BACE2活性片段与细胞穿膜肽融合蛋白对APP剪切作用的研究

Alzheimer’s Disease(AD) is the most common type of dementia without effective treatment. Senile plaques accumulate around the neurons is the unique pathological hallmark of AD. The neurotoxic Aβ is the core component of senile plaque and is generated by abnormal cleavage of APP in neuron. Previous studies have shown that BACE2 cleavage APP within Aβ domain and preclude Aβ production. Blockage of BACE2 degradation increases the expression of BACE2 and thus facilitates the non-amyloid pathway of APP degradation. Therefore, increasing the level of exogenous BACE2 paves an effective way for AD treatment. As the very low level of BACE2 in neuron and exogenous BACE2 is difficult to penetrate the cell membrane and to exert it biological functions. This project is designated to synthesis BACE2 active fragment and cell membrane penetrating peptide fusion protein。 Our in vivo and in vitro studies is to elucidate the mechanism of BACE2 active fragment fusion protein’s effects on APP cleavage. This project also provide the evidence exogenous BACE2 active fragment with cell membrane penetrating peptide can lower the Aβexpression in vivo and in vitro, we also focus on the effect of this fusion protein on behavior test of AD animal model and its safety analysis. Our study will raise a novel concept in further understanding the molecular mechanism of AD, and the results will provide theoretical evidence of target gene therapy.

AD是最常见的痴呆类型，目前尚无有效治疗手段。APP的异常剪切引起有毒性作用的Aβ蛋白在神经元周围大量沉积形成淀粉样斑块是其独有的病理特征。BACE2在Aβ结构域内剪切APP，可避免Aβ的生成；阻断BACE2的降解可使更多的APP通过非淀粉样途径代谢。提高细胞内BACE2的水平可有效降低胞内外Aβ的表达。由于神经细胞内BACE2的表达量很低，且外源性BACE2难以穿透细胞膜进入细胞发挥其生物活性。本研究拟采用基因工程技术合成BACE2活性片段与TAT穿膜结构域的融合蛋白，通过体内和体外实验分别评价细胞内和AD动物模型脑内导入该融合蛋白对APP剪切的影响，检测通过穿膜肽导入外源性的BACE2活性片段是否可降低细胞及AD动物模型脑组织内Aβ的表达，观察该融合蛋白对AD模型动物行为学的影响并对其安全性进行评价。本研究有助于进一步认识AD的分子机制，为针对AD特定基因的靶向治疗提供理论依据。