Chromosomes in micronuclei are fragmented into small pieces, sometimes catastrophically. Such severely damaged chromosomes can lead to genomic rearrangements, but how the chromosome fragments segregate during mitosis is unknown. Using… Click to show full abstract
Chromosomes in micronuclei are fragmented into small pieces, sometimes catastrophically. Such severely damaged chromosomes can lead to genomic rearrangements, but how the chromosome fragments segregate during mitosis is unknown. Using live-cell imaging to follow micronuclei during mitosis, this study shows that chromosome fragments in micronuclei cluster together during mitosis and segregate into one daughter cell. The authors found that the DNA damage response complex CIP2A-TOPBP1 is responsible for clustering chromosome fragments by binding to the damaged DNA after micronuclei membrane breakdown. This work suggests that biased segregation of chromosome fragments following micronucleation could explain the lack of DNA copy number errors in various cancers.
               
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