ADF/cofilin-actin rods in neurodegenerative diseases

描述（由申请人提供）：在几乎所有培养的海马神经元的神经突内，短暂的ATP消耗迅速诱导主要由肌动蛋白和ADF/cofilin（AC）组成的杆状结构。杆的形成，螯合的肌动蛋白的一部分，但几乎所有的AC，是短暂的有益的应激神经元，因为它节省ATP与肌动蛋白周转。然而，杆可以完全闭塞神经突，阻碍运输，并导致远端神经突枯萎。杆是阿尔茨海默病（AD）脑的突出特征，但不是缺乏淀粉样蛋白斑块的对照人脑。在尼曼-皮克病分型动物（NPC 1）和表达突变型人淀粉样前体蛋白（APP）的转基因小鼠（Tg 2576）的脑中发现了类似的结构。在培养的神经元和小鼠脑切片中，缺血、过氧化物、NO和兴奋性毒性谷氨酸诱导了视杆细胞。在多达20%的海马神经元中，无论是来自区域CA 1还是CAS，AD淀粉样β肽（Ab）也诱导视杆细胞：诱导是剂量依赖性的，在处理后6小时内发生，并在12-24小时后达到平台期。与乱序肽对照相比，低至IOnM的Ab寡聚体具有显著效果。将探索仅一个神经元子集对Ab的敏感性的性质。杆状物阻断APP的囊泡运输，APP囊泡聚集在杆状物的末端和侧面。在这些停滞的囊泡内是β-分泌酶切割的APP，这表明这些可能是Ab产生和/或转化为更具破坏性的构象异构体的位点。综上所述，这些结果表明AD的模型，其中神经元应激，包括在家族性AD中形成的Ab，诱导阻止囊泡运输并增加毒性Ab的杆，从而诱导邻近细胞中的杆。这种模型可以解释淀粉样斑块的形成，它会在最初的损伤部位周围扩大。使用细胞培养和器官型脑切片，我们将确定：1）cofilin的哪些活性是杆形成所必需的; 2）AC中的突变是否可以被鉴定为阻止杆形成; 3）杆是否促进Ab的产生或寡聚化; 4）是什么使得神经元的子集对Ab敏感：以及5）器官型脑切片如何被用作研究杆在哪里形成以及它们如何破坏突触的模型。与公共卫生的相关性：AD极大地影响了美国老年人的生活质量，影响了25%的85岁以上老年人。该提案测试了AD进展的新假设，并确定了可能的靶向干预部位。

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.