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Di Y, Cai S, Zheng S, Huang J, Du L, Song Y, Zhang M, Wang Z, Yu G, Ren L, Han H, Zhao Y. Reshaping the murine immunoglobulin heavy chain repertoire with bovine DH genes. Immunology 2021; 165:74-87. [PMID: 34428313 DOI: 10.1111/imm.13407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 08/04/2021] [Accepted: 08/19/2021] [Indexed: 11/30/2022] Open
Abstract
Having a limited number of VH segments, cattle rely on uniquely long DH gene segments to generate CDRH3 length variation (3-70 aa) far greater than that in humans or mice. Bovine antibodies with ultralong CDRH3s (>50 aa) possess unusual structures and abilities to bind to special antigens. In this study, we replaced most murine endogenous DH segments with bovine DH genes, generating a mouse line termed B-DH. The use of bovine DH genes significantly increased the length variation of CDRH3 and consequently the Ig heavy chain repertoire in B-DH mice. However, no ultralong CDRH3 was observed in B-DH mice, suggesting that other factors, in addition to long DH genes, are also involved in the formation of ultralong CDRH3. The B-DH mice mounted a normal humoral immune response to various antigens, although the B-cell developmental paradigm was obviously altered compared with wild-type mice. Additionally, B-DH mice are not predisposed to the generation of autoantibodies despite the interspecies DH gene replacement. The B-DH mice reported in this study provide a unique model to answer basic questions regarding the synergistic evolution of DH and VH genes, VDJ recombination and BCR selection in B-cell development.
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Affiliation(s)
- Yu Di
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, National Engineering Laboratory for Animal Breeding, China Agricultural University, Beijing, China
| | - Shuyi Cai
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, National Engineering Laboratory for Animal Breeding, China Agricultural University, Beijing, China
| | - Shunan Zheng
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, National Engineering Laboratory for Animal Breeding, China Agricultural University, Beijing, China
| | - Jinwei Huang
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, National Engineering Laboratory for Animal Breeding, China Agricultural University, Beijing, China
| | - Lijuan Du
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, National Engineering Laboratory for Animal Breeding, China Agricultural University, Beijing, China
| | - Yu Song
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, National Engineering Laboratory for Animal Breeding, China Agricultural University, Beijing, China
| | - Ming Zhang
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, National Engineering Laboratory for Animal Breeding, China Agricultural University, Beijing, China
| | - Zhao Wang
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, National Engineering Laboratory for Animal Breeding, China Agricultural University, Beijing, China
| | - Guotao Yu
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, National Engineering Laboratory for Animal Breeding, China Agricultural University, Beijing, China
| | - Liming Ren
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, National Engineering Laboratory for Animal Breeding, China Agricultural University, Beijing, China
| | - Haitang Han
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, National Engineering Laboratory for Animal Breeding, China Agricultural University, Beijing, China
| | - Yaofeng Zhao
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, National Engineering Laboratory for Animal Breeding, China Agricultural University, Beijing, China
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Jaconi M, Magni F, Raimondo F, Ponzoni M, Chinello C, Smith A, Piga I, Fusco N, Di Bella C, Pagni F. TdT expression in germ cell tumours: a possible immunohistochemical cross-reaction and diagnostic pitfall. J Clin Pathol 2019; 72:536-541. [PMID: 31055472 DOI: 10.1136/jclinpath-2019-205713] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 04/12/2019] [Accepted: 04/13/2019] [Indexed: 11/04/2022]
Abstract
AIMS Very recent papers proposed a possible role for the expression of terminal deoxynucleotidyl transferase (TdT) in the tumourigenesis of gonadal and extragonadal germ cell-derived tumours (GCTs). Our multicentric study evaluated the magnitude of the immunoreactivity for TdT in GCTs, encompassing seminoma, dysgerminoma, mature teratoma and mixed GCTs. METHODS AND RESULTS The histological series was stained with both monoclonal and polyclonal antibodies, yielding a positivity of 80% of cases with well-defined nuclear reactivity. A significant difference in staining intensity between monoclonal and polyclonal antibodies was observed (p=0.005). However, exploiting western blot and more innovative proteomic approaches, no clear-cut evidence of the TdT protein was observed in the neoplastic tissues of the series. CONCLUSIONS Alternatively to the pathogenetic link between TdT expression and GCTs tumourigenesis, we hypothesised the occurrence of a spurious immunohistochemical nuclear cross-reaction, a well-known phenomenon with important implications and a possible source of diagnostic pitfalls in routine practice for pathologists.
