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1.
Sci Rep ; 13(1): 12794, 2023 08 07.
Article En | MEDLINE | ID: mdl-37550331

The role of iron in the two major sites of adaptive thermogenesis, namely the beige inguinal (iWAT) and brown adipose tissues (BAT) has not been fully understood yet. Body iron levels and distribution is controlled by the iron regulatory peptide hepcidin. Here, we explored iron homeostasis and thermogenic activity in brown and beige fat in wild-type and iron loaded Hepcidin KO mice. Hepcidin-deficient mice displayed iron overload in both iWAT and BAT, and preferential accumulation of ferritin in stromal cells compared to mature adipocytes. In contrast to BAT, the iWAT of Hepcidin KO animals featured with defective thermogenesis evidenced by an altered beige signature, including reduced UCP1 levels and decreased mitochondrial respiration. This thermogenic modification appeared cell autonomous and persisted after a 48 h-cold challenge, a potent trigger of thermogenesis, suggesting compromised de novo adipogenesis. Given that WAT browning occurs in both mice and humans, our results provide physiological results to interrogate the thermogenic capacity of patients with iron overload disorders.


Adipogenesis , Hepcidins , Animals , Mice , Adipose Tissue, Brown , Adipose Tissue, White , Hepcidins/genetics , Iron , Mice, Inbred C57BL , Thermogenesis , Uncoupling Protein 1/genetics
2.
Nat Commun ; 14(1): 2594, 2023 05 05.
Article En | MEDLINE | ID: mdl-37147287

Brown adipose tissue expresses uncoupling protein 1 (UCP1), which dissipates energy as heat, making it a target for treating metabolic disorders. Here, we investigate how purine nucleotides inhibit respiration uncoupling by UCP1. Our molecular simulations predict that GDP and GTP bind UCP1 in the common substrate binding site in an upright orientation, where the base moiety interacts with conserved residues R92 and E191. We identify a triplet of uncharged residues, F88/I187/W281, forming hydrophobic contacts with nucleotides. In yeast spheroplast respiration assays, both I187A and W281A mutants increase the fatty acid-induced uncoupling activity of UCP1 and partially suppress the inhibition of UCP1 activity by nucleotides. The F88A/I187A/W281A triple mutant is overactivated by fatty acids even at high concentrations of purine nucleotides. In simulations, E191 and W281 interact with purine but not pyrimidine bases. These results provide a molecular understanding of the selective inhibition of UCP1 by purine nucleotides.


Ion Channels , Membrane Proteins , Ion Channels/genetics , Ion Channels/metabolism , Uncoupling Protein 1/genetics , Uncoupling Protein 1/metabolism , Membrane Proteins/metabolism , Mitochondrial Proteins/metabolism , Fatty Acids/metabolism , Purine Nucleotides/metabolism , Adipose Tissue, Brown/metabolism , Saccharomyces cerevisiae/metabolism
3.
Antioxidants (Basel) ; 12(3)2023 Feb 27.
Article En | MEDLINE | ID: mdl-36978834

The protective effects of hydrogen sulphide (H2S) to limit oxidative injury and preserve mitochondrial function during sepsis, ischemia/reperfusion, and neurodegenerative diseases have prompted the development of soluble H2S-releasing compounds such as GYY4137. Yet, the effects of GYY4137 on the mitochondrial function of endothelial cells remain unclear, while this cell type comprises the first target cell after parenteral administration. Here, we specifically assessed whether human endothelial cells possess a functional sulfide:quinone oxidoreductase (SQOR), to oxidise GYY4137-released H2S within the mitochondria for electron donation to the electron transport chain. We demonstrate that H2S administration increases oxygen consumption by human umbilical vein endothelial cells (HUVECs), which does not occur in the SQOR-deficient cell line SH-SY5Y. GYY4137 releases H2S in HUVECs in a dose- and time-dependent fashion as quantified by oxygen consumption and confirmed by lead acetate assay, as well as AzMC fluorescence. Scavenging of intracellular H2S using zinc confirmed intracellular and intramitochondrial sulfur, which resulted in mitotoxic zinc sulfide (ZnS) precipitates. Together, GYY4137 increases intramitochondrial H2S and boosts oxygen consumption of endothelial cells, which is likely governed via the oxidation of H2S by SQOR. This mechanism in endothelial cells may be instrumental in regulating H2S levels in blood and organs but can also be exploited to quantify H2S release by soluble donors such as GYY4137 in living systems.

