REGULATION OF ALZHEIMER AMYLOID GENERATION BY NEURONS

β-淀粉样蛋白（Abeta）在大脑脆弱区域的沉积是阿尔茨海默病（AD）的一个不变特征。 Abeta是由淀粉样前体蛋白（betaAPP）的调节切割形成的。 主要通过在转染人β APP的克隆细胞系中的研究阐明了β APP的代谢。然而，由于神经元是Abeta的最丰富的来源并且是AD中最受影响的细胞类型，因此神经元中betaAPP代谢和Abeta产生的研究对于阐明AD患者脑中发生的生物学过程将是重要的。 我们的目的是研究内源性加工和细胞内运输的Abeta和betaAPP在啮齿动物原代神经元培养。 此外，我们正在研究β APP加工途径的相对利用率是否以与在细胞系中观察到的神经元培养物中类似的方式进行调节。 已知的β APP代谢调节剂，如蛋白磷酸化和第一信使神经递质信号转导系统，以及性腺激素治疗正在这些皮质培养物中进行评估。 使用放射性测序和代谢标记-质谱，我们最近发现变体AbetaGlu 11肽是神经元分泌的主要Abeta种类。 此外，我们发现用17 β-雌二醇或蛋白磷酸酶抑制剂处理神经元在减少淀粉样蛋白生成性A β肽的分泌方面特别有效。阐明β APP和Abeta在神经元中代谢的分子和细胞过程将为AD的合理治疗策略提供重要信息。

Deposition of beta-amyloid (Abeta) in vulnerable brain regions is an invariable feature of Alzheimer's disease (AD). Abeta is formed by the regulated cleavage of the amyloid precursor protein (betaAPP). The metabolism of betaAPP has been elucidated mainly by studies in clonal cell lines transfected with human betaAPP. However, since neurons are the most abundant source of Abeta and are the most affected cell-type in AD, the study of betaAPP metabolism and Abeta generation in neurons will be important to elucidate the biological processes occuring in the brain of those afflicted by AD. Our objective is to study the endogenous processing and intracellular trafficking of Abeta and betaAPP in rodent primary neuronal cultures. Furthermore, we are investigating whether the relative utilization of processing pathways for betaAPP are regulated in a similar manner in neuronal cultures as has been observed in cell lines. Known regulators of betaAPP metabolism, such as protein phosphorylation and first messenger neurotransmitter signal transduction systems, and gonadal hormone treatment are being assessed in these cortical cultures. Using radiosequencing and metabolic labeling- mass spectrometry, we have recently discovered that variant AbetaGlu11 peptides are principal Abeta species secreted by neurons. Moreover, we have found that treatment of neurons with 17beta-estradiol or protein phosphatase inhibitors are especially effective at reducing secretion of amyloidogenic Abeta peptides. The elucidation of the molecular and cellular processes governing the metabolism of betaAPP and Abeta in neurons will provide important information in the pursuit of rational therapeutic strategies for AD.