Functional expression of sodium-dependent vitamin C transporter 2 in human endothelial cells.
Since oxidative stress plays an important role in dysregulation of the microcirculation as well as the pathogenesis of atherosclerosis, therapeutic intervention with antioxidants has been speculated to prevent cardiovascular diseases. Ascorbic acid (AA) has been reported to improve endothelial function; however, its intracellular metabolic pathway has not been fully determined. Sodium-dependent vitamin C transporter (SVCT) types 1 and 2 were recently cloned. In the present study, we investigated whether SVCT-2 is functionally expressed in vascular endothelial cells and, if so, what factors modulate its activity. The uptake of AA into human umbilical vein endothelial cells (HUVECs) was examined by incubation with radiolabeled AA (14C-AA). AA was transported into HUVECs in a dose- and time-dependent manner. Replacement of sodium chloride with choline chloride in the medium suppressed the uptake of AA. RT-PCR revealed that HUVECs expressed SVCT-2 mRNA, but not SVCT-1. Transfection of HUVECs with the antisense oligonucleotide of SVCT-2 significantly suppressed the uptake of AA. Furthermore, tumor necrosis factor-alpha and interleukin-1beta inhibited the transport activity of AA. Thus, SVCT-2 is functionally expressed in human endothelial cells, and its activity is negatively regulated by inflammatory cytokines. Our findings might provide a new insight into understanding the treatment of cardiovascular diseases with AA.
Seno
Tadashi
T
Division of Cardiovascular and Respiratory Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan.
Inoue
Nobutaka
N
Matsui
Kiyoko
K
Ejiri
Junya
J
Hirata
Ken-Ichi
K
Kawashima
Seinosuke
S
Yokoyama
Mitsuhiro
M
D001205:Ascorbic Acid / Q000037:antagonists & inhibitors / Q000493:pharmacokinetics; D001692:Biological Transport; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000378:metabolism*; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D029363:Organic Anion Transporters, Sodium-Dependent / Q000235:genetics / Q000378:metabolism*; D010693:Phloretin / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D060347:Sodium-Coupled Vitamin C Transporters; D027981:Symporters / Q000235:genetics / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D007375:Interleukin-1; D016376:Oligonucleotides, Antisense; D029363:Organic Anion Transporters, Sodium-Dependent; D012333:RNA, Messenger; C555163:SLC23A2 protein, human; D060347:Sodium-Coupled Vitamin C Transporters; D027981:Symporters; D014409:Tumor Necrosis Factor-alpha; D013755:Tetradecanoylphorbol Acetate; D001205:Ascorbic Acid; D010693:Phloretin