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Dendritic Cell Amiloride-Sensitive Channels Mediate Sodium-Induced Inflammation and Hypertension.
Barbaro NR, Foss JD, Kryshtal DO, Tsyba N, Kumaresan S, Xiao L, Mernaugh RL, Itani HA, Loperena R, Chen W, Dikalov S, Titze JM, Knollmann BC, Harrison DG, Kirabo A
(2017) Cell Rep 21: 1009-1020
MeSH Terms: Amiloride, Animals, Cells, Cultured, Cytokines, Dendritic Cells, Epithelial Sodium Channel Blockers, Epithelial Sodium Channels, Hypertension, Inflammation, Male, Mice, Mice, Inbred C57BL, NADPH Oxidases, Oxidative Stress, Prostaglandins E, Protein Kinase C, Sodium, Sodium-Hydrogen Exchanger 1, Superoxides
Show Abstract · Added December 27, 2017
Sodium accumulates in the interstitium and promotes inflammation through poorly defined mechanisms. We describe a pathway by which sodium enters dendritic cells (DCs) through amiloride-sensitive channels including the alpha and gamma subunits of the epithelial sodium channel and the sodium hydrogen exchanger 1. This leads to calcium influx via the sodium calcium exchanger, activation of protein kinase C (PKC), phosphorylation of p47, and association of p47 with gp91. The assembled NADPH oxidase produces superoxide with subsequent formation of immunogenic isolevuglandin (IsoLG)-protein adducts. DCs activated by excess sodium produce increased interleukin-1β (IL-1β) and promote T cell production of cytokines IL-17A and interferon gamma (IFN-γ). When adoptively transferred into naive mice, these DCs prime hypertension in response to a sub-pressor dose of angiotensin II. These findings provide a mechanistic link between salt, inflammation, and hypertension involving increased oxidative stress and IsoLG production in DCs.
Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.
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19 MeSH Terms
Suppressed ubiquitination of Nrf2 by p47 contributes to Nrf2 activation.
Ha Kim K, Sadikot RT, Yeon Lee J, Jeong HS, Oh YK, Blackwell TS, Joo M
(2017) Free Radic Biol Med 113: 48-58
MeSH Terms: Animals, Disease Models, Animal, HEK293 Cells, Humans, Kelch-Like ECH-Associated Protein 1, Lipopolysaccharides, Mice, NADPH Oxidases, NF-E2-Related Factor 2, Pneumonia, RAW 264.7 Cells, Reactive Oxygen Species, Signal Transduction, Ubiquitination
Show Abstract · Added March 21, 2018
Although critical in phagocytosis in innate immunity, reactive oxygen species (ROS) collaterally inflict damage to host phagocytes because they indiscriminate targets. Since Nrf2 increases the expression of anti-oxidant enzymes that nullifies ROS, ROS activating Nrf2 is a critical negative regulatory step for countering the deleterious effects of ROS. Here, we postulate whether, along with ROS activating Nrf2, NADPH oxidase components also participate in direct activation of Nrf2, contributing to protection from ROS. Our results show that the p47 of the NADPH oxidase, but not p65 or p40, physically binds to Nrf2, activating the Nrf2 function. p47 binding to Nrf2/Keap1 complex suppresses the ubiquitination of Nrf2, while p47 becomes ubiquitinated by Keap1. p47 increases the nuclear translocation of Nrf2 and the expression of Nrf2-dependent genes, whereas genetic ablation of p47 decreases the expression of those genes. In a lipopolysaccharide-induced acute lung inflammation mouse model, selective expression of p47 in mouse lungs induces the expression of Nrf2-dependent genes and is sufficient to suppress neutrophilic lung inflammation. Therefore, our findings suggest that p47 is a novel regulator of Nrf2 function.
Copyright © 2017 Elsevier Inc. All rights reserved.
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14 MeSH Terms
Activation of NADPH oxidases leads to DNA damage in esophageal cells.
