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Stefos GC, Szantai E, Konstantopoulos D, Samiotaki M, Fousteri M. aniFOUND: analysing the associated proteome and genomic landscape of the repaired nascent non-replicative chromatin. Nucleic Acids Res 2021; 49:e64. [PMID: 33693861 DOI: 10.1093/nar/gkab144] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 02/01/2021] [Accepted: 02/22/2021] [Indexed: 12/13/2022] Open
Abstract
Specific capture of chromatin fractions with distinct and well-defined features has emerged as both challenging and a key strategy towards a comprehensive understanding of genome biology. In this context, we developed aniFOUND (accelerated native isolation of factors on unscheduled nascent DNA), an antibody-free method, which can label, capture, map and characterise nascent chromatin fragments that are synthesized in response to specific cues outside S-phase. We used the 'unscheduled' DNA synthesis (UDS) that takes place during the repair of UV-induced DNA lesions and coupled the captured chromatin to high-throughput analytical technologies. By mass-spectrometry we identified several factors with no previously known role in UVC-DNA damage response (DDR) as well as known DDR proteins. We experimentally validated the repair-dependent recruitment of the chromatin remodeller RSF1 and the cohesin-loader NIPBL at sites of UVC-induced photolesions. Developing aniFOUND-seq, a protocol for mapping UDS activity with high resolution, allowed us to monitor the landscape of UVC repair-synthesis events genome wide. We further resolved repair efficacy of the rather unexplored repeated genome, in particular rDNA and telomeres. In summary, aniFOUND delineates the proteome composition and genomic landscape of chromatin loci with specific features by integrating state-of-the-art 'omics' technologies to promote a comprehensive view of their function.
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Affiliation(s)
- Georgios C Stefos
- Institute for Fundamental Biomedical Research, BSRC 'Alexander Fleming', Vari 16672, Greece
| | - Eszter Szantai
- Institute for Fundamental Biomedical Research, BSRC 'Alexander Fleming', Vari 16672, Greece
| | | | | | - Maria Fousteri
- Institute for Fundamental Biomedical Research, BSRC 'Alexander Fleming', Vari 16672, Greece
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2
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Yang Y, Hu J, Selby CP, Li W, Yimit A, Jiang Y, Sancar A. Single-nucleotide resolution analysis of nucleotide excision repair of ribosomal DNA in humans and mice. J Biol Chem 2018; 294:210-217. [PMID: 30413533 DOI: 10.1074/jbc.ra118.006121] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Indexed: 12/15/2022] Open
Abstract
The unique nucleolar environment, the repetitive nature of ribosomal DNA (rDNA), and especially the possible involvement of RNA polymerase I (RNAPI) in transcription-coupled repair (TCR) have made the study of repair of rDNA both interesting and challenging. TCR, the transcription-dependent, preferential excision repair of the template strand compared with the nontranscribed (coding) strand has been clearly demonstrated in genes transcribed by RNAPII. Whether TCR occurs in rDNA is unresolved. In the present work, we have applied analytical methods to map repair events in rDNA using data generated by the newly developed XR-seq procedure, which measures excision repair genome-wide with single-nucleotide resolution. We find that in human and mouse cell lines, rDNA is not subject to TCR of damage caused by UV or by cisplatin.
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Affiliation(s)
- Yanyan Yang
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Jinchuan Hu
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599; Fifth People's Hospital of Shanghai and Institute of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Christopher P Selby
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Wentao Li
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Askar Yimit
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Yuchao Jiang
- Departments of Biostatistics and Genetics, University of North Carolina, Chapel Hill, North Carolina 27599; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599.
| | - Aziz Sancar
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599.
