseases, Graduate School of Medicine, Kyoto University, Yoshida Konoe-Cho, Sakyo-Ku, Kyoto 606-8501, Japan
| | - Il-mi Okazaki
- Departments of *Immunology and Genomic Medicine and of
| | | | - Kazuo Kinoshita
- Evolutionary Medicine, Shiga Medical Institute, 5-4-30, Moriyama, Shiga 524-8524, Japan
| | | | - Daisuke Yabe
- Departments of *Immunology and Genomic Medicine and of
| | - Tasuku Honjo
- Departments of *Immunology and Genomic Medicine and of
- To whom correspondence should be addressed. E-mail:
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17
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Xiao Z, Ray M, Jiang C, Clark AB, Rogozin IB, Diaz M. Known components of the immunoglobulin A:T mutational machinery are intact in Burkitt lymphoma cell lines with G:C bias. Mol Immunol 2007; 44:2659-66. [PMID: 17240451 PMCID: PMC1868521 DOI: 10.1016/j.molimm.2006.12.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2006] [Accepted: 12/10/2006] [Indexed: 12/14/2022]
Abstract
The basis for mutations at A:T base pairs in immunoglobulin hypermutation and defining how AID interacts with the DNA of the immunoglobulin locus are major aspects of the immunoglobulin mutator mechanism where questions remain unanswered. Here, we examined the pattern of mutations generated in mice deficient in various DNA repair proteins implicated in A:T mutation and found a previously unappreciated bias at G:C base pairs in spectra from mice simultaneously deficient in DNA mismatch repair and uracil DNA glycosylase. This suggests a strand-biased DNA transaction for AID delivery which is then masked by the mechanism that introduces A:T mutations. Additionally, we asked if any of the known components of the A:T mutation machinery underscore the basis for the paucity of A:T mutations in the Burkitt lymphoma cell lines, Ramos and BL2. Ramos and BL2 cells were proficient in MSH2/MSH6-mediated mismatch repair, and express high levels of wild-type, full-length DNA polymerase eta. In addition, Ramos cells have high levels of uracil DNA glycosylase protein and are proficient in base excision repair. These results suggest that Burkitt lymphoma cell lines may be deficient in an unidentified factor that recruits the machinery necessary for A:T mutation or that AID-mediated cytosine deamination in these cells may be processed by conventional base excision repair truncating somatic hypermutation at the G:C phase. Either scenario suggests that cytosine deamination by AID is not enough to trigger A:T mutation, and that additional unidentified factors are required for full spectrum hypermutation in vivo.
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Affiliation(s)
- Zheng Xiao
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, National Institutes of Health, D3-01, 111 TW Alexander Drive, Research Triangle Park NC 27709
| | - Madhumita Ray
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, National Institutes of Health, D3-01, 111 TW Alexander Drive, Research Triangle Park NC 27709
| | - Chuancang Jiang
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, National Institutes of Health, D3-01, 111 TW Alexander Drive, Research Triangle Park NC 27709
| | - Alan B. Clark
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, National Institutes of Health, D3-01, 111 TW Alexander Drive, Research Triangle Park NC 27709
| | - Igor B. Rogozin
- National Center for Biotechnology Information, National Libray of Medicine, National Institutes of Health, Bethesda, MD 20894
| | - Marilyn Diaz
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, National Institutes of Health, D3-01, 111 TW Alexander Drive, Research Triangle Park NC 27709
- * Corresponding author: , Phone Number: 919-541-4740, Fax: 919-541-7593
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Poltoratsky V, Prasad R, Horton JK, Wilson SH. Down-regulation of DNA polymerase beta accompanies somatic hypermutation in human BL2 cell lines. DNA Repair (Amst) 2006; 6:244-53. [PMID: 17127106 PMCID: PMC2121660 DOI: 10.1016/j.dnarep.2006.10.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2006] [Revised: 10/11/2006] [Accepted: 10/12/2006] [Indexed: 01/09/2023]
Abstract
Somatic hypermutation (SHM) is a fundamental process in immunoglobulin gene maturation that results in increased affinity of antibodies toward antigens. In one hypothesis explaining SHM in human B cells, the process is initiated by enzymatic deamination of cytosine to uracil in the immunoglobulin gene V-region and this in turn triggers mutation-prone forms of uracil-DNA base excision repair (BER). Yet, an uncertainty with this model is that BER of uracil-DNA in mammalian cells is generally error-free, wherein DNA polymerase beta (pol beta) conducts gap-filling synthesis by insertion of bases according to Watson-Crick rules. To evaluate this inconsistency, we examined pol beta expression in various SHM proficient human BL2 cell line subclones. We report that expression of pol beta in SHM proficient cell lines was strongly down-regulated. In contrast, in other BL2 subclones, we found that SHM was deficient and that pol beta expression was much higher than in the SHM proficient subclones. We also found that overexpression of recombinant human pol beta in a SHM proficient subclone abrogated its capacity for SHM. These results suggest that down-regulation of the normal BER gap-filling DNA polymerase, pol beta, accompanies induced SHM in BL2 cells. This is consistent with the hypothesis that normal error-free BER must be silenced to make way for an error-prone BER process that may be required during somatic hypermutation.
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Affiliation(s)
| | | | | | - Samuel H. Wilson
- * Corresponding author. Tel.: +1 919 541 3267; fax: +1 919 541 3592. E-mail address: (S.H. Wilson)
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Seki M, Gearhart PJ, Wood RD. DNA polymerases and somatic hypermutation of immunoglobulin genes. EMBO Rep 2006; 6:1143-8. [PMID: 16319960 PMCID: PMC1369213 DOI: 10.1038/sj.embor.7400582] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2005] [Accepted: 10/17/2005] [Indexed: 11/08/2022] Open
Abstract
Somatic hypermutation of immunoglobulin variable genes, which increases antibody diversity, is initiated by the activation-induced cytosine deaminase (AID) protein. The current DNA-deamination model posits that AID deaminates cytosine to uracil in DNA, and that mutations are generated by DNA polymerases during replication or repair of the uracil residue. Mutations could arise as follows: by DNA replicating past the uracil; by removing the uracil with a uracil glycosylase and replicating past the resulting abasic site with a low-fidelity polymerase; or by repairing the uracil and synthesizing a DNA-repair patch downstream using a low-fidelity polymerase. In this review, we summarize the biochemical properties of specialized DNA polymerases in mammalian cells and discuss their participation in the mechanisms of hypermutation. Many recent studies have examined mice deficient in the genes that encode various DNA polymerases, and have shown that DNA polymerase H (POLH) contributes to hypermutation, whereas POLI, POLK and several other enzymes do not have major roles. The low-fidelity enzyme POLQ has been proposed as another candidate polymerase because it can efficiently bypass abasic sites and recent evidence indicates that it might participate in hypermutation.
