Regulation Of Cellular Iron Homeostasis Research Articles

A regulatory module comprising G3BP1-FBXL5-IRP2 axis determines sodium arsenite-induced ferroptosis

Arsenic contamination is extremely threatening to the global public health. It was reported that sodium arsenite exposure induces serious kidney injury. However, the underlying mechanism is unclear. Ferroptosis is a newly characterized form of iron-dependent programmed cell death, which is implicated in the pathogenesis of various human diseases, including kidney injury. The lethal accumulation of iron-catalyzed lipid peroxidation is the fundamental biochemical characteristic of ferroptosis. Herein we report that sodium arsenite exposure initiates ferroptosis in mammalian HEK293, MEF and HT1080 cells, and induces ferroptosis-associated acute kidney injury in mice. RNA-binding protein G3BP1, the switch component of stress granules, is indispensable for sodium arsenite-induced ferroptosis in a stress granule-independent manner. Mechanistically, G3BP1 stabilizes IRP2, the master regulator of cellular iron homeostasis, through binding to and suppressing the translation of FBXL5 mRNA, which encodes the E3 ligase component to mediate IRP2 ubiquitination and proteasomal degradation. Sodium arsenite intoxication expedites this G3BP1-FBXL5-IRP2 axis and elevates cellular labile free iron, which is responsible for sodium arsenite exposure-induced lipid peroxidation and ferroptotic cell death. In summary, this study highlights a regulatory module comprising G3BP1-FBXL5-IRP2 axis in determining sodium arsenite-induced ferroptosis and ferroptosis-associated acute kidney injury in mice.

Restoring neuronal iron homeostasis revitalizes neurogenesis after spinal cord injury.

Spinal cord injury (SCI) can lead to iron overloading and subsequent neuronal ferroptosis, which hinders the recovery of locomotor function. However, it is still unclear whether the maintenance of neuronal iron homeostasis enables to revitalize intrinsic neurogenesis. Herein, we report the regulation of cellular iron homeostasis after SCI via the chelation of excess iron ions and modulation of the iron transportation pathway using polyphenol-based hydrogels for the revitalization of intrinsic neurogenesis. The reversed iron overloading can promote neural stem/progenitor cell differentiation into neurons and elicit the regenerative potential of newborn neurons, which is accompanied by improved axon reinnervation and remyelination. Notably, polyphenol-based hydrogels significantly increase the neurological motor scores from ~8 to 18 (out of 21) and restore the transmission of sensory and motor electrophysiological signals after SCI. Maintenance of iron homeostasis at the site of SCI using polyphenol-based hydrogels provides a promising paradigm to revitalize neurogenesis for the treatment of iron accumulation-related nervous system diseases.

β-catenin-IRP2-primed iron availability to mitochondrial metabolism is druggable for active β-catenin-mediated cancer

BackgroundAlthough β-catenin signaling cascade is frequently altered in human cancers, targeting this pathway has not been approved for cancer treatment.MethodsHigh-throughput screening of an FDA-approved drug library was conducted to identify therapeutics that selectively inhibited the cells with activated β-catenin. Efficacy of iron chelator and mitochondrial inhibitor was evaluated for suppression of cell proliferation and tumorigenesis. Cellular chelatable iron levels were measured to gain insight into the potential vulnerability of β-catenin-activated cells to iron deprivation. Extracellular flux analysis of mitochondrial function was conducted to evaluate the downstream events of iron deprivation. Chromatin immunoprecipitation, real-time quantitative PCR and immunoblotting were performed to identify β-catenin targets. Depletion of iron-regulatory protein 2 (IRP2), a key regulator of cellular iron homeostasis, was carried out to elucidate its significance in β-catenin-activated cells. Online databases were analyzed for correlation between β-catenin activity and IRP2-TfR1 axis in human cancers.ResultsIron chelators were identified as selective inhibitors against β-catenin-activated cells. Deferoxamine mesylate, an iron chelator, preferentially repressed β-catenin-activated cell proliferation and tumor formation in mice. Mechanically, β-catenin stimulated the transcription of IRP2 to increase labile iron level. Depletion of IRP2-sequered iron impaired β-catenin-invigorated mitochondrial function. Moreover, mitochondrial inhibitor S-Gboxin selectively reduced β-catenin-associated cell viability and tumor formation.Conclusionsβ-catenin/IRP2/iron stimulation of mitochondrial energetics is targetable vulnerability of β-catenin-potentiated cancer.

