scholarly journals Arabidopsis glutathione reductase 2 is indispensable in plastids, while mitochondrial glutathione is safeguarded by additional reduction and transport systems

2019 ◽  
Author(s):  
Laurent Marty ◽  
Daniela Bausewein ◽  
Christopher Müller ◽  
Sajid Ali Khan Bangash ◽  
Anna Moseler ◽  
...  
Keyword(s):  
Glutathione Reductase ◽  
Redox Regulation ◽  
Redox Homeostasis ◽  
Immunogold Labelling ◽  
Transport Systems ◽  
List Type ◽  
Iron Sulfur Cluster ◽  
Thioredoxin System ◽  
Glutathione Redox

SummaryA highly negative glutathione redox potential (EGSH) is maintained in the cytosol, plastids and mitochondria of plant cells to support fundamental processes, including antioxidant defence, redox regulation and iron-sulfur cluster biogenesis. Out of two glutathione reductase (GR) proteins in Arabidopsis, GR2 is predicted to be dual-targeted to plastids and mitochondria, but its differential roles in these organelles remain unclear.We dissected the role of GR2 in organelle glutathione redox homeostasis and plant development using a combination of genetic complementation and stacked mutants, biochemical activity studies, immunogold labelling and in vivo biosensing.Our data demonstrate that GR2 is dual-targeted to plastids and mitochondria, but embryo lethality of gr2 null mutants is caused specifically in plastids. Whereas lack of mitochondrial GR2 leads to a partially oxidised glutathione pool in the matrix, the ABC transporter ATM3 and the mitochondrial thioredoxin system provide functional backup and maintain plant viability.We identify GR2 as essential in the plastid stroma, where it counters GSSG accumulation and developmental arrest. By contrast a functional triad of GR2, ATM3 and the thioredoxin system in the mitochondria provides resilience to excessive glutathione oxidation.

scholarly journals AMPKα1 confers survival advantage of colorectal cancer cells under metabolic stress by promoting redox balance through the regulation of glutathione reductase phosphorylation

Oncogene ◽  
2019 ◽  
Vol 39 (3) ◽  
pp. 637-650 ◽  
Author(s):  
Ying-Nan Wang ◽  
Yun-Xin Lu ◽  
Jie Liu ◽  
Ying Jin ◽  
Hui-Chang Bi ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Glutathione Reductase ◽  
Redox Regulation ◽  
Redox Homeostasis ◽  
Metabolic Stress ◽  
Redox Balance ◽  
Underlying Mechanisms ◽  
High Level

Abstract Patients with stage II or III colorectal cancer (CRC) exhibit various clinical outcomes after radical treatments. The 5-year survival rate was between 50 and 87%. However, the underlying mechanisms of the variation remain unclear. Here we show that AMPKα1 is overexpressed in CRC patient specimens and the high expression is correlated with poor patient survival. We further reveal a previously unrecognized function of AMPKα1, which maintains high level of reduced glutathione to keep reduction–oxidation reaction (redox) homeostasis under stress conditions, thus promoting CRC cell survival under metabolic stress in vitro and enhancing tumorigenesis in vivo. Mechanistically, AMPKα1 regulate the glutathione reductase (GSR) phosphorylation possibly through residue Thr507 which enhances its activity. Suppression of AMPKα1 by using nano-sized polymeric vector induces a favorable therapeutic effect, especially when in combination with oxaliplatin. Our study uncovers a novel function of AMPKα1 in redox regulation and identifies a promising therapeutic strategy for treatment of CRC.

scholarly journals Endoplasmic reticulum oxidoreductin (ERO) provides resilience against reductive stress and hypoxic conditions by mediating luminal redox dynamics

2021 ◽  
Author(s):  
Jose Manuel Ugalde ◽  
Isabel Aller ◽  
Lika Kudrjasova ◽  
Romy Schmidt ◽  
Michelle Schloesser ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Folding ◽  
Redox Homeostasis ◽  
Midpoint Potential ◽  
Oxidative Protein Folding ◽  
Reductive Stress ◽  
Hypoxic Conditions ◽  
Glutathione Redox ◽  
Redox Dynamics

