Mechanisms Of Iron Homeostasis Research Articles

Free iron accumulation and oxidative stress burden induce ferroptotic atrophy of chicken yolk sac during the late embryogenesis

AbstractThe aim of this study was to investigate the mechanism of iron homeostasis and the ferroptosis pathway for yolk sac atrophy during late embryogenesis. To study the mechanism of yolk sac atrophy, 100 eggs were used. Further, 500 eggs were randomly divided into five treatments and in ovo feeding with different iron sources, such as FeSO4, ferrous glycinate (Fe‐Gly), or deferoxamine (DFO), to study the effects of free iron content on hatching quality and embryonic development. The results showed that total iron content of yolk decreased, but yolk sac increased from embryonic(E)13 to E19 (p < 0.05). Comparison of gene expression of iron transport systems showed that free iron accumulation and dysfunction occurred in the yolk sac. Yolk sac metabolites at E19 compared to E13 were more enriched in histidine and sulfur pathways, suppressing glutathione synthesis and resulting in oxidative stress damage in the yolk sac. Combined analysis of differential metabolites and gene expression in ferroptosis pathway at E13 and E19 revealed the activation of the yolk sac during late embryogenesis was probably through up‐regulation of ACSL4 expression and down‐regulation of GPX4 expression. Furthermore, in ovo feeding FeSO4 shortened the incubation time compared to CON, while Fe‐Gly or DFO delayed the hatching peak and increased hatching weight with less residual yolk. Collectively, it can be concluded that yolk sac atrophy during late embryogenesis may be mediated by iron disorders and provides a novel insight to modulate yolk sac nutrition, and hatching efficiency in chickens.

Iron deficiency and supplementation in heart failure.

Non-anaemic iron deficiency (NAID) is a strategic target in cardiovascular medicine because of its association with a range of adverse effects in various conditions. Endeavours to tackle NAID in heart failure have yielded mixed results, exposing knowledge gaps in how best to define 'iron deficiency' and the handling of iron therapies by the body. To address these gaps, we harness the latest understanding of the mechanisms of iron homeostasis outside the erythron and integrate clinical and preclinical lines of evidence. The emerging picture is that current definitions of iron deficiency do not assimilate the multiple influences at play in patients with heart failure and, consequently, fail to identify those with a truly unmet need for iron. Additionally, current iron supplementation therapies benefit onlycertain patients with heart failure, reflecting differences in the nature of the unmet need for iron and the modifying effects of anaemia and inflammation on the handling of iron therapies by the body. Building on these insights, we identify untapped opportunities in the management of NAID, including the refinement of current approaches and the development of novel strategies. Lessons learned from NAID in cardiovascular disease could ultimately translate into benefits for patients with other chronic conditions such as chronic kidney disease, chronic obstructive pulmonary disease and cancer.

Iron Deficiency Modulates Metabolic Landscape of Bacteroidetes Promoting Its Resilience during Inflammation.