Bhardwaj V, Gokulan RC, Horvat A, Yermalitskaya L, Korolkova O, Washington KM, El-Rifai W, Dikalov SI, Zaika AI
(2017) Sci Rep 7: 9956
MeSH Terms: Barrett Esophagus, Bile Acids and Salts, Cells, Cultured, DNA Damage, Epithelial Cells, Humans, NADPH Oxidase 1, NADPH Oxidase 2, Reactive Oxygen Species
Show Abstract · Added March 26, 2019
Gastroesophageal reflux disease (GERD) is the strongest known risk factor for esophageal adenocarcinoma. In the center of tumorigenic events caused by GERD is repeated damage of esophageal tissues by the refluxate. In this study, we focused on a genotoxic aspect of exposure of esophageal cells to acidic bile reflux (BA/A). Analyzing cells generated from patients with Barrett's esophagus and human esophageal specimens, we found that BA/A cause significant DNA damage that is mediated by reactive-oxygen species. ROS originate from mitochondria and NADPH oxidases. We specifically identified NOX1 and NOX2 enzymes to be responsible for ROS generation. Inhibition of NOX2 and NOX1 with siRNA or chemical inhibitors significantly suppresses ROS production and DNA damage induced by BA/A. Mechanistically, our data showed that exposure of esophageal cells to acidic bile salts induces phosphorylation of the p47 subunit of NOX2 and its translocation to the cellular membrane. This process is mediated by protein kinase C, which is activated by BA/A. Taken together, our studies suggest that inhibition of ROS induced by reflux can be a useful strategy for preventing DNA damage and decreasing the risk of tumorigenic transformation caused by GERD.
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9 MeSH Terms
Kinetic processivity of the two-step oxidations of progesterone and pregnenolone to androgens by human cytochrome P450 17A1.
Gonzalez E, Guengerich FP
(2017) J Biol Chem 292: 13168-13185
MeSH Terms: 17-alpha-Hydroxypregnenolone, Androstenedione, Animals, Binding Sites, Biocatalysis, Cytochrome P-450 Enzyme Inhibitors, Cytochromes b5, Dehydroepiandrosterone, Humans, Imidazoles, Kinetics, Ligands, Models, Molecular, NADPH-Ferrihemoprotein Reductase, Naphthalenes, Oxidation-Reduction, Pregnenolone, Progesterone, Protein Conformation, Rats, Recombinant Proteins, Stereoisomerism, Steroid 17-alpha-Hydroxylase
Show Abstract · Added March 14, 2018
Cytochrome P450 (P450, CYP) 17A1 plays a critical role in steroid metabolism, catalyzing both the 17α-hydroxylation of pregnenolone and progesterone and the subsequent 17α,20-lyase reactions to form dehydroepiandrosterone (DHEA) and androstenedione (Andro), respectively, critical for generating glucocorticoids and androgens. Human P450 17A1 reaction rates examined are enhanced by the accessory protein cytochrome (), but the exact role of in P450 17A1-catalyzed reactions is unclear as are several details of these reactions. Here, we examined in detail the processivity of the 17α-hydroxylation and lyase steps. did not enhance reaction rates by decreasing the rates of any of the steroids. Steroid binding to P450 17A1 was more complex than a simple two-state system. Pre-steady-state experiments indicated lag phases for Andro production from progesterone and for DHEA from pregnenolone, indicating a distributive character of the enzyme. However, we observed processivity in pregnenolone/DHEA pulse-chase experiments. ()-Orteronel was three times more inhibitory toward the conversion of 17α-hydroxypregnenolone to DHEA than toward the 17α-hydroxylation of pregnenolone. IC values for ()-orteronel were identical for blocking DHEA formation from pregnenolone and for 17α-hydroxylation, suggestive of processivity. Global kinetic modeling helped assign sets of rate constants for individual or groups of reactions, indicating that human P450 17A1 is an inherently distributive enzyme but that some processivity is present, some of the 17α-OH pregnenolone formed from pregnenolone did not dissociate from P450 17A1 before conversion to DHEA. Our results also suggest multiple conformations of P450 17A1, as previously proposed on the basis of NMR spectroscopy and X-ray crystallography.
