GPR30 regulates glutamate transporter GLT-1 expression in rat primary astrocytes.
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.
Department of Physiology, Meharry Medical College, Nashville, Tennessee 37208, USA. elee@mmc.edu
Eunsook
E
Lee
Marta
M
Sidoryk-Wêgrzynowicz
Ning
N
Wang
Anton
A
Webb
Deok-Soo
DS
Son
Kyuwon
K
Lee
Michael
M
Aschner
D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D001483:Base Sequence; D015153:Blotting, Western; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D017931:DNA Primers; D027342:Excitatory Amino Acid Transporter 2 / Q000378:metabolism*; D020868:Gene Silencing; D007150:Immunohistochemistry; D016133:Polymerase Chain Reaction; D011494:Protein Kinases / Q000378:metabolism; D034741:RNA, Small Interfering; D051381:Rats; D017207:Rats, Sprague-Dawley; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000502:physiology*
D017362:Cyclic AMP Response Element-Binding Protein; D017931:DNA Primers; D027342:Excitatory Amino Acid Transporter 2; C520305:Gper1 protein, rat; D034741:RNA, Small Interfering; D043562:Receptors, G-Protein-Coupled; C493395:Slc1a2 protein, rat; D011494:Protein Kinases