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Lan L, Nakajima S, Wei L, Sun L, Hsieh CL, Sobol RW, Bruchez M, Van Houten B, Yasui A, Levine AS. Novel method for site-specific induction of oxidative DNA damage reveals differences in recruitment of repair proteins to heterochromatin and euchromatin. Nucleic Acids Res 2013; 42:2330-45. [PMID: 24293652 PMCID: PMC3936713 DOI: 10.1093/nar/gkt1233] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Reactive oxygen species (ROS)-induced DNA damage is repaired by the base excision repair pathway. However, the effect of chromatin structure on BER protein recruitment to DNA damage sites in living cells is poorly understood. To address this problem, we developed a method to specifically produce ROS-induced DNA damage by fusing KillerRed (KR), a light-stimulated ROS-inducer, to a tet-repressor (tetR-KR) or a transcription activator (TA-KR). TetR-KR or TA-KR, bound to a TRE cassette (∼90 kb) integrated at a defined genomic locus in U2OS cells, was used to induce ROS damage in hetero- or euchromatin, respectively. We found that DNA glycosylases were efficiently recruited to DNA damage in heterochromatin, as well as in euchromatin. PARP1 was recruited to DNA damage within condensed chromatin more efficiently than in active chromatin. In contrast, recruitment of FEN1 was highly enriched at sites of DNA damage within active chromatin in a PCNA- and transcription activation-dependent manner. These results indicate that oxidative DNA damage is differentially processed within hetero or euchromatin.
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Affiliation(s)
- Li Lan
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA, University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, 5117 Centre Avenue, Pittsburgh, PA 15213, USA, School of Medicine, Tsinghua University, No.1 Tsinghua Yuan, Haidian District, Beijing 100084, People's Republic of China, Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA, Department of Human Genetics, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA 15213, USA, Department of Chemistry and Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA and Division of Dynamic Proteome, Institute of Development, Aging, and Cancer, Tohoku University, Seiryomachi 4-1, Sendai 980-8575, Japan
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52
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The complexity of DNA double strand breaks is a critical factor enhancing end-resection. DNA Repair (Amst) 2013; 12:936-46. [PMID: 24041488 DOI: 10.1016/j.dnarep.2013.08.009] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 08/09/2013] [Accepted: 08/17/2013] [Indexed: 11/22/2022]
Abstract
DNA double strand breaks (DSBs) induced by ionizing radiation (IR) are deleterious damages. Two major pathways repair DSBs in human cells, DNA non-homologous end-joining (NHEJ) and homologous recombination (HR). It has been suggested that the balance between the two repair pathways varies depending on the chromatin structure surrounding the damage site and/or the complexity of damage at the DNA break ends. Heavy ion radiation is known to induce complex-type DSBs, and the efficiency of NHEJ in repairing these DSBs was shown to be diminished. Taking advantage of the ability of high linear energy transfer (LET) radiation to produce complex DSBs effectively, we investigated how the complexity of DSB end structure influences DNA damage responses. An early step in HR is the generation of 3'-single strand DNA (SSD) via a process of DNA end resection that requires CtIP. To assess this process, we analyzed the level of phosphorylated CtIP, as well as RPA phosphorylation and focus formation, which occur on the exposed SSD. We show that complex DSBs efficiently activate DNA end resection. After heavy ion beam irradiation, resection signals appear both in the vicinity of heterochromatic areas, which is also observed after X-irradiation, and additionally in euchromatic areas. Consequently, ~85% of complex DSBs are subjected to resection in heavy ion particle tracks. Furthermore, around 20-40% of G1 cells exhibit resection signals. Taken together, our observations reveal that the complexity of DSB ends is a critical factor regulating the choice of DSB repair pathway and drastically alters the balance toward resection-mediated rejoining. As demonstrated here, studies on DNA damage responses induced by heavy ion radiation provide an important tool to shed light on mechanisms regulating DNA end resection.
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53
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Ferrando-May E, Tomas M, Blumhardt P, Stöckl M, Fuchs M, Leitenstorfer A. Highlighting the DNA damage response with ultrashort laser pulses in the near infrared and kinetic modeling. Front Genet 2013; 4:135. [PMID: 23882280 PMCID: PMC3712194 DOI: 10.3389/fgene.2013.00135] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Accepted: 06/25/2013] [Indexed: 12/13/2022] Open
Abstract
Our understanding of the mechanisms governing the response to DNA damage in higher eucaryotes crucially depends on our ability to dissect the temporal and spatial organization of the cellular machinery responsible for maintaining genomic integrity. To achieve this goal, we need experimental tools to inflict DNA lesions with high spatial precision at pre-defined locations, and to visualize the ensuing reactions with adequate temporal resolution. Near-infrared femtosecond laser pulses focused through high-aperture objective lenses of advanced scanning microscopes offer the advantage of inducing DNA damage in a 3D-confined volume of subnuclear dimensions. This high spatial resolution results from the highly non-linear nature of the excitation process. Here we review recent progress based on the increasing availability of widely tunable and user-friendly technology of ultrafast lasers in the near infrared. We present a critical evaluation of this approach for DNA microdamage as compared to the currently prevalent use of UV or VIS laser irradiation, the latter in combination with photosensitizers. Current and future applications in the field of DNA repair and DNA-damage dependent chromatin dynamics are outlined. Finally, we discuss the requirement for proper simulation and quantitative modeling. We focus in particular on approaches to measure the effect of DNA damage on the mobility of nuclear proteins and consider the pros and cons of frequently used analysis models for FRAP and photoactivation and their applicability to non-linear photoperturbation experiments.
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Affiliation(s)
- Elisa Ferrando-May
- Department of Biology, Bioimaging Center and Center for Applied Photonics, University of Konstanz Konstanz, Germany
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54
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Possible involvement of LKB1-AMPK signaling in non-homologous end joining. Oncogene 2013; 33:1640-8. [PMID: 23584481 DOI: 10.1038/onc.2013.125] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 02/01/2013] [Accepted: 02/18/2013] [Indexed: 11/09/2022]
Abstract
LKB1/STK11 is a tumor suppressor gene responsible for Peutz-Jeghers syndrome, an inherited cancer disorder associated with genome instability. The LKB1 protein functions in the regulation of cell proliferation, polarization and differentiation. Here, we suggest a role of LKB1 in non-homologous end joining (NHEJ), a major DNA double-strand break (DSB) repair pathway. LKB1 localized to DNA ends upon the generation of micro-irradiation and I-SceI endonuclease-induced DSBs. LKB1 inactivation either by RNA interference or by kinase-dead mutation compromised NHEJ-mediated DNA repair by suppressing the accumulation of BRM, a catalytic subunit of the SWI/SNF complex, at DSB sites, which promotes the recruitment of an essential NHEJ factor, KU70. AMPK2, a major substrate of LKB1 and a histone H2B kinase, was recruited to DSBs in an LKB1-dependent manner. AMPK2 depletion and a mutation of H2B that disrupted the AMPK2 phoshorylation site impaired KU70 and BRM recruitment to DSB sites. LKB1 depletion induced the formation of chromosome breaks and radials. These results suggest that LKB1-AMPK signaling controls NHEJ and contributes to genome stability.
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55
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Tadokoro T, Rybanska-Spaeder I, Kulikowicz T, Dawut L, Oshima J, Croteau DL, Bohr VA. Functional deficit associated with a missense Werner syndrome mutation. DNA Repair (Amst) 2013; 12:414-21. [PMID: 23583337 DOI: 10.1016/j.dnarep.2013.03.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2013] [Revised: 03/15/2013] [Accepted: 03/19/2013] [Indexed: 12/23/2022]
Abstract
Werner syndrome (WS) is a rare autosomal recessive disorder caused by mutations in the WRN gene. WRN helicase, a member of the RecQ helicase family, is involved in various DNA metabolic pathways including DNA replication, recombination, DNA repair and telomere maintenance. In this study, we have characterized the G574R missense mutation, which was recently identified in a WS patient. Our biochemical experiments with purified mutant recombinant WRN protein showed that the G574R mutation inhibits ATP binding, and thereby leads to significant decrease in helicase activity. Exonuclease activity of the mutant protein was not significantly affected, whereas its single strand DNA annealing activity was higher than that of wild type. Deficiency in the helicase activity of the mutant may cause defects in replication and other DNA metabolic processes, which in turn could be responsible for the Werner syndrome phenotype in the patient. In contrast to the usual appearance of WS, the G574R patient has normal stature. Thus the short stature normally associated with WS may not be due to helicase deficiency.
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Affiliation(s)
- Takashi Tadokoro
- Laboratory of Molecular Gerontology, National Institute on Aging, 251 Bayview Blvd, Suite 100, Baltimore, MD 21224, USA
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56
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Campalans A, Kortulewski T, Amouroux R, Menoni H, Vermeulen W, Radicella JP. Distinct spatiotemporal patterns and PARP dependence of XRCC1 recruitment to single-strand break and base excision repair. Nucleic Acids Res 2013; 41:3115-29. [PMID: 23355608 PMCID: PMC3597691 DOI: 10.1093/nar/gkt025] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Single-strand break repair (SSBR) and base excision repair (BER) of modified bases and abasic sites share several players. Among them is XRCC1, an essential scaffold protein with no enzymatic activity, required for the coordination of both pathways. XRCC1 is recruited to SSBR by PARP-1, responsible for the initial recognition of the break. The recruitment of XRCC1 to BER is still poorly understood. Here we show by using both local and global induction of oxidative DNA base damage that XRCC1 participation in BER complexes can be distinguished from that in SSBR by several criteria. We show first that XRCC1 recruitment to BER is independent of PARP. Second, unlike SSBR complexes that are assembled within minutes after global damage induction, XRCC1 is detected later in BER patches, with kinetics consistent with the repair of oxidized bases. Third, while XRCC1-containing foci associated with SSBR are formed both in eu- and heterochromatin domains, BER complexes are assembled in patches that are essentially excluded from heterochromatin and where the oxidized bases are detected.
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Affiliation(s)
- Anna Campalans
- CEA, Institute of Cellular and Molecular Radiobiology, F-96265 Fontenay aux Roses, France.
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57
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Recruitment of HRDC domain of WRN and BLM to the sites of DNA damage induced by mitomycin C and methyl methanesulfonate. Cell Biol Int 2013; 36:873-81. [PMID: 22657828 DOI: 10.1042/cbi20110510] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The HRDC (helicase and RNase D C-terminal) domain at the C-terminal of WRNp (Werner protein) (1150-1229 amino acids) and BLMp (Bloom protein) (1212-1292 amino acids) recognize laser microirradiation-induced DNA dsbs (double-strand breaks). However, their role in the recognition of DNA damage other than dsbs has not been reported. In this work, we show that HRDC domain of both the proteins can be recruited to the DNA damage induced by MMS (methyl methanesulfonate) and MMC (methyl mitomycin C). GFP (green fluorescent protein)-tagged HRDC domain produces distinct foci-like respective wild-types after DNA damage induced by the said agents and co-localize with γ-H2AX. However, in time course experiment, we observed that the foci of HRDC domain exist after 24 h of removal of the damaging agents, while the foci of full-length protein disappear completely. This indicates that the repair events are not completed by the presence of protein corresponding to only the HRDC domain. Consequently, cells overexpressing the HRDC domain fail to survive after DNA damage, as determined by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide] assay. Moreover, 24 h after removal of damaging agents, the extent of DNA damage is greater in cells overexpressing HRDC domain compared with corresponding wild-types, as observed by comet assay. Thus, our observations suggest that HRDC domain of both WRN and BLM can also recognize different types of DNA damages, but for the successful repair they fail to respond to subsequent repair events.
