Insights into glutamate transport regulation in human astrocytes: Cloning of the promoter for excitatory amino acid transporter 2 (EAAT2)

Su, Zao-zhong; Leszczyniecka, Magdalena; Kang, Dong‐Chul; Sarkar, Devanand; Chao, Wei; Volsky, David J.; Fisher, Paul B.

doi:10.1073/pnas.0136555100

Cited by 174 publications

(229 citation statements)

References 53 publications

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“…Recent studies have provided limited information on the genomic regulation of GLT-1 and GLAST transporters, which has been restricted to in vitro analysis of promoter fragments (Kim et al, 2003;Su et al, 2003) that may not accurately reflect normal gene regulation (Su et al, 2004). Consequently, little is known about the genomic regulation of glutamate transporters in vivo.…”

Section: Introductionmentioning

confidence: 99%

Variations in Promoter Activity Reveal a Differential Expression and Physiology of Glutamate Transporters by Glia in the Developing and Mature CNS

Regan

Huang

Kim

et al. 2007

Journal of Neuroscience

297

317

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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.

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Section: Introductionmentioning

confidence: 99%

Variations in Promoter Activity Reveal a Differential Expression and Physiology of Glutamate Transporters by Glia in the Developing and Mature CNS

Regan

Huang

Kim

et al. 2007

Journal of Neuroscience

297

317

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“…The excitatory amino acid transporter 2 (EAAT2) prevents glutamate toxicity by removing excess glutamate from the synaptic cleft. Treatment with TNF-a down-regulates EAAT2 mRNA and protein and also inhibits EAAT2-Prom activity in primary human fetal astrocytes (18,19) The primary pathway by which TNF-a suppresses EAAT2 expression is by activating NF-nB (19,20) that binds to the EAAT2 promoter and inhibits its activity. Interestingly, ectopic expression of AEG-1 also inhibits EAAT2 promoter activity.…”

Section: Introductionmentioning

confidence: 99%

Activation of the Nuclear Factor κB Pathway by Astrocyte Elevated Gene-1: Implications for Tumor Progression and Metastasis

Emdad¹,

Sarkar²,

Su³

et al. 2006

Cancer Research

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256

355

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Astrocyte elevated gene-1 (AEG-1) was initially identified as an HIV-1-and tumor necrosis factor A (TNF-A)-inducible transcript in primary human fetal astrocytes by a rapid subtraction hybridization approach. Interestingly, AEG-1 expression is elevated in subsets of breast cancer, glioblastoma multiforme and melanoma cells and AEG-1 cooperates with Ha-ras to promote transformation of immortalized melanocytes. Activation of the transcription factor nuclear factor KB (NF-KB), a TNF-A downstream signaling component, is associated with several human illnesses, including cancer, and NF-KB controls the expression of multiple genes involved in tumor progression and metastasis. We now document that AEG-1 is a significant positive regulator of NF-KB. Enhanced expression of AEG-1 via a replication-incompetent adenovirus (Ad.AEG-1) in HeLa cells markedly increased binding of the transcriptional activator p50/p65 complex of NF-KB. The NF-KB activation induced by AEG-1 corresponded with degradation of IKBA and nuclear translocation of p65 that resulted in the induction of NF-KB downstream genes. Infection with an adenovirus expressing the mt32IKBA superrepressor (Ad.IKBA-mt32), which prevents p65 nuclear translocation, inhibited AEG-1-induced enhanced agar cloning efficiency and increased matrigel invasion of HeLa cells. We also document that TNF-A treatment resulted in nuclear translocation of both AEG-1 and p65 wherein these two proteins physically interacted, suggesting a potential mechanism by which AEG-1 could activate NF-KB. Our findings suggest that activation of NF-KB by AEG-1 could represent a key molecular mechanism by which AEG-1 promotes anchorage-independent growth and invasion, two central features of the neoplastic phenotype.

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“…Moreover, we intended to find out if mutant Htt-552 expressed in cultured astrocytes had the same effects as N-208 and N-171. It was reported that the decreased glutamate uptake in astrocytes was mainly caused by the decreased expression of GLT-1, which has a gene promoter that carries multiple Sp1 binding sites [9] . The transcription of GLT-1 was Sp1-dependent, and it had been reported that mutant Htt bound more Sp1 and reduced Sp1-mediated GLT-1 expression in astrocytes.…”

Section: Introductionmentioning

confidence: 99%

Rapamycin prevents the mutant huntingtin-suppressed GLT-1 expression in cultured astrocytes

Chen

Wang

et al. 2012

Acta Pharmacol Sin

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Aim: To investigate the effects of rapamycin on glutamate uptake in cultured rat astrocytes expressing N-terminal 552 residues of mutant huntingtin (Htt-552). Methods: Primary astrocyte cultures were prepared from the cortex of postnatal rat pups. An astrocytes model of Huntington's disease was established using the astrocytes infected with adenovirus carrying coden gene of N-terminal 552 residues of Huntingtin. The protein levels of glutamate transporters GLT-1 and GLAST, the autophagic marker microtubule-associated protein 1A/1B-light chain 3 (LC3) and the autophagy substrate p62 in the astrocytes were examined using Western blotting. The mRNA expression levels of GLT-1 and GLAST in the astrocytes were determined using Real-time PCR. [ 3 H]glutamate uptake by the astrocytes was measured with liquid scintillation counting. Results: The expression of mutant Htt-552 in the astrocytes significantly decreased both the mRNA and protein levels of GLT-1 but not those of GLAST. Furthermore, Htt-552 significantly reduced [ 3 H]glutamate uptake by the astrocytes. Treatment with the autophagy inhibitor 3-MA (10 mmol/L) significantly increased the accumulation of mutant Htt-552, and reduced the expression of GLT-1 and [ 3 H]glutamate uptake in the astrocytes. Treatment with the autophagy stimulator rapamycin (0.2 mg/mL) significantly reduced the accumulation of mutant Htt-552, and reversed the changes in GLT-1 expression and [ 3 H]glutamate uptake in the astrocytes. Conclusion: Rapamcin, an autophagy stimulator, can prevent the suppression of GLT-1 expression and glutamate uptake by mutant Htt-552 in cultured astrocytes.

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Insights into glutamate transport regulation in human astrocytes: Cloning of the promoter for excitatory amino acid transporter 2 (EAAT2)

Cited by 174 publications

References 53 publications

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

Activation of the Nuclear Factor κB Pathway by Astrocyte Elevated Gene-1: Implications for Tumor Progression and Metastasis

Rapamycin prevents the mutant huntingtin-suppressed GLT-1 expression in cultured astrocytes

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