scholarly journals Iron Status Influences Mitochondrial Disease Progression in Complex I-Deficient Mice

2021 ◽  
Author(s):  
Anthony S. Grillo ◽  
CJ Kelly ◽  
Vivian T. Ha ◽  
Camille M. Bodart ◽  
Sydney Huff ◽  
...  
Keyword(s):  
Disease Progression ◽  
Mitochondrial Disease ◽  
Knockout Mice ◽  
Complex I ◽  
Iron Homeostasis ◽  
Iron Status ◽  
Leigh Syndrome ◽  
Intracellular Iron ◽  
Iron Restriction ◽  
Iron Sulfur

AbstractMitochondrial dysfunction caused by aberrant Complex I assembly and reduced activity of the electron transport chain is pathogenic in many genetic and age-related diseases. Mice missing the Complex I subunit NADH dehydrogenase [ubiquinone] iron-sulfur protein 4 (NDUFS4) are a leading mammalian model of severe mitochondrial disease that exhibit many characteristic symptoms of Leigh Syndrome including oxidative stress, neuroinflammation, brain lesions, and premature death. NDUFS4 knockout mice have decreased expression of nearly every Complex I subunit. As Complex I normally contains at least 8 iron-sulfur clusters and more than 25 iron atoms, we asked whether a deficiency of Complex I may lead to intracellular iron perturbations thereby accelerating disease progression. Consistent with this, iron supplementation accelerates symptoms of brain degeneration in these mice while iron restriction delays the onset of these symptoms and increases survival. NDUFS4 knockout mice display signs of iron overload in the liver including increased expression of hepcidin, and show changes in iron responsive element-regulated proteins consistent with increased intracellular iron that were prevented by iron restriction. These results suggest that perturbed iron homeostasis may contribute to pathology in Leigh Syndrome and possibly other mitochondrial disorders.

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

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 1283-1283
Author(s):  
Mikyoung You ◽  
Soonkyu Chung
Keyword(s):  
Adipose Tissue ◽  
Iron Metabolism ◽  
Knockout Mice ◽  
Iron Homeostasis ◽  
Regulatory Protein ◽  
Mrna Translation ◽  
Intracellular Iron ◽  
Mobility Shift ◽  
Iron Regulatory Proteins ◽  
Tissue Browning

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

Altered lipid metabolism in Hfe-knockout mice promotes severe NAFLD and early fibrosis

2011 ◽  
Vol 301 (5) ◽  
pp. G865-G876 ◽  
Author(s):  
Terrence C. H. Tan ◽  
Darrell H. G. Crawford ◽  
Lesley A. Jaskowski ◽  
Therese M. Murphy ◽  
Mandy L. Heritage ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Knockout Mice ◽  
Iron Homeostasis ◽  
Iron Status ◽  
Current Evidence ◽  
Hepatic Iron ◽  
Potential Contribution ◽  
Nonalcoholic Fatty Liver ◽  
Hepcidin Expression ◽  
Mitochondrial Fatty Acid

The HFE protein plays a crucial role in the control of cellular iron homeostasis. Steatosis is commonly observed in HFE-related iron-overload disorders, and current evidence suggests a causal link between iron and steatosis. Here, we investigated the potential contribution of HFE mutations to hepatic lipid metabolism and its role in the pathogenesis of nonalcoholic fatty liver disease. Wild-type (WT) and Hfe knockout mice ( Hfe−/−) were fed either standard chow, a monounsaturated low fat, or a high-fat, high-carbohydrate diet (HFD) and assessed for liver injury, body iron status, and markers of lipid metabolism. Despite hepatic iron concentrations and body weights similar to WT controls, Hfe −/− mice fed the HFD developed severe hypoxia-related steatohepatitis, Tnf-α activation, and mitochondrial respiratory complex and antioxidant dysfunction with early fibrogenesis. These features were associated with an upregulation in the expression of genes involved in intracellular lipid synthesis and trafficking, while transcripts for mitochondrial fatty acid β-oxidation and adiponectin signaling-related genes were significantly attenuated. In contrast, HFD-fed WT mice developed bland steatosis only, with no inflammation or fibrosis and no upregulation of lipogenesis-related genes. A HFD led to reduced hepatic iron in Hfe −/− mice compared with chow-fed mice, despite higher serum iron, decreased hepcidin expression, and increased duodenal ferroportin mRNA . In conclusion, our results demonstrate that Hfe −/− mice show defective hepatic-intestinal iron and lipid signaling, which predispose them toward diet-induced hepatic lipotoxicity, accompanied by an accelerated progression of injury to fibrosis.

