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Shin E, Kwon Y, Jung E, Kim YJ, Kim C, Hong S, Kim J. TM4SF19 controls GABP-dependent YAP transcription in head and neck cancer under oxidative stress conditions. Proc Natl Acad Sci U S A 2024; 121:e2314346121. [PMID: 38315837 PMCID: PMC10873613 DOI: 10.1073/pnas.2314346121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 01/04/2024] [Indexed: 02/07/2024] Open
Abstract
Tobacco and alcohol are risk factors for human papillomavirus-negative head and neck squamous cell carcinoma (HPV- HNSCC), which arises from the mucosal epithelium of the upper aerodigestive tract. Notably, despite the mutagenic potential of smoking, HPV- HNSCC exhibits a low mutational load directly attributed to smoking, which implies an undefined role of smoking in HPV- HNSCC. Elevated YAP (Yes-associated protein) mRNA is prevalent in HPV- HNSCC, irrespective of the YAP gene amplification status, and the mechanism behind this upregulation remains elusive. Here, we report that oxidative stress, induced by major risk factors for HPV- HNSCC such as tobacco and alcohol, promotes YAP transcription via TM4SF19 (transmembrane 4 L six family member 19). TM4SF19 modulates YAP transcription by interacting with the GABP (Guanine and adenine-binding protein) transcription factor complex. Mechanistically, oxidative stress induces TM4SF19 dimerization and topology inversion in the endoplasmic reticulum membrane, which in turn protects the GABPβ1 subunit from proteasomal degradation. Conversely, depletion of TM4SF19 impairs the survival, proliferation, and migration of HPV- HNSCC cells, highlighting the potential therapeutic relevance of targeting TM4SF19. Our findings reveal the roles of the key risk factors of HPV- HNSCC in tumor development via oxidative stress, offering implications for upcoming therapeutic approaches in HPV- HNSCC.
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Affiliation(s)
- Eunbie Shin
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon34141, Korea
| | - Yongsoo Kwon
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon34141, Korea
| | - Eunji Jung
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon34141, Korea
| | - Yong Joon Kim
- Department of Ophthalmology, Severance Hospital, Institute of Vision Research, Yonsei University College of Medicine, Seoul03722, South Korea
| | - Changgon Kim
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon34141, Korea
| | - Semyeong Hong
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon34141, Korea
| | - Joon Kim
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon34141, Korea
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2
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Sevilla F, Martí MC, De Brasi-Velasco S, Jiménez A. Redox regulation, thioredoxins, and glutaredoxins in retrograde signalling and gene transcription. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:5955-5969. [PMID: 37453076 PMCID: PMC10575703 DOI: 10.1093/jxb/erad270] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 07/12/2023] [Indexed: 07/18/2023]
Abstract
Integration of reactive oxygen species (ROS)-mediated signal transduction pathways via redox sensors and the thiol-dependent signalling network is of increasing interest in cell biology for their implications in plant growth and productivity. Redox regulation is an important point of control in protein structure, interactions, cellular location, and function, with thioredoxins (TRXs) and glutaredoxins (GRXs) being key players in the maintenance of cellular redox homeostasis. The crosstalk between second messengers, ROS, thiol redox signalling, and redox homeostasis-related genes controls almost every aspect of plant development and stress response. We review the emerging roles of TRXs and GRXs in redox-regulated processes interacting with other cell signalling systems such as organellar retrograde communication and gene expression, especially in plants during their development and under stressful environments. This approach will cast light on the specific role of these proteins as redox signalling components, and their importance in different developmental processes during abiotic stress.
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Affiliation(s)
- Francisca Sevilla
- Abiotic Stress, Production and Quality Laboratory, Department of Stress Biology and Plant Pathology, CEBAS-CSIC, Murcia, Spain
| | - Maria Carmen Martí
- Abiotic Stress, Production and Quality Laboratory, Department of Stress Biology and Plant Pathology, CEBAS-CSIC, Murcia, Spain
| | - Sabrina De Brasi-Velasco
- Abiotic Stress, Production and Quality Laboratory, Department of Stress Biology and Plant Pathology, CEBAS-CSIC, Murcia, Spain
| | - Ana Jiménez
- Abiotic Stress, Production and Quality Laboratory, Department of Stress Biology and Plant Pathology, CEBAS-CSIC, Murcia, Spain
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Saei AA, Gullberg H, Sabatier P, Beusch CM, Johansson K, Lundgren B, Arvidsson PI, Arnér ESJ, Zubarev RA. Comprehensive chemical proteomics for target deconvolution of the redox active drug auranofin. Redox Biol 2020; 32:101491. [PMID: 32199331 PMCID: PMC7082630 DOI: 10.1016/j.redox.2020.101491] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 02/17/2020] [Accepted: 03/02/2020] [Indexed: 12/17/2022] Open
Abstract
Chemical proteomics encompasses novel drug target deconvolution methods in which compound modification is not required. Herein we use Thermal Proteome Profiling, Functional Identification of Target by Expression Proteomics and multiplexed redox proteomics for deconvolution of auranofin targets to aid elucidation of its mechanisms of action. Auranofin (Ridaura®) was approved for treatment of rheumatoid arthritis in 1985. Because several clinical trials are currently ongoing to repurpose auranofin for cancer therapy, comprehensive characterization of its targets and effects in cancer cells is important. Together, our chemical proteomics tools confirmed thioredoxin reductase 1 (TXNRD1, EC:1.8.1.9) as a main auranofin target, with perturbation of oxidoreductase pathways as the top mechanism of drug action. Additional indirect targets included NFKB2 and CHORDC1. Our comprehensive data can be used as a proteomic signature resource for further analyses of the effects of auranofin. Here we also assessed the orthogonality and complementarity of different chemical proteomics methods that can furnish invaluable mechanistic information and thus the approach can facilitate drug discovery efforts in general.
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Affiliation(s)
- Amir Ata Saei
- Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 65, Stockholm, Sweden; Science for Life Laboratory, Drug Discovery and Development Platform, Biochemical and Cellular Assay Facility, Stockholm, Sweden and Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Hjalmar Gullberg
- Science for Life Laboratory, Drug Discovery and Development Platform, Biochemical and Cellular Assay Facility, Stockholm, Sweden and Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Pierre Sabatier
- Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 65, Stockholm, Sweden
| | - Christian M Beusch
- Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 65, Stockholm, Sweden
| | - Katarina Johansson
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institute, 171 65, Stockholm, Sweden; Pfizer Innovations AB, 191 90, Sollentuna, Sweden
| | - Bo Lundgren
- Science for Life Laboratory, Drug Discovery and Development Platform, Biochemical and Cellular Assay Facility, Stockholm, Sweden and Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Per I Arvidsson
- Science for Life Laboratory Drug Discovery and Development Platform and Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 65, Stockholm, Sweden
| | - Elias S J Arnér
- Science for Life Laboratory, Drug Discovery and Development Platform, Biochemical and Cellular Assay Facility, Stockholm, Sweden and Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Roman A Zubarev
- Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 65, Stockholm, Sweden; Sechenov First Moscow State Medical University, 119146, Moscow, Russia.
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4
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Niopek K, Üstünel BE, Seitz S, Sakurai M, Zota A, Mattijssen F, Wang X, Sijmonsma T, Feuchter Y, Gail AM, Leuchs B, Niopek D, Staufer O, Brune M, Sticht C, Gretz N, Müller-Decker K, Hammes HP, Nawroth P, Fleming T, Conkright MD, Blüher M, Zeigerer A, Herzig S, Berriel Diaz M. A Hepatic GAbp-AMPK Axis Links Inflammatory Signaling to Systemic Vascular Damage. Cell Rep 2017; 20:1422-1434. [PMID: 28793265 DOI: 10.1016/j.celrep.2017.07.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 03/24/2017] [Accepted: 07/12/2017] [Indexed: 02/06/2023] Open
Abstract
Increased pro-inflammatory signaling is a hallmark of metabolic dysfunction in obesity and diabetes. Although both inflammatory and energy substrate handling processes represent critical layers of metabolic control, their molecular integration sites remain largely unknown. Here, we identify the heterodimerization interface between the α and β subunits of transcription factor GA-binding protein (GAbp) as a negative target of tumor necrosis factor alpha (TNF-α) signaling. TNF-α prevented GAbpα and β complex formation via reactive oxygen species (ROS), leading to the non-energy-dependent transcriptional inactivation of AMP-activated kinase (AMPK) β1, which was identified as a direct hepatic GAbp target. Impairment of AMPKβ1, in turn, elevated downstream cellular cholesterol biosynthesis, and hepatocyte-specific ablation of GAbpα induced systemic hypercholesterolemia and early macro-vascular lesion formation in mice. As GAbpα and AMPKβ1 levels were also found to correlate in obese human patients, the ROS-GAbp-AMPK pathway may represent a key component of a hepato-vascular axis in diabetic long-term complications.
