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Huang Y, Cai J, Tang JF, Zhang HY, Wang ZW, Jian JC, Wu ZH, Lu YS. Identification and expression analysis of terminal deoxynucleotidyl transferase in humphead snapper Lutjanus sanguineus. JOURNAL OF FISH BIOLOGY 2017; 90:2194-2199. [PMID: 28369937 DOI: 10.1111/jfb.13259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Accepted: 11/30/2016] [Indexed: 06/07/2023]
Abstract
A tdt gene was identified successfully from humphead snapper Lutjanus sanguineus, which contained 1710 bp encoding a protein of 463 amino acids. Results of quantitative real-time polymerase chain reaction (qRT-PCR) indicated that tdt mainly expressed in thymus and head kidney and the transcripts of tdt in these tissues were up-regulated significantly at 36 and 48 h after Vibrio harveyi infection. Meanwhile Tdt-producing cells were found in thymus and head kidney.
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Affiliation(s)
- Y Huang
- College of Fishery, Guangdong Ocean University, Zhanjiang, 524088, People's Republic of China
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
- Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
| | - J Cai
- College of Fishery, Guangdong Ocean University, Zhanjiang, 524088, People's Republic of China
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
- Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
| | - J F Tang
- College of Fishery, Guangdong Ocean University, Zhanjiang, 524088, People's Republic of China
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
- Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
| | - H Y Zhang
- College of Fishery, Guangdong Ocean University, Zhanjiang, 524088, People's Republic of China
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
- Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
| | - Z W Wang
- College of Fishery, Guangdong Ocean University, Zhanjiang, 524088, People's Republic of China
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
- Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
| | - J C Jian
- College of Fishery, Guangdong Ocean University, Zhanjiang, 524088, People's Republic of China
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
- Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
| | - Z H Wu
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
- Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
| | - Y S Lu
- College of Fishery, Guangdong Ocean University, Zhanjiang, 524088, People's Republic of China
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
- Guangdong Key Laboratory of Control for Diseases of Aquatic Economic Animals, Zhanjiang, 524088, People's Republic of China
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Schenten V, Guéguinou N, Baatout S, Frippiat JP. Modulation of Pleurodeles waltl DNA polymerase mu expression by extreme conditions encountered during spaceflight. PLoS One 2013; 8:e69647. [PMID: 23936065 PMCID: PMC3729694 DOI: 10.1371/journal.pone.0069647] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 06/12/2013] [Indexed: 11/29/2022] Open
Abstract
DNA polymerase µ is involved in DNA repair, V(D)J recombination and likely somatic hypermutation of immunoglobulin genes. Our previous studies demonstrated that spaceflight conditions affect immunoglobulin gene expression and somatic hypermutation frequency. Consequently, we questioned whether Polμ expression could also be affected. To address this question, we characterized Polμ of the Iberian ribbed newt Pleurodeles waltl and exposed embryos of that species to spaceflight conditions or to environmental modifications corresponding to those encountered in the International Space Station. We noted a robust expression of Polμ mRNA during early ontogenesis and in the testis, suggesting that Polμ is involved in genomic stability. Full-length Polμ transcripts are 8–9 times more abundant in P. waltl than in humans and mice, thereby providing an explanation for the somatic hypermutation predilection of G and C bases in amphibians. Polμ transcription decreases after 10 days of development in space and radiation seem primarily involved in this down-regulation. However, space radiation, alone or in combination with a perturbation of the circadian rhythm, did not affect Polμ protein levels and did not induce protein oxidation, showing the limited impact of radiation encountered during a 10-day stay in the International Space Station.