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3
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Charton R, Guintini L, Peyresaubes F, Conconi A. Repair of UV induced DNA lesions in ribosomal gene chromatin and the role of "Odd" RNA polymerases (I and III). DNA Repair (Amst) 2015; 36:49-58. [PMID: 26411875 DOI: 10.1016/j.dnarep.2015.09.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
In fast growing eukaryotic cells, a subset of rRNA genes are transcribed at very high rates by RNA polymerase I (RNAPI). Nuclease digestion-assays and psoralen crosslinking have shown that they are open; that is, largely devoid of nucleosomes. In the yeast Saccharomyces cerevisae, nucleotide excision repair (NER) and photolyase remove UV photoproducts faster from open rRNA genes than from closed and nucleosome-loaded inactive rRNA genes. After UV irradiation, rRNA transcription declines because RNAPI halt at UV photoproducts and are then displaced from the transcribed strand. When the DNA lesion is quickly recognized by NER, it is the sub-pathway transcription-coupled TC-NER that removes the UV photoproduct. If dislodged RNAPI are replaced by nucleosomes before NER recognizes the lesion, then it is the sub-pathway global genome GG-NER that removes the UV photoproducts from the transcribed strand. Also, GG-NER maneuvers in the non-transcribed strand of open genes and in both strands of closed rRNA genes. After repair, transcription resumes and elongating RNAPI reopen the rRNA gene. In higher eukaryotes, NER in rRNA genes is inefficient and there is no evidence for TC-NER. Moreover, TC-NER does not occur in RNA polymerase III transcribed genes of both, yeast and human fibroblast.
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Affiliation(s)
- Romain Charton
- Département de Microbiologie et Infectiologie, Faculté de Médecine, Université de Sherbrooke, Sherbrooke, QC J1E 4K8, Canada
| | - Laetitia Guintini
- Département de Microbiologie et Infectiologie, Faculté de Médecine, Université de Sherbrooke, Sherbrooke, QC J1E 4K8, Canada
| | - François Peyresaubes
- Département de Microbiologie et Infectiologie, Faculté de Médecine, Université de Sherbrooke, Sherbrooke, QC J1E 4K8, Canada
| | - Antonio Conconi
- Département de Microbiologie et Infectiologie, Faculté de Médecine, Université de Sherbrooke, Sherbrooke, QC J1E 4K8, Canada.
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Cramers P, Filon AR, Pines A, Kleinjans JC, Mullenders LHF, van Zeeland AA. Enhanced nucleotide excision repair in human fibroblasts pre-exposed to ionizing radiation. Photochem Photobiol 2011; 88:147-53. [PMID: 22017241 DOI: 10.1111/j.1751-1097.2011.01019.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Cellular protection against deleterious effects of DNA damaging agents requires an intricate network of defense mechanisms known as the DNA damage response (DDR). Ionizing radiation (IR) mediated activation of the DDR induces a transcriptional upregulation of genes that are also involved in nucleotide excision repair (NER). This suggests that pre-exposure to X-rays might stimulate NER in human cells. Here, we demonstrate in normal human fibroblasts that UV-induced NER is augmented by pre-exposure to IR and that this increased repair is accompanied by elevated mRNA and protein levels of the NER factors XPC and DDB2. Furthermore, when IR exposure precedes local UV irradiation, the presence of XPC and DDB2 at the sites of local UV damages is increased. This increase might be p53 dependent, but the mechanism of X-ray specific stabilization of p53 is unclear as both X-rays and UV stabilize p53.
