title: A centrosome-autonomous signal that involves centriole disengagement permits centrosome duplication in G2 phase after DNA damage.
abstract: DNA damage can induce centrosome overduplication in a manner that requires G2-to-M checkpoint function, suggesting that genotoxic stress can decouple the centrosome and chromosome cycles. How this happens is unclear. Using live-cell imaging of cells that express fluorescently tagged NEDD1/GCP-WD and proliferating cell nuclear antigen, we found that ionizing radiation (IR)-induced centrosome amplification can occur outside S phase. Analysis of synchronized populations showed that significantly more centrosome amplification occurred after irradiation of G2-enriched populations compared with G1-enriched or asynchronous cells, consistent with G2 phase centrosome amplification. Irradiated and control populations of G2 cells were then fused to test whether centrosome overduplication is allowed through a diffusible stimulatory signal, or the loss of a duplication-inhibiting signal. Irradiated G2/irradiated G2 cell fusions showed significantly higher centrosome amplification levels than irradiated G2/unirradiated G2 fusions. Chicken-human cell fusions demonstrated that centrosome amplification was limited to the irradiated partner. Our finding that only the irradiated centrosome can duplicate supports a model where a centrosome-autonomous inhibitory signal is lost upon irradiation of G2 cells. We observed centriole disengagement after irradiation. Although overexpression of dominant-negative securin did not affect IR-induced centrosome amplification, Plk1 inhibition reduced radiation-induced amplification. Together, our data support centriole disengagement as a licensing signal for DNA damage-induced centrosome amplification.
authors.affiliation: Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland.
authors.forename: Burcu
authors.initials: B
authors.lastname: Inanç
authors.forename: Helen
authors.initials: H
authors.lastname: Dodson
authors.forename: Ciaran G
authors.initials: CG
authors.lastname: Morrison
mesh_terms: D000818:Animals; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D002502:Centrioles / Q000378:metabolism / Q000528:radiation effects; D018385:Centrosome / Q000378:metabolism* / Q000528:radiation effects; D004249:DNA Damage; D016195:G2 Phase / Q000502:physiology*; D006801:Humans; D015151:Immunoblotting; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D018809:Proliferating Cell Nuclear Antigen / Q000235:genetics / Q000378:metabolism; D016196:S Phase / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*; D013997:Time Factors
chemical_list: C472752:CETN2 protein, human; D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins; D008164:Luminescent Proteins; D008869:Microtubule-Associated Proteins; C509189:NEDD1 protein, human; D018809:Proliferating Cell Nuclear Antigen