51
|
Ramadan K, Shevelev IV, Maga G, Hübscher U. De novo DNA synthesis by human DNA polymerase lambda, DNA polymerase mu and terminal deoxyribonucleotidyl transferase. J Mol Biol 2004; 339:395-404. [PMID: 15136041 DOI: 10.1016/j.jmb.2004.03.056] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2004] [Revised: 03/18/2004] [Accepted: 03/19/2004] [Indexed: 11/23/2022]
Abstract
DNA polymerases (pols) catalyse the synthesis of DNA. This reaction requires a primer-template DNA in order to grow from the 3'OH end of the primer along the template. On the other hand terminal deoxyribonucleotidyl transferase (TdT) catalyses the addition of nucleotides at the 3'OH end of a DNA strand, without the need of a template. Pol lambda and pol micro are ubiquitous enzymes, possess both DNA polymerase and terminal deoxyribonucleotidyl transferase activities and belong to pol X family, together with pol beta and TdT. Here we show that pol lambda, pol micro and TdT, all possess the ability to synthesise in vitro short fragments of DNA in the absence of a primer-template or even a primer or a template in the reaction. The DNA synthesised de novo by pol lambda, pol micro and TdT appears to have an unusual structure. Furthermore we found that the amino acid Phe506 of pol lambda is essential for the de novo synthesis. This novel catalytic activity might be related to the proposed functions of these three pol X family members in DNA repair and DNA recombination.
Collapse
Affiliation(s)
- Kristijan Ramadan
- Institute of Veterinary Biochemistry and Molecular Biology, University of Zürich-Irchel, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
| | | | | | | |
Collapse
|
52
|
Candon S, McHugh RS, Foucras G, Natarajan K, Shevach EM, Margulies DH. Spontaneous organ-specific Th2-mediated autoimmunity in TCR transgenic mice. THE JOURNAL OF IMMUNOLOGY 2004; 172:2917-24. [PMID: 14978094 DOI: 10.4049/jimmunol.172.5.2917] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CD4(+) T cells that lead to autoimmune gastritis (AIG) in BALB/c mice are either Th1 or Th2 cells. To test whether the phenotype of disease is related to the particular TCR expressed by the pathogenic cell, we have generated several lines of TCR transgenic mice using receptors cloned from pathogenic Th1 or Th2 cells. We previously described spontaneous inflammatory AIG in A23 mice, caused by the transgenic expression of the TCR from a Th1 clone, TXA23. In this study we describe the generation of A51 mouse lines, transgenic for the TCR of a CD4(+) self-reactive Th2 clone, TXA51. A proportion of A51 mice spontaneously develop AIG by 10 wk of age, with a disease characterized by eosinophilic infiltration of the gastric mucosa and Th2 differentiation of transgenic T cells in the gastric lymph node. The Th2 phenotype of this autoimmune response seems to be related to a low availability of MHC class II-self peptide complexes. This in vivo model of spontaneous Th2-mediated, organ-specific autoimmunity provides a unique example in which the clonotypic TCR conveys the Th2 disease phenotype.
Collapse
Affiliation(s)
- Sophie Candon
- Molecular Biology Section, Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892, USA
| | | | | | | | | | | |
Collapse
|
53
|
Golub R, André S, Hassanin A, Affaticati P, Larijani M, Fellah JS. Early expression of two TdT isoforms in the hematopoietic system of the Mexican axolotl. Implications for the evolutionary origin of the N-nucleotide addition. Immunogenetics 2004; 56:204-13. [PMID: 15146297 DOI: 10.1007/s00251-004-0681-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2003] [Revised: 04/20/2004] [Indexed: 11/28/2022]
Abstract
Nontemplate (N)-nucleotide addition by the terminal dideoxynucleotidyl transferase (TdT) at the junctions of rearranging V( D) J gene segments greatly contribute to antigen-receptor diversity. TdT has been identified in several vertebrate species, where it is highly conserved. We report here the isolation of two forms of TdT mRNA in an amphibian, the Mexican axolotl. The isoform TdT1 shares all of the conserved structural motifs required for TdT activity and displays an average of 50-58% similarity at the amino acid level with TdT of other species. The second axolotl TdT variant ( TdT2) differs from TdT1 by a 57-amino acid deletion located between amino acids 165-222 of TdT1, including the first helix-hairpin-helix DNA-binding motif. During ontogeny, TdT products are first detected in the head of 6-week-old larvae and further in the head and trunk of 8-month-old larvae. These developmental stages correspond to the first detection of RAG1 and antigen-receptor (TCRbeta and IgHmicro) products in axolotl larvae. Our results suggest that in contrast to mammalian development, N diversity occurs early in axolotl development to diversify the primary repertoire. Phylogenetic analyses reveal that TdT and DNA polymerase mu(Pol mu) genes are closely related, and that both enzymes were already present in the common ancestor of jawed vertebrates.