4.
Int J Mol Sci ; 24(4)2023 Feb 17.
Article En | MEDLINE | ID: mdl-36835457

Succinate dehydrogenase (SDH) is one of the enzymes of the tricarboxylic acid cycle (Krebs cycle) and complex II of the mitochondrial respiratory chain. A class of fungicides (SDHIs) targets the complex II reaction in the SDH. A large number of those in use have been shown to inhibit SDH in other phyla, including humans. This raises questions about possible effects on human health and non-target organisms in the environment. The present document will address metabolic consequences in mammals; it is neither a review on SDH nor is it about the toxicology of SDHIs. Most clinically relevant observations are linked to a severe decrease in SDH activity. Here we shall examine the mechanisms for compensating a loss of SDH activity and their possible weaknesses or adverse consequences. It can be expected that a mild inhibition of SDH will be compensated by the kinetic properties of this enzyme, but this implies a proportionate increase in succinate concentration. This would be relevant for succinate signaling and epigenetics (not reviewed here). With regard to metabolism, exposure of the liver to SDHIs would increase the risk for non-alcoholic fatty liver disease (NAFLD). Higher levels of inhibition may be compensated by modification of metabolic fluxes with net production of succinate. SDHIs are much more soluble in lipids than in water; consequently, a different diet composition between laboratory animals and humans is expected to influence their absorption.


Fungicides, Industrial , Pesticides , Animals , Humans , Succinate Dehydrogenase/metabolism , Fungicides, Industrial/pharmacology , Energy Metabolism , Succinates , Mammals/metabolism
5.
Nat Commun ; 13(1): 5956, 2022 10 11.
Article En | MEDLINE | ID: mdl-36220814

HIV-1 eradication is hindered by viral persistence in cell reservoirs, established not only in circulatory CD4+T-cells but also in tissue-resident macrophages. The nature of macrophage reservoirs and mechanisms of persistence despite combined anti-retroviral therapy (cART) remain unclear. Using genital mucosa from cART-suppressed HIV-1-infected individuals, we evaluated the implication of macrophage immunometabolic pathways in HIV-1 persistence. We demonstrate that ex vivo, macrophage tissue reservoirs contain transcriptionally active HIV-1 and viral particles accumulated in virus-containing compartments, and harbor an inflammatory IL-1R+S100A8+MMP7+M4-phenotype prone to glycolysis. Reactivation of infectious virus production and release from these reservoirs in vitro are induced by the alarmin S100A8, an endogenous factor produced by M4-macrophages and implicated in "sterile" inflammation. This process metabolically depends on glycolysis. Altogether, inflammatory M4-macrophages form a major tissue reservoir of replication-competent HIV-1, which reactivate viral production upon autocrine/paracrine S100A8-mediated glycolytic stimulation. This HIV-1 persistence pathway needs to be targeted in future HIV eradication strategies.


HIV Infections , HIV-1 , Alarmins , Anti-Retroviral Agents/therapeutic use , CD4-Positive T-Lymphocytes , Calgranulin A , HIV Infections/drug therapy , HIV-1/physiology , Humans , Macrophages , Matrix Metalloproteinase 7/pharmacology , Matrix Metalloproteinase 7/therapeutic use , Virus Latency , Virus Replication
6.
Biomolecules ; 12(3)2022 02 24.
Article En | MEDLINE | ID: mdl-35327553

The present article will not attempt to deal with sulfide per se as a signaling molecule but will aim to examine the consequences of sulfide oxidation by mitochondrial sulfide quinone reductase in mammalian cells. This oxidation appears first as a priority to avoid self-poisoning by endogenous sulfide and second to occur with the lowest ATP/O2 ratio when compared to other mitochondrial substrates. This is explained by the injection of electrons in the respiratory chain after complex I (as for succinate) and by a sulfur oxidation step implying a dioxygenase that consumes oxygen but does not contribute to mitochondrial bioenergetics. Both contribute to increase cellular oxygen consumption if sulfide is provided below its toxic level (low µM). Accordingly, if oxygen supply or respiratory chain activity becomes a limiting factor, small variations in sulfide release impact the cellular ATP/ADP ratio, a major metabolic sensor.


