101
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Shiomi N, Mori M, Kito S, Harada YN, Tanaka K, Shiomi T. Severe growth retardation and short life span of double-mutant mice lacking Xpa and exon 15 of Xpg. DNA Repair (Amst) 2005; 4:351-7. [PMID: 15661658 DOI: 10.1016/j.dnarep.2004.10.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2004] [Indexed: 11/26/2022]
Abstract
In addition to xeroderma pigmentosum (XP), mutations in the human XPG gene cause an early onset of Cockayne syndrome (CS) in some patients (XP-G/CS) with characteristics, such as growth retardation and a short life span. In the previous studies, we generated four Xpg mutant mice with two different C-terminal truncations, null, or a base substitution mutation to identify the protein region that causes the onset of CS, and found that the CS-causing mutations, null or a deletion of the last 360 amino acids, completely inhibited the NER activity of mouse XPG (Xpg), but the non-CS-causing mutations, XpgD811A (base substitution that eliminates the nuclease activity of Xpg) or XpgDeltaex15 (deletion of the exon 15 corresponding to the last 183 amino acids), resulted in the retention of residual NER activity. To understand why mutations that completely eliminate the NER activity of Xpg cause CS but those that abolish the nuclease activity without totally eliminating the NER activity of Xpg do not result in CS, we made a series of Xpg mutant mice with Xpa-null mutant allele and found that mice with the non-CS-causing deletion mutation (XpgDeltaex15) exhibited the CS phenotype when XPA was also absent but the base substitution mutation (XpgD811A) that eliminated the Xpg nuclease activity did not. These results indicate that Xpg has a second function, beside NER, and that the disruption of this second function (deletion of the last 183 amino acids) when combined with an NER defect causes CS. When we compared amino acid sequences corresponding to the exon 15 of Xpg, a significant homology was conserved among vertebrates, but not in Drosophila and Saccharomyces cerevisiae. These observations suggest that the second function of XPG may be conserved only in vertebrates and CS symptoms may occur in its absence.
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Affiliation(s)
- Naoko Shiomi
- Research Center for Radiation Safety, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
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102
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Armelini MG, Muotri AR, Marchetto MCN, de Lima-Bessa KM, Sarasin A, Menck CFM. Restoring DNA repair capacity of cells from three distinct diseases by XPD gene-recombinant adenovirus. Cancer Gene Ther 2005; 12:389-96. [PMID: 15650764 DOI: 10.1038/sj.cgt.7700797] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The nucleotide excision repair (NER) is one of the major human DNA repair pathways. Defects in one of the proteins that act in this system result in three distinct autosomal recessive syndromes: xeroderma pigmentosum (XP), Cockayne syndrome (CS) and trichothiodystrophy (TTD). TFIIH is a nine-protein complex essential for NER activity, initiation of RNA polymerase II transcription and with a possible role in cell cycle regulation. XPD is part of the TFIIH complex and has a helicase function, unwinding the DNA in the 5' --> 3' direction. Mutations in the XPD gene are found in XP, TTD and XP/CS patients, the latter exhibiting both XP and CS symptoms. Correction of DNA repair defects of these cells by transducing the complementing wild-type gene is one potential strategy for helping these patients. Over the last years, adenovirus vectors have been largely used in gene delivering because of their efficient transduction, high titer, and stability. In this work, we present the construction of a recombinant adenovirus carrying the XPD gene, which is coexpressed with the EGFP reporter gene by an IRES sequence, making it easier to follow cell infection. Infection by this recombinant adenovirus grants full correction of SV40-transformed and primary skin fibroblasts obtained from XP-D, TTD and XP/CS patients.
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Affiliation(s)
- Melissa Gava Armelini
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo 05508-900 SP, Brazil
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103
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Abstract
Cells induce the expression of DNA-repair enzymes, activate cell-cycle checkpoints and, under some circumstances, undergo apoptosis in response to DNA-damaging agents. The mechanisms by which these cellular responses are triggered are not well understood, but there is recent evidence that the transcription machinery might be used in DNA-damage surveillance and in triggering DNA-damage responses to suppress mutagenesis. Transcription might also act as a DNA-damage dosimeter where the severity of blockage determines whether or not to induce cell death. Could transcription therefore be a potential therapeutic target for anticancer strategies?
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Affiliation(s)
- Mats Ljungman
- Department of Radiation Oncology, Division of Radiation and Cancer Biology, University of Michigan Comprehensive Cancer Center, University of Michigan Medical School, University of Michigan, Ann Arbor, Michigan 48109-0936, USA.
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104
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Shiomi N, Kito S, Oyama M, Matsunaga T, Harada YN, Ikawa M, Okabe M, Shiomi T. Identification of the XPG region that causes the onset of Cockayne syndrome by using Xpg mutant mice generated by the cDNA-mediated knock-in method. Mol Cell Biol 2004; 24:3712-9. [PMID: 15082767 PMCID: PMC387744 DOI: 10.1128/mcb.24.9.3712-3719.2004] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2003] [Revised: 10/22/2003] [Accepted: 01/26/2004] [Indexed: 12/23/2022] Open
Abstract
In addition to xeroderma pigmentosum (XP), mutations in the human XPG gene cause early onset of Cockayne syndrome (CS) in some patients (XPG/CS). The CS-causing mutations in such patients all produce truncated XPG proteins. To test the hypothesis that the CS phenotype, with characteristics such as growth retardation and a short life span in XPG/CS patients, results from C-terminal truncations, we constructed mutants with C-terminal truncations in mouse XPG (Xpg) (from residue D811 to the stop codon [XpgD811stop] and deletion of exon 15 [Xpg Delta ex15]). In the XpgD811stop and Xpg Delta ex15 mutations, the last 360 and 183 amino acids of the protein were deleted, respectively. To generate Xpg mutant mice, we devised the shortcut knock-in method by replacing genomic DNA with a mutated cDNA fragment (cDNA-mediated knock in). The control mice, in which one-half of Xpg genomic DNA fragment was replaced with a normal Xpg cDNA fragment, had a normal growth rate, a normal life span, normal sensitivity to UV light, and normal DNA repair ability, indicating that the Xpg gene partially replaced with the normal cDNA fragment retained normal functions. The XpgD811stop homozygous mice exhibited growth retardation and a short life span, but the Xpg Delta ex15 homozygous mice did not, indicating that deletion of the last 360 amino acids results in the CS phenotype but deletion of the last 183 amino acids does not. The XpgD811stop homozygous mice, however, exhibited a slightly milder CS phenotype than did the Xpg null mutant mice, indicating that the XpgD811stop protein still retains some Xpg function that affects the severity of the CS phenotype.
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Affiliation(s)
- Naoko Shiomi
- Research Center for Radiation Safety, National Institute of Radiological Sciences, Inage-ku, Chiba 263-8555, Japan
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105
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Hasty P, Vijg J. Accelerating aging by mouse reverse genetics: a rational approach to understanding longevity. Aging Cell 2004; 3:55-65. [PMID: 15038819 DOI: 10.1111/j.1474-9728.2004.00082.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Investigating the molecular basis of aging has been difficult, primarily owing to the pleiotropic and segmental nature of the aging phenotype. There are many often interacting symptoms of aging, some of which are obvious and appear to be common to every aged individual, whereas others affect only a subset of the elderly population. Although at first sight this would suggest multiple molecular mechanisms of aging, there now appears to be almost universal consensus that aging is ultimately the result of the accumulation of somatic damage in cellular macromolecules, with reactive oxygen species likely to be the main damage-inducing agent. What remains significant is unravelling how such damage can give rise to the large variety of aging symptoms and how these can be controlled. Although humans, with over a century of clinical observations, remain the obvious target of study, the mouse, with a relatively short lifespan, easy genetic accessibility and close relatedness to humans, is the tool par excellence to model aging-related phenotypes and test strategies of intervention. Here we present the argument that mouse models with engineered defects in genome maintenance systems are especially important because they often exhibit a premature appearance of aging symptoms. Confirming studies on human segmental progeroid syndromes, most of which are based on heritable mutations in genes involved in genome maintenance, the results thus far obtained with mouse models strongly suggest that lifespan and onset of aging are directly related to the quality of DNA metabolism. This may be in keeping with the recent discovery of a possible 'universal survival' pathway that improves antioxidant defence and genome maintenance and simultaneously extends lifespan in the mouse and several invertebrate species.
