Expression of SoxC Transcription Factors during Zebrafish Retinal and Optic Nerve Regeneration

The SoxC transcription factors (Sox4, Sox11, and Sox12) play important roles in the development of the vertebrate eye and retina. However, their expression and function during retinal and optic nerve regeneration remain elusive. In this study, we investigated the expression and possible functions of the SoxC genes after retinal and optic nerve injury in adult zebrafish. We found that among the five SoxC members, Sox11b was strongly induced in BrdU-positive cells in the inner nuclear layer (INL) after retinal injury, and morpholino-mediated Sox11b-knockdown significantly reduced the number of proliferating cells in the INL at 4 days post-injury. After optic nerve lesion, both Sox11a and Sox11b were strongly expressed in retinal ganglion cells (RGCs), and knockdown of both Sox11a and Sox11b inhibited RGC axon regrowth in retinal explants. Our study thus uncovered a novel expression pattern of SoxC family genes after retinal and optic nerve injury, and suggests that they have important functions during retinal and optic nerve regeneration.