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Affiliation(s)
- Mineaki Seki
- Suite 2.6, Research Pavilion, Hillman Cancer Center, University of Pittsburgh Cancer Institute, 5117 Centre Avenue, Pittsburgh, Pennsylvania 15213, USA
| | - Patricia J Gearhart
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, Maryland 21224, USA
| | - Richard D Wood
- Suite 2.6, Research Pavilion, Hillman Cancer Center, University of Pittsburgh Cancer Institute, 5117 Centre Avenue, Pittsburgh, Pennsylvania 15213, USA
- Tel: +1 412 623 7766; Fax: +1 412 623 7761; E-mail:
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21
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Pavlov YI, Shcherbakova PV, Rogozin IB. Roles of DNA Polymerases in Replication, Repair, and Recombination in Eukaryotes. INTERNATIONAL REVIEW OF CYTOLOGY 2006; 255:41-132. [PMID: 17178465 DOI: 10.1016/s0074-7696(06)55002-8] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The functioning of the eukaryotic genome depends on efficient and accurate DNA replication and repair. The process of replication is complicated by the ongoing decomposition of DNA and damage of the genome by endogenous and exogenous factors. DNA damage can alter base coding potential resulting in mutations, or block DNA replication, which can lead to double-strand breaks (DSB) and to subsequent chromosome loss. Replication is coordinated with DNA repair systems that operate in cells to remove or tolerate DNA lesions. DNA polymerases can serve as sensors in the cell cycle checkpoint pathways that delay cell division until damaged DNA is repaired and replication is completed. Eukaryotic DNA template-dependent DNA polymerases have different properties adapted to perform an amazingly wide spectrum of DNA transactions. In this review, we discuss the structure, the mechanism, and the evolutionary relationships of DNA polymerases and their possible functions in the replication of intact and damaged chromosomes, DNA damage repair, and recombination.
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Affiliation(s)
- Youri I Pavlov
- Eppley Institute for Research in Cancer and Allied Diseases, Departments of Biochemistry and Molecular Biology, and Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska 68198-6805, USA
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22
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Abstract
Three processes alter genomic sequence and structure at the immunoglobulin genes of B lymphocytes: gene conversion, somatic hypermutation, and class switch recombination. Though the molecular signatures of these processes differ, they occur by a shared pathway which is induced by targeted DNA deamination by a B cell-specific factor, activation induced cytidine deaminase (AID). Ubiquitous factors critical for DNA repair carry out all downstream steps, creating mutations and deletions in genomic DNA. This review focuses on the genetic and biochemical mechanisms of diversification of immunoglobulin genes.
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Affiliation(s)
- Nancy Maizels
- Department of Immunology, University of Washington Medical School, Seattle, Washington 98195-7650, USA.
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23
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Hara T, Kouno J, Nakamura K, Kusaka M, Yamaoka M. Possible role of adaptive mutation in resistance to antiandrogen in prostate cancer cells. Prostate 2005; 65:268-75. [PMID: 16015592 DOI: 10.1002/pros.20282] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Some mutations of androgen receptor (AR) confer resistance to antiandrogen to prostate cancer (PC) cells. Previously we reported that LNCaP-cxD2 cells established from androgen-dependent LNCaP-FGC PC cells as an antiandrogen bicalutamide-resistant subline harbor W741C/L mutation in the AR gene. In this report, we examined one possible mechanism of the resistance. METHODS Change in the gene expression and the protein levels relevant to mutagenesis in LNCaP-FGC cells during bicalutamide-treatment was assessed. The AR sequence of bicalutamide-resistant LNCaP-cxD2 cells was compared with that of parental LNCaP-FGC cells. RESULTS The expression of DNA polymerases (Pol) switched from high-fidelity subset to error-prone subset, and DNA mismatch repair proteins (MMR) were down-regulated. The rate of multiple mutations in the AR gene was higher in LNCaP-cxD2 cells than LNCaP-FGC cells. CONCLUSIONS These results suggest the hypermutational state might occur in LNCaP-FGC cells during bicalutamide-treatment, which might create the W741C/L mutant AR leading to bicalutamide-resistance.
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Affiliation(s)
- Takahito Hara
- Pharmacology Research Laboratories I, Takeda Pharmaceutical Company Limited, 17-85, Jusohonmachi 2-chome, Yodogawa-ku, Osaka, Japan
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24
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Fujimura S, Xing Y, Takeya M, Yamashita Y, Ohshima K, Kuwahara K, Sakaguchi N. Increased expression of germinal center-associated nuclear protein RNA-primase is associated with lymphomagenesis. Cancer Res 2005; 65:5925-34. [PMID: 15994971 DOI: 10.1158/0008-5472.can-04-3259] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Lymphomas arise containing abnormalities of various differentiation stage-specific molecules. In the study reported here, we have shown abnormal up-regulation of germinal center B cell-associated GANP in various human lymphomas including mantle cell, diffuse large B cell, and Hodgkin lymphoma, by immunohistochemical analysis. To study the role of GANP in lymphomagenesis, we generated mutant mice (ganp-Tg) that express the transgenic ganp gene under immunoglobulin enhancer and promoter control. Ganp-Tg mice showed a high incidence of lymphomagenesis (29.5%) after aging with a non-B/non-T cell surface phenotype having slight CD45R/B220 expression and Ig transcripts of rearranged VH-DH-JH IgH loci. Lymphomas generated in ganp-Tg mice displayed similar pathologic characteristics to mouse reticulum cell neoplasm or Hodgkin lymphoma-like lesions. The VH sequences of individual mice showed that the tumors proliferated from a single clone or oligoclones, as is found in human diffuse large B-cell lymphomas and Hodgkin lymphoma. These results suggest that GANP overexpression is a causative factor in the generation of B lymphomas.