Collapse
Affiliation(s)
- Rachel Golub
- Unité du Développement des Lymphocytes, CNRS URA 1961 Institut Pasteur, 25-28 rue du Docteur Roux, 75724, Paris Cedex 15, France
| | | | | | | | | | | |
Collapse
|
54
|
Sandor Z, Calicchio ML, Sargent RG, Roth DB, Wilson JH. Distinct requirements for Ku in N nucleotide addition at V(D)J- and non-V(D)J-generated double-strand breaks. Nucleic Acids Res 2004; 32:1866-73. [PMID: 15047854 PMCID: PMC390357 DOI: 10.1093/nar/gkh502] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2004] [Revised: 03/03/2004] [Accepted: 03/03/2004] [Indexed: 12/18/2022] Open
Abstract
Loss or addition of nucleotides at junctions generated by V(D)J recombination significantly expands the antigen-receptor repertoire. Addition of nontemplated (N) nucleotides is carried out by terminal deoxynucleotidyl transferase (TdT), whose only known physiological role is to create diversity at V(D)J junctions during lymphocyte development. Although purified TdT can act at free DNA ends, its ability to add nucleotides (i.e. form N regions) at coding joints appears to depend on the nonhomologous end-joining factor Ku80. Because the DNA ends generated during V(D)J rearrangements remain associated with the RAG proteins after cleavage, TdT might be targeted for N region addition through interactions with RAG proteins or with Ku80 during remodeling of the post-cleavage complex. Such regulated access would help to prevent TdT from acting at other types of broken ends and degrading the fidelity of end joining. To test this hypothesis, we measured TdT's ability to add nucleotides to endonuclease-induced chromosomal and extrachromosomal breaks. In both cases TdT added nucleotides efficiently to the cleaved DNA ends. Strikingly, the frequency of N regions at non-V(D)J-generated ends was not dependent on Ku80. Thus our results suggest that Ku80 is required to allow TdT access to RAG post-cleavage complexes, providing support for the hypothesis that Ku is involved in disassembling or remodeling the post-cleavage complex. We also found that N regions were abnormally long in the absence of Ku80, indicating that Ku80 may regulate TdT's activity at DNA ends in vivo.
Collapse
Affiliation(s)
- Zoltan Sandor
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | | | | | | | | |
Collapse
|
55
|
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.
Collapse
Affiliation(s)
- Alison J Rattray
- Gene Regulation and Chromosome Biology Laboratory, NCI-Frederick, National Cancer Institute, National Institutes of Health, Frederick, Maryland 21702, USA.
| | | |
Collapse
|
56
|
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.
Collapse
Affiliation(s)
- Simona Bartl
- Moss Landing Marine Laboratories, 8272 Moss Landing Road, CA 95039, Moss Landing, USA.
| | | | | | | | | | | | | |
Collapse
|
57
|
Bebenek K, Garcia-Diaz M, Blanco L, Kunkel TA. The frameshift infidelity of human DNA polymerase lambda. Implications for function. J Biol Chem 2003; 278:34685-90. [PMID: 12829698 DOI: 10.1074/jbc.m305705200] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
DNA polymerase lambda (Pol lambda) is a member of the Pol X family having properties in common with several other mammalian DNA polymerases. To obtain clues to possible functions in vivo, we have determined the fidelity of DNA synthesis by human Pol lambda. The results indicate that the average single-base deletion error rate of Pol lambda is higher than those of other mammalian polymerases. In fact, unlike other DNA polymerases, Pol lambda generates single-base deletions at average rates that substantially exceed base substitution rates. Moreover, the sequence specificity for single-base deletions made by Pol lambda is different from that of other DNA polymerases and reveals that Pol lambda readily uses template-primers with limited base pair homology at the primer terminus. This ability, together with an ability to fill short gaps in DNA at low dNTP concentrations, is consistent with a role for mammalian Pol lambda in non-homologous end-joining. This may include non-homologous end-joining of strand breaks resulting from DNA damage, because Pol lambda has intrinsic 5',2'-deoxyribose-5-phosphate lyase activity.
Collapse
Affiliation(s)
- Katarzyna Bebenek
- Laboratory of Molecular Genetics and Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina 27709, USA
| | | | | | | |
Collapse
|
58
|
Abstract
DNA polymerases are defined as such because they use deoxynucleotides instead of ribonucleotides with high specificity. We show here that polymerase mu (pol mu), implicated in the nonhomologous end-joining pathway for repair of DNA double-strand breaks, incorporates both ribonucleotides and deoxynucleotides in a template-directed manner. pol mu has an approximately 1,000-fold-reduced ability to discriminate against ribonucleotides compared to that of the related pol beta, although pol mu's substrate specificity is similar to that of pol beta in most other respects. Moreover, pol mu more frequently incorporates ribonucleotides when presented with nucleotide concentrations that approximate cellular pools. We therefore addressed the impact of ribonucleotide incorporation on the activities of factors required for double-strand break repair by nonhomologous end joining. We determined that the ligase required for this pathway readily joined strand breaks with terminal ribonucleotides. Most significantly, pol mu frequently introduced ribonucleotides into the repair junctions of an in vitro nonhomologous end-joining reaction, an activity that would be expected to have important consequences in the context of cellular double-strand break repair.
