NEURAL REGULATION AND PHYSIOLOGIC ACTIONS OF THE APP FAMILY OF PROTEINS

APP 蛋白质家族的神经调节和生理作用

基本信息

批准号：
6098487
负责人：
Walter J. Koroshetz
金额：
$ 14.43万
依托单位：
MASSACHUSETTS GENERAL HOSPITAL
依托单位国家：
美国
项目类别：
财政年份：
1998
资助国家：
美国
起止时间：
1998-04-01 至 2000-03-31
项目状态：
已结题

项目摘要

The nature of the genetic mutations associated with AD strongly suggest that an abnormality in the expression or processing of the amyloid precursor protein (APP) leads to AD pathology. How might aging itself, which underlies the vast majority of AD cases, lead to a similar pathology? Recent in vitro evidence establishes that secreted fragments of APP, APPS, improve neuronal CA ++ homeostasis and promote neuronal survival; secreted ABeta has opposite effects. A disruption of this balance, between the neurotoxic ABeta and the neuroprotective APPS, now seems a compelling mechanism which might contribute to AD pathology. Homologous proteins, the amyloid precursor-like proteins (APLPs), likely have functional and pathophysiologic roles in APP biology as well. Using electrophysiologic recording techniques, fluorescent Ca++ -indicator dyes and neurotoxicity assays, we have designed experiments to examine how APPs and APLPs and APLPs modulate important processes involved in Ca++ homeostasis including: voltage-dependent calcium channels, robust synaptic activity, glutamate-receptor activation and Ca++ release from internal stores. Since APPs, ABeta, and APLPs are secreted, present in synaptic terminals, modulate intraneuronal [Ca++], and are neuroprotective in excitotoxicity models, we suspect they play an important role in synaptic transmission. To test this, we plan to examine the effects of APPs and APLPs in a model system that exhibits easily controlled synaptic activity. Known mechanisms of APP regulation in non-neural tissues combined with newly found functional properties, strongly suggest that the synthesis and secretion of the APP family of proteins are regulated by inherently neural processes. In this proposal we plan to carefully examine the effects of neurotransmitter-receptor activation, thermal and metabolic neural stress, and activated second messenger systems on APP, APPs, ABeta and APLP synthesis and secretion. Our preliminary data indicate that a variety of physiologically important conditions differentially affect APP, APPs and APLP levels in neurons and glia and their overlying media. Aging-related disorders, like genetic mutations, could alter the functional activity, processing or synthesis of these molecules contributing to AD neurodegeneration. To study effects due to aging itself, we will compare regulatory and functional properties of the APP family of proteins in mature, month old cultures with cultures grown for greater than 6 months. Our goal is to discover how the functional properties and regulation of the various members of the APP family of molecules are coordinated in normal and stressed CNS tissue. Our central hypothesis is that a disorder in this relationship could adversely affect neuronal Ca++ homeostasis and thereby contribute to neurodegeneration in AD.

与 AD 相关的基因突变的性质强烈表明淀粉样蛋白的表达或加工异常前体蛋白 (APP) 导致 AD 病理。衰老本身会如何，这是绝大多数 AD 案例的基础，导致类似的情况病理？最近的体外证据表明分泌的片段 APP、APPS，改善神经元CA++稳态，促进神经元生存；分泌的 Aβ 具有相反的作用。对此的破坏现在，神经毒性 Aβ 和神经保护性 APPS 之间的平衡似乎是一种令人信服的机制，可能有助于 AD 病理学。同源蛋白，淀粉样前体样蛋白（APLP），可能在 APP 生物学中也具有功能和病理生理作用。使用电生理记录技术、荧光 Ca++ 指示剂染料和神经毒性测定，我们设计了实验来检验如何 APP 和 APLP 以及 APLP 调节涉及 Ca++ 的重要过程稳态包括：电压依赖性钙通道，稳健突触活性、谷氨酸受体激活和 Ca++ 释放内部商店。由于 APP、Aβ 和 APLP 是分泌的，因此存在于突触末梢，调节神经元内 [Ca++]，并且是在兴奋性毒性模型中具有神经保护作用，我们怀疑它们发挥了作用在突触传递中发挥重要作用。为了测试这一点，我们计划检查 APP 和 APLP 在模型系统中的影响，该系统表现出容易控制突触活动。非神经组织中 APP 调节的已知机制结合新发现的功能特性强烈表明该合成 APP 家族蛋白的分泌受到固有的调节神经过程。在本提案中，我们计划仔细审查神经递质-受体激活、热和代谢的影响神经应激，并激活 APP、APPs、Abeta 上的第二信使系统以及APLP的合成和分泌。我们的初步数据表明各种重要的生理条件会产生不同的影响神经元和神经胶质细胞及其上覆介质中的 APP、APP 和 APLP 水平。与衰老相关的疾病，如基因突变，可能会改变这些分子的功能活性、加工或合成导致 AD 神经变性。研究衰老造成的影响本身，我们将比较 APP 的监管和功能属性成熟、一个月龄培养物中的蛋白质家族，培养物生长时间为大于6个月。我们的目标是发现功能如何 APP家族各成员的属性和监管分子在正常和应激的中枢神经系统组织中协调。我们的中央假设这种关系出现紊乱可能会产生不利影响神经元 Ca++ 稳态，从而导致神经退行性变广告。