Proteolysis of apoE and Alzheimer's pathology

描述(申请人提供)：尽管最近收集了大量与阿尔茨海默病相关的遗传和环境风险因素的新信息，但对于导致神经病理的关键途径仍未达成共识。主导当前许多研究工作的“淀粉样假说”既有长处，也有短处。淀粉样蛋白的假设作用特别有争议的一个方面是，它在多大程度上是神经元退化的直接原因，而不是参与最终导致神经元功能障碍和死亡的一连串事件。与AD有关的蛋白质的其他遗传风险因素包括载脂蛋白E(ApoE)，越来越多的证据表明apoE4可能直接参与AD的神经病理。特别是，apoE4已被证明在体外表现出神经毒性作用。这种毒性可能与蛋白质分解生成一种缩短形式的apoE(截断的apoE)有关，这种apoE在AD脑组织中更为丰富。此外，一些证据表明，apoE的C-末端片段与淀粉样蛋白结合，并与淀粉样蛋白共定位。本文提出的工作将检验载脂蛋白E的蛋白分解片段对神经病理和淀粉样蛋白沉积的影响这一假说。免疫组织化学、生物化学和组织培养相结合的研究将用于：检测载脂蛋白E在人脑和转基因小鼠脑中的蛋白分解程度；确定载脂蛋白E的细胞来源及其在中枢神经系统中的蛋白分解；研究特定受体在载脂蛋白E神经毒性中的作用；研究C端载脂蛋白E对ABeta聚集和活性的影响；以及在AD病理部位定位载脂蛋白E片段。我们的目标是寻找证据支持或反对载脂蛋白E蛋白分解有助于AD病理这一主要假说。

DESCRIPTION (provided by applicant): Although abundant new information has recently been collected on the genetic and environmental risk factors associated with Alzheimer's disease, there is still no consensus on the critical pathway leading to neuropathology. The "amyloid hypothesis", which dominates much current research effort, has both strengths and weaknesses. One aspect of the postulated role for amyloid that is particularly contentious is the extent to which it is a direct cause of neuronal degeneration, as opposed to participating in a cascade of events that ultimately leads to neuronal dysfunction and death. Other genetic risk factors for proteins involved in AD include apolipoprotein E (apoE) and there is accumulating evidence that apoE4 may directly contribute to AD neuropathology. In particular, apoE4 has been shown to exhibit neurotoxic effects in vitro. This toxicity may be associated with proteolytic generation of a shortened form of apoE (truncated apoE), which is more abundant in AD brain tissue. In addition, several lines of evidence suggest that a C-terminal fragment of apoE binds to, and co-localizes with, amyloid. The work proposed here will examine the hypothesis that proteolytic fragments of apoE contribute to both neuropathology and amyloid deposition. A combination of immunohistochemical, biochemical, and tissue culture studies will be used to: examine the extent of apoE proteolysis in human brain and apoE transgenic mouse brain; identify the cellular source of apoE and its proteolysis in the CNS; study the role of specific receptors in apoE neurotoxicity; study the effect of C-terminal apoE on ABeta aggregation and activity; and localize apoE fragments at sites of AD pathology. The goal is to pursue evidence in support or against the major hypothesis that proteolysis of apoE contributes to AD pathology.