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Seiple LA, Cardellina JH, Akee R, Stivers JT. Potent inhibition of human apurinic/apyrimidinic endonuclease 1 by arylstibonic acids. Mol Pharmacol 2007; 73:669-77. [PMID: 18042731 DOI: 10.1124/mol.107.042622] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Human apurinic/apyrimidinic endonuclease (Ape1) plays an important role by processing the >10,000 highly toxic abasic sites generated in the genome of each cell every day. Ape1 has recently emerged as a target for inhibition, in that its overexpression in tumors has been linked with poor response to both radiation and chemotherapy and lower overall patient survival. Inhibition of Ape1 using siRNA or the expression of a dominant-negative form of the protein has been shown to sensitize cells to DNA-damaging agents, including various chemotherapeutic agents. However, potent small-molecule inhibitors of Ape1 remain to be found. To this end, we screened Ape1 against the NCI Diversity Set of small molecules and discovered aromatic nitroso, carboxylate, sulfonamide, and arylstibonic acid compounds with micromolar affinities for the protein. A further screen of a 37-compound arylstibonic acid sublibrary identified ligands with IC(50) values in the range of 4 to 300 nM. The negatively charged stibonic acids act by a partial-mixed mode and probably serve as DNA phosphate mimics. These compounds provide a useful scaffold for development of chemotherapeutic agents against Ape1.
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Affiliation(s)
- Lauren A Seiple
- The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore MD 21205-2185, USA
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203
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Guikema JEJ, Linehan EK, Tsuchimoto D, Nakabeppu Y, Strauss PR, Stavnezer J, Schrader CE. APE1- and APE2-dependent DNA breaks in immunoglobulin class switch recombination. ACTA ACUST UNITED AC 2007; 204:3017-26. [PMID: 18025127 PMCID: PMC2118529 DOI: 10.1084/jem.20071289] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Antibody class switch recombination (CSR) occurs by an intrachromosomal deletion requiring generation of double-stranded breaks (DSBs) in switch-region DNA. The initial steps in DSB formation have been elucidated, involving cytosine deamination by activation-induced cytidine deaminase and generation of abasic sites by uracil DNA glycosylase. However, it is not known how abasic sites are converted into single-stranded breaks and, subsequently, DSBs. Apurinic/apyrimidinic endonuclease (APE) efficiently nicks DNA at abasic sites, but it is unknown whether APE participates in CSR. We address the roles of the two major mammalian APEs, APE1 and APE2, in CSR. APE1 deficiency causes embryonic lethality in mice; we therefore examined CSR and DSBs in mice deficient in APE2 and haploinsufficient for APE1. We show that both APE1 and APE2 function in CSR, resulting in the DSBs necessary for CSR and thereby describing a novel in vivo function for APE2.
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Affiliation(s)
- Jeroen E J Guikema
- Department of Molecular Genetics and Microbiology, Program in Immunology and Virology, University of Massachusetts Medical School, Worcester, MA 01655, USA
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204
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Abstract
Elevated plasma levels of homocysteine are a metabolic risk factor for atherosclerotic vascular disease, as shown in numerous clinical studies that linked elevated homocysteine levels to de novo and recurrent cardiovascular events. High levels of homocysteine promote oxidant stress in vascular cells and tissue because of the formation of reactive oxygen species (ROS), which have been strongly implicated in the development of atherosclerosis. In particular, ROS have been shown to cause endothelial injury, dysfunction, and activation. Elevated homocysteine stimulates proinflammatory pathways in vascular cells, resulting in leukocyte recruitment to the vessel wall, mediated by the expression of adhesion molecules on endothelial cells and circulating monocytes and neutrophils, in the infiltration of leukocytes into the arterial wall mediated by increased secretion of chemokines, and in the differentiation of monocytes into cholesterol-scavenging macrophages. Furthermore, it stimulates the proliferation of vascular smooth muscle cells followed by the production of extracellular matrix. Many of these events involve redox-sensitive signaling events, which are promoted by elevated homocysteine, and result in the formation of atherosclerotic lesions. In this article, we review current knowledge about the role of homocysteine on oxidant stress-mediated vascular inflammation during the development of atherosclerosis.
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Affiliation(s)
- Louisa Papatheodorou
- Department of Vascular Medicine, Medical Policlinic-City Campus, University of Munich Medical Center, Munich, Germany
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205
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Hecker A, Leulliot N, Gadelle D, Graille M, Justome A, Dorlet P, Brochier C, Quevillon-Cheruel S, Le Cam E, van Tilbeurgh H, Forterre P. An archaeal orthologue of the universal protein Kae1 is an iron metalloprotein which exhibits atypical DNA-binding properties and apurinic-endonuclease activity in vitro. Nucleic Acids Res 2007; 35:6042-51. [PMID: 17766251 PMCID: PMC2094082 DOI: 10.1093/nar/gkm554] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The Kae1 (Kinase-associated endopeptidase 1) protein is a member of the recently identified transcription complex EKC and telomeres maintenance complex KEOPS in yeast. Kae1 homologues are encoded by all sequenced genomes in the three domains of life. Although annotated as putative endopeptidases, the actual functions of these universal proteins are unknown. Here we show that the purified Kae1 protein (Pa-Kae1) from Pyrococcus abyssi is an iron-protein with a novel type of ATP-binding site. Surprisingly, this protein did not exhibit endopeptidase activity in vitro but binds cooperatively to single and double-stranded DNA and induces unusual DNA conformational change. Furthermore, Pa-Kae1 exhibits a class I apurinic (AP)-endonuclease activity (AP-lyase). Both DNA binding and AP-endonuclease activity are inhibited by ATP. Kae1 is thus a novel and atypical universal DNA interacting protein whose importance could rival those of RecA (RadA/Rad51) in the maintenance of genome integrity in all living cells.
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Affiliation(s)
- Arnaud Hecker
- Institut de Génétique et Microbiologie, Univ. Paris-Sud, IFR115, UMR8621-CNRS, 91405 Orsay, France, Institut de Biochimie et de Biophysique Moléculaire et Cellulaire, Univ. Paris-Sud, IFR115, UMR8619-CNRS, 91405 Orsay, France, Institut Gustave Roussy, Interactions Moléculaires et Cancer, UMR8126-CNRS, 94805 Villejuif Cedex, France, Institut de Chimie Moléculaire et des Matériaux, Univ. Paris-Sud, UMR8182-CNRS, 91405 Orsay, France, Institut de Biologie Structurale et de Microbiologie, Laboratoire de Chimie Bactérienne, UPR9043-CNRS, 13402 Marseille Cedex 20, France, Université de Provence - Aix-Marseille I, 13331 Marseille Cedex 3, France and Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, 25 rue du Dr Roux, 75724 Paris Cedex 15, France
| | - Nicolas Leulliot
- Institut de Génétique et Microbiologie, Univ. Paris-Sud, IFR115, UMR8621-CNRS, 91405 Orsay, France, Institut de Biochimie et de Biophysique Moléculaire et Cellulaire, Univ. Paris-Sud, IFR115, UMR8619-CNRS, 91405 Orsay, France, Institut Gustave Roussy, Interactions Moléculaires et Cancer, UMR8126-CNRS, 94805 Villejuif Cedex, France, Institut de Chimie Moléculaire et des Matériaux, Univ. Paris-Sud, UMR8182-CNRS, 91405 Orsay, France, Institut de Biologie Structurale et de Microbiologie, Laboratoire de Chimie Bactérienne, UPR9043-CNRS, 13402 Marseille Cedex 20, France, Université de Provence - Aix-Marseille I, 13331 Marseille Cedex 3, France and Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, 25 rue du Dr Roux, 75724 Paris Cedex 15, France
| | - Danièle Gadelle
- Institut de Génétique et Microbiologie, Univ. Paris-Sud, IFR115, UMR8621-CNRS, 91405 Orsay, France, Institut de Biochimie et de Biophysique Moléculaire et Cellulaire, Univ. Paris-Sud, IFR115, UMR8619-CNRS, 91405 Orsay, France, Institut Gustave Roussy, Interactions Moléculaires et Cancer, UMR8126-CNRS, 94805 Villejuif Cedex, France, Institut de Chimie Moléculaire et des Matériaux, Univ. Paris-Sud, UMR8182-CNRS, 91405 Orsay, France, Institut de Biologie Structurale et de Microbiologie, Laboratoire de Chimie Bactérienne, UPR9043-CNRS, 13402 Marseille Cedex 20, France, Université de Provence - Aix-Marseille I, 13331 Marseille Cedex 3, France and Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, 25 rue du Dr Roux, 75724 Paris Cedex 15, France
| | - Marc Graille
- Institut de Génétique et Microbiologie, Univ. Paris-Sud, IFR115, UMR8621-CNRS, 91405 Orsay, France, Institut de Biochimie et de Biophysique Moléculaire et Cellulaire, Univ. Paris-Sud, IFR115, UMR8619-CNRS, 91405 Orsay, France, Institut Gustave Roussy, Interactions Moléculaires et Cancer, UMR8126-CNRS, 94805 Villejuif Cedex, France, Institut de Chimie Moléculaire et des Matériaux, Univ. Paris-Sud, UMR8182-CNRS, 91405 Orsay, France, Institut de Biologie Structurale et de Microbiologie, Laboratoire de Chimie Bactérienne, UPR9043-CNRS, 13402 Marseille Cedex 20, France, Université de Provence - Aix-Marseille I, 13331 Marseille Cedex 3, France and Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, 25 rue du Dr Roux, 75724 Paris Cedex 15, France
| | - Anthony Justome
- Institut de Génétique et Microbiologie, Univ. Paris-Sud, IFR115, UMR8621-CNRS, 91405 Orsay, France, Institut de Biochimie et de Biophysique Moléculaire et Cellulaire, Univ. Paris-Sud, IFR115, UMR8619-CNRS, 91405 Orsay, France, Institut Gustave Roussy, Interactions Moléculaires et Cancer, UMR8126-CNRS, 94805 Villejuif Cedex, France, Institut de Chimie Moléculaire et des Matériaux, Univ. Paris-Sud, UMR8182-CNRS, 91405 Orsay, France, Institut de Biologie Structurale et de Microbiologie, Laboratoire de Chimie Bactérienne, UPR9043-CNRS, 13402 Marseille Cedex 20, France, Université de Provence - Aix-Marseille I, 13331 Marseille Cedex 3, France and Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, 25 rue du Dr Roux, 75724 Paris Cedex 15, France
| | - Pierre Dorlet
- Institut de Génétique et Microbiologie, Univ. Paris-Sud, IFR115, UMR8621-CNRS, 91405 Orsay, France, Institut de Biochimie et de Biophysique Moléculaire et Cellulaire, Univ. Paris-Sud, IFR115, UMR8619-CNRS, 91405 Orsay, France, Institut Gustave Roussy, Interactions Moléculaires et Cancer, UMR8126-CNRS, 94805 Villejuif Cedex, France, Institut de Chimie Moléculaire et des Matériaux, Univ. Paris-Sud, UMR8182-CNRS, 91405 Orsay, France, Institut de Biologie Structurale et de Microbiologie, Laboratoire de Chimie Bactérienne, UPR9043-CNRS, 13402 Marseille Cedex 20, France, Université de Provence - Aix-Marseille I, 13331 Marseille Cedex 3, France and Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, 25 rue du Dr Roux, 75724 Paris Cedex 15, France
| | - Céline Brochier
