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Updated: Sep 27, 2026
A Drosophila In Vivo Injury Model for Studying Neuroregeneration in the Peripheral and Central Nervous System
Published on: May 5, 2018
Rho kinase inhibition enhances axonal regeneration in the injured CNS
Alyson E Fournier1, Bayan T Takizawa, Stephen M Strittmatter
1Department of Neurology and Section of Neurobiology, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
Abstract:
Myelin-associated inhibitors limit axonal regeneration in the injured brain and spinal cord. A common target of many neurite outgrowth inhibitors is the Rho family of small GTPases. Activation of Rho and a downstream effector of Rho, p160ROCK, inhibits neurite outgrowth. Here, we demonstrate that Rho is directly activated by the myelin-associated inhibitor Nogo-66. Using a binding assay to measure Rho activity, we detected increased levels of GTP Rho in PC12 and dorsal root ganglion (DRG) cell lysates after Nogo-66 stimulation. Rho activity levels were not affected by Amino-Nogo stimulation. Rho inactivation with C3 transferase promotes neurite outgrowth of chick DRG neurons in vitro, but with the delivery method used here, it fails to promote neurite outgrowth after corticospinal tract (CST) lesions in the adult rat. Inhibition of p160ROCK with Y-27632 also promotes neurite outgrowth on myelin-associated inhibitors in vitro. Furthermore, Y-27632 enhances sprouting of CST fibers in vivo and accelerates locomotor recovery after CST lesions in adult rats.
Insights
Myelin inhibitors like Nogo-66 activate Rho GTPases, hindering nerve regeneration. Inhibiting Rho-associated kinase (ROCK) promotes axonal regrowth and functional recovery after spinal cord injury.
Area of Science:
- Neuroscience
- Cell Biology
- Regenerative Medicine
Background:
- Myelin-associated inhibitors impede axonal regeneration in the central nervous system.
- The Rho signaling pathway, particularly Rho and its effector p160ROCK, is a key mediator of neurite outgrowth inhibition.
Purpose of the Study:
- To investigate the direct activation of Rho by the myelin-associated inhibitor Nogo-66.
- To evaluate the therapeutic potential of inhibiting Rho or p160ROCK for axonal regeneration and functional recovery after spinal cord injury.
Main Methods:
- Stimulation of PC12 and dorsal root ganglion (DRG) cells with Nogo-66 and Amino-Nogo.
- Measurement of Rho activity using a GTP-Rho binding assay.
- Inhibition of Rho with C3 transferase and p160ROCK with Y-27632 in vitro and in vivo models of spinal cord injury.
Main Results:
- Nogo-66 directly activated Rho GTPases in neuronal cell lysates.
- Rho inactivation promoted neurite outgrowth in vitro but failed to enhance regeneration after corticospinal tract (CST) lesions in vivo with the tested delivery method.
- p160ROCK inhibition promoted neurite outgrowth on myelin inhibitors in vitro, enhanced CST fiber sprouting, and accelerated locomotor recovery in vivo.
Conclusions:
- Nogo-66-mediated Rho activation is a significant mechanism underlying inhibition of axonal regeneration.
- Targeting p160ROCK represents a promising therapeutic strategy for promoting axonal regeneration and functional recovery after central nervous system injury.
