The long history of iron in the Universe and in health and disease

NDRG1 acts as an oncogene in triple-negative breast cancer and its loss sensitizes cells to mitochondrial iron chelation

Multiple studies indicate that iron chelators enhance their anti-cancer properties by inducing NDRG1, a known tumor and metastasis suppressor. However, the exact role of NDRG1 remains controversial, as newer studies have shown that NDRG1 can also act as an oncogene. Our group recently introduced mitochondrially targeted iron chelators deferoxamine (mitoDFO) and deferasirox (mitoDFX) as effective anti-cancer agents. In this study, we evaluated the ability of these modified chelators to induce NDRG1 and the role of NDRG1 in breast cancer. We demonstrated that both compounds specifically increase NDRG1 without inducing other NDRG family members. We have documented that the effect of mitochondrially targeted chelators is at least partially mediated by GSK3α/β, leading to phosphorylation of NDRG1 at Thr346 and to a lesser extent on Ser330. Loss of NDRG1 increases cell death induced by mitoDFX. Notably, MDA-MB-231 cells lacking NDRG1 exhibit reduced extracellular acidification rate and grow slower than parental cells, while the opposite is true for ER+ MCF7 cells. Moreover, overexpression of full-length NDRG1 and the N-terminally truncated isoform (59112) significantly reduced sensitivity towards mitoDFX in ER+ cells. Furthermore, cells overexpressing full-length NDRG1 exhibited a significantly accelerated tumor formation, while its N-terminally truncated isoforms showed significantly impaired capacity to form tumors. Thus, overexpression of full-length NDRG1 promotes tumor growth in highly aggressive triple-negative breast cancer.

Copper, Iron, Cadmium, and Arsenic, All Generated in the Universe: Elucidating Their Environmental Impact Risk on Human Health Including Clinical Liver Injury

Humans are continuously exposed to various heavy metals including copper, iron, cadmium, and arsenic, which were specifically selected for the current analysis because they are among the most frequently encountered environmental mankind and industrial pollutants potentially causing human health hazards and liver injury. So far, these issues were poorly assessed and remained a matter of debate, also due to inconsistent results. The aim of the actual report is to thoroughly analyze the positive as well as negative effects of these four heavy metals on human health. Copper and iron are correctly viewed as pollutant elements essential for maintaining human health because they are part of important enzymes and metabolic pathways. Healthy individuals are prepared through various genetically based mechanisms to maintain cellular copper and iron homeostasis, thereby circumventing or reducing hazardous liver and organ injury due to excessive amounts of these metals continuously entering the human body. In a few humans with gene aberration, however, liver and organ injury may develop because excessively accumulated copper can lead to Wilson disease and substantial iron deposition to hemochromatosis. At the molecular level, toxicities of some heavy metals are traced back to the Haber Weiss and Fenton reactions involving reactive oxygen species formed in the course of oxidative stress. On the other hand, cellular homeostasis for cadmium and arsenic cannot be provided, causing their life-long excessive deposition in the liver and other organs. Consequently, cadmium and arsenic represent health hazards leading to higher disability-adjusted life years and increased mortality rates due to cancer and non-cancer diseases. For unknown reasons, however, liver injury in humans exposed to cadmium and arsenic is rarely observed. In sum, copper and iron are good for the human health of most individuals except for those with Wilson disease or hemochromatosis at risk of liver injury through radical formation, while cadmium and arsenic lack any beneficial effects but rather are potentially hazardous to human health with a focus on increased disability potential and risk for cancer. Primary efforts should focus on reducing the industrial emission of hazardous heavy metals.

Quantitative susceptibility mapping in the brain reflects spatial expression of genes involved in iron homeostasis and myelination

Quantitative susceptibility mapping (QSM) is an MRI modality used to non-invasively measure iron content in the brain. Iron exhibits a specific anatomically varying pattern of accumulation in the brain across individuals. The highest regions of accumulation are the deep grey nuclei, where iron is stored in paramagnetic molecule ferritin. This form of iron is considered to be what largely contributes to the signal measured by QSM in the deep grey nuclei. It is also known that QSM is affected by diamagnetic myelin contents. Here, we investigate spatial gene expression of iron and myelin related genes, as measured by the Allen Human Brain Atlas, in relation to QSM images of age-matched subjects. We performed multiple linear regressions between gene expression and the average QSM signal within 34 distinct deep grey nuclei regions. Our results show a positive correlation (p < .05, corrected) between expression of ferritin and the QSM signal in deep grey nuclei regions. We repeated the analysis for other genes that encode proteins thought to be involved in the transport and storage of iron in the brain, as well as myelination. In addition to ferritin, our findings demonstrate a positive correlation (p < .05, corrected) between the expression of ferroportin, transferrin, divalent metal transporter 1, several gene markers of myelinating oligodendrocytes, and the QSM signal in deep grey nuclei regions. Our results suggest that the QSM signal reflects both the storage and active transport of iron in the deep grey nuclei regions of the brain.

Iron mobilization from intact ferritin: effect of differential redox activity of quinone derivatives with NADH/O2 and in situ-generated ROS

Ferritins are multimeric nanocage proteins that sequester/concentrate excess of free iron and catalytically synthesize a hydrated ferric oxyhydroxide bio-mineral. Besides functioning as the primary intracellular iron storehouses, these supramolecular assemblies also oversee the controlled release of iron to meet physiologic demands. By virtue of the reducing nature of the cytosol, reductive dissolution of ferritin-iron bio-mineral by physiologic reducing agents might be a probable pathway operating in vivo. Herein, to explore this reductive iron-release pathway, a series of quinone analogs differing in size, position/nature of substituents and redox potentials were employed to relay electrons from physiologic reducing agent, NADH, to the ferritin core. Quinones are well known natural electron/proton mediators capable of facilitating both 1/2 electron transfer processes and have been implicated in iron/nutrient acquisition in plants and energy transduction. Our findings on the structure-reactivity of quinone mediators highlight that iron release from ferritin is dictated by electron-relay capability (dependent on E1/2 values) of quinones, their molecular structure (i.e., the presence of iron-chelation sites and the propensity for H-bonding) and the type/amount of reactive oxygen species (ROS) they generate in situ. Juglone/Plumbagin released maximum iron due to their intermediate E1/2 values, presence of iron chelation sites, the ability to inhibit in situ generation of H2O2 and form intramolecular H-bonding (possibly promotes semiquinone formation). This study may strengthen our understanding of the ferritin-iron-release process and their significance in bioenergetics/O2-based cellular metabolism/toxicity while providing insights on microbial/plant iron acquisition and the dynamic host-pathogen interactions.

Small-Molecule Fluorescent Probes for Binding- and Activity-Based Sensing of Redox-Active Biological Metals

Although transition metals constitute less than 0.1% of the total mass within a human body, they have a substantial impact on fundamental biological processes across all kingdoms of life. Indeed, these nutrients play crucial roles in the physiological functions of enzymes, with the redox properties of many of these metals being essential to their activity. At the same time, imbalances in transition metal pools can be detrimental to health. Modern analytical techniques are helping to illuminate the workings of metal homeostasis at a molecular and atomic level, their spatial localization in real time, and the implications of metal dysregulation in disease pathogenesis. Fluorescence microscopy has proven to be one of the most promising non-invasive methods for studying metal pools in biological samples. The accuracy and sensitivity of bioimaging experiments are predominantly determined by the fluorescent metal-responsive sensor, highlighting the importance of rational probe design for such measurements. This review covers activity- and binding-based fluorescent metal sensors that have been applied to cellular studies. We focus on the essential redox-active metals: iron, copper, manganese, cobalt, chromium, and nickel. We aim to encourage further targeted efforts in developing innovative approaches to understanding the biological chemistry of redox-active metals.

