ERAB, A BETA, NEUROTOXICITY AND ALZHEIMERS DISEASE

描述（来自申请人的摘要）：越来越多的证据表明淀粉样β肽（Abeta）在阿尔茨海默病（AD）的发病机制中具有致病作用。因此，Abeta影响细胞特性的机制已经得到深入研究。较高浓度的Abeta（1-40/42），出现在AD的后期，形成聚集体和原纤维，非特异性地破坏几乎任何细胞的膜。在AD早期，当存在较低水平的Abeta时，Abeta与特定细胞以及敏感的亚细胞位点的特异性相互作用也可以介导细胞毒性。我们已经确定了一种新的内质网相关的Abeta结合蛋白ERAB，它具有b-羟酰辅酶A脱氢酶/短链醇脱氢酶的特性。重组人ERAB特异性结合Abeta（1-40/42），尽管它不与β-淀粉样前体蛋白（betaAPP）或来自前体的含有C-末端氨基酸的Abeta形式相互作用。ERAB，组成性产生的神经母细胞瘤细胞，与Abeta免疫共沉淀;暴露于外源性Abeta的培养物后，ERAB迅速重新分布到质膜的内部。通过脂质体介导的将阻断性抗ERAB F（ab '）2引入细胞中来防止Abeta对神经母细胞瘤细胞的毒性，并且通过在COS细胞中过表达ERAB来增强Abeta对神经母细胞瘤细胞的毒性。我们认为ERAB是一个关键的细胞内靶点，它增强了Abeta介导的细胞扰动，并最终增强了细胞毒性。我们假设Abeta通过影响ERAB易位到质膜/核膜来影响ERAB，在质膜/核膜处发生以产生毒性醛和触发细胞凋亡的事件为标志的细胞应激诱导。我们的第一个目的是通过分析ERAB-Abeta诱导的毒性醛类和细胞凋亡的产生来确定ERAB酶活性和ERAB与Abeta结合对细胞毒性的贡献。我们的第二个目的是分析ERAB的贡献，以A β诱导的细胞应激转基因小鼠，我们假设，有针对性的过度表达ERAB的小鼠将显示夸大的细胞毒性在A β丰富的环境，这将进一步加剧缺血性应激。这项工作的长期目标是确定ERAB是否是Abeta细胞毒性的重要细胞辅因子，以评估ERAB的抑制是否可能是未来药物开发的新神经保护策略。

DESCRIPTION (from applicant's abstract): Increasing evidence points to a causative role for amyloid-beta peptide (Abeta) in the pathogenesis of Alzheimer's disease (AD). Thus, mechanisms through which Abeta affects cellular properties have come under intensive study. Higher concentrations of Abeta(1-40/42), present later in the course of AD, form aggregates and fibrils which nonspecifically damage membranes of virtually any cell. Earlier in AD, when lower levels of Abeta are present, specific interactions of Abeta with particular cells, as well as sensitive subcellular loci, could also mediate cellular toxicity. We have identified a novel endoplasmic reticulum-associated Abeta binding protein termed ERAB which has properties of a b-hydroxyacyl-Coenzyme A dehydrogenase/short-chain alcohol dehydrogenase. Recombinant human ERAB binds Abeta(1-40/42) specifically, though it does not interact with beta-amyloid precursor protein (betaAPP) or forms of Abeta containing C-terminal amino acids from the precursor. ERAB, constitutively produced by neuroblastoma cells, was co-immunoprecipitated with Abeta; following exposure of cultures to exogenous Abeta, ERAB was rapidly redistributed to the inner aspect of the plasma membrane. Toxicity of Abeta to neuroblastoma cells was prevented by liposome-mediated introduction of blocking anti-ERAB F(ab')2 into the cells, and was enhanced by overexpression of ERAB in COS cells. We propose that ERAB is a critical intracellular target potentiating Abeta-mediated cellular perturbation and, ultimately, cytotoxicity. We hypothesized that Abeta influences ERAB by effecting ERAB translocation to the plasma/nuclear membrane, where induction of cell stress, marked by generation of toxic aldehydes and events triggering apoptosis, occurs. Our first aim is to determine the contribution of ERAB enzymatic activity and ERAB binding to Abeta on cytotoxicity by analyzing ERAB-Abeta-induced generation of toxic aldehydes and apoptosis. Our second aim is to analyze the contribution of ERAB to Abeta-induced cell stress using transgenic mice; we hypothesize that mice with targeted overexpression of ERAB will display exaggerated cytotoxicity in an Abeta-rich environment, and that this will be further exacerbated by ischemic stress. The long-term goal of this wok is to determine if ERAB is an important cellular cofactor for Abeta cytotoxicity, in order to assess whether inhibition of ERAB might be a novel neuroprotective strategy for future drug development.