Regensburg 2010 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 9: Physics of Cells I
BP 9.2: Vortrag
Dienstag, 23. März 2010, 10:00–10:15, H43
Centering of dynamic microtubule asters by cortical pulling forces — Liedewij Laan1, •Nenad Pavin2,3, Guillaume Romet-Lemonne1, Frank Julicher2, and Marileen Dogterom1 — 1FOM Institute for Atomic and Molecular Physics (AMOLF), Amsterdam, The Netherlands — 2Max Planck Institute for the Physics of Complex Systems, Dresden, Germany — 3Department of Physics, Faculty of Science, Zagreb, Croatia
Dynamic microtubules (MTs) interact with the cortex to generate pushing and/or pulling forces that position organelles correctly with respect to the confining geometry of living cells. In particular, pulling forces mediated by dynein linked to the cortex, provide a versatile mechanism to properly position MT organizing centers in systems ranging from small yeast cells to large embryonic cells. Nevertheless, the respective roles of pushing and pulling forces, and especially the mechanism by which pulling forces may contribute to centering processes, remain poorly understood. We address this question in an in vitro experiment, where MT asters are grown in microfabricated chambers. Pushing forces arise from MT polymerization and buckling forces, and pulling forces arise from interactions between MT ends and dynein motor proteins attached to the chamber walls. Surprisingly, we find that MT asters center more reliably by a combination of pulling and pushing forces than by pushing forces alone. Our theoretical results obtained for various geometries, imply distinct positioning strategies employed in different cell types.