Microsomal Transfer Protein Modulates Lipoprotein Metabolism and Retinal lipid Homeostasis

微粒体转移蛋白调节脂蛋白代谢和视网膜脂质稳态

• 批准号: 10372593
• 负责人: Kathleen Boesze-Battaglia
• 金额: $ 25.49万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-03-01 至 2024-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10372593
• 关键词: ATP binding cassette transporter 1; Ablation; Acids; Address; Aging; Apical; Apolipoproteins; Apolipoproteins B; Blindness; Bruch' s basal membrane structure; Cardiac Myocytes; Cell Culture System; Cell Culture Techniques; Cell physiology; Cells; Characteristics; Cholesterol; Cholesterol Homeostasis; Choroid; Complex; Consequentialism; Deposition; Development; Disease; Endoplasmic Reticulum; Energy-Generating Resources; Enterocytes; Equilibrium; Fatty Acids; Foundations; Functional disorder; Gatekeeping; Genes; Genetic; Health; Hepatocyte; Homeostasis; Human; Inflammation; Inflammatory; Inflammatory Response; Ingestion; Intracellular Accumulation of Lipids; Lead; Lesion; Lipids; Lipoproteins; Liver; Low-Density Lipoproteins; Mediating; Metabolic; Metabolism; Missense Mutation; Mitotic; Morphology; Mouse Protein; Neural Retina; Pathologic; Pathway interactions; Patients; Phagocytosis; Pharmacology; Plasma; Play; Process; Production; Protein Deficiency; Proteins; Recycling; Regulation; Retina; Retinal Degeneration; Retinal Diseases; Retinal Pigments; Role; Secondary to; Structure of retinal pigment epithelium; System; Testing; Toxic effect; Vision; age related; cholesterol transporters; density; environmental stressor; human fetal retinal pigment epithelial cell; in vivo; induced pluripotent stem cell; lipid metabolism; lipid transfer protein; mouse model; negative affect; normal aging; novel; oxidation; prevent; protein function; western diet

Lipid handling is one of the most critical functions of the retinal pigment epithelium (RPE) a single mitotically inactive cell layer that is situated between the neural retina and the Bruch's membrane-Choroid. Visual function depends on the intimate structural, functional and metabolic interactions between the RPE and the neural retina. Within this complex, lipid metabolism is tightly regulated, and its' dysregulation triggers accumulation of excess lipids within the RPE and the adjacent Bruch's membrane and choroidal vasculature. In the human retina the accumulation of neutral lipid deposits is a characteristic of aging and precedes disease associated-lesions. A significant proportion of this neutral lipid is enclosed within apolipoprotein B100 containing lipoproteins (Blps) that resemble cardiomyocyte associated Blps. The prodigious amount of lipid that must be processed by the RPE, through the recycling and metabolism of lipid rich outer segments and ingestion of circulating lipoproteins, predicts that to prevent lipid overload the RPE synthesize and secrete Blp. In this regard, RPE shares metabolic similarity with cardiomyocytes; both utilize fatty acids as an energy source and both secrete unique EC rich Blps. While it has been shown that MTP-mediated secretion of Blps protects cardiomyocytes from lipid accumulation, there is a paucity of studies regarding Blp assembly/secretion by RPE in vivo. In these studies we will use mouse models and cell culture to decipher the pathological consequences associated with dysregulation of Blp assembly and secretion pathway by inhibiting or genetic ablation of the Mttp gene in RPE. Microsomal transfer protein (MTP), the product of the MTTP gene, is an endoplasmic reticulum-resident lipid transfer protein necessary for Blp assembly and secretion. In the first specific aim we will test the hypothesis that MTP-mediated secretion of Blp is a mechanism for protecting against RPE lipid overload. To test the contribution of localized synthesis and secretion of Blp by the RPE to retinal lipid homeostasis and cell function in a metabolically intact system, we generated the RPE-specific MTP deficient (RPEMttp) mouse. In the second specific aim we will test the hypothesis that Blp assembly is modulated by the daily load of ingested OS lipids. We will use RPE differentiated from human induced pluripotent stem cells (iPSCs) to investigate the mechanism by which lipids taken up through outer segment phagocytosis regulate MTP activity and Blp production. Using these cells, we will determine if loss of MTP, either through gene ablation (KD of MTP in iRPE) or pharmacological inhibition, contributes to RPE steatosis. Collectively, these exploratory studies will address the specific role of local Blp assembly in retinal lipid homeostasis. Dysregulation of Blp function can cause non- autonomous changes that negatively affect the entire system and lead to vision loss. These studies maybe foundational to study subsequent steps in the development of age-related changes such as inflammation and degeneration associated with dysregulation of lipoprotein metabolism.

脂质处理是视网膜色素上皮（RPE）的最关键功能之一 位于神经视网膜和Bruch的膜 - 舌之间的无活性细胞层。视觉功能 取决于RPE和神经视网膜之间的亲密结构，功能和代谢相互作用。 在这种复合物中，脂质代谢受到严格调节，其功能障碍会触发过量的积累 RPE内的脂质以及相邻的Bruch膜和脉络膜脉管系统。在人类视网膜中 中性脂质沉积物的积累是衰老的特征，并且是疾病相关的衰老。一个 这种中性脂质的显着比例被封闭在载脂蛋白B100中，含有脂蛋白（BLP） 这类似于心肌细胞相关的BLP。必须处理的大量脂质 RPE通过富含脂质外部片段的回收和代谢，摄入循环脂蛋白的摄入 预测，以防止脂质超载RPE合成和秘密BLP。在这方面，RPE分享了代谢 与心肌细胞相似；两者都利用脂肪酸作为能源，都是秘密独特的EC富含BLP。 虽然已显示MTP介导的BLPS分泌可保护心肌细胞免受脂质积累的影响，但 RPE在体内关于BLP组装/分泌的研究很少。在这些研究中，我们将使用鼠标 模型和细胞培养以破译与BLP失调相关的病理后果 通过抑制RPE中MTTP基因的遗传消融来组装和分泌途径。微粒体转移 蛋白质（MTP）是MTTP基因的乘积，是一种内质网居住的脂质转移蛋白 BLP组装和分泌所必需的。在第一个特定目的中，我们将测试MTP介导的假设 BLP的分泌是防止RPE脂质超负荷的机制。测试本地化的贡献 RPE将BLP的合成和分泌到代谢完整的视网膜脂质稳态和细胞功能 系统，我们生成了RPE特异性MTP缺陷（RPEMTTP）鼠标。在第二个特定目标中，我们将 测试BLP组件的假设是通过每日摄入的OS脂质负载调节的。我们将使用RPE 与人类诱导的多能干细胞（IPSC）区分开来研究脂质的机制 通过外部段吞噬作用占据，调节MTP活性和BLP产生。使用这些细胞，我们 将通过基因消融（IRPE中的MTP的KD）或药理抑制作用确定MTP的丧失，或 有助于RPE脂肪变性。总的来说，这些探索性研究将解决本地BLP的具体作用 视网膜脂质稳态中的组装。 BLP功能的失调可能会导致非自主变化 负面影响整个系统并导致视力丧失。这些研究可能是为了研究的基础 与年龄相关变化的发展的随后步骤，例如创新和变性 脂蛋白代谢失调。