Role of PS1 in neurodegeneration

描述（由申请人提供）：突触功能障碍和asb积累是阿尔茨海默病（AD）病理的关键特征。大量研究表明，乙酰胆碱可以活性依赖的方式产生，这与突触囊泡胞吐有关。PS1/g分泌酶存在于突触末端，我们的初步数据表明，它的构象随着突触活性和钙（Ca2+）内流而迅速可逆地改变。早老素1 （PS1）是γ-分泌酶的催化成分，它释放α -肽的c端，从而决定α -肽的数量和产生哪一种α -肽：Aß40还是更长、高纤维原性和神经毒性的Aß42。然而，控制PS1/γ-分泌酶切割位点精度和突触局部as2产生的细胞生物学机制尚不清楚。PS1被几种激酶磷酸化已被报道；然而PS1磷酸化的机制作用尚不清楚。Aim 1将确定神经元活性/Ca2+诱导的PS1/γ分泌酶磷酸化是否代表PS1在突触构象和功能的调节机制。此外，我们最近对存在或不存在钙的小鼠脑裂解物进行了蛋白质组学筛选，发现了两种新的PS1相互作用蛋白，synapsin1 （Syn1）和synaptotagmin1 (Syt1)，它们显示出与PS1结合的强烈但相反的Ca2+依赖性谱。Syn1将突触囊泡锚定在肌动蛋白丝上，但在Ca2+诱导的Syn1磷酸化后释放它们。Syt1在神经递质释放中作为Ca2+传感器。Aim 2将探讨Ca2+内流是否可以作为控制PS1构象和与Syn1和Syt1相互作用的开关。此外，我们将测试PS1与Syn1和Syt1的相互作用是否以活动控制的方式调节PS1/γ-分泌酶和突触的APP处理。目的3将验证新发现的PS1与突触蛋白相互作用在体内的生理相关性，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在药理学上被操纵。本研究将提供PS1构象变化的机制数据，探索PS1与突触囊泡机械蛋白的新型相互作用，并阐明PS1在突触中的新型a ß依赖和独立作用。了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 Aß42. 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.