The role of mitochondria in the recovery of neurons after injury.

The role of mitochondria in the recovery of neurons after injury.

Interleukin-6 triggers toxic neuronal iron sequestration in response to pathological α-synuclein.

SUMMARYα-synuclein (α-syn) aggregation and accumulation drive neurodegeneration in Parkinson’s disease (PD). The substantia nigra of patients with PD contains excess iron, yet the underlying mechanism accounting for this iron accumulation is unclear. Here, we show that misfolded α-syn activates microglia, which release interleukin 6 (IL-6). IL-6, via its trans-signaling pathway, induces changes in the neuronal iron transcriptome that promote ferrous iron uptake and decrease cellular iron export via a pathway we term the cellular iron sequestration response, or CISR. The brains of patients with PD exhibit molecular signatures of the IL-6-mediated CISR. Genetic deletion of IL-6, or treatment with the iron chelator deferiprone, reduces pathological α-syn toxicity in a mouse model of sporadic PD. These data suggest that IL-6-induced CISR leads to toxic neuronal iron accumulation, contributing to synuclein-induced neurodegeneration.

Biochemistry of mammalian ferritins in the regulation of cellular iron homeostasis and oxidative responses.

Ferritin, an iron-storage protein, regulates cellular iron metabolism and oxidative stress. The ferritin structure is characterized as a spherical cage, inside which large amounts of iron are deposited in a safe, compact and bioavailable form. All ferritins readily catalyze Fe(II) oxidation by peroxides at the ferroxidase center to prevent free Fe(II) from participating in oxygen free radical formation via Fenton chemistry. Thus, ferritin is generally recognized as a cytoprotective stratagem against intracellular oxidative damage The expression of cytosolic ferritins is usually regulated by iron status and oxidative stress at both the transcriptional and post-transcriptional levels. The mechanism of ferritin-mediated iron recycling is far from clarified, though nuclear receptor co-activator 4 (NCOA4) was recently identified as a cargo receptor for ferritin-based lysosomal degradation. Cytosolic ferritins are heteropolymers assembled by H- and L-chains in different proportions. The mitochondrial ferritins are homopolymers and distributed in restricted tissues. They play protective roles in mitochondria where heme- and Fe/S-enzymes are synthesized and high levels of ROS are produced. Genetic ferritin disorders are mainly related to the L-chain mutations, which generally cause severe movement diseases. This review is focused on the biochemistry and function of mammalian intracellular ferritin as the major iron-storage and anti-oxidation protein.

How Oxidation of a Unique Iron-Sulfur Cluster in FBXL5 Regulates IRP2 Levels and Promotes Regulation of Iron Metabolism Proteins

In this issue of Molecular Cell, Wang etal. (2020) discover that the C-terminal substrate-binding domain of FBXL5 contains a redox-sensitive [2Fe-2S] cluster that, upon oxidation, promotes FBXL5 binding to IRP2 to effect its oxygen-dependent degradation, unveiling a novel and previously unrecognized mechanism involved in regulation of cellular iron homeostasis.

Irp2 regulates insulin production through iron-mediated Cdkal1-catalyzed tRNA modification

Regulation of cellular iron homeostasis is crucial as both iron excess and deficiency cause hematological and neurodegenerative diseases. Here we show that mice lacking iron-regulatory protein 2 (Irp2), a regulator of cellular iron homeostasis, develop diabetes. Irp2 post-transcriptionally regulates the iron-uptake protein transferrin receptor 1 (TfR1) and the iron-storage protein ferritin, and dysregulation of these proteins due to Irp2 loss causes functional iron deficiency in β cells. This impairs Fe–S cluster biosynthesis, reducing the function of Cdkal1, an Fe–S cluster enzyme that catalyzes methylthiolation of t6A37 in tRNALysUUU to ms2t6A37. As a consequence, lysine codons in proinsulin are misread and proinsulin processing is impaired, reducing insulin content and secretion. Iron normalizes ms2t6A37 and proinsulin lysine incorporation, restoring insulin content and secretion in Irp2−/− β cells. These studies reveal a previously unidentified link between insulin processing and cellular iron deficiency that may have relevance to type 2 diabetes in humans.

