Transcriptional Regulation of the Astrocytic Excitatory Amino Acid Transporter 1 (EAAT1) via NF-κB and Yin Yang 1 (YY1).
Astrocytic glutamate transporter excitatory amino acid transporter (EAAT) 1, also known as glutamate aspartate transporter (GLAST) in rodents, is one of two glial glutamate transporters that are responsible for removing excess glutamate from synaptic clefts to prevent excitotoxic neuronal death. Despite its important role in neurophysiological functions, the molecular mechanisms of EAAT1 regulation at the transcriptional level remain to be established. Here, we report that NF-κB is a main positive transcription factor for EAAT1, supported by the following: 1) EAAT1 contains two consensus sites for NF-κB, 2) mutation of NF-κB binding sites decreased EAAT1 promoter activity, and 3) activation of NF-κB increased, whereas inhibition of NF-κB decreased EAAT1 promoter activity and mRNA/protein levels. EGF increased EAAT1 mRNA/protein levels and glutamate uptake via NF-κB. The transcription factor yin yang 1 (YY1) plays a role as a critical negative regulator of EAAT1, supported by the following: 1) the EAAT1 promoter contains multiple consensus sites for YY1, 2) overexpression of YY1 decreased EAAT1 promoter activity and mRNA/protein levels, and 3) knockdown of YY1 increased EAAT1 promoter activity and mRNA/protein levels. Manganese decreased EAAT1 expression via YY1. Epigenetic modifiers histone deacetylases (HDACs) served as co-repressors of YY1 to further decrease EAAT1 promoter activity, whereas inhibition of HDACs reversed manganese-induced decrease of EAAT1 expression. Taken together, our findings suggest that NF-κB is a critical positive regulator of EAAT1, mediating the stimulatory effects of EGF, whereas YY1 is a negative regulator of EAAT1 with HDACs as co-repressors, mediating the inhibitory effects of manganese on EAAT1 regulation.
From the Department of Physiology, School of Medicine, Meharry Medical College, Nashville, Tennessee 37208.
Pratap
P
Karki
the Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02115, and.
Clifford
C
Kim
From the Department of Physiology, School of Medicine, Meharry Medical College, Nashville, Tennessee 37208.
Keisha
K
Smith
From the Department of Physiology, School of Medicine, Meharry Medical College, Nashville, Tennessee 37208.
Deok-Soo
DS
Son
the Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461.
Michael
M
Aschner
From the Department of Physiology, School of Medicine, Meharry Medical College, Nashville, Tennessee 37208, elee@mmc.edu.
Eunsook
E
Lee
D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism*; D002478:Cells, Cultured; D044127:Epigenesis, Genetic / Q000187:drug effects / Q000502:physiology*; D027341:Excitatory Amino Acid Transporter 1 / Q000096:biosynthesis*; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D006655:Histone Deacetylases / Q000378:metabolism; D008345:Manganese / Q000378:metabolism / Q000494:pharmacology; D016328:NF-kappa B / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020218:Response Elements / Q000502:physiology; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology*; D050986:YY1 Transcription Factor / Q000378:metabolism*
D027341:Excitatory Amino Acid Transporter 1; D056572:Histone Deacetylase Inhibitors; D016328:NF-kappa B; C493392:Slc1a3 protein, rat; D050986:YY1 Transcription Factor; C494700:Yy1 protein, rat; D008345:Manganese; D006655:Histone Deacetylases
NF-κB transcription factor; astrocyte; epidermal growth factor (EGF); glutamate; manganese