Collapse
Affiliation(s)
- Stephanie A Nick McElhinny
- Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | | |
Collapse
|
59
|
Tseng HM, Tomkinson AE. A physical and functional interaction between yeast Pol4 and Dnl4-Lif1 links DNA synthesis and ligation in nonhomologous end joining. J Biol Chem 2002; 277:45630-7. [PMID: 12235149 DOI: 10.1074/jbc.m206861200] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Genetic studies have implicated the Saccharomyces cerevisiae POL4 gene product in the repair of DNA double-strand breaks by nonhomologous end joining. Here we show that Pol4 preferentially catalyzes DNA synthesis on small gaps formed by the alignment of linear duplex DNA molecules with complementary ends, a DNA substrate specificity that is compatible with its predicted role in the repair of DNA double-strand breaks. Pol4 also interacts directly with the Dnl4 subunit of the Dnl4-Lif1 complex via its N-terminal BRCT domain. This interaction stimulates the DNA synthesis activity of Pol4 and, to a lesser extent, the DNA joining activity of Dnl4-Lif1. Notably, the joining of DNA substrates that require the combined action of Pol4 and Dnl4-Lif1 is much more efficient than the joining of similar DNA substrates that require only ligation. Thus, the physical and functional interactions between Pol4 and Dnl4-Lif1 provide a molecular mechanism for both the recruitment of Pol4 to in vivo DNA double-strand breaks and the coupling of the gap filling DNA synthesis and DNA joining reactions that complete the microhomology-mediated pathway of nonhomologous end joining.
Collapse
Affiliation(s)
- Hui-Min Tseng
- Department of Molecular Medicine and Institute of Biotechnology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas 78245-3207, USA
| | | |
Collapse
|
60
|
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.
Collapse
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
| | | | | | | |
Collapse
|
61
|
Mi QS, Rezanka LJ, Lustig A, Zhou L, Longo DL, Kenny JJ. The M603 idiotype is lost in the response to phosphocholine in terminal deoxynucleotidyl transferase-deficient mice. Eur J Immunol 2002; 32:1139-46. [PMID: 11932921 DOI: 10.1002/1521-4141(200204)32:4<1139::aid-immu1139>3.0.co;2-e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The majority of anti-phosphocholine (PC) antibodies induced by the PC epitope in Proteus morganii (PM) express the M603 idiotype (id), which is characterized by an invariant Asp to Asn substitution at the V(H):D(H) junction. To elucidate the molecular basis by which M603-like B cells acquire the mutations resulting in this invariant substitution, we analyzed the immune response to PC-PM in terminal deoxynucleotidyl transferase (TdT) gene knockout (KO) mice. In the absence of TdT, T15-id antibodies comprised 80-100% of the primary response to PC-PM. Less than 10% of the response in wild-type mice is T15-id(+). In TdT KO mice, the secondary response to PC-KLH was higher than in wild-type mice and was dominated by the germ-line T15-id. About 10% of this response, in both TdT KO and wild-type mice, comprised M167-id(+) antibodies. Additionally, none of the functionally rearranged V1/DFL16.1/J(H)1 cDNA isolated from PC-PM-immunized TdT KO mice showed the Asp/Asn substitution characteristic of PC-binding, PC-PM-induced M603-like antibodies. These data indicate that production of M603-id antibody is TdT dependent, while generation of M167-id antibody is TdT independent, and that in the absence of competition from M603-like B cells, T15-id B cells can respond to PC-PM.
Collapse
Affiliation(s)
- Qing-Sheng Mi
- Laboratory of Immunology, Gerontology Research Center, National Institute on Aging, National Institutes of Health, Baltimore 21224, USA
| | | | | | | | | | | |
Collapse
|
62
|
Cabaniols JP, Fazilleau N, Casrouge A, Kourilsky P, Kanellopoulos JM. Most alpha/beta T cell receptor diversity is due to terminal deoxynucleotidyl transferase. J Exp Med 2001; 194:1385-90. [PMID: 11696602 PMCID: PMC2195970 DOI: 10.1084/jem.194.9.1385] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
The contribution of template-independent nucleotide addition to antigen receptor diversity is unknown. We therefore determined the size of the T cell receptor (TCR)alpha/beta repertoire in mice bearing a null mutation on both alleles of the terminal deoxynucleotidyl transferase (Tdt) gene. We used a method based upon polymerase chain reaction amplification and exhaustive sequencing of various AV-AJ and BV-BJ combinations. In both wild-type and Tdt degrees / degrees mice, TCRAV diversity is one order of magnitude lower than the TCRBV diversity. In Tdt degrees / degrees animals, TCRBV chain diversity is reduced 10-fold compared with wild-type mice. In addition, in Tdt degrees / degrees mice, one BV chain can associate with three to four AV chains as in wild-type mice. The alpha/beta repertoire size in Tdt degrees / degrees mice is estimated to be 10(5) distinct receptors, approximately 5-10% of that calculated for wild-type mice. Thus, while Tdt activity is not involved in the combinatorial diversity resulting from alpha/beta pairing, it contributes to at least 90% of TCRalpha/beta diversity.