Mitochondria , Oxygen , Adenosine Triphosphate/metabolism , Animals , Electron Transport , Mammals/metabolism , Mitochondria/metabolism , Oxidation-Reduction , Oxygen/metabolism , Oxygen Consumption , Sulfides/metabolism
7.
Int J Mol Sci ; 22(20)2021 Oct 19.
Article En | MEDLINE | ID: mdl-34681924

Cyclic fertilin peptide (cFEE: phenylalanine, glutamic acid; glutamic acid) improves gamete interaction in humans. We investigate whether it could be via improvement of sperm movement parameters and their mitochondrial ATP production. Sperm movement parameters were studied using computer-assisted sperm analysis (CASA) in sperm samples from 38 patients with normal sperm in medium supplemented with cyclic fertilin against a control group. Sperm mitochondrial functions were studied using donor's sperm, incubated or not with cFEE. It was evaluated by the measurement of their ATP production using bioluminescence, their respiration by high resolution oxygraphy, and of mitochondrial membrane potential (MMP) using potentiometric dyes and flow cytometry. cFEE significantly improved sperm movement parameters and percentage of hyperactivated sperm. Impact of inhibitors showed OXPHOS as the predominant energy source for sperm movement. However, cFEE had no significant impact on any of the analyzed mitochondrial bioenergetic parameters, suggesting that it could act via a more efficient use of its energy resources.


Mitochondria/metabolism , Peptides, Cyclic/pharmacology , Spermatozoa/physiology , Adenosine Triphosphate/metabolism , Energy Metabolism , Humans , Luminescent Measurements , Male , Membrane Potential, Mitochondrial/drug effects , Membranes/metabolism , Mitochondria/drug effects , Oxidative Phosphorylation , Sperm Motility/drug effects , Spermatozoa/drug effects
8.
Biology (Basel) ; 10(10)2021 Oct 04.
Article En | MEDLINE | ID: mdl-34681099

Cellular bioenergetics requires an intense ATP turnover that is increased further by hypermetabolic states caused by cancer growth or inflammation. Both are associated with metabolic alterations and, notably, enhancement of the Warburg effect (also known as aerobic glycolysis) of poor efficiency with regard to glucose consumption when compared to mitochondrial respiration. Therefore, beside this efficiency issue, other properties of these two pathways should be considered to explain this paradox: (1) biosynthesis, for this only indirect effect should be considered, since lactate release competes with biosynthetic pathways in the use of glucose; (2) ATP production, although inefficient, glycolysis shows other advantages when compared to mitochondrial respiration and lactate release may therefore reflect that the glycolytic flux is higher than required to feed mitochondria with pyruvate and glycolytic NADH; (3) Oxygen supply becomes critical under hypermetabolic conditions, and the ATP/O2 ratio quantifies the efficiency of oxygen use to regenerate ATP, although aerobic metabolism remains intense the participation of anaerobic metabolisms (lactic fermentation or succinate generation) could greatly increase ATP/O2 ratio; (4) time and space constraints would explain that anaerobic metabolism is required while the general metabolism appears oxidative; and (5) active repression of respiration by glycolytic intermediates, which could ensure optimization of glucose and oxygen use.

9.
FEBS J ; 288(9): 3024-3033, 2021 05.
Article En | MEDLINE | ID: mdl-33202085

Uncoupling protein 1 (UCP1) is found in the inner mitochondrial membrane of brown adipocytes. In the presence of long-chain fatty acids (LCFAs), UCP1 increases the proton conductance, which, in turn, increases fatty acid oxidation and energy release as heat. Atomic models of UCP1 and UCP2 have been generated based on the NMR backbone structure of UCP2 in dodecylphosphocholine (DPC), a detergent known to inactivate UCP1. Based on NMR titration experiments on UCP1 with LCFA, it has been proposed that K56 and K269 are crucial for LCFA binding and UCP1 activation. Given the numerous controversies on the use of DPC for structure-function analyses of membrane proteins, we revisited those UCP1 mutants in a more physiological context by expressing them in the mitochondria of Saccharomyces cerevisiae. Mitochondrial respiration, assayed on permeabilized spheroplasts, enables the determination of UCP1 activation and inhibition. The K56S, K269S, and K56S/K269S mutants did not display any default in activation, which shows that the NMR titration experiments in DPC detergent are not relevant to UCP1 function.


