Mechanisms Of Iron Regulation Research Articles

The Impact of the Combined Effect of Inhalation Anesthetics and Iron Dextran on Rats' Systemic Toxicity.

Disruption of any stage of iron homeostasis, including uptake, utilization, efflux, and storage, can cause progressive damage to peripheral organs. The health hazards associated with occupational exposure to inhalation anesthetics (IA) in combination with chronic iron overload are not well documented. This study aimed to investigate changes in the concentration of essential metals in the peripheral organs of rats after iron overload in combination with IA. The aim was also to determine how iron overload in combination with IA affects tissue metal homeostasis, hepcidin-ferritin levels, and MMP levels according to physiological, functional, and tissue features. According to the obtained results, iron accumulation was most pronounced in the liver (19×), spleen (6.7×), lungs (3.1×), and kidneys (2.5×) compared to control. Iron accumulation is associated with elevated heavy metal levels and impaired essential metal concentrations due to oxidative stress (OS). Notably, the use of IA increases the iron overload toxicity, especially after Isoflurane exposure. The results show that the regulation of iron homeostasis is based on the interaction of hepcidin, ferritin, and other proteins regulated by inflammation, OS, free iron levels, erythropoiesis, and hypoxia. Long-term exposure to IA and iron leads to the development of numerous adaptation mechanisms in response to toxicity, OS, and inflammation. These adaptive mechanisms of iron regulation lead to the inhibition of MMP activity and reduction of oxidative stress, protecting the organism from possible damage.

A Carbamoyl Oxime-Based Highly Specific Fluorescent Chemodosimeter for Monitoring Labile Fe2+ in Food and Living Organisms.

Iron is an essential element in the composition of living organisms and plays a crucial role in a wide range of biological activities. The human body primarily obtains essential iron through the consumption of food. Therefore, it is vital for the health of human body to maintain iron homeostasis. The reducing character of the cellular microenvironment enables Fe2+ to occupy a dominant position within the cell. Hence, there is an urgent need for a simple and sensitive tool that can detect a large amount of Fe2+ in organisms. In this work, a highly specific fluorescent chemodosimeter NPCO ("NP" represents the naphthalimide fluorophore, and "CO" represents the carbamoyl oxime structure) for the detection of Fe2+ with excellent sensitivity (LOD = 82 nM) was constructed by incorporating a novel carbamoyl oxime structure as the recognition group. NPCO can be effectively employed for the detection of Fe2+ in food samples, living cells, and zebrafish. Furthermore, by using soybean sprouts as a model plant, the application of NPCO was expanded to detect Fe2+ in plants. Therefore, NPCO could be used as an excellent assay tool for detecting Fe2+ in organisms and is expected to be an important aid in exploring the mechanism of iron regulation.

Convergent imaging-transcriptomic evidence for disturbed iron homeostasis in Gilles de la Tourette syndrome

Gilles de la Tourette syndrome (GTS) is a neuropsychiatric movement disorder with reported abnormalities in various neurotransmitter systems. Considering the integral role of iron in neurotransmitter synthesis and transport, it is hypothesized that iron exhibits a role in GTS pathophysiology. As a surrogate measure of brain iron, quantitative susceptibility mapping (QSM) was performed in 28 patients with GTS and 26 matched controls. Significant susceptibility reductions in the patients, consistent with reduced local iron content, were obtained in subcortical regions known to be implicated in GTS. Regression analysis revealed a significant negative association of tic scores and striatal susceptibility. To interrogate genetic mechanisms that may drive these reductions, spatially specific relationships between susceptibility and gene-expression patterns from the Allen Human Brain Atlas were assessed. Correlations in the striatum were enriched for excitatory, inhibitory, and modulatory neurochemical signaling mechanisms in the motor regions, mitochondrial processes driving ATP production and iron‑sulfur cluster biogenesis in the executive subdivision, and phosphorylation-related mechanisms affecting receptor expression and long-term potentiation in the limbic subdivision. This link between susceptibility reductions and normative transcriptional profiles suggests that disruptions in iron regulatory mechanisms are involved in GTS pathophysiology and may lead to pervasive abnormalities in mechanisms regulated by iron-containing enzymes.

