Expression Of Iron Metabolism Proteins Research Articles

The Relation of the Iron Metabolism Index to the Vulnerability Index of Carotid Plaque with Different Degrees of Stenosis.

To investigate the differences in serum iron index and iron metabolizing protein expression in plaques in patients with different degrees of carotid artery stenosis and the relationship with plaque traits. A total of 100 patients eligible for carotid endarterectomy (CEA) from August 2021 to February 2022 were included. Patients completed a computed tomography (CTA) scan for patient grouping and a magnetic resonance imaging (MRI) for precise quantification of carotid plaque traits within 1 week prior to surgery. Clinical indicators associated with the progression of carotid stenosis to occlusion were analyzed using ordered logistic regression. Twenty carotid plaques were analyzed immunohistochemically to investigate the relationship between plaque traits and the iron metabolism indexes. No significant correlation between high serum ferritin (SF), unsaturated iron binding capacity (UIBC) and progression of carotid stenosis (OR 1.100, 95% CI 0.004-0.165, p = 0.039; OR 1.050, 95% CI 0.005-0.094, p = 0.031). SF and serum transferrin receptor (sTfR) were correlated with normalized wall index (NWI) (R = 0.470, p = 0.036; R = 0.449, p = 0.046), and the results of multiple linear regression suggested that SF and sTfR remained associated with NWI (R = 0.630, R2 = 0.397, Adjusted R2 = 0.326, p = 0.014). In plaques, H-type ferritin (H-FT) was correlated with NWI and lipid-rich necrotic core (LRNC) volume (R = 0.502, p = 0.028; R = 0.468, p = 0.043). Transferrin receptor 1 (TfR1) was correlated with LRNC volume and intraplaque hemorrhage (IPH) volume (R = 0.538, p = 0.017; R = 0.707, p = 0.001). There were statistical differences in the expression of iron metabolism proteins in carotid plaques with different degrees of stenosis. Serum iron metabolism index (SF and sTfR) and expression of iron metabolizing proteins (H-FT and TfR1) in plaques were positively correlated with carotid plaque vulnerability index (NWI, LRNC volume).

Expression of Iron Metabolism Proteins in Patients with Chronic Heart Failure.

In heart failure, iron deficiency is a common comorbid disease that negatively influences exercise tolerance, number of hospitalizations and mortality rate, and this is why iron iv supplementation is recommended. Little is known about the changes in iron-related proteins in the human HF myocardium. The purpose of this study was to assess iron-related proteins in non-failing (NFH) vs. failing (FH) human myocardium. The study group consisted of 58 explanted FHs; control consisted of 31 NFHs unsuitable for transplantation. Myocardial proteins expressions: divalent metal transporter (DMT-1); L-type calcium channel (L-CH); transferrin receptors (TfR-1/TfR-2); ferritins: heavy (FT-H) or light (FT-L) chain, mitochondrial (FT-MT); ferroportin (FPN), regulatory factors and oxidative stress marker: 4-hydroxynonenal (4-HNE). In FH, the expression in almost all proteins responsible for iron transport: DMT-1, TfR-1, L-CH, except TfR-2, and storage: FT-H/-L/-MT were reduced, with no changes in FPN. Moreover, 4-HNE expression (pg/mg; NFH 10.6 ± 8.4 vs. FH 55.7 ± 33.7; p < 0.0001) in FH was increased. HNE-4 significantly correlated with DMT-1 (r = −0.377, p = 0.036), L-CH (r = −0.571, p = 0.001), FT-H (r = −0.379, p = 0.036), also FPN (r = 0.422, p = 0.018). Reducing iron-gathering proteins and elevated oxidative stress in failing hearts is very unfavorable for myocardiocytes. It should be taken into consideration before treatment with drugs or supplements that elevate free oxygen radicals in the heart.

MicroRNA profile and iron-related gene expression in hepatitis C-related hepatocellular carcinoma: a preliminary study.