Adipocytes, Brown/ultrastructure , Mitochondrial Uncoupling Proteins/ultrastructure , Protein Conformation , Uncoupling Protein 1/ultrastructure , Adipocytes, Brown/metabolism , Animals , Fatty Acids/genetics , Fatty Acids/metabolism , Humans , Ion Channels/genetics , Mitochondrial Membranes/metabolism , Mitochondrial Membranes/ultrastructure , Mitochondrial Uncoupling Proteins/chemistry , Models, Structural , Oxygen Consumption/genetics , Phosphorylcholine/analogs & derivatives , Phosphorylcholine/chemistry , Protons , Rats , Saccharomyces cerevisiae , Structure-Activity Relationship , Uncoupling Protein 1/chemistry , Uncoupling Protein 1/genetics
10.
Int J Mol Sci ; 21(23)2020 Nov 30.
Article En | MEDLINE | ID: mdl-33266350

Addition of hydrogen peroxide (H2O2) is a method commonly used to trigger cellular oxidative stress. However, the doses used (often hundreds of micromolar) are disproportionally high with regard to physiological oxygen concentration (low micromolar). In this study using polarographic measurement of oxygen concentration in cellular suspensions we show that H2O2 addition results in O2 release as expected from catalase reaction. This reaction is fast enough to, within seconds, decrease drastically H2O2 concentration and to annihilate it within a few minutes. Firstly, this is likely to explain why recording of oxidative damage requires the high concentrations found in the literature. Secondly, it illustrates the potency of intracellular antioxidant (H2O2) defense. Thirdly, it complicates the interpretation of experiments as subsequent observations might result from high/transient H2O2 exposure and/or from the diverse possible consequences of the O2 release.


Catalase/metabolism , Hydrogen Peroxide/metabolism , Oxidative Stress , Aconitate Hydratase/metabolism , Cell Respiration , DNA Breaks , Enzyme Activation , Humans , Models, Biological , Oxidation-Reduction , Reactive Oxygen Species/metabolism
11.
FASEB J ; 34(1): 222-236, 2020 01.
Article En | MEDLINE | ID: mdl-31914644

Hyperosmotic conditions are associated to several pathological states. In this article, we evaluate the consequence of hyperosmotic medium on cellular energy metabolism. We demonstrate that exposure of cells to hyperosmotic conditions immediately reduces the mitochondrial oxidative phosphorylation rate. This causes an increase in glycolysis, which represses further respiration. This is known as the Warburg or Crabtree effect. In addition to aerobic glycolysis, we observed two other cellular responses that would help to preserve cellular ATP level and viability: A reduction in the cellular ATP turnover rate and a partial mitochondrial uncoupling which is expected to enhance ATP production by Krebs cycle. The latter is likely to constitute another metabolic adaptation to compensate for deficient oxidative phosphorylation that, importantly, is not dependent on glucose.


Neuroblastoma/metabolism , Oxygen Consumption/physiology , Animals , CHO Cells , Cell Line, Tumor , Cell Survival , Cricetinae , Cricetulus , Energy Metabolism , HEK293 Cells , Humans , Male , Mitochondria/metabolism , Rats , Rats, Wistar
12.
Cell Rep ; 28(9): 2306-2316.e5, 2019 08 27.
Article En | MEDLINE | ID: mdl-31461648

Colorectal cancer (CRC) is associated with metabolic and redox perturbation. The mitochondrial transporter uncoupling protein 2 (UCP2) controls cell proliferation in vitro through the modulation of cellular metabolism, but the underlying mechanism in tumors in vivo remains unexplored. Using murine intestinal cancer models and CRC patient samples, we find higher UCP2 protein levels in tumors compared to their non-tumoral counterparts. We reveal the tumor-suppressive role of UCP2 as its deletion enhances colon and small intestinal tumorigenesis in AOM/DSS-treated and ApcMin/+ mice, respectively, and correlates with poor survival in the latter model. Mechanistically, UCP2 loss increases levels of oxidized glutathione and proteins in tumors. UCP2 deficiency alters glycolytic pathways while promoting phospholipid synthesis, thereby limiting the availability of NADPH for buffering oxidative stress. We show that UCP2 loss renders colon cells more prone to malignant transformation through metabolic reprogramming and perturbation of redox homeostasis and could favor worse outcomes in CRC.