The Interplay between Intracellular Iron Homeostasis and Neuroinflammation in Neurodegenerative Diseases.

Iron is essential for life. Many enzymes require iron for appropriate function. However, dysregulation of intracellular iron homeostasis produces excessive reactive oxygen species (ROS) via the Fenton reaction and causes devastating effects on cells, leading to ferroptosis, an iron-dependent cell death. In order to protect against harmful effects, the intracellular system regulates cellular iron levels through iron regulatory mechanisms, including hepcidin-ferroportin, divalent metal transporter 1 (DMT1)-transferrin, and ferritin-nuclear receptor coactivator 4 (NCOA4). During iron deficiency, DMT1-transferrin and ferritin-NCOA4 systems increase intracellular iron levels via endosomes and ferritinophagy, respectively. In contrast, repleting extracellular iron promotes cellular iron absorption through the hepcidin-ferroportin axis. These processes are regulated by the iron-regulatory protein (IRP)/iron-responsive element (IRE) system and nuclear factor erythroid 2-related factor 2 (Nrf2). Meanwhile, excessive ROS also promotes neuroinflammation by activating the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). NF-κB forms inflammasomes, inhibits silent information regulator 2-related enzyme 1 (SIRT1), and induces pro-inflammatory cytokines (IL-6, TNF-α, and IL-1β). Furthermore, 4-hydroxy-2,3-trans-nonenal (4-HNE), the end-product of ferroptosis, promotes the inflammatory response by producing amyloid-beta (Aβ) fibrils and neurofibrillary tangles in Alzheimer's disease, and alpha-synuclein aggregation in Parkinson's disease. This interplay shows that intracellular iron homeostasis is vital to maintain inflammatory homeostasis. Here, we review the role of iron homeostasis in inflammation based on recent findings.

Stem-Loop Structures in Iron-Regulated mRNAs of Giardia duodenalis.

Giardia duodenalis is a significant cause of waterborne and foodborne infections, day-care center outbreaks, and traveler's diarrhea worldwide. In protozoa such as Trichomonas vaginalis and Entamoeba histolytica, iron affects the growth, pathogenicity mechanisms, and expression of virulence genes. One of the proposed iron regulatory mechanisms is at the post-transcriptional level through an IRE/IRP-like (iron responsive element/iron regulatory protein) system. Recently, the expression of many putative giardial virulence factors in the free-iron levels has been reported in subsequent RNAseq experiments; however, the iron regulatory mechanism remains unknown. Thus, this work aimed to determine the effects of iron on the growth, gene expression, and presence of IRE-like structures in G. duodenalis. First, the parasite's growth kinetics at different iron concentrations were studied, and the cell viability was determined. It was observed that the parasite can adapt to an iron range from 7.7 to 500 µM; however, in conditions without iron, it is unable to survive in the culture medium. Additionally, the iron modulation of three genes was determined by RT-PCR assays. The results suggested that Actin, glucosamine-6-phosphate deaminase, and cytochrome b5 mRNA were down-regulated by iron. To investigate the presence of IRE-like structures, in silico analyses were performed for different mRNAs from the Giardia genome database. The Zuker mfold v2.4 web server and theoretical analysis were used to predict the secondary structures of the 91 mRNAs analyzed. Interestingly, the iron-induced downregulation of the genes analyzed corresponds to the location of the stem-loop structures found in their UTR regions. In conclusion, iron modulates the growth and expression of specific genes, likely due to the presence of IRE-like structures in G. duodenalis mRNAs.

Association of Transferrin Gene Polymorphism with Cognitive Deficits and Psychiatric Symptoms in Patients with Chronic Schizophrenia.