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58
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Popuri V, Huang J, Ramamoorthy M, Tadokoro T, Croteau DL, Bohr VA. RECQL5 plays co-operative and complementary roles with WRN syndrome helicase. Nucleic Acids Res 2012. [PMID: 23180761 PMCID: PMC3553943 DOI: 10.1093/nar/gks1134] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Humans have five RecQ helicases, whereas simpler organisms have only one. Little is known about whether and how these RecQ helicases co-operate and/or complement each other in response to cellular stress. Here we show that RECQL5 associates longer at laser-induced DNA double-strand breaks in the absence of Werner syndrome (WRN) protein, and that it interacts physically and functionally with WRN both in vivo and in vitro. RECQL5 co-operates with WRN on synthetic stalled replication fork-like structures and stimulates its helicase activity on DNA fork duplexes. Both RECQL5 and WRN re-localize from the nucleolus into the nucleus after replicative stress and significantly associate with each other during S-phase. Further, we show that RECQL5 is essential for cell survival in the absence of WRN. Loss of both RECQL5 and WRN severely compromises DNA replication, accumulates genomic instability and ultimately leads to cell death. Collectively, our results indicate that RECQL5 plays both co-operative and complementary roles with WRN. This is an early demonstration of a significant functional interplay and a novel synthetic lethal interaction among the human RecQ helicases.
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Affiliation(s)
- Venkateswarlu Popuri
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH, Baltimore, MD 21224, USA
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59
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Tadokoro T, Ramamoorthy M, Popuri V, May A, Tian J, Sykora P, Rybanska I, Wilson DM, Croteau DL, Bohr VA. Human RECQL5 participates in the removal of endogenous DNA damage. Mol Biol Cell 2012; 23:4273-85. [PMID: 22973052 PMCID: PMC3484104 DOI: 10.1091/mbc.e12-02-0110] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Human RECQL5 is a member of the RecQ helicase family, which maintains genome stability via participation in many DNA metabolic processes, including DNA repair. Human cells lacking RECQL5 display chromosomal instability. We find that cells depleted of RECQL5 are sensitive to oxidative stress, accumulate endogenous DNA damage, and increase the cellular poly(ADP-ribosyl)ate response. In contrast to the RECQ helicase family members WRN, BLM, and RECQL4, RECQL5 accumulates at laser-induced single-strand breaks in normal human cells. RECQL5 depletion affects the levels of PARP-1 and XRCC1, and our collective results suggest that RECQL5 modulates and/or directly participates in base excision repair of endogenous DNA damage, thereby promoting chromosome stability in normal human cells.
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Affiliation(s)
- Takashi Tadokoro
- Laboratory of Molecular Gerontology, National Institute on Aging, Baltimore, MD 21224, USA
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60
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Huda N, Abe S, Gu L, Mendonca MS, Mohanty S, Gilley D. Recruitment of TRF2 to laser-induced DNA damage sites. Free Radic Biol Med 2012; 53:1192-7. [PMID: 22841872 DOI: 10.1016/j.freeradbiomed.2012.07.024] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 07/10/2012] [Accepted: 07/17/2012] [Indexed: 12/18/2022]
Abstract
Several lines of evidence suggest that the telomere-associated protein TRF2 plays critical roles in the DNA damage response. TRF2 is rapidly and transiently phosphorylated by an ATM-dependent pathway in response to DNA damage and this DNA damage-induced phosphoryation is essential for the DNA-PK-dependent pathway of DNA double-strand break repair (DSB). However, the type of DNA damage that induces TRF2 localization to the damage sites, the requirement for DNA damage-induced phosphorylation of TRF2 for its recruitment, as well as the detailed kinetics of TRF2 accumulation at DNA damage sites have not been fully investigated. In order to address these questions, we used an ultrafast femtosecond multiphoton laser and a continuous wave 405-nm single photon laser to induce DNA damage at defined nuclear locations. Our results showed that DNA damage produced by a femtosecond multiphoton laser was sufficient for localization of TRF2 to these DNA damage sites. We also demonstrate that ectopically expressed TRF2 was recruited to DNA lesions created by a 405-nm laser. Our data suggest that ATM and DNA-PKcs kinases are not required for TRF2 localization to DNA damage sites. Furthermore, we found that phosphorylation of TRF2 at residue T188 was not essential for its recruitment to laser-induced DNA damage sites. Thus, we provide further evidence that a protein known to function in telomere maintenance, TRF2, is recruited to sites of DNA damage and plays critical roles in the DNA damage response.
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Affiliation(s)
- Nazmul Huda
- Indiana University School of Medicine, Department of Medical and Molecular Genetics, Indianapolis, IN 46202, USA
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61
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Singh DK, Ghosh AK, Croteau DL, Bohr VA. RecQ helicases in DNA double strand break repair and telomere maintenance. Mutat Res 2012; 736:15-24. [PMID: 21689668 PMCID: PMC3368089 DOI: 10.1016/j.mrfmmm.2011.06.002] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Revised: 04/19/2011] [Accepted: 06/02/2011] [Indexed: 10/24/2022]
Abstract
Organisms are constantly exposed to various environmental insults which could adversely affect the stability of their genome. To protect their genomes against the harmful effect of these environmental insults, organisms have evolved highly diverse and efficient repair mechanisms. Defective DNA repair processes can lead to various kinds of chromosomal and developmental abnormalities. RecQ helicases are a family of evolutionarily conserved, DNA unwinding proteins which are actively engaged in various DNA metabolic processes, telomere maintenance and genome stability. Bacteria and lower eukaryotes, like yeast, have only one RecQ homolog, whereas higher eukaryotes including humans possess multiple RecQ helicases. These multiple RecQ helicases have redundant and/or non-redundant functions depending on the types of DNA damage and DNA repair pathways. Humans have five different RecQ helicases and defects in three of them cause autosomal recessive diseases leading to various kinds of cancer predisposition and/or aging phenotypes. Emerging evidence also suggests that the RecQ helicases have important roles in telomere maintenance. This review mainly focuses on recent knowledge about the roles of RecQ helicases in DNA double strand break repair and telomere maintenance which are important in preserving genome integrity.
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Affiliation(s)
| | | | - Deborah L. Croteau
- Laboratory of Molecular Gerontology, Biomedical Research Center, 251 Bayview Boulevard, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Vilhelm A. Bohr
- Laboratory of Molecular Gerontology, Biomedical Research Center, 251 Bayview Boulevard, National Institute on Aging, NIH, Baltimore, MD 21224, USA
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62
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Popuri V, Ramamoorthy M, Tadokoro T, Singh DK, Karmakar P, Croteau DL, Bohr VA. Recruitment and retention dynamics of RECQL5 at DNA double strand break sites. DNA Repair (Amst) 2012; 11:624-35. [PMID: 22633600 PMCID: PMC3374033 DOI: 10.1016/j.dnarep.2012.05.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2012] [Revised: 05/01/2012] [Accepted: 05/03/2012] [Indexed: 02/04/2023]
Abstract
RECQL5 is one of the five human RecQ helicases, involved in the maintenance of genomic integrity. While much insight has been gained into the function of the Werner (WRN) and Bloom syndrome proteins (BLM), little is known about RECQL5. We have analyzed the recruitment and retention dynamics of RECQL5 at laser-induced DNA double strand breaks (DSBs) relative to other human RecQ helicases. RECQL5-depleted cells accumulate persistent 53BP1 foci followed by γ-irradiation, indicating a potential role of RECQL5 in the processing of DSBs. Real time imaging of live cells using confocal laser microscopy shows that RECQL5 is recruited early to laser-induced DSBs and remains for a shorter duration than BLM and WRN, but persist longer than RECQL4. These studies illustrate the differential involvement of RecQ helicases in the DSB repair process. Mapping of domains within RECQL5 that are necessary for recruitment to DSBs revealed that both the helicase and KIX domains are required for DNA damage recognition and stable association of RECQL5 to the DSB sites. Previous studies have shown that MRE11 is essential for the recruitment of RECQL5 to the DSB sites. Here we show that the recruitment of RECQL5 does not depend on the exonuclease activity of MRE11 or on active transcription by RNA polymerase II, one of the prominent interacting partners of RECQL5. Also, the recruitment of RECQL5 to laser-induced damage sites is independent of the presence of other DNA damage signaling and repair proteins BLM, WRN and ATM.
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Affiliation(s)
- Venkateswarlu Popuri
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH, 251 Bayview Blvd, Suite 100, Baltimore, MD 21224
| | | | - Takashi Tadokoro
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH, 251 Bayview Blvd, Suite 100, Baltimore, MD 21224
| | - Dharmendra Kumar Singh
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH, 251 Bayview Blvd, Suite 100, Baltimore, MD 21224
| | | | - Deborah L. Croteau
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH, 251 Bayview Blvd, Suite 100, Baltimore, MD 21224
| | - Vilhelm A. Bohr
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH, 251 Bayview Blvd, Suite 100, Baltimore, MD 21224
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63
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Thompson LH. Recognition, signaling, and repair of DNA double-strand breaks produced by ionizing radiation in mammalian cells: the molecular choreography. Mutat Res 2012; 751:158-246. [PMID: 22743550 DOI: 10.1016/j.mrrev.2012.06.002] [Citation(s) in RCA: 272] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Revised: 06/09/2012] [Accepted: 06/16/2012] [Indexed: 12/15/2022]
Abstract
The faithful maintenance of chromosome continuity in human cells during DNA replication and repair is critical for preventing the conversion of normal diploid cells to an oncogenic state. The evolution of higher eukaryotic cells endowed them with a large genetic investment in the molecular machinery that ensures chromosome stability. In mammalian and other vertebrate cells, the elimination of double-strand breaks with minimal nucleotide sequence change involves the spatiotemporal orchestration of a seemingly endless number of proteins ranging in their action from the nucleotide level to nucleosome organization and chromosome architecture. DNA DSBs trigger a myriad of post-translational modifications that alter catalytic activities and the specificity of protein interactions: phosphorylation, acetylation, methylation, ubiquitylation, and SUMOylation, followed by the reversal of these changes as repair is completed. "Superfluous" protein recruitment to damage sites, functional redundancy, and alternative pathways ensure that DSB repair is extremely efficient, both quantitatively and qualitatively. This review strives to integrate the information about the molecular mechanisms of DSB repair that has emerged over the last two decades with a focus on DSBs produced by the prototype agent ionizing radiation (IR). The exponential growth of molecular studies, heavily driven by RNA knockdown technology, now reveals an outline of how many key protein players in genome stability and cancer biology perform their interwoven tasks, e.g. ATM, ATR, DNA-PK, Chk1, Chk2, PARP1/2/3, 53BP1, BRCA1, BRCA2, BLM, RAD51, and the MRE11-RAD50-NBS1 complex. Thus, the nature of the intricate coordination of repair processes with cell cycle progression is becoming apparent. This review also links molecular abnormalities to cellular pathology as much a possible and provides a framework of temporal relationships.
