ARS | Publication request: Approaching the cellular processes involved in the positive effect of glycosaminoglycans on Fe uptake to Caco-2 cells

Submitted to: Journal of Nutritional Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 5, 2009
Publication Date: N/A

Interpretive Summary: Our lab has developed a model for studying mineral absorption from different foods and food combinations. Food samples undergo a simulated digestion and are placed over Caco-2 cells, which act as a mimic of the intestinal lining. An increase in cell ferritin (an iron storage protein) formation was used as a measure of Fe uptake. Our past in vitro studies have indicated that meat enhances iron absorption, specially some carbohydrates such as glycosaminoglycans(GAGS) located in the extracellular matrix of muscle tissues. However, the accepted iron uptake mechanism(s) described to date would not explain the GAGs enhancing effect on Fe uptake. This study evaluates the cellular metabolic response(s) and regulation of the main accepted iron transporters in mammal cells. The obtained data will help to improve our understanding of the potential coordinated mechanism(s) present in mammalian cells to maintain iron homeostasis.

Technical Abstract: This study constitutes an approach to understand the enhancing effect of glycosaminoglycans (GAGs) on Fe uptake to Caco-2 cells. The high-sulfated GAGs fraction was isolated and purified from cooked haddock. An in vitro digestion/Caco-2 cell culture model was used to monitor Fe uptake (cell ferritin formation), and to compare the cellular responses after exposure to digests of a Fe + 3-containing solution, Fe +3/GAGs, and Fe+3/Ascorbic acid mixtures. Mitochondrial and endo-/lysosomal activities, intracellular accumulation of reactive oxygen species and GSH concentration were monitored as biomarkers of the changes on cellular iron metabolism. Changes in mRNA expression of Fe transporters, DMT1 and Dcytb, were also evaluated. GAGs produced a positive effect on Fe uptake, which was accompanied of increased endo-/lysosomal activities and a more preserved intracellular GSH concentration. The cellular responses noted in cell cultures exposed to Fe+3/GAGs mixture may suggest that Fe could be also internalized into cells by endocytosis in addition to via DMT1.