A large amount of recent literature has focused on impaired iron homeostasis in the pathophysiology of schizophrenia. Specifically, microarray analysis has illustrated associations between the transferrin locus and schizophrenia. To elaborate on the effects of transferrin on schizophrenia and its psychiatric phenotypes, our study aimed to investigate whether transferrin gene polymorphism was correlated with cognitive deficits and clinical symptoms in schizophrenia. We recruited 564 patients with chronic schizophrenia and 422 healthy controls (HCs) in a Han Chinese population, collected phenotypic data, and genotyped the rs3811655 polymorphism of the transferrin gene. Our results showed that the rs3811655 polymorphism was related to cognitive performance in both patients and HCs, as well as negative symptoms in patients (all p < 0.05), and patients carrying at least one G-allele showed worsened cognition/severe negative symptoms (all p < 0.05). Further analyses also found that the rs3811655 polymorphism in combination with cognition may exert small but significant contributions to the negative (β = -0.10, t = -2.48, p < 0.05) or total psychiatric symptoms (β = -0.08, t = -1.92, p < 0.05) in patients. Our findings indicated that the rs3811655 polymorphism may be implicated in the cognitive deficits of schizophrenia and HCs as well as psychiatric symptoms in patients, which suggested the possible iron regulatory mechanism in the pathology of schizophrenia.

Influence of prazosin on systemic iron levels and the associated iron metabolic alterations in spontaneously hypertensive rats

The relationship between cardiovascular diseases and iron disorders has gained increasing attention; however, the effects of hypotensive drugs on iron metabolic alterations in hypertension are not well understood. The purpose of this study was to investigate iron metabolic changes after prazosin treatment of spontaneously hypertensive rats (SHRs) and Wistar–Kyoto (WKY) rats. Our second objective was to examine the effects of hypertension and anti‐hypertensive drugs on bone formation and resorption. SHRs and WKY rats were randomized into either prazosin‐treated groups (WKY + PZ and SHR + PZ) or untreated groups (WKY and SHR). After 7 days of intragastric prazosin administration, the rats were sacrificed for analysis; blood samples and organs (the duodenum, liver, kidneys, spleen, and femur) were collected. Both WKY + PZ and SHR groups exhibited iron deficiency in the serum and liver. Prazosin increased the iron levels in the bone tissue of SHRs. Prazosin stimulated the expression of hepcidin mRNA in the liver of SHRs and inhibited the expression of this iron‐regulatory hormone in WKY rats. FPN1 expression in the duodenum was increased significantly in SHRs, however markedly decreased after prazosin treatment. The expression of TLR4 and Ctsk was enhanced in the bone tissue of SHRs, whereas CLC‐7 expression was inhibited. Both hypotension and hypertension can lead to iron deficiency. Treatment with prazosin restored iron homeostasis in SHRs. The inverse impacts of prazosin on hepatic hepcidin expression in SHRs versus WKY rats indicates differing iron regulatory mechanisms between hypertensive and normal animals. The osteoclast activity was found to be enhanced in SHRs. Further study is needed to address whether the changes in osteoblast and osteoclast activity in SHRs correlates with the effects on iron metabolism.

Investigating the Molecular Mechanisms of Renal Hepcidin Induction and Protection upon Hemoglobin-Induced Acute Kidney Injury.

Hemolysis is known to cause acute kidney injury (AKI). The iron regulatory hormone hepcidin, produced by renal distal tubules, is suggested to exert a renoprotective role during this pathology. We aimed to elucidate the molecular mechanisms of renal hepcidin synthesis and its protection against hemoglobin-induced AKI. In contrast to known hepatic hepcidin induction, incubation of mouse cortical collecting duct (mCCDcl1) cells with IL-6 or LPS did not induce Hamp1 mRNA expression, whereas iron (FeS) and hemin significantly induced hepcidin synthesis (p < 0.05). Moreover, iron/heme-mediated hepcidin induction in mCCDcl1 cells was caused by the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway, as indicated by increased nuclear Nrf2 translocation and induced expression of Nrf2 downstream targets GCLM (p < 0.001), NQO1 (p < 0.001), and TXNRD1 (p < 0.005), which could be prevented by the known Nrf2 inhibitor trigonelline. Newly created inducible kidney-specific hepcidin KO mice demonstrated a significant reduction in renal Hamp1 mRNA expression. Phenylhydrazine (PHZ)-induced hemolysis caused renal iron loading and oxidative stress in both wildtype (Wt) and KO mice. PHZ treatment in Wt induced inflammatory markers (IL-6, TNFα) but not Hamp1. However, since PHZ treatment also significantly reduced systemic hepcidin levels in both Wt and KO mice (both p < 0.001), a dissection between the roles of systemic and renal hepcidin could not be made. Combined, the results of our study indicate that there are kidney-specific mechanisms in hepcidin regulation, as indicated by the dominant role of iron and not inflammation as an inducer of renal hepcidin, but also emphasize the complex interplay of various iron regulatory mechanisms during AKI on a local and systemic level.

