Growth, collapse, and stalling in a mechanical model for neurite motility

TL;DR

This paper introduces a three-component active gel model that captures the mechanical behaviors of neurites, including growth, collapse, and stalling, based on the interplay of microtubules and acto-myosin forces.

Contribution

It presents a novel mechanical model that explains neurite states and responses to forces and drugs, integrating microtubule dynamics and acto-myosin contractility.

Findings

Model predicts neurite response to towing forces.

Reproduces effects of cytoskeletal drug treatments.

Identifies conditions for neurite stability and motility.

Abstract

Neurites, the long cellular protrusions that form the routes of the neuronal network are capable to actively extend during early morphogenesis or to regenerate after trauma. To perform this task, they rely on their cytoskeleton for mechanical support. In this paper, we present a three-component active gel model that describes neurites in the three robust mechanical states observed experimentally: collapsed, static, and motile. These states arise from an interplay between the physical forces driven by growth of the microtubule-rich inner core of the neurite and the acto-myosin contractility of its surrounding cortical membrane. In particular, static states appear as a mechanical traction/compression balance of these two parallel structures. The model predicts how the response of a neurite to a towing force depends on the force magnitude and recovers the response of neurites to several drug treatments that modulate the cytoskeleton active and passive properties.