Activation of Wnt signaling reduces ipsilaterally projecting retinal ganglion cells in pigmented retina.

In mammalian albinism, disrupted melanogenesis in the retinal pigment epithelium (RPE) is associated with fewer retinal ganglion cells (RGCs) projecting ipsilaterally to the brain, resulting in numerous abnormalities in the retina and visual pathway, especially binocular vision. To further understand the molecular link between disrupted RPE and a reduced ipsilateral RGC projection in albinism, we compared gene expression in the embryonic albino and pigmented mouse RPE. We found that the Wnt pathway, which directs peripheral retinal differentiation and, generally, cell proliferation, is dysregulated in the albino RPE.