Dynamic PML protein nucleolar associations with persistent DNA damage lesions in response to nucleolar stress and senescence-inducing stimuli

• Published in: Aging (Albany, NY.) Vol. 11; no. 17; pp. 7206 - 7235
• Main Authors: Imrichova, Terezie, Hubackova, Sona, Kucerova, Alena, Kosla, Jan, Bartek, Jiri, Hodny, Zdenek, Vasicova, Pavla
• Format: Journal Article
• Language: English
• Published: United States Impact Journals 07.09.2019
• Subjects: Medicin och hälsovetenskap; Research Paper; time-lapse imaging; rDNA loci; nucleolar segregation; DNA damage; super-resolution microscopy
• ISSN: 1945-4589; 1945-4589
• DOI: 10.18632/aging.102248

Diverse stress insults trigger interactions of PML with nucleolus, however, the function of these PML nucleolar associations (PNAs) remains unclear. Here we show that during induction of DNA damage-induced senescence in human non-cancerous cells, PML accumulates at the nucleolar periphery simultaneously with inactivation of RNA polymerase I (RNAP I) and nucleolar segregation. Using time-lapse and high-resolution microscopy, we followed the genesis, structural transitions and destiny of PNAs to show that: 1) the dynamic structural changes of the PML-nucleolar interaction are tightly associated with inactivation and reactivation of RNAP I-mediated transcription, respectively; 2) the PML-nucleolar compartment develops sequentially under stress and, upon stress termination, it culminates in either of two fates: disappearance or persistence; 3) all PNAs stages can associate with DNA damage markers; 4) the persistent, commonly long-lasting PML multi-protein nucleolar structures (PML-NDS) associate with markers of DNA damage, indicating a role of PNAs in persistent DNA damage response characteristic for senescent cells. Given the emerging evidence implicating PML in homologous recombination-directed DNA repair, we propose that PNAs contribute to sequestration and faithful repair of the highly unstable ribosomal DNA repeats, a fundamental process to maintain a precise balance between DNA repair mechanisms, with implications for genomic integrity and aging.