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Molecular mechanism(s) involved in differential expression of vitamin C transporters along the intestinal tract. Am J Physiol Gastrointest Liver Physiol 2017 Apr 01;312(4):G340-G347

Date

12/10/2016

Pubmed ID

27932501

Pubmed Central ID

PMC5407060

DOI

10.1152/ajpgi.00369.2016

Scopus ID

2-s2.0-85016973750   11 Citations

Abstract

Mammalian cells utilize two transporters for the uptake of ascorbic acid (AA), Na+-dependent vitamin C transporter SVCT-1 and SVCT-2. In the intestine, these transporters are involved in AA absorption and are expressed at the apical and basolateral membrane domains of the polarized epithelia, respectively. Little is known about the differential expression of these two transporters along the anterior-posterior axis of the intestinal tract and the molecular mechanism(s) that dictate this pattern of expression. We used mouse and human intestinal cDNAs to address these issues. The results showed a significantly lower rate of carrier-mediated AA uptake by mouse colon than jejunum. This was associated with a significantly lower level of expression of SVCT-1 and SVCT-2 at the protein, mRNA, and heterogeneous nuclear RNA (hnRNA) levels in the colon than the jejunum, implying the involvement of transcriptional mechanism(s). Similarly, expression levels of SVCT-1 and SVCT-2 mRNA and hnRNA were significantly lower in human colon. We also examined the levels of expression of hepatocyte nuclear factor 1α and specificity protein 1, which drive transcription of the Slc23a1 and Slc23a2 promoters, respectively, and found them to be markedly lower in the colon. Furthermore, significantly lower levels of the activating markers for histone (H3) modifications [H3 trimethylation of lysine 4 (H3K4me3) and H3 triacetylation of lysine 9 (H3K9ac)] were observed in the Slc23a1 and Slc23a2 promoters in the colon. These findings show, for the first time, that SVCT-1 and SVCT-2 are differentially expressed along the intestinal tract and that this pattern of expression is, at least in part, mediated via transcriptional/epigenetic mechanisms.NEW & NOTEWORTHY Our findings show, for the first time, that transporters of the water-soluble vitamin ascorbic acid (i.e., the vitamin C transporters SVCT-1 and SVCT-2) are differentially expressed along the length of the intestinal tract and that the pattern of expression is mediated, at least in part, by transcriptional and epigenetic mechanism(s) affecting both Slc23a1 and Slc23a2 genes.

Author List

Subramanian VS, Srinivasan P, Wildman AJ, Marchant JS, Said HM

Author

Jonathan S. Marchant PhD Chair, Professor in the Cell Biology, Neurobiology and Anatomy department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Adolescent
Adult
Animals
Colon
DNA Methylation
Female
Gene Expression Regulation
Humans
Jejunum
Male
Mice
Middle Aged
Organ Specificity
Promoter Regions, Genetic
Sodium-Coupled Vitamin C Transporters
Young Adult
jenkins-FCD Prod-482 91ad8a360b6da540234915ea01ff80e38bfdb40a