SummaryWith a global increase in chronic kidney disease patients, alternatives to dialysis and or... more SummaryWith a global increase in chronic kidney disease patients, alternatives to dialysis and organ transplantation are needed. Stem cell-based therapies could be one possibility to treat chronic kidney disease. Here, we used multipotent urine-derived renal progenitor cells (UdRPCs) to study nephrogenesis. UdRPCs treated with the JNK inhibitor-AEG3482, displayed decreased proliferation and downregulated transcription of cell cycle-associated genes as well as the kidney progenitor markers -SIX2, CITED1, and SALL1. In addition, levels of activated SMAD2/3, which is associated with the maintenance of self-renewal in UdRPCs, were decreased. JNK inhibition resulted in less efficient oxidative phosphorylation and more lipid peroxidation via ferroptosis-an iron-dependent non-apoptotic cell death pathway linked to various forms of kidney disease. Our study reveals the importance of JNK signalling in maintaining self-renewal as well as protection against ferroptosis in SIX2-positive UdRPCs....
Besides vaccines, the development of antiviral drugs targeting SARS-CoV-2 is critical for stoppin... more Besides vaccines, the development of antiviral drugs targeting SARS-CoV-2 is critical for stopping the current COVID-19 pandemic and preventing future outbreaks. The SARS-CoV-2 main protease (Mpro), a cysteine protease with essential functions in viral replication, has been validated as an effective drug target. Here, we show that Mpro is subject to redox regulation and reversibly switches between the enzymatically active dimer and the functionally dormant monomer through redox modifications of cysteine residues. These include sulfenylation, disulfide formation between the catalytic cysteine and a proximal cysteine, and generation of an allosteric lysine-cysteine SONOS bridge that is required for structural stability under oxidative stress conditions, such as those exerted by the innate immune system. We identify homo- and heterobifunctional reagents that mimic the redox switching and possess antiviral activity. The discovered redox switches are conserved in main proteases from othe...
Upregulation of Wnt activity in the hippocampus and the spinal cord correlates with disease sever... more Upregulation of Wnt activity in the hippocampus and the spinal cord correlates with disease severity. (a) Iba1 immunostaining (red) of spinal cord sections from Axin2lacZ/+ EAE mice at day 20. The white dashed line highlights lesion areas; white matter tissue is outlined by yellow dashed line. Nuclei were counterstained with Hoechst (blue). Scale bar, 100 μm. (b) Histogram represents the average number of lesions per section of each EAE time point as mean + SEM. Spinal cord: day 20 (n = 4; 15–35 sections/mouse), day 30 (n = 3; 10–23 sections/mouse), day 50 (n = 3; 10–17 sections/mouse). (c) Representative image of lesion site in the DG. Iba1 (red) immunostaining in hippocampal section from EAE mouse at day 30. Nuclei (grey). Scale bar, 50 μm. (d) Representative image of neural stem cells located in the SGZ. SOX2 (green) and GFAP (red). Arrowheads indicate SOX2+/GFAP+ radial glia-like cells and arrows indicate SOX2+/GFAP+ horizontal progenitors. Nuclei (grey). Scale bar, 25 μm. (e+f)...
Gene expression analysis in the hippocampal tissue of EAE mice. (a) qPCR analysis of selected Wnt... more Gene expression analysis in the hippocampal tissue of EAE mice. (a) qPCR analysis of selected Wnt ligands in the hippocampus at early (day 20) and chronic (day 50) stages of passive EAE. Histogram represents mean + SEM of fold-changes relative to control group (PBS) set as 1. Gene expression was normalized to Gapdh. Day 20 (EAE, n = 4–6; control, n = 4); day 50 (EAE, n = 8–13; control, n = 7–11). (b) qPCR analysis of selected Wnt ligands in the cortex, cerebellum and spinal cord at early stages of passive EAE (day 20). Histogram represents mean + SEM of fold-changes relative to control group (PBS) set as 1. Gene expression was normalized to Gapdh. Six control and six EAE mice were analysed for each part of the CNS. n.d. not detectable. (c) A regression analysis shows correlation between the TNFα and the Axin2 gene expression levels examined in hippocampal tissue of individual EAE animals. Pearson correlation, r = 0.8458; p
Table S1. Advised Protocol for OCT Study Terminology and Elements (APOSTEL) checklist; each item ... more Table S1. Advised Protocol for OCT Study Terminology and Elements (APOSTEL) checklist; each item discussed in the manuscript on the indicated page. (PDF 30Â kb)
Oxidative stress is two sided: Whereas excessive oxidant challenge causes damage to biomolecules,... more Oxidative stress is two sided: Whereas excessive oxidant challenge causes damage to biomolecules, maintenance of a physiological level of oxidant challenge, termed oxidative eustress, is essential for governing life processes through redox signaling. Recent interest has focused on the intricate ways by which redox signaling integrates these converse properties. Redox balance is maintained by prevention, interception, and repair, and concomitantly the regulatory potential of molecular thiol-driven master switches such as Nrf2/Keap1 or NF-κB/IκB is used for system-wide oxidative stress response. Nonradical species such as hydrogen peroxide (H2O2) or singlet molecular oxygen, rather than free-radical species, perform major second messenger functions. Chemokine-controlled NADPH oxidases and metabolically controlled mitochondrial sources of H2O2 as well as glutathione- and thioredoxin-related pathways, with powerful enzymatic back-up systems, are responsible for fine-tuning physiological...
