Research Project
10315588
Summary Age-related macular degeneration (AMD) causes vision loss among many older individuals, and the retinal pigment epithelium (RPE) is thought to be a critical site of injury. Vision loss in AMD occurs due to photoreceptor degeneration and/or choroidal neovascularization. Geographic atrophy (GA), the advanced form of dry AMD, is characterized by the breakdown of RPE, choriocapillaris, and photoreceptors, especially in the macula. Lack of clear understanding of the molecular mechanisms of GA hinders the development of therapy. For lifelong maintenance of photoreceptors, RPE cells play an essential role in phagocytosis and degradation of tips shed from photoreceptor outer segments (POS). Photoreceptors and RPE cells are susceptible to injury from mitochondrial oxidative stress. The central goal of the project is to understand how photoreceptor degeneration occurs in GA. I hypothesize that oxidative stress impairs phagocytosis and lysosome function and ultimately activates inflammatory processes in RPE that stimulate geographic atrophy. I will test my hypothesis in RPE cell culture and in a new mouse model of age dependent RPE atrophy that was recently developed in our lab. In this model we used the cre/lox system to generate an RPE-specific deletion of Sod2, the mitochondrial gene for manganese superoxide dismutase (MnSOD). These mice develop a normal RPE but overtime the RPE has elevated oxidative stress resulting in phenotypic changes that are commonly observed in AMD, including RPE injury, loss of function and subsequent retinal degeneration. In the context of GA, I have following aims: (1) To characterize the impact of oxidative stress on phagocytosis, lysosomal function and inflammasome activation in RPE; (2) Identify molecular changes in RPE under oxidative stress. These studies will illuminate signaling pathways that drive photoreceptor and RPE loss and will provide a foundation to develop new therapeutic targets to prevent disease progression in AMD.