Soluble Form of Transferrin Receptor as A Biomarker of Ineffective Erythropoiesis and Iron Overload in Pediatric Egyptian Patients with b-Thalassemia

AbstractBackground: Beta-thalassemias (b-thalassemias) are a group of inherited blood disorders caused by reduced or absent synthesis of the beta chains of hemoglobin resulting in variable phenotypes ranging from severe anemia to clinically asymp-tomatic individuals. Thalassemia is the commonest hereditary hemolytic anemia in Egypt. Iron overload is a major compli-cation of repeated blood transfusion in patients with thalassem-ia. Soluble Transferrin Receptor (sTfR), one of the main regulators of cellular iron homeostasis, is the truncated form of the tissue receptor.Aim of Study: This work was conducted to study the pathophysiology of iron overload in children with b-thalassemia intermedia and thalassemia major and explore the possible utility of Soluble Transferrin Receptor (sTfR) for the evaluation of iron overload and ineffective erythropoi-esis in pediatric Egyptian patients with s thalassemia major, b-thalassemia intermedia and comparing this with the controls.Patients and Methods: This study was conducted on sixty b-thalassemia patients (30 b-thalassemia major and 30 b-thalassemia intermedia) together with 30 age and sex matched controls. Patients were selected from the outpatient clinics of the Pediatric Hematology Unit and the Inpatients of Pediatric Department; Faculty of Medicine, Beni Suef University Hospital during the year 2017. Patients and control were subjected to clinical evaluation and complete blood count along with serum ferritin and sTfR levels by Enzyme-Linked Immunosorbent Assay (ELIZA) technique.Results: Both serum ferritin and sTfR levels were signif-icantly higher in patients compared with controls and in patients with thalassemia major compared with those with thalassemia intermedia. Serum ferritin and sTfR levels were significantly positively correlated with patients' age and with each other. Each of them was negatively correlated with age of disease onset, frequency of blood transfusions and with hemoglobin level.Conclusion: Serum levels of ferritin and soluble transferrin receptor were significantly higher in both thalassemic groups in comparison to control group.

Downregulation of TfR1 promotes progression of colorectal cancer via the JAK/STAT pathway.

Background: Colorectal cancer (CRC) is one of the most prevalent gastrointestinal malignancies. The incidence of CRC has been rapidly increasing in China. Transferrin receptor 1 (TfR1) is a key regulator of cellular iron homeostasis. Several studies have demonstrated TfR1 overexpression in a variety of human tumors, but the association between TfR1 and CRC remains unclear.Methods: TfR1 expression was evaluated in six CRC cell lines and tumor tissues. A total of 201 CRC patients were included for immunohistochemistry and 19 pairs of frozen tissues were used for real-time PCR. Cell proliferation, cell cycle, cell migration and invasion, and in vivo carcinogenesis were tested after downregulation of TfR1 by lentivirus. Protein microarray and Western blot analyses were used to explore the underlying mechanisms of TfR1 in CRC.Results: TfR1 expression was higher in CRC tissues than in normal tissues (57.2% vs 22.9%, P＜0.001). TfR1 expression was obviously higher in CRC tissues with well differentiation (P＝0.008), no lymph node metastasis (P＝0.002), no distant metastasis (P＝0.006), no vascular invasion (P＜0.001) and early TNM stage (P＝0.013). CRC patients with TfR1-positive expression had a better survival than those with TfR1-negative expression (P＝0.044). Downregulation of TfR1 expression inhibited cell proliferation, promoted cells from G1 phase to S phase and facilitated cell migration and invasion. Knockdown of TfR1 also suppressed tumor growth in BALB/C-nu mice. Protein microarray and Western blot analyses showed that the Janus protein tyrosine kinase/signal transducer and activator of transcription pathway was activated along with downregulation of TfR1 expression.Conclusion: Though TfR1 was overexpressed in colorectal cancer tissues, there was evidence that downregulation of TfR1 could promote cancer progression.

Evaluating the predictions of the protein stability change upon single amino acid substitutions for the FXN CAGI5 challenge.