© 2017 by The American Society for Biochemistry and Molecular Biology, Inc.
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23 MeSH Terms
Pyridine Dinucleotides from Molecules to Man.
Fessel JP, Oldham WM
(2018) Antioxid Redox Signal 28: 180-212
MeSH Terms: ADP-ribosyl Cyclase 1, Adenosine Triphosphate, Biosynthetic Pathways, Catalysis, Disease Susceptibility, Energy Metabolism, Homeostasis, Humans, Hydrolysis, Intracellular Space, Male, Mitochondria, NAD, NADP, NADPH Oxidases, Nitric Oxide Synthase, Oxidation-Reduction, Pyridines, Reactive Oxygen Species, Stress, Physiological
Show Abstract · Added March 14, 2018
SIGNIFICANCE - Pyridine dinucleotides, nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), were discovered more than 100 years ago as necessary cofactors for fermentation in yeast extracts. Since that time, these molecules have been recognized as fundamental players in a variety of cellular processes, including energy metabolism, redox homeostasis, cellular signaling, and gene transcription, among many others. Given their critical role as mediators of cellular responses to metabolic perturbations, it is unsurprising that dysregulation of NAD and NADP metabolism has been associated with the pathobiology of many chronic human diseases. Recent Advances: A biochemistry renaissance in biomedical research, with its increasing focus on the metabolic pathobiology of human disease, has reignited interest in pyridine dinucleotides, which has led to new insights into the cell biology of NAD(P) metabolism, including its cellular pharmacokinetics, biosynthesis, subcellular localization, and regulation. This review highlights these advances to illustrate the importance of NAD(P) metabolism in the molecular pathogenesis of disease.
CRITICAL ISSUES - Perturbations of NAD(H) and NADP(H) are a prominent feature of human disease; however, fundamental questions regarding the regulation of the absolute levels of these cofactors and the key determinants of their redox ratios remain. Moreover, an integrated topological model of NAD(P) biology that combines the metabolic and other roles remains elusive.
FUTURE DIRECTIONS - As the complex regulatory network of NAD(P) metabolism becomes illuminated, sophisticated new approaches to manipulating these pathways in specific organs, cells, or organelles will be developed to target the underlying pathogenic mechanisms of disease, opening doors for the next generation of redox-based, metabolism-targeted therapies. Antioxid. Redox Signal. 28, 180-212.
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20 MeSH Terms
Autofluorescence imaging identifies tumor cell-cycle status on a single-cell level.
Heaster TM, Walsh AJ, Zhao Y, Hiebert SW, Skala MC
(2018) J Biophotonics 11:
MeSH Terms: Apoptosis, Cell Cycle, Cell Line, Tumor, Cell Proliferation, Discriminant Analysis, Flavin-Adenine Dinucleotide, Humans, Least-Squares Analysis, Leukemia, Myeloid, Acute, NADP, Optical Imaging, Single-Cell Analysis
Show Abstract · Added March 26, 2019
The goal of this study is to validate fluorescence intensity and lifetime imaging of metabolic co-enzymes NAD(P)H and FAD (optical metabolic imaging, or OMI) as a method to quantify cell-cycle status of tumor cells. Heterogeneity in tumor cell-cycle status (e. g. proliferation, quiescence, apoptosis) increases drug resistance and tumor recurrence. Cell-cycle status is closely linked to cellular metabolism. Thus, this study applies cell-level metabolic imaging to distinguish proliferating, quiescent, and apoptotic populations. Two-photon microscopy and time-correlated single photon counting are used to measure optical redox ratio (NAD(P)H fluorescence intensity divided by FAD intensity), NAD(P)H and FAD fluorescence lifetime parameters. Redox ratio, NAD(P)H and FAD lifetime parameters alone exhibit significant differences (p<0.05) between population means. To improve separation between populations, linear combination models derived from partial least squares - discriminant analysis (PLS-DA) are used to exploit all measurements together. Leave-one-out cross validation of the model yielded high classification accuracies (92.4 and 90.1 % for two and three populations, respectively). OMI and PLS-DA also identifies each sub-population within heterogeneous samples. These results establish single-cell analysis with OMI and PLS-DA as a label-free method to distinguish cell-cycle status within intact samples. This approach could be used to incorporate cell-level tumor heterogeneity in cancer drug development.
© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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MeSH Terms
Rare and low-frequency coding variants alter human adult height.
Marouli E, Graff M, Medina-Gomez C, Lo KS, Wood AR, Kjaer TR, Fine RS, Lu Y, Schurmann C, Highland HM, Rüeger S, Thorleifsson G, Justice AE, Lamparter D, Stirrups KE, Turcot V, Young KL, Winkler TW, Esko T, Karaderi T, Locke AE, Masca NG, Ng MC, Mudgal P, Rivas MA, Vedantam S, Mahajan A, Guo X, Abecasis G, Aben KK, Adair LS, Alam DS, Albrecht E, Allin KH, Allison M, Amouyel P, Appel EV, Arveiler D, Asselbergs FW, Auer PL, Balkau B, Banas B, Bang LE, Benn M, Bergmann S, Bielak LF, Blüher M, Boeing H, Boerwinkle E, Böger CA, Bonnycastle LL, Bork-Jensen J, Bots ML, Bottinger EP, Bowden DW, Brandslund I, Breen G, Brilliant MH, Broer L, Burt AA, Butterworth AS, Carey DJ, Caulfield MJ, Chambers JC, Chasman DI, Chen YI, Chowdhury R, Christensen C, Chu AY, Cocca M, Collins FS, Cook JP, Corley J, Galbany JC, Cox AJ, Cuellar-Partida G, Danesh J, Davies G, de Bakker PI, de Borst GJ, de Denus S, de Groot MC, de Mutsert R, Deary IJ, Dedoussis G, Demerath EW, den Hollander AI, Dennis JG, Di Angelantonio E, Drenos F, Du M, Dunning AM, Easton DF, Ebeling T, Edwards TL, Ellinor PT, Elliott P, Evangelou E, Farmaki AE, Faul JD, Feitosa MF, Feng S, Ferrannini E, Ferrario MM, Ferrieres J, Florez JC, Ford I, Fornage M, Franks PW, Frikke-Schmidt R, Galesloot TE, Gan W, Gandin I, Gasparini P, Giedraitis V, Giri A, Girotto G, Gordon SD, Gordon-Larsen P, Gorski M, Grarup N, Grove ML, Gudnason V, Gustafsson S, Hansen T, Harris KM, Harris TB, Hattersley AT, Hayward C, He L, Heid IM, Heikkilä K, Helgeland Ø, Hernesniemi J, Hewitt AW, Hocking LJ, Hollensted M, Holmen OL, Hovingh GK, Howson JM, Hoyng CB, Huang PL, Hveem K, Ikram MA, Ingelsson E, Jackson AU, Jansson JH, Jarvik GP, Jensen GB, Jhun MA, Jia Y, Jiang X, Johansson S, Jørgensen ME, Jørgensen T, Jousilahti P, Jukema JW, Kahali B, Kahn RS, Kähönen M, Kamstrup PR, Kanoni S, Kaprio J, Karaleftheri M, Kardia SL, Karpe F, Kee F, Keeman R, Kiemeney LA, Kitajima H, Kluivers KB, Kocher T, Komulainen P, Kontto J, Kooner JS, Kooperberg C, Kovacs P, Kriebel J, Kuivaniemi H, Küry S, Kuusisto J, La Bianca M, Laakso M, Lakka TA, Lange EM, Lange LA, Langefeld CD, Langenberg C, Larson EB, Lee IT, Lehtimäki T, Lewis CE, Li H, Li J, Li-Gao R, Lin H, Lin LA, Lin X, Lind L, Lindström J, Linneberg A, Liu Y, Liu Y, Lophatananon A, Luan J, Lubitz SA, Lyytikäinen LP, Mackey DA, Madden PA, Manning AK, Männistö S, Marenne G, Marten J, Martin NG, Mazul AL, Meidtner K, Metspalu A, Mitchell P, Mohlke KL, Mook-Kanamori DO, Morgan A, Morris AD, Morris AP, Müller-Nurasyid M, Munroe PB, Nalls MA, Nauck M, Nelson CP, Neville M, Nielsen SF, Nikus K, Njølstad PR, Nordestgaard BG, Ntalla I, O'Connel JR, Oksa H, Loohuis LM, Ophoff RA, Owen KR, Packard CJ, Padmanabhan S, Palmer CN, Pasterkamp G, Patel AP, Pattie A, Pedersen O, Peissig PL, Peloso GM, Pennell CE, Perola M, Perry JA, Perry JR, Person TN, Pirie A, Polasek O, Posthuma D, Raitakari OT, Rasheed A, Rauramaa R, Reilly DF, Reiner AP, Renström F, Ridker PM, Rioux JD, Robertson N, Robino A, Rolandsson O, Rudan