Bacteria have to persist under low iron conditions in order to adapt to the nutritional immunity of a host. Since the knowledge of iron stimulon of Bacteroidetes is sparse, we examined oral (Porphyromonas gingivalis and Prevotella intermedia) and gut (Bacteroides thataiotaomicron) representatives for their ability to adapt to iron deplete and iron replete conditions. Our transcriptomics and comparative genomics analysis show that many iron-regulated mechanisms are conserved within the phylum. They include genes upregulated in low iron, as follows: fldA (flavodoxin), hmu (hemin uptake operon), and loci encoding ABC transporters. Downregulated genes were frd (ferredoxin), rbr (rubrerythrin), sdh (succinate dehydrogenase/fumarate reductase), vor (oxoglutarate oxidoreductase/dehydrogenase), and pfor (pyruvate:ferredoxin/flavodoxin oxidoreductase). Some genus-specific mechanisms, such as the sus of B. thetaiotaomicron coding for carbohydrate metabolism and the xusABC coding for xenosiderophore utilization were also identified. While all bacteria tested in our study had the nrfAH operon coding for nitrite reduction and were able to reduce nitrite levels present in culture media, the expression of the operon was iron dependent only in B. thetaiotaomicron. It is noteworthy that we identified a significant overlap between regulated genes found in our study and the B. thetaiotaomicron colitis study (W. Zhu, M. G. Winter, L. Spiga, E. R. Hughes et al., Cell Host Microbe 27:376-388, 2020, http://dx.doi.org/10.1016/j.chom.2020.01.010). Many of those commonly regulated genes were also iron regulated in the oral bacterial genera. Overall, this work points to iron being the master regulator enabling bacterial persistence in the host and paves the way for a more generalized investigation of the molecular mechanisms of iron homeostasis in Bacteroidetes. IMPORTANCE Bacteroidetes are an important group of anaerobic bacteria abundant both in the oral and gut microbiomes. Although iron is a required nutrient for most living organisms, the molecular mechanisms of adaptation to the changing levels of iron are not well known in this group of bacteria. We defined the iron stimulon of Bacteroidetes by examination of the transcriptomic response of Porphyromonas gingivalis and Prevotella intermedia (both belong to the oral microbiome) and Bacteroidetes thetaiotaomicron (belongs to the gut microbiome). Our results indicate that many of the iron-regulated operons are shared among the three genera. Furthermore, using bioinformatics analysis, we identified a significant overlap between our in vitro studies and transcriptomic data derived from a colitis study, thus underscoring the biological significance of our work. Defining the iron-dependent stimulon of Bacteroidetes can help to identify the molecular mechanisms of iron-dependent regulation as well as better understand the persistence of the anaerobes in the human host.

Structures of ferroportin in complex with its specific inhibitor vamifeport.

A central regulatory mechanism of iron homeostasis in humans involves ferroportin (FPN), the sole cellular iron exporter, and the peptide hormone hepcidin, which inhibits Fe2+ transport and induces internalization and degradation of FPN. Dysregulation of the FPN/hepcidin axis leads to diverse pathological conditions, and consequently, pharmacological compounds that inhibit FPN-mediated iron transport are of high clinical interest. Here, we describe the cryo-electron microscopy structures of human FPN in complex with synthetic nanobodies and vamifeport (VIT-2763), the first clinical-stage oral FPN inhibitor. Vamifeport competes with hepcidin for FPN binding and is currently in clinical development for β-thalassemia and sickle cell disease. The structures display two distinct conformations of FPN, representing outward-facing and occluded states of the transporter. The vamifeport site is located in the center of the protein, where the overlap with hepcidin interactions underlies the competitive relationship between the two molecules. The introduction of point mutations in the binding pocket of vamifeport reduces its affinity to FPN, emphasizing the relevance of the structural data. Together, our study reveals conformational rearrangements of FPN that are of potential relevance for transport, and it provides initial insight into the pharmacological targeting of this unique iron efflux transporter.

Mechanisms of iron homeostasis in Pseudomonas aeruginosa and emerging therapeutics directed to disrupt this vital process.

Pseudomonas aeruginosa is an opportunistic pathogen able to infect any human tissue. One of the reasons for its high adaptability and colonization of host tissues is its capacity of maintaining iron homeostasis through a wide array of iron acquisition and removal mechanisms. Due to their ability to cause life-threatening acute and chronic infections, especially among cystic fibrosis and immunocompromised patients, and their propensity to acquire resistance to many antibiotics, the World Health Organization (WHO) has encouraged the scientific community to find new strategies to eradicate this pathogen. Several recent strategies to battle P.aeruginosa focus on targeting iron homeostasis mechanisms, turning its greatest advantage into an exploitable weak point. In this review, we discuss the different mechanisms used by P.aeruginosa to maintain iron homeostasis and the strategies being developed to fight this pathogen by blocking these mechanisms. Among others, the use of iron chelators and mimics, as well as disruption of siderophore production and uptake, have shown promising results in reducing viability and/or virulence of this pathogen. The so-called 'Trojan-horse' strategy taking advantage of the siderophore uptake systems is emerging as an efficient method to improve delivery of antibiotics into the bacterial cells. Moreover, siderophore transporters are considered promising targets for the developing of P.aeruginosa vaccines.