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Affiliation(s)
- Satoru Fujimura
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Honjo, Kumamoto, Japan
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Machida K, Cheng KTH, Pavio N, Sung VMH, Lai MMC. Hepatitis C virus E2-CD81 interaction induces hypermutation of the immunoglobulin gene in B cells. J Virol 2005; 79:8079-89. [PMID: 15956553 PMCID: PMC1143751 DOI: 10.1128/jvi.79.13.8079-8089.2005] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Hepatitis C virus (HCV) is one of the leading causes of chronic liver diseases and B-lymphocyte proliferative disorders, including mixed cryoglobulinemia and B-cell lymphoma. It has been suggested that HCV infects human cells through the interaction of its envelope glycoprotein E2 with a tetraspanin molecule CD81, the putative viral receptor. Here, we show that the engagement of B cells by purified E2 induced double-strand DNA breaks specifically in the variable region of immunoglobulin (V(H)) gene locus, leading to hypermutation in the V(H) genes of B cells. Other gene loci were not affected. Preincubation with the anti-CD81 monoclonal antibody blocked this effect. E2-CD81 interaction on B cells triggered the enhanced expression of activation-induced cytidine deaminase (AID) and also stimulated the production of tumor necrosis factor alpha. Knockdown of AID by the specific small interfering RNA blocked the E2-induced double-strand DNA breaks and hypermutation of the V(H) gene. These findings suggest that HCV infection, through E2-CD81 interaction, may modulate host's innate or adaptive immune response by activation of AID and hypermutation of immunoglobulin gene in B cells, leading to HCV-associated B-cell lymphoproliferative diseases.
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Affiliation(s)
- Keigo Machida
- Department of Molecular Microbiology and Immunology, University of Southern California, Keck School of Medicine, 2011 Zonal Ave., Los Angeles, California 90033, USA
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26
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Lucas D, Laín de Lera T, González MA, Ruiz JF, Domínguez O, Casanova JC, Martínez-A C, Blanco L, Bernad A. Polymerase mu is up-regulated during the T cell-dependent immune response and its deficiency alters developmental dynamics of spleen centroblasts. Eur J Immunol 2005; 35:1601-11. [PMID: 15789338 DOI: 10.1002/eji.200526015] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Mammalian DNA polymerase mu (Polmu), preferentially expressed in secondary lymphoid organs, is shown here to be up-regulated in germinal centers after immunization. Alternative splicing appears to be part of Polmu regulation during an immune response. We generated Polmu-deficient mice that are viable and show no anatomical malformation or serious alteration in lymphoid populations, with the exception of an underrepresentation of the B cell compartment. Young and aged homozygous Polmu(-/-) mice generated similar immune responses after immunization with the hapten (4-hydroxy-3-nitrophenyl)acetyl (NP) coupled to chicken gammaglobulin (CGG), compared with their wild-type littermates. Nonetheless, the kinetics of development of the centroblast population showed significant differences. Hypermutation analysis of the rearranged heavy chain intron region in centroblasts isolated from NP-CGG-immunized Polmu(-/-) mice showed a similar quantitative and qualitative somatic mutation spectrum, but a lower representation of heavily mutated clones. These results suggest that although it is not a critical partner, Polmu modulates the in vivo somatic hypermutation process.
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Affiliation(s)
- Daniel Lucas
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/CSIC, Madrid, Spain
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27
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Mayorov VI, Rogozin IB, Adkison LR, Frahm C, Kunkel TA, Pavlov YI. Expression of human AID in yeast induces mutations in context similar to the context of somatic hypermutation at G-C pairs in immunoglobulin genes. BMC Immunol 2005; 6:10. [PMID: 15949042 PMCID: PMC1180437 DOI: 10.1186/1471-2172-6-10] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2005] [Accepted: 06/10/2005] [Indexed: 12/02/2022] Open
Abstract
Background Antibody genes are diversified by somatic hypermutation (SHM), gene conversion and class-switch recombination. All three processes are initiated by the activation-induced deaminase (AID). According to a DNA deamination model of SHM, AID converts cytosine to uracil in DNA sequences. The initial deamination of cytosine leads to mutation and recombination in pathways involving replication, DNA mismatch repair and possibly base excision repair. The DNA sequence context of mutation hotspots at G-C pairs during SHM is DGYW/WRCH (G-C is a hotspot position, R = A/G, Y = T/C, W = A/T, D = A/G/T). Results To investigate the mechanisms of AID-induced mutagenesis in a model system, we studied the genetic consequences of AID expression in yeast. We constructed a yeast vector with an artificially synthesized human AID gene insert using codons common to highly expressed yeast genes. We found that expression of the artificial hAIDSc gene was moderately mutagenic in a wild-type strain and highly mutagenic in an ung1 uracil-DNA glycosylase-deficient strain. A majority of mutations were at G-C pairs. In the ung1 strain, C-G to T-A transitions were found almost exclusively, while a mixture of transitions with 12% transversions was characteristic in the wild-type strain. In the ung1 strain mutations that could have originated from deamination of the transcribed stand were found more frequently. In the wild-type strain, the strand bias was reversed. DGYW/WRCH motifs were preferential sites of mutations. Conclusion The results are consistent with the hypothesis that AID-mediated deamination of DNA is a major cause of mutations at G-C base pairs in immunoglobulin genes during SHM. The sequence contexts of mutations in yeast induced by AID and those of somatic mutations at G-C pairs in immunoglobulin genes are significantly similar. This indicates that the intrinsic substrate specificity of AID itself is a primary determinant of mutational hotspots at G-C base pairs during SHM.
