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XRCC1 Arg194Trp polymorphism is no risk factor for skin cancer development in Kashmiri population. EGYPTIAN JOURNAL OF MEDICAL HUMAN GENETICS 2018. [DOI: 10.1016/j.ejmhg.2017.07.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Fan J, Fan Y, Kang X, Zhao L. XRCC3 T241M polymorphism and melanoma skin cancer risk: A meta-analysis. Oncol Lett 2015; 9:2425-2429. [PMID: 26137085 DOI: 10.3892/ol.2015.3040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2014] [Accepted: 02/25/2015] [Indexed: 12/12/2022] Open
Abstract
Although the T241M polymorphism in the X-ray cross-complementing group 3 (XRCC3) gene has been implicated in the pathogenesis of melanoma, the results have been inconsistent. In this study, a meta-analysis was performed to assess the association of XRCC3 T241M polymorphism with melanoma. Published literature from PubMed and Embase databases was retrieved. The pooled odds ratio (OR) with 95% confidence interval (CI) was calculated using fixed- or random-effects models. A total of six case-control studies containing 2,133 patients and 3,141 controls were enrolled into this meta-analysis. In a combined analysis, the results revealed no significant association between XRCC3 T241M polymorphism and melanoma risk in the overall population. In the subgroup analysis by ethnicity, no significant associations between the XRCC3 T241M polymorphism and melanoma risk were identified in Caucasians. However, when the analyses were restricted to three larger studies (n>500 cases), a significant association was noted with melanoma (TT vs. MT: OR=1.20, 95% CI=1.04-1.38; dominant model: OR=0.86, 95% CI=0.75-0.98). In conclusion, the meta-analysis results suggest that the XRCC3 T241M polymorphism was associated with risk of melanoma. Further large and well-designed studies are needed to confirm this conclusion.
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Affiliation(s)
- Jinghua Fan
- Department of Dermatology, Xi'an Central Hospital, Medical School of Xi'an Jiaotong University, Xi'an, Shaanxi 710003, P.R. China
| | - Yuhua Fan
- The First Department of Internal Medicine, The Fifth Hospital of Xi'an, Xi'an, Shaanxi 710003, P.R. China
| | - Xiaoxiao Kang
- Department of Dermatology, Xi'an Central Hospital, Medical School of Xi'an Jiaotong University, Xi'an, Shaanxi 710003, P.R. China
| | - Limin Zhao
- Department of Dermatology, Xi'an Central Hospital, Medical School of Xi'an Jiaotong University, Xi'an, Shaanxi 710003, P.R. China
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Aguilar-Fuentes J, Fregoso M, Herrera M, Reynaud E, Braun C, Egly JM, Zurita M. p8/TTDA overexpression enhances UV-irradiation resistance and suppresses TFIIH mutations in a Drosophila trichothiodystrophy model. PLoS Genet 2008; 4:e1000253. [PMID: 19008953 PMCID: PMC2576456 DOI: 10.1371/journal.pgen.1000253] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Accepted: 10/03/2008] [Indexed: 11/25/2022] Open
Abstract
Mutations in certain subunits of the DNA repair/transcription factor complex TFIIH are linked to the human syndromes xeroderma pigmentosum (XP), Cockayne's syndrome (CS), and trichothiodystrophy (TTD). One of these subunits, p8/TTDA, interacts with p52 and XPD and is important in maintaining TFIIH stability. Drosophila mutants in the p52 (Dmp52) subunit exhibit phenotypic defects similar to those observed in TTD patients with defects in p8/TTDA and XPD, including reduced levels of TFIIH. Here, we demonstrate that several Dmp52 phenotypes, including lethality, developmental defects, and sterility, can be suppressed by p8/TTDA overexpression. TFIIH levels were also recovered in rescued flies. In addition, p8/TTDA overexpression suppressed a lethal allele of the Drosophila XPB homolog. Furthermore, transgenic flies overexpressing p8/TTDA were more resistant to UV irradiation than were wild-type flies, apparently because of enhanced efficiency of cyclobutane-pyrimidine-dimers and 6–4 pyrimidine-pyrimidone photoproducts repair. This study is the first using an intact higher-animal model to show that one subunit mutant can trans-complement another subunit in a multi-subunit complex linked to human diseases. TFIIH participates in RNA polymerase II transcription, nucleotide excision repair, and control of the cell cycle. In humans, certain mutations in the XPB and XPD subunits of TFIIH generate the syndromes trichothiodystrophy (TTD), xeroderma pigmentosum (XP), and Cockayne's syndrome (CS). In contrast, mutations in the p8/TTDA subunit have been linked only to TTD. Cells derived from TTD patients with defects in p8/TTDA have reduced levels of TFIIH. Therefore, it has been proposed that the main function of p8/TTDA is to stabilize and maintain steady-state levels of TFIIH. In Drosophila, mutations in Dmp52 and haywire genes generate phenotypes that share similarities with those associated with mutations in their human counterparts, including reduced TFIIH levels. We report that p8/TTDA overexpression suppressed accumulated developmental defects associated with mutations in the Dmp52 and haywire genes. We also provide evidence suggesting that the rescue of these defects is, in part, because of the recovery of normal TFIIH levels in mutant flies. These results indicate that overexpression of p8/TTDA trans-complemented mutations in other TFIIH subunits and suppressed defects accumulated during fly development. The overexpression of p8/TTDA in wild-type flies increased their UV irradiation resistance, apparently because of more efficient nucleotide excision repair.