Collapse
Affiliation(s)
- J P Cabaniols
- Unité de Biologie Moléculaire du Gène, Institut National de la Sante et de la Recherche Medicale U277, Institut Pasteur, 75 724 Paris, France
| | | | | | | | | |
Collapse
|
63
|
McHugh RS, Shevach EM, Margulies DH, Natarajan K. A T cell receptor transgenic model of severe, spontaneous organ-specific autoimmunity. Eur J Immunol 2001; 31:2094-103. [PMID: 11449363 DOI: 10.1002/1521-4141(200107)31:7<2094::aid-immu2094>3.0.co;2-s] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The development of mouse models of human organ-specific autoimmune diseases has been hampered by the need to immunize mice with autoantigens in potent adjuvants. Even autoantigen-specific T cell receptor transgenic models of autoimmunity have proven to be complex as the transgenic mice frequently fail to develop disease spontaneously. We have isolated a CD4(+) T cell clone (TxA23)that recognizes the gastric parietal cell antigen, H/K ATPase alpha-chain(630-641), from a mouse with autoimmune gastritis that developed after thymectomy on day 3 of life. The T cell receptor alpha and beta genes from this clone were used to generate A23 transgenic mice. All A23 transgenic animals spontaneously developed severe autoimmune gastritis, and evidence of disease was detected as early as day 10 of life. Gastritis could be transferred to immunocompromised mice with a limited number of transgenic thymocytes (10(3)), but as many as 10(7) induced only mild disease in wild-type animals. Due to the complete penetrance of spontaneous disease, identity of the auto-antigen, susceptibility to immunoregulation, and close relation to autoimmune gastritis in man, A23 transgenic mice represent a unique CD4(+) T cell-mediated disease model for understanding the multiple factors regulating organ-specific autoimmunity.
Collapse
Affiliation(s)
- R S McHugh
- Cellular Immunology Section, Laboratory of Immunology, NIAID, NIH, Bethesda, MD, USA
| | | | | | | |
Collapse
|
64
|
Purugganan MM, Shah S, Kearney JF, Roth DB. Ku80 is required for addition of N nucleotides to V(D)J recombination junctions by terminal deoxynucleotidyl transferase. Nucleic Acids Res 2001; 29:1638-46. [PMID: 11266568 PMCID: PMC31272 DOI: 10.1093/nar/29.7.1638] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
V(D)J recombination generates a remarkably diverse repertoire of antigen receptors through the rearrangement of germline DNA. Terminal deoxynucleotidyl transferase (TdT), a polymerase that adds random nucleotides (N regions) to recombination junctions, is a key enzyme contributing to this diversity. The current model is that TdT adds N regions during V(D)J recombination by random collision with the DNA ends, without a dependence on other cellular factors. We previously demonstrated, however, that V(D)J junctions from Ku80-deficient mice unexpectedly lack N regions, although the mechanism responsible for this effect remains undefined in the mouse system. One possibility is that junctions are formed in these mice during a stage in development when TdT is not expressed. Alternatively, Ku80 may be required for the expression, nuclear localization or enzymatic activity of TdT. Here we show that V(D)J junctions isolated from Ku80-deficient fibroblasts are devoid of N regions, as were junctions in Ku80-deficient mice. In these cells TdT protein is abundant at the time of recombination, localizes properly to the nucleus and is enzymatically active. Based on these data, we propose that TdT does not add to recombination junctions through random collision but is actively recruited to the V(D)J recombinase complex by Ku80.
Collapse
Affiliation(s)
- M M Purugganan
- Department of Immunology, M929, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX 77030, USA
| | | | | | | |
Collapse
|
65
|
Ruiz JF, Domínguez O, Laín de Lera T, Garcia-Díaz M, Bernad A, Blanco L. DNA polymerase mu, a candidate hypermutase? Philos Trans R Soc Lond B Biol Sci 2001; 356:99-109. [PMID: 11205337 PMCID: PMC1087697 DOI: 10.1098/rstb.2000.0754] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A novel DNA polymerase (Pol mu) has been recently identified in human cells. The amino-acid sequence of Pol mu is 42% identical to that of terminal deoxynucleotidyl transferase (TdT), a DNA-independent DNA polymerase that contributes to antigen-receptor diversity. In this paper we review the evidence supporting the role of Pol mu in somatic hypermutation of immunoglobulin genes, a T-dependent process that selectively occurs at germinal centres: (i) preferential expression in secondary lymphoid organs; (ii) expression associated to developing germinal centres; and (iii) very low base discrimination during DNA-dependent DNA polymerization by Pol mu, a mutator phenotype enormously accentuated by the presence of activating Mn2+ ions. Moreover, its similarity to TdT, together with extrapolation to the crystal structure of DNA polymerase beta complexed (Pol beta) with DNA, allows us to discuss the structural basis for the unprecedented error proneness of Pol mu, and to predict that Pol mu is structurally well suited to participate also in DNA end-filling steps occurring both during V(D)J recombination and repair of DNA double-strand breaks that are processed by non-homologous end-joining.
Collapse
Affiliation(s)
- J F Ruiz
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autónoma, Madrid, Spain
| | | | | | | | | | | |
Collapse
|
66
|
Abstract
The durability of declarative memory suggests that it has either a chemical or a structural basis. Current models of long-term memory are based on the general assumption that traces of memory are stored by structural modifications of synaptic connections, resulting in alterations in the patterns of neural activity. Changes in gene expression, regulated at both the transcriptional and the translational levels, are considered essential for structural synaptic modifications. Here we present an alternative hypothesis stating that permanent memory has a chemical rather than a structural basis. We suggest that the mechanism of memory coding in the brain is similar to that in the immune system so that the permanence of memories in the nervous system is ensured at the genomic level by a somatic recombination mechanism. Thus, we hypothesize that traces of permanent declarative memory might present within cerebral neurons in the form of novel proteins coded by the modified genes. This discussion is intended to provide evidence in support of a DNA recombination mechanism for memory storage in the brain and to stimulate further research working toward the evaluation of this hypothesis.
