Animal Model for Evaluation of Druge on Therapeutics of Alzheimer Disease

我们成功构建了早老素-1突变基因（I213T）敲入小鼠模型。a - β42/ a - β40比值升高。免疫组化研究显示，30周、8个月、24个月小鼠无老年斑，无神经原纤维缠结，但模型小鼠海马抗gfap抗体阳性星形细胞呈基因剂量依赖性增加。Western bolt分析显示抗gfap抗体染色增加。大脑皮层第II层和第III层神经元细胞内a - β42水平明显升高。这些结果表明，PS-1突变和衰老共同诱导了阿尔茨海默病大脑中常见的星形胶质细胞的增加和细胞内Aβ42的积累。来源于该模型小鼠的原代培养神经元对内质网应激的反应减弱。在突变型早老素表达的细胞中，伴侣蛋白之一GRP78的表达降低，内质网应激传感器蛋白ie1的功能降低。因此，这些细胞比未突变的早老素细胞更容易诱导细胞凋亡。阐明了早老素突变体神经退行性变的部分机制。

We succeeded in making a knock-in mouse model that has mutant presenilin-1 gene (I213T). An increase of the ratio of Aβ42/Aβ40 was observed in this model mouse. Immunohistochemical study showed no senile plaque or no neurofibrillary tangle in this mouse in 30 weeks, 8 months, and 24 months, however an increase of anti-GFAP antibody-positive astrocytes was observed in hippocampus of this model mouse in the gene-dose dependent manner. An increase of anti-GFAP antibody staining was also observed in Western bolt analysis. Furthermore an increase of intracellular Aβ42 was observed in neurons was observed in the II and III layers of cerebral cortex. These results suggest that PS-1 mutation and aging synergetically induce increase of astrocytes and accumulation of intracellular Aβ42 that are usually observed in Alzheimer brains.Primary cultured neurons derived from this model mouse showed decreased responses to ER (endoplasmic reticulum) stresses. The expression of GRP78, one of chaperone protein, was decreased and Ire 1, an sensor protein to ER stress, was less functioning, in cells with expression of mutant presenilin. Therefore apoptosis was more easily induced in these cells than in cells without mutant presenilin. A part of mechanisms on neurodegeneration in mutant presenilin was clarified.