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The Small Protein HemP Is a Transcriptional Activator for the Hemin Uptake Operon in Burkholderia multivorans ATCC 17616. Appl Environ Microbiol 2017. [PMID: 28625994 DOI: 10.1128/aem.00479-17] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Iron and heme play very important roles in various metabolic functions in bacteria, and their intracellular homeostasis is maintained because high concentrations of free forms of these molecules greatly facilitate the Fenton reaction-mediated production of large amounts of reactive oxygen species that severely damage various biomolecules. The ferric uptake regulator (Fur) from Burkholderiamultivorans ATCC 17616 is an iron-responsive global transcriptional regulator, and its fur deletant exhibits pleiotropic phenotypes. In this study, we found that the phenotypes of the fur deletant were suppressed by an additional mutation in hemP The transcription of hemP was negatively regulated by Fur under iron-replete conditions and was constitutive in the fur deletant. Growth of a hemP deletant was severely impaired in a medium containing hemin as the sole iron source, demonstrating the important role of HemP in hemin utilization. HemP was required as a transcriptional activator that specifically binds the promoter-containing region upstream of a Fur-repressive hmuRSTUV operon, which encodes the proteins for hemin uptake. A hmuR deletant was still able to grow using hemin as the sole iron source, albeit at a rate clearly lower than that of the wild-type strain. These results strongly suggested (i) the involvement of HmuR in hemin uptake and (ii) the presence in ATCC 17616 of at least part of other unknown hemin uptake systems whose expression depends on the HemP function. Our in vitro analysis also indicated high-affinity binding of HemP to hemin, and such a property might modulate transcriptional activation of the hmu operon.IMPORTANCE Although the hmuRSTUV genes for the utilization of hemin as a sole iron source have been identified in a few Burkholderia strains, the regulatory expression of these genes has remained unknown. Our analysis in this study using B. multivorans ATCC 17616 showed that its HemP protein is required for expression of the hmuRSTUV operon, and the role of HemP in betaproteobacterial species was elucidated for the first time, to our knowledge, in this study. The HemP protein was also found to have two additional properties that have not been reported for functional homologues in other species; one is that HemP is able to bind to the promoter-containing region of the hmu operon to directly activate its transcription, and the other is that HemP is also required for the expression of an unknown hemin uptake system.
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Yu C, Sun X, Niu Y. An investigation of the developmental neurotoxic potential of curcumol in PC12 cells. Toxicol Mech Methods 2016; 26:635-643. [DOI: 10.1080/15376516.2016.1207735] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Chunlei Yu
- The Institute of Medicine, Qiqihar Medical University, Qiqihar, China
| | - Xiaojie Sun
- Department of Medical Technology, Qiqihar Medical University, Qiqihar, China
| | - Yingcai Niu
- The Institute of Medicine, Qiqihar Medical University, Qiqihar, China
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Li C, Pan Z, Xu T, Zhang C, Wu Q, Niu Y. Puerarin induces the upregulation of glutathione levels and nuclear translocation of Nrf2 through PI3K/Akt/GSK-3β signaling events in PC12 cells exposed to lead. Neurotoxicol Teratol 2014; 46:1-9. [PMID: 25195717 DOI: 10.1016/j.ntt.2014.08.007] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Revised: 07/14/2014] [Accepted: 08/29/2014] [Indexed: 01/16/2023]
Abstract
Oxidative stress is thought to be involved in lead-induced toxicity, especially affecting the brain. We reported previously that puerarin possesses antioxidative properties in the nervous system. Therefore, the aim of the present study was to test the hypothesis that puerarin inhibits lead acetate-induced oxidative stress in PC12 cells by interrupting phosphatidylinositol-3 kinase (PI3K)/Akt signaling through increasing glutathione (GSH) synthesis. Our results showed that puerarin attenuates oxidative stress in a concentration-dependent manner in PC12 cells exposed to lead acetate demonstrated by scavenging reactive oxygen species (ROS) and reducing lipid peroxidation (LPO). Treatment with puerarin significantly up-regulates glutamate cysteine ligase catalytic subunit (GCLc) expression both at its mRNA and protein levels, but not glutamate cysteine ligase modifier (GCLm) subunit, accompanying the elevation of cellular glutathione level. The increased nuclear accumulation of nuclear factor erythroid 2-related factor 2 (Nrf2) was not because of increased transcription of Nrf2 as Nrf2 transcript levels did not change after puerarin treatment. The effects of puerarin could be partially blocked by pharmacologic inhibition of PI3K and the glycogen synthase kinase 3β (GSK-3β) pathways with LY294002 and LiCl, respectively. On the other hand, puerarin treatment promoted Akt and GSK-3β phosphorylation in PC12 cells exposed to lead acetate. Moreover, puerarin failed to modulate the phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2), p-c-Jun N-terminal kinases (JNK), and p-p38 mitogen-activated protein kinase (MAPK) demonstrating some specificity for its action on the PI3K/GSK-3β pathway. These findings suggest that puerarin as a phytoestrogen might be an attractive agent for prevention and treatment of chronic diseases related to lead neurotoxicity.
