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Updated: Nov 15, 2025
Coculture of Axotomized Rat Retinal Ganglion Neurons with Olfactory Ensheathing Glia, as an In Vitro Model of Adult Axonal Regeneration
Published on: November 2, 2020
Optic nerve regeneration screen identifies multiple genes restricting adult neural repair
Jane A Lindborg1, Nicholas M Tran2, Devon M Chenette1
1Cellular Neuroscience, Neurodegeneration, Repair, Departments of Neurology and of Neuroscience, Yale University School of Medicine, New Haven, CT 06536, USA.
Abstract:
Adult mammalian central nervous system (CNS) trauma interrupts neural networks and, because axonal regeneration is minimal, neurological deficits persist. Repair via axonal growth is limited by extracellular inhibitors and cell-autonomous factors. Based on results from a screen in vitro, we evaluate nearly 400 genes through a large-scale in vivo regeneration screen. Suppression of 40 genes using viral-driven short hairpin RNAs (shRNAs) promotes retinal ganglion cell (RGC) axon regeneration after optic nerve crush (ONC), and most are validated by separate CRISPR-Cas9 editing experiments. Expression of these axon-regeneration-suppressing genes is not significantly altered by axotomy. Among regeneration-limiting genes, loss of the interleukin 22 (IL-22) cytokine allows an early, yet transient, inflammatory response in the retina after injury. Reduced IL-22 drives concurrent activation of signal transducer and activator of transcription 3 (Stat3) and dual leucine zipper kinase (DLK) pathways and upregulation of multiple neuron-intrinsic regeneration-associated genes (RAGs). Including IL-22, our screen identifies dozens of genes that limit CNS regeneration. Suppression of these genes in the context of axonal damage could support improved neural repair.
Insights
Researchers identified genes that limit central nervous system (CNS) axon regeneration after injury. Suppressing these genes, including interleukin-22 (IL-22), promotes neural repair and could improve outcomes for CNS trauma patients.
Area of Science:
- Neuroscience
- Regenerative Medicine
- Molecular Biology
Background:
- Adult mammalian central nervous system (CNS) injuries cause persistent neurological deficits due to limited axonal regeneration.
- Axonal growth is hindered by both extracellular inhibitors and intrinsic cellular factors.
Purpose of the Study:
- To identify genes that suppress axonal regeneration in the CNS using a large-scale in vivo screen.
- To evaluate the therapeutic potential of suppressing identified regeneration-limiting genes.
Main Methods:
- Conducted a large-scale in vivo regeneration screen of nearly 400 genes based on in vitro results.
- Utilized viral-driven short hairpin RNAs (shRNAs) to suppress gene expression and CRISPR-Cas9 for validation.
- Investigated the role of interleukin-22 (IL-22) in the inflammatory response and downstream signaling pathways after optic nerve crush (ONC).
Main Results:
- Suppression of 40 genes promoted retinal ganglion cell (RGC) axon regeneration after ONC, with most findings validated by CRISPR-Cas9.
- Expression of these regeneration-limiting genes was not significantly altered by axotomy.
- Loss of IL-22 induced a transient inflammatory response, activating STAT3 and DLK pathways and upregulating regeneration-associated genes (RAGs).
Conclusions:
- Identified numerous genes that limit CNS regeneration, providing novel targets for therapeutic intervention.
- Suppression of identified genes, particularly IL-22, shows promise for enhancing neural repair after axonal damage.
- Findings suggest that targeting these regeneration-limiting genes could lead to improved treatments for CNS injuries.
