ATP-Binding Cassette Transporter-2 Regulates Amyloid Precursor Protein Dynamics

项目概述：该项目的长期目标是建立atp结合盒转运体-2 （ABCA2）作为淀粉样前体蛋白（APR）蛋白水解加工的新型调节剂。APP的淀粉样变性加工导致a - β肽裂解产物的产生，这与阿尔茨海默病（AD）的病因有关。调控APP加工和Ap产生的机制尚未完全阐明。调控APP加工的一种机制是依赖胆固醇运输的APP定位和在膜室中介导其蛋白水解裂解的关键酶。ABCA2可能调节细胞内胆固醇运输外源脂蛋白来源的胆固醇从内核体/溶酶体到膜室。我们在体外鉴定出ABCA2是APP加工和a - β产生的调节因子。我们确定，在携带APP“瑞典”突变的ABCA2和APP稳定共表达的非神经元HEK293细胞中，细胞APP全蛋白水平和a - β分泌增加。我们还在稳定表达ABCA2的HEK293细胞中使用微阵列分析检测到与AD相关的一些基因的表达增加。尽管有证据表明ABCA2可能是APP代谢的关键调节剂，可能通过调节细胞内胆固醇的运输和分布，我们还没有研究ABCA2功能在表达突变形式APP的转基因小鼠的神经元细胞或大脑中的影响。我们最近生产的ABCA2敲除小鼠和ABCA2转基因小鼠在脑特异性Thy-1启动子的控制下，将允许研究ABCA2转运体在AD转基因小鼠模型中调节APP加工和a - β产生的这种新功能。我们的初步结果使我们提出了一个新的假设，即ABCA2通过调节细胞内胆固醇运输依赖的APP定位和膜室中关键加工酶来调节APP加工和a - β的产生。

DESCRIPTION (provided by applicant): Project Summary: The long-term goals of this project focus on establishing the ATP-binding cassette transporter-2 (ABCA2) as a novel regulator of proteolytic processing of the amyloid precursor protein (APR). Amyloidogenic processing of APP results in the generation of A-beta peptide cleavage products that are implicated in the etiology of Alzheimer's disease (AD). The complete elucidation of the mechanisms that regulate APP processing and Ap production has not been realized. One mechanism that regulates APP processing is the cholesterol trafficking-dependent localization of APP and key enzymes that mediate its proteolytic cleavage in membrane compartments. ABCA2 may function to modulate intracellular cholesterol trafficking of exogenous llpoprotein-derived cholesterol from late-endosomes/lysosomes to membrane compartments. We identified ABCA2 as a regulator of APP processing and A-beta production in vitro. We determined that cellular APP holoprotein levels and A-beta secretion were increased in non-neuronal HEK293 cells that stably co-expressed ABCA2 and APP bearing the APP "Swedish" mutation. We also detected increased expression of a number of genes associated with AD using microarray analysis in HEK293 cells that stably expressed ABCA2. Although evidence suggests that ABCA2 may be a key regulator of APP metabolism, perhaps by regulation of intracellular cholesterol trafficking and distribution, we have not examined the effects of ABCA2 function in either neuronal cells or in the brains of transgenic mice expressing mutant forms of APP. Our recent production of ABCA2 knockout mice and ABCA2 transgenic mice under the control of the brain-specific Thy-1 promoter will permit the investigation of this novel function of the ABCA2 transporter in regulating APP processing and A-beta production in vivo in transgenic mouse models of AD. Our preliminary results have led us to the novel hypothesis that ABCA2 acts to regulate APP processing and A-beta production through modulation of intracellular cholesterol trafficking-dependent localization of APP and key processing enzymes in membrane compartments. Public Health Relevance: These studies may provide novel and mechanistic links between cholesterol metabolism and APP processing that could be of direct clinical relevance. In depth knowledge of the mechanisms of action of the ABCA2 transporter on regulation of APP processing may provide a basis for the development of therapeutic strategies in prevention and treatment of AD.