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Affiliation(s)
- Chengchong Li
- The Institute of Medicine, Qiqihar Medical University, Qiqihar 161006, China
| | - Zhi Pan
- Center for New Medicine Research, Changchun University of Chinese Medicine, Changchun 130117, China
| | - Tianjiao Xu
- The Institute of Medicine, Qiqihar Medical University, Qiqihar 161006, China
| | - Chun Zhang
- Ningxia Key Laboratory of Cerebrocranial Diseases, Ningxia Medical University, Yinchuan 750004, China
| | - Qi Wu
- Medical Technology Department, Qiqihar Medical University, Qiqihar 161006, China
| | - Yingcai Niu
- The Institute of Medicine, Qiqihar Medical University, Qiqihar 161006, China.
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Li X, Wang X, Han C, Wang X, Xing G, Zhou L, Li G, Niu Y. Astragaloside IV suppresses collagen production of activated hepatic stellate cells via oxidative stress-mediated p38 MAPK pathway. Free Radic Biol Med 2013; 60:168-76. [PMID: 23459070 DOI: 10.1016/j.freeradbiomed.2013.02.027] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 02/21/2013] [Accepted: 02/22/2013] [Indexed: 01/06/2023]
Abstract
Oxidative stress is involved in hepatic fibrogenesis. Activation of hepatic stellate cells (HSCs), the key effectors in hepatic fibrogenesis, is characterized by overproduction of extracellular matrix. Astragaloside IV, the active component of Radix Astragali, has antioxidant properties and antifibrotic potential in renal fibrosis. Little is known about the role of astragaloside IV in liver and its involvement in hepatic fibrosis. This study aims at evaluating the antifibrotic potential of astragaloside IV and characterizing involved signal transduction pathways in culture-activated HSCs. Our results show that astragaloside IV attenuates oxidative stress in culture-activated HSCs, as demonstrated by scavenging reactive oxygen species and reducing lipid peroxidation, and elevates the level of cellular glutathione by stimulating Nrf2gene expression. Depletion of cellular glutathione by buthionine sulfoximine or abrogation of p38 MAPK by SB-203580 evidently eliminates the inhibitory effects of astragaloside IV on genes relevant to HSC activation. These results demonstrate that astragaloside IV inhibits HSC activation by inhibiting generation of oxidative stress and associated p38 MAPK activation and provide novel insights into the mechanisms of astragaloside IV as an antifibrogenic candidate in the prevention and treatment of liver fibrosis.
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Affiliation(s)
- Xiaoming Li
- Institute of Medicine, Qiqihar Medical University, Qiqihar 161006, China
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Kimura A, Yuhara S, Ohtsubo Y, Nagata Y, Tsuda M. Suppression of pleiotropic phenotypes of a Burkholderia multivorans fur mutant by oxyR mutation. MICROBIOLOGY-SGM 2012; 158:1284-1293. [PMID: 22361941 DOI: 10.1099/mic.0.057372-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Fur (ferric uptake regulator) is an iron-responsive transcriptional regulator in many bacterial species, and the fur mutant of Burkholderia multivorans ATCC 17616 exhibits pleiotropic phenotypes, such as an inability to efficiently use several carbon sources, as well as high sensitivity to hydrogen peroxide (H(2)O(2)), paraquat (a superoxide-producing compound) and nitric oxide (NO). To gain more insight into the pleiotropic role of the Fur protein of ATCC 17616, spontaneous suppressor mutants of the ATCC 17616 fur mutant that restored tolerance to NO were isolated and characterized in this study. The microarray-based comparative genomic analysis and subsequent sequencing analysis indicated that such suppressor mutants had a 2 bp deletion in the oxyR gene, whose orthologues encode H(2)O(2)-responsive transcriptional regulators in other bacterial species. The suppressor mutants and the reconstructed fur-oxyR double-deletion mutant showed indistinguishable phenotypes in that they were all (i) more resistant than the fur mutant to H(2)O(2), superoxide, NO and streptonigrin (an iron-activated antibiotic) and (ii) able to use carbon sources that cannot efficiently support the growth of the fur mutant. These results clearly indicate that the oxyR mutation suppressed the pleiotropic effect of the B. multivorans fur mutant. The fur-oxyR double mutants were found to overexpress the KatG (catalase/peroxidase) and AhpC1 and AhpD (alkyl hydroperoxide reductase subunits C and D) proteins, and their enzymic activities to remove reactive oxygen and nitrogen species were suggested to be responsible for the suppression of phenotypes caused by the fur mutation.
