ApoE Receptor Pathways to Intraneuronal Abeta

ApoE 受体通往神经元内 Abeta 的途径

• 批准号: 7618381
• 负责人: GUOJUN BU
• 金额: $ 29.65万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-05-01 至 2011-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7618381
• 关键词: Alzheimer' s Disease; Amino Acids; Amyloid; Amyloid beta-Protein; Amyloid beta-Protein Precursor; Animal Model; Apolipoprotein E; Binding; Brain; Breeding; Cell surface; Cells; Cellular biology; Cognitive deficits; Complex; Deposition; Embryo; Endocytosis; Event; Family; Goals; In Vitro; Infusion procedures; Knock-out; Knockout Mice; LDL-Receptor Related Protein 1; Lead; Ligands; Low Density Lipoprotein Receptor; Macroglobulins; Mediating; Metabolism; Molecular; Molecular Chaperones; Mus; Neurons; Pathogenesis; Pathway interactions; Peptide Metabolism; Peptides; Play; Process; Production; Prosencephalon; Protein Overexpression; Proteins; Proteolytic Processing; Research Personnel; Role; Testing; Toxic effect; amyloid peptide; amyloid precursor protein processing; design; experience; in vivo; insight; loss of function; member; mouse model; novel; novel therapeutics; programs; protein transport; receptor; receptor mediated endocytosis; secretase; trafficking; uptake

DESCRIPTION (provided by applicant): Intraneuronal amyloid-p peptide (AP) accumulation is an early and toxic event in the pathogenesis of Alzheimer's disease (AD). Understanding cellular mechanisms that accelerate or inhibit intraneuronal A¿ accumulation may provide novel therapeutic strategies for AD. A¿ can accumulate inside neurons via receptor-mediated uptake. It can also accumulate via de novo processing of amyloid precursor protein (APR) to A¿ in the endocytic pathway. Our recent studies have shown that apolipoprotein E (apoE) receptors, members of the low-density lipoprotein receptor (LDLR) family, modulate A¿ uptake as well as APR endocytic trafficking and processing to A¿. In particular, we have demonstrated that LRP overexpression in the brain increases cell-associated A¿. A¿ can bind to apoE receptors either directly or indirectly via A¿ chaperones such as apoE. This proposal will focus on two apoE receptors, the LDLR-related protein (LRP) and LRP1B. These homologous receptors are both highly expressed in neurons and bind multiple ligands including A¿, apoE, and APP. However, evidence from our lab suggests that LRP and LRP1B play opposing roles in ligand endocytosis. While LRP mediates rapid endocytosis, LRP1B endocytoses very slowly and as a consequence, retains ligands at the cell surface. Our overall hypothesis is that LRP facilitates A¿ uptake, p production, and intraneuronal A¿ accumulation, and that LRP1B blocks these effects, thus inhibiting A¿ toxicity and pathogenesis of Alzheimer's disease. We have designed both in vivo and in vitro approaches to test our hypothesis. In Aim 1, we plan to determine the roles of LRP and LRP1B in intraneuronal accumulation in animal models. Because conventional LRP knockout is early embryonic lethal, our lab has generated conditional LRP forebrain-specific knockout mice. Together with the LRP1B knockout mice, we plan to test the roles of LRP and LRP1B in intraneuronal A¿ accumulation after brain A¿ infusion or after breeding with PDAPP amyloid model mice. In Aim 2, we will define the opposing roles of LRP and LRP1B in apoE-dependent and apoE-independent A¿ uptake in primary neurons. Impacts of altered LRP and/or LRP1B expression in neurons on A¿ uptake and intraneuronal accumulation will be assessed in the absence or presence of apoE. In Aim 3, we plan to dissect the mechanisms underlying the opposing roles of LRP and LRP1B in APP endocytic trafficking and A¿ production. Our proposed studies will take advantage of our experience in studying the cell biology of receptor-mediated endocytosis, APP endocytic trafficking, and A¿ metabolism using both in vitro and in vivo approaches. Because recent studies have established the causal role of intraneuronal A¿ in cognitive deficits prior to A¿ plaques, an understanding of the pathways leading to or protecting against intraneuronal AB accumulation may lead to specific targets for AD therapy.

描述（由申请人提供）：神经元内淀粉样β肽（AP）积累是阿尔茨海默氏病（AD）发病机制中的早期毒性事件。了解加速或抑制神经元内 A 积累的细胞机制可能为 AD 提供新的治疗策略。 A¿ 可以通过受体介导的摄取在神经元内积累。它还可以通过在内吞途径中将淀粉样前体蛋白 (APR) 重新加工成 A¿ 来积累。我们最近的研究表明，载脂蛋白 E (apoE) 受体是低密度脂蛋白受体 (LDLR) 家族的成员，可调节 A¿ 的摄取以及 APR 内吞运输和加工为 A¿。特别是，我们已经证明大脑中 LRP 的过度表达会增加细胞相关的 A¿。 A? 可以直接或通过 A? 分子伴侣（例如 apoE）间接与 apoE 受体结合。该提案将重点关注两种 apoE 受体：LDLR 相关蛋白 (LRP) 和 LRP1B。这些同源受体在神经元中高度表达，并结合多种配体，包括 A¿、apoE 和 APP。然而，我们实验室的证据表明，LRP 和 LRP1B 在配体内吞作用中发挥相反的作用。 LRP 介导快速内吞作用，而 LRP1B 内吞作用非常缓慢，因此将配体保留在细胞表面。我们的总体假设是，LRP 促进 A¿ 的摄取、p 产生和神经元内 A 的积累，而 LRP1B 则阻断这些作用，从而抑制 A 的毒性和阿尔茨海默病的发病机制。我们设计了体内和体外方法来检验我们的假设。在目标 1 中，我们计划确定 LRP 和 LRP1B 在动物模型中神经元内积累中的作用。由于传统的LRP敲除是早期胚胎致死的，因此我们实验室培育了条件性LRP前脑特异性敲除小鼠。我们计划与 LRP1B 敲除小鼠一起测试 LRP 和 LRP1B 在脑 A¿ 输注后或与 PDAPP 淀粉样蛋白模型小鼠繁殖后神经元内 A¿ 积累中的作用。在目标 2 中，我们将定义 LRP 和 LRP1B 在初级神经元中依赖于 apoE 和不依赖于 apoE 的 A¿ 摄取中的相反作用。将在apoE不存在或存在的情况下评估神经元中改变的LRP和/或LRP1B表达对A 摄取和神经元内积累的影响。在目标 3 中，我们计划剖析 LRP 和 LRP1B 在 APP 内吞运输和 A¿ 生产中相反作用的机制。我们提出的研究将利用我们在体外和体内方法研究受体介导的内吞作用、APP内吞运输和A¿代谢的细胞生物学方面的经验。由于最近的研究已经确定了神经元内 A¿ 在 A 斑之前的认知缺陷中的因果作用，因此了解导致或防止神经元内 AB 积累的途径可能会导致 AD 治疗的具体目标。