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Affiliation(s)
- Larry H Thompson
- Biology & Biotechnology Division, L452, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551-0808, United States.
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64
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Sharma S, Phatak P, Stortchevoi A, Jasin M, Larocque JR. RECQ1 plays a distinct role in cellular response to oxidative DNA damage. DNA Repair (Amst) 2012; 11:537-49. [PMID: 22542292 DOI: 10.1016/j.dnarep.2012.04.003] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Revised: 04/02/2012] [Accepted: 04/03/2012] [Indexed: 10/28/2022]
Abstract
RECQ1 is the most abundant RecQ homolog in humans but its functions have remained mostly elusive. Biochemically, RECQ1 displays distinct substrate specificities from WRN and BLM, indicating that these RecQ helicases likely perform non-overlapping functions. Our earlier work demonstrated that RECQ1-deficient cells display spontaneous genomic instability. We have obtained key evidence suggesting a unique role of RECQ1 in repair of oxidative DNA damage. We show that similar to WRN, RECQ1 associates with PARP-1 in nuclear extracts and exhibits direct protein interaction in vitro. Deficiency in WRN or BLM helicases have been shown to result in reduced homologous recombination and hyperactivation of PARP under basal condition. However, RECQ1-deficiency did not lead to PARP activation in undamaged cells and nor did it result in reduction in homologous recombination repair. In stark contrast to what is seen in WRN-deficiency, RECQ1-deficient cells hyperactivate PARP in a specific response to H₂O₂treatment. RECQ1-deficient cells are more sensitive to oxidative DNA damage and exposure to oxidative stress results in a rapid and reversible recruitment of RECQ1 to chromatin. Chromatin localization of RECQ1 precedes WRN helicase, which has been shown to function in oxidative DNA damage repair. However, oxidative DNA damage-induced chromatin recruitment of these RecQ helicases is independent of PARP activity. As other RecQ helicases are known to interact with PARP-1, this study provides a paradigm to delineate specialized and redundant functions of RecQ homologs in repair of oxidative DNA damage.
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Affiliation(s)
- Sudha Sharma
- Department of Biochemistry and Molecular Biology, College of Medicine, Howard University, 520 W Street, NW, Washington, DC 20059, USA.
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65
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WRNIP1 accumulates at laser light irradiated sites rapidly via its ubiquitin-binding zinc finger domain and independently from its ATPase domain. Biochem Biophys Res Commun 2011; 417:1145-50. [PMID: 22209848 DOI: 10.1016/j.bbrc.2011.12.080] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 12/15/2011] [Indexed: 11/22/2022]
Abstract
WRNIP1 (Werner helicase-interacting protein 1) was originally identified as a protein that interacts with the Werner syndrome responsible gene product. WRNIP1 contains a ubiquitin-binding zinc-finger (UBZ) domain in the N-terminal region and two leucine zipper motifs in the C-terminal region. In addition, it possesses an ATPase domain in the middle of the molecule and the lysine residues serving as ubiquitin acceptors in the entire of the molecule. Here, we report that WRNIP1 accumulates in laser light irradiated sites very rapidly via its ubiquitin-binding zinc finger domain, which is known to bind polyubiquitin and to be involved in ubiquitination of WRNIP1 itself. The accumulation of WRNIP1 in laser light irradiated sites also required the C-terminal region containing two leucine zippers, which is reportedly involved in the oligomerization of WRNIP1. Mutated WRNIP1 with a deleted ATPase domain or with mutations in lysine residues, which serve as ubiquitin acceptors, accumulated in laser light irradiated sites, suggesting that the ATPase domain of WRNIP1 and ubiquitination of WRNIP1 are dispensable for the accumulation.
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66
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Zlatanou A, Despras E, Braz-Petta T, Boubakour-Azzouz I, Pouvelle C, Stewart GS, Nakajima S, Yasui A, Ishchenko AA, Kannouche PL. The hMsh2-hMsh6 complex acts in concert with monoubiquitinated PCNA and Pol η in response to oxidative DNA damage in human cells. Mol Cell 2011; 43:649-62. [PMID: 21855803 DOI: 10.1016/j.molcel.2011.06.023] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Revised: 04/01/2011] [Accepted: 06/08/2011] [Indexed: 11/29/2022]
Abstract
Posttranslational modification of PCNA by ubiquitin plays an important role in coordinating the processes of DNA damage tolerance during DNA replication. The monoubiquitination of PCNA was shown to facilitate the switch between the replicative DNA polymerase with the low-fidelity polymerase eta (η) to bypass UV-induced DNA lesions during replication. Here, we show that in response to oxidative stress, PCNA becomes transiently monoubiquitinated in an S phase- and USP1-independent manner. Moreover, Polη interacts with mUb-PCNA at sites of oxidative DNA damage via its PCNA-binding and ubiquitin-binding motifs. Strikingly, while functional base excision repair is not required for this modification of PCNA or Polη recruitment to chromatin, the presence of hMsh2-hMsh6 is indispensable. Our findings highlight an alternative pathway in response to oxidative DNA damage that may coordinate the removal of oxidatively induced clustered DNA lesions and could explain the high levels of oxidized DNA lesions in MSH2-deficient cells.
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Affiliation(s)
- Anastasia Zlatanou
- Group TLS Polymerases and Cancer, Université Paris-Sud, CNRS-UMR8200, Institut Gustave Roussy, 94800 Villejuif, France
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67
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The RAD9-RAD1-HUS1 (9.1.1) complex interacts with WRN and is crucial to regulate its response to replication fork stalling. Oncogene 2011; 31:2809-23. [PMID: 22002307 PMCID: PMC3272477 DOI: 10.1038/onc.2011.468] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The WRN protein belongs to the RecQ family of DNA helicases and is implicated in replication fork restart, but how its function is regulated remains unknown. We show that WRN interacts with the 9.1.1 complex, one of the central factors of the replication checkpoint. This interaction is mediated by the binding of the RAD1 subunit to the N-terminal region of WRN and is instrumental for WRN relocalisation in nuclear foci and its phosphorylation in response to replication arrest. We also find that ATR-dependent WRN phosphorylation depends on TopBP1, which is recruited by the 9.1.1 complex in response to replication arrest. Finally, we provide evidence for a cooperation between WRN and 9.1.1 complex in preventing accumulation of DNA breakage and maintaining genome integrity at naturally-occurring replication fork stalling sites. Taken together, our data unveil a novel functional interplay between WRN helicase and the replication checkpoint, contributing to shed light into the molecular mechanism underlying the response to replication fork arrest.
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68
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Liu J, Song Y, Qian J, Liu B, Dong Y, Tian B, Sun Z. Promyelocytic leukemia protein interacts with werner syndrome helicase and regulates double-strand break repair in γ-irradiation-induced DNA damage responses. BIOCHEMISTRY (MOSCOW) 2011; 76:550-4. [PMID: 21639834 DOI: 10.1134/s000629791105004x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We show here that γ-irradiation leads to the translocation of endogenous Werner syndrome helicase (WRN) from nucleoli to nucleoplasmic DNA double strand breaks (DSBs), and WRN plays a role in damage repair. The relocation of WRN after irradiation was perturbed by promyelocytic leukemia protein (PML) knockdown and enhanced by PML IV overexpression. PML IV physically interacted with WRN after irradiation. Amino acids (a.a.) 394 to 433 of PML were necessary for this interaction and the nucleoplasmic translocation of WRN and were involved in DSB repair and cellular sensitivity to γ-irradiation. Taken together, our results provide molecular support for a model in which PML IV physically interacts with and regulates the translocation of WRN for DNA damage repair through its 394-433 a.a. domain.
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Affiliation(s)
- Jilai Liu
- Department of Biochemistry and Molecular Biology, Beijing Institute of Radiation Medicine, P. R. China
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69
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Trego KS, Chernikova SB, Davalos AR, Perry JJP, Finger LD, Ng C, Tsai MS, Yannone SM, Tainer JA, Campisi J, Cooper PK. The DNA repair endonuclease XPG interacts directly and functionally with the WRN helicase defective in Werner syndrome. Cell Cycle 2011; 10:1998-2007. [PMID: 21558802 DOI: 10.4161/cc.10.12.15878] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
XPG is a structure-specific endonuclease required for nucleotide excision repair (NER). XPG incision defects result in the cancer-prone syndrome xeroderma pigmentosum, whereas truncating mutations of XPG cause the severe postnatal progeroid developmental disorder Cockayne syndrome. We show that XPG interacts directly with WRN protein, which is defective in the premature aging disorder Werner syndrome, and that the two proteins undergo similar subnuclear redistribution in S phase and colocalize in nuclear foci. The co-localization was observed in mid- to late S phase, when WRN moves from nucleoli to nuclear foci that have been shown to contain both protein markers of stalled replication forks and telomeric proteins. We mapped the interaction between XPG and WRN to the C-terminal domains of each, and show that interaction with the C-terminal domain of XPG strongly stimulates WRN helicase activity. WRN also possesses a competing DNA single-strand annealing activity that, combined with unwinding, has been shown to coordinate regression of model replication forks to form Holliday junction/chicken foot intermediate structures. We tested whether XPG stimulated WRN annealing activity, and found that XPG itself has intrinsic strand annealing activity that requires the unstructured R- and C-terminal domains but not the conserved catalytic core or endonuclease activity. Annealing by XPG is cooperative, rather than additive, with WRN annealing. Taken together, our results suggest a novel function for XPG in S phase that is, at least in part, performed coordinately with WRN, and which may contribute to the severity of the phenotypes that occur upon loss of XPG.
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Affiliation(s)
- Kelly S Trego
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
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70
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Khodyreva SN, Lavrik OI. Affinity modification in a proteomic study of DNA repair ensembles. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2011; 37:91-107. [DOI: 10.1134/s1068162011010109] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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71
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Lan L, Ui A, Nakajima S, Hatakeyama K, Hoshi M, Watanabe R, Janicki SM, Ogiwara H, Kohno T, Kanno SI, Yasui A. The ACF1 complex is required for DNA double-strand break repair in human cells. Mol Cell 2011; 40:976-87. [PMID: 21172662 DOI: 10.1016/j.molcel.2010.12.003] [Citation(s) in RCA: 161] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Revised: 07/11/2010] [Accepted: 10/18/2010] [Indexed: 01/23/2023]
Abstract
DNA double-strand breaks (DSBs) are repaired via nonhomologous end-joining (NHEJ) or homologous recombination (HR), but cellular repair processes remain elusive. We show here that the ATP-dependent chromatin-remodeling factors, ACF1 and SNF2H, accumulate rapidly at DSBs and are required for DSB repair in human cells. If the expression of ACF1 or SNF2H is suppressed, cells become extremely sensitive to X-rays and chemical treatments producing DSBs, and DSBs remain unrepaired. ACF1 interacts directly with KU70 and is required for the accumulation of KU proteins at DSBs. The KU70/80 complex becomes physically more associated with the chromatin-remodeling factors of the CHRAC complex, which includes ACF1, SNF2H, CHRAC15, and CHRAC17, after treatments producing DSBs. Furthermore, the frequency of NHEJ as well as HR induced by DSBs in chromosomal DNA is significantly decreased in cells depleted of either of these factors. Thus, ACF1 and its complexes play important roles in DSBs repair.