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Affiliation(s)
- Paul Hasty
- Department of Molecular Medicine, University of Texas Health Science Center, San Antonio, TX 78245, USA
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106
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Itoh T, Cado D, Kamide R, Linn S. DDB2 gene disruption leads to skin tumors and resistance to apoptosis after exposure to ultraviolet light but not a chemical carcinogen. Proc Natl Acad Sci U S A 2004; 101:2052-7. [PMID: 14769931 PMCID: PMC357050 DOI: 10.1073/pnas.0306551101] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2003] [Indexed: 11/18/2022] Open
Abstract
Mutations in the human DDB2 gene give rise to xeroderma pigmentosum group E, a disease characterized by increased skin tumorigenesis in response to UV-irradiation. Cell strains derived from xeroderma pigmentosum group E individuals also have enhanced resistance to UV-irradiation due to decreased p53-mediated apoptosis. To further address the precise function(s) of DDB2 and the consequence of non-naturally occurring DDB2 mutations, we generated mice with a disruption of the gene. The mice exhibited significantly enhanced skin carcinogenesis in response to UV-irradiation, and cells from the DDB2(-/-) mice were abnormally resistant to killing by the radiation and had diminished UV-induced, p53-mediated apoptosis. Notably, the cancer-prone phenotype and the resistance to cellular killing were not observed after exposure to the chemical carcinogen, 7,12-dimethylbenz[a]anthracene (DMBA), to which mice carrying defective nucleotide excision repair genes respond with enhanced tumors and cell killing. Although cells from heterozygous DDB2(+/-) mice appeared normal, these mice had enhanced skin carcinogenesis after UV-irradiation, so that XP-E heterozygotes might be at risk for carcinogenesis. In sum, these results demonstrate that DDB2 is well conserved between humans and mice and functions as a tumor suppressor, at least in part, by controlling p53-mediated apoptosis after UV-irradiation.
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Affiliation(s)
- Toshiki Itoh
- Divisions of Biochemistry and Molecular Biology, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3202, USA. toshiki@
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107
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Wijnhoven SWP, van Steeg H. Transgenic and knockout mice for DNA repair functions in carcinogenesis and mutagenesis. Toxicology 2003; 193:171-87. [PMID: 14599776 DOI: 10.1016/s0300-483x(03)00295-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Genetically modified mouse models with defects in DNA repair pathways, especially in nucleotide excision repair (NER) and mismatch repair (MMR), are powerful tools to study processes like carcinogenesis and mutagenesis. The use of mutant mice in these studies has many advantages over using normal wild type mice with respect to costs, number of animals, predictive value towards carcinogenic compounds and the duration of study. Short-term carcinogenicity assays still require considerable number of animals and extensive pathological analyses. Therefore, alternatives demanding less animals and shorter exposure times would be desirable. In this respect, one approach could be the use of transgenic mice harbouring marker genes, that can easily detect mutagenic features of carcinogenic compounds, especially when such models are in a DNA repair deficient background. Here, we review the progress made in the development and use of DNA repair deficient mouse models as replacements for long-term cancer assays and discuss the applicability of enhanced gene mutant frequencies as early indicators of tumourigenesis. Although promising models exist, there is still a need for more universally responding and highly sensitive mouse models, since it is likely that non-genotoxic carcinogens will go undetected in a DNA repair deficient mouse. One attractive candidate mouse model, having a presumptive broad detective range, is the Xpa/p53 mutant mouse model, which will be discussed in more detail.
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Affiliation(s)
- Susan W P Wijnhoven
- National Institute of Public Health and Environment, RIVM/TOX pb12, P.O. Box 1, 3720 BA Bilthoven, The Netherlands.
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108
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Liu Z, Hong SW, Escobar M, Vierling E, Mitchell DL, Mount DW, Hall JD. Arabidopsis UVH6, a homolog of human XPD and yeast RAD3 DNA repair genes, functions in DNA repair and is essential for plant growth. PLANT PHYSIOLOGY 2003; 132:1405-14. [PMID: 12857822 PMCID: PMC167080 DOI: 10.1104/pp.103.021808] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2003] [Revised: 03/30/2003] [Accepted: 04/17/2003] [Indexed: 05/18/2023]
Abstract
To evaluate the genetic control of stress responses in Arabidopsis, we have analyzed a mutant (uvh6-1) that exhibits increased sensitivity to UV light, a yellow-green leaf coloration, and mild growth defects. We have mapped the uvh6-1 locus to chromosome I and have identified a candidate gene, AtXPD, within the corresponding region. This gene shows sequence similarity to the human (Homo sapiens) XPD and yeast (Saccharomyces cerevisiae) RAD3 genes required for nucleotide excision repair. We propose that UVH6 is equivalent to AtXPD because uvh6-1 mutants carry a mutation in a conserved residue of AtXPD and because transformation of uvh6-1 mutants with wild-type AtXPD DNA suppresses both UV sensitivity and other defective phenotypes. Furthermore, the UVH6/AtXPD protein appears to play a role in repair of UV photoproducts because the uvh6-1 mutant exhibits a moderate defect in the excision of UV photoproducts. This defect is also suppressed by transformation with UVH6/AtXPD DNA. We have further identified a T-DNA insertion in the UVH6/AtXPD gene (uvh6-2). Plants carrying homozygous insertions were not detected in analyses of progeny from plants heterozygous for the insertion. Thus, homozygous insertions appear to be lethal. We conclude that the UVH6/AtXPD gene is required for UV resistance and is an essential gene in Arabidopsis.
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Affiliation(s)
- Zongrang Liu
- Departments of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721, USA
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109
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Dubaele S, Proietti De Santis L, Bienstock RJ, Keriel A, Stefanini M, Van Houten B, Egly JM. Basal transcription defect discriminates between xeroderma pigmentosum and trichothiodystrophy in XPD patients. Mol Cell 2003; 11:1635-46. [PMID: 12820975 DOI: 10.1016/s1097-2765(03)00182-5] [Citation(s) in RCA: 154] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mutations in the XPD gene result in xeroderma pigmentosum (XP) and trichothiodystrophy (TTD), the phenotypes of which are often intricate. To understand the genotype/phenotype relationship, we engineered recombinant TFIIHs in which XPD subunits carry amino acid changes found in XPD patients. We demonstrate that all the XPD mutations are detrimental for XPD helicase activity, thus explaining the NER defect. We also show that TFIIH from TTD patients, but not from XP patients, exhibits a significant in vitro basal transcription defect in addition to a reduced intracellular concentration. Moreover, when XPD mutations prevent interaction with the p44 subunit of TFIIH, transactivation directed by certain nuclear receptors is inhibited, regardless of TTD versus XP phenotype, thus explaining the overlapping symptoms. The implications of these mutations are discussed using a structural model of the XPD protein. Our study provides explanations for the nature and the severity of the various clinical features.
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Affiliation(s)
- Sandy Dubaele
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, BP 10142, 67404 Illkirch Cedex, C.U. Strasbourg, France
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110
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Mitchell JR, Hoeijmakers JHJ, Niedernhofer LJ. Divide and conquer: nucleotide excision repair battles cancer and ageing. Curr Opin Cell Biol 2003; 15:232-40. [PMID: 12648680 DOI: 10.1016/s0955-0674(03)00018-8] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Protection from cancer and ensured longevity are tightly linked in mammals. One of the fundamental mechanisms contributing to both is the cellular response to DNA damage. The appropriate response is an initial attempt at repair, but if the damage is too extensive or compromises DNA metabolism, a signalling cascade triggers cellular senescence or death. Evidence in mice and humans suggests a division of tasks amongst DNA repair pathways: transcription-coupled repair and interstrand crosslink repair of cytotoxic lesions are predominantly responsible for longevity assurance, whereas excision repair of mutagenic lesions provides protection against cancer. Similarly, the signalling component of the DNA-damage response might contribute unequally to organismal outcomes depending on its set point: an inadequate response to DNA damage sanctions carcinogenesis but might limit local ageing, whereas overzealous signalling provides cancer protection but accelerates ageing.
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Affiliation(s)
- James R Mitchell
- Department of Cell Biology and Genetics, Erasmus University Rotterdam, PO Box 1738, 3000 DR, Rotterdam, The Netherlands
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111
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Merino C, Reynaud E, Vázquez M, Zurita M. DNA repair and transcriptional effects of mutations in TFIIH in Drosophila development. Mol Biol Cell 2002; 13:3246-56. [PMID: 12221129 PMCID: PMC124156 DOI: 10.1091/mbc.e02-02-0087] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Mutations in XPB and XPD TFIIH helicases have been related with three hereditary human disorders: xeroderma pigmentosum, Cockayne syndrome, and trichothiodystrophy. The dual role of TFIIH in DNA repair and transcription makes it difficult to discern which of the mutant TFIIH phenotypes is due to defects in any of these different processes. We used haywire (hay), the Drosophila XPB homolog, to dissect this problem. Our results show that when hay dosage is affected, the fly shows defects in structures that require high levels of transcription. We found a genetic interaction between hay and cdk7, and we propose that some of these phenotypes are due to transcriptional deficiencies. We also found more apoptotic cells in imaginal discs and in the CNS of hay mutant flies than in wild-type flies. Because this abnormal level of apoptosis was not detected in cdk7 flies, this phenotype could be related to defects in DNA repair. In addition the apoptosis induced by p53 Drosophila homolog (Dmp53) is suppressed in heterozygous hay flies.