Elucidating Iron Metabolism through Molecular Imaging

Iron is essential for many physiological processes, and the dysregulation of its metabolism is implicated in the pathogenesis of various diseases. Recent advances in iron metabolism research have revealed multiple complex pathways critical for maintaining iron homeostasis. Molecular imaging, an interdisciplinary imaging technique, has shown considerable promise in advancing research on iron metabolism. Here, we comprehensively review the multifaceted roles of iron at the cellular and systemic levels (along with the complex regulatory mechanisms of iron metabolism), elucidate appropriate imaging methods, and summarize their utility and fundamental principles in diagnosing and treating diseases related to iron metabolism. Utilizing molecular imaging technology to deeply understand the complexities of iron metabolism and its critical role in physiological and pathological processes offers new possibilities for early disease diagnosis, treatment monitoring, and the development of novel therapies. Despite technological limitations and the need to ensure the biological relevance and clinical applicability of imaging results, molecular imaging technology's potential to reveal the iron metabolic process is unparalleled, providing new insights into the link between iron metabolism abnormalities and various diseases.

Quantitative susceptibility mapping for iron monitoring of multiple subcortical nuclei in type 2 diabetes mellitus: a systematic review and meta-analysis

Introduction

Iron accumulation in the brain has been linked to diabetes, but its role in subcortical structures involved in motor and cognitive functions remains unclear. Quantitative susceptibility mapping (QSM) allows the non-invasive quantification of iron deposition in the brain. This systematic review and meta-analysis examined magnetic susceptibility measured by QSM in the subcortical nuclei of patients with type 2 diabetes mellitus (T2DM) compared with controls.

Methods

PubMed, Scopus, and Web of Science databases were systematically searched [following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines] for studies reporting QSM values in the deep gray matter (DGM) regions of patients with T2DM and controls. Pooled standardized mean differences (SMDs) for susceptibility were calculated using fixed-effects meta-analysis models, and heterogeneity was assessed using I2. Sensitivity analyses were conducted, and publication bias was evaluated using Begg's and Egger's tests.

Results

Six studies including 192 patients with T2DM and 245 controls were included. This study found a significant increase in iron deposition in the subcortical nuclei of patients with T2DM compared to the control group. The study found moderate increases in the putamen (SMD = 0.53, 95% CI 0.33 to 0.72, p = 0.00) and dentate nucleus (SMD = 0.56, 95% CI 0.27 to 0.85, p = 0.00) but weak associations between increased iron levels in the caudate nucleus (SMD = 0.32, 95% CI 0.13 to 0.52, p = 0.00) and red nucleus (SMD = 0.22, 95% CI 0.00 0.44, p = 0.05). No statistical significance was found for iron deposition alterations in the globus pallidus (SMD = 0.19; 95% CI -0.01 to 0.38; p = 0.06) and substantia nigra (SMD = 0.12, 95% CI -0.10, 0.34, p = 0.29). Sensitivity analysis showed that the findings remained unaffected by individual studies, and consistent increases were observed in multiple subcortical areas.

Discussion

QSM revealed an increase in iron in the DGM/subcortical nuclei in T2DM patients versus controls, particularly in the motor and cognitive nuclei, including the putamen, dentate nucleus, caudate nucleus, and red nucleus. Thus, QSM may serve as a potential biomarker for iron accumulation in T2DM patients. However, further research is needed to validate these findings.

Mitigating pathogenesis for target discovery and disease subtyping

Treatments ideally mitigate pathogenesis, or the detrimental effects of the root causes of disease. However, existing definitions of treatment effect fail to account for pathogenic mechanism. We therefore introduce the Treated Root causal Effects (TRE) metric which measures the ability of a treatment to modify root causal effects. We leverage TREs to automatically identify treatment targets and cluster patients who respond similarly to treatment. The proposed algorithm learns a partially linear causal model to extract the root causal effects of each variable and then estimates TREs for target discovery and downstream subtyping. We maintain interpretability even without assuming an invertible structural equation model. Experiments across a range of datasets corroborate the generality of the proposed approach.

Impact of micronutrients and nutraceuticals on cognitive function and performance in Alzheimer's disease

Alzheimer's disease (AD) is a major global health problem today and is the most common form of dementia. AD is characterized by the formation of β-amyloid (Aβ) plaques and neurofibrillary clusters, leading to decreased brain acetylcholine levels in the brain. Another mechanism underlying the pathogenesis of AD is the abnormal phosphorylation of tau protein that accumulates at the level of neurofibrillary aggregates, and the areas most affected by this pathological process are usually the cholinergic neurons in cortical, subcortical, and hippocampal areas. These effects result in decreased cognitive function, brain atrophy, and neuronal death. Malnutrition and weight loss are the most frequent manifestations of AD, and these are also associated with greater cognitive decline. Several studies have confirmed that a balanced low-calorie diet and proper nutritional intake may be considered important factors in counteracting or slowing the progression of AD, whereas a high-fat or hypercholesterolemic diet predisposes to an increased risk of developing AD. Especially, fruits, vegetables, antioxidants, vitamins, polyunsaturated fatty acids, and micronutrients supplementation exert positive effects on aging-related changes in the brain due to their antioxidant, anti-inflammatory, and radical scavenging properties. The purpose of this review is to summarize some possible nutritional factors that may contribute to the progression or prevention of AD, understand the role that nutrition plays in the formation of Aβ plaques typical of this neurodegenerative disease, to identify some potential therapeutic strategies that may involve some natural compounds, in delaying the progression of the disease.

Hemochromatosis: Ferroptosis, ROS, Gut Microbiome, and Clinical Challenges with Alcohol as Confounding Variable

Hemochromatosis represents clinically one of the most important genetic storage diseases of the liver caused by iron overload, which is to be differentiated from hepatic iron overload due to excessive iron release from erythrocytes in patients with genetic hemolytic disorders. This disorder is under recent mechanistic discussion regarding ferroptosis, reactive oxygen species (ROS), the gut microbiome, and alcohol abuse as a risk factor, which are all topics of this review article. Triggered by released intracellular free iron from ferritin via the autophagic process of ferritinophagy, ferroptosis is involved in hemochromatosis as a specific form of iron-dependent regulated cell death. This develops in the course of mitochondrial injury associated with additional iron accumulation, followed by excessive production of ROS and lipid peroxidation. A low fecal iron content during therapeutic iron depletion reduces colonic inflammation and oxidative stress. In clinical terms, iron is an essential trace element required for human health. Humans cannot synthesize iron and must take it up from iron-containing foods and beverages. Under physiological conditions, healthy individuals allow for iron homeostasis by restricting the extent of intestinal iron depending on realistic demand, avoiding uptake of iron in excess. For this condition, the human body has no chance to adequately compensate through removal. In patients with hemochromatosis, the molecular finetuning of intestinal iron uptake is set off due to mutations in the high-FE2+ (HFE) genes that lead to a lack of hepcidin or resistance on the part of ferroportin to hepcidin binding. This is the major mechanism for the increased iron stores in the body. Hepcidin is a liver-derived peptide, which impairs the release of iron from enterocytes and macrophages by interacting with ferroportin. As a result, iron accumulates in various organs including the liver, which is severely injured and causes the clinically important hemochromatosis. This diagnosis is difficult to establish due to uncharacteristic features. Among these are asthenia, joint pain, arthritis, chondrocalcinosis, diabetes mellitus, hypopituitarism, hypogonadotropic hypogonadism, and cardiopathy. Diagnosis is initially suspected by increased serum levels of ferritin, a non-specific parameter also elevated in inflammatory diseases that must be excluded to be on the safer diagnostic side. Diagnosis is facilitated if ferritin is combined with elevated fasting transferrin saturation, genetic testing, and family screening. Various diagnostic attempts were published as algorithms. However, none of these were based on evidence or quantitative results derived from scored key features as opposed to other known complex diseases. Among these are autoimmune hepatitis (AIH) or drug-induced liver injury (DILI). For both diseases, the scored diagnostic algorithms are used in line with artificial intelligence (AI) principles to ascertain the diagnosis. The first-line therapy of hemochromatosis involves regular and life-long phlebotomy to remove iron from the blood, which improves the prognosis and may prevent the development of end-stage liver disease such as cirrhosis and hepatocellular carcinoma. Liver transplantation is rarely performed, confined to acute liver failure. In conclusion, ferroptosis, ROS, the gut microbiome, and concomitant alcohol abuse play a major contributing role in the development and clinical course of genetic hemochromatosis, which requires early diagnosis and therapy initiation through phlebotomy as a first-line treatment.