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Affiliation(s)
- Li Lan
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Seiryomachi 4-1, Sendai 980-8575, Japan
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72
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Ogiwara H, Ui A, Otsuka A, Satoh H, Yokomi I, Nakajima S, Yasui A, Yokota J, Kohno T. Histone acetylation by CBP and p300 at double-strand break sites facilitates SWI/SNF chromatin remodeling and the recruitment of non-homologous end joining factors. Oncogene 2011; 30:2135-46. [PMID: 21217779 DOI: 10.1038/onc.2010.592] [Citation(s) in RCA: 223] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Non-homologous end joining (NHEJ) is a major repair pathway for DNA double-strand breaks (DSBs) generated by ionizing radiation (IR) and anti-cancer drugs. Therefore, inhibiting the activity of proteins involved in this pathway is a promising way of sensitizing cancer cells to both radiotherapy and chemotherapy. In this study, we developed an assay for evaluating NHEJ activity against DSBs in chromosomal DNA in human cells to identify the chromatin modification/remodeling proteins involved in NHEJ. We showed that ablating the activity of the homologous histone acetyltransferases, CBP and p300, using inhibitors or small interfering RNAs-suppressed NHEJ. Ablation of CBP or p300 impaired IR-induced DSB repair and sensitized lung cancer cells to IR and the anti-cancer drug, etoposide, which induces DSBs that are repaired by NHEJ. The CBP/p300 proteins were recruited to sites of DSBs and their ablation suppressed acetylation of lysine 18 within histone H3, and lysines 5, 8, 12, and 16 within histone H4, at the DSB sites. This then suppressed the recruitment of KU70 and KU80, both key proteins for NHEJ, to the DSB sites. Ablation of CBP/p300 also impaired the recruitment of BRM, a catalytic subunit of the SWI/SNF complex involved in chromatin remodeling at DSB sites. These results indicate that CBP and p300 function as histone H3 and H4 acetyltransferases at DSB sites in NHEJ and facilitate chromatin relaxation. Therefore, inhibition CBP and p300 activity may sensitize cancer cells to radiotherapy and chemotherapy.
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Affiliation(s)
- H Ogiwara
- Division of Genome Biology, National Cancer Center Research Institute, Chuo-ku, Tokyo, Japan
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73
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Yuan J, Adamski R, Chen J. Focus on histone variant H2AX: to be or not to be. FEBS Lett 2010; 584:3717-24. [PMID: 20493860 PMCID: PMC3695482 DOI: 10.1016/j.febslet.2010.05.021] [Citation(s) in RCA: 234] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2010] [Revised: 05/04/2010] [Accepted: 05/11/2010] [Indexed: 12/16/2022]
Abstract
Phosphorylation of histone variant H2AX at serine 139, named gammaH2AX, has been widely used as a sensitive marker for DNA double-strand breaks (DSBs). gammaH2AX is required for the accumulation of many DNA damage response (DDR) proteins at DSBs. Thus it is believed to be the principal signaling protein involved in DDR and to play an important role in DNA repair. However, only mild defects in DNA damage signaling and DNA repair were observed in H2AX-deficient cells and animals. Such findings prompted us and others to explore H2AX-independent mechanisms in DNA damage response. Here, we will review recent advances in our understanding of H2AX-dependent and independent DNA damage signaling and repair pathways in mammalian cells.
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Affiliation(s)
- Jingsong Yuan
- Department of Experimental Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Rachel Adamski
- Department of Experimental Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Junjie Chen
- Department of Experimental Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
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74
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Singh DK, Karmakar P, Aamann M, Schurman SH, May A, Croteau DL, Burks L, Plon SE, Bohr VA. The involvement of human RECQL4 in DNA double-strand break repair. Aging Cell 2010; 9:358-71. [PMID: 20222902 PMCID: PMC4624395 DOI: 10.1111/j.1474-9726.2010.00562.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Rothmund-Thomson syndrome (RTS) is an autosomal recessive hereditary disorder associated with mutation in RECQL4 gene, a member of the human RecQ helicases. The disease is characterized by genomic instability, skeletal abnormalities and predisposition to malignant tumors, especially osteosarcomas. The precise role of RECQL4 in cellular pathways is largely unknown; however, recent evidence suggests its involvement in multiple DNA metabolic pathways. This study investigates the roles of RECQL4 in DNA double-strand break (DSB) repair. The results show that RECQL4-deficient fibroblasts are moderately sensitive to gamma-irradiation and accumulate more gammaH2AX and 53BP1 foci than control fibroblasts. This is suggestive of defects in efficient repair of DSB's in the RECQL4-deficient fibroblasts. Real time imaging of live cells using laser confocal microscopy shows that RECQL4 is recruited early to laser-induced DSBs and remains for a shorter duration than WRN and BLM, indicating its distinct role in repair of DSBs. Endogenous RECQL4 also colocalizes with gammaH2AX at the site of DSBs. The RECQL4 domain responsible for its DNA damage localization has been mapped to the unique N-terminus domain between amino acids 363-492, which shares no homology to recruitment domains of WRN and BLM to the DSBs. Further, the recruitment of RECQL4 to laser-induced DNA damage is independent of functional WRN, BLM or ATM proteins. These results suggest distinct cellular dynamics for RECQL4 protein at the site of laser-induced DSB and that it might play important roles in efficient repair of DSB's.
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Affiliation(s)
- Dharmendra Kumar Singh
- Laboratory of Molecular Gerontology, Biomedical Research Center, 251 Bayview Boulevard, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Parimal Karmakar
- Department of Life Sciences and Biotechnology, Jadavpur University, Kolkata, West Bengal-700 032, India
| | - Maria Aamann
- Laboratory of Molecular Gerontology, Biomedical Research Center, 251 Bayview Boulevard, National Institute on Aging, NIH, Baltimore, MD 21224, USA
- Danish Center for Molecular Gerontology, MBI, University of Aarhus, Denmark
| | - Shepherd H. Schurman
- Laboratory of Molecular Gerontology, Biomedical Research Center, 251 Bayview Boulevard, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Alfred May
- Laboratory of Molecular Gerontology, Biomedical Research Center, 251 Bayview Boulevard, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Deborah L. Croteau
- Laboratory of Molecular Gerontology, Biomedical Research Center, 251 Bayview Boulevard, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Lynnette Burks
- Baylor College of Medicine, Departments of Molecular and Human Genetics and Pediatrics, Houston, USA
| | - Sharon E. Plon
- Baylor College of Medicine, Departments of Molecular and Human Genetics and Pediatrics, Houston, USA
| | - Vilhelm A. Bohr
- Laboratory of Molecular Gerontology, Biomedical Research Center, 251 Bayview Boulevard, National Institute on Aging, NIH, Baltimore, MD 21224, USA
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75
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Rossi ML, Ghosh AK, Bohr VA. Roles of Werner syndrome protein in protection of genome integrity. DNA Repair (Amst) 2010; 9:331-44. [PMID: 20075015 DOI: 10.1016/j.dnarep.2009.12.011] [Citation(s) in RCA: 157] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Werner syndrome protein (WRN) is one of a family of five human RecQ helicases implicated in the maintenance of genome stability. The conserved RecQ family also includes RecQ1, Bloom syndrome protein (BLM), RecQ4, and RecQ5 in humans, as well as Sgs1 in Saccharomyces cerevisiae, Rqh1 in Schizosaccharomyces pombe, and homologs in Caenorhabditis elegans, Xenopus laevis, and Drosophila melanogaster. Defects in three of the RecQ helicases, RecQ4, BLM, and WRN, cause human pathologies linked with cancer predisposition and premature aging. Mutations in the WRN gene are the causative factor of Werner syndrome (WS). WRN is one of the best characterized of the RecQ helicases and is known to have roles in DNA replication and repair, transcription, and telomere maintenance. Studies both in vitro and in vivo indicate that the roles of WRN in a variety of DNA processes are mediated by post-translational modifications, as well as several important protein-protein interactions. In this work, we will summarize some of the early studies on the cellular roles of WRN and highlight the recent findings that shed some light on the link between the protein with its cellular functions and the disease pathology.
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Affiliation(s)
- Marie L Rossi
- Laboratory of Molecular Gerontology, National Institute on Aging, Baltimore, MD 21224, USA
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76
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The Caenorhabditis elegans Werner syndrome protein functions upstream of ATR and ATM in response to DNA replication inhibition and double-strand DNA breaks. PLoS Genet 2010; 6:e1000801. [PMID: 20062519 PMCID: PMC2791846 DOI: 10.1371/journal.pgen.1000801] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Accepted: 12/07/2009] [Indexed: 11/19/2022] Open
Abstract
WRN-1 is the Caenorhabditis elegans homolog of the human Werner syndrome protein, a RecQ helicase, mutations of which are associated with premature aging and increased genome instability. Relatively little is known as to how WRN-1 functions in DNA repair and DNA damage signaling. Here, we take advantage of the genetic and cytological approaches in C. elegans to dissect the epistatic relationship of WRN-1 in various DNA damage checkpoint pathways. We found that WRN-1 is required for CHK1 phosphorylation induced by DNA replication inhibition, but not by UV radiation. Furthermore, WRN-1 influences the RPA-1 focus formation, suggesting that WRN-1 functions in the same step or upstream of RPA-1 in the DNA replication checkpoint pathway. In response to ionizing radiation, RPA-1 focus formation and nuclear localization of ATM depend on WRN-1 and MRE-11. We conclude that C. elegans WRN-1 participates in the initial stages of checkpoint activation induced by DNA replication inhibition and ionizing radiation. These functions of WRN-1 in upstream DNA damage signaling are likely to be conserved, but might be cryptic in human systems due to functional redundancy. Werner syndrome is a premature aging syndrome associated with genomic instability. The protein linked to Werner syndrome, WRN, has both helicase and exonuclease activities and is thought to be involved in DNA repair, including the resolution of replication fork arrest as well as in telomere maintenance. However, no definite and detailed role of the protein has been elucidated in vivo. We take advantage of the Caenorhabditis elegans germ cell system to explore DNA damage response defects associated with WRN, and we focus particularly on the role of wrn in the cell cycle checkpoint in response to DNA replication blockage and ionizing radiation (IR). We show that WRN functions together with RPA upstream of C. elegans ATR in the intra S-phase checkpoint pathway, and upstream of C. elegans ATM and RPA in the cell cycle arrest pathway triggered by IR–induced double-strand DNA breaks. These functions of WRN in upstream DNA damage signaling are likely to be conserved, but not obvious in human systems due to functional redundancy.