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Affiliation(s)
- Carlos Merino
- Department of Genetics and Molecular Physiology, Institute of Biotechnology, Universidad Nacional Autónoma de México, Morelos 62250, México
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112
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Abstract
Trichothiodystrophy (TTD) is a complex disorder caused by mutations in the XPD gene which affect both DNA repair and transcription. A mouse with a TTD mutation has now been found to display remarkable signs of premature ageing.
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Affiliation(s)
- Alan Lehmann
- Genome Damage and Stability Centre, University of Sussex, Falmer, BN1 9RQ, Brighton, UK.
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113
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Cancrini C, Romiti ML, Di Cesare S, Angelini F, Gigliotti D, Livadiotti S, Bertini E, Rossi P, Racioppi L. Restriction in T-cell receptor repertoire in a patient affected by trichothiodystrophy and CD4+ lymphopenia. Scand J Immunol 2002; 56:212-6. [PMID: 12121441 DOI: 10.1046/j.1365-3083.2002.01122.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Molecular analysis of T-cell receptor (TCR) repertoire, by measuring the CDR3 heterogeneity length of beta-variable regions (spectratyping), is useful for acquiring novel information on the status of immune system in primary immunodeficiency. Here, we evaluate TCR repertoire in a child with trichothiodystrophy (TTD) and combined immunodeficiency (CID). Spectratyping revealed marked alterations of TCR repertoire distribution: 21 and 10 out of 27 TCR Vbeta (TCRBV) families and subfamilies were skewed in CD8+ and CD4+ subsets, respectively. These findings revealed, for the first time in a TTD patient with CID, a marked reduction in the TCR repertoire complexity, which may reflect alterations in the mechanisms regulating the generation and homeostasis of T cells.
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Affiliation(s)
- C Cancrini
- Division of Immunology and Infectius Deseases, Children's Hospital Bambino Gensù, University of Rome Tor bbergata, Rome, Italy.
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114
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Affiliation(s)
- Paul Hasty
- Department of Molecular Medicine, University of Texas Health Science Center, San Antonio, TX 78245, USA.
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115
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de Boer J, Andressoo JO, de Wit J, Huijmans J, Beems RB, van Steeg H, Weeda G, van der Horst GTJ, van Leeuwen W, Themmen APN, Meradji M, Hoeijmakers JHJ. Premature aging in mice deficient in DNA repair and transcription. Science 2002; 296:1276-9. [PMID: 11950998 DOI: 10.1126/science.1070174] [Citation(s) in RCA: 383] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
One of the factors postulated to drive the aging process is the accumulation of DNA damage. Here, we provide strong support for this hypothesis by describing studies of mice with a mutation in XPD, a gene encoding a DNA helicase that functions in both repair and transcription and that is mutated in the human disorder trichothiodystrophy (TTD). TTD mice were found to exhibit many symptoms of premature aging, including osteoporosis and kyphosis, osteosclerosis, early greying, cachexia, infertility, and reduced life-span. TTD mice carrying an additional mutation in XPA, which enhances the DNA repair defect, showed a greatly accelerated aging phenotype, which correlated with an increased cellular sensitivity to oxidative DNA damage. We hypothesize that aging in TTD mice is caused by unrepaired DNA damage that compromises transcription, leading to functional inactivation of critical genes and enhanced apoptosis.
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Affiliation(s)
- Jan de Boer
- Medical Genetics Center, Department of Cell Biology and Genetics, Center for Biomedical Genetics, Erasmus University, 3000 DR Rotterdam, Netherlands
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116
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van Brabant AJ, Stan R, Ellis NA. DNA helicases, genomic instability, and human genetic disease. Annu Rev Genomics Hum Genet 2002; 1:409-59. [PMID: 11701636 DOI: 10.1146/annurev.genom.1.1.409] [Citation(s) in RCA: 203] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
DNA helicases are a highly conserved group of enzymes that unwind DNA. They function in all processes in which access to single-stranded DNA is required, including DNA replication, DNA repair and recombination, and transcription of RNA. Defects in helicases functioning in one or more of these processes can result in characteristic human genetic disorders in which genomic instability and predisposition to cancer are common features. So far, different helicase genes have been found mutated in six such disorders. Mutations in XPB and XPD can result in xeroderma pigmentosum, Cockayne syndrome, or trichothiodystrophy. Mutations in the RecQ-like genes BLM, WRN, and RECQL4 can result in Bloom syndrome, Werner syndrome, and Rothmund-Thomson syndrome, respectively. Because XPB and XPD function in both nucleotide excision repair and transcription initiation, the cellular phenotypes associated with a deficiency of each one of them include failure to repair mutagenic DNA lesions and defects in the recovery of RNA transcription after UV irradiation. The functions of the RecQ-like genes are unknown; however, a growing body of evidence points to a function in restarting DNA replication after the replication fork has become stalled. The genomic instability associated with mutations in the RecQ-like genes includes spontaneous chromosome instability and elevated mutation rates. Mouse models for nearly all of these entities have been developed, and these should help explain the widely different clinical features that are associated with helicase mutations.
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Affiliation(s)
- A J van Brabant
- Department of Human Genetics, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA
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117
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Termorshuizen F, Garssen J, Norval M, Koulu L, Laihia J, Leino L, Jansen CT, De Gruijl F, Gibbs NK, De Simone C, Van Loveren H. A review of studies on the effects of ultraviolet irradiation on the resistance to infections: evidence from rodent infection models and verification by experimental and observational human studies. Int Immunopharmacol 2002; 2:263-75. [PMID: 11811930 DOI: 10.1016/s1567-5769(01)00178-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Recent studies on the immunosuppressive effects of ultraviolet radiation (UVR) and the related resistance to infections in rodents and humans are presented. The waveband dependency of trans-to-cis isomerisation of urocanic acid in the stratum corneum and the role of DNA damage in UVR-induced erythema and immunosuppression were investigated to further elucidate the underlying mechanisms. Furthermore, human experimental studies on UVR-induced immunomodulation were performed. It appeared that the doses needed to suppress various immune parameters in humans (e.g. NK activity, contact hypersensitivity) were higher than those needed in experiments in rodents. Still, extrapolation of experimental animal data to the human situation showed that UVR may impair the resistance to different systemic infections at relevant outdoor doses. In observational human studies we aimed to substantiate the relevance of UVR for infections in humans. It was shown that sunny season was associated with a slightly retarded but clinically non-relevant antibody response to hepatitis B vaccination. Furthermore, sunny season appeared to be associated with a small decline in the number of CD4+ T-helper cells in a cohort of HIV-infected persons and a higher recurrence of herpes simplex and herpes zoster in a cohort of renal transplant recipients. However, in a study among young children a higher exposure to solar UVR was associated with a lower occurrence of upper respiratory tract symptoms. As disentangling the effects of UVR from other relevant factors is often impossible in observational studies, concise quantitative risk estimations for the human situation cannot be given at present.
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Affiliation(s)
- F Termorshuizen
- Laboratory for Pathology and Immunobiology, National Institute of Public Health and the Environment, Bilthoven, The Netherlands
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118
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Abstract
Inherited defects in DNA repair or the processing of DNA damage can lead to disease. Both autosomal recessive and autosomal dominant modes of inheritance are represented. The diseases as a group are characterized by genomic instability, with eventual appearance of cancer. The inherited defects frequently have a specific DNA damage sensitivity, with cells from affected individuals showing normal resistance to other genotoxic agents. The known defects are subtle alterations in transcription, replication, or recombination, with alternate pathways of processing permitting cellular viability. Distinct diseases may arise from different mutations in one gene; thus, clinical phenotypes may reflect the loss of different partial functions of a gene. The findings indicate that partial defects in transcription or recombination lead to genomic instability, cancer, and characteristic disease phenotypes.
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Affiliation(s)
- R E Moses
- Department of Molecular and Medical Genetics, Oregon Health Sciences University, Portland, Oregon 97201, USA.
