NEURAL REGULATION AND PHYSIOLOGIC ACTIONS OF THE APP FAMILY OF PROTEINS

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， 这是绝大多数AD病例的基础，导致类似的 病理学 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CA ++稳态， 存活;分泌的ABeta具有相反的效果。 破坏这一点 平衡，在神经毒性ABeta和神经保护APPS之间，现在 似乎是一个令人信服的机制，可能有助于AD病理。 同型半胱氨酸蛋白，淀粉样蛋白受体样蛋白（APLPs），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++指示染料 和神经毒性分析，我们设计了实验来研究如何 APPs和APLPs和APLPs调节Ca++参与的重要过程 稳态包括：电压依赖性钙通道，稳健 突触活动、谷氨酸受体激活和Ca++释放 内部存储。 由于APPs、ABeta和APLPs是分泌的，存在于 突触终末，调节神经元内[Ca++]， 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 在突触传递中的重要作用。 为了验证这一点，我们计划 在一个模型系统中研究杀伤人员地雷和杀伤人员地雷的影响， 易于控制的突触活动。 非神经组织中APP调节的已知机制与 新发现的功能特性，强烈表明，合成 APP家族蛋白质的分泌受固有的 神经过程 在这份提案中，我们计划仔细研究 神经递质-受体活化、热和代谢的影响 神经应激和激活的第二信使系统对APP，APP，ABeta 以及APLP的合成和分泌。 我们的初步数据显示， 各种生理上重要的条件不同地影响 神经元和神经胶质及其上覆介质中的APP、APP和APLP水平。 与衰老有关的疾病，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 为了研究由于衰老 本身，我们将比较APP的监管和功能属性 蛋白质家族在成熟的，月龄的培养物中， 超过6个月。 我们的目标是发现 APP家族的各种成员的特性和调节 分子在正常和应激的CNS组织中是协调的。 我们的中央 一种假设是，这种关系中的障碍可能会对 神经元Ca++稳态，从而有助于神经变性， AD.

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.