Abstract TP117: Temporal Serum Iron And Hemoglobin Changes In Patients From The High Dose Deferoxamine In Intracerebral Hemorrhage Trial

Introduction: Following intracerebral hemorrhage (ICH), elevated cerebral tissue iron concentrations are seen. It is unclear how peripheral serum iron concentrations change over time and how they relate to anemia after ICH. Given the known impacts of iron concentrations and anemia on clinical outcomes, we explored serum iron biomarker and hemoglobin concentration changes after acute ICH. Methods: A post hoc analysis of patients with available serial (baseline and 5 day) serum biomarker data from the multicenter, High Dose Deferoxamine in Intracerebral Hemorrhage (HI-DEF) trial was performed. Changes of serum hemoglobin, iron, transferrin, and ferritin were assessed using repeated measure ANOVA analyses. Deferoxamine treatment and poor 90 day modified Rankin Scale 4-6 were separately assessed as between subject factors for these laboratory changes. Results: Of 42 ICH patients analyzed, the mean age was 64, 62% were male, median ICH volume was 15.7mL (IQR 5.7-37.5), and baseline anemia was seen in 19%. We identified significant decrements of hemoglobin (mean difference -1.4 g/dL; 95%CI: -1.9 to -0.9; p<0.0001), iron (mean difference -16.9 ug/dL; 95%CI: -29.7 to -4.1; p=0.01), transferrin (mean difference -43.9 ng/mL; 95%CI: -56.6 to -31.3; p<0.0001), and conversely, significant ferritin elevations (mean difference 104.5 ug/L; 95%CI: 52.5-156.6; p<0.0001) at 5 days. Anemia was identified in 43% of patients at 5 days. Deferoxamine did not have a significant impact on these repeated measures. Patients with poor long-term outcomes had greater decrements in hemoglobin compared to those with good outcomes (mean difference: -1.5 g/dL; 95%CI: -2.6 to -0.3; p=0.01). Conclusions: Serum iron and hemoglobin concentrations decrease significantly over time following ICH. Patients with worse long term ICH outcomes had greater hemoglobin decrements during their hospitalization. The aggregate iron biomarker and hemoglobin concentration changes suggest anemia development may be due to anemia of inflammation. Further work is required to address the pathophysiologic difference between systemic and central iron homeostasis mechanisms following ICH and the impacts that ICH has on inflammation, systemic iron homeostasis, anemia, and clinical outcomes.

Comprehensive Survey of ChIP-Seq Datasets to Identify Candidate Iron Homeostasis Genes Regulated by Chromatin Modifications.

Vital biochemical reactions including photosynthesis to respiration require iron, which should be tightly regulated. Although increasing evidence reveals the importance of epigenetic regulation in gene expression and signaling, the role of histone modifications and chromatin remodeling in plant iron homeostasis is not well understood. In this study, we surveyed publicly available ChIP-seq datasets of Arabidopsis wild-type and mutants defective in key enzymes of histone modification and chromatin remodeling and compared the deposition of epigenetic marks on loci of genes involved in iron regulation. Based on the analysis, we compiled a comprehensive list of iron homeostasis genes with differential enrichment of various histone modifications. This report will provide a resource for future studies to investigate epigenetic regulatory mechanisms of iron homeostasis in plants.

Iron Homeostasis in Insects.

Iron is an essential micronutrient for all types of organisms; however, iron has chemical properties that can be harmful to cells. Because iron is both necessary and potentially damaging, insects have homeostatic processes that control the redox state, quantity, and location of iron in the body. These processes include uptake of iron from the diet, intracellular and extracellular iron transport, and iron storage. Early studies of iron-binding proteins in insects suggested that insects and mammals have surprisingly different mechanisms of iron homeostasis, including different primary mechanisms for exporting iron from cells and for transporting iron from one cell to another, and subsequent studies have continued to support this view. This review summarizes current knowledge about iron homeostasis in insects, compares insect and mammalian iron homeostasis mechanisms, and calls attention to key remaining knowledge gaps.