The Role of Iron Overload in Diabetic Cognitive Impairment: A Review

It is well documented that diabetes mellitus (DM) is strongly associated with cognitive decline and structural damage to the brain. Cognitive deficits appear early in DM and continue to worsen as the disease progresses, possibly due to different underlying mechanisms. Normal iron metabolism is necessary to maintain normal physiological functions of the brain, but iron deposition is one of the causes of some neurodegenerative diseases. Increasing evidence shows that iron overload not only increases the risk of DM, but also contributes to the development of cognitive impairment. The current review highlights the role of iron overload in diabetic cognitive impairment (DCI), including the specific location and regulation mechanism of iron deposition in the diabetic brain, the factors that trigger iron deposition, and the consequences of iron deposition. Finally, we also discuss possible therapies to improve DCI and brain iron deposition.

Iron regulatory proteins: players or pawns in ferroptosis and cancer?

Cells require iron for essential functions like energy production and signaling. However, iron can also engage in free radical formation and promote cell proliferation thereby contributing to both tumor initiation and growth. Thus, the amount of iron within the body and in individual cells is tightly regulated. At the cellular level, iron homeostasis is maintained post-transcriptionally by iron regulatory proteins (IRPs). Ferroptosis is an iron-dependent form of programmed cell death with vast chemotherapeutic potential, yet while IRP-dependent targets have established roles in ferroptosis, our understanding of the contributions of IRPs themselves is still in its infancy. In this review, we present the growing circumstantial evidence suggesting that IRPs play critical roles in the adaptive response to ferroptosis and ferroptotic cell death and describe how this knowledge can be leveraged to target neoplastic iron dysregulation more effectively.

Yeast Mitochondria Import Aqueous FeII and, When Activated for Iron-Sulfur Cluster Assembly, Export or Release Low-Molecular-Mass Iron and Also Export Iron That Incorporates into Cytosolic Proteins

Iron-sulfur cluster (ISC) assembly occurs in both mitochondria and cytosol. Mitochondria are thought to export a low-molecular-mass (LMM) iron and/or sulfur species which is used as a substrate for cytosolic ISC assembly. This species, called X-S or (Fe-S)_int, has not been directly detected. Here, an assay was developed in which mitochondria were isolated from ⁵⁷Fe-enriched cells and incubated in various buffers. Thereafter, mitochondria were separated from the supernatant, and both fractions were investigated by ICP-MS-detected size exclusion liquid chromatography. Aqueous ⁵⁴Fe^II in the buffer declined upon exposure to intact ⁵⁷Fe-enriched mitochondria. Some ⁵⁴Fe was probably surface-absorbed but some was incorporated into mitochondrial iron-containing proteins when mitochondria were activated for ISC biosynthesis. When activated, mitochondria exported/released two LMM nonproteinaceous iron complexes. One species, which comigrated with an Fe-ATP complex, developed faster than the other Fe species, which also comigrated with phosphorus. Both were enriched in ⁵⁴Fe and ⁵⁷Fe, suggesting that the added ⁵⁴Fe entered a pre-existing pool of ⁵⁷Fe, which was also the source of the exported species. When ⁵⁴Fe-loaded ⁵⁷Fe-enriched mitochondria were mixed with isolated cytosol and activated, multiple cytosolic proteins became enriched with Fe. No incorporation was observed when ⁵⁴Fe was added directly to the cytosol in the absence of mitochondria. This suggests that a different Fe source in mitochondria, the one enriched mainly with ⁵⁷Fe, was used to export a species that was ultimately incorporated into cytosolic proteins. Iron from buffer was imported into mitochondria fastest, followed by mitochondrial ISC assembly, LMM iron export, and cytosolic ISC assembly.

Microbiota-assisted iron uptake promotes immune tolerance in the intestine

Iron deficiencies are the most common nonenteric syndromes observed in patients with inflammatory bowel disease, but little is known about their impacts on immune tolerance. Here we show that homeostasis of regulatory T cells in the intestine was dependent on high cellular iron levels, which were fostered by pentanoate, a short-chain fatty acid produced by intestinal microbiota. Iron deficiencies in Treg caused by the depletion of Transferrin receptor 1, a major iron transporter, result in the abrogation of Treg in the intestine and lethal autoimmune disease. Transferrin receptor 1 is required for differentiation of c-Maf⁺ Treg, major constituents of intestinal Treg. Mechanistically, iron enhances the translation of HIF-2α mRNA, and HIF-2α in turn induces c-Maf expression. Importantly, microbiota-produced pentanoate promotes iron uptake and Treg differentiation in the intestine. This subsequently restores immune tolerance and ameliorated iron deficiencies in mice with colitis. Our results thus reveal an association between nutrient uptake and immune tolerance in the intestine.

The transcription factor POPEYE negatively regulates the expression of bHLH Ib genes to maintain iron homeostasis

Iron (Fe) is an essential trace element for plants. When suffering from Fe deficiency, plants modulate the expression of Fe deficiency-responsive genes to promote Fe uptake. POPEYE (PYE) is a key bHLH (basic helix-loop-helix) transcription factor involved in Fe homeostasis. However, the molecular mechanism of PYE regulating the Fe deficiency response remains elusive in Arabidopsis. We found that the overexpression of PYE attenuates the expression of Fe deficiency-responsive genes. PYE directly represses the transcription of bHLH Ib genes (bHLH38, bHLH39, bHLH100, and bHLH101) by associating with their promoters. Although PYE contains an ethylene response factor-associated amphiphilic repression (EAR) motif, it does not interact with the transcriptional co-repressors TOPLESS/TOPLESS-RELATED (TPL/TPRs). Sub-cellular localization analysis indicated that PYE localizes in both the cytoplasm and nucleus. PYE contains a nuclear export signal (NES) which is required for the cytoplasmic localization of PYE. Mutation of the NES amplifies the repression function of PYE, resulting in down-regulation of Fe deficiency-responsive genes. Co-expression assays indicated that three bHLH IVc members (bHLH104, bHLH105/ILR3, and bHLH115) facilitate the nuclear accumulation of PYE. Conversely, PYE indirectly represses the transcription activation ability of bHLH IVc. Additionally, PYE directly negatively regulates its own transcription. This study provides new insights into the Fe deficiency response signalling pathway and enhances the understanding of PYE functions in Arabidopsis.

Ferritin as a potential disease marker in patients with bipolar disorder

BACKGROUND

Low-grade inflammation and oxidative stress have been implicated as potential pathophysiological processes in bipolar disorder, but the underlying mechanism is unknown. Ferritin is a marker of iron stores and involved in redox processes and inflammation but its role in bipolar disorder is unclear.

METHODS

We investigated the possible association of increased plasma ferritin levels and bipolar disorder. We pooled two studies using similar longitudinal repeated measures designs and included 330 blood- and urinary samples from 95 patients with bipolar disorder across all affective states and 84 samples from 84 healthy control individuals. Plasma ferritin was measured along with multiple blood inflammatory markers and urinary markers of oxidatively generated damage to DNA and RNA.