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Affiliation(s)
- Marta Jaconi
- Department of Medicine and Surgery, University Milan Bicocca, Milan, Italy
| | - Fulvio Magni
- Department of Medicine and Surgery, University Milan Bicocca, Milan, Italy
| | - Francesca Raimondo
- Department of Medicine and Surgery, University Milan Bicocca, Milan, Italy
| | | | - Clizia Chinello
- Department of Medicine and Surgery, University Milan Bicocca, Milan, Italy
| | - Andrew Smith
- Department of Medicine and Surgery, University Milan Bicocca, Milan, Italy
| | - Isabella Piga
- Department of Medicine and Surgery, University Milan Bicocca, Milan, Italy
| | - Nicola Fusco
- Division of Pathology, Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Camillo Di Bella
- Department of Medicine and Surgery, University Milan Bicocca, Milan, Italy
| | - Fabio Pagni
- Department of Medicine and Surgery, University Milan Bicocca, Milan, Italy
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3
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Hershberg U, Luning Prak ET. The analysis of clonal expansions in normal and autoimmune B cell repertoires. Philos Trans R Soc Lond B Biol Sci 2016; 370:rstb.2014.0239. [PMID: 26194753 PMCID: PMC4528416 DOI: 10.1098/rstb.2014.0239] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Clones are the fundamental building blocks of immune repertoires. The number of different clones relates to the diversity of the repertoire, whereas their size and sequence diversity are linked to selective pressures. Selective pressures act both between clones and within different sequence variants of a clone. Understanding how clonal selection shapes the immune repertoire is one of the most basic questions in all of immunology. But how are individual clones defined? Here we discuss different approaches for defining clones, starting with how antibodies are diversified during different stages of B cell development. Next, we discuss how clones are defined using different experimental methods. We focus on high-throughput sequencing datasets, and the computational challenges and opportunities that these data have for mining the antibody repertoire landscape. We discuss methods that visualize sequence variants within the same clone and allow us to consider collections of shared mutations to determine which sequences share a common ancestry. Finally, we comment on features of frequently encountered expanded B cell clones that may be of particular interest in the setting of autoimmunity and other chronic conditions.
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Affiliation(s)
- Uri Hershberg
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Bossone 7-711, 3141 Chestnut Street, Philadelphia, PA 19104, USA Department of Immunology and Microbiology, College of Medicine, Drexel University, Bossone 7-711, 3141 Chestnut Street, Philadelphia, PA 19104, USA
| | - Eline T Luning Prak
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, 405B Stellar Chance Labs, 422 Curie Boulevard, Philadelphia, PA 19104, USA
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4
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Troshchynsky A, Dzneladze I, Chen L, Sheng Y, Saridakis V, Wu GE. Functional analyses of polymorphic variants of human terminal deoxynucleotidyl transferase. Genes Immun 2015; 16:388-98. [PMID: 26043173 DOI: 10.1038/gene.2015.19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Revised: 04/19/2015] [Accepted: 04/23/2015] [Indexed: 12/11/2022]
Abstract
Human terminal deoxynucleotidyl transferase (hTdT) is a DNA polymerase that functions to generate diversity in the adaptive immune system. Here, we focus on the function of naturally occurring single-nucleotide polymorphisms (SNPs) of hTdT to evaluate their role in genetic-generated immune variation. The data demonstrate that the genetic variations generated by the hTdT SNPs will vary the human immune repertoire and thus its responses. Human TdT catalyzes template-independent addition of nucleotides (N-additions) during coding joint formation in V(D)J recombination. Its activity is crucial to the diversity of the antigen receptors of B and T lymphocytes. We used in vitro polymerase assays and in vivo human cell V(D)J recombination assays to evaluate the activity and the N-addition levels of six natural (SNP) variants of hTdT. In vitro, the variants differed from wild-type hTdT in polymerization ability with four having significantly lower activity. In vivo, the presence of TdT varied both the efficiency of recombination and N-addition, with two variants generating coding joints with significantly fewer N-additions. Although likely heterozygous, individuals possessing these genetic changes may have less diverse B- and T-cell receptors that would particularly effect individuals prone to adaptive immune disorders, including autoimmunity.
