Degradative Processes in RPE-photoreceptor renewal

描述(申请人提供)：视网膜色素上皮细胞作为吞噬细胞，起到维持光感受器完整性和维持视觉功能的稳态调节作用。因此，对于有丝分裂后的RPE细胞来说，利用分解代谢途径导致吞噬的货物降解是有利的，在压力下，吞噬的货物可以处理氧化的有毒底物的摄入。我们认为，RPE中的吞噬小体成熟包括LC_3相关吞噬细胞(LAP)过程中的LC_3脂化。我们假设这些过程在RPE脂质动态平衡中至关重要，因为它为神经保护素D1(NPD1)的合成提供了一个二十二碳六烯酸(DHA；22：6)池，以促进RPE细胞的存活，进而维持光感受器的完整性。在特定的目标1中，我们将检验RPE吞噬小体在LAP中吞噬自噬途径的组件的假设，并评估氧化外段(OS)对这一过程的贡献。在特定的目标2中，我们假设黑素调节蛋白(MREG)介导的降解涉及LAP，并将确定MREG作为LC3结合伙伴在这一过程中的作用。在具体目标3中，我们的研究重点是了解LAP和MREG介导的OS脂质降解在维持RPE健康中的保护作用。这些研究将为理解LAP依赖过程中的缺陷如何导致疾病进展提供基础工作。

DESCRIPTION (provided by applicant): As phagocytes, retinal pigment epithelial cells function as homeostatic regulators to maintain photoreceptor integrity and preserve visual function. Thus it is advantageous for the post-mitotic RPE cell to utilize catabolic pathways that result in degradation of phagocytosed cargo that under stress can handle ingestion of oxidized toxic substrates. We propose that phagosome maturation in the RPE includes LC3 lipidation in an LC3 associated phagocytic (LAP) process. We hypothesize that these processes are critical in RPE lipid homeostasis by providing a docasahexaenoic acid (DHA; 22:6) pool for Neuroprotectin D1 (NPD1) synthesis to promote RPE cell survival and in turn sustain photoreceptor integrity. In specific aim 1 we will test the hypothesis that RPE phagosomes annex components of the autophagy pathway in LAP and assess the contribution of oxidized outer segments (OS) to this process. In specific aim 2 we hypothesize that melanoregulin (MREG) mediated degradation involves LAP and will determine the role of MREG, an LC3 binding partner, in this process. In Specific Aim 3, we focus our studies on understanding the protective role of LAP and MREG mediated degradation of OS lipids in maintaining RPE health. These studies will provide the ground-work for understanding how deficiencies in LAP dependent processes contribute to disease progression.