Collapse
Affiliation(s)
- S Peña De Ortiz
- Department of Biology, University of Puerto Rico Rio Piedras Campus, San Juan, Puerto Rico
| | | |
Collapse
|
67
|
García-Díaz M, Domínguez O, López-Fernández LA, de Lera LT, Saníger ML, Ruiz JF, Párraga M, García-Ortiz MJ, Kirchhoff T, del Mazo J, Bernad A, Blanco L. DNA polymerase lambda (Pol lambda), a novel eukaryotic DNA polymerase with a potential role in meiosis. J Mol Biol 2000; 301:851-67. [PMID: 10966791 DOI: 10.1006/jmbi.2000.4005] [Citation(s) in RCA: 214] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A new gene (POLL) encoding a novel DNA polymerase (Pol lambda) has been identified at mouse chromosome 19. Murine Pol lambda, consisting of 573 amino acid residues, has a 32% identity to Pol beta, involved in nuclear DNA repair in eukaryotic cells. It is interesting that Pol lambda contains all the critical residues involved in DNA binding, nucleotide binding and selection, and catalysis of DNA polymerization, that are conserved in Pol beta and other DNA polymerases belonging to family X. Murine Pol lambda, overproduced in Escherichia coli, displayed intrinsic DNA polymerase activity when assessed by in situ gel analysis. Pol lambda also conserves the critical residues of Pol beta required for its intrinsic deoxyribose phosphate lyase (dRPase) activity. The first 230 amino acid residues of Pol lambda, that have no counterpart in Pol beta, contain a BRCT domain, present in a variety of cell-cycle check-point control proteins responsive to DNA damage and proteins involved in DNA repair. Northern blotting, in situ hybridization analysis and immunostaining showed high levels of Pol lambda specifically expressed in testis, being developmentally regulated and mainly associated to pachytene spermatocytes. These first evidences, although indirect, suggest a potential role of Pol lambda in DNA repair synthesis associated with meiosis.
Collapse
Affiliation(s)
- M García-Díaz
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autónoma, Madrid, 28049, Spain
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
68
|
Tuaillon N, Capra JD. Evidence that terminal deoxynucleotidyltransferase expression plays a role in Ig heavy chain gene segment utilization. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 164:6387-97. [PMID: 10843694 DOI: 10.4049/jimmunol.164.12.6387] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
TdT is a nuclear enzyme that catalyzes the addition of random nucleotides at Ig and TCR V(D)J junctions. In this paper we analyze human IgH rearrangements generated from transgenic minilocus mice in the presence or absence of TdT. In the absence of TdT, the pseudo-VH gene segment present in the minilocus is rearranged dramatically more frequently. Additionally, JH6 gene segment utilization is increased as well as the number of rearrangements involving only VH and JH gene segments. Thus, the recombination of IgH gene segments that are flanked by 23-nt spacer recombination signal sequences may be influenced by TdT expression. Extensive analysis indicates that these changes are independent of antigenic selection and cannot be explained by homology-mediated recombination. Thus, the role played by TdT may be more extensive than previously thought.
Collapse
MESH Headings
- Animals
- Antibody Diversity/genetics
- Base Sequence
- Cloning, Molecular
- DNA Nucleotidylexotransferase/biosynthesis
- DNA Nucleotidylexotransferase/deficiency
- DNA Nucleotidylexotransferase/genetics
- DNA Nucleotidylexotransferase/physiology
- Gene Rearrangement, B-Lymphocyte, Heavy Chain
- Genetic Markers/immunology
- Humans
- Immunoglobulin Heavy Chains/blood
- Immunoglobulin Heavy Chains/genetics
- Immunoglobulin Heavy Chains/metabolism
- Immunoglobulin Joining Region/genetics
- Immunoglobulin Variable Region/genetics
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Molecular Sequence Data
- Receptors, Antigen, B-Cell/genetics
- Receptors, Antigen, B-Cell/metabolism
- Sequence Homology, Nucleic Acid
Collapse
Affiliation(s)
- N Tuaillon
- Molecualar Immunogenetics Program, Oklahoma Medical Research Foundation, Oklahoma City 73104, USA
| | | |
Collapse
|
69
|
Faber J, Kantarjian H, Roberts MW, Keating M, Freireich E, Albitar M. Terminal deoxynucleotidyl transferase-negative acute lymphoblastic leukemia. Arch Pathol Lab Med 2000; 124:92-7. [PMID: 10629138 DOI: 10.5858/2000-124-0092-tdtnal] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Terminal deoxynucleotidyl transferase (TdT) is a useful marker in the diagnosis of acute lymphoblastic leukemia (ALL) (French-American-British [FAB] L1 and L2) and is most useful in distinguishing ALL from mature B-lymphoid neoplasms, such as Burkitt lymphoma (FAB L3) and other lymphoid malignancies. The frequency of TdT-negative ALL is not known. Here we report 3 TdT-negative ALL cases that met the criteria for T-cell ALL. DESIGN We reviewed approximately 200 cases of ALL retrieved from the database at our institution. All cases were evaluated using Wright-Giemsa, myeloperoxidase, butyrate, and TdT staining; immunophenotyped using flow cytometry; and studied using Southern blot analyses for T-cell receptors and immunoglobulin gene rearrangement. RESULTS All ALL cases (L1 and L2) were TdT-positive, except for 3 cases that were of early T-cell lineage. None of the 3 cases demonstrated positivity for TdT in immunofluorescence staining with polyclonal antibodies or flow cytometry with monoclonal antibodies. Flow cytometric analysis confirmed a pre-T-cell immunophenotype in all 3 cases. One of the cases showed rearrangement of a T-cell antigen receptor and immunoglobulin heavy chain (J(H)). A second case showed germline configuration of T-cell receptors, but also showed rearrangement of the J(H), despite the expression of T-cell markers only.
