Gamma-aminobutyric acid transporter (BGT-1) expressed in human astrocytoma U373 MG cells: pharmacological and molecular characterization and phorbol ester-induced inhibition.
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Ruiz-Tachiquin ME, Sanchez-Lemus E, Soria-Jasso LE, Arias-Montano JA, Ortega A
Gamma-aminobutyric acid transporter (BGT-1) expressed in human astrocytoma U373 MG cells: pharmacological and molecular characterization and phorbol ester-induced inhibition.
J Neurosci Res. 2002 Jul 1;69(1):125-32.
- PubMed ID
- 12111824 [ View in PubMed]
- Abstract
The properties of a transport system specific for gamma-aminobutyric acid (GABA) expressed in human U373 MG astrocytoma cells were examined. The uptake of [(3)H]GABA was dependent on both extracellular Na(+) and Cl(-) ions and was inhibited by (+/-)-nipecotic acid, guvacine, and beta-alanine, with a pharmacological profile corresponding to that reported for the human homologue of the GABA/betaine transporter (BGT-1). Accordingly, [(3)H]GABA uptake was also inhibited by betaine, and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of total RNA from U373 MG cells with specific BGT-1 primers resulted in the amplification of a 440 bp fragment that was further characterized by restriction analysis and sequencing. In addition, Western blot analysis with anti-BGT-1 antiserum revealed the presence of a characteristic 60 kDa band. The primary structure of the human BGT-1 protein predicts two putative phosphorylation sites for the Ca(2+)/diacylglicerol-dependent protein kinase (PKC), and treatment of U373 MG cells with the PKC activator phorbol 12-myristate-13-acetate (TPA) led to a concentration- and time-dependent decrease in [(3)H]GABA uptake. The maximal effect was detected at 2 hr of incubation, to disappear after 4 hr. TPA-induced reduction in [(3)H]GABA uptake was reversed by preincubation with staurosporine. Taken together, these results indicate that U373 MG cells express a GABA transporter of the BGT-1 subtype whose function is regulated by phosphorylation events through PKC.
DrugBank Data that Cites this Article
- Drug Targets
Drug Target Kind Organism Pharmacological Action Actions Guvacine Sodium- and chloride-dependent betaine transporter Protein Humans UnknownInhibitorDetails