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bioRxiv · 10.1101/333286

Flow-independent accumulation of motor-competent non-muscle myosin II in the contractile ring is essential for cytokinesis

Osorio, D. S.·Chan, F. Y.·Saramago, J.·Leite, J.·Silva, A. M.·Sobral, A. F.·Gassmann, R.·Xavier Carvalho, A.
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Abstract

Cytokinesis in animal cells requires the assembly of a contractile actomyosin ring, whose subsequent constriction physically separates the two daughter cells. Non-muscle myosin II (myosin) is essential for cytokinesis, but the role of its motor activity remains poorly defined. Here, we examine cytokinesis in C. elegans one-cell embryos expressing myosin motor mutants generated by genome editing. Motor-dead myosin, which is capable of binding F-actin, does not support cytokinesis, and embryos co-expressing motor-dead and wild-type myosin are delayed in cytokinesis. Partially motor-impaired myosin also delays cytokinesis and renders contractile rings more sensitive to reduced myosin levels. Thus, myosin motor activity, rather than its ability to cross-link actin filaments, drives contractile ring assembly and constriction. We further demonstrate that myosin motor activity is required for long-range cortical actin flows, but that flows per se play a minor role in contractile ring assembly. Our results suggest that flow-independent recruitment of motor-competent myosin to the cell equator is both essential and rate-limiting for cytokinesis.

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Osorio, D. S., Chan, F. Y., Saramago, J., Leite, J., Silva, A. M., Sobral, A. F., Gassmann, R., Xavier Carvalho, A.. 2018-05-31. Flow-independent accumulation of motor-competent non-muscle myosin II in the contractile ring is essential for cytokinesis. https://doi.org/10.1101/333286

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