NRF2 and Hypoxia-Inducible Factors: Key Players in the Redox Control of Systemic Iron Homeostasis.

Significance: Oxygen metabolism and iron homeostasis are closely linked. Iron facilitates the oxygen-carrying capacity of blood, and its deficiency causes anemia. Conversely, excess free iron is detrimental for stimulating the formation of reactive oxygen species, causing tissue damage. The amount and distribution of iron thus need to be tightly regulated by the liver-expressed hormone hepcidin. This review analyzes the roles of key oxygen-sensing pathways in cellular and systemic regulation of iron homeostasis; specifically, the prolyl hydroxylase domain (PHD)/hypoxia-inducible factor (HIF) and the Kelch-like ECH-associated protein 1/NF-E2 p45-related factor 2 (KEAP1/NRF2) pathways, which mediate tissue adaptation to low and high oxygen, respectively. Recent Advances: In macrophages, NRF2 regulates genes involved in hemoglobin catabolism, iron storage, and iron export. NRF2 was recently identified as the molecular sensor of iron-induced oxidative stress and is responsible for BMP6 expression by liver sinusoidal endothelial cells, which in turn activates hepcidin synthesis by hepatocytes to restore systemic iron levels. Moreover, NRF2 orchestrates the activation of antioxidant defenses that are crucial to protect against iron toxicity. On the contrary, low iron/hypoxia stabilizes renal HIF2a via inactivation of iron-dependent PHD dioxygenases, causing an erythropoietic stimulus that represses hepcidin via an inhibitory effect of erythroferrone on bone morphogenetic proteins. Intestinal HIF2a is also stabilized, increasing the expression of genes involved in dietary iron absorption. Critical Issues: An intimate crosstalk between oxygen-sensing pathways and iron regulatory mechanisms ensures that fluctuations in systemic iron levels are promptly detected and restored. Future Directions: The realization that redox-sensitive transcription factors regulate systemic iron levels suggests novel therapeutic approaches. Antioxid. Redox Signal. 35, 433-452.

CBIO-10. REDUCED IRON EXPORT FUNCTIONS IN A CELL INTRINSIC MANNER TO DRIVE GLIOBLASTOMA GROWTH

Abstract Glioblastoma (GBM), the most common primary malignant brain tumor in adults, is characterized by invasive growth and poor prognosis. Iron is a critical regulator of many cellular processes, and GBM tumor cells have been shown to modulate expression of iron-associated proteins to enhance iron uptake from the surrounding microenvironment, driving tumor initiation and growth. While iron uptake has been the central focus of previous investigations, additional mechanisms of iron regulation, such as compensatory iron efflux, have not been explored in the context of GBM. The hemochromatosis (HFE) gene encodes a transmembrane glycoprotein that aids in iron homeostasis by limiting cellular iron release, resulting in a sequestration phenotype. We find that HFE is upregulated in GBM tumors compared to non-tumor brain and that expression of HFE increases with tumor grade. Furthermore, HFE mRNA expression is associated with significantly reduced survival specifically in female patients with GBM. Based on these findings, we hypothesize that GBM tumor cells upregulate HFE expression to augment cellular iron loading and drive proliferation, ultimately leading to reduced survival of female patients. To test this hypothesis, we generated Hfe knockdown and overexpressing mouse glioma cell lines. We observed significant alterations in the expression of several iron handling genes with Hfe knockdown or overexpression, suggesting global disruption of iron homeostasis. Additionally, we show that knockdown of Hfe in these cells increases apoptosis and leads to a significant impairment of tumor growth in vivo. These findings support the hypothesis that Hfe is a critical regulator of cellular iron status and contributes to tumor aggression. Future work will include further exploration of the mechanisms that contribute to these phenotypes as well as interactions with the tumor microenvironment. Elucidating the mechanisms by which iron effulx contributes to GBM may inform the development of next-generation targeted therapies.

