Sensitivity of Bloom's syndrome lymphocytes to ethyl methanesulfonate

Krepinsky, Alena B.; Heddle, John A.; German, James

doi:10.1007/bf00390236

Cited by 75 publications

(29 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similarly, treatment of Bloom syndrome patientderived cells with the alkylating agent ethyl methanesulfonate (EMS) leads to elevated SCEs (Krepinsky et al 1979). These findings support models in which BLM is important in managing forks when DNA synthesis is blocked.…”

Section: Functions Of Blm In Preventing Mitotic Crossoversmentioning

confidence: 65%

Sources and Structures of Mitotic Crossovers That Arise When BLM Helicase Is Absent inDrosophila

et al. 2014

View full text Add to dashboard Cite

The Bloom syndrome helicase, BLM, has numerous functions that prevent mitotic crossovers. We used unique features of Drosophila melanogaster to investigate origins and properties of mitotic crossovers that occur when BLM is absent. Induction of lesions that block replication forks increased crossover frequencies, consistent with functions for BLM in responding to fork blockage. In contrast, treatment with hydroxyurea, which stalls forks, did not elevate crossovers, even though mutants lacking BLM are sensitive to killing by this agent. To learn about sources of spontaneous recombination, we mapped mitotic crossovers in mutants lacking BLM. In the male germline, irradiation-induced crossovers were distributed randomly across the euchromatin, but spontaneous crossovers were nonrandom. We suggest that regions of the genome with a high frequency of mitotic crossovers may be analogous to common fragile sites in the human genome. Interestingly, in the male germline there is a paucity of crossovers in the interval that spans the pericentric heterochromatin, but in the female germline this interval is more prone to crossing over. Finally, our system allowed us to recover pairs of reciprocal crossover chromosomes. Sequencing of these revealed the existence of gene conversion tracts and did not provide any evidence for mutations associated with crossovers. These findings provide important new insights into sources and structures of mitotic crossovers and functions of BLM helicase. MEIOTIC recombination was discovered 100 years ago by T. H. Morgan and his students in classic studies of Drosophila genetics (Morgan 1911). Since that time, a great deal has been learned about the functions, molecular mechanisms, and regulation of meiotic recombination. This process is initiated through the introduction of programmed DNA doublestrand breaks (DSBs), which are then repaired through highly regulated homologous recombination (HR) pathways such that a substantial fraction of repair events produce reciprocal crossovers (reviewed in Kohl and Sekelsky 2013). The chiasmata that form at sites of crossovers help to ensure accurate segregation of homologous chromosomes. In addition, crossovers generate chromosomes with novel combinations of alleles at linked loci, leading to increased genetic diversity.A quarter century after the discovery of meiotic recombination, Curt Stern, also working with Drosophila, found that crossovers can occur in somatic cells (Stern 1936). This phenomenon is usually called "mitotic recombination," although most such events are thought to occur during interphase rather than in mitosis per se. Compared to meiotic recombination, little is known about mitotic recombination. Except in some specialized cases, like antibody gene rearrangement, mitotic recombination occurs in response to DNA damage (spontaneous or exogenously induced). Mitotic recombination, like meiotic recombination, can be initiated by DSBs, but it is unclear whether DSBs constitute a substantial fraction of the events that initiate spontan...

show abstract

Section: Functions Of Blm In Preventing Mitotic Crossoversmentioning

confidence: 65%

Sources and Structures of Mitotic Crossovers That Arise When BLM Helicase Is Absent inDrosophila

et al. 2014

View full text Add to dashboard Cite

show abstract

“…Finally, the flow methodology developed to study Fanconi's anemia might prove useful in analysis of cells from patients with other diseases, who are treated with agents to which these cells show unusual sensitivity. Examples include cells from ataxia telangiectasia exposed to bleomycin (32,48), MNNG (46), or x-rays (ll), cells from Bloom's syndrome exposed to EMS (26,27), or cells from xeroderma pigmentosum exposed to ultraviolet light (10).…”

Section: Discussionmentioning

confidence: 99%

Flow cytometric characterization of the response of Fanconi's anemia cells to mitomycin C treatment