Redox regulation of specific cysteines via oxidoreductases of the thioredoxin family is increasin... more Redox regulation of specific cysteines via oxidoreductases of the thioredoxin family is increasingly being recognized as an important signaling pathway. Here, we demonstrate that the cytosolic isoform of the vertebrate-specific oxidoreductase Glutaredoxin 2 (Grx2c) regulates the redox state of the transcription factor SP-1 and thereby its binding affinity to both the promoter and an enhancer region of the CSPG4 gene encoding chondroitin sulfate proteoglycan nerve/glial antigen 2 (NG2). This leads to an increased number of NG2 glia during in vitro oligodendroglial differentiation and promotes migration of these wound healing cells. On the other hand, we found that the same mechanism also leads to increased invasion of glioma tumor cells. Using in vitro (human cell lines), ex vivo (mouse primary cells), and in vivo models (zebrafish), as well as glioblastoma patient tissue samples we provide experimental data highlighting the Yin and Yang of redox signaling in the central nervous system and the enzymatic Taoism of Grx2c.
Thioredoxins (Trxs) provide electrons to essential cellular processes such as DNA synthesis. Here... more Thioredoxins (Trxs) provide electrons to essential cellular processes such as DNA synthesis. Here, we characterize human and murine Trx1 as new iron-sulfur proteins. The [2Fe-2S] cluster is complexed using cysteinyl side chains 32 and 73 in a dimeric holocomplex. Formation of the holo-dimer depends on small structural changes of the loop connecting helices three and four and is stabilized by the formation of a direct electrostatic interaction between Lys72 and Asp60 of two monomers. The not strictly conserved Cys73 in vertebrates co-evolved with the regulation of cellular iron homeostasis through the iron-regulatory proteins (IRP). Active apo-Trx1 is required for the reduction of cysteinyl residues in IRP1 and its binding to the iron-responsive elements in the mRNA encoding hypoxiainducible factor (HIF) 2α. Depletion of Trx1 increased the mRNA levels of HIF2α, an important target of IRP1. Hence, translation of the HIF2α mRNA requires either sufficient iron-supply or the lack of redu...
Ferroptosis is a form of regulated cell death that emerges to be relevant for therapy-resistant a... more Ferroptosis is a form of regulated cell death that emerges to be relevant for therapy-resistant and dedifferentiating cancers. Although several lines of evidence suggest that ferroptosis is a type of autophagy-dependent cell death, the underlying molecular mechanisms remain unclear. Fin56, a type 3 ferroptosis inducer, triggers ferroptosis by promoting glutathione peroxidase 4 (GPX4) protein degradation via a not fully understood pathway. Here, we determined that Fin56 induces ferroptosis and autophagy in bladder cancer cells and that Fin56-triggered ferroptosis mechanistically depends on the autophagic machinery. Furthermore, we found that autophagy inhibition at different stages attenuates Fin56-induced oxidative stress and GPX4 degradation. Moreover, we investigated the effects of Fin56 in combination with Torin 2, a potent mTOR inhibitor used to activate autophagy, on cell viability. We found that Fin56 synergizes with Torin 2 in cytotoxicity against bladder cancer cells. Collec...
