Boundary-induced orientation of dynamic filament networks and vesicle agglomerations

TL;DR

This paper uncovers a statistical mechanism by which boundary conditions influence the orientation of intracellular filament networks and vesicle distributions, independent of filament interactions or regulation.

Contribution

It introduces a boundary-induced orientation mechanism based on filament dynamics, explaining vesicle accumulation patterns in axons without requiring explicit regulation.

Findings

Filament orientations are biased by cell boundaries.

The model reproduces vesicle accumulation in axons.

Orientation bias disappears with periodic boundary conditions.

Abstract

We find a statistical mechanism that can adjust orientations of intracellular filaments to cell geometry in absence of organizing centers. The effect is based on random and isotropic filament (de-)polymerization dynamics and is independent of filament interactions and explicit regulation. It can be understood by an analogy to electrostatics and appears to be induced by the confining boundaries; for periodic boundary conditions no orientational bias emerges. Including active transport of particles, the model reproduces experimental observations of vesicle accumulations in transected axons.