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Digestive Diseases and Sciences
Article . 2012 . Peer-reviewed
License: Springer TDM
Data sources: Crossref
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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

Authors: Veedamali S, Subramanian; Sandeep B, Subramanya; Abhisek, Ghosal; Jonathan S, Marchant; Akihiro, Harada; Hamid M, Said;

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

Abstract

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.The purpose of this study was to determine whether Rab8a impacts the function and/or targeting of hSVCT1, and intestinal AA uptake.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.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.These findings show a role for Rab8a in the physiological function of hSVCT1 in intestinal epithelia.

Keywords

Mice, Knockout, Blotting, Western, Ascorbic Acid, Real-Time Polymerase Chain Reaction, Mice, Protein Transport, rab GTP-Binding Proteins, Gene Knockdown Techniques, Animals, Humans, Gene Silencing, Amino Acids, Caco-2 Cells, Intestinal Mucosa, RNA, Small Interfering, Sodium-Coupled Vitamin C Transporters

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citations
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
7
Average
Average
Average
bronze