Evaluating the role of intestinal divalent metal-ion transporter 1 (DMT1) in high dietary iron induced copper deficiency in mice

Iron (Fe) and Copper (Cu) are essential trace minerals that are important in various biological processes within the body. High iron intake has been associated with perturbations in copper metabolism leading to copper deficiency in rats and mice. We hypothesized that high dietary iron blocks intestinal copper transport via the divalent metal transporter 1 (DMT1), which is essential for iron absorption but can also transport other divalent cations, including possibly copper. Prior to conducting experiments, to evaluate the effect of high iron intake on copper status, pilot studies were conducted in male and female intestine-specific DMT1 KO (DMT1 int/int ) mice and controls (DMT1 fl/fl ) to make both genotypes similarly iron deficient/anemic. At weanling, mice were divided into groups and administered IP iron dextran at doses of 0.5, 0.75, or 1.0 mg (DMT1 int/int ), or PBS (DMT1 fl/fl ), to raise the Hb levels in the DMT1 int/int mice since they are severely anemic. DMT1 int/int mice were then fed a 50-ppm control iron AIN-93G diet, while DMT1 fl/fl mice were fed a 2-3 ppm (iron-deficient) diet, for 4 weeks. Weekly hemoglobin (Hb) measurements were taken via tail vein bleeds. For copper studies, iron status in weanling mice of both genotypes and sexes was modified based on pilot studies, and subsequently, mice were switched to experimental diets containing 1x iron (50 ppm Fe) with marginal copper (2-3 ppm Cu) or 20x iron (1000 ppm Fe) with marginal copper for 3 weeks. Biomarkers of iron and copper status were assessed including hemoglobin content and hematocrit (Hct), serum, and tissue nonheme iron concentration, blood transferrin saturation, liver hepcidin and copper transporter (Ctr1) expression and serum ceruloplasmin (Cp) activity. Outcomes showed that administration of 0.75 mg iron dextran at weanling combined with dietary intervention resulted in lowered and comparable iron status in mice of both genotypes and sexes as indicated by Hb, Hct and hepatic nonheme iron and liver hepcidin expression. In dietary copper studies, male and female DMT1 fl/fl mice fed a high iron / marginal copper diet loaded iron in the liver and spleen, while DMT1 int/int mice had significantly lower liver and spleen nonheme iron when fed the same diet. Liver hepcidin expression was elevated in both genotypes with high iron / marginal copper feeding while no changes were observed in Ctr1 expression between genotypes or diets. Serum Cp activity was decreased by 48% in female DMT1 int/int mice as compared to a 23% decrease in DMT1 fl/fl mice fed the high iron / marginal copper diet. These findings suggest that high dietary iron feeding in DMT1 int/int mice does not cause severe iron loading but leads to lower copper content when compared to DMT1 fl/fl mice. This investigation was funded by grant DK074867 from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) (JFC, PI), and grant DK109717 from NIDDK and the Office of Dietary Supplements (to JFC, PI). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.