Wrinkling of a spherical lipid interface induced by actomyosin cortex

TL;DR

This study investigates how actomyosin cortex induces curvature-dependent wrinkling on a spherical lipid interface, revealing a transition from bending to stretching elasticity as curvature increases, providing insights into membrane deformation mechanisms.

Contribution

It introduces a reconstituted cell-sized model system to analyze actomyosin-induced wrinkling and explains the curvature-dependent deformation through theoretical cortex elasticity and contractility.

Findings

Wrinkling depends on membrane curvature, shifting from bending to stretching elasticity.

Theoretical model explains the curvature dependence of cortex elasticity.

Provides fundamental insights into membrane deformation by actomyosin.

Abstract

Actomyosin actively generates contractile forces that provide the plasma membrane with the deformation stresses essential to carry out biological processes. Although the contractile property of purified actomyosin has been extensively studied, to understand the physical contribution of the actiomyosin contractile force on a deformable membrane is still a challenging problem and of great interest in the field of biophysics. Here, we reconstituted a model system with a cell-sized deformable interface that exhibits anomalous curvature dependent wrinkling caused by actomyosin cortex underneath the spherical closed interface. Through the shape analysis of the wrinkling deformation, we found that the dominant contributor on the wrinkled shape changes from bending elasticity to stretching elasticity of the reconstituted cortex by increasing the droplet curvature radius of the order of the cell-size, i.e., tens of micrometer. The observed curvature dependence was explained by the theoretical description of the cortex elasticity and contractility. Our present results provide a fundamental insight on the deformation of a curved membrane induced by the actomyosin cortex.