IntroductionHepatocellular carcinoma (HCC) is very difficult to diagnose, especially in its early stages. Non-invasive diagnostic and prognostic factors for this cancer are urgently needed. The purpose of our study was to investigate whether the microRNAs (miRNAs) regulating genes involved in iron homeostasis, whose disruption is a hallmark of HCC, offer potential as diagnostic or prognostic factors of HCV-related hepatocellular carcinoma.Material and methodsSerum and tumor samples, and adjacent liver specimens, were obtained from 65 HCC patients. Additionally, serum samples were obtained from 65 healthy controls. In total, 28 circulating and eight tissue microRNA expression profiles were estimated by TaqMan qPCR.ResultsThe expression profiles of all tested miRNAs were altered in the hepatocellular carcinoma patients. Iron level was negatively related to serum miR-96 level in healthy controls. Although the expression of iron metabolism proteins correlated with the level of serum miRNA in the controls, this was not observed in cancer patients. In the group of cancer patients, Let-7a, miR-29b, and miR-133a were positively related to ferroportin, transferrin and ferritin levels, while miR-31, miR-221 and miR-532 were negatively related to ferroportin, transferrin receptor 1 and ferritin levels. According to ROC curve analyses, 15 miRNAs are able to discriminate with 100% sensitivity and specificity between hepatocellular carcinoma patients and healthy subjects, which is more efficient than α-fetoprotein.ConclusionsCirculating miRNAs that regulate the expression of iron metabolism proteins should be evaluated as promising candidates for HCV-related HCC diagnostic agents.

Cystathionine \u03b2-synthase (CBS) deficiency suppresses erythropoiesis by disrupting expression of heme biosynthetic enzymes and transporter

The reduced iron usage induced by the suppression of erythropoiesis is a major cause of the systemic iron overload in CBS knockout (CBS−/−) mice. However, the relevant mechanisms are unknown. Here, we examined changes in granulocyte/erythroid cell ratios, iron content, and expression of iron-metabolism proteins, including; two key enzymes involved in the heme biosynthetic pathway, ALAS2 (delta-aminolevulinate synthase 2) and FECH (ferrochelatase), a heme exporter from the cytosol and mitochondria, FLVCR (feline leukemia virus subgroup C cellular receptor) as well as EPO (erythropoietin), EPOR (erythropoietin receptor) and HIF-2α (hypoxia inducible factor-2 subunit α), in the blood, bone marrow or liver of CBS−/− (homozygous), CBS+/− (heterozygous) and CBS+/+ (Wild Type) mice. Our findings demonstrate that CBS deficiency can induce a significant reduction in the expression of ALAS2, FECH, FLVCR, HIF-2α, EPO, and EPOR as well as an increase in interleukin-6 (IL-6), hepcidin and iron content in the blood, bone marrow or liver of mice. We conclude that the suppression of erythropoiesis is mainly due to the CBS deficiency-induced disruption in the expression of heme biosynthetic enzymes and heme-transporter.

Glia maturation factor-γ regulates murine macrophage iron metabolism and M2 polarization through mitochondrial ROS

AbstractIn macrophages, cellular iron metabolism status is tightly integrated with macrophage phenotype and associated with mitochondrial function. However, how molecular events regulate mitochondrial activity to integrate regulation of iron metabolism and macrophage phenotype remains unclear. Here, we explored the important role of the actin-regulatory protein glia maturation factor-γ (GMFG) in the regulation of cellular iron metabolism and macrophage phenotype. We found that GMFG was downregulated in murine macrophages by exposure to iron and hydrogen peroxide. GMFG knockdown altered the expression of iron metabolism proteins and increased iron levels in murine macrophages and concomitantly promoted their polarization toward an anti-inflammatory M2 phenotype. GMFG-knockdown macrophages exhibited moderately increased levels of mitochondrial reactive oxygen species (mtROS), which were accompanied by decreased expression of some mitochondrial respiration chain components, including the iron-sulfur cluster assembly scaffold protein ISCU as well as the antioxidant enzymes SOD1 and SOD2. Importantly, treatment of GMFG-knockdown macrophages with the antioxidant N-acetylcysteine reversed the altered expression of iron metabolism proteins and significantly inhibited the enhanced gene expression of M2 macrophage markers, suggesting that mtROS is mechanistically linked to cellular iron metabolism and macrophage phenotype. Finally, GMFG interacted with the mitochondrial membrane ATPase ATAD3A, suggesting that GMFG knockdown–induced mtROS production might be attributed to alteration of mitochondrial function in macrophages. Our findings suggest that GMFG is an important regulator in cellular iron metabolism and macrophage phenotype and could be a novel therapeutic target for modulating macrophage function in immune and metabolic disorders.