A Family Affected by a Life-Threatening Erythrocyte Defect Caused by Pyruvate Kinase Deficiency With Normal Iron Status: A Case Report.

BackgroundRed cell pyruvate kinase deficiency (PKD) is a defect of glycolysis causing congenital non-spherocytic hemolytic anemia. PKD is transmitted as an autosomal recessive trait. The clinical features of PKD are highly variable, from mild to life-threatening anemia which can lead to death in the neonatal period. Most patients with PKD must receive regular transfusions in early childhood and as a consequence suffer from iron overloading.PatientHere, we report a Polish family with life-threatening hemolytic anemia of unknown etiology. Whole exome sequencing identified two heterozygous mutations, c.1529 G > A (p.R510Q) and c.1495 T > C (p.S499P) in the PKLR gene. Molecular modeling showed that the both PKLR mutations are responsible for major disturbance of the protein structure and functioning. Despite frequent transfusions the patients do not show any signs of iron overload and hepcidin, a major regulator of iron uptake, is undetectable in their serum. The patients were homozygous for the rs855791 variant of the TMPRSS6 gene which has earlier been shown to down-regulate iron absorption and accumulation.ConclusionThe lack of iron overload despite a reduced level of hepcidin in two transfusion-dependent PKD patients suggests the existence of a hepcidin-independent mechanism of iron regulation preventing iron overloading.

Iron-Response Element Binding to Iron Regulatory Protein (IRP) 1 and 2 Are Indispensable for Adipose Tissue Browning

Abstract Objectives Intracellular iron homeostasis is tightly regulated in posttranscriptional levels via iron regulatory proteins (IRPs). IRPs bind to the iron-responsive elements (IREs), leading to either mRNA translation or stability. Our recent study demonstrated that iron metabolism is intimately linked with adipose tissue browning and thermogenic activation. However, the role of IRP/IRE interactions in the adipose tissue is poorly understood. We aim to characterize the IRP/IRE interactions in the adipose tissue in terms of depot-specificity and thermogenic potential. Methods To induce adipocyte browning, mice were administrated with beta-3 adrenoceptor agonist CL316243 (CL) for 5 days, and different depots of adipose tissue of epididymal (eWAT), inguinal (iWAT), brown (BAT), and liver were collected. Iron metabolism and thermogenesis were evaluated. To investigate the IRP/IRE binding, electrophoretic mobility shift assay (EMSA) was performed in the cytosolic using the fluorescence-labeled IRE (IR-IRE). To distinguish the IRE binding with IRP1 and 2, the cytosolic fraction from IRP1 and 2 knockout mice were used as positive controls. Results In a normal temperature, the constitutive IRP/IRE binding was found in the BAT, but not in the eWAT and iWAT. In response to CL treatment, iron content and transferrin receptor levels significantly increased in the WAT. Accordingly, the IRE/IRPs binding significantly increased in the CL-treated iWAT. Genetic deletion of IRP1 or 2 poses a marginal impact on constitutively active BAT development, suggesting IRP1 and 2 plays a compensatory role. Unlikely to BAT, the deletion of either IRP1 or 2 failed to induce WAT browning in the IRP1 and 2 knockout mice with CL stimulation. Consistently, both IRE binding to IRP1 and 2 were manifest in the CL treated iWAT, implicating that IRP1 and 2 plays a separate and synergistic function for WAT browning. Conclusions Our study defined the depot-specific iron regulatory metabolism in the adipose tissue using an innovative EMSA method. We demonstrated that, for the first time in our knowledge, IRE binding to both IRP1 and IRP2 is indispensable for the thermogenic activation of WAT, which is distinct from the iron regulatory mechanism found in the BAT. We propose that iron metabolism in the WAT is a novel determinant for WAT browning and thermogenic energy expenditure. Funding Sources None.

