Deciphering the metabolism of LBPA and its function in the endolysosomal system

解读 LBPA 的代谢及其在内溶酶体系统中的功能

• 批准号: 8802927
• 负责人: Gilbert Di Paolo
• 金额: $ 24万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-01 至 2016-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8802927
• 关键词: Address; Adult; Alzheimer' s Disease; Amyloid beta-Protein; Antibodies; Apolipoproteins; Applications Grants; Autophagocytosis; Biochemical; Biological Assay; Biological Markers; Biology; Blocking Antibodies; Brain region; Cells; Characteristics; Cholesterol; Chronic; Data; Defect; Disease; Employee Strikes; Endosomes; Enzymes; Family; Fluorescence; Frontotemporal Dementia; Functional disorder; Genes; Goals; Hela Cells; Hippocampus (Brain); Hydrolase; In Vitro; Lewy Body Disease; Lipids; Lysosomes; Mass Spectrum Analysis; Mediating; Metabolism; Microscopic; Microscopy; Molecular Genetics; Mus; Mutant Strains Mice; Mutation; Neurodegenerative Disorders; Neurons; Organelles; Parkinson Disease; Pathway interactions; Patients; Peptides; Phospholipids; Physiological; Physiology; Prevention; Process; Proteins; RNA Interference; Reagent; Recombinant Proteins; Role; Sphingolipids; System; Techniques; Technology; Testing; Therapeutic; Tissues; Vesicle; alpha synuclein; base; bis(monoacylglyceryl)phosphate; genome-wide; lipid metabolism; liquid chromatography mass spectrometry; mouse model; mutant; nervous system disorder; public health relevance; synuclein; tau Proteins; tool

DESCRIPTION (provided by applicant): Defects in the endolysosomal system are increasingly viewed as key pathological features of neurodegenerative disorders, such as Alzheimer's disease (AD) and Parkinson's disease. An emerging hypothesis is that chronic endolysosomal defects occurring in these disorders compromise the degradative capacity of lysosomes, causing the aberrant accumulation of a variety of lysosomal cargoes that are targeted to these organelles generally through the endocytic or autophagy pathway. These cargoes not only include a range of aggregate-prone proteins or peptides (e.g., Abeta, aberrant alpha-synuclein and tau), but also lipids, such as cholesterol and sphingolipids. Recently, our lab has employed a systems-based approach called "lipidomics" to profile hundreds of lipids from healthy and diseased tissue using state-of-the-art mass spectrometry. With this technology, we identified a striking lipid alteration in vulnerable brain regions from patients with AD, in a mouse model of Niemann-Pick type C (NPC), an aggressive lysosomal storage disorder that shares some pathogenic processes in common with AD, as well as in other instances where apolipoprotein-derived cholesterol is aberrantly accumulating. This lipid is called lysobisphosphatidic acid (LBPA) or bis(monoacylglycero) phosphate, an atypical phospholipid that is specifically enriched in the multivesicular endosomes and lysosomes, where it is further concentrated on cholesterol-rich intralumenal vesicles (ILVs). LBPA has been previously suggested to promote the formation of ILVs in the endolysosomal compartment, to regulate the storage and distribution of apolipoprotein-derived cholesterol, and facilitate lysosomal degradation by stimulating hydrolases. Together with these studies, our lipidomic data not only identify LBPA as a candidate biomarker for disorders associated with endolysosomal dysfunction, but they also suggest a critical role for this phospholipid both in the physiology and the pathophysiology of these organelles as well as in the administration of apolipoprotein-derived cholesterol. Unfortunately, tools are currently lacking to understand the precise (patho)physiological roles of this endolysosomal lipid and manipulate its levels to assess its therapeutic potential. The primary reason behind this roadblock is that the enzymes mediating the synthesis and degradation of this elusive phospholipid are unknown. The main goals of this proposal are thus (i) to identify the LBPA-metabolizing enzymes and more generally, the genes positively or negatively regulating the levels of LBPA using a combination of genome-wide RNAi screen and lipidomics; and (ii) to assess the impact of various types of LBPA manipulations on lysosomal function in normal neurons as well as in neurons derived from Npc1 mutant mice. We anticipate that our studies will be critical to understand the role of LBPA in endolysosomal physiology with potentially major implications for disorders associated with lysosomal dysfunction.

描述（由申请人提供）：越来越多地将内溶性系统中的缺陷视为神经退行性疾病的关键病理特征，例如阿尔茨海默氏病（AD）和帕金森氏病。一个新兴的假设是，在这些疾病中发生的慢性内溶缺陷型损害溶酶体的降解能力损害，导致通常通过内环或自动途径通常针对这些细胞器的多种溶酶体货物的异常积累。这些货物不仅包括一系列易受蛋白质的蛋白质或肽（例如Abeta，异常α-核蛋白和Tau），还包括脂质，例如胆固醇和鞘脂。最近，我们的实验室使用最先进的质谱法采用了一种基于系统的方法来介绍来自健康和患病组织的数百种脂质。借助这项技术，我们在Niemann-Pick型C（NPC）的鼠标模型中确定了AD患者脆弱的大脑区域的脂质改变，这是一种侵略性的溶酶体储存障碍，与AD共有一些致病过程，在其他情况下，以及其他情况下，以及其他情况下，载脂蛋白蛋白质来源于促脂蛋白的胆固醇均为依赖促脂蛋白。该脂质称为溶血二磷酸（LBPA）或BIS（Monoacylglycero）磷酸盐，一种非典型的磷脂，特异性地富集于多囊体内体和溶酶体中，在那里它进一步浓缩在胆固醇含有胆固醇的内脂肪体内（ILVS）。先前已提出LBPA来促进内溶室中ILV的形成，以调节载脂蛋白衍生的胆固醇的储存和分布，并通过刺激水解酶促进溶酶体降解。与这些研究一起，我们的脂肪组数据不仅将LBPA鉴定为与内溶性功能障碍相关的疾病的候选生物标志物，而且它们还暗示了这种磷脂在这些细胞器的生理学和病理生理学以及这些细胞生理学以及载脂蛋白蛋白蛋白蛋白磷脂蛋白磷脂层酚酚 - 磷脂蛋白磷脂层中的关键作用。不幸的是，目前缺乏了解这种内溶性脂质的确切（病情）生理作用，并操纵其水平以评估其治疗潜力。这种障碍背后的主要原因是介导这种难以捉摸的磷脂的合成和降解的酶是未知的。因此，该提案的主要目标是（i）确定LBPA代谢酶，更普遍地，使用全基因组RNAI筛查和脂肪组的组合对LBPA的水平进行积极或负面调节； （ii）评估各种类型的LBPA操纵对正常神经元以及源自NPC1突变小鼠的神经元中溶酶体功能的影响。我们预计，了解LBPA在内溶性生理学中的作用至关重要，对与溶酶体功能障碍相关的疾病有可能产生重大影响。