Pnc1p Supports Increases in Cellular NAD(H) Levels in Response to Internal or External Oxidative Stress

Minard, Karyl I.; McAlister-Henn, Lee

doi:10.1021/bi100825z

Cited by 5 publications

(3 citation statements)

References 22 publications

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“…This suggests that a mechanism for inducible cross talk may exist between exogenous and endogenous stimuli. Indeed, exogenous ROS appear to cross talk with endogenous oxidases to activate NF-κB as demonstrated in an NADPH oxidase-deficient mouse model [70]. The magnitudes of the increases in NADPH levels were similar in response to either endogenous or exogenous oxidative stress [71].…”

Section: Discussionmentioning

confidence: 97%

Toll-Like Receptor 4–Mediated Nuclear Factor Kappa B Activation Is Essential for Sensing Exogenous Oxidants to Propagate and Maintain Oxidative/Nitrosative Cellular Stress

Karki

Igwe

2013

PLoS ONE

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The mechanism(s) by which cells can sense exogenous oxidants that may contribute to intracellular oxidative/nitrosative stress is not clear. The objective of this study was to determine how cells might respond to exogenous oxidants to potentially initiate, propagate and/or maintain inflammation associated with many human diseases through NF-κB activation. First, we used HEK-Blue cells that are stably transfected with mouse toll-like receptor 4 (mTLR4) or mouse TLR2. These cells also express optimized secreted embryonic alkaline phosphatase (SEAP) reporter gene under the control of a promoter inducible by NF-κB transcription factor. These cells were challenged with their respective receptor-specific ligands, different pro-oxidants and/or inhibitors that act at different levels of the receptor signaling pathways. A neutralizing antibody directed against TLR4 inhibited responses to both TLR4-specific agonist and a prooxidant, which confirmed that both agents act through TLR4. We used the level of SEAP released into the culture media due to NF-κB activation as a measure of TLR4 or TLR2 stimulation. Pro-oxidants evoked increased release of SEAP from HEK-Blue mTLR4 cells at a much lower concentration compared with release from the HEK-Blue mTLR2 cells. Specific TLR4 signaling pathway inhibitors and oxidant scavengers (anti-oxidants) significantly attenuated oxidant-induced SEAP release by TLR4 stimulation. Furthermore, a novel pro-oxidant that decays to produce the same reactants as activated phagocytes induced inflammatory pain responses in the mouse orofacial region with increased TLR4 expression, and IL-1β and TNFα tissue levels. EUK-134, a synthetic serum-stable scavenger of oxidative species decreased these effects. Our data provide in vitro and related in vivo evidence that exogenous oxidants can induce and maintain inflammation by acting mainly through a TLR4-dependent pathway, with implications in many chronic human ailments.

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Section: Discussionmentioning

confidence: 97%

Toll-Like Receptor 4–Mediated Nuclear Factor Kappa B Activation Is Essential for Sensing Exogenous Oxidants to Propagate and Maintain Oxidative/Nitrosative Cellular Stress

Karki

Igwe

2013

PLoS ONE

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“…Nicotinamidase enzymes play a critical role in maintaining NAD + homeostasis and have been found to contribute to important biological processes in both prokaryotes and eukaryotes, including bacterial pathogenesis (Anderson et al , 2003; Balan et al , 2008; Evans et al , 2010; Frothingham et al , 1996; Ghislain et al , 2002; Hunt et al , 2007; Kim et al , 2004; Minard & McAlister-Henn, 2010; Purser et al , 2003; Raynaud et al , 1998; Silva et al , 2009; van der Horst et al , 2007; Vrablik et al , 2009; Wang & Pichersky, 2007). Because of the absence of nicotinamidases in mammals, these enzymes may be potential drug targets for mammalian pathogens (Sauve, 2008), including the Lyme disease spirochaete B. burgdorferi .…”

