Rebuilding cytoskeleton roads: Active-transport-induced polarization of cells

TL;DR

This paper presents an analytical model explaining how cytoskeleton organization influences cell polarization, showing that filament geometry determines spontaneous polarization or response to external cues, aligning with experimental observations.

Contribution

The model introduces a unified framework linking cytoskeleton filament geometry to cell polarization mechanisms, integrating positive feedback dynamics.

Findings

Filament geometry dictates polarization capability.

Spontaneous polarization occurs with certain cytoskeleton arrangements.

Model aligns with experiments in yeast and neuron systems.

Abstract

Many cellular processes require a polarization axis which generally initially emerges as an inhomogeneous distribution of molecular markers in the cell. We present a simple analytical model of a general mechanism of cell polarization taking into account the positive feedback due to the coupled dynamics of molecular markers and cytoskeleton filaments. We find that the geometry of the organization of cytoskeleton filaments, nucleated on the membrane (e.g., cortical actin) or from a center in the cytoplasm (e.g., microtubule asters), dictates whether the system is capable of spontaneous polarization or polarizes only in response to external asymmetric signals. Our model also captures the main features of recent experiments of cell polarization in two considerably different biological systems, namely, mating budding yeast and neuron growth cones.