Wnt signaling induces GLT-1 expression in rat C6 glioma cells.
The regulation of glial and neuronal Na+-dependent glutamate/aspartate transporters is of interest because abnormal glutamate transport may be responsible for certain neurological diseases. Because expression of the Wnt-1 protooncogene results in induction of the glial-type glutamate transporter GLAST in PC12 neuron-like cells, we have evaluated the effect of Wnt-1-induced signaling on glutamate transporter expression in rat C6 glioma cells. C6 cells are known normally to express EAAC1, a neuronal glutamate transporter, but not the GLAST or the GLT-1 glutamate transporter. C6 cells that ectopically expressed Wnt-1 contained a GLT-1 RNA species similar in size (>10 kb) to the GLT-1 transcript present in rat brain, and they also contained a previously unreported 3.3-kb GLT-1 RNA species. Both GLT-1 RNAs contain large parts of the coding region. However, the 3.3-kb GLT-1 species contains at least one small deletion within the coding region. The Wnt-1-expressing C6 cells contained little, if any, GLT-1 protein as determined by immunological techniques. We suggest that one or both of the GLT-1 RNA species induced by Wnt-1 either fail to be translated or yield abnormal translation products that are quickly degraded. Wnt-1-expressing C6 cells may thus represent a novel in vitro system for studying GLT-1 transporter expression at the transcriptional and/or posttranscriptional levels.
Palos
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TP
Department of Biological Chemistry, School of Medicine, University of California, Los Angeles 90095, USA.
Zheng
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Howard
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BD
D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis* / Q000235:genetics; D027322:Amino Acid Transport System X-AG; D000818:Animals; D001692:Biological Transport; D015152:Blotting, Northern; D015153:Blotting, Western; D005910:Glioma; D007150:Immunohistochemistry; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D012190:Retroviridae / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D014407:Tumor Cells, Cultured; D051153:Wnt Proteins; D051155:Wnt1 Protein; D029961:Zebrafish Proteins
D018528:ATP-Binding Cassette Transporters; D027322:Amino Acid Transport System X-AG; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D051153:Wnt Proteins; D051155:Wnt1 Protein; C495245:Wnt1 protein, rat; D029961:Zebrafish Proteins