title: Acidic amino acid transport characteristics of a newly developed conditionally immortalized rat type 2 astrocyte cell line (TR-AST).
abstract: To characterize acidic amino acid transport in type 2 astrocytes, we established conditionally immortalized rat astrocyte cell lines (TR-AST) from newly developed transgenic rats harboring temperature-sensitive SV40 large T-antigen gene. TR-AST exhibited positive immunostaining for anti-GFAP antibody and A2B5 antibody, characteristics associated with type 2 astrocytes, and expressed glutamine synthetase. Acidic amino acid transporters, GLT-1 and system xc-, which consists of xCT and 4F2hc, were expressed in all TR-ASTs by RT-PCR. On the other hand, GLAST expression was found in TR-AST3 and 5. The characteristics of [3H]L-glutamic acid (L-Glu) uptake by TR-AST5 include an Na+-dependent and Na+-independent manner, concentration-dependence, and inhibition by L-aspartic acid (L-Asp) and D-aspartic acid (D-Asp). The corresponding Michaelis-Menten constants for the Na+-dependent and Na+-independent process were 36.3 microM and 155 microM, respectively. [3H]L-Asp and [3H]D-Asp uptake by TR-AST5 had an Na+-dependent and Na+-independent manner. This study demonstrated that GLT-1, system xc-, and GLAST were expressed in TR-AST, which has the characteristics of type 2 astrocytes and is able to transport acidic amino acids.
authors.affiliation: Department of Molecular Biopharmacy and Genetics, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Tetsuka
authors.forename: K I
authors.initials: KI
authors.lastname: Hosoya
authors.forename: S
authors.initials: S
authors.lastname: Ohtsuki
authors.forename: H
authors.initials: H
authors.lastname: Takanaga
authors.forename: N
authors.initials: N
authors.lastname: Yanai
authors.forename: M
authors.initials: M
authors.lastname: Ueda
authors.forename: M
authors.initials: M
authors.lastname: Obinata
authors.forename: T
authors.initials: T
authors.lastname: Terasaki
mesh_terms: D026922:Amino Acid Transport Systems, Acidic / Q000378:metabolism*; D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D030801:Animals, Genetically Modified; D000952:Antigens, Polyomavirus Transforming / Q000235:genetics; D001253:Astrocytes / Q000166:cytology* / Q000378:metabolism*; D001693:Biological Transport, Active; D002352:Carrier Proteins / Q000378:metabolism; D002461:Cell Line, Transformed; D027342:Excitatory Amino Acid Transporter 2 / Q000378:metabolism; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism; D007150:Immunohistochemistry; D007700:Kinetics; D008297:Male; D051381:Rats; D012964:Sodium / Q000378:metabolism; D013696:Temperature
chemical_list: D026922:Amino Acid Transport Systems, Acidic; D000596:Amino Acids; D000952:Antigens, Polyomavirus Transforming; D002352:Carrier Proteins; D027342:Excitatory Amino Acid Transporter 2; D012964:Sodium; D005974:Glutamate-Ammonia Ligase