Frataxin (FXN) is a highly conserved protein found in prokaryotes and eukaryotes that is required for efficient regulation of cellular iron homeostasis. Experimental evidence associates amino acid substitutions of the FXN to Friedreich Ataxia, a neurodegenerative disorder. Recently, new thermodynamic experiments have been performed to study the impact of somatic variations identified in cancer tissues on protein stability. The Critical Assessment of Genome Interpretation (CAGI) data provider at the University of Rome measured the unfolding free energy of a set of variants (FXN challenge data set) with far-UV circular dichroism and intrinsic fluorescence spectra. These values have been used to calculate the change in unfolding free energy between the variant and wild-type proteins at zero concentration of denaturant . The FXN challenge data set, composed of eight amino acid substitutions, was used to evaluate the performance of the current computational methods for predicting the value associated with the variants and to classify them as destabilizing and not destabilizing. For the fifth edition of CAGI, six independent research groups from Asia, Australia, Europe, and North America submitted 12 sets of predictions from different approaches. In this paper, we report the results of our assessment and discuss the limitations of the tested algorithms.

Expression and characterization of the ferritin binding domain of Nuclear Receptor Coactivator-4 (NCOA4)

Ferritinophagy is the process of autophagic degradation of ferritin that participates in the regulation of cellular iron homeostasis. This process was shown to be mediated by the selective cargo-receptor Nuclear Receptor Coactivator-4 (NCOA4) that binds ferritin and targets it to emerging autophagosome. To characterize some of the biochemical properties of the interaction between the two proteins we cloned and expressed in E. coli the ferritin-binding domain of human NCOA4, fragment 383–522. It was purified and subjected to biochemical analysis. The NCOA4(383–522) fragment was expressed in soluble and dimeric form, and CD spectra indicated low level of secondary structure. The Ferritin binding activity of the fragment was investigated by developing an electrophoretic mobility shift and an ELISA assays. They showed that the NCOA4 fragment binds the H-ferritin with an affinity in the nM range, but not the R23A H-ferritin mutant and the L-ferritin chain, confirming the high specificity for the H-chain. The H-ferritin could bind up to 24 NCOA4(383–522) fragments forming highly stable and insoluble complexes. The binding was partially inhibited only by Fe(II) among the various divalent metal ions analyzed. The iron-dependent, highly-specific formation of the remarkably stable H-ferritin-NCOA4 complex shown in this work may be important for the characterization of the mechanism of ferritinophagy.

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.

Anamorsin/Ndor1 Complex Reduces [2Fe-2S]-MitoNEET via a Transient Protein-Protein Interaction.

Human mitoNEET is a homodimeric protein anchored to the outer mitochondrial membrane and has a C-terminal [2Fe-2S] binding domain located in the cytosol. Recently, human mitoNEET has been shown to be implicated in Fe/S cluster repair of cytosolic iron regulatory protein 1 (IRP1), a key regulator of cellular iron homeostasis in mammalian cells. The Fe/S cluster repair function of mitoNEET is based on an Fe/S redox switch mechanism: under normal cellular conditions, reduced [2Fe-2S]+-mitoNEET is present and is inactive as an Fe/S cluster transfer protein; under conditions of oxidative cellular stress, the clusters of mitoNEET become oxidized, and the formed [2Fe-2S]2+-mitoNEET species reacts promptly to initiate Fe/S cluster transfer to IRP1, recycling the cytosolic apo-IRP1 into holo-aconitase. Until now, no clear data have been available on which is the system that reduces the mitoNEET clusters back once oxidative stress is not present anymore. In the present work, we used UV-vis and NMR spectroscopies to investigate the electron transfer process between mitoNEET and the cytosolic electron-donor Ndor1/anamorsin complex, a component of the cytosolic iron-sulfur protein assembly (CIA) machinery. The [2Fe-2S] clusters of mitoNEET are reduced via the formation of a transient complex that brings the [2Fe-2S] clusters of mitoNEET close to the redox-active [2Fe-2S] cluster of anamorsin. Our data provide in vitro evidence of a possible direct link between the CIA machinery and the mitoNEET cluster transfer repair pathway. This link might contribute to recovery of CIA machinery efficiency to mature cytosolic and nuclear Fe/S proteins.

Ferritin, cellular iron storage and regulation.

Ferritin is considered the major iron storage protein which maintains a large iron core in its cavity and has ferroxidase activity. There are many types of ferritin particularly in prokaryotes that include the canonical 24-mer FTN molecules, the heme-containing BFR, the smaller 12-mer DPS and the newly recognized EncFtn of encapsulin that forms a very large iron storage compartment. Recent studies show that ferritin function is more dynamic than previous depicted and new mechanisms of ferritin iron recycling are emerging. They participate to the regulation of cellular iron homeostasis as those of ferritin biosynthesis, cooperating also with the iron-dependent mechanism of cellular iron secretion. Some of these basic processes are in common between unicellular and animal cells, and this review aims at discussing the findings on the connections between iron storage, cellular iron regulation and ferritin iron recycling that have been explored in unicellular organisms and in animals. © 2017 IUBMB Life, 69(6):414-422, 2017.

