The Regenerative Potential and Mechanism of an Alpha7 Nicotinic Acetylcholine Receptor Agonist in the Adult Mammalian Retina
Date of Award
Doctor of Philosophy
Dr. Cindy Linn
Dr. Jeremy Duncan
Dr. John Spitsbergen
Dr. David Linn
Retina, retinal regeneration, PNU-282487, a7 nAChR, glaucoma, retinitis pigmentosa
The capacity for sight is one of our most precious senses as humans rely on vision to interact with the world around them. Therefore, degenerative diseases or disorders of the retina that lead to loss of vision take a significant toll on our national healthcare system, our communities, and the global population. Regeneration of lost or damaged cells would drastically reduce effects and outcomes of disease states. However, to date, the extent of retinal regeneration possible in mammals is extremely limited and requires significant external manipulation. This study seeks to demonstrate that adult mammals can regenerate significant numbers of retinal neurons in multiple disease paradigms, with a relatively simple retinal treatment using PNU- 282987, an alpha 7 nicotinic acetylcholine receptor agonist. Treatment with PNU-282987 restores the retina back to full visual potential in both glaucoma and retinitis pigmentosa-like disease, with lost neurons being replaced and integrating into the existing retinal infrastructure. In addition, the mechanism of PNU-282987’s effect is investigated in this study. New adult retinal neurons are shown to be derived from the resident Müller glia, which generate Müller-derived progenitor cells upon PNU-282987 treatment. The generation of these Müller-derived progenitor cells are shown to stem from activating α7 nicotinic acetylcholine receptors on retinal pigment epithelium, which cause large transcriptional changes, resulting in the release of signaling molecules onto Müller glia. Genetic analysis and CRISPR/cpf1-based gene editing reveals that several important signaling molecules are required for PNU-282987-based regeneration including Six3, Sim2, and hbEGF while others that are important in other vertebrate regeneration model systems, like wnt2b, were not found to play a role. Lastly, these studies demonstrate that PNU-282987 generated neurons affect ERG function in the retina. Taken together, these findings demonstrate that the adult mammalian retina is capable of robust regeneration in the face of significant degenerative disease, and that Six3, Sim2, and hbEGF play a novel role in the generation of retinal progenitor cells in the adult mammalian retina. This illustrates the potential of understanding a specific regeneration mechanism for adult mammals that can ultimately lead to treatments that help millions living with low vision and blindness.
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Webster, Sarah E., "The Regenerative Potential and Mechanism of an Alpha7 Nicotinic Acetylcholine Receptor Agonist in the Adult Mammalian Retina" (2021). Dissertations. 3776.