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Nikolas Jorstad, Matthew Wilken, Leah VandenBosch, Thomas A Reh; Genomic analyses of Müller glia identifies additional factors to improve Ascl1-mediated retinal regeneration in mice. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1485. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Millions of people suffer from visual impairment from retinal disease and injury. Unlike mammals, zebrafish have the ability to regenerate lost neurons and restore visual function after retinal injury. The Müller glia (MG) are the source cell of this regeneration in fish and a key step in the process is the up-regulation of the proneural transcription factor, Ascl1, after injury. We recently showed transgenic expression of Ascl1 in mouse MG (along with Trichostatin A) enables them to regenerate functional retinal neurons after injury. In this study we analyzed the genomic basis for MG reprogramming that allows for their neurogenic competence to identify potential collaborating molecular pathways that may increase the regenerative response.
To determine if there are additional factors involved in Ascl1-mediated reprogramming that could be used to further stimulate this process, we carried out ChIP-seq for Ascl1 in (1) normal retinal progenitors and (2) the reprogrammed MG. The Ascl1-ChIP-seq peaks were called using HOMER and examined for overlap with ATAC-seq data from similar samples (using BEDOPS).
The top-scoring motif in both progenitors and reprogrammed MG was the canonical Ascl1 E-box, and neural development genes were enriched in Gene Ontology analyses for both conditions; however, the MG had more than twice the peaks of P0 progenitors, and only a third of them overlapped with progenitor peaks. Thus, in reprogrammed MG most of the Ascl1-bound sites are novel. To determine if glial transcription factors are associated with inappropriate Ascl1 ChIP-seq peaks in MG, we used HOMER to identify motifs enriched in these regions. We found these regions were significantly enriched for additional transcription factors that might facilitate regeneration. We are currently testing if additional factors identified with this genome wide analysis can be used to facilitate regeneration in adult mouse retina.
The combination of Ascl1, and a histone deacetylase inhibitor enable MG to undergo robust functional neural regeneration in the adult mouse retina. Genomic approaches have revealed additional candidate factors to further improve the effectiveness of this approach, with the potential for ultimate clinical application to promote retinal regeneration from endogenous MG.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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