Anillin forms linear structures and facilitates furrow ingression after septin and formin depletion

• Published in: bioRxiv
• Main Authors: Lebedev, Mikhail, Fung-Yi, Chan, Bellessem, Jennifer, Osorio, Daniel S, Rackles, Elisabeth, Mikeladze-Dvali, Tamara, Carvalho, Ana X, Zanin, Esther
• Format: Paper
• Language: English
• Published: Cold Spring Harbor Cold Spring Harbor Laboratory Press 22.12.2022
• Subjects: Actin; Contractility; Cytokinesis; Deletion mutant; Filaments; Lipids; Mutants; Myosin; Septin
• DOI: 10.1101/2022.12.22.521621

During cytokinesis a contractile ring consisting of unbranched filamentous actin (F-actin) and myosin II filaments assembles and constricts at the cell equator. Unbranched F-actin is de novo generated by formin and without formin cleavage furrow ingression fails. In C. elegans depletion of septin restores cleavage furrow ingression in formin (CYK-1) mutants. How the cleavage furrow ingresses without a detectable unbranched F-actin ring is not known. We report, that in this setting anillin (ANI-1) is essential for furrow ingression and forms a meshwork of linear structures, which circumferentially align around the cell equator. Although equatorial ANI-1 recruitment is facilitated by septins, the formation of linear ANI-1 structures is septin independent. Analysis of ANI-1 deletion mutants reveals that its disordered linker region is required for linear structure formation and furrow ingression. We also found that myosin II (NMY-2) decorates linear ANI-1 structures and promotes their circumferential alignment. NMY-2 also interacts with various lipids and forms membrane localized clusters in absence of F-actin and anillin binding. This suggests that NMY-2 represents an independent link between the F-actin / ANI-1 network and the plasma membrane. Collectively, our data reveals a compensatory mechanism, mediated by ANI-1 linear structures and membrane-bound NMY-2, that promotes furrow formation and ingression when formins are depleted and therefore unbranched F-actin polymerization is compromised.Competing Interest StatementThe authors have declared no competing interest.