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77
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DNA repair: easy to visualize, difficult to elucidate. Trends Cell Biol 2009; 19:617-29. [DOI: 10.1016/j.tcb.2009.08.010] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2009] [Revised: 08/24/2009] [Accepted: 08/26/2009] [Indexed: 11/19/2022]
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78
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Zecevic A, Menard H, Gurel V, Hagan E, DeCaro R, Zhitkovich A. WRN helicase promotes repair of DNA double-strand breaks caused by aberrant mismatch repair of chromium-DNA adducts. Cell Cycle 2009; 8:2769-78. [PMID: 19652551 PMCID: PMC3226781 DOI: 10.4161/cc.8.17.9410] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Recent studies in yeast have found that processing of DNA double-strand breaks (DSB) for recombination repair involves Sgs1 helicase. Human cells have five Sgs1 homologues with unknown selectivity and significance for repair of different DSB types. Here we examined the importance of WRN helicase in repair of G(2)-specific DSB caused by abnormal mismatch repair (MMR) of ternary Cr-DNA adducts. We found that Cr(VI) induced a rapid dispersal of WRN from the nucleolus resulting in its prolonged retention in the nucleoplasm. The loss of MSH2 or MLH1 MMR proteins abolished the long-term but not the initial WRN relocalization. WRN-deficient fibroblasts were hypersensitive to Cr(VI)-induced clonogenic death and contained high levels of persistent DSB detected by gamma-H2AX/53BP1 foci and pulsed-field gel electrophoresis. WRN was involved in recombination repair of Cr-induced DNA damage, as evidenced by WRN-RAD51 colocalization and defective formation of RAD51 foci in the absence of WRN. The accumulation of unrepaired DSB in WRN-depleted cells was rescued by the inactivation of MMR, indicating that MMR-generated DSB were a key substrate for WRN action in Cr(VI)-treated cells. Competition for the limited amounts of WRN in primary cells between G(2) processes of telomere rebuilding and recombinational repair is expected to increase persistence of Cr-induced DSB and may cause telomeric abnormalities in tissues of chronically chromate-exposed workers. Our work provides the first demonstration of the major importance of WRN in repair of a specific class of DSB in human cells.
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Affiliation(s)
- Alma Zecevic
- Brown University, Department of Pathology and Laboratory Medicine, Providence RI 02912
- University of Texas, MD Anderson Cancer Center, Houston TX 77030
| | - Haley Menard
- Brown University, Department of Pathology and Laboratory Medicine, Providence RI 02912
| | - Volkan Gurel
- Brown University, Department of Pathology and Laboratory Medicine, Providence RI 02912
| | - Elizabeth Hagan
- Brown University, Department of Pathology and Laboratory Medicine, Providence RI 02912
| | - Rosamaria DeCaro
- Brown University, Department of Pathology and Laboratory Medicine, Providence RI 02912
| | - Anatoly Zhitkovich
- Brown University, Department of Pathology and Laboratory Medicine, Providence RI 02912
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79
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Kong X, Mohanty SK, Stephens J, Heale JT, Gomez-Godinez V, Shi LZ, Kim JS, Yokomori K, Berns MW. Comparative analysis of different laser systems to study cellular responses to DNA damage in mammalian cells. Nucleic Acids Res 2009; 37:e68. [PMID: 19357094 PMCID: PMC2685111 DOI: 10.1093/nar/gkp221] [Citation(s) in RCA: 162] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Proper recognition and repair of DNA damage is critical for the cell to protect its genomic integrity. Laser microirradiation ranging in wavelength from ultraviolet A (UVA) to near-infrared (NIR) can be used to induce damage in a defined region in the cell nucleus, representing an innovative technology to effectively analyze the in vivo DNA double-strand break (DSB) damage recognition process in mammalian cells. However, the damage-inducing characteristics of the different laser systems have not been fully investigated. Here we compare the nanosecond nitrogen 337 nm UVA laser with and without bromodeoxyuridine (BrdU), the nanosecond and picosecond 532 nm green second-harmonic Nd:YAG, and the femtosecond NIR 800 nm Ti:sapphire laser with regard to the type(s) of damage and corresponding cellular responses. Crosslinking damage (without significant nucleotide excision repair factor recruitment) and single-strand breaks (with corresponding repair factor recruitment) were common among all three wavelengths. Interestingly, UVA without BrdU uniquely produced base damage and aberrant DSB responses. Furthermore, the total energy required for the threshold H2AX phosphorylation induction was found to vary between the individual laser systems. The results indicate the involvement of different damage mechanisms dictated by wavelength and pulse duration. The advantages and disadvantages of each system are discussed.
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Affiliation(s)
- Xiangduo Kong
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, CA 92697-1700, USA
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80
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Grigaravicius P, Greulich KO, Monajembashi S. Laser microbeams and optical tweezers in ageing research. Chemphyschem 2009; 10:79-85. [PMID: 19090523 DOI: 10.1002/cphc.200800725] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We show how a technique developed within the framework of physics and physical chemistry-in a true interdisciplinary approach-can answer questions in life sciences that are not solvable by using other techniques. Herein, we focus on blood-pressure regulation and DNA repair in ageing studies. Laser microbeams and optical tweezers are now established tools in many fields of science, particularly in the life sciences. A short glimpse is given on the wide field of non-age-research applications in life sciences. Then, optical tweezers are used to show that exerting a vertical pressure on cells representing the inner lining of blood vessels results in bursts of NO liberation concomitant with large changes in cell morphology. Repeated treatment of such human umbilical vein endothelial cells (HUVEC) results in stiffening, a hallmark of manifest high blood pressure, a disease primarily of the elderly. As a second application in ageing research, a laser microbeam is used to induce, with high spatial and temporal resolution, DNA damages in the nuclei of U2OS human osteosarcoma cells. A pairwise study of the recruitment kinetics of different DNA repair proteins reveals that DNA repair starts with non-homologous end joining (NHEJ), a repair pathway, and may only after several minutes switch to the error-free homologous recombination repair (HRR) pathway. Since DNA damages-when incorrectly repaired-accumulate with time, laser microbeams are becoming well-used tools in ageing research.
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81
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Yano KI, Morotomi-Yano K, Adachi N, Akiyama H. Molecular mechanism of protein assembly on DNA double-strand breaks in the non-homologous end-joining pathway. JOURNAL OF RADIATION RESEARCH 2009; 50:97-108. [PMID: 19346677 DOI: 10.1269/jrr.08119] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Non-homologous end-joining (NHEJ) is the major repair pathway for DNA double-strand breaks (DSBs) in mammalian species. Upon DSB induction, a living cell quickly activates the NHEJ pathway comprising of multiple molecular events. However, it has been difficult to analyze the initial phase of DSB responses in living cells, primarily due to technical limitations. Recent advances in real-time imaging and site-directed DSB induction using laser microbeam allow us to monitor the spatiotemporal dynamics of NHEJ factors in the immediate-early phase after DSB induction. These new approaches, together with the use of cell lines deficient in each essential NHEJ factor, provide novel mechanistic insights into DSB recognition and protein assembly on DSBs in the NHEJ pathway. In this review, we provide an overview of recent progresses in the imaging analyses of the NHEJ core factors. These studies strongly suggest that the NHEJ core factors are pre-assembled into a large complex on DSBs prior to the progression of the biochemical reactions in the NHEJ pathway. Instead of the traditional step-by-step assembly model from the static view of NHEJ, a novel model for dynamic protein assembly in the NHEJ pathway is proposed. This new model provides important mechanistic insights into the protein assembly at DSBs and the regulation of DSB repair.
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82
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Rapid recruitment of BRCA1 to DNA double-strand breaks is dependent on its association with Ku80. Mol Cell Biol 2008; 28:7380-93. [PMID: 18936166 DOI: 10.1128/mcb.01075-08] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
BRCA1 is the first susceptibility gene to be linked to breast and ovarian cancers. Although mounting evidence has indicated that BRCA1 participates in DNA double-strand break (DSB) repair pathways, its precise mechanism is still unclear. Here, we analyzed the in situ response of BRCA1 at DSBs produced by laser microirradiation. The amino (N)- and carboxyl (C)-terminal fragments of BRCA1 accumulated independently at DSBs with distinct kinetics. The N-terminal BRCA1 fragment accumulated immediately after laser irradiation at DSBs and dissociated rapidly. In contrast, the C-terminal fragment of BRCA1 accumulated more slowly at DSBs but remained at the sites. Interestingly, rapid accumulation of the BRCA1 N terminus, but not the C terminus, at DSBs depended on Ku80, which functions in the nonhomologous end-joining (NHEJ) pathway, independently of BARD1, which binds to the N terminus of BRCA1. Two small regions in the N terminus of BRCA1 independently accumulated at DSBs and interacted with Ku80. Missense mutations found within the N terminus of BRCA1 in cancers significantly changed the kinetics of its accumulation at DSBs. A P142H mutant failed to associate with Ku80 and restore resistance to irradiation in BRCA1-deficient cells. These might provide a molecular basis of the involvement of BRCA1 in the NHEJ pathway of the DSB repair process.
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83
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Petta TB, Nakajima S, Zlatanou A, Despras E, Couve-Privat S, Ishchenko A, Sarasin A, Yasui A, Kannouche P. Human DNA polymerase iota protects cells against oxidative stress. EMBO J 2008; 27:2883-95. [PMID: 18923427 DOI: 10.1038/emboj.2008.210] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2008] [Accepted: 09/15/2008] [Indexed: 01/10/2023] Open
Abstract
Human DNA polymerase iota (poliota) is a unique member of the Y-family of specialised polymerases that displays a 5'deoxyribose phosphate (dRP) lyase activity. Although poliota is well conserved in higher eukaryotes, its role in mammalian cells remains unclear. To investigate the biological importance of poliota in human cells, we generated fibroblasts stably downregulating poliota (MRC5-pol iota(KD)) and examined their response to several types of DNA-damaging agents. We show that cell lines downregulating poliota exhibit hypersensitivity to DNA damage induced by hydrogen peroxide (H(2)O(2)) or menadione but not to ethylmethane sulphonate (EMS), UVC or UVA. Interestingly, extracts from cells downregulating poliota show reduced base excision repair (BER) activity. In addition, poliota binds to chromatin after treatment of cells with H(2)O(2) and interacts with the BER factor XRCC1. Finally, green fluorescent protein-tagged poliota accumulates at the sites of oxidative DNA damage in living cells. This recruitment is partially mediated by its dRP lyase domain and ubiquitin-binding domains. These data reveal a novel role of human poliota in protecting cells from oxidative damage.
