Nrf2 deficiency decreases NADPH from impaired IDH shuttle and pentose phosphate pathway in retinal pigmented epithelial cells to magnify oxidative stress‐induced mitochondrial dysfunction

Tp53-induced glycolysis and apoptosis regulator (TIGAR) activation blocks glycolytic ATP synthesis by inhibiting phosphofructokinase-1 activity. Our data indicate that TIGAR is selectively induced and activated in renal outermedullary proximal straight tubules (PSTs) after ischemia-reperfusion injury in a p53-dependent manner. Under severe ischemic conditions, TIGAR expression persisted through 48 h postinjury and induced loss of renal function and histological damage. Furthermore, TIGAR upregulation inhibited phosphofructokinase-1 activity, glucose 6-phosphate dehydrogenase (G6PD) activity, and induced ATP depletion, oxidative stress, autophagy, and apoptosis. Small interfering RNA-mediated TIGAR inhibition prevented the aforementioned malevolent effects and protected the kidneys from functional and histological damage. After mild ischemia, but not severe ischemia, G6PD activity and NADPH levels were restored, suggesting that TIGAR activation may redirect the glycolytic pathway into gluconeogenesis or the pentose phosphate pathway to produce NADPH. The increased level of NADPH maintained the level of GSH to scavenge ROS, resulting in a lower sensitivity of PST cells to injury. Under severe ischemia, G6PD activity and NADPH levels were reduced during reperfusion; however, blockade of TIGAR enhanced their levels and reduced oxidative stress and apoptosis. Collectively, these results demonstrate that inhibition of TIGAR may protect PST cells from energy depletion and apoptotic cell death in the setting of severe ischemia-reperfusion injury. However, under low ischemic burden, TIGAR activation induces the pentose phosphate pathway and autophagy as a protective mechanism.

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The pentose phosphate pathway in Trypanosoma cruzi: a potential target for the chemotherapy of Chagas disease

Anais da Academia Brasileira de Ciências ◽

10.1590/s0001-37652007000400007 ◽

2007 ◽

Vol 79 (4) ◽

pp. 649-663 ◽

Cited By ~ 29

Author(s):

Mariana Igoillo-Esteve ◽

Dante Maugeri ◽

Ana L. Stern ◽

Paula Beluardi ◽

Juan J. Cazzulo

Keyword(s):

Oxidative Stress ◽

Trypanosoma Cruzi ◽

Pentose Phosphate Pathway ◽

Single Copy ◽

Pentose Phosphate ◽

Site Directed Mutagenesis ◽

Haploid Genome ◽

Salt Bridges ◽

Phosphogluconate Dehydrogenase ◽

Genes Encoding

Trypanosoma cruzi is highly sensitive to oxidative stress caused by reactive oxygen species. Trypanothione, the parasite's major protection against oxidative stress, is kept reduced by trypanothione reductase, using NADPH; the major source of the reduced coenzyme seems to be the pentose phosphate pathway. Its seven enzymes are present in the four major stages in the parasite's biological cycle; we have cloned and expressed them in Escherichia coli as active proteins. Glucose 6-phosphate dehydrogenase, which controls glucose flux through the pathway by its response to the NADP/NADPH ratio, is encoded by a number of genes per haploid genome, and is induced up to 46-fold by hydrogen peroxide in metacyclic trypomastigotes. The genes encoding 6-phosphogluconolactonase, 6-phosphogluconate dehydrogenase, transaldolase and transketolase are present in the CL Brener clone as a single copy per haploid genome. 6-phosphogluconate dehydrogenase is very unstable, but was stabilized introducing two salt bridges by site-directed mutagenesis. Ribose-5-phosphate isomerase belongs to Type B; genes encoding Type A enzymes, present in mammals, are absent. Ribulose-5-phosphate epimerase is encoded by two genes. The enzymes of the pathway have a major cytosolic component, although several of them have a secondary glycosomal localization, and also minor localizations in other organelles.

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1,25‐Dihydroxyvitamin D alters the pentose phosphate pathway in Harvey‐ ras oncogene transfected MCF10A breast epithelial cells (644.3)

The FASEB Journal ◽

10.1096/fasebj.28.1_supplement.644.3 ◽

2014 ◽

Vol 28 (S1) ◽

Author(s):

Tomasz Wilmanski ◽

Wei Zheng ◽

Shawn Donkin ◽

Daniel Raftery ◽

Brian Bequette ◽

...