Redox Regulation of Differentiation and De-Differentiation
Cysteine, the predominant biological thiol, was identified in 1884. Its presence in living organi... more Cysteine, the predominant biological thiol, was identified in 1884. Its presence in living organisms and the biochemistry of reduction and oxidation as well the importance of the redox state for protein function was elucidated in the first half of the 20th century. In the second half, proteins regulating the thiol redox state were identified, especially proteins facilitating or maintaining thiols reduced. Numerous posttranslational thiol modifications are described. This chapter provides a brief overview of the research on thiol redox regulation and is intended to remind researchers that knowledge of the history of a research field is helpful in pointing out that observations considered novel may already have been described years ago.
Despite their very close structural similarity, CxxC/S-type (class I) glutaredoxins (Grxs) act as... more Despite their very close structural similarity, CxxC/S-type (class I) glutaredoxins (Grxs) act as oxidoreductases, while CGFS-type (class II) Grxs act as FeS cluster transferases. Here we show that the key determinant of Grx function is a distinct loop structure adjacent to the active site. Engineering of a CxxC/S-type Grx with a CGFS-type loop switched its function from oxidoreductase to FeS transferase. Engineering of a CGFS-type Grx with a CxxC/S-type loop abolished FeS transferase activity and activated the oxidative half reaction of the oxidoreductase. The reductive half-reaction, requiring the interaction with a second GSH molecule, was enabled by switching additional residues in the active site. We explain how subtle structural differences, mostly depending on the structure of one particular loop, act in concert to determine Grx function.
Biochimica et Biophysica Acta (BBA) - Bioenergetics
Among the thioredoxin superfamily of proteins, the observation that numerous glutaredoxins bind i... more Among the thioredoxin superfamily of proteins, the observation that numerous glutaredoxins bind iron-sulphur (Fe/S) clusters is one of the more recent and major developments concerning their functional properties. Glutaredoxins are present in most organisms. All members of the class II subfamily (including most monothiol glutaredoxins), but also some members of the class I (mostly dithiol glutaredoxins) and class III (land plant-specific monothiol or dithiol glutaredoxins) are Fe/S proteins. In glutaredoxins characterised so far, the [2Fe-2S] cluster is coordinated by two active-site cysteine residues and two molecules of non-covalently bound glutathione in homo-dimeric complexes bridged by the cluster. In contrast to dithiol glutaredoxins, monothiol glutaredoxins possess no or very little oxidoreductase activity, but have emerged as important players in cellular iron metabolism. In this review we summarise the recent developments of the most prominent Fe/S glutaredoxins in eukaryotes, the mitochondrial single domain monothiol glutaredoxin 5, the chloroplastic single domain monothiol glutaredoxin S14 and S16, the nuclear/cytosolic multi-domain monothiol glutaredoxin 3, and the mitochondrial/cytosolic dithiol glutaredoxin 2.
Mitochondrial fusion and fission tailors the mitochondrial shape to changes in cellular homeostas... more Mitochondrial fusion and fission tailors the mitochondrial shape to changes in cellular homeostasis. Players of this process are the mitofusins, which regulate fusion of the outer mitochondrial membrane, and the fission protein DRP1. Upon specific stimuli, DRP1 translocates to the mitochondria, where it interacts with its receptors FIS1, MFF, and MID49/51. Another fission factor of clinical relevance is GDAP1. Here, we identify and discuss cysteine residues of these proteins that are conserved in phylogenetically distant organisms and which represent potential sites of posttranslational redox modifications. We reveal that worms and flies possess only a single mitofusin, which in vertebrates diverged into MFN1 and MFN2. All mitofusins contain four conserved cysteines in addition to cysteine 684 in MFN2, a site involved in mitochondrial hyperfusion. DRP1 and FIS1 are also evolutionarily conserved but only DRP1 contains four conserved cysteine residues besides cysteine 644, a specific ...
The European Cooperation in Science and Technology (COST) provides an ideal framework to establis... more The European Cooperation in Science and Technology (COST) provides an ideal framework to establish multi-disciplinary research networks. COST Action BM1203 (EU-ROS) represents a consortium of researchers from different disciplines who are dedicated to providing new insights and tools for better understanding redox biology and medicine and, in the long run, to finding new therapeutic strategies to target dysregulated redox processes in various diseases. This report highlights the major achievements of EU-ROS as well as research updates and new perspectives arising from its members. The EU-ROS consortium comprised more than 140 active members who worked together for four years on the topics briefly described below. The formation of reactive oxygen and nitrogen species (RONS) is an established hallmark of our aerobic environment and metabolism but RONS also act as messengers via redox regulation of essential cellular processes. The fact that many diseases have been found to be associat...