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119
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Abstract
All living organisms are constantly exposed to endogenous or exogenous agents that can cause damage to the genomic DNA, leading to the loss of stable genetic information. Fortunately, all cells are equipped with numerous classes of DNA repair pathways which are able to correct many kinds of DNA damage such as bulky adducts, oxidative lesions, single- and double-strand breaks and mismah. The importance of these DNA repair processes is attested by the existence of several rare but dramatic hereditary diseases caused by defects in one of their repair pathways. These diseases are usually associated with early onset of malignancies confirming the direct relationship between unrepaired DNA lesions, mutations or chromosomal modifications and cancer incidence. Among these hereditary diseases the UV-hypersensitive ones have been particularly well studied and the xeroderma pigmentosum (XP) is probably the best known syndrome up to now in terms of genetics and biochemistry.
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Affiliation(s)
- Anne Stary
- Laboratory Genetic Instability UPR2169 CNRS, 7, rue Guy Moquet, 94800 Villejuif, France.
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120
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Nakamura M, Sundberg JP, Paus R. Mutant laboratory mice with abnormalities in hair follicle morphogenesis, cycling, and/or structure: annotated tables. Exp Dermatol 2001; 10:369-90. [PMID: 11737257 DOI: 10.1034/j.1600-0625.2001.100601.x] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Numerous transgenic, targeted mutagenesis (so-called knockouts), conditional (so-called "gene switch") and spontaneous mutant mice develop abnormal hair phenotypes. The number of mice that exhibit such abnormalities is increasing exponentially as genetic engineering methods become routine. Since defined abnormalities in hair follicle morphogenesis, cycling and/or structure in such mutant mice provide important clues to the as yet poorly understood functional roles of many gene products, it is useful to summarize and classify these mutant mice according to their hair phenotype. This review provides a corresponding, annotated table of mutant mice with hair abnormalities, classifying the latter into 6 categories, 1) abnormally low number of hair follicles, 2) disorders of hair morphogenesis, 3) of hair follicle cycling, 4) of hair follicle structure 5) of sebaceous gland structure, and 6) hair growth disorders as a consequence of immunological abnormalities. This annotated table should serve as a useful source of reference for anyone who is interested in the molecular controls of hair growth, for investigators who are looking for mouse models to explore or compare the functional activities of their gene of interest, and for comparing the hair phenotype of newly generated mouse mutants with existing ones.
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Affiliation(s)
- M Nakamura
- Department of Dermatology, University Hospital Eppendorf, University of Hamburg, Martinistrasse 52, D-20246, Hamburg, Germany
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121
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Racioppi L, Cancrini C, Romiti ML, Angelini F, Di Cesare S, Bertini E, Livadiotti S, Gambarara MG, Matarese G, Lago Paz F, Stefanini M, Rossi P. Defective dendritic cell maturation in a child with nucleotide excision repair deficiency and CD4 lymphopenia. Clin Exp Immunol 2001; 126:511-8. [PMID: 11737070 PMCID: PMC1906228 DOI: 10.1046/j.1365-2249.2001.01625.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report a case of a combined immunodeficiency (CID) in a child affected by trichothiodystrophy (TTD) characterized by an altered response to ultraviolet (UV) light due to a defect in the XPD gene. The XPD gene encodes a subunit of the transcription factor II H (TFIIH), a complex involved in nucleotide-excision repair (NER) and basal transcription. Our patient showed neurological and immune system abnormalities, including CD4 + lymphopenia never previously reported in TTD patients. In vitro immunological studies revealed a marked reduction in T-cell proliferation in response to mitogens and CD3 cross-linking which was partially recovered by the addition of anti-CD28 antibody or exogenous interleukin-2. The patient's T cells displayed alterations in T-cell receptor (TCR/CD3) proximal signalling characterized by marked reduction in Lck kinase activity coupled with a constitutive hyperactivation of Fyn kinase. Despite these alterations, normal levels of Lck and Fyn proteins were detected. The role of antigen-presenting cells (APCs) in the pathogenesis of the T-cell defect was investigated by analysing dendritic cells (DCs) generated from the patient's blood monocytes. In these cells, flow cytometry revealed significantly reduced expression of the CD86 co-stimulatory molecules and HLA glycoproteins. In addition, the patient's DCs showed a decreased ability to stimulate naive T lymphocytes. Overall, the results of our study suggest that a defective TFIIH complex might result in alterations in T cells and DC functions leading to a severe immunodeficiency.
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Affiliation(s)
- L Racioppi
- Dipartimento di Biologia e Patologia Cellulare e Molecolare, Università di Napoli Federico II, Italy
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122
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Murai M, Enokido Y, Inamura N, Yoshino M, Nakatsu Y, van der Horst GT, Hoeijmakers JH, Tanaka K, Hatanaka H. Early postnatal ataxia and abnormal cerebellar development in mice lacking Xeroderma pigmentosum Group A and Cockayne syndrome Group B DNA repair genes. Proc Natl Acad Sci U S A 2001; 98:13379-84. [PMID: 11687625 PMCID: PMC60879 DOI: 10.1073/pnas.231329598] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Xeroderma pigmentosum (XP) and Cockayne syndrome (CS) are rare autosomal recessive disorders associated with a defect in the nucleotide excision repair (NER) pathway required for the removal of DNA damage induced by UV light and distorting chemical adducts. Although progressive neurological dysfunction is one of the hallmarks of CS and of some groups of XP patients, the causative mechanisms are largely unknown. Here we show that mice lacking both the XPA (XP-group A) and CSB (CS-group B) genes in contrast to the single mutants display severe growth retardation, ataxia, and motor dysfunction during early postnatal development. Their cerebella are hypoplastic and showed impaired foliation and stunted Purkinje cell dendrites. Reduced neurogenesis and increased apoptotic cell death occur in the cerebellar external granular layer. These findings suggest that XPA and CSB have additive roles in the mouse nervous system and support a crucial role for these genes in normal brain development.
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Affiliation(s)
- M Murai
- Division of Protein Biosynthesis, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
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123
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Abstract
Eukaryotic cells can repair many types of DNA damage. Among the known DNA repair processes in humans, one type--nucleotide excision repair (NER)--specifically protects against mutations caused indirectly by environmental carcinogens. Humans with a hereditary defect in NER suffer from xeroderma pigmentosum and have a marked predisposition to skin cancer caused by sunlight exposure. How does NER protect against skin cancer and possibly other types of environmentally induced cancer in humans?
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Affiliation(s)
- E C Friedberg
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas 75390-9072, USA.
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124
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Tanaka K, Kamiuchi S, Ren Y, Yonemasu R, Ichikawa M, Murai H, Yoshino M, Takeuchi S, Saijo M, Nakatsu Y, Miyauchi-Hashimoto H, Horio T. UV-induced skin carcinogenesis in xeroderma pigmentosum group A (XPA) gene-knockout mice with nucleotide excision repair-deficiency. Mutat Res 2001; 477:31-40. [PMID: 11376684 DOI: 10.1016/s0027-5107(01)00093-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nucleotide excision repair (NER) removes a wide variety of lesions from the genome and is deficient in the genetic disorder, xeroderma pigmentosum (XP). In this paper, an in vitro analysis of the XP group A gene product (XPA protein) is reported. Results of an analysis on the pathogenesis of ultraviolet (UV)-B-induced skin cancer in the XPA gene-knockout mouse are also described: (1) contrary to wild type mice, significant bias of p53 mutations to the transcribed strand and no evident p53 mutational hot spots were detected in the skin tumors of XPA-knockout mice. (2) Skin cancer cell lines from UVB-irradiated XPA-knockout mice had a decreased mismatch repair activity and an abnormal cell cycle checkpoint, suggesting that the downregulation of mismatch repair helps cells escape killing by UVB and that mismatch repair-deficient clones are selected for during the tumorigenic transformation of XPA (-/-) cells. (3) The XPA-knockout mice showed a higher frequency of UVB-induced mutation in the rpsL transgene at a low dose of UVB-irradiation than the wild type mice. CC-->TT tandem transition, a hallmark of UV-induced mutation, was detected at higher frequency in the rpsL transgene in the XPA-knockout mice than the wild type mice. This rpsL/XPA mouse system will be useful for further analysing the role of NER in the mutagenesis induced by various carcinogens. (4) The UVB-induced immunosuppression was greatly enhanced in the XPA-knockout mice. It is possible that an enhanced impairment of the immune system by UVB irradiation is involved in the high incidence of skin cancer in XP.
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Affiliation(s)
- K Tanaka
- Institute for Molecular and Cellular Biology, Osaka University, 1-3 Yamadaoka, Suita, 565-0871, Osaka, Japan.