Keyword(s):

Epithelial Cells ◽

Pentose Phosphate Pathway ◽

Pentose Phosphate ◽

Ras Oncogene ◽

Breast Epithelial Cells ◽

Dihydroxyvitamin D ◽

1,25 Dihydroxyvitamin D ◽

Breast Epithelial

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Inhibition of autophagy aggravates molybdenum-induced mitochondrial dysfunction by aggravating oxidative stress in duck renal tubular epithelial cells

Ecotoxicology and Environmental Safety ◽

10.1016/j.ecoenv.2020.111771 ◽

2021 ◽

Vol 209 ◽

pp. 111771

Author(s):

Jionghan Zhuang ◽

Gaohui Nie ◽

Ruiming Hu ◽

Chang Wang ◽

Chenghong Xing ◽

...

Keyword(s):

Oxidative Stress ◽

Epithelial Cells ◽

Mitochondrial Dysfunction ◽

Tubular Epithelial Cells ◽

Renal Tubular Epithelial Cells ◽

Renal Tubular

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Mechanisms of housedust-induced toxicity in primary human corneal epithelial cells: Oxidative stress, proinflammatory response and mitochondrial dysfunction

Environment International ◽

10.1016/j.envint.2016.01.008 ◽

2016 ◽

Vol 89-90 ◽

pp. 30-37 ◽

Cited By ~ 31

Author(s):

Ping Xiang ◽

Rui-Wen He ◽

Yong-He Han ◽

Hong-Jie Sun ◽

Xin-Yi Cui ◽

...

Keyword(s):

Oxidative Stress ◽

Epithelial Cells ◽

Mitochondrial Dysfunction ◽

Proinflammatory Response ◽

Corneal Epithelial Cells ◽

Corneal Epithelial ◽

Human Corneal Epithelial Cells

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Beneficial effects of acute inhibition of the oxidative pentose phosphate pathway in the failing heart

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00783.2013 ◽

2014 ◽

Vol 306 (5) ◽

pp. H709-H717 ◽

Cited By ~ 13

Author(s):

Claudio Vimercati ◽

Khaled Qanud ◽

Gianfranco Mitacchione ◽

Danuta Sosnowska ◽

Zoltan Ungvari ◽

...

Keyword(s):

Oxidative Stress ◽

Pentose Phosphate Pathway ◽

Tissue Concentration ◽

Glucose Consumption ◽

Pentose Phosphate ◽

Oxidative Pentose Phosphate Pathway ◽

Stroke Work ◽

Failing Heart

In vitro studies suggested that glucose metabolism through the oxidative pentose phosphate pathway (oxPPP) can paradoxically feed superoxide-generating enzymes in failing hearts. We therefore tested the hypothesis that acute inhibition of the oxPPP reduces oxidative stress and enhances function and metabolism of the failing heart, in vivo. In 10 chronically instrumented dogs, congestive heart failure (HF) was induced by high-frequency cardiac pacing. Myocardial glucose consumption was enhanced by raising arterial glycemia to levels mimicking postprandial peaks, before and after intravenous administration of the oxPPP inhibitor 6-aminonicotinamide (80 mg/kg). Myocardial energy substrate metabolism was measured with radiolabeled glucose and oleic acid, and cardiac 8-isoprostane output was used as an index of oxidative stress. A group of five chronically instrumented, normal dogs served as control. In HF, raising glycemic levels from ∼80 to ∼170 mg/dL increased cardiac isoprostane output by approximately twofold, whereas oxPPP inhibition normalized oxidative stress and enhanced cardiac oxygen consumption, glucose oxidation, and stroke work. In normal hearts glucose infusion did not induce significant changes in cardiac oxidative stress. Myocardial tissue concentration of 6P-gluconate, an intermediate metabolite of the oxPPP, was significantly reduced by ∼50% in treated versus nontreated failing hearts, supporting the inhibitory effect of 6-aminonicotinamide. Our study indicates an important contribution of the oxPPP activity to cardiac oxidative stress in HF, which is particularly pronounced during common physiological changes such as postprandial glycemic peaks.