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Affiliation(s)
- Javier Aguilar-Fuentes
- Department of Developmental Genetics, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, México
| | - Mariana Fregoso
- Department of Developmental Genetics, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, México
| | - Mariana Herrera
- Department of Developmental Genetics, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, México
| | - Enrique Reynaud
- Department of Developmental Genetics, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, México
| | - Cathy Braun
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, C.U. de Strasbourg, France
| | - Jean Marc Egly
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, C.U. de Strasbourg, France
| | - Mario Zurita
- Department of Developmental Genetics, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, México
- * E-mail:
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Fregoso M, Lainé JP, Aguilar-Fuentes J, Mocquet V, Reynaud E, Coin F, Egly JM, Zurita M. DNA repair and transcriptional deficiencies caused by mutations in the Drosophila p52 subunit of TFIIH generate developmental defects and chromosome fragility. Mol Cell Biol 2007; 27:3640-50. [PMID: 17339330 PMCID: PMC1899989 DOI: 10.1128/mcb.00030-07] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The transcription and DNA repair factor TFIIH is composed of 10 subunits. Mutations in the XPB, XPD, and p8 subunits are genetically linked to human diseases, including cancer. However, no reports of mutations in other TFIIH subunits have been reported in higher eukaryotes. Here, we analyze at genetic, molecular, and biochemical levels the Drosophila melanogaster p52 (DMP52) subunit of TFIIH. We found that DMP52 is encoded by the gene marionette in Drosophila and that a defective DMP52 produces UV light-sensitive flies and specific phenotypes during development: organisms are smaller than their wild-type siblings and present tumors and chromosomal instability. The human homologue of DMP52 partially rescues some of these phenotypes. Some of the defects observed in the fly caused by mutations in DMP52 generate trichothiodystrophy and cancer-like phenotypes. Biochemical analysis of DMP52 point mutations introduced in human p52 at positions homologous to those of defects in DMP52 destabilize the interaction between p52 and XPB, another TFIIH subunit, thus compromising the assembly of the complex. This study significantly extends the role of p52 in regulating XPB ATPase activity and, consequently, both its transcriptional and nucleotide excision repair functions.
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Affiliation(s)
- Mariana Fregoso
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, BP 163, 67404 Illkirch Cedex, C.U. de Strasbourg, France
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Aguilar-Fuentes J, Valadez-Graham V, Reynaud E, Zurita M. TFIIH trafficking and its nuclear assembly during early Drosophila embryo development. J Cell Sci 2006; 119:3866-75. [PMID: 16940351 DOI: 10.1242/jcs.03150] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We present the first analysis of the dynamics of the transcription DNA-repair factor TFIIH at the onset of transcription in early Drosophila development. TFIIH is composed of ten polypeptides that are part of two complexes - the core and the CAK. We found that the TFIIH core is initially located in the cytoplasm of syncytial blastoderm embryos, and that after mitotic division ten and until the cellular blastoderm stage, the core moves from the cytoplasm to the nucleus. By contrast, the CAK complex is mostly cytoplasmic during cellularization and during gastrulation. However, both components are positioned at promoters of genes that are activated at transcription onset. Later in development, the CAK complex becomes mostly nuclear and co-localizes in most chromosomal regions with the TFIIH core, but not in all sites, suggesting that the CAK complex could have a TFIIH-independent role in transcription of some loci. We also demonstrate that even though the CAK and the core coexist in the early embryo cytoplasm, they do not interact until they are in the nucleus and suggest that the complete assembly of the ten subunits of TFIIH occurs in the nucleus at the mid-blastula transition. In addition, we present evidence that suggests that DNA helicase subunits XPB and XPD are assembled in the core when they are transported into the nucleus and are required for the onset of transcription.
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Affiliation(s)
- Javier Aguilar-Fuentes
- Department of Developmental Genetics and Molecular Physiology, Institute of Biotechnology, National Autonomous University of México, Av. Universidad 2001, Cuernavaca Morelos 62250, Mexico
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Abstract
AIM: To investigate the effects of inositol hexaphosphate (IP6) on proliferation of HT-29 human colon carcinoma cell line.
METHODS: Cells were exposed to various concen-trations (0, 1.8, 3.3, 5.0, 8.0, 13.0 mmol/L) of IP6 for a certain period of time. Its effect on growth of HT-29 cells was measured by MTT assay. The expressions of cell cycle regulators treated with IP6 for 2 d were detected by immunocytochemistry.
