The bulk of DNA damage caused by ionizing radiation (IR) is generally repaired within hours, yet a subset of DNA lesions may persist even for long periods of time. Such persisting IR-induced foci (pIRIF) co-associate with PML nuclear bodies (PML-NBs) and are among the characteristics of cellular senescence. Here we addressed some fundamental questions concerning the nature and determinants of this co-association, the role of PML-NBs at such sites, and the reason for the persistence of DNA damage in human primary cells. We show that the persistent DNA lesions are devoid of homologous recombination (HR) proteins BRCA1 and Rad51. Our super-resolution microscopy-based analysis showed that PML-NBs are juxtaposed to and partially overlap with the pIRIFs. Notably, depletion of 53BP1 resulted in decreased intersection between PML-NBs and pIRIFs implicating the RNF168-53BP1 pathway in their interaction. To test whether the formation and persistence of IRIFs is PML-dependent and to investigate the role of PML in the context of DNA repair and senescence, we genetically deleted PML in human hTERT-RPE-1 cells. Unexpectedly, upon high-dose IR treatment, cells displayed similar DNA damage signalling, repair dynamics and kinetics of cellular senescence regardless of the presence or absence of PML. In contrast, the PML knock-out cells showed increased sensitivity to low doses of IR and DNA-damaging agents mitomycin C, cisplatin and camptothecin that all cause DNA lesions requiring repair by HR. These results, along with enhanced sensitivity of the PML knock-out cells to DNA-PK and PARP inhibitors implicate PML as a factor contributing to HR-mediated DNA repair.

• Klíčová slova
• Cellular senescence, DNA-PK and PARP/olaparib, Homologous recombination, Ionizing radiation, Super-resolution microscopy,
• MeSH
• 53BP1 metabolismus   MeSH
• genový knockout MeSH
• intranukleární inkluzní tělíska metabolismus   účinky záření   MeSH
• lidé MeSH
• oprava DNA * účinky záření   MeSH
• poškození DNA * MeSH
• protein promyelocytické leukemie nedostatek   genetika   metabolismus   MeSH
• stárnutí buněk genetika   účinky záření   MeSH
• ubikvitinligasy metabolismus   MeSH
• vztah dávky záření a odpovědi MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 53BP1 MeSH
• PML protein, human MeSH Prohlížeč
• protein promyelocytické leukemie MeSH
• RNF168 protein, human MeSH Prohlížeč
• ubikvitinligasy MeSH