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Main Title: In Vitro Studies on Zinc Binding and Buffering by Intestinal Mucins
Author(s): Maares, Maria Henrietta
Keil, Claudia
Koza, Jenny
Straubing, Sophia
Schwerdtle, Tanja
Haase, Hajo
Type: Article
Is Part Of: 10.14279/depositonce-8353
Language Code: en
Abstract: The investigation of luminal factors influencing zinc availability and accessibility in the intestine is of great interest when analyzing parameters regulating intestinal zinc resorption. Of note, intestinal mucins were suggested to play a beneficial role in the luminal availability of zinc. Their exact zinc binding properties, however, remain unknown and the impact of these glycoproteins on human intestinal zinc resorption has not been investigated in detail. Thus, the aim of this study is to elucidate the impact of intestinal mucins on luminal uptake of zinc into enterocytes and its transfer into the blood. In the present study, in vitro zinc binding properties of mucins were analyzed using commercially available porcine mucins and secreted mucins of the goblet cell line HT-29-MTX. The molecular zinc binding capacity and average zinc binding affinity of these glycoproteins demonstrates that mucins contain multiple zinc-binding sites with biologically relevant affinity within one mucin molecule. Zinc uptake into the enterocyte cell line Caco-2 was impaired by zinc-depleted mucins. Yet this does not represent their form in the intestinal lumen in vivo under zinc adequate conditions. In fact, zinc-uptake studies into enterocytes in the presence of mucins with differing degree of zinc saturation revealed zinc buffering by these glycoproteins, indicating that mucin-bound zinc is still available for the cells. Finally, the impact of mucins on zinc resorption using three-dimensional cultures was studied comparing the zinc transfer of a Caco-2/HT-29-MTX co-culture and conventional Caco-2 monoculture. Here, the mucin secreting co-cultures yielded higher fractional zinc resorption and elevated zinc transport rates, suggesting that intestinal mucins facilitate the zinc uptake into enterocytes and act as a zinc delivery system for the intestinal epithelium.
Issue Date: 7-Sep-2018
Date Available: 15-Aug-2019
DDC Class: 540 Chemie und zugeordnete Wissenschaften
Subject(s): intestinal zinc resorption
zinc binding
mucus layer
intestinal mucins
in vitro intestinal model
goblet cells
Sponsor/Funder: DFG, 316442145, FOR 2558: Interaktionen von essenziellen Spurenelementen in gesunden und erkrankten älteren Menschen (TraceAge)
Journal Title: International Journal of Molecular Sciences
Publisher: MDPI
Publisher Place: Basel
Volume: 19
Issue: 9
Article Number: 2662
Publisher DOI: 10.3390/ijms19092662
EISSN: 1422-0067
ISSN: 1661-6596
Appears in Collections:FG Lebensmittelchemie und Toxikologie » Publications

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