Proceedings of the National Academy of Sciences, 2013
Significance Embryonic development is one of the most amazing miracles in nature. The proteins an... more Significance Embryonic development is one of the most amazing miracles in nature. The proteins and signaling events driving this highly complex process are far from being elucidated completely. For a long time, an important role of protein reduction and oxidation during development has been assumed. Here, we demonstrate the essential role of such a regulation during cardiovascular development: The modification of a single cysteine in the protein sirtuin 1 by the vertebrate-specific oxidoreductase glutaredoxin 2 is required for vessel formation and guidance. Our data indicate that this redox-signaling pathway based on glutaredoxin-dependent reversible S -glutathionylation may be also important for diseases of the cardiovascular system and pathological situations connected to angiogenesis, e.g., malignancies.
The mechanisms by which eukaryotic cells handle and distribute the essential micronutrient iron w... more The mechanisms by which eukaryotic cells handle and distribute the essential micronutrient iron within the cytosol and other cellular compartments are only beginning to emerge. The yeast monothiol multidomain glutaredoxins (Grx) 3 and 4 are essential for both transcriptional iron regulation and intracellular iron distribution. Despite the fact that the mechanisms of iron metabolism differ drastically in fungi and higher eukaryotes, the glutaredoxins are conserved, yet their precise function in vertebrates has remained elusive. Here we demonstrate a crucial role of the vertebrate-specific monothiol multidomain Grx3 (PICOT) in cellular iron homeostasis. During zebrafish embryonic development, depletion of Grx3 severely impairs the maturation of hemoglobin, the major iron-consuming process. Silencing of human Grx3 expression in HeLa cells decreases the activities of several cytosolic Fe/S proteins, for example, iron-regulatory protein 1, a major component of posttranscriptional iron re...
SummaryWith a global increase in chronic kidney disease patients, alternatives to dialysis and or... more SummaryWith a global increase in chronic kidney disease patients, alternatives to dialysis and organ transplantation are needed. Stem cell-based therapies could be one possibility to treat chronic kidney disease. Here, we used multipotent urine-derived renal progenitor cells (UdRPCs) to study nephrogenesis. UdRPCs treated with the JNK inhibitor-AEG3482, displayed decreased proliferation and downregulated transcription of cell cycle-associated genes as well as the kidney progenitor markers -SIX2, CITED1, and SALL1. In addition, levels of activated SMAD2/3, which is associated with the maintenance of self-renewal in UdRPCs, were decreased. JNK inhibition resulted in less efficient oxidative phosphorylation and more lipid peroxidation via ferroptosis-an iron-dependent non-apoptotic cell death pathway linked to various forms of kidney disease. Our study reveals the importance of JNK signalling in maintaining self-renewal as well as protection against ferroptosis in SIX2-positive UdRPCs....
Besides vaccines, the development of antiviral drugs targeting SARS-CoV-2 is critical for stoppin... more Besides vaccines, the development of antiviral drugs targeting SARS-CoV-2 is critical for stopping the current COVID-19 pandemic and preventing future outbreaks. The SARS-CoV-2 main protease (Mpro), a cysteine protease with essential functions in viral replication, has been validated as an effective drug target. Here, we show that Mpro is subject to redox regulation and reversibly switches between the enzymatically active dimer and the functionally dormant monomer through redox modifications of cysteine residues. These include sulfenylation, disulfide formation between the catalytic cysteine and a proximal cysteine, and generation of an allosteric lysine-cysteine SONOS bridge that is required for structural stability under oxidative stress conditions, such as those exerted by the innate immune system. We identify homo- and heterobifunctional reagents that mimic the redox switching and possess antiviral activity. The discovered redox switches are conserved in main proteases from othe...