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Affiliation(s)
- Véronique Schenten
- Stress Immunity Pathogens Laboratory, EA7300, Lorraine University, Vandœuvre-lès-Nancy, France
| | - Nathan Guéguinou
- Stress Immunity Pathogens Laboratory, EA7300, Lorraine University, Vandœuvre-lès-Nancy, France
| | - Sarah Baatout
- Radiobiology Unit, Belgian Nuclear Research Centre, SCK•CEN, Mol, Belgium
- Department of Molecular Biotechnology, Ghent University, Ghent, Belgium
| | - Jean-Pol Frippiat
- Stress Immunity Pathogens Laboratory, EA7300, Lorraine University, Vandœuvre-lès-Nancy, France
- * E-mail:
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3
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Matsumoto T, Go K, Hyodo M, Koiwai K, Maezawa S, Hayano T, Suzuki M, Koiwai O. BRCT domain of DNA polymerase μ has DNA-binding activity and promotes the DNA polymerization activity. Genes Cells 2012; 17:790-806. [DOI: 10.1111/j.1365-2443.2012.01628.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 06/14/2012] [Indexed: 11/30/2022]
Affiliation(s)
- Takuro Matsumoto
- Department of Applied Biological Science; Faculty of Science and Technology; Tokyo University of Science; Noda; Chiba; 278-8510; Japan
| | - Kaori Go
- Department of Applied Biological Science; Faculty of Science and Technology; Tokyo University of Science; Noda; Chiba; 278-8510; Japan
| | - Mariko Hyodo
- Department of Applied Biological Science; Faculty of Science and Technology; Tokyo University of Science; Noda; Chiba; 278-8510; Japan
| | - Kotaro Koiwai
- Department of Applied Biological Science; Faculty of Science and Technology; Tokyo University of Science; Noda; Chiba; 278-8510; Japan
| | - So Maezawa
- Department of Applied Biological Science; Faculty of Science and Technology; Tokyo University of Science; Noda; Chiba; 278-8510; Japan
| | - Takahide Hayano
- Department of Applied Biological Science; Faculty of Science and Technology; Tokyo University of Science; Noda; Chiba; 278-8510; Japan
| | - Masahiro Suzuki
- Department of Applied Biological Science; Faculty of Science and Technology; Tokyo University of Science; Noda; Chiba; 278-8510; Japan
| | - Osamu Koiwai
- Department of Applied Biological Science; Faculty of Science and Technology; Tokyo University of Science; Noda; Chiba; 278-8510; Japan
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Motea EA, Berdis AJ. Terminal deoxynucleotidyl transferase: the story of a misguided DNA polymerase. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1804:1151-66. [PMID: 19596089 DOI: 10.1016/j.bbapap.2009.06.030] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2009] [Revised: 06/27/2009] [Accepted: 06/30/2009] [Indexed: 01/06/2023]
Abstract
Nearly every DNA polymerase characterized to date exclusively catalyzes the incorporation of mononucleotides into a growing primer using a DNA or RNA template as a guide to direct each incorporation event. There is, however, one unique DNA polymerase designated terminal deoxynucleotidyl transferase that performs DNA synthesis using only single-stranded DNA as the nucleic acid substrate. In this chapter, we review the biological role of this enigmatic DNA polymerase and the biochemical mechanism for its ability to perform DNA synthesis in the absence of a templating strand. We compare and contrast the molecular events for template-independent DNA synthesis catalyzed by terminal deoxynucleotidyl transferase with other well-characterized DNA polymerases that perform template-dependent synthesis. This includes a quantitative inspection of how terminal deoxynucleotidyl transferase binds DNA and dNTP substrates, the possible involvement of a conformational change that precedes phosphoryl transfer, and kinetic steps that are associated with the release of products. These enzymatic steps are discussed within the context of the available structures of terminal deoxynucleotidyl transferase in the presence of DNA or nucleotide substrate. In addition, we discuss the ability of proteins involved in replication and recombination to regulate the activity of the terminal deoxynucleotidyl transferase. Finally, the biomedical role of this specialized DNA polymerase is discussed focusing on its involvement in cancer development and its use in biomedical applications such as labeling DNA for detecting apoptosis.
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Affiliation(s)
- Edward A Motea
- Department of Chemistry, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
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5
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Sweasy JB, Lauper JM, Eckert KA. DNA polymerases and human diseases. Radiat Res 2006; 166:693-714. [PMID: 17067213 DOI: 10.1667/rr0706.1] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2006] [Accepted: 07/12/2006] [Indexed: 11/03/2022]
Abstract
DNA polymerases function in DNA replication, repair, recombination and translesion synthesis. Currently, 15 DNA polymerase genes have been identified in human cells, belonging to four distinct families. In this review, we briefly describe the biochemical activities and known cellular roles of each DNA polymerase. Our major focus is on the phenotypic consequences of mutation or ablation of individual DNA polymerase genes. We discuss phenotypes of current mouse models and altered polymerase functions and the relationship of DNA polymerase gene mutations to human cell phenotypes. Interestingly, over 120 single nucleotide polymorphisms (SNPs) have been identified in human populations that are predicted to result in nonsynonymous amino acid substitutions of DNA polymerases. We discuss the putative functional consequences of these SNPs in relation to human disease.
