Frataxin Acts as an Iron Chaperone Protein to Modulate Mitochondrial Aconitase Activity

Bulteau, Anne Laure; O'Neill, Heather A.; Kennedy, Mary Claire; Ikeda‐Saito, Masao; Isaya, Grazia; Szweda, Luke I.

doi:10.1126/science.1098991

Cited by 335 publications

(298 citation statements)

References 30 publications

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“…We have previously shown in vitro that when mitochondria are challenged with prooxidants, aconitase and the mitochondrial iron-binding protein frataxin interact. This interaction requires the enzyme's substrate citrate, protects the [4Fe-4S] 2ϩ cluster of aconitase from oxidant-induced disassembly, and is required for enzyme reactivation (24). Immunopurification of aconitase followed by Western blot analysis of frataxin revealed that the two proteins interacted exclusively during reperfusion (Fig.…”

Section: Resultsmentioning

confidence: 99%

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Reversible redox-dependent modulation of mitochondrial aconitase and proteolytic activity during in vivo cardiac ischemia/reperfusion

Bulteau

Lundberg

Ikeda‐Saito

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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129

118

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Prooxidents can induce reversible inhibition or irreversible inactivation and degradation of the mitochondrial enzyme aconitase. Cardiac ischemia͞reperfusion is associated with an increase in mitochondrial free radical production. In the current study, the effects of reperfusion-induced production of prooxidants on mitochondrial aconitase and proteolytic activity were determined to assess whether alterations represented a regulated response to changes in redox status or oxidative damage. Evidence is provided that ATP-dependent proteolytic activity increased during early reperfusion followed by a time-dependent reduction in activity to control levels. These alterations in proteolytic activity paralleled an increase and subsequent decrease in the level of oxidatively modified protein. In vitro data supports a role for prooxidants in the activation of ATP-dependent proteolytic activity. Despite inhibition during early periods of reperfusion, aconitase was not degraded under the conditions of these experiments. Aconitase activity exhibited a decline in activity followed by reactivation during cardiac reperfusion. Loss and regain in activity involved reversible sulfhydryl modification. Aconitase was found to associate with the iron binding protein frataxin exclusively during reperfusion. In vitro, frataxin has been shown to protect aconitase from [4Fe-4S] 2؉ cluster disassembly, irreversible inactivation, and, potentially, degradation. Thus, the response of mitochondrial aconitase and ATP-dependent proteolytic activity to reperfusioninduced prooxidant production appears to be a regulated event that would be expected to reduce irreparable damage to the mitochondria.H ighly reactive oxygen derived free radicals, such as superoxide anion (O 2•Ϫ ) and the prooxidant hydrogen peroxide (H 2 O 2 ), can interact with a variety of cellular components, altering both structure and function (1). Although evidence for these reactions has long been sought as indication of free radical involvement in degenerative disorders, recent evidence indicates that these processes also participate in the regulation of cellular function (1, 2). This finding is exemplified by the discovery of enzymatic systems, such as thioredoxin reductase͞thioredoxin (3), glutaredoxin (4), methione sulfoxide reductase (5), and sulfiredoxin (6), which catalyze reversal of oxidative modifications to protein and restoration of protein function. Additionally, receptor-and enzyme-mediated systems exist that catalyze the production of free radicals in response to changes in extracellular and intracellular factors (1, 2). It is therefore important that free radicals produced during physiological and pathophysiological conditions be investigated not simply for their potential to carry out damaging processes but also to induce appropriate alterations in response to changes in cellular homeostasis.Reduction and͞or cessation of blood f low to myocardial tissue, termed ischemia, occurs primarily as a result of formation of atherosclerotic lesions in the coronary arteries...

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Section: Resultsmentioning

confidence: 99%

“…3A). Based on previous in vitro results (24), the interaction between aconitase and frataxin upon reoxygenation likely protects aconitase from prooxidant-induced cluster disassembly, irreversible inactivation, and degradation.…”

Section: Resultsmentioning

confidence: 99%

Reversible redox-dependent modulation of mitochondrial aconitase and proteolytic activity during in vivo cardiac ischemia/reperfusion

Bulteau

Lundberg

Ikeda‐Saito

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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129

118

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“…On the contrary, 30% of the patients with NAFLD have elevated ferritin levels [139][140][141], and there is an association between insulin resistance and liver iron [142,143]. Therefore, it sounds rationale that iron causes oxidative stress because it is a well-known prooxidant and possesses negative effects upon the mitochondria [144,145]. However, ongoing additional studies at present indicate that iron is likely to be important in only a minority of patients with NAFLD.…”

