Kinetochore life histories reveal the origins of chromosome mis-segregation and correction mechanisms

Abstract

Chromosome mis-segregation during mitosis leads to daughter cells with deviant karyotypes (aneuploidy) and an increased mutational burden through chromothripsis of mis-segregated chromosomes. The rate of mis-segregation and the aneuploidy state are hallmarks of cancer and linked to cancer genome evolution. Errors can manifest as lagging chromosomes in anaphase, although the mechanistic origins and likelihood of correction are incompletely understood. Here we combine lattice light sheet microscopy, endogenous protein labelling and computational analysis to define the life history of >10^4 kinetochores throughout metaphase and anaphase from over 200 cells. By defining the laziness of kinetochores in anaphase, we reveal that chromosomes are at a considerable and continual risk of mis-segregation. We show that the majority of kinetochores are corrected rapidly in early anaphase through an Aurora B dependent process. Moreover, quantitative analyses of the kinetochore life histories reveal a unique dynamic signature of metaphase kinetochore oscillations that forecasts their fate in the subsequent anaphase. We propose that in diploid human cells chromosome segregation is fundamentally error prone, with a new layer of early anaphase error correction required for stable karyotype propagation.

Micronuclei from misaligned chromosomes that satisfy the spindle assembly checkpoint in cancer cells

“… 43 , 56 , 57 , 58 , 59 We now show that although most micronuclei derive from anaphase lagging chromosomes, simply because these events occur at a very high frequency in chromosomally unstable cancer cells, 54 misaligned chromosomes that satisfy the SAC often directly missegregate (without lagging behind in anaphase) and have the highest probability to form micronuclei, specifically in human cancer cell models (see graphical abstract). This is consistent with recent high-resolution live-cell studies in both cancer and non-cancer human cells that showed that the vast majority of lagging chromosomes have a transient nature and are corrected during anaphase by an Aurora-B-dependent mechanism that prevents micronuclei formation, 46 , 60 and the relatively low frequency of micronuclei formation even after induction of massive chromosome segregation errors by experimental abrogation of the SAC. 61 , 62 …”

Misaligned chromosomes that satisfy the spindle assembly checkpoint are a strong predictor of micronuclei formation in dividing cancer cells

“…We now show that although most micronuclei derive from anaphase lagging chromosomes, simply because these events occur at a very high frequency in chromosomally unstable cancer cells 55 , chronically misaligned chromosomes that satisfy the SAC often missegregate and have the highest probability to form micronuclei, specifically in human cancer cell models (see graphical abstract). This is consistent with recent high-resolution live-cell studies in both cancer and non-cancer human cells that showed that the vast majority of lagging chromosomes have a transient nature and are corrected during anaphase by an Aurora B-dependent mechanism that prevents micronuclei formation 48, 61 .…”

Microtubule-based mitotic spindles contain a micron-sized mixed-nucleotide zone

“…To precisely define the relationship between HURP-gaps and kinetochore motion we used lattice-light sheet microscopy and kinetochore tracking to acquire and analyse 3D volumes of hTERT-RPE1 EGFP-HURP/Halo-CENP-A cells every 4.5 s (Movie 4) (17). As metaphase sister-kinetochores oscillated back-and-forth with K-fibres switching from growth to shrinkage, we found that HURP was exclusively present on depolymerizing K-fibres (associated to the leading kinetochore sister), and never on the growing K-fibre (associated to the trailing kinetochore sister) (Fig.…”