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Affiliation(s)
- Patricia Cramers
- Department of Toxicogenetics, Leiden University Medical Center, Leiden, The Netherlands
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5
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Cramers P, Verhoeven EE, Filon AR, Rockx DAP, Santos SJ, van der Leer AA, Kleinjans JCS, van Zeeland AA, Mullenders LHF. Impaired repair of ionizing radiation-induced DNA damage in Cockayne syndrome cells. Radiat Res 2011; 175:432-43. [PMID: 21299404 DOI: 10.1667/rr1972.1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Cockayne syndrome (CS) cells are defective in transcription-coupled repair (TCR) and sensitive to oxidizing agents, including ionizing radiation. We examined the hypothesis that TCR plays a role in ionizing radiation-induced oxidative DNA damage repair or alternatively that CS plays a role in transcription elongation after irradiation. Irradiation with doses up to 100 Gy did not inhibit RNA polymerase II-dependent transcription in normal and CS-B fibroblasts. In contrast, RNA polymerase I-dependent transcription was severely inhibited at 5 Gy in normal cells, indicating different mechanisms of transcription response to X rays. The frequency of radiation-induced base damage was 2 × 10(-7) lesions/base/Gy, implying that 150 Gy is required to induce one lesion/30-kb transcription unit; no TCR of X-ray-induced base damage in the p53 gene was observed. Therefore, it is highly unlikely that defective TCR underlies the sensitivity of CS to ionizing radiation. Overall genome repair levels of radiation-induced DNA damage measured by repair replication were significantly reduced in CS-A and CS-B cells. Taken together, the results do not provide evidence for a key role of TCR in repair of radiation-induced oxidative damages in human cells; rather, impaired repair of oxidative lesions throughout the genome may contribute to the CS phenotype.
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Affiliation(s)
- Patricia Cramers
- Department of Toxicogenetics, Leiden University Medical Center, Einthovenweg 20, 2300 RC Leiden, The Netherlands
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6
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Schmitz KM, Schmitt N, Hoffmann-Rohrer U, Schäfer A, Grummt I, Mayer C. TAF12 recruits Gadd45a and the nucleotide excision repair complex to the promoter of rRNA genes leading to active DNA demethylation. Mol Cell 2009; 33:344-53. [PMID: 19217408 DOI: 10.1016/j.molcel.2009.01.015] [Citation(s) in RCA: 147] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2008] [Revised: 12/11/2008] [Accepted: 01/27/2009] [Indexed: 11/28/2022]
Abstract
Many studies have detailed the repressive effects of DNA methylation on gene expression. However, the mechanisms that promote active demethylation are just beginning to emerge. Here, we show that methylation of the rDNA promoter is a dynamic and reversible process. Demethylation of rDNA is initiated by recruitment of Gadd45a (growth arrest and DNA damage inducible protein 45 alpha) to the rDNA promoter by TAF12, a TBP-associated factor that is contained in Pol I- and Pol II-specific TBP-TAF complexes. Once targeted to rDNA, Gadd45a triggers demethylation of promoter-proximal DNA by recruiting the nucleotide excision repair (NER) machinery to remove methylated cytosines. Knockdown of Gadd45a, XPA, XPG, XPF, or TAF12 or treatment with drugs that inhibit NER causes hypermethylation of rDNA, establishes heterochromatic histone marks, and impairs transcription. The results reveal a mechanism that recruits the DNA repair machinery to the promoter of active genes, keeping them in a hypomethylated state.
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Affiliation(s)
- Kerstin-Maike Schmitz
- Division of Molecular Biology of the Cell II, German Cancer Research Center, DKFZ-ZMBH Alliance, INF 581, D-69120 Heidelberg, Germany
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7
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Manova V, Gecheff K, Stoilov L. Efficient repair of bleomycin-induced double-strand breaks in barley ribosomal genes. Mutat Res 2006; 601:179-90. [PMID: 16930631 DOI: 10.1016/j.mrfmmm.2006.07.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2005] [Revised: 06/28/2006] [Accepted: 07/11/2006] [Indexed: 05/11/2023]
Abstract
Ability of barley ribosomal genes to cope with damage produced in vivo by the radiomimetic agent bleomycin was investigated. Repair kinetics of bleomycin-induced double-strand breaks in ribosomal and total genomic DNA was compared. Induction and repair of double-strand breaks in defined regions of the ribosomal genes was also analyzed. Preferential sensitivity of barley linker DNA towards bleomycin treatment in vivo was established. Relatively higher yield of initially induced double-strand breaks in genomic DNA in comparison to ribosomal DNA was also found. Fragments containing intergenic spacers of barley rRNA genes displayed higher sensitivity to bleomycin than the coding sequences. No heterogeneity in the repair of DSB between transcribed and non-transcribed regions of ribosomal genes was detected. Data indicate that DSB repair in barley rDNA, although more efficient than in genomic DNA, does not correlate with the activity of nucleolus organizer regions.