Oxidative protein folding in the endoplasmic reticulum (ER) depends on the coordinated action of protein disulfide isomerases and ER oxidoreductins (EROs). Strict dependence of ERO activity on molecular oxygen as the final electron acceptor implies that oxidative protein folding and other ER processes are severely compromised under hypoxia. While many key players involved in oxidative protein folding are known, our understanding of how redox homeostasis in the ER is maintained and how EROs, the Cys residues of nascent proteins, and the luminal glutathione redox buffer interact is limited. Here, we isolated viable ero1 ero2 double mutants largely deficient in ERO activity, which rendered the mutants highly sensitive to reductive stress and hypoxia. To elucidate the specific redox dynamics in the ER lumen in vivo, we expressed the glutathione redox potential (EGSH) sensor Grx1-roGFP2iL-HDEL with a midpoint potential of -240 mV in the ER of Arabidopsis plants. We found EGSH values of -241 mV in wild-type plants, which is less oxidizing than previously estimated. In the ero1 ero2 mutants, luminal EGSH was reduced further to -253 mV. Recovery to reductive ER stress, as induced by acute exposure to dithiothreitol, was delayed in ero1 ero2 mutants. The characteristic signature of EGSH dynamics in the ER lumen triggered by hypoxia was affected in the ero1 ero2 mutant reflecting a disrupted balance of reductive and oxidizing inputs, including nascent polypeptides and glutathione entry. The ER redox dynamics can now be dissected in vivo, revealing a central role of EROs as major redox integrators to promote luminal redox homeostasis.

scholarly journals Enhancing autophagy by redox regulation extends lifespan in Drosophila

2019 ◽  
Author(s):  
Helena M. Cochemé ◽  
Ivana Bjedov ◽  
Sebastian Grönke ◽  
Katja E. Menger ◽  
Andrew M. James ◽  
...  
Keyword(s):  
Redox Regulation ◽  
Redox Homeostasis ◽  
Model Organism ◽  
Fruit Fly ◽  
Cysteine Residue ◽  
Lifespan Extension ◽  
Post Translational Modification ◽  
Redox Signalling ◽  
Age Related

Redox signalling is an important modulator of diverse biological pathways and processes, and operates through specific post-translational modification of redox-sensitive thiols on cysteine residues 1–4. Critically, redox signalling is distinct from irreversible oxidative damage and functions as a reversible ‘redox switch’ to regulate target proteins. H2O2 acts as the major effector of redox signalling, both directly and through intracellular thiol redox relays 5,6. Dysregulation of redox homeostasis has long been implicated in the pathophysiology of many age-related diseases, as well as in the ageing process itself, however the underlying mechanisms remain largely unclear 7,8. To study redox signalling by H2O2in vivo and explore its involvement in metabolic health and longevity, we used the fruit fly Drosophila as a model organism, with its tractable lifespan and strong evolutionary conservation with mammals 9. Here we report that inducing an endogenous redox-shift, by manipulating levels of the H2O2-degrading enzyme catalase, improves health and robustly extends lifespan in flies, independently of oxidative stress resistance and dietary restriction. We find that the catalase redox-shifted flies are acutely sensitive to starvation stress, which relies on autophagy as a vital survival mechanism. Importantly, we show that autophagy is essential for the lifespan extension of the catalase flies. Furthermore, using redox-inactive knock-in mutants of Atg4a, a major effector of autophagy, we show that the lifespan extension in response to catalase requires a key redox-regulatory cysteine residue, Cys102 in Atg4a. These findings demonstrate that redox regulation of autophagy can extend lifespan, confirming the importance of redox signalling in ageing and as a potential pro-longevity target.

scholarly journals Chloroplasts Require Glutathione Reductase to Balance Reactive Oxygen Species and Maintain Efficient Photosynthesis

