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Updated: Aug 10, 2025
Methods for Experimental Manipulations after Optic Nerve Transection in the Mammalian CNS
Published on: May 12, 2011
Effects of constitutively active K-Ras on axon regeneration after optic nerve injury
Naoki Kiyota1, Kazuhiko Namekata2, Euido Nishijima2
1Visual Research Project, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan; Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan.
Abstract:
Visual disturbance after optic nerve injury is a serious problem. Attempts have been made to enhance the intrinsic ability of retinal ganglion cells (RGCs) to regenerate their axons, and the importance of PI3K/Akt and RAF/MEK/ERK signal activation has been suggested. Since these signals are shared with oncogenic signaling cascades, in this study, we focused on a constitutively active form of K-Ras, K-RasV12, to determine if overexpression of this molecule could stimulate axon regeneration. We confirmed that K-RasV12 phosphorylated Akt and ERK in vitro. Intravitreal delivery of AAV2-K-RasV12 increased the number of surviving RGCs and promoted 1.0 mm of axon regeneration one week after optic nerve injury without inducing abnormal proliferative effects in the RGCs. In addition, AAV2-K-RasV12 induced robust RGC axon regeneration, reaching as far as approximately 2.5 mm from the injury site, in eight weeks. Our findings suggest that AAV2-K-RasV12 could provide a good model for speedy and efficient analysis of the mechanism underlying axon regeneration in vivo.
Insights
Overexpressing K-RasV12 in retinal ganglion cells (RGCs) promotes significant axon regeneration after optic nerve injury. This approach enhances RGC survival and aids in studying regeneration mechanisms in vivo.
Area of Science:
- Neuroscience
- Cell Biology
- Regenerative Medicine
Background:
- Optic nerve injury causes visual disturbance, highlighting the need for retinal ganglion cell (RGC) axon regeneration.
- Signaling pathways like PI3K/Akt and RAF/MEK/ERK are implicated in RGC axon growth.
- These pathways overlap with oncogenic signaling, suggesting potential therapeutic targets.
Purpose of the Study:
- To investigate if a constitutively active K-Ras mutant (K-RasV12) can stimulate RGC axon regeneration.
- To assess the safety and efficacy of AAV2-mediated K-RasV12 delivery in vivo.
Main Methods:
- In vitro confirmation of K-RasV12's ability to phosphorylate Akt and ERK.
- Intravitreal injection of adeno-associated virus serotype 2 carrying K-RasV12 (AAV2-K-RasV12) into rats.
- Assessment of RGC survival and axon regeneration at one and eight weeks post-optic nerve injury.
Main Results:
- K-RasV12 successfully phosphorylated Akt and ERK in vitro.
- AAV2-K-RasV12 treatment increased RGC survival and promoted 1.0 mm axon regeneration within one week.
- Significant regeneration, approximately 2.5 mm, was observed by eight weeks without inducing abnormal RGC proliferation.
Conclusions:
- AAV2-K-RasV12 effectively stimulates RGC axon regeneration and enhances RGC survival post-injury.
- K-RasV12 shows potential as a therapeutic strategy for optic nerve injury.
- This model offers a valuable tool for studying axon regeneration mechanisms in vivo.
