Inhibitory regulation of glutamate aspartate transporter (GLAST) expression in astrocytes by cadmium-induced calcium influx

Yu Peng Liu, Chung Shi Yang, Shun-Fen Tzeng

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

After injury to the CNS, the accumulation of extracellular glutamate induces neuronal excitotoxicity, leading to secondary tissue damage. Astrocytes can reduce excess extracellular glutamate primarily through the astrocytic glutamate transporter-1 and the Na+-dependent glutamate/aspartate transporter (GLAST). In this study, we used an in vitro model of cadmium-induced cellular stress and found that glutamate uptake activity of astrocytes was suppressed because of cadmium-induced inhibition of GLAST expression. The blockage of cadmium-triggered Ca2+ influx by Ca2+ chelators elevated GLAST transcription and glutamate uptake activity in astrocytes, suggesting that the suppression of GLAST expression in cadmium-treated astrocytes was Ca2+-dependent. This was supported by the findings showing the reduction of GLAST mRNA in astrocytes after treatment with Ca2+-ionophore A23187. Cadmium reduced human GLAST promoter activity; however, it increased the binding of Ca2+-sensitive activator protein-1 (AP-1) and cAMP response element binding protein (CREB) to their specific elements derived from the human GLAST promoter. These results demonstrate that AP-1 and CREB may be coupled with Ca2+-dependent pathway triggered by cadmium to mediate the inhibition of GLAST transcription. Our results suggest that Ca2+ influx into astrocytes after CNS injury could cause the down-regulation of GLAST expression, thus reducing the astrocytic glutamate uptake function, which in turn may exacerbate secondary damage after CNS injury.

Original languageEnglish
Pages (from-to)137-150
Number of pages14
JournalJournal of Neurochemistry
Volume105
Issue number1
DOIs
Publication statusPublished - 2008 Apr 1

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Amino Acid Transport System X-AG
Cadmium
Astrocytes
Calcium
Glutamic Acid
Cyclic AMP Response Element-Binding Protein
Transcription Factor AP-1
Transcription
Wounds and Injuries
Ionophores
Calcimycin
Chelating Agents
Down-Regulation
Tissue

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Cellular and Molecular Neuroscience

Cite this

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abstract = "After injury to the CNS, the accumulation of extracellular glutamate induces neuronal excitotoxicity, leading to secondary tissue damage. Astrocytes can reduce excess extracellular glutamate primarily through the astrocytic glutamate transporter-1 and the Na+-dependent glutamate/aspartate transporter (GLAST). In this study, we used an in vitro model of cadmium-induced cellular stress and found that glutamate uptake activity of astrocytes was suppressed because of cadmium-induced inhibition of GLAST expression. The blockage of cadmium-triggered Ca2+ influx by Ca2+ chelators elevated GLAST transcription and glutamate uptake activity in astrocytes, suggesting that the suppression of GLAST expression in cadmium-treated astrocytes was Ca2+-dependent. This was supported by the findings showing the reduction of GLAST mRNA in astrocytes after treatment with Ca2+-ionophore A23187. Cadmium reduced human GLAST promoter activity; however, it increased the binding of Ca2+-sensitive activator protein-1 (AP-1) and cAMP response element binding protein (CREB) to their specific elements derived from the human GLAST promoter. These results demonstrate that AP-1 and CREB may be coupled with Ca2+-dependent pathway triggered by cadmium to mediate the inhibition of GLAST transcription. Our results suggest that Ca2+ influx into astrocytes after CNS injury could cause the down-regulation of GLAST expression, thus reducing the astrocytic glutamate uptake function, which in turn may exacerbate secondary damage after CNS injury.",
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Inhibitory regulation of glutamate aspartate transporter (GLAST) expression in astrocytes by cadmium-induced calcium influx. / Liu, Yu Peng; Yang, Chung Shi; Tzeng, Shun-Fen.

In: Journal of Neurochemistry, Vol. 105, No. 1, 01.04.2008, p. 137-150.

Research output: Contribution to journalArticle

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