The vitamin C transporter SVCT2 is expressed by astrocytes in culture but not in situ.
Ascorbic acid (vitamin C) is known to be selectively accumulated by brain cells through sodium-dependent vitamin C transporters. It is unclear however, whether this uptake occurs in neurons, astrocytes or both. Using Northern analysis we demonstrate that the recently cloned ascorbate transporter isoform SVCT2 is expressed by cultured astrocytes. In contrast, in situ hybridization experiments reveal that SVCT2 mRNA is expressed only in neurons and not in normal astrocytes or astrocytes stimulated by an intrastriatal injection of the neurotoxin quinolinic acid. We conclude that SVCT2 is neuron specific and that the majority of ascorbate storage occurs in neurons. Furthermore, we propose that the observed sodium-dependent ascorbate transport in cultured astrocytes may be due to artificial upregulation of SVCT2 during cell culturing.
Berger
U V
UV
Renal Division, Brigham and Women's Hospital, Harvard Medical School, Harvard Institutes of Medicine, Boston, MA 02115, USA.
Hediger
M A
MA
D000818:Animals; D001253:Astrocytes / Q000737:chemistry / Q000166:cytology / Q000502:physiology*; D015152:Blotting, Northern; D002478:Cells, Cultured; D003342:Corpus Striatum / Q000166:cytology; D003714:Denervation; D015870:Gene Expression / Q000502:physiology; D005904:Glial Fibrillary Acidic Protein / Q000032:analysis; D017403:In Situ Hybridization; D008297:Male; D009474:Neurons / Q000737:chemistry / Q000502:physiology; D029363:Organic Anion Transporters, Sodium-Dependent; D011506:Proteins / Q000235:genetics*; D017378:Quinolinic Acid; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D060347:Sodium-Coupled Vitamin C Transporters; D027981:Symporters
D005904:Glial Fibrillary Acidic Protein; D029363:Organic Anion Transporters, Sodium-Dependent; D011506:Proteins; D012333:RNA, Messenger; D060347:Sodium-Coupled Vitamin C Transporters; D027981:Symporters; D017378:Quinolinic Acid