title: Localized movement and morphology of UBF1-positive nucleolar regions are changed by γ-irradiation in G2 phase of the cell cycle.
abstract: The nucleolus is a well-organized site of ribosomal gene transcription. Moreover, many DNA repair pathway proteins, including ATM, ATR kinases, MRE11, PARP1 and Ku70/80, localize to the nucleolus (Moore et al., 2011 ). We analyzed the consequences of DNA damage in nucleoli following ultraviolet A (UVA), C (UVC), or γ-irradiation in order to test whether and how radiation-mediated genome injury affects local motion and morphology of nucleoli. Because exposure to radiation sources can induce changes in the pattern of UBF1-positive nucleolar regions, we visualized nucleoli in living cells by GFP-UBF1 expression for subsequent morphological analyses and local motion studies. UVA radiation, but not 5 Gy of γ-rays, induced apoptosis as analyzed by an advanced computational method. In non-apoptotic cells, we observed that γ-radiation caused nucleolar re-positioning over time and changed several morphological parameters, including the size of the nucleolus and the area of individual UBF1-positive foci. Radiation-induced nucleoli re-arrangement was observed particularly in G2 phase of the cell cycle, indicating repair of ribosomal genes in G2 phase and implying that nucleoli are less stable, thus sensitive to radiation, in G2 phase.
authors.affiliation: a Institute of Biophysics ; Academy of Sciences of the Czech Republic ; Brno , Czech Republic.
authors.forename: Dmitry V
authors.initials: DV
authors.lastname: Sorokin
authors.forename: Lenka
authors.initials: L
authors.lastname: Stixová
authors.forename: Petra
authors.initials: P
authors.lastname: Sehnalová
authors.forename: Soňa
authors.initials: S
authors.lastname: Legartová
authors.forename: Jana
authors.initials: J
authors.lastname: Suchánková
authors.forename: Pavel
authors.initials: P
authors.lastname: Šimara
authors.forename: Stanislav
authors.initials: S
authors.lastname: Kozubek
authors.forename: Pavel
authors.initials: P
authors.lastname: Matula
authors.forename: Magdalena
authors.initials: M
authors.lastname: Skalníková
authors.forename: Ivan
authors.initials: I
authors.lastname: Raška
authors.forename: Eva
authors.initials: E
authors.lastname: Bártová
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D002453:Cell Cycle / Q000528:radiation effects*; D002460:Cell Line; D045744:Cell Line, Tumor; D002466:Cell Nucleolus / Q000528:radiation effects; D019295:Computational Biology; D004249:DNA Damage / Q000528:radiation effects; D016195:G2 Phase / Q000528:radiation effects*; D005720:Gamma Rays / Q000009:adverse effects*; D051379:Mice; D035463:Pol1 Transcription Initiation Complex Proteins / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D014466:Ultraviolet Rays
chemical_list: D035463:Pol1 Transcription Initiation Complex Proteins; C063844:transcription factor UBF
keywords: DNA damage; UBF1; live cells; nucleolus; nuncleoli tracking