Mitochondrial pyruvate transport in retinal health and disease

项目总结/摘要 视网膜是人体内代谢最活跃的神经组织。中的缺陷 光感受器神经元及其支持细胞包括胶质细胞和视网膜的能量代谢 色素上皮（RPE）是视网膜变性的重要原因 遗传性视网膜变性和年龄相关性黄斑变性（AMD）等疾病。 以前的研究和我们实验室的数据支持光感受器，神经胶质细胞和RPE是 在生物化学上适于形成代谢生态系统：1）RPE从脉络膜转运葡萄糖 光感受器的血液供应; 2）光感受器将大部分葡萄糖代谢成乳酸; 3） 乳酸盐抑制RPE中的糖酵解以促进葡萄糖转运; 4）乳酸盐刺激Müller胶质细胞， 合成光感受器用谷氨酰胺。该项目的长期目标是定义 光感受器和Müller胶质细胞之间以及RPE和外视网膜之间的代谢相互作用 并确定它们在视网膜功能和变性中的作用。 线粒体丙酮酸载体（MPC）控制丙酮酸从糖酵解进入线粒体。 线粒体的氧化代谢。我们最近发现视网膜中MPC的缺失 消耗谷氨酰胺和谷氨酸，抑制谷氨酰胺利用，增强酮体 氧化，导致视觉功能进行性下降和视网膜变性。我们 初步数据显示，在光感受器中缺失MPC会导致更温和的 表型比整个视网膜敲除，支持代谢的相互作用，乳酸是利用 其他细胞。本研究的目的是探讨线粒体丙酮酸的作用 光感受器、Müller细胞和RPE在代谢相互作用、视觉功能和 视网膜存活率我们计划分别在光感受器、神经胶质或RPE中条件性敲除MPC 并严格测试我们的假设，使用先进的示踪方法，质谱， 体内输注13 C示踪剂，代谢物的高分辨率成像，视觉功能测试，光学 相干断层扫描和透射电子显微镜。 这项研究的结果将建立一个视网膜代谢的概念框架， 描述了葡萄糖是如何在不同的视网膜细胞中运输和利用的， 一种视网膜细胞代谢的破坏会影响其代谢、功能和生存能力 其他的视网膜细胞。这些新知识将为理解 视网膜退行性疾病的发病机制，为开发新的 治疗。

PROJECT SUMMARY/ABSTRACT The retina is the most metabolically active neuronal tissue in the human body. The defect in the energy metabolism of photoreceptor neurons and their supporting cells including glia and retinal pigment epithelium (RPE), emerges as an important underlying cause for retinal degenerative diseases such as inherited retinal degeneration and aging-related macular degeneration (AMD). Previous studies and data from our lab support that photoreceptors, glial cells, and RPE are biochemically adapted to form a metabolic ecosystem: 1) RPE transports glucose from choroid blood supply to photoreceptors; 2) Photoreceptors metabolize most of the glucose into lactate; 3) Lactate inhibits glycolysis in RPE to facilitate glucose transport; 4) Lactate stimulate Müller glia to synthesize glutamine for photoreceptors. The long term goal of this project is to define the metabolic interactions between photoreceptors and Müller glia and between RPE and outer retina in vivo and identify their roles in retinal function and degeneration. Mitochondrial pyruvate carrier (MPC) controls the entry of pyruvate from glycolysis into mitochondria for oxidative metabolism. We recently found that the deletion of MPC in the retina depletes glutamine and glutamate, inhibits glutamine utilization and enhancing ketone body oxidation, resulting in a progressive decline of visual function and retinal degeneration. Our preliminary data showed that the deletion of MPC in photoreceptors causes much milder phenotype than whole retina knockout, supporting the metabolic interaction that lactate is utilized by other cells. The objective of this proposal is to investigate the roles of mitochondrial pyruvate transport in photoreceptor, Müller cells and RPE in metabolic interactions, visual function, and retinal survival. We plan to conditionally knockout MPC in photoreceptors, glia or RPE separately and rigorously test our hypothesis using advanced tracer methodology, mass spectrometry, in vivo infusion with 13C tracers, high-resolution imaging of metabolites, visual function tests, optical coherence tomography, and transmission electron microscopy. The outcome of this research will establish a conceptual framework for retinal metabolism that describes how glucose is transported and utilized in different retinal cells and describes how disruption of metabolism in one kind of retinal cells impacts the metabolism, function, and viability of other retinal cells. This new knowledge will provide the basis for understanding the mechanisms of retinal degenerative diseases and lay the foundation for developing new treatments.