| Modulation of Function of Sodium-Dependent Vitamin C Transporter 1 (SVCT1) by Rab8a in Intestinal Epithelial Cells: Studies Utilizing Caco-2 Cells and Rab8a Knockout Mice. | |
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MedLine Citation:
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PMID: 23014846 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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BACKGROUND: Ascorbic acid (AA) is required for normal human health and development. Human intestine expresses two sodium-dependent vitamin C transporters (hSVCT-1 and -2) that mediate cellular AA transport, with hSVCT1 targeting to the apical membrane of polarized epithelia. Studies have shown a role for the Rab8a in the apical membrane targeting of transporters in intestinal cells. AIMS: The purpose of this study was to determine whether Rab8a impacts the function and/or targeting of hSVCT1, and intestinal AA uptake. METHODS: We used human intestinal cells and cells from a Rab8a knockout mouse. (14)C-AA uptake was performed to determine functionality. PCR and western blotting were performed to determine RNA and protein expression, respectively. Confocal imaging was performed to determine co-localization. RESULTS: We show that hSVCT1 co-localized with Rab8a in intestinal cells. Knockdown of Rab8a lead to a significant inhibition in AA uptake and cell surface biotinylation studies revealed a lower cell surface expression of hSVCT1 in Rab8a siRNA-treated cells. Similarly, in the small intestine of a Rab8a knockout mouse, AA uptake was significantly inhibited. This effect again resulted from a decreased expression level of mSVCT1 protein, even though mRNA expression of SVCT1 was similar in intestinal cells from Rab8a knockout and wild-type litter-mates. The latter data are suggestive of enhanced lysosomal degradation of hSVCT1 protein in Rab8a-deficient cells; indeed, confocal imaging of Rab8a siRNA-treated intestinal cells revealed a strong overlap between hSVCT1-YFP and LAMP1-RFP. CONCLUSIONS: These findings show a role for Rab8a in the physiological function of hSVCT1 in intestinal epithelia. |
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Authors:
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Veedamali S Subramanian; Sandeep B Subramanya; Abhisek Ghosal; Jonathan S Marchant; Akihiro Harada; Hamid M Said |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2012-9-27 |
Journal Detail:
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Title: Digestive diseases and sciences Volume: - ISSN: 1573-2568 ISO Abbreviation: Dig. Dis. Sci. Publication Date: 2012 Sep |
Date Detail:
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Created Date: 2012-9-27 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 7902782 Medline TA: Dig Dis Sci Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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Departments of Medicine, Physiology and Biophysics, University of California, Irvine, CA, 92697, USA, vsubrama@uci.edu. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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