scholarly journals Response of Monocyte Iron Regulatory Protein Activity to Inflammation: Abnormal Behavior in Genetic Hemochromatosis

Blood ◽  
1998 ◽  
Vol 91 (7) ◽  
pp. 2565-2572 ◽  
Author(s):  
Stefania Recalcati ◽  
Roberta Pometta ◽  
Sonia Levi ◽  
Dario Conte ◽  
Gaetano Cairo
Keyword(s):  
Iron Homeostasis ◽  
Iron Status ◽  
Regulatory Protein ◽  
Abnormal Behavior ◽  
Iron Regulatory Protein ◽  
Iron Release ◽  
Protein Activity ◽  
Intracellular Iron ◽  
Ifn Γ ◽  
Genetic Hemochromatosis

Abstract In genetic hemochromatosis (GH), iron overload affects mainly parenchymal cells, whereas little iron is found in reticuloendothelial (RE) cells. We previously found that RE cells from GH patients had an inappropriately high activity of iron regulatory protein (IRP), the key regulator of intracellular iron homeostasis. Elevated IRP should reflect a reduction of the iron pool, possibly because of a failure to retain iron. A defect in iron handling by RE cells that results in a lack of feedback regulation of intestinal absorption might be the basic abnormality in GH. To further investigate the capacity of iron retention in RE cells of GH patients, we used inflammation as a model system as it is characterized by a block of iron release from macrophages. We analyzed the iron status of RE cells by assaying IRP activity and ferritin content after 4, 8, and 24 hours of incubation with lipopolysaccharide (LPS) and interferon-γ (IFN-γ). RNA-bandshift assays showed that in monocytes and macrophages from 16 control subjects, IRP activity was transiently elevated 4 hours after treatment with LPS and IFN-γ but remarkably downregulated thereafter. Treatment with NO donors produced the same effects whereas an inducible Nitric Oxide Synthase (iNOS) inhibitor prevented them, which suggests that the NO pathway was involved. Decreased IRP activity was also found in monocytes from eight patients with inflammation. Interestingly, no late decrease of IRP activity was detected in cytokine-treated RE cells from 12 GH patients. Ferritin content was increased 24 hours after treatment in monocytes from normal subjects but not in monocytes from GH patients. The lack of downregulation of IRP activity under inflammatory conditions seems to confirm that the control of iron release from RE cells is defective in GH.

scholarly journals Mitochondrial Proteome of Affected Neurons in a Mouse Model of Leigh Syndrome

2019 ◽  
Author(s):  
Alejandro Gella ◽  
Patricia Prada-Dacasa ◽  
Montserrat Carrascal ◽  
Melania González-Torres ◽  
Joaquin Abian ◽  
...  
Keyword(s):  
Mouse Model ◽  
Mitochondrial Disease ◽  
Complex I ◽  
Viral Vector ◽  
Mitochondrial Diseases ◽  
Leigh Syndrome ◽  
Premature Death ◽  
Cell Types ◽  
Supporting Cell ◽  
Pediatric Presentation