RESULTS: IP6 inhibited the HT-29 cell growth in a dose- and time-dependent manner. Analysis of cell cycle regulator expression revealed that IP6 reduced the abnormal expression of P53 and PCNA and induced the expression of P21.
CONCLUSION: IP6 has potent inhibitory effect on proliferation of HT-29 cells by modulating the expression of special cell cycle regulators.
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Affiliation(s)
- Ying Tian
- Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong Province, China
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Gutiérrez L, Merino C, Vázquez M, Reynaud E, Zurita M. RNA polymerase II 140wimp mutant and mutations in the TFIIH subunit XPB differentially affect homeotic gene expression in Drosophila. Genesis 2005; 40:58-66. [PMID: 15354295 DOI: 10.1002/gene.20066] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Mutations in the XPB and XPD helicases of the DNA repair/transcription factor TFIIH are involved in several human genetic disorders. An unanswered problem concerning the complexity of the phenotype-genotype relationship is why mutations in individual subunits of TFIIH produce specific phenotypes and not many others. In order to investigate this question we tested whether mutations in the Drosophila XPB homolog, haywire (hay), would modify homeotic derepression phenotypes. In this work, we report that mutations in hay and in the 140-kDa subunit of the RNA polymerase II (RpII140wimp) act as dominant modifiers of the derepression phenotypes of the Sex combs reduced (Scr) and Ultrabithorax (Ubx) genes. The hay mutations only weakly suppress the Scr derepression phenotype caused by the Antp(Scx) mutation but not by Polycomb. In contrast, the RpII140wimp mutation strongly suppresses both Scr derepression phenotypes. In addition, the RpII140wimp also generates phenotypes indicative of loss of Ubx function. On the other hand, all the derepression homeotic phenotypes are sensitive to the generalized reduction of transcription levels when the flies are grown with actinomycin D. We also show that different promoter control regions have differential sensitivity to different hay alleles. All these results support that although TFIIH is a basal transcription factor, mutations in the subunit encoded by hay have specific effects in the transcription of some genes.
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Affiliation(s)
- Luis Gutiérrez
- Department of Developmental Genetics and Molecular Physiology, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca Morelos, México
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Yin J, Li J, Ma Y, Guo L, Wang H, Vogel U. The DNA repair gene ERCC2/XPD polymorphism Arg 156Arg (A22541C) and risk of lung cancer in a Chinese population. Cancer Lett 2004; 223:219-26. [PMID: 15896456 DOI: 10.1016/j.canlet.2004.10.032] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2004] [Revised: 10/22/2004] [Accepted: 10/24/2004] [Indexed: 02/03/2023]
Abstract
To determine the effect of the DNA repair gene XPD Arg156Arg polymorphism on the risk of lung cancer in a North-Eastern Chinese population, a hospital-based case-control study was designed consisting of 149 newly diagnosis subjects with lung cancer and 137 cancer-free control subjects matched on age (+/-3 years), gender and ethnicity. In the whole study group, XPD Arg156Arg was not associated with risk of lung cancer. In stratified analyses, the variant A-allele of XPD Arg156Arg was associated with increased risk of adenocarcinoma of lung (AA/AC versus CC; adjusted OR=1.65; 95% CI=1.09-2.50) (P=0.02). Furthermore, the presence of one or two variant A-alleles was associated with increased risk for lung cancer (OR=2.49; 95% CI=1.10-5.64) (P=0.03) and adenocarcinoma of lung (OR=5.60; 95% CI=1.52-20.56) (P=0.005) among never-smokers only. These results suggest a possible gene-environment interaction. This is the first study to report a significant association of XPD Arg156Arg with risk of lung cancer.
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Affiliation(s)
- Jiaoyang Yin
- Institute of Cell Biology, Zhejiang University, Hangzhou (310031), Zhejiang Province, People's Republic of China
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Gospodinov A, Ivanov R, Anachkova B, Russev G. Nucleotide excision repair rates in rat tissues. EUROPEAN JOURNAL OF BIOCHEMISTRY 2003; 270:1000-5. [PMID: 12603333 DOI: 10.1046/j.1432-1033.2003.03473.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have determined and compared nucleotide excision repair capability of several rat tissues by a method based on restoration of the transformation activity of UV-irradiated pBlueScript by incubation in repair-competent protein extracts. After 3 h of incubation, plasmid DNA was isolated and used to transform competent Escherichia coli cells. Damaged plasmids showed low transformation efficiency prior to incubation in repair-competent extracts. After incubation the transformation efficiency was restored to different extents permitting calculation of the repair capacity of the extracts. Our results showed that rapidly proliferating tissues such as liver, kidney and testis showed higher nucleotide excision repair capacity than slowly proliferating tissues such as heart, muscle, lung and spleen. When liver and splenocytes were stimulated to proliferation by partial hepatectomy and mitogen stimulation, their repair capability increased in parallel with the respective proliferative rates.
