Effects of HSV-1 reactivation from latency on aspects of neural precursor cells neurogenesis and accumulation of Alzheimer's molecular hallmarks

7.摘要 阿尔茨海默病(AD)是导致痴呆的主要神经退行性疾病。原发神经病理 阿尔茨海默病的病变是细胞外的纤维状β-淀粉样多肽(Aβ)斑块和细胞内的神经原纤维 过度磷酸化的tau(p-tau)蛋白的缠结。成人神经发生障碍是一个早期事件 在AD的发展过程中。最近的一项假说(病原体假说)提出，单纯疱疹病毒 单纯疱疹病毒1型(HSV-1)在AD的发病中起重要作用。单纯疱疹病毒1型在小鼠中枢的重新激活结果 神经系统(CNS)是由于神经前体细胞在海马区神经发生受损而导致的认知功能障碍。 单纯疱疹病毒1型感染导致Aβ42积聚在海马区的NPC中，这些小鼠表现出 与淀粉样蛋白-β蛋白积聚有关的神经发生受损。 在目前的提案中，我们的目标是专门调查HSV-1重新激活对 神经干细胞的神经分化与病毒感染细胞中AD分子标志的产生 重新激活。我们提出了以下补充目标：1)分析HSV-1重新激活的效果 在神经发生方面，如神经前体细胞的增殖和分化；2)积聚分析 联合荧光法研究β多肽与单纯疱疹病毒1型激活过程中鼻咽癌细胞tau蛋白的过度磷酸化 原位杂交和免疫组织化学(FISH-IHC)。 补充目标1与阿尔茨海默病相关，因为体内研究表明，在 这是阿尔茨海默病的早期阶段，可能是认知缺陷的至少部分原因。虽然不正常 在HSV-1重新激活的小鼠模型中，已经描述了神经前体细胞的神经发生和认知能力下降，它 目前尚不清楚这些结果是否可归因于鼻咽癌中病毒的重新激活。 补充AIM 2与AD相关，因为从熟悉的阿尔茨海默病小鼠模型中分离出NPC 疾病表现为tau蛋白的过度磷酸化。这个活体模型的结果表明：i)tau 过度磷酸化是神经发生受损的主要因素；ii)Aβ水平似乎不是 影响神经前体细胞神经发生改变的主要因素。然而，最近的一项研究表明，β 在单纯疱疹病毒1型小鼠模型中，神经前体细胞的蓄积是神经发生受损的主要原因 重新激活。然而，值得注意的是，在这项研究中，tau蛋白过度磷酸化 未对NSCs/NPC进行调查。我们建议调查Aβ水平的变化或 在HSV-1重新激活之后过度磷酸化的tau，以及这些AD中的一种水平的增加 在经历HSV-1重新激活的NC中，可能会出现分子特征。

7. ABSTRACT Alzheimer's disease (AD) is the leading neurodegenerative cause of dementia. Primary neuropathological lesions of AD are extracellular plaques of fibrillized β-amyloid (Aβ) peptides and intracellular neurofibrillary tangles of hyper-phosphorylated tau (p-tau) protein. The impairment of adult neurogenesis is an early event in the development of AD. A recent hypothesis (“pathogen hypothesis”) proposes that herpes simplex virus 1 (HSV-1) plays a relevant role in the onset of AD. A consequence of HSV-1 reactivation in murine central nervous system (CNS) is cognition deficits caused by impaired NPCs neurogenesis in the hippocampus. HSV-1 infection results in Aβ42 accumulation in the NPCs in the hippocampus and these mice demonstrate impaired neurogenesis linked to amyloid-β protein accumulation. In the present proposal, we aim to specifically investigate the consequences of HSV-1 reactivation on neuronal differentiation of NPCs and the generation of AD molecular hallmarks in cells undergoing viral reactivation. We propose the following Supplemental Aims: 1) Analysis of the effects of HSV-1 reactivation on aspects of neurogenesis, such as NPCs proliferation and differentiation; 2) Analysis of accumulation of Aβ peptides and hyperphosphorylation of tau in NPCs during HSV-1 reactivation by combined Fluorescent in Situ Hybridization and Immunohistochemistry (FISH-IHC). Supplemental Aim 1 is relevant to AD because in vivo studies suggest that neurogenesis is impaired during early stages of Alzheimer's disease and may underlie, at least in part, cognition deficit. Although abnormal NPCs neurogenesis and cognitive decline have been described in a mouse model of HSV-1 reactivation, it is not known whether these outcomes can be attributed to viral reactivation in NPCs. Supplemental Aim 2 is relevant to AD because NPCs isolated from a murine model of familiar Alzheimer’s disease exhibit hyperphosphorylation of tau. The results from this in vivo model indicate that: i) tau hyperphosphorylation is the main contributor to impaired neurogenesis; ii) Aβ levels do not seem to be the primary factor in the alteration of NPCs neurogenesis. However, a recent study indicates that Aβ accumulation in NPCs is the major contributor to impaired neurogenesis in a murine model of HSV-1 reactivation. Nevertheless, it is important to note that in this study the tau hyperphosphorylation in NSCs/NPCs had not been investigated. We propose to investigate whether altered levels of Aβ or hyperphosphorylated tau follows HSV-1 reactivation and whether the increased levels of one of these AD molecular hallmarks may occur in NPCs undergoing to HSV-1 reactivation.