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Affiliation(s)
- Akane Kimura
- Department of Environmental Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Satoshi Yuhara
- Department of Environmental Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Yoshiyuki Ohtsubo
- Department of Environmental Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Yuji Nagata
- Department of Environmental Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
| | - Masataka Tsuda
- Department of Environmental Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
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Osti RZ, Serrano FA, Paschoalin T, Massaoka MHS, Travassos LR, Truzzi DR, Rodrigues EG, Franco DW. The In Vitro and In Vivo Antitumour Activities of Nitrosyl Ruthenium Amine Complexes. Aust J Chem 2012. [DOI: 10.1071/ch12245] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Ruthenium compounds of the type trans-[Ru(NO)(NH3)4(L)]X3, L = N-heterocyclic ligands, P(OEt)3, SO32–, X = BF4– or PF6–, or [Ru(NO)Hedta], were tested for antitumour activity in vitro against murine melanoma and human tumour cells. The ruthenium complexes induced DNA fragmentation and morphological alterations suggestive of necrotic tumour cell death. The calculated IC50 values were lower than 100 μM. Complexes for which L = isn or imN were partially effective in vivo in a syngeneic model of murine melanoma B16F10, increasing animal survival. In addition, the same ruthenium complexes effectively inhibited angiogenesis of HUVEC cells in vitro. The results suggest that these nitrosyl complexes are a promising platform to be explored for the development of novel antitumour agents.
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de Mel A, Murad F, Seifalian AM. Nitric oxide: a guardian for vascular grafts? Chem Rev 2011; 111:5742-67. [PMID: 21663322 DOI: 10.1021/cr200008n] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Achala de Mel
- Centre for Nanotechnology & Regenerative Medicine, Division of Surgery & Interventional Science, University College London, London, United Kingdom
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Ueno S, Kashimoto T, Susa N, Ishikawa M, Kawagoe T, Mizuta K, Nishimura M, Homma-Takeda S, Temma K. Smoking induces bimodal DNA damage in mouse lung. Toxicol Sci 2011; 120:322-30. [PMID: 21239512 DOI: 10.1093/toxsci/kfq397] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
To clarify the relationship between DNA damage and free radical generation caused by smoking in vivo, DNA damage was investigated in the mouse lung by single-cell gel electrophoresis assay after exposure to cigarette smoke (CS) or gas phase cigarette smoke (GPCS). Although GPCS did not induce DNA lesions, bimodal peaks of DNA damage were detected in mouse lung exposed to CS, one immediately after exposure and another 15 min later. Pretreatment with a specific hydroxyl radical (•OH) scavenger completely prevented both types of DNA damage induced by CS. Electron spin resonance (ESR) study of the kinetics of free radical generation in CS or GPCS revealed that •OH could be detected immediately after the spin trapping of CS without chelators (first •OH generation), whereas •OH was also generated gradually with a time lag when the spin trapping was performed with chelators (second •OH generation). Our ESR study also indicated that the first •OH peak was probably generated from H(2)O(2) via a metal-independent pathway, whereas the second •OH peak might have been generated from H(2)O(2) and other sources via at least two different metal-masked pathways. The bimodal DNA damage induced in lung by smoking appears to be the result of a time lag between the first •OH generation and second •OH generation after exposure to the tar in CS.
