February 16, 2012

Dynein is a microtubule motor that resides at the cortex of a cell and can position an entire mitotic spindle. To visualize this, it would help if you were aware of one my killer dance moves…I stand in one spot and reel in a friend with my invisible lasso to dance. And, that friend may or may not have a look of total embarrassment (pity?) on his or her face. While dynein will never beat me in a dance-off, it is a pretty spectacular motor protein. Check out today’s image from a paper describing exactly how dynein can generate pulling forces.

Proper positioning of the mitotic spindle is important for cell division, especially when a cell has to divide asymmetrically to result in two cells of different sizes. Dynein is a microtubule motor that resides at the cortex of a dividing cell and can reel in and position an entire spindle. Cortical dynein functions this way in contexts outside of mitosis too—during migration, for example, dynein may help position the microtubule-nucleating centrosome correctly for trafficking of membrane vesicles. Recently, a group of cell biologists looked at exactly how dynein interacts with microtubules to generate a pulling force, and did so by taking dynein and microtubule asters out of cells and into chambers with microfabricated barriers. In this paper, Laan and colleagues looked at how dynein, attached to the fabricated barriers, interacted with microtubules. By capturing microtubules head-on, dynein regulated microtubule dynamics and length. When the microtubule ends were shrinking, dynein generated a pulling force strong enough to center the microtubule aster in the chamber. Images above show microtubule asters in the microchambers with barriers either coated with dynein or not. Without dynein at the barrier, microtubules continued to grow after reaching the barrier then buckled. With dynein-coated barriers to interact with, microtubules were captured by dynein and stopped growing, mostly remaining straight.

Laan, L., Pavin, N., Husson, J., Romet-Lemonne, G., van Duijn, M., López, M., Vale, R., Jülicher, F., Reck-Peterson, S., & Dogterom, M. (2012). Cortical Dynein Controls Microtubule Dynamics to Generate Pulling Forces that Position Microtubule Asters Cell, 148 (3), 502-514 DOI: 10.1016/j.cell.2012.01.007
Copyright ©2012 Elsevier Ltd. All rights reserved.