Molecular machines push and pull cells in shape
Researchers from the FOM Institute AMOLF have discovered together with colleagues from the Vrije Universiteit how molecular machines work in unison to change the shape of biological cells. Their findings will be published in the early online edition of the Proceedings of the National Academy of Sciences (PNAS) of this week.
Biological cells undergo drastic changes in shape when they migrate or divide. They rely for these shape changes on tiny molecular machines, which contract a skeleton of protein fibers inside the cell. It is a long-standing puzzle how the molecular machines actually coordinate to achieve directed contraction.
While each molecular motor by itself pushes on a protein fiber in one direction only, the cell contains a woven network of many fibers pointing in random directions. Thus the motors pull and push on the network in equal amounts. Marina Soares e Silva and her colleagues have been able to show that the random actions of the motors result in coordinated contraction, because the protein fibers respond differently to pushing than to pulling.
The network of protein fibers is essentially similar to a fishnet. The fibers strongly resist stretching by the motors, but they cannot support any compressive load since they will immediately buckle. This asymmetry leads to a coordinated contraction of the fiber network by the motors, even when the network starts out with a random configuration of fibers. This mechanical effect helps to explain how living cells use molecular motors to change their shape. An important step in the understanding of fundamental life processes like cell division and embryonic development.
Reference
'Active multistage coarsening of actin networks driven by myosin motors'
M. Soares e Silva, M. Depken, B. Stuhrmann, M. Korsten, F.C. MacKintosh, G.H. Koenderink, Proceedings of the National Academy of Sciences USA
For more information please contact Gijsje Koenderink