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Journal ArticleDOI

Normal telomere length and chromosomal end capping in poly(ADP-ribose) polymerase–deficient mice and primary cells despite increased chromosomal instability

TL;DR: The results presented here indicate that PARp-1 does not play a major role in regulating telomere length or in telomeric end capping, and the chromosomal instability of PARP-1−/− primary cells can be explained by the repair defect associated to PARP -1 deficiency.
Abstract: Poly(ADP-ribose) polymerase (PARP)-1, a detector of single-strand breaks, plays a key role in the cellular response to DNA damage. PARP-1-deficient mice are hypersensitive to genotoxic agents and display genomic instability due to a DNA repair defect in the base excision repair pathway. A previous report suggested that PARP-1-deficient mice also had a severe telomeric dysfunction consisting of telomere shortening and increased end-to-end fusions (d'Adda di Fagagna, F., M.P. Hande, W.-M. Tong, P.M. Lansdorp, Z.-Q. Wang, and S.P. Jackson. 1999. NAT: Genet. 23:76-80). In contrast to that, and using a panoply of techniques, including quantitative telomeric (Q)-FISH, we did not find significant differences in telomere length between wild-type and PARP-1(-/)- littermate mice or PARP-1(-/)- primary cells. Similarly, there were no differences in the length of the G-strand overhang. Q-FISH and spectral karyotyping analyses of primary PARP-1(-/)- cells showed a frequency of 2 end-to-end fusions per 100 metaphases, much lower than that described previously (d'Adda di Fagagna et al., 1999). This low frequency of end-to-end fusions in PARP-1(-/)- primary cells is accordant with the absence of severe proliferative defects in PARP-1(-/)- mice. The results presented here indicate that PARP-1 does not play a major role in regulating telomere length or in telomeric end capping, and the chromosomal instability of PARP-1(-/)- primary cells can be explained by the repair defect associated to PARP-1 deficiency. Finally, no interaction between PARP-1 and the telomerase reverse transcriptase subunit, Tert, was found using the two-hybrid assay.

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Citations
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Journal ArticleDOI
TL;DR: The link between telomere maintenance and radiosensitivity is also apparent in mice genetically engineered to have dysfunctional telomeres, and studies using non-mammalian model systems such as C. elegans and yeast point to the link.
Abstract: Several recent studies point to the possibility that telomere maintenance may constitute a potential genetic marker of radiosensitivity. For example, the human diseases ataxia telangiectasia and Nijmegen breakage syndrome, which are characterized by clinical radiosensitivity, show alterations in telomere maintenance. In addition, Fanconi's anemia patients, who are characterized by mild cellular radiosensitivity and in some cases marked clinical radiosensitivity, have altered telomere maintenance. Similarly, a correlation between telomere maintenance and cellular radiosensitivity was reported in a group of breast cancer patients. Another study demonstrated that radiosensitivity may be more pronounced in human fibroblasts with short telomeres than in their counterparts with long telomeres. Several mouse models including mice deficient in Ku, DNA-PKcs (Prkdc), Parp and Atm, all of which are radiosensitive in vivo, show clear telomere alterations. The link between telomere maintenance and radiosensitivity is also apparent in mice genetically engineered to have dysfunctional telomeres. Finally, studies using non-mammalian model systems such as C. elegans and yeast point to the link between radiosensitivity and telomere maintenance. These results warrant further investigation to identify the extent to which these two phenotypes, namely radiosensitivity and telomere maintenance, are linked.

31 citations


Cites background from "Normal telomere length and chromoso..."

  • ...Mice deficient in Parp, a protein involved in the repair of DNA single-strand breaks, showed a strong telomere dysfunction and telomere shortening in one study (16) but a milder telomere dysfunction phenotype in another study (17)....

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Journal ArticleDOI
TL;DR: ParP had a role in telomerase activity through poly(ADP‐ribosyl)ation of TERT and down‐regulation of TEP1/TP1.
Abstract: To test the role of poly(ADP-ribose) polymerase on the telomerase activity, we determined the telomerase activity in leukemic cells K562 treated with benzamide and 4-amino 1,8 naphthalimide (NAP), the inhibitors of PARP. We observed that both the agents inhibited telomerase activity in a dose-dependent manner. The doses of benzamide and NAP that inhibited telomerase activity to 50% of untreated control cells were 10.7 +/- 0.6 mm and 200 +/- 7 microm, respectively. Benzamide treatment (10 mm) inhibited telomerase activity in a time-dependent manner. We also tested the ability of benzamide to inhibit the telomerase activity in Chinese hamster V79 cells and observed similar inhibition of the telomerase activity. Expression of telomerase reverse transcriptase (TERT) and telomerase RNA component, detected by RT-PCR, remained unaltered by treatment with benzamide or NAP. On the contrary, the expression of telomerase associated protein (TEP1/TP1), as detected by RT-PCR and western blot analysis, was reduced by both the agents. Further, in K562 cells, immunoprecipitation with the anti-TERT IgG and probed anti-poly (ADP-ribose) IgG revealed that TERT was poly(ADP-ribosyl)ated in the physiological condition of cell growth and such poly(ADP-ribosyl)ation was inhibited by benzamide treatment. Decrease in TEP1/TP1 expression and poly(ADP-ribosyl)ation of TERT were correlated with the inhibition of PARP activity by benzamide, indicating that PARP had a role in telomerase activity through poly(ADP-ribosyl)ation of TERT and down-regulation of TEP1/TP1.