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Affiliation(s)
- Katharina Niopek
- Institute for Diabetes and Cancer (IDC), Helmholtz Center Munich and Technical University Munich, 85764 Neuherberg, Germany; Joint Heidelberg-IDC Translational Diabetes Program, Inner Medicine 1, Heidelberg University Hospital, 69120 Heidelberg, Germany
| | - Bilgen Ekim Üstünel
- Institute for Diabetes and Cancer (IDC), Helmholtz Center Munich and Technical University Munich, 85764 Neuherberg, Germany; Joint Heidelberg-IDC Translational Diabetes Program, Inner Medicine 1, Heidelberg University Hospital, 69120 Heidelberg, Germany
| | - Susanne Seitz
- Institute for Diabetes and Cancer (IDC), Helmholtz Center Munich and Technical University Munich, 85764 Neuherberg, Germany; Joint Heidelberg-IDC Translational Diabetes Program, Inner Medicine 1, Heidelberg University Hospital, 69120 Heidelberg, Germany
| | - Minako Sakurai
- Institute for Diabetes and Cancer (IDC), Helmholtz Center Munich and Technical University Munich, 85764 Neuherberg, Germany; Joint Heidelberg-IDC Translational Diabetes Program, Inner Medicine 1, Heidelberg University Hospital, 69120 Heidelberg, Germany
| | - Annika Zota
- Institute for Diabetes and Cancer (IDC), Helmholtz Center Munich and Technical University Munich, 85764 Neuherberg, Germany; Joint Heidelberg-IDC Translational Diabetes Program, Inner Medicine 1, Heidelberg University Hospital, 69120 Heidelberg, Germany
| | - Frits Mattijssen
- Institute for Diabetes and Cancer (IDC), Helmholtz Center Munich and Technical University Munich, 85764 Neuherberg, Germany; Joint Heidelberg-IDC Translational Diabetes Program, Inner Medicine 1, Heidelberg University Hospital, 69120 Heidelberg, Germany
| | - Xiaoyue Wang
- Joint Division Molecular Metabolic Control, DKFZ-ZMBH Alliance and Network Aging Research, German Cancer Research Center, 69120 Heidelberg, Germany
| | - Tjeerd Sijmonsma
- Joint Division Molecular Metabolic Control, DKFZ-ZMBH Alliance and Network Aging Research, German Cancer Research Center, 69120 Heidelberg, Germany
| | - Yvonne Feuchter
- Joint Division Molecular Metabolic Control, DKFZ-ZMBH Alliance and Network Aging Research, German Cancer Research Center, 69120 Heidelberg, Germany
| | - Anna M Gail
- Joint Division Molecular Metabolic Control, DKFZ-ZMBH Alliance and Network Aging Research, German Cancer Research Center, 69120 Heidelberg, Germany
| | - Barbara Leuchs
- Division of Tumor Virology, German Cancer Research Center, 69120 Heidelberg, Germany
| | - Dominik Niopek
- Division of Theoretical Bioinformatics (B080), German Cancer Research Center, 69120 Heidelberg, Germany; Department of Bioinformatics and Functional Genomics, Institute for Pharmacy and Biotechnology and BioQuant, University of Heidelberg, 69120 Heidelberg, Germany
| | - Oskar Staufer
- Institute for Diabetes and Cancer (IDC), Helmholtz Center Munich and Technical University Munich, 85764 Neuherberg, Germany; Joint Heidelberg-IDC Translational Diabetes Program, Inner Medicine 1, Heidelberg University Hospital, 69120 Heidelberg, Germany
| | - Maik Brune
- Institute for Diabetes and Cancer (IDC), Helmholtz Center Munich and Technical University Munich, 85764 Neuherberg, Germany; Joint Heidelberg-IDC Translational Diabetes Program, Inner Medicine 1, Heidelberg University Hospital, 69120 Heidelberg, Germany
| | - Carsten Sticht
- Medical Research Center, Klinikum Mannheim, 68167 Mannheim, Germany
| | - Norbert Gretz
- Medical Research Center, Klinikum Mannheim, 68167 Mannheim, Germany
| | - Karin Müller-Decker
- Core Facility Tumor Models, German Cancer Research Center, 69120 Heidelberg, Germany
| | - Hans-Peter Hammes
- 5th Medical Department, University Medicine Mannheim, University of Heidelberg, 68167 Mannheim, Germany
| | - Peter Nawroth
- Institute for Diabetes and Cancer (IDC), Helmholtz Center Munich and Technical University Munich, 85764 Neuherberg, Germany; Joint Heidelberg-IDC Translational Diabetes Program, Inner Medicine 1, Heidelberg University Hospital, 69120 Heidelberg, Germany; Department of Internal Medicine I and Clinical Chemistry, University of Heidelberg, 69120 Heidelberg, Germany
| | - Thomas Fleming
- Department of Internal Medicine I and Clinical Chemistry, University of Heidelberg, 69120 Heidelberg, Germany
| | - Michael D Conkright
- Department of Cancer Biology, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Matthias Blüher
- Department of Medicine, University of Leipzig, 04103 Leipzig, Germany
| | - Anja Zeigerer
- Institute for Diabetes and Cancer (IDC), Helmholtz Center Munich and Technical University Munich, 85764 Neuherberg, Germany; Joint Heidelberg-IDC Translational Diabetes Program, Inner Medicine 1, Heidelberg University Hospital, 69120 Heidelberg, Germany
| | - Stephan Herzig
- Institute for Diabetes and Cancer (IDC), Helmholtz Center Munich and Technical University Munich, 85764 Neuherberg, Germany; Joint Heidelberg-IDC Translational Diabetes Program, Inner Medicine 1, Heidelberg University Hospital, 69120 Heidelberg, Germany.
| | - Mauricio Berriel Diaz
- Institute for Diabetes and Cancer (IDC), Helmholtz Center Munich and Technical University Munich, 85764 Neuherberg, Germany; Joint Heidelberg-IDC Translational Diabetes Program, Inner Medicine 1, Heidelberg University Hospital, 69120 Heidelberg, Germany.
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Morales-Prieto N, López de Lerma N, Pacheco IL, Pérez J, Peinado RA, Abril N. Redox proteomics reveals the hepatoprotective effect of must from Pedro Ximénez dried grapes in aged Mus spretus mice. J Funct Foods 2017. [DOI: 10.1016/j.jff.2017.04.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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6
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Cooper CDO, Newman JA, Aitkenhead H, Allerston CK, Gileadi O. Structures of the Ets Protein DNA-binding Domains of Transcription Factors Etv1, Etv4, Etv5, and Fev: DETERMINANTS OF DNA BINDING AND REDOX REGULATION BY DISULFIDE BOND FORMATION. J Biol Chem 2015; 290:13692-709. [PMID: 25866208 PMCID: PMC4447949 DOI: 10.1074/jbc.m115.646737] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Indexed: 12/31/2022] Open
Abstract
Ets transcription factors, which share the conserved Ets DNA-binding domain, number nearly 30 members in humans and are particularly involved in developmental processes. Their deregulation following changes in expression, transcriptional activity, or by chromosomal translocation plays a critical role in carcinogenesis. Ets DNA binding, selectivity, and regulation have been extensively studied; however, questions still arise regarding binding specificity outside the core GGA recognition sequence and the mode of action of Ets post-translational modifications. Here, we report the crystal structures of Etv1, Etv4, Etv5, and Fev, alone and in complex with DNA. We identify previously unrecognized features of the protein-DNA interface. Interactions with the DNA backbone account for most of the binding affinity. We describe a highly coordinated network of water molecules acting in base selection upstream of the GGAA core and the structural features that may account for discrimination against methylated cytidine residues. Unexpectedly, all proteins crystallized as disulfide-linked dimers, exhibiting a novel interface (distant to the DNA recognition helix). Homodimers of Etv1, Etv4, and Etv5 could be reduced to monomers, leading to a 40–200-fold increase in DNA binding affinity. Hence, we present the first indication of a redox-dependent regulatory mechanism that may control the activity of this subset of oncogenic Ets transcription factors.