Role of Iron Uptake Systems in Coordinating Iron Homeostasis in NaCl-resistant Mutant of the Cyanobacterium Nostoc muscorum

Aims: To investigate the effect of NaCl stress on parent Nostoc muscorum and its spontaneously occurring mutant clone showing resistance to growth inhibitory action of NaCl in terms of various physiological parameters. We have further analyzed the role of iron uptake systems in providing a resistant phenotype.
 Place and Duration of Study: Division of Microbiology, Department of Botany, Government Motilal Science College, Bhopal 462008 (M.P.) India. This work was carried out between August 2021 to May 2022.
 Methodology: We have examined the various physiological parameters viz. growth, specific growth rate, photosynthetic O2 evolution, and nitrogenase activity as per the prescribed protocol. Further, DNA microarray analysis was carried out using the Agilent platform.
 Results: NaCl stress adversely affected growth, photosynthetic O2 evolution, and nitrogenase activity of the wild-type Nostoc muscorum, while NaCl-resistant mutant remains unaffected under a given stress. Microarray data analysis identified 24 ORF related to the uptake of iron with fold regulation ≥2 in the mutant strain. These ORFs belonging to the ABC-type ferric iron transporter that plays a significant role in the iron acquisition were identified in the mutant strain.
 Conclusion: The mechanism of iron homeostasis in the NaCl-resistant mutant has been explained. The results presented are essential to explain the regulatory role of the iron uptake system in stressed conditions.

PPARδ Activation Mitigates 6-OHDA-Induced Neuronal Damage by Regulating Intracellular Iron Levels.

Intracellular iron accumulation in dopaminergic neurons contributes to neuronal cell death in progressive neurodegenerative disorders such as Parkinson’s disease. However, the mechanisms of iron homeostasis in this context remain incompletely understood. In the present study, we assessed the role of the nuclear receptor peroxisome proliferator-activated receptor δ (PPARδ) in cellular iron homeostasis. We identified that PPARδ inhibited 6-hydroxydopamine (6-OHDA)-triggered neurotoxicity in SH-SY5Y neuroblastoma cells. PPARδ activation with GW501516, a specific PPARδ agonist, mitigated 6-OHDA-induced neuronal damage. Further, PPARδ activation also suppressed iron accumulation, which contributes to 6-OHDA-induced neuronal damage. PPARδ activation attenuated 6-OHDA-induced neuronal damage in a similar manner to that of the iron chelator deferoxamine. We further elucidated that PPARδ modulated cellular iron homeostasis by regulating expression of divalent metal transporter 1, ferroportin 1, and ferritin, but not transferrin receptor 1, through iron regulatory protein 1 in 6-OHDA-treated cells. Interestingly, PPARδ activation suppressed 6-OHDA-triggered generation of reactive oxygen species and lipid peroxides. The effects of GW501516 were abrogated by shRNA knockdown of PPARδ, indicating that the effects of GW501516 were PPARδ-dependent. Taken together, these findings suggest that PPARδ attenuates 6-OHDA-induced neurotoxicity by preventing intracellular iron accumulation, thereby suppressing iron overload-associated generation of reactive oxygen species and lipid peroxides, key mediators of ferroptotic cell death.

Salmon Protein Hydrolysate Potentiates the Growth Inhibitory Effect of Bicalutamide on Human Prostate Cancer Cell Lines LNCaP and PC3 by Modulating Iron Homeostasis.

Prostate cancer is a common cause of cancer death in men. In advanced stages of prostate cancer, androgen deprivation therapy (ADT) is initiated. Despite ADT, prostate cancers invariably progress to become androgen independent. A growing body of evidence implicates iron dysmetabolism in prostate cancer progression. A bioactive peptide-rich salmon protein hydrolysate (SPH) has previously been demonstrated to modulate iron homeostatic mechanisms. In the present study, the anticancer effect of SPH and bicalutamide co-treatment on LNCaP and PC3 prostate cancer cell proliferation was investigated. Our results found that SPH potentiates the anti-proliferative effect of bicalutamide in a dose-dependent manner for both cell lines. In the presence of 160 µg/mL SPH, co-treatment with 1.0 µM bicalutamide decreased LNCaP cells’ relative colony survival from 25% (1.0 µM bicalutamide monotreatment) to 2% after culturing for 12 days. For PC3 cells, the relative colony survival diminished from 52% (10.0 µM bicalutamide) to 32% at an SPH concentration of 160 µg/mL. Gene expression profiling, employing quantitative real-time PCR, revealed that the inhibitory effects were related to significant FTH1 up-regulation with a concomitant TFRC down-regulation. In conclusion, our results provide in vitro evidence that SPH potentiates the growth inhibitory effect of bicalutamide on prostate cancer cells by modulating iron homeostasis mechanisms.