Expression of Iron Transporters and Pathological Hallmarks of Parkinson's and Alzheimer's Diseases in the Brain of Young, Adult, and Aged Rats.

Iron accumulates progressively in the brain with age; however, the cause is unknown. We hypothesized that iron accumulation may be associated with the age-induced changes in the expression of iron metabolism proteins in the brain. Here, we systematically investigated iron content and the expression of two major iron importers, transferrin receptor 1 (TfR1) and divalent metal transporter (DMT1), two iron exporters, ferroportin 1 (Fpn1) and ceruloplasmin (CP), and hepcidin, along with the pathological hallmarks of Parkinson's (PD) and Alzheimer's diseases (AD) in the brain of young (3months), adult (12months), and aged (24months) rats. We demonstrated that age has a region-specific effect on iron transport proteins along with iron content in the cortex, striatum, hippocampus, and substantia nigra. We also found an age-dependent increase in hyperphosphorylated tau, total beta-amyloid, and neurotoxic oligomeric aggregates in the cortex and hippocampus as well as an increase in α-synuclein and a decrease in tyrosine hydroxylase positive neurons in the substantia nigra. Our findings suggest that the age-dependent increase in brain iron may be partly due to the age-induced increase in DMT1 expression, rather than TfR1 and Fpn1 expression, and also imply that the increased brain iron is associated with expression of the pathological hallmarks of AD and PD.

A high fat diet does not affect the iron bioavailability in Wistar rats fed with chia and increases gene expression of iron metabolism proteins.

This study evaluated the effect of chia on the iron bioavailability and gene expression of proteins involved in iron metabolism in animals fed with a high fat diet and a standard diet. Four experimental groups were tested (n = 8): standard diet + ferrous sulfate (SD + FS), standard diet + chia (SD + C), high fat diet + ferrous sulfate (HFD + FS), high fat diet + chia (HFD + C). The hemoglobin gain, hemoglobin regeneration efficiency, biological relative value of HRE, serum ferritin and transferrin, liver iron concentration and gene expression of proteins were evaluated. The SD + C group showed lower transferrin expression when compared to the control group. The control group showed serum transferrin concentration higher than the other groups. Serum ferritin and liver iron concentration did not differ among the animals that received chia ferritin and hephaestin expression was lower in experimental groups when compared with the control group. The peroxisome proliferator activated receptor expression was higher in animals fed with SD + C than in the control group. The expression of duodenal cytochrome B and divalent metal transporter 1 in the HFD + C group was higher and ferroportin was lower in the groups containing chia. Animals fed with chia showed similar iron bioavailability compared to animals fed with ferrous sulfate.

Hfe and Hjv exhibit overlapping functions for iron signaling to hepcidin.

Functional inactivation of HFE or hemojuvelin (HJV) is causatively linked to adult or juvenile hereditary hemochromatosis, respectively. Systemic iron overload results from inadequate expression of hepcidin, the iron regulatory hormone. While HJV regulates hepcidin by amplifying bone morphogenetic protein (BMP) signaling, the role of HFE in the hepcidin pathway remains incompletely understood. We investigated the pathophysiological implications of combined Hfe and Hjv ablation in mice. Isogenic Hfe (-)/(-) and Hjv (-)/(-) mice were crossed to generate double Hfe (-)/(-) Hjv (-)/(-) progeny. Wild-type control and mutant mice of all genotypes were analyzed for serum, hepatic, and splenic iron content, expression of iron metabolism proteins, and expression of hepcidin and Smad signaling in the liver, in response to a standard or an iron-enriched diet. As expected, Hfe (-)/(-) and Hjv (-)/(-) mice developed relatively mild or severe iron overload, respectively, which corresponded to the degree of hepcidin inhibition. The double Hfe (-)/(-) Hjv (-)/(-) mice exhibited an indistinguishable phenotype to single Hjv (-)/(-) counterparts with regard to suppression of hepcidin, serum and hepatic iron overload, splenic iron deficiency, tissue iron metabolism, and Smad signaling, under both dietary regimens. We conclude that the hemochromatotic phenotype caused by disruption of Hjv is not further aggravated by combined Hfe/Hjv deficiency. Our results provide genetic evidence that Hfe and Hjv operate in the same pathway for the regulation of hepcidin expression and iron metabolism. Combined disruption of Hfe and Hjv phenocopies single Hjv deficiency. Single Hjv(-)/(-) and double Hfe(-)/(-)Hjv(-)/(-) mice exhibit comparable iron overload. Hfe and Hjv regulate hepcidin via the same pathway.

