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Manganese Detoxification by MntE Is Critical for Resistance to Oxidative Stress and Virulence of .
Grunenwald CM, Choby JE, Juttukonda LJ, Beavers WN, Weiss A, Torres VJ, Skaar EP
(2019) MBio 10:
MeSH Terms: Animals, Cation Transport Proteins, Disease Models, Animal, Gene Expression Regulation, Bacterial, Homeostasis, Iron, Manganese, Mice, Inbred BALB C, Microbial Viability, Oxidative Stress, Staphylococcal Infections, Staphylococcus aureus, Transcription Factors, Transcription, Genetic, Virulence
Show Abstract · Added April 2, 2019
Manganese (Mn) is an essential micronutrient critical for the pathogenesis of , a significant cause of human morbidity and mortality. Paradoxically, excess Mn is toxic; therefore, maintenance of intracellular Mn homeostasis is required for survival. Here we describe a Mn exporter in , MntE, which is a member of the cation diffusion facilitator (CDF) protein family and conserved among Gram-positive pathogens. Upregulation of transcription in response to excess Mn is dependent on the presence of MntR, a transcriptional repressor of the Mn uptake system. Inactivation of or leads to reduced growth in media supplemented with Mn, demonstrating MntE is required for detoxification of excess Mn. Inactivation of results in elevated levels of intracellular Mn, but reduced intracellular iron (Fe) levels, supporting the hypothesis that MntE functions as a Mn efflux pump and Mn efflux influences Fe homeostasis. Strains inactivated for are more sensitive to the oxidants NaOCl and paraquat, indicating Mn homeostasis is critical for resisting oxidative stress. Furthermore, and are required for full virulence of during infection, suggesting experiences Mn toxicity Combined, these data support a model in which MntR controls Mn homeostasis by balancing transcriptional repression of and induction of , both of which are critical for pathogenesis. Thus, Mn efflux contributes to bacterial survival and virulence during infection, establishing MntE as a potential antimicrobial target and expanding our understanding of Mn homeostasis. Manganese (Mn) is generally viewed as a critical nutrient that is beneficial to pathogenic bacteria due to its function as an enzymatic cofactor and its capability of acting as an antioxidant; yet paradoxically, high concentrations of this transition metal can be toxic. In this work, we demonstrate utilizes the cation diffusion facilitator (CDF) family protein MntE to alleviate Mn toxicity through efflux of excess Mn. Inactivation of leads to a significant reduction in resistance to oxidative stress and mediated mortality within a mouse model of systemic infection. These results highlight the importance of MntE-mediated Mn detoxification in intracellular Mn homeostasis, resistance to oxidative stress, and virulence. Therefore, this establishes MntE as a potential target for development of anti- therapeutics.
Copyright © 2019 Grunenwald et al.
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15 MeSH Terms
S100 Proteins in the Innate Immune Response to Pathogens.
Kozlyuk N, Monteith AJ, Garcia V, Damo SM, Skaar EP, Chazin WJ
(2019) Methods Mol Biol 1929: 275-290
MeSH Terms: Calcium, Host-Pathogen Interactions, Humans, Immunity, Innate, Inflammation, Manganese, Models, Molecular, Protein Conformation, S100 Proteins, Toll-Like Receptor 4
Show Abstract · Added March 26, 2019
S100 proteins are distinct dimeric EF-hand Ca-binding proteins that can bind Zn, Mn, and other transition metals with high affinity at two sites in the dimer interface. Certain S100 proteins, including S100A7, S100A12, S100A8, and S100A9, play key roles in the innate immune response to pathogens. These proteins function via a "nutritional immunity" mechanism by depleting essential transition metals in the infection that are required for the invading organism to grow and thrive. They also act as damage-associated molecular pattern ligands, which activate pattern recognition receptors (e.g., Toll-like receptor 4, RAGE) that mediate inflammation. Here we present protocols for these S100 proteins for high-level production of recombinant protein, measurement of binding affinities using isothermal titration calorimetry, and an assay of antimicrobial activity.
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10 MeSH Terms
From the Cover: Manganese and Rotenone-Induced Oxidative Stress Signatures Differ in iPSC-Derived Human Dopamine Neurons.
