Cytogenetics of Werner’s syndrome cultured skin fibroblasts: variegated translocation mosaicism

Salk, Darrell; Au, Kam; Hoehn, Holger; Martin, George M.

doi:10.1159/000131596

Cited by 233 publications

(138 citation statements)

References 7 publications

Supporting

Mentioning

130

Contrasting

Order By: Relevance

“…In contrast to the previous reports suggesting that WRN may function as a key factor in resolving aberrant DNA structures that arise from DNA metabolic processes Cheng et al, 1990;Constantinou et al, 2000;Fukuchi et al, 1989;Kamath-Loeb et al, 2000;Lebel et al, 1999;Salk et al, 1981), our study shows a novel function of WRN in accelerating rRNA transcription Figure 4 Pulse-chase analysis of rRNA synthesis in normal and WS ®broblasts. Normal ®broblasts (A/N0014) and WS ®broblasts (A/WS10801) were cultured at 378C for 48 h. Each culture was pulse-labeled with [ 3 H]-uridine (40 mCi/ml) for 2 h, and then was chased with 2 mM non-radioactive uridine for 1 h and 2 h. The radioactivity of total RNA prepared from each sample was counted.…”

Section: Resultscontrasting

confidence: 97%

WRN helicase accelerates the transcription of ribosomal RNA as a component of an RNA polymerase I-associated complex

et al. 2002

View full text Add to dashboard Cite

Werner syndrome (WS) is a rare autosmomal recessive genetic disorder causing premature aging. The gene (WRN) responsible for WS encodes a protein homologous to the RecQ-type helicase. WRN has a nucleolar localization signal and shows intranuclear tra cking between the nucleolus and the nucleoplasm. WRN is recruited into the nucleolus when rRNA transcription is reactivated in quiescent cells. Inhibition of mRNA transcription with a-amanitin has no e ect on nucleolar localization of WRN whereas inhibition of rRNA transcription with actinomycin D releases WRN from nucleoli, suggesting that nucleolar WRN is closely related to rRNA transcription by RNA polymerase I (RPI). A possible function of WRN on rRNA transcription through interaction with RPI is supported by the results described here showing that WRN is coimmunoprecipitated with an RPI subunit, RPA40. Here we show that WS ®broblasts are characterized by a decreased level of rRNA transcription compared with wild-type cells, and that the decreased level of rRNA transcription in WS ®broblasts recovers when wild-type WRN is exogenously expressed. By contrast, exogenously expressed mutant-type WRN lacking an ability to migrate into the nucleolus fails to stimulate rRNA transcription. These results suggest that WRN promotes rRNA transcription as a component of an RPIassociated complex in the nucleolus.

show abstract

Section: Resultscontrasting

confidence: 97%

WRN helicase accelerates the transcription of ribosomal RNA as a component of an RNA polymerase I-associated complex

et al. 2002

View full text Add to dashboard Cite

show abstract

“…3 A and B and Table 1). This result is in accordance with previously published studies, mostly carried out in WS patient lymphocytes, where large deletions, breaks, and reciprocal translocations were reported (6,7,26). The appearance of these chromosomal aberrations is also consistent with the formation of chromosome fusions quickly after suppression of DNA damage checkpoints in WS cells.…”

Section: Resultssupporting

confidence: 93%

“…The severity of this syndrome can be explained by the multiple functions of WRN, which plays a role in DNA replication, repair, and recombination (1,3,4). WS is also characterized by increased genomic instability, which likely is the cause of cancer in affected individuals (5)(6)(7). Cells derived from WS patients grow poorly in culture, entering a senescence phenotype after few population doublings.…”

mentioning

confidence: 99%

Telomere dysfunction as a cause of genomic instability in Werner syndrome

Crabbé

Jauch

Naeger

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

213

167

View full text Add to dashboard Cite

Werner syndrome (WS) is a rare human premature aging disease caused by mutations in the gene encoding the RecQ helicase WRN. In addition to the aging features, this disorder is marked by genomic instability, associated with an elevated incidence of cancer. Several lines of evidence suggest that telomere dysfunction is associated with the aging phenotype of the syndrome; however, the origin of the genomic instability observed in WS cells and the reason for the high incidence of cancer in WS have not been established. We previously proposed that WRN helicase activity was necessary to prevent dramatic telomere loss during DNA replication. Here we demonstrate that replication-associated telomere loss is responsible for the chromosome fusions found in WS fibroblasts. Moreover, using metaphase analysis we show that telomere elongation by telomerase can significantly reduce the appearance of new chromosomal aberrations in cells lacking WRN, similar to complementation of WS cells with WRN. Our results suggest that the genome instability in WS cells depends directly on telomere dysfunction, linking chromosome end maintenance to chromosomal aberrations in this disease.cancer ͉ WRN ͉ genome instability ͉ aging

show abstract

“…2 The purified EXO-1 protein was judged to be Ͼ97% pure from analysis on Coomassie-stained SDS-polyacrylamide gels (see Fig. 2A).…”