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Affiliation(s)
- Christopher D O Cooper
- From the Structural Genomics Consortium, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ, United Kingdom
| | - Joseph A Newman
- From the Structural Genomics Consortium, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ, United Kingdom
| | - Hazel Aitkenhead
- From the Structural Genomics Consortium, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ, United Kingdom
| | - Charles K Allerston
- From the Structural Genomics Consortium, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ, United Kingdom
| | - Opher Gileadi
- From the Structural Genomics Consortium, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ, United Kingdom
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7
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Kanno M, Yazawa T, Kawabe S, Imamichi Y, Usami Y, Ju Y, Matsumura T, Mizutani T, Fujieda S, Miyamoto K. Sex-determining region Y-box 2 and GA-binding proteins regulate the transcription of liver receptor homolog-1 in early embryonic cells. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:406-14. [DOI: 10.1016/j.bbagrm.2014.03.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Revised: 03/26/2014] [Accepted: 03/27/2014] [Indexed: 01/08/2023]
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8
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Hayashi R, Takeuchi N, Ueda T. Nuclear Respiratory Factor 2β (NRF-2β) recruits NRF-2α to the nucleus by binding to importin-α:β via an unusual monopartite-type nuclear localization signal. J Mol Biol 2013; 425:3536-48. [PMID: 23856623 DOI: 10.1016/j.jmb.2013.07.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Revised: 07/03/2013] [Accepted: 07/04/2013] [Indexed: 11/28/2022]
Abstract
Nuclear respiratory factor 2 (NRF-2) is a mammalian transcription factor composed of two distinct and unrelated proteins: NRF-2α, which binds to DNA through its Ets domain, and NRF-2β, which contains the transcription activation domain. The activity of NRF-2 in neurons is regulated by nuclear localization; however, the mechanism by which NRF-2 is imported into the nucleus remains unknown. By using in vitro nuclear import assays and immuno-cytofluorescence, we dissect the nuclear import pathways of NRF-2. We show that both NRF-2α and NRF-2β contain intrinsic nuclear localization signals (NLSs): the Ets domain within NRF-2α and the NLS within NRF-2β (amino acids 311/321: EEPPAKRQCIE) that is recognized by importin-α:β. When NRF-2α and NRF-2β form a complex, the nuclear import of NRF-2αβ becomes strictly dependent on the NLS within NRF-2β. Therefore, the nuclear import mechanism of NRF-2 is unique among Ets factors. The NRF-2β NLS contains only two lysine/arginine residues, unlike other known importin-α:β-dependent NLSs. Using ELISA-based binding assays, we show that it is bound by importin-α in almost the same manner and with similar affinity to that of the classical monopartite NLSs, such as c-myc and SV40 T-antigen NLSs. However, the part of the tryptophan array of importin-α that is essential for the recognition of classical monopartite NLSs by generating apolar pockets for the P3 and the P5 lysine/arginine side chains is not required for the recognition of the NRF-2β NLS. We conclude that the NRF-2β NLS is an unusual but is, nevertheless, a bona fide monopartite-type NLS.
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Affiliation(s)
- Rippei Hayashi
- Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwanoha, Kashiwa, Chiba Prefecture 277-8562, Japan.
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9
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Wu H, Xiao Y, Zhang S, Ji S, Wei L, Fan F, Geng J, Tian J, Sun X, Qin F, Jin C, Lin J, Yin ZY, Zhang T, Luo L, Li Y, Song S, Lin SC, Deng X, Camargo F, Avruch J, Chen L, Zhou D. The Ets transcription factor GABP is a component of the hippo pathway essential for growth and antioxidant defense. Cell Rep 2013; 3:1663-77. [PMID: 23684612 DOI: 10.1016/j.celrep.2013.04.020] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2012] [Revised: 02/15/2013] [Accepted: 04/22/2013] [Indexed: 12/21/2022] Open
Abstract
The transcriptional coactivator Yes-associated protein (YAP) plays an important role in organ-size control and tumorigenesis. However, how Yap gene expression is regulated remains unknown. This study shows that the Ets family member GABP binds to the Yap promoter and activates YAP transcription. The depletion of GABP downregulates YAP, resulting in a G1/S cell-cycle block and increased cell death, both of which are substantially rescued by reconstituting YAP. GABP can be inactivated by oxidative mechanisms, and acetaminophen-induced glutathione depletion inhibits GABP transcriptional activity and depletes YAP. In contrast, activating YAP by deleting Mst1/Mst2 strongly protects against acetaminophen-induced liver injury. Similar to its effects on YAP, Hippo signaling inhibits GABP transcriptional activity through several mechanisms. In human liver cancers, enhanced YAP expression is correlated with increased nuclear expression of GABP. Therefore, we conclude that GABP is an activator of Yap gene expression and a potential therapeutic target for cancers driven by YAP.
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Affiliation(s)
- Hongtan Wu
- State Key Laboratory of Stress Cell Biology, School of Life Sciences, Xiamen University, Xiang'an District, Xiamen, Fujian 361102, China
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10
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Chae S, Ahn BY, Byun K, Cho YM, Yu MH, Lee B, Hwang D, Park KS. A Systems Approach for Decoding Mitochondrial Retrograde Signaling Pathways. Sci Signal 2013; 6:rs4. [DOI: 10.1126/scisignal.2003266] [Citation(s) in RCA: 140] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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11
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Verschoor ML, Wilson LA, Singh G. Mechanisms associated with mitochondrial-generated reactive oxygen species in cancer. Can J Physiol Pharmacol 2011; 88:204-19. [PMID: 20393586 DOI: 10.1139/y09-135] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The mitochondria are unique cellular organelles that contain their own genome and, in conjunction with the nucleus, are able to transcribe and translate genes encoding components of the electron transport chain (ETC). To do so, the mitochondria must communicate with the nucleus via the production of reactive oxygen species (ROS) such as hydrogen peroxide (H2O2), which are produced as a byproduct of aerobic respiration within the mitochondria. Mitochondrial signaling is proposed to be altered in cancer cells, where the mitochondria are frequently found to harbor mutations within their genome and display altered functional characteristics leading to increased glycolysis. As signaling molecules, ROS oxidize and inhibit MAPK phosphatases resulting in enhanced proliferation and survival, an effect particularly advantageous to cancer cells. In terms of transcriptional regulation, ROS affect the phosphorylation, activation, oxidation, and DNA binding of transcription factors such as AP-1, NF-kappaB, p53, and HIF-1alpha, leading to changes in target gene expression. Increased ROS production by defective cancer cell mitochondria also results in the upregulation of the transcription factor Ets-1, a factor that has been increasingly associated with aggressive cancers.
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Affiliation(s)
- Meghan L Verschoor
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON L8N 3Z5, Canada
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12
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Finley LW, Haigis MC. The coordination of nuclear and mitochondrial communication during aging and calorie restriction. Ageing Res Rev 2009; 8:173-88. [PMID: 19491041 DOI: 10.1016/j.arr.2009.03.003] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Revised: 02/27/2009] [Accepted: 03/04/2009] [Indexed: 12/24/2022]
Abstract
Mitochondria are dynamic organelles that integrate environmental signals to regulate energy production, apoptosis and Ca(2+) homeostasis. Not surprisingly, mitochondrial dysfunction is associated with aging and the pathologies observed in age-related diseases. The vast majority of mitochondrial proteins are encoded in the nuclear genome, and so communication between the nucleus and mitochondria is essential for maintenance of appropriate mitochondrial function. Several proteins have emerged as major regulators of mitochondrial gene expression, capable of increasing transcription of mitochondrial genes in response to the physiological demands of the cell. In this review, we will focus on PGC-1alpha, SIRT1, AMPK and mTOR and discuss how these proteins regulate mitochondrial function and their potential involvement in aging, calorie restriction and age-related disease. We will also discuss the pathways through which mitochondria signal to the nucleus. Although such retrograde signaling is not well studied in mammals, there is growing evidence to suggest that it may be an important area for future aging research. Greater understanding of the mechanisms by which mitochondria and the nucleus communicate will facilitate efforts to slow or reverse the mitochondrial dysfunction that occurs during aging.
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13
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Pandit A, Vadnal J, Houston S, Freeman E, McDonough J. Impaired regulation of electron transport chain subunit genes by nuclear respiratory factor 2 in multiple sclerosis. J Neurol Sci 2009; 279:14-20. [PMID: 19187944 DOI: 10.1016/j.jns.2009.01.009] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Revised: 12/09/2008] [Accepted: 01/08/2009] [Indexed: 11/27/2022]
Abstract
Multiple sclerosis (MS) is an inflammatory neurodegenerative disease. Recently, decreased expression of nuclear encoded electron transport chain genes was found in neurons in MS cortex. To understand the transcriptional mechanisms responsible for the coordinate down regulation of these genes, we performed electrophoretic mobility shifts with nuclear extracts isolated from gray matter from nonlesion areas of postmortem MS and control cortex. Nine tissue blocks from eight different MS brains and six matched control blocks from five control brains were analyzed. We identified a decrease in a transcription factor complex containing nuclear respiratory factor 2 (NRF-2) in nuclear extracts isolated from MS cortex. This decrease is correlated with decreased expression of electron transport chain subunit genes and increased oxidative damage measured by increased anti-nitrotyrosine immunoreactivity. We conclude that in MS cortex a chronic increase in oxidative stress leads to aberrant regulation of transcription of genes involved in energy metabolism.
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Affiliation(s)
- Ashish Pandit
- School of Biomedical Sciences, Kent State University, Kent, OH 44242, USA
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14
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Coffman JA, Denegre JM. Mitochondria, redox signaling and axis specification in metazoan embryos. Dev Biol 2007; 308:266-80. [PMID: 17586486 DOI: 10.1016/j.ydbio.2007.05.042] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Revised: 05/30/2007] [Accepted: 05/30/2007] [Indexed: 11/29/2022]
Abstract
Mitochondria are not only the major energy generators of the eukaryotic cell but they are also sources of signals that control gene expression and cell fate. While mitochondria are often asymmetrically distributed in early embryos, little is known about how they contribute to axial patterning. Here we review studies of mitochondrial distribution in metazoan eggs and embryos and the mechanisms of redox signaling, and speculate on the role that mitochondrial anisotropies might play in the developmental specification of cell fate during embryogenesis of sea urchins and other animals.