Cerebral Ischemia Induces Iron Deposit, Ferritin Accumulation, Nuclear Receptor Coactivator 4-depletion, and Ferroptosis.

The neuronal death upon cerebral ischemia shares not only characteristics of necrosis, apoptosis, and autophagy but also exhibits biochemical and morphological characteristics of ferroptosis. Ferroptosis is a regulated form of cell death that is considered to be an oxidative iron-dependent process. It is now commonly accepted that iron and free radicals are considered to cause lipid peroxidation as well as the oxidation of proteins and nucleic acids, leading to increased membrane and enzymatic dysfunction and finally contributing to cell death. Although ferroptosis was first described in cancer cells, emerging evidence now links mechanisms of ferroptosis to many different diseases, including cerebral ischemia. The objective of this study was to identify the key players and underlying biochemical pathways of ferroptosis, leading to cell death upon focal cerebral ischemia in mice by using immunofluorescence, Western blotting, histochemistry, and densitometry. In this study, we demonstrated that cerebral ischemia induced iron-deposition, downregulated dramatically the expression of the glutathione peroxidase 4 (GPX4), decreased the expression of the nuclear receptor coactivator 4 (NCOA4), and induced inappropriate accumulation of ferritin in the ischemic brain. This supports the hypothesis that an ischemic insult may induce ferroptosis through inhibition of GPX4. We conclude that iron excess following cerebral ischemia leads to cell death despite activating compensatory mechanisms for iron homeostasis, as illustrated by the accumulation of ferritins. These data emphasized the presence of a cellular mechanism that allows neuronal cells to buffer iron levels.

Iron Deficiency in Heart Failure: Characteristics and Treatment.

Purpose of the ReviewIron deficiency in heart failure has been associated with impaired functional capacity and quality of life. The purpose of this paper is to review mechanisms of iron homeostasis and current clinical data exploring mechanisms of iron repletion in heart failure.Recent FindingMultiple international societies now advise iron repletion for symptomatic heart failure patients with iron deficiency. Due to the chronic inflammation in heart failure, iron deficiency in heart failure is classically defined as ferritin < 100 µg/L or ferritin 100–300 µg/L and transferrin saturation < 20%. Multiple randomized clinical trials have demonstrated benefit from intravenous iron repletion, though studies have predominantly focused on functional capacity and quality of life. A recent study, AFFIRM-AHF, supports the treatment of iron deficiency identified during acute heart failure admissions, noting a reduction in future heart failure hospitalizations. Studies examining iron repletion in patients with heart failure with preserved ejection fraction are currently in process.SummaryIron homeostasis is maintained predominantly through the regulation of iron absorption, keeping iron levels tightly controlled in the normal state regardless of iron intake. In chronic heart failure however, iron homeostasis becomes dysregulated with resulting iron deficiency in many patients, with and without associated anemia. Iron is a critical element not only for erythropoiesis and oxygen carrying, but also for energy production at the level of the mitochondria and in other cell processes. We thus propose a standardized approach be utilized to screen and treat heart failure patients with iron deficiency.

Iron Homeostasis Disorder and Alzheimer's Disease.

Iron is an essential trace metal for almost all organisms, including human; however, oxidative stress can easily be caused when iron is in excess, producing toxicity to the human body due to its capability to be both an electron donor and an electron acceptor. Although there is a strict regulation mechanism for iron homeostasis in the human body and brain, it is usually inevitably disturbed by genetic and environmental factors, or disordered with aging, which leads to iron metabolism diseases, including many neurodegenerative diseases such as Alzheimer’s disease (AD). AD is one of the most common degenerative diseases of the central nervous system (CNS) threatening human health. However, the precise pathogenesis of AD is still unclear, which seriously restricts the design of interventions and treatment drugs based on the pathogenesis of AD. Many studies have observed abnormal iron accumulation in different regions of the AD brain, resulting in cognitive, memory, motor and other nerve damages. Understanding the metabolic balance mechanism of iron in the brain is crucial for the treatment of AD, which would provide new cures for the disease. This paper reviews the recent progress in the relationship between iron and AD from the aspects of iron absorption in intestinal cells, storage and regulation of iron in cells and organs, especially for the regulation of iron homeostasis in the human brain and prospects the future directions for AD treatments.

