Mouser Peter E, Head Elizabeth, Ha Kwang-Ho, Rohn Troy T
Department of Biology, Boise State University, Boise, ID 83725, USA.
Am J Pathol. 2006 Mar;168(3):936-46. doi: 10.2353/ajpath.2006.050798.
Recent studies demonstrate roles for activation of caspases and cleavage of cellular proteins within neurons of the Alzheimer's disease (AD) brain. To determine whether a similar role for caspases also occurs within glial cells in AD, we designed a site-directed caspase-cleavage antibody specific to glial fibrillary acidic protein (GFAP), a cytoskeleton protein specifically expressed in astrocytes. In vitro characterization of this antibody using both a cell-free system and a cell model system of apoptosis demonstrated that the antibody (termed GFAP caspase-cleavage product antibody or GFAP-CCP Ab) immunolabeled the predicted caspase-cleavage fragment, but not full-length GFAP, by Western blot analysis. To determine whether caspases cleave GFAP in vivo, tissue sections from control and AD brains were examined by immunohistochemistry using the GFAP-CCP Ab. Two prominent features of staining were evident: immunolabeling of degenerating astrocytes in proximity to blood vessels and staining within plaque-rich regions of the AD brain. Furthermore, co-localization of the GFAP-CCP Ab and an antibody specific to active caspase-3 was demonstrated within damaged astrocytes of the AD brain. These data suggest that the activation of caspases and cleavage of cellular proteins such as GFAP may contribute to astrocyte injury and damage in the AD brain.
最近的研究表明，在阿尔茨海默病（AD）大脑的神经元内，半胱天冬酶的激活和细胞蛋白的切割发挥了作用。为了确定在AD的神经胶质细胞中是否也存在类似的半胱天冬酶作用，我们设计了一种针对胶质纤维酸性蛋白（GFAP）的位点特异性半胱天冬酶切割抗体，GFAP是一种在星形胶质细胞中特异性表达的细胞骨架蛋白。使用无细胞系统和细胞凋亡模型系统对该抗体进行的体外特性分析表明，通过蛋白质印迹分析，该抗体（称为GFAP半胱天冬酶切割产物抗体或GFAP-CCP Ab）能免疫标记预测的半胱天冬酶切割片段，而不是全长GFAP。为了确定半胱天冬酶在体内是否切割GFAP，我们使用GFAP-CCP Ab通过免疫组织化学检查了对照和AD大脑的组织切片。染色有两个显著特征：靠近血管的退化星形胶质细胞的免疫标记以及AD大脑富含斑块区域内的染色。此外，在AD大脑受损的星形胶质细胞内，GFAP-CCP Ab与活性半胱天冬酶-3特异性抗体共定位。这些数据表明，半胱天冬酶的激活和诸如GFAP等细胞蛋白的切割可能导致AD大脑中的星形胶质细胞损伤。