Carcinogenesis/genetics , Colorectal Neoplasms/metabolism , Lipogenesis , NADP/metabolism , Oxidative Stress , Uncoupling Protein 2/metabolism , Aged , Aged, 80 and over , Animals , Carcinogenesis/metabolism , Colon/metabolism , Colon/pathology , Colorectal Neoplasms/genetics , Colorectal Neoplasms/pathology , Glycolysis , Humans , Intestine, Small/metabolism , Intestine, Small/pathology , Male , Mice , Mice, Inbred C57BL , Middle Aged , Uncoupling Protein 2/genetics
13.
Sci Rep ; 9(1): 11360, 2019 08 06.
Article En | MEDLINE | ID: mdl-31388052

The aim of the present study was to elucidate the in vitro short-term (2-h) and longer-term (24-h) effects of hyperosmolar media (500 and 680 mOsm/L) on intestinal epithelial cells using the human colonocyte Caco-2 cell line model. We found that a hyperosmolar environment slowed down cell proliferation compared to normal osmolarity (336 mOsm/L) without inducing cell detachment or necrosis. This was associated with a transient reduction of cell mitochondrial oxygen consumption, increase in proton leak, and decrease in intracellular ATP content. The barrier function of Caco-2 monolayers was also transiently affected since increased paracellular apical-to-basal permeability and modified electrolyte permeability were measured, allowing partial equilibration of the trans-epithelial osmotic difference. In addition, hyperosmotic stress induced secretion of the pro-inflammatory cytokine IL-8. By measuring expression of genes involved in energy metabolism, tight junction forming, electrolyte permeability and intracellular signaling, different response patterns to hyperosmotic stress occurred depending on its intensity and duration. These data highlight the potential impact of increased luminal osmolarity on the intestinal epithelium renewal and barrier function and point out some cellular adaptive capacities towards luminal hyperosmolar environment.


Cell Proliferation , Enterocytes/metabolism , Mitochondria/metabolism , Osmolar Concentration , Oxygen Consumption , Caco-2 Cells , Enterocytes/physiology , Humans , Interleukin-8/metabolism , Intestinal Mucosa/metabolism , Intestinal Mucosa/physiopathology , Signal Transduction
14.
PLoS Pathog ; 15(5): e1007669, 2019 05.
Article En | MEDLINE | ID: mdl-31042779

HIV-1 is dependent on the host cell for providing the metabolic resources for completion of its viral replication cycle. Thus, HIV-1 replicates efficiently only in activated CD4+ T cells. Barriers preventing HIV-1 replication in resting CD4+ T cells include a block that limits reverse transcription and also the lack of activity of several inducible transcription factors, such as NF-κB and NFAT. Because FOXO1 is a master regulator of T cell functions, we studied the effect of its inhibition on T cell/HIV-1 interactions. By using AS1842856, a FOXO1 pharmacologic inhibitor, we observe that FOXO1 inhibition induces a metabolic activation of T cells with a G0/G1 transition in the absence of any stimulatory signal. One parallel outcome of this change is the inhibition of the activity of the HIV restriction factor SAMHD1 and the activation of the NFAT pathway. FOXO1 inhibition by AS1842856 makes resting T cells permissive to HIV-1 infection. In addition, we found that FOXO1 inhibition by either AS1842856 treatment or upon FOXO1 knockdown induces the reactivation of HIV-1 latent proviruses in T cells. We conclude that FOXO1 has a central role in the HIV-1/T cell interaction and that inhibiting FOXO1 with drugs such as AS1842856 may be a new therapeutic shock-and-kill strategy to eliminate the HIV-1 reservoir in human T cells.