ARTEMISININ MODULATING EFFECT ON HUMAN BREAST CANCER CELL LINES WITH DIFFERENT SENSITIVITY TO CYTOSTATICS

To explore effects of Artemisinin on a series of breast cancer cells with different sensitivity to typical cytotoxic drugs (doxorubicin - Dox; cisplatin - DDP) and to investigate possible artemisinin-induced modification of the mechanisms of drug resistance. The study was performed on wild-type breast cancer MCF-7 cell line (MCF-7/S) and its two sublines MCF-7/Dox and MCF-7/DDP resistant to Dox and DDP, respectively. The cells were treated with artemisinin and iron-containing magnetic fluid. The latter was added to modulate iron levels in the cells and explore its role in artemisinin-induced effects. The MTT assay was used to monitor cell viability, whereas changes of expression of selected proteins participating in regulation of cellular iron homeostasis were estimated using immunocytochemical methods. Finally, relative expression levels of miRNA-200b, -320a, and -34a were examined by using qRT-PCR. Artemisinin affects mechanisms of the resistance of breast cancer cells towards both Dox and DDP at sub-toxic doses. The former drug induces changes of expression of iron-regulating proteins via different mechanisms, including epigenetic regulation. Particularly, the disturbances in ferritin heavy chain 1, lactoferrin, hepcidin (decrease) and ferroportin (increase) expression (р ≤ 0.05) were established. The most enhanced increase of miRNA expression under artemisinin influence were found for miRNA-200b in MCF-7/DDP cells (7.1 ± 0.98 fold change), miRNA-320a in MCF-7/Dox cells (2.9 ± 0.45 fold change) and miRNA-34a (1.7 ± 0.15 fold change) in MCF-7/S cells. It was observed that the sensitivity to artemisinin can be influenced by changing iron levels in cells. Artemisinin can modify iron metabolism of breast cancer cells by its cytotoxic effect, but also by inducing changes in expression of iron-regulating proteins and microRNAs (miRNAs), involved in their regulation. This modification affects the mechanisms that are implicated in drug-resistance, that makes artemisinin a perspective modulator of cell sensitivity towards chemotherapeutic agents in cancer treatment.

Redox Control of the Human Iron-Sulfur Repair Protein MitoNEET Activity via Its Iron-Sulfur Cluster

Human mitoNEET (mNT) is the first identified Fe-S protein of the mammalian outer mitochondrial membrane. Recently, mNT has been implicated in cytosolic Fe-S repair of a key regulator of cellular iron homeostasis. Here, we aimed to decipher the mechanism by which mNT triggers its Fe-S repair capacity. By using tightly controlled reactions combined with complementary spectroscopic approaches, we have determined the differential roles played by both the redox state of the mNT cluster and dioxygen in cluster transfer and protein stability. We unambiguously demonstrated that only the oxidized state of the mNT cluster triggers cluster transfer to a generic acceptor protein and that dioxygen is neither required for the cluster transfer reaction nor does it affect the transfer rate. In the absence of apo-acceptors, a large fraction of the oxidized holo-mNT form is converted back to reduced holo-mNT under low oxygen tension. Reduced holo-mNT, which holds a [2Fe-2S](+)with a global protein fold similar to that of the oxidized form is, by contrast, resistant in losing its cluster or in transferring it. Our findings thus demonstrate that mNT uses an iron-based redox switch mechanism to regulate the transfer of its cluster. The oxidized state is the "active state," which reacts promptly to initiate Fe-S transfer independently of dioxygen, whereas the reduced state is a "dormant form." Finally, we propose that the redox-sensing function of mNT is a key component of the cellular adaptive response to help stress-sensitive Fe-S proteins recover from oxidative injury.

Iron Regulatory Protein 1 Suppresses Hypoxia-Induced Iron Uptake Proteins Expression and Decreases Iron Levels in HepG2 Cells.

