An apoptosis-inducing genotoxin differentiates heterozygotic carriers for Werner helicase mutations from wild-type and homozygous mutants

Ogburn, Charles E.; Oshima, Junko; Poot, Martin; Chen, Ru; Hunt, Kristin E.; Gollahon, Katherine A.; Rabinovitch, Peter S.; Martin, George M.

doi:10.1007/s004390050599

Cited by 177 publications

(147 citation statements)

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“…1A). The rationale for these experiments was provided by previous work showing intermediate sensitivity of WRN heterozygous lymphoblastoid cell lines to several DNA damaging agents including cis-Pt [24,25] and the identification of genetic instability in vivo in the red blood cell lineage of WRN heterozygotes [26].…”

Section: Resultsmentioning

confidence: 99%

The Werner syndrome protein has separable recombination and survival functions☆

et al. 2004

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The Werner syndrome (WS) protein WRN is unique in possessing a 3 to 5 exonuclease activity in addition to the 3 to 5 helicase activity characteristic of other RecQ proteins. In order to determine in vivo functions of the WRN catalytic activities and their roles in Werner syndrome pathogenesis, we quantified cell survival and homologous recombination after DNA damage in cells expressing WRN missense-mutant proteins that lacked exonuclease and/or helicase activity. Both WRN biochemical activities were required to generate viable recombinant daughter cells. In contrast, either activity was sufficient to promote cell survival after DNA damage in the absence of recombination. These results indicate that WRN has recombination and survival functions that can be separated by missense mutations. Two implications are that Werner syndrome most likely results from the loss of both activities and their associated functions from patient cells, and that WRN missense mutations or polymorphisms could promote genetic instability and cancer in the general population by selectively interfering with recombination in somatic cells.

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Section: Resultsmentioning

confidence: 99%

The Werner syndrome protein has separable recombination and survival functions☆

et al. 2004

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“…Noteworthy, yeast mutants in such RecQ-like helicases are extremely sensitive to agents that cause replication arrest, such as hydroxyurea because of uncontrolled illegitimate recombinational events (Stewart et al, 1997;Yamagata et al, 1998). The observed sensitivity of WS cells to 4-nitroquinoline-1-oxide (Gebhart et al, 1988;Ogburn et al (Lebel and Leder, 1998;Poot et al, 1999;Pichierri et al, 2000). For these reasons, it has been proposed that the primary defect of this disorder is "unprotected synthesis," that is, the failure of cells to protect the integrity of the genoma during the DNA replication process (Chakraverty and Hickson, 1999).…”

Section: Introductionmentioning

confidence: 99%

“…Noteworthy, yeast mutants in such RecQ-like helicases are extremely sensitive to agents that cause replication arrest, such as hydroxyurea because of uncontrolled illegitimate recombinational events (Stewart et al, 1997;Yamagata et al, 1998). The observed sensitivity of WS cells to 4-nitroquinoline-1-oxide (Gebhart et al, 1988;Ogburn et al, 1997) has prompted a search for sensitivity toward drugs that interfere with DNA replication and transcription. More recently, the finding that WS cells show sensitivity to camptothecin, an agent that produces replication-dependent DNA damage, reinforces the hypothesis that WRN functions mainly during the DNA replication processes (Lebel and Leder, 1998;Poot et al, 1999;Pichierri et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

Werner's Syndrome Protein Is Required for Correct Recovery after Replication Arrest and DNA Damage Induced in S-Phase of Cell Cycle

Pichierri

Franchitto

Mosesso

et al. 2001

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Werner's syndrome (WS) is a rare autosomal recessive disorder that arises as a consequence of mutations in a gene coding for a protein that is a member of RecQ family of DNA helicases, WRN. The cellular function of WRN is still unclear, but on the basis of the cellular phenotypes of WS and of RecQ yeast mutants, its possible role in controlling recombination and/or in maintenance of genomic integrity during S-phase has been envisaged. With the use of two drugs, camptothecin and hydroxyurea, which produce replication-associated DNA damage and/or inhibit replication fork progression, we find that WS cells have a slower rate of repair associated with DNA damage induced in the S-phase and a reduced induction of RAD51 foci. As a consequence, WS cells undergo apoptotic cell death more than normal cells, even if they arrest and resume DNA synthesis at an apparently normal rate. Furthermore, we report that WS cells show a higher background level of DNA strand breaks and an elevated spontaneous induction of RAD51 foci. Our findings support the hypothesis that WRN could be involved in the correct resolution of recombinational intermediates that arise from replication arrest due to either DNA damage or replication fork collapse. INTRODUCTIONWerner's syndrome (WS) is a rare autosomal recessive disorder characterized by premature aging (Salk et al., 1985) and early onset of various neoplasms, including different types of carcinomas and sarcomas (Goto et al., 1981;Hrabko et al., 1982;Sato et al., 1988). This disorder arises as a consequence of mutations in a gene coding for a protein that is a member of RecQ family of DNA helicases, WRN. One of the hallmarks of WS patients is the genomic instability as evidenced by the spontaneous chromosome anomalies and large deletions in many genes (Salk et al., 1985;Fukuchi et al., 1989). It has been demonstrated that WRN exhibits DNA unwinding activity (Gray et al., 1997;Suzuki et al., 1997) and exonuclease activity residing in the N-terminal region (Huang et al., 1998). The cellular function of WRN is still unclear. It has been proposed that helicases are required for various DNA metabolic activities, including progression of replication fork, segregation of newly replicated chromosomes, disruption of the nucleosome structure, DNA supercoiling, transcription, recombination, and repair (Duguet, 1997). In addition, it has been suggested that RecQ family of DNA helicases has an important role in the maintenance of genomic integrity during DNA replication . Studies from yeast show that DNA replication does not proceed normally in absence of RecQ helicase function (Stewart et al., 1997) and in Xenopus laevis the ortholog of WRN is absolutely required for proper formation of replication foci (Yan et al., 1998). Functional interaction between proteins involved in DNA replication, such as replication protein A (RPA) and DNA polymerase ␦, and WRN also have been reported (Shen et al., 1998;Brosh et al., 1999;Kamath-Loeb et al., 2000). Furthermore, in yeast, the RecQlike proteins seem involved in ...

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“…Clinicians should be aware of the possibility of elevated drug sensitivities to genotoxic agents in this patient population. 17 …”

Section: Infarction Management (Please Describe)mentioning

confidence: 99%

“…Clinicians should be aware of the potential for increased sensitivity to genotoxic drugs. 17 An affected person could learn that his or her children are unlikely to be affected by Werner syndrome.…”

Section: If Applicable Further Consequences Of Testingmentioning

confidence: 99%