RESULTS

Plasma ferritin levels, adjusting for multiple demographical- and lifestyle variables, did not differ between patients with bipolar disorder compared with healthy control individuals (b = 1.09, 95 % CI: 0.86 to 1.39, p = 0.49). Within patients with bipolar disorder ferritin levels were higher in a depressed state compared with euthymia (b = 1.12, 95 % CI: 1.01 to 1.24, p < 0.04), and ferritin levels were positively associated with Interleukin-18 blood levels and urinary levels of 8-oxodG.

LIMITATIONS

Patients with bipolar disorder received medication which could potentially influence iron metabolism.

CONCLUSION

Elevated ferritin levels in depressed patients with bipolar disorder may point to a role for iron metabolism in bipolar disorder pathophysiology, and potentially as a biomarker, linking low-grade inflammation with redox biology and the well-known increased risk of medical comorbidity and reduced life expectancy.

Association between susceptibility value and cerebral blood flow in the bilateral putamen in patients undergoing hemodialysis

Hemodialysis (HD) is the most regularly applied replacement therapy for end-stage renal disease, but it may result in brain injuries. The correlation between cerebral blood flow (CBF) alteration and iron deposition has not been investigated in patients undergoing HD. Ferritin level may be a dominant factor in CBF and iron deposition change. We hypothesize that ferritin level might be the key mediator between iron deposition and CBF alteration. The correlation in the putamen was estimated between the susceptibility values and CBF in patients undergoing HD. Compared with healthy controls, patients showed more altered global susceptibility values and CBF. The susceptibility value was negatively correlated with CBF in the putamen in patients. Moreover, the susceptibility value was negatively correlated with ferritin level and positively correlated with serum iron level in the putamen of patients. CBF was positively correlated with ferritin level and negatively correlated with serum iron level in the putamen of patients. These findings indicate that iron dyshomeostasis and vascular damage might exist in the putamen in patients. The results revealed that iron dyshomeostasis and vascular damage in the putamen may be potential neural mechanisms for neurodegenerative processes in patients undergoing HD.

Conformational multiplicity of bacterial ferric binding protein revealed by small angle x-ray scattering and molecular dynamics calculations

This study combines molecular dynamics (MD) simulations with small angle x-ray scattering (SAXS) measurements to investigate the range of conformations that can be adopted by a pH/ionic strength (IS) sensitive protein and to quantify its distinct populations in solution. To explore how the conformational distribution of proteins may be modified in the environmental niches of biological media, we focus on the periplasmic ferric binding protein A (FbpA) from Haemophilus influenzae involved in the mechanism by which bacteria capture iron from higher organisms. We examine iron-binding/release mechanisms of FbpA in varying conditions simulating its biological environment. While we show that these changes fall within the detectable range for SAXS as evidenced by differences observed in the theoretical scattering patterns calculated from the crystal structure models of apo and holo forms, detection of conformational changes due to the point mutation D52A and changes in ionic strength (IS) from SAXS scattering profiles have been challenging. Here, to reach conclusions, statistical analyses with SAXS profiles and results from different techniques were combined in a complementary fashion. The SAXS data complemented by size exclusion chromatography point to multiple and/or alternative conformations at physiological IS, whereas they are well-explained by single crystallographic structures in low IS buffers. By fitting the SAXS data with unique conformations sampled by a series of MD simulations under conditions mimicking the buffers, we quantify the populations of the occupied substates. We also find that the D52A mutant that we predicted by coarse-grained computational modeling to allosterically control the iron binding site in FbpA, responds to the environmental changes in our experiments with conformational selection scenarios that differ from those of the wild type.

Effects of Iron-Peptides Chelate Nanoliposomes on Iron Supplementation in Rats

The objective of this study was to investigate the effects of iron nanoliposomes on iron supplementation and toxicity in SD rats induced by a low-iron diet. The size and infrared spectroscopy of a liposomal oral delivery system were investigated. The particle size of nanoliposomes embedded with chelates was increased. Infrared spectra proved that peptides-iron and blank nanoliposomes were bonded by interaction forces, including the fracture of hydrogen bonds, C = C bonds, hydrophobic interaction, and C-N bonds. We found that iron supplementation chelates had a certain protective effect on viscera after being embedded by nanoliposomes. After 10 days of treatment, the concentration of hemoglobin could be gradually increased. Nanoliposome encapsulated peptides-iron has a better effect than other groups. At the same time, SOD, MDA, and CAT reached normal levels after 20 days. Histological results showed that the sections of the nanoliposomes groups were clearer than those of the other groups. There was a little inflammation in the liver without obvious pathological changes, which also proved that the iron chelates embedded by nanoliposomes had no obvious side effects on iron supplementation in rats. Nanoliposome encapsulated peptides-iron has a small side effect and a significant curative effect of iron supplementation. It maybe has a good application prospect in the clinical medical field.

Iron metabolism and cardiovascular disease: Basic to translational purviews and therapeutical approach

Iron interactions with the cardiovascular system were proposed about half a century ago, yet a clear-cut understanding of this micronutrient and its intricacies with acute and chronic events is still lacking. In chronic heart failure, patients with decreased iron stores appear to benefit from intravenous administration of metallic formulations, whereas acute diseases (e.g., myocardial infarction, stroke) are barely studied in randomized controlled trials in humans. However, proof-of-concept studies have indicated that the dual redox characteristics of iron could be involved in atherosclerosis, necrosis, and ferroptosis. To this end, we sought to review the currently available body of literature pertaining to these temporal profiles of heart diseases, as well as the pathophysiologic mechanism by which iron enacts, underlining key points related to treatment options.

Emerging roles of ferroptosis in infectious diseases

In living organisms, lipid peroxidation is a continuously occurring cellular process and therefore involved in various physiological and pathological contexts. Among the broad variety of lipids, polyunsaturated fatty acids (PUFA) constitute a major target of oxygenation either when released as mediators by phospholipases or when present in membranous phospholipids. The last decade has seen the characterization of an iron- and lipid peroxidation-dependent cell necrosis, namely, ferroptosis, that involves the accumulation of peroxidized PUFA-containing phospholipids. Further studies could link ferroptosis in a very large body of (physio)-pathological processes, including cancer, neurodegenerative, and metabolic diseases. In this review, we mostly focus on the emerging involvement of lipid peroxidation-driven ferroptosis in infectious diseases, and the immune consequences. We also discuss the putative ability of microbial virulence factors to exploit or to dampen ferroptosis regulatory pathways to their own benefit.

Enantioselective Imine Reduction of Dihydro-β-carbolines by Fe-Thiosquaramide Catalyst

Enantioselective imine reduction of dihydro-β-carbolines (DHBCs) is a reliable and powerful tool to construct bioactive chiral tetrahydro-β-carbolines (THBCs). Here, we report an efficient enantioselective imine reduction employing in situ generated Fe-thiosquaramides (Fe-TSQs) 3a and 3b as asymmetric organometallic catalysts to produce chiral THBCs (2a-h). The catalyst 3a at 15 mol % was found to be suitable for the substrates with alkyl and aryl groups which afford corresponding chiral THBCs with excellent enantioselectivities (up to ee 99%).

Current Use of Fenton Reaction in Drugs and Food

Iron is the most abundant mineral in the human body and plays essential roles in sustaining life, such as the transport of oxygen to systemic organs. The Fenton reaction is the reaction between iron and hydrogen peroxide, generating hydroxyl radical, which is highly reactive and highly toxic to living cells. “Ferroptosis”, a programmed cell death in which the Fenton reaction is closely involved, has recently received much attention. Furthermore, various applications of the Fenton reaction have been reported in the medical and nutritional fields, such as cancer treatment or sterilization. Here, this review summarizes the recent growing interest in the usefulness of iron and its biological relevance through basic and practical information of the Fenton reaction and recent reports.