- Institut de Génétique et Microbiologie, Univ. Paris-Sud, IFR115, UMR8621-CNRS, 91405 Orsay, France, Institut de Biochimie et de Biophysique Moléculaire et Cellulaire, Univ. Paris-Sud, IFR115, UMR8619-CNRS, 91405 Orsay, France, Institut Gustave Roussy, Interactions Moléculaires et Cancer, UMR8126-CNRS, 94805 Villejuif Cedex, France, Institut de Chimie Moléculaire et des Matériaux, Univ. Paris-Sud, UMR8182-CNRS, 91405 Orsay, France, Institut de Biologie Structurale et de Microbiologie, Laboratoire de Chimie Bactérienne, UPR9043-CNRS, 13402 Marseille Cedex 20, France, Université de Provence - Aix-Marseille I, 13331 Marseille Cedex 3, France and Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, 25 rue du Dr Roux, 75724 Paris Cedex 15, France
| | - Sophie Quevillon-Cheruel
- Institut de Génétique et Microbiologie, Univ. Paris-Sud, IFR115, UMR8621-CNRS, 91405 Orsay, France, Institut de Biochimie et de Biophysique Moléculaire et Cellulaire, Univ. Paris-Sud, IFR115, UMR8619-CNRS, 91405 Orsay, France, Institut Gustave Roussy, Interactions Moléculaires et Cancer, UMR8126-CNRS, 94805 Villejuif Cedex, France, Institut de Chimie Moléculaire et des Matériaux, Univ. Paris-Sud, UMR8182-CNRS, 91405 Orsay, France, Institut de Biologie Structurale et de Microbiologie, Laboratoire de Chimie Bactérienne, UPR9043-CNRS, 13402 Marseille Cedex 20, France, Université de Provence - Aix-Marseille I, 13331 Marseille Cedex 3, France and Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, 25 rue du Dr Roux, 75724 Paris Cedex 15, France
| | - Eric Le Cam
- Institut de Génétique et Microbiologie, Univ. Paris-Sud, IFR115, UMR8621-CNRS, 91405 Orsay, France, Institut de Biochimie et de Biophysique Moléculaire et Cellulaire, Univ. Paris-Sud, IFR115, UMR8619-CNRS, 91405 Orsay, France, Institut Gustave Roussy, Interactions Moléculaires et Cancer, UMR8126-CNRS, 94805 Villejuif Cedex, France, Institut de Chimie Moléculaire et des Matériaux, Univ. Paris-Sud, UMR8182-CNRS, 91405 Orsay, France, Institut de Biologie Structurale et de Microbiologie, Laboratoire de Chimie Bactérienne, UPR9043-CNRS, 13402 Marseille Cedex 20, France, Université de Provence - Aix-Marseille I, 13331 Marseille Cedex 3, France and Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, 25 rue du Dr Roux, 75724 Paris Cedex 15, France
| | - Herman van Tilbeurgh
- Institut de Génétique et Microbiologie, Univ. Paris-Sud, IFR115, UMR8621-CNRS, 91405 Orsay, France, Institut de Biochimie et de Biophysique Moléculaire et Cellulaire, Univ. Paris-Sud, IFR115, UMR8619-CNRS, 91405 Orsay, France, Institut Gustave Roussy, Interactions Moléculaires et Cancer, UMR8126-CNRS, 94805 Villejuif Cedex, France, Institut de Chimie Moléculaire et des Matériaux, Univ. Paris-Sud, UMR8182-CNRS, 91405 Orsay, France, Institut de Biologie Structurale et de Microbiologie, Laboratoire de Chimie Bactérienne, UPR9043-CNRS, 13402 Marseille Cedex 20, France, Université de Provence - Aix-Marseille I, 13331 Marseille Cedex 3, France and Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, 25 rue du Dr Roux, 75724 Paris Cedex 15, France
| | - Patrick Forterre
- Institut de Génétique et Microbiologie, Univ. Paris-Sud, IFR115, UMR8621-CNRS, 91405 Orsay, France, Institut de Biochimie et de Biophysique Moléculaire et Cellulaire, Univ. Paris-Sud, IFR115, UMR8619-CNRS, 91405 Orsay, France, Institut Gustave Roussy, Interactions Moléculaires et Cancer, UMR8126-CNRS, 94805 Villejuif Cedex, France, Institut de Chimie Moléculaire et des Matériaux, Univ. Paris-Sud, UMR8182-CNRS, 91405 Orsay, France, Institut de Biologie Structurale et de Microbiologie, Laboratoire de Chimie Bactérienne, UPR9043-CNRS, 13402 Marseille Cedex 20, France, Université de Provence - Aix-Marseille I, 13331 Marseille Cedex 3, France and Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, 25 rue du Dr Roux, 75724 Paris Cedex 15, France
- *To whom correspondence should be addressed. +33 1 69 15 74 89+33 1 69 15 78 08 Correspondence may also be addressed to Herman van Tilbeurgh.
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206
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Penning TM, Drury JE. Human aldo-keto reductases: Function, gene regulation, and single nucleotide polymorphisms. Arch Biochem Biophys 2007; 464:241-50. [PMID: 17537398 PMCID: PMC2025677 DOI: 10.1016/j.abb.2007.04.024] [Citation(s) in RCA: 215] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2007] [Revised: 04/24/2007] [Accepted: 04/24/2007] [Indexed: 01/31/2023]
Abstract
Aldo-keto reductases (AKRs) are a superfamily of NAD(P)H linked oxidoreductases that are generally monomeric 34-37kDa proteins present in all phyla. The superfamily consists of 15 families, which contains 151 members (www.med.upenn.edu/akr). Thirteen human AKRs exist that use endogenous substrates (sugar and lipid aldehydes, prostaglandins, retinals and steroid hormones), and in many instances they regulate nuclear receptor signaling. Exogenous substrates include metabolites implicated in chemical carcinogenesis: NNK (4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone), polycyclic aromatic hydrocarbon trans-dihydrodiols, and aflatoxin dialdehyde. Promoter analysis of the human genes identifies common elements involved in their regulation which include osmotic response elements, anti-oxidant response elements, xenobiotic response elements, AP-1 sites and steroid response elements. The human AKRs are highly polymorphic, and in some instances single nucleotide polymorphisms (SNPs) of high penetrance exist. This suggests that there will be inter-individual variation in endogenous and xenobiotic metabolism which in turn affect susceptibility to nuclear receptor signaling and chemical carcinogenesis.
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Affiliation(s)
- Trevor M Penning
- Center of Excellence in Environmental Toxicology, Department of Pharmacology, University of Pennsylvania School of Medicine, 130 C John Morgan Bldg., 3620 Hamilton Walk, Philadelphia, PA 19104-6084, USA.
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207
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Merluzzi S, D'Orlando O, Leonardi A, Vitale G, Pucillo C. TRAF2 and p38 are involved in B cells CD40-mediated APE/Ref-1 nuclear translocation: a novel pathway in B cell activation. Mol Immunol 2007; 45:76-86. [PMID: 17599408 DOI: 10.1016/j.molimm.2007.05.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2007] [Accepted: 05/13/2007] [Indexed: 12/31/2022]
Abstract
The interaction between CD40 and its ligand CD40L plays a key role in the regulation of B cell proliferation, activation, isotype switching and the humoral memory response. APE/Ref-1 plays a key role in transcriptional responses during CD40-mediated B cell activation. It is demonstrated that CD40 signaling is mediated principally through TRAF adapter proteins. Different TRAFs exhibit specific biological functions and the role of individual TRAFs in the activation of different CD40-dependent signaling pathways has not yet been defined. To better understand the role of these factors in CD40-mediated B cell activation and how they contribute to APE/Ref-1 activity, we investigated the TRAF molecules and the downstream protein kinases directly activated in the pathways triggered by CD40. Here we show that TRAF2 is involved in CD40-mediated induction of APE/Ref-1 nuclear translocation and that the two proteins physically interact in vitro and in vivo. Moreover, treatment with the p38 inhibitor, SB203580 or site directed mutagenesis of the serine 54 (Ser(54)) in the MAP kinase consensus site present in APE/Ref-1 blocks its nuclear translocation caused by CD40-mediated B cell activation and reveals a potential role of p38 in this pathway. These data together uncovers a new signaling pathway regulating APE/Ref-1 nuclear translocation involving CD40-crosslinking, TRAF2 and p38.
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Affiliation(s)
- Sonia Merluzzi
- Dipartimento di Scienze e Tecnologie Biomediche, Università di Udine, P.le Kolbe 4, I-33100 Udine, Italy
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208
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Abstract
Maintenance of normal intracellular redox status plays an important role in such processes as DNA synthesis, gene expression, enzymatic activity, and others. In addition, it is clear that changes in the redox status of intracellular content and individual molecules, resulting from stress or intrinsic cellular activity, are involved in the regulation of different processes in cells. Small changes in intracellular levels of reactive oxygen species participate in intracellular signaling. Thiol-containing molecules, such as glutathione, thioredoxins, glutaredoxins, and peroxiredoxins, also play an important role in maintaining redox homeostasis and redox regulation. This review attempts to summarize the current knowledge about redox regulation in different cell types.
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Affiliation(s)
- O N Oktyabrsky
- Institute of Ecology and Genetics of Microorganisms, Urals Division of the Russian Academy of Sciences, 614081 Perm', Russia.
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209
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Dyrkheeva NS, Khodyreva SN, Lavrik OI. Multifunctional human apurinic/apyrimidinic endonuclease 1: Role of additional functions. Mol Biol 2007. [DOI: 10.1134/s0026893307030065] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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210
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Cesaratto L, Calligaris SD, Vascotto C, Deganuto M, Bellarosa C, Quadrifoglio F, Ostrow JD, Tiribelli C, Tell G. Bilirubin-induced cell toxicity involves PTEN activation through an APE1/Ref-1-dependent pathway. J Mol Med (Berl) 2007; 85:1099-112. [PMID: 17479230 DOI: 10.1007/s00109-007-0204-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2006] [Revised: 03/31/2007] [Accepted: 04/04/2007] [Indexed: 12/19/2022]
Abstract
Unconjugated bilirubin (UCB) is the major degradation product of the heme catabolism. A growing body of evidences suggests that UCB plays major biological effects by inhibiting cell proliferation in cancer cell lines and eliciting cell toxicity particularly in neurons and glial cells. Early molecular events responsible for bilirubin-induced cytotoxicity remain poorly understood. Using HeLa cells and mouse embryonic fibroblasts, we found that UCB at a concentration of free pigment (Bf) of 80 nM induced oxidative stress, promoting a significant increase in intracellular reactive oxygen species (ROS) and a decreased cell survival (by the MTT test). The ROS increase activated the antioxidant cell response through APE1/Ref-1, a master redox regulator in eukaryotic cells. Activation of APE1/Ref-1 was followed by a concomitant activation of Egr-1 transcription factor and by an upregulation of PTEN tumor suppressor, an Egr-1 target gene, leading to inhibition of cell growth. Blocking ROS generation with N-acetylcysteine pretreatment, restored cell survival, limited the upregulation of PTEN in response to UCB, and prevented the inhibition of cell proliferation. HeLa cells transfected with mutants of the PTEN promoter or silenced with APE1/Ref-1 small interference RNA confirmed that UCB modulates a signaling pathway involving APE1/Ref-1, Egr-1, and PTEN. These findings describe a new molecular pathway involved in the cytotoxic effects of UCB.