Upregulation of Wnt activity in the hippocampus and the spinal cord correlates with disease sever... more Upregulation of Wnt activity in the hippocampus and the spinal cord correlates with disease severity. (a) Iba1 immunostaining (red) of spinal cord sections from Axin2lacZ/+ EAE mice at day 20. The white dashed line highlights lesion areas; white matter tissue is outlined by yellow dashed line. Nuclei were counterstained with Hoechst (blue). Scale bar, 100 μm. (b) Histogram represents the average number of lesions per section of each EAE time point as mean + SEM. Spinal cord: day 20 (n = 4; 15–35 sections/mouse), day 30 (n = 3; 10–23 sections/mouse), day 50 (n = 3; 10–17 sections/mouse). (c) Representative image of lesion site in the DG. Iba1 (red) immunostaining in hippocampal section from EAE mouse at day 30. Nuclei (grey). Scale bar, 50 μm. (d) Representative image of neural stem cells located in the SGZ. SOX2 (green) and GFAP (red). Arrowheads indicate SOX2+/GFAP+ radial glia-like cells and arrows indicate SOX2+/GFAP+ horizontal progenitors. Nuclei (grey). Scale bar, 25 μm. (e+f)...
Gene expression analysis in the hippocampal tissue of EAE mice. (a) qPCR analysis of selected Wnt... more Gene expression analysis in the hippocampal tissue of EAE mice. (a) qPCR analysis of selected Wnt ligands in the hippocampus at early (day 20) and chronic (day 50) stages of passive EAE. Histogram represents mean + SEM of fold-changes relative to control group (PBS) set as 1. Gene expression was normalized to Gapdh. Day 20 (EAE, n = 4–6; control, n = 4); day 50 (EAE, n = 8–13; control, n = 7–11). (b) qPCR analysis of selected Wnt ligands in the cortex, cerebellum and spinal cord at early stages of passive EAE (day 20). Histogram represents mean + SEM of fold-changes relative to control group (PBS) set as 1. Gene expression was normalized to Gapdh. Six control and six EAE mice were analysed for each part of the CNS. n.d. not detectable. (c) A regression analysis shows correlation between the TNFα and the Axin2 gene expression levels examined in hippocampal tissue of individual EAE animals. Pearson correlation, r = 0.8458; p
Table S1. Advised Protocol for OCT Study Terminology and Elements (APOSTEL) checklist; each item ... more Table S1. Advised Protocol for OCT Study Terminology and Elements (APOSTEL) checklist; each item discussed in the manuscript on the indicated page. (PDF 30Â kb)
Oxidative stress is two sided: Whereas excessive oxidant challenge causes damage to biomolecules,... more Oxidative stress is two sided: Whereas excessive oxidant challenge causes damage to biomolecules, maintenance of a physiological level of oxidant challenge, termed oxidative eustress, is essential for governing life processes through redox signaling. Recent interest has focused on the intricate ways by which redox signaling integrates these converse properties. Redox balance is maintained by prevention, interception, and repair, and concomitantly the regulatory potential of molecular thiol-driven master switches such as Nrf2/Keap1 or NF-κB/IκB is used for system-wide oxidative stress response. Nonradical species such as hydrogen peroxide (H2O2) or singlet molecular oxygen, rather than free-radical species, perform major second messenger functions. Chemokine-controlled NADPH oxidases and metabolically controlled mitochondrial sources of H2O2 as well as glutathione- and thioredoxin-related pathways, with powerful enzymatic back-up systems, are responsible for fine-tuning physiological...
Redox regulation of specific cysteines via oxidoreductases of the thioredoxin family is increasin... more Redox regulation of specific cysteines via oxidoreductases of the thioredoxin family is increasingly being recognized as an important signaling pathway. Here, we demonstrate that the cytosolic isoform of the vertebrate-specific oxidoreductase Glutaredoxin 2 (Grx2c) regulates the redox state of the transcription factor SP-1 and thereby its binding affinity to both the promoter and an enhancer region of the CSPG4 gene encoding chondroitin sulfate proteoglycan nerve/glial antigen 2 (NG2). This leads to an increased number of NG2 glia during in vitro oligodendroglial differentiation and promotes migration of these wound healing cells. On the other hand, we found that the same mechanism also leads to increased invasion of glioma tumor cells. Using in vitro (human cell lines), ex vivo (mouse primary cells), and in vivo models (zebrafish), as well as glioblastoma patient tissue samples we provide experimental data highlighting the Yin and Yang of redox signaling in the central nervous system and the enzymatic Taoism of Grx2c.
