分泌酶蛋白复合体的组装和活性及其在老年痴呆症发生发展过程中的调控机制

Despite tens of thousands of scientific articles about neurodegeneration, we are not closer to a cure of a remedy for dementia. This actually suggests that neurodegeneration research needs an invasion of new ideas from scientists in different fields to try to reinvigorate the development of new therapeutic targets as well as strategies. Amyloid precursor protein (APP) is best known for its involvement in the pathogenesis of the Alzheimer's disease (AD). Understanding the mechanisms regulating the amyloidogenic processing of APP has been a central area of investigation in AD research. On the other hand, a detail picture of the physiological functions of APP as well as its processing protease complexes (also called secretases) could be helpful to understand the disease, however, has been barely explored. In our present studies, we have verified the GPCR/secretase complex and β-arrestin1/APH-1 complex. We have shown that the interference of the formation of these complexes ameliorated the pathogenesis of the disease. Here, we will apply a serial of interaction HTS analysis (e.g. BiFC, BRET, FRET) to quantitative the assembly and dynamics of these protein complexes. These HTS analysis will also be used to verify direct effects of interfering peptides and further applied to screen for small probes. Afterwards, we will use the small probes to investigate the function and regulation details of APP and secretases. These robust approaches would also provide proof-of-concept evidence whether there would be better targets for the diseases. This study will not only reveal novel regulatory mechanisms of secretase complexes; the complex physiological functions and pathological effects of these protein complexes; enrich our understanding of pathogenesis of neurodegenerative diseases; but will also provide novel strategies for the diagnosis and treatment of these disease.

老年痴呆症在老年人死因中占第四位。老年痴呆症的主要病理学特征为大脑内神经细胞表面异常的淀粉样蛋白斑沉淀，神经纤维丝缠结以及神经元死亡。我们的前期的研究成果提示分泌酶在细胞膜结构中可能通过与不同的调控蛋白形成各种复合体，从而可能对分泌酶的活性、底物识别、亚细胞定位及其生理功能的实现进行精细调控，从而特异影响Aβ产生和代谢。本项目就是基于我们这些前期的研究成果，将进一步深入研究各种参与调控β淀粉样蛋白的产生和代谢的细胞表面蛋白复合体的功能和调控机制，发现分泌酶活性特异调控的突破口，进而通过对这些参与β淀粉样蛋白的产生和代谢过程蛋白复合体功能的研究及干预不仅会很有希望影响老年痴呆症的发病过程，并进而开辟预防和治疗老年痴呆症的新途径。这项研究不仅能进一步揭示细胞表面蛋白复合体的调控规律及其生理功能和病理效应，而且是理解和认识神经退行性疾病等复杂疾病的发病机制的重要方向。

在 Aβ致病假说中，β-淀粉样蛋白前体经 β-和γ-分泌酶顺序剪切产生Aβ。目前对此顺序剪切的调控机制还比较模糊，亟需研究 APP 剪切的蛋白复合体的具体工作机制及其在阿尔兹海默症发病机理中的作用。在本项研究工作中，我们系统地探求了 APP 剪切复合体的调控机理。在研究中，我们发现：顺序剪切 APP 的β-/γ-分泌酶能够发生直接相互作用，形成剪切复合体；通过高通量筛选我们得到了抑制这一蛋白质间相互作用的小分子化合物，能够减少细胞水平Aβ。我们在转基因小鼠模型中进一步验证了靶向β-/γ-分泌酶相互作用的小分子化合物能够缓解AD小鼠的行为认知缺陷和 AD 相关的病理学指标的能力。我们这些研究表明，细胞内存在能够精细调控 APP 剪切的分泌酶复合体。该复合体不仅包括 BACE1、β-分泌酶等剪切必须的蛋白酶，而且含有包括G蛋白偶联受体在内的重要信号转导分子。我们完全有希望通过靶向 APP 剪切复合体为AD治疗另辟蹊径。