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Affiliation(s)
- James A Coffman
- Mount Desert Island Biological Laboratory, Salisbury Cove, ME 04672, USA.
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15
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Jaworski A, Smith CL, Burden SJ. GA-binding protein is dispensable for neuromuscular synapse formation and synapse-specific gene expression. Mol Cell Biol 2007; 27:5040-6. [PMID: 17485447 PMCID: PMC1951497 DOI: 10.1128/mcb.02228-06] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The mRNAs encoding postsynaptic components at the neuromuscular junction are concentrated in the synaptic region of muscle fibers. Accumulation of these RNAs in the synaptic region is mediated, at least in part, by selective transcription of the corresponding genes in synaptic myofiber nuclei. The transcriptional mechanisms that are responsible for synapse-specific gene expression are largely unknown, but an Ets site in the promoter regions of acetylcholine receptor (AChR) subunit genes and other "synaptic" genes is required for synapse-specific transcription. The Ets domain transcription factor GA-binding protein (GABP) has been implicated to mediate synapse-specific gene expression. Inactivation of GABPalpha, the DNA-binding subunit of GABP, leads to early embryonic lethality, preventing analysis of synapse formation in gabpalpha mutant mice. To study the role of GABP at neuromuscular synapses, we conditionally inactivated gabpalpha in skeletal muscle and studied synaptic differentiation and muscle gene expression. Although expression of rb, a target of GABP, is elevated in muscle tissue deficient in GABPalpha, clustering of synaptic AChRs at synapses and synapse-specific gene expression are normal in these mice. These data indicate that GABP is dispensable for synapse-specific transcription and maintenance of normal AChR expression at synapses.
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Affiliation(s)
- Alexander Jaworski
- The Helen L. and Martin S. Kimmel Center for Biology and Medicine, Skirball Institute of Biomoledular Medicine, NYU School of Medicine, New York, NY 10016, USA
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16
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Zanotto E, Shah ZH, Jacobs HT. The bidirectional promoter of two genes for the mitochondrial translational apparatus in mouse is regulated by an array of CCAAT boxes interacting with the transcription factor NF-Y. Nucleic Acids Res 2006; 35:664-77. [PMID: 17179180 PMCID: PMC1802594 DOI: 10.1093/nar/gkl1037] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The genes for mitoribosomal protein S12 (Mrps12) and mitochondrial seryl-tRNA ligase (Sarsm and Sars2) are oppositely transcribed from a conserved promoter region of <200 bp in both human and mouse. Using a dual reporter vector we identified an array of 4 CCAAT box elements required for efficient transcription of the two genes in cultured mouse 3T3 cells, and for enforcing directionality in favour of Mrps12. Electrophoretic mobility shift assay (EMSA) and in vivo footprinting confirmed the importance of these promoter elements as sites of protein-binding, and EMSA supershift and chromatin immunoprecipitation (ChIP) assays identified NF-Y as the key transcription factor involved, revealing a common pattern of protein–DNA interactions in all tissues tested (liver, brain, heart, kidney and 3T3 cells). The inherently bidirectional activity of NF-Y makes it an especially suitable factor to govern promoters of this class, whose expression is linked to cell proliferation.
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Affiliation(s)
- Ernesto Zanotto
- Institute of Medical Technology & Tampere University Hospital, FI-33014 University of TampereFinland
| | - Zahid H. Shah
- Institute of Medical Technology & Tampere University Hospital, FI-33014 University of TampereFinland
| | - Howard T. Jacobs
- Institute of Medical Technology & Tampere University Hospital, FI-33014 University of TampereFinland
- Institute of Biomedical and Life Sciences, University of GlasgowGlasgow G12 8QQ, Scotland, UK
- To whom correspondence should be addressed. Tel: +35 8335517731; Fax: +35 832157710;
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17
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LeMoine CMR, McClelland GB, Lyons CN, Mathieu-Costello O, Moyes CD. Control of mitochondrial gene expression in the aging rat myocardium. Biochem Cell Biol 2006; 84:191-8. [PMID: 16609700 DOI: 10.1139/o05-169] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Aging induces complex changes in myocardium bioenergetic and contractile properties. Using F344BNF(1) rats, we examined age-dependent changes in myocardial bioenergetic enzymes (catalytic activities and transcript levels) and mRNA levels of putative transcriptional regulators of bioenergetic genes. Very old rats (35 months) showed a 22% increase in ventricular mass with no changes in DNA or RNA per gram. Age-dependent cardiac hypertrophy was accompanied by complex changes in mitochondrial enzymes. Enzymes of the Krebs cycle and electron transport system remained within 15% of the values measured in adult heart, significant decreases occurring in citrate synthase (10%) and aconitase (15%). Transcripts for these enzymes were largely unaffected by aging, although mRNA levels of putative transcriptional regulators of the enzymes (nuclear respiratory factor (NRF) 1 and 2 alpha subunit) increased by about 30%-50%. In contrast, enzymes of fatty acid oxidation exhibited a more diverse pattern, with a 50% decrease in beta-hydroxyacyl-CoA dehydrogenase (HOAD) and no change in long-chain acyl-CoA dehydrogenase or carnitine palmitoyltransferase. Transcript levels for fatty acid oxidizing enzymes covaried with HOAD, which declined significantly by 30%. There were no significant changes in the relative transcript levels of regulators of genes for fatty acid oxidizing enzymes: peroxisome proliferator-activated receptor-alpha (PPARalpha), PPARbeta, or PPARgamma coactivator-1alpha (PGC-1alpha). There were no changes in the mRNA levels of Sirt1, a histone-modifying enzyme that interacts with PGC-1alpha. Collectively, these data suggest that aging causes complex changes in the enzymes of myocardial energy metabolism, triggered in part by NRF-independent pathways as well as post-transcriptional regulation.
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18
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Kraft CS, LeMoine CMR, Lyons CN, Michaud D, Mueller CR, Moyes CD. Control of mitochondrial biogenesis during myogenesis. Am J Physiol Cell Physiol 2006; 290:C1119-27. [PMID: 16531567 DOI: 10.1152/ajpcell.00463.2005] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We used expression and reporter gene analysis to understand how changes in transcription factors impinge on mitochondrial gene expression during myogenesis of cultured murine myoblasts (C2C12 and Sol8). The mRNA levels for nuclear respiratory factor-1 (NRF-1) and NRF-2α increased 60% by the third day of myogenesis, whereas NRF-1 and NRF-2 reporter gene activity increased by fivefold over the same period. Although peroxisome proliferator activated receptor (PPARα) mRNA levels increased almost 10-fold, the activity of a PPAR reporter was unchanged during myogenesis. The PPAR coactivator PPAR-γ coactivator-1α (PGC1α), a master controller of mitochondrial biogenesis, was not expressed at detectable levels. However, the mRNA for both PGC1α-related coactivator and PGC1β was abundant, with the latter increasing by 50% over 3 days of differentiation. We also conducted promoter analysis of the gene for citrate synthase (CS), a common mitochondrial marker enzyme. The proximal promoter (∼2,100 bp) of the human CS lacks binding sites for PPAR, NRF-1, or NRF-2. Deletion mutants, a targeted mutation, and an Sp1 site-containing reporter construct suggest that changes in Sp1 regulation also participate in mitochondrial biogenesis during myogenesis. Because most mitochondrial genes are regulated by PPARs, NRF-1, and/or NRF-2, we conducted inhibitor studies to further support the existence of a distinct pathway for CS gene regulation in myogenesis. Although both LY-294002 (a phosphatidylinositol 3-kinase inhibitor) and SB-203580 (a p38-MAPK inhibitor) blocked myogenesis (as indicated by creatine phosphokinase activity), only SB-203580 prevented the myogenic increase in cytochrome oxidase activity, whereas only LY-294002 blocked the increase in CS (enzyme and reporter gene activities). Collectively, these studies help delineate the roles of some transcriptional regulators involved in mitochondrial biogenesis associated with myogenesis and underscore an import role for posttranscriptional regulation of transcription factor activity.