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Affiliation(s)
- Vasilissa Manova
- Department of Molecular Genetics, Institute of Genetics, Acad D Kostoff, BAS, Sofia, Bulgaria
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8
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Oliva-Trastoy M, Trastoy MO, Defais M, Larminat F. Resistance to the antibiotic Zeocin by stable expression of the Sh ble gene does not fully suppress Zeocin-induced DNA cleavage in human cells. Mutagenesis 2005; 20:111-4. [PMID: 15755800 DOI: 10.1093/mutage/gei016] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Zeocin is a member of the bleomycin/phleomycin family of antibiotics, known to bind and cleave DNA. We established human SK-OV-3 cells that stably express the Zeocin resistance gene (Sh ble) using an ecdysone-inducible mammalian expression system. Surprisingly, our results demonstrated that Zeocin, added in the culture medium to maintain the expression of the ecdysone receptor, was responsible for the formation of DNA strand breaks in the recombinant cells. This suggests that the Zeocin is not completely detoxified and is still able to cleave DNA, despite the stable expression of the Sh ble gene in the recombinant clones. Our study indicates that one needs to be very cautious in the interpretation of data involving stable cell lines selected with Zeocin.
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Prashanth Kumar V, Ravishankara M, Padh H, Rajani M. High-performance thin-layer chromatographic method for estimation of rutin in medicinal plants. JPC-J PLANAR CHROMAT 2003. [DOI: 10.1556/jpc.16.2003.5.11] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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10
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Abstract
Barley nucleolus organizing regions (NORs) were previously found to behave as prominent aberration hot-spots after treatment with some restriction endonucleases. The ability of MspI for directed induction of double-strand breaks in barley ribosomal DNA was further analyzed. Ionizing radiation-produced strand breakage within the ribosomal gene clusters was also a subject of investigation. Reconstructed barley karyotypes T1586 and T35 with normal and increased expression of rRNA genes were utilized to evaluate the relationship between transcriptional activity and damage induction. Scanning densitometry of the hybridization profiles revealed that MspI is generating double-strand breaks in barley rDNA with efficiency being independent from the NOR activity. Damage induction observed after treatment with gamma-rays was also not influenced by the transcriptional status of the ribosomal genes. A tendency towards restoration of rDNA integrity after irradiation of both germinating and dry seeds was observed which is indicative for the efficient recovery of double-strand breaks in barley ribosomal DNA.
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Affiliation(s)
- Vasilissa I Manova
- Department of Molecular Genetics, Bulgarian Academy of Sciences, Institute of Genetics Acad. D. Kostoff, Sofia 1113, Bulgaria
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11
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Meier A, Livingstone-Zatchej M, Thoma F. Repair of active and silenced rDNA in yeast: the contributions of photolyase and transcription-couples nucleotide excision repair. J Biol Chem 2002; 277:11845-52. [PMID: 11805105 DOI: 10.1074/jbc.m110941200] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DNA repair by photolyase (photoreactivation) and nucleotide excision repair (NER) are the major pathways to remove UV-induced cyclobutane-pyrimidine dimers (CPDs). The nucleolus is a nuclear subcompartment containing the ribosomal RNA genes (rDNA) of which a fraction is transcribed by RNA polymerase I (RNAP-I), and the rest is silenced. Here yeast was used to investigate how photoreactivation and NER contribute to repair of active and inactive rDNA. Cells were irradiated with UV light and exposed to different repair conditions. Nuclei were isolated, and the active genes were separated from the inactive genes by restriction endonuclease digestion. CPDs were measured in total rDNA, in both fractions, and in the GAL10 gene. Repair in rDNA was as efficient as in GAL10 indicating that both pathways have unrestricted access to the nucleolus. Photoreactivation was much faster than NER and therefore was the predominant repair pathway. Active genes were faster repaired by photolyase than were silenced genes providing evidence for an open chromatin structure during repair. The transcribed strands of active genes, but not of inactive genes, were slightly faster repaired by NER providing evidence for transcription-coupled repair by RNAP-I. There was no pronounced inhibition of photoreactivation by RNAP-I in the transcribed strand, which is in contrast to genes transcribed by RNAP-II and suggests different stabilities of RNAP-I and RNAP-II stalled at CPDs.