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Affiliation(s)
- A Troshchynsky
- Department of Biology, York University, Toronto, Ontario, Canada
| | - I Dzneladze
- Department of Biology, York University, Toronto, Ontario, Canada
| | - L Chen
- School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada
| | - Y Sheng
- Department of Biology, York University, Toronto, Ontario, Canada
| | - V Saridakis
- Department of Biology, York University, Toronto, Ontario, Canada
| | - G E Wu
- Department of Biology, York University, Toronto, Ontario, Canada.,School of Kinesiology and Health Science, York University, Toronto, Ontario, Canada.,School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
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5
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Wang H, Song C, Gurel Z, Song N, Ma J, Ouyang H, Lai L, Payne KJ, Dovat S. Protein phosphatase 1 (PP1) and Casein Kinase II (CK2) regulate Ikaros-mediated repression of TdT in thymocytes and T-cell leukemia. Pediatr Blood Cancer 2014; 61:2230-5. [PMID: 25214003 PMCID: PMC4205270 DOI: 10.1002/pbc.25221] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 07/20/2014] [Indexed: 12/16/2022]
Abstract
BACKGROUND Ikaros is a DNA-binding protein that acts as master-regulator of hematopoiesis and a tumor suppressor. In thymocytes and T-cell leukemia, Ikaros negatively regulates transcription of terminal deoxynucleotide transferase (TdT), a key protein in lymphocyte differentiation. The signaling pathways that regulate Ikaros-mediated repression of TdT are unknown. Our previous work identified Casein Kinase II (CK2) and Protein Phosphatase 1 (PP1) as regulators of Ikaros DNA binding activity. Here, we investigated the role of PP1 and CK2 in regulating Ikaros-mediated control of TdT expression. PROCEDURES Ikaros phosphomimetic and phosphoresistant mutants and specific CK2 and PP1 inhibitors were used in combination with quantitative chromatin immunoprecipitation (qChIP) and quantitative reverse transcriptase-PCR (q RT-PCR) assays to evaluate the role of CK2 and PP1 in regulating the ability of Ikaros to bind the TdT promoter and to regulate TdT expression. RESULTS We demonstrate that phosphorylation of Ikaros by pro-oncogenic CK2 decreases Ikaros binding to the promoter of the TdT gene and reduces the ability of Ikaros to repress TdT expression during thymocyte differentiation. CK2 inhibition and PP1 activity restore Ikaros DNA-binding affinity toward the TdT promoter, as well as Ikaros-mediated transcriptional repression of TdT in primary thymocytes and in leukemia. CONCLUSION These data establish that PP1 and CK2 signal transduction pathways regulate Ikaros-mediated repression of TdT in thymocytes and leukemia. These findings reveal that PP1 and CK2 have opposing effects on Ikaros-mediated repression of TdT and establish novel roles for PP1 and CK2 signaling in thymocyte differentiation and leukemia.
