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Query: UMLS:C0240066 (iron deficiency)
 7,156 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Although hepcidin expression was shown to be induced by the BMP/Smad signaling pathway, it is not yet known how iron regulates this pathway and what its exact molecular targets are. We therefore assessed genome-wide liver transcription profiles of mice of 2 genetic backgrounds fed iron-deficient, -balanced, or -enriched diets. Among 1419 transcripts significantly modulated by the dietary iron content, 4 were regulated similarly to the hepcidin genes Hamp1 and Hamp2. They are coding for Bmp6, Smad7, Id1, and Atoh8 all related to the Bmp/Smad pathway. As shown by Western blot analysis, variations in Bmp6 expression induced by the diet iron content have for functional consequence similar changes in Smad1/5/8 phosphorylation that leads to formation of heteromeric complexes with Smad4 and their translocation to the nucleus. Gene expression variations induced by secondary iron deficiency or iron overload were compared with those consecutive to Smad4 and Hamp1 deficiency. Iron overload developed by Smad4- and Hamp1-deficient mice also increased Bmp6 transcription. However, as shown by analysis of mice with liver-specific disruption of Smad4, activation of Smad7, Id1, and Atoh8 transcription by iron requires Smad4. This study points out molecules that appear to play a critical role in the control of systemic iron balance.
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PMID:Iron regulates phosphorylation of Smad1/5/8 and gene expression of Bmp6, Smad7, Id1, and Atoh8 in the mouse liver. 1853 98

Expression of hepcidin, the hormone regulating iron homeostasis, is increased by iron overload and decreased by accelerated erythropoiesis or iron deficiency. The purpose of the study was to examine the effect of these stimuli, either alone or in combination, on the main signaling pathway controlling hepcidin biosynthesis in the liver, and on the expression of splenic modulators of hepcidin biosynthesis. Liver phosphorylated SMAD 1 and 5 proteins were determined by immunoblotting in male mice treated with iron dextran, kept on an iron deficient diet, or administered recombinant erythropoietin for four consecutive days. Administration of iron increased liver phosphorylated SMAD protein content and hepcidin mRNA content; subsequent administration of erythropoietin significantly decreased both the iron-induced phosphorylated SMAD proteins and hepcidin mRNA. These results are in agreement with the recent observation that erythroferrone binds and inactivates the BMP6 protein. Administration of erythropoietin substantially increased the amount of erythroferrone and transferrin receptor 2 proteins in the spleen; pretreatment with iron did not influence the erythropoietin-induced content of these proteins. Erythropoietin-treated iron-deficient mice displayed smaller spleen size in comparison with erythropoietin-treated mice kept on a control diet. While the erythropoietin-induced increase in splenic erythroferrone protein content was not significantly affected by iron deficiency, the content of transferrin receptor 2 protein was lower in the spleens of erythropoietin-treated mice kept on iron-deficient diet, suggesting posttranscriptional regulation of transferrin receptor 2. Interestingly, iron deficiency and erythropoietin administration had additive effect on hepcidin gene downregulation in the liver. In mice subjected both to iron deficiency and erythropoietin administration, the decrease of hepcidin expression was much more pronounced than the decrease in phosphorylated SMAD protein content or the decrease in the expression of the SMAD target genes Id1 and Smad7. These results suggest the existence of another, SMAD-independent pathway of hepcidin gene downregulation.
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PMID:Effect of stimulated erythropoiesis on liver SMAD signaling pathway in iron-overloaded and iron-deficient mice. 3095 54