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Affiliation(s)
- Laura Cesaratto
- Department of Biomedical Sciences and Technologies, University of Udine, 33100, Udine, Italy
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211
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Fishel ML, Kelley MR. The DNA base excision repair protein Ape1/Ref-1 as a therapeutic and chemopreventive target. Mol Aspects Med 2007; 28:375-95. [PMID: 17560642 DOI: 10.1016/j.mam.2007.04.005] [Citation(s) in RCA: 205] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Accepted: 04/15/2007] [Indexed: 10/23/2022]
Abstract
With our growing understanding of the pathways involved in cell proliferation and signaling, targeted therapies, in the treatment of cancer are entering the clinical arena. New and emerging targets are proteins involved in DNA repair pathways. Inhibition of various proteins in the DNA repair pathways sensitizes cancer cells to DNA damaging agents such as chemotherapy and/or radiation. We study the apurinic endonuclease 1/redox factor-1 (Ape1/Ref-1) and believe that its crucial function in DNA repair and reduction-oxidation or redox signaling make it an excellent target for sensitizing tumor cells to chemotherapy. Ape1/Ref-1 is an essential enzyme in the base excision repair (BER) pathway which is responsible for the repair of DNA caused by oxidative and alkylation damage. As importantly, Ape1/Ref-1 also functions as a redox factor maintaining transcription factors in an active reduced state. Ape1/Ref-1 stimulates the DNA binding activity of numerous transcription factors that are involved in cancer promotion and progression such as AP-1 (Fos/Jun), NFkappaB, HIF-1alpha, CREB, p53 and others. We will discuss what is known regarding the pharmacological targeting of the DNA repair activity, as well as the redox activity of Ape1/Ref-1, and explore the budding clinical utility of inhibition of either of these functions in cancer treatment. A brief discussion of the effect of polymorphisms in its DNA sequence is included because of Ape1/Ref-1's importance to maintenance and integrity of the genome. Experimental modification of Ape1/Ref-1 activity changes the response of cells and of organisms to DNA damaging agents, suggesting that Ape1/Ref-1 may also be a productive target of chemoprevention. In this review, we will provide an overview of Ape1/Ref-1's activities and explore the potential of this protein as a target in cancer treatment as well as its role in chemoprevention.
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Affiliation(s)
- Melissa L Fishel
- Department of Pediatrics (Section of Hematology/Oncology), Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, United States
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212
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Gollnick SO, Lee BY, Vaughan L, Owczarczak B, Henderson BW. Activation of the IL-10 Gene Promoter Following Photodynamic Therapy of Murine Keratinocytes¶. Photochem Photobiol 2007. [DOI: 10.1562/0031-8655(2001)0730170aotigp2.0.co2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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213
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Agapakis-Caussé C, Boscá F, Castell JV, Hernández D, Marín ML, Marrot L, Miranda MA. Tiaprofenic Acid-photosensitized Damage to Nucleic Acids: A Mechanistic Study Using Complementary in vitro Approaches. Photochem Photobiol 2007. [DOI: 10.1562/0031-8655(2000)0710499tapdtn2.0.co2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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214
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Abstract
Aldo-keto reductases (AKRs) are soluble NAD(P)(H) oxidoreductases that primarily reduce aldehydes and ketones to primary and secondary alcohols, respectively. The ten known human AKR enzymes can turnover a vast range of substrates, including drugs, carcinogens, and reactive aldehydes. They play central roles in the metabolism of these agents, and this can lead to either their bioactivation or detoxication. AKRs are Phase I drug metabolizing enzymes for a variety of carbonyl-containing drugs and are implicated in cancer chemotherapeutic drug resistance. They are involved in tobacco-carcinogenesis because they activate polycyclic aromatic trans-dihydrodiols to yield reactive and redox active o-quinones, but they also catalyze the detoxication of nicotine derived nitrosamino ketones. They also detoxify reactive aldehydes formed from exogenous toxicants, e.g., aflatoxin, endogenous toxicants, and those formed from the breakdown of lipid peroxides. AKRs are stress-regulated genes and play a central role in the cellular response to osmotic, electrophilic, and oxidative stress.
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Affiliation(s)
- Yi Jin
- Department of Pharmacology, Center of Excellence in Environmental Toxicology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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215
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Almeida KH, Sobol RW. A unified view of base excision repair: lesion-dependent protein complexes regulated by post-translational modification. DNA Repair (Amst) 2007; 6:695-711. [PMID: 17337257 PMCID: PMC1995033 DOI: 10.1016/j.dnarep.2007.01.009] [Citation(s) in RCA: 306] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2007] [Accepted: 01/22/2007] [Indexed: 12/29/2022]
Abstract
Base excision repair (BER) proteins act upon a significantly broad spectrum of DNA lesions that result from endogenous and exogenous sources. Multiple sub-pathways of BER (short-path or long-patch) and newly designated DNA repair pathways (e.g., SSBR and NIR) that utilize BER proteins complicate any comprehensive understanding of BER and its role in genome maintenance, chemotherapeutic response, neuro-degeneration, cancer or aging. Herein, we propose a unified model of BER, comprised of three functional processes: Lesion Recognition/Strand Scission, Gap Tailoring and DNA Synthesis/Ligation, each represented by one or more multi-protein complexes and coordinated via the XRCC1/DNA Ligase III and PARP1 scaffold proteins. BER therefore may be represented by a series of repair complexes that assemble at the site of the DNA lesion and mediates repair in a coordinated fashion involving protein-protein interactions that dictate subsequent steps or sub-pathway choice. Complex formation is influenced by post-translational protein modifications that arise from the cellular state or the DNA damage response, providing an increase in specificity and efficiency to the BER pathway. In this review, we have summarized the reported BER protein-protein interactions and protein post-translational modifications and discuss the impact on DNA repair capacity and complex formation.
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Affiliation(s)
- Karen H. Almeida
- Department of Physical Sciences, Rhode Island College, 600 Mt. Pleasant Ave., Providence RI 02908-1991
| | - Robert W. Sobol
- Department of Pharmacology, University of Pittsburgh School of Medicine & University of Pittsburgh Cancer Institute, Hillman Cancer Center, Research Pavilion, Suite 2.6, 5117 Centre Avenue, Pittsburgh, PA 15213-1863
- *To whom correspondence should be addressed: Robert W. Sobol, Ph.D., Tel. 412-623-7764, Fax 412-623-7761, e-mail
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216
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Berndt SI, Huang WY, Fallin MD, Helzlsouer KJ, Platz EA, Weissfeld JL, Church TR, Welch R, Chanock SJ, Hayes RB. Genetic variation in base excision repair genes and the prevalence of advanced colorectal adenoma. Cancer Res 2007; 67:1395-404. [PMID: 17283177 DOI: 10.1158/0008-5472.can-06-1390] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Base excision repair (BER) corrects DNA damage caused by oxidative stress and low folate intake, which are putative risk factors for colorectal neoplasia. To examine the relationship between genetic variation in BER genes and colorectal adenoma risk, we conducted a case-control study of 767 cases of advanced colorectal adenoma and 773 controls from the baseline screening exam of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Cases included participants diagnosed with advanced left-sided adenoma, and controls were subjects without evidence of a left-sided polyp by sigmoidoscopy, frequency-matched to cases on race and gender. Twenty single nucleotide polymorphisms were genotyped in four BER genes (APEX1, PARP1, POLB, and XRCC1), and conditional logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI) for the association with colorectal adenoma. Two variants with possible functional significance were associated with risk. The APEX1 51H variant was associated with a borderline significant decreased risk of colorectal adenoma (OR, 0.66; 95% CI, 0.44-1.00), and the XRCC1 399Q variant was inversely associated with risk among Caucasians (OR, 0.80; 95% CI, 0.64-0.99). Homozygotes at two PARP1 loci (A284A and IVS13+118G>A) were also associated with a decreased risk of colorectal adenoma compared with wild-type carriers (OR, 0.70; 95% CI, 0.49-0.98 for both), which was restricted to advanced adenomas displaying histologically aggressive characteristics (OR, 0.51; 95% CI, 0.33-0.78, P = 0.002 for PARP1 A284A). This study suggests that polymorphisms in APEX1, XRCC1, and PARP1 may be associated with advanced colorectal adenoma.
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Affiliation(s)
- Sonja I Berndt
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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217
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Raffoul JJ, Banerjee S, Singh-Gupta V, Knoll ZE, Fite A, Zhang H, Abrams J, Sarkar FH, Hillman GG. Down-regulation of apurinic/apyrimidinic endonuclease 1/redox factor-1 expression by soy isoflavones enhances prostate cancer radiotherapy in vitro and in vivo. Cancer Res 2007; 67:2141-9. [PMID: 17332344 DOI: 10.1158/0008-5472.can-06-2147] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We previously showed that genistein, the major bioactive component of soy isoflavones, acts as a radiosensitizer and potentiates prostate tumor cell killing by radiation in vitro and in animal tumor models in vivo. However, when given alone in vivo, pure genistein promoted increased lymph node metastasis, which was not observed with a soy isoflavone mixture consisting of genistein, daidzein, and glycitein. In this study, we show that soy inhibit tumor cell growth and potentiates radiation-induced cell killing in vitro like pure genistein. In an orthotopic model, combining soy isoflavones with tumor irradiation inhibited prostate tumor growth. To determine the molecular mechanisms by which soy isoflavones potentiate radiotherapy, we investigated apurinic/apyrimidinic endonuclease 1/redox factor-1 (APE1/Ref-1) and nuclear factor kappaB (NF-kappaB), two signaling molecules involved in survival pathways. Soy isoflavones decreased APE1/Ref-1 expression in vitro, whereas radiation up-regulated it. Pretreatment with soy isoflavones followed by radiation inhibited APE1/Ref-1 expression. APE1/Ref-1 decrease correlated with decreased DNA-binding activity of NF-kappaB mediated by soy isoflavones and radiation, thus promoting cell killing. In vivo treatment of prostate tumors with soy isoflavones and radiation down-regulated APE1/Ref-1 protein expression and NF-kappaB activity, confirming the molecular alterations observed in vitro. The down-regulation of APE1/Ref-1 and NF-kappaB by isoflavones, in vitro and in vivo, supports our hypothesis that these markers represent biological targets of isoflavones. Indeed, a 2-fold increase in APE1/Ref-1 expression, obtained by cDNA transfection, resulted in a 2-fold increase in NF-kappaB DNA-binding activity, and both of which were down-regulated by soy isoflavones, confirming the cross-talk between these molecules and, in turn, causing radiosensitization.
