BIOPHYSICAL THEORY AND MODELING |
Spatial regulation improves anti-parallel microtubule overlap during mitotic spindle assembly
Wilbur E Channels 1, Francois J Nedelec 2, Yixian Zheng 3 and Pablo A. Iglesias 1*
1 Johns Hopkins University
2 EMBL
3 Carnegie Institution and HHMI
* To whom correspondence should be addressed. E-mail: pi{at}jhu.edu.
Submitted on July 23, 2007
Revised on August 24, 2007
Accepted on 30 November 2007
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Abstract |
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The mitotic spindle plays an essential role in chromosome segregation during cell division. Spindle formation and proper function requires that microtubules with opposite polarity overlap and interact. Previous computational simulations have demonstrated that these antiparallel interactions could be created by complexes combining plus and minus end directed motors. The resulting spindles, however, exhibit sparse antiparallel microtubule overlap with motor complexes linking only a nominal number of antiparallel microtubules. Here we investigate the role that spatial differences in the regulation of microtubule interactions can have on spindle morphology. We show that the spatial regulation of microtubule catastrophe parameters can lead to significantly better spindle morphology and spindles with greater antiparallel MT overlap. We also demonstrate that antiparallel microtubule overlap can be increased by having new microtubules nucleated along the length of existing astral microtubules, but this increase negatively affects spindle morphology. Finally, we show that limiting the diffusion of motor complexes within the spindle region increases antiparallel microtubule interaction.
Key Words:
microtubule, mitotic spindle, spatial gradient
