Deconstructing the pathogenic effect of APP in memory circuits

解构APP对记忆回路的致病作用

• 批准号: 9104241
• 负责人: JOANNA L JANKOWSKY
• 金额: $ 47.47万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-15 至 2019-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9104241
• 关键词: Acute; Address; Adult; Affect; Alzheimer' s Disease; Amyloid beta-Protein; Amyloid beta-Protein Precursor; Axon; Behavior; Behavioral; Biochemical; Biological Models; Biology; Brain; Cells; Dendrites; Development; Disease; Electrophysiology (science); Environment; Genetic study; Glutamates; Health; Hippocampus (Brain); Impairment; In Vitro; Injection of therapeutic agent; Interneurons; Learning; Location; Maintenance; Measures; Memory; Modeling; Morphology; Mosaicism; Mus; Neuronal Dysfunction; Neurons; Pathogenesis; Pathway interactions; Pattern; Physiological; Physiology; Population; Positioning Attribute; Preparation; Production; Property; Proteins; Research Design; Role; Seminal; Side; Site; Slice; Source; Structure; Synapses; Synaptic Transmission; System; Testing; Tetanus Helper Peptide; Time; Transgenic Mice; Transgenic Organisms; Variant; Vertebral column; Viral; amyloid pathology; amyloid precursor protein processing; cell type; cognitive function; cognitive performance; density; excitatory neuron; flexibility; grasp; in vivo; inhibitory neuron; mouse model; mutant; neonatal brain; neurogenesis; neuronal circuitry; neuronal excitability; overexpression; postnatal; postsynaptic; postsynaptic neurons; presynaptic; protein expression; research study; selective expression; synaptic function; synaptogenesis; transgene expression; transmission process

 DESCRIPTION (provided by applicant): Genetic studies have demonstrated a central role for the amyloid precursor protein (APP) in Alzheimer's disease, yet we do not understand at a cellular level how this protein contributes to disease. Endogenous APP is found in both excitatory and inhibitory neurons, but whether it exerts greater impact on one than the other has not yet been examined. We lack even a fundamental grasp of whether disease-associated APP variants primarily affect the neuron in which they are expressed, or instead act on neighboring cells within reach of secreted fragments. To address these fundamental questions about the basic biology and pathogenic potential of APP, we have developed a set of model systems that combine precise spatial control over the cells in which APP is expressed with reversible temporal control over when it is active. We will use these models to test our central hypothesis that the impact of pathogenic APP depends on both the timing and location of its expression. Our studies are designed to answer three main questions. In the first aim, we will examine whether pathogenic APP causes distinct impairments in circuit function and cognitive performance when expressed in excitatory vs. inhibitory neurons. We have already characterized the behavioral and hippocampal deficits evoked by excitatory APP expression, and here will create and characterize a mouse model in which APP is limited to GABAergic interneurons for comparison. In our second aim, we will examine how the position of APP-overexpressing cells within the hippocampus affects transmission through the trisynaptic circuit. We will use stereotaxic viral injection to selectively express pathogenic APP within presynaptic CA3 or postsynaptic CA1 neurons to determine which side of the synapse APP acts from and on to impair synaptic transmission in the Schaeffer collateral pathway. Finally, in our third aim, we will determine whether pathogenic APP affects neuronal function through a cell-autonomous or cell-extrinsic manner. We will use viral mosaicism to produce two complementary expression patterns in which isolated APP-overexpressing cells are surrounded by wild-type neurons, or in which isolated wild-type cells are surrounded by APP-overexpressing cells, to test how neuronal physiology is altered by APP expression within the neuron compared to APP expression within its neighbors. By using the tet-off transgenic system to restrict the location of APP in each of these models, we gain the added flexibility to control when it is expressed. This feature will allo us to distinguish the effects of pathogenic APP on synapse formation during postnatal development from its impact on synapse maintenance and plasticity in the adult. Moreover, by acutely arresting pathogenic APP expression in either of these settings, we will identify which physiological or behavioral changes are dependent on continued production of APP/Aß and which are permanent consequences of past exposure.

 描述（由申请人提供）：遗传学研究已经证明淀粉样前体蛋白（APP）在阿尔茨海默氏病中发挥着核心作用，但我们在细胞水平上不了解这种蛋白如何在兴奋性和阿尔茨海默氏病中导致疾病。抑制性神经元，但它是否对一个神经元产生比另一个更大的影响尚未得到检验，我们甚至缺乏对与疾病相关的 APP 变体是否主要影响其表达的神经元或作用于其的基本了解。为了解决有关 APP 的基本生物学和致病潜力的基本问题，我们开发了一套模型系统，它将对 APP 表达的细胞的精确空间控制与对何时表达的可逆时间控制结合起来。我们将使用这些模型来检验我们的中心假设，即致病性 APP 的影响取决于其表达的时间和位置。我们的研究旨在回答三个主要问题。致病性 APP 会导致明显的损伤我们已经描述了兴奋性 APP 表达引起的行为和海马缺陷，这里将创建并描述一个小鼠模型，其中 APP 仅限于 GABA 能中间神经元进行比较。我们的第二个目标是，我们将研究海马体内 APP 过表达细胞的位置如何影响通过三突触回路的传播。我们将使用立体定位病毒注射来选择性表达致病性 APP。最后，在我们的第三个目标中，我们将确定致病性 APP 是否通过细胞自主影响神经元功能。我们将使用病毒嵌合体产生两种互补的表达模式，其中分离的 APP 过表达细胞被野生型神经元包围，或者其中分离的 APP 过表达细胞被野生型神经元包围。野生型细胞被 APP 过表达细胞包围，通过使用 tet-off 转基因系统限制每个神经元中 APP 的位置，以测试神经元内 APP 表达与其相邻细胞内 APP 表达如何改变神经元生理学。通过这些模型，我们可以更加灵活地控制其表达时间。这一特征将使我们能够区分致病性 APP 对出生后发育过程中突触形成的影响与其对成人突触维持和可塑性的影响。通过在这些环境中敏锐地抑制致病性 APP 的表达，我们将确定哪些生理或行为变化依赖于 APP/Aß 的持续产生，哪些是过去接触的永久性后果。