Expression and regulation of L-cystine transporter, system xc-, in the newly developed rat retinal Müller cell line (TR-MUL).
The purpose of the present study was to elucidate the expression and regulation of the L-cystine transporter, system x(c) (-), in Müller cells. In this study, newly developed conditionally immortalized rat Müller cell lines (TR-MUL) from transgenic rats harboring the temperature-sensitive SV 40 large T-antigen gene were used as an in vitro model. TR-MUL cells express large T-antigen and grow well at 33 degrees C with a doubling time of 30 h, but do not grow at 39 degrees C. TR-MUL cells express typical Müller cell markers such as S-100, glutamine synthetase, and EAAT1/GLAST, whereas EAAT2/GLT-1 and EAAT5 are not detected. TR-MUL cells also exhibit little or no expression of glial fibrillary acidic protein. We found that TR-MUL5 cells exhibited [(14)C]L-cystine uptake activity and expressed xCT and 4F2hc, which involve system x(c) (-). The uptake of [(14)C]L-cystine was significantly inhibited by L-glutamic acid and L-aspartic acid, whereas L-leucine had no effect. Following diethyl maleate (DEM) treatment, the glutathione concentration in TR-MUL5 cells was reduced in the first 24 h, then gradually recovered for more than 24 h. The L-cystine uptake rate and the xCT expression level in TR-MUL5 cells were enhanced by DEM treatment. In contrast, the 4F2hc expression level was unchanged. In conclusion, TR-MUL cells have the properties of Müller cells and exhibit system x(c) (-)-mediated L-cystine uptake activity. The oxidative stress conditions following DEM treatment activate L-cystine transport in TR-MUL cells due to the enhanced transcription of the xCT gene.
Tomi
Masatoshi
M
Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, Toyama, Japan.
Funaki
Takeshi
T
Abukawa
Hayato
H
Katayama
Kazunori
K
Kondo
Tetsu
T
Ohtsuki
Sumio
S
Ueda
Masatsugu
M
Obinata
Masuo
M
Terasaki
Tetsuya
T
Hosoya
Ken-Ichi
K
D000818:Animals; D030801:Animals, Genetically Modified; D000957:Antigens, Viral, Tumor / Q000235:genetics; D001224:Aspartic Acid / Q000494:pharmacology; D015415:Biomarkers; D002352:Carrier Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D002461:Cell Line, Transformed; D003553:Cystine / Q000378:metabolism*; D027282:Fusion Regulatory Protein 1, Heavy Chain / Q000378:metabolism; D018698:Glutamic Acid / Q000494:pharmacology; D005978:Glutathione / Q000378:metabolism; D008297:Male; D008298:Maleates / Q000494:pharmacology; D008954:Models, Biological; D009457:Neuroglia / Q000166:cytology / Q000378:metabolism*; D018384:Oxidative Stress / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000166:cytology / Q000378:metabolism*; D012164:Retinal Diseases / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
D000957:Antigens, Viral, Tumor; D015415:Biomarkers; D002352:Carrier Proteins; D027282:Fusion Regulatory Protein 1, Heavy Chain; D008298:Maleates; D001224:Aspartic Acid; D018698:Glutamic Acid; D003553:Cystine; C014476:diethyl maleate; D005978:Glutathione