2019 ◽  
Author(s):  
Stefanie J. Müller-Schüssele ◽  
Ren Wang ◽  
Desirée D. Gütle ◽  
Jill Romer ◽  
Marta Rodriguez-Franco ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Plant Growth ◽  
Glutathione Reductase ◽  
Critical Role ◽  
Reactive Oxygen ◽  
List Type ◽  
Oxygen Species ◽  
Protein Repair ◽  
Glutathione Redox

SummaryThiol-based redox-regulation is vital to coordinate chloroplast functions depending on illumination. Yet, how the redox-cascades of the thioredoxin and glutathione redox machineries integrate metabolic regulation and reactive oxygen species (ROS) detoxification remains largely unresolved. We investigate if maintaining a highly reducing stromal glutathione redox potential (EGSH) via glutathione reductase (GR) is necessary for functional photosynthesis and plant growth.Since absence of the plastid/mitochondrial GR is embryo-lethal in Arabidopsis thaliana, we used the model moss Physcomitrella patens to create knock-out lines. We dissect the role of GR in chloroplasts by in vivo monitoring stromal EGSH dynamics, and reveal changes in protein abundances by metabolic labelling.Whereas stromal EGSH is highly reducing in wildtype and clearly responsive to light, the absence of GR leads to a partial oxidation, which is not rescued by light. Photosynthetic performance and plant growth are decreased with increasing light intensities, while ascorbate and zeaxanthin levels are elevated. An adjustment of chloroplast proteostasis is pinpointed by the induction of plastid protein repair and degradation machineries.Our results indicate that the plastid thioredoxin and glutathione redox systems operate largely independently. They reveal a critical role of GR in maintaining efficient photosynthesis.

scholarly journals Loss of glutathione redox homeostasis impairs proteostasis by inhibiting autophagy-dependent protein degradation

2018 ◽  
Author(s):  
David Guerrero-Gómez ◽  
José Antonio Mora-Lorca ◽  
Beatriz Sáenz-Narciso ◽  
Francisco José Naranjo-Galindo ◽  
Fernando Muñoz-Lobato ◽  
...  
Keyword(s):  
Protein Aggregation ◽  
Glutathione Reductase ◽  
Mammalian Cells ◽  
Nuclear Translocation ◽  
Redox Homeostasis ◽  
Redox Status ◽  
C Elegans ◽  
Physiological Importance ◽  
Dramatic Shift ◽  
Glutathione Redox

ABSTRACTIn the presence of aggregation-prone proteins, the cytosol and endoplasmic reticulum (ER) undergo a dramatic shift in their respective redox status, with the cytosol becoming more oxidized and the ER more reducing. However, whether and how changes in the cellular redox status may affect protein aggregation is unknown. Here, we show that C. elegans mutants lacking glutathione reductase gsr-1 gene enhance the deleterious phenotypes of heterologous human as well as endogenous worm aggregation-prone proteins. These effects are phenocopied by the GSH depleting agent diethyl maleate. Additionally, gsr-1 mutants abolish the nuclear translocation of HLH-30/TFEB transcription factor, a key inducer of autophagy, and strongly impair the degradation of the autophagy substrate p62/SQST-1::GFP, revealing glutathione reductase may have a role in the clearance of protein aggregates by autophagy. Blocking autophagy in gsr-1 worms expressing aggregation-prone proteins results in strong synthetic developmental phenotypes and lethality, supporting the physiological importance of glutathione reductase in the regulation of misfolded protein clearance. Furthermore, impairing redox homeostasis in both yeast and mammalian cells induces toxicity phenotypes associated with protein aggregation. Together, our data reveal that glutathione redox homeostasis may be central to proteostasis maintenance through autophagy regulation.

scholarly journals Evaluation of CBSX Proteins as Regulators of the Chloroplast Thioredoxin System

2021 ◽  
Vol 12 ◽  
Author(s):  
Ryota Murai ◽  
Yuki Okegawa ◽  
Nozomi Sato ◽  
Ken Motohashi
Keyword(s):  
Redox Regulation ◽  
Light Conditions ◽  
Wild Type ◽  
Target Proteins ◽  
Thioredoxin System ◽  
Biochemical Studies ◽  
Metabolic Reactions ◽  
Normal Light