CD4-Positive T-Lymphocytes/immunology , Forkhead Box Protein O1/antagonists & inhibitors , Gene Expression Regulation , HIV Infections/virology , HIV-1/immunology , Virus Activation/immunology , Virus Replication , Animals , CD4-Positive T-Lymphocytes/virology , Cell Cycle , Forkhead Box Protein O1/genetics , HIV Infections/genetics , HIV Infections/immunology , HIV Infections/metabolism , Humans , Jurkat Cells , Lymphocyte Activation/immunology , Macaca fascicularis , Male , Virus Latency
15.
Toxicol Sci ; 170(1): 82-94, 2019 07 01.
Article En | MEDLINE | ID: mdl-30907955

Our study was aimed at (1) determining the efficacy of the dye methylene blue (MB), following a rapidly lethal cyanide (CN) intoxication in un-sedated rats; (2) clarifying some of the mechanisms responsible for the antidotal properties produced by this potent cyclic redox dye. Sixty-nine awake rats acutely intoxicated by CN (IP, KCN 7 mg/kg) received saline, MB (20 mg/kg) or hydroxocobalamin (HyCo, 150 mg/kg) when in deep coma. Survival in this model was very low, reaching 9% at 60 min without any treatment. Methylene blue significantly increased survival (59%, p < .001) at 60 min, versus 37% with HyCo (p < .01). In addition, 8 urethane-anesthetized rats were exposed to a sublethal CN intoxication (KCN, 0.75 mg/kg/min IV for 4 min); they received MB (20 mg/kg, IV) or saline, 5 min after the end of CN exposure. All MB-treated rats displayed a significant reduction in hyperlactacidemia, a restoration of pyruvate/lactate ratio-a marker of NAD/NADH ratio-and an increase in CO2 production, a marker of the activity of the TCA cycle. These changes were also associated with a 2-fold increase in the pool of CN in red cells. Based on series of in vitro experiments, looking at the effects of MB on NADH, as well as the redox effects of MB on hemoglobin and cytochrome c, we hypothesize that the antidotal properties of MB can in large part be accounted for by its ability to readily restore NAD/NADH ratio and to cyclically re-oxidize then reduce the iron in hemoglobin and the electron chain complexes. All of these effects can account for the rapid antidotal properties of this dye following CN poisoning.


Antidotes/pharmacology , Cyanides/poisoning , Methylene Blue/pharmacology , Animals , Coma/chemically induced , Coma/drug therapy , Coma/metabolism , Cytochromes c/metabolism , Hemoglobins/metabolism , Hydroxocobalamin/pharmacology , Male , Methemoglobin/metabolism , NAD/metabolism , Rats
16.
Mol Pharmacol ; 95(3): 269-285, 2019 03.
Article En | MEDLINE | ID: mdl-30567956

Quinone reductase 2 (QR2, E.C. 1.10.5.1) is an enzyme with a feature that has attracted attention for several decades: in standard conditions, instead of recognizing NAD(P)H as an electron donor, it recognizes putative metabolites of NADH, such as N-methyl- and N-ribosyl-dihydronicotinamide. QR2 has been particularly associated with reactive oxygen species and memory, strongly suggesting a link among QR2 (as a possible key element in pro-oxidation), autophagy, and neurodegeneration. In molecular and cellular pharmacology, understanding physiopathological associations can be difficult because of a lack of specific and powerful tools. Here, we present a thorough description of the potent, nanomolar inhibitor [2-(2-methoxy-5H-1,4b,9-triaza(indeno[2,1-a]inden-10-yl)ethyl]-2-furamide (S29434 or NMDPEF; IC50 = 5-16 nM) of QR2 at different organizational levels. We provide full detailed syntheses, describe its cocrystallization with and behavior at QR2 on a millisecond timeline, show that it penetrates cell membranes and inhibits QR2-mediated reactive oxygen species (ROS) production within the 100 nM range, and describe its actions in several in vivo models and lack of actions in various ROS-producing systems. The inhibitor is fairly stable in vivo, penetrates cells, specifically inhibits QR2, and shows activities that suggest a key role for this enzyme in different pathologic conditions, including neurodegenerative diseases.


Pyridines/pharmacology , Pyrrolizidine Alkaloids/pharmacology , Quinone Reductases/antagonists & inhibitors , Animals , Cell Line, Tumor , Cell Membrane/drug effects , Cell Membrane/metabolism , Hep G2 Cells , Humans , Male , Mice , NAD(P)H Dehydrogenase (Quinone)/metabolism , Rats , Rats, Wistar , Reactive Oxygen Species/metabolism
17.
J Clin Invest ; 128(4): 1671-1687, 2018 04 02.
Article En | MEDLINE | ID: mdl-29447131