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Affiliation(s)
- Shunji Ueno
- Laboratory of Veterinary Public Health, School of Veterinary Medicine, Kitasato University, 35-1 Higashi 23-bancho, Towada-shi 034-8628, Japan
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Abstract
Heme oxygenases (HO) catabolize free heme, that is, iron (Fe) protoporphyrin (IX), into equimolar amounts of Fe(2+), carbon monoxide (CO), and biliverdin. The stress-responsive HO-1 isoenzyme affords protection against programmed cell death. The mechanism underlying this cytoprotective effect relies on the ability of HO-1 to catabolize free heme and prevent it from sensitizing cells to undergo programmed cell death. This cytoprotective effect inhibits the pathogenesis of a variety of immune-mediated inflammatory diseases.
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Ferguson HE, Thatcher TH, Olsen KC, Garcia-Bates TM, Baglole CJ, Kottmann RM, Strong ER, Phipps RP, Sime PJ. Peroxisome proliferator-activated receptor-gamma ligands induce heme oxygenase-1 in lung fibroblasts by a PPARgamma-independent, glutathione-dependent mechanism. Am J Physiol Lung Cell Mol Physiol 2009; 297:L912-9. [PMID: 19734319 DOI: 10.1152/ajplung.00148.2009] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Oxidative stress plays an important role in the pathogenesis of pulmonary fibrosis. Heme oxygenase-1 (HO-1) is a key antioxidant enzyme, and overexpression of HO-1 significantly decreases lung inflammation and fibrosis in animal models. Peroxisome proliferator-activated receptor-gamma (PPARgamma) is a transcription factor that regulates adipogenesis, insulin sensitization, and inflammation. We report here that the PPARgamma ligands 15d-PGJ2 and 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO), which have potent antifibrotic effects in vitro, also strongly induce HO-1 expression in primary human lung fibroblasts. Pharmacological and genetic approaches are used to demonstrate that induction of HO-1 is PPARgamma independent. Upregulation of HO-1 coincides with decreased intracellular glutathione (GSH) levels and can be inhibited by N-acetyl cysteine (NAC), a thiol antioxidant and GSH precursor. Upregulation of HO-1 is not inhibited by Trolox, a non-thiol antioxidant, and does not involve the transcription factors AP-1 or Nrf2. CDDO and 15d-PGJ2 contain an alpha/beta unsaturated ketone that acts as an electrophilic center that can form covalent bonds with free reduced thiols. Rosiglitazone, a PPARgamma ligand that lacks an electrophilic center, does not induce HO-1. These data suggest that in human lung fibroblasts, 15d-PGJ2 and CDDO induce HO-1 via a GSH-dependent mechanism involving the formation of covalent bonds between 15d-PGJ2 or CDDO and GSH. Inhibiting HO-1 upregulation with NAC has only a small effect on the antifibrotic properties of 15d-PGJ2 and CDDO in vitro. These results suggest that CDDO and similar electrophilic PPARgamma ligands may have great clinical potential as antifibrotic agents, not only through direct effects on fibroblast differentiation and function, but indirectly by bolstering antioxidant defenses.
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Affiliation(s)
- Heather E Ferguson
- Department of Environmental Medicine, University of Rochester, 601 Elmwood Ave., Box 692, Rochester, NY 14642, USA
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Morse D, Lin L, Choi AMK, Ryter SW. Heme oxygenase-1, a critical arbitrator of cell death pathways in lung injury and disease. Free Radic Biol Med 2009; 47:1-12. [PMID: 19362144 PMCID: PMC3078523 DOI: 10.1016/j.freeradbiomed.2009.04.007] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Revised: 03/17/2009] [Accepted: 04/06/2009] [Indexed: 11/22/2022]
Abstract
Increases in cell death by programmed (i.e., apoptosis, autophagy) or nonprogrammed mechanisms (i.e., necrosis) occur during tissue injury and may contribute to the etiology of several pulmonary or vascular disease states. The low-molecular-weight stress protein heme oxygenase-1 (HO-1) confers cytoprotection against cell death in various models of lung and vascular injury by inhibiting apoptosis, inflammation, and cell proliferation. HO-1 serves a vital metabolic function as the rate-limiting step in the heme degradation pathway and in the maintenance of iron homeostasis. The transcriptional induction of HO-1 occurs in response to multiple forms of chemical and physical cellular stress. The cytoprotective functions of HO-1 may be attributed to heme turnover, as well as to beneficial properties of its enzymatic reaction products: biliverdin-IXalpha, iron, and carbon monoxide (CO). Recent studies have demonstrated that HO-1 or CO inhibits stress-induced extrinsic and intrinsic apoptotic pathways in vitro. A variety of signaling molecules have been implicated in the cytoprotection conferred by HO-1/CO, including autophagic proteins, p38 mitogen-activated protein kinase, signal transducer and activator of transcription proteins, nuclear factor-kappaB, phosphatidylinositol 3-kinase/Akt, and others. Enhanced HO-1 expression or the pharmacological application of HO end-products affords protection in preclinical models of tissue injury, including experimental and transplant-associated ischemia/reperfusion injury, promising potential future therapeutic applications.