Section: Ironmentioning

confidence: 99%

Role of free radicals in liver diseases

2009

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Reactive oxygen and nitrogen species (ROS and RNS) are produced by metabolism of normal cells. However, in liver diseases, redox is increased thereby damaging the hepatic tissue; the capability of ethanol to increase both ROS/RNS and peroxidation of lipids, DNA, and proteins was demonstrated in a variety of systems, cells, and species, including humans. ROS/RNS can activate hepatic stellate cells, which are characterized by the enhanced production of extracellular matrix and accelerated proliferation. Cross-talk between parenchymal and nonparenchymal cells is one of the most important events in liver injury and fibrogenesis; ROS play an important role in fibrogenesis throughout increasing platelet-derived growth factor. Most hepatocellular carcinomas occur in cirrhotic livers, and the common mechanism for hepatocarcinogenesis is chronic inflammation associated with severe oxidative stress; other risk factors are dietary aflatoxin B 1 consumption, cigarette smoking, and heavy drinking. Ischemia-reperfusion injury affects directly on hepatocyte viability, particularly during transplantation and hepatic surgery; ischemia activates Kupffer cells which are the main source of ROS during the reperfusion period. The toxic action mechanism of paracetamol is focused on metabolic activation of the drug, depletion of glutathione, and covalent binding of the reactive metabolite N-acetyl-pbenzoquinone imine to cellular proteins as the main cause of hepatic cell death; intracellular steps critical for cell death include mitochondrial dysfunction and, importantly, the formation of ROS and peroxynitrite. Infection with hepatitis C is associated with increased levels of ROS/RNS and decreased antioxidant levels. As a consequence, antioxidants have been proposed as an adjunct therapy for various liver diseases.

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“…The decrease in frataxin protein has broad, far-reaching effects because the protein is an essential iron chaperone required for the biogenesis of iron-sulfur clusters, aconitase activation, and heme biosynthesis [18][19][20][21], and further performs a critical role in iron detoxification and anti-oxidant protection [22][23][24]. Thus a loss of frataxin leads to widespread impairment of energy metabolism, increased oxidative stress, and a generally dysregulated iron metabolism, including accumulation of iron in the heart and nervous system [25].…”

Section: Introductionmentioning

confidence: 99%

Lateral-flow immunoassay for the frataxin protein in Friedreich’s ataxia patients and carriers

Willis¹,

Isaya

Gakh

et al. 2008

Molecular Genetics and Metabolism

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Friedreich's Ataxia (FA) is an inherited neurodegenerative disease caused by reduction in levels of the mitochondrial protein frataxin. Currently there are no simple, reliable methods to accurately measure the concentrations of frataxin protein. We designed a lateral-flow immunoassay that quantifies frataxin protein levels in a variety of sample materials. Using recombinant frataxin we evaluated the accuracy and reproducibility of the assay. The assay measured recombinant human frataxin concentrations between 40 and 4000 pg/test or approximately 0.1 -10 nM of sample. The intra and inter-assay error was < 10% throughout the working range. To evaluate clinical utility of the assay we used genetically defined lymphoblastoid cells derived from FA patients, FA carriers and controls. Mean frataxin concentrations in FA patients and carriers were significantly different from controls and from one another (p = 0.0001, p = 0.003, p = 0.005, respectively) with levels, on average, 29% (patients) and 64% (carriers) of the control group. As predicted, we observed an inverse relationship between GAA repeat number and frataxin protein concentrations within the FA patient cohort. The lateral flow immunoassay provides a simple, accurate and reproducible method to quantify frataxin protein in whole cell and tissue extracts, including primary samples obtained by non-invasive means, such as cheek swabs and whole blood. The assay is a novel tool for FA research that may facilitate improved diagnostic and prognostic evaluation of FA patients and could also be used to evaluate efficacy of therapies designed to cure FA by increasing frataxin protein levels.

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Frataxin Acts as an Iron Chaperone Protein to Modulate Mitochondrial Aconitase Activity

Cited by 335 publications

References 30 publications

Reversible redox-dependent modulation of mitochondrial aconitase and proteolytic activity during in vivo cardiac ischemia/reperfusion

Reversible redox-dependent modulation of mitochondrial aconitase and proteolytic activity during in vivo cardiac ischemia/reperfusion

Role of free radicals in liver diseases

Lateral-flow immunoassay for the frataxin protein in Friedreich’s ataxia patients and carriers

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