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Affiliation(s)
- Julian J Raffoul
- Department of Radiation Oncology, Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI 48201, USA
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218
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Arnoys EJ, Wang JL. Dual localization: proteins in extracellular and intracellular compartments. Acta Histochem 2007; 109:89-110. [PMID: 17257660 DOI: 10.1016/j.acthis.2006.10.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2006] [Revised: 10/01/2006] [Accepted: 10/09/2006] [Indexed: 12/24/2022]
Abstract
The goal of this article is to provide a comprehensive catalog of those proteins documented to exhibit dual localization, being found in both the extracellular compartment (cell surface and extracellular medium) as well as the intracellular compartment (cytosol and nucleus). A large subset of these proteins that show dual localization is found both in the nucleus and outside of cells. Proteins destined to be secreted out of the cell or to be expressed at the cell surface usually enter the endomembrane pathway on the basis of a signal sequence that targets them into the endoplasmic reticulum. Proteins destined for import into the nucleus, on the other hand, usually carry a nuclear localization signal. We have organized our catalog in terms of the presence and absence of these trafficking signals: (a) proteins that contain a signal sequence but no nuclear localization signal; (b) proteins that contain both a signal sequence as well as a nuclear localization signal; (c) proteins that contain a nuclear localization signal but lack a signal sequence; and (d) proteins containing neither a signal sequence nor a nuclear localization signal. Novel insights regarding the activities of several classes of proteins exhibiting dual localization can be derived when one targeting signal is experimentally abrogated. For example, the mitogenic activity of both fibroblasts growth factor-1 and schwannoma-derived growth factor clearly requires nuclear localization, independent of the activation of the receptor tyrosine kinase signaling pathway. In addition, there is a growing list of integral membrane receptors that undergo translocation to the nucleus, with bona fide nuclear localization signals and transcription activation activity. The information provided in this descriptive catalog will, hopefully, stimulate investigations into the pathways and mechanisms of transport between these compartments and the physiological significance of dual localization.
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Affiliation(s)
- Eric J Arnoys
- Department of Chemistry and Biochemistry, Calvin College, Grand Rapids, MI 49546, USA
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219
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O'Hara AM, Bhattacharyya A, Mifflin RC, Smith MF, Ryan KA, Scott KGE, Naganuma M, Casola A, Izumi T, Mitra S, Ernst PB, Crowe SE. Interleukin-8 induction by Helicobacter pylori in gastric epithelial cells is dependent on apurinic/apyrimidinic endonuclease-1/redox factor-1. THE JOURNAL OF IMMUNOLOGY 2007; 177:7990-9. [PMID: 17114472 DOI: 10.4049/jimmunol.177.11.7990] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Helicobacter pylori infection causes inflammation and increases the expression of IL-8 in human gastric epithelial cells. H. pylori activates NF-kappaB and AP-1, essential transcriptional factors in H. pylori-induced IL-8 gene transcription. Although colonization creates a local oxidative stress, the molecular basis for the transition from infection to the expression of redox-sensitive cytokine genes is unknown. We recently reported that the expression of apurinic/apyrimidinic endonuclease-1/redox factor-1 (APE-1/Ref-1), which repairs oxidative DNA damage and reductively activates transcription factors including AP-1 and NF-kappaB, is increased in human gastric epithelia during H. pylori infection. In this study, we examine whether APE-1/Ref-1 functions in the modulation of IL-8 gene expression in H. pylori-infected human gastric epithelial cells. Small interfering RNA-mediated silencing of APE-1/Ref-1 inhibited basal and H. pylori-induced AP-1 and NF-kappaB DNA-binding activity without affecting the nuclear translocation of these transcription factors and also reduced H. pylori-induced IL-8 mRNA and protein. In contrast, overexpression of APE-1/Ref-1 enhanced basal and H. pylori-induced IL-8 gene transcription, and the relative involvement of AP-1 in inducible IL-8 promoter activity was greater in APE-1/Ref-1 overexpressing cells than in cells with basal levels of APE-1/Ref-1. APE-1/Ref-1 inhibition also reduced other H. pylori-induced chemokine expression. By implicating APE-1/Ref-1 as an important regulator of gastric epithelial responses to H. pylori infection, these data elucidate a novel mechanism controlling transcription and gene expression in bacterial pathogenesis.
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Affiliation(s)
- Ann M O'Hara
- Department of Internal Medicine, University of Virginia, Charlottesville, VA 22908, USA
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220
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Liu H, Zhang H, Iles KE, Rinna A, Merrill G, Yodoi J, Torres M, Forman HJ. The ADP-stimulated NADPH oxidase activates the ASK-1/MKK4/JNK pathway in alveolar macrophages. Free Radic Res 2007; 40:865-74. [PMID: 17015265 PMCID: PMC2713795 DOI: 10.1080/10715760600758514] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The role of H2O2 as a second messenger in signal transduction pathways is well established. We show here that the NADPH oxidase-dependent production of O2*(-) and H2O2 or respiratory burst in alveolar macrophages (AM) (NR8383 cells) is required for ADP-stimulated c-Jun phosphorylation and the activation of JNK1/2, MKK4 (but not MKK7) and apoptosis signal-regulating kinase-1 (ASK1). ASK1 binds only to the reduced form of thioredoxin (Trx). ADP induced the dissociation of ASK1/Trx complex and thus resulted in ASK1 activation, as assessed by phosphorylation at Thr845, which was enhanced after treatment with aurothioglucose (ATG), an inhibitor of Trx reductase. While dissociation of the complex implies Trx oxidation, protein electrophoretic mobility shift assay detected oxidation of Trx only after bolus H2O2 but not after ADP stimulation. These results demonstrate that the ADP-stimulated respiratory burst activated the ASK1-MKK4-JNK1/c-Jun signaling pathway in AM and suggest that transient and localized oxidation of Trx by the NADPH oxidase-mediated generation of H2O2 may play a critical role in ASK1 activation and the inflammatory response.
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Affiliation(s)
- Honglei Liu
- School of Natural Sciences, University of California Merced, Merced, CA 95340, USA
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221
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Dai J, Li W, Chang L, Zhang Z, Tang C, Wang N, Zhu Y, Wang X. Role of redox factor-1 in hyperhomocysteinemia-accelerated atherosclerosis. Free Radic Biol Med 2006; 41:1566-77. [PMID: 17045925 DOI: 10.1016/j.freeradbiomed.2006.08.020] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2006] [Revised: 08/21/2006] [Accepted: 08/23/2006] [Indexed: 02/03/2023]
Abstract
Hyperhomocysteinemia (HHcy) is an independent risk factor for atherosclerosis. We have previously shown that homocysteine can induce monocyte chemoattractant protein-1 (MCP-1) secretion via reactive oxygen species (ROS) in human monocytes in vitro. In the present study, we investigated whether redox factor-1 (Ref-1) is involved in HHcy-accelerated atherosclerosis. We used a mild HHcy animal model, aortic roots and peritoneal macrophages were isolated for immunohistochemistry and Western blotting, from apoE-/- and C57BL/6J mice fed a high Hcy diet (1.8 g/L) for 4 or 12 weeks. Four-week HHcy apoE-/- mice showed more plaques and significantly increased immunostaining of Ref-1 and MCP-1 in foam cells, and HHcy mice showed enhanced Ref-1 expression in peritoneal macrophages. To explore the mediating mechanism, incubation with Hcy (100 microM) increased Ref-1 protein level and translocation in human monocytes in vitro. In addition, Hcy-induced NADPH oxidase activity mediated the upregulation of Ref-1. Furthermore, overexpressed Ref-1 upregulated NF-kappaB and MCP-1 promoter activity, and antisense Ref-1 reduced Hcy-induced NF-kappaB DNA-binding activity and MCP-1 secretion. These data indicate that Hcy-induced ROS upregulate the expression and translocation of Ref-1 via NADPH oxidase, and then Ref-1 increases NF-kappaB activity and MCP-1 secretion in human monocytes/macrophages, which may accelerate the development of atherosclerosis.
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Affiliation(s)
- Jing Dai
- Department of Physiology and Pathophysiology, School of Basic Medical Science, Peking University, Beijing 100083, People's Republic of China
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222
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Martelli A, Rousselet E, Dycke C, Bouron A, Moulis JM. Cadmium toxicity in animal cells by interference with essential metals. Biochimie 2006; 88:1807-14. [PMID: 16814917 DOI: 10.1016/j.biochi.2006.05.013] [Citation(s) in RCA: 219] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2006] [Accepted: 05/12/2006] [Indexed: 12/15/2022]
Abstract
Cadmium is found in the environment as part of several, mainly zinc-rich, ores. It has been used in many technological applications, but biological systems generally failed to safely deal with this element. In mammalian biology, cadmium exposure jeopardizes health and mechanisms of cadmium toxicity are multifarious. Mainly because bioavailable cadmium mimics other metals that are essential to diverse biological functions, cadmium follows a Trojan horse strategy to get assimilated. Metals susceptible to cadmium deceit include calcium, zinc, and iron. The wealth of data addressing cadmium toxicity in animal cells is briefly reviewed with special emphasis on disturbance of the homeostasis of calcium, zinc, and iron. A limited number of tissues and cell types are considered as main targets for cadmium toxicity. Still, the diversity of pathways affected by cadmium exposure points to a more general threat to basic cellular functions. The poor efficiency of cellular export systems for cadmium explains the long residence time of the element in mammals. Therefore, proper disposal and educated uses of this technologically appealing, but biologically malicious, element should be favored in the future. The comprehensive knowledge of cadmium biological effects is indeed a necessary step to protect human and animal populations from environmental and anthropological exposures.
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Affiliation(s)
- A Martelli
- Laboratoire de Biophysique Moléculaire et Cellulaire, CNRS UMR 5090, Université Joseph-Fourier, Département Réponse et Dynamique Cellulaires, CEA-Grenoble, 17, avenue des Martyrs, 38054 Grenoble cedex 09, France
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223
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Bravard A, Vacher M, Gouget B, Coutant A, de Boisferon FH, Marsin S, Chevillard S, Radicella JP. Redox regulation of human OGG1 activity in response to cellular oxidative stress. Mol Cell Biol 2006; 26:7430-6. [PMID: 16923968 PMCID: PMC1636869 DOI: 10.1128/mcb.00624-06] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2006] [Revised: 06/05/2006] [Accepted: 07/31/2006] [Indexed: 11/20/2022] Open
Abstract
8-Oxoguanine (8-oxoG), a common and mutagenic form of oxidized guanine in DNA, is eliminated mainly through base excision repair. In human cells its repair is initiated by human OGG1 (hOGG1), an 8-oxoG DNA glycosylase. We investigated the effects of an acute cadmium exposure of human lymphoblastoid cells on the activity of hOGG1. We show that coinciding with alteration of the redox cellular status, the 8-oxoG DNA glycosylase activity of hOGG1 was nearly completely inhibited. However, the hOGG1 activity returned to normal levels once the redox cellular status was normalized. In vitro, the activity of purified hOGG1 was abolished by cadmium and could not be recovered by EDTA. In cells, however, the reversible inactivation of OGG1 activity by cadmium was strictly associated with reversible oxidation of the protein. Moreover, the 8-oxoG DNA glycosylase activity of purified OGG1 and that from crude extracts were modulated by cysteine-modifying agents. Oxidation of OGG1 by the thiol oxidant diamide led to inhibition of the activity and a protein migration pattern similar to that seen in cadmium-treated cells. These results suggest that cadmium inhibits hOGG1 activity mainly by indirect oxidation of critical cysteine residues and that excretion of the metal from the cells leads to normalization of the redox cell status and restoration of an active hOGG1. The results presented here unveil a novel redox-dependent mechanism for the regulation of OGG1 activity.