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Affiliation(s)
- Anastas Gospodinov
- Institute of Molecular Biology, Bulgarian Academy of Sciences, Academic G. Bonchev Street, block 21, 1113 Sofia, Bulgaria
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Dias AP, Braun EL, McMullen MD, Grotewold E. Recently duplicated maize R2R3 Myb genes provide evidence for distinct mechanisms of evolutionary divergence after duplication. PLANT PHYSIOLOGY 2003; 131:610-20. [PMID: 12586885 PMCID: PMC166837 DOI: 10.1104/pp.012047] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2002] [Revised: 09/22/2002] [Accepted: 10/19/2002] [Indexed: 05/17/2023]
Abstract
R2R3 Myb genes are widely distributed in the higher plants and comprise one of the largest known families of regulatory proteins. Here, we provide an evolutionary framework that helps explain the origin of the plant-specific R2R3 Myb genes from widely distributed R1R2R3 Myb genes, through a series of well-established steps. To understand the routes of sequence divergence that followed Myb gene duplication, we supplemented the information available on recently duplicated maize (Zea mays) R2R3 Myb genes (C1/Pl1 and P1/P2) by cloning and characterizing ZmMyb-IF35 and ZmMyb-IF25. These two genes correspond to the recently expanded P-to-A group of maize R2R3 Myb genes. Although the origins of C1/Pl1 and ZmMyb-IF35/ZmMyb-IF25 are associated with the segmental allotetraploid origin of the maize genome, other gene duplication events also shaped the P-to-A clade. Our analyses indicate that some recently duplicated Myb gene pairs display substantial differences in the numbers of synonymous substitutions that have accumulated in the conserved MYB domain and the divergent C-terminal regions. Thus, differences in the accumulation of substitutions during evolution can explain in part the rapid divergence of C-terminal regions for these proteins in some cases. Contrary to previous studies, we show that the divergent C termini of these R2R3 MYB proteins are subject to purifying selection. Our results provide an in-depth analysis of the sequence divergence for some recently duplicated R2R3 Myb genes, yielding important information on general patterns of evolution for this large family of plant regulatory genes.
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Affiliation(s)
- Anusha P Dias
- Plant Genetics Research and Plant Science Units, United States Department of Agriculture-Agricultural Research Service, University of Missouri, Columbia, Missouri 65211, USA
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Dollfus H, Porto F, Caussade P, Speeg-Schatz C, Sahel J, Grosshans E, Flament J, Sarasin A. Ocular manifestations in the inherited DNA repair disorders. Surv Ophthalmol 2003; 48:107-22. [PMID: 12559331 DOI: 10.1016/s0039-6257(02)00400-9] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Deoxyribonucleic acid (DNA) repair is a fundamental process designed to keep the integrity of genomic DNA that is continuously challenged by intrinsic or environmental induced alterations. Numerous genes involved in DNA repair have been cloned and are involved in different DNA repair pathways: base excision repair, nucleotide excision repair, mismatch repair, DNA recombination. Inherited conditions due to mutations in DNA repair genes include mainly: xeroderma pigmentosum, Cockayne syndrome, Trichothiodystrophy, Bloom syndrome, Rothmund-Thomson syndrome, and Werner syndrome. Minor to major ocular manifestations occur in these syndromes. For example, eyelid skin cancers in xeroderma pigmentosum and retinal dystrophy in Cockayne syndrome are major features of these syndromes. This review focuses on the DNA repair pathways, the general and ocular features of the related syndromes, the laboratory tests useful for diagnosis, and the general processes implied with DNA repair (ultraviolet sensitivity, carcinogenesis, apoptosis, oxydative stress, and premature aging).
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Affiliation(s)
- Hélène Dollfus
- Fédération de Génétique Médicale, Clinique Ophtalmologique, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
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12
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Frit P, Kwon K, Coin F, Auriol J, Dubaele S, Salles B, Egly JM. Transcriptional activators stimulate DNA repair. Mol Cell 2002; 10:1391-401. [PMID: 12504014 DOI: 10.1016/s1097-2765(02)00732-3] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
To counteract the deleterious effects of genotoxic injury, cells have set up a sophisticated network of DNA repair pathways. We show that Gal4-VP16 and RAR transcriptional activators stimulate nucleotide excision repair (NER). This DNA repair activation is not coupled to transcription since it occurs in Cockayne syndrome cells (which are transcription-coupled repair deficient) and is observed in vitro in the presence of alpha-amanitin and in the absence of the basal transcription factors. Using a reconstituted dual incision assay, we also show that binding of activators to their cognate sequences induces a local chromatin remodeling mediated by ATP-driven chromatin remodeling and acetyltransferase activities to facilitate DNA repair.
