Reduced expression of glutamate transporter EAAT2 and impaired glutamate transport in human primary astrocytes exposed to HIV-1 or gp120.
Reduced expression of glutamate transporter EAAT2 and impaired glutamate transport in human primary astrocytes exposed to HIV-1 or gp120.
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DOI：
10.1016/s0042-6822(03)00181-8
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发表时间：
2003-07
期刊：
影响因子：
3.7
通讯作者：
Zhuying Wang;O. Pekarskaya;M. Bencheikh;W. Chao;H. Gelbard;A. Ghorpade;J. Rothstein;D. Volsky
中科院分区：
文献类型：
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作者：
Zhuying Wang;O. Pekarskaya;M. Bencheikh;W. Chao;H. Gelbard;A. Ghorpade;J. Rothstein;D. Volsky
谷氨酸是大脑中主要的兴奋性神经递质。星形胶质细胞通过高亲和力摄取维持低水平的突触谷氨酸，并且该功能的缺陷可通过兴奋性毒性导致神经元细胞死亡。我们检测了HIV-1及其包膜糖蛋白gp 120对体外培养的人胎儿星形胶质细胞谷氨酸摄取和谷氨酸转运体EAAT 1和EAAT 2表达的影响。从孕16 ~ 19周的胎儿组织中分离的星形胶质细胞分别通过北方印迹分析和免疫印迹法检测到EAAT 1和EAAT 2 RNA和蛋白质的表达，并且这些细胞能够特异性摄取谷氨酸。星形胶质细胞暴露于HIV-1或gp 120显著损害细胞的谷氨酸摄取，在6小时内达到最大抑制，随后在3天的观察期间逐渐下降。HIV-1感染的细胞显示谷氨酸转运的Vmax降低了59%，表明细胞表面活性转运位点的数量减少。HIV-1感染或gp 120暴露后谷氨酸转运受损与EAAT 2 RNA和蛋白稳态水平下降40-70%相关。EAAT 1 RNA和蛋白水平受影响较小。用肿瘤坏死因子-α（TNF-α）处理星形胶质细胞可降低EAAT 1和EAAT 2的表达，但HIV-1和gp 120均不能诱导星形胶质细胞产生TNF-α。这些研究结果表明，HIV-1和gp 120诱导转录下调EAAT 2转运蛋白基因在人类星形胶质细胞和协调衰减谷氨酸转运细胞。HIV-1感染的星形胶质细胞摄取谷氨酸的能力降低可能有助于神经系统疾病的发展。
l-Glutamate is the major excitatory neurotransmitter in the brain. Astrocytes maintain low levels of synaptic glutamate by high-affinity uptake and defects in this function may lead to neuronal cell death by excitotoxicity. We tested the effects of HIV-1 and its envelope glycoprotein gp120 upon glutamate uptake and expression of glutamate transporters EAAT1 and EAAT2 in fetal human astrocytes in vitro. Astrocytes isolated from fetal tissues between 16 and 19 weeks of gestation expressed EAAT1 and EAAT2 RNA and proteins as detected by Northern blot analysis and immunoblotting, respectively, and the cells were capable of specific glutamate uptake. Exposure of astrocytes to HIV-1 or gp120 significantly impaired glutamate uptake by the cells, with maximum inhibition within 6 h, followed by gradual decline during 3 days of observation. HIV-1-infected cells showed a 59% reduction in Vmaxfor glutamate transport, indicating a reduction in the number of active transporter sites on the cell surface. Impaired glutamate transport after HIV-1 infection or gp120 exposure correlated with a 40–70% decline in steady-state levels of EAAT2 RNA and protein. EAAT1 RNA and protein levels were less affected. Treatment of astrocytes with tumor necrosis factor-α (TNF-α) decreased the expression of both EAAT1 and EAAT2, but neither HIV-1 nor gp120 were found to induce TNF-α production by astrocytes. These findings demonstrate that HIV-1 and gp120 induce transcriptional downmodulation of the EAAT2 transporter gene in human astrocytes and coordinately attenuate glutamate transport by the cells. Reduction of the ability of HIV-1-infected astrocytes to take up glutamate may contribute to the development of neurological disease.