Evidence of Muller glia conversion into retina ganglion cells using Neurogenin2

Abstract

Macular Degeneration, Glaucoma, and Retinitis Pigmentosa are all leading causes of irreversible visual impairment in the elderly, affecting hundreds of millions of patients. Muller glia cells (MGC), the main type of glia found in the vertebrate retina, can resume proliferation in the adult injured retina and contribute to tissue repair. Also, MGC can be genetically reprogrammed through the expression of the transcription factor (TF) Achaete-scute homolog 1 (ASCL1) into induced neurons (iNs), displaying key hallmarks of photoreceptors, bipolar and amacrine cells, which may contribute to regenerate the damaged retina. Here, we show that the TF neurogenin 2 (NEUROG2) is also sufficient to lineage-reprogram MGC into iNs. The efficiency of MGC lineage conversion by NEUROG2 is similar to that observed after expression of ASCL1. However, reprogramming efficiency is affected by previous exposure to EGF and FGF2 during the expansion of MGC population. Transduction of either Neurog2 or Ascl1 led to the upregulation of key retina neuronal genes in MGC-derived iNs, but only NEUROG2 induced a consistent increase in the expression of putative retinal ganglion cell (RGC) genes. In vivo electroporation of Neurog2 in the neonatal retina also induced a shift in the generation of retinal cell subtypes, favoring the differentiation RGCs at the expense of MGCs. Altogether, our data indicate that Neurog2 induces lineage conversion of MGCs into RGC-like iNs.