Parpura V, Fang Y, Basarsky T, Jahn R, Haydon P G
Department of Zoology and Genetics, Iowa State University, Ames 50011, USA.
FEBS Lett. 1995 Dec 27;377(3):489-92. doi: 10.1016/0014-5793(95)01401-2.
Astrocytes, a sub-type of glial cell in the central nervous system, can release the excitatory transmitters glutamate and aspartate in response to elevated levels of internal calcium. To investigate potential release mechanisms that may be present in these cells we have determined whether protein components of the neuronal secretory apparatus are expressed in astrocytes. Western blots, immunocytochemistry and RT PCR demonstrate that astrocytes express cellubrevin, synaptobrevin II and syntaxin, proteins known to form a macromolecular fusion complex. However, SNAP-25 which is another neuronal protein of the fusion complex, was not detected. Astrocyte cellubrevin and synaptobrevin II were also shown to be sensitive to the proteolytic activity of tetanus toxin. Together these data indicate that astrocytes express some proteins that are known to form a fusion complex indicating that regulated exocytosis might mediate calcium-regulated transmitter release from these cells.
星形胶质细胞是中枢神经系统中的一种神经胶质细胞亚型，可在细胞内钙水平升高时释放兴奋性递质谷氨酸和天冬氨酸。为了研究这些细胞中可能存在的潜在释放机制，我们已确定神经元分泌装置的蛋白质成分是否在星形胶质细胞中表达。蛋白质免疫印迹、免疫细胞化学和逆转录聚合酶链反应表明，星形胶质细胞表达细胞ubrevin、突触小泡蛋白II和 syntaxin，这些蛋白质已知可形成大分子融合复合物。然而，未检测到融合复合物的另一种神经元蛋白SNAP-25。星形胶质细胞的细胞ubrevin和突触小泡蛋白II也显示对破伤风毒素的蛋白水解活性敏感。这些数据共同表明，星形胶质细胞表达一些已知可形成融合复合物的蛋白质，这表明受调控的胞吐作用可能介导这些细胞中钙调节的递质释放。