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Affiliation(s)
- C S Kraft
- Department of Biology, Queen's University, Kingston, ON, K7L 3N6, Canada
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19
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Patton J, Block S, Coombs C, Martin ME. Identification of functional elements in the murine Gabp alpha/ATP synthase coupling factor 6 bi-directional promoter. Gene 2005; 369:35-44. [PMID: 16309857 DOI: 10.1016/j.gene.2005.10.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2005] [Revised: 09/26/2005] [Accepted: 10/10/2005] [Indexed: 11/19/2022]
Abstract
The GA-repeat binding protein (GABP) is a ubiquitous transcription factor involved in transcriptional regulation of genes encoding proteins involved in a variety of cellular processes including adipocyte differentiation, mitochondrial respiration, and neuromuscular signaling. GABP is composed of two subunits; the GABP alpha subunit is a member of the Ets-family of transcription factors, and the unrelated ankyrin repeat containing GABP beta subunit. We previously identified a bidirectional promoter directing the expression of Gabpa (GAA) gene in one direction and ATP Synthase Coupling Factor 6 (Atp5j) (CF6) gene in the other [Chinenov, Y., Coombs, C. and Martin, M. E., 2000a. "Isolation of a bi-directional promoter directing the expression of the mouse GABP alpha and ATP Synthase Coupling Factor 6 genes. Gene 261:311-320.]. In this study we characterize sequence elements and regulatory factors contributing to the promoter activities of the GAA/CF6 bidirectional promoter. The core of the GAA/CF6 bidirectional promoter is retained within a 400 bp sequence and contains four GABP binding sites, a Sp1/3 binding site and an YY1 binding site. Site-directed mutagenesis demonstrated that while no single factor binding site was essential for promoter activity in either direction, the GA1 site located proximal to the previously mapped transcription start sites functioned cooperatively with the other GABP binding sites and with the Sp1/3 and YY1 sites to provide transcriptional activation of the GAA and CF6 promoters. The other GABP sites and the Sp1/3 and YY1 binding sites were functionally redundant for basal promoter activities in both directions. Electrophoretic mobility shift assays identified multiple DNA-protein complexes containing GABP alpha, GABP beta, Sp1, Sp3 or YY1 proteins, including one ternary complex containing GABP alpha, GABP beta and Sp1 proteins. Binding of GABP to the GAA/CF6 bi-directional promoter provides the potential for autoregulation of GABP alpha expression and confirms the importance of GABP in the coordinate expression of respiratory chain components.
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Affiliation(s)
- John Patton
- Department of Biochemistry, University of Missouri, Columbia, MO 65212, USA
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20
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Wong-Riley MTT, Yang SJ, Liang HL, Ning G, Jacobs P. Quantitative immuno-electron microscopic analysis of nuclear respiratory factor 2 alpha and beta subunits: Normal distribution and activity-dependent regulation in mammalian visual cortex. Vis Neurosci 2005; 22:1-18. [PMID: 15842736 DOI: 10.1017/s0952523805221016] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2004] [Indexed: 11/07/2022]
Abstract
The macaque visual cortex is exquisitely organized into columns, modules, and streams, much of which can be correlated with its metabolic organization revealed by cytochrome oxidase (CO). Plasticity in the adult primate visual system has also been documented by changes in CO activity. Yet, the molecular mechanism of regulating this enzyme remains not well understood. Being one of only four bigenomic enzymes in mammalian cells, the transcriptional regulation of this enzyme necessitates a potential bigenomic coordinator. Nuclear respiratory factor 2 (NRF-2) or GA-binding protein is a transcription factor that may serve such a critical role. The goal of the present study was to determine if the two major subunits of NRF-2, 2alpha and 2beta, had distinct subcellular distribution in neurons of the rat and monkey visual cortex, if major metabolic neuronal types in the macaque exhibited different levels of the two subunits, and if they would respond differently to monocular impulse blockade. Quantitative immuno-electron microscopy was used. In both rats and monkeys, nuclear labeling of alpha and beta subunits was mainly over euchromatin rather than heterochromatin, consistent with their active participation in transcriptional activity. Cytoplasmic labeling was over free ribosomes, the Golgi apparatus, and occasionally the nuclear envelope, signifying sites of synthesis and possible posttranslational modifications. The density of both subunits was much higher in the nucleus than in the cytoplasm for all neurons examined, again indicating that their major sites of cellular action is in the nucleus.
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Affiliation(s)
- Margaret T T Wong-Riley
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee 53226, USA.
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21
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O'Leary DA, Pritchard MA, Xu D, Kola I, Hertzog PJ, Ristevski S. Tissue-specific overexpression of the HSA21 gene GABPalpha: implications for DS. Biochim Biophys Acta Mol Basis Dis 2005; 1739:81-7. [PMID: 15607120 DOI: 10.1016/j.bbadis.2004.09.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2004] [Revised: 09/07/2004] [Accepted: 09/08/2004] [Indexed: 11/15/2022]
Abstract
The ETS transcription factor GABPalpha is encoded by a gene on HSA21 and interacts with an ankyrin repeat-containing beta subunit to form the GABP complex. GABP regulates expression of genes involved in mitochondrial respiration and neuromuscular signalling. When GABPalpha mRNA is overexpressed in human DS fibroblast cell lines, or by tranfection in NIH3T3 cells, no increase in protein level is detected. However, increased Gabpalpha gene dosage in the Ts65Dn segmental trisomy mouse model of DS (DS) results in elevated Gabpalpha protein levels in brain and skeletal muscle only. These findings suggest that GABPalpha protein levels are tightly regulated in a tissue-specific manner, and consequently GABP may play a role in DS pathologies in tissues where GABPalpha protein levels are elevated.
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Affiliation(s)
- Debra A O'Leary
- Centre for Functional Genomics and Human Disease, Monash Institute of Reproduction and Development, Monash University, Clayton, Victoria 3168, Australia
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22
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Yang SJ, Liang HL, Ning G, Wong-Riley MTT. Ultrastructural study of depolarization-induced translocation of NRF-2 transcription factor in cultured rat visual cortical neurons. Eur J Neurosci 2004; 19:1153-62. [PMID: 15016074 DOI: 10.1111/j.1460-9568.2004.03250.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nuclear respiratory factor (NRF)-2 or GA-binding protein is a potential transcriptional, bigenomic coordinator of mitochondrial and nuclear-encoded subunits of cytochrome oxidase genes. It is composed of an alpha subunit that binds DNA and a beta subunit that has the transactivating domain. Previously, we found that the level of NRF-2 paralleled that of cytochrome oxidase under normal and functionally altered states. The goal of our present study was to increase the resolution to the ultrastructural level and to quantify changes before and after depolarizing stimulation. We used a pre-embedding immunogold-silver method for the two subunits of NRF-2 in cultured rat visual cortical neurons. NRF-2alpha and beta were normally located in both the nucleus and the cytoplasm. In the nucleus, both subunits were associated primarily with euchromatin rather than heterochromatin, consistent with active involvement in transcription. In the cytoplasm, they were associated mainly with free ribosomes and occasionally with the Golgi apparatus and the outer membrane of the nuclear envelope. Labelling was not found in the mitochondria, confirming the specificity of the antibodies. Neuronal depolarization by KCl for 5 h induced a six- to seven-fold increase in the nuclear-to-cytoplasmic ratio of both subunits (P < 0.001) without increases in total labelling densities. These results strongly indicate that both NRF-2alpha and NRF-2beta respond to increased neuronal activity by translocating from the cytoplasm to the nucleus, where they engage in transcriptional activation of target genes. Our results also indicate that the cytoplasmic to nuclear movement of transcription factors is a dynamic process induced by neuronal activity.
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Affiliation(s)
- Shou Jing Yang
- Department of Cell Biology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
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23
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Suliman HB, Carraway MS, Welty-Wolf KE, Whorton AR, Piantadosi CA. Lipopolysaccharide stimulates mitochondrial biogenesis via activation of nuclear respiratory factor-1. J Biol Chem 2003; 278:41510-8. [PMID: 12902348 DOI: 10.1074/jbc.m304719200] [Citation(s) in RCA: 141] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Exposure to bacterial lipopolysaccharide (LPS) in vivo damages mitochondrial DNA (mtDNA) and interferes with mitochondrial transcription and oxidative phosphorylation (OXPHOS). Because this damage accompanies oxidative stress and is reversible, we postulated that LPS stimulates mtDNA replication and mitochondrial biogenesis via expression of factors responsive to reactive oxygen species, i.e. nuclear respiratory factor-1 (NRF-1) and mitochondrial transcription factor-A. In testing this hypothesis in rat liver, we found that LPS induces NRF-1 protein expression and activity accompanied by mRNA expression for mitochondrial transcription factor-A, mtDNA polymerase gamma, NRF-2, and single-stranded DNA-binding protein. These events restored the loss in mtDNA copy number and OXPHOS gene expression caused by LPS and increased hepatocyte mitotic index, nuclear cyclin D1 translocation, and phosphorylation of pro-survival kinase, Akt. Thus, NRF-1 was implicated in oxidant-mediated mitochondrial biogenesis to provide OXPHOS for proliferation. This implication was tested in novel mtDNA-deficient cells generated from rat hepatoma cells that overexpress NRF-1. Depletion of mtDNA (rhoo clones) diminished oxidant production and caused loss of NRF-1 expression and growth delay. NRF-1 expression and growth were restored by exogenous oxidant exposure indicating that oxidative stress stimulates biogenesis in part via NRF-1 activation and corresponding to recovery events after LPS-induced liver damage.
