Octyl gallate (OG) and Promotion of non-amyloidogenic processing of APP

描述(由申请人提供)： 近年来，反对淀粉样前体蛋白(APP)裂解成A？肽并导致脑淀粉样变性(AD的一个关键病理特征)的治疗方法已成为主要关注焦点。主要的靶标是分泌酶和分泌酶，这两种酶分别在A肽的氨基和羧基末端裂解APP，因此负责A肽的生成。另一种策略，即激活分泌酶，几乎没有人研究过。分泌酶在A肽段内裂解APP并阻止其生成，从而促进APP蛋白分解的非淀粉样蛋白生成途径。分泌酶的激活也会产生可能具有神经保护作用的Sapp-。此外，先前的研究表明，主要候选分泌酶ADAM10的增强激活减少了A？的产生，并防止了阿尔茨海默病小鼠模型的认知障碍。我们以前的发现表明，EGCG通过体外激活ADAM10促进非淀粉样变性APP的蛋白分解，并在体内类似地防止淀粉样蛋白病变。最近，我们发现EGCG通过雌激素受体介导的ADAM10的激活来促进APP的非淀粉样变过程。此外，这些事件与这些酚类化合物中的没食子酸基的存在呈正相关。此外，我们还发现，与EGCG相比，没食子酸辛酯(OG)在促进APP的分泌酶裂解方面具有显著的深远影响，从而限制了表达人野生型APP的神经元样N2a细胞中A的产生。最近，我们发现，外源人重组Sapp-1蛋白通过与培养细胞中主要的分泌酶候选BACE1特异地相互作用，促进非淀粉样变性APP的蛋白分解过程。Sapp-β与BACE1的这种相互作用抑制了其随后对全长APP的切割，从而进一步减少了A？的生成。这项拟议的研究的目标是确定OG的这种非淀粉样变机制，并确定潜在的分子药物靶点，这些靶点对于开发新的、有效的治疗AD至关重要。 在这项建议中，我们假设ADAM10激活化合物，由各种植物单宁的没食子酸产生的辛基没食子酸酯(OG)，将增加APP的非淀粉样变性/α-分泌酶蛋白分解，并减少转基因AD小鼠模型中的脑淀粉样变性。我们希望明确定义这种由OG推动的非淀粉样变性APP处理机制，从而识别潜在的分子药物靶点，这些靶点对于开发新的、有效的AD治疗方法至关重要。这项工作将通过以下目的来完成：(I)研究雌激素受体(ER)信号在OG促进的抗淀粉样变APP？分泌酶蛋白分解中的作用；SAPP-？介导OG诱导的抗淀粉样变APP的处理；(Iii)体内评价没食子酸辛酯(OG)对 促进抗淀粉样蛋白生成的APP？分泌酶蛋白分解。在这些实验结束时，这些研究将为OG作为新的、药理上安全的阿尔茨海默病预防/治疗药物的未来发展提供分子基础。

DESCRIPTION (provided by applicant): Therapies opposing cleavage of amyloid precursor protein (APP) into A¿ peptides and resultant cerebral amyloidosis, a key pathological feature of AD, have become a primary focus in recent years. The main targets have been ¿- and ?-secretase, the two proteases that cleave APP at the amino and carboxyl-terminus of the A¿ peptide, respectively and, hence, are responsible for A¿ peptide generation. An alternative strategy, the activation of ¿-secretase, has scarcely been investigated. ¿-secretase cleaves APP within the A¿ peptide domain and precludes its generation, thereby promoting the non-amyloidogenic pathway of APP proteolysis. ¿-secretase activation also generates the putatively neuroprotective sAPP-¿. In addition, previous studies have shown that enhanced activation of ADAM10, a primary candidate ¿-secretase, has reduced A¿ generation and prevented cognitive impairment in a mouse model of AD. Our previous findings suggest that EGCG promotes non-amyloidogenic APP proteolysis by in vitro activation of ADAM10 and, similarly, prevent ¿-amyloid pathology in vivo. Recently, we found that EGCG functions through an estrogen receptor-mediated activation of ADAM10 in the promotion of non-amyloidogenic processing of APP. Further these events are positively correlated with presence of the gallate group of these phenolic compounds. Furthermore, we have shown that octyl gallate (OG) has a significantly profound effect on promoting ¿-secretase cleavage of APP thus limiting A¿ production in neuron-like N2a cells expressing human wild-type APP compared to EGCG. Most recently, we found that exogenous human recombinant sAPP-¿ protein promotes non-amyloidogenic APP proteolytic processing through specifically interacting with BACE1, a primary ¿-secretase candidate, in cultured cells. This interaction of sAPP-¿ with BACE1 inhibited its subsequent cleavage of full-length APP and resultant further decreased A¿ generation. The goal of the proposed research is to define this non-amyloidogenic mechanism in OG and identify potential molecular drug targets, which are essential for formulating novel, effective treatments against AD. In this proposal we hypothesize that ADAM10 activating compound, octyl gallate (OG) produced from the gallic acid of various plant tannins, will increase non-amyloidogenic/alpha-secretase proteolysis of APP, and reduce cerebral amyloidosis in a transgenic mouse model of AD. We expect to clearly define this non-amyloidogenic APP processing mechanism promoted by OG, and, consequently, identify potential molecular drug targets, which are essential for formulating novel, effective treatments against AD. This work will be completed by investigation of the following aims: (I) Investigate the role of estrogen receptor (ER) signaling in OG-promoted anti-amyloidogenic APP ¿-secretase proteolysis; Characterize sAPP-¿ mediation of OG-induced anti-amyloidogenic APP processing; (III) In vivo evaluation of the effect of octyl gallate (OG) for the promotion of anti-amyloidogenic APP ¿-secretase proteolysis. At the end of these experiments, these studies will provide the molecular basis for the future development of OG as novel and pharmacologically safe agents for Alzheimer's disease prevention/treatment.