Changes in Water Channel Localization to Astrocytic Endfeet with Aging

项目摘要 阿尔茨海默病(AD)是一种与年龄相关的神经退行性疾病，是痴呆症的首要原因和第六位 在美国的死因。它的病理特征是淀粉样蛋白(Aβ，Aβ)多肽积聚。在……里面 对于健康的大脑，有几种机制有助于在病原体积累之前清除Aβ。这些工具的功能 随着个人年龄的增长，清除机制会恶化。为AD患者制定有效的治疗策略， 重要的是要了解驱动Aβ清除的机制，以及它们在老年人中功能障碍的来源 大脑。 先前的研究表明，最近描述的淋巴系统就是β中涉及的一种机制 这也表明了与年龄相关的功能障碍。正确的淋巴功能有赖于脑脊液的混合 脑脊液(CSF)和间质液(ISF)沿整个大脑的血管周围间隙。这一过程是由 覆盖脑血管的星形胶质细胞间的水流量。水通道水通道蛋白-4(AQP4)支持这一点 水通量，并高度定位于健康大脑中血管周围星形细胞终末足，但在 大脑老化，患有老年痴呆症。最近的研究表明，在AD的转基因小鼠模型中，Aqp4的缺失 小鼠的基因增加了Aβ斑块的积累，并加剧了认知障碍。在老年小鼠和患有阿尔茨海默病的人类中， 在维持AQP4整体表达的同时，AQP4在血管周围的定位丢失。重要的是，无论失去 在衰老的大脑中看到的AQP4的末端定位促进Aβ的积累，其方式与在 目前尚不清楚Aqp4基因敲除小鼠。 这项建议的目的是确定血管周围水通道蛋白4定位缺失在Aβ积聚中所起的作用。 并确定有助于调节AQP4血管周围定位和分解的细胞机制 老化的大脑。在目标1中，我将使用小鼠模型评估血管周围定位丢失对β清除的影响 这两个特点都缺乏血管周围水通道蛋白4定位和自发的Aβ斑块形成。在目标2中， 提案I将研究dystrophin相关复杂蛋白的变化是否调节血管周围AQP4 衰老大脑中的定位，以及它们表达的丧失如何影响β斑块负担。在目标3中，我将调查一个 AQP4本地化的第二种候选调控机制，使用 星形胶质细胞特异性病毒过度表达范例，以分离每个AQP4亚型的作用。 这项研究将首次确定与年龄相关的星形细胞血管周围AQP4定位缺失的后果。 此外，它还将是第一批研究血管周围AQP4定位变化的机制之一 在活体内。这项研究的结果将为AQP4作为AD和其他疾病的潜在治疗靶点提供洞察力 包括帕金森氏症和亨廷顿病在内的蛋白质聚集物积聚的神经病理学。

Project Summary Alzheimer's disease (AD) is an age-linked neurodegenerative disease that is the leading cause of dementia and 6th leading cause of death in the United States. It is characterized pathologically by the accumulation of amyloid β (Aβ) peptides. In the healthy brain, several mechanisms facilitate clearance of Aβ prior to pathogenic accumulation. The function of these clearance mechanisms deteriorates as an individual ages. To develop effective therapeutic strategies for patients with AD, it is important to understand the mechanisms that drive Aβ clearance, and the source of their dysfunction in the aged brain. Previous research has shown that the recently described glymphatic system is one such mechanism involved in Aβ clearance that also demonstrates age-linked dysfunction. Proper glymphatic function relies on mixing of cerebrospinal spinal fluid (CSF) with interstitial fluid (ISF) along perivascular spaces throughout the brain. This process is mediated by water flux across astrocytes that ensheathe the brain vasculature. The water channel aquaporin-4 (AQP4) supports this water flux, and is highly localized to perivascular astrocytic endfeet in the healthy brain, but loses this localization in the aging brain and with AD status. Recent research has shown that in a transgenic mouse model of AD, deletion of the Aqp4 gene in mice increases Aβ plaque accumulation and worsens cognitive impairment. In aging mice and humans with AD, while overall expression of AQP4 is maintained, perivascular AQP4 localization is lost. Importantly, whether the loss of endfoot localization of AQP4 seen in the aging brain promotes accumulation of Aβ in a similar manner to that seen in Aqp4 knockout mice is not known. The goal of this proposal is to determine the role that loss of perivascular AQP4 localization plays in Aβ accumulation, and identify cellular mechanisms that contribute to the regulation of AQP4 perivascular localization and break down in the aging brain. In Aim 1, I will assess the effect of loss of perivascular localization on Aβ clearance using a mouse model that features both a lack of perivascular AQP4 localization and spontaneous Aβ plaque formation. In Aim 2 of the proposal I will investigate whether changes in dystrophin associated complex proteins regulate perivascular AQP4 localization in the aging brain, and how loss of their expression impacts Aβ plaque burden. In Aim 3 I will investigate a second candidate regulatory mechanism for AQP4 localization, the expression of alternate AQP4 isoforms using an astrocyte-specific viral overexpression paradigm to isolate the role of each AQP4 isoform. This study will be the first to define the consequences of age-linked loss of astrocytic perivascular AQP4 localization. Additionally it will be one of the first to examine the mechanisms underlying changes in perivascular AQP4 localization in vivo. The results of this study will provide insight into AQP4 as a potential therapeutic target for AD and other neuropathologies that demonstrate an accumulation of protein aggregates including Parkinson's and Huntington's disease.