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Affiliation(s)
| | - Igor B Rogozin
- National Center for Biotechnology Information NLM, National Institutes of Health, Bethesda MD 20894, USA
- Institute of Cytology and Genetics SD RAS, Novosibirsk 630090, Russia
| | | | - Christin Frahm
- Eppley Institute for Research in Cancer, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE 68198, USA
| | - Thomas A Kunkel
- Laboratory of Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Youri I Pavlov
- Eppley Institute for Research in Cancer, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE 68198, USA
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE 68198, USA
- Department of Pathology and Microbiology, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE 68198, USA
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28
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Abstract
It is generally believed that in cells undergoing Ig somatic hypermutation, more cell divisions result in more mutations. This is because DNA synthesis and replication is thought to play roles in the known mechanisms-cytidine deamination and subsequent conversion to thymidine, uracil-DNA glycosylase-mediated repair, mismatch repair, and DNA synthesis by error-prone polymerases. In this study, we manipulated the number of cell generations by varying the rate at which cultures of a mouse cell line were replenished with fresh medium. We found that the frequency of mutants does not necessarily increase with the number of cell generations. On the contrary, a greater number of divisions can lead to a lower frequency of mutants, indicating that cell division is not a rate-limiting step in the hypermutation process. Thus, when comparing mutation rates, we suggest that rates are more appropriately expressed as mutations per day than per cell generation.
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Affiliation(s)
- Clifford L Wang
- Department of Microbiology and Immunology, University of California, San Francisco, CA 94143, USA.
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29
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Abstract
A functional immune system is one of the prerequisites for the survival of a species. Humans have one of the most complicated immune systems, with the ability to learn from and adapt to pathogens. At first, a primary repertoire of antibodies is generated, which, upon antigen encounter, will diversify and adapt to produce a highly specific and potent secondary response, part of which is kept in memory to fight off future infections. In this review, the mechanism as well as the specificities of the key protein in the secondary immune response, activation-induced cytidine deaminase (AID), are highlighted, as well as its role in the DNA deamination model of immunoglobulin diversification. The review also highlights aspects of AID's regulation on both the transcriptional as well as post-translational level and its potential molecular mechanism and specificity. Furthermore, it expands outside the involvement of AID in somatic hypermutation, class switching, and gene conversion to discuss the implications of DNA deamination in epigenetic modifications of DNA (as a potential demethylase), the induction of mutations during oncogenesis, and includes an evolutionary comparison to the DNA deaminase family member APOBEC3G, a key protein in human immunodeficiency virus pathogenesis.
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Affiliation(s)
- Svend Petersen-Mahrt
- DNA Editing Laboratory, Cancer Research UK, Clare Hall Laboratories, South Mimms Hert, UK.
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30
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Steele EJ. DNA polymerase-eta as a reverse transcriptase: implications for mechanisms of hypermutation in innate anti-retroviral defences and antibody SHM systems. DNA Repair (Amst) 2004; 3:687-92. [PMID: 15177177 DOI: 10.1016/j.dnarep.2004.03.040] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Kluger Y, Tuck DP, Chang JT, Nakayama Y, Poddar R, Kohya N, Lian Z, Ben Nasr A, Halaban HR, Krause DS, Zhang X, Newburger PE, Weissman SM. Lineage specificity of gene expression patterns. Proc Natl Acad Sci U S A 2004; 101:6508-13. [PMID: 15096607 PMCID: PMC404075 DOI: 10.1073/pnas.0401136101] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The hematopoietic system offers many advantages as a model for understanding general aspects of lineage choice and specification. Using oligonucleotide microarrays, we compared gene expression patterns of multiple purified hematopoietic cell populations, including neutrophils, monocytes, macrophages, resting, centrocytic, and centroblastic B lymphocytes, dendritic cells, and hematopoietic stem cells. Some of these cells were studied under both resting and stimulated conditions. We studied the collective behavior of subsets of genes derived from the Biocarta database of functional pathways, hand-tuned groupings of genes into broad functional categories based on the Gene Ontology database, and the metabolic pathways in the Kyoto Encyclopedia of Genes and Genomes database. Principal component analysis revealed strikingly pervasive differences in relative levels of gene expression among cell lineages that involve most of the subsets examined. These results indicate that many processes in these cells behave differently in different lineages. Much of the variation among lineages was captured by the first few principal components. Principal components biplots were found to provide a convenient visual display of the contributions of the various genes within the subsets in lineage discrimination. Moreover, by applying tree-constructing methodologies borrowed from phylogenetics to the expression data from differentiated cells and stem cells, we reconstructed a tree of relationships that resembled the established hematopoietic program of lineage development. Thus, the mRNA expression data implicitly contained information about developmental relationships among cell types.
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Affiliation(s)
- Yuval Kluger
- Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA
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32
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Kivisaar M. Stationary phase mutagenesis: mechanisms that accelerate adaptation of microbial populations under environmental stress. Environ Microbiol 2004; 5:814-27. [PMID: 14510835 DOI: 10.1046/j.1462-2920.2003.00488.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Microorganisms are exposed to constantly changing environmental conditions. In a growth-restricting environment (e.g. during starvation), mutants arise that are able to take over the population by a process known as stationary phase mutation. Genetic adaptation of a microbial population under environmental stress involves mechanisms that lead to an elevated mutation rate. Under stressful conditions, DNA synthesis may become more erroneous because of the induction of error-prone DNA polymerases, resulting in a situation in which DNA repair systems are unable to cope with increasing amounts of DNA lesions. Transposition may also increase genetic variation. One may ask whether the rate of mutation under stressful conditions is elevated as a result of malfunctioning of systems responsible for accuracy or are there specific mechanisms that regulate the rate of mutations under stress. Evidence for the presence of mutagenic pathways that have probably been evolved to control the mutation rate in a cell will be discussed.
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Affiliation(s)
- Maia Kivisaar
- Department of Genetics, Institute of Molecular and Cell Biology, Tartu University and Estonian Biocentre, 51010 Tartu, Estonia.
