Assembly of the contractile ring for cytokinesis

Cytokinesis is the final step in cell division when a dividing cell physically separates into two. During cytokinesis, animals and fungi assemble a contractile ring containing actin filaments and the motor protein myosin to separate into two daughter cells. Despite huge progress in identifying most major protein components, many aspects of the physical mechanism of contractile ring assembly and constriction remain unclear. To better understand this process, we are developing models of ring self-organization, in collaboration with experimentalists.

In fission yeast, membrane-bound nodes containing myosin are broadly distributed around the cell equator. They assemble into a contractile ring through stochastic motions, after a meshwork of dynamic actin filaments appears. Analysis of node motions and numerical simulations supported a "search, capture, pull and release" mechanism whereby transient connections are established when myosins in one node capture and exert force on actin filaments growing from other nodes.




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