阿尔茨海默病（AD）是老年人群中最常见痴呆原因，机制不明。BACE1是AD发病的关键分子并被作为AD药靶，但BACE1成熟和参与AD的机制仍不十分清楚。我们在前期工作中发现并鉴定了AD转基因鼠脑内BACE1新磷酸化位点Thr252，且Thr252磷酸化BACE1在AD转基因鼠脑内表达较野生型鼠升高。本项目在前期工作基础上，拟首先利用细胞生物学、生物化学及活细胞示踪技术观察我们已经构建的野生型和T252突变BACE1在神经元内的转运过程及对AD标志性病理过程-淀粉样蛋白产生的影响；采用分子遗传学手段获得BACE1敲除的AD转基因鼠，定点注射野生或突变BACE1的慢病毒表达载体，在体验证Thr252磷酸化位点如何影响BACE1的成熟及功能。以阐明Thr252磷酸化修饰是BACE1成熟及在AD样病理改变中发挥作用的关键形式。将为以BACE1为靶点防治AD的低毒高效多肽药物研发提供理论基础。

Alzheimer's disease (AD) is the most common cause of dementia in older adults. BACE1 plays a pivotal role in pathogenesis of AD and is considered a target for AD drug development. However, the mechanism of BACE1 maturation and involvement in AD brain has not been well understood. We found and determined a novel phosphorylation site in BACE1, Threonine 252 in brains of 5XFAD mice. How would the phosphorylated Thr252BACE1 affect the amyloid beta peptide production and contribute to the pathological process of AD brain deserves investigation. Here, we will utilize technologies of cell biology, biochemistry and live-cell imaging to observe the traffic pattern of wild type BACE1 or its mutants, BACE1 T252A and BACE1 T252D carried by plasmids or lenti-virus in HEK293APPswe cells or primary neurons, and determine the important role of Thr252 phosphorylation in maturation and function of BACE1. Finally, we will generate 5XFAD/BACE1-/- mice and inject lenti-virus carrying BACE1 WT or its mutants to hippocampus of the transgenic mice to verify the function of phosphorylated Thr252BACE1 in AD model brain. The project will provide an evidence that the phosphorylated Thr252BACE1 is the import form of BACE1 involved in amyloid beta peptide production and cognitive dysfunction in AD brain.