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Affiliation(s)
- Andreas Meier
- Institut für Zellbiologie, Departement Biologie, Eidgenössische Technische Hochschule (ETH), Hönggerberg, CH-8093 Zürich, Switzerland
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12
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Conconi A, Bespalov VA, Smerdon MJ. Transcription-coupled repair in RNA polymerase I-transcribed genes of yeast. Proc Natl Acad Sci U S A 2002; 99:649-54. [PMID: 11782531 PMCID: PMC117360 DOI: 10.1073/pnas.022373099] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nucleotide excision repair (NER) of UV-induced cyclobutane pyrimidine dimers (CPDs) was measured in the individual strands of transcriptionally active and inactive ribosomal genes of yeast. Ribosomal genes (rDNA) are present in multiple copies, but only a fraction of them is actively transcribed. Restriction enzyme digestion was used to specifically release the transcriptionally active fraction from yeast nuclei, and selective psoralen crosslinking was used to distinguish between active and inactive rDNA chromatin. Removal of CPDs was followed in both rDNA populations, and the data clearly show that strand-specific repair occurs in transcriptionally active rDNA while being absent in the inactive rDNA fraction. Thus, transcription-coupled repair occurs in RNA polymerase I-transcribed genes in yeast. Moreover, the nontranscribed strand of active rDNA is repaired faster than either strand of inactive rDNA, implying that NER has preferred access to the active, non-nucleosomal rDNA chromatin. Finally, restriction enzyme accessibility to active rDNA varies during NER, suggesting that there is a change in ribosomal gene chromatin structure during or soon after CPD removal.
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Affiliation(s)
- Antonio Conconi
- Biochemistry and Biophysics, School of Molecular Biosciences, Washington State University, Pullman, WA 99164-4660, USA
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13
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Tomilin NV, Solovjeva LV, Svetlova MP, Pleskach NM, Zalenskaya IA, Yau PM, Bradbury EM. Visualization of focal nuclear sites of DNA repair synthesis induced by bleomycin in human cells. Radiat Res 2001; 156:347-54. [PMID: 11554846 DOI: 10.1667/0033-7587(2001)156[0347:vofnso]2.0.co;2] [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: 11/03/2022]
Abstract
In this study, we examined DNA repair synthesis in human cells treated with the radiomimetic drug bleomycin, which efficiently induces double-strand breaks (DSBs). Using tyramide-biotin to amplify fluorescent signals, discrete nuclear foci from the incorporation of 5-iododeoxyuridine (IdU) were detected in proliferating human cells treated with bleomycin. We believe this comes from the repair of DSBs. An increase in the number of foci (>5 per nucleus) was detected in a major fraction (75%) of non-S-phase cells labeled for 30 min with IdU 1 h after the end of bleomycin treatment. The fraction of cells with multiple IdU-containing foci was found to decrease 18 h after treatment. The average number of foci per nucleus detected 1 h after bleomycin treatment was found to decrease twofold between 1 and 3.5 h, indicating that the foci may be associated with the slow component of DSB repair. The presence of DSBs in bleomycin-treated cells was confirmed using antibodies against phosphorylated histone H2AX (gamma-H2AX), which is strictly associated with this type of DNA damage. After treatment with bleomycin, non-S-phase cells also displayed heterogeneous nuclear foci containing tightly bound proliferating cell nuclear antigen (PCNA), suggesting an ongoing process of unscheduled DNA synthesis. PCNA is known to be involved in base excision repair, but a fraction of the PCNA foci may also be associated with DNA synthesis occurring during the repair of DSBs.
