Sustained EGFR Signaling Expands Otx2⁺ and Chx10⁺ Retinal Progenitors in the Postnatal Mouse Retina

The regenerative potential of the mammalian retina is limited, yet identifying signaling pathways that influence progenitor cell behavior remains an important step toward understanding the mechanisms of retinal development and plasticity. Epidermal Growth Factor Receptor (EGFR) signaling has been implicated in regulating proliferation and differentiation in the central nervous system, but its role in the postnatal retina is less defined. In this study, we employed an ex vivo explant model of the postnatal mouse retina to investigate the effects of sustained Epidermal Growth Factor (EGF) stimulation. Our results demonstrate that EGF extends the proliferative activity of progenitors that are normally quiescent after birth. However, the sustained EGFR activation (10 ng/mL, for 7 days) in the postnatal retina not only promotes EGFR+ progenitor proliferation but also maintains co-expression of Otx2 and Chx10, revealing a distinct progenitor population, suggesting that extended EGF signaling influences lineage allocation. These findings indicate that EGFR activation can modulate both the maintenance and differentiation potential of retinal progenitors in a context-dependent manner. While additional studies are needed to determine whether these progenitors develop into mature, functional neurons, our work provides a framework for future investigations into signaling pathways that may be leveraged to influence retinal development and plasticity.