Collapse
Affiliation(s)
- J Faber
- Division of Pathology and Laboratory Medicine, Section of Hematopathology, The University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA
| | | | | | | | | | | |
Collapse
|
70
|
Mickelsen S, Snyder C, Trujillo K, Bogue M, Roth DB, Meek K. Modulation of Terminal Deoxynucleotidyltransferase Activity by the DNA-Dependent Protein Kinase. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.163.2.834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Rare Ig and TCR coding joints can be isolated from mice that have a targeted deletion in the gene encoding the 86-kDa subunit of the Ku heterodimer, the regulatory subunit of the DNA-dependent protein kinase (DNA-PK). However in the coding joints isolated from Ku86−/− animals, there is an extreme paucity of N regions (the random nucleotides added during V(D)J recombination by the enzyme TdT). This finding is consistent with a decreased frequency of coding joints containing N regions isolated from C.B-17 SCID mice that express a truncated form of the catalytic subunit of the DNA-PK (DNA-PKCS). This finding suggests an unexpected role for DNA-PK in addition of N nucleotides to coding ends during V(D)J recombination. In this report, we establish that TdT forms a stable complex with DNA-PK. Furthermore, we show that DNA-PK modulates TdT activity in vitro by limiting both the length and composition of nucleotide additions.
Collapse
Affiliation(s)
- Scott Mickelsen
- *Harold C. Simmons Arthritis Research Center and Departments of Internal Medicine and Microbiology, University of Texas Southwestern Medical Center, Dallas, TX 75235
| | - Carolyn Snyder
- *Harold C. Simmons Arthritis Research Center and Departments of Internal Medicine and Microbiology, University of Texas Southwestern Medical Center, Dallas, TX 75235
| | - Kelly Trujillo
- †Department of Molecular Medicine, Institute for Biotechnology, University of Texas Health Science Center, San Antonio, TX 78245; and
| | - Molly Bogue
- ‡Department of Microbiology and Immunology and
| | - David B. Roth
- ‡Department of Microbiology and Immunology and
- §Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030
| | - Katheryn Meek
- *Harold C. Simmons Arthritis Research Center and Departments of Internal Medicine and Microbiology, University of Texas Southwestern Medical Center, Dallas, TX 75235
| |
Collapse
|
71
|
Conde C, Weller S, Gilfillan S, Marcellin L, Martin T, Pasquali JL. Terminal Deoxynucleotidyl Transferase Deficiency Reduces the Incidence of Autoimmune Nephritis in (New Zealand Black × New Zealand White)F1 Mice. THE JOURNAL OF IMMUNOLOGY 1998. [DOI: 10.4049/jimmunol.161.12.7023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Abstract
Terminal deoxynucleotidyl transferase (TdT) enzyme activity in lymphocytes generates diversity in the Ag receptor repertoires by adding template-independent N nucleotides and disrupting homology-directed rearrangements. The importance of this diversity in vivo and the significance of the suppression of TdT during fetal life remain uncertain. Previous studies have shown that in TdT knockout mice (TdT°) 1) the T cell repertoire is less peptide oriented; and 2) natural autoantibody, particularly anti-DNA autoantibodies, are less polyreactive, and their mean affinities are reduced. Consequently, the suppression of TdT during early T/B cell ontogeny may participate in controlling autoimmunity. To study the impact of TdT suppression in autoimmune-prone mice, we introduced the TdT null mutation into the (NZB × NZW)F1 (B/W) mouse strain. We show that TdT deficiency significantly reduces the incidence of autoimmune nephritis and prolongs survival compared with those in control mice. Surprisingly, the long-term survivor TdT° mice produced amounts of anti-ADN and anti-histone autoantibodies similar to those of their TdT+ littermates. However, these TdT° mice showed no evidence of renal inflammation, and the immune deposits were restricted to the mesangium, whereas basal membrane deposits were clearly correlated with overt renal disease. The present study supports the idea that the absence of TdT enzyme activity in lymphocytes protects mice against autoimmunity and could offer a therapeutic approach to autoimmune diseases. Moreover, our results may help to unravel the mechanisms of lupus nephritis.