Hybrid antigens expressing surface loops of BauA from Acinetobacter baumannii are capable of inducing protection against infection

Acinetobacter baumannii is a human bacterial pathogen of increasing concern in clinical settings due to the emergence of antibiotic resistant strains and the lack of effective therapeutics. Researchers have been exploring new treatment options such as novel drug candidates and vaccines to prevent severe infections and mortality. Bacterial surface antigens that are essential to A. baumannii for acquiring micronutrients (e.g. iron, zinc) from nutrient restricted environments are being considered as targets for vaccines or immunotherapy due to their crucial role for growth and pathogenesis in the human host. BauA, the outer membrane receptor for the siderophore acinetobactin was targeted for vaccine development in this study. Due to challenges in the commercial production of membrane proteins for vaccines, a novel hybrid antigen method developed by our group was used. Exposed loops of BauA were selected and displayed on a foreign scaffold to generate novel hybrid antigens designed to elicit an immune response against the native BauA protein. The potential epitopes were incorporated into a scaffold derived from the C-lobe of Neisseria meningitidis transferrin binding protein B (TbpB), named the loopless C-lobe (LCL). Hybrid proteins displaying three selected loops (5, 7 and 8) individually or in combination were designed and produced and evaluated in an A. baumannii murine sepsis model as vaccine antigens. Immunization with the recombinant BauA protein protected 100% of the mice while immunization with hybrid antigens displaying individual loops achieved between 50 and 100% protection. The LCL scaffold did not induce a protective immune response, enabling us to attribute the observed protection elicited by the hybrid antigens to the displayed loops. Notably, the mice immunized with the hybrid antigen displaying loop 7 were completely protected from infection. Taken together, these results suggest that our hybrid antigen approach is a viable method for generating novel vaccine antigens that target membrane surface proteins necessary for bacterial growth and pathogenesis and the loop 7 hybrid antigen can be a foundation for approaches to combat A. baumannii infections.

Ferroptosis in COVID-19-related liver injury: A potential mechanism and therapeutic target

The outbreak and worldwide spread of coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been a threat to global public health. SARS-CoV-2 infection not only impacts the respiratory system but also causes hepatic injury. Ferroptosis, a distinct iron-dependent form of non-apoptotic cell death, has been investigated in various pathological conditions, such as cancer, ischemia/reperfusion injury, and liver diseases. However, whether ferroptosis takes part in the pathophysiological process of COVID-19-related liver injury has not been evaluated yet. This review highlights the pathological changes in COVID-19-related liver injury and presents ferroptosis as a potential mechanism in the pathological process. Ferroptosis, as a therapeutic target for COVID-19-related liver injury, is also discussed. Discoveries in these areas will improve our understanding of strategies to prevent and treat hepatic injuries caused by COVID-19.

Assessment of humoral immunity and nutritionally essential trace elements in steady-state sickle cell disease Nigerian children before and after Prevenar 13 pneumococcal vaccination

Children with sickle cell disease (SCD) are particularly prone to pneumococcal infection and administration of Prevenar 13 pneumococcal vaccine in Nigerian children with SCD is yet to be wide spread. This call for the need to study humoral immune responses stimulated by Prevenar 13 pneumococcal vaccine in SCD children to confirm the benefit or otherwise for the use of Prevenar 13 pneumococcal vaccine.

Method

The levels of humoral (innate and adaptive) immune factors and associated nutritionally essential trace elements were determined following Prevenar 13 pneumococcal vaccination of 23 Nigerian children with SCD. Serum innate humoral immune factors [Complement factors (C1q and C4), transferrin, ferritin, and C-reactive protein (CRP)] and adaptive humoral immune factors [IgG, IgA, IgM, and IgE] were determined using ELISA. Nutritionally essential trace elements such as iron (Fe), copper (Cu), and zinc (Zn) were measured also using an atomic absorption spectrophotometer.

Results

The serum levels of certain innate humoral immune factors (ferritin, CRP, and C4), only one adaptive humoral immune factors (IgE), and essential trace elements (Fe, Zn, and Cu) were significantly elevated in children with SCD post Prevenar 13 pneumococcal vaccination when compared to prevaccination levels.

Conclusion

Vaccination of children with SCD with Prevenar 13 pneumococcal vaccine was associated with increased levels of more innate humoral immune factors than adaptive factors. This study thus supports the administration of Prevenar 13 pneumococcal vaccination to children with SCD.

Iron overload and neurodegenerative diseases: What can we learn from Caenorhabditis elegans?

Iron (Fe) is an essential trace element required for several physiological processes. It plays important roles in mitochondrial function, synthesis, and metabolism of the neurotransmitter, as well as oxygen transport. However, excess Fe can cause toxicity. Particularly, Fe overload may result in neurotoxicity, contributing to the development and progression of neurodegenerative diseases, although the molecular mechanisms underlying Fe-induced neurodegeneration have yet to be entirely understood. Alternative (non-rodent) experimental models have been pointed as important approaches to elucidate molecular and physiological events mediating Fe-induced pathology. Among such alternative strategies, an advantageous experimental worm-model system, Caenorhabditis elegans ( C. elegans), has been used to investigate Fe-induced neurotoxicity and neurodegenerative disorders. Its genome has been fully sequenced, corroborating that it shares significant homology with mammalians, and has approximately 40% of human disease-related genes. As part of this review, we discuss studies using the C. elegans model to study molecular mechanisms such as oxidative stress, mitochondrial dysfunction, disturbed homeostasis, and its potential contribution to the study of metal-induced neurodegenerative diseases such as Parkinson’s disease (PD) and Alzheimer’s disease (AD).

Iron Dyshomeostasis and Ferroptosis: A New Alzheimer’s Disease Hypothesis?

Iron plays a crucial role in many physiological processes of the human body, but iron is continuously deposited in the brain as we age. Early studies found iron overload is directly proportional to cognitive decline in Alzheimer’s disease (AD). Amyloid precursor protein (APP) and tau protein, both of which are related to the AD pathogenesis, are associated with brain iron metabolism. A variety of iron metabolism-related proteins have been found to be abnormally expressed in the brains of AD patients and mouse models, resulting in iron deposition and promoting AD progression. Amyloid β (Aβ) and hyperphosphorylated tau, two pathological hallmarks of AD, can also promote iron deposition in the brain, forming a vicious cycle of AD development-iron deposition. Iron deposition and the subsequent ferroptosis has been found to be a potential mechanism underlying neuronal loss in many neurodegenerative diseases. Iron chelators, antioxidants and hepcidin were found useful for treating AD, which represents an important direction for AD treatment research and drug development in the future. The review explored the deep connection between iron dysregulation and AD pathogenesis, discussed the potential of new hypothesis related to iron dyshomeostasis and ferroptosis, and summarized the therapeutics capable of targeting iron, with the expectation to draw more attention of iron dysregulation and corresponding drug development.

Temporal variation of planetary iron as a driver of evolution

Iron is an irreplaceable component of proteins and enzyme systems required for life. This need for iron is a well-characterized evolutionary mechanism for genetic selection. However, there is limited consideration of how iron bioavailability, initially determined by planetary accretion but fluctuating considerably at global scale over geological time frames, has shaped the biosphere. We describe influences of iron on planetary habitability from formation events >4 Gya and initiation of biochemistry from geochemistry through oxygenation of the atmosphere to current host–pathogen dynamics. By determining the iron and transition element distribution within the terrestrial planets, planetary core formation is a constraint on both the crustal composition and the longevity of surface water, hence a planet’s habitability. As such, stellar compositions, combined with metallic core-mass fraction, may be an observable characteristic of exoplanets that relates to their ability to support life. On Earth, the stepwise rise of atmospheric oxygen effectively removed gigatons of soluble ferrous iron from habitats, generating evolutionary pressures. Phagocytic, infectious, and symbiotic behaviors, dating from around the Great Oxygenation Event, refocused iron acquisition onto biotic sources, while eukaryotic multicellularity allows iron recycling within an organism. These developments allow life to more efficiently utilize a scarce but vital nutrient. Initiation of terrestrial life benefitted from the biochemical properties of abundant mantle/crustal iron, but the subsequent loss of iron bioavailability may have been an equally important driver of compensatory diversity. This latter concept may have relevance for the predicted future increase in iron deficiency across the food chain caused by elevated atmospheric CO₂.

