X-Ray Induced DNA Damage and Repair in Germ Cells of PARP1−/− Male Mice

• Main Authors: Eugenia Cordelli, Francesca Pacchierotti, Lorena Paris, Roberto Ranaldi, Patrizia Eleuteri, Anna Maria Fresegna, Paola Villani
• Format: Article
• Language: English
• Published: MDPI AG 2013-09-01
• Series: International Journal of Molecular Sciences
• Subjects: poly(ADP-ribose)polymerase-1; DNA repair; male mouse germ cells; comet assay; H2AX phosphorylation; ionizing radiation
• Online Access: http://www.mdpi.com/1422-0067/14/9/18078

Poly(ADP-ribose)polymerase-1 (PARP1) is a nuclear protein implicated in DNA repair, recombination, replication, and chromatin remodeling. The aim of this study was to evaluate possible differences between PARP1−/− and wild-type mice regarding induction and repair of DNA lesions in irradiated male germ cells. Comet assay was applied to detect DNA damage in testicular cells immediately, and two hours after 4 Gy X-ray irradiation. A similar level of spontaneous and radiation-induced DNA damage was observed in PARP1−/− and wild-type mice. Conversely, two hours after irradiation, a significant level of residual damage was observed in PARP1−/− cells only. This finding was particularly evident in round spermatids. To evaluate if PARP1 had also a role in the dynamics of H2AX phosphorylation in round spermatids, in which γ-H2AX foci had been shown to persist after completion of DNA repair, we carried out a parallel analysis of γ-H2AX foci at 0.5, 2, and 48 h after irradiation in wild-type and PARP1−/− mice. No evidence was obtained of an effect of PARP1 depletion on H2AX phosphorylation induction and removal. Our results suggest that, in round spermatids, under the tested experimental conditions, PARP1 has a role in radiation-induced DNA damage repair rather than in long-term chromatin modifications signaled by phosphorylated H2AX.