Ultrastructure of the duodenal mucosa of mice with a hereditary defect in iron absorption

Bédard, Yvan C.; Pinkerton, P. H.; Simon, Gérard

doi:10.1002/path.1711040106

Cited by 10 publications

(2 citation statements)

References 27 publications

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“…Their studies showed accumulation of iron in the apical area of duodenal villous cells with in ferritin. The presence of maximal 55 Fe radioactivity at 5 min over the brush border and terminal web was demonstrated by Bedard et al [28] . They observed that during the next 3 h, radioactivity was present almost exclusively in absorptive cells and in lamina propria.…”

Section: Discussionmentioning

confidence: 81%

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Evidence for a sequential transfer of iron amongst ferritin, transferrin and transferrin receptor during duodenal absorption of iron in rat and human

Kolachala

Sesikeran²,

Nair³

2007

WJG

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according to the iron nutrition in humans, with intense staining of transferrin receptor observed in iron deficient subjects. CONCLUSION:It is concluded that the intestine takes up iron through a sequential transfer involving interaction of luminal transferrin, transferrin-transferrin receptor and ferritin. INTRODUCTIONIron homeostasis is accomplished by regulating absorption in the proximal small intestine and is regulated according to the body's needs. Failure to maintain this equilibrium leads to pathological conditions resulting in either iron deficiency or iron overload. Iron deficiency anemia remains the most important micronutrient deficiency world wide. Iron is essential because of its unique ability to serve as both an electron donor and acceptor. Because of iron's virtual insolubility and potential toxicity under physiological conditions, special molecules have evolved for its acquisition, transport and storage in soluble, nontoxic form. In humans, heme iron is absorbed more efficiently than non-heme iron [1] . Recent studies demonstrate that non-heme iron is transported into the cell in the ferrous [Fe (Ⅱ)] form, mainly by carrier divalent metal transporter 1 (DMT1)-also known as natural resistance associated macrophage protein 2 (Nramp2) or divalent cation transporter 1 (DCT1) [2] . However, iron absorption is not impaired by mutation of DMT-1, suggesting that DMT-1 is not the only transporter operating within the endosomes of crypt cells. Studies of Conrad et al [3] , showed that ferric iron is absorbed by β3 integrin and mobilferrin pathway which is shared with other nutritional metals .In last few decades, several candidate proteins involved METHODS:Incorporation of 59 Fe into mucosal and luminal proteins was carried out in control WKY rats. The sequential transfer of iron amongst ferritin, transferrin and transferrin receptor was carried out in iron deficient, c o nt ro l a nd iro n overloaded rats. The duodenal proteins were subjected to immunoprecipitation and quantitation by specific ELISA and in situ localization by microautoradiography and immunohistochemistry in tandem duodenal sections. Human duodenal biopsy (n = 36) collected from subjects with differing iron status were also stained for these proteins. RESULTS:Ferritin was identified as the major protein that incorporated iron in a time-dependent manner in the duodenal mucosa. The concentration of mucosal ferritin was significantly higher in the iron excess group compared to control, iron deficient groups (731.5 ± 191.96 vs 308.3 ± 123.36, 731.5 ± 191.96 vs 256.0 ± 1.19, P < 0.005), while that of luminal transferrin which was significantly higher than the mucosal did not differ among the groups (10.9 ± 7.6 vs 0.87 ± 0.79, 11.1 ± 10.3 vs 0.80 ± 1.20, 6.8 ± 4.7 vs 0.61 ± 0.63, P < 0.001). In situ grading of proteins and iron, and their superimposition, suggested the occurrence of a sequential transfer of iron. This was demonstrated to occur through the initial binding of iron to luminal transferrin then to absorptive cell surface tran...

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Section: Discussionmentioning

confidence: 81%

“…Autoradiographic studies by Conrad and Crosby [30] and Bedard et al [28] also suggest that intestinal crypt cells are able to take up transferrinbound iron from circulation. According to some other investigators, however, transferrin is unlikely to be a major transporter of iron from lumen to the baso-lateral membrane [31][32][33] .…”

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confidence: 99%