Analysis of helicase gene mutations in Japanese Werner's syndrome patients

Goto, Makaoto; Imamura, Osamu; Kuromitsu, Junro; Matsumoto, Takehisa; Yamabe, Yukako; Tokutake, Yoshiki; Suzuki, Noriyuki; Mason, Brian; Drayna, Dennis; Sugawara, Mitsuru; Sugimoto, Masanobu; Furuichi, Yasuhiro

doi:10.1007/s004390050336

Cited by 82 publications

(57 citation statements)

References 6 publications

(6 reference statements)

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“…Mutations in the WS gene (WRN) are found in patients exhibiting the clinical symptoms of WS (3)(4)(5). The vast majority of WRN mutations result in loss of function of the WRN protein (6).…”

Section: Dna Methylationmentioning

confidence: 99%

Epigenetic inactivation of the premature aging Werner syndrome gene in human cancer

Agrelo

Cheng

Setién

et al. 2006

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

241

227

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Werner syndrome (WS) is an inherited disorder characterized by premature onset of aging, genomic instability, and increased cancer incidence. The disease is caused by loss of function mutations of the WRN gene, a RecQ family member with both helicase and exonuclease activities. However, despite its putative tumorsuppressor function, little is known about the contribution of WRN to human sporadic malignancies. Here, we report that WRN function is abrogated in human cancer cells by transcriptional silencing associated with CpG island-promoter hypermethylation. We also show that, at the biochemical and cellular levels, the epigenetic inactivation of WRN leads to the loss of WRN-associated exonuclease activity and increased chromosomal instability and apoptosis induced by topoisomerase inhibitors. The described phenotype is reversed by the use of a DNA-demethylating agent or by the reintroduction of WRN into cancer cells displaying methylationdependent silencing of WRN. Furthermore, the restoration of WRN expression induces tumor-suppressor-like features, such as reduced colony formation density and inhibition of tumor growth in nude mouse xenograft models. Screening a large collection of human primary tumors (n ‫؍‬ 630) from different cell types revealed that WRN CpG island hypermethylation was a common event in epithelial and mesenchymal tumorigenesis. Most importantly, WRN hypermethylation in colorectal tumors was a predictor of good clinical response to the camptothecin analogue irinotecan, a topoisomerase inhibitor commonly used in the clinical setting for the treatment of this tumor type. These findings highlight the importance of WRN epigenetic inactivation in human cancer, leading to enhanced chromosomal instability and hypersensitivity to chemotherapeutic drugs. DNA methylationW erner syndrome (WS) is an autosomal recessive disease characterized by premature aging and a high incidence of malignant neoplasms (1, 2). Mutations in the WS gene (WRN) are found in patients exhibiting the clinical symptoms of WS (3-5). The vast majority of WRN mutations result in loss of function of the WRN protein (6). The WRN protein has been demonstrated to possess helicase and exonuclease activities (7-9), and cultures of WS cells show increased chromosomal instability, with abundant deletions, reciprocal translocations, and inversions (10, 11).WRN belong to the RecQ family of helicases, which are highly conserved from bacteria to human, and whose members are thought to be essential caretakers of the genome (11,12). In addition to WRN, germline mutations of two other RecQ helicases, BLM in Bloom syndrome and RECQL4 in Rothmund-Thomson syndrome, are also associated with an elevated incidence of cancer (12). Because patients with WRN germline mutations develop a broad spectrum of epithelial and mesenchymal tumors, which is one of the main causes of their death before the age of 50, a tumorsuppressor function for WRN has been proposed. This putative role is also supported by a very high rate of loss of heterozygosity at the chrom...

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Section: Dna Methylationmentioning

confidence: 99%

Epigenetic inactivation of the premature aging Werner syndrome gene in human cancer

Agrelo

Cheng

Setién

et al. 2006

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

241

227

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“…The best-known segmental progeroid syndrome is Werner's syndrome (WS) (Goto et al, 1997). An inactivating mutation in WRN, a homolog of the E. coli RECQ gene, causes WS (Yu et al, 1996).…”

Section: Dna Damage Defective Mammalian Models Of Agingmentioning

confidence: 99%

DNA double-strand breaks: A potential causative factor for mammalian aging?

Han

Mitchell

Hasty

2008

Mechanisms of Ageing and Development

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Aging is a pleiotropic and stochastic process influenced by both genetics and environment. As a result the fundamental underlying causes of aging are controversial and likely diverse. Genome maintenance and in particular the repair of DNA damage is critical to ensure longevity needed for reproduction and as a consequence imperfections or defects in maintaining the genome may contribute to aging. There are many forms of DNA damage with double-strand breaks (DSBs) being the most toxic. Here we discuss DNA DSBs as a potential causative factor for aging including factors that generate DNA DSBs, pathways that repair DNA DSBs, consequences of faulty or failed DSB repair and how these consequences may lead to age-dependent decline in fitness. At the end we compare mouse models of premature aging that are defective for repairing either DSBs or UV lightinduced lesions. Based on these comparisons we believe the basic mechanisms responsible for their aging phenotypes are fundamentally different demonstrating the complex and pleiotropic nature of this process.

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“…Most of the mutations identified in WRN cause premature termination of translation (13,14) resulting in impaired nuclear import of the protein, because the nuclear localization signal is located in the carboxyl terminus of Wrn (15). Therefore, the clinical features and cellular phenotypes of most WS patients are due to an absolute lack of Wrn helicase in the nucleus.…”

mentioning

confidence: 99%

Covalent Modification of the Werner's Syndrome Gene Product with the Ubiquitin-related Protein, SUMO-1

Kawabe

Seki

et al. 2000

Journal of Biological Chemistry

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101

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Werner's syndrome is a potential model of accelerated human aging. The gene responsible for Werner's syndrome encodes a protein that has a helicase domain homologous to Escherichia coli RecQ. To identify binding partners that regulate the function in concert with Wrn, we screened for proteins using the yeast two-hybrid system with mouse Wrn as bait and found three. One was a novel protein, and the other two were mouse Ubc9 and SUMO-1. Ubc9 also interacted with the mouse homologue of the Bloom's syndrome gene product, another eukaryotic RecQ-type helicase, but not mouse DNA helicase Q1/RecQL (RecQL1). Deletion experiments indicated that both proteins interacted with the N-terminal segment of Wrn (amino acid 272-514). The interaction between Wrn and SUMO-1 was weaker than that between Wrn and Ubc9. Positive interaction was observed in the heterogeneous combination of Wrn and yeast Ubc9 (yUbc9), as well as yUbc9 and SUMO-1, in the two-hybrid system. The interaction between yUbc9 and SUMO-1 was abolished by deleting the C-terminal Gly residue of SUMO-1, which is reportedly required for the formation of Ubc9-SUMO-1 thioester linkage. The interaction of Wrn and SUMO-1 was also abolished by deleting the Gly residue, indicating that the interaction of Wrn and SUMO-1 is mediated by yUbc9 in the two-hybrid system. Finally, we confirmed by immunoblotting with an anti-SUMO-1 antibody that Wrn was covalently attached with SUMO-1.

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Analysis of helicase gene mutations in Japanese Werner's syndrome patients

Cited by 82 publications

References 6 publications

Epigenetic inactivation of the premature aging Werner syndrome gene in human cancer

Epigenetic inactivation of the premature aging Werner syndrome gene in human cancer

DNA double-strand breaks: A potential causative factor for mammalian aging?

Covalent Modification of the Werner's Syndrome Gene Product with the Ubiquitin-related Protein, SUMO-1

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