CAUSES AND CONSEQUENCES OF ALPHA-SYNUCLEIN AGGREGATION

帕金森病（PD）和相关的路易体疾病与α-突触核蛋白的异常神经元内积累相关。增强α-突触核蛋白聚集倾向的突变导致早发性家族性PD。值得注意的是，大多数患有阿尔茨海默病（AD）的患者也具有α-突触核蛋白免疫反应性路易体，并且其中相当大比例的患者发展出一种无视常规治疗方法的帕金森症形式。这表明，参与AD发病机制的因素可能会促进PD的发展，特别是难治性PD。我们已经表明，淀粉样β肽（Abeta），它在AD发病机制中发挥核心作用，促进细胞内积累的α-突触核蛋白和加速α-突触核蛋白依赖性运动缺陷的α-突触核蛋白/淀粉样前体蛋白转基因小鼠，动物模型，模仿路易体病的方面。然而，这些影响的机制仍然未知。本提案的主要目标是阐明这些机制，并确定阻断Abeta效应是否可能预防或改善PD和其他路易体疾病。在目标1中，我们将确定是否增加神经元α-突触核蛋白的积累和α-突触核蛋白依赖性缺陷的路易体病转基因小鼠模型取决于两个主要的Abeta物种的比例（Abeta 1 -42/Abeta 1 -40）。为此，将α-突触核蛋白转基因小鼠与野生型或突变型人淀粉样前体蛋白（hAPP）转基因小鼠杂交，并进行详细的生化、神经病理学和行为分析。这些实验将通过在用Abeta 1 -42或Abeta 1 -40或两者的混合物处理的α-突触核蛋白转染的细胞细粉中的体外研究来补充。在目标2中，我们将确定神经元α-突触核蛋白的增加是否 路易体病转基因小鼠模型中的α-突触核蛋白累积和α-突触核蛋白依赖性缺陷取决于通过LDL受体相关蛋白（LRP）摄取分泌的Abeta。为此，将表达α-突触核蛋白和野生型或突变型hAPP的小鼠与受体相关蛋白缺陷小鼠杂交，所述受体相关蛋白缺陷小鼠具有降低的LRP表达。这些实验将通过α-突触核蛋白转染细胞系的体外研究进行补充。在目标3中，我们将确定是否可以通过抗氧化剂减少Abeta依赖的α-突触核蛋白聚集和α-突触核蛋白依赖的神经元缺陷。为此，将α-突触核蛋白/hAPP小鼠与超氧化物歧化酶1或2转基因小鼠杂交。这些实验将补充与抗氧化剂处理的突触核蛋白转染细胞系的体外研究。这些实验将阐明AD和PD之间的重叠以及hAPP/Abeta在PD和其他路易体疾病发病机制中的作用。

Parkinson's disease (PD) and related Lewy body diseases are associated with the abnormal intraneuronal accumulation of alpha-synuclein. Mutations that enhance the propensity of alpha-synuclein to aggregate cause early onset familial PD. Notably, the majority of patients with Alzheimer's disease (AD) also have alpha-synuclein immunoreactive Lewy bodies and a substantial proportion of them develop a form of parkinsonism that defies conventional therapeutic approaches. This suggests that factors involved in the pathogenesis of AD might promote the development of particularly recalcitrant forms of PD. We have shown that amyloid beta peptides (Abeta), which play a central role in AD pathogenesis, promote the intracellular accumulation of alpha-synuclein and accelerate alpha-synuclein-dependent motor deficits in alpha-synuclein/amyloid precursor protein transgenic mice, an animal model that mimics aspects of Lewy body disease. However, the mechanisms underlying these effects remain unknown. The main objectives of this proposal are to elucidate these mechanisms and to determine whether blocking Abeta effects might prevent or ameliorate PD and other Lewy body diseases. In Aim 1 we will determine whether the increase in neuronal alpha-synuclein accumulation and in alpha-synuclein-dependent deficits in a transgenic mouse model of Lewy body disease depends on the ratio of the two predominant Abeta species (Abeta1-42/Abeta1-40). For this purpose, alpha-synuclein transgenic mice will be crossed with wildtype or mutant human amyloid precursor protein (hAPP) transgenic mice and detailed biochemical, neuropathological and behavioral analysis will be performed. These experiments will be complemented with in vitro studies in alpha-synuclein-transfected cell fines treated with Abeta1-42 or Abeta1-40 or a mixture of both. In Aim 2 we will determine whether the increase in neuronal alpha-synuclein accumulation and in alpha-synuclein-dependent deficits in a transgenic mouse model of Lewy body disease depends on the uptake of secreted Abeta via the LDL receptor-related protein (LRP). For this purpose, mice expressing both alpha-synuclein and wildtype or mutant hAPP will be crossed with receptor associated protein-deficient mice, which have reduced LRP expression. These experiments will be complemented with in vitro studies in alpha-synuclein-transfected cell lines. In Aim 3 we will determine whether Abeta-dependent alpha-synuclein aggregation and alpha-synuclein-dependent neuronal deficits can be reduced by antioxidants. For this purpose, alpha-synuclein/hAPP mice will be crossed with superoxide dismutase 1 or 2 transgenic mice. These experiments will be complemented with in vitro studies in synuclein-transfected cell lines treated with antioxidants. These experiments will shed light on the overlap between AD and PD and on the role of hAPP/Abeta in the pathogenesis of PD and other Lewy body diseases.