Summary: During cytokinesis, a contractile ring consisting of unbranched filamentous actin (F-actin) and myosin II constricts at the cell equator.Unbranched F-actin is generated by formin, and without formin no cleavage furrow forms.In Caenorhabditis elegans, depletion of septin restores furrow ingression in formin mutants.
How the cleavage furrow ingresses without laufenn 275/55r20 a detectable unbranched F-actin ring is unknown.We report that, in this setting, anillin (ANI-1) forms a meshwork of circumferentially aligned linear structures decorated by non-muscle myosin II (NMY-2).Analysis of ANI-1 deletion mutants reveals that its disordered N-terminal half is required for linear structure formation and sufficient for furrow ingression.
NMY-2 promotes the circumferential alignment of the linear ANI-1 structures and interacts with various lipids, suggesting that NMY-2 links the ANI-1 network with the plasma membrane.Collectively, our data reveal a compensatory mechanism, mediated by ANI-1 linear structures and membrane-bound NMY-2, that wall-e bearbrick promotes furrowing when unbranched F-actin polymerization is compromised.