The chloroplast-localized cystathionine β-synthase X (CBSX) proteins CBSX1 and CBSX2 have been proposed as modulators of thioredoxins (Trxs). In this study, the contribution of CBSX proteins to the redox regulation of thiol enzymes in the chloroplast Trx system was evaluated both in vitro and in vivo. The in vitro biochemical studies evaluated whether CBSX proteins alter the specificities of classical chloroplastic Trx f and Trx m for their target proteins. However, addition of CBSX proteins did not alter the specificities of Trx f and Trx m for disulfide bond reduction of the photosynthesis-related major thiol enzymes, FBPase, SBPase, and NADP-MDH. In vivo analysis showed that CBSX-deficient mutants grew similarly to wild type plants under continuous normal light conditions and that CBSX deficiency did not affect photo-reduction of photosynthesis-related thiol enzymes by Trx system at several light intensities. Although CBSX proteins have been suggested as modulators in the chloroplast Trx system, our results did not support this model, at least in the cases of FBPase, SBPase, and NADP-MDH in leaves. However, fresh weights of the cbsx2 mutants were decreased under short day. Since Trxs regulate many proteins participating in various metabolic reactions in the chloroplast, CBSX proteins may function to regulate other chloroplast Trx target proteins, or serve as modulators in non-photosynthetic plastids of flowers. As a next stage, further investigations are required to understand the modulation of Trx-dependent redox regulation by plastidal CBSX proteins.

scholarly journals Mammalian thioredoxin reductase 1: roles in redox homoeostasis and characterization of cellular targets

2010 ◽  
Vol 430 (2) ◽  
pp. 285-293 ◽  
Author(s):  
Anton A. Turanov ◽  
Sebastian Kehr ◽  
Stefano M. Marino ◽  
Min-Hyuk Yoo ◽  
Bradley A. Carlson ◽  
...  
Keyword(s):  
Redox Regulation ◽  
Thioredoxin Reductase ◽  
In Vitro Assays ◽  
Mouse Serum ◽  
Main Function ◽  
Major Pathway ◽  
Thioredoxin System

The classical Trx (thioredoxin) system, composed of TR (Trx reductase), Trx and NADPH, defines a major pathway of cellular thiol-based redox regulation. Three TRs have been identified in mammals: (i) cytosolic TR1, (ii) mitochondrial TR3 and (iii) testes-specific TGR (Trx-glutathione reductase). All three are selenocysteine-containing enzymes with broad substrate specificity in in vitro assays, but which protein substrates are targeted by TRs in vivo is not well understood. In the present study, we used a mechanism-based approach to characterize the molecular targets of TR1. Cytosolic Trx1 was the major target identified in rat and mouse liver, as well as in rat brain and mouse serum. The results suggest that the main function of TR1 is to reduce Trx1. We also found that TR1-based affinity resins provide a convenient tool for specific isolation of Trxs from a variety of biological samples. To better assess the role of TRs in redox homoeostasis, we comparatively analysed TR1- and TR3-knockdown cells. Although cells deficient in TR1 were particularly sensitive to diamide, TR3-knockdown cells were more sensitive to hydrogen peroxide. To further examine the TR1–Trx1 redox pair, we used mice with a liver-specific knockout of selenocysteine tRNA. In this model, selenocysteine insertion into TR1 was blocked, but the truncated form of this protein was not detected. Instead, TR1 and TR3 levels were decreased in the knockout samples. Diminished hepatic TR1 function was associated with elevated Trx1 levels, but this protein was mostly in the oxidized state. Overall, this study provides evidence for the key role of the TR1–Trx1 pair in redox homoeostasis.

scholarly journals Redox regulation of PTPN22 affects the severity of T cell dependent autoimmune inflammation

2021 ◽  
Author(s):  
Jaime James ◽  
Yifei Chen ◽  
Clara M. Hernandez ◽  
Florian Forster ◽  
Markus Dagnell ◽  
...  
Keyword(s):  
T Cell ◽  
Redox Regulation ◽  
Protein Tyrosine Phosphatases ◽  
Functional Results ◽  
Cell Receptor ◽  
Tcr Signaling ◽  
Complex Activity ◽  
Autoimmune Inflammation ◽  
Thioredoxin System