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125
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de Crom R, Wulf P, van Nimwegen H, Kutryk MJ, Visser P, van der Kamp A, Hamming J. Irradiated versus nonirradiated endothelial cells: effect on proliferation of vascular smooth muscle cells. J Vasc Interv Radiol 2001; 12:855-61. [PMID: 11435542 DOI: 10.1016/s1051-0443(07)61511-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
PURPOSE Endovascular radiation therapy is a promising strategy for the prevention of restenosis. Radiation prevents proliferation of vascular smooth muscle cells, thereby reducing the incidence of restenosis, but may also affect the remaining endothelial cells. For this reason, a comparison was made between irradiated and nonirradiated endothelial cells and their effects on the proliferation of vascular smooth muscle cells in a coculture system was evaluated. MATERIALS AND METHODS A coculture system was used, in which both endothelial cells and vascular smooth muscle cells were grown on opposite sides of a semipermeable membrane. After a period of growth arrest, the proliferation of vascular smooth muscle cells was measured during four subsequent days. RESULTS The presence of endothelial cells stimulated the proliferation of vascular smooth muscle cells during the first days of analysis but had an inhibitory effect during the subsequent days (P <.5). gamma-irradiation of endothelial cells resulted in a complete blockage of the proliferation of these cells. However, irradiated endothelial cells affected the proliferation of vascular smooth muscle cells in coculture in a fashion comparable to nonirradiated endothelial cells (P >.5). CONCLUSION The results suggest that, in endovascular radiation therapy, irradiation of endothelial cells does not change their effects on the proliferative behavior of vascular smooth muscle cells.
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Affiliation(s)
- R de Crom
- Medical Genetics Centre, Department of Cell Biology and Genetics, Erasmus University, Rotterdam, The Netherlands.
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126
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Itin PH, Sarasin A, Pittelkow MR. Trichothiodystrophy: update on the sulfur-deficient brittle hair syndromes. J Am Acad Dermatol 2001; 44:891-920; quiz 921-4. [PMID: 11369901 DOI: 10.1067/mjd.2001.114294] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Trichothiodystrophy (TTD) refers to a heterogeneous group of autosomal recessive disorders that share the distinctive features of short, brittle hair and an abnormally low sulfur content. Within the spectrum of the TTD syndromes are numerous interrelated neuroectodermal disorders. The TTD syndromes show defective synthesis of high-sulfur matrix proteins. Abnormalities in excision repair of ultraviolet (UV)-damaged DNA are recognized in about half of the patients. Three distinct autosomal recessive syndromes are associated with nucleotide excision repair (NER) defects: the photosensitive form of TTD, xeroderma pigmentosum, and Cockayne syndrome. The unifying feature of these conditions is exaggerated sensitivity to sunlight and UV radiation. In contrast to patients with xeroderma pigmentosum, no increase of skin cancers in patients with TTD has been observed. Genetically, 3 complementation groups have been characterized among photosensitive patients with TTD. Most patients exhibit mutations on the two alleles of the XPD gene. Rarely, mutated XPB gene or an unidentified TTD-A gene may result in TTD. In UV-sensitive TTD, the TFIIH transcription factor containing XPB and XPD helicase activities necessary for both transcription initiation and DNA repair is damaged. Beyond deficiency in the NER pathway, it is hypothesized that basal transcription may be altered leading to decreased transcription of specific genes. Depressed RNA synthesis may account for some clinical features, such as growth retardation, neurologic abnormalities, and brittle hair and nails. Therefore the attenuated expression of some proteins in differentiated cells is most likely explained by a mechanism distinct from DNA repair deficiency. The first transgenic mouse models for NER deficiencies have been generated. The TTD mouse as well as related cell models will provide important tools to understand the complex relationships between defects in DNA repair, low-sulfur hair shaft disorders, and the genotype-phenotype correlates for this constellation of inherited disorders, including the lack of predisposition to cancer in patients with TTD.
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Affiliation(s)
- P H Itin
- Department of Dermatology, University of Basel and Kantonsspital Aarau, Switzerland
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127
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Abstract
Trichothiodystrophy (TTD) is a rare genetic disorder characterized by a hair dysplasia and associated with numerous symptoms affecting mainly organs derived from the neuroectoderm. About half of TTD patients exhibit photosensitivity because their nucleotide-excision repair pathway (NER) does not remove UV-induced DNA lesions efficiently. However, they do not present the skin cancer susceptibility expected from such an NER disorder. Their deficiencies result from phenotype-specific mutations in either XPB or XPD. These genes encode the helicase subunits of TFIIH, a DNA repair factor that is also required for transcription of class II genes. Thus, time- and tissue-specific impairments of transcription might explain the developmental and neurological symptoms of TTD. In a third group of photosensitive patients, TTD-A, no mutation has been identified, although TFIIH amount is reduced.
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Affiliation(s)
- E Bergmann
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, BP 163, 67404 Illkirch Cedex, C.U. de Strasbourg, France
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128
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Kadkhodayan S, Coin F, Salazar EP, George JW, Egly JM, Thompson LH. Codominance associated with overexpression of certain XPD mutations. Mutat Res 2001; 485:153-68. [PMID: 11182546 DOI: 10.1016/s0921-8777(00)00077-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mutations in the XPD gene are associated with three complex clinical phenotypes, namely xeroderma pigmentosum (XP), XP in combination with Cockayne syndrome (XP-CS), and trichothiodystrophy (TTD). XP is caused by a deficiency in nucleotide excision repair (NER) that results in a high risk of skin cancer. TTD is characterized by severe developmental and neurological defects, with hallmark features of brittle hair and scaly skin, and sometimes has defective NER. We used CHO cells as a system to study how specific mutations alter the dominant/recessive behavior of XPD protein. Previously we identified the T46I and R75W mutations in two highly UV-sensitive hamster cell lines that were reported to have paradoxically high levels of unscheduled DNA synthesis. Here we report that these mutants have greatly reduced XPD helicase activity and fully defective NER in a cell-extract excision assay. We conclude that the unscheduled DNA synthesis seen in these mutants is caused by abortive "repair" that does not contribute to cell survival. These mutations, as well as the K48R canonical helicase-domain mutation, each produced codominant negative phenotypes when overexpressed in wild-type CHO cells. The common XP-specific R683W mutation also behaved in a codominant manner when overexpressed, which is consistent with the idea that this mutation may affect primarily the enzymatic activity of the protein rather than impairing protein interactions, which may underlie TTD. A C-terminal mutation uniquely found in TTD (R722W) was overexpressed but not to levels sufficiently high to rigorously test for a codominant phenotype. Overexpression of mutant XPD alleles may provide a simple means of producing NER deficiency in other cell lines.
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Affiliation(s)
- S Kadkhodayan
- Biology and Biotechnology Research Program, L441, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551-0808, USA
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129
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Berneburg M, Lehmann AR. Xeroderma pigmentosum and related disorders: defects in DNA repair and transcription. ADVANCES IN GENETICS 2001; 43:71-102. [PMID: 11037299 DOI: 10.1016/s0065-2660(01)43004-5] [Citation(s) in RCA: 155] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The genetic disorders xeroderma pigmentosum (XP), Cockayne syndrome (CS), and trichothiodystrophy (TTD) are all associated with defects in nucleotide excision repair (NER) of DNA damage. Their clinical features are very different, however, XP being a highly cancer-prone skin disorder, whereas CS and TTD are cancer-free multisystem disorders. All three are genetically complex, with at least eight complementation groups for XP (XP-A to -G and variant), five for CS (CS-A, CS-B, XP-B, XP-D, and XP-G), and three for TTD (XP-B, XP-D, and TTD-A). With the exception of the variant, the products of the XP genes are proteins involved in the different steps of NER, and comprise three damage-recognition proteins, two helicases, and two nucleases. The two helicases, XPB and XPD, are components of the basal transcription factor TFIIH, which has a dual role in NER and initiation of transcription. Different mutations in these genes can affect NER and transcription differentially, and this accounts for the different clinical phenotypes. Mutations resulting in defective repair without affecting transcription result in XP, whereas if transcription is also affected, TTD is the outcome. CS proteins are only involved in transcription-coupled repair, a subpathway of NER in which damage in the transcribed strands of active genes is rapidly and preferentially repaired. Current evidence suggests that they also have an important but not essential role in transcription. The variant form of XP is defective in a novel DNA polymerase, which is able to synthesise DNA past UV-damaged sites.