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Affiliation(s)
- Joann B Sweasy
- Department of Therapeutic Radiology, Yale University School of Medicine, 15 York Street, HRT 313D, P.O. Box 208040, New Haven, CT 06520-8040, USA.
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Abstract
The human genome, comprising three billion base pairs coding for 30000-40000 genes, is constantly attacked by endogenous reactive metabolites, therapeutic drugs and a plethora of environmental mutagens that impact its integrity. Thus it is obvious that the stability of the genome must be under continuous surveillance. This is accomplished by DNA repair mechanisms, which have evolved to remove or to tolerate pre-cytotoxic, pre-mutagenic and pre-clastogenic DNA lesions in an error-free, or in some cases, error-prone way. Defects in DNA repair give rise to hypersensitivity to DNA-damaging agents, accumulation of mutations in the genome and finally to the development of cancer and various metabolic disorders. The importance of DNA repair is illustrated by DNA repair deficiency and genomic instability syndromes, which are characterised by increased cancer incidence and multiple metabolic alterations. Up to 130 genes have been identified in humans that are associated with DNA repair. This review is aimed at updating our current knowledge of the various repair pathways by providing an overview of DNA-repair genes and the corresponding proteins, participating either directly in DNA repair, or in checkpoint control and signaling of DNA damage.
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Affiliation(s)
- Markus Christmann
- Division of Applied Toxicology, Institute of Toxicology, University of Mainz, Obere Zahlbacher Str. 67, D-55131 Mainz, Germany
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Bartl S, Miracle AL, Rumfelt LL, Kepler TB, Mochon E, Litman GW, Flajnik MF. Terminal deoxynucleotidyl transferases from elasmobranchs reveal structural conservation within vertebrates. Immunogenetics 2003; 55:594-604. [PMID: 14579105 DOI: 10.1007/s00251-003-0608-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2003] [Revised: 08/25/2003] [Indexed: 01/21/2023]
Abstract
The DNA polymerase (pol) X family is an ancient group of enzymes that function in DNA replication and repair (pol beta), translesion synthesis (pol lambda and pol micro) and terminal addition of non-templated nucleotides. This latter terminal deoxynucleotidyl transferase (TdT) activity performs the unique function of providing diversity at coding joins of immunoglobulin and T-cell receptor genes. The first isolated full-length TdT genes from shark and skate are reported here. Comparisons with the three-dimensional structure of mouse TdT indicate structural similarity with elasmobranch orthologues that supports both a template-independent mode of replication and a lack of strong nucleotide bias. The vertebrate TdTs appear more closely related to pol micro and fungal polymerases than to pol lambda and pol beta. Thus, unlike other molecules of adaptive immunity, TdT is a member of an ancient gene family with a clear gene phylogeny and a high degree of similarity, which implies the existence of TdT ancestors in jawless fishes and invertebrates.
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Affiliation(s)
- Simona Bartl
- Moss Landing Marine Laboratories, 8272 Moss Landing Road, CA 95039, Moss Landing, USA.
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Bertocci B, De Smet A, Berek C, Weill JC, Reynaud CA. Immunoglobulin kappa light chain gene rearrangement is impaired in mice deficient for DNA polymerase mu. Immunity 2003; 19:203-11. [PMID: 12932354 DOI: 10.1016/s1074-7613(03)00203-6] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
DNA polymerase mu (pol mu) is a template-dependent polymerase closely related to the lymphoid-specific enzyme terminal deoxynucleotidyl transferase (TdT). We report here the phenotype of pol mu-deficient mice. Such animals display an abnormal B cell differentiation, with a specific alteration in the IgM- to IgM+ transition in bone marrow. In all mice, Ig light chain gene rearrangement is impaired at the level of the Vkappa-Jkappa and Vlambda-Jlambda junctions, which show extensive nibbling of both coding extremities. These alterations lead to a profound defect in the peripheral B cell compartment which, although variable between animals, results in an average 40% reduction in the splenic B cell fraction. Pol mu appears, therefore, as a key element contributing to the relative homogeneity in size of light chain CDR3 and taking part in Ig gene rearrangement at a stage where TdT is no longer expressed.