Iron metabolic pathways in the processes of sponge plasticity.

The ability to regulate oxygen consumption evolved in ancestral animals and is intrinsically linked to iron metabolism. The iron pathways have been intensively studied in mammals, whereas data on distant invertebrates are limited. Sea sponges represent the oldest animal phylum and have unique structural plasticity and capacity to reaggregate after complete dissociation. We studied iron metabolic factors and their expression during reaggregation in the White Sea cold-water sponges Halichondria panicea and Halisarca dujardini. De novo transcriptomes were assembled using RNA-Seq data, and evolutionary trends were analyzed with bioinformatic tools. Differential expression during reaggregation was studied for H. dujardini. Enzymes of the heme biosynthesis pathway and transport globins, neuroglobin (NGB) and androglobin (ADGB), were identified in sponges. The globins mutate at higher evolutionary rates than the heme synthesis enzymes. Highly conserved iron-regulatory protein 1 (IRP1) presumably interacts with the iron-responsive elements (IREs) found in mRNAs of ferritin (FTH1) and a putative transferrin receptor NAALAD2. The reaggregation process is accompanied by increased expression of IRP1, the antiapoptotic factor BCL2, the inflammation factor NFκB (p65), FTH1 and NGB, as well as by an increase in mitochondrial density. Our data indicate a complex mechanism of iron regulation in sponge structural plasticity and help to better understand general mechanisms of morphogenetic processes in multicellular species.

Local hepcidin increased intracellular iron overload via the degradation of ferroportin in the kidney

BackgroundHepcidin is a key regulator of iron homeostasis. Some studies showed that exogenous hepcidin decreased the expression of divalent metal transporter (DMT1) rather than ferroportin(FPN1) to regulate renal iron metabolism. This study explored the effects of hepcidin synthesized by the kidney and its mechanism of iron regulation. MethodsIn the in vivo experiments, mice were divided into a unilateral ureter obstruction (UUO) model group and a sham operation group, and mice in the UUO model group were sacrificed on days 1, 3, 5 and 7. The expression of renal hepcidin, FPN1, DMT1 and the retention of renal iron were studied. In the in vitro experiments, we overexpressed hepcidin in HK-2 cells. Then we tested the expression of renal hepcidin, FPN1, DMT1 and observed the production of intracellular ferrous ions. ResultsRenal hepcidin expression was consistently higher in the UUO group than in the sham group from the first day. The expression of FPN1 gradually decreased, and the expression of DMT1 gradually increased in the UUO model. Intracellular ferrous ions significantly increased on the first day of the UUO model. In hepcidin overexpressed HK-2 cells, the expression of FPN1 was decreased, while the expression of DMT1 has no significant change. In addition, production of intracellular ferrous ions increased.Conclusion: local hepcidin can regulate iron metabolism in the kidney by adjusting the expression of FPN1.

OmpW is positively regulated by iron via Fur, and negatively regulated by SoxS contribution to oxidative stress resistance in Escherichia coli

Iron plays a central role at the interface of pathogen and host. The ability to sequester iron from a host not only reduces host immune defenses but also promotes pathogen virulence, leading to the occurrence of infectious disease. Recently, outer membrane protein OmpW was shown to protect bacteria against harsh environmental conditions and to play a role in infectious disease. The expression of this versatile protein is controlled by iron, but the underlying mechanism of iron regulation has not been elucidated. In this study, the relation between OmpW expression and iron was investigated. Our results demonstrated that expression of OmpW is responsive to iron. Iron uptake analysis showed that an ompW mutant strain has a strong requirement for iron as compared to wild type and the ompW complemented strain. Moreover, ferric uptake regulation protein Fur, an iron binding transcriptional factor, was downregulated under iron limitation conditions and had a similar expression profile to OmpW in the presence or absence of iron. Based on these results, we suggest that iron regulates OmpW by binding to Fur. Furthermore, SoxS, a transcriptional factor involved in oxidative stress, was found to negatively regulate OmpW. We found that downregulating or knocking out OmpW results in bacterial resistance to oxidative stress. These findings provide new insight into the regulation of OmpW expression by iron, and may represent a new mechanism contributing to iron-mediated infectious disease.