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33
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Machida K, Cheng KTN, Sung VMH, Shimodaira S, Lindsay KL, Levine AM, Lai MY, Lai MMC. Hepatitis C virus induces a mutator phenotype: enhanced mutations of immunoglobulin and protooncogenes. Proc Natl Acad Sci U S A 2004; 101:4262-7. [PMID: 14999097 PMCID: PMC384729 DOI: 10.1073/pnas.0303971101] [Citation(s) in RCA: 272] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Hepatitis C virus (HCV) is a nonretroviral oncogenic RNA virus, which is frequently associated with hepatocellular carcinoma (HCC) and B cell lymphoma. We demonstrated here that acute and chronic HCV infection caused a 5- to 10-fold increase in mutation frequency in Ig heavy chain, BCL-6, p53, and beta-catenin genes of in vitro HCV-infected B cell lines and HCV-associated peripheral blood mononuclear cells, lymphomas, and HCCs. The nucleotide-substitution pattern of p53 and beta-catenin was different from that of Ig heavy chain in HCV-infected cells, suggesting two different mechanisms of mutation. In addition, the mutated protooncogenes were amplified in HCV-associated lymphomas and HCCs, but not in lymphomas of nonviral origin or HBV-associated HCC. HCV induced error-prone DNA polymerase zeta, polymerase iota, and activation-induced cytidine deaminase, which together, contributed to the enhancement of mutation frequency, as demonstrated by the RNA interference experiments. These results indicate that HCV induces a mutator phenotype and may transform cells by a hit-and-run mechanism. This finding provides a mechanism of oncogenesis for an RNA virus.
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Affiliation(s)
- Keigo Machida
- Department of Molecular Microbiology and Immunology, University of Southern California Keck School of Medicine, 2011 Zonal Avenue, Los Angeles, CA 90033, USA
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34
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Abstract
Cells have high-fidelity polymerases whose task is to accurately replicate the genome, and low-fidelity polymerases with specialized functions. Although some of these low-fidelity polymerases are exceptional in their ability to replicate damaged DNA and restore the undamaged sequence, they are error prone on undamaged DNA. In fact, these error-prone polymerases are sometimes used in circumstances where the capacity to make errors has a selective advantage. The mutagenic potential of the error-prone polymerases requires that their expression, activity, and access to undamaged DNA templates be regulated. Here we review these specialized polymerases with an emphasis on their biological roles.
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Affiliation(s)
- Alison J Rattray
- Gene Regulation and Chromosome Biology Laboratory, NCI-Frederick, National Cancer Institute, National Institutes of Health, Frederick, Maryland 21702, USA.
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35
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Bardwell PD, Woo CJ, Wei K, Li Z, Martin A, Sack SZ, Parris T, Edelmann W, Scharff MD. Altered somatic hypermutation and reduced class-switch recombination in exonuclease 1-mutant mice. Nat Immunol 2004; 5:224-9. [PMID: 14716311 DOI: 10.1038/ni1031] [Citation(s) in RCA: 195] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2003] [Accepted: 11/11/2003] [Indexed: 11/09/2022]
Abstract
The generation of protective antibodies requires somatic hypermutation (SHM) and class-switch recombination (CSR) of immunoglobulin genes. Here we show that mice mutant for exonuclease 1 (Exo1), which participates in DNA mismatch repair (MMR), have decreased CSR and changes in the characteristics of SHM similar to those previously observed in mice mutant for the MMR protein Msh2. Exo1 is thus the first exonuclease shown to be involved in SHM and CSR. The phenotype of Exo1(-/-) mice and the finding that Exo1 and Mlh1 are physically associated with mutating variable regions support the idea that Exo1 and MMR participate directly in SHM and CSR.
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Affiliation(s)
- Philip D Bardwell
- Department of Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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36
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Kuwahara K, Fujimura S, Takahashi Y, Nakagata N, Takemori T, Aizawa S, Sakaguchi N. Germinal center-associated nuclear protein contributes to affinity maturation of B cell antigen receptor in T cell-dependent responses. Proc Natl Acad Sci U S A 2004; 101:1010-5. [PMID: 14715907 PMCID: PMC327142 DOI: 10.1073/pnas.0307609100] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Acquired immunity depends on proliferation and differentiation of antigen (Ag)-specific B cells in germinal centers (GCs) of lymphoid follicles in response to T cell-dependent Ags. Here, we studied the function of GC-associated nuclear protein that is selectively up-regulated in GC-B cells. B cell-specific ganp-deficient mice were compromised in affinity maturation of hapten-specific antibodies against T cell-dependent Ags with retarded development of GCs. B cell numbers and development, serum Ig levels, mitogen-induced B cell proliferation in vitro, and responses to T cell-independent Ag were nearly normal; however, the mutant B cells showed a decrease in anti-CD40-induced proliferation and an increased susceptibility to B cell apoptosis in vitro and in vivo. B cell-specific ganp-deficient mice showed a decreased frequency of variable-region somatic mutations, especially of the high-affinity type (W(33) --> L) in the V(H)186.2 region against nitrophenyl-chicken gamma globulin, whereas the class switching was normal. We conclude that GC-associated nuclear protein is necessary for generation or maintenance of B cells with high-affinity B cell Ag receptors during the maturation in GCs.
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Affiliation(s)
- Kazuhiko Kuwahara
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Honjo, Kumamoto 860-8556, Japan
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Martin A, Li Z, Lin DP, Bardwell PD, Iglesias-Ussel MD, Edelmann W, Scharff MD. Msh2 ATPase activity is essential for somatic hypermutation at a-T basepairs and for efficient class switch recombination. ACTA ACUST UNITED AC 2003; 198:1171-8. [PMID: 14568978 PMCID: PMC2194233 DOI: 10.1084/jem.20030880] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Somatic hypermutation (SHM) and class switch recombination (CSR) are initiated by activation-induced cytidine deaminase–mediated cytidine deamination of immunoglobulin genes. MutS homologue (Msh) 2−/− mice have reduced A-T mutations and CSR. This suggests that Msh2 may play a role in repairing activation-induced cytidine deaminase–generated G-U mismatches. However, because Msh2 not only initiates mismatch repair but also has other functions, such as signaling for apoptosis, it is not known which activity of Msh2 is responsible for the effects observed, and consequently, many models have been proposed. To further dissect the role of Msh2 in SHM and CSR, mice with a “knockin” mutation in the Msh2 gene that inactivates the adenosine triphosphatase domain were examined. This mutation (i.e., Msh2G674A), which does not affect apoptosis signaling, allows mismatches to be recognized but prevents Msh2 from initiating mismatch repair. Here, we show that, similar to Msh2−/− mice, SHM in Msh2G674A mice is biased toward G-C mutations. However, CSR is partially reduced, and switch junctions are more similar to those of postmeiotic segregation 2−/− mice than to Msh2−/− mice. These results indicate that Msh2 adenosine triphosphatase activity is required for A-T mutations, and suggest that Msh2 has more than one role in CSR.