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Affiliation(s)
- Philippe Frit
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, B.P.163, 67404 Cedex, Illkirch, France
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13
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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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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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15
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Bains W. Implications of the network structure of cellular control circuits for the design of anti-cancer vaccine therapies. Med Hypotheses 2002; 58:403-10. [PMID: 12056878 DOI: 10.1054/mehy.2001.1523] [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: 11/18/2022]
Abstract
I describe the use of a statistical mechanical model of a heirarchical network of failure-prone elements as a model for the failure of a network of interconnected biological elements that are or could be involved in the causation of cancer. From its topology, such a model predicts some of the properties of observed oncogene/tumour suppressor gene networks. I show that the same model suggests that a cancer vaccine strategy that targets 'key' network elements, such as p53 or RAS gene products, is not the only effective strategy for a broadly effective anti-cancer therapy. A mixed antigen or whole cell strategy could be as effective as single antigen vaccines, even if the latter are targeted at the most commonly mutated gene products.
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Affiliation(s)
- W Bains
- Amedis Pharmaceuticals, Cambridge, UK.
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16
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Riballo E, Doherty AJ, Dai Y, Stiff T, Oettinger MA, Jeggo PA, Kysela B. Cellular and biochemical impact of a mutation in DNA ligase IV conferring clinical radiosensitivity. J Biol Chem 2001; 276:31124-32. [PMID: 11349135 DOI: 10.1074/jbc.m103866200] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DNA ligase IV functions in DNA non-homologous end-joining, in V(D)J recombination, and during brain development. We previously reported a homozygous mutation (R278H) in DNA ligase IV in a developmentally normal leukemia patient who overresponded to radiotherapy. The impact of this hypomorphic mutation has been evaluated using cellular, biochemical, and structural approaches. Structural modeling using T7 DNA ligase predicts that the activity and conformational stability of the protein is likely to be impaired. We show that wild type DNA ligase IV-Xrcc4 is an efficient double-stranded ligase with distinct optimal requirements for adenylate complex formation versus rejoining. The mutation impairs the formation of an adenylate complex as well as reducing the rejoining activity. Additionally, it imparts temperature-sensitive activity to the protein consistent with the predictions of the structural modeling. At the cellular level, the mutation confers a unique V(D)J recombination phenotype affecting the fidelity of signal joint formation with little effect on the frequency of the reaction. These findings suggest that hypomorphic mutations in ligase IV may allow normal development but confer marked radiosensitivity.
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Affiliation(s)
- E Riballo
- Medical Research Council, Cell Mutation Unit, University of Sussex, Brighton BN1 9RR, United Kingdom
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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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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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19
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Vermeulen W, Bergmann E, Auriol J, Rademakers S, Frit P, Appeldoorn E, Hoeijmakers JH, Egly JM. Sublimiting concentration of TFIIH transcription/DNA repair factor causes TTD-A trichothiodystrophy disorder. Nat Genet 2000; 26:307-13. [PMID: 11062469 DOI: 10.1038/81603] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The repair-deficient form of trichothiodystrophy (TTD) most often results from mutations in the genes XPB or XPD, encoding helicases of the transcription/repair factor TFIIH. The genetic defect in a third group, TTD-A, is unknown, but is also caused by dysfunctioning TFIIH. None of the TFIIH subunits carry a mutation and TFIIH from TTD-A cells is active in both transcription and repair. Instead, immunoblot and immunofluorescence analyses reveal a strong reduction in the TFIIH concentration. Thus, the phenotype of TTD-A appears to result from sublimiting amounts of TFIIH, probably due to a mutation in a gene determining the complex stability. The reduction of TFIIH mainly affects its repair function and hardly influences transcription.
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Affiliation(s)
- W Vermeulen
- Department of Cell Biology and Genetics, Medical Genetics Center, Erasmus University Rotterdam, The Netherlands
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20
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Seroz T, Perez C, Bergmann E, Bradsher J, Egly JM. p44/SSL1, the regulatory subunit of the XPD/RAD3 helicase, plays a crucial role in the transcriptional activity of TFIIH. J Biol Chem 2000; 275:33260-6. [PMID: 10924514 DOI: 10.1074/jbc.m004764200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In order to unravel the mechanism that regulates transcription of protein-coding genes, we investigated the function of the p44 subunit of TFIIH, a basal transcription factor that is also involved in DNA repair. We have shown previously that mutations in the C terminus of the XPD helicase, another subunit of TFIIH, prevent its regulation by p44 (Coin, F., Bergmann, E., Tremeau-Bravard, A., and Egly, J. M. (1999) EMBO 18, 1357-1366). By using a site-directed mutagenesis approach within the p44 region from amino acids 66 to 200, we indicate how a decrease in the interaction between p44 and XPD results in a decrease of the XPD helicase activity and leads to a defect in the first steps of the transcription reaction, namely the first phosphodiester bond formation and promoter clearance. We thus provide some explanation for the transcriptional defect found in SSL1 mutated yeast (Wang, Z., Buratowski, S., Svejstrup, J. Q., Feaver, W. J., Wu, X., Kornberg, R. D., Donahue, T. F., and Friedberg, E. C. (1995) Mol. Cell. Biol. 15, 2288-2293). Moreover, this study shows how the activity of the the cyclin-dependent kinase-activating kinase associated with TFIIH complex in stimulating transcription is mediated in part by p44/XPD interaction.
