Role of PS1 in neurodegeneration

描述（由申请人提供）：突触功能障碍和突触积聚是阿尔茨海默病（AD）病理学的关键特征。大量研究表明，腺苷酸可以以活性依赖的方式产生，并且这与突触囊泡胞吐作用相关。PS1/g-分泌酶存在于突触末梢，我们的初步数据表明，它的构象迅速，可逆地改变与突触活动和钙（Ca 2+）内流一致。早老素1（PS1）是γ-分泌酶的催化成分，它释放A β肽的C末端，从而决定A β的量以及将产生的A β种类：A β 40还是更长、高度纤维形成和神经毒性的A β？42.然而，控制PS1/γ-分泌酶切割位点的精确性和突触处的局部ApoE产生的细胞生物学机制仍然未知。已经报道了由几种激酶引起的PS1磷酸化，然而PS1磷酸化的机制作用仍然不清楚。目的1探讨神经元活动/Ca ~（2+）诱导的PS_1/γ-分泌酶磷酸化是否代表了突触对PS_1构象和功能的调节机制。此外，我们最近的蛋白质组学屏幕的小鼠脑裂解物中存在或不存在的钙确定了两种新的PS1相互作用的蛋白质，突触蛋白1（Syn 1）和突触结合蛋白1（Syt 1），表现出强大的，但相反的钙依赖性的档案结合PS1。Syn 1将突触囊泡锚定在肌动蛋白丝上，但在Ca 2+诱导的Syn 1磷酸化后释放它们。Syt 1在神经递质释放中起Ca ~（2+）感受器的作用。目的2探讨Ca 2+内流是否作为开关控制PS1的构象以及与Syn 1和Syt 1的相互作用。此外，我们将测试PS1与Syn 1和Syt 1的相互作用是否以活性控制的方式调节PS1/γ-分泌酶和突触处的APP加工。目的3将验证新发现的PS1与突触蛋白在体内的相互作用的生理相关性，通过确定它是否在老年和/或患病的大脑中受到影响，以及这些相互作用是否可以被操纵。本研究将为PS1的构象变化提供机制数据，将探索新的PS1与突触囊泡机制蛋白的相互作用，并将阐明新的突触依赖和独立的PS1的作用。理解这些问题是非常重要的，因为操纵PS1构象和突触相互作用可能会转化为新的治疗策略。

DESCRIPTION (provided by applicant): Synaptic dysfunction and Aß accumulation are the key features of Alzheimer's disease (AD) pathology. Numerous studies have shown that Aß can be produced in activity-dependent manner, and this correlates with synaptic vesicle exocytosis. PS1/g-secretase is present at the synaptic terminals, and our preliminary data show that it changes its conformation rapidly and reversibly in concert with synaptic activity and calcium (Ca2+) influx. Presenilin 1 (PS1) is the catalytic component of γ-secretase, which liberates the C-terminus of Aß peptide, and thus determines both amount of Aß and which Aß species will be produced: Aß40 or the longer, highly fibrillogenic and neurotoxic A?42. However, the cell biological mechanisms that control precision of the PS1/γ-secretase cleavage site and local Aß production at the synapse remains unknown. PS1 phosphorylation by several kinases has been reported; however mechanistic effect of the PS1 phosphorylation remains unclear. Aim 1 will determine whether neuronal activity/Ca2+-induced phosphorylation of PS1/γ-secretase represents the regulatory mechanism of PS1 conformation and function at the synapse. Furthermore, our recent proteomics screen of mouse brain lysates in the presence or absence of calcium identified two novel PS1 interacting proteins, synapsin1 (Syn1) and synaptotagmin1 (Syt1), that showed strong but opposing Ca2+-dependent profiles of binding to PS1. Syn1 anchors synaptic vesicles to actin filaments, but releases them after Ca2+-induced Syn1 phosphorylation. Syt1 acts as Ca2+sensor in neurotransmitter release. Aim 2 will explore whether, Ca2+ influx may function as a switch controlling PS1 conformation and interactions with Syn1 and Syt1. In addition, we will test if PS1 interactions with Syn1 and Syt1 modulate PS1/γ-secretase and APP processing at the synapse in an activity-controlled manner. Aim 3 will validate physiological relevance of the newly found PS1 interaction with synaptic proteins in vivo by establishing if it is affected in aged and/or diseased brain, and whether these interactions can be manipulated pharmacologically. This study will provide mechanistic data for PS1 conformational changes, will explore novel PS1 interactions with synaptic vesicle machinery proteins, and will elucidate novel Aß-dependent and independent role of PS1 at the synapse. Understanding these issues is of high importance because manipulation of the PS1 conformation and synaptic interactions may translate into novel therapeutic strategies.