title: Promyelocytic leukemia nuclear bodies are predetermined processing sites for damaged DNA.
abstract: The promyelocytic leukemia protein (PML) participates in several cellular functions, including transcriptional regulation, apoptosis and maintenance of genomic stability. A key feature of this protein is its ability to induce the assembly of nuclear compartments termed PML-nuclear bodies (PML-NBs). Here we show that these nuclear structures recruit single-stranded DNA (ssDNA) molecules in response to exogenous DNA damage. ssDNA was readily detected in PML-NBs within 1 hour following exposure of cells to UV light. Confocal real-time imaging of cells expressing YFP-tagged PML did not reveal de novo formation of new PML-NBs following UV-irradiation, which shows that ssDNA focus formation occurred within pre-existing PML-NBs. Moreover, siRNA-mediated depletion of PML prevented ssDNA focus formation and sensitized cells to UV-induced apoptosis. PML-dependent ssDNA focus formation was found to be particularly efficient during S-phase of the cell cycle, and PML-depleted cells became retarded in S-phase upon growth in the presence of etoposide. In addition, we found that caffeine and the poly(ADP-ribose) polymerase (PARP) inhibitor NU1027 enhanced UV-induced recruitment of ssDNA to PML-NBs. Together, our results show that PML-NBs have the capacity to accommodate DNA metabolic activities that are associated with processing of damaged DNA.
authors.affiliation: Section of Oncology, Department of Medicine, Haukeland University Hospital, Bergen, Norway. stig.boe@vir.uib.no
authors.forename: Stig Ove
authors.initials: SO
authors.lastname: Bøe
authors.forename: Marte
authors.initials: M
authors.lastname: Haave
authors.forename: Asne
authors.initials: A
authors.lastname: Jul-Larsen
authors.forename: Amra
authors.initials: A
authors.lastname: Grudic
authors.forename: Rolf
authors.initials: R
authors.lastname: Bjerkvig
authors.forename: Per Eystein
authors.initials: PE
authors.lastname: Lønning
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D002110:Caffeine / Q000494:pharmacology; D022003:Cell Nucleus Structures / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D000697:Central Nervous System Stimulants / Q000494:pharmacology; D004249:DNA Damage / Q000187:drug effects / Q000528:radiation effects*; D004260:DNA Repair; D004273:DNA, Neoplasm / Q000235:genetics / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000235:genetics / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D006801:Humans; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000071156:Promyelocytic Leukemia Protein; D034741:RNA, Small Interfering / Q000494:pharmacology; D016196:S Phase / Q000187:drug effects / Q000528:radiation effects; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D014466:Ultraviolet Rays; D014471:Umbilical Veins / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D016335:Zinc Fingers
chemical_list: D000697:Central Nervous System Stimulants; D004273:DNA, Neoplasm; D004277:DNA, Single-Stranded; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D000071156:Promyelocytic Leukemia Protein; D034741:RNA, Small Interfering; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; C070576:PML protein, human; D002110:Caffeine