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Affiliation(s)
- T Seroz
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, B.P.163, 67404 Illkirch Cedex, C.U. de Strasbourg, France
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21
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Rockx DA, Mason R, van Hoffen A, Barton MC, Citterio E, Bregman DB, van Zeeland AA, Vrieling H, Mullenders LH. UV-induced inhibition of transcription involves repression of transcription initiation and phosphorylation of RNA polymerase II. Proc Natl Acad Sci U S A 2000; 97:10503-8. [PMID: 10973477 PMCID: PMC27054 DOI: 10.1073/pnas.180169797] [Citation(s) in RCA: 162] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cells from patients with Cockayne syndrome (CS) are hypersensitive to DNA-damaging agents and are unable to restore damage-inhibited RNA synthesis. On the basis of repair kinetics of different types of lesions in transcriptionally active genes, we hypothesized previously that impaired transcription in CS cells is a consequence of defective transcription initiation after DNA damage induction. Here, we investigated the effect of UV irradiation on transcription by using an in vitro transcription system that allowed uncoupling of initiation from elongation events. Nuclear extracts prepared from UV-irradiated or mock-treated normal human and CS cells were assayed for transcription activity on an undamaged beta-globin template. Transcription activity in nuclear extracts closely mimicked kinetics of transcription in intact cells: extracts from normal cells prepared 1 h after UV exposure showed a strongly reduced activity, whereas transcription activity was fully restored in extracts prepared 6 h after treatment. Extracts from CS cells exhibited reduced transcription activity at any time after UV exposure. Reduced transcription activity in extracts coincided with a strong reduction of RNA polymerase II (RNAPII) containing hypophosphorylated C-terminal domain, the form of RNAPII known to be recruited to the initiation complex. These results suggest that inhibition of transcription after UV irradiation is at least partially caused by repression of transcription initiation and not solely by blocked elongation at sites of lesions. Generation of hypophosphorylated RNAPII after DNA damage appears to play a crucial role in restoration of transcription. CS proteins may be required for this process in a yet unknown way.
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Affiliation(s)
- D A Rockx
- MGC-Department of Radiation Genetics and Chemical Mutagenesis, Leiden University Medical Center, Wassenaarseweg 72, 2333 AL Leiden, The Netherlands
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22
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McCullough AK, Dodson ML, Lloyd RS. Initiation of base excision repair: glycosylase mechanisms and structures. Annu Rev Biochem 2000; 68:255-85. [PMID: 10872450 DOI: 10.1146/annurev.biochem.68.1.255] [Citation(s) in RCA: 291] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The base excision repair pathway is an organism's primary defense against mutations induced by oxidative, alkylating, and other DNA-damaging agents. This pathway is initiated by DNA glycosylases that excise the damaged base by cleavage of the glycosidic bond between the base and the DNA sugar-phosphate backbone. A subset of glycosylases has an associated apurinic/apyrimidinic (AP) lyase activity that further processes the AP site to generate cleavage of the DNA phosphate backbone. Chemical mechanisms that are supported by biochemical and structural data have been proposed for several glycosylases and glycosylase/AP lyases. This review focuses on the chemical mechanisms of catalysis in the context of recent structural information, with emphasis on the catalytic residues and the active site conformations of several cocrystal structures of glycosylases with their substrate DNAs. Common structural motifs for DNA binding and damage specificity as well as conservation of acidic residues and amino groups for catalysis are discussed.
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Affiliation(s)
- A K McCullough
- Sealy Center for Molecular Science, University of Texas Medical Branch, Galveston 77555-1071, USA
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23
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Abstract
Werner syndrome (WS) is one of a group of human genetic diseases that have recently been linked to deficits in cellular helicase function. We review the spectrum of WS-associated WRN mutations, the organization and potential functions of the WRN protein, and potential mechanistic links between the loss of WRN function and pathogenesis of the WS clinical and cellular phenotypes.
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Affiliation(s)
- M J Moser
- Department of Pathology, University of Washington, Seattle 98195-7705, USA
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24
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Abstract
There is growing evidence that recombination is mu;tagenic and that some forms of DNA repair synthesis are error prone. DNA synthesis in mismatch repair might also be error prone. DNA-repair systems detect structural defects in DNA with high efficiency but they occasionally also strike at normal sections of DNA. Considering the diversity of local DNA structure, some DNA sections with complementary sequences are bound to act as preferential false targets for a repair system (i.e. as "illusory defects"). However, if the repair system never changes the sequence upon repair, it will be solicited again and again by the illusory defect, a potentially harmful situation. It is therefore advantageous for a repair system to be, to some extent, error prone. Strong illusory defects may arise at the decanucleotide level and could be the cause of local increases in mutation levels. They might be used to initiate somatic hypermutation pathways.
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Affiliation(s)
- J Ninio
- Laboratoire de Physique Statistique, Ecole Normale Supérieure, 24 rue Lhomond, 75231 Paris Cedex 05, France.