Heme Oxygenase-1 (HMOX-1) and inhibitor of differentiation proteins (ID1, ID3) are key response mechanisms against iron-overload in pancreatic β-cells

Iron overload promotes the generation of reactive oxygen species (ROS). Pancreatic β-cells can counter oxidative stress through multiple anti-oxidant responses. Herein, RNA-sequencing was used to describe the expression profile of iron regulatory genes in human islets with or without diabetes. Functional experiments including siRNA silencing, qPCR, western blotting, cell viability, ELISA and RNA-sequencing were performed as means of identifying the genetic signature of the protective response following iron overload-induced stress in human islets and INS-1. FTH1 and FTL genes were highly expressed in human islets and INS-1 cells, while hepcidin (HAMP) was low. FXN, DMT1 and FTHL1 genes were differentially expressed in diabetic islets compared to control. Silencing of Hamp in INS-1 cells impaired insulin secretion and influenced the expression of β-cell key genes. RNA-sequencing analysis in iron overloaded INS-1 cells identified Id1 and Id3 as the top down-regulated genes, while Hmox1 was the top upregulated. Expression of ID1, ID3 and HMOX1 was validated at the protein level in INS-1 cells and human islets. Differentially expressed genes (DEGs) were enriched for TGF-β, regulating stem cells, ferroptosis, and HIF-1 signaling. Hmox1-silenced cells treated with FAC elevated the expression of Id1 and Id3 expression than untreated cells. Our findings suggest that HMOX1, ID1 and ID3 define the response mechanism against iron-overload-induced stress in β-cells.

Pre-Clinical Insights into the Iron and Breast Cancer Hypothesis

Population studies, systematic reviews, and meta-analyses have revealed no relationship between iron status and breast cancer, a weak positive association, or a small protective effect of low iron status. However, in those studies, the authors concluded that further investigation was merited. The set of experiments reported here used preclinical models to assess the likely value of further investigation. The effects of iron status on the initiation and promotion stage of mammary carcinogenesis are reported. Using the classical model of cancer initiation in the mammary gland, 7,12 dimethyl-benz[α]anthracene-induced carcinogenesis was unaffected by iron status. Similarly, excess iron intake showed no effect on the promotion stage of 1-methyl-1-nitrosurea-induced mammary carcinogenesis, though iron deficiency exerted a specific inhibitory effect on the carcinogenic process. Though iron-mediated cellular oxidation is frequently cited as a potential mechanism for effects on breast cancer, no evidence of increased oxidative damage to DNA attributable to excess iron intake was found. The reported preclinical data fail to provide convincing evidence that the further evaluation of the iron–breast cancer risk hypotheses is warranted and underscore the value of redefining the referent group in population-based studies of iron–cancer hypotheses in other tissues.

Iron Metabolism in Pancreatic Beta-Cell Function and Dysfunction

Iron is an essential element involved in a variety of physiological functions. In the pancreatic beta-cells, being part of Fe-S cluster proteins, it is necessary for the correct insulin synthesis and processing. In the mitochondria, as a component of the respiratory chain, it allows the production of ATP and reactive oxygen species (ROS) that trigger beta-cell depolarization and potentiate the calcium-dependent insulin release. Iron cellular content must be finely tuned to ensure the normal supply but also to prevent overloading. Indeed, due to the high reactivity with oxygen and the formation of free radicals, iron excess may cause oxidative damage of cells that are extremely vulnerable to this condition because the normal elevated ROS production and the paucity in antioxidant enzyme activities. The aim of the present review is to provide insights into the mechanisms responsible for iron homeostasis in beta-cells, describing how alteration of these processes has been related to beta-cell damage and failure. Defects in iron-storing or -chaperoning proteins have been detected in diabetic conditions; therefore, the control of iron metabolism in these cells deserves further investigation as a promising target for the development of new disease treatments.

Vitamin D decreases pancreatic iron overload in type 2 diabetes through the NF-κB-DMT1 pathway

Emerging evidence has deemed vitamin D as a potential candidate for the intervention of type 2 diabetes (T2D). Herein, we explored the underlying mechanisms of T2D prevention by vitamin D, concentrating on pancreatic iron deposition reported recently. Zucker diabetic fatty (ZDF) rats were treated by vitamin D, with age-matched Zucker lean rats as control. As expected, vitamin D treatment for ZDF rats normalized islet morphology and β-cell function. Moreover, vitamin D alleviated iron accumulation and apoptosis in pancreatic cells of ZDF rats, accompanied by lowered divalent metal transporter 1 (DMT1) expression. Consistently, similar results were observed in high glucose-stimulated INS-1 cells treated with or without vitamin D. Nuclear factor-κB (NF-κB), a transcription factor involving DMT1 regulation, was activated in pancreases of ZDF rats and INS-1 cells exposed to high glucose, but inactivated by vitamin D or BAY 11-7082, a NF-κB inhibitor. Futhermore, IL-1β functioning as NF-κB activator abolished the suppression of NF-κB activation, DMT1 induction and the attenuation of apoptosis as a consequence of vitamin D incubation. Our study showed that iron overload in pancreas may contribute to T2D pathogenesis and uncovered a potentially protective role for vitamin D on iron deposition of diabetic pancreas through NF-κB- DMT1 signaling.

Regulation of Ferroptosis Pathway by Ubiquitination

Ferroptosis is an iron-dependent form of programmed cell death, which plays crucial roles in tumorigenesis, ischemia–reperfusion injury and various human degenerative diseases. Ferroptosis is characterized by aberrant iron and lipid metabolisms. Mechanistically, excess of catalytic iron is capable of triggering lipid peroxidation followed by Fenton reaction to induce ferroptosis. The induction of ferroptosis can be inhibited by sufficient glutathione (GSH) synthesis via system Xc^– transporter-mediated cystine uptake. Therefore, induction of ferroptosis by inhibition of cystine uptake or dampening of GSH synthesis has been considered as a novel strategy for cancer therapy, while reversal of ferroptotic effect is able to delay progression of diverse disorders, such as cardiopathy, steatohepatitis, and acute kidney injury. The ubiquitin (Ub)–proteasome pathway (UPP) dominates the majority of intracellular protein degradation by coupling Ub molecules to the lysine residues of protein substrate, which is subsequently recognized by the 26S proteasome for degradation. Ubiquitination is crucially involved in a variety of physiological and pathological processes. Modulation of ubiquitination system has been exhibited to be a potential strategy for cancer treatment. Currently, more and more emerged evidence has demonstrated that ubiquitous modification is involved in ferroptosis and dominates the vulnerability to ferroptosis in multiple types of cancer. In this review, we will summarize the current findings of ferroptosis surrounding the viewpoint of ubiquitination regulation. Furthermore, we also highlight the potential effect of ubiquitination modulation on the perspective of ferroptosis-targeted cancer therapy.

Effect of Erythropoietin on the Expression of Murine Transferrin Receptor 2

Erythropoietin (EPO) downregulates hepcidin expression to increase the availability of iron; the downregulation of hepcidin is mediated by erythroferrone (ERFE) secreted by erythroblasts. Erythroblasts also express transferrin receptor 2 (TFR2); however, the possible role of TFR2 in hepcidin downregulation is unclear. The purpose of the study was to correlate liver expression of hepcidin with the expression of ERFE and TFR2 in murine bone marrow and spleen at 4, 16, 24, 48, 72 and 96 h following administration of a single dose of EPO. Splenic Fam132b expression increased 4 h after EPO injection; liver hepcidin mRNA was decreased at 16 h. In the spleen, expression of TFR2 and transferrin receptor (TFR1) proteins increased by an order of magnitude at 48 and 72 h after EPO treatment. The EPO-induced increase in splenic TFR2 and TFR1 was associated with an increase in the number of Tfr2- and Tfr1-expressing erythroblasts. Plasma exosomes prepared from EPO-treated mice displayed increased amount of TFR1 protein; however, no exosomal TFR2 was detected. Overall, the results confirm the importance of ERFE in stress erythropoiesis, support the role of TFR2 in erythroid cell development, and highlight possible differences in the removal of TFR2 and TFR1 from erythroid cell membranes.