Transferrin receptor (TfR1) and divalent metal transporter 1 (DMT1) are important proteins for cellular iron uptake, and both are regulated transcriptionally through the binding of hypoxia-inducible factor 1 (HIF-1) to hypoxia-responsive elements (HREs) under hypoxic conditions. These proteins are also regulated post-transcriptionally through the binding of iron regulatory protein 1 (IRP1) to iron-responsive elements (IREs) located in the mRNA untranslated region (UTR) to control cellular iron homeostasis. In iron-deficient cells, IRP1-IRE interactions stabilize TfR1 and DMT1 mRNAs, enhancing iron uptake. However, little is known about the impact of IRP1 on the regulation of cellular iron homeostasis under hypoxia. Thus, to investigate the role of IRP1 in hypoxic condition, overexpression and knockdown assays were performed using HepG2 cells. The overexpression of IRP1 suppressed the hypoxia-induced increase in TfR1 and DMT1 (+IRE) expression and reduced the stability of TfR1 and DMT1 (+IRE) mRNAs under hypoxia, whereas IRP1 knockdown further increased the hypoxia-induced expression of both proteins, preventing the decrease in IRE-dependent luciferase activity induced by hypoxia. Under hypoxic conditions, ferrous iron uptake, the labile iron pool (LIP), and total intracellular iron reduced when IRP1 was overexpressed and further increased when IRP1 was knocked down. IRP1 expression declined and TfR1/DMT1 (+IRE) expression increased with the time of hypoxia prolonged, whereas the binding of IRP1 to the IRE of TfR1/DMT1 mRNA maintained. In summary, IRP1 suppressed TfR1/DMT1 (+IRE) expression, limited the cellular iron content and decreased lactate dehydrogenase (LDH) release induced by hypoxia.

Compartmentalization of iron between mitochondria and the cytosol and its regulation

Iron is essential for life. Its coordinated distribution between intracellular compartments and the adaptation of iron uptake to intracellular demands are central for a balanced iron homeostasis. Mitochondria take center stage in cellular iron metabolism as they harbor the two major iron-utilizing pathways, the synthesis of heme and the biogenesis of iron–sulfur (Fe/S) proteins. Consistent with this central role, mitochondria are also critical regulators of cellular iron homeostasis. They directly influence cellular iron uptake and the status of iron-utilizing metabolic processes through iron-dependent co-factors or by control of gene expression. For all these aspects of cellular iron metabolism, the uptake of iron into mitochondria is critical. During the last decade, considerable progress has been made with respect to the functional characterization of mitochondrial iron acquisition and the identification of transporters involved. The model organism Saccharomyces cerevisiae has been especially useful for the elucidation of this process. Here, we summarize the recent advances in the mechanism of mitochondrial iron transport and the impact of mitochondria on the regulation of cellular iron homeostasis.

Catecholamine Stress Hormones Regulate Cellular Iron Homeostasis by a Posttranscriptional Mechanism Mediated by Iron Regulatory Protein: IMPLICATION IN ENERGY HOMEOSTASIS

Adequate availability of iron is important for cellular energy metabolism. Catecholamines such as epinephrine and norepinephrine promote energy expenditure to adapt to conditions that arose due to stress. To restore the energy balance, epinephrine/norepinephrine-exposed cells may face higher iron demand. So far, no direct role of epinephrine/norepinephrine in cellular iron homeostasis has been reported. Here we show that epinephrine/norepinephrine regulates iron homeostasis components such as transferrin receptor-1 and ferritin-H in hepatic and skeletal muscle cells by promoting the binding of iron regulatory proteins to iron-responsive elements present in the UTRs of transferrin receptor-1 and ferritin-H transcripts. Increased transferrin receptor-1, decreased ferritin-H, and increased iron-responsive element-iron regulatory protein interaction are also observed in liver and muscle tissues of epinephrine/norepinephrine-injected mice. We demonstrate the role of epinephrine/norepinephrine-induced generation of reactive oxygen species in converting cytosolic aconitase (ACO1) into iron regulatory protein-1 to bind iron-responsive elements present in UTRs of transferrin receptor-1 and ferritin-H. Our study further reveals that mitochondrial iron content and mitochondrial aconitase (ACO2) activity are elevated by epinephrine/norepinephrine that are blocked by the antioxidant N-acetyl cysteine and iron regulatory protein-1 siRNA, suggesting involvement of reactive oxygen species and iron regulatory protein-1 in this mechanism. This study reveals epinephrine and norepinephrine as novel regulators of cellular iron homeostasis.