title: Cells bearing chromosome aberrations lacking one telomere are selectively blocked at the G2/M checkpoint.
abstract: Cell cycle checkpoints are part of the cellular mechanisms to maintain genomic integrity. After ionizing radiation exposure, the cells can show delay or arrest in their progression through the cell cycle, as well as an activation of the DNA repair machinery in order to reduce the damage. The G2/M checkpoint prevents G2 cells entering mitosis until the DNA damage has been reduced. The present study evaluates which G0 radiation-induced chromosome aberrations are negatively selected in the G2/M checkpoint. For this purpose, peripheral blood samples were irradiated at 1 and 3 Gy of gamma-rays, and lymphocytes were cultured for 48 h. Calyculin-A and Colcemid were used to analyze, in the same slide, cells in G2 and M. Chromosome spreads were consecutively analyzed by solid stain, pancentromeric and pantelomeric FISH and mFISH. The results show that the frequency of incomplete chromosome elements, those lacking a telomeric signal at one end, decreases abruptly from G2 to M. This indicates that cells with incomplete chromosome elements can progress from G0 to G2, but at the G2/M checkpoint suffer a strong negative selection.
authors.affiliation: Unitat de Biologia Cel.lular, Departament de Biologia Cel.lular, Fisiologia i Immunologia, Universitat Autònoma de Barcelona, Bellaterra, Spain.
authors.forename: Pilar
authors.initials: P
authors.lastname: Rodríguez
authors.forename: Joan Francesc
authors.initials: JF
authors.lastname: Barquinero
authors.forename: Assumpta
authors.initials: A
authors.lastname: Duran
authors.forename: María Rosa
authors.initials: MR
authors.lastname: Caballín
authors.forename: Montserrat
authors.initials: M
authors.lastname: Ribas
authors.forename: Leonardo
authors.initials: L
authors.lastname: Barrios
mesh_terms: D000328:Adult; D002453:Cell Cycle; D002869:Chromosome Aberrations; D016195:G2 Phase; D006801:Humans; D008214:Lymphocytes / Q000528:radiation effects*; D008297:Male; D008938:Mitosis; D011839:Radiation, Ionizing; D016615:Telomere