Synthetic lethality is an efficient mechanism-based approach to selectively target DNA repair defects. Excision repair cross-complementation group 1 (ERCC1) deficiency is frequently found in non-small-cell lung cancer (NSCLC), making this DNA repair protein an attractive target for exploiting synthetic lethal approaches in the disease. Using unbiased proteomic and metabolic high-throughput profiling on a unique in-house-generated isogenic model of ERCC1 deficiency, we found marked metabolic rewiring of ERCC1-deficient populations, including decreased levels of the metabolite NAD+ and reduced expression of the rate-limiting NAD+ biosynthetic enzyme nicotinamide phosphoribosyltransferase (NAMPT). We also found reduced NAMPT expression in NSCLC samples with low levels of ERCC1. These metabolic alterations were a primary effect of ERCC1 deficiency, and caused selective exquisite sensitivity to small-molecule NAMPT inhibitors, both in vitro - ERCC1-deficient cells being approximately 1,000 times more sensitive than ERCC1-WT cells - and in vivo. Using transmission electronic microscopy and functional metabolic studies, we found that ERCC1-deficient cells harbor mitochondrial defects. We propose a model where NAD+ acts as a regulator of ERCC1-deficient NSCLC cell fitness. These findings open therapeutic opportunities that exploit a yet-undescribed nuclear-mitochondrial synthetic lethal relationship in NSCLC models, and highlight the potential for targeting DNA repair/metabolic crosstalks for cancer therapy.


Carcinoma, Non-Small-Cell Lung/metabolism , DNA Repair , Lung Neoplasms/metabolism , NAD/biosynthesis , Neoplasms, Experimental/metabolism , A549 Cells , Animals , Carcinoma, Non-Small-Cell Lung/genetics , Carcinoma, Non-Small-Cell Lung/pathology , Carcinoma, Non-Small-Cell Lung/therapy , Cytokines/genetics , Cytokines/metabolism , DNA-Binding Proteins/genetics , Endonucleases/genetics , Humans , Lung Neoplasms/genetics , Lung Neoplasms/pathology , Lung Neoplasms/therapy , Mice , Mice, Nude , NAD/genetics , Neoplasm Proteins/genetics , Neoplasm Proteins/metabolism , Neoplasms, Experimental/genetics , Neoplasms, Experimental/pathology , Neoplasms, Experimental/therapy , Nicotinamide Phosphoribosyltransferase/genetics , Nicotinamide Phosphoribosyltransferase/metabolism
18.
Clin Toxicol (Phila) ; 56(9): 828-840, 2018 09.
Article En | MEDLINE | ID: mdl-29451035

BACKGROUND: Although methylene blue (MB) had long been proposed to counteract the effects of cyanide (CN) intoxication, research on its mechanisms of action and efficacy has been abandoned for decades. Recent studies on the benefits of MB in post-anoxic injuries have prompted us to reexamine the relevance of this historical observation. METHODS: Our study was performed in adult male Sprague-Dawley rats and on HEK293T epithelial cells. First, the effects and toxicity of MB (0-80 mg/kg) on circulation and metabolism were established in four urethane-anesthetized rats. Then nine rats received a lethal infusion of a solution of KCN (0.75 mg/kg/min) and were treated by either saline or MB, at 20 mg/kg, a dose that we found to be innocuous in rat and to correspond to a dose of about 4 mg/kg in humans. MB was also administered 5 min after the end of a sub-lethal exposure to CN in a separate group of 10 rats. In addition, ATP/ADP ratio, ROS production, mitochondrial membrane potential (Δψm) and cellular O2 consumption rate (OCR) were determined in HEK293T cells exposed to toxic levels of CN (200 µM for 10 min) before and after applying a solution containing MB (1-100 µM for 10 min). RESULTS: Methylene blue was found to be innocuous up to 50 mg/kg. KCN infusion (0.75 mg/kg/min) killed all animals within 7-8 min. MB (20 mg/kg) administered at the same time restored blood pressure, cardiac contractility and limited O2 deficit, allowing all the animals to survive, without any significant methemoglobinemia. When administered 5 min after a non-lethal CN intoxication, MB sped up the recovery of lactate and O2 deficit. Finally, MB was able to decrease the production of ROS and restore the ATP/ADP ratio, Δψm as well as OCR of epithelial cells intoxicated by CN. CONCLUSIONS: The present observations should make us consider the potential interest of MB in the treatment of CN intoxication. The mechanisms of the antidotal properties of MB cannot be accounted for by the creation of a cyanomethemoglobinemia, rather its protective effects appears to be related to the unique properties of this redox dye, which, depending on the dose, could directly oppose some of the consequences of the metabolic depression produced by CN at the cellular level.


