Mint Adaptor Proteins in APP Binding and Processing

描述（由申请人提供）：由纤维状淀粉样蛋白（A β）肽组成的淀粉样蛋白斑块在阿尔茨海默病（AD）发病机制中起关键作用。已充分确定，A β是分别通过β-和γ-分泌酶对淀粉样前体蛋白（APP）进行连续蛋白水解而产生的。然而，细胞生物学和分子控制APP运输必不可少的AAP 12生产在神经元中是不太确定的。AAPs产生的关键步骤是由位于APP胞质区域的YENPTY序列介导的APP内吞作用。Mint是在调节APP内吞作用和AAPs产生中功能重要的衔接蛋白。我们以前表明，薄荷衔接蛋白调节APP内吞直接绑定到APP的YENPTY内吞基序，从而影响APP的蛋白水解加工。证据表明，薄荷上调，发现在AAPs斑块在死后的人类AD大脑支持的作用，薄荷在AD发病机制。与这一发现相一致，我们发现三种Mint蛋白中的任何一种的丢失都会降低衰老小鼠和AD小鼠模型中的ApoA产生。这些发现表明，APP-薄荷相互作用是一个潜在的关键治疗靶点，以选择性地减少AD中的腺苷酸产生。然而，薄荷糖对APP结合和ApoA产生影响的潜在机制尚不清楚。因此，本研究提案的总体目标是了解APP结合和加工的Mint依赖性调节。在目标1中，我们将确定APP运输的细胞生物学以及薄荷糖如何对突触活性诱导的APP内吞作用和AAPO 2产生至关重要。在目标2中，我们将研究干扰APP-Mint 1相互作用以减少体外和体内小鼠模型中的Ablation产生的影响。识别新的方式来调节APP的结合和AAP 13的生产将是一个重要的工具，可以导致替代治疗策略的发展，用于治疗AD。通过我们的结构研究，我们发现Mint 1的自抑制调节APP结合和加工;然而，Mint 1自抑制的分子机制和神经元中这种调节的生理相关性尚不清楚。在目标3中，我们将阐明Mint 1自身抑制调节APP结合的生物学机制。对调节Mint 1与APP结合的自抑制机制的详细描述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。拟议的研究将为理解APP-Mint生物学提供新的见解，预计这项研究的结果将具有很强的翻译意义。

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.