Expression Of Iron-related Proteins Research Articles

Effect of Hypoxia-Ischemia on the Expression of Iron-Related Proteins in Neonatal Rat Brains.

Hypoxic-ischemic white matter injury (WMI) pathogenesis in preterm infants is not well established, and iron-related proteins in the brain may play an important role in imbalanced iron metabolism. We aimed to investigate the iron-related protein changes in neonatal rats after hypoxia-ischemia (HI), clarify the role of iron-related proteins in hypoxic-ischemic WMI, and potentially provide a new target for the clinical treatment of hypoxic-ischemic WMI in preterm infants. We adopted a WMI animal model of bilateral common carotid artery electrocoagulation combined with hypoxia in neonatal 3-day-old Sprague-Dawley rats. We observed basic myelin protein (MBP) and iron-related protein expression in the brain (ferritin, transferrin receptor [TfR], and membrane iron transporter 1 [FPN1]) via Western blot and double immunofluorescence staining. The expression of MBP in the WMI group was significantly downregulated on postoperative days (PODs) 14, 28, and 56. Ferritin levels were significantly increased on PODs 3, 7, 14, and 28 and were most significant on POD 28, returning to the sham group level on POD 56. FPN1 levels were significantly increased on PODs 7, 28, and 56 and were still higher than those in the sham group on POD 56. TfR expression was significantly upregulated on PODs 1, 7, and 28 and returned to the sham group level on POD 56. Immunofluorescence staining showed that ferritin, TfR, and FPN1 were expressed in neurons, blood vessels, and oligodendrocytes in the cortex and corpus callosum on POD 28. Compared with the sham group, the immune-positive markers of three proteins in the WMI group were significantly increased. The expression of iron-related proteins in the brain (ferritin, FPN1, and TfR) showed spatiotemporal dynamic changes and may play an important role in hypoxic-ischemic WMI.

Expression of iron-related proteins in feline and canine mammary gland reveals unexpected accumulation of iron

Dysregulation of cellular iron homeostasis in human breast cancer is reflected by the altered expression of regulatory proteins. The expressions of iron-related proteins in the mammary glands of cats and dogs have not been assessed. We evaluated the expressions of ferritin, ferroportin, hepcidin and transferrin receptor 1 in benign and malignant mammary gland lesions in cats and dogs. Iron deposition was detected using Perls’ Prussian blue staining. We found no major differences in the expression of iron-related proteins between benign and malignant mammary gland lesions in either cats or dogs; however, these species exhibited accumulation of iron in benign lesions. Our findings provide an explanation for the absence of higher iron requirements by tumor cells in these animals. Further investigation of local iron homeostasis in cats and dogs and differences in their physiology compared to human breast cancer is required.

HFE Variants and the Expression of Iron-Related Proteins in Breast Cancer-Associated Lymphocytes and Macrophages.

The association of HFE (High Iron FE) major variants with breast cancer risk and behavior has been a matter of discussion for a long time. However, their impact on the expression of iron-related proteins in the breast cancer tissue has never been addressed. In the present study, hepcidin, ferroportin 1, transferrin receptor 1 (TfR1), and ferritin expressions, as well as tissue iron deposition were evaluated in a collection of samples from breast cancers patients and analyzed according to the patients' HFE genotype. Within the group of patients with invasive carcinoma, those carrying the p.Cys282Tyr variant in heterozygosity presented a higher expression of hepcidin in lymphocytes and macrophages than wild-type or p.His63Asp carriers. An increased expression of TfR1 was also observed in all the cell types analyzed but only in p.Cys282Tyr/p.His63Asp compound heterozygous patients. A differential impact of the two HFE variants was further noticed with the observation of a significantly higher percentage of p.Cys282Tyr heterozygous patients presenting tissue iron deposition in comparison to p.His63Asp heterozygous. In the present cohort, no significant associations were found between HFE variants and classical clinicopathological markers of breast cancer behavior and prognosis. Although limited by a low sampling size, our results provide a new possible explanation for the previously reported impact of HFE major variants on breast cancer progression, i.e., not by influencing systemic iron homeostasis but rather by differentially modulating the local cellular expression of iron-related proteins and tissue iron deposition.

Expression of Iron-Related Proteins at the Neurovascular Unit Supports Reduction and Reoxidation of Iron for Transport Through the Blood-Brain Barrier.

The mechanisms for iron transport through the blood-brain barrier (BBB) remain a controversy. We analyzed for expression of mRNA and proteins involved in oxidation and transport of iron in isolated brain capillaries from dietary normal, iron-deficient, and iron-reverted rats. The expression was also investigated in isolated rat brain endothelial cells (RBECs) and in immortalized rat brain endothelial (RBE4) cells grown as monoculture or in hanging culture inserts with defined BBB properties. Transferrin receptor 1, ferrireductases Steap 2 and 3, divalent metal transporter 1 (DMT1), ferroportin, soluble and glycosylphosphatidylinositol (GPI)-anchored ceruloplasmin, and hephaestin were all expressed in brain capillaries in vivo and in isolated RBECs and RBE4 cells. Gene expression of DMT1, ferroportin, and soluble and GPI-anchored ceruloplasmin were significantly higher in isolated RBECs with induced BBB properties. Primary pericytes and astrocytes both expressed ceruloplasmin and hephaestin, and RBECs, pericytes, and astrocytes all exhibited ferrous oxidase activity. The coherent protein expression of these genes was demonstrated by immunocytochemistry. The data show that brain endothelial cells provide the machinery for receptor-mediated uptake of ferric iron-containing transferrin. Ferric iron can then undergo reduction to ferrous iron by ferrireductases inside endosomes followed by DMT1-mediated pumping into the cytosol and subsequently cellular export by ferroportin. The expression of soluble ceruloplasmin by brain endothelial cells, pericytes, and astrocytes that together form the neurovascular unit (NVU) provides the ferroxidase activity necessary to reoxidize ferrous iron once released inside the brain.

