Non-Random Mis-Segregation of Human Chromosomes

Abstract

Summary: Recurrent patterns of chromosomal changes (aneuploidy) are widespread in cancer. These patterns are mainly attributed to selection processes due to an assumption that human chromosomes carry equal chance of being mis-segregated into daughter cells when fidelity of cell division is compromised. Human chromosomes vary widely in size, gene density and other parameters that might generate bias in mis-segregation rates, however technological limitations have precluded a systematic and high throughput analysis of chromosome-specific aneuploidy. Here, using fluorescence In-Situ hybridization (FISH) imaging of specific centromeres coupled with high-throughput single cell analysis, as well as single-cell sequencing we show that human chromosome mis-segregation is non-random.Merotelic kinetochore attachment induced by nocodazole washout leads to elevated aneuploidy of a subset of chromosomes, and high rates of anaphase lagging of chromosomes 1 and 2. Mechanistically, we show that these chromosomes are prone to cohesion fatigue that results in anaphase lagging upon release from nocodazole or Eg5 inhibition. Our findings suggest that inherent properties of specific chromosomes can influence chromosome mis-segregation and aneuploidy, with implications for studies on aneuploidy in human disease.

Micronucleus formation in human cancer cells is biased by chromosome size

“…The findings by Drpic et al and Worrall and coworkers are fully in tune with our NCH149 data, which show a significantly increased rate of large chromosomes sequestered into micronuclei in human cancer cells. Mechanistically, both cohesion fatigue and chromosome lagging related to kinetochore size might contribute.…”

“…This effect was further increased when erroneous attachments were enhanced by monastrol treatment . Similarly, it has most recently been shown that the largest chromosomes 1 and 2 are particularly prone to missegregation in human retinal pigment epithelium cells (RPE1) following mitotic spindle disruption by release from a nocodazole‐mediated mitotic arrest . In this study, chromosomes 1 and 2 together made up for more than one‐third of anaphase lagging chromosomes as a consequence of cohesion fatigue, a gradual failure of the cohesive forces holding sister chromatids together, leading to premature sister chromatid separation.…”

“…Mechanistically, both cohesion fatigue and chromosome lagging related to kinetochore size might contribute. In order to address the underlying mechanisms, we performed nocodazole release experiments as described by Worrall and coworkers, using centromeric FISH probes against chromosomes 2 and 17. In these experiments, 16.5% of anaphases and telophases showed lagging chromosomes without skewing toward the larger chromosome 2.…”

“…In nocodazole release experiments as described by Worrall and coworkers, 16 hours of 100 ng/mL nocodazole followed by 2 hours of release were determined as the setting to obtain most mitotic cells by time‐lapse experiments and were subsequently used for hybridization with centromeric FISH probes against chromosomes 2 and 17.…”

Human chromosome‐specific aneuploidy is influenced by DNA ‐dependent centromeric features

“…Interestingly, in the RPE-1 cell line, chromosome 1, that carries a large centromere, tends to lag (likely due to merotelic attachment) at a higher frequency than chromosomes with a smaller centromere, such as chromosome 3, even in unperturbed conditions (Fig 2E and data not shown). Accordingly, chromosome 1 was recently found to be lost at higher frequency compared to others following nocodazole release (Worrall et al, 2018), a treatment known to promote merotelic attachment (Crasta et al, 2012). This suggests that stronger centromeres, as the ones from chromosome 1, are less affected in conditions that compromise centromere function, but more vulnerable to incorrect attachment.…”