ABSTRACT
Age-related macular degeneration (AMD) is a leading cause of irreversible blindness in the developed world. Caucasians are eightfold more likely to develop AMD than any other race, indicating a racial bias in AMD incidence which is unexplained. We hypothesize that pigmentation of the retinal pigment epithelium (RPE) and choroid protects from AMD and underlies this peculiar racial bias. We investigated GPR143, a receptor in the pigmentation pathway, which is activated by a melanin synthesis by-product, l-dopa. In this model, greater pigmentation leads to greater l-dopa production and, in turn, greater GPR143 signaling. GPR143 activity upregulates PEDF and downregulates both VEGF and exosomes; all of which reduce the angiogenic potential in the retina. Moreover, we demonstrate that GPR143 signaling enhances the digestion of shed photoreceptor outer segments. Together, our data suggests a central role for GPR143 signaling in RPE-photoreceptor interaction which is critical to healthy vision.