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Affiliation(s)
- M Berneburg
- MRC Cell Mutation Unit, University of Sussex, Falmer, Brighton, United Kingdom
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130
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Vermeulen W, Rademakers S, Jaspers NG, Appeldoorn E, Raams A, Klein B, Kleijer WJ, Hansen LK, Hoeijmakers JH. A temperature-sensitive disorder in basal transcription and DNA repair in humans. Nat Genet 2001; 27:299-303. [PMID: 11242112 DOI: 10.1038/85864] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The xeroderma pigmentosum group D (XPD) helicase subunit of TFIIH functions in DNA repair and transcription initiation. Different mutations in XPD give rise to three ultraviolet-sensitive syndromes: the skin cancer-prone disorder xeroderma pigmentosum (XP), in which repair of ultraviolet damage is affected; and the severe neurodevelopmental conditions Cockayne syndrome (CS) and trichothiodystrophy (TTD). In the latter two, the basal transcription function of TFIIH is also presumed to be affected. Here we report four unusual TTD patients with fever-dependent reversible deterioration of TTD features such as brittle hair. Cells from these patients show an in vivo temperature-sensitive defect of transcription and DNA repair due to thermo-instability of TFIIH. Our findings reveal the clinical consequences of impaired basal transcription and mutations in very fundamental processes in humans, which previously were only known in lower organisms.
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Affiliation(s)
- W Vermeulen
- MGC, Department of Cell Biology and Genetics, Center for Biomedical Genetics, Erasmus University, P.O. Box 1738, Rotterdam, The Netherlands
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131
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Hoeijmakers JH. From xeroderma pigmentosum to the biological clock contributions of Dirk Bootsma to human genetics. Mutat Res 2001; 485:43-59. [PMID: 11341993 DOI: 10.1016/s0921-8777(00)00079-3] [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: 11/22/2022]
Abstract
This paper commemorates the multiple contributions of Dirk Bootsma to human genetics. During a scientific 'Bootsma' cruise on his sailing-boat 'de Losbol', we visit a variety of scenery locations along the lakes and canals in Friesland, passing the highlights of Dirk Bootsma's scientific oeuvre. Departing from 'de Fluessen', his homeport, with his PhD work on the effect of X-rays and UV on cell cycle progression, we head for the pioneering endeavours of his team on mapping genes on human chromosomes by cell hybridization. Next we explore the use of cell hybrids by the Bootsma team culminating in the molecular cloning of one of the first chromosomal breakpoints involved in oncogenesis: the bcr-abl fusion gene responsible for chronic myelocytic leukemia. This seminal achievement enabled later development of new methods for early detection and very promising therapeutic intervention. A series of highlights at the horizon constitute the contributions of his team to the field of DNA repair, beginning with the discovery of genetic heterogeneity in the repair syndrome xeroderma pigmentosum (XP) followed later by the cloning of a large number of human repair genes. This led to the discovery that DNA repair is strongly conserved in evolution rendering knowledge from yeast relevant for mammals and vice versa. In addition, it resolved the molecular basis of several repair syndromes and permitted functional analysis of the encoded proteins. Another milestone is the discovery of the surprising connection between DNA repair and transcription initiation via the dual functional TFIIH complex in collaboration with Jean-Marc Egly et al. in Strasbourg. This provided an explanation for many puzzling clinical features and triggered a novel concept in human genetics: the existence of repair/transcription syndromes. The generation of many mouse mutants carrying defects in repair pathways yielded valuable models for assessing the clinical relevance of DNA repair including carcinogenesis and the identification of a link between DNA damage and premature aging. His team also opened a fascinating area of cell biology with the analysis of repair and transcription in living cells. A final surprising evolutionary twist was the discovery that photolyases designed for the light-dependent repair of UV-induced DNA lesions appeared to be adopted for driving the mammalian biological clock. The latter indicates that it is time to return to 'de Fluessen', where we will consider briefly the merits of Dirk Bootsma for Dutch science in general.
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Affiliation(s)
- J H Hoeijmakers
- MGC, Cell Biology and Genetics, Center for Biomedical Genetics, Erasmus University, P.O. Box 1738, 3000 DR Rotterdam, The Netherlands.
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132
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Lehmann AR. The xeroderma pigmentosum group D (XPD) gene: one gene, two functions, three diseases. Genes Dev 2001; 15:15-23. [PMID: 11156600 DOI: 10.1101/gad.859501] [Citation(s) in RCA: 272] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- A R Lehmann
- MRC Cell Mutation Unit, University of Sussex, Falmer, Brighton BN1 9RR, UK.
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133
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Cleaver JE, Thompson LH, Richardson AS, States JC. A summary of mutations in the UV-sensitive disorders: xeroderma pigmentosum, Cockayne syndrome, and trichothiodystrophy. Hum Mutat 2000; 14:9-22. [PMID: 10447254 DOI: 10.1002/(sici)1098-1004(1999)14:1<9::aid-humu2>3.0.co;2-6] [Citation(s) in RCA: 177] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The human diseases xeroderma pigmentosum, Cockayne syndrome, and trichothiodystrophy are caused by mutations in a set of interacting gene products, which carry out the process of nucleotide excision repair. The majority of the genes have now been cloned and many mutations in the genes identified. The relationships between the distribution of mutations in the genes and the clinical presentations can be used for diagnosis and for understanding the functions and the modes of interaction among the gene products. The summary presented here represents currently known mutations that can be used as the basis for future studies of the structure, function, and biochemical properties of the proteins involved in this set of complex disorders, and may allow determination of the critical sites for mutations leading to different clinical manifestations. The summary indicates where more data are needed for some complementation groups that have few reported mutations, and for the groups for which the gene(s) are not yet cloned. These include the Xeroderma pigmentosum (XP) variant, the trichothiodystrophy group A (TTDA), and ultraviolet sensitive syndrome (UVs) groups. We also recommend that the XP-group E should be defined explicitly through molecular terms, because assignment by complementation in culture has been difficult. XP-E by this definition contains only those cell lines and patients that have mutations in the small subunit, DDB2, of a damage-specific DNA binding protein.
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Affiliation(s)
- J E Cleaver
- UCSF Cancer Center and Department of Dermatology, University of California, San Francisco 94143-0808, USA.
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134
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Garssen J, van Steeg H, de Gruijl F, de Boer J, van der Horst GT, van Kranen H, van Loveren H, van Dijk M, Fluitman A, Weeda G, Hoeijmakers JH. Transcription-coupled and global genome repair differentially influence UV-B-induced acute skin effects and systemic immunosuppression. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 164:6199-205. [PMID: 10843671 DOI: 10.4049/jimmunol.164.12.6199] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Exposure to UV-B radiation impairs immune responses in mammals by inhibiting especially Th1-mediated contact hypersensitivity and delayed-type hypersensitivity. Immunomodulation is not restricted to the exposed skin, but is also observed at distant sites, indicating the existence of mediating factors such as products from exposed skin cells or photoactivated factors present in the superficial layers. DNA damage appears to play a key role, because enhanced nucleotide excision repair (NER) strongly counteracts immunosuppression. To determine the effects of the type and genomic location of UV-induced DNA damage on immunosuppression and acute skin reactions (edema and erythema) four congenic mouse strains carrying different defects in NER were compared: CSB and XPC mice lacking transcription-coupled or global genome NER, respectively, as well as XPA and TTD/XPD mice carrying complete or partial defects in both NER subpathways, respectively. The major conclusions are that 1) transcription-coupled DNA repair is the dominant determinant in protection against acute skin effects; 2) systemic immunomodulation is only affected when both NER subpathways are compromised; and 3) sunburn is not related to UV-B-induced immunosuppression.
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MESH Headings
- Animals
- Cockayne Syndrome/genetics
- Cockayne Syndrome/immunology
- DNA Repair/immunology
- DNA Repair/radiation effects
- Dermatitis, Contact/genetics
- Dermatitis, Contact/immunology
- Dose-Response Relationship, Immunologic
- Dose-Response Relationship, Radiation
- Edema/genetics
- Edema/immunology
- Erythema/genetics
- Erythema/immunology
- Genome
- Hair Diseases/genetics
- Hair Diseases/immunology
- Hypersensitivity, Delayed/genetics
- Hypersensitivity, Delayed/immunology
- Hypersensitivity, Delayed/microbiology
- Immunosuppression Therapy
- Listeria monocytogenes/immunology
- Listeria monocytogenes/radiation effects
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Picryl Chloride/immunology
- Skin/immunology
- Skin/metabolism
- Skin/radiation effects
- Transcription, Genetic/immunology
- Transcription, Genetic/radiation effects
- Ultraviolet Rays
- Xeroderma Pigmentosum/genetics
- Xeroderma Pigmentosum/immunology
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Affiliation(s)
- J Garssen
- Laboratory for Pathology and Immunobiology and Laboratory of Health Effects Research, National Institute of Public Health and the Environment, Bilthoven, The Netherlands.
