Cerebral Amyloidosis and Dementia

描述（由申请人提供）：AB在AD的发病机制中起着核心作用，尽管仍然非常需要完全确定多个AB组合中的哪一个是神经毒性和淀粉样蛋白形成能力的基础。虽然纤维结构以上的可溶性低聚物与神经元毒性的机制有关，但很少有体内实验和我们自己最近的数据表明，在APP转基因小鼠中，脑内灌注可溶性AD脑提取物可以加速AB淀粉样蛋白的形成，但不同聚集状态下的同源合成肽却不能达到相同的程度，这表明存在尚未确定的淀粉样蛋白形成辅助因子。两种早发性神经退行性疾病，家族性英国和丹麦痴呆（FBD和FDD）表现出广泛的前淀粉样蛋白和淀粉样蛋白沉积，嗜血性血管病和神经原纤维缠结病理，与AD非常相似。然而，沉积的蛋白质（FBD中的ABri和FDD中的ADan）在长度和初级结构上与AB不同，然而，所有物种都有很大的寡聚化倾向，在脂质双层中聚集成离子通道样结构并形成原纤维，所有这些都表明了共同的致病途径。我们假设不相关的肽可以采用类似的改变淀粉样蛋白结构，在神经元细胞中引发类似的下游有害影响，当与其他淀粉样蛋白生成辅助因子结合时，能够加速体内淀粉样蛋白沉积。因此，我们提出：目的1：比较从FBD / FDD / AD的大脑和Tg小鼠模型中分离的低聚和纤维状ABri、ADan和AB组装体，确定合成ABri、ADan和AB的结构要求，以形成体外与体内相似的组装体；目标2:为了测试目的1中描述的低聚和纤维状ABri和ADan物种与类似AB结构的功能影响，比较其不同的神经毒性潜力，评估在体内和体外模式下诱导特定的细胞死亡机制（激活引发剂和效应剂半胱氨酸酶，线粒体途径，Ca2+失调等）。用富含寡聚物的组织组分以及在淀粉样蛋白缺失的组织提取物中重组的合成同源物来验证结果；目标3:(a)分析低聚物/纤维AB的外源性淀粉样蛋白生成能力；在APP和ADanPP Tg动物体内的ABri和ADan物种，使用海马内注射脑提取物与在存在/不存在淀粉样蛋白缺失的脑提取物的情况下具有类似寡聚化的合成同源物进行比较，(b)对淀粉样蛋白诱导提取物进行比较蛋白质组学分析，以确定常见的翻译后修饰和/或负责淀粉样蛋白诱导活性的其他辅助因子。公共卫生相关性：大量实验数据强烈提示β淀粉样蛋白（AB）在阿尔茨海默病（AD）中起核心作用，尽管发病机制的基本问题仍不清楚，特别是低聚物的作用和该疾病的淀粉样原性辅助因子的存在。为了澄清这些问题，我们建议研究两种与AD非常相似的早发性非ab神经退行性疾病：家族性英国和丹麦痴呆。将这些替代的神经退行性变模型与阿尔茨海默病病例进行密切比较，将有助于阐明不同的淀粉样蛋白是否会触发共同的致病机制，并可能适用于类似的治疗策略。

DESCRIPTION (provided by applicant): AB plays a central role in AD pathogenesis, although there is still a great need to fully define on which of the multiple AB assemblies underlay the neurotoxic properties and the amyloid-forming ability. While soluble oligomers more than fibrillar structures have been implicated in the mechanism(s) of neuronal toxicity, few in vivo experiments and our own recent data indicate that seeding of AB amyloidogenesis in APP transgenic mice can be accelerated by intracerebral infusion of soluble AD brain extracts but not to the same extent by homologous synthetic peptides in various states of aggregation, suggesting the existence of still undefined amyloidogenic co-factors. Two early-onset neurodegenerative conditions, familial British and Danish dementias (FBD and FDD) show extensive pre-amyloid and amyloid deposits, congophilic angiopathy and neurofibrillary tangle pathology, closely resembling AD. The deposited proteins (ABri in FBD and ADan in FDD), nevertheless, differ from AB in length and in primary structure and yet, all species share great propensity to oligomerize, assemble as ion-channel like structures in lipid bi-layers and form fibrils, all suggestive of common pathogenic pathways. We hypothesize that unrelated peptides could adopt similar altered amyloidogenic configurations that trigger comparable downstream detrimental effects in neuronal cells, being capable of accelerating amyloid deposition in vivo when in conjunction with additional amyloidogenic co-factors. Accordingly, we propose: Aim 1: to compare oligomeric and fibrillar ABri, ADan and AB assemblies isolated from brains with FBD / FDD / AD as well as from Tg mouse models and determine the structural requirements for synthetic ABri, ADan and AB to form in vitro similar assemblies to those found in vivo; Aim 2: to test the functional effect of the oligomeric and fibrillar ABri and ADan species characterized in aim 1 in comparison with analogous AB structures on their differential neurotoxic potential, assessing the induction of specific cell-death mechanisms (activation of initiator and effector caspases, mitochondrial pathways, Ca2+ dysregulation, etc) in ex vivo and in vitro paradigms, validating the results with tissue fractions enriched in oligomeric assemblies as well as synthetic homologues reconstituted in amyloid-depleted tissue extracts; Aim 3: to (a) analyze the exogenous amyloidogenic capability of oligomeric/fibrillar AB, ABri and ADan species in vivo in APP and ADanPP Tg animals using intra-hippocampal injections of brain extracts compared with synthetic homologues with analogous oligomerization in the presence/absence of amyloid-depleted brain extracts and (b) conduct a comparative proteomic analysis of the amyloid-inducing extracts to identify common post-translational modifications and/or additional co-factor(s) responsible for the amyloid-inducing activity. PUBLIC HEALTH RELEVANCE: There is extensive experimental data strongly suggesting that amyloid beta (AB) plays a central role in Alzheimer's disease (AD) although basic questions in the pathogenetic mechanisms remain unclear, particularly the role of oligomers and the existence of amyloidogenic co-factors of the disease. To clarify these issues we propose to study two early-onset non-AB neurodegenerative conditions that closely resemble AD: familial British and Danish dementias. The use of these alternative models of neurodegeneration in close comparison with AD cases will help elucidate whether different amyloids trigger common pathogenic mechanisms and are potentially amenable to similar therapeutics strategies.