30 citations

Journal ArticleDOI
TL;DR: The dual roles played by DNA repair proteins are examined, focusing on mammalian cells, and it is hoped this review will serve as a useful gateway to the literature, and will help to frame the major issues in this exciting and rapidly progressing field.
Abstract: How a cell deals with its DNA ends is a question that returns us to the very beginnings of modern telomere biology It is also a question we are still asking today because it is absolutely essential t

30 citations

Journal ArticleDOI
TL;DR: Important accomplishments for patients with genetic diseases, leukemias and lymphomas, mesenchymal tumors and solid cancers, and mouse karyotyping has also contributed to the comprehensive characterization of mouse models of human disease and for gene therapy studies.
Abstract: Spectral karyotyping (SKY) is a widely used methodology to identify genetic aberrations. Multicolor fluorescence in situ hybridization using chromosome painting probes in individual colors for all metaphase chromosomes at once is combined with a unique spectral measurement and analysis system to automatically classify normal and aberrant chromosomes. Based on countless studies and investigations in many laboratories worldwide, numerous new chromosome translocations and other aberrations have been identified in clinical and tumor cytogenetics. Thus, gene identification studies have been facilitated resulting in the dissection of tumor development and progression. For example, different translocation partners of the TEL/ETV6 transcription factor that is specially required for hematopoiesis within the bone marrow were identified. Also, the correct classification of complex karyotypes of solid tumors supports the prognostication of cancer patients. Important accomplishments for patients with genetic diseases, leukemias and lymphomas, mesenchymal tumors and solid cancers are summarized and exemplified. Furthermore, studies of disease mechanisms such as centromeric DNA breakage, DNA double strand break repair, telomere shortening and radiation-induced neoplastic transformation have been accompanied by SKY analyses. Besides the hybridization of human chromosomes, mouse karyotyping has also contributed to the comprehensive characterization of mouse models of human disease and for gene therapy studies.

26 citations


Cites result from "Normal telomere length and chromoso..."

  • ...Using QFISH and SKY analyses Samper et al. (2001) showed that primary Parp1 –/– cells showed a frequency of only two endto-end fusions per 100 metaphases, much lower than that described previously....

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Journal ArticleDOI
25 Feb 2013-PLOS ONE
TL;DR: Evaluating anticancer activities of anthraquinone-derived tricyclic and tetracyclic small molecules and their structure-activity relationships with PARP-1 inhibition in non-small cell lung cancer (NSCLC) and NSCLC-overexpressing Oct4 and Nanog clone shows its cytotoxicity and dose-dependent PARP inhibitory manner emerges as a promising structure for anti-cancer therapy with no significant negative influence on normal cells.
Abstract: Poly (ADP-ribose) polymerase-1 (PARP-1) and telomerase, as well as DNA damage response pathways are targets for anticancer drug development, and specific inhibitors are currently under clinical investigation. The purpose of this work is to evaluate anticancer activities of anthraquinone-derived tricyclic and tetracyclic small molecules and their structure-activity relationships with PARP-1 inhibition in non-small cell lung cancer (NSCLC) and NSCLC-overexpressing Oct4 and Nanog clone, which show high-expression of PARP-1 and more resistance to anticancer drug. We applied our library selected compounds to NCI's 60 human cancer cell-lines (NCI-60) in order to generate systematic profiling data. Based on our analysis, it is hypothesized that these drugs might be, directly and indirectly, target components to induce mitochondrial permeability transition and the release of pro-apoptotic factors as potential anti-NSCLC or PARP inhibitor candidates. Altogether, the most active NSC747854 showed its cytotoxicity and dose-dependent PARP inhibitory manner, thus it emerges as a promising structure for anti-cancer therapy with no significant negative influence on normal cells. Our studies present evidence that telomere maintenance should be taken into consideration in efforts not only to overcome drug resistance, but also to optimize the use of telomere-based therapeutics. These findings will be of great value to facilitate structure-based design of selective PARP inhibitors, in general, and telomerase inhibitors, in particular. Together, the data presented here expand our insight into the PARP inhibitors and support the resource-demanding lead optimization of structurally related small molecules for human cancer therapy.