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Affiliation(s)
- Danielle Morse
- Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115
| | - Ling Lin
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Pittsburgh Medical Center, Pittsburgh, PA 15213
| | - Augustine M. K. Choi
- Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115
| | - Stefan W. Ryter
- Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115
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Song W, Patel A, Qureshi HY, Han D, Schipper HM, Paudel HK. The Parkinson disease-associated A30P mutation stabilizes alpha-synuclein against proteasomal degradation triggered by heme oxygenase-1 over-expression in human neuroblastoma cells. J Neurochem 2009; 110:719-33. [PMID: 19457084 DOI: 10.1111/j.1471-4159.2009.06165.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Proteosomal degradation of proteins is one of the major mechanisms of intracellular protein turnover. Failure of the proteosome to degrade misfolded protein is implicated in the accumulation of alpha-synuclein in Parkinson's disease (PD). Heme oxygenase-1 (HO-1), an enzyme that converts heme to free iron, carbon monoxide (CO) and biliverdin (bilirubin precursor) is expressed in response to various stressors. HO-1 is up-regulated in PD- and Alzheimer's disease-affected neural tissues. In this study, we found that HO-1 over-expression engenders dose-dependent decreases in alpha-synuclein protein levels in human neuroblastoma M17 cells. When over-expression of HO-1 was silenced in HO-1 transfected cells, level of alpha-synuclein was restored. Likewise, treatment of HO-1 over-expressing cells with the HO-1 inhibitor, tin mesoporphyrin, the iron chelator deferoxamine or antagonist of CO-dependent cGMP activation, methylene blue, mitigated the HO-1-induced reduction in alpha-synuclein levels. Furthermore, when HO-1 over-expressing cells were treated with the proteosome inhibitors, lactacystin and MG132, level of alpha-synuclein was almost completely restored. In contrast to the effect on alpha-synuclein [wild-type (WT)] levels, HO-1 over-expression did not significantly impact PD-associated alpha-synuclein (A30P) levels in these cells. HO-1 also significantly reduced aggregation of alpha-synuclein (WT) but not that of A30P. Our results suggest that HO-1, which is expressed when neurons are exposed to toxic stimuli capable of inducing protein misfolding, triggers proteosomal degradation of proteins and prevents intracellular accumulation of protein aggregates and inclusions. Resistance to HO-1 induced proteosomal degradation may render the familial PD-associated A30P mutation prone to toxic intracellular aggregation.
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Affiliation(s)
- Wei Song
- Bloomfield Center for Research in Aging, Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada
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Bishop A, Hobbs KG, Eguchi A, Jeffrey S, Smallwood L, Pennie C, Anderson J, Estévez AG. Differential sensitivity of oligodendrocytes and motor neurons to reactive nitrogen species: implications for multiple sclerosis. J Neurochem 2009; 109:93-104. [PMID: 19226373 PMCID: PMC2756289 DOI: 10.1111/j.1471-4159.2009.05891.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Depending on its concentration, nitric oxide (NO) has beneficial or toxic effects. In pathological conditions, NO reacts with superoxide to form peroxynitrite, which nitrates proteins forming nitrotyrosine residues (3NY), leading to loss of protein function, perturbation of signal transduction, and cell death. 3NY immunoreactivity is present in many CNS diseases, particularly multiple sclerosis. Here, using the high flux NO donor, spermine-NONOate, we report that oligodendrocytes are resistant to NO, while motor neurons are NO sensitive. Motor neuron sensitivity correlates with the NO-dependent formation of 3NY, which is significantly more pronounced in motor neurons when compared with oligodendrocytes, suggesting peroxynitrite as the toxic molecule. The heme-metabolizing enzyme, heme-oxygenase-1 (HO1), is necessary for oligodendrocyte NO resistance, as demonstrated by loss of resistance after HO1 inhibition. Resistance is reinstated by peroxynitrite scavenging with uric acid further implicating peroxynitrite as responsible for NO sensitivity. Most importantly, differential sensitivity to NO is also present in cultures of primary oligodendrocytes and motor neurons. Finally, motor neurons cocultured with oligodendrocytes, or oligodendrocyte-conditioned media, become resistant to NO toxicity. Preliminary studies suggest oligodendrocytes release a soluble factor that protects motor neurons. Our findings challenge the current paradigm that oligodendrocytes are the exclusive target of multiple sclerosis pathology.