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25
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Brenneisen P, Wenk J, Wlaschek M, Krieg T, Scharffetter-Kochanek K. Activation of p70 ribosomal protein S6 kinase is an essential step in the DNA damage-dependent signaling pathway responsible for the ultraviolet B-mediated increase in interstitial collagenase (MMP-1) and stromelysin-1 (MMP-3) protein levels in human dermal fibroblasts. J Biol Chem 2000; 275:4336-44. [PMID: 10660603 DOI: 10.1074/jbc.275.6.4336] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ultraviolet B (UVB) irradiation has been shown to stimulate the expression of matrix-degrading metalloproteinases via generation of DNA damage and/or reactive oxygen species. Matrix-degrading metalloproteinases promote UVB-triggered detrimental long term effects like cancer formation and premature skin aging. Here, we were interested in identifying components of the signal transduction pathway that causally link UVB-mediated DNA damage and induction of matrix-degrading metalloproteinase (MMP)-1/interstitial collagenase and MMP-3/stromelysin-1 in human dermal fibroblasts in vitro. The activity of p70 ribosomal S6 kinase, a downstream target of the FK506-binding protein-12/rapamycin-associated protein kinase (FRAP) kinase (RAFT1, mTOR), was identified to be 4.8 +/- 0.8-fold, and MMP-1 and MMP-3 protein levels 2.4- and 11.5-fold increased upon UVB irradiation compared with mock-irradiated controls. The FRAP kinase inhibitor rapamycin and the DNA repair inhibitor aphidicolin significantly suppressed the UVB-mediated increase in p70 ribosomal S6 kinase activity by 50-65% and MMP-1 and MMP-3 protein levels by 34-68% and 42-88% compared with UVB-irradiated fibroblasts. By contrast, the interleukin-1beta-mediated increase in MMP-1 and MMP-3 protein levels could not be suppressed by rapamycin. Collectively, our data suggest that the FRAP-controlled p70 ribosomal S6 kinase is an essential component of a DNA damage-dependent, but not of the interleukin-1/cell membrane receptor-dependent signaling.
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Affiliation(s)
- P Brenneisen
- Department of Dermatology, University of Cologne, D-50924 Cologne, Germany
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26
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Berneburg M, Krutmann J. Photoimmunology, DNA repair and photocarcinogenesis. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2000; 54:87-93. [PMID: 10836536 DOI: 10.1016/s1011-1344(00)00024-5] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In recent years major progress has been made in identifying the molecular mechanisms by which UV radiation modulates the immune system of the skin. From these studies it appears that the generation of DNA damage and the subsequent activation of DNA repair enzymes play a critical role in the generation of UV-B-induced immunosuppression. These studies have made use of cells from both nucleotide excision repair (NER)-deficient individuals and mice. Results obtained from these studies have important clinical implications for DNA-repair-deficient patients in particular and for effective photoprotection of human skin in general.
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Affiliation(s)
- M Berneburg
- Department of Dermatology, Heinrich-Heine-University, Düsseldorf, Germany
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27
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Bernstein C, Bernstein H, Payne C. Cell immortality: maintenance of cell division potential. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 1999; 24:23-50. [PMID: 10547857 DOI: 10.1007/978-3-662-06227-2_2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- C Bernstein
- Department of Microbiology and Immunology, College of Medicine, University of Arizona, Tucson 85724, USA
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28
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Li S, Livingstone-Zatchej M, Gupta R, Meijer M, Thoma F, Smerdon MJ. Nucleotide excision repair in a constitutive and inducible gene of a yeast minichromosome in intact cells. Nucleic Acids Res 1999; 27:3610-20. [PMID: 10446254 PMCID: PMC148608 DOI: 10.1093/nar/27.17.3610] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Repair of UV-induced cyclobutane pyrimidine dimers (CPDs) was measured in a yeast minichromosome, having a galactose-inducible GAL1:URA3 fusion gene, a constitutively expressed HIS3 gene and varied regions of chromatin structure. Transcription of GAL1:URA3 increased >150-fold, while HIS3 expression decreased <2-fold when cells were switched from glucose to galactose medium. Following galactose induction, four nucleosomes were displaced or rearranged in the GAL3-GAL10 region. However, no change in nucleosome arrangement was observed in other regions of the minichromosome following induction, indicating that only a few plasmid molecules actively transcribe at any one time. Repair at 269 cis-syn CPD sites revealed moderate preferential repair of the transcribed strand of GAL1:URA3 in galactose, consistent with transcription-coupled repair in a fraction of these genes. Many sites upstream of the transcription start site in the transcribed strand were also repaired faster upon induction. There is remarkable repair heterogeneity in the HIS3 gene and preferential repair is seen only in a short sequence immediately downstream of the transcription start site. Finally, a mild correlation of repair heterogeneity with nucleosome positions was observed in the transcribed strand of the inactive GAL1:URA3 gene and this correlation was abolished upon galactose induction.