I, Ruth KS, Saleheen D, Salomaa V, Samani NJ, Sandow K, Sapkota Y, Sattar N, Schmidt MK, Schreiner PJ, Schulze MB, Scott RA, Segura-Lepe MP, Shah S, Sim X, Sivapalaratnam S, Small KS, Smith AV, Smith JA, Southam L, Spector TD, Speliotes EK, Starr JM, Steinthorsdottir V, Stringham HM, Stumvoll M, Surendran P, 't Hart LM, Tansey KE, Tardif JC, Taylor KD, Teumer A, Thompson DJ, Thorsteinsdottir U, Thuesen BH, Tönjes A, Tromp G, Trompet S, Tsafantakis E, Tuomilehto J, Tybjaerg-Hansen A, Tyrer JP, Uher R, Uitterlinden AG, Ulivi S, van der Laan SW, Van Der Leij AR, van Duijn CM, van Schoor NM, van Setten J, Varbo A, Varga TV, Varma R, Edwards DR, Vermeulen SH, Vestergaard H, Vitart V, Vogt TF, Vozzi D, Walker M, Wang F, Wang CA, Wang S, Wang Y, Wareham NJ, Warren HR, Wessel J, Willems SM, Wilson JG, Witte DR, Woods MO, Wu Y, Yaghootkar H, Yao J, Yao P, Yerges-Armstrong LM, Young R, Zeggini E, Zhan X, Zhang W, Zhao JH, Zhao W, Zhao W, Zheng H, Zhou W, EPIC-InterAct Consortium, CHD Exome+ Consortium, ExomeBP Consortium, T2D-Genes Consortium, GoT2D Genes Consortium, Global Lipids Genetics Consortium, ReproGen Consortium, MAGIC Investigators, Rotter JI, Boehnke M, Kathiresan S, McCarthy MI, Willer CJ, Stefansson K, Borecki IB, Liu DJ, North KE, Heard-Costa NL, Pers TH, Lindgren CM, Oxvig C, Kutalik Z, Rivadeneira F, Loos RJ, Frayling TM, Hirschhorn JN, Deloukas P, Lettre G
(2017) Nature 542: 186-190
MeSH Terms: ADAMTS Proteins, Adult, Alleles, Body Height, Cell Adhesion Molecules, Female, Gene Frequency, Genetic Variation, Genome, Human, Glycoproteins, Glycosaminoglycans, Hedgehog Proteins, Humans, Intercellular Signaling Peptides and Proteins, Interferon Regulatory Factors, Interleukin-11 Receptor alpha Subunit, Male, Multifactorial Inheritance, NADPH Oxidase 4, NADPH Oxidases, Phenotype, Pregnancy-Associated Plasma Protein-A, Procollagen N-Endopeptidase, Proteoglycans, Proteolysis, Receptors, Androgen, Somatomedins
Show Abstract · Added April 26, 2017
Height is a highly heritable, classic polygenic trait with approximately 700 common associated variants identified through genome-wide association studies so far. Here, we report 83 height-associated coding variants with lower minor-allele frequencies (in the range of 0.1-4.8%) and effects of up to 2 centimetres per allele (such as those in IHH, STC2, AR and CRISPLD2), greater than ten times the average effect of common variants. In functional follow-up studies, rare height-increasing alleles of STC2 (giving an increase of 1-2 centimetres per allele) compromised proteolytic inhibition of PAPP-A and increased cleavage of IGFBP-4 in vitro, resulting in higher bioavailability of insulin-like growth factors. These 83 height-associated variants overlap genes that are mutated in monogenic growth disorders and highlight new biological candidates (such as ADAMTS3, IL11RA and NOX4) and pathways (such as proteoglycan and glycosaminoglycan synthesis) involved in growth. Our results demonstrate that sufficiently large sample sizes can uncover rare and low-frequency variants of moderate-to-large effect associated with polygenic human phenotypes, and that these variants implicate relevant genes and pathways.
