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Gut. Feb 2000; 46(2): 270–276.
PMCID: PMC1727808

Localisation of divalent metal transporter 1 (DMT1) to the microvillus membrane of rat duodenal enterocytes in iron deficiency, but to hepatocytes in iron overload

Abstract

BACKGROUND—The mechanism of iron absorption by the intestine and its transfer to the main iron storage site, the liver, is poorly understood. Recently an iron carrier was cloned and named DMT1 (divalent metal transporter 1).
AIMS—To determine the level of DMT1 gene expression and protein distribution in duodenum and liver.
METHODS—A DMT1 cRNA and antibody were produced and used in in situ hybridisation and immunohistochemistry, respectively, in rats in which the iron stores were altered by feeding diets with normal, low, and high iron content.
RESULTS—Duodenal DMT1 mRNA was low in crypts and increased at the crypt-villus junction in iron deficient and control rats; it fell in the iron loaded state. Staining for DMT1 protein was not detected in crypts. In villus enterocytes, protein staining was localised to the microvillus membrane in iron deficiency, in the cytoplasm and to a lesser extent in the membrane in controls, and entirely in the cytoplasm of iron loaded animals. Liver DMT1 mRNA was distributed evenly across hepatocytes. DMT1 protein staining was observed on hepatocyte plasma membranes, with highest values in the iron loaded state, lower values in control animals, and none after iron depletion.
CONCLUSIONS—Results are consistent with a role for DMT1 in the transmembrane transport of non-transferrin bound iron from the intestinal lumen and from the portal blood.


Keywords: DMT1; iron transporters; iron absorption; duodenum; liver

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Selected References

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Figures and Tables

Figure 1
In situ hybridisation using an antisense rat DMT1 cRNA of the duodenum of an iron deficient (A), control (B), and iron loaded (C) rat. In all cases low levels of DMT1 mRNA expression were seen in cells lining the upper half of the crypt (below arrow). ...
Figure 2
Immunohistochemical localisation of rat DMT1 protein using a polyclonal antibody in the duodenum of iron deficient (A,B,C) and control tissue (D,E). No staining was observed in epithelial cells of the crypt region (A,D; below arrow). In the villus region ...
Figure 3
In situ hybridisation using DMT1 cRNA of liver tissue from control animals (A). DMT1 mRNA was seen in the cytoplasm of hepatocytes with an even distribution across the liver. Immunohistochemical localisation of DMT1 in iron deficient (B), control (C), ...

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