End-on microtubule-dynein interactions and pulling-based positioning of microtubule organizing centers
Volume 11, Issue 20
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October 15, 2012
Pages 3750 - 3757http://dx.doi.org/10.4161/cc.21753
: GUVs, aster, centering, centrosome, cytoskeleton, dynein, emulsion droplets, microfabricated chambers, microtubules, molecular motors, positioning, pulling, pushing, slipping
Authors: Liedewij Laan, Sophie Roth and Marileen Dogterom View affiliations
During important cellular processes such as centrosome and spindle positioning, dynein at the cortex interacts with dynamic microtubules in an apparent “end-on” fashion. It is well-established that dynein can generate forces by moving laterally along the microtubule lattice, but much less is known about dynein’s interaction with dynamic microtubule ends. In this paper, we review recent in vitro experiments that show that dynein, attached to an artificial cortex, is able to capture microtubule ends, regulate microtubule dynamics and mediate the generation of pulling forces on shrinking microtubules. We further review existing ideas on the involvement of dynein-mediated cortical pulling forces in the positioning of microtubule organizing centers such as centrosomes. Recent in vitro experiments have demonstrated that cortical pulling forces in combination with pushing forces can lead to reliable centering of microtubule asters in quasi two-dimensional microfabricated chambers. In these experiments, pushing leads to slipping of microtubule ends along the chamber boundaries, resulting in an anisotropic distribution of cortical microtubule contacts that favors centering, once pulling force generators become engaged. This effect is predicted to be strongly geometry-dependent, and we therefore finally discuss ongoing efforts to repeat these experiments in three-dimensional, spherical and deformable geometries.
Received: July 30, 2012; Accepted: August 7, 2012; Published Online: August 16, 2012
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