Project Summary Accumulating evidence highlights the significance of comprehending metabolic changes in the retinal pigment epithelium (RPE) - the first site where pathogenesis occurs in many retinal degenerative diseases. The objective of the proposed research is to gain a deeper understanding of RPE metabolism and mitochondrial biology in both healthy and diseased states, from a cell biological perspective using state-of-the-art live imaging methods. The results of this project will bring about novel discoveries in disease mechanisms. The RPE is positioned between the photoreceptors and the choroid and has a crucial role in maintaining homeostasis in the outer retina. One of the critical functions of the RPE is the daily phagocytosis of the photoreceptor outer segment (POS). Phagosome transport is powered by ATP-dependent molecular motor activities, while the degradation products of the phagosome serve as a source of energy. The RPE mitochondria must adapt to these daily metabolic events. The proposed study will investigate the molecular and functional basis of these changes through metabolic analysis. Additionally, super-resolution high-speed live imaging and electron microscopy will be used to analyze the behaviors of potentially different subsets of RPE mitochondria in relation to specific RPE functions. The focus will be on three main questions: 1) How does RPE phagocytosis affect peroxisome- mitochondria-dependent lipid metabolism? 2) What is the role of mitochondrial dynamics and interaction with actin in the basal RPE? 3) What are the differences and similarities in the alterations of these mitochondrial interactions in Choroideremia? The findings of the study will be compared and contrasted with observations in human RPE cell lines and patient-derived iPSC-RPE cultures. A perfused microphysiological organ-on-chip model will also be utilized to imitate the outer blood-retina environment. This study will provide new insights into RPE mitochondrial dynamics, opening up the possibility of discovering new disease mechanisms and identifying novel therapeutic targets. The proposed research and training plan aligns with the missions of the National Eye Institute (NEI) to prevent and treat eye diseases. The applicant's advisory committee, made up of well-rounded experts, will provide guidance, and the applicant will have access to a wide range of scientific, career development, and diversity training resources at UCLA. This experience will help jumpstart the applicant's independent research career and bring her closer to her long-term goal of becoming a molecular and cellular vision biologist at a primary research university. With her earlier background in vascular biology, the proposed training will position the applicant as a uniquely qualified expert in the study of molecular mechanisms and cell- cell interactions in the vision system, while also promoting diversity in academia.