Antidotes/pharmacology , Antidotes/therapeutic use , Cyanides/poisoning , HEK293 Cells/drug effects , Methylene Blue/pharmacology , Methylene Blue/therapeutic use , Poisoning/drug therapy , Animals , Dose-Response Relationship, Drug , Humans , Male , Rats , Rats, Sprague-Dawley
19.
Methods Appl Fluoresc ; 5(1): 015007, 2017 03 22.
Article En | MEDLINE | ID: mdl-28328544

We evaluated our phosphonium-based fluorescent probes for selective staining of mitochondria. Currently used probes for monitoring mitochondrial membrane potential show varying degrees of interference with cell metabolism, photo-induced damage and probe binding. Here presented probes are characterised by highly efficient cellular uptake and specific accumulation in mitochondria. Fluorescent detection of the probes was accomplished using flow cytometry and confocal microscopy imaging of yeast and mammalian cells. Toxicity analysis (impedimetry-xCELLigence for the cellular proliferation and Seahorse technology for respiratory properties) confirms that these dyes exhibit no-toxicity on mitochondrial or cellular functioning even for long time incubation. The excellent chemical and photophysical stability of the dyes makes them promising leads toward improved fluorescent probes. Therefore, the probes described here offer to circumvent the problems associated with existing-probe's limitations.


Fluorescent Dyes/pharmacology , Membrane Potential, Mitochondrial/drug effects , Mitochondria/drug effects , Organophosphorus Compounds/pharmacology , Animals , Cell Line, Tumor , Female , Humans , Mice, Inbred CBA , Microscopy, Confocal , Mitochondria/physiology , Oxygen Consumption/drug effects , Saccharomyces cerevisiae/drug effects , Saccharomyces cerevisiae/physiology
20.
Free Radic Biol Med ; 104: 311-323, 2017 03.
Article En | MEDLINE | ID: mdl-28108277

Microglia fulfill important immunological functions in the brain by responding to pathological stresses and modulating their activities according to pro- or anti-inflammatory stimuli. Recent evidence indicates that changes in metabolism accompany the switch in microglia activation state, favoring glycolysis over oxidative phosphorylation when cells exhibit a pro-inflammatory phenotype. Carbon monoxide (CO), a byproduct of heme breakdown by heme oxygenase, exerts anti-inflammatory action and affects mitochondrial function in cells and tissues. In the present study, we analyzed the metabolic profile of BV2 and primary mouse microglia exposed to the CO-releasing molecules CORM-401 and CORM-A1 and investigated whether CO affects the metabolic adaptation of cells to the inflammatory stimulus lipopolysaccharide (LPS). Microglia respiration and glycolysis were measured using an Extracellular Flux Analyzer to provide a real-time bioenergetic assessment, and biochemical parameters were evaluated to define the metabolic status of the cells under normal or inflammatory conditions. We show that CO prevents LPS-induced depression of microglia respiration and reduction in ATP levels while altering the early expression of inflammatory markers, suggesting the metabolic changes induced by CO are associated with control of inflammation. CO alone affects microglia respiration depending on the concentration, as low levels increase oxygen consumption while higher amounts inhibit respiration. Increased oxygen consumption was attributed to an uncoupling activity observed in cells, at the molecular level (respiratory complex activities) and during challenge with LPS. Thus, application of CO is a potential countermeasure to reverse the metabolic changes that occur during microglia inflammation and in turn modulate their inflammatory profile.


Carbon Monoxide/metabolism , Inflammation/metabolism , Microglia/metabolism , Mitochondria/metabolism , Adenosine Triphosphate/metabolism , Animals , Brain/metabolism , Brain/pathology , Cell Line , Glycolysis , Heme Oxygenase-1/metabolism , Inflammation/chemically induced , Inflammation/pathology , Lipopolysaccharides/toxicity , Mice , Microglia/pathology , Mitochondria/pathology , Oxidative Phosphorylation , Oxygen Consumption , Pyroptosis/genetics , Respiration
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