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Affiliation(s)
- Tirzah Braz Petta
- Centre National de la Recherche Scientifique FRE2939, Unit of genetic stability and oncogenesis, Institut Gustave Roussy, Université Paris-Sud, Villejuif, France
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84
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Hong Z, Jiang J, Hashiguchi K, Hoshi M, Lan L, Yasui A. Recruitment of mismatch repair proteins to the site of DNA damage in human cells. J Cell Sci 2008; 121:3146-54. [DOI: 10.1242/jcs.026393] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Mismatch repair (MMR) proteins contribute to genome stability by excising DNA mismatches introduced by DNA polymerase. Although MMR proteins are also known to influence cellular responses to DNA damage, how MMR proteins respond to DNA damage within the cell remains unknown. Here, we show that MMR proteins are recruited immediately to the sites of various types of DNA damage in human cells. MMR proteins are recruited to single-strand breaks in a poly(ADP-ribose)-dependent manner as well as to double-strand breaks. Using mutant cells, RNA interference and expression of fluorescence-tagged proteins, we show that accumulation of MutSβ at the DNA damage site is solely dependent on the PCNA-binding domain of MSH3, and that of MutSα depends on a region near the PCNA-binding domain of MSH6. MSH2 is recruited to the DNA damage site through interactions with either MSH3 or MSH6, and is required for recruitment of MLH1 to the damage site. We found, furthermore, that MutSβ is also recruited to UV-irradiated sites in nucleotide-excision-repair- and PCNA-dependent manners. Thus, MMR and its proteins function not only in replication but also in DNA repair.
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Affiliation(s)
- Zehui Hong
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Seiryomachi 4-1, Aobaku, Sendai 980-8575, Japan
| | - Jie Jiang
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Seiryomachi 4-1, Aobaku, Sendai 980-8575, Japan
| | - Kazunari Hashiguchi
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Seiryomachi 4-1, Aobaku, Sendai 980-8575, Japan
| | - Mikiko Hoshi
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Seiryomachi 4-1, Aobaku, Sendai 980-8575, Japan
| | - Li Lan
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Seiryomachi 4-1, Aobaku, Sendai 980-8575, Japan
| | - Akira Yasui
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Seiryomachi 4-1, Aobaku, Sendai 980-8575, Japan
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85
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Cheng WH, Muftic D, Muftuoglu M, Dawut L, Morris C, Helleday T, Shiloh Y, Bohr VA. WRN is required for ATM activation and the S-phase checkpoint in response to interstrand cross-link-induced DNA double-strand breaks. Mol Biol Cell 2008; 19:3923-33. [PMID: 18596239 PMCID: PMC2526706 DOI: 10.1091/mbc.e07-07-0698] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2007] [Revised: 04/25/2008] [Accepted: 06/20/2008] [Indexed: 12/18/2022] Open
Abstract
Werner syndrome (WS) is a human genetic disorder characterized by extensive clinical features of premature aging. Ataxia-telengiectasia (A-T) is a multisystem human genomic instability syndrome that includes premature aging in some of the patients. WRN and ATM, the proteins defective in WS and A-T, respectively, play significant roles in the maintenance of genomic stability and are involved in several DNA metabolic pathways. A role for WRN in DNA repair has been proposed; however, this study provides evidence that WRN is also involved in ATM pathway activation and in a S-phase checkpoint in cells exposed to DNA interstrand cross-link-induced double-strand breaks. Depletion of WRN in such cells by RNA interference results in an intra-S checkpoint defect, and interferes with activation of ATM as well as downstream phosphorylation of ATM target proteins. Treatment of cells under replication stress with the ATM kinase inhibitor KU 55933 results in a S-phase checkpoint defect similar to that observed in WRN shRNA cells. Moreover, gamma H2AX levels are higher in WRN shRNA cells than in control cells 6 and 16 h after exposure to psoralen DNA cross-links. These results suggest that WRN and ATM participate in a replication checkpoint response, in which WRN facilitates ATM activation in cells with psoralen DNA cross-link-induced collapsed replication forks.
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Affiliation(s)
- Wen-Hsing Cheng
- *Laboratory of Molecular Gerontology and
- Department of Nutrition and Food Science, University of Maryland, College Park, MD 20742
| | - Diana Muftic
- *Laboratory of Molecular Gerontology and
- Department of Genetics, Microbiology, and Toxicology, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden; and
| | | | - Lale Dawut
- *Laboratory of Molecular Gerontology and
| | - Christa Morris
- Flow Cytometry Unit, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224
| | - Thomas Helleday
- Department of Genetics, Microbiology, and Toxicology, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden; and
| | - Yosef Shiloh
- David and Inez Myers Laboratory for Genetic Research, Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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86
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Riches LC, Lynch AM, Gooderham NJ. Early events in the mammalian response to DNA double-strand breaks. Mutagenesis 2008; 23:331-9. [PMID: 18644834 DOI: 10.1093/mutage/gen039] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
Physical and chemical agents that induce DNA double-strand breaks (DSBs) are among the most potent mutagens. The mammalian cell response to DSB comprises a highly co-ordinated, yet complex network of proteins that have been categorized as sensors, signal transducers, mediators and effectors of damage and repair. While this provides an accessible classification system, review of the literature indicates that many proteins satisfy the criteria of more than one category, pointing towards a series of highly co-operative pathways with overlapping function. In summary, the MRE11-NBS1-RAD50 complex is necessary for achieving optimal activation of ataxia-telangiectasia-mutated (ATM) kinase, which catalyses a phosphorylation-mediated signal transduction cascade. Among the subset of proteins phosphorylated by ATM are histone H2AX (H2AX), mediator of damage checkpoint protein 1, nibrin (NBS1), P53-binding protein 1 and breast cancer protein 1, all of which subsequently redistribute into DSB-containing sub-nuclear compartments. Post-translational modification of DSB responding proteins achieves a rapid and reversible change in protein behaviour and mediates damage-specific interactions, hence imparting a high degree of vigilance to the cell. This review highlights events fundamental in maintaining genetic integrity with emphasis on early stages of the DSB response.
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Affiliation(s)
- Lucy C Riches
- Department of Biomolecular Medicine, Faculty of Medicine, Imperial College London, Sir Alexander Fleming Building, London SW7 2AZ, UK
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87
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Kusumoto R, Dawut L, Marchetti C, Wan Lee J, Vindigni A, Ramsden D, Bohr VA. Werner protein cooperates with the XRCC4-DNA ligase IV complex in end-processing. Biochemistry 2008; 47:7548-56. [PMID: 18558713 PMCID: PMC2572716 DOI: 10.1021/bi702325t] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Werner syndrome is a rare human disease characterized by the premature onset of aging-associated pathologies, cancer predisposition, and genomic instability. The Werner protein (WRN), which is defective in Werner syndrome ( WS) patients, belongs to the RecQ family helicases and interacts with several DNA metabolic proteins, including DNA repair factors and telomere associated proteins. Nonhomologous end-joining (NHEJ) is an important pathway in the repair of DNA double strand breaks (DSBs), and the DNA-PK complex, composed of the heterodimer Ku 70/86 and the DNA-PK catalytic subunit (DNA-PKcs), together with the XRCC4-DNA ligase IV complex (X4L4), are major factors. One of the most prominent protein interactions of WRN is with Ku 70/86, and it is possible that WRN is involved in NHEJ via its associations with Ku 70/86 and DNA-PKcs. This study demonstrates that WRN physically interacts with the major NHEJ factor, X4L4, which stimulates WRN exonuclease but not its helicase activity. The human RecQ helicase, BLM, which possesses only helicase activity, does not bind to X4L4, and its helicase activity is not affected by X4L4. In a DNA end-joining assay, we find that a substrate, which is processed by WRN, is ligated by X4L4, thus further supporting the significance of their functional interaction.
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Affiliation(s)
- Rika Kusumoto
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH, 5600 Nathan Shock Drive, Baltimore, Maryland 21224, USA
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88
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Hong Z, Jiang J, Lan L, Nakajima S, Kanno SI, Koseki H, Yasui A. A polycomb group protein, PHF1, is involved in the response to DNA double-strand breaks in human cell. Nucleic Acids Res 2008; 36:2939-47. [PMID: 18385154 PMCID: PMC2396414 DOI: 10.1093/nar/gkn146] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
DNA double-strand breaks (DSBs) represent the most toxic DNA damage arisen from endogenous and exogenous genotoxic stresses and are known to be repaired by either homologous recombination or nonhomologous end-joining processes. Although many proteins have been identified to participate in either of the processes, the whole processes still remain elusive. Polycomb group (PcG) proteins are epigenetic chromatin modifiers involved in gene silencing, cancer development and the maintenance of embryonic and adult stem cells. By screening proteins responding to DNA damage using laser micro-irradiation, we found that PHF1, a human homolog of Drosophila polycomb-like, Pcl, protein, was recruited to DSBs immediately after irradiation and dissociated within 10 min. The accumulation at DSBs is Ku70/Ku80-dependent, and knockdown of PHF1 leads to X-ray sensitivity and increases the frequency of homologous recombination in HeLa cell. We found that PHF1 interacts physically with Ku70/Ku80, suggesting that PHF1 promotes nonhomologous end-joining processes. Furthermore, we found that PHF1 interacts with a number of proteins involved in DNA damage responses, RAD50, SMC1, DHX9 and p53, further suggesting that PHF1, besides the function in PcG, is involved in genome maintenance processes.
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Affiliation(s)
- Zehui Hong
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Seiryomachi 4-1, Aobaku, Sendai 980-8575, Japan
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89
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Salminen A, Huuskonen J, Ojala J, Kauppinen A, Kaarniranta K, Suuronen T. Activation of innate immunity system during aging: NF-kB signaling is the molecular culprit of inflamm-aging. Ageing Res Rev 2008; 7:83-105. [PMID: 17964225 DOI: 10.1016/j.arr.2007.09.002] [Citation(s) in RCA: 410] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Revised: 09/14/2007] [Accepted: 09/14/2007] [Indexed: 10/22/2022]
Abstract
Innate and adaptive immunity are the major defence mechanisms of higher organisms against inherent and environmental threats. Innate immunity is present already in unicellular organisms but evolution has added novel adaptive immune mechanisms to the defence armament. Interestingly, during aging, adaptive immunity significantly declines, a phenomenon called immunosenescence, whereas innate immunity seems to be activated which induces a characteristic pro-inflammatory profile. This process is called inflamm-aging. The recognition and signaling mechanisms involved in innate immunity have been conserved during evolution. The master regulator of the innate immunity is the NF-kB system, an ancient signaling pathway found in both insects and vertebrates. The NF-kB system is in the nodal point linking together the pathogenic assault signals and cellular danger signals and then organizing the cellular resistance. Recent studies have revealed that SIRT1 (Sir2 homolog) and FoxO (DAF-16), the key regulators of aging in budding yeast and Caenorhabditis elegans models, regulate the efficiency of NF-kB signaling and the level of inflammatory responses. We will review the role of innate immunity signaling in the aging process and examine the function of NF-kB system in the organization of defence mechanisms and in addition, its interactions with the protein products of several gerontogenes. Our conclusion is that NF-kB signaling seems to be the culprit of inflamm-aging, since this signaling system integrates the intracellular regulation of immune responses in both aging and age-related diseases.
