β分泌酶1降低β肌养蛋白聚糖的蛋白质水平

Beta-secretase 1 Lowers β-Dystroglycan Protein Levels

目的β分泌酶1(BACE1)是阿尔茨海默病患者脑中淀粉样蛋白(Aβ)产生的关键酶。肌养蛋白聚糖(dystroglycan,DG)帮助星形胶质细胞的终足锚定在脑血管上,形成一道支持血脑屏障的胶质界限。一项无靶标蛋白质组学研究指出BACE1可能会下调DG的表达水平。本文旨在研究BACE1能否调控DG的蛋白质水平及其可能的调控机制。方法利用瞬时转染法在HEK-293T细胞系和原代培养的小鼠星形胶质细胞中表达目的蛋白。通过蛋白质免疫印迹分析目标蛋白质的相对水平。利用基因荧光定量和免疫共沉淀技术探索BACE1调控DG的潜在机制。结果在HEK-293T和原代小鼠星形胶质细胞中引入BACE1会使DGβ亚基(β-DG)的蛋白质水平显著降低。在HEK-293T细胞中,β-DG蛋白水平的下降依赖于BACE1的酶活性。结论在HEK-293T细胞和小鼠星形胶质细胞中,BACE1使β-DG的蛋白质水平下降。

Objective Beta-secretase 1(BACE1) is the key enzyme for amyloid β(Aβ) production in the Alzheimer’ s disease(AD) brain. The dystroglycan(DG) protein anchors astroglial endfeet onto cerebral blood vessels forming glia limitans, a supportive element in the blood-brain barrier. An untargeted proteomics study predicted that BACE1 downregulates DG expression. Here, this study investigated whether BACE1 modulates the protein levels of DG and its hypothetic mechanism. Methods Transient transfection technique was used to express target protein in HEK-293T cells and in primary mouse astrocytes. And the protein levels of targets were analyzed by Western blot. Quantitative polymerase chain reaction and co-immunoprecipitation were used to explore the potential mechanisms of BACE1-dependent regulation of DG. Results This study found that addition of BACE1 resulted in significantly lower levels of β subunit DG(β-DG) protein, both in HEK-293T cells and in primary mouse astrocytes. And in HEK-293T cells, this down-regulation of β-DG protein dependent on the enzyme activity of BACE1. Conclusion BACE1 lowers β-DG protein levels in HEK-293T cells and in mouse astrocytes.