The dynamics of centromere motion through the metaphase-to-anaphase transition reveal a centromere separation order

Abstract

During cell division, chromosomes align at the equator of the cell before sister chromatids separate to move to each daughter cell during anaphase. We use high-speed imaging, Bayesian modelling and quantitative analysis to examine the regulation of centromere dynamics through the metaphase-toanaphase transition. We find that, contrary to the apparent instantaneous separation seen in lowfrequency imaging, centromeres separate asynchronously over 1-2 minutes. The timing of separations negatively correlates with the centromere intersister distance during metaphase, which could potentially be explained by variable amounts of cohesion at centromeres. Depletion of condensin I increases this asynchrony. Depletion of condensin II, on the other hand, abolishes centromere metaphase oscillations and impairs centromere speed in anaphase. These results suggest that condensin complexes have broader direct roles in mitotic chromosome dynamics than previously believed and may be crucial for the regulation of chromosome segregation.

Kinetochore life histories reveal an Aurora-B-dependent error correction mechanism in anaphase

“…Estimates of anaphase onset times for the kinetochore pairs are shown in Figure 1F for the example cell displayed throughout Figure 1. The asynchrony in anaphase onset times between different sister pairs, as assessed by the median absolute deviation (a measure of spread similar to standard deviation but robust to outliers), was 16 ± 6 s for all cells (N = 153 cells; DMSO, 2 h noc, 4 h noc pooled), consistent with earlier observations (Armond et al, 2019). Lagging chromosomes then manifest as a kinetochore that is delayed in segregating, or fails to segregate at all, compared with the two clusters of kinetochores that are moving toward opposite spindle poles (e.g., Figure 2A).…”

“…All of the imaged cells entered anaphase, indicating an appropriate imaging setup for studying mitosis. Furthermore, population level analysis of kinetochore trajectories in metaphase confirms that sister kinetochore pairs underwent heterogeneous oscillatory motion with a half period of $40 s as previously described (Figures 1C-1E and S2A) (Armond et al, 2019;Dudka et al, 2019). This lattice light-sheet imaging and analysis pipeline thus captures dynamics of kinetochores at high temporal resolution from late prometaphase to late anaphase.…”

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

“…1a. The asynchrony in anaphase onset times between different sister pairs, as assessed by the median absolute deviation (a measure of spread similar to standard deviation but robust to outliers), was 16±6 s for all cells ( N = 153 cells; DMSO, 2h noc, 4h noc pooled), consistent with earlier observations 51 . Lagging chromosomes then manifest as a kinetochore that is delayed in segregating, or fails to segregate at all, compared to the two clusters of kinetochores that are moving towards opposite spindle poles (e.g.…”

“…1a. The asynchrony in anaphase onset times between different sister pairs, as assessed by the median absolute deviation (a measure of spread similar to standard deviation but robust to outliers), was 16±6 s for all cells (N = 153 cells; DMSO, 2h noc, 4h noc pooled), consistent with earlier observations 51 . Lagging chromosomes then…”

“…Fig. 2a) 51,52 . This lattice light sheet imaging and analysis pipeline thus capture dynamics of kinetochores at high temporal resolution from late prometaphase to late anaphase.…”