Neely MD, Davison CA, Aschner M, Bowman AB
(2017) Toxicol Sci 159: 366-379
MeSH Terms: Cell Differentiation, Cells, Cultured, Dopaminergic Neurons, Humans, Induced Pluripotent Stem Cells, Lipid Peroxidation, Manganese, Oxidative Stress, Reactive Nitrogen Species, Reactive Oxygen Species, Rotenone
Show Abstract · Added April 11, 2018
Parkinson's disease (PD) is the result of complex interactions between genetic and environmental factors. Two chemically distinct environmental stressors relevant to PD are the metal manganese and the pesticide rotenone. Both are thought to exert neurotoxicity at least in part via oxidative stress resulting from impaired mitochondrial activity. Identifying shared mechanism of action may reveal clues towards an understanding of the mechanisms underlying PD pathogenesis. Here we compare the effects of manganese and rotenone in human-induced pluripotent stem cells-derived postmitotic mesencephalic dopamine neurons by assessing several different oxidative stress endpoints. Manganese, but not rotenone caused a concentration and time-dependent increase in intracellular reactive oxygen/nitrogen species measured by quantifying the fluorescence of oxidized chloromethyl 2',7'-dichlorodihydrofluorescein diacetate (DCF) assay. In contrast, rotenone but not manganese caused an increase in cellular isoprostane levels, an indicator of lipid peroxidation. Manganese and rotenone both caused an initial decrease in cellular reduced glutathione; however, glutathione levels remained low in neurons treated with rotenone for 24 h but recovered in manganese-exposed cells. Neurite length, a sensitive indicator of overall neuronal health was adversely affected by rotenone, but not manganese. Thus, our observations suggest that the cellular oxidative stress evoked by these 2 agents is distinct yielding unique oxidative stress signatures across outcome measures. The protective effect of rasagiline, a compound used in the clinic for PD, had negligible impact on any of oxidative stress outcome measures except a subtle significant decrease in manganese-dependent production of reactive oxygen/nitrogen species detected by the DCF assay.
© The Author 2017. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.
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11 MeSH Terms
Dietary Manganese Promotes Staphylococcal Infection of the Heart.
Juttukonda LJ, Berends ETM, Zackular JP, Moore JL, Stier MT, Zhang Y, Schmitz JE, Beavers WN, Wijers CD, Gilston BA, Kehl-Fie TE, Atkinson J, Washington MK, Peebles RS, Chazin WJ, Torres VJ, Caprioli RM, Skaar EP
(2017) Cell Host Microbe 22: 531-542.e8
MeSH Terms: Abscess, Animals, Diet, Disease Models, Animal, Endocarditis, Bacterial, Heart, Humans, Leukocyte L1 Antigen Complex, Liver, Manganese, Mice, Mice, Congenic, Mice, Inbred C57BL, Neutrophils, Reactive Oxygen Species, Staphylococcal Infections, Staphylococcus aureus
Show Abstract · Added March 14, 2018
Diet, and specifically dietary metals, can modify the risk of infection. However, the mechanisms by which manganese (Mn), a common dietary supplement, alters infection remain unexplored. We report that dietary Mn levels dictate the outcome of systemic infections caused by Staphylococcus aureus, a leading cause of bacterial endocarditis. Mice fed a high Mn diet display alterations in Mn levels and localization within infected tissues, and S. aureus virulence and infection of the heart are enhanced. Although the canonical mammalian Mn-sequestering protein calprotectin surrounds staphylococcal heart abscesses, calprotectin is not released into the abscess nidus and does not limit Mn in this organ. Consequently, excess Mn is bioavailable to S. aureus in the heart. Bioavailable Mn is utilized by S. aureus to detoxify reactive oxygen species and protect against neutrophil killing, enhancing fitness within the heart. Therefore, a single dietary modification overwhelms vital host antimicrobial strategies, leading to fatal staphylococcal infection.
Copyright © 2017 Elsevier Inc. All rights reserved.
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4 Members
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17 MeSH Terms
Manganese and the Insulin-IGF Signaling Network in Huntington's Disease and Other Neurodegenerative Disorders.
