Specificity of ABCA7-mediated lipid efflux and its effects on intracellular lipid metabolism in neural cells

项目摘要/摘要 阿尔茨海默病(AD)痴呆症已成为医疗保健系统的主要负担和主要 人类长寿的障碍，尤其是生产性的人类长寿。家族性早发性阿尔茨海默病的遗传学 散发性晚发性阿尔茨海默病患者脑组织的病理改变 经常伴有淀粉样前体蛋白(APP)表达增加的唐氏综合征患者 由于21号染色体的部分三体，ALL指向APP及其切割产物淀粉样蛋白β(Aβ)多肽 AD发病的主要致病因素。然而，其他因素也可能起到一定作用。全基因组 阿尔茨海默病常见遗传易感性的关联研究(GWAS)，遗传学调查 罕见的功能丧失突变和在AD小鼠模型中的研究涉及到ATP结合盒 运输亚家族A成员7(ABCA7)在AD发病中的作用。一种密切相关的蛋白质，三磷酸腺苷结合盒 运输亚家族A成员1(ABCA1)已在GWAS和动物研究中被认为与AD有关。在我们的 初步数据显示，ABCA7蛋白水平低的个体患AD的风险更大 病理学。ABCA1和ABCA7均参与细胞高密度脂蛋白颗粒的形成 脂类。在初步数据中，我们发现ABCA7-和ABCA1-高密度脂蛋白在脂类组成上有显著不同。 最近，我们发表了利用ABCA1提供的范例的改变的脂肪沉积假说。 和另一种ABC A转运蛋白，ABCA4，并提出了神经退行性脂质的存在 在正常生理过程中持续产生，并在不消除时促进AD的发病 神经细胞由ABCA7。ABCA1和ABCA4从特定细胞中清除这些细胞 在正常运行期间积累。本探索性项目的目的是进行比较 ABCA7与ABCA1对神经细胞脂质外流特异性的研究及对脂质沉积预测的检验 阿尔茨海默病的假说认为，在神经组织中，ABCA7介导特定脂质物种的外流(即 神经退行性脂肪)不会被ABCA1显著排出。为了验证这一预测，我们将使用 脂质代谢放射性标记/高效薄层层析(HPTLC)和 多维电喷雾 电离 比较ABCA7和ABCA7的质谱脂组学 ABCA1介导的脂质外流/高密度脂蛋白及其对血管内皮细胞脂质成分的影响 小胶质细胞C20、星形胶质母细胞瘤A172和神经母细胞瘤SK-N的质膜和全细胞 SH细胞可诱导表达ABCA7或ABCA1。

Project Summary/Abstract Alzheimer's disease (AD) dementia has emerged as a major burden on the healthcare system and a major barrier to human longevity, especially productive human longevity. Genetics of familial early-onset AD, pathological changes in the brain of sporadic late-onset AD patients and pathological changes in the brain of individuals with Down syndrome, who frequently have increased expression of amyloid precursor protein (APP) owing to partial trisomy of chromosome 21, all point to APP and its cleavage product amyloid β (Aβ) peptide as major causative factors in AD pathogenesis. However, other factors may also play a role. The genome-wide association studies (GWAS) of the architecture of common genetic predisposition to AD, genetic investigations of rare loss-function mutations and studies in mouse models of AD have implicated ATP-binding cassette transport subfamily A member 7 (ABCA7) in AD pathogenesis. A closely related protein, ATP-binding cassette transport subfamily A member 1 (ABCA1) has been implicated in AD in the GWAS and animal studies. In our preliminary data, we show that individuals with low ABCA7 protein levels have a greater risk for developing AD pathology. Both ABCA1 and ABCA7 mediate formation of high-density lipoprotein (HDL) particles from cell lipids. In preliminary data, we show that ABCA7- and ABCA1-HDL significantly differ in the lipid composition. Recently, we published the altered lipidostasis hypothesis that draws on the paradigms provided by ABCA1 and another ABC A transporter, ABCA4, and poses the existence of a neurodegenerative lipid that continuously arises during normal physiology and promotes AD pathogenesis when it is not eliminated from neural cells by ABCA7. ABCA1 and ABCA4 eliminate from specific cells deleterious lipids that these cells accumulate during normal function. The purpose of the present exploratory project is to conduct comparative ABCA7 vs ABCA1 studies in specificity of lipid efflux in neural cells and to test the prediction of the lipidostasis hypothesis of AD that in the neural tissue ABCA7 mediates efflux of a specific lipid species (i.e., the neurodegenerative lipid) that is not effluxed significantly by ABCA1. To test this prediction, we will use metabolic radioactive labeling of lipids/high performance thin layer chromatography (HPTLC) and multidimensional electrospray ionization `shotgun' mass spectrometry lipidomics to compare ABCA7- and ABCA1-mediated lipid efflux/HDL and the effects that this efflux/HDL formation has on the lipid composition of the plasma membrane and whole cell in microglia C20, astrocyte glioblastoma A172 and neuroblastoma SK-N- SH cells inducibly expressing ABCA7 or ABCA1.