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Affiliation(s)
- Barbara Bertocci
- Institut National Français de Recherche Médicale U373, Faculté de Médecine Necker-Enfants Malades, 156 rue de Vaugirard, 75730 Paris 15, France
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Wu X, Feng J, Komori A, Kim EC, Zan H, Casali P. Immunoglobulin somatic hypermutation: double-strand DNA breaks, AID and error-prone DNA repair. J Clin Immunol 2003; 23:235-46. [PMID: 12959216 PMCID: PMC4624321 DOI: 10.1023/a:1024571714867] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Somatic hypermutation (SHM) is critical for antibody affinity maturation and the generation of memory B cells. Somatic mutations consist mainly of single nucleotide changes with rare insertions and deletions. Such changes would be introduced during error-prone repair of lesions involving single-strand DNA breaks (SSBs) or, more likely, double-strand DNA breaks (DSBs), as DSBs occur exclusively in genes that have the potentials to undergo SHM. In the human, such genes include Ig V, BCL6, and c-MYC. In these germline genes, DSBs are blunt. In rearranged Ig V, BCL6, and translocated c-MYC genes, blunt DSBs are processed to yield resected DNA ends. This process is dependent on the expression of activation-induced cytidine deaminase (AID), which is selectively expressed upon CD40-signaling in hypermutating B cells. CD40-induced and AID-dependent free 5'- and 3'-staggered DNA ends critically channel the repair of DSBs through the homologous recombination (HR) repair pathway. During HR, the modulation of critical translesion DNA polymerases, as signaled by cross-linking of the B cell receptor (BCR) for antigen, leads to the insertions of mismatches, i.e., mutations. The nature of DSBs, the possible roles of AID in the modification of DSBs and that of the translesion DNA polymerases zeta and iota in the subsequent repair process that lead to the insertions of mutations are discussed here within the context of an integrated model of SHM.
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Affiliation(s)
- Xiaoping Wu
- Division of Molecular Immunology, Joan and Sanford I. Weill Medical College and Graduate School of Medical Sciences, Cornell University, New York, USA
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10
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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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Weill JC, Bertocci B, Faili A, Aoufouchi S, Frey S, De Smet A, Storck S, Dahan A, Delbos F, Weller S, Flatter E, Reynaud CA. Ig gene hypermutation: a mechanism is due. Adv Immunol 2002; 80:183-202. [PMID: 12078481 DOI: 10.1016/s0065-2776(02)80015-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Jean-Claude Weill
- INSERM Unité 373, Faculté de Médecine Necker-Enfants Malades, Université Paris V, 75730 Paris, 15, France
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12
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Abstract
Hodgkin's lymphoma (HL) is characterized by typical mononucleated Hodgkin and multinucleated Reed-Sternberg cells, which occur at low frequency in a mixed cellular infiltrate in the tumor tissue. Because of the rarity of these cells and their unusual immunophenotype, which is strikingly different from those of all normal hematopoietic cell types, the origin of these cells and their clonality have long been unclear. Single-cell studies of rearranged immunoglobulin genes showed that Hodgkin and Reed-Sternberg (HRS) cells represent clonal tumor-cell populations derived from germinal center B cells. In classical HL, the detection of obviously crippling immunoglobulin gene mutations in a fraction of the cases suggests that HRS cells may derive from germinal center B cells that have lost the capacity to be positively selected by antigen and that normally would have undergone apoptosis. In rare cases, HRS cells represent transformed T lymphocytes. The transforming events involved in malignant transformation of HRS cells are still largely unknown. Constitutive activation of the transcription factor NFkappaB, which can, for example, be induced through Epstein-Barr virus transformation of HRS cells or destructive somatic mutations of the inhibitor of NFkappaB, is likely to be a key event in HL pathogenesis. Significant progress has been made in our understanding of the cellular interactions in HL tissues, which are mainly mediated by a large variety of cytokines and chemokines.