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Affiliation(s)
- Alberto Martin
- Department of Immunology, University of Toronto, Medical Sciences Bldg., Toronto, Canada, M5S 1A8.
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Woo CJ, Martin A, Scharff MD. Induction of somatic hypermutation is associated with modifications in immunoglobulin variable region chromatin. Immunity 2003; 19:479-89. [PMID: 14563313 DOI: 10.1016/s1074-7613(03)00261-9] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Somatic hypermutation (SHM) requires selective targeting of the mutational machinery to the variable region of the immunoglobulin heavy chain gene. The induction of SHM in the BL2 cell line upon costimulation is associated with hyperacetylation of the chromatin at the variable region but not at the constant region. The V region-restricted histone hyperacetylation resulting from costimulation occurs independent of AID expression and mutation. Interestingly, costimulation in the presence of Trichostatin A causes hyperacetylation of histones associated with the constant region and extends mutations to the constant region. Under this condition, promoter proximal mutations are observed in the variable region as well. The overexpression of AID results in a similar deregulation of mutational targeting. Our results indicate that the stimulation of SHM in BL2 cells activates two independent pathways resulting in histone modifications that permit induced levels of AID to selectively target the variable region for mutation.
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Affiliation(s)
- Caroline J Woo
- Department of Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Chanin 403, Bronx, NY 10461, USA
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39
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Vaisman A, Frank EG, Iwai S, Ohashi E, Ohmori H, Hanaoka F, Woodgate R. Sequence context-dependent replication of DNA templates containing UV-induced lesions by human DNA polymerase iota. DNA Repair (Amst) 2003; 2:991-1006. [PMID: 12967656 DOI: 10.1016/s1568-7864(03)00094-6] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Humans possess four Y-family polymerases: pols eta, iota, kappa and the Rev1 protein. The pivotal role that pol eta plays in protecting us from UV-induced skin cancers is unquestioned given that mutations in the POLH gene (encoding pol eta), lead to the sunlight-sensitive and cancer-prone xeroderma pigmentosum variant phenotype. The roles that pols iota, kappa and Rev1 play in the tolerance of UV-induced DNA damage is, however, much less clear. For example, in vitro studies in which the ability of pol iota to bypass UV-induced cyclobutane pyrimidine dimers (CPDs) or 6-4 pyrimidine-pyrimidone (6-4PP) lesions has been assayed, are somewhat varied with results ranging from limited misinsertion opposite CPDs to complete lesion bypass. We have tested the hypothesis that such discrepancies might have arisen from different assay conditions and local sequence contexts surrounding each UV-photoproduct and find that pol iota can facilitate significant levels of unassisted highly error-prone bypass of a T-T CPD, particularly when the lesion is located in a 3'-A[T-T]A-5' template sequence context and the reaction buffer contains no KCl. When encountering a T-T 6-4PP dimer under the same assay conditions, pol iota efficiently and accurately inserts the correct base, A, opposite the 3'T of the 6-4PP by factors of approximately 10(2) over the incorporation of incorrect nucleotides, while incorporation opposite the 5'T is highly mutagenic. Pol kappa has been proposed to function in the bypass of UV-induced lesions by helping extend primers terminated opposite CPDs. However, we find no evidence that the combined actions of pol iota and pol kappa result in a significant increase in bypass of T-T CPDs when compared to pol iota alone. Our data suggest that under certain conditions and sequence contexts, pol iota can bypass T-T CPDs unassisted and can efficiently incorporate one or more bases opposite a T-T 6-4PP. Such biochemical activities may, therefore, be of biological significance especially in XP-V cells lacking the primary T-T CPD bypassing enzyme, pol eta.
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Affiliation(s)
- Alexandra Vaisman
- Section on DNA Replication, Repair and Mutagenesis, Laboratory of Genomic Integrity, National Institute of Child Health and Human Development, National Institutes of Health, Building 6, Room 1A13, 9000 Rockville Pike, Bethesda, MD 20892-2725,USA
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40
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McDonald JP, Frank EG, Plosky BS, Rogozin IB, Masutani C, Hanaoka F, Woodgate R, Gearhart PJ. 129-derived strains of mice are deficient in DNA polymerase iota and have normal immunoglobulin hypermutation. J Exp Med 2003; 198:635-43. [PMID: 12925679 PMCID: PMC2194173 DOI: 10.1084/jem.20030767] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Recent studies suggest that DNA polymerase eta (poleta) and DNA polymerase iota (poliota) are involved in somatic hypermutation of immunoglobulin variable genes. To test the role of poliota in generating mutations in an animal model, we first characterized the biochemical properties of murine poliota. Like its human counterpart, murine poliota is extremely error-prone when catalyzing synthesis on a variety of DNA templates in vitro. Interestingly, when filling in a 1 base-pair gap, DNA synthesis and subsequent strand displacement was greatest in the presence of both pols iota and eta. Genomic sequence analysis of Poli led to the serendipitous discovery that 129-derived strains of mice have a nonsense codon mutation in exon 2 that abrogates production of poliota. Analysis of hypermutation in variable genes from 129/SvJ (Poli-/-) and C57BL/6J (Poli+/+) mice revealed that the overall frequency and spectrum of mutation were normal in poliota-deficient mice. Thus, either poliota does not participate in hypermutation, or its role is nonessential and can be readily assumed by another low-fidelity polymerase.
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Affiliation(s)
- John P McDonald
- Laboratory of Genomic Integrity, Building 6, Room 1A13, NICHD, NIH, 9000 Rockville Pike, Bethesda, MD 20892-2725, USA.
