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A Rapid and Specific Microplate Assay for the Determination of Intra- and Extracellular Ascorbate in Cultured Cells
Published on: April 11, 2014
Ascorbic acid uptake affects ferritin, Dcytb and Nramp2 expression in Caco-2 cells.
Nathalie M Scheers1, Ann-Sofie Sandberg
1Dept. of Chemical and Biological Engineering/Food Science, Chalmers University of Technology, 412 96, Goteborg, Sweden. nathalie.scheers@chalmers.se
European Journal of Nutrition
|September 26, 2008
Summary
Ascorbic acid (vitamin C) influences iron metabolism in intestinal cells by affecting ferritin, Nramp2, and Dcytb expression. This study reveals both iron-dependent and independent effects of vitamin C on iron uptake and storage.
Area of Science:
- Cellular biology
- Nutritional science
- Gastroenterology
Background:
- Ascorbic acid (vitamin C) is known to enhance iron absorption in the human intestine, primarily attributed to its ability to reduce ferric iron to ferrous iron.
- Emerging research suggests additional effects of ascorbic acid on cellular iron metabolism that warrant further investigation, particularly in the absence of extracellular iron.
Purpose of the Study:
- To investigate the impact of intracellular ascorbic acid uptake on iron acquisition in the Caco-2 cell line.
- To examine the expression of key iron-related proteins: ferritin, Nramp2, and duodenal ferric reductase (Dcytb).
Main Methods:
- Utilized the human Caco-2 cell model to study interactions between ascorbic acid and iron.
- Employed SDS-PAGE and Western blotting to analyze Nramp2 and Dcytb protein expression.
- Quantified cellular ferritin content using a commercial kit and intracellular ascorbic acid levels via HPLC.
Main Results:
- Ascorbic acid uptake significantly increased both iron-independent (19%) and iron-dependent (470%) ferritin formation.
- Long-term exposure to ascorbic acid down-regulated Nramp2 (8-29%) and Dcytb (31-50%) expression.
- Short-term exposure to ascorbic acid up-regulated Nramp2 and Dcytb, with iron's effect on Nramp2 being more pronounced without ascorbic acid.
Conclusions:
- Intracellular ascorbic acid levels critically influence ferritin production in Caco-2 cells, potentially explaining inter-laboratory variations in iron uptake studies.
- Observed long-term down-regulation of Nramp2 and Dcytb aligns with human studies showing no change in iron status with chronic vitamin C supplementation.
- Short-term up-regulation of Nramp2 and Dcytb supports findings of improved iron absorption with acute vitamin C intake.