et al. 1982

View full text Add to dashboard Cite

DNA flow histogram analysis, using 33342 Hoechst as a stain, has been used to detect the effect of the potentially bifunctional alkylating agent, mitomycin C (MMC) on dermal fibroblasts from patients with Fanconi's anemia (FA), a hereditary human disease characterized by pancytopenia, hypersensitivity to DNA-crosslinking agents, congenital abnormalities, and a predisposition for neoplasia. At 24 or 48 hr after a 2-hr exposure to 0.05 or 0.10 pg/ml MMC, 3HdT incorporation was reduced to a greater extent in FA cells than in normal cells. Cells sorted from the last half of S phase showed a slightly greater inhibition of 3HdT incorporation than did those sorted from the first half of S.Fanconi's anemia cells exhibited a marked accumulation in the Gz + M peak of flow histograms following exposure to MMC. Twenty-four hr after treatment with 0.05 pg/ ml MMC, the G2 + M fraction of FA cells (eight lines) increased to more than 0.5 from a control value of approximately 0.2. Both normals (six lines) and heterozygotes (eight lines) showed, on the average, much less of a Gz + M increment than did FA cells, even after exposure to 0.1 pg/ml MMC. Examination of cells sorted from the Gz + M peak revealed that MMC-treated FA cells were blocked prior to mitosis.To determine whether the response of FA cells was specific for a bifunctional alkylating agent, cells were also treated with ethylmethanesulfonate, a monofunctional agent. Twenty-four hours after exposure to 0.25 or 0.5 mg/ml ethylmethanesulfonate, FA and normal cells showed similar, small increases in the G2 + M peak. The results suggest the utility of flow cytometry in the diagnostic evaluation of fibroblasts from patients suspected of having Fanconi's anemia.Key terms: Fanconi's anemia, DNA crosslinking agent, mitomycin C, flow cytometry, 33342 Hoechst, Gz block, Cell cycle analysis, DNA repair Fanconi's anemia (FA), a syndrome of pancytopenia and a variable constellation of congenital anomalies (12,34,44), has been shown to be associated with chromosomal instability (8, 42, 47) and a predisposition for cancer (5,16, 43). Cells from patients with FA show increased sensitivity to agents capable of producing DNA crosslinks. This sensitivity is evident as decreased survival (51), increased chromosome breakage (3, 29,40) and a reduction in both the rate of progression through I This research was supported by grants CD-36F from the American Cancer Society and GM21121 from the National Institute of General Medical Sciences.Presented at the VIII Conference on Analytical Cytology and Cytometry, Wentworth-by-the-Sea, New Hampshire, May 19-25, 1981. the cell cycle (41) and in the proportion of mitotic cells (17, 51), following exposure to such agents.A reduction in the ability of cells from patients with Fanconi's anemia to remove DNA crosslinks, caused e.g. by mitomycin C (MMC), was observed in some studies (15) but not in others (13, 25). There are also isolated reports that cells from patients with FA exhibit other defects, such as a reduced ability to remove damage induc...

show abstract

“…However, WS cells do not exhibit a hypersensitivity to other DNA-damaging agents such as most alkylating agents, and X-rays, bleomycin, or H 2 O 2 that produce reactive oxygen species (Fujiwara et al, 1977;Gebhart et al, 1988;Higashikawa and Fujiwara, 1978;Okada et al, 1998), as well as to UV irradiation (Krepinsky et al, 1979). On the other hand, BS cells show hypersensitivities to N-ethyl-N-nitrosourea, ethyl methanesulfonate, methyl methanesulfonate (MMS) and 4-NQO, as well as UV irradiation (Krepinsky et al, 1979;Kurihara et al, 1987;Shiraishi et al, 1985). These observations suggest that both WRN and BLM may be directly or indirectly involved in DNA repair and may prefer certain types of DNA damage, respectively.…”

Section: Introductionmentioning

confidence: 99%

Werner and Bloom helicases are involved in DNA repair in a complementary fashion

et al. 2002

View full text Add to dashboard Cite

Werner syndrome (WS) is a recessive disorder characterized by premature senescence. Bloom syndrome (BS) is a recessive disorder characterized by short stature and immunode®ciency. A common characteristic of both syndromes is genomic instability leading to tumorigenesis. WRN and BLM genes causing WS and BS, encode proteins that are closely related to the RecQ helicase. We produced WRN 7/7, BLM 7/7 and WRNmutants in the chicken B-cell line DT40. WRN 7/7 cells showed hypersensitivities to genotoxic agents, such as 4-nitroquinoline 1-oxide, camptothecin and methyl methanesulfonate. They also showed a threefold increase in targeted integration rate of exogenous DNAs, but not in sister chromatid exchange (SCE) frequency. BLM 7/7 cells showed hypersensitivities to the genotoxic agents as well as ultraviolet (UV) light, in addition to a 10-fold increase in targeted integration rate and an 11-fold increase in SCE frequency. In WRN 7/7 /BLM 7/7 cells, synergistically increased hypersensitivities to the genotoxic agents were observed whereas both SCE frequencies and targeted integration rates were partially diminished compared to the single mutants. Chromosomal aberrations were also synergistically increased in WRN 7/7 / BLM 7/7 cells when irradiated with UV light in late S to G 2 phases. These results suggest that both WRN and BLM may be involved in DNA repair in a complementary fashion.

show abstract

Sensitivity of Bloom's syndrome lymphocytes to ethyl methanesulfonate

Cited by 75 publications

References 12 publications

Sources and Structures of Mitotic Crossovers That Arise When BLM Helicase Is Absent inDrosophila

Sources and Structures of Mitotic Crossovers That Arise When BLM Helicase Is Absent inDrosophila

Flow cytometric characterization of the response of Fanconi's anemia cells to mitomycin C treatment

Werner and Bloom helicases are involved in DNA repair in a complementary fashion

Contact Info

Product

Resources

About