Role of ELOVL2 in age-related visual decline - PROJECT SUMMARY/ABSTRACT Age-related macular degeneration (AMD) is a leading cause of visual disability worldwide, resulting in a significant medical and social burden. While the pathogenesis of AMD is multifactorial, dysfunction of the retinal pigment epithelium (RPE) contributes early to the progression of the disease. The RPE is a post-mitotic epithelial monolayer that is essential in maintaining the health and proper function of the adjacent photoreceptors. The RPE performs several functions, which include nutrient delivery, regeneration of the visual chromophore 11-cis-retinal for phototransduction, and phagocytosis of shed photoreceptor outer segments (POS). In fact, the RPE is the most actively phagocytic cell in the human body, engulfing and processing up to 10% of spent POS every day to avoid accumulation of harmful photooxidative products. Therefore, it is critical to understand age-related changes in RPE physiology; however, the role of lipid metabolism in regulating these changes has yet to be fully understood. It is becoming increasingly clear that alterations in lipid metabolism occur during aging across several tissues. In particular, the eye is highly enriched in docosahexanoic acid (DHA) and very long-chain polyunsaturated fatty acids (VLC-PUFAs), which play key roles in maintaining cellular membrane homeostasis. Recent research has correlated decreased levels of DHA and VLC-PUFAs with advanced age, and this decrease was further amplified in AMD eyes. A separate study has also linked a decline in RPE phagocytic function during aging, which also declined even further in AMD eyes. Thus, this proposal will investigate the mechanistic basis for age-related changes in RPE lipid metabolism and their influence on cell function. To pursue these objectives, we have generated Elovl2C234W mice, which lack Elovl2 enzymatic activity and exhibit decreased levels of DHA and VLC-PUFAs. Elovl2C234W mice also show accumulation of sub-RPE deposits with similar composition to drusen, one of the hallmarks of non-neovascular, or dry, AMD. The retinal structure, visual function, visual cycle activity, and phagocytic ability of mutant mice will be assessed at several ages. Changes in gene expression resulting from lack of Elovl2 activity will be analyzed by bulk and single cell RNA sequencing in RPE and retina. Lastly, we will correlate findings from mouse RPE to results from human RPE through the culture of RPE cells derived from human induced pluripotent stem cells. This proposal will be completed under the mentorship of Dorota Skowronska-Krawczyk, PhD and co-mentorship of Krzysztof Palczewsk, PhD in the Center for Translational Vision Research at the University of California, Irvine. The scientific training will also be supported by the Department of Physiololgy & Biophysics, the Medical Scientist Training Program, and collaborators and mentors from external institutions. The training plan details specific goals under this proposal, which include technical skills, such as measurements of mouse visual physiology and human induced pluripotent stem cell culture, analytical skills, including bioinformatic approaches, and professional skills, such as scientific communication and mentorship.
