The homeobox gene, dmbx1a, is required for the development and maintenance of bipolar and photoreceptor cells in the zebrafish retina

Retinal neurogenesis at early postembryonic stages is conserved among vertebrates for its role in homeostatic tissue growth and its dysfunction in humans may partially account for diseases of retinal growth or other retinal dystrophies. However, the molecular mechanisms underlying neurogenic growth of the postembryonic retina are poorly characterized. We report a novel role for the homeobox gene dmbx1a in tissue growth, survival of differentiated cells, bipolar differentiation, and photoreceptor maintenance in the postembryonic zebrafish retina. Specifically, dmbx1a mutants exhibited reduced eye size over time, increased cell death in differentiated cells derived from progenitor cells of the central retina and ciliary marginal zone, and age- and light-dependent photoreceptor dysmorphism. By examining the early changes in the retinal transcriptome of dmbx1a mutants, we were able to determine changes in gene expression that are associated with the observed retinal defects. Among this transcriptomic data, there is evidence to suggest that dmbx1 affects known retinal-associated genes implicated in retinal degenerative conditions and ocular impairments, with a particular emphasis on ciliogenesis factors important for outer segment growth in photoreceptors.