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Affiliation(s)
- N V Tomilin
- Laboratory of Chromosome Stability, Institute of Cytology, The Russian Academy of Sciences, 194064 St. Petersburg, Russia.
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Stivala LA, Riva F, Cazzalini O, Savio M, Prosperi E. p21(waf1/cip1)-null human fibroblasts are deficient in nucleotide excision repair downstream the recruitment of PCNA to DNA repair sites. Oncogene 2001; 20:563-70. [PMID: 11313988 DOI: 10.1038/sj.onc.1204132] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2000] [Revised: 11/07/2000] [Accepted: 11/23/2000] [Indexed: 11/09/2022]
Abstract
The cyclin-dependent kinase inhibitor p21(waf1/cip1) is known to impair DNA synthesis by binding to PCNA, the co-factor of DNA polymerases delta and epsilon. However, a positive role for p21 in nucleotide excision repair (NER) has been suggested. In this study, the sensitivity to DNA damage and DNA repair efficiency were investigated in p21-null human fibroblasts obtained by targeted homologous recombination. After UV-C irradiation, p21-/- cells showed a threefold reduction in clonogenic survival and an increased susceptibility to apoptosis, as compared with parental p21+/+ cells. Removal of cyclobutane pyrimidine dimers was significantly reduced in p21-/- cells both in the whole genome, and at the level of the rDNA gene cluster, as determined by immunoassay and Southern blot, respectively. After DNA damage, the recruitment of PCNA as detergent-insoluble form associated to DNA repair sites in p21-/- fibroblasts, was comparable to that observed in parental p21+/+ cells. However, PCNA remained associated with DNA for a longer period in p21-/- than in p21+/+ cells. These results suggest that in human cells, p21 is required for NER at a step located downstream the recruitment of PCNA to DNA repair sites.
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Affiliation(s)
- L A Stivala
- Dipartimento di Medicina Sperimentale, sez. Patologia generale, Università di Pavia, Italy
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15
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Hannan RD, Cavanaugh A, Hempel WM, Moss T, Rothblum L. Identification of a mammalian RNA polymerase I holoenzyme containing components of the DNA repair/replication system. Nucleic Acids Res 1999; 27:3720-7. [PMID: 10471742 PMCID: PMC148628 DOI: 10.1093/nar/27.18.3720] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Traditional models for transcription initiation by RNA polymerase I include a stepwise assembly of basic transcription factors/regulatory proteins on the core promoter to form a preinitiation complex. In contrast, we have identified a preassembled RNA polymerase I (RPI) complex that contains all the factors necessary and sufficient to initiate transcription from the rDNA promoter in vitro. The purified RPI holoenzyme contains the RPI homolog of TFIID, SL-1 and the rDNA transcription terminator factor (TTF-1), but lacks UBF, an activator of rDNA transcription. Certain components of the DNA repair/replication system, including Ku70/80, DNA topoisomerase I and PCNA, are also associated with the RPI complex. We have found that the holo-enzyme supported specific transcription and that specific transcription was stimulated by the RPI transcription activator UBF. These results support the hypothesis that a fraction of the RPI exists as a preassembled, transcriptionally competent complex that is readily recruited to the rDNA promoter, i.e. as a holoenzyme, and provide important new insights into the mechanisms governing initiation by RPI.
