GPR30 regulates glutamate transporter GLT-1 expression in rat primary astrocytes

J Biol Chem. 2012 Aug 3;287(32):26817-28. doi: 10.1074/jbc.M112.341867. Epub 2012 May 29.

Abstract

The G protein-coupled estrogen receptor GPR30 contributes to the neuroprotective effects of 17β-estradiol (E2); however, the mechanisms associated with this protection have yet to be elucidated. Given that E2 increases astrocytic expression of glutamate transporter-1 (GLT-1), which would prevent excitotoxic-induced neuronal death, we proposed that GPR30 mediates E2 action on GLT-1 expression. To investigate this hypothesis, we examined the effects of G1, a selective agonist of GPR30, and GPR30 siRNA on astrocytic GLT-1 expression, as well as glutamate uptake in rat primary astrocytes, and explored potential signaling pathways linking GPR30 to GLT-1. G1 increased GLT-1 protein and mRNA levels, subject to regulation by both MAPK and PI3K signaling. Inhibition of TGF-α receptor suppressed the G1-induced increase in GLT-1 expression. Silencing GPR30 reduced the expression of both GLT-1 and TGF-α and abrogated the G1-induced increase in GLT-1 expression. Moreover, the G1-induced increase in GLT-1 protein expression was abolished by a protein kinase A inhibitor and an NF-κB inhibitor. G1 also enhanced cAMP response element-binding protein (CREB), as well as both NF-κB p50 and NF-κB p65 binding to the GLT-1 promoter. Finally, to model dysfunction of glutamate transporters, manganese was used, and G1 was found to attenuate manganese-induced impairment in GLT-1 protein expression and glutamate uptake. Taken together, the present data demonstrate that activation of GPR30 increases GLT-1 expression via multiple pathways, suggesting that GPR30 is worthwhile as a potential target to be explored for developing therapeutics of excitotoxic neuronal injury.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Astrocytes / metabolism*
  • Base Sequence
  • Blotting, Western
  • Cells, Cultured
  • Cyclic AMP Response Element-Binding Protein / metabolism
  • DNA Primers
  • Excitatory Amino Acid Transporter 2 / metabolism*
  • Gene Silencing
  • Immunohistochemistry
  • Polymerase Chain Reaction
  • Protein Kinases / metabolism
  • RNA, Small Interfering
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, G-Protein-Coupled / genetics
  • Receptors, G-Protein-Coupled / physiology*

Substances

  • Cyclic AMP Response Element-Binding Protein
  • DNA Primers
  • Excitatory Amino Acid Transporter 2
  • Gper1 protein, rat
  • RNA, Small Interfering
  • Receptors, G-Protein-Coupled
  • Slc1a2 protein, rat
  • Protein Kinases