Format

Send to

Choose Destination
Front Mol Neurosci. 2018 Sep 4;11:319. doi: 10.3389/fnmol.2018.00319. eCollection 2018.

The Regulation of Axon Diameter: From Axonal Circumferential Contractility to Activity-Dependent Axon Swelling.

Author information

1
Nerve Regeneration Group, Instituto de Biologia Molecular e Celular (IBMC) and Instituto de Inovação e Investigação em Saúde, University of Porto, Porto, Portugal.
2
Instituto de Ciências Biomédicas Abel Salazar (ICBAS), University of Porto, Porto, Portugal.

Abstract

In the adult nervous system axon caliber varies widely amongst different tracts. When considering a given axon, its diameter can further fluctuate in space and time, according to processes including the distribution of organelles and activity-dependent mechanisms. In addition, evidence is emerging supporting that in axons circumferential tension/contractility is present. Axonal diameter is generically regarded as being regulated by neurofilaments. When neurofilaments are absent or low, microtubule-dependent mechanisms can also contribute to the regulation of axon caliber. Despite this knowledge, the fine-tune mechanisms controlling diameter and circumferential tension throughout the lifetime of an axon, remain largely elusive. Recent data supports the role of the actin-spectrin-based membrane periodic skeleton and of non-muscle myosin II in the control of axon diameter. However, the cytoskeletal arrangement that underlies circumferential axonal contraction and expansion is still to be discovered. Here, we discuss in a critical viewpoint the existing knowledge on the regulation of axon diameter, with a specific focus on the possible role played by the axonal actin cytoskeleton.

KEYWORDS:

axon diameter; axonal contractility; axonal cytoskeleton; axonal tension; membrane periodic skeleton

Supplemental Content

Full text links

Icon for Frontiers Media SA Icon for PubMed Central
Loading ...
Support Center