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27 MeSH Terms
NADPH oxidase 4 deficiency increases tubular cell death during acute ischemic reperfusion injury.
Nlandu-Khodo S, Dissard R, Hasler U, Schäfer M, Pircher H, Jansen-Durr P, Krause KH, Martin PY, de Seigneux S
(2016) Sci Rep 6: 38598
MeSH Terms: Animals, Apoptosis, Cell Death, Creatinine, Disease Models, Animal, Gene Expression, Gene Expression Regulation, Genetic Predisposition to Disease, Glutathione, Kelch-Like ECH-Associated Protein 1, Kidney Diseases, Kidney Tubules, Mice, Mice, Knockout, Mitochondria, NADPH Oxidase 4, NF-E2-Related Factor 2, Oxidation-Reduction, Proto-Oncogene Proteins c-bcl-2, Reperfusion Injury
Show Abstract · Added December 26, 2018
NADPH oxidase 4 (NOX4) is highly expressed in kidney proximal tubular cells. NOX4 constitutively produces hydrogen peroxide, which may regulate important pro-survival pathways. Renal ischemia reperfusion injury (IRI) is a classical model mimicking human ischemic acute tubular necrosis. We hypothesized that NOX4 plays a protective role in kidney IRI. In wild type (WT) animals subjected to IRI, NOX4 protein expression increased after 24 hours. NOX4 KO (knock-out) and WT littermates mice were subjected to IRI. NOX4 KO mice displayed decreased renal function and more severe tubular apoptosis, decreased Bcl-2 expression and higher histologic damage scores compared to WT. Activation of NRF2 was decreased in NOX4 KO mice in response to IRI. This was related to decreased KEAP1 oxidation leading to decreased NRF2 stabilization. This resulted in decreased glutathione levels. In vitro silencing of NOX4 in cells showed an enhanced propensity to apoptosis, with reduced expression of NRF2, glutathione content and Bcl-2 expression, similar to cells derived from NOX4 KO mice. Overexpression of a constitutively active form of NRF2 (caNRF2) in NOX4 depleted cells rescued most of this phenotype in cultured cells, implying that NRF2 regulation by ROS issued from NOX4 may play an important role in its anti-apoptotic property.
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MeSH Terms
LRRC8A channels support TNFα-induced superoxide production by Nox1 which is required for receptor endocytosis.
