Neuronal dysfunction caused by Abeta inhibition of MT motors

描述（由申请人提供）：微管（MT）功能障碍、神经毒性、染色体错误分离和神经元可塑性缺陷都是由A -肽诱导的，并与阿尔茨海默病（AD）的发病机制有关。我们最近的数据支持一个统一的假设，即A¿诱导的病理部分是由A¿抑制特定的MT电机引起的，我们建议验证这一假设及其含义。微管是ATP驱动的运动蛋白将关键细胞成分（如蛋白质、囊泡、染色体和大分子，包括微管本身）从细胞的一部分移动到另一部分的高速公路。许多神经退行性疾病显示微管运输系统的缺陷，强调其在正常细胞生理中的重要性。先前，我们发现在AD患者、tg小鼠和培养细胞中，引起家族性AD的淀粉样前体蛋白和早老素突变基因诱导染色体错分离和非整倍体，这一过程与微管功能密切相关。其他实验室的验证结果表明，早期AD皮层中30%的神经元是非整倍体/超二倍体。最近，我们发现在人类细胞或爪蟾卵提取物中添加A¿后，会损害有丝分裂纺锤体的形成和稳定性，并直接抑制三种微管运动驱动蛋白Eg5、KIF4A和MCAK，这三种微管运动驱动蛋白对有丝分裂纺锤体的正常结构和功能至关重要，值得注意的是，它们也存在于神经元中。特别是，Eg5在APP/PS转基因小鼠（一种阿尔茨海默病模型）大脑提取物中的活性严重降低，在a¿处理的神经元中被抑制，并且含有增加AD风险的多态性。化学抑制Eg5会导致有丝分裂缺陷、NMDA受体远离质膜的错误定位以及LTP的抑制。A对LTP的负面影响，以及我们关于其对微管功能影响的新数据表明，A对阿尔茨海默病记忆过程的抑制可能部分源于其对特定运动蛋白的抑制，这可能会破坏神经发生和神经可塑性。通过测定细胞、小鼠脑切片培养物和成年小鼠暴露于Eg5和/或A¿on 1的化学抑制剂的影响。神经毒性,2。2 .切片培养的LTP；在成年小鼠的学习和记忆以及AD样神经病理中，所提出的实验将使我们能够得出阿尔茨海默病中阿尔茨海默病A肽抑制某些微管运动的能力是否对其破坏神经发生和神经元功能起重要作用，以及这种运动抑制是否构成阿尔茨海默病治疗的新靶点。

DESCRIPTION (provided by applicant): Microtubule (MT) dysfunction, neurotoxicity, chromosome mis-segregation, and defective neuronal plasticity are all induced by A¿ peptide and implicated in Alzheimer's disease (AD) pathogenesis. Our recent data support the unifying hypothesis that A¿-induced pathologies are caused in part by A¿ inhibiting specific MT motors, and we propose to test this hypothesis and its implications. Microtubules serve as the highways upon which ATP driven motor proteins move key cellular components such as proteins, vesicles, chromosomes and large macromolecules, including microtubules themselves, from one part of the cell to another. Many neurodegenerative diseases show defects in the microtubule transport system, underlining its importance in normal cellular physiology. Previously, we found that in AD patients, tg mice, and cultured cells, mutant amyloid precursor protein and presenilin genes that cause familial AD induce chromosome mis-segregation and aneuploidy, processes that are intimately involved with microtubule function. Confirmatory results from other labs showed that 30% of neurons in early AD cortex are aneuploid/ hyperdiploid. Recently, we found that after addition to human cells or Xenopus egg extracts, A¿ impairs the formation and stability of mitotic spindles and directly inhibits three microtubule motor kinesins, Eg5, KIF4A and MCAK, which are essential for the normal structure and function of the mitotic spindle, and, remarkably, are also present in neurons. In particular, Eg5 has severely reduced activity in extracts from brains of the APP/PS transgenic mice, a model of Alzheimer's disease, is inhibited in neurons treated with A¿, and harbors polymorphisms that increase AD risk. Chemical inhibition of Eg5 results in mitotic defects, mis-localization of the NMDA receptor away from the plasma membrane, and inhibition of LTP. A¿snegative impacton LTP, together with our new data regarding its influence on microtubule function, suggests that A¿ inhibition of memory processes in AD may derive in part from its inhibition of specific kinesins, which can disrupt both neurogenesis and neuroplasticity. By determining the effects of exposing cells, mouse brain slice cultures, and adult mice to chemical inhibitors of Eg5 and/or to A¿ on 1. Neurotoxicity, 2. LTP in slice cultures, and 3. learning and memory and AD-like neuropathology in adult mice, the proposed experiments will allow us to conclude whether or not the ability of the Alzheimer A¿ peptide to inhibit certain microtubule motors contributes importantly to its disruption of neurogenesis and neuronal function in Alzheimer's disease and whether such motor inhibition constitutes a novel target for AD therapy.