June 2023
Volume 64, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2023
Mef2c overexpression during late-stage retinal development delays photoreceptor maturation and promotes cone photoreceptor specification
Author Affiliations & Notes
  • Nicole Pannullo
    Neuroscience, Johns Hopkins University, Baltimore, Maryland, United States
  • Lizhi Jiang
    Neuroscience, Johns Hopkins University, Baltimore, Maryland, United States
  • Seth Blackshaw
    Neuroscience, Johns Hopkins University, Baltimore, Maryland, United States
  • Footnotes
    Commercial Relationships   Nicole Pannullo None; Lizhi Jiang None; Seth Blackshaw None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science June 2023, Vol.64, 3640. doi:
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      Nicole Pannullo, Lizhi Jiang, Seth Blackshaw; Mef2c overexpression during late-stage retinal development delays photoreceptor maturation and promotes cone photoreceptor specification. Invest. Ophthalmol. Vis. Sci. 2023;64(8):3640.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Mef2c is an important transcriptional regulator of photoreceptor development, however its ability to influence cell fate specification in the developing retina has not been evaluated. We have electroporated a Mef2c overexpression construct in murine retinal explants to test its ability to alter the developmental trajectory and promote photoreceptor specification during late-stage retinal development. Since late-stage retinal progenitor cells (RPCs) share similar transcriptional regulatory networks with Muller glia (MG), this phenotype would inform current efforts to reprogram adult MG to RPCs that are competent to produce photoreceptors upon retinal injury in vivo.

Methods : Mef2c was expressed in a pCAGIG construct downstream of a CAG promoter and upstream of an eGFP under the control of a bicistronic IRES element. Postnatal day 0 (P0) retinal explants were electroporated ex vivo and cultured until P8. The resulting phenotype was analyzed using both scRNA-seq and immunohistochemistry to screen the construct for its ability to alter the developmental trajectory in the retina.

Results : Retinal explants electroporated with the Mef2c construct at P0 showed a phenotype at P8 that included an increase in photoreceptor generation, particularly cone photoreceptors, and a decrease in the generation of inner retinal cells including bipolar and amacrine cells. Notably, this construct also delayed the maturation of photoreceptors. The construct induced expression of genes associated with photoreceptor specification, including Guca1a, Rcvrn, Pdc. and Prom1, with a cluster of immature photoreceptor cells also expressing markers of cones, including Cngb3, Gnat2, and Arr3.

Conclusions : These results suggest that Mef2c overexpression is sufficient to shift the developmental trajectory of the retina to promote photoreceptor specification, specifically cone photoreceptors, and delay maturation of photoreceptors. Since adult MG share similar transcriptional regulatory networks with late-stage RPCs, this construct is a potentially promising candidate for reprogramming MG to RPCs that are competent to produce photoreceptors upon retinal injury in vivo.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

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