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Affiliation(s)
- Haijun Wang
- School of Pharmacology, Wenzhou Medical University, Wenzhou 325035, China,Pennsylvania State University College of Medicine, Hershey, PA 17033,College of Animal Sciences, Jilin University, Changchun 130062, China
| | - Chunhua Song
- Pennsylvania State University College of Medicine, Hershey, PA 17033
| | | | - Na Song
- School of Pharmacology, Wenzhou Medical University, Wenzhou 325035, China
| | - Jisheng Ma
- School of Pharmacology, Wenzhou Medical University, Wenzhou 325035, China
| | - Hongsheng Ouyang
- College of Animal Sciences, Jilin University, Changchun 130062, China
| | - Liangxue Lai
- College of Animal Sciences, Jilin University, Changchun 130062, China
| | | | - Sinisa Dovat
- Pennsylvania State University College of Medicine, Hershey, PA 17033,Corresponding author: Sinisa Dovat, MD PhD, Division of Pediatric Hematology/Oncology, Department of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA 17033, Phone: 717-531-6012, FAX: 717-531-4789,
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6
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Affiliation(s)
- Johnny Habchi
- Aix-Marseille Université , Architecture et Fonction des Macromolécules Biologiques (AFMB), UMR 7257, 13288, Marseille, France
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Berdis AJ. DNA Polymerases That Perform Template-Independent DNA Synthesis. NUCLEIC ACID POLYMERASES 2014. [DOI: 10.1007/978-3-642-39796-7_5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Shriner AK, Liu H, Sun G, Guimond M, Alugupalli KR. IL-7-dependent B lymphocytes are essential for the anti-polysaccharide response and protective immunity to Streptococcus pneumoniae. THE JOURNAL OF IMMUNOLOGY 2010; 185:525-31. [PMID: 20505146 DOI: 10.4049/jimmunol.0902841] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Young children are impaired in their response to T cell-independent (TI) Ags, such as pneumococcal polysaccharide (PPS). B lymphopoeisis early in life is IL-7 independent, whereas in adults it is IL-7 dependent. Therefore, we hypothesized that IL-7-driven B lymphopoiesis plays a critical role in promoting Ab responses to TI Ags. Young but not adult mice are impaired in responses to PPS vaccination and to 4-hydroxy-3-nitrophenyl-acetyl-Ficoll, a widely studied model TI Ag, and B1b cells generate Ab responses to these Ags. In this paper, we show that, despite having B1b, B1a, and MZ B cells-all of which are involved in TI responses-young wild-type or adult mice deficient either in IL-7 or in IL-7Ralpha are severely impaired in anti-PPS responses and do not survive Streptococcus pneumoniae challenge, indicating IL-7-dependent B cells are required for TI immunity. Consistent with this, PPS immunization induced a robust TI response in young IL-7 transgenic mice that was comparable to adult wild-type responses. Moreover, immunized young or adult IL-7 transgenic mice were completely resistant to S. pneumoniae challenge. Our data indicate that activating the IL-7 signaling pathway could restore impaired TI responses in the young.
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Affiliation(s)
- Anne K Shriner
- Department of Microbiology and Immunology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA
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Abstract
T-cell receptor (TCR) revision is a process of tolerance induction by which peripheral T cells lose surface expression of an autoreactive TCR, reinduce expression of the recombinase machinery, rearrange genes encoding extrathymically generated TCRs for antigen, and express these new receptors on the cell surface. We discuss the evidence for this controversial tolerance mechanism below. Despite the apparent heresy of post-thymic gene rearrangement, we argue here that TCR revision follows the rules obeyed by maturing thymocytes undergoing gene recombination. Expression of the recombinase is carefully controlled both spatially and temporally, and may be initiated by loss of signals through surface TCRs. The resulting TCR repertoire is characterized by its diversity, self major histocompatibility complex restriction, self tolerance, and ability to mount productive immune responses specific for foreign antigens. Hence, TCR revision is a carefully regulated process of tolerance induction that can contribute to the protection of the individual against invading pathogens while preserving the integrity of self tissue.
