Mint Adaptor Proteins in APP Binding and Processing

描述（由申请人提供）：淀粉样斑块由纤维状淀粉样蛋白-ß （ß）肽组成，在阿尔茨海默病（AD）的发病机制中起关键作用。已经确定，ß是由ß-和γ-分泌酶分别对淀粉样蛋白前体蛋白（APP）进行顺序蛋白水解而产生的。然而，细胞生物学和控制APP运输的分子对神经元中ß的产生至关重要，目前还不太清楚。asas产生的关键步骤是APP内吞作用，这是由位于APP细胞质区域的YENPTY序列介导的。Mints是在调节APP内吞作用和asas产生方面具有重要功能的衔接蛋白。我们之前的研究表明，薄荷受体蛋白通过直接结合APP的enpty内吞基序来调节APP的内吞作用，从而影响APP的蛋白水解过程。薄荷蛋白在死后人类AD大脑的ß斑块中被上调，这一证据支持了薄荷蛋白在AD发病机制中的作用。与这一发现一致，我们发现，在衰老小鼠和阿尔茨海默病小鼠模型中，三种薄荷蛋白中的任何一种的丢失都会减少β的产生。这些发现表明APP-Mint相互作用是一个潜在的关键治疗靶点，可以选择性地减少AD中asb的产生。然而，薄荷糖影响APP结合和asb产生的机制尚不清楚。因此，本研究计划的总体目标是了解薄荷依赖的APP结合和加工调控。在Aim 1中，我们将确定APP运输的细胞生物学，以及薄荷糖如何对突触活动诱导的APP内吞作用和asb产生至关重要。在Aim 2中，我们将在体外和体内小鼠模型中研究干扰APP-Mint1相互作用对减少as2产生的影响。确定调节APP结合和asb产生的新方法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的自抑制调节APP的结合和加工；然而，Mint1自抑制的分子机制和这种调节在神经元中的生理相关性尚不清楚。在Aim 3中，我们将阐明Mint1自抑制调节APP结合的生物学机制。详细描述调节Mint1与APP结合的自身抑制机制是探索其运作关键途径的宝贵工具，也是未来靶向治疗的平台。该研究将为理解APP-Mint生物学提供新的见解，该研究的结果有望具有强大的转化意义。

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.