Regulation of the mouse Na+-dependent glutamate/aspartate transporter GLAST: putative role of an AP-1 DNA binding site.
Appropriate removal of L: -glutamate from the synaptic cleft is important for prevention of the excitotoxic effects of this neurotransmitter. The Na+-dependent glutamate/aspartate transporter GLAST is regulated in the short term, by a transporter-dependent decrease in uptake activity while in the long term, a receptor's-dependent decrease in GLAST protein levels leads to a severe reduction in glutamate uptake. The promoter region of the mouse glast gene harbors an Activator Protein-1 site (AP-1). To gain insight into the molecular mechanisms triggered by Glu-receptors activation involved in GLAST regulation, we took advantage of the neonatal mouse cerebellar prisms model. We characterized the glutamate uptake activity; the glutamate-dependent effect on GLAST protein levels and over the interaction of nuclear proteins with a mouse glast promoter AP-1 probe. A time and dose dependent decrease in transporter activity matching with a decrease in GLAST levels was recorded upon glutamate treatment. Moreover, a significant increase in glast AP-1 DNA binding was found. Pharmacological experiments established that both effects are mediated through alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptors, favoring the notion of the critical involvement of glutamate in the regulation of its binding partners: receptors and transporters.
Ramírez-Sotelo
Guadalupe
G
Departamento de Genética y Biología Molecular, Cinvestav Campus Zacatenco, Apartado Postal 14-740, Mexico, D.F. 07000, Mexico.
López-Bayghen
Esther
E
Hernández-Kelly
L Clara R
LC
Arias-Montaño
J Antonio
JA
Bernabé
Alfonso
A
Ortega
Arturo
A
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D002531:Cerebellum / Q000187:drug effects / Q000502:physiology; D015536:Down-Regulation; D027341:Excitatory Amino Acid Transporter 1 / Q000096:biosynthesis* / Q000235:genetics; D005786:Gene Expression Regulation; D018698:Glutamic Acid / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D011401:Promoter Regions, Genetic; D018091:Receptors, AMPA / Q000502:physiology*; D018808:Transcription Factor AP-1 / Q000502:physiology*
D027341:Excitatory Amino Acid Transporter 1; D018091:Receptors, AMPA; C493393:Slc1a3 protein, mouse; D018808:Transcription Factor AP-1; D018698:Glutamic Acid; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione