Filamin cross-linked semiflexible networks: Fragility under strain

TL;DR

This study models semiflexible cytoskeletal networks cross-linked by filamin proteins, revealing how high strain induces self-organization where many cross-linkers reach unfolding threshold, impacting network fragility.

Contribution

It introduces a simple network model capturing key mechanical features and explains strain-induced reorganization through a mean-field approach.

Findings

Network spontaneously reorganizes under high strain

Many filamin cross-linkers reach unfolding threshold

Proposes experimental signatures of reorganization

Abstract

The semiflexible F-actin network of the cytoskeleton is cross-linked by a variety of proteins including filamin, which contain Ig-domains that unfold under applied tension. We examine a simple semiflexible network model cross-linked by such unfolding linkers that captures the main mechanical features of F-actin networks cross-linked by filamin proteins and show that under sufficiently high strain the network spontaneously self-organizes so that an appreciable fraction of the filamin cross-linkers are at the threshold of domain unfolding. We propose an explanation of this organization based on a mean-field model and suggest a qualitative experimental signature of this type of network reorganization under applied strain that may be observable in intracellular microrheology experiments of Crocker et al.