Section: Discussionmentioning

confidence: 99%

Molecular characterization of the Borrelia burgdorferi in vivo-essential protein PncA

et al. 2011

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The conversion of nicotinamide to nicotinic acid by nicotinamidase enzymes is a critical step in maintaining NAD+ homeostasis and contributes to numerous important biological processes in diverse organisms. In Borrelia burgdorferi, the nicotinamidase enzyme, PncA, is required for spirochaete survival throughout the infectious cycle. Mammals lack nicotinamidases and therefore PncA may serve as a therapeutic target for Lyme disease. Contrary to the in vivo importance of PncA, the current annotation for the pncA ORF suggests that the encoded protein may be inactive due to the absence of an N-terminal aspartic acid residue that is a conserved member of the catalytic triad of characterized PncA proteins. Herein, we have used genetic and biochemical strategies to determine the N-terminal sequence of B. burgdorferi PncA. Our data demonstrate that the PncA protein is 24 aa longer than the currently annotated sequence and that pncA translation is initiated from the rare, non-canonical initiation codon AUU. These findings are an important first step in understanding the catalytic function of this in vivo-essential protein.

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“…This could be a cellular response to the state of constitutive oxidative stress in mutant cells. Two studies reported that treatment of wild-type cells with H 2 O 2 induced an increase in total NAD + + NADH levels [28,29]. In addition, the salvage pathway appears to be necessary for this increase under oxidative stress conditions [29].…”

Section: Nad + /Nadh Pools In Yfh1 and Aat1 Cellsmentioning

confidence: 99%

Inactivation of mitochondrial aspartate aminotransferase contributes to the respiratory deficit of yeast frataxin-deficient cells

Sliwa

Dairou

Camadro

et al. 2012

Biochemical Journal

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Friedreich's ataxia is a hereditary neurodegenerative disease caused by reduced expression of mitochondrial frataxin. Frataxin deficiency causes impairment in respiratory capacity, disruption of iron homoeostasis and hypersensitivity to oxidants. Although the redox properties of NAD (NAD+ and NADH) are essential for energy metabolism, only few results are available concerning homoeostasis of these nucleotides in frataxin-deficient cells. In the present study, we show that the malate-aspartate NADH shuttle is impaired in Saccharomyces cerevisiae frataxin-deficient cells (Δyfh1) due to decreased activity of cytosolic and mitochondrial isoforms of malate dehydrogenase and to complete inactivation of the mitochondrial aspartate aminotransferase (Aat1). A considerable decrease in the amount of mitochondrial acetylated proteins was observed in the Δyfh1 mutant compared with wild-type. Aat1 is acetylated in wild-type mitochondria and deacetylated in Δyfh1 mitochondria suggesting that inactivation could be due to this post-translational modification. Mutants deficient in iron-sulfur cluster assembly or lacking mitochondrial DNA also showed decreased activity of Aat1, suggesting that Aat1 inactivation was a secondary phenotype in Δyfh1 cells. Interestingly, deletion of the AAT1 gene in a wild-type strain caused respiratory deficiency and disruption of iron homoeostasis without any sensitivity to oxidative stress. Our results show that secondary inactivation of Aat1 contributes to the amplification of the respiratory defect observed in Δyfh1 cells. Further implication of mitochondrial protein deacetylation in the physiology of frataxin-deficient cells is anticipated.

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Pnc1p Supports Increases in Cellular NAD(H) Levels in Response to Internal or External Oxidative Stress

Cited by 5 publications

References 22 publications

Toll-Like Receptor 4–Mediated Nuclear Factor Kappa B Activation Is Essential for Sensing Exogenous Oxidants to Propagate and Maintain Oxidative/Nitrosative Cellular Stress

Toll-Like Receptor 4–Mediated Nuclear Factor Kappa B Activation Is Essential for Sensing Exogenous Oxidants to Propagate and Maintain Oxidative/Nitrosative Cellular Stress

Molecular characterization of the Borrelia burgdorferi in vivo-essential protein PncA

Inactivation of mitochondrial aspartate aminotransferase contributes to the respiratory deficit of yeast frataxin-deficient cells

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