Effects of hypoxic preconditioning on the expression of iron influx and efflux proteins in primary neuron culture

The mechanisms of neuroprotection induced by hypoxic preconditioning (HP) and the effects of HP on iron metabolism proteins in the brain have not been fully elucidated. Based on the accumulated information, we hypothesized that HP would be able to affect the expression of iron metabolism proteins in the brain and that the changes in the expression of these proteins induced by HP might be partly associated with the HP-induced neuroprotection. Here, we demonstrated for the first time that HP could induce a significant increase in the expression of HIF-1alpha as well as iron uptake (TfR1 and DMT1) and release (Fpn1) proteins and thus increase transferrin-bound iron (Tf-Fe) and non-transferrin-bound iron (NTBI) uptake and iron release, and also a progressive increase in cellular iron content in the cultured neurons. We concluded that HP has the ability to speed iron transport rate and proposed that the increase in iron transport rate and cellular iron in neurons might be one of the mechanisms involved in neuroprotection in the HP neurons. We also demonstrated that Fpn1 expression was significantly affected by HIF-1alpha, implying that the gene encoding this iron efflux protein is hypoxia-inducible.

Hypoxic preconditioning increases iron transport rate in astrocytes

The mechanisms involved in the neuroprotection induced by hypoxic preconditioning (HP) have not been fully elucidated. The involvement of hypoxia-inducible factor-1 alpha (HIF-1alpha) in such neuroprotection has been confirmed. There is also evidence showing that a series of genes with important functions in iron metabolism, including transferrin receptor (TfR1) and divalent metal transporter 1 (DMT1), are regulated by HIF-1alpha in response to hypoxia in extra-neural organs or cells. We therefore hypothesized that HP is able to affect the expression of iron metabolism proteins in the brain and that changes in these proteins induced by HP might be associated with the HP-induced neuroprotection. We herein demonstrated for the first time that HP could induce a significant increase in the expression of HIF-1alpha as well as iron uptake (TfR1 and DMT1) and release (ferroportin1) proteins, and thus increase tansferrin-bound iron (Tf-Fe) and non-transferrin-bound iron (NTBI) uptake and iron release in astrocytes. Moreover, HP could lead to a progressive increase in cellular iron content. We concluded that HP has the ability to increase iron transport speed in astrocytes. Based on our findings and the importance of astrocytes in neuronal survival in hypoxic/ischemic preconditioning, we proposed that the increase in iron transport rate and cellular iron in astocytes might be one of the mechanisms associated with the HP-induced neuroprotection. We also demonstrated that ferroportin1 expression was significantly affected by HIF-1alpha in astrocytes, implying that the gene encoding this iron efflux protein might be a hypoxia-inducible one.

Differential expression of iron metabolism proteins in diabetic and diabetic iron‐supplemented rat liver

Diabetes mellitus is associated with altered iron homeostasis that can potentially effect reactive oxygen species generation and contribute to diabetes-related complications. We investigated, by quantitative polymerase chain reaction, whether the expression of liver hepcidin, ferritin, and TfR-1 is altered in diabetes. Rats in the control (C) group received a standard diet; control iron (CI) group received a standard diet supplemented with iron; diabetic (D) group received an injection of streptozotocin; and diabetic iron (DI) group received streptozotocin and the diet with iron. Animals of the D group showed higher levels of serum iron, increased concentration of carbonyl protein, and a decrease in antioxidant status. Group D rats showed increased hepatic expression of Trf-1 compared to the other groups. Iron supplementation reversed this increase. Hepcidin mRNA was 81% higher in DI than in C and CI rats. The results suggest that diabetes, with or without excess iron, can cause perturbations in iron status, hepcidin and Trf-1 expression.

