Regensburg 2010 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 26: From Single-Molecule to Tissue Dynamics
BP 26.5: Vortrag
Donnerstag, 25. März 2010, 15:15–15:30, H43
Nuclear centering in fission yeast mediated by kinesin-8 motor proteins — •nicola maghelli1, vladimir krstić2, nenad pavin2, frank jülicher2, and iva tolić-nørrelykke1 — 1MPI-CBG, Dresden, GERMANY — 2MPI-PKS, Dresden, GERMANY
In the fission yeast Schizosaccharomyces pombe, the nucleus is positioned at the cell center. Since the nucleus determines the cell division site, keeping the nucleus at the center is crucial for ensuring symmetrical cell division (1). Microtubules push against the cell ends and exert force on the nucleus (2), but how the cell regulates these forces in order to center the nucleus remains unknown. Here we tackle this problem by using a combination of live cell imaging, cell manipulations by laser ablation and optical tweezers, and a theoretical model. We show that microtubule pushing forces can center the nucleus because of a larger number of contacts between the microtubules and the proximal cell end than the distal one. Moreover, kinesin-8 motors (Klp5/6) increase the rate of microtubule catastrophe (transition from growth to shrinkage) in a microtubule length- and contact time-dependent manner. Thus, the motor behavior results in a longer contact between a microtubule and the proximal than the distal cell end. Taken together, our experimental and theoretical results provide a novel centering mechanism, where kinesin-8 motors increase the efficiency of nuclear centering.
1. I. Tolić-Nørrelykke, L. Sacconi, C. Stringari, I. Raabe, F. S. Pavone, Curr Biol 15, 1212 (Jun 30, 2005).
2. P. T. Tran, L. Marsh, V. Doye, S. Inoue, F. Chang, J Cell Biol 153, 397 (Apr 16, 2001).