Collapse
Affiliation(s)
- Carmen Conde
- *Laboratory of Immunopathology, Institute of Immuno-Hematology, Central Hospital, and
| | - Sandra Weller
- *Laboratory of Immunopathology, Institute of Immuno-Hematology, Central Hospital, and
| | | | - Luc Marcellin
- †Department of Pathology, Hautepierre Hospital, University Hospitals of Strasbourg, Strasbourg, France; and
| | - Thierry Martin
- *Laboratory of Immunopathology, Institute of Immuno-Hematology, Central Hospital, and
| | - Jean-Louis Pasquali
- *Laboratory of Immunopathology, Institute of Immuno-Hematology, Central Hospital, and
| |
Collapse
|
72
|
Hagmann M, Bruggmann R, Xue L, Georgiev O, Schaffner W, Rungger D, Spaniol P, Gerster T. Homologous recombination and DNA-end joining reactions in zygotes and early embryos of zebrafish (Danio rerio) and Drosophila melanogaster. Biol Chem 1998; 379:673-81. [PMID: 9687016 DOI: 10.1515/bchm.1998.379.6.673] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A linear DNA with partial sequence redundancy can be recircularized in cells by either nonhomologous end joining (NEJ) or by homologous recombination (HR). We have studied the relative contributions of these processes in zygotes or early embryos of species that serve as model organisms for developmental genetics. Thus, we have microinjected a linearized plasmid substrate into zygotes of zebrafish (Danio rerio) or into the posterior end of Drosophila melanogaster early embryos before pole cell formation. Similar to the situation observed previously in Xenopus zygotes/early embryos, we detected a large preponderance of DNA-end joining over homologous recombination. A comparison of end-joined junctions revealed that from the three species tested, zebrafish introduced the least number of sequence distortions upon DNA-end joining, while Drosophila produced the largest deletions (average 14 bp) with occasional nucleotide patch insertions, reminiscent of the N nucleotides at V(D)J junctions in mammalian immune receptor genes. Double-strand gap repair by homologous sequences ('homologous recombination') involving a bimolecular reaction was readily detectable in both zebrafish and Drosophila. This involved specifically designed recombination substrates consisting of a mutagenized linear plasmid and DNA fragments carrying the wild-type sequence. Our results show that the basic machinery for homologous recombination is present at early developmental stages of these two genetic model organisms. However, it seems that for any experimental exploitation, such as targeted gene disruption, one would have to inhibit or bypass the overwhelming DNA-end joining activity.
Collapse
Affiliation(s)
- M Hagmann
- Institut für Molekularbiologie (Abteilung II), Universität Zürich, Switzerland
| | | | | | | | | | | | | | | |
Collapse
|
73
|
Rodewald HR, Haller C. Antigen-receptor junctional diversity in growth-factor-receptor mutant mice. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 1998; 22:351-365. [PMID: 9700464 DOI: 10.1016/s0145-305x(98)00013-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Precursor lymphocytes undergo expansion prior to immunoglobulin (Ig) or T cell receptor (TCR) rearrangements. Development of thymocytes, but not B cells, is entirely blocked in mice lacking both the receptor-tyrosine-kinase c-kit and the common cytokine receptor gamma chain (gamma c). In c-kit-gamma c-mice, TCR beta rearrangements are limited to mono- or oligoclonal DJ junctions. Here, effects of lack of c-kit or gamma c, or both, on the junctional diversity of TCR gamma and delta, and Ig VH(DH)JH loci were analyzed. All rearrangements were present in wildtype and mutant mice. However, sequencing of the junctions revealed monoclonal TCR gamma (V gamma 2 J gamma 1) and TCR delta (V delta 1(D delta)J delta 2) joints in c-kit-gamma c-, but not c-kit+ gamma c- or wildtype thymocytes. In contrast to TCR beta, gamma and delta loci, VHDHJH junctions were more diverse in c-kit-gamma c-mice. Thus, the two analyzed growth factor receptors mediate signaling pathways required for progenitor expansion and generation of junctional diversity at TCR loci, but have less influence on the diversity of IgH junctions.
Collapse
MESH Headings
- Animals
- Female
- Gene Rearrangement, T-Lymphocyte
- Genes, Immunoglobulin
- Genetic Variation
- Growth Substances/physiology
- Immunoglobulin Joining Region/genetics
- Immunoglobulin Variable Region/genetics
- Immunoglobulin delta-Chains/genetics
- Immunoglobulin gamma-Chains/genetics
- Male
- Mice
- Mice, Inbred BALB C
- Mice, Mutant Strains
- Proto-Oncogene Proteins c-kit/genetics
- Proto-Oncogene Proteins c-kit/physiology
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, gamma-delta/genetics
- Receptors, Antigen, T-Cell, gamma-delta/physiology
- Spleen
- Thymus Gland
Collapse
Affiliation(s)
- H R Rodewald
- Basel Institute for Immunology, Basel, Switzerland.
| | | |
Collapse
|
74
|
Fehling HJ, Gilfillan S, Ceredig R. αβ/γδ Lineage Commitment in the Thymus of Normal and Genetically Manipulated Mice. Adv Immunol 1998. [DOI: 10.1016/s0065-2776(08)60399-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
|
75
|
Merkenschlager M, Graf D, Lovatt M, Bommhardt U, Zamoyska R, Fisher AG. How many thymocytes audition for selection? J Exp Med 1997; 186:1149-58. [PMID: 9314563 PMCID: PMC2199071 DOI: 10.1084/jem.186.7.1149] [Citation(s) in RCA: 175] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
T cell maturation requires the rearrangement of clonotypic T cell receptors (TCR) capable of interacting with major histocompatibility complex (MHC) ligands to initiate positive and negative selection. Only 3-5% of thymocytes mature to join the peripheral T cell pool. To investigate the basis for this low success rate, we have measured the frequency of preselection thymocytes capable of responding to MHC. As many as one in five MHC-naive thymocytes show upregulation of activation markers on exposure to MHC-expressing thymic stroma in short-term reaggregate culture. The majority of these cells display physiological changes consistent with entry into the selection process within 24 h. By exposing TCR transgenic thymocytes to a range of MHC-peptide complexes, we show that CD69 induction is indicative of thymocyte selection, positive or negative. Our data provide evidence that the fraction of thymocytes that qualify to enter the thymic selection process far exceeds the fraction that successfully complete it, and suggest that most MHC-reactive thymocytes are actively eliminated in the course of selection.