Section: Methodsmentioning

confidence: 99%

The Exonucleolytic and Endonucleolytic Cleavage Activities of Human Exonuclease 1 Are Stimulated by an Interaction with the Carboxyl-terminal Region of the Werner Syndrome Protein

Sharma

Sommers

Driscoll

et al. 2003

Journal of Biological Chemistry

View full text Add to dashboard Cite

Exonuclease 1 (EXO-1), a member of the RAD2 family of nucleases, has recently been proposed to function in the genetic pathways of DNA recombination, repair, and replication which are important for genome integrity. Although the role of EXO-1 is not well understood, its 5 to 3 -exonuclease and flap endonuclease activities may cleave intermediates that arise during DNA metabolism. In this study, we provide evidence that the Werner syndrome protein (WRN) physically interacts with human EXO-1 and dramatically stimulates both the exonucleolytic and endonucleolytic incision functions of EXO-1. The functional interaction between WRN and EXO-1 is mediated by a protein domain of WRN which interacts with flap endonuclease 1 (FEN-1). Thus, the genomic instability observed in WRN؊/؊ cells may be at least partially attributed to the lack of interactions between the WRN protein and human nucleases including EXO-1.Werner syndrome (WS) 1 is a hereditary premature aging disorder characterized by genome instability (1). WS cells display elevated chromosomal aberrations (2-4), replication defects (3, 5-8), abnormal recombination (9, 10), altered telomere dynamics (11), and hypersensitivity to DNA-damaging agents (12-16). The gene defective in WS, designated WRN (17), encodes a protein with DNA helicase (18,19) and exonuclease (20 -22) activities which presumably functions in DNA metabolism to preserve genome integrity. To understand the basis of WS, a number of groups have investigated WRN protein interactions (for review, see Ref. 23). The collective work indicates that WRN interacts functionally with proteins implicated in replication and DNA repair including replication protein A (RPA), p53, Ku, and polymerase ␦. These studies have enabled researchers to speculate about pathways of DNA metabolism in which WRN might participate; however, the precise functions of the WRN gene product in vivo are not well understood.Recently we reported a novel interaction of WRN protein with the human 5Ј-flap endonuclease/5Ј to 3Ј-exonuclease (FEN-1) (24), a DNA structure-specific nuclease implicated in DNA replication, recombination, and repair (25). WRN protein stimulates FEN-1 cleavage activity by a physical interaction with a COOH-terminal domain of the WRN protein (24). Another member of the RAD2 family to which FEN-1 belongs is human exonuclease 1 (EXO-1) (26). Like FEN-1, EXO-1 is a structure-specific endonuclease as well as an exonuclease (27, 28). EXO-1 has been implicated in a number of DNA metabolic pathways including mismatch correction, mitotic and meiotic recombination, and double strand break repair (29 -34). A role for EXO-1 in Okazaki fragment processing during DNA replication has been suggested based on its structure-specific endonuclease and RNase H activities that are similar to those of FEN-1 (30). Functional overlap between EXO-1 and FEN-1 (Rad27 in Saccharomyces cerevisiae) has been proposed from observations in yeast that exoI: rad27 double mutants are inviable (35) and that overexpression of yeast EXO-1 or human EXO-1 co...

show abstract

Cytogenetics of Werner’s syndrome cultured skin fibroblasts: variegated translocation mosaicism

Cited by 233 publications

References 7 publications

WRN helicase accelerates the transcription of ribosomal RNA as a component of an RNA polymerase I-associated complex

WRN helicase accelerates the transcription of ribosomal RNA as a component of an RNA polymerase I-associated complex

Telomere dysfunction as a cause of genomic instability in Werner syndrome

The Exonucleolytic and Endonucleolytic Cleavage Activities of Human Exonuclease 1 Are Stimulated by an Interaction with the Carboxyl-terminal Region of the Werner Syndrome Protein

Contact Info

Product

Resources

About