25 citations

References
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Journal ArticleDOI
16 Dec 1993-Nature
TL;DR: P16 seems to act in a regulatory feedback circuit with CDK4, D-type cyclins and retinoblastoma protein, and inhibits the catalytic activity of theCDK4/cyclin D enzymes.
Abstract: The division cycle of eukaryotic cells is regulated by a family of protein kinases known as the cyclin-dependent kinases (CDKs). The sequential activation of individual members of this family and their consequent phosphorylation of critical substrates promotes orderly progression through the cell cycle. The complexes formed by CDK4 and the D-type cyclins have been strongly implicated in the control of cell proliferation during the G1 phase. CDK4 exists, in part, as a multi-protein complex with a D-type cyclin, proliferating cell nuclear antigen and a protein, p21 (refs 7-9). CDK4 associates separately with a protein of M(r) 16K, particularly in cells lacking a functional retinoblastoma protein. Here we report the isolation of a human p16 complementary DNA and demonstrate that p16 binds to CDK4 and inhibits the catalytic activity of the CDK4/cyclin D enzymes. p16 seems to act in a regulatory feedback circuit with CDK4, D-type cyclins and retinoblastoma protein.

3,716 citations


"Normal telomere length and chromoso..." refers methods in this paper

  • ...As control for the two-hybrid assay we show interaction between the cell cycle proteins CDK4 and p16 as described previously (Table VI; Serrano et al., 1993)....

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Journal ArticleDOI
18 Apr 1991-Nature
TL;DR: The DNA of telomeres—the terminal DNA-protein complexes of chromosomes—differs notably from other DNA sequences in both structure and function, and has been shown to be essential for telomere maintenance and long-term viability.
Abstract: The DNA of telomeres--the terminal DNA-protein complexes of chromosomes--differs notably from other DNA sequences in both structure and function. Recent work has highlighted its remarkable mode of synthesis by the ribonucleoprotein reverse transcriptase, telomerase, as well as its ability to form unusual structures in vitro. Moreover, telomere synthesis by telomerase has been shown to be essential for telomere maintenance and long-term viability.

3,139 citations

Journal ArticleDOI
14 May 1999-Cell
TL;DR: Electron microscopy reported here demonstrated that TRF2 can remodel linear telomeric DNA into large duplex loops (t loops) in vitro, which may provide a general mechanism for the protection and replication of telomeres.

2,413 citations

Journal ArticleDOI
03 Oct 1997-Cell
TL;DR: Results indicate that telomerase is essential for telomere length maintenance but is not required for establishment of cell lines, oncogenic transformation, or tumor formation in mice.

2,066 citations


"Normal telomere length and chromoso..." refers background or methods in this paper

  • ...These Robertsonian fusions are different from those found in late generation telomerase-deficient mice that have critically short telomeres (Blasco et al., 1997)....

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  • ...5 embryos derived from heterozygous crosses as described (Blasco et al., 1997)....

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  • ...Telomeres have an essential role in chromosome stability and are proposed to be biological determinants in the processes of tumorigenesis and aging (for reviews see Blackburn, 1991; Autexier and Greider, 1996; Greider, 1996; Blasco et al., 1997; Lee et al., 1998)....

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  • ...Then the plugs were digested with MboI overnight and run in a pulse field gel electrophoresis as described (Blasco et al., 1997)....

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Journal ArticleDOI
TL;DR: The history and present situation of Spanish language, culture, literature, cuisine, tourism, and more are explored in more detail in this booklet.
Abstract: TELOMERES DEFINED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 579 TELOMERE FUNCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 580 SEQUENCE AND STRUCTURE OF TELOMERES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 581 SOLUTIONS FOR REPLICATION OF DNA TERMINI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 586 STRUCTURE OF SUBTELOMERIC REGIONS.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 589 FORMA TION OF TELOMERES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . . .. 591 PROTEINS THAT INTERACT WITH TELOMERES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 594 ARE TELOMERES REALLY ESSENTIAL? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 597 FUTURE PROSPECTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 598

1,923 citations


"Normal telomere length and chromoso..." refers background in this paper

  • ...Vertebrate telomeres consist of tandem repeats of the sequence TTAGGG (for review see Blackburn, 1991)....

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  • ...Telomeres have an essential role in chromosome stability and are proposed to be biological determinants in the processes of tumorigenesis and aging (for reviews see Blackburn, 1991; Autexier and Greider, 1996; Greider, 1996; Blasco et al., 1997; Lee et al., 1998)....

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