Biophysics

Microtubules search for lost kinetochores by pivoting around half of the dividing spindle

June 5, 2011.

Lecturer

Assistant Professor NENAD PAVIN, PhD
Department of Physics, Faculty of Science, University of Zagreb*

Date and time

Thursday, June 9, 2011, at 3:00 PM

Location

Lecture hall in the Mladen Paić building, Institute of Physics, Bijenička cesta 46, Zagreb

Abstract

In living cells, the correct distribution of genetic material between two daughter cells is possible if all chromosomes are attached to the division spindle by microtubules. The link between microtubules and chromosomes are kinetochores, protein complexes located on chromosomes. In yeast cells, kinetochores are located on the centrosome, which facilitates their attachment to microtubules growing from the centrosome. If the division spindle breaks down, it has the ability to re-form itself, which involves capturing lost kinetochores that are now lost somewhere inside the nucleus, but far from the centrosome. However, the mechanism by which microtubules find these lost kinetochores is unknown. We found that lost kinetochores are captured by microtubules that perform random angular motion. By recording events inside a living cell, we observed that astral microtubules pivot around the centrosome in cells with lost kinetochores, as well as in cells without lost kinetochores. We also found that the kinetochore performs a random motion by which it traverses a portion of the space comparable to the space traversed by the microtubule. Finally, by introducing a stochastic model, we showed that the process of kinetochore capture can be explained by the measured random movement of astral microtubules and kinetochore. It will be interesting to see to what extent microtubule pivoting helps in targeting in different situations in living cells.

*Joint seminar of the Institute of Physics, Department of Physics, Faculty of Science and the Croatian Biophysical Society
IF seminar leaders: Vlasta Horvatić and Ivica Živković
Seminar leader of the Faculty of Medicine: Hrvoje Buljan

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