Collapse
MESH Headings
- Animals
- Antigens, CD/biosynthesis
- Antigens, CD/immunology
- Antigens, Differentiation, T-Lymphocyte/biosynthesis
- Antigens, Differentiation, T-Lymphocyte/immunology
- CD4-Positive T-Lymphocytes/immunology
- CD8-Positive T-Lymphocytes/immunology
- Cells, Cultured
- Clonal Deletion
- DNA Primers
- DNA-Binding Proteins/immunology
- Gene Expression Regulation
- Histocompatibility Antigens Class I/immunology
- Histocompatibility Antigens Class I/metabolism
- Histocompatibility Antigens Class II/immunology
- Histocompatibility Antigens Class II/metabolism
- Homeodomain Proteins
- Lectins, C-Type
- Lymphocyte Activation
- Major Histocompatibility Complex/immunology
- Mice
- Polymerase Chain Reaction
- Receptors, Antigen, T-Cell/genetics
- Receptors, Antigen, T-Cell/immunology
- Selection, Genetic
- T-Lymphocytes/cytology
- T-Lymphocytes/immunology
- Thymus Gland/embryology
- Thymus Gland/immunology
Collapse
Affiliation(s)
- M Merkenschlager
- Lymphocyte Development Group, Medical Research Council Clinical Sciences Centre, Royal Postgraduate Medical School, Hammersmith Hospital, London W12 0NN, United Kingdom.
| | | | | | | | | | | |
Collapse
|
76
|
Bogue MA, Wang C, Zhu C, Roth DB. V(D)J recombination in Ku86-deficient mice: distinct effects on coding, signal, and hybrid joint formation. Immunity 1997; 7:37-47. [PMID: 9252118 DOI: 10.1016/s1074-7613(00)80508-7] [Citation(s) in RCA: 125] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Ku, a heterodimer of 70 and 86 kDa subunits, plays a critical but poorly understood role in V(D)J recombination. Although Ku86-deficient mice are defective in coding and signal joint formation, rare recombination products have been detected by PCR. Here, we report nucleotide sequences of 99 junctions from Ku86-deficient mice. Over 90% of the coding joints, but not signal or hybrid joints, exhibit short sequence homologies, indicating that homology is required to join coding ends in the absence of Ku86. Our results suggest that Ku86 may normally have distinct functions in the formation of these different types of junctions. Furthermore, Ku86(-/-) joints are unexpectedly devoid of N-region diversity, suggesting a novel role for Ku in the addition of N nucleotides by terminal deoxynucleotidyl transferase.
Collapse
MESH Headings
- Animals
- Antigens, Nuclear
- Base Sequence
- Bone Marrow Cells
- DNA Helicases
- DNA Nucleotidylexotransferase/metabolism
- DNA Repair
- DNA-Binding Proteins/physiology
- Gene Rearrangement
- Gene Rearrangement, T-Lymphocyte
- Immunoglobulin Heavy Chains/genetics
- Immunoglobulin Heavy Chains/metabolism
- Immunoglobulin Joining Region/genetics
- Immunoglobulin Joining Region/metabolism
- Ku Autoantigen
- Mice
- Mice, SCID
- Molecular Sequence Data
- Nuclear Proteins/physiology
- Polymerase Chain Reaction
- Receptors, Antigen, T-Cell, gamma-delta/genetics
- Receptors, Antigen, T-Cell, gamma-delta/metabolism
- Recombination, Genetic
- Stem Cells/metabolism
- Transcription Factors/deficiency
- Transcription Factors/physiology
Collapse
Affiliation(s)
- M A Bogue
- Department of Microbiology and Immunology, Baylor College of Medicine, Houston, Texas 77030, USA
| | | | | | | |
Collapse
|
77
|
Rodewald HR, Ogawa M, Haller C, Waskow C, DiSanto JP. Pro-thymocyte expansion by c-kit and the common cytokine receptor gamma chain is essential for repertoire formation. Immunity 1997; 6:265-72. [PMID: 9075927 DOI: 10.1016/s1074-7613(00)80329-5] [Citation(s) in RCA: 160] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Growth factors have been implicated in thymocyte development, but mutants lacking cytokines, or their receptors, have failed to reveal essential roles for growth/differentiation factors in the thymus. Mutations in the receptor tyrosine kinase c-kit and the common cytokine receptor gamma chain (gamma c) reduce cellularity, but are permissive for thymocyte development. We now report that thymocyte development is completely abrogated in mice lacking both c-kit and gamma c (c-kit-gamma c-). Thymic hypocellularity is so severe that the T cell receptor repertoire fails to form except for monoclonal or oligoclonal beta chain DJ rearrangements. B lymphopoiesis is only mildly reduced in c-kit-gamma c- as compared with c-kit+gamma c- mice, and hematological values are identical comparing c-kit-deficient and c-kit-gamma c- mice. These experiments reveal essential, overlapping, and synergistic functions for two distinct signaling pathways, one utilizing c-kit and the other cytokine receptor gamma c complexes coupling to Janus kinases and signal transducers and activators of transcription.
Collapse
|