Normal telomere length and chromosomal end capping in poly(ADP-ribose) polymerase-deficient mice and primary cells despite increased chromosomal instability.
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.
Samper
E
E
Department of Immunology and Oncology, Centro Nacional de Biotecnología-CSIC, Campus Cantoblanco, E-28049 Madrid, Spain.
Goytisolo
F A
FA
Ménissier-de Murcia
J
J
González-Suárez
E
E
Cigudosa
J C
JC
de Murcia
G
G
Blasco
M A
MA
D000818:Animals; D001854:Bone Marrow Cells / Q000378:metabolism; D002455:Cell Division; D002478:Cells, Cultured; D002875:Chromosomes / Q000737:chemistry* / Q000648:ultrastructure*; D018076:DNA, Complementary / Q000378:metabolism; D004268:DNA-Binding Proteins; D005838:Genotype; D006579:Heterozygote; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D051379:Mice; D008822:Mice, Transgenic; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics* / Q000502:physiology; D012313:RNA; D013154:Spleen / Q000166:cytology; D019098:Telomerase / Q000378:metabolism; D016615:Telomere / Q000737:chemistry* / Q000648:ultrastructure*; D020798:Two-Hybrid System Techniques
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; C422952:telomerase RNA; D012313:RNA; D011065:Poly(ADP-ribose) Polymerases; D019098:Telomerase; C509187:Tert protein, mouse