Dynamics and stability of contractile actomyosin ring in the cell

TL;DR

This paper develops a continuum gel theory model to analyze the dynamics and stability of the actomyosin contractile ring during cell division, explaining experimental observations and predicting stability changes during constriction.

Contribution

It provides exact axisymmetric solutions and linear stability analysis of the actomyosin ring, revealing how active stresses influence flow and stability during cytokinesis.

Findings

Unstable low wave number modes during initial constriction become stable as the ring shrinks.

Effective tension decreases with ring radius, slowing contraction at later stages.

Model aligns with experimental closure rates and stability patterns.

Abstract

Contraction of the cytokinetic ring during cell division leads to physical partitioning of a eukaryotic cell into two daughter cells. This involves flows of actin filaments and myosin motors in the growing membrane interface at the mid-plane of the dividing cell. Assuming boundary driven alignment of the acto-myosin filaments at the inner edge of the iterface we explore how the resulting active stresses influence the flow. Using the continuum gel theory framework, we obtain exact axisymmetric solutions of the dynamical equations. These solutions are consistent with experimental observations on closure rate. Using these solutions we perform linear stability analysis for the contracting ring under non-axisymmetric deformations. Our analysis shows that few low wave number modes, which are unstable during onset of the constriction, later on become stable when the ring shrinks to smaller radii, which is a generic feature of actomyosin ring closure. Our theory also captures how the effective tension in the ring decreases with its radius causing significant slow down in the contraction process at later times.