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41
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Shimizu T, Shinkai Y, Ogi T, Ohmori H, Azuma T. The absence of DNA polymerase kappa does not affect somatic hypermutation of the mouse immunoglobulin heavy chain gene. Immunol Lett 2003; 86:265-70. [PMID: 12706529 DOI: 10.1016/s0165-2478(03)00046-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During the immune response to T cell-dependent antigen, somatic hypermutation (SHM) is introduced into immunoglobulin (Ig) genes. The variable region is the target for SHM and it is here that DNA lesions are introduced and mutations are generated. It has been suggested that error-prone DNA polymerase(s) may play an important role in this mutagenesis phase. Recently, DNA polymerase kappa (Polkappa), which belongs to the Y-family of DNA polymerases, was identified. Since a hot spot of SHMs (RGYW motif) is also a hot spot of mutations by human Polkappa, this enzyme was suggested to be an SHM instigator. In order to address the question whether Polkappa is involved in SHM, we immunized Polkappa-deficient mice and analyzed the SHM of the Ig heavy chain gene. We found that the SHM frequency and spectrum were indistinguishable between the Polkappa knockout mice and control mice. These results suggested that Polkappa is not essential for this process.
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Affiliation(s)
- Takeyuki Shimizu
- Division of Biosignaling, Research Institute for Biological Science (RIBS), Tokyo University of Science, Yamazaki 2669, Noda Chiba 278-0022, Japan
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Weller S, Faili A, Aoufouchi S, Guéranger Q, Braun M, Reynaud CA, Weill JC. Hypermutation in human B cells in vivo and in vitro. Ann N Y Acad Sci 2003; 987:158-65. [PMID: 12727635 DOI: 10.1111/j.1749-6632.2003.tb06044.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We develop our previous observation that a subpopulation of circulating memory IgM(+)IgD(+)CD27(+)B cells belongs to a separate pathway of differentiation in humans. This subpopulation, which represents 5-25% of peripheral B cells, is also present in spleen in the same proportion and displays a marginal-zone-like B cell phenotype. In addition, we describe a short-time in vitro induction model for somatic hypermutation by using the BL2 Burkitt's lymphoma cell line stimulated by a combination of antibodies directed against different surface receptors. This short-time assay allows us to show that mutations are stably introduced in one DNA strand of the BL2 VH gene in the G1 phase of the cell cycle.
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Affiliation(s)
- Sandra Weller
- INSERM U373, Faculté de Médecine Necker-Enfants Malades, Paris, France
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Gordon MS, Kanegai CM, Doerr JR, Wall R. Somatic hypermutation of the B cell receptor genes B29 (Igbeta, CD79b) and mb1 (Igalpha, CD79a). Proc Natl Acad Sci U S A 2003; 100:4126-31. [PMID: 12651942 PMCID: PMC153059 DOI: 10.1073/pnas.0735266100] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2002] [Indexed: 12/27/2022] Open
Abstract
Somatic hypermutation (SHM), coupled to selection by antigen, generates high-affinity antibodies during germinal center (GC) B cell maturation. SHM is known to affect Bcl6, four additional oncogenes in diffuse large B cell lymphoma, and the CD95Fas gene and is regarded as a major mechanism of B cell tumorigenesis. We find that mutations in the genes encoding the B cell receptor (BCR) accessory proteins B29 (Igbeta, CD79b) and mb1 (Igalpha, CD79a) occur as often as Ig genes in a broad spectrum of GC- and post-GC-derived malignant B cell lines, as well as in normal peripheral B cells. These B29 and mb1 mutations are typical SHM consisting largely of single nucleotide substitutions targeted to hotspots. The B29 and mb1 mutations appear at frequencies similar to those of other non-Ig genes but lower than Ig genes. The distribution of mb1 mutations followed the characteristic pattern found in Ig and most non-Ig genes. In contrast, B29 mutations displayed a bimodal distribution resembling the CD95Fas gene, in which promoter distal mutations conferred resistance to apoptosis. Distal B29 mutations in the cytoplasmic domain may contribute to B cell survival by limiting BCR signaling. B29 and mb1 are mutated in a much broader spectrum of GC-derived B cells than any other known somatically hypermutated non-Ig gene. This may be caused by the common cis-acting regulatory sequences that control the requisite coexpression of the B29, mb1, and Ig chains in the BCR.
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Affiliation(s)
- Melinda S Gordon
- Department of Microbiology, Immunology, and Molecular Genetics, and David Geffen School of Medicine at the University of California, Los Angeles, CA 90095, USA
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Shcherbakova PV, Bebenek K, Kunkel TA. Functions of eukaryotic DNA polymerases. SCIENCE OF AGING KNOWLEDGE ENVIRONMENT : SAGE KE 2003; 2003:RE3. [PMID: 12844548 DOI: 10.1126/sageke.2003.8.re3] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
A major function of DNA polymerases is to accurately replicate the six billion nucleotides that constitute the human genome. This task is complicated by the fact that the genome is constantly challenged by a variety of endogenous and exogenous DNA-damaging agents. DNA damage can block DNA replication or alter base coding potential, resulting in mutations. In addition, the accumulation of damage in nonreplicating DNA can affect gene expression, which leads to the malfunction of many cellular processes. A number of DNA repair systems operate in cells to remove DNA lesions, and several DNA polymerases are known to be the key components of these repair systems. In the past few years, a number of novel DNA polymerases have been discovered that likely function in replicative bypass of DNA damage missed by DNA repair enzymes or in specialized forms of repair. Furthermore, DNA polymerases can act as sensors in cell cycle checkpoint pathways that prevent entry into mitosis until damaged DNA is repaired and replication is completed. The list of DNA template-dependent eukaryotic DNA polymerases now consists of 14 enzymes with amazingly different properties. In this review, we discuss the possible functions of these polymerases in DNA damage repair, the replication of intact and damaged chromosomes, and cell cycle checkpoints.
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Affiliation(s)
- Polina V Shcherbakova
- Laboratory of Molecular Genetics at the National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
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Kunkel TA, Pavlov YI, Bebenek K. Functions of human DNA polymerases eta, kappa and iota suggested by their properties, including fidelity with undamaged DNA templates. DNA Repair (Amst) 2003; 2:135-49. [PMID: 12531385 DOI: 10.1016/s1568-7864(02)00224-0] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Human DNA polymerases eta, kappa and iota are template-dependent, Y-family DNA polymerases that have been implicated in translesion DNA synthesis (TLS) in human cells. Here, we briefly review evidence that these exonuclease-deficient polymerases copy undamaged DNA with very low fidelity and unusual error specificity. Based on the base substitution specificity and other biochemical properties of DNA polymerases eta and iota, we consider the possibility that they participate in specialized DNA transactions that repair damaged DNA and/or generate mutations in the variable regions of immunoglobulin genes.