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Affiliation(s)
- Anne Bravard
- Département de Radiobiologie et Radiopathologie, CEA, 18 route du Panorama, F-92265 Fontenay aux Roses, France.
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224
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Grillo C, D'Ambrosio C, Scaloni A, Maceroni M, Merluzzi S, Turano C, Altieri F. Cooperative activity of Ref-1/APE and ERp57 in reductive activation of transcription factors. Free Radic Biol Med 2006; 41:1113-23. [PMID: 16962936 DOI: 10.1016/j.freeradbiomed.2006.06.016] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2006] [Revised: 06/01/2006] [Accepted: 06/24/2006] [Indexed: 11/27/2022]
Abstract
ERp57, a protein disulfide isomerase localized mainly in the endoplasmic reticulum, has also been found in lesser amounts in the cytosol and nucleus, where its function is still not characterized. We report here that ERp57 displays affinity for Ref-1, a protein involved in DNA repair as well as in the reduction and activation of transcription factors. Immunoprecipitation experiments showed that Ref-1 and ERp57 also interact in vivo in at least three types of cultured human cells, namely HepG2, M14, and Raji. Oxidative stress increased the amount of nuclear Ref-1 associated with ERp57. Moreover, ERp57 reduced by the thioredoxin-reductase/thioredoxin system stimulated the binding of AP-1 to its consensus sequence on DNA, and HeLa cells stably transfected and overexpressing ERp57 were protected against hydrogen peroxide-induced cell killing. Accordingly, ERp57 appears to cooperate with Ref-1 in the regulation of gene expression mediated by redox-sensitive transcription factors and in the adaptive response of the cell to oxidative insult.
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Affiliation(s)
- Caterina Grillo
- Department of Biochemical Sciences A. Rossi Fanelli, University La Sapienza, P.le A. Moro 5, 00185 Rome, Italy
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225
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Daviet S, Couvé-Privat S, Gros L, Shinozuka K, Ide H, Saparbaev M, Ishchenko AA. Major oxidative products of cytosine are substrates for the nucleotide incision repair pathway. DNA Repair (Amst) 2006; 6:8-18. [PMID: 16978929 DOI: 10.1016/j.dnarep.2006.08.001] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2006] [Revised: 08/01/2006] [Accepted: 08/02/2006] [Indexed: 11/21/2022]
Abstract
Most common point mutations occurring spontaneously or induced by ionizing radiation are C-->T transitions implicating cytosine as the target. Oxidative cytosine derivatives are the most abundant and mutagenic DNA damage induced by oxidative stress. Base excision repair (BER) pathway initiated by DNA glycosylases is thought to be the major pathway for the removal of these lesions. However, in alternative nucleotide incision repair (NIR) pathway the apurinic/apyrimidinic (AP) endonucleases incise DNA duplex 5' to an oxidatively damaged base in a DNA glycosylase-independent manner. Here, we characterized the substrate specificity of human major AP endonuclease, Ape1, towards 5-hydroxy-2'-deoxycytidine (5ohC) and alpha-anomeric 2'-deoxycytidine (alphadC) residues. The apparent kinetic parameters of the reactions suggest that Ape1 and the DNA glycosylases/AP lyases, hNth1 and hNeil1 repair 5ohC with a low efficiency. Nevertheless, due to the extremely high cellular concentration of Ape1, NIR was the major activity towards 5ohC in cell-free extracts. To address the physiological role of NIR function, we have characterized naturally occurring Ape1 variants including amino acids substitutions (E126A, E126D and D148E) and N-terminal truncated forms (NDelta31, NDelta35 and NDelta61). As expected, all Ape1 mutants had proficient AP endonuclease activity, however, truncated forms showed reduced NIR and 3'-->5' exonuclease activities indicating that these two functions are genetically linked and governed by the same amino acid residues. Furthermore, both Ape1-catalyzed NIR and 3'-->5' exonuclease activities generate a single-strand gap at the 5' side of a damaged base but not at an AP site in duplex DNA. We hypothesized that biochemical coupling of the nucleotide incision and exonuclease degradation may serve to remove clustered DNA damage. Our data suggest that NIR is a backup system for the BER pathway to remove oxidative damage to cytosines in vivo.
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Affiliation(s)
- Stéphane Daviet
- Groupe Réparation de l'ADN, UMR 8126 CNRS, Univ Paris-Sud, Institut Gustave Roussy, 94805 Villejuif Cedex, France
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226
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Yoshida A, Pommier Y, Ueda T. Endonuclease activation and chromosomal DNA fragmentation during apoptosis in leukemia cells. Int J Hematol 2006; 84:31-7. [PMID: 16867899 DOI: 10.1007/bf03342699] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Apoptotic endonuclease is a key enzyme that mediates regulated DNA fragmentation and chromatin condensation in response to apoptotic signals such as the Fas ligand, ionizing radiation, and anticancer agents. An endonuclease that is activated specifically by caspase-3 has been identified in humans and mice. The human gene for this protein has been termed DFF40 (DNA fragmentation factor, 40-kd subunit) or caspase-activated nuclease (CPAN), whereas the mouse homologue has been named caspase-activated deoxyribonuclease (CAD). Although CAD/DFF40 is known as a major apoptotic nuclease, mice lacking inhibitor of CAD (ICAD) (also known as DFF45) are viable and still show DNA fragmentation, suggesting that alternative endonucleases play an important role during apoptosis. Endonuclease G has been reported to possibly be responsible for DNA fragmentation in various cells during apoptosis. Furthermore, we also have found that apurinic/apyrimidinic endonuclease 1 (Ape1) and its N-terminal-truncated form (AN34) are involved in DNA fragmentation during apoptosis in leukemia cells. In this review, we describe the features of several endonucleases that are involved in the apoptosis of human leukemia cells. Apoptotic endonuclease may vary among different leukemia cell types.
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Affiliation(s)
- Akira Yoshida
- First Department of Internal Medicine, Faculty of Medical Sciences, University of Fukui, Matsuoka, Fukui, Japan.
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227
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Wang Y, Shupenko CC, Melo LF, Strauss PR. DNA repair protein involved in heart and blood development. Mol Cell Biol 2006; 26:9083-93. [PMID: 16966376 PMCID: PMC1636828 DOI: 10.1128/mcb.01216-06] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Apurinic/apyrimidinic endonuclease 1, a key enzyme in repairing abasic sites in DNA, is an embryonic lethal in mice. We are examining its role in embryogenesis in zebra fish. Zebra fish contain two genomic copies (zfAPEX1a and zfAPEX1b) with identical coding sequences. zfAPEX1b lacks introns. Recombinant protein (ZAP1) is highly homologous with and has the same enzymatic properties as its human orthologue. ZAP1 is highly expressed throughout development. Embryos microinjected with morpholino oligonucleotide (MO) targeting the translation start site die at approximately the midblastula transition (MBT) without apoptosis. They are rescued with mRNA for human wild-type APEX1 but not for APEX1 encoding endonuclease-defective protein. Rescued embryos develop dysmorphic hearts, pericardial edema, few erythrocytes, small eyes, and abnormal notochords. Although the hearts in rescued embryos form defective loops ranging from no loop to one that is abnormally shaped, cardiac myosin (cmlc2) is present and contraction occurs. Embryos microinjected with MO targeting zfAPEX1a intron-exon junctions also pass the MBT with similar abnormalities. We conclude that AP endonuclease 1 is involved in both repairing DNA and regulating specific early stages of embryonic development.
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Affiliation(s)
- Yi Wang
- Department of Biology, Northeastern University, 360 Huntington Ave., Boston, MA 02115, USA
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228
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Basi DL, Adhikari N, Mariash A, Li Q, Kao E, Mullegama SV, Hall JL. Femoral artery neointimal hyperplasia is reduced after wire injury in Ref-1+/- mice. Am J Physiol Heart Circ Physiol 2006; 292:H516-21. [PMID: 16936011 DOI: 10.1152/ajpheart.00246.2006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Redox factor-1 (Ref-1) is a multifunctional protein that regulates redox, DNA repair, and the response to cell stress. We previously demonstrated that Ref-1(+/-) mice exhibit a significantly reduced Ref-1 mRNA and protein levels within the vasculature, which are associated with increased oxidative stress. The goal of this study was to test the hypothesis that partial loss of Ref-1 altered the cellular response to vascular injury. Fourteen days after femoral artery wire injury, we found that vessel intima-to-media ratio was significantly reduced in Ref-1(+/-) mice compared with that in wild-type mice (P < 0.01). Bromodeoxyuridine labeling and transferase-mediated dUTP nick-end labeling staining at 14 days did not differ in the Ref-1(+/-) mice. In vitro studies found no significant changes in either serum-induced proliferation or baseline apoptosis in Ref-1(+/-) vascular smooth muscle cells. Exposure to Fas ligand; however, did result in increased susceptibility of Ref-1(+/-) vascular smooth muscle cells to apoptosis (P < 0.001). Ref-1(+/-) mice exhibited an increase in circulating baseline levels of IL-10, IL-1alpha, and VEGF compared with those in wild-type mice but a marked impairment in these pathways in response to injury. In sum, loss of a single allele of Ref-1 is sufficient to reduce intimal lesion formation and to alter circulating cytokine and growth factor expression.
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Affiliation(s)
- David L Basi
- Lillehei Heart Institute, Univ. of Minnesota, 420 Delaware St., Minneapolis, MN 55455, USA.
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229
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Na HK, Surh YJ. Transcriptional regulation via cysteine thiol modification: a novel molecular strategy for chemoprevention and cytoprotection. Mol Carcinog 2006; 45:368-80. [PMID: 16673384 DOI: 10.1002/mc.20225] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Chemoprevention refers to the use of defined nontoxic chemical regimens to inhibit, reverse, or retard the process of multistage carcinogenesis that involves multiple signal transduction events. Identification of signaling molecules associated with carcinogenesis as prime targets of chemopreventive agents has become an area of great interest. Recent studies have implicated cysteine thiols present in various transcription factors, such as NF-kappaB, AP-1, and p53 as redox sensors in transcriptional regulation of many genes essential for maintaining cellular homeostasis. Some chemopreventive and cytoprotective agents have been found to target cysteine thiols present in key transcription factors or their regulators, thereby suppressing aberrant over-activation of carcinogenic signal transduction or restoring/normalizing or even potentiating cellular defense signaling. The focus of this review is the oxidation or covalent modification of thiol groups present in key representative redox-sensitive transcription factors and their regulating molecules as a unique strategy for molecular target-based chemoprevention and cytoprotection.