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Role of Intracellular Carbon Metabolism Pathways in Shigella flexneri Virulence

Infection and Immunity ◽

10.1128/iai.01575-13 ◽

2014 ◽

Vol 82 (7) ◽

pp. 2746-2755 ◽

Cited By ~ 23

Author(s):

E. A. Waligora ◽

C. R. Fisher ◽

N. J. Hanovice ◽

A. Rodou ◽

E. E. Wyckoff ◽

...

Keyword(s):

Epithelial Cells ◽

Pentose Phosphate Pathway ◽

Carbon Metabolism ◽

Cultured Cells ◽

Shigella Flexneri ◽

Plaque Assay ◽

Pentose Phosphate ◽

Host Cells ◽

Content Type ◽

Pathway Gene

ABSTRACTShigella flexneri, which replicates in the cytoplasm of intestinal epithelial cells, can use the Embden-Meyerhof-Parnas, Entner-Doudoroff, or pentose phosphate pathway for glycolytic carbon metabolism. To determine which of these pathways is used by intracellularS. flexneri, mutants were constructed and tested in a plaque assay for the ability to invade, replicate intracellularly, and spread to adjacent epithelial cells. Mutants blocked in the Embden-Meyerhof-Parnas pathway (pfkABandpykAFmutants) invaded the cells but formed very small plaques. Loss of the Entner-Doudoroff pathway geneedaresulted in small plaques, but the doubleeda eddmutant formed normal-size plaques. This suggested that the plaque defect of theedamutant was due to buildup of the toxic intermediate 2-keto-3-deoxy-6-phosphogluconic acid rather than a specific requirement for this pathway. Loss of the pentose phosphate pathway had no effect on plaque formation, indicating that it is not critical for intracellularS. flexneri. Supplementation of the epithelial cell culture medium with pyruvate allowed the glycolysis mutants to form larger plaques than those observed with unsupplemented medium, consistent with data from phenotypic microarrays (Biolog) indicating that pyruvate metabolism was not disrupted in these mutants. Interestingly, the wild-typeS. flexnerialso formed larger plaques in the presence of supplemental pyruvate or glucose, with pyruvate yielding the largest plaques. Analysis of the metabolites in the cultured cells showed increased intracellular levels of the added compound. Pyruvate increased the growth rate ofS. flexneriin vitro, suggesting that it may be a preferred carbon source inside host cells.

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The Pentose Phosphate Pathway and Pyruvate Carboxylation after Neonatal Hypoxic-Ischemic Brain Injury

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/jcbfm.2014.8 ◽

2014 ◽

Vol 34 (4) ◽

pp. 724-734 ◽

Cited By ~ 27

Author(s):

Eva MF Brekke ◽

Tora S Morken ◽

Marius Widerøe ◽

Asta K Håberg ◽

Ann-Mari Brubakk ◽

...

Keyword(s):

Oxidative Stress ◽

Glucose Metabolism ◽

Pentose Phosphate Pathway ◽

De Novo ◽

Pentose Phosphate ◽

Adult Brain ◽

Resonance Spectroscopy ◽

Neonatal Brain ◽

Artery Ligation ◽

Pyruvate Carboxylation

The neonatal brain is vulnerable to oxidative stress, and the pentose phosphate pathway (PPP) may be of particular importance to limit the injury. Furthermore, in the neonatal brain, neurons depend on de novo synthesis of neurotransmitters via pyruvate carboxylase (PC) in astrocytes to increase neurotransmitter pools. In the adult brain, PPP activity increases in response to various injuries while pyruvate carboxylation is reduced after ischemia. However, little is known about the response of these pathways after neonatal hypoxia-ischemia (HI). To this end, 7-day-old rats were subjected to unilateral carotid artery ligation followed by hypoxia. Animals were injected with [1,2-13C]glucose during the recovery phase and extracts of cerebral hemispheres ipsi- and contralateral to the operation were analyzed using 1H- and 13C-NMR (nuclear magnetic resonance) spectroscopy and high-performance liquid chromatography (HPLC). After HI, glucose levels were increased and there was evidence of mitochondrial hypometabolism in both hemispheres. Moreover, metabolism via PPP was reduced bilaterally. Ipsilateral glucose metabolism via PC was reduced, but PC activity was relatively preserved compared with glucose metabolism via pyruvate dehydrogenase. The observed reduction in PPP activity after HI may contribute to the increased susceptibility of the neonatal brain to oxidative stress.

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