Bryan MR, Bowman AB
(2017) Adv Neurobiol 18: 113-142
MeSH Terms: Alzheimer Disease, Amyotrophic Lateral Sclerosis, Animals, Autophagy, Brain, Disease Models, Animal, Humans, Huntingtin Protein, Huntington Disease, Insulin, Manganese, Mitochondria, Neostriatum, Neural Stem Cells, Neurodegenerative Diseases, Parkinson Disease, Reactive Oxygen Species, Signal Transduction, Somatomedins
Show Abstract · Added April 11, 2018
Huntington's disease (HD) is an autosomal dominant neurodegenerative disease resulting in motor impairment and death in patients. Recently, several studies have demonstrated insulin or insulin-like growth factor (IGF) treatment in models of HD, resulting in potent amelioration of HD phenotypes via modulation of the PI3K/AKT/mTOR pathways. Administration of IGF and insulin can rescue microtubule transport, metabolic function, and autophagy defects, resulting in clearance of Huntingtin (HTT) aggregates, restoration of mitochondrial function, amelioration of motor abnormalities, and enhanced survival. Manganese (Mn) is an essential metal to all biological systems but, in excess, can be toxic. Interestingly, several studies have revealed the insulin-mimetic effects of Mn-demonstrating Mn can activate several of the same metabolic kinases and increase peripheral and neuronal insulin and IGF-1 levels in rodent models. Separate studies have shown mouse and human striatal neuroprogenitor cell (NPC) models exhibit a deficit in cellular Mn uptake, indicative of a Mn deficiency. Furthermore, evidence from the literature reveals a striking overlap between cellular consequences of Mn deficiency (i.e., impaired function of Mn-dependent enzymes) and known HD endophenotypes including excitotoxicity, increased reactive oxygen species (ROS) accumulation, and decreased mitochondrial function. Here we review published evidence supporting a hypothesis that (1) the potent effect of IGF or insulin treatment on HD models, (2) the insulin-mimetic effects of Mn, and (3) the newly discovered Mn-dependent perturbations in HD may all be functionally related. Together, this review will present the intriguing possibility that intricate regulatory cross-talk exists between Mn biology and/or toxicology and the insulin/IGF signaling pathways which may be deeply connected to HD pathology and, perhaps, other neurodegenerative diseases (NDDs) and other neuropathological conditions.
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MeSH Terms
Phosphatidylinositol 3 kinase (PI3K) modulates manganese homeostasis and manganese-induced cell signaling in a murine striatal cell line.
Bryan MR, Uhouse MA, Nordham KD, Joshi P, Rose DIR, O'Brien MT, Aschner M, Bowman AB
(2018) Neurotoxicology 64: 185-194
MeSH Terms: Animals, Cell Line, Chromones, Corpus Striatum, HEK293 Cells, Homeostasis, Humans, Induced Pluripotent Stem Cells, Inhibitory Concentration 50, Manganese, Mice, Morpholines, Neural Stem Cells, Phosphatidylinositol 3-Kinase, Signal Transduction, Tumor Suppressor Protein p53
Show Abstract · Added April 11, 2018
In a recent study, we found that blocking the protein kinase ataxia telangiectasia mutated (ATM) with the small molecule inhibitor (SMI) KU-55933 can completely abrogate Mn-induced phosphorylation of p53 at serine 15 (p-p53) in human induced pluripotent stem cell (hiPSC)-differentiated striatal neuroprogenitors. However, in the immortalized mouse striatal progenitor cell line STHdh, a concentration of KU55933 far exceeding its IC for ATM was required to inhibit Mn-induced p-p53. This suggested an alternative signaling system redundant with ATM kinase for activating p53 in this cell line- one that was altered by KU55933 at these higher concentrations (i.e. mTORC1, DNApk, PI3K). To test the hypothesis that one or more of these signaling pathways contributed to Mn-induced p-p53, we utilized a set of SMIs (e.g. NU7441 and LY294002) known to block DNApk, PI3K, and mTORC1 at distinct concentrations. We found that the SMIs inhibit Mn-induced p-p53 expression near the expected IC for PI3K, versus other known targets. We hypothesized that inhibiting PI3K reduces intracellular Mn and thereby decreases activation of p53 by Mn. Using the cellular fura-2 manganese extraction assay (CFMEA), we determined that KU55933/60019, NU7441, and LY294002 (at concentrations near their IC for PI3K) all decrease intracellular Mn (∼50%) after a dual, 24-h Mn and SMI exposure. Many pathways are activated by Mn aside from p-p53, including AKT and mTOR pathways. Thus, we explored the activation of these pathways by Mn in STHdh cells as well as the effects of other pathway inhibitors. p-AKT and p-S6 activation by Mn is almost completely blocked upon addition of NU7441(5μM) or LY294002(7μM), supporting PI3K's upstream role in the AKT/mTOR pathway. We also investigated whether PI3K inhibition blocks Mn uptake in other cell lines. LY294002 exposure did not reduce Mn uptake in ST14A, Neuro2A, HEK293, MEF, or hiPSC-derived neuroprogenitors. Next, we sought to determine whether inhibition of PI3K blocked p53 phosphorylation by directly blocking an unknown PI3K/p53 interaction or indirectly reducing intracellular Mn, decreasing p-p53 expression. In-Cell Western and CFMEA experiments using multiple concentrations of Mn exposures demonstrated that intracellular Mn levels directly correlated with p-p53 expression with or without addition of LY294002. Finally, we examined whether PI3K inhibition was able to block Mn-induced p-p53 activity in hiPSC-derived striatal neuroprogenitors. As expected, LY294002 does not block Mn-induced p-p53 as PI3K inhibition is unable to reduce Mn net uptake in this cell line, suggesting the effect of LY294002 on Mn uptake is relatively specific to the STHdh mouse striatal cell line.