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Affiliation(s)
- Hagir B Suliman
- Departments of Medicine, Anesthesiology, and Pharmacology, Duke University Medical Center, Durham, North Carolina 27710, USA
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24
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Zelko IN, Folz RJ. Myeloid zinc finger (MZF)-like, Kruppel-like and Ets families of transcription factors determine the cell-specific expression of mouse extracellular superoxide dismutase. Biochem J 2003; 369:375-86. [PMID: 12374566 PMCID: PMC1223085 DOI: 10.1042/bj20021431] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2002] [Revised: 10/08/2002] [Accepted: 10/10/2002] [Indexed: 12/13/2022]
Abstract
Extracellular superoxide dismutase (EC-SOD or SOD3) is an important protective enzyme against the toxicity of superoxide radicals that are produced under both physiological and pathophysiological conditions. We have isolated and characterized over 11 kb of the mouse EC-SOD gene and its 5'- and 3'-flanking regions. The gene consists of two exons, with the entire coding region located within exon 2. In order to study the mechanism of cell-specific gene regulation for mouse EC-SOD, we characterized 2500 bp of its 5'-flanking region using cultured cells derived from mouse lung fibroblasts (MLg), kidney medulla (mIMCD3) and hepatocytes (Hepa 1-6). Real-time PCR showed that basal expression of EC-SOD was considerably higher in MLg cells compared with the other cell types. Reporter-gene assays revealed that the proximal promoter region was sufficient to support this high expression in MLg cells. Although no obvious TATA box was identified, our results show that a highly purine-rich region from -208 to +104 contains active binding sites for both the Kruppel-like and Ets families of transcription factors. Using electrophoretic mobility shift, DNase footprinting and reporter gene assays, we identified myeloid zinc finger 1 and gut-enriched Kruppel-like-factor-like nuclear transcription factors as repressors of EC-SOD expression, whereas nuclear transcription factors from the Ets family, such as Elf-1 and GA-binding protein alpha and beta, were potent activators of EC-SOD transcription. We propose a model that highlights competition between Ets activators and Kruppel-like repressors within the proximal promoter region that determines the level of EC-SOD expression in a particular cell type.
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Affiliation(s)
- Igor N Zelko
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Duke University Medical Center, Durham, NC 27710, U.S.A
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25
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Brookes PS, Levonen AL, Shiva S, Sarti P, Darley-Usmar VM. Mitochondria: regulators of signal transduction by reactive oxygen and nitrogen species. Free Radic Biol Med 2002; 33:755-64. [PMID: 12208364 DOI: 10.1016/s0891-5849(02)00901-2] [Citation(s) in RCA: 250] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The functional role of mitochondria in cell physiology has previously centered around metabolism, with oxidative phosphorylation playing a pivotal role. Recently, however, this perspective has changed significantly with the realization that mitochondria are active participants in signal transduction pathways, not simply the passive recipients of injunctions from the rest of the cell. In this review the emerging role of the mitochondrion in cell signaling is discussed in the context of cytochrome c release, hydrogen peroxide formation from the respiratory chain, and the nitric oxide-cytochrome c oxidase signaling pathway.
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Affiliation(s)
- Paul S Brookes
- Department of Pathology and Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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26
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Scarpulla RC. Nuclear activators and coactivators in mammalian mitochondrial biogenesis. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1576:1-14. [PMID: 12031478 DOI: 10.1016/s0167-4781(02)00343-3] [Citation(s) in RCA: 447] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The biogenesis of mitochondria requires the expression of a large number of genes, most of which reside in the nuclear genome. The protein-coding capacity of mtDNA is limited to 13 respiratory subunits necessitating that nuclear regulatory factors play an important role in governing nucleo-mitochondrial interactions. Two classes of nuclear transcriptional regulators implicated in mitochondrial biogenesis have emerged in recent years. The first includes DNA-binding transcription factors, typified by nuclear respiratory factor (NRF)-1, NRF-2 and others, that act on known nuclear genes that specify mitochondrial functions. A second, more recently defined class, includes nuclear coactivators typified by PGC-1 and related family members (PRC and PGC-1 beta). These molecules do not bind DNA but rather work through their interactions with DNA-bound transcription factors to regulate gene expression. An important feature of these coactivators is that their expression is responsive to physiological signals mediating thermogenesis, cell proliferation and gluconeogenesis. Thus, they have the ability to integrate the action of multiple transcription factors in orchestrating programs of gene expression essential to cellular energetics. The interplay of these nuclear factors appears to be a major determinant in regulating the biogenesis of mitochondria.
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Affiliation(s)
- Richard C Scarpulla
- Department of Cell and Molecular Biology, Northwestern Medical School, 303 East Chicago Avenue, Searle 4-458, Chicago, IL 60611, USA.
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27
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Weitzel JM, Radtke C, Seitz HJ. Two thyroid hormone-mediated gene expression patterns in vivo identified by cDNA expression arrays in rat. Nucleic Acids Res 2001; 29:5148-55. [PMID: 11812848 PMCID: PMC97559 DOI: 10.1093/nar/29.24.5148] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Thyroid hormone (T3) is essential for normal development, differentiation and metabolic balance. Only a limited number of T3-target genes have been identified so far and their complex regulation pattern is poorly understood. We performed cDNA expression array hybridisation to identify T3-regulated genes and to investigate their expression pattern after various time points in vivo. Radioactively labelled cDNA was prepared from hepatic RNA of hypothyroid and hyperthyroid rats 6, 24 and 48 h after the administration of T3. Labelled cDNA probes were hybridised to rat Atlas Arrays. Twenty-three of 588 genes were shown to be differentially regulated, 18 of which were previously not known to be regulated by T3. The expression of 19 genes was verified by independent northern blot hybridisation. Two different expression time courses of T3 expression were observed. In a first expression profile ('early' expression) the transcription level of the target genes rises within 6 h, drops by 24 h and increases again within 48 h after the administration of T3. In a second expression profile ('late' expression) the mRNA level rose in the first 6 h and rose further by 48 h, indicating an additional regulation mechanism. Nuclear respiratory factor (NRF)-1 and peroxisome proliferator-activated receptor gamma coactivator 1 (PGC-1), but not NRF-2, were up-regulated within 6 h after T3 administration, suggesting NRF-1 and/or PGC-1 as key regulators for mediating the 'late' expression pattern.
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Affiliation(s)
- J M Weitzel
- Institut für Medizinische Biochemie und Molekularbiologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
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28
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Preston TJ, Abadi A, Wilson L, Singh G. Mitochondrial contributions to cancer cell physiology: potential for drug development. Adv Drug Deliv Rev 2001; 49:45-61. [PMID: 11377802 DOI: 10.1016/s0169-409x(01)00127-2] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Mitochondria make an integral contribution to the regulation of several aspects of cell biology such as energy production, molecular metabolism, redox status, calcium signalling and programmed cell death. In accordance with an endosymbiotic origin, mitochondria rely upon the nucleus for synthesis and function. In addition, these organelles can respond to intra- and extracellular cues independently, and there exists a highly coordinated "cross talk" between mitochondrial and nuclear signals that can greatly influence cell behaviour. This review focuses upon the putative roles of altered mitochondrial physiology in the process of cellular transformation. Discussed are: mitochondria as targets of drug-induced cytotoxicity or cancer promotion, as regulators of apoptosis, as sources of cell signalling through reactive oxygen species, and mitochondrial control of specific nuclear responses.
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Affiliation(s)
- T J Preston
- Department of Pathology and Molecular Medicine, McMaster University, 699 Concession St., Hamilton, Ontario, Canada L8V 5C2
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29
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Garesse R, Vallejo CG. Animal mitochondrial biogenesis and function: a regulatory cross-talk between two genomes. Gene 2001; 263:1-16. [PMID: 11223238 DOI: 10.1016/s0378-1119(00)00582-5] [Citation(s) in RCA: 223] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Mitochondria play a pivotal role in cell physiology, producing the cellular energy and other essential metabolites as well as controlling apoptosis by integrating numerous death signals. The biogenesis of the oxidative phosphorylation system (OXPHOS) depends on the coordinated expression of two genomes, nuclear and mitochondrial. As a consequence, the control of mitochondrial biogenesis and function depends on extremely complex processes that require a variety of well orchestrated regulatory mechanisms. It is now clear that in order to provide cells with the correct number of structural and functional differentiated mitochondria, a variety of intracellular and extracellular signals including hormones and environmental stimuli need to be integrated. During the last few years a considerable effort has been devoted to study the factors that regulate mtDNA replication and transcription as well as the expression of nuclear-encoded mitochondrial genes in physiological and pathological conditions. Although still in their infancy, these studies are starting to provide the molecular basis that will allow to understand the mechanisms involved in the nucleo-mitochondrial communication, a cross-talk essential for cell life and death.
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Affiliation(s)
- R Garesse
- Instituto de Investigaciones Biomédicas Alberto Sols CSIC-UAM, Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de Madrid, Arturo Duperier, 4, 28029 Madrid, Spain.