Thioredoxins (Trxs) provide electrons to essential cellular processes such as DNA synthesis. Here... more Thioredoxins (Trxs) provide electrons to essential cellular processes such as DNA synthesis. Here, we characterize human and murine Trx1 as new iron-sulfur proteins. The [2Fe-2S] cluster is complexed using cysteinyl side chains 32 and 73 in a dimeric holocomplex. Formation of the holo-dimer depends on small structural changes of the loop connecting helices three and four and is stabilized by the formation of a direct electrostatic interaction between Lys72 and Asp60 of two monomers. The not strictly conserved Cys73 in vertebrates co-evolved with the regulation of cellular iron homeostasis through the iron-regulatory proteins (IRP). Active apo-Trx1 is required for the reduction of cysteinyl residues in IRP1 and its binding to the iron-responsive elements in the mRNA encoding hypoxiainducible factor (HIF) 2α. Depletion of Trx1 increased the mRNA levels of HIF2α, an important target of IRP1. Hence, translation of the HIF2α mRNA requires either sufficient iron-supply or the lack of redu...
Ferroptosis is a form of regulated cell death that emerges to be relevant for therapy-resistant a... more Ferroptosis is a form of regulated cell death that emerges to be relevant for therapy-resistant and dedifferentiating cancers. Although several lines of evidence suggest that ferroptosis is a type of autophagy-dependent cell death, the underlying molecular mechanisms remain unclear. Fin56, a type 3 ferroptosis inducer, triggers ferroptosis by promoting glutathione peroxidase 4 (GPX4) protein degradation via a not fully understood pathway. Here, we determined that Fin56 induces ferroptosis and autophagy in bladder cancer cells and that Fin56-triggered ferroptosis mechanistically depends on the autophagic machinery. Furthermore, we found that autophagy inhibition at different stages attenuates Fin56-induced oxidative stress and GPX4 degradation. Moreover, we investigated the effects of Fin56 in combination with Torin 2, a potent mTOR inhibitor used to activate autophagy, on cell viability. We found that Fin56 synergizes with Torin 2 in cytotoxicity against bladder cancer cells. Collec...
Redox Regulation of Differentiation and De-Differentiation
Cysteine, the predominant biological thiol, was identified in 1884. Its presence in living organi... more Cysteine, the predominant biological thiol, was identified in 1884. Its presence in living organisms and the biochemistry of reduction and oxidation as well the importance of the redox state for protein function was elucidated in the first half of the 20th century. In the second half, proteins regulating the thiol redox state were identified, especially proteins facilitating or maintaining thiols reduced. Numerous posttranslational thiol modifications are described. This chapter provides a brief overview of the research on thiol redox regulation and is intended to remind researchers that knowledge of the history of a research field is helpful in pointing out that observations considered novel may already have been described years ago.
Despite their very close structural similarity, CxxC/S-type (class I) glutaredoxins (Grxs) act as... more Despite their very close structural similarity, CxxC/S-type (class I) glutaredoxins (Grxs) act as oxidoreductases, while CGFS-type (class II) Grxs act as FeS cluster transferases. Here we show that the key determinant of Grx function is a distinct loop structure adjacent to the active site. Engineering of a CxxC/S-type Grx with a CGFS-type loop switched its function from oxidoreductase to FeS transferase. Engineering of a CGFS-type Grx with a CxxC/S-type loop abolished FeS transferase activity and activated the oxidative half reaction of the oxidoreductase. The reductive half-reaction, requiring the interaction with a second GSH molecule, was enabled by switching additional residues in the active site. We explain how subtle structural differences, mostly depending on the structure of one particular loop, act in concert to determine Grx function.