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Affiliation(s)
- R D Hannan
- Cancer Research Centre and Department of Biochemistry, Laval University, Hotel-Dieu de Quebec, 11 Cote du Palais, Quebec G1R 2J6, Canada
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16
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Conconi A, Liu X, Koriazova L, Ackerman EJ, Smerdon MJ. Tight correlation between inhibition of DNA repair in vitro and transcription factor IIIA binding in a 5S ribosomal RNA gene. EMBO J 1999; 18:1387-96. [PMID: 10064604 PMCID: PMC1171228 DOI: 10.1093/emboj/18.5.1387] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
UV-induced photoproducts (cyclobutane pyrimidine dimers, CPDs) in DNA are removed by nucleotide excision repair (NER), and the presence of transcription factors on DNA can restrict the accessibility of NER enzymes. We have investigatigated the modulation of NER in a gene promoter using the Xenopus transcription factor IIIA (TFIIIA)-5S rDNA complex and Xenopus oocyte nuclear extracts. TFIIIA alters CPD formation primarily in the transcribed strand of the 50 bp internal control region (ICR) of 5S rDNA. During NER in vitro, CPD removal is reduced at most sites in both strands of the ICR when TFIIIA is bound. Efficient repair occurs just outside the TFIIIA-binding site (within 10 bp), and in the absence of 5S rRNA transcription. Interestingly, three CPD sites within the ICR [+56, +75 (transcribed strand) and +73 (non-transcribed strand)] are repaired rapidly when TFIIIA is bound, while CPDs within approximately 5 bases of these sites are repaired much more slowly. CPDs at these three sites may partially displace TFIIIA, thereby enabling rapid repair. However, TFIIIA is not completely displaced during NER, at least at sites outside the ICR, even though the NER complex could be sterically hindered by TFIIIA. Such inefficient repair of transcription factor binding sites could increase mutation frequency in regulatory regions of genes.
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Affiliation(s)
- A Conconi
- Department of Biochemistry and Biophysics, Washington State University, Pullman, WA 99164-4660, USA
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17
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Smerdon MJ, Conconi A. Modulation of DNA damage and DNA repair in chromatin. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1999; 62:227-55. [PMID: 9932456 DOI: 10.1016/s0079-6603(08)60509-7] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
DNA is packaged in the highly compact and dynamic structure of chromatin in eukaryotic cells. It is generally accepted that DNA processing events in the nucleus, such as transcription, replication, recombination, and repair, are restricted by this packaging. For some processes (e.g., transcription), the chromatin fiber is "preset" in a more open structure to allow access of proteins to specific regions of DNA within this structural hierarchy. These regions contain modified nucleosomes that accommodate a less compact state of chromatin and allow access to specific regions of DNA. DNA repair proteins, however, must access DNA lesions in all structural domains of chromatin after sudden insult to the genome. Damaged DNA must be recognized, removed, and replaced by repair enzymes at all levels of chromatin packaging. Therefore, the modulation of DNA damage and its repair in chromatin is crucial to our understanding of the fate of potential mutagenic and carcinogenic lesions in DNA. In this review, we discuss the modulation of DNA damage and DNA repair by chromatin structure, and the modulation of chromatin structure by these events.
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Affiliation(s)
- M J Smerdon
- Department of Biochemistry and Biophysics, Washington State University, Pullman 99164, USA
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Monnat RJ, Hackmann AF, Cantrell MA. Generation of highly site-specific DNA double-strand breaks in human cells by the homing endonucleases I-PpoI and I-CreI. Biochem Biophys Res Commun 1999; 255:88-93. [PMID: 10082660 DOI: 10.1006/bbrc.1999.0152] [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: 11/22/2022]
Abstract
We have determined the ability of two well-characterized eukaryotic homing endonucleases, I-PpoI from the myxomycete Physarum polycephalum and I-CreI from the green alga Chlamydomonas reinhardtii, to generate site-specific DNA double-strand breaks in human cells. These 18-kDa proteins cleave highly conserved 15- or 24-bp rDNA homing sites in their respective hosts to generate homogeneous 4-base, 3' ends that initiate target intron transposition or "homing." We show that both endonucleases can be expressed in human cells and can generate site-specific DNA double-strand breaks in 28S rDNA and homing site plasmids. These endonuclease-induced breaks can be repaired in vivo, although break repair is mutagenic with the frequent generation of short deletions or insertions. I-PpoI and I-CreI should be useful for analyzing DNA double-strand break repair in human cells and rDNA.