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Affiliation(s)
- Amy Bishop
- Department of Biological Sciences, University of Alabama in Huntsville, Huntsville, Alabama 35899, USA.
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Baglole CJ, Sime PJ, Phipps RP. Cigarette smoke-induced expression of heme oxygenase-1 in human lung fibroblasts is regulated by intracellular glutathione. Am J Physiol Lung Cell Mol Physiol 2008; 295:L624-36. [PMID: 18689604 DOI: 10.1152/ajplung.90215.2008] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Fibroblasts are key structural cells that can be damaged by cigarette smoke. Cigarette smoke contains many components capable of eliciting oxidative stress, which may induce heme oxygenase (HO)-1, a cytoprotective enzyme. There are no data on HO-1 expression in primary human lung fibroblasts after cigarette smoke extract (CSE) exposure. We hypothesized that human lung fibroblasts exposed to cigarette smoke would increase HO-1 though changes in intracellular glutathione (GSH). Primary human lung fibroblasts were exposed to CSE, and changes in HO-1 expression and GSH levels were assessed. CSE induced a time- and dose-dependent increase in expression of HO-1, but not HO-2 or biliverdin reductase, in two different primary human lung fibroblast strains, a novel finding. This induction of HO-1 paralleled a decrease in intracellular GSH, and a sustained reduction in GSH resulted in a dramatic increase in HO-1. Treatment with the antioxidants N-acetyl-l-cysteine or GSH reduced the expression of HO-1 induced by CSE. We also examined the signal transduction mechanism responsible for HO-1 induction. Nuclear factor erythroid-derived 2, like 2 (Nrf2) was not involved in HO-1 induction by CSE. Activator protein-1 (AP-1) is a redox-sensitive transcription factor shown in other systems to regulate HO-1 expression. CSE exposure resulted in nuclear accumulation of c-Fos and c-Jun, two key AP-1 components. Reduction of c-Fos and c-Jun nuclear translocation by SP-600125 attenuated the CSE-induced expression of HO-1. These data support the concept that changes in the cellular redox status brought on by cigarette smoke induce HO-1 in fibroblasts. This increase in HO-1 may help protect against cigarette smoke-induced inflammation and/or cell death.
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Affiliation(s)
- Carolyn J Baglole
- University of Rochester School of Medicine and Dentistry, Dept. of Environmental Medicine, Rochester, NY 14642, USA
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Brynczka C, Merrick BA. Nerve growth factor potentiates p53 DNA binding but inhibits nitric oxide-induced apoptosis in neuronal PC12 cells. Neurochem Res 2007; 32:1573-85. [PMID: 17592775 PMCID: PMC2231119 DOI: 10.1007/s11064-007-9362-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Accepted: 04/25/2007] [Indexed: 12/16/2022]
Abstract
NGF is recognized for its role in neuronal differentiation and maintenance. Differentiation of PC12 cells by NGF involves p53, a transcription factor that controls growth arrest and apoptosis. We investigated NGF influence over p53 activity during NO-induced apoptosis by sodium nitroprusside in differentiated and mitotic PC12 cells. NGF-differentiation produced increased p53 levels, nuclear localization and sequence-specific DNA binding. Apoptosis in mitotic cells also produced these events but the accompanying activation of caspases 1-10 and mitochondrial depolarization were inhibited during NGF differentiation and could be reversed in p53-silenced cells. Transcriptional regulation of PUMA and survivin expression were not inhibited by NGF, although NO-induced mitochondrial depolarization was dependent upon de novo gene transcription and only occurred in mitotic cells. We conclude that NGF mediates prosurvival signaling by increasing factors such as Bcl-2 and p21(Waf1/Cip1) without altering p53 transcriptional activity to inhibit mitochondrial depolarization, caspase activation and apoptosis.
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Affiliation(s)
- Christopher Brynczka
- National Center for Toxicogenomics, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709
- Department of Environmental and Molecular Toxicology, North Carolina State University, Raleigh, North Carolina 27606
| | - B. Alex Merrick
- National Center for Toxicogenomics, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709
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