Light-Induced Retinal Degeneration Correlates with Changes in Iron Metabolism Gene Expression, Ferritin Level, and Aging

Retinal degeneration is associated with iron accumulation in several rodent models in which iron-regulating proteins are impaired. Oxidative stress is catalyzed by unbound iron. The role of the heavy chain of ferritin, which sequesters iron, in regulating the thickness of the photoreceptor nuclear layer in the 4- and 16-month-old wild-type H ferritin (HFt(+/+)) and heterozygous H ferritin (HFt(+/-)) mice was investigated, before and 12 days after exposure to 13,000-lux light for 24 hours. The regulation of gene expression of the various proteins involved in iron homeostasis, such as transferrin, transferrin receptor, hephaestin, ferroportin, iron regulatory proteins 1 and 2, hepcidin, ceruloplasmin, and heme-oxygenase 1, was analyzed by quantitative (q)RT-PCR during exposure (2, 12, and 24 hours) and 24 hours after 1 day of exposure in the 4-month-old HFt(+/+) and HFt(+/-) mouse retinas. Retinal degeneration in the 4-month-old HFt(+/-) mice was more extensive than in the HFt(+/+) mice. Yet, it was more extensive in both of the 16-month-old mouse groups, revealing the combined effect of age and excessive light. Injury caused by excessive light modified the temporal gene expression of iron-regulating proteins similarly in the HFt(+/-) and HFt(+/+) mice. Loss of one allele of H ferritin appears to increase light-induced degeneration. This study highlighted that oxidative stress related to light-induced injury is associated with major changes in gene expression of iron metabolism proteins.

Mapping of Char10, a novel malaria susceptibility locus on mouse chromosome 9

Resistance to blood-stage malaria in AcB55 and AcB61 is caused by a loss of function mutation in pyruvate kinase (Pklr(I90N)). Likewise, pyruvate kinase (PK) deficiency in humans is protective against Plasmodium replication in vitro. We identified a third AcB strain, AcB62 that also carries the Pklr(I90N) mutation. However, AcB62 mice were susceptible to P.chabaudi infection and showed high levels of parasite replication (54-62% peak parasitemia). AcB62 mice showed the hallmarks of PK deficiency-associated anemia similar to AcB55/61 with reticulocytosis, splenic red pulp expansion, tissue iron overload, and increased expression of iron metabolism proteins. This suggests that malaria susceptibility in AcB62 is not because of absence of PK deficiency-associated pathophysiology. To map novel genetic factors affecting malaria susceptibility in AcB62, we generated an informative F2 population using AcB62 (Pklr(I90N)) and CBA-Pk(slc) (Pklr(G338D)) as progenitors and identified a novel locus on chromosome 9 (Char10; LOD=7.24) that controls peak parasitemia. A weaker linkage to the Pklr region of chromosome 3 (LOD=3.7) was also detected, a finding that may reflect the segregation of the two defective Pklr alleles. AcB62 alleles at both loci are associated with higher peak parasitemia. These results identify Char10 as a novel locus modulating severity of malaria in the context of PK deficiency.

The role of endogenous heme synthesis and degradation domain cysteines in cellular iron-dependent degradation of IRP2

Iron regulatory protein 2 (IRP2) is a mammalian cytosolic iron-sensing protein that regulates expression of iron metabolism proteins, including ferritin and transferrin receptor 1. IRP2 is ubiquitinated and degraded by the proteasome in iron-replete cells but is relatively stable in iron-depleted cells. Recent work has shown that IRP2 contains a unique 73-amino-acid domain that binds iron in vitro and undergoes iron-dependent oxidation and cleavage (J. Biol. Chem. 278 (2003), 14857). Several cysteines in the 73-amino-acid domain function as an in vitro iron-binding site. To assess the role of these cysteines in cellular iron- dependent degradation of IRP2, we mutagenized these cysteines in various combinations in the context of full-length protein and generated cell lines in which recombinant IRP2 expression was inducible. Iron-dependent degradation of IRP2 mutagenized at any or all of the cysteines of the putative degradation domain in cells was comparable to wild-type (WT). Both WT and cysteine mutant protein were stabilized in 3% oxygen. Treatment with sodium nitroprusside (SNP), an NO+ donor, caused a decrease in cellular IRP2 concentrations, but the SNP effect was abrogated by simultaneous addition of the iron chelator desferal and was not affected by cysteine mutations. Inhibition of endogenous heme synthesis with succinylacetone significantly inhibited iron- dependent degradation of IRP2. Addition of cobalt chloride inhibited degradation of both WT and mutagenized IRP2. Thus, we could not discern a role for the recently defined in vitro cysteine-dependent iron-binding site of IRP2 in cellular physiology. The early molecular events in iron-dependent degradation of IRP2 remain to be elucidated.