Iron metabolism in infections: Focus on COVID-19

Iron is a micronutrient essential for a wide range of metabolic processes in virtually all living organisms. During infections, a battle for iron takes place between the human host and the invading pathogens. The liver peptide hepcidin, which is phylogenetically and structurally linked to defensins (antimicrobial peptides of the innate immunity), plays a pivotal role by subtracting iron to pathogens through its sequestration into host cells, mainly macrophages. While this phenomenon is well studied in certain bacterial infections, much less is known regarding viral infections. Iron metabolism also has implications on the functionality of cells of the immune system. Once primed by the contact with antigen presenting cells, lymphocytes need iron to sustain the metabolic burst required for mounting an effective cellular and humoral response. The COVID-19 pandemic has boosted an amount of clinical and translational research over the possible influences of nutrients on SARS-CoV-2 infection, in terms of either susceptibility or clinical course. Here we review the intersections between iron metabolism and COVID-19, belonging to the wider domain of the so-called “nutritional immunity”. A better understanding of such connections has potential broad implications, either from a mechanistic standpoint, or for the development of more effective strategies for managing COVID-19 and possible future pandemics.

Serum Iron and Ferritin Levels Are Correlated with Complement C3

Iron is one of the most important trace elements in the body, and its homeostasis is essential to the normal function of the immune system. Complement component C3, which is the converging of three main pathways of complement system activation, plays a key role in the innate immunity. However, the relationship between iron homeostasis and complement C3 remains unknown. The aim of our study was to analyze the relationship between serum iron and ferritin level and complement C3 and C4. A total of 590 healthy individuals were recruited in our study. Higher serum complement C3 level (p < 0.001) was found in individuals with higher serum ferritin level (> 104.0 μg/L). Moreover, serum iron level and serum ferritin level were positively correlated with complement C3 (r = 0.133, p = 0.001; r = 0.221, p < 0.001) and complement C4 (r = 0.117, p = 0.004; r = 0.123, p = 0.003). The linear regression analysis displayed that both serum iron level and serum ferritin level were linearly correlated with serum complement C3 level (adjusted beta: 2.382, 95% CI: 0.841-3.923; adjusted beta: 42.911, 95% CI: 29.070-56.751). To explore the relationship between iron homeostasis and complement C3 further, the serum samples from C3^-/- mice and the wild-type (WT) control mice were obtained. Significantly lower serum iron level and higher ferritin level were found in C3^-/- mice than those in WT mice (p < 0.001; p < 0.001), indicating that complement C3 might influence iron distribution and utilization. Overall, these data suggested that serum iron and ferritin levels were correlated with complement C3. The deficiency of complement C3 may disrupt the regular iron metabolism in the body.

Iron-binding cellular profile of transferrin using label-free Raman hyperspectral imaging and singular value decomposition (SVD)

Serum transferrin (Tf) is the essential iron transport protein in the body. Transferrin is responsible for the sequestration of free iron in serum and the delivery of iron throughout the body and into cells, where iron is released inside a mildly acidified endosome. Altered iron distributions are associated with diseases such as iron-overload, cancer, and cardiovascular disease. The presence of free iron is linked to deleterious redox reactions, inside and outside cells and organelles. As Tf iron release is pH dependent, any changes in intraorganelle and extracellular pH, often associated with disease progression, could inhibit normal iron delivery or accelerate iron release in the wrong compartment. However, imaging approaches to monitor changes in the iron-bound state of Tf are lacking. Recently, Raman spectroscopy has been shown to measure iron-bound forms of Tf in solution, intact cells and tissue samples. Here, a biochemical Raman assay has been developed to identify iron-release from Tf following modification of chemical environment. Quantitative singular value decomposition (SVD) method has been applied to discriminate between iron-bound Tf samples during endocytic trafficking in intact cancer cells subjected to Raman hyperspectral confocal imaging. We demonstrate the strength of the SVD method to monitor pH-induced Tf iron-release using Raman hyperspectral imaging, providing the redox biology field with a novel tool that facilitates subcellular investigation of the iron-binding profile of transferrin in various disease models.

Targeting Mitochondrial Iron Metabolism Suppresses Tumor Growth and Metastasis by Inducing Mitochondrial Dysfunction and Mitophagy

Deferoxamine (DFO) represents a widely used iron chelator for the treatment of iron overload. Here we describe the use of mitochondrially targeted deferoxamine (mitoDFO) as a novel approach to preferentially target cancer cells. The agent showed marked cytostatic, cytotoxic, and migrastatic properties in vitro, and it significantly suppressed tumor growth and metastasis in vivo. The underlying molecular mechanisms included (i) impairment of iron-sulfur [Fe-S] cluster/heme biogenesis, leading to destabilization and loss of activity of [Fe-S] cluster/heme containing enzymes, (ii) inhibition of mitochondrial respiration leading to mitochondrial reactive oxygen species production, resulting in dysfunctional mitochondria with markedly reduced supercomplexes, and (iii) fragmentation of the mitochondrial network and induction of mitophagy. Mitochondrial targeting of deferoxamine represents a way to deprive cancer cells of biologically active iron, which is incompatible with their proliferation and invasion, without disrupting systemic iron metabolism. Our findings highlight the importance of mitochondrial iron metabolism for cancer cells and demonstrate repurposing deferoxamine into an effective anticancer drug via mitochondrial targeting. SIGNIFICANCE: These findings show that targeting the iron chelator deferoxamine to mitochondria impairs mitochondrial respiration and biogenesis of [Fe-S] clusters/heme in cancer cells, which suppresses proliferation and migration and induces cell death. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/9/2289/F1.large.jpg.

Flavin-mediated reductive iron mobilization from frog M and Mycobacterial ferritins: impact of their size, charge and reactivities with NADH/O2

In vitro, reductive mobilization of ferritin iron using suitable electron transfer mediators has emerged as a possible mechanism to mimic the iron release process, in vivo. Nature uses flavins as electron relay molecules for important biological oxidation and oxygenation reactions. Therefore, the current work utilizes three flavin analogues: riboflavin (RF), flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), which differ in size and charge but have similar redox potentials, to relay electron from nicotinamide adenine dinucleotide (NADH) to ferritin mineral core. Of these, the smallest/neutral analogue, RF, released more iron (~ three fold) in comparison to the larger and negatively charged FMN and FAD. Although iron mobilization got marred during the initial stages under aerobic conditions, but increased with a greater slope at the later stages of the reaction kinetics, which gets inhibited by superoxide dismutase, consistent with the generation of O₂^∙- in situ. The initial step, i.e., interaction of flavins with NADH played critical role in the iron release process. Overall, the flavin-mediated reductive iron mobilization from ferritins occurred via two competitive pathways, involving the reduced form of flavins either alone (anaerobic condition) or in combination with O₂^∙- intermediate (aerobic condition). Moreover, faster iron release was observed for ferritins from Mycobacterium tuberculosis than from bullfrog, indicating the importance of protein nanocage and the advantages they provide to the respective organisms. Therefore, these structure-reactivity studies of flavins with NADH/O₂ holds significance in ferritin iron release, bioenergetics, O₂-based cellular toxicity and may be potentially exploited in the treatment of methemoglobinemia. Smaller sized/neutral flavin analogue, riboflavin (RF) exhibits faster reactivity towards both NADH and O₂ generating more amount of O₂^∙- and releases higher amount of iron from different ferritins, compared to its larger sized/negatively charged derivatives such as FMN and FAD.

