A study of abnormaly phosphorylated tau in glidl cells

出现在胶质细胞中的tau阳性包涵体称为胶质原纤维缠结，或更简单地称为胶质缠结。这些细胞包括簇状星形胶质细胞、刺状星形胶质细胞、盘绕体和亲银线。后两种结构出现在少突胶质细胞中。神经胶质缠结中的tau蛋白是过度磷酸化的，其免疫组织化学特征与神经原纤维缠结（nft）相似，除了没有来自选择性剪接的外显子2和3的表位。与nft相比，胶质缠结很少显示实心细丝。诸如泛素、载脂蛋白E、α - 1抗凝乳胰蛋白酶和硫酸肝素等与nfts相关的分子都不存在于胶质缠结中。这些特征表明，胶质缠结类似于发生在神经元中的前缠结，被认为代表了nft的早期阶段。神经退行性疾病中的Tau病理学表现为异质形式。通过磷酸化和非磷酸化的tau抗体和免疫印迹，免疫组织化学方法显示了部分磷酸化的tau在大鼠原代培养星形胶质细胞中的表现。在进一步的培养过程中，tau蛋白的免疫原性逐渐减弱，然而，在培养的星形胶质细胞中，持续和反复暴露于钙离子载体中，维持了tau蛋白的免疫反应性，并且在Ser 396位点发生磷酸化。电镜观察显示，除了细胞核和线粒体外，tau蛋白在实验星形胶质细胞中弥漫性分布，未见丝状聚集。

Tau-positive inclusions that occur in glial cells are called glial fibrillary tangles or, more simply, glial tangles. These include tuft-shaped astrocytes, thorn-shaped astrocytes, coiled bodies and argyrophilic threads. The latter two sltructures occur in oligodendroglia. The tau protein in glial tangles is hyperphosphorylated and has similar immunohistochemical profiles to that in neurofibrillary tangles (NFTs) except that there are no epitopes derived from alternatively spliced exon 2 and 3. In contrast to NFTs, glial tangles rarely show solid filaments. Such NFTs-associated molecules as ubiquitin, apolipoprotein E,alpha1-antichymotrypsin and heparan sulfate are all absent from glial tangles. These characteristics suggest that glial tangles resemble the pretangles which occur in neurons adn are thought to represent an early stage of NFTs. Tau pathology in neurodegenerative diseases takes heterogenous forms.Manifestation of partially phosphorylated tau in rat primary culture astrocytes was shown immunohistochemically by phosphorylated as well as non-phosphorylated tau antibodies and by immunoblots. Immunogenicity for tau gradually diminished during further culture、however, continuous and recurrent exposure to calcium ionophore maintained immunoreactivity for tau in culture astrocytes and moreover occurred phosphorylation at Ser 396. Electron microscopy showed tau distributed diffusely in the experimental astrocytes except for in the nucleus and mitochondria but no filamentous assembly was observed.