AbstractDefects in mitochondrial function lead to severe neuromuscular orphan pathologies known as mitochondrial disease. Among them, Leigh Syndrome is the most common pediatric presentation, characterized by symmetrical brain lesions, hypotonia, motor and respiratory deficits, and premature death. Mitochondrial diseases are characterized by a marked anatomical and cellular specificity. However, the molecular determinants for this susceptibility are currently unknown, hindering the efforts to find an effective treatment. Due to the complex crosstalk between mitochondria and their supporting cell, strategies to assess the underlying alterations in affected cell types in the context of mitochondrial dysfunction are critical. Here, we developed a novel virus-based tool, the AAV-mitoTag viral vector, to isolate mitochondria from genetically-defined cell types. Administration of the AAV-mitoTag in the vestibular neurons of a mouse model of Leigh Syndrome lacking the complex I subunit Ndufs4 allowed us to assess the proteome and acetylome of susceptible neurons in a well characterized model recapitulating the human disease. Our results show a marked reduction of complex-I N-module subunit abundance and an increase in the levels of the assembly factor NDUFA2. Transiently-associated non-mitochondrial proteins such as PKCδ, and the complement subcomponent C1Q were also increased in Ndufs4-deficient mitochondria. Furthermore, lack of Ndufs4 induced pyruvate dehydrogenase (PDH) subunit hyperacetylation, leading to decreased PDH activity. We provide novel insight on the pathways involved in mitochondrial disease, which could underlie potential therapeutic approaches for these pathologies.

scholarly journals Sensing of Liver Iron Content Requires Cell-Cell Communication between Hepatocytes and Liver Sinusoidal Endothelial Cells

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 432-432
Author(s):  
Silvia Colucci ◽  
Sandro Altamura ◽  
Matthias Hentze ◽  
Martina U. Muckenthaler
Keyword(s):  
Endothelial Cells ◽  
Mrna Expression ◽  
Iron Content ◽  
Iron Homeostasis ◽  
Iron Status ◽  
Molecular Signature ◽  
Iron Release ◽  
Liver Sinusoidal Endothelial Cells ◽  
Intracellular Iron ◽  
Sinusoidal Endothelial Cells

The liver stores iron and senses systemic and tissue iron availability. Hepatocytes control iron homeostasis by producing the peptide hormone hepcidin that controls dietary iron absorption and iron release from intracellular stores. Recent data challenged the exclusive role of hepatocytes in controlling iron levels. Indeed, liver sinusoidal endothelial cells (LSECs) increase BMP2 and BMP6 levels in response to iron, which control hepcidin expression in a paracrine manner. However the molecular mechanism(s) of how BMPs respond to iron levels remain unknown. We established primary murine LSEC cultures and exposed these to iron sources. Unexpectedly, BMP2 mRNA expression is strongly reduced by iron treatment, while BMP6 levels are only mildly increased. This finding suggests that intracellular iron content cannot directly activate BMP2 transcription and only slightly contribute to BMP6 upregulation in LSEC cultures. However, if LSECs are co-cultured with iron-loaded primary hepatocytes the expression of BMP2 and BMP6 is increased and the fold induction of BMP6 is greater compared to LSECs cultured alone, suggesting that the iron status of hepatocytes instructs the LSEC BMP response. These data are supported by findings in a genetic mouse model of iron overload (Slc40a1C326S/C326S). Hepatocytes isolated from Slc40a1C326S/C326S mice display an iron-loaded molecular signature and the expected low mRNA expression of Transferrin Receptor 1 (Tfr1). By contrast, LSECs show high expression of Tfr1, indicating intracellular iron deficiency. Despite this, hepatic BMP levels are increased, suggesting that BMP2 and BMP6 expression are directly related to the intracellular iron content of hepatocytes but not LSECs. RNA-sequencing of isolated hepatic cell populations is ongoing to identify putative hepatocyte regulators involved in the iron-mediated BMP2 and BMP6 regulation. Disclosures Muckenthaler: Silence Therapeutics: Consultancy; Novartis: Research Funding.

scholarly journals Copper Stress Affects Iron Homeostasis by Destabilizing Iron-Sulfur Cluster Formation in Bacillus subtilis

2010 ◽  
Vol 192 (10) ◽  
pp. 2512-2524 ◽  
Author(s):  
Shashi Chillappagari ◽  
Andreas Seubert ◽  
Hein Trip ◽  
Oscar P. Kuipers ◽  
Mohamed A. Marahiel ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Iron Homeostasis ◽  
Cluster Formation ◽  
Cellular Growth ◽  
Copper Stress ◽  
Intracellular Iron ◽  
Iron Sulfur Cluster ◽  
Sulfur Cluster ◽  
Iron Sulfur ◽  
Copper Excess

