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Updated: Jun 18, 2026
A Drosophila In Vivo Injury Model for Studying Neuroregeneration in the Peripheral and Central Nervous System
Published on: May 5, 2018
Rho-associated kinase II (ROCKII) limits axonal growth after trauma within the adult mouse spinal cord
Philip Duffy1, Andre Schmandke, Antonio Schmandke
1Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
Abstract:
Rho GTPases are thought to mediate the action of several axonal growth inhibitors in the adult brain and spinal cord. RhoA has been targeted pharmacologically in both humans and animals to promote neurite outgrowth and functional recovery following CNS trauma. However, rat spinal cord injury studies suggest a complicated and partial benefit of inhibiting Rho or its downstream effector, Rho-associated kinase (ROCKII). This limited benefit may reflect inhibition of other kinases, poor access, or a minimal role of ROCKII in vivo. Therefore, we studied ROCKII mutant mice to probe this pathway genetically. ROCKII(-/-) dorsal root ganglion neurons are less sensitive to inhibition by Nogo protein or by chondroitin sulfate proteoglycan in vitro. We examined adult ROCKII(-/-) mice in two injury paradigms, cervical multilevel dorsal rhizotomy and midthoracic dorsal spinal cord hemisection. After dorsal root crush injury, the ROCKII(-/-) mice recovered use of the affected forepaw more quickly than did controls. Moreover, multiple classes of sensory axons regenerated across the dorsal root entry zone into the spinal cord of mice lacking ROCKII. After the spinal cord injury, ROCKII(-/-) mice showed enhanced local growth of raphespinal axons in the caudal spinal cord and corticospinal axons into the lesion site. Improved functional recovery was not observed by Basso Mouse Scale score following dorsal hemisection, likely due to developmental defects in the nervous system. Together, these findings demonstrate that the ROCKII gene product limits axonal growth after CNS trauma.
Insights
Genetic studies reveal that Rho-associated kinase II (ROCKII) limits axonal regeneration after central nervous system trauma. Inhibiting ROCKII promotes sensory axon regrowth and recovery following spinal cord injury in mice.
Area of Science:
- Neuroscience
- Molecular Biology
- Regenerative Medicine
Background:
- Rho GTPases, including RhoA, are implicated in mediating axonal growth inhibition in the adult central nervous system (CNS).
- Pharmacological inhibition of RhoA and its effector, Rho-associated kinase II (ROCKII), has shown limited efficacy in promoting functional recovery after CNS trauma.
- The precise in vivo role of ROCKII in axonal regeneration following CNS injury remains incompletely understood.
Purpose of the Study:
- To genetically investigate the role of ROCKII in axonal growth inhibition and regeneration after CNS trauma.
- To determine the effect of ROCKII deficiency on neuronal sensitivity to growth inhibitors and functional recovery post-injury.
Main Methods:
- Utilized ROCKII knockout (ROCKII-/-) mice to genetically probe the ROCKII pathway.
- Assessed in vitro neuronal sensitivity of ROCKII-/- dorsal root ganglion neurons to Nogo and chondroitin sulfate proteoglycan.
- Examined adult ROCKII-/- mice in dorsal root crush and spinal cord hemisection injury models.
Main Results:
- ROCKII-/- neurons exhibited reduced sensitivity to known axonal growth inhibitors.
- ROCKII-/- mice showed accelerated forepaw recovery after dorsal root crush injury, with enhanced sensory axon regeneration into the spinal cord.
- Spinal cord injury in ROCKII-/- mice led to increased local growth of raphespinal and corticospinal axons, although overall functional recovery was not improved.
Conclusions:
- The ROCKII gene product acts as a significant barrier to axonal growth following CNS trauma.
- Genetic deletion of ROCKII promotes sensory axon regeneration and partial functional recovery in specific injury models.
- ROCKII is a critical molecular target for enhancing axonal regeneration and potentially improving outcomes after CNS injuries.