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Affiliation(s)
- J Scott Hale
- Department of Immunology, University of Washington, Seattle, WA 98195, USA
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10
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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: 154] [Impact Index Per Article: 10.3] [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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Martin G, Doublié S, Keller W. Determinants of substrate specificity in RNA-dependent nucleotidyl transferases. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2007; 1779:206-16. [PMID: 18177750 DOI: 10.1016/j.bbagrm.2007.12.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2007] [Revised: 11/23/2007] [Accepted: 12/06/2007] [Indexed: 01/28/2023]
Abstract
Poly(A) polymerases were identified almost 50 years ago as enzymes that add multiple AMP residues to the 3' ends of primer RNAs without use of a template from ATP as cosubstrate and with release of pyrophosphate. Based on sequence homology of a signature motif in the catalytic domain, poly(A) polymerases were later found to belong to a superfamily of nucleotidyl transferases acting on a very diverse array of substrates. Enzymes belonging to the superfamily can add from single nucleotides of AMP, CMP or UMP to RNA, antibiotics and proteins but also homopolymers of many hundred residues to the 3' ends of RNA molecules. The recently reported structures of several nucleotidyl transferases facilitate the study of the catalytic mechanisms of these very diverse enzymes. Numerous structures of CCA-adding enzymes have now revealed all steps in the formation of a CCA tail at the 3' end of tRNAs. In addition, structures of poly(A) polymerases and uridylyl transferases are now available as binary and ternary complexes with incoming nucleotide and RNA primer. Some of these proteins undergo significant conformational changes after substrate binding. This is proposed to be an indication for an induced fit mechanism that drives substrate selection and leads to catalysis. Insights from recent structures of ternary complexes indicate an important role for the primer molecule in selecting the incoming nucleotide.
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Affiliation(s)
- Georges Martin
- Department of Cell Biology, Biozentrum, University of Basel, Klingelbergstrasse 70, Basel, Switzerland
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12
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Cidofovir and (S)-9-[3-hydroxy-(2-phosphonomethoxy)propyl]adenine are highly effective inhibitors of vaccinia virus DNA polymerase when incorporated into the template strand. Antimicrob Agents Chemother 2007; 52:586-97. [PMID: 18056278 DOI: 10.1128/aac.01172-07] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The acyclic nucleoside phosphonate drug (S)-9-[3-hydroxy-(2-phosphonomethoxy)propyl]adenine [(S)-HPMPA], is a broad-spectrum antiviral and antiparasitic agent. Previous work has shown that the active intracellular metabolite of this compound, (S)-HPMPA diphosphate [(S)-HPMPApp], is an analog of dATP and targets DNA polymerases. However, the mechanism by which (S)-HPMPA inhibits DNA polymerases remains elusive. Using vaccinia virus as a model system, we have previously shown that cidofovir diphosphate (CDVpp), an analog of dCTP and a related antiviral agent, is a poor substrate for the vaccinia virus DNA polymerase and acts to inhibit primer extension and block 3'-to-5' proofreading exonuclease activity. Based on structural similarities and the greater antiviral efficacy of (S)-HPMPA, we predicted that (S)-HPMPApp would have a similar, but more pronounced effect on vaccinia polymerase than CDVpp. Interestingly, we found that (S)-HPMPApp is a good substrate for the viral enzyme, exhibiting K(m) and V(max) parameters comparable to those of dATP, and certainly not behaving like CDVpp as a functional chain terminator. Metabolic experiments indicated that (S)-HPMPA is converted to (S)-HPMPApp to a much greater extent than CDV is converted to CDVpp, although both drugs cause identical effects on virus DNA replication at their 50% effective concentration. Subsequent studies showed that both compounds can be faithfully incorporated into DNA, but when CDV and (S)-HPMPA are incorporated into the template strand, both strongly inhibit trans-lesion DNA synthesis. It thus appears that nucleoside phosphonate drugs exhibit at least two different effects on DNA polymerases depending upon in what form the enzyme encounters the drug.
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Abstract
RNA-specific nucleotidyl transferases (rNTrs) are a diverse family of template-independent polymerases that add ribonucleotides to the 3'-ends of RNA molecules. All rNTrs share a related active-site architecture first described for DNA polymerase beta and a catalytic mechanism conserved among DNA and RNA polymerases. The best known examples are the nuclear poly(A) polymerases involved in the 3'-end processing of eukaryotic messenger RNA precursors and the ubiquitous CCA-adding enzymes that complete the 3'-ends of tRNA molecules. In recent years, a growing number of new enzymes have been added to the list that now includes the "noncanonical" poly(A) polymerases involved in RNA quality control or in the readenylation of dormant messenger RNAs in the cytoplasm. Other members of the group are terminal uridylyl transferases adding single or multiple UMP residues in RNA-editing reactions or upon the maturation of small RNAs and poly(U) polymerases, the substrates of which are still not known. 2'-5'Oligo(A) synthetases differ from the other rNTrs by synthesizing oligonucleotides with 2'-5'-phosphodiester bonds de novo.