Ferroptosis in a sarcopenia model of senescence accelerated mouse prone 8 (SAMP8)

As a systemic syndrome characterized by age-associated degenerative skeletal muscle atrophy, sarcopenia leads to a risk of adverse outcomes in the elderly. Age-related iron accumulation is found in the muscles of sarcopenia animal models and patients, but the role of iron in sarcopenia remains poorly understood. It has been recently found that iron overload in several diseases is involved in ferroptosis, an iron- dependent form of programmed cell death. However, whether this excess iron can result in ferroptosis in muscles is still unclear. In our present study, we found that ferric citrate induced ferroptosis in C2C12 cells, as well as impaired their differentiation from myoblasts to myotubes. Due to the decreased muscle mass and fiber size, 40-week-old senescence accelerated mouse prone 8 (SAMP8) mice were used as a sarcopenia model, in whose muscles the iron content and markers of ferroptosis were found to increase, compared to 8-week- old SAMP8 controls. Moreover, our results showed that iron overload upregulated the expression of P53, which subsequently repressed the protein level of Slc7a11 (solute carrier family 7, member 11), a known ferroptosis-related gene. The downregulation of Slc7a11 then induced the ferroptosis of muscle cells through the accumulation of lipid peroxidation products, which may be one of the causes of sarcopenia. The findings in this study indicate that iron plays a key role in triggering P53- Slc7a11-mediated ferroptosis in muscles, and suggest that targeting iron accumulation and ferroptosis might be a therapeutic strategy for treating sarcopenia.

Metalloporphyrins in Medicine: From History to Recent Trends

The history of metalloporphyrins dates back more than 200 years ago. Metalloporphyrins are excellent catalysts, capable of forming supramolecular systems, participate in oxygen photosynthesis, transport, and used as contrast agents or superoxide dismutase mimetics. Today, metalloporphyrins represent complexes of conjugated π-electron system and metals from the entire periodic system. However, the effect of these compounds on living systems has not been fully understood, and researchers are exploring the properties of metalloporphyrins thereby extending their further application. This review provides an overview of the variety of metalloporphyrins that are currently used in different medicine fields and how metalloporphyrins became the subject of scientists' interest. Currently, metalloporphyrins utilization has expanded significantly, which gave us an opprotunuty to summarize recent progress in metalloporphyrins derivatives and prospects of their application in the treatment and diagnosis of different diseases.

A high-fructose diet in rats induces systemic iron deficiency and hepatic iron overload by an inflammation mechanism

Nonalcoholic fatty liver disease (NAFLD) correlates with the high intake of fructose-rich soft drinks. Both inflammation and dysregulated iron metabolism are pathogenic factors in the development of NAFLD. The present investigation assessed the effects of a high-fructose diet (HF diet) on inflammation and iron metabolism. In this study, rats were fed a control or HF diet for 4, 8, or 12 weeks, after which insulin resistance, transaminases levels, serum and liver lipid profiles, inflammatory factors, and iron metabolism-related molecules were evaluated. The activities of the hepatic inflammation-associated pathways, IKKβ/NF-κB, and JAK2/STAT3, were detected by western blot. Result showed that the HF diet-fed animals developed a time-dependent serum lipid increase and hepatic lipid accumulation as well as insulin resistance. Serum iron (SI), serum ferritin (SF), and transferrin saturation (TS) decreased while total iron-binding capacity (TIBC) and serum transferrin (s-TF) increased at 8 and 12 weeks in the HF diet group. The HF diet led to increased transaminases levels at 8 and 12 weeks, and iron deposition was observed in the liver, accompanied by an upregulation of ferritin light chain (FTL), hepcidin (HEPC), transferrin (TF), transferrin receptor 1 (TfR1), iron regulatory protein 1 (IRP1), hemojuvelin (HJV), and divalent metal transporter 1 (DMT1). Moreover, ferroportin (FPN1) levels were downregulated, as expected from the increased HEPC. A progressive inflammation phenotype was apparent, with increased inflammatory factors, MDA, IL-1β, IL-6, and TNF-α, in the serum and liver tissue. Concomitantly, the hepatic IKKβ/NF-κB and JAK2/STAT3 pathways were activated. In summary, we verified that HF diet induces systemic iron deficiency and hepatic iron accumulation, likely due to the activation of inflammation via the NF-κB and JAK2/STAT3 pathways. PRACTICAL APPLICATIONS: As increasing numbers of individuals consume HF diets, the health implications of this type of over nutrition become globally relevant. Using a high-fructose diet rat model, our present study reveals inflammation as the link between a HF diet and dysregulated iron metabolism. Importantly, both inflammation and disrupted iron metabolism have been shown to be pathogenic factors in nonalcoholic fatty liver disease (NAFLD). The iron regulatory hormone, HEPC, is a link between the liver, inflammation, and iron metabolism. As fructose-rich foods become increasingly abundant and people's fructose intake increases, the impact of high fructose on health requires increased attention. Little research has been conducted on the effects of fructose on iron metabolism. Our study provides useful insights into the prevention and treatment of iron metabolism disorders arising from metabolic syndrome.

Opportunities for plant-derived enhancers for iron, zinc, and calcium bioavailability: A review

Understanding of the mechanism of interactions between dietary elements, their salts, and complexing/binding ligands is vital to manage both deficiency and toxicity associated with essential element bioavailability. Numerous mineral ligands are found in both animal and plant foods and are known to exert bioactivity via element chelation resulting in modulation of antioxidant capacity or micobiome metabolism among other physiological outcomes. However, little is explored in the context of dietary mineral ligands and element bioavailability enhancement, particularly with respect to ligands from plant-derived food sources. This review highlights a novel perspective to consider various plant macro/micronutrients as prospective bioavailability enhancing ligands of three essential elements (Fe, Zn, and Ca). We also delineate the molecular mechanisms of the ligand-binding interactions underlying mineral bioaccessibility at the luminal level. We conclude that despite current understandings of some of the structure-activity relationships associated with strong mineral-ligand binding, the physiological links between ligands as element carriers and uptake at targeted sites throughout the gastrointestinal (GI) tract still require more research. The binding behavior of potential ligands in the human diet should be further elucidated and validated using pharmacokinetic approaches and GI models.

Whole-Exome Sequencing Identifies Three Candidate Homozygous Variants in a Consanguineous Iranian Family with Autism Spectrum Disorder and Skeletal Problems

Autism spectrum disorder (ASD) is characterized by 3 core symptoms with impaired social communication, repetitive behavior, and/or restricted interests in early childhood. As a complex neurodevelopmental disorder (NDD), the phenotype and severity of autism are extremely heterogeneous. Genetic factors have a key role in the etiology of autism. In this study, we investigated an Azeri Turkish family with 2 ASD-affected individuals to identify probable ASD-causing variants. First, the affected individuals were karyotyped in order to exclude chromosomal abnormalities. Then, whole-exome sequencing was carried out in one affected sibling followed by cosegregation analysis for the candidate variants in the family. In addition, SNP genotyping was carried out in the patients to identify possible homozygosity regions. Both proband and sibling had a normal karyotype. We detected 3 possible causative variants in this family: c.5443G>A; p.Gly1815Ser, c.1027C>T; p.Arg343Trp, and c.382A>G; p.Lys128Glu, which are in the FBN1, TF, and PLOD2 genes, respectively. All of the variants cosegregated in the family, and SNP genotyping revealed that these 3 variants are located in the homozygosity regions. This family serves as an example of a multimodal polygenic risk for a complex developmental disorder. Of these 3 genes, confluence of the variants in FBN1 and PLOD2 may contribute to the autistic features of the patient in addition to skeletal problems. Our study highlights the genetic complexity and heterogeneity of NDDs such as autism. In other words, in some patients with ASD, multiple rare variants in different loci rather than a monogenic state may contribute to the development of phenotypes.