ABSTRACT Copper and iron are essential elements for cellular growth. Although bacteria have to overcome limitations of these metals by affine and selective uptake, excessive amounts of both metals are toxic for the cells. Here we investigated the influences of copper stress on iron homeostasis in Bacillus subtilis, and we present evidence that copper excess leads to imbalances of intracellular iron metabolism by disturbing assembly of iron-sulfur cofactors. Connections between copper and iron homeostasis were initially observed in microarray studies showing upregulation of Fur-dependent genes under conditions of copper excess. This effect was found to be relieved in a csoR mutant showing constitutive copper efflux. In contrast, stronger Fur-dependent gene induction was found in a copper efflux-deficient copA mutant. A significant induction of the PerR regulon was not observed under copper stress, indicating that oxidative stress did not play a major role under these conditions. Intracellular iron and copper quantification revealed that the total iron content was stable during different states of copper excess or efflux and hence that global iron limitation did not account for copper-dependent Fur derepression. Strikingly, the microarray data for copper stress revealed a broad effect on the expression of genes coding for iron-sulfur cluster biogenesis (suf genes) and associated pathways such as cysteine biosynthesis and genes coding for iron-sulfur cluster proteins. Since these effects suggested an interaction of copper and iron-sulfur cluster maturation, a mutant with a conditional mutation of sufU, encoding the essential iron-sulfur scaffold protein in B. subtilis, was assayed for copper sensitivity, and its growth was found to be highly susceptible to copper stress. Further, different intracellular levels of SufU were found to influence the strength of Fur-dependent gene expression. By investigating the influence of copper on cluster-loaded SufU in vitro, Cu(I) was found to destabilize the scaffolded cluster at submicromolar concentrations. Thus, by interfering with iron-sulfur cluster formation, copper stress leads to enhanced expression of cluster scaffold and target proteins as well as iron and sulfur acquisition pathways, suggesting a possible feedback strategy to reestablish cluster biogenesis.

scholarly journals Iron Homeostasis in Mycobacterium tuberculosis: Mechanistic Insights into Siderophore-Mediated Iron Uptake

2016 ◽  
Vol 198 (18) ◽  
pp. 2399-2409 ◽  
Author(s):  
Manjula Sritharan
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Iron Uptake ◽  
Metal Ion ◽  
Iron Homeostasis ◽  
Iron Status ◽  
Mammalian Host ◽  
Intracellular Iron ◽  
Comprehensive Overview ◽  
Content Type ◽  
Excess Iron

Mycobacterium tuberculosisrequires iron for normal growth but faces a limitation of the metal ion due to its low solubility at biological pH and the withholding of iron by the mammalian host. The pathogen expresses the Fe3+-specific siderophores mycobactin and carboxymycobactin to chelate the metal ion from insoluble iron and the host proteins transferrin, lactoferrin, and ferritin. Siderophore-mediated iron uptake is essential for the survival ofM. tuberculosis, as knockout mutants, which were defective in siderophore synthesis or uptake, failed to survive in low-iron medium and inside macrophages. But as excess iron is toxic due to its catalytic role in the generation of free radicals, regulation of iron uptake is necessary to maintain optimal levels of intracellular iron. The focus of this review is to present a comprehensive overview of iron homeostasis inM. tuberculosisthat is discussed in the context of mycobactin biosynthesis, transport of iron across the mycobacterial cell envelope, and storage of excess iron. The clinical significance of the serum iron status and the expression of the iron-regulated protein HupB in tuberculosis (TB) patients is presented here, highlighting the potential of HupB as a marker, notably in extrapulmonary TB cases.

scholarly journals Neurospora Strains Harboring Mitochondrial Disease-Associated Mutations in Iron-Sulfur Subunits of Complex I

Genetics ◽  
2005 ◽  
Vol 171 (1) ◽  
pp. 91-99 ◽  
Author(s):  
Margarida Duarte ◽  
Ulrich Schulte ◽  
Alexandra V. Ushakova ◽  
Arnaldo Videira
Keyword(s):  
Mitochondrial Disease ◽  
Complex I ◽  
Iron Sulfur

scholarly journals Cardiac ferroportin regulates cellular iron homeostasis and is important for cardiac function