Choi H, Ettinger N, Rohrbough J, Dikalova A, Nguyen HN, Lamb FS
(2016) Free Radic Biol Med 101: 413-423
MeSH Terms: Cell Line, Cyclopentanes, Endocytosis, Gene Expression Regulation, HEK293 Cells, Humans, Indans, JNK Mitogen-Activated Protein Kinases, Membrane Proteins, Myocytes, Smooth Muscle, NADPH Oxidase 1, NF-kappa B, Phosphorylation, Protein Subunits, RNA, Small Interfering, Receptors, Tumor Necrosis Factor, Type I, Signal Transduction, Superoxide Dismutase, Superoxides, Tumor Necrosis Factor-alpha, Vascular Cell Adhesion Molecule-1
Show Abstract · Added March 26, 2019
Leucine Rich Repeat Containing 8A (LRRC8A) is a required component of volume-regulated anion channels (VRACs). In vascular smooth muscle cells, tumor necrosis factor-α (TNFα) activates VRAC via type 1 TNFα receptors (TNFR1), and this requires superoxide (O) production by NADPH oxidase 1 (Nox1). VRAC inhibitors suppress the inflammatory response to TNFα by an unknown mechanism. We hypothesized that LRRC8A directly supports Nox1 activity, providing a link between VRAC current and inflammatory signaling. VRAC inhibition by 4-(2-butyl-6,7-dichlor-2-cyclopentylindan-1-on-5-yl) oxobutyric acid (DCPIB) impaired NF-κB activation by TNFα. LRRC8A siRNA reduced the magnitude of VRAC and inhibited TNFα-induced NF-κB activation, iNOS and VCAM expression, and proliferation of VSMCs. Signaling steps disrupted by both siLRRC8A and DCPIB included; extracellular O production by Nox1, c-Jun N-terminal kinase (JNK) phosphorylation and endocytosis of TNFR1. Extracellular superoxide dismutase, but not catalase, selectively inhibited TNFR1 endocytosis and JNK phosphorylation. Thus, O is the critical extracellular oxidant for TNFR signal transduction. Reducing JNK expression (siJNK) increased extracellular O suggesting that JNK provides important negative feedback regulation to Nox1 at the plasma membrane. LRRC8A co-localized by immunostaining, and co-immunoprecipitated with, both Nox1 and its p22phox subunit. LRRC8A is a component of the Nox1 signaling complex. It is required for extracellular O production, which is in turn essential for TNFR1 endocytosis. These data are the first to provide a molecular mechanism for the potent anti-proliferative and anti-inflammatory effects of VRAC inhibition.
Copyright © 2016 Elsevier Inc. All rights reserved.
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Targeting Enox1 in tumor stroma increases the efficacy of fractionated radiotherapy.
Smith CA, Mont S, Traver G, Sekhar KR, Crooks PA, Freeman ML
(2016) Oncotarget 7: 77926-77936
MeSH Terms: Animals, Cell Line, Tumor, Colorectal Neoplasms, Dose Fractionation, Radiation, HT29 Cells, Humans, Mice, Mice, Nude, Molecular Targeted Therapy, NADH, NADPH Oxidoreductases, Radiation-Sensitizing Agents, Xenograft Model Antitumor Assays
Show Abstract · Added March 17, 2017
The goal of this investigation was to clarify the question of whether targeting Enox1 in tumor stroma would synergistically enhance the survival of tumor-bearing mice treated with fractionated radiotherapy. Enox1, a NADH oxidase, is expressed in tumor vasculature and stroma. However, it is not expressed in many tumor types, including HT-29 colorectal carcinoma cells. Pharmacological inhibition of Enox1 in endothelial cells inhibited repair of DNA double strand breaks, as measured by γH2AX and 53BP1 foci formation, as well as neutral comet assays. For 4 consecutive days athymic mice bearing HT-29 hindlimb xenografts were injected with a small molecule inhibitor of Enox1 or solvent control. Tumors were then administered 2 Gy of x-rays. On day 5 tumors were administered a single 'top-up' fraction of 30 Gy, the purpose of which was to amplify intrinsic differences in the radiation fractionation regimen produced by Enox1 targeting. Pharmacological targeting of Enox1 resulted in 80% of the tumor-bearing mice surviving at 90 days compared to only 40% of tumor-bearing mice treated with solvent control. The increase in survival was not a consequence of reoxygenation, as measured by pimonidazole immunostaining. These results are interpreted to indicate that targeting of Enox1 in tumor stroma significantly enhances the effectiveness of 2 Gy fractionated radiotherapy and identifies Enox1 as a potential therapeutic target.
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12 MeSH Terms