Crosstalk between Iron and Arteriosclerosis.

Iron is an important element for life; however, intracellular labile iron overload can lead to the generation of reactive oxygen species and cellular damage. Although iron is mainly utilized for heme synthesis and is incorporated into hemoglobin, body iron status is often implicated in the pathogenesis of cardiovascular diseases. In a cell, iron is used for basic processes such as cell growth, maintenance, and repair. Thus, iron is considered to be involved in the pathogenesis of arteriosclerosis. In fact, clinical and experimental studies have shown an association between iron and arteriosclerosis. These data suggest the crosstalk between iron and arteriosclerosis. However, iron metabolism in arteriosclerosis is often complicated, and the systemic and cellular mechanisms of iron homeostasis in arteriosclerosis remain completely unsolved. Thus, in this review, we aimed to examine the role of iron in arteriosclerosis.

Ironing out mechanisms of iron homeostasis and disorders of iron deficiency.

Iron plays an important role in mammalian physiological processes. It is a critical component for the function of many proteins, including enzymes that require heme and iron-sulfur clusters. However, excess iron is also detrimental because of its ability to catalyze the formation of reactive oxygen species. As a result, cellular and systemic iron levels are tightly regulated to prevent oxidative damage. Iron deficiency can lead to a number of pathological conditions, the most prominent being anemia. Iron deficiency should be corrected to improve adult patients' symptoms and to facilitate normal growth during fetal development and childhood. However, inappropriate use of intravenous iron in chronic conditions, such as cancer and heart failure, in the absence of clear iron deficiency can lead to unwanted side effects. Thus, this form of therapy should be reserved for certain patients who cannot tolerate oral iron and need rapid iron replenishment. Here, we will review cellular and systemic iron homeostasis and will discuss complications of iron deficiency.

Prevalence of iron deficiency in heart transplant recipients.

Optimal iron management is crucial to marginal patients such as heart transplant recipients. As inflammatory mechanisms are present in transplant recipients, the definition of iron deficiency used in the general population might not be appropriate. To evaluate the prevalence and determinants of iron deficiency in Norwegian heart transplant recipients. We consecutively assessed iron parameters in all Norwegian heart transplant recipients at their annual follow-up. Several definitions of iron deficiency suggested in the literature were assessed: ferritin <100µg/L, or ferritin 100-300µg/L combined with transferrin saturation of <20% (IDHF ); ferritin <100µg/L (IDF100 ); transferrin saturation of <20% (IDTsat ), and ferritin <30µg/L (IDF30 ). 179 of 378 heart transplant recipients (47%) had iron deficiency defined as IDHF . 152 patients (40%) had IDF100 , and 103 patients (27%) had IDTsat . 17 patients (5%) had IDF30 . 88 patients (23%) had a C-reactive protein (CRP) >5.0µg/L. Iron deficiency defined as IDHF , IDF100, or IDTsat is prevalent in the heart transplant population, while IDF30 is not. Further research is required to identify the mechanisms of iron homeostasis in heart transplant recipients and to establish a definition of iron deficiency suitable for this population.

Transcriptomics Reveals Fast Changes in Salicylate and Jasmonate Signaling Pathways in Shoots of Carbonate-Tolerant Arabidopsis thaliana under Bicarbonate Exposure.

