ADF/cofilin-actin rods in neurodegenerative diseases

描述(申请人提供)：在几乎所有培养的海马神经元的神经突起中，短暂的ATP耗竭迅速诱导出主要由肌动蛋白和ADF/cofilin(AC)组成的杆状结构。杆形成，它隔离了肌动蛋白的一部分，但几乎所有的AC，对应激神经元是暂时有益的，因为它节省了与肌动蛋白周转相关的ATP。然而，杆状突起可以完全闭塞轴突，阻止运输并导致远端轴突萎缩。杆状突起是阿尔茨海默病(AD)脑的显著特征，但不是缺乏淀粉样斑块的对照人脑。在尼曼-皮克病(NPC1)型动物和表达突变的人类淀粉样前体蛋白(APP)的转基因小鼠(Tg2576)的大脑中也发现了类似的结构。在培养的神经元和小鼠脑片中，缺血、过氧化氢、一氧化氮和兴奋性毒性谷氨酸诱导了杆状突起。在高达20%的海马神经元中，无论是来自CA1区还是CAS区，AD淀粉样β肽(Ab)也能诱导杆状突起：诱导呈剂量依赖性，在处理后6小时内发生，12-24小时后达到平台期。与杂乱多肽对照相比，低至10 nM的抗体寡聚体具有显著的作用。我们将探索仅有一部分神经元对抗体敏感的本质。视杆细胞阻断APP的囊泡运输。含有APP的囊泡聚集在杆状结构的末端和侧面。在这些停滞的小泡中有β-分泌酶裂解的APP，这表明这些小泡可能是抗体产生和/或转化为更具破坏性的构象的部位。综上所述，这些结果提出了一种AD模型，在该模型中，神经元应激，包括家族性AD形成的抗体，诱导杆状突起，使囊泡运输停滞，并增加毒性抗体，从而在邻近细胞中诱导杆状突起。这样的模型可以解释淀粉样斑块的形成，淀粉样斑块会在损伤的初始位置周围扩大。利用细胞培养和器官型脑片，我们将确定：1)什么是cofilin的活性对于杆形成是必需的；2)是否可以确定AC中的突变，以防止杆的形成；3)杆是否促进抗体的产生或寡聚化；4)是什么使神经元亚群对抗体敏感：以及5)器官型脑片如何可以用作研究杆在哪里形成以及它们如何破坏突触的模型。与公共健康的相关性：广告极大地影响了美国老年人的生活质量，影响了25%的老年人。这项建议测试了AD进展的新假说，并确定了可能的靶向干预地点。

DESCRIPTION (provided by applicant): Within neurites of nearly all cultured hippocampal neurons, transient ATP depletion rapidly induces rod- shaped structures composed primarily of actin and ADF/cofilin (AC). Rod formation, which sequesters a portion of the actin but virtually all of the AC, is transiently beneficial to the stressed neuron because it spares ATP associated with actin turnover. However, rods can completely occlude the neurite, blocking transport and causing distal neurite withering. Rods are prominent features of Alzheimer's disease (AD) brain but not of control human brain lacking amyloid plaques. Similar structures are found in brains of animals with Niemann-Pick disease typed (NPC1) and of transgenic mice (Tg2576) expressing mutant human amyloid precursor protein (APP). In cultured neurons and mouse brain slices, rods are induced by ischemia, peroxide, NO, and excitotoxic glutamate. In up to 20% of hippocampal neurons, whether from region CA1 or CAS, the AD amyloid beta peptide (Ab) also induces rods: induction is dose-dependent, occurring within 6 h after treatment and reaching a plateau 12-24 h later. As little as 10 nM of Ab oligomer has a significant effect compared to the scrambled peptide control. The nature of the sensitivity of only a subset of neurons to Ab will be explored. Rods block vesicular transport of APP. APP-containing vesicles accumulate at the ends and sides of rods. Within these stalled vesicles is beta-secretase cleaved APP, suggesting that these may be sites of Ab production and/or conversion into more damaging conformers. Taken together, these results suggest a model for AD in which neuronal stress, including Ab formed in familial AD, induces rods that stall vesicle transport and increase toxic Ab, thus inducing rods in neighboring cells. Such a model could explain the formation of amyloid plaques, which would enlarge around the initial site of injury. Using cell culture and organotypic brain slices, we will determine: 1) what activities of cofilin are required for rod formation; 2) if mutations in AC can be identified that prevent rod formation; 3) if rods promote the production or oligomerization of Ab; 4) what makes a subset of neurons sensitive to Ab: and 5) how organotypic brain slices can be used as a model to study where rods form and how they disrupt synapses. Relevance to public health: AD dramatically impacts life quality of senior Americans, affecting 25% of those > 85. This proposal tests a new hypothesis for AD progression and identifies possible sites for targeted intervention.