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Affiliation(s)
- Hye-Kyung Na
- National Research Laboratory of Molecular Carcinogenesis and Chemoprevention, College of Pharmacy, Seoul National University, Seoul, South Korea
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230
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Winyard PG, Moody CJ, Jacob C. Oxidative activation of antioxidant defence. Trends Biochem Sci 2006; 30:453-61. [PMID: 15996871 DOI: 10.1016/j.tibs.2005.06.001] [Citation(s) in RCA: 191] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2005] [Revised: 05/19/2005] [Accepted: 06/21/2005] [Indexed: 02/02/2023]
Abstract
Living cells maintain a delicate balance between oxidizing and reducing species, and many disorders such as rheumatoid arthritis and Alzheimer's disease have been associated with a disturbed intracellular 'redox equilibrium'. The past few years have witnessed accelerated research into how natural redox responses and antioxidant defence systems are activated and how they restore a healthy redox balance. To function properly, many of these processes rely on a powerful sulfur redox chemistry, which is best exemplified by the complex, newly emerging cysteine-based redox regulation of the glutathione and thioredoxin pathways. Other redox systems based on oxidatively activated amino acid side chains in proteins are also becoming increasingly important, but are still barely understood or explored.
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Affiliation(s)
- Paul G Winyard
- Peninsula Medical School, Universities of Exeter and Plymouth, St. Luke's Campus, UK
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231
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Sokolov MV, Smirnova NA, Camerini-Otero RD, Neumann RD, Panyutin IG. Microarray analysis of differentially expressed genes after exposure of normal human fibroblasts to ionizing radiation from an external source and from DNA-incorporated iodine-125 radionuclide. Gene 2006; 382:47-56. [PMID: 16876969 DOI: 10.1016/j.gene.2006.06.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2006] [Revised: 06/15/2006] [Accepted: 06/16/2006] [Indexed: 01/07/2023]
Abstract
Exposure of cells to ionizing radiation (IR) produces changes in the expression level of a large number of genes. However, less is known of gene-expression changes caused by local radiation exposure from radionuclides within cells. We studied changes in the genome-wide gene expression induced by decay of 125I incorporated into DNA as [125I]-iododeoxyuridine (125I-IUdR) in normal IMR-90 human lung fibroblasts and compared them with the changes produced by external gamma-radiation delivered at high (HDR) or low (LDR) dose rate. We found that more than 2000 genes were consistently up- or down-regulated following HDR and LDR gamma-radiation. The profiles of differentially expressed genes following HDR and LDR shared about 64% (up) and 74% (down) genes in common, with many genes identified as radiation-responsive for the first time. In contrast, in all only 206 genes changed their expression level in the 125I-IUdR-treated cells, even though the total number of DNA double-strand breaks (DSB) produced by 125I-IUdR exceeded that produced by the gamma-radiation. With few exceptions, the expression levels of 125I-IUdR-responsive genes were also altered following gamma-irradiation. Therefore, nuclear DNA-localized decays of 125I produce 10 times fewer differentially expressed genes than whole-cell exposure to gamma-radiation of comparable dose. These results suggest that the effect of IR on the changes in global gene expression depends on the distribution of energy depositions within the cell. In contrast to cell survival, DNA DSB may not be the major factor modulating changes in gene expression following irradiation.
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Affiliation(s)
- M V Sokolov
- Department of Nuclear Medicine, Clinical Center, NIH, Bldg. 10 Room 4D45, 9000 Rockville Pike, Bethesda, MD 20892, United States
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232
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Amoutzias GD, Bornberg-Bauer E, Oliver SG, Robertson DL. Reduction/oxidation-phosphorylation control of DNA binding in the bZIP dimerization network. BMC Genomics 2006; 7:107. [PMID: 16674813 PMCID: PMC1479340 DOI: 10.1186/1471-2164-7-107] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2006] [Accepted: 05/04/2006] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND bZIPs are transcription factors that are found throughout the eukarya from fungi to flowering plants and mammals. They contain highly conserved basic region (BR) and leucine zipper (LZ) domains and often function as environmental sensors. Specifically, bZIPs frequently have a role in mediating the response to oxidative stress, a crucial environmental signal that needs to be transduced to the gene regulatory network. RESULTS Based on sequence comparisons and experimental data on a number of important bZIP transcription factors, we predict which bZIPs are under redox control and which are regulated via protein phosphorylation. By integrating genomic, phylogenetic and functional data from the literature, we then propose a link between oxidative stress and the choice of interaction partners for the bZIP proteins. CONCLUSION This integration permits the bZIP dimerization network to be interpreted in functional terms, especially in the context of the role of bZIP proteins in the response to environmental stress. This analysis demonstrates the importance of abiotic factors in shaping regulatory networks.
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Affiliation(s)
- Gregory D Amoutzias
- Centre for the Analysis of Biological Complexity, Faculty of Life Sciences, The University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
- Department of Ecology and Evolution, University of Lausanne, Lausanne, 1015, Switzerland
| | - Erich Bornberg-Bauer
- Centre for the Analysis of Biological Complexity, Faculty of Life Sciences, The University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
- Bioinformatics Division, Institute of Botany, School of Biological Sciences, University of Münster, Schlossplatz 4, D4814P, Germany
| | - Stephen G Oliver
- Centre for the Analysis of Biological Complexity, Faculty of Life Sciences, The University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
| | - David L Robertson
- Centre for the Analysis of Biological Complexity, Faculty of Life Sciences, The University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
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233
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Ishchenko AA, Deprez E, Maksimenko A, Brochon JC, Tauc P, Saparbaev MK. Uncoupling of the base excision and nucleotide incision repair pathways reveals their respective biological roles. Proc Natl Acad Sci U S A 2006; 103:2564-9. [PMID: 16473948 PMCID: PMC1413785 DOI: 10.1073/pnas.0508582103] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The multifunctional DNA repair enzymes apurinic/apyrimidinic (AP) endonucleases cleave DNA at AP sites and 3'-blocking moieties generated by DNA glycosylases in the base excision repair pathway. Alternatively, in the nucleotide incision repair (NIR) pathway, the same AP endonucleases incise DNA 5' of a number of oxidatively damaged bases. At present, the physiological relevance of latter function remains unclear. Here, we report genetic dissection of AP endonuclease functions in base excision repair and NIR pathways. Three mutants of Escherichia coli endonuclease IV (Nfo), carrying amino acid substitutions H69A, H109A, and G149D have been isolated. All mutants were proficient in the AP endonuclease and 3'-repair diesterase activities but deficient in the NIR. Analysis of metal content reveals that all three mutant proteins have lost one of their intrinsic zinc atoms. Expression of the nfo mutants in a repair-deficient strain of E. coli complemented its hypersensitivity to alkylation but not to oxidative DNA damage. The differential drug sensitivity of the mutants suggests that the NIR pathway removes lethal DNA lesions generated by oxidizing agents. To address the physiological relevance of the NIR pathway in human cells, we used the fluorescence quenching mechanism of molecular beacons. We show that in living cells a major human AP endonuclease, Ape1, incises DNA containing alpha-anomeric 2'-deoxyadenosine, indicating that the intracellular environment supports NIR activity. Our data establish that NIR is a distinct and separable function of AP endonucleases essential for handling lethal oxidative DNA lesions.
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Affiliation(s)
- Alexander A. Ishchenko
- Groupe Réparation de l’ADN, Unité Mixte de Recherche 8126, Centre National de la Recherche Scientifique, Institut Gustave Roussy, 94805 Villejuif Cedex, France
| | - Eric Deprez
- Laboratoire de Biotechnologie et Pharmacologie Génétique Appliquée, Unité Mixte de Recherche 8113, Centre National de la Recherche Scientifique, Ecole Normale Supérieure de Cachan, 94235 Cachan Cedex, France; and
| | - Andrei Maksimenko
- Laboratoire de Biotechnologie et Pharmacologie Génétique Appliquée, Unité Mixte de Recherche 8113, Centre National de la Recherche Scientifique, Ecole Normale Supérieure de Cachan, 94235 Cachan Cedex, France; and
- BioAlliance Pharma, 59, Boulevard du Général Martial Valin, 75015 Paris, France
| | - Jean-Claude Brochon
- Laboratoire de Biotechnologie et Pharmacologie Génétique Appliquée, Unité Mixte de Recherche 8113, Centre National de la Recherche Scientifique, Ecole Normale Supérieure de Cachan, 94235 Cachan Cedex, France; and
| | - Patrick Tauc
- Laboratoire de Biotechnologie et Pharmacologie Génétique Appliquée, Unité Mixte de Recherche 8113, Centre National de la Recherche Scientifique, Ecole Normale Supérieure de Cachan, 94235 Cachan Cedex, France; and
| | - Murat K. Saparbaev
- Groupe Réparation de l’ADN, Unité Mixte de Recherche 8126, Centre National de la Recherche Scientifique, Institut Gustave Roussy, 94805 Villejuif Cedex, France
- To whom correspondence should be addressed. E-mail:
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234
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Szczesny B, Mitra S. Effect of aging on intracellular distribution of abasic (AP) endonuclease 1 in the mouse liver. Mech Ageing Dev 2006; 126:1071-8. [PMID: 15951004 DOI: 10.1016/j.mad.2005.04.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2004] [Revised: 03/01/2005] [Accepted: 04/11/2005] [Indexed: 11/26/2022]
Abstract
The abasic (AP) endonuclease (APE1) plays a central role in the base excision repair (BER) pathway for repairing oxidatively damaged bases and abasic sites in mammalian genomes. We have investigated age-dependent changes in APE activity, contributed primarily by APE1, in total extracts as well as in nuclear, mitochondrial, and cytoplasmic compartments of mouse hepatocytes. The APE1 protein and mRNA levels did not differ significantly between the livers of 4-mo (young), 10-mo (middle-aged), and 20-mo (old) mice, and corresponds with similar APE activity. However, we observed a 2-fold increase in specific activity of APE1 in the nucleus, a 2-fold decrease in the cytoplasm, and a 6-fold increase in the mitochondrial matrix of hepatocytes of the old relative to the young animals. Surprisingly, in the middle-age animals we observed 30% increase in APE activity in the nucleus but 6-fold in the mitochondrial matrix. These results indicate age-dependent accumulation of APE1 in the nucleus and mitochondria. Such redistribution occurred early in the mitochondria during the aging process and preferential accumulation of APE in the nucleus was more gradual which may reflect distinct levels of oxidative stress in these organelles.
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Affiliation(s)
- Bartosz Szczesny
- University of Texas Medical Branch, Sealy Center for Molecular Science, Department of Human Biological Chemistry and Genetics, Galveston, TX 77555, USA
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235
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Meira LB, Burgis NE, Samson LD. Base excision repair. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2006; 570:125-73. [PMID: 18727500 DOI: 10.1007/1-4020-3764-3_5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Lisiane B Meira
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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236
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237
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Abstract
Reactive oxygen species contribute to the pathogenesis of a number of disparate disorders including tissue inflammation, heart failure, hypertension, and atherosclerosis. In response to oxidative stress, cells activate expression of a number of genes, including those required for the detoxification of reactive molecules as well as for the repair and maintenance of cellular homeostasis. In many cases, these induced genes are regulated by transcription factors whose structure, subcellular localization, or affinity for DNA is directly or indirectly regulated by the level of oxidative stress. This review summarizes the recent progress on how cellular redox status can regulate transcription-factor activity and the implications of this regulation for cardiovascular disease.