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Affiliation(s)
- Thomas A Kunkel
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA.
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46
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Abstract
The newly found Y-family DNA polymerases are characterized by low fidelity replication using an undamaged template and the ability to carry out translesion DNA synthesis. The crystal structures of three Y-family polymerases, alone or complexed with DNA and nucleotide substrate, reveal a conventional right-hand-like catalytic core consisting of finger, thumb and palm domains. The finger and thumb domains are unusually small resulting in an open and spacious active site, which can accommodate mismatched base pairs as well as various DNA lesions. Although devoid of a 3'-->5' exonuclease activity, the Y-family polymerases possess a unique "little finger" domain that facilitates DNA association, catalytic efficiency and interactions with auxiliary factors. Expression of Y-family polymerases is often induced by DNA damage, and their recruitment to the replication fork is mediated by beta-clamp, clamp loader, single-strand-DNA-binding protein and RecA in Escherichia coli, and by ubiquitin-modified proliferating cell nuclear antigen in yeast.
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Affiliation(s)
- Wei Yang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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47
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Affiliation(s)
- Peter J Hudson
- CRC for Diagnostics at CSIRO Health Sciences and Nutrition, Parkville, Victoria, Australia.
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48
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Abstract
Based upon phylogenetic relationships, the broad Y-family of DNA polymerases can be divided into various subfamilies consisting of UmuC (polV)-like; DinB (polIV/polkappa)-like; Rev1-like, Rad30A (poleta)-like and Rad30B (poliota)-like polymerases. The polIV/polkappa-like polymerases are most ubiquitous, having been identified in bacteria, archaea and eukaryotes. In contrast, the polV-like polymerases appear restricted to bacteria (both Gram positive and Gram negative). Rev1 and poleta-like polymerases are found exclusively in eukaryotes, and to date, poliota-like polymerases have only been identified in higher eukaryotes. In general, the in vitro properties of polymerases characterized within each sub-family are quite similar. An exception to this rule occurs with the poliota-like polymerases, where the enzymatic properties of Drosophila melanogaster poliota are more similar to that of Saccharomyces cerevisiae and human poleta than to the related human poliota. For example, like poleta, Drosophila poliota can bypass a cis-syn thymine-thymine dimer both accurately and efficiently, while human poliota bypasses the same lesion inefficiently and with low-fidelity. Even in cases where human poliota can efficiently insert a base opposite a lesion (such as a synthetic abasic site, the 3'T of a 6-4-thymine-thymine pyrimidine-pyrimidone photoproduct or opposite benzo[a]pyrene diol epoxide deoxyadenosine adducts), further extension is often limited. Thus, although poliota most likely arose from a genetic duplication of poleta millions of years ago as eukaryotes evolved, it would appear that poliota from humans (and possibly all mammals) has been further subjected to evolutionary pressures that have "tailored" its enzymatic properties away from lesion bypass and towards other function(s) specific for higher eukaryotes. The identification of such functions and the role that mammalian poliota plays in lesion bypass in vivo, should hopefully be forthcoming with the construction of human cell lines deleted for poliota and the identification of mice deficient in poliota.
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Affiliation(s)
- Alexandra Vaisman
- Section on DNA Replication, Repair and Mutagenesis, National Institute of Child Health and Human Development, National Institutes of Health, Building 6, Room 1A13, 9000 Rockville Pike, Bethesda, MD 20892-2725, USA
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49
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Abstract
DNA repair is crucial to the well-being of all organisms from unicellular life forms to humans. A rich tapestry of mechanistic studies on DNA repair has emerged thanks to the recent discovery of Y-family DNA polymerases. Many Y-family members carry out aberrant DNA synthesis-poor replication accuracy, the favored formation of non-Watson-Crick base pairs, efficient mismatch extension, and most importantly, an ability to replicate through DNA damage. This review is devoted primarily to a discussion of Y-family polymerase members that exhibit error-prone behavior. Roles for these remarkable enzymes occur in widely disparate DNA repair pathways, such as UV-induced mutagenesis, adaptive mutation, avoidance of skin cancer, and induction of somatic cell hypermutation of immunoglobulin genes. Individual polymerases engaged in multiple repair pathways pose challenging questions about their roles in targeting and trafficking. Macromolecular assemblies of replication-repair "factories" could enable a cell to handle the complex logistics governing the rapid migration and exchange of polymerases.
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Affiliation(s)
- Myron F Goodman
- Department of Biological Sciences and Chemistry, Hedco Molecular Biology Laboratory, University of Southern California, Los Angeles, California 90089-1340, USA.
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50
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Faili A, Aoufouchi S, Flatter E, Guéranger Q, Reynaud CA, Weill JC. Induction of somatic hypermutation in immunoglobulin genes is dependent on DNA polymerase iota. Nature 2002; 419:944-7. [PMID: 12410315 DOI: 10.1038/nature01117] [Citation(s) in RCA: 156] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2002] [Accepted: 08/20/2002] [Indexed: 11/09/2022]
Abstract
Somatic hypermutation of immunoglobulin genes is a unique, targeted, adaptive process. While B cells are engaged in germinal centres in T-dependent responses, single base substitutions are introduced in the expressed Vh/Vl genes to allow the selection of mutants with a higher affinity for the immunizing antigen. Almost every possible DNA transaction has been proposed to explain this process, but each of these models includes an error-prone DNA synthesis step that introduces the mutations. The Y family of DNA polymerases--pol eta, pol iota, pol kappa and rev1--are specialized for copying DNA lesions and have high rates of error when copying a normal DNA template. By performing gene inactivation in a Burkitt's lymphoma cell line inducible for hypermutation, we show here that somatic hypermutation is dependent on DNA polymerase iota.
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Affiliation(s)
- Ahmad Faili
- INSERM U373, Faculté de Médecine Necker-Enfants Malades, 156 rue de Vaugirard, 75730, Paris Cedex 15, France
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