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90
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Galván N, Lim S, Zmugg S, Smith MT, Zhang L. Depletion of WRN enhances DNA damage in HeLa cells exposed to the benzene metabolite, hydroquinone. Mutat Res 2008; 649:54-61. [PMID: 17875398 PMCID: PMC3461953 DOI: 10.1016/j.mrgentox.2007.07.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2007] [Revised: 07/30/2007] [Accepted: 07/31/2007] [Indexed: 11/18/2022]
Abstract
Werner syndrome is a progeroid disorder caused by mutations of the WRN gene. The encoded WRN protein belongs to the family of RecQ helicases that plays a role in the maintenance of genomic stability. Single nucleotide polymorphisms in WRN have been associated with an increased risk for some cancers and were recently linked to benzene hematotoxicity. To further address the role of WRN in benzene toxicity, we employed RNA interference (RNAi) to silence endogenous WRN in HeLa cells and examined the susceptibility of these WRN-depleted cells to the toxic effects of the benzene metabolite hydroquinone. HeLa cells were used as the experimental model because RNAi is highly effective in this system producing almost complete depletion of the target protein. Depletion of WRN led to a decrease in cell proliferation and an enhanced susceptibility to hydroquinone cytotoxicity as revealed by an increase in necrosis. WRN-depleted HeLa cells treated with hydroquinone also displayed an increase in the amount of DNA double-strand breaks as determined by the Comet assay, and an elevated DNA damage response as indicated by the sevenfold induction of gammaH2AX and acetyl-p53 (Lys373 and Lys382) over control levels. Together, these results show that WRN plays an important role in the protection of HeLa cells against the toxicity of the benzene metabolite hydroquinone, specifically in mounting a normal DNA damage response following the induction of DNA double-strand breaks. Further studies in bone marrow-derived stem or progenitor cells are required to confirm our findings in HeLa cells and expand our ability to extrapolate the results to benzene toxicity in humans.
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Affiliation(s)
- Noé Galván
- Molecular Epidemiology and Toxicology Laboratory, School of Public Health, University of California at Berkeley, Berkeley, CA 94720
| | - Sophia Lim
- Molecular Epidemiology and Toxicology Laboratory, School of Public Health, University of California at Berkeley, Berkeley, CA 94720
| | - Stephan Zmugg
- Molecular Epidemiology and Toxicology Laboratory, School of Public Health, University of California at Berkeley, Berkeley, CA 94720
| | - Martyn T. Smith
- Molecular Epidemiology and Toxicology Laboratory, School of Public Health, University of California at Berkeley, Berkeley, CA 94720
| | - Luoping Zhang
- Molecular Epidemiology and Toxicology Laboratory, School of Public Health, University of California at Berkeley, Berkeley, CA 94720
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91
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Opresko PL. Telomere ResQue and preservation--roles for the Werner syndrome protein and other RecQ helicases. Mech Ageing Dev 2007; 129:79-90. [PMID: 18054793 DOI: 10.1016/j.mad.2007.10.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2007] [Revised: 10/12/2007] [Accepted: 10/23/2007] [Indexed: 12/30/2022]
Abstract
Werner syndrome is an autosomal recessive disorder resulting from loss of function of the RecQ helicase, WRN protein. WS patients prematurely develop numerous clinical symptoms and diseases associated with aging early in life and are predisposed to cancer. WRN protein and many other RecQ helicases in general, seem to function during DNA replication in the processing of stalled replication forks. Genetic, cellular and biochemical evidence support roles for WRN in proper replication and repair of telomeric DNA, and indicate that telomere dysfunction contributes to the WS disease pathology.
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Affiliation(s)
- Patricia L Opresko
- Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health, Bridgeside Pt., Pittsburgh, PA 15219, United States.
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92
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Prasad R, Liu Y, Deterding LJ, Poltoratsky VP, Kedar PS, Horton JK, Kanno SI, Asagoshi K, Hou EW, Khodyreva SN, Lavrik OI, Tomer KB, Yasui A, Wilson SH. HMGB1 is a cofactor in mammalian base excision repair. Mol Cell 2007; 27:829-41. [PMID: 17803946 PMCID: PMC2799894 DOI: 10.1016/j.molcel.2007.06.029] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2007] [Revised: 04/30/2007] [Accepted: 06/20/2007] [Indexed: 01/24/2023]
Abstract
Deoxyribose phosphate (dRP) removal by DNA polymerase beta (Pol beta) is a pivotal step in base excision repair (BER). To identify BER cofactors, especially those with dRP lyase activity, we used a Pol beta null cell extract and BER intermediate as bait for sodium borohydride crosslinking. Mass spectrometry identified the high-mobility group box 1 protein (HMGB1) as specifically interacting with the BER intermediate. Purified HMGB1 was found to have weak dRP lyase activity and to stimulate AP endonuclease and FEN1 activities on BER substrates. Coimmunoprecipitation experiments revealed interactions of HMGB1 with known BER enzymes, and GFP-tagged HMGB1 was found to accumulate at sites of oxidative DNA damage in living cells. HMGB1(-/-) mouse cells were slightly more resistant to MMS than wild-type cells, probably due to the production of fewer strand-break BER intermediates. The results suggest HMGB1 is a BER cofactor capable of modulating BER capacity in cells.
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Affiliation(s)
- Rajendra Prasad
- Laboratory of Structural Biology, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Yuan Liu
- Laboratory of Structural Biology, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Leesa J. Deterding
- Laboratory of Structural Biology, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Vladimir P. Poltoratsky
- Laboratory of Structural Biology, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Padmini S. Kedar
- Laboratory of Structural Biology, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Julie K. Horton
- Laboratory of Structural Biology, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Shin-ichiro Kanno
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Sendai 980-8575, Japan
| | - Kenjiro Asagoshi
- Laboratory of Structural Biology, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Esther W. Hou
- Laboratory of Structural Biology, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Svetlana N. Khodyreva
- Institute of Chemical Biology and Fundamental Medicine, Siberian Division of Russian Academy of Sciences, 630090 Novosibirsk, Russia
| | - Olga I. Lavrik
- Institute of Chemical Biology and Fundamental Medicine, Siberian Division of Russian Academy of Sciences, 630090 Novosibirsk, Russia
| | - Kenneth B. Tomer
- Laboratory of Structural Biology, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Akira Yasui
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Sendai 980-8575, Japan
| | - Samuel H. Wilson
- Laboratory of Structural Biology, NIEHS, National Institutes of Health, Research Triangle Park, NC 27709, USA
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93
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Saydam N, Kanagaraj R, Dietschy T, Garcia PL, Peña-Diaz J, Shevelev I, Stagljar I, Janscak P. Physical and functional interactions between Werner syndrome helicase and mismatch-repair initiation factors. Nucleic Acids Res 2007; 35:5706-16. [PMID: 17715146 PMCID: PMC2034464 DOI: 10.1093/nar/gkm500] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Werner syndrome (WS) is a severe recessive disorder characterized by premature aging, cancer predisposition and genomic instability. The gene mutated in WS encodes a bi-functional enzyme called WRN that acts as a RecQ-type DNA helicase and a 3′-5′ exonuclease, but its exact role in DNA metabolism is poorly understood. Here we show that WRN physically interacts with the MSH2/MSH6 (MutSα), MSH2/MSH3 (MutSβ) and MLH1/PMS2 (MutLα) heterodimers that are involved in the initiation of mismatch repair (MMR) and the rejection of homeologous recombination. MutSα and MutSβ can strongly stimulate the helicase activity of WRN specifically on forked DNA structures with a 3′-single-stranded arm. The stimulatory effect of MutSα on WRN-mediated unwinding is enhanced by a G/T mismatch in the DNA duplex ahead of the fork. The MutLα protein known to bind to the MutS α–heteroduplex complexes has no effect on WRN-mediated DNA unwinding stimulated by MutSα, nor does it affect DNA unwinding by WRN alone. Our data are consistent with results of genetic experiments in yeast suggesting that MMR factors act in conjunction with a RecQ-type helicase to reject recombination between divergent sequences.
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Affiliation(s)
- Nurten Saydam
- Institute of Molecular Cancer Research of the University of Zurich, Switzerland, Department of Biochemistry and Department of Medical Genetics and Microbiology, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Canada
| | - Radhakrishnan Kanagaraj
- Institute of Molecular Cancer Research of the University of Zurich, Switzerland, Department of Biochemistry and Department of Medical Genetics and Microbiology, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Canada
| | - Tobias Dietschy
- Institute of Molecular Cancer Research of the University of Zurich, Switzerland, Department of Biochemistry and Department of Medical Genetics and Microbiology, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Canada
| | - Patrick L. Garcia
- Institute of Molecular Cancer Research of the University of Zurich, Switzerland, Department of Biochemistry and Department of Medical Genetics and Microbiology, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Canada
| | - Javier Peña-Diaz
- Institute of Molecular Cancer Research of the University of Zurich, Switzerland, Department of Biochemistry and Department of Medical Genetics and Microbiology, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Canada
| | - Igor Shevelev
- Institute of Molecular Cancer Research of the University of Zurich, Switzerland, Department of Biochemistry and Department of Medical Genetics and Microbiology, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Canada
| | - Igor Stagljar
- Institute of Molecular Cancer Research of the University of Zurich, Switzerland, Department of Biochemistry and Department of Medical Genetics and Microbiology, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Canada
| | - Pavel Janscak
- Institute of Molecular Cancer Research of the University of Zurich, Switzerland, Department of Biochemistry and Department of Medical Genetics and Microbiology, Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Canada
- *To whom correspondence should be addressed. +41(0)44 635 3470+41(0)44 635 3484
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94
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Opresko PL, Calvo JP, von Kobbe C. Role for the Werner syndrome protein in the promotion of tumor cell growth. Mech Ageing Dev 2007; 128:423-36. [PMID: 17624410 DOI: 10.1016/j.mad.2007.05.009] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2007] [Revised: 05/18/2007] [Accepted: 05/21/2007] [Indexed: 11/20/2022]
Abstract
Werner syndrome (WS) is a premature aging and cancer-prone disease caused by loss of the RecQ helicase WRN protein. Cultured WS fibroblasts display high genomic instability and senesce prematurely. Epigenetic inactivation of the WRN gene occurs in numerous tumor types, in which WRN demonstrates tumor suppressor-like activity (Agrelo et al., 2006). However, the role of WRN in tumors that express WRN protein is unknown. Here we report that the inhibition of WRN expression strongly impairs growth of 12 out of 15 cancer cell lines tested. For those cell lines in which WRN depletion induced high cell death, the majority of the surviving proliferative clones exhibited WRN expression. Growth arrest induced by WRN depletion was characterized by an accumulation of cells in the G2/M cell cycle phases and an increase in DNA damage. Importantly, WRN depletion inhibited tumor growth in vivo in SCID mouse xenograft models. Altogether, these findings support a dual role for WRN in tumorigenesis; tumor suppressor-like activity in tumors with WRN inactivation and the promotion of proliferation and survival in tumors that express WRN. These findings suggest a possible therapeutic role for WRN as an anti-cancer target, and highlight the importance of WRN protein status for tumorigenesis and clinical treatments of patients.
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Affiliation(s)
- Patricia L Opresko
- University of Pittsburgh, Department of Environmental and Occupational Health, Pittsburgh, PA, USA.
