Naslov
Forces in bridging fibers segregate chromosomes independently of the attachment to the spindle pole

Autori
Buđa, Renata ; Vukušić, Kruno ; Bosilj, Agneza ; Milas, Ana ; Pavin, Nenad ; Tolić, Iva M.

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, neobjavljeni rad, znanstveni

Skup
EMBO/EMBL Symposium: Microtubules: From atoms to complex systems

Mjesto i datum
Heidelberg, Njemačka, 29.05.2016. - 01.06.2016

Vrsta sudjelovanja
Poster

Vrsta recenzije
Nije recenziran

Ključne riječi
cell division ; anaphase ; bridging fiber ; human cells

Sažetak
During cell division, chromosomes are segregated by a self-organized micromachine made of microtubules and associated proteins, termed mitotic spindle. Currently, chromosome segregation is described by mechanochemical mechanisms including depolymerization of k-fibers at kinetochores (“Pacman”), depolymerization of k-fibers at spindle poles (poleward flux), and sliding of interpolar microtubules in the spindle midzone. Recently, we have characterized a microtubule structure that connects two sister k-fibers and forms antiparallel bundles, termed bridging fiber, as an important part of the spindle in metaphase in human cells (Kajtez et al., Nat Commun 2016). However, the role of the bridging fiber in anaphase remains unknown. Here we show, by using laser ablation to sever one k-fiber in human U2OS cells, that sister kinetochores can segregate without the attachment to the spindle pole while remaining connected to the complex consisting of their k-fibers linked with the bridging fiber. Interestingly, the kinetochores segregated only when the length of the severed k-fiber was above 1.5-2 µm. Photoactivation of tubulin tagged with photoactivatable GFP showed that the minus end of the severed k-fiber is not dynamic. The distance between this minus end and the opposite spindle pole increased during kinetochore separation, indicating that bridging microtubules slide apart. We found that the major contribution to kinetochore movement in detached fibers came from “Pacman” depolymerization and sliding between bridging fibers. Both mechanisms require lateral linkage between sister k-fibers and the bridging fiber to segregate sister kinetochores. Our results demonstrate that the bridging fiber, while linked to k-fibers, segregates chromosomes independently of the attachment to the spindle pole.

Izvorni jezik
Engleski

Znanstvena područja
Biologija

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