Mint Adaptor Proteins in APP Binding and Processing

描述(申请人提供)：淀粉样斑块，由纤维淀粉样多肽组成，在阿尔茨海默病(AD)的发病机制中起着关键作用。已有的研究表明，A？是由淀粉样前体蛋白(APP)分别由？和γ-分泌酶连续蛋白分解而产生的。然而，细胞生物学和控制APP运输的分子对于神经元中A？的产生是必不可少的，这一点还不太清楚。APP内吞作用是APP发生的关键步骤，APP内吞作用由APP胞质区域的YENPTY序列介导。薄荷是一种适配蛋白，在调节APP内吞作用和A？产生方面起着重要的作用。我们之前已经证明，Mint接头蛋白通过直接与APP的YENPTY内吞基序结合来调节APP的内吞作用，从而影响APP的蛋白降解过程。有证据表明，薄荷糖在人死后AD脑的Aü斑块中表达上调，并存在于其中，这支持了薄荷糖在AD发病机制中的作用。与这一发现一致的是，我们发现，失去三种薄荷蛋白中的任何一种，都会减少衰老小鼠和阿尔茨海默病小鼠模型中Aü的产生。这些发现表明，APP-Mint相互作用是选择性减少AD患者Aü产生的潜在关键治疗靶点。然而，薄荷糖对APP结合和Aü产生的影响的潜在机制尚不清楚。因此，本研究方案的总体目标是了解薄荷依赖的APP绑定和处理的调节。在目标1中，我们将确定APP运输的细胞生物学，以及薄荷糖是如何在突触活动诱导APP内吞和A？产生中起关键作用的。在目标2中，我们将在体外和体内小鼠模型中研究干扰APP-Mint1相互作用以减少Aü的产生的效果。识别新的方法来调节APP结合和Aü产生将是一个重要的工具，可以导致开发治疗AD的替代治疗策略。通过我们的结构研究，我们发现Mint1的自身抑制调节APP的结合和处理；然而，Mint1自身抑制的分子机制以及这种调节在神经元中的生理相关性尚不清楚。在目标3中，我们将阐明Mint1自身抑制调控APP结合的生物学机制。详细描述调节Mint1与APP结合的自动抑制机制是探索其运作的关键途径的宝贵工具，也是未来靶向治疗的平台。这项拟议的研究将为理解APP-Mint生物学提供新的见解，这项研究的结果预计将具有强烈的翻译意义。

DESCRIPTION (provided by applicant): Amyloid plaques, which consist of fibrillar amyloid-ß (Aß) peptides, play a key role in Alzheimer's disease (AD) pathogenesis. It is well established that Aß is generated by sequential proteolysis of the amyloid precursor protein (APP) by ß- and γ-secretases, respectively. However, the cell biology and molecules controlling APP trafficking essential for Aß production in neurons are less defined. A key step in Aß generation is APP endocytosis that is mediated by the YENPTY sequence located in the cytoplasmic region of APP. Mints are adaptor proteins that are functionally important in regulating APP endocytosis and Aß production. We previously showed that the Mint adaptor proteins regulate APP endocytosis by directly binding to the YENPTY endocytic motif of APP, thereby influencing proteolytic processing of APP. The evidence that Mints are upregulated and found in Aß plaques in postmortem human AD brains supports a role for Mints in AD pathogenesis. Consistent with this finding, we showed that loss of any one of the three Mint proteins decreases Aß production in aging mice and mouse models of AD. These findings suggest that the APP-Mint interaction is a potential key therapeutic target to selectively reduce Aß production in AD. However, the mechanisms underlying the effects of Mints on APP binding and Aß production are unclear. Therefore, the overall goal of this research proposal is to understand Mint-dependent regulation of APP binding and processing. In Aim 1, we will determine the cell biology of APP trafficking and how Mints are essential for synaptic activity-induced APP endocytosis and Aß production. In Aim 2, we will investigate the effects of perturbing the APP-Mint1 interaction to decrease Aß production in both in vitro and in vivo mouse models. The identification of novel ways to modulate APP binding and Aß production will be an important tool that can lead to the development of alternative therapeutic strategies for treating AD. Through our structural studies, we found that autoinhibition of Mint1 regulates APP binding and processing; however, the molecular mechanism underlying Mint1 autoinhibition and the physiological relevance of this regulation in neurons are not known. In Aim 3, we will elucidate the biological mechanisms underlying Mint1 autoinhibition in regulating APP binding. A detailed delineation of the autoinhibitory mechanism regulating Mint1 binding to APP is an invaluable tool in exploring the critical routes to which it operates and a platform for future targeted therapeutics. The proposed research will provide new insights into understanding APP-Mint biology and the outcomes of this research are expected to have strong translational implications.