Abstract
Purpose :
We recently demonstrated that Wnt signaling induced robust axonal regeneration in the optic nerve after traumatic injury. Additionally, Wnt activation in Muller glia-RGC co-cultures significantly increases RGC average neurite length and branch site number and Wnt-treated Muller glia exhibited a distinct secretome protein profile associated with the regulation of axon extension, axon projection, and cell adhesion. In this study, we investigated whether the secretome of the Muller glia contains developmental embryologic genes involved in Wnt-induced axonal regeneration.
Methods :
The Wnt-treated Muller glia secretome was cross-referenced for proteins encoding eye and retinal development, Wnt signaling, Wnt signaling and development, axonal guidance, and any combination of these categories. Mice received intravitreal injections of Wnt5a or saline immediately before optic nerve crush injury and retinas were obtained 3, 7, and 14 days later. QPCR was used to quantify developmental regulators and immunohistochemistry assessed cells expressing progenitor cell markers.
Results :
Analysis of the Wnt-treated Muller glia secretome showed that of the 1253 unique proteins, 12 were associated with two or more of the categories listed above. QPCR demonstrated that Nphp4, a gene involved in retinal development, was decreased in Wnt5a injected retinas compared to saline seven days after optic nerve injury (p<0.024). Jade1, a stabilizing protein linked to Nphp4 and canonical Wnt signaling, was decreased in Wnt5a injected retinas compared to saline three days after optic nerve injury (p<0.035). INTU, a gene involved in ciliogenesis and axis polarity, was decreased in Wnt5a injected retinas compared to saline three days after optic nerve injury (p<0.0093). Immunohistochemistry of SOX2, PAX6, and Nestin showed no significant difference in the number of cells expressing these proteins in Wnt5a and Saline treated retinas (p<0.577, p<0.263, p<0.769).
Conclusions :
This study demonstrated that developmental genes may play a role in the Wnt signaling pathway and may be down-regulated during Wnt signaling-induced axonal regeneration. These findings identify possible key pathway links between developmental embryologic genes and Wnt-induced optic axonal regeneration.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.