Variations in promoter activity reveal a differential expression and physiology of glutamate transporters by glia in the developing and mature CNS
Variations in promoter activity reveal a differential expression and physiology of glutamate transporters by glia in the developing and mature CNS
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DOI：
10.1523/jneurosci.0790-07.2007
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发表时间：
2007-06-20
影响因子：
5.3
通讯作者：
Rothstein, Jeffrey D.
中科院分区：
文献类型：
--
作者：
Regan, Melissa R.;Huang, Yanhua H.;Rothstein, Jeffrey D.
谷氨酸转运蛋白调节兴奋性神经传递并防止中枢神经系统中谷氨酸介导的兴奋性毒性。为了更好地研究这些转运蛋白表达的细胞和时间动力学，我们产生了细菌人工染色体启动子Discosoma red [谷氨酸-天冬氨酸转运蛋白（GLAST）]和绿色荧光蛋白[谷氨酸转运蛋白-1（GLT- 1）]报告基因转基因小鼠。对这些小鼠的分析揭示了以前没有认识到的转运蛋白启动子的差异激活。GLT- 1启动子活性在成人中枢神经系统中几乎完全限于星形胶质细胞，经常和出乎意料地在一个不重叠的模式与GLAST。脊髓GLT- 1启动子报告基因、蛋白质密度和生理学比脑中低10倍，这表明在疾病中观察到的区域敏感性的可能机制。GLAST启动子在发育中的CNS中的放射状神经胶质细胞和许多星形胶质细胞中都有活性，但随着小鼠成熟，在大多数星形胶质细胞中下调。在成人中枢神经系统中，最高的GLAST启动子活性观察到放射状胶质细胞，如那些位于齿状回的颗粒下层。这些神经祖细胞持续表达GLAST增加了GLAST在调节其行为中可能具有意想不到的作用的可能性。此外，在白色物质中的少突胶质细胞中观察到GLAST启动子激活，遍及许多（例如，例如，在一个实施例中，脊髓和胼胝体），但不是全部（e.例如，在一个实施例中，小脑）、CNS纤维束。总体而言，这些研究GLT- 1和GLAST启动子活性，蛋白质表达和谷氨酸摄取揭示了转基因报告信号和摄取能力之间的密切相关性，表明这些小鼠提供了原位监测谷氨酸转运蛋白表达和调节的方法。
Glutamate transporters regulate excitatory neurotransmission and prevent glutamate- mediated excitotoxicity in the CNS. To better study the cellular and temporal dynamics of the expression of these transporters, we generated bacterial artificial chromosome promoter Discosoma red [ glutamate - aspartate transporter ( GLAST)] and green fluorescent protein [ glutamate transporter- 1 ( GLT- 1)] reporter transgenic mice. Analysis of these mice revealed a differential activation of the transporter promoters not previously appreciated. GLT- 1 promoter activity in the adult CNS is almost completely restricted to astrocytes, often and unexpectedly in a nonoverlapping pattern with GLAST. Spinal cord GLT- 1 promoter reporter, protein density, and physiology were 10- fold lower than in brain, suggesting a possible mechanism for regional sensitivity seen in disease. The GLAST promoter is active in both radial glia and many astrocytes in the developing CNS but is downregulated in most astrocytes as the mice mature. In the adult CNS, the highest GLAST promoter activity was observed in radial glia, such as those located in the subgranular layer of the dentate gyrus. The continued expression of GLAST by these neural progenitors raises the possibility that GLAST may have an unanticipated role in regulating their behavior. In addition, GLAST promoter activation was observed in oligodendrocytes in white matter throughout many ( e. g., spinal cord and corpus callosum), but not all ( e. g., cerebellum), CNS fiber tracts. Overall, these studies of GLT- 1 and GLAST promoter activity, protein expression, and glutamate uptake revealed a close correlation between transgenic reporter signals and uptake capacity, indicating that these mice provide the means to monitor the expression and regulation of glutamate transporters in situ.