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95
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Kamath-Loeb AS, Lan L, Nakajima S, Yasui A, Loeb LA. Werner syndrome protein interacts functionally with translesion DNA polymerases. Proc Natl Acad Sci U S A 2007; 104:10394-9. [PMID: 17563354 PMCID: PMC1965524 DOI: 10.1073/pnas.0702513104] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2007] [Indexed: 12/14/2022] Open
Abstract
Werner syndrome (WS) is characterized by premature onset of age-associated disorders and predisposition to cancer. The WS protein, WRN, encodes 3' --> 5' DNA helicase and 3' --> 5' DNA exonuclease activities, and is implicated in the maintenance of genomic stability. Translesion (TLS) DNA polymerases (Pols) insert nucleotides opposite replication-blocking DNA lesions and presumably prevent replication fork stalling/collapse. Here, we present in vitro and in vivo data that demonstrate functional interaction between WRN and the TLS Pols, Poleta, Polkappa, and Poliota. In vitro, WRN stimulates the extension activity of TLS Pols on lesion-free and lesion-containing DNA templates, and alleviates pausing at stalling lesions. Stimulation is mediated through an increase in the apparent V(max) of the polymerization reaction. Notably, by accelerating the rate of nucleotide incorporation, WRN increases mutagenesis by Poleta. In vivo, WRN and Poleta colocalize at replication-dependent foci in response to UVC irradiation. The functional interaction between WRN and TLS Pols may promote replication fork progression, at the expense of increased mutagenesis, and obviate the need to resolve stalled/collapsed forks by processes involving chromosomal rearrangements.
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Affiliation(s)
- Ashwini S. Kamath-Loeb
- *Department of Pathology, The Gottstein Memorial Cancer Research Center, University of Washington, Seattle, WA 98195; and
| | - Li Lan
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Seiryomachi 4-1, Aobaku, Sendai 98-8575, Japan
| | - Satoshi Nakajima
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Seiryomachi 4-1, Aobaku, Sendai 98-8575, Japan
| | - Akira Yasui
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Seiryomachi 4-1, Aobaku, Sendai 98-8575, Japan
| | - Lawrence A. Loeb
- *Department of Pathology, The Gottstein Memorial Cancer Research Center, University of Washington, Seattle, WA 98195; and
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96
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Uematsu N, Weterings E, Yano KI, Morotomi-Yano K, Jakob B, Taucher-Scholz G, Mari PO, van Gent DC, Chen BPC, Chen DJ. Autophosphorylation of DNA-PKCS regulates its dynamics at DNA double-strand breaks. ACTA ACUST UNITED AC 2007; 177:219-29. [PMID: 17438073 PMCID: PMC2064131 DOI: 10.1083/jcb.200608077] [Citation(s) in RCA: 321] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The DNA-dependent protein kinase catalytic subunit (DNA-PK(CS)) plays an important role during the repair of DNA double-strand breaks (DSBs). It is recruited to DNA ends in the early stages of the nonhomologous end-joining (NHEJ) process, which mediates DSB repair. To study DNA-PK(CS) recruitment in vivo, we used a laser system to introduce DSBs in a specified region of the cell nucleus. We show that DNA-PK(CS) accumulates at DSB sites in a Ku80-dependent manner, and that neither the kinase activity nor the phosphorylation status of DNA-PK(CS) influences its initial accumulation. However, impairment of both of these functions results in deficient DSB repair and the maintained presence of DNA-PK(CS) at unrepaired DSBs. The use of photobleaching techniques allowed us to determine that the kinase activity and phosphorylation status of DNA-PK(CS) influence the stability of its binding to DNA ends. We suggest a model in which DNA-PK(CS) phosphorylation/autophosphorylation facilitates NHEJ by destabilizing the interaction of DNA-PK(CS) with the DNA ends.
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Affiliation(s)
- Naoya Uematsu
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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97
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Hashiguchi K, Matsumoto Y, Yasui A. Recruitment of DNA repair synthesis machinery to sites of DNA damage/repair in living human cells. Nucleic Acids Res 2007; 35:2913-23. [PMID: 17439963 PMCID: PMC1888830 DOI: 10.1093/nar/gkm115] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The eukaryotic sliding DNA clamp, proliferating cell nuclear antigen (PCNA), is essential for DNA replication and repair synthesis. In order to load the ring-shaped, homotrimeric PCNA onto the DNA double helix, the ATPase activity of the replication factor C (RFC) clamp loader complex is required. Although the recruitment of PCNA by RFC to DNA replication sites has well been documented, our understanding of its recruitment during DNA repair synthesis is limited. In this study, we analyzed the accumulation of endogenous and fluorescent-tagged proteins for DNA repair synthesis at the sites of DNA damage produced locally by UVA-laser micro-irradiation in HeLa cells. Accumulation kinetics and in vitro pull-down assays of the large subunit of RFC (RFC140) revealed that there are two distinct modes of recruitment of RFC to DNA damage, a simultaneous accumulation of RFC140 and PCNA caused by interaction between PCNA and the extreme N-terminus of RFC140 and a much faster accumulation of RFC140 than PCNA at the damaged site. Furthermore, RFC140 knock-down experiments showed that PCNA can accumulate at DNA damage independently of RFC. These results suggest that immediate accumulation of RFC and PCNA at DNA damage is only partly interdependent.
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Affiliation(s)
- Kazunari Hashiguchi
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Sendai 980-8575, Japan and Division of Medical Science, Fox Chase Cancer Center, PA 19111, USA
| | - Yoshihiro Matsumoto
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Sendai 980-8575, Japan and Division of Medical Science, Fox Chase Cancer Center, PA 19111, USA
| | - Akira Yasui
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Sendai 980-8575, Japan and Division of Medical Science, Fox Chase Cancer Center, PA 19111, USA
- *To whom correspondence should be addressed. +81-22-717-8465+81-22-717-8470 Correspondence may also be addressed to Kazunari Hashiguchi. +81-22-717-8469 +81-22-717-8470
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98
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Kanno SI, Kuzuoka H, Sasao S, Hong Z, Lan L, Nakajima S, Yasui A. A novel human AP endonuclease with conserved zinc-finger-like motifs involved in DNA strand break responses. EMBO J 2007; 26:2094-103. [PMID: 17396150 PMCID: PMC1852789 DOI: 10.1038/sj.emboj.7601663] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2006] [Accepted: 03/05/2007] [Indexed: 11/09/2022] Open
Abstract
DNA damage causes genome instability and cell death, but many of the cellular responses to DNA damage still remain elusive. We here report a human protein, PALF (PNK and APTX-like FHA protein), with an FHA (forkhead-associated) domain and novel zinc-finger-like CYR (cysteine-tyrosine-arginine) motifs that are involved in responses to DNA damage. We found that the CYR motif is widely distributed among DNA repair proteins of higher eukaryotes, and that PALF, as well as a Drosophila protein with tandem CYR motifs, has endo- and exonuclease activities against abasic site and other types of base damage. PALF accumulates rapidly at single-strand breaks in a poly(ADP-ribose) polymerase 1 (PARP1)-dependent manner in human cells. Indeed, PALF interacts directly with PARP1 and is required for its activation and for cellular resistance to methyl-methane sulfonate. PALF also interacts directly with KU86, LIGASEIV and phosphorylated XRCC4 proteins and possesses endo/exonuclease activity at protruding DNA ends. Various treatments that produce double-strand breaks induce formation of PALF foci, which fully coincide with gammaH2AX foci. Thus, PALF and the CYR motif may play important roles in DNA repair of higher eukaryotes.
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Affiliation(s)
- Shin-ichiro Kanno
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Aobaku, Sendai, Japan
- Japan Bio Services Co., Ltd, Asaka, Saitama, Japan
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Seiryo-machi 4-1, Aobaku, Sendai 980-8575, Japan. Tel.: +81 22 717 8469; Fax: +81 22 717 8470; E-mail:
| | - Hiroyuki Kuzuoka
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Aobaku, Sendai, Japan
| | - Shigeru Sasao
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Aobaku, Sendai, Japan
| | - Zehui Hong
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Aobaku, Sendai, Japan
| | - Li Lan
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Aobaku, Sendai, Japan
| | - Satoshi Nakajima
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Aobaku, Sendai, Japan
| | - Akira Yasui
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Aobaku, Sendai, Japan
- Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Seiryo-machi 4-1, Aobaku, Sendai 980-8575, Japan. Tel.: +81 22 717 8465; Fax: +81 22 717 8470; E-mail:
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99
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Wu L, Hickson ID. DNA helicases required for homologous recombination and repair of damaged replication forks. Annu Rev Genet 2007; 40:279-306. [PMID: 16856806 DOI: 10.1146/annurev.genet.40.110405.090636] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
DNA helicases are found in all kingdoms of life and function in all DNA metabolic processes where the two strands of duplex DNA require to be separated. Here, we review recent developments in our understanding of the roles that helicases play in the intimately linked processes of replication fork repair and homologous recombination, and highlight how the cell has evolved many distinct, and sometimes antagonistic, uses for these enzymes.
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Affiliation(s)
- Leonard Wu
- Cancer Research UK, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, United Kingdom
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100
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Hirano M, Yamamoto A, Mori T, Lan L, Iwamoto TA, Aoki M, Shimada K, Furiya Y, Kariya S, Asai H, Yasui A, Nishiwaki T, Imoto K, Kobayashi N, Kiriyama T, Nagata T, Konishi N, Itoyama Y, Ueno S. DNA single-strand break repair is impaired in aprataxin-related ataxia. Ann Neurol 2007; 61:162-74. [PMID: 17315206 DOI: 10.1002/ana.21078] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
OBJECTIVE Early-onset ataxia with ocular motor apraxia and hypoalbuminemia (EAOH)/ataxia with oculomotor apraxia type 1 (AOA1) is an autosomal recessive form of cerebellar ataxia. The causative protein for EAOH/AOA1, aprataxin (APTX), interacts with X-ray repair cross-complementing 1 (XRCC1), a scaffold DNA repair protein for single-strand breaks (SSBs). The goal of this study was to prove the functional involvement of APTX in SSB repair (SSBR). METHODS We visualized the SSBR process with a recently developed laser irradiation system that allows real-time observation of SSBR proteins and with a local ultraviolet-irradiation system using a XPA-UVDE cell line that repairs DNA lesions exclusively via SSBR. APTX was knocked down using small interference RNA in the cells. Oxidative stress-induced DNA damage and cell death were assessed in EAOH fibroblasts and cerebellum. RESULTS Our systems showed the XRCC1-dependent recruitment of APTX to SSBs. SSBR was impaired in APTX-knocked-down cells. Oxidative stress in EAOH fibroblasts readily induced SSBs and cell death, which were blocked by antioxidants. Accumulated oxidative DNA damage was confirmed in EAOH cerebellum. INTERPRETATION This study provides the first direct evidence for the functional involvement of APTX in SSBR and in vivo DNA damage in EAOH/AOA1, and suggests a benefit of antioxidant treatment.
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Affiliation(s)
- Makito Hirano
- Department of Neurology, Radioisotope Research Center, Nara Medical University, Nara, Japan.
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