Quantitative characterization of the regulation of iron metabolism in glioblastoma stem-like cells using magnetophoresis.

This study focuses on different iron regulation mechanisms of glioblastoma (GBM) cancer stem-like cells (CSCs) and non-stem tumor cells (NSTCs) using multiple approaches: cell viability, density, and magnetophoresis. GBM CSCs and NSTCs were exposed to elevated iron concentration, and their magnetic susceptibility was measured using single cell magnetophoresis (SCM), which tracks the magnetic and settling velocities of thousands of individual cells passing through the magnetic field with a constant energy gradient. Our results consistently demonstrate that GBM NSTCs have higher magnetic susceptibility distribution at increased iron concentration compared with CSCs, and we speculate that it is because CSCs have the ability to store a high amount of iron in ferritin, whereas the free iron ions inside the NSTCs lead to higher magnetic susceptibility and reduced cell viability and growth. Further, their difference in magnetic susceptibility has led us to pursue a separate experiment using a quadrupole magnetic separator (QMS), a novel microfluidic device that uses a concentric channel and permanent magnets in a special configuration to separate samples based on their magnetic susceptibilities. GBM CSCs and NSTCs were exposed to elevated iron concentration, stained with two different trackers, mixed and introduced into QMS; subsequently, the separated fractions were analyzed by fluorescent microscopy. The separation results portray a successful label-less magnetic separation of the two populations.

Rationale and Current Evidence for Testing Iron Chelators for Treating Stroke.

To discuss the mechanisms of iron regulation in the brain and the pathophysiological role of deregulation of iron homeostasis following a stroke, and to review existing evidence supporting the potential role of iron chelators in the treatment of ischemic and hemorrhagic stroke. In recent years, accumulating evidence has highlighted the role of neuroinflammation in neurological injury after ischemic and hemorrhagic stroke, and that free iron is central to this process. Via the Fenton reaction, free iron catalyzes the conversion of superoxide ion and hydrogen peroxide into hydroxyl radicals, which promote oxidative stress. Advances in our understanding of changes in brain iron metabolism and its relationship to neuronal injury in stroke could provide new therapeutic strategies to improve the outcome of stroke patients. Pharmacological agents targeting brain iron regulation hold promise as potentially effective treatments in both ischemic and hemorrhagic stroke.

Iron-responsive element-binding protein 2 plays an essential role in regulating prostate cancer cell growth.

Iron-responsive element-binding proteins (IRPs) are master regulators of cellular iron homeostasis. Our previous work demonstrated that iron homeostasis is altered in prostate cancer and contributes to prostate cancer progression. Here we report that prostate cancer cells overexpress IRP2 and that overexpression of IRP2 drives the altered iron phenotype of prostate cancer cells. IRP2 knockdown in prostate cancer cell lines reduces intracellular iron and causes cell cycle inhibition and apoptosis. Cell cycle analysis demonstrates that IRP2-depleted prostate cancer cells accumulate in G0/G1 due to induction of p15, p21, and p27. Activation of these pathways is sufficient to significantly reduce the growth of PC3 prostate tumors in vivo. In contrast, IRP1 knockdown does not affect iron homeostasis and only modestly affects cell growth, likely through an iron-independent mechanism. These results demonstrate that upregulation of IRP2 in prostate cancer cells co-opts normal iron regulatory mechanisms to facilitate iron retention and drive enhanced tumor growth.

Computational characterization of Iron metabolism in the Tsetse disease vector, Glossina morsitans: IRE stem-loops.