High bicarbonate concentrations of calcareous soils with high pH can affect crop performance due to different constraints. Among these, Fe deficiency has mostly been studied. The ability to mobilize sparingly soluble Fe is a key factor for tolerance. Here, a comparative transcriptomic analysis was performed with two naturally selected Arabidopsis thaliana demes, the carbonate-tolerant A1(c+) and the sensitive T6(c−). Analyses of plants exposed to either pH stress alone (pH 5.9 vs. pH 8.3) or to alkalinity caused by 10 mM NaHCO3 (pH 8.3) confirmed better growth and nutrient homeostasis of A1(c+) under alkaline conditions. RNA-sequencing (RNA-seq) revealed that bicarbonate quickly (3 h) induced Fe deficiency-related genes in T6(c−) leaves. Contrastingly, in A1(c+), initial changes concerned receptor-like proteins (RLP), jasmonate (JA) and salicylate (SA) pathways, methionine-derived glucosinolates (GS), sulfur starvation, starch degradation, and cell cycle. Our results suggest that leaves of carbonate-tolerant plants do not sense iron deficiency as fast as sensitive ones. This is in line with a more efficient Fe translocation to aerial parts. In A1(c+) leaves, the activation of other genes related to stress perception, signal transduction, GS, sulfur acquisition, and cell cycle precedes the induction of iron homeostasis mechanisms yielding an efficient response to bicarbonate stress.

Iron Dysregulation in Human Cancer: Altered Metabolism, Biomarkers for Diagnosis, Prognosis, Monitoring and Rationale for Therapy.

Simple SummaryIron is the more abundant metal ion in humans. It is essential for life as it has a role in various cellular processes involved, for instance, in cell metabolism and DNA synthesis. These functions are crucial for cell proliferation, and it is therefore not surprising that iron is accumulated in tumors. In this review, we describe normal and altered iron homeostasis mechanisms. We also provide a vision of iron-related proteins with altered expression in cancers and discuss their potential as diagnostic and/or prognostic biomarkers. Finally, we give an overview of therapeutic strategies acting on iron metabolism to fight against cancers.Iron (Fe) is a trace element that plays essential roles in various biological processes such as DNA synthesis and repair, as well as cellular energy production and oxygen transport, and it is currently widely recognized that iron homeostasis is dysregulated in many cancers. Indeed, several iron homeostasis proteins may be responsible for malignant tumor initiation, proliferation, and for the metastatic spread of tumors. A large number of studies demonstrated the potential clinical value of utilizing these deregulated proteins as prognostic and/or predictive biomarkers of malignancy and/or response to anticancer treatments. Additionally, the iron present in cancer cells and the importance of iron in ferroptosis cell death signaling pathways prompted the development of therapeutic strategies against advanced stage or resistant cancers. In this review, we select relevant and promising studies in the field of iron metabolism in cancer research and clinical oncology. Besides this, we discuss some co-existing discrepant findings. We also present and discuss the latest lines of research related to targeting iron, or its regulatory pathways, as potential promising anticancer strategies for human therapy. Iron chelators, such as deferoxamine or iron-oxide-based nanoparticles, which are already tested in clinical trials, alone or in combination with chemotherapy, are also reported.

Systematic Surveys of Iron Homeostasis Mechanisms Reveal Ferritin Superfamily and Nucleotide Surveillance Regulation to be Modified by PINK1 Absence.

Iron deprivation activates mitophagy and extends lifespan in nematodes. In patients suffering from Parkinson’s disease (PD), PINK1-PRKN mutations via deficient mitophagy trigger iron accumulation and reduce lifespan. To evaluate molecular effects of iron chelator drugs as a potential PD therapy, we assessed fibroblasts by global proteome profiles and targeted transcript analyses. In mouse cells, iron shortage decreased protein abundance for iron-binding nucleotide metabolism enzymes (prominently XDH and ferritin homolog RRM2). It also decreased the expression of factors with a role for nucleotide surveillance, which associate with iron-sulfur-clusters (ISC), and are important for growth and survival. This widespread effect included prominently Nthl1-Ppat-Bdh2, but also mitochondrial Glrx5-Nfu1-Bola1, cytosolic Aco1-Abce1-Tyw5, and nuclear Dna2-Elp3-Pold1-Prim2. Incidentally, upregulated Pink1-Prkn levels explained mitophagy induction, the downregulated expression of Slc25a28 suggested it to function in iron export. The impact of PINK1 mutations in mouse and patient cells was pronounced only after iron overload, causing hyperreactive expression of ribosomal surveillance factor Abce1 and of ferritin, despite ferritin translation being repressed by IRP1. This misregulation might be explained by the deficiency of the ISC-biogenesis factor GLRX5. Our systematic survey suggests mitochondrial ISC-biogenesis and post-transcriptional iron regulation to be important in the decision, whether organisms undergo PD pathogenesis or healthy aging.