Nuclear chromosome locations dictate segregation error frequencies

Chromosome segregation errors during cell divisions generate aneuploidies and micronuclei, which can undergo extensive chromosomal rearrangements such as chromothripsis. Selective pressures then shape distinct aneuploidy and rearrangement patterns, for example in cancer, but it is unknown if initial biases in segregation errors and micronucleation for particular chromosomes exist. Using single-cell DNA sequencing after an error-prone mitosis in untransformed, diploid cell lines and organoids, we here show that chromosomes have different segregation error frequencies that result in non-random aneuploidy landscapes. Isolation and sequencing of single micronuclei from these cells showed that chromosomes missegregating frequently also preferentially become entrapped in micronuclei. A similar bias was found in naturally occurring micronuclei of two cancer cell lines. We find that segregation error frequencies of individual chromosomes correlate with their location in the interphase nucleus, and show that this is highest for peripheral chromosomes behind spindle poles. Randomization of chromosome positions, Cas9-mediated live tracking and forced repositioning of individual chromosomes showed that a greater distance from the nuclear center directly increases the propensity to missegregate. Accordingly, chromothripsis in cancer genomes and aneuploidies in early development1occur more frequently for larger chromosomes, which are preferentially located near the nuclear periphery. Our findings reveal a direct link between nuclear chromosome positions, segregation error frequencies, and micronucleus content, with implications for our understanding of tumor genome evolution and the origins of specific aneuploidies during development.