Viral-mediated Oct4 overexpression and inhibition of Notch signaling synergistically induce neurogenic competence in mammalian Muller glia.

Retinal Muller glia in cold-blooded vertebrates can reprogram into neurogenic progenitors to replace neurons lost to injury, but mammals lack this ability. While recent studies have shown that transgenic overexpression of neurogenic bHLH factors and glial-specific disruption of NFI family transcription factors and Notch signaling induce neurogenic competence in mammalian Muller glia, induction of neurogenesis in wildtype glia has thus far proven elusive. Here we report that viral overexpression of the pluripotency factor Oct4 (Pou5f1) induces transdifferentiation of wildtype mouse Muller glia into bipolar neurons, and stimulates this process synergistically in parallel with Notch loss of function. Single cell multiomic analysis shows that Oct4 overexpression leads to widespread changes in gene expression and chromatin accessibility, inducing activity of both the neurogenic transcription factor Rfx4 and the Yamanaka factors Sox2 and Klf4. This study demonstrates that viral overexpression of Oct4 induces neurogenic competence in wildtype retinal Muller glia, identifying mechanisms that could be used in cell-based therapies for treating retinal dystrophies.