Expression profiling of Ascl1-reprogrammed P12 Mller glia compared with freshly dissociated progenitors and Mller glia

Non-mammalian vertebrates have a robust ability to regenerate injured retinal neurons from Mller glia cells (MG) that activate the proneural factor Achaete-scute homolog 1 (Ascl1/Mash1) and de-differentiate into progenitors cells. In contrast, mammalian MG have a limited regenerative response and fail to upregulate Ascl1 after injury. To test whether Ascl1 could restore a neurogenic potential to mammalian MG, we over-expressed Ascl1 in dissociated mouse MG cultures and intact retinal explants. Ascl1-infected MG upregulate retinal progenitor-specific genes, while downregulating glial genes. Furthermore, Ascl1 remodeled the chromatin at its targets from a repressive to active configuration. MG-derived progenitors differentiated into cells that exhibited neuronal morphologies, expressed retinal subtype-specific neuronal markers, and displayed neuron-like physiological responses. These results indicate that a single transcription factor, Ascl1, can produce a neurogenic state in mature Muller glia.

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Pollak J, Wilken MS, Ueki Y, Cox KE, Sullivan JM, Taylor RJ, Levine EM, Reh TA