Abstract

Bundled actin structures play a key role in maintaining cellular shape, in aiding force transmission to and from extracellular substrates, and in affecting cellular motility. Recent studies have also brought to light new details on stress generation, force transmission and contractility of actin bundles. In this work, we are primarily interested in the question of what determines the stability of actin bundles and what network geometries do unstable bundles eventually transition to. To address this problem, we used the MEDYAN mechano-chemical force field, modeling several micron-long actin bundles in 3D, while accounting for a comprehensive set of chemical, mechanical and transport processes. We developed a hierarchical clustering algorithm for classification of the different long time scale morphologies in our study. Our main finding is that initially unipolar bundles are significantly more stable compared with an apolar initial configuration. Filaments within the latter bundles slide easily with respect to each other due to myosin activity, producing a loose network that can be subsequently severely distorted. At high myosin concentrations, a morphological transition to aster-like geometries was observed. We also investigated how actin treadmilling rates influence bundle dynamics, and found that enhanced treadmilling leads to network fragmentation and disintegration, while this process is opposed by myosin and crosslinking activities. Interestingly, treadmilling bundles with an initial apolar geometry eventually evolve to a whole gamut of network morphologies based on relative positions of filament ends, such as sarcomere-like organization. We found that apolar bundles show a remarkable sensitivity to environmental conditions, which may be important in enabling rapid cytoskeletal structural reorganization and adaptation in response to intracellular and extracellular cues.

Highlights

  • In these run folders, the following files and formats are found for each trajectory: 1. Input Files Input files are provided for all system configurations studied

  • Data is organized into three major compressed folders, namely non-treadmilling, Unipolar_treadmilling and Apolar_treadmilling. These zip files contain datafro and input files for studies on non-treadmilling, treadmilling unipolar and treadmilling apolar bundles respectively. This data upload contains a set of system configurations that have been studied

  • The following files and formats are found for each trajectory: 1. Input Files Input files are provided for all system configurations studied

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Summary

Introduction

The following files and formats are found for each trajectory: 1. Input Files Input files are provided for all system configurations studied. Data is organized into three major compressed (zip) folders, namely non-treadmilling, Unipolar_treadmilling and Apolar_treadmilling. These zip files contain datafro and input files for studies on non-treadmilling (unipoalr and apolar), treadmilling unipolar and treadmilling apolar bundles respectively. This data upload contains a set of system configurations that have been studied. The following table describes what each folder name denotes. Folder Name alpha:A values: 0.01, 0.05, 0.1, 0.4, 0.6, 0.8

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