Biochimica et Biophysica Acta (BBA) - Bioenergetics
Among the thioredoxin superfamily of proteins, the observation that numerous glutaredoxins bind i... more Among the thioredoxin superfamily of proteins, the observation that numerous glutaredoxins bind iron-sulphur (Fe/S) clusters is one of the more recent and major developments concerning their functional properties. Glutaredoxins are present in most organisms. All members of the class II subfamily (including most monothiol glutaredoxins), but also some members of the class I (mostly dithiol glutaredoxins) and class III (land plant-specific monothiol or dithiol glutaredoxins) are Fe/S proteins. In glutaredoxins characterised so far, the [2Fe-2S] cluster is coordinated by two active-site cysteine residues and two molecules of non-covalently bound glutathione in homo-dimeric complexes bridged by the cluster. In contrast to dithiol glutaredoxins, monothiol glutaredoxins possess no or very little oxidoreductase activity, but have emerged as important players in cellular iron metabolism. In this review we summarise the recent developments of the most prominent Fe/S glutaredoxins in eukaryotes, the mitochondrial single domain monothiol glutaredoxin 5, the chloroplastic single domain monothiol glutaredoxin S14 and S16, the nuclear/cytosolic multi-domain monothiol glutaredoxin 3, and the mitochondrial/cytosolic dithiol glutaredoxin 2.
Mitochondrial fusion and fission tailors the mitochondrial shape to changes in cellular homeostas... more Mitochondrial fusion and fission tailors the mitochondrial shape to changes in cellular homeostasis. Players of this process are the mitofusins, which regulate fusion of the outer mitochondrial membrane, and the fission protein DRP1. Upon specific stimuli, DRP1 translocates to the mitochondria, where it interacts with its receptors FIS1, MFF, and MID49/51. Another fission factor of clinical relevance is GDAP1. Here, we identify and discuss cysteine residues of these proteins that are conserved in phylogenetically distant organisms and which represent potential sites of posttranslational redox modifications. We reveal that worms and flies possess only a single mitofusin, which in vertebrates diverged into MFN1 and MFN2. All mitofusins contain four conserved cysteines in addition to cysteine 684 in MFN2, a site involved in mitochondrial hyperfusion. DRP1 and FIS1 are also evolutionarily conserved but only DRP1 contains four conserved cysteine residues besides cysteine 644, a specific ...
The European Cooperation in Science and Technology (COST) provides an ideal framework to establis... more The European Cooperation in Science and Technology (COST) provides an ideal framework to establish multi-disciplinary research networks. COST Action BM1203 (EU-ROS) represents a consortium of researchers from different disciplines who are dedicated to providing new insights and tools for better understanding redox biology and medicine and, in the long run, to finding new therapeutic strategies to target dysregulated redox processes in various diseases. This report highlights the major achievements of EU-ROS as well as research updates and new perspectives arising from its members. The EU-ROS consortium comprised more than 140 active members who worked together for four years on the topics briefly described below. The formation of reactive oxygen and nitrogen species (RONS) is an established hallmark of our aerobic environment and metabolism but RONS also act as messengers via redox regulation of essential cellular processes. The fact that many diseases have been found to be associat...
Proceedings of the National Academy of Sciences, 2013
Significance Embryonic development is one of the most amazing miracles in nature. The proteins an... more Significance Embryonic development is one of the most amazing miracles in nature. The proteins and signaling events driving this highly complex process are far from being elucidated completely. For a long time, an important role of protein reduction and oxidation during development has been assumed. Here, we demonstrate the essential role of such a regulation during cardiovascular development: The modification of a single cysteine in the protein sirtuin 1 by the vertebrate-specific oxidoreductase glutaredoxin 2 is required for vessel formation and guidance. Our data indicate that this redox-signaling pathway based on glutaredoxin-dependent reversible S -glutathionylation may be also important for diseases of the cardiovascular system and pathological situations connected to angiogenesis, e.g., malignancies.
The mechanisms by which eukaryotic cells handle and distribute the essential micronutrient iron w... more The mechanisms by which eukaryotic cells handle and distribute the essential micronutrient iron within the cytosol and other cellular compartments are only beginning to emerge. The yeast monothiol multidomain glutaredoxins (Grx) 3 and 4 are essential for both transcriptional iron regulation and intracellular iron distribution. Despite the fact that the mechanisms of iron metabolism differ drastically in fungi and higher eukaryotes, the glutaredoxins are conserved, yet their precise function in vertebrates has remained elusive. Here we demonstrate a crucial role of the vertebrate-specific monothiol multidomain Grx3 (PICOT) in cellular iron homeostasis. During zebrafish embryonic development, depletion of Grx3 severely impairs the maturation of hemoglobin, the major iron-consuming process. Silencing of human Grx3 expression in HeLa cells decreases the activities of several cytosolic Fe/S proteins, for example, iron-regulatory protein 1, a major component of posttranscriptional iron re...
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Papers by Carsten Berndt