Anillin propels myosin-independent constriction of actin rings

Abstract

Constriction of the cytokinetic ring, a circular structure of actin filaments, is an essential step during cell division. Mechanical forces driving the constriction are attributed to myosin motor proteins, which slide actin filaments along each other. However, in multiple organisms, ring constriction has been reported to be myosin independent. How actin rings constrict in the absence of motor activity remains unclear. Here, we demonstrate that anillin, a non­motor actin crosslinker, indispensable during cytokinesis, autonomously propels the contractility of actin bundles. Anillin generates contractile forces of tens of pico-Newtons to maximise the lengths of overlaps between bundled actin filaments. The contractility is enhanced by actin disassembly. When multiple actin filaments are arranged into a ring, this contractility leads to ring constriction. Our results indicate that passive actin crosslinkers can substitute for the activity of molecular motors to generate contractile forces in a variety of actin networks, including the cytokinetic ring.

Wrangling Actin Assemblies: Actin Ring Dynamics during Cell Wound Repair

“…Their roles in actin ring translocation are highlighted by their persistent expression at the wound edge. Other actin binding proteins have also been demonstrated to be vital during actin ring translocation such as the actin-associated proteins α-actinin, cofilin, and anillin [ 60 , 79 ]. These known contributors can affect wound repair by facilitating dynamic actin ring organization and thus the ability for the actin ring to efficiently translocate.…”

Pulmonary Mesenchymal Stem Cells in Mild Cases of COVID-19 Are Dedicated to Proliferation; In Severe Cases, They Control Inflammation, Make Cell Dispersion, and Tissue Regeneration

“…Moreover, some key genes involved in cytokinesis were upregulated, which is the separation of chromosomes and cytoplasm, yielding two daughter cells ( 59 ). These genes were ANLN (anillin) ( 60 ) and some kinesins ( KIF21A , KIF2C , and KIF4A ) ( 61 ) ( Figure 1 ). Other upregulated genes control the cell cycle progression, which were FAM111B , PCNA , SMC4 , and ESCO2 ( 62 – 65 ), or multiple cell division checkpoints, as ATAD2 ( 66 ) and PBK ( 67 ) gene products ( Figure 1 ).…”

Actomyosin-Driven Division of a Synthetic Cell

“…Alternatively, proteins can be used to bend actin into rings. Septins spontaneously bend actin into ringlike structures and are recruited to the cytokinetic ring, where they cooperate with anillin in actin–membrane binding. − Anillin itself also promotes the formation of actin rings by promoting overlap between filaments . Furthermore, the IQGAP fragment “curly” has recently been shown to bend actin into rings on model membranes by bending single actin filaments .…”

“…Alternatively, ring contraction may be driven by mechanisms that do not require molecular motors. For instance, anillin was recently shown to drive actin bundle contraction even though it is a passive cross-linker . Contraction was attributed to an energetically driven process whereby actin filaments increase their overlap as long as energy can be gained by accumulating diffusive cross-linkers in the overlap region .…”