Relative quantification of the effect of blood meal iron on protein expression in the ovaries of Aedes aegypti (778.8)

Diseases transmitted by mosquitoes are estimated to kill more than 2 million people annually. The vector for dengue, Aedes aegypti (yellow fever mosquito), is found in the desert Southwest of the continental United States. One approach to limiting the spread of disease is to reduce the numbers of mosquito vectors. Our area of research is iron metabolism. Our long term goal is to use molecular techniques to alter the expression of iron related proteins in mosquitoes to reduce mosquito fecundity and survival. Our hypothesis is that female mosquitoes require iron in the blood meal as an essential nutrient to aid in egg development. Although the iron is necessary for fecundity it is also highly oxidative and toxic in biological systems unless the mineral is strictly regulated to mitigate its oxidative potential. We are currently analyzing tissue‐specific, iron regulated proteins of the mosquito ovary 24 h post‐blood meal fed on artificial blood meal diets supplemented with no iron or low iron, or a porcine blood meal (high iron). Measurement of the blood meal iron effect on ovarian protein expression was carried out using Tandem Mass Tags (TMT) which permits simultaneous identification and relative quantification of proteins during LTQ Velos Orbitrap LC‐MS/MS analysis. This research will contribute to our understanding of mosquito development in general, as well as ovarian iron metabolism.Grant Funding Source: Supported by funds from the Arizona Ag Experiment Station and CALS

Expression of iron-related proteins in the duodenum is up-regulated in patients with chronic inflammatory disorders

Mechanisms responsible for derangements in Fe homeostasis in chronic inflammatory conditions are not entirely clear. The aim of the present study was to test the hypothesis that inflammation affects the expression of Fe-related proteins in the duodenum and monocytes of patients with chronic inflammatory disorders, thus contributing to dysregulated Fe homeostasis. Duodenal mucosal samples and peripheral blood monocytes obtained from patients with chronic inflammatory disorders, namely ulcerative colitis (UC), Crohn's disease (CD) and rheumatoid arthritis, were used for gene and protein expression studies. Hb levels were significantly lower and serum C-reactive protein levels were significantly higher in patients in the disease groups. The gene expression of several Fe-related proteins in the duodenum was significantly up-regulated in patients with UC and CD. In patients with UC, the protein expression of divalent metal transporter 1 and ferroportin, which are involved in the absorption of dietary non-haem Fe, was also found to be significantly higher in the duodenal mucosa. The gene expression of the duodenal proteins of interest correlated positively with one another and negatively with Hb. In patients with UC, the gene expression of Fe-related proteins in monocytes was found to be unaffected. In a separate group of patients with UC, serum hepcidin levels were found to be significantly lower than those in the control group. In conclusion, the expression of Fe-related proteins was up-regulated in the duodenum of patients with chronic inflammatory conditions in the present study. The effects appeared to be secondary to anaemia and the consequent erythropoietic drive.

Iron Accumulation and Expression of Iron-Related Proteins Following Murine Exposure to Crocidolite

We tested the postulate that asbestos exposure alters iron homeostasis in the mouse lung. Crocidolite asbestos (100 microg intratracheally) was instilled into C57BL/6 mice. TiO2 served as a control exposure. Using iron staining and immunohistochemistry, concentrations of this metal and expression of several iron transport and storage proteins were evaluated at one day and one month following asbestos exposure. Iron was not stainable one day following asbestos instillation but was increased one month later. There was an elevated expression of duodenal cytochrome b (Dcytb), divalent metal transporter 1 (DMT1), and ferritin at both one day and one month after crocidolite exposure. While ferroportin (FPN1) expression was increased one day after asbestos exposure, levels of this metal exporter had returned to baseline at one month. TiO2 did not affect changes in either the iron concentration or the expression of these iron-related proteins at one day and one month. We conclude that asbestos exposure alters lung iron homeostasis with an accumulation of the metal resulting. Elevations in available iron affect changes in the expression of Dcytb, DMT1, ferritin, and FPN1, which further modify metal homeostasis in the lung.

Differential expression of transferrin receptor in duodenal mucosa in iron overload: Evidence for a site-specific defect in genetic hemochromatosis

In genetic hemochromatosis, metabolic studies have demonstrated inappropriately increased iron absorption by cells of the duodenal mucosa. It is not clear whether this reflects an intrinsic abnormality of iron homeostasis at this site or is a consequence of a more generalized defect in cellular iron metabolism particularly involving the liver. We have previously used the expression of iron-related proteins as markers of iron homeostasis and have demonstrated normal regulation of the transferrin receptor and ferritin in the liver in this condition. In the present study we used immunohistochemical techniques to study transferrin-receptor expression in the gastrointestinal epithelium in normal subjects and patients with iron overload. In untreated genetic hemochromatosis and normal subjects, villus epithelial cells expressed receptor in the basolateral, subnuclear region. In contrast, in patients with secondary iron overload, receptor staining was absent in villus epithelial cells. The cells in the duodenal crypts showed intense staining for the transferrin receptor in all subjects investigated, a finding consistent with the known behavior of this receptor in proliferating cells. Given that body iron stores in both types of iron overload were comparable, these findings indicating a failure of down-regulation of the villus enterocyte transferrin receptor in genetic hemochromatosis may reflect the presence of a regulatory defect associated with the inability to control iron absorption in this condition.