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Chinenov Y, Coombs C, Martin ME. Isolation of a bi-directional promoter directing expression of the mouse GABPalpha and ATP synthase coupling factor 6 genes. Gene 2000; 261:311-20. [PMID: 11167019 DOI: 10.1016/s0378-1119(00)00500-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The GA-binding protein (GABP) is a ubiquitous heteromeric transcription factor implicated in the regulation of several genes involved in mitochondrial energy metabolism including subunits of cytochrome c oxidase, ATP synthase, and mitochondrial transcription factor 1 (mtTF1). GABPalpha subunit binds the PEA3/Ets binding sites (EBS), while GABPbeta contains a transcription activation domain and mediates alphabeta dimer and alpha(2)beta(2) tetramer formation essential for activation of transcription. Here we report the cloning of 2449 bp of the mouse (m) GABPalpha promoter region including 201 bp of the 5' end of the published mGABPalpha cDNA sequence. Surprisingly, sequences homologous to the 5'UTR of mouse, rat and human mitochondrial ATP synthase coupling factor 6 (ATPsynCF6) cDNAs were found165-240 bp upstream of the mGABPalpha cDNA. A search of the non-redundant nucleotide database revealed a human genomic sequence derived from chromosome 21 (21q22) bearing significant homology to the mGABPalpha/ATPsynCF6 promoter region and encompassed the entire hGABPalpha and hATPsynCF6 genes. Primer extension analysis revealed multiple transcription start sites for both mGABPalpha and mATPsynCF6 mRNAs that mapped near the published cDNA 5' ends. Sequence analysis identified several binding sites upstream of the GABPalpha cDNA sequence including sites for GABP (-86, -104, -169, -257, and -994), YY1 (-57), Sp1 (-242 and -226), and NRF1 (-5). No 'TATA' motif was identified near either the GABPalpha or ATPsynCF6 transcription start sites. The human and mouse promoters retain significant sequence identity including binding sites for several tissue-specific transcription factors. Transient transfection assays using Luciferase reporter constructs containing the intergenic region and flanking sequences confirmed that this region of DNA promotes transcription in both directions.
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Affiliation(s)
- Y Chinenov
- Department of Biochemistry, University of Missouri at Columbia, MO, Columbia 65212, USA
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31
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Mavrothalassitis G, Ghysdael J. Proteins of the ETS family with transcriptional repressor activity. Oncogene 2000; 19:6524-32. [PMID: 11175368 DOI: 10.1038/sj.onc.1204045] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
ETS proteins form one of the largest families of signal-dependent transcriptional regulators, mediating cellular proliferation, differentiation and tumorigenesis. Most of the known ETS proteins have been shown to activate transcription. However, four ETS proteins (YAN, ERF, NET and TEL) can act as transcriptional repressors. In three cases (ERF, NET and TEL) distinct repression domains have been identified and there are indications that NET and TEL may mediate transcription via Histone Deacetylase recruitment. All four proteins appear to be regulated by MAPKs, though for YAN and ERF this regulation seems to be restricted to ERKs. YAN, ERF and TEL have been implicated in cellular proliferation although there are indications suggesting a possible involvement of YAN and TEL in differentiation as well. Other ETS-domain proteins have been shown to repress transcription in a context specific manner, and there are suggestions that the ETS DNA-binding domain may act as a transcriptional repressor. Transcriptional repression by ETS domain proteins adds an other level in the orchestrated regulation by this diverse family of transcription factors that often recognize similar if not identical binding sites on DNA and are believed to regulate critical genes in a variety of biological processes. Definitive assessment of the importance of this novel regulatory level will require the identification of ETS proteins target genes and the further analysis of transcriptional control and biological function of these proteins in defined pathways.
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Affiliation(s)
- G Mavrothalassitis
- School of Medicine, University of Crete and IMBB-FORTH, Voutes, Heraklion, Crete 714-09, Greece
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Gong Q, Brown LJ, MacDonald MJ. Functional analysis of two promoters for the human mitochondrial glycerol phosphate dehydrogenase gene. J Biol Chem 2000; 275:38012-21. [PMID: 10954707 DOI: 10.1074/jbc.m004078200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mitochondrial glycerol phosphate dehydrogenase (mGPD) is abundant in the normal pancreatic insulin cell, but its level is lowered 50% by diabetes. To evaluate mGPD expression, we cloned and characterized the 5'-flanking region of the human mGPD gene. The gene has two alternative first exons and two promoters. The downstream promoter (B) is 10 times more active than the upstream promoter (A) in insulin-secreting cells (INS-1) and HeLa cells. Promoter B has higher activity in INS-1 than in non-beta cells. Deletion and mutation analysis suggested that a NRF-2 binding site at -94 to -101 and an E2F binding site at -208 to -215 are important regulatory cis elements in promoter B. Gel mobility shift assays indicated that the -94 to -101 region binds the NRF-2 protein. When INS-1 cells were maintained in the presence of high glucose (25 mm) for 7 days, mGPD was the only 1 of 6 enzyme activities lowered (53%). mGPD promoter B activity was reduced by 60% in INS-1 cells by the high glucose, but in HepG2 cells and HeLa cells, promoter B activity was unchanged or slightly increased. Deletion analysis indicated the glucose responsiveness was distributed across the region from -340 to -260 in promoter B. The results indicate that mGPD gene transcription in the beta cell is regulated differently from other cells and that decreased mGPD promoter B transcription is at least in part the cause of the decreased beta cell mGPD levels in diabetes.
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Affiliation(s)
- Q Gong
- Children's Diabetes Center, University of Wisconsin, Madison, Wisconsin 53706, USA
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33
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Marshall HE, Merchant K, Stamler JS. Nitrosation and oxidation in the regulation of gene expression. FASEB J 2000; 14:1889-900. [PMID: 11023973 DOI: 10.1096/fj.00.011rev] [Citation(s) in RCA: 310] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
A growing body of evidence suggests that the cellular response to oxidative and nitrosative stress is primarily regulated at the level of transcription. Posttranslational modification of transcription factors may provide a mechanism by which cells sense these redox changes. In bacteria, for example, OxyR senses redox-related changes via oxidation or nitrosylation of a free thiol in the DNA binding region. This mode of regulation may serve as a paradigm for redox-sensing by eukaryotic transcription factors as most-including NF-kappaB, AP-1, and p53-contain reactive thiols in their DNA binding regions, the modification of which alters binding in vitro. Several of these transcription factors have been found to be sensitive to both reactive oxygen species and nitric oxide-related species in vivo. It remains entirely unclear, however, if oxidation or nitrosylation of eukaryotic transcription factors is an important mode of regulation, or whether transcriptional activating pathways are principally controlled at other redox-sensitive levels.-Marshall, H. E., Merchant, K., Stamler, J. S. Nitrosation and oxidation in the regulation of gene expression.
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Affiliation(s)
- H E Marshall
- Howard Hughes Medical Institute, Departments of Medicine and Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
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34
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Sen CK. Cellular thiols and redox-regulated signal transduction. CURRENT TOPICS IN CELLULAR REGULATION 2000; 36:1-30. [PMID: 10842745 DOI: 10.1016/s0070-2137(01)80001-7] [Citation(s) in RCA: 172] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In contrast to the conventional notion that reactive oxygen is mostly a trigger for oxidative damage of biological structures, now we know that low physiologically relevant concentrations of ROS can regulate a variety of key molecular mechanisms that may be linked with important cell functions (Fig. 4). Redox-based regulation of gene expression has emerged as a fundamental regulatory mechanism in cell biology. Several proteins, with apparent redox-sensing activity, have been described. Electron flow through side-chain functional CH2-SH groups of conserved cysteinyl residues in these proteins account for the redox-sensing properties. Protein thiol groups with high thiol-disulfide oxidation potentials are likely to be redox-sensitive. The ubiquitous endogenous thiols thioredoxin and glutathione are of central importance in redox signaling. Signals are transduced from the cell surface to the nucleus through phosphorylation and dephosphorylation chain reactions of cellular proteins at tyrosine and serine/threonine. Protein phosphorylation, one of the most fundamental mediators of cell signaling, is redox-sensitive. DNA-binding proteins are involved in the regulation of cellular processes such as replication, recombination, viral integration and transcription. Several studies show that the interaction of certain transcription regulatory proteins with their respective cognate DNA sites is also redox-regulated. Changes in the concentration of Ca2+i control a wide variety of cellular functions, including transcription and gene expression; Ca(2+)-driven protein phosphorylation and proteolytic processing of proteins are two major intracellular events that are implicated in signal transduction from the cell surface to the nucleus. Intracellular calcium homeostasis is regulated by the redox state of cellular thiols, and it is evident that cell calcium may play a critical role in the activation of the redox-sensitive transcription factor NF-kappa B. Among the several thiol agents tested for their efficacy in modulating cellular redox status, N-acetyl-L-cysteine and alpha-lipoic acid hold most promise for human use. A strong therapeutic potential of strategies that would modulate the cellular thioredoxin system has been also evident.