2015 ◽  
Vol 112 (10) ◽  
pp. 3164-3169 ◽  
Author(s):  
Samira Lakhal-Littleton ◽  
Magda Wolna ◽  
Carolyn A. Carr ◽  
Jack J. J. Miller ◽  
Helen C. Christian ◽  
...  
Keyword(s):  
Cardiac Function ◽  
Iron Homeostasis ◽  
Iron Status ◽  
Cell Types ◽  
Cardiac Complications ◽  
Iron Loading ◽  
Intracellular Iron ◽  
Cellular Iron ◽  
Assessment And Treatment ◽  
Cellular Iron Homeostasis

Iron is essential to the cell. Both iron deficiency and overload impinge negatively on cardiac health. Thus, effective iron homeostasis is important for cardiac function. Ferroportin (FPN), the only known mammalian iron-exporting protein, plays an essential role in iron homeostasis at the systemic level. It increases systemic iron availability by releasing iron from the cells of the duodenum, spleen, and liver, the sites of iron absorption, recycling, and storage respectively. However, FPN is also found in tissues with no known role in systemic iron handling, such as the heart, where its function remains unknown. To explore this function, we generated mice with a cardiomyocyte-specific deletion of Fpn. We show that these animals have severely impaired cardiac function, with a median survival of 22 wk, despite otherwise unaltered systemic iron status. We then compared their phenotype with that of ubiquitous hepcidin knockouts, a recognized model of the iron-loading disease hemochromatosis. The phenotype of the hepcidin knockouts was far milder, with normal survival up to 12 mo, despite far greater iron loading in the hearts. Histological examination demonstrated that, although cardiac iron accumulates within the cardiomyocytes of Fpn knockouts, it accumulates predominantly in other cell types in the hepcidin knockouts. We conclude, first, that cardiomyocyte FPN is essential for intracellular iron homeostasis and, second, that the site of deposition of iron within the heart determines the severity with which it affects cardiac function. Both findings have significant implications for the assessment and treatment of cardiac complications of iron dysregulation.

scholarly journals Disruption in iron homeostasis and impaired activity of iron-sulfur cluster containing proteins in the yeast model of Shwachman-Diamond syndrome

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Ayushi Jain ◽  
Phubed Nilatawong ◽  
Narinrat Mamak ◽  
Laran T. Jensen ◽  
Amornrat Naranuntarat Jensen
Keyword(s):  
Succinate Dehydrogenase ◽  
Ribosome Biogenesis ◽  
Manganese Superoxide Dismutase ◽  
Iron Homeostasis ◽  
Iron Chelation ◽  
Anion Channel ◽  
Voltage Dependent Anion Channel ◽  
Intracellular Iron ◽  
Iron Sulfur ◽  
Shwachman Diamond Syndrome

Abstract Background Shwachman-Diamond syndrome (SDS) is a congenital disease that affects the bone marrow, skeletal system, and pancreas. The majority of patients with SDS have mutations in the SBDS gene, involved in ribosome biogenesis as well as other processes. A Saccharomyces cerevisiae model of SDS, lacking Sdo1p the yeast orthologue of SBDS, was utilized to better understand the molecular pathogenesis in the development of this disease. Results Deletion of SDO1 resulted in a three-fold over-accumulation of intracellular iron. Phenotypes associated with impaired iron-sulfur (ISC) assembly, up-regulation of the high affinity iron uptake pathway, and reduced activities of ISC containing enzymes aconitase and succinate dehydrogenase, were observed in sdo1∆ yeast. In cells lacking Sdo1p, elevated levels of reactive oxygen species (ROS) and protein oxidation were reduced with iron chelation, using a cell impermeable iron chelator. In addition, the low activity of manganese superoxide dismutase (Sod2p) seen in sdo1∆ cells was improved with iron chelation, consistent with the presence of reactive iron from the ISC assembly pathway. In yeast lacking Sdo1p, the mitochondrial voltage-dependent anion channel (VDAC) Por1p is over-expressed and its deletion limits iron accumulation and increases activity of aconitase and succinate dehydrogenase. Conclusions We propose that oxidative stress from POR1 over-expression, resulting in impaired activity of ISC containing proteins and disruptions in iron homeostasis, may play a role in disease pathogenesis in SDS patients.

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