title: Emergence of micronuclei and their effects on the fate of cells under replication stress.
abstract: The presence of micronuclei in mammalian cells is related to several mutagenetic stresses. In order to understand how micronuclei emerge, behave in cells, and affect cell fate, we performed extensive time-lapse microscopy of HeLa H2B-GFP cells in the presence of hydroxyurea at low concentration. Micronuclei formed after mitosis from lagging chromatids or chromatin bridges between anaphase chromosomes and were stably maintained in the cells for up to one cell cycle. Nuclear buds also formed from chromatin bridges or during interphase. If the micronuclei-bearing cells entered mitosis, they either produced daughter cells without micronuclei or, more frequently, produced cells with additional micronuclei. Low concentrations of hydroxyurea efficiently induced multipolar mitosis, which generated lagging chromatids or chromatin bridges, and also generated multinuclear cells that were tightly linked to apoptosis. We found that the presence of micronuclei is related to apoptosis but not to multipolar mitosis. Furthermore, the structural heterogeneity among micronuclei, with respect to chromatin condensation or the presence of lamin B, derived from the mechanism of micronuclei formation. Our study reinforces the notion that micronucleation has important implications in the genomic plasticity of tumor cells.
authors.affiliation: Graduate School of Biosphere Science, Hiroshima University, Hiroshima, Japan.
authors.forename: Koh-ichi
authors.initials: K
authors.lastname: Utani
authors.forename: Yuka
authors.initials: Y
authors.lastname: Kohno
authors.forename: Atsushi
authors.initials: A
authors.lastname: Okamoto
authors.forename: Noriaki
authors.initials: N
authors.lastname: Shimizu
mesh_terms: D017209:Apoptosis; D006367:HeLa Cells; D006801:Humans; D006918:Hydroxyurea / Q000494:pharmacology; D007700:Kinetics; D048629:Micronuclei, Chromosome-Defective / Q000139:chemically induced*; D008853:Microscopy; D008938:Mitosis; D016296:Mutagenesis; D009369:Neoplasms / Q000473:pathology* / Q000648:ultrastructure; D013997:Time Factors
chemical_list: D006918:Hydroxyurea
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