title: Nanoscopic exclusion between Rad51 and 53BP1 after ion irradiation in human HeLa cells.
abstract: Many proteins involved in detection, signalling and repair of DNA double-strand breaks (DSB) accumulate in large number in the vicinity of DSB sites, forming so called foci. Emerging evidence suggests that these foci are sub-divided in structural or functional domains. We use stimulated emission depletion (STED) microscopy to investigate localization of mediator protein 53BP1 and recombination factor Rad51 after irradiation of cells with low linear energy transfer (LET) protons or high LET carbon ions. With a resolution better than 100 nm, STED microscopy and image analysis using a newly developed analyzing algorithm, the reduced product of the differences from the mean, allowed us to demonstrate that with both irradiation types Rad51 occupies spherical regions of about 200 nm diameter. These foci locate within larger 53BP1 accumulations in regions of local 53BP1 depletion, similar to what has been described for the localization of Brca1, CtIP and RPA. Furthermore, localization relative to 53BP1 and size of Rad51 foci was not different after irradiation with low and high LET radiation. As expected, 53BP1 foci induced by low LET irradiation mostly contained one Rad51 focal structure, while after high LET irradiation, most foci contained >1 Rad51 accumulation.
authors.affiliation: Angewandte Physik und Messtechnik, Universitaet der Bundeswehr Muenchen, Werner-Heisenberg-Weg 39, D-85577 Neubiberg, Germany.
authors.forename: Judith
authors.initials: J
authors.lastname: Reindl
authors.forename: Guido A
authors.initials: GA
authors.lastname: Drexler
authors.forename: Stefanie
authors.initials: S
authors.lastname: Girst
authors.forename: Christoph
authors.initials: C
authors.lastname: Greubel
authors.forename: Christian
authors.initials: C
authors.lastname: Siebenwirth
authors.forename: Sophie E
authors.initials: SE
authors.lastname: Drexler
authors.forename: Günther
authors.initials: G
authors.lastname: Dollinger
authors.forename: Anna A
authors.initials: AA
authors.lastname: Friedl
mesh_terms: D002244:Carbon / Q000737:chemistry*; D018797:Cell Cycle Proteins / Q000737:chemistry; D053903:DNA Breaks, Double-Stranded / Q000528:radiation effects*; D004260:DNA Repair; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D018499:Linear Energy Transfer; D011522:Protons; D051135:Rad51 Recombinase / Q000737:chemistry*; D000071857:Tumor Suppressor p53-Binding Protein 1
chemical_list: D018797:Cell Cycle Proteins; D047908:Intracellular Signaling Peptides and Proteins; D007477:Ions; D011522:Protons; C498301:TP53BP1 protein, human; D000071857:Tumor Suppressor p53-Binding Protein 1; D002244:Carbon; C495153:RAD51 protein, human; D051135:Rad51 Recombinase