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135
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Friedberg EC, Meira LB. Database of mouse strains carrying targeted mutations in genes affecting cellular responses to DNA damage. Version 4. Mutat Res 2000; 459:243-74. [PMID: 10844240 DOI: 10.1016/s0921-8777(00)00006-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- E C Friedberg
- Department of Pathology, University of Texas Southwestern Medical Center Dallas, TX 75235-9072, USA.
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136
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Murai H, Takeuchi S, Nakatsu Y, Ichikawa M, Yoshino M, Gondo Y, Katsuki M, Tanaka K. Studies of in vivo mutations in rpsL transgene in UVB-irradiated epidermis of XPA-deficient mice. Mutat Res 2000; 450:181-92. [PMID: 10838142 DOI: 10.1016/s0027-5107(00)00024-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
We have established xeroderma pigmentosum group A (XPA) gene-knockout mice with nucleotide excision repair (NER) deficiency, which rapidly developed skin tumors when exposed to a low dose of chronic UV like XP-A patients, confirming that the NER process plays an important role in preventing UVB-induced skin cancer. To examine the in vivo mutation in the UVB-irradiated epidermis, we established XPA (-/-), (+/-) and (+/+) mice carrying the Escherichia coli rpsL transgene with which the mutation frequencies and spectra in the UVB-irradiated epidermal tissue can be examined conveniently. The XPA (-/-) mice showed a higher frequency of UVB-induced mutation in the rpsL transgene with a low dose (150 J/m(2)) of UVB-irradiation than the XPA (+/-) and (+/+) mice, while, at a high dose (900 J/m(2)) they showed almost the same frequency of mutation as the XPA (+/-) and (+/+) mice, probably because of cell death in the epidermis of the XPA (-/-) mice. However, CC-->TT tandem transition, a hallmark of UV-induced mutation, was detected at higher frequency in the XPA (-/-) mice than the XPA (+/-) and (+/+) mice at both doses of UVB. This rpsL/XPA mouse system will be useful for further analyzing the role of NER in the mutagenesis and carcinogenesis induced by various carcinogens.
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Affiliation(s)
- H Murai
- Division of Cellular Genetics, Institute for Molecular and Cellular Biology, Osaka University, 1-3 Yamadaoka, Osaka 565-0871, Suita, Japan
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137
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Abstract
DNA damage is implicated in cancer and aging, and several DNA repair mechanisms exist that safeguard the genome from these deleterious consequences. Nucleotide excision repair (NER) removes a wide diversity of lesions, the main of which include UV-induced lesions, bulky chemical adducts and some forms of oxidative damage. The NER process involves the action of at least 30 proteins in a 'cut-and-paste'-like mechanism. The consequences of a defect in one of the NER proteins are apparent from three rare recessive syndromes: xeroderma pigmentosum (XP), Cockayne syndrome (CS) and the photosensitive form of the brittle hair disorder trichothiodystrophy (TTD). Sun-sensitive skin is associated with skin cancer predisposition in the case of XP, but remarkably not in CS and TTD. Moreover, the spectrum of clinical symptoms differs considerably between the three syndromes. CS and TTD patients exhibit a spectrum of neurodevelopmental abnormalities and, in addition, TTD is associated with ichthyosis and brittle hair. These typical CS and TTD abnormalities are difficult to comprehend as a consequence of defective NER. This review briefly describes the biochemistry of the NER process, summarizes the clinical features of the NER disorders and speculates on the molecular basis underlying these pleitropic syndromes.
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Affiliation(s)
- J de Boer
- Medical Genetics Centre, Department of Cell Biology and Genetics, Centre for Biomedical Genetics, Erasmus University, PO Box 1738, 3000DR Rotterdam, The Netherlands
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138
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Winkler GS, Araújo SJ, Fiedler U, Vermeulen W, Coin F, Egly JM, Hoeijmakers JH, Wood RD, Timmers HT, Weeda G. TFIIH with inactive XPD helicase functions in transcription initiation but is defective in DNA repair. J Biol Chem 2000; 275:4258-66. [PMID: 10660593 DOI: 10.1074/jbc.275.6.4258] [Citation(s) in RCA: 131] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
TFIIH is a multisubunit protein complex involved in RNA polymerase II transcription and nucleotide excision repair, which removes a wide variety of DNA lesions including UV-induced photoproducts. Mutations in the DNA-dependent ATPase/helicase subunits of TFIIH, XPB and XPD, are associated with three inherited syndromes as follows: xeroderma pigmentosum with or without Cockayne syndrome and trichothiodystrophy. By using epitope-tagged XPD we purified mammalian TFIIH carrying a wild type or an active-site mutant XPD subunit. Contrary to XPB, XPD helicase activity was dispensable for in vitro transcription, catalytic formation of trinucleotide transcripts, and promoter opening. Moreover, in contrast to XPB, microinjection of mutant XPD cDNA did not interfere with in vivo transcription. These data show directly that XPD activity is not required for transcription. However, during DNA repair, neither 5' nor 3' incisions in defined positions around a DNA adduct were detected in the presence of TFIIH containing inactive XPD, although substantial damage-dependent DNA synthesis was induced by the presence of mutant XPD both in cells and cell extracts. The aberrant damage-dependent DNA synthesis caused by the mutant XPD does not lead to effective repair, consistent with the discrepancy between repair synthesis and survival in cells from a number of XP-D patients.
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Affiliation(s)
- G S Winkler
- Department of Cell Biology and Genetics, Medical Genetics Center, Erasmus University Rotterdam, P. O. Box 1738, 3000 DR Rotterdam, The Netherlands
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139
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Liu J, He L, Collins I, Ge H, Libutti D, Li J, Egly JM, Levens D. The FBP interacting repressor targets TFIIH to inhibit activated transcription. Mol Cell 2000; 5:331-41. [PMID: 10882074 DOI: 10.1016/s1097-2765(00)80428-1] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
FUSE-binding protein (FBP) binds the single-stranded far upstream element of active c-myc genes, possesses potent transcription activation and repression domains, and is necessary for c-myc expression. A novel 60 kDa protein, the FBP interacting repressor (FIR), blocked activator-dependent, but not basal, transcription through TFIIH. Recruited through FBP's nucleic acid-binding domain, FIR formed a ternary complex with FBP and FUSE. FIR repressed a c-myc reporter via the FUSE. The amino terminus of FIR contained an activator-selective repression domain capable of acting in cis or even in trans in vivo and in vitro. The repression domain of FIR targeted only TFIIH's p89/XPB helicase, required at several stages in transcription, but not factors required for promoter selection. Thus, FIR locks TFIIH in an activation-resistant configuration that still supports basal transcription.
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Affiliation(s)
- J Liu
- Gene Regulation Section, Laboratory of Pathology, National Cancer Institute, Bethesda, Maryland 20892, USA
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140
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Abstract
Faithful maintenance of the genome is crucial to the individual and to species. DNA damage arises from both endogenous sources such as water and oxygen and exogenous sources such as sunlight and tobacco smoke. In human cells, base alterations are generally removed by excision repair pathways that counteract the mutagenic effects of DNA lesions. This serves to maintain the integrity of the genetic information, although not all of the pathways are absolutely error-free. In some cases, DNA damage is not repaired but is instead bypassed by specialized DNA polymerases.
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Affiliation(s)
- T Lindahl
- Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms, Herts, EN6 3LD, UK
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141
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Robles AI, Wang XW, Harris CC. Drug-induced apoptosis is delayed and reduced in XPD lymphoblastoid cell lines: possible role of TFIIH in p53-mediated apoptotic cell death. Oncogene 1999; 18:4681-8. [PMID: 10467415 DOI: 10.1038/sj.onc.1202862] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The tumor suppressor gene product p53 can bind to and inhibit the helicase activity of the multisubunit transcription-repair factor TFIIH. We previously reported that p53-mediated apoptosis is attenuated in primary human fibroblasts from individuals with Xeroderma Pigmentosum (XP) that harbor mutations in the TFIIH DNA helicases XPD or XPB. In this study we show that apoptosis is reduced and delayed in three XPD lymphoblastoid cell lines (LCLs), but not in an XPD heterozygote LCL, after exposure to doxorubicin, a DNA-damaging agent and topoisomerase II inhibitor frequently used in cancer therapy. Apoptosis was assessed by quantitation of Annexin V binding to exposed phosphatidylserine residues and by caspase-mediated cleavage of Poly(ADP)Ribose Polymerase (PARP). Apoptosis induced by doxorubicin was suppressed in LCLs retrovirally transduced with the Human Papillomavirus 16 E6 oncoprotein, consistent with the hypothesis that this is a p53-dependent process. PARP cleavage was not delayed in XPD LCLs in response to anti-Fas (CD95) antibody-mediated apoptosis, thus, the defect in the apoptotic pathway in these cells lies upstream of caspase activation. Similar changes in the expression of apoptosis-effector genes, p53, and p53-responsive genes p21Cip1/WAF-1/Sid1 (p21), gadd45, bcl-2 and bax were observed in normal and XPD LCLs after treatment with doxorubicin, indicating that delayed apoptosis was not a consequence of defective transcription of these genes. Thus, our studies provide further support to the hypothesis that XPD and p53 can functionally interact in a p53-mediated apoptotic pathway.