BackgroundIron metabolism and regulation is an indispensable part of species survival, most importantly for blood feeding insects. Iron regulatory proteins are central regulators of iron homeostasis, whose binding to iron response element (IRE) stem-loop structures within the UTRs of genes regulate expression at the post-transcriptional level. Despite the extensive literature on the mechanism of iron regulation in human, less attention has been given to insect and more specifically the blood feeding insects, where research has mainly focused on the characterization of ferritin and transferrin. We thus, examined the mechanism of iron homeostasis through a genome-wide computational identification of IREs and other enriched motifs in the UTRs of Glossina morsitans with the view to identify new IRE-regulated genes.ResultsWe identified 150 genes, of which two are known to contain IREs, namely the ferritin heavy chain and the MRCK-alpha. The remainder of the identified genes is considered novel including 20 hypothetical proteins, for which an iron-regulatory mechanism of action was inferred. Forty-three genes were found with IRE-signatures of regulation in two or more insects, while 46 were only found to be IRE-regulated in two species. Notably 39 % of the identified genes exclusively shared IRE-signatures in other Glossina species, which are potentially Glossina-specific adaptive measures in addressing its unique reproductive biology and blood meal-induced iron overload. In line with previous findings, we found no evidence pertaining to an IRE regulation of Transferrin, which highlight the importance of ferritin heavy chain and the other proposed transporters in the tsetse fly. In the context of iron-sequestration, key players of tsetse immune defence against trypanosomes have been introduced namely 14 stress and immune response genes, while 28 cell-envelop, transport, and binding genes were assigned a putative role in iron trafficking. Additionally, we identified and annotated enriched motifs in the UTRs of the putative IRE-regulated genes to derive at a co-regulatory network that maintains iron homeostasis in tsetse flies. Three putative microRNA-binding sites namely Gy-box, Brd-box and K-box motifs were identified among the regulatory motifs, enriched in the UTRs of the putative IRE-regulated genes.ConclusionBeyond our current view of iron metabolism in insects, with ferritin and transferrin as its key players, this study provides a comprehensive catalogue of genes with possible roles in the acquisition; transport and storage of iron hence iron homeostasis in the tsetse fly.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2932-7) contains supplementary material, which is available to authorized users.

OC-019 Iron Deficiency Anaemia and Hepcidin Levels in H. Pylori Infected Patients

Introduction IDA affects up to 5% of the adult population in the developing world. There is an association between H. pylori (Hp) infection and incidence of unexplained IDA, but the mechanisms remain unclear. In children it has been suggested that Hp disturbs the iron regulatory mechanism via hepicidin. This peptide hormone induces internalisation and degradation of the iron transporter protein ferroportin thus limiting iron absorption and release. Hepcidin expression is induced by inflammation, but how this relates to Hp and IDA has not been fully elucidated, particularly in adults. This pilot study aimed to characterise local and systemic iron transporter expression in IDA patients with and without Hp infection, in comparison to Hp negative dyspepsia controls. Methods Patients undergoing routine endoscopy for IDA (HpIDA and IDA groups, n = 18 and 40 respectively) or without IDA (control group, n = 18) donated blood and biopsy samples with informed consent and ethical approval. Hp status was assessed by three biopsy based tests and by serology. Duodenal and gastric biopsies were evaluated by immunohistochemistry for ferroportin and hepcidin, in addition to H&E staining for inflammation and atrophy grading. All scoring was carried out by experienced blinded histopathologists. A commercial ELISA assay was used to quantify serum Hepcidin-25. Results As expected, anaemia parameters were significantly lower in the HpIDA and IDA groups compared to the controls (P Conclusion IDA was associated with significantly lower levels of serum hepcidin in contrast to previous studies. Local or systemic factors such as inflammatory mediators could be driving this response as more severe atrophy was observed in both IDA groups. We now aim to perform quantitative analysis of hepcidin in the gastric specimens using RT-qPCR to further evaluate whether local Hp transcriptionally upregulated hepcidin expression might cause these effects on iron transport. Disclosure of Interest None Declared