Copyright © 2017 Elsevier B.V. All rights reserved.
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16 MeSH Terms
Relationships Between Essential Manganese Biology and Manganese Toxicity in Neurological Disease.
Pfalzer AC, Bowman AB
(2017) Curr Environ Health Rep 4: 223-228
MeSH Terms: Aging, Central Nervous System Diseases, Humans, Manganese, Manganese Poisoning, Neurotoxicity Syndromes, Risk Factors
Show Abstract · Added April 26, 2017
PURPOSE OF REVIEW - Manganese (Mn) is critical for neurodevelopment but also has been implicated in the pathophysiology of several neurological diseases. We discuss how Mn requirements intersect with Mn biology and toxicity, and how these requirements may be altered in neurological disease. Furthermore, we discuss the emerging evidence that the level of Mn associated with optimal overall efficiency for Mn biology does not necessarily coincide with optimal cognitive outcomes.
RECENT FINDINGS - Studies have linked Mn exposures with urea cycle metabolism and autophagy, with evidence that exposures typically neurotoxic may be able to correct deficiencies in these processes at least short term. The line between Mn-dependent biology and toxicity is thus blurred. Further, new work suggests that Mn exposures correlating to optimal cognitive scores in children are associated with cognitive decline in adults. This review explores relationships between Mn-dependent neurobiology and Mn-dependent neurotoxicity. We propose the hypothesis that Mn levels/exposures that are toxic to some biological processes are beneficial for other biological processes and influenced by developmental stage and disease state.
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7 MeSH Terms
Reduced bioavailable manganese causes striatal urea cycle pathology in Huntington's disease mouse model.
Bichell TJV, Wegrzynowicz M, Tipps KG, Bradley EM, Uhouse MA, Bryan M, Horning K, Fisher N, Dudek K, Halbesma T, Umashanker P, Stubbs AD, Holt HK, Kwakye GF, Tidball AM, Colbran RJ, Aschner M, Neely MD, Di Pardo A, Maglione V, Osmand A, Bowman AB
(2017) Biochim Biophys Acta Mol Basis Dis 1863: 1596-1604
MeSH Terms: Animals, Arginase, Corpus Striatum, Disease Models, Animal, Huntington Disease, Male, Manganese, Mice, Neurons, Urea
Show Abstract · Added April 26, 2017
Huntington's disease (HD) is caused by a mutation in the huntingtin gene (HTT), resulting in profound striatal neurodegeneration through an unknown mechanism. Perturbations in the urea cycle have been reported in HD models and in HD patient blood and brain. In neurons, arginase is a central urea cycle enzyme, and the metal manganese (Mn) is an essential cofactor. Deficient biological responses to Mn, and reduced Mn accumulation have been observed in HD striatal mouse and cell models. Here we report in vivo and ex vivo evidence of a urea cycle metabolic phenotype in a prodromal HD mouse model. Further, either in vivo or in vitro Mn supplementation reverses the urea-cycle pathology by restoring arginase activity. We show that Arginase 2 (ARG2) is the arginase enzyme present in these mouse brain models, with ARG2 protein levels directly increased by Mn exposure. ARG2 protein is not reduced in the prodromal stage, though enzyme activity is reduced, indicating that altered Mn bioavailability as a cofactor leads to the deficient enzymatic activity. These data support a hypothesis that mutant HTT leads to a selective deficiency of neuronal Mn at an early disease stage, contributing to HD striatal urea-cycle pathophysiology through an effect on arginase activity.
Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.
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10 MeSH Terms
A Superoxide Dismutase Capable of Functioning with Iron or Manganese Promotes the Resistance of Staphylococcus aureus to Calprotectin and Nutritional Immunity.
Garcia YM, Barwinska-Sendra A, Tarrant E, Skaar EP, Waldron KJ, Kehl-Fie TE
(2017) PLoS Pathog 13: e1006125
MeSH Terms: Animals, Chromatography, Ion Exchange, Disease Models, Animal, Iron, Leukocyte L1 Antigen Complex, Manganese, Mass Spectrometry, Mice, Mice, Inbred C57BL, Polymerase Chain Reaction, Staphylococcal Infections, Staphylococcus aureus, Superoxide Dismutase
Show Abstract · Added April 8, 2017
Staphylococcus aureus is a devastating mammalian pathogen for which the development of new therapeutic approaches is urgently needed due to the prevalence of antibiotic resistance. During infection pathogens must overcome the dual threats of host-imposed manganese starvation, termed nutritional immunity, and the oxidative burst of immune cells. These defenses function synergistically, as host-imposed manganese starvation reduces activity of the manganese-dependent enzyme superoxide dismutase (SOD). S. aureus expresses two SODs, denoted SodA and SodM. While all staphylococci possess SodA, SodM is unique to S. aureus, but the advantage that S. aureus gains by expressing two apparently manganese-dependent SODs is unknown. Surprisingly, loss of both SODs renders S. aureus more sensitive to host-imposed manganese starvation, suggesting a role for these proteins in overcoming nutritional immunity. In this study, we have elucidated the respective contributions of SodA and SodM to resisting oxidative stress and nutritional immunity. These analyses revealed that SodA is important for resisting oxidative stress and for disease development when manganese is abundant, while SodM is important under manganese-deplete conditions. In vitro analysis demonstrated that SodA is strictly manganese-dependent whereas SodM is in fact cambialistic, possessing equal enzymatic activity when loaded with manganese or iron. Cumulatively, these studies provide a mechanistic rationale for the acquisition of a second superoxide dismutase by S. aureus and demonstrate an important contribution of cambialistic SODs to bacterial pathogenesis. Furthermore, they also suggest a new mechanism for resisting manganese starvation, namely populating manganese-utilizing enzymes with iron.
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13 MeSH Terms
"Manganese-induced neurotoxicity: a review of its behavioral consequences and neuroprotective strategies".
Peres TV, Schettinger MR, Chen P, Carvalho F, Avila DS, Bowman AB, Aschner M
(2016) BMC Pharmacol Toxicol 17: 57
MeSH Terms: Animals, Brain, Cognition Disorders, Food, Humans, Manganese, Manganese Poisoning, Motor Skills Disorders, Neuroprotective Agents, Parkinson Disease
Show Abstract · Added April 26, 2017
Manganese (Mn) is an essential heavy metal. However, Mn's nutritional aspects are paralleled by its role as a neurotoxicant upon excessive exposure. In this review, we covered recent advances in identifying mechanisms of Mn uptake and its molecular actions in the brain as well as promising neuroprotective strategies. The authors focused on reporting findings regarding Mn transport mechanisms, Mn effects on cholinergic system, behavioral alterations induced by Mn exposure and studies of neuroprotective strategies against Mn intoxication. We report that exposure to Mn may arise from environmental sources, occupational settings, food, total parenteral nutrition (TPN), methcathinone drug abuse or even genetic factors, such as mutation in the transporter SLC30A10. Accumulation of Mn occurs mainly in the basal ganglia and leads to a syndrome called manganism, whose symptoms of cognitive dysfunction and motor impairment resemble Parkinson's disease (PD). Various neurotransmitter systems may be impaired due to Mn, especially dopaminergic, but also cholinergic and GABAergic. Several proteins have been identified to transport Mn, including divalent metal tranporter-1 (DMT-1), SLC30A10, transferrin and ferroportin and allow its accumulation in the central nervous system. Parallel to identification of Mn neurotoxic properties, neuroprotective strategies have been reported, and these include endogenous antioxidants (for instance, vitamin E), plant extracts (complex mixtures containing polyphenols and non-characterized components), iron chelating agents, precursors of glutathione (GSH), and synthetic compounds that can experimentally afford protection against Mn-induced neurotoxicity.
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10 MeSH Terms