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Affiliation(s)
- Ralf Küppers
- Institute for Genetics and Department of Internal Medicine I, University of Cologne, Germany
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Mahajan KN, Nick McElhinny SA, Mitchell BS, Ramsden DA. Association of DNA polymerase mu (pol mu) with Ku and ligase IV: role for pol mu in end-joining double-strand break repair. Mol Cell Biol 2002; 22:5194-202. [PMID: 12077346 PMCID: PMC139779 DOI: 10.1128/mcb.22.14.5194-5202.2002] [Citation(s) in RCA: 223] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Mammalian DNA polymerase mu (pol mu) is related to terminal deoxynucleotidyl transferase, but its biological role is not yet clear. We show here that after exposure of cells to ionizing radiation (IR), levels of pol mu protein increase. pol mu also forms discrete nuclear foci after IR, and these foci are largely coincident with IR-induced foci of gammaH2AX, a previously characterized marker of sites of DNA double-strand breaks. pol mu is thus part of the cellular response to DNA double-strand breaks. pol mu also associates in cell extracts with the nonhomologous end-joining repair factor Ku and requires both Ku and another end-joining factor, XRCC4-ligase IV, to form a stable complex on DNA in vitro. pol mu in turn facilitates both stable recruitment of XRCC4-ligase IV to Ku-bound DNA and ligase IV-dependent end joining. In contrast, the related mammalian DNA polymerase beta does not form a complex with Ku and XRCC4-ligase IV and is less effective than pol mu in facilitating joining mediated by these factors. Our data thus support an important role for pol mu in the end-joining pathway for repair of double-strand breaks.
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Affiliation(s)
- Kiran N Mahajan
- Lineberger Comprehensive Cancer Center, Mason Farm Road, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7295, USA
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Bross L, Muramatsu M, Kinoshita K, Honjo T, Jacobs H. DNA double-strand breaks: prior to but not sufficient in targeting hypermutation. J Exp Med 2002; 195:1187-92. [PMID: 11994423 PMCID: PMC2193713 DOI: 10.1084/jem.20011749] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2001] [Revised: 01/18/2002] [Accepted: 01/24/2002] [Indexed: 11/29/2022] Open
Abstract
The activation-induced cytidine deaminase (AID) is required for somatic hypermutation (SHM) and class-switch recombination (CSR) of immunoglobulin (Ig) genes, both of which are associated with DNA double-strand breaks (DSBs). As AID is capable of deaminating deoxy-cytidine (dC) to deoxy-uracil (dU), it might induce nicks (single strand DNA breaks) and also DNA DSBs via a U-DNA glycosylase-mediated base excision repair pathway ('DNA-substrate model'). Alternatively, AID functions like its closest homologue Apobec1 as a catalytic subunit of a RNA editing holoenzyme ('RNA-substrate model'). Although rearranged Vlambda genes are preferred targets of SHM we found that germinal center (GC) B cells of AID-proficient and -deficient Vlambda1-expressing GC B cells display a similar frequency, distribution, and sequence preference of DSBs in rearranged and also in germline Vlambda1 genes. The possible roles of DSBs in relation to AID function and SHM are discussed.
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Affiliation(s)
- Linda Bross
- Basel Institute for Immunology, CH-4005 Basel, Switzerland
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15
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Burgers PM, Koonin EV, Bruford E, Blanco L, Burtis KC, Christman MF, Copeland WC, Friedberg EC, Hanaoka F, Hinkle DC, Lawrence CW, Nakanishi M, Ohmori H, Prakash L, Prakash S, Reynaud CA, Sugino A, Todo T, Wang Z, Weill JC, Woodgate R. Eukaryotic DNA polymerases: proposal for a revised nomenclature. J Biol Chem 2001; 276:43487-90. [PMID: 11579108 DOI: 10.1074/jbc.r100056200] [Citation(s) in RCA: 269] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- P M Burgers
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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16
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Rada C, Milstein C. The intrinsic hypermutability of antibody heavy and light chain genes decays exponentially. EMBO J 2001; 20:4570-6. [PMID: 11500383 PMCID: PMC125579 DOI: 10.1093/emboj/20.16.4570] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Somatic hypermutation, essential for the affinity maturation of antibodies, is restricted to a small segment of DNA. The upstream boundary is sharp and is probably related to transcription initiation. However, for reasons unknown, the hypermutation domain does not encompass the whole transcription unit, notably the C-region exon. Since analysis of the downstream decay of hypermutation is obscured by sequence-dependent hot and cold spots, we describe a strategy to minimize these fluctuations by computing mutations of different sequences located at similar distances from the promoter. We pool large databases of mutated heavy and light chains and analyse the decay of mutation frequencies. We define an intrinsic decay of probability of mutation that is remarkably similar for heavy and light chains, faster than anticipated and consistent with an exponential fit. Indeed, quite apart from hot spots, the intrinsic probability of mutation at CDR1 can be almost twice that of CDR3. The analysis has mechanistic implications for current and future models of hypermutation.
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Affiliation(s)
- C Rada
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK.
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