Inhibition of intestinal ascorbic acid uptake by lipopolysaccharide is mediated via transcriptional mechanisms

Veedamali S. Subramanian, Subrata Sabui, Hamid Moradi, Jonathan S. Marchant, Hamid M. Said

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Ascorbic acid (AA) accumulation in intestinal epithelial cells is an active transport process mainly mediated by two sodium-dependent vitamin C transporters (SVCT-1 and SVCT-2). To date, little is known about the effect of gut microbiota generated lipopolysaccharide (LPS) on intestinal absorption of water-soluble vitamins. Therefore, the objective of this study was to investigate the effects of bacterially-derived LPS on AA homeostasis in enterocytes using Caco-2 cells, mouse intestine and intestinal enteroids models. Pre-treating Caco-2 cells and mice with LPS led to a significant decrease in carrier-mediated AA uptake. This inhibition was associated with a significant reduction in SVCT-1 and SVCT-2 protein, mRNA, and hnRNA expression. Furthermore, pre-treating enteroids with LPS also led to a marked decrease in SVCT-1 and SVCT-2 protein and mRNA expression. Inhibition of SVCT-1 and SVCT-2 occurred at least in part at the transcriptional level as promoter activity of SLC23A1 and SLC23A2 was attenuated following LPS treatment. Subsequently, we examined the protein and mRNA expression levels of HNF1α and Sp1 transcription factors, which are needed for basal SLC23A1 and SLC23A2 promoter activity, and found that they were significantly decreased in the LPS treated Caco-2 cells and mouse jejunum; this was reflected on level of the observed reduction in the interaction of these transcription factors with their respective promoters in Caco-2 cells treated with LPS. Our findings indicate that LPS inhibits intestinal carrier- mediated AA uptake by down regulating the expression of both vitamin C transporters and transcriptional regulation of SLC23A1 and SLC23A2 genes.

Original languageEnglish (US)
Pages (from-to)556-565
Number of pages10
JournalBiochimica et Biophysica Acta - Biomembranes
Volume1860
Issue number2
DOIs
StatePublished - Feb 2018

Bibliographical note

Funding Information:
This study was supported by grants from the Dept. of Veterans Affairs and the National Institutes of Health (NIH) grants DK107474 (VSS), DK56061 (HMS), DK58057 (HMS), AA018071 (HMS) and GM088790 (JSM).

Publisher Copyright:
© 2017 Elsevier B.V.

Keywords

  • Enteroids
  • SVCT-1
  • SVCT-2
  • Transport
  • Uptake
  • Vitamin C

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