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Affiliation(s)
- A I Robles
- Laboratory of Human Carcinogenesis, Division of Basic Sciences, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, MD 20892-4255, USA
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142
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Friedberg EC, Meira LB. Database of mouse strains carrying targeted mutations in genes affecting cellular responses to DNA damage: version 3. Mutat Res 1999; 433:69-87. [PMID: 10102034 DOI: 10.1016/s0921-8777(98)00068-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- E C Friedberg
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas 75235, USA.
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143
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Harada YN, Shiomi N, Koike M, Ikawa M, Okabe M, Hirota S, Kitamura Y, Kitagawa M, Matsunaga T, Nikaido O, Shiomi T. Postnatal growth failure, short life span, and early onset of cellular senescence and subsequent immortalization in mice lacking the xeroderma pigmentosum group G gene. Mol Cell Biol 1999; 19:2366-72. [PMID: 10022922 PMCID: PMC84028 DOI: 10.1128/mcb.19.3.2366] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The xeroderma pigmentosum group G (XP-G) gene (XPG) encodes a structure-specific DNA endonuclease that functions in nucleotide excision repair (NER). XP-G patients show various symptoms, ranging from mild cutaneous abnormalities to severe dermatological impairments. In some cases, patients exhibit growth failure and life-shortening and neurological dysfunctions, which are characteristics of Cockayne syndrome (CS). The known XPG protein function as the 3' nuclease in NER, however, cannot explain the development of CS in certain XP-G patients. To gain an insight into the functions of the XPG protein, we have generated and examined mice lacking xpg (the mouse counterpart of the human XPG gene) alleles. The xpg-deficient mice exhibited postnatal growth failure and underwent premature death. Since XPA-deficient mice, which are totally defective in NER, do not show such symptoms, our data indicate that XPG performs an additional function(s) besides its role in NER. Our in vitro studies showed that primary embryonic fibroblasts isolated from the xpg-deficient mice underwent premature senescence and exhibited the early onset of immortalization and accumulation of p53.
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Affiliation(s)
- Y N Harada
- The Genome Research Group, National Institute of Radiological Sciences, Inage-ku, Chiba 263, Osaka 565, Japan
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144
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van Steeg H, Kraemer KH. Xeroderma pigmentosum and the role of UV-induced DNA damage in skin cancer. MOLECULAR MEDICINE TODAY 1999; 5:86-94. [PMID: 10200950 DOI: 10.1016/s1357-4310(98)01394-x] [Citation(s) in RCA: 146] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Xeroderma pigmentosum (XP) is a rare, autosomal recessive disease that is characterized by the extreme sensitivity of the skin to sunlight. Compared to normal individuals, XP patients have a more than 1000-fold increased risk of developing cancer on sun-exposed areas of the skin. Genetic and molecular analyses have revealed that the repair of ultraviolet (UV)-induced DNA damage is impaired in XP patients owing to mutations in genes that form part of a DNA-repair pathway known as nucleotide excision repair (NER). Two other diseases, Cockayne syndrome (CS) and the photosensitive form of trichothiodystrophy (TTD), are linked to a defect in the NER pathway. Strikingly, although CS and TTD patients are UV-sensitive, they do not develop skin cancer. The recently developed animal models that mimic the human phenotypes of XP, CS and TTD will contribute to a better understanding of the etiology of these diseases and the role of UV-induced DNA damage in the development of skin cancer.
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Affiliation(s)
- H van Steeg
- National Institute of Public Health and the Environment, Dept of Carcinogenesis, Mutagenesis and Genetics, Bilthoven, The Netherlands.
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145
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de Boer J, Hoeijmakers JH. Cancer from the outside, aging from the inside: mouse models to study the consequences of defective nucleotide excision repair. Biochimie 1999; 81:127-37. [PMID: 10214917 DOI: 10.1016/s0300-9084(99)80045-5] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In recent years, mouse models have been generated to study the syndromes associated with a defect in nucleotide excision repair (NER). Thus, via conventional knockout gene targeting or by mimicking patient-specific alleles, mouse models for xeroderma pigmentosum (XP), Cockayne syndrome (CS) and photosensitive trichothiodystrophy (TTD) have been obtained. The generation of this series of mouse mutants allows in vivo investigation of some intriguing questions that have puzzled the field, such as the paradoxical absence of cancer development in TTD and CS despite their NER deficiencies, and the role of the ERCC1 gene in mitotic recombination and cross-link repair. Other interesting issues include the pathophysiology of the non-NER related clinical symptoms in TTD and CS patients and the proposed involvement of NER and transcription in the process of aging. This review will focus on data obtained thus far and discuss further utilization of the mouse mutants for unraveling some of the fascinating and medically relevant aspects associated with defects in NER and related processes.
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Affiliation(s)
- J de Boer
- MGC-Department of Cell Biology and Genetics, Rotterdam, The Netherlands
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146
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Cox GA, Mahaffey CL, Frankel WN. Identification of the mouse neuromuscular degeneration gene and mapping of a second site suppressor allele. Neuron 1998; 21:1327-37. [PMID: 9883726 DOI: 10.1016/s0896-6273(00)80652-2] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The nmd mouse mutation causes progressive degeneration of spinal motor neurons and muscle atrophy. We identified the mutated gene as the putative transcriptional activator and ATPase/DNA helicase previously described as Smbp2, Rip1, Gf1, or Catf1. Mutations were found in two alleles-a single amino acid deletion in nmdJ and a splice donor mutation in nmd2J. The selective vulnerability of motor neurons is striking in view of the widespread expression of this gene, although the pattern of degeneration may reflect a specific threshold since neither allele is null. In addition, the severity of the nmd phenotype is attenuated in a semidominant fashion by a major genetic locus on chromosome (Chr) 13. The identification of the nmd gene and mapping of a major suppressor provide new opportunities for understanding mechanisms of motor neuron degeneration.
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Affiliation(s)
- G A Cox
- The Jackson Laboratory, Bar Harbor, Maine 04609, USA.
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147
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148
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Affiliation(s)
- J E Cleaver
- Department of Dermatology, University of California, San Francisco 94143-0750, USA
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149
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Jacobs H, Fukita Y, van der Horst GT, de Boer J, Weeda G, Essers J, de Wind N, Engelward BP, Samson L, Verbeek S, de Murcia JM, de Murcia G, te Riele H, Rajewsky K. Hypermutation of immunoglobulin genes in memory B cells of DNA repair-deficient mice. J Exp Med 1998; 187:1735-43. [PMID: 9607915 PMCID: PMC2212309 DOI: 10.1084/jem.187.11.1735] [Citation(s) in RCA: 99] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/1997] [Revised: 02/23/1998] [Indexed: 01/02/2023] Open
Abstract
To investigate the possible involvement of DNA repair in the process of somatic hypermutation of rearranged immunoglobulin variable (V) region genes, we have analyzed the occurrence, frequency, distribution, and pattern of mutations in rearranged Vlambda1 light chain genes from naive and memory B cells in DNA repair-deficient mutant mouse strains. Hypermutation was found unaffected in mice carrying mutations in either of the following DNA repair genes: xeroderma pigmentosum complementation group (XP)A and XPD, Cockayne syndrome complementation group B (CSB), mutS homologue 2 (MSH2), radiation sensitivity 54 (RAD54), poly (ADP-ribose) polymerase (PARP), and 3-alkyladenine DNA-glycosylase (AAG). These results indicate that both subpathways of nucleotide excision repair, global genome repair, and transcription-coupled repair are not required for somatic hypermutation. This appears also to be true for mismatch repair, RAD54-dependent double-strand-break repair, and AAG-mediated base excision repair.
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Affiliation(s)
- H Jacobs
- Basel Institute for Immunology, CH-4005 Basel, Switzerland.
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