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

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 cytok...

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Published inbioRxiv
Main Authors Daniel Sampaio Osorio, Fung Yi Chan, Saramago, Joana, Leite, Joana, Silva, Ana Marta, Sobral, Ana Filipa, Gassmann, Reto, Carvalho, Ana Xavier
Format Paper
LanguageEnglish
Published Cold Spring Harbor Cold Spring Harbor Laboratory Press 31.05.2018
Subjects
Actin
Actomyosin
Cytokinesis
Embryos
Filaments
Genomes
Motor activity
Muscle contraction
Myosin
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Summary: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.
DOI:10.1101/333286