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Affiliation(s)
- R J Monnat
- Department of Pathology, University of Washington, Seattle, Washington 98195, USA.
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Baxter BK, Smerdon MJ. Nucleosome unfolding during DNA repair in normal and xeroderma pigmentosum (group C) human cells. J Biol Chem 1998; 273:17517-24. [PMID: 9651343 DOI: 10.1074/jbc.273.28.17517] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The fate of nucleosomes during nucleotide excision repair is unclear. We have used organomercurial chromatography to capture accessible thiol groups of proteins at (or near) nascent repair sites in normal and xeroderma pigmentosum (group C) human cells. The reactive groups include cysteine 110 of histone H3, which is exposed in unfolded nucleosomes. Immediately after UV irradiation and a short pulse labeling of repair patches, intact nuclei were digested with restriction enzymes to release approximately 18% of the chromatin into soluble fragments, which are enriched (approximately 4-fold) in a constitutively transcribed gene. Upon organomercurial affinity fractionation, approximately 1.8% of the soluble chromatin remains bound in high salt (0.5 M NaCl) and is released with dithiothreitol. In normal cell chromatin, this fraction is enriched in nascent repair patches (1.5-1.8-fold) over the unbound fraction. This enrichment decreases following short chase periods with a time course similar to the loss of enhanced nuclease sensitivity of these regions (t 1/2 approximately 30 min). Much less enrichment of nascent repair patches is observed in the thiol-reactive fraction from XPC cells, which repair primarily the transcribed strand of active genes. These results suggest that transient nucleosome unfolding occurs during nucleotide excision repair in normal human cells, and this unfolding may require the XPC protein.
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Affiliation(s)
- B K Baxter
- Department of Biochemistry and Biophysics, P.O. Box 644660, Washington State University, Pullman, Washington 99164-4660, USA
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Grishko VI, Driggers WJ, LeDoux SP, Wilson GL. Repair of oxidative damage in nuclear DNA sequences with different transcriptional activities. Mutat Res 1997; 384:73-80. [PMID: 9298116 DOI: 10.1016/s0921-8777(97)00017-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
This study was designed to investigate the repair of oxidative damage in nuclear DNA sequences with different transcriptional activities. Chinese hamster ovary (CHO) cells were treated with the oxygen radical generator hypoxanthine/xanthine oxidase (Hyp/XO). Damage and repair were evaluated in 14-kb restriction fragments containing either the DHFR gene, a 3'-non-transcribed flanking region, or the c-fos gene using a quantitative Southern blot technique. Damage to the sugar-phosphate backbone and abasic sites were detected by measuring their lability in alkali conditions. Lesions in DNA bases were identified using the bacterial repair enzyme endonuclease III, which predominantly recognizes damage to thymines and cytosines, and formamidopyrimidine-DNA glycosylase, which recognizes 8-oxoguanine and purines with fractured imidazole rings. The results showed that similar amounts of all types of oxidative damage were produced in both the transcribed and non-transcribed sequences following a 1-h exposure to the radical generator. Repair in all sequences was rapid, with approximately 60% removal of lesions observed by 1 h. Therefore, within these sequences, the repair of oxidative lesions is much faster than that of other types of damage, such as those induced by alkylating toxins and UV irradiation, and the repair is not affected appreciably by transcriptional status.
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Affiliation(s)
- V I Grishko
- Department of Structural and Cellular Biology, University of South Alabama, Mobile 36688, USA
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