Isolation of novel human and mouse genes of the recA/RAD51 recombination-repair gene family

Cartwright, R. D.; Dunn, Alison M.; Simpson, Paul J.; Tambini, Cathryn E.; Thacker, John

doi:10.1093/nar/26.7.1653

Cited by 83 publications

(51 citation statements)

References 46 publications

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“…This is interpreted as inhibition of a repair process, repair of potentially lethal damage (Iliakis, 1988), which occurs with a variable e cacy throughout the cell cycle (Beetham and Tolmach, 1984;Iliakis and Nusse, 1983b). A similar¯attening in the cell cycle dependent variation in radiosensitivity to killing is observed in irs1 cells (Cheong et al, 1994), a radiosensitive mutant isolated from V79 cells (Jones et al, 1987), and shown to be defective in XRCC2, a RAD51 homolog (Cartwright et al, 1998;Liu et al, 1998;Tambini et al, 1997). Practically identical observations regarding radiosensitivity throughout the cell cycle have recently been published in DT40 mutants de®cient in RAD54 (Takata et al, 1998).…”

Section: Introductionmentioning

confidence: 72%

“…Irs1 cells corrected for XRCC2 (irs1/ XRCC2) were generated by transfecting XRCC2 cDNA in a mammalian expression vector as described (Cartwright et al, 1998). Following selection for successful transfection, complemented clones showing more than 10-fold increase in resistance to the DNA cross-linking agent mitomycin C were tested for correction with respect to radiosensitivity to killing.…”

Section: Cell Culture and Irradiationmentioning

confidence: 99%

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Homologous recombination as a potential target for caffeine radiosensitization in mammalian cells: reduced caffeine radiosensitization in XRCC2 and XRCC3 mutants

et al. 2000

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The radiosensitizing e ect of ca eine has been associated with the disruption of multiple DNA damage-responsive cell cycle checkpoints, but several lines of evidence also implicate inhibition of DNA repair. The role of DNA repair inhibition in ca eine radiosensitization remains uncharacterized, and it is unknown which repair process, or lesion, is a ected. We show that a radiosensitive cell line, mutant for the RAD51 homolog XRCC2 and defective in homologous recombination repair (HRR), displays signi®cantly diminished ca eine radiosensitization that can be restored by expression of XRCC2. Despite the reduced radiosensitization, ca eine e ectively abrogates checkpoints in S and G2 phases in XRCC2 mutant cells indicating that checkpoint abrogation is not su cient for radiosensitization. Another radiosensitive line, mutant for XRCC3 and defective in HRR, similarly shows reduced ca eine radiosensitization. On the other hand, a radiosensitive mutant (irs-20) of DNA-PKcs with a defect in non-homologous endjoining (NHEJ) is radiosensitized by ca eine to an extent comparable to wild-type cells. In addition, rejoining of radiation-induced DNA DSBs, that mainly re¯ects NHEJ, remains una ected by ca eine in XRCC2 and XRCC3 mutants, or their wild-type counterparts. These observations suggest that ca eine targets steps in HRR but not in NHEJ and that abrogation of checkpoint response is not su cient to explain radiosensitization. Indeed, immortalized ®bro-blasts from AT patients show ca eine radiosensitization despite the checkpoint defects associated with ATM mutation. We propose that ca eine radiosensitization is mediated by inhibition of stages in DNA DSB repair requiring HRR and that checkpoint disruption contributes by allowing these DSBs to transit into irreparable states. Thus, checkpoints may contribute to genomic stability by promoting error-free HRR. Oncogene (2000) 19, 5788 ± 5800.

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Section: Introductionmentioning

confidence: 72%

Section: Cell Culture and Irradiationmentioning

confidence: 99%

Homologous recombination as a potential target for caffeine radiosensitization in mammalian cells: reduced caffeine radiosensitization in XRCC2 and XRCC3 mutants

et al. 2000

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“…Further investigation of the SHU genes in S. cerevisiae is likely to be relevant to all eukaryotes, because putative PSY3 and SHU2 homologues have recently been identified in Schizosaccharomyces pombe (rld1 ϩ and sws1 ϩ , respectively) and human cells (RAD51D and SWS1, respectively;Martin et al, 2006). RAD51D is one of the so-called human RAD51 paralogs, based on some shared sequence similarity to RAD51 (Cartwright et al, 1998a;Kawabata and Saeki, 1998;Pittman et al, 1998). Interestingly, like psy3 and shu2 mutations in S. cerevisiae, mutation of rld1 ϩ or sws1 ϩ in S. pombe also causes sensitivity to MMS (but not to other types of DNA damage) and rescues various cellular defects caused by mutation of the RecQ helicase gene, rqh1 ϩ , in S. pombe (Martin et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

“…RAD51D is one of the so-called human RAD51 paralogs, based on some shared sequence similarity to RAD51 (Cartwright et al, 1998a;Kawabata and Saeki, 1998;Pittman et al, 1998). Interestingly, like psy3 and shu2 mutations in S. cerevisiae, mutation of rld1 ϩ or sws1 ϩ in S. pombe also causes sensitivity to MMS (but not to other types of DNA damage) and rescues various cellular defects caused by mutation of the RecQ helicase gene, rqh1 ϩ , in S. pombe (Martin et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Shu Proteins Promote the Formation of Homologous Recombination Intermediates That Are Processed by Sgs1-Rmi1-Top3

