Naslov
Peripheral location in early mitotic spindles predisposes chromosomes to persistent monoorientation and risk of mis-segregation

Autori
Dundović, Iva ; Koprivec, Isabella ; Štimac, Valentina ; Risteski, Patrik ; Kodba, Snježana ; Vukušić, Kruno ; Tolić, Iva

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Skup
The Consequences of Aneuploidy Conference: Honoring the Contributions of Angelika Amon

Mjesto i datum
Southbridge, SAD, 11.09.2022. - 16.09.2022

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Podatak o recenziji nije dostupan

Ključne riječi
Cancer ; Segregation errors ; Mitotic fidelity ; Chromosome position

Sažetak
Background: During prometaphase all chromosomes must congress to the metaphase plate in order to satisfy the spindle assembly checkpoint (SAC) and initiate correct chromosome segregation. Contrary to healthy cells, human cancer cells often start mitosis via prometaphase pathway - without fully separating their centrosomes. This initial centrosome distance is believed to be an important determinant of chromosome segregation fidelity, as this pathway likely promotes the generation of syntelic attachments. However, the importance of chromosome position relative to centrosomes remains unknown. Aims: We set out to elucidate how chromosome positions relative to the position of centrosomes predict their speed of alignment and likelihood of mis-segregation. Methods: Using live-cell imaging and kinetochore tracking in three cellular systems with distinct fractions of peripherally positioned chromosomes at the onset of mitosis, we explore the paths of chromosome congression and the outcomes of their segregation. Results: We show that non-transformed RPE1 cells start mitosis with only a small fraction of polar chromosomes that are more prone to mis-segregate than non-polar chromosomes when SAC is weakened. Meanwhile, in the U2OS cancer cell line the fraction of polar chromosomes is higher, and they are prone to late alignment that predisposes them to mis-segregation. As the third system we use monastrol washout in RPE1 cells to increase the fraction of polar chromosomes before the spindle elongation, and we demonstrate that this leads to an increase in the proportion of late-aligning chromosomes after the washout, mimicking U2OS cells. By tracking congression of kinetochores during bipolarization, we notice that polar chromosomes take substantially longer to align to the metaphase plate, inducing long mitotic delays when compared to non-treated RPE1 cells. Interestingly, the majority of non-polar chromosomes reach the metaphase plate before spindle elongation is completed, contrary to polar chromosomes, which are often detained in the region between the pole and the emerging metaphase plate. The increase in the number of segregation errors following monastrol washout could not be rescued by depolymerizing all microtubules with additional nocodazole treatment to remove preformed syntelic attachments before the final washout and bipolarization. Moreover, in monopole, the angles of kinetochore pairs toward their respective poles that suggest syntelic orientation, cannot predict their future late alignment. These two results imply that formation of syntelic attachments that takes place in the monopole is not the primary cause of late alignment and segregation errors. Conclusions: We propose that unfavorable position of chromosomes behind the spindle pole at the start of spindle elongation increases the likelihood of their mis-segregation and that syntelic monooriented intermediates form during their delayed congression.

Izvorni jezik
Engleski

Znanstvena područja
Biologija

POVEZANOST RADA