Document Detail

Chondrocyte transport and concentration of ascorbic acid is mediated by SVCT2.
MedLine Citation:
PMID:  15921655     Owner:  NLM     Status:  MEDLINE    
Collagen II is the major protein component of articular cartilage and forms the collagen fibril network, which provides the tensile strength of cartilage. Collagen II synthesis is enhanced by ascorbic acid (vitamin C) at both a transcriptional and post-transcriptional level. While the importance of ascorbic acid in the synthesis of collagen has been established, the mechanism by which this essential nutrient is transported into chondrocytes has not been investigated previously. We have characterized the transport of the reduced form of ascorbic acid in passaged primary human chondrocytes to discern the physiologically relevant pathways of ascorbic acid transport in cartilage. We have found that chondrocytes are robust concentrators of ascorbic acid, capable of transporting the reduced form, and concentrating total ascorbic acid, in the reduced form and its metabolites, 960-fold over the concentration in the extracellular milieu. Chondrocyte transport of ascorbic acid was sodium and temperature dependent, stereoselective for the L-forms, and inhibited by the anion transport inhibitor, sulfinpyrazone. Chondrocytes preferentially expressed the full-length and functional isoform of sodium-dependent vitamin C transporter 2 (SVCT2). When this transcript was suppressed with sequence-specific siRNAs, the active transport component of ascorbic acid was abolished. Thus, we provide the first evidence that SVCT2 mediates the secondary active and concentrative transport of ascorbic acid in human chondrocytes.
Amy L McNulty; Thomas P Vail; Virginia B Kraus
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  1712     ISSN:  0006-3002     ISO Abbreviation:  Biochim. Biophys. Acta     Publication Date:  2005 Jun 
Date Detail:
Created Date:  2005-06-13     Completed Date:  2005-07-27     Revised Date:  2011-01-21    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  212-21     Citation Subset:  IM    
Department of Pathology, Duke University Medical Center, Box 3416, Durham, NC 27710, USA.
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MeSH Terms
Amino Acids / chemistry
Ascorbic Acid / chemistry*,  metabolism
Cartilage / metabolism
Cell Survival
Chondrocytes / metabolism*
Chromatography, High Pressure Liquid
Dehydroascorbic Acid / metabolism
Glucose / metabolism
Organic Anion Transporters, Sodium-Dependent / chemistry,  physiology*
RNA / chemistry,  metabolism
RNA Interference
Reverse Transcriptase Polymerase Chain Reaction
Sodium / chemistry
Sulfinpyrazone / pharmacology
Symporters / chemistry,  physiology*
Time Factors
Grant Support
Reg. No./Substance:
0/Amino Acids; 0/Organic Anion Transporters, Sodium-Dependent; 0/Symporters; 0/sodium-dependent vitamin C transporter; 490-83-5/Dehydroascorbic Acid; 50-81-7/Ascorbic Acid; 50-99-7/Glucose; 57-96-5/Sulfinpyrazone; 63231-63-0/RNA; 7440-23-5/Sodium

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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