Mankouri

Ngo

Hickson

2007

MBoC

125

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CSM2, PSY3, SHU1, and SHU2 (collectively referred to as the SHU genes) were identified in Saccharomyces cerevisiae as four genes in the same epistasis group that suppress various sgs1 and top3 mutant phenotypes when mutated. Although the SHU genes have been implicated in homologous recombination repair (HRR), their precise role(s) within this pathway remains poorly understood. Here, we have identified a specific role for the Shu proteins in a Rad51/Rad54-dependent HRR pathway(s) to repair MMS-induced lesions during S-phase. We show that, although mutation of RAD51 or RAD54 prevented the formation of MMS-induced HRR intermediates (X-molecules) arising during replication in sgs1 cells, mutation of SHU genes attenuated the level of these structures. Similar findings were also observed in shu1 cells in which Rmi1 or Top3 function was impaired. We propose a model in which the Shu proteins act in HRR to promote the formation of HRR intermediates that are processed by the Sgs1-Rmi1-Top3 complex. INTRODUCTIONHomologous recombination repair (HRR) is a well-conserved cellular process for the repair of single-strand DNA (ssDNA) gaps and double-strand DNA breaks (DSBs) that can arise during DNA synthesis or as a result of replication fork stalling during S-phase. Although many of the key proteins involved in HRR have been identified (reviewed in Paques and Haber, 1999;Sung et al., 2003;West, 2003;Krogh and Symington, 2004), in some cases their precise function(s) remains to be identified. Moreover, the mechanisms for suppression of inappropriate HRR in S-phase are only poorly defined. It is likely that HRR must be carefully regulated and/or executed in dividing cells, as inappropriate or excessive HR can lead to genome rearrangements and cancer in mammals. This is exemplified by the cancer-predisposition disorder, Bloom's syndrome, which is caused by mutation in the human BLM gene (reviewed in German, 1993). Because the BLM protein, in conjunction with its associated proteins, hTOPOIII␣ and hRMI1 (Johnson et al., 2000;Wu et al., 2000;Yin et al., 2005), can catalyze dissolution of HRR intermediates in vitro Plank et al., 2006;Raynard et al., 2006;Wu et al., 2006), it is likely that unprocessed and/or aberrantly processed HRR intermediates at least partly contribute to the cellular defects in Bloom's syndrome. Indeed, Bloom's syndrome cells classically demonstrate elevated levels of sister chromatid exchanges, mitotic recombination, and genome instability. Mutation of the BLM, hTOPOIII␣, or hRMI1 homologues in Saccharomyces cerevisiae (SGS1, TOP3, or RMI1, respectively) similarly causes sensitivity to genotoxic agents, hyper-recombination, and synthetic lethality with mutations in other genes also implicated in HRR (e.g., MUS81 and SRS2; Gangloff et al., 1994;Watt et al., 1996;Gangloff et al., 2000;Mullen et al., 2001;Fabre et al., 2002;Chang et al., 2005;Mullen et al., 2005). Furthermore, unresolved HRR intermediates have been directly visualized by two-dimensional (2D) gel electrophoresis in cells lacking Sgs1 or in cells w...

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“…To investigate whether inhibition of HDR is a component of caffeine radiosensitization, we tested wild type and two radiosensitive mutant cell lines, irs1 and irs1SF (Jones et al, 1987;Fuller and Painter, 1988), with defects in the RAD51 paralogs XRCC2 (Tambini et al, 1997;Cartwright et al, 1998;Liu et al, 1998) and XRCC3 (Tebbs et al, 1995;Liu et al, 1998), respectively, and documented defects in HDR Pierce et al, 1999). We reasoned that if caffeine acts as a radiosensitizer by selectively targeting steps in HDR, it should be less effective in cells with genetic defects in this pathway.…”

Section: Introductionmentioning

confidence: 99%

Caffeine inhibits homology-directed repair of I-SceI-induced DNA double-strand breaks

et al. 2004

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We recently reported that two Chinese hamster mutants deficient in the RAD51 paralogs XRCC2 and XRCC3 show reduced radiosensitization after treatment with caffeine, thus implicating homology-directed repair (HDR) of DNA double-strand breaks (DSBs) in the mechanism of caffeine radiosensitization. Here, we investigate directly the effect of caffeine on HDR initiated by DSBs induced by a rare cutting endonuclease (I-SceI) into one of two direct DNA repeats. The results demonstrate a strong inhibition by caffeine of HDR in wild-type cells, and a substantial reduction of this effect in HDR-deficient XRCC3 mutant cells. Inhibition of HDR and cell radiosensitization to killing shows similar dependence on caffeine concentration suggesting a cause-effect relationship between these effects. UCN-01, a kinase inhibitor that effectively abrogates checkpoint activation in irradiated cells, has only a small effect on HDR, indicating that similar to radiosensitization, inhibition of checkpoint signaling is not sufficient for HDR inhibition. Recombination events occurring during treatment with caffeine are characterized by rearrangements reminiscent to those previously reported for the XRCC3 mutant, and immunofluorescence microscopy demonstrates significantly reduced formation of IR-specific RAD51 foci after caffeine treatment. In summary, our results identify inhibition of HDR as a significant contributor to caffeine radiosensitization.

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Isolation of novel human and mouse genes of the recA/RAD51 recombination-repair gene family

Cited by 83 publications

References 46 publications

Homologous recombination as a potential target for caffeine radiosensitization in mammalian cells: reduced caffeine radiosensitization in XRCC2 and XRCC3 mutants

Homologous recombination as a potential target for caffeine radiosensitization in mammalian cells: reduced caffeine radiosensitization in XRCC2 and XRCC3 mutants

Shu Proteins Promote the Formation of Homologous Recombination Intermediates That Are Processed by Sgs1-Rmi1-Top3

Caffeine inhibits homology-directed repair of I-SceI-induced DNA double-strand breaks

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