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MESH Headings
- Chromatin/metabolism
- Chromosomes, Fungal/genetics
- Chromosomes, Fungal/metabolism
- Chromosomes, Fungal/radiation effects
- DNA Repair
- DNA, Fungal/analysis
- DNA, Fungal/radiation effects
- Genes, Reporter/genetics
- Models, Genetic
- Plasmids
- Pyrimidine Dimers/metabolism
- RNA, Fungal/analysis
- RNA, Fungal/radiation effects
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
- Time Factors
- Transcription, Genetic
- Ultraviolet Rays
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Affiliation(s)
- S Li
- Department of Biochemistry and Biophysics, Washington State University, Pullman, WA 99164-4660, USA
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29
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Chakalova L, Russev G. Transcriptionally active and inactive mouse beta-globin gene loci are repaired at similar rates after ultraviolet irradiation. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 261:667-73. [PMID: 10215882 DOI: 10.1046/j.1432-1327.1999.00332.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
It has been demonstrated, by Northern blot and in situ hybridization, that the mouse erythroleukaemia cell line F4N-Sofia constitutively expresses the beta-globin genes. The recently developed quantitative assay for DNA repair has been used to study the overall repair rate in the beta-globin gene domain in this cell line after ultraviolet irradiation and to compare it with the repair rate of the same chromatin domain in mouse Ehrlich ascites tumour cells which do not express the beta-globin genes. The results showed that in both cases the 5'-end of the domain was repaired preferentially and that the repair rates in the two cell lines were very similar despite the different transcription state of the genes.
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Affiliation(s)
- L Chakalova
- Institute of Molecular Biology, Bulgarian Academy of Sciences, Sofia, Bulgaria
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30
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Reynaud E, Lomelí H, Vázquez M, Zurita M. The Drosophila melanogaster homologue of the Xeroderma pigmentosum D gene product is located in euchromatic regions and has a dynamic response to UV light-induced lesions in polytene chromosomes. Mol Biol Cell 1999; 10:1191-203. [PMID: 10198066 PMCID: PMC25250 DOI: 10.1091/mbc.10.4.1191] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The XPD/ERCC2/Rad3 gene is required for excision repair of UV-damaged DNA and is an important component of nucleotide excision repair. Mutations in the XPD gene generate the cancer-prone syndrome, xeroderma pigmentosum, Cockayne's syndrome, and trichothiodystrophy. XPD has a 5'- to 3'-helicase activity and is a component of the TFIIH transcription factor, which is essential for RNA polymerase II elongation. We present here the characterization of the Drosophila melanogaster XPD gene (DmXPD). DmXPD encodes a product that is highly related to its human homologue. The DmXPD protein is ubiquitous during development. In embryos at the syncytial blastoderm stage, DmXPD is cytoplasmic. At the onset of transcription in somatic cells and during gastrulation in germ cells, DmXPD moves to the nuclei. Distribution analysis in polytene chromosomes shows that DmXPD is highly concentrated in the interbands, especially in the highly transcribed regions known as puffs. UV-light irradiation of third-instar larvae induces an increase in the signal intensity and in the number of sites where the DmXPD protein is located in polytene chromosomes, indicating that the DmXPD protein is recruited intensively in the chromosomes as a response to DNA damage. This is the first time that the response to DNA damage by UV-light irradiation can be visualized directly on the chromosomes using one of the TFIIH components.
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Affiliation(s)
- E Reynaud
- Department of Genetics and Molecular Physiology, Institute of Biotechnology, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62250 México
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31
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Frolov MV, Birchler JA. Mutation in P0, a dual function ribosomal protein/apurinic/apyrimidinic endonuclease, modifies gene expression and position effect variegation in Drosophila. Genetics 1998; 150:1487-95. [PMID: 9832526 PMCID: PMC1460415 DOI: 10.1093/genetics/150.4.1487] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In a search for modifiers of gene expression with the white eye color gene as a target, a third chromosomal P-element insertion mutant l(3)01544 has been identified that exhibits a strong pigment increase in a white-apricot background. Molecular analysis shows that the P-element insertion is found in the first intron of the gene surrounding the insertion site. Sequencing both the cDNA and genomic fragments revealed that the identified gene is identical to one encoding ribosomal protein P0/apurinic/apyrimidinic endonuclease. The P-element-induced mutation, l(3)01544, affects the steady-state level of white transcripts and transcripts of some other genes. In addition, l(3)01544 suppresses the variegated phenotypes of In(1)wm4h and In(1)y3P, suggesting a potential involvement of the P0 protein in modifying position effect variegation. The revertant generated by the precise excision of the P element has lost all mutant phenotypes. Recent work revealed that Drosophila ribosomal protein P0 contains an apurinic/apyrimidinic endonuclease activity. Our results suggest that this multifunctional protein is also involved in regulation of gene expression in Drosophila.
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Affiliation(s)
- M V Frolov
- University of Missouri, Columbia, Missouri 65211, USA
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32
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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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