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Affiliation(s)
- Hongjun Liu
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
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238
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Wang P, Day L, Dheekollu J, Lieberman PM. A redox-sensitive cysteine in Zta is required for Epstein-Barr virus lytic cycle DNA replication. J Virol 2005; 79:13298-309. [PMID: 16227252 PMCID: PMC1262569 DOI: 10.1128/jvi.79.21.13298-13309.2005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Epstein-Barr virus (EBV) reactivation from latency is known to be sensitive to redox regulation. The immediate-early protein Zta is a member of the basic-leucine zipper (bZIP) family of DNA binding proteins that stimulates viral and cellular transcription and nucleates a replication complex at the viral lytic origin. Zta shares with several members of the bZIP family a conserved cysteine residue (C189) that confers redox regulation of DNA binding. In this work, we show that replacement of C189 with serine (C189S) eliminated lytic cycle DNA replication function of Zta. The mechanistic basis for this replication defect was investigated. We show that C189S was not significantly altered for DNA binding activity in vitro or in vivo. We also show that C189S was not defective for transcription activation of EBV early gene promoters. C189S was deficient for transcription activation of several viral late genes that depend on lytic replication and therefore was consistent with a primary defect of C189S in activating lytic replication. C189S was not defective in binding methylated DNA binding sites and was capable of activating Rta from endogenous latent viral genomes, in contrast to the previously characterized S186A mutation. C189S was slightly impaired for its ability to form a stable complex with Rta, although this did not prevent Rta recruitment to OriLyt. C189S did provide some resistance to oxidation and nitrosylation, which potently inhibit Zta DNA binding activity in vitro. Interestingly, this redox sensitivity was not strictly dependent on C189S but involved additional cysteine residues in Zta. These results provide evidence that the conserved cysteine in the bZIP domain of Zta plays a primary role in EBV lytic cycle DNA replication.
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Affiliation(s)
- Pu Wang
- The Wistar Institute, Philadelphia, PA 19104, USA
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239
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Demple B, Sung JS. Molecular and biological roles of Ape1 protein in mammalian base excision repair. DNA Repair (Amst) 2005; 4:1442-9. [PMID: 16199212 DOI: 10.1016/j.dnarep.2005.09.004] [Citation(s) in RCA: 153] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Many oxidative DNA lesions are handled well by base excision repair (BER), but some types may be problematic. Recent work indicates that 2-deoxyribonolactone (dL) is such a lesion by forming stable, covalent cross-links between the abasic residue and DNA repair proteins with lyase activity. In the case of DNA polymerase beta, the reaction is potentiated by incision of dL by Ape1, the major mammalian AP endonuclease. When repair is prevented, polymerase beta is the most reactive cross-linking protein in whole-cell extracts. Cross-linking with dL is largely avoided by processing the damage through the "long-patch" (multinucleotide) BER pathway. However, if excess damage leads to the accumulation of unrepaired oxidative lesions in DNA, there may be a danger of polymerase beta-mediated cross-link formation. Understanding how cells respond to such complex damage is an important issue. In addition to its role in defending against DNA damage caused by exogenous agents, Ape1 protein is essential for coping with the endogenous DNA damage in human cells grown in culture. Suppression of Ape1 using RNA-interference technology causes arrest of cell proliferation and activation of apoptosis in various cell types, correlated with the accumulation of unrepaired abasic DNA damage. Notably, all these effects are reversed by expression of the unrelated protein Apn1 of S. cerevisiae, which shares only the enzymatic repair function with Ape1 (AP endonuclease).
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Affiliation(s)
- Bruce Demple
- Department of Genetics and Complex Diseases, Harvard School of Public Health, Boston, MA 02115, USA.
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240
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Madhusudan S, Smart F, Shrimpton P, Parsons JL, Gardiner L, Houlbrook S, Talbot DC, Hammonds T, Freemont PA, Sternberg MJE, Dianov GL, Hickson ID. Isolation of a small molecule inhibitor of DNA base excision repair. Nucleic Acids Res 2005; 33:4711-24. [PMID: 16113242 PMCID: PMC1188083 DOI: 10.1093/nar/gki781] [Citation(s) in RCA: 166] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
The base excision repair (BER) pathway is essential for the removal of DNA bases damaged by alkylation or oxidation. A key step in BER is the processing of an apurinic/apyrimidinic (AP) site intermediate by an AP endonuclease. The major AP endonuclease in human cells (APE1, also termed HAP1 and Ref-1) accounts for >95% of the total AP endonuclease activity, and is essential for the protection of cells against the toxic effects of several classes of DNA damaging agents. Moreover, APE1 overexpression has been linked to radio- and chemo-resistance in human tumors. Using a newly developed high-throughput screen, several chemical inhibitors of APE1 have been isolated. Amongst these, CRT0044876 was identified as a potent and selective APE1 inhibitor. CRT0044876 inhibits the AP endonuclease, 3′-phosphodiesterase and 3′-phosphatase activities of APE1 at low micromolar concentrations, and is a specific inhibitor of the exonuclease III family of enzymes to which APE1 belongs. At non-cytotoxic concentrations, CRT0044876 potentiates the cytotoxicity of several DNA base-targeting compounds. This enhancement of cytotoxicity is associated with an accumulation of unrepaired AP sites. In silico modeling studies suggest that CRT0044876 binds to the active site of APE1. These studies provide both a novel reagent for probing APE1 function in human cells, and a rational basis for the development of APE1-targeting drugs for antitumor therapy.
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Affiliation(s)
| | - Fiona Smart
- Cancer Research Technology Ltd, Wolfson Institute for Biomedical ResearchThe Cruciform Building, Gower Street, London, WC1E 6BT, UK
| | - Paul Shrimpton
- Structural Bioinformatics Group, Centre for Bioinformatics, Imperial College LondonLondon, SW7 2AZ, UK
| | - Jason L. Parsons
- MRC Radiation and Genome Stability UnitHarwell, Oxfordshire, OX11 0RD, UK
| | | | | | | | - Timothy Hammonds
- Cancer Research Technology Ltd, Wolfson Institute for Biomedical ResearchThe Cruciform Building, Gower Street, London, WC1E 6BT, UK
| | - Paul A. Freemont
- Centre for Structural Biology, Imperial College LondonLondon SW7 2AZ, UK
| | - Michael J. E. Sternberg
- Structural Bioinformatics Group, Centre for Bioinformatics, Imperial College LondonLondon, SW7 2AZ, UK
| | - Grigory L. Dianov
- MRC Radiation and Genome Stability UnitHarwell, Oxfordshire, OX11 0RD, UK
| | - Ian D. Hickson
- To whom correspondence should be addressed. Tel: +44 0 1865 222 417; Fax: +44 0 1865 222 431;
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241
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Affiliation(s)
- J Christopher Fromme
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
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242
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Li Y, Liu W, Xing G, Tian C, Zhu Y, He F. Direct association of hepatopoietin with thioredoxin constitutes a redox signal transduction in activation of AP-1/NF-κB. Cell Signal 2005; 17:985-96. [PMID: 15894171 DOI: 10.1016/j.cellsig.2004.11.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2004] [Revised: 11/18/2004] [Accepted: 11/19/2004] [Indexed: 11/16/2022]
Abstract
It has been demonstrated that growth factors quiescin Q6 family was created by the fusion of the sulfhydryl oxidase fragment of the yeast essential for respiration and vegetative growth (ERV)1 prototype [an orthologue of hepatopoietin (HPO)] and thioredoxin (TRX)/disulfide isomerase domain during evolution. In this paper, our results demonstrated that two components of this composite protein, i.e., HPO and TRX, were involved in the same signal transduction and interacted physically in eukaryocyte. When HPO and TRX were cotransfected into COS7 cells, the activity of activator protein-1 (AP-1) and NF-kappaB was evidently enhanced compared with the transfection with HPO or TRX alone, at the same time, the phosphorylation of c-Jun was increased. They were colocalized in the cells. By Co-IP and GST pull-down experiments, we found that HPO could physically interact with TRX, which was also confirmed by yeast two-hybrid assay. By further investigation, we found both HPO and TRX were sensitive to cellular oxidative state. HPO dimer is in its natural state and could be reduced by dithiothreitol (DTT) in vitro and in vivo. Under the treatment of oxidants such as H(2)O(2) and diamide, the amount of HPO monomer was decreased significantly and assembled into dimer, and the free thiol in TRX was oxidized. HPO could transfer oxidizing equivalents to TRX via direct thiol-disulfide exchange in vitro, the redox state of TRX was also affected by HPO in vivo. Taken together, it was implicated that the oxidizing equivalents might flow from HPO to TRX and then to substrate protein by the dimerization of HPO, and its interaction with TRX finally activates the redox-sensitive transcription factor, suggesting a new redox signal pathway conducted by thiol-disulfide transformation in eukaryocytic cytoplasm.
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Affiliation(s)
- Yingxian Li
- Laboratory of Systems Biology, Beijing Institute of Radiation Medicine, Chinese Human Genome Center at Beijing
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243
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Seemann S, Hainaut P. Roles of thioredoxin reductase 1 and APE/Ref-1 in the control of basal p53 stability and activity. Oncogene 2005; 24:3853-63. [PMID: 15824742 DOI: 10.1038/sj.onc.1208549] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The p53 protein is redox-sensitive in vitro but in vivo effectors of this sensitivity are not known. In yeasts deficient for thioredoxin (Trx) reductase (TRR), p53 accumulates in an inactive, oxidized form, suggesting a role for TRR-Trx in controlling p53. In mammalian cells, p53 binds to redox factor-1 (APE/Ref-1), an enzyme containing an abasic endonuclease domain involved in base excision repair, and a thiol reductase domain recycled by Trx and involved in regulating the transcription factor AP-1. To evaluate the role of TRR and APE/Ref-1 in p53 regulation, we have abrogated their expression using RNA interference in cell lines expressing wild-type p53. Inhibition of TRR resulted in accumulation of oxidized Trx and increased levels and DNA-binding activity of p53, with no phosphorylation of Ser15 or Ser20. In contrast, inhibition of APE/Ref-1 accelerated p53 protein turnover, resulting in a decrease in p53 levels and activity. However, inhibition of either TRR or APE/Ref-1 did not prevent activation and accumulation of p53 in response to DNA-damage by doxorubicin. When both factors were inhibited, basal levels of p53 were restored. These results suggest that TRR-Trx and APE/Ref-1 cooperate in the control of basal p53 activity, but not in its induction by DNA-damage.