AbstractChronic autoimmune diseases are associated with mutations in PTPN22, a modifier of T cell receptor signaling. As with all protein tyrosine phosphatases the activity of PTPN22 is redox regulated, but if or how such regulation can modulate inflammatory pathways in vivo is not known. To determine this, we created a mouse with a cysteine-to-serine mutation at position 129 in PTPN22 (C129S), a residue proposed to alter the redox regulatory properties of PTPN22 by forming a disulfide with the catalytic C227 residue. The C129S mutant mouse showed a stronger T cell-dependent inflammatory response and development of T cell dependent autoimmune arthritis due to enhanced TCR signaling and activation of T cells, an effect neutralized by a mutation in Ncf1, a component of the NOX2 complex. Activity assays with purified proteins suggest that the functional results can be explained by an increased sensitivity to oxidation of the C129S mutated PTPN22 protein. We also observed that the disulfide of native PTPN22 can be directly reduced by the thioredoxin system, while the C129S mutant lacking this disulfide was less amenable to reductive reactivation. In conclusion, we show that PTPN22 functionally interacts with Ncf1 and is regulated by oxidation via the non-catalytic C129 residue and oxidation-prone PTPN22 leads to increased severity in the development of T cell-dependent autoimmunity.Significance statementA hitherto unstudied aspect of PTPN22 biology is its regulation by cell redox states. Here we created a mouse model where PTPN22 was mutated to respond differentially to redox levels in vivo and found that PTPN22 function is regulated by reactive oxygen species and that redox regulation of PTPN22 impacts T-cell-dependent autoimmune inflammation.

LACK OF EFFECT OF CORTICOSTEROIDS ON THE IN VIVO DISAPPEARANCE OF SULFHYDRYL-INHIBITED AND ANTIBODY-COATED ERYTHROCYTES

1964 ◽  
Vol 47 (3_Suppl) ◽  
pp. S28-S36
Author(s):  
Kailash N. Agarwal
Keyword(s):  
Red Cells ◽  
List Type ◽  
Red Cell

ABSTRACT Red cells were incubated in vitro with sulfhydryl inhibitors and Rhantibody with and without prior incubation with prednisolone-hemisuccinate. These erythrocytes were labelled with Cr51 and P32 and their disappearance in vivo after autotransfusion was measured. Prior incubation with prednisolone-hemisuccinate had no effect on the rate of red cell disappearance. The disappearance of the cells was shown to take place without appreciable intravascular destruction.

STUDIES IN CONGENITAL GENERALIZED LIPODYSTROPHY

1973 ◽  
Vol 72 (3) ◽  
pp. 495-505 ◽  
Author(s):  
Oddmund Søvik ◽  
Svein Oseid
Keyword(s):  
Biological Activity ◽  
Insulin Response ◽  
Epididymal Adipose Tissue ◽  
Large Individual ◽  
Immunoreactive Insulin ◽  
List Type ◽  
Glucose Load ◽  
Congenital Generalized Lipodystrophy ◽  
The One

ABSTRACT The biological activity of plasma insulin from 4 cases of congenital generalized lipodystrophy has been studied, using rat diaphragm and epididymal adipose tissue in vivo. The results are compared with previous data on plasma immunoreactive insulin obtained in these patients. 2 of the 4 cases exhibited unusually high biological insulin activities during the fasting state as well as after an intravenous (iv) glucose load. In the fat pad assay activities as high as 10 000 μU insulin per ml were observed. During childhood the biological insulin activities were generally high, although there were large individual variations. However, in the one case studied after the age of puberty, the insulin response to a glucose load was negligible. Taken together, the biological and immunological activities observed strongly suggest the presence of pancreatic insulin in these patients. It appears that the circulating insulin has a fully biological activity. The decreasing insulin activities after cessation of growth are in agreement with the appearance of frank diabetes at this time.

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