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Affiliation(s)
- Georges Martin
- Department of Cell Biology, Biozentrum, University of Basel, Basel, Switzerland
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14
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Beetz S, Diekhoff D, Steiner LA. Characterization of terminal deoxynucleotidyl transferase and polymerase mu in zebrafish. Immunogenetics 2007; 59:735-44. [PMID: 17701034 DOI: 10.1007/s00251-007-0241-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Accepted: 06/27/2007] [Indexed: 11/30/2022]
Abstract
Terminal deoxynucleotidyl transferase (TdT) contributes to the junctional diversity of immunoglobulin and T-cell receptors by incorporating nucleotides in a template-independent manner. A closely related enzyme, polymerase mu (polmu), a template-directed polymerase, plays a role in general end-joining double-strand break repair. We cloned zebrafish TdT and polmu and found them to be 43% identical in amino acid sequence. Comparisons with sequences of other species revealed conserved residues typical for TdT in the zebrafish sequence that support the template independence of this enzyme. Some but not all of these features were identified in zebrafish polmu. In adult fish, TdT expression was most prominent in thymus, pro- and mesonephros, the primary lymphoid organs in teleost fish and in spleen, intestine, and the tissue around the intestine. Polmu expression was detected not only in pro- and mesonephros, the major sites for B-lymphocyte development, but also in ovary and testis and in all tissue preparations to a low extent. TdT expression starts at 4 dpf and increases thereafter. Polmu is expressed at all times to a similar extent. In situ studies showed a strong expression of TdT and polmicro in the thymic cortex of 8-week-old fish. The characterization of zebrafish TdT and polmu provide new insights in fish lymphopoiesis and addresses the importance and evolution of TdT and polmu themselves.
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Affiliation(s)
- Susann Beetz
- Biology Department, Massachusetts Institute of Technology, Cambridge, MA, USA.
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15
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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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Bertocci B, De Smet A, Weill JC, Reynaud CA. Nonoverlapping functions of DNA polymerases mu, lambda, and terminal deoxynucleotidyltransferase during immunoglobulin V(D)J recombination in vivo. Immunity 2006; 25:31-41. [PMID: 16860755 DOI: 10.1016/j.immuni.2006.04.013] [Citation(s) in RCA: 137] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2006] [Revised: 03/31/2006] [Accepted: 04/10/2006] [Indexed: 11/28/2022]
Abstract
DNA polymerases mu (pol mu), lambda (pol lambda), and terminal deoxynucleotidyltransferase (TdT) are enzymes of the pol X family that share homology in sequence and functional domain organization. We showed previously that pol mu participates in light chain but surprisingly not heavy chain gene rearrangement. We show here that immunoglobulin heavy chain junctions from pol lambda-deficient animals have shorter length with normal N-additions, thus indicating that pol lambda is recruited during heavy chain rearrangement at a step that precedes the action of TdT. In contrast to previous in vitro studies, analysis of animals with combined inactivation of these enzymes revealed no overlapping or compensatory activities for V(D)J recombination between pol mu, pol lambda, and TdT. This complex usage of polymerases with distinct catalytic specificities may correspond to the specific function that the third hypervariable region assumes for each immunoglobulin chain, with pol lambda maintaining a large heavy chain junctional heterogeneity and pol mu ensuring a restricted light chain junctional variability.
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Affiliation(s)
- Barbara Bertocci
- INSERM U783, Faculté de Médecine René Descartes, Site Necker-Enfants Malades, 156 rue de Vaugirard, 75730 Paris Cedex 15, France
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