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Affiliation(s)
- Séverine Seemann
- Group of Molecular Carcinogenesis, International Agency for Research on Cancer, 150 Cours Albert Thomas, 69372 Lyon, France
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244
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Nguyen P, Awwad RT, Smart DDK, Spitz DR, Gius D. Thioredoxin reductase as a novel molecular target for cancer therapy. Cancer Lett 2005; 236:164-74. [PMID: 15955621 DOI: 10.1016/j.canlet.2005.04.028] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2005] [Accepted: 04/24/2005] [Indexed: 11/23/2022]
Abstract
Tumor cell proliferation, de-differentiation, and progression depend on a complex combination of altered cell cycle regulation, excessive growth factor pathway activation, and decreased apoptosis. The understanding of these complex mechanisms should lead to the identification of potential targets for therapeutic intervention. Redox-sensitive signaling factors also regulate multiple cellular processes including proliferation, cell cycle, and pro-survival signaling cascades, suggesting their potential as molecular targets for anticancer agents. These observations suggest that redox-sensitive signaling factors may be potential novel molecular markers. We hypothesized that thioredoxin reductase-1 (TR), a component of several redox-regulated pathways, may represent a potential molecular target candidate in response to agents that induce oxidative stress. There have been numerous biological studies over the last decade investigating the cell biological, biochemical, and genetic properties of TR both in culture and in in vivo models. In addition, using a series of permanent cell lines that express either a wild-type TR or a dominant mutant TR gene or a chemical agent that inhibits TR we demonstrated that TR meets most criteria that would identify a molecular target. Based on these results we believe TR is a potential molecular target and discuss potential clinical possibilities.
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Affiliation(s)
- Phuongmai Nguyen
- Molecular Radiation Oncology Section, Radiation Oncology Branch, Radiation Oncology Sciences Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
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Shatilla A, Leduc A, Yang X, Ramotar D. Identification of two apurinic/apyrimidinic endonucleases from Caenorhabditis elegans by cross-species complementation. DNA Repair (Amst) 2005; 4:655-70. [PMID: 15907773 DOI: 10.1016/j.dnarep.2005.02.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2005] [Revised: 02/18/2005] [Accepted: 02/22/2005] [Indexed: 11/27/2022]
Abstract
The Saccharomyces cerevisiae mutant strain YW778, which lacks apurinic/apyrimidinic (AP) endonuclease and 3'-diesterase DNA repair activities, displays high levels of spontaneous mutations and hypersensitivities to several DNA damaging agents. We searched a cDNA library derived from the nematode Caenorhabditis elegans for gene products that would rescue the DNA repair defects of this yeast mutant. We isolated two genes, apn-1 and exo-3, encoding proteins that have not been previously characterized. Both APN-1 and EXO-3 share significant identity with the functionally established Escherichia coli AP endonucleases, endonuclease IV and exonuclease III, respectively. Strain YW778 expressing either apn-1 or exo-3 shows parental levels of spontaneous mutations, as well as resistance to DNA damaging agents that produce AP sites and DNA single strand breaks with blocked 3'-ends. Using an in vitro assay, we show that the apn-1 and exo-3 genes independently express AP endonuclease activity in the yeast mutant. We further characterize the EXO-3 protein and three of its mutated variants E68A, D190A, and H279A. The E68A variant retains both AP endonuclease and 3'-diesterase repair activities in vitro, yet severely lacks the ability to protect strain YW778 from spontaneous and drug-induced DNA lesions, suggesting that this variant E68A may possess a defect that interferes with the repair process in vivo. In contrast, D190A and H279A are completely devoid of DNA repair activities and fail to rescue the genetic instability of strain YW778. Our data strongly suggest that EXO-3 and APN-1 are enzymes possessing intrinsic AP endonuclease and 3'-diesterase activities.
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Affiliation(s)
- Andrea Shatilla
- University of Montreal, Maisonneuve-Rosemont Hospital, Guy-Bernier Research Centre, 5415 de l'Assomption, Montreal, Que., Canada H1T 2M4
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246
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Szczesny B, Bhakat KK, Mitra S, Boldogh I. Age-dependent modulation of DNA repair enzymes by covalent modification and subcellular distribution. Mech Ageing Dev 2005; 125:755-65. [PMID: 15541770 DOI: 10.1016/j.mad.2004.07.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Chronic oxidative stress is generally believed to be a major etiologic factor in the aging process. In addition to modulation of signaling processes and oxidation of cellular proteins and lipids, reactive oxygen species (ROS) induce multiple damages in both nuclear and mitochondrial genomes, most of which are repaired via the DNA base excision repair pathway. 8-Oxoguanine (8-oxoG), a major ROS product in the genome, is excised by 8-oxoG-DNA glycosylase (OGG1) and the resulting abasic (AP) site is cleaved by AP-endonuclease (APE1) in the initial steps of repair. Here, we provide data showing that differences between young and aged cells' efficiency in import of OGG1 and APE1 may be responsible for age-associated increase in DNA damage in both nuclear and mitochondrial compartments. It is also evident that age-dependent changes in covalent modifications of APE1 by acetylation regulate its action as a transcriptional repressor of many Ca(2+)-responsive genes by binding to nCaRE, in addition to its endonuclease activity. Thus, ROS-induced altered signaling is responsible for age-dependent changes in post-translational modifications and import of DNA repair enzymes into nuclei and mitochondria (mt), which in turn affect repair of their genomes.
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Affiliation(s)
- Bartosz Szczesny
- Sealy Center for Molecular Science, University of Texas Medical Branch, 6.136 Medical Research Building, Route 1079, Galveston, TX 77555, USA
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247
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Cao X, Kambe F, Lu X, Kobayashi N, Ohmori S, Seo H. Glutathionylation of two cysteine residues in paired domain regulates DNA binding activity of Pax-8. J Biol Chem 2005; 280:25901-6. [PMID: 15888455 DOI: 10.1074/jbc.m411443200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We reported that the first two cysteine residues out of three present in paired domain (PD), a DNA-binding domain, are responsible for redox regulation of Pax-8 DNA binding activity. We show that glutathionylation of these cysteines has a regulatory role in PD binding. Wild-type PD and its mutants with substitution of cysteine to serine were synthesized and named CCC, CSS, SCS, SSC, and SSS according to the positions of substituted cysteines. They were incubated in a buffer containing various ratios of GSH/GSSG and subjected to gel shift assay. Binding of CCC, CSS, and SCS was impaired with decreasing GSH/GSSG ratio, whereas that of SSC and SSS was not affected. Because [3H]glutathione was incorporated into CCC, CSS, and SCS, but not into SSC and SSS, the binding impairment was ascribed to glutathionylation of the redox-reactive cysteines. This oxidative inactivation of PD binding was reversed by a reductant dithiothreitol and by redox factor (Ref)-1 in vitro. To explore the glutathionylation in cells, Chinese hamster ovary cells overexpressing CSS and SCS were labeled with [35S]cysteine in the presence of cycloheximide. Immunoprecipitation with an antibody against PD revealed that treatment of the cells with an oxidant diamide induced the 35S incorporation into both mutants, suggesting the PD glutathionylation in cells. Since the two cysteine residues in PD are conserved in all Pax members, this novel posttranslational modification of PD would provide a new insight into molecular basis for modulation of Pax function.
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Affiliation(s)
- Xia Cao
- Department of Endocrinology and Metabolism, Division of Molecular and Cellular Adaptation, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Japan.
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248
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O'reilly MA, Vitiello PF, Gehen SC, Staversky RJ. p21(Cip1/WAF1/Sdi1) does not affect expression of base excision DNA repair enzymes during chronic oxidative stress. Antioxid Redox Signal 2005; 7:719-25. [PMID: 15890018 DOI: 10.1089/ars.2005.7.719] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Exposure to chronic oxidative stress during elevated oxygen (hyperoxia) damages DNA and inhibits cell proliferation in G(1) through induction of the cyclin-dependent kinase inhibitor p21. Cells that fail to express p21 growth-arrest in S phase. The observation that growth arrest in G(1) is associated with reduced DNA damage and enhanced survival suggests that p21 may affect expression of base excision repair (BER) enzymes used to repair oxidized DNA. This hypothesis was tested in p21 wild-type and p21-deficient mice and human lung adenocarcinoma H1299 cells with tetracycline-on regulated expression of p21. The mRNA levels of Ogg1, Tdg, Udg, Mpg, Nth1, and Mgmt remained constant during 3 days of hyperoxia. The expression of Ogg1, Nth1, and APE protein also remained unchanged. Although hyperoxia increased p21, its absence did not significantly affect expression of these repair enzymes. These findings reveal that hyperoxia induces p21 without significantly altering BER enzyme expression. This suggests that p21 may protect oxidized cells by affecting the activity of BER enzymes and/or through other mechanisms, such as apoptosis.
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Affiliation(s)
- Michael A O'reilly
- Department of Pediatrics, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA.
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249
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Laderoute KR. The interaction between HIF-1 and AP-1 transcription factors in response to low oxygen. Semin Cell Dev Biol 2005; 16:502-13. [PMID: 16144688 DOI: 10.1016/j.semcdb.2005.03.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Hypoxia-inducible factor-1 (HIF-1) is a critical regulator of the transcriptional response to low oxygen conditions (hypoxia/anoxia) experienced by mammalian cells in both physiological and pathophysiological circumstances. As our understanding of the biology and biochemistry of HIF-1 has grown, it has become apparent that cells adapt to signals generated by low oxygen through a network of stress responsive transcription factors or complexes, which are influenced by HIF-1 activity. This review summarizes our current understanding of the interaction of HIF-1 with AP-1, a classic example of a family of pleiotropic transcription factors that impact on diverse cellular processes and phenotypes, including the adaptation to low oxygen stress. The review focuses on experimental studies involving cultured cells exposed to hypoxia/anoxia, and describes both established and possible interactions between HIF-1 and AP-1 at different levels of cellular organization.
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Affiliation(s)
- Keith R Laderoute
- Biosciences Division, SRI International, Bldg. L, Rm. A258, 333 Ravenswood Avenue, Menlo Park, CA 94025, USA.
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250
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Izumi T, Brown DB, Naidu CV, Bhakat KK, Macinnes MA, Saito H, Chen DJ, Mitra S. Two essential but distinct functions of the mammalian abasic endonuclease. Proc Natl Acad Sci U S A 2005; 102:5739-43. [PMID: 15824325 PMCID: PMC556297 DOI: 10.1073/pnas.0500986102] [Citation(s) in RCA: 177] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The mammalian abasic endonuclease, APE1, has two distinct roles in the repair of oxidative DNA damage and in gene regulation. Here we show that both functions are essential for cell survival. Deletion of the APE1 gene causes embryonic lethality in mice, and no nullizygous embryo fibroblasts have been isolated. We have now established nullizygous embryo fibroblast lines from APE1(-/-) mouse embryos that are transgenic with the "floxed" human APE1 (hAPE1) gene. Removal of hAPE1 by Cre expression through nuclear microinjection elicited apoptosis in these cells within 24 h, which was blocked by coinjection of the wild-type hAPE1 gene. In contrast, mutant hAPE1 alleles, lacking either the DNA repair or acetylation-mediated gene regulatory function, could not prevent apoptosis, although the combination of these two mutants complemented APE deficiency induced by Cre. These results indicate that distinct and separable functions of APE1 are both essential for mammalian cells even in vitro and provide the evidence that mammalian cells, unlike yeast or Escherichia coli, absolutely require APE for survival, presumably to protect against spontaneous oxidative DNA damage.
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Affiliation(s)
- Tadahide Izumi
- Sealy Center for Molecular Science, Department of Human Biological Chemistry and Genetics, University of Texas Medical Branch, Galveston, TX 77555, USA
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