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Affiliation(s)
- C K Sen
- Department of Molecular and Cell Biology, University of California Berkeley 94720, USA
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Aurrekoetxea-Hernández K, Buetti E. Synergistic action of GA-binding protein and glucocorticoid receptor in transcription from the mouse mammary tumor virus promoter. J Virol 2000; 74:4988-98. [PMID: 10799572 PMCID: PMC110850 DOI: 10.1128/jvi.74.11.4988-4998.2000] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
B lymphocytes are among the first cells to be infected by mouse mammary tumor virus (MMTV), and they play a crucial role in its life cycle. To study transcriptional regulation of MMTV in B cells, we have analyzed two areas of the long terminal repeat (LTR) next to the glucocorticoid receptor binding site, fp1 (at position -139 to -146 from the cap site) and fp2 (at -157 to -164). Both showed B-cell-specific protection in DNase I in vitro footprinting assays and contain binding sites for Ets transcription factors, a large family of proteins involved in cell proliferation and differentiation and oncogenic transformation. In gel retardation assays, fp1 and fp2 bound the heterodimeric Ets factor GA-binding protein (GABP) present in B-cell nuclear extracts, which was identified by various criteria: formation of dimers and tetramers, sensitivity to pro-oxidant conditions, inhibition of binding by specific antisera, and comigration of complexes with those formed by recombinant GABP. Mutations which prevented complex formation in vitro abolished glucocorticoid-stimulated transcription from an MMTV LTR linked to a reporter gene in transiently transfected B-cell lines, whereas they did not affect the basal level. Exogenously expressed GABP resulted in an increased level of hormone response of the LTR reporter plasmid and produced a synergistic effect with the coexpressed glucocorticoid receptor, indicating cooperation between the two. This is the first example of GABP cooperation with a steroid receptor, providing the opportunity for studying the integration of their intracellular signaling pathways.
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36
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Chinenov Y, Henzl M, Martin ME. The alpha and beta subunits of the GA-binding protein form a stable heterodimer in solution. Revised model of heterotetrameric complex assembly. J Biol Chem 2000; 275:7749-56. [PMID: 10713087 DOI: 10.1074/jbc.275.11.7749] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
We have studied the assembly of GA-binding protein (GABP) in solution and established the role of DNA in the assembly of the transcriptionally active GABPalpha(2)beta(2) heterotetrameric complex. GABP binds DNA containing a single PEA3/Ets-binding site (PEA3/EBS) exclusively as the alphabeta heterodimer complex, but readily binds as the GABPalpha(2)beta(2) heterotetramer complex on DNA containing two PEA3/EBSs. Positioning of the PEA3/EBSs on the same face of the DNA helix stabilizes heterotetramer complex binding. These observations suggest that GABPalphabeta heterodimers are the predominant molecular species in solution and that DNA containing two PEA3/EBSs promotes formation of the GABPalpha(2)beta(2) heterotetrameric complex. We analyzed the assembly of GABPalpha(2)beta(2) heteromeric complexes in solution by analytical ultracentrifugation. GABPalpha exists as a monomer in solution while GABPbeta exists in a monomer-dimer equilibrium (K(d) = 1.8 +/- 0.27 microM). In equimolar mixtures of the two subunits, GABPalpha and GABPbeta formed a stable heterodimer, with no heterotetramer complex detected. Thus, GABP exists in solution as the heterodimer previously shown to be a weak transcriptional activator. Assembly of the transcriptionally active GABPalpha(2)beta(2) heterotetramer complex requires the presence of specific DNA containing at least two PEA3/EBSs.
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Affiliation(s)
- Y Chinenov
- Department of Biochemistry, University of Missouri at Columbia, Columbia, Missouri 65212, USA
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37
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Guo A, Nie F, Wong-Riley M. Human nuclear respiratory factor 2 alpha subunit cDNA: isolation, subcloning, sequencing, and in situ hybridization of transcripts in normal and monocularly deprived macaque visual system. J Comp Neurol 2000; 417:221-32. [PMID: 10660899 DOI: 10.1002/(sici)1096-9861(20000207)417:2<221::aid-cne7>3.0.co;2-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Nuclear respiratory factor 2 (NRF-2) has been shown to contribute to the transcriptional regulation of a number of subunits of respiratory chain enzymes, including cytochrome c oxidase (CO). Our recent study demonstrated a parallel distribution of the alpha subunit proteins of NRF-2 (NRF-2 alpha) with CO in the monkey striate cortex, and that it can be regulated by neuronal activity. To determine whether this regulation is at the transcriptional level, the present study examined the expression of NRF-2 alpha mRNA in normal and monocularly deprived adult monkeys. A partial NRF-2 alpha cDNA was isolated from a human brain cDNA library. Sequence analysis revealed that it shared 99% identity with the published sequence from human HeLa cells. Riboprobes of NRF-2 alpha was generated and labeled with digoxigenin-11-UTP for in situ hybridization. The expression pattern of NRF-2 alpha mRNA in the normal striate cortex paralleled that of CO activity. It was highly expressed in layers IVC and VI, which contained high levels of CO, and more densely expressed in puffs of layers II and III than in interpuffs. In monkeys monocularly treated with tetrodotoxin for 1 day to 2 weeks, both NRF-2 alpha expression and CO activity were reduced in deprived ocular dominance columns of the visual cortex and in deprived layers of the lateral geniculate nucleus. These data indicate that, in the normal and visually deprived adult monkeys, NRF-2 alpha is regulated by neuronal activity at the transcriptional level.
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Affiliation(s)
- A Guo
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee 53226, USA
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38
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The Effects of Bioenergetic Stress and Redox Balance on the Expression of Genes Critical to Mitochondrial Function. ACTA ACUST UNITED AC 2000. [DOI: 10.1016/s1568-1254(00)80017-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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39
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Abstract
Mitochondria are the major ATP producer of the mammalian cell. Moreover, mitochondria are also the main intracellular source and target of reactive oxygen species (ROS) that are continually generated as by-products of aerobic metabolism in human cells. A low level of ROS generated from the respiratory chain was recently proposed to take part in the signaling from mitochondria to the nucleus. Several structural characteristics of mitochondria and the mitochondrial genome enable them to sense and respond to extracellular and intracellular signals or stresses in order to sustain the life of the cell. It has been established that mitochondrial respiratory function declines with age, and that defects in the respiratory chain increase the production of ROS and free radicals in mitochondria. Within a certain concentration range, ROS may induce stress responses of the cell by altering the expression of a number of genes in order to uphold energy metabolism to rescue the cell. However, beyond this threshold, ROS may elicit apoptosis by induction of mitochondrial membrane permeability transition and release of cytochrome c. Intensive research in the past few years has established that mitochondria play a pivotal role in the early phase of apoptosis in mammalian cells. In this article, the role of mitochondria in the determination of life and death of the cell is reviewed on the basis of recent findings gathered from this and other laboratories.
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Affiliation(s)
- H C Lee
- Department of Biochemistry and Center for Cellular and Molecular Biology, National Yang-Ming University, Taipei, Taiwan, Republic of China
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40
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Miranda S, Foncea R, Guerrero J, Leighton F. Oxidative stress and upregulation of mitochondrial biogenesis genes in mitochondrial DNA-depleted HeLa cells. Biochem Biophys Res Commun 1999; 258:44-9. [PMID: 10222232 DOI: 10.1006/bbrc.1999.0580] [Citation(s) in RCA: 131] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The signaling mechanism through which deficitary mitochondrial function would activate nuclear genes required for mitochondrial biogenesis, has not been established. To explore the hypothesis that reactive oxygen species (ROS), a mitochondrial product, constitute part of the mitochondria-nuclei signaling pathway, we obtained HeLa cells depleted of mitochondrial DNA (rho0 cells) through exposure to ethidium bromide. We found evidences of oxidative stress in rho0 cells, employing a fluorescent probe and measuring NF-kappaB activation. Nuclear Respiratory Factor-1 (NRF-1) and Mitochondrial Transcription Factor A (Tfam) mRNA were measured by RT-PCR. For both transcription factors, rho0 cells revealed significantly higher levels of mRNA. These results support several hypothesis: that endogenous ROS enhance the expression of nuclear mitochondrial biogenesis genes NRF-1 and Tfam; that DNA deprived mitochondria lead to cellular oxidative stress, probably because of incomplete biogenesis of the mitochondrial electron transport chain, and consequently, that ROS are part of a mitochondria-nuclei regulatory signaling pathway.
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Affiliation(s)
- S Miranda
- Departamento de Biología Celular y Molecular, Pontificia Universidad Católica de Chile, Casilla, Santiago, 114-D, Chile
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41
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Abstract
Extracellular stimuli elicit a variety of responses, such as cell proliferation and differentiation, through the cellular signalling system. Binding of growth factors to the respective receptor leads to the activation of receptor tyrosine kinases, which in turn stimulate downstream signalling systems such as mitogen-activated protein (MAP) kinases, phospholipase Cgamma (PLCgamma) and phosphatidylinositol 3-kinase. These biochemical reactions finally reach the nucleus, resulting in gene expression mediated by the activation of several transcription factors. Recent studies have revealed that cellular signalling pathways are regulated by the intracellular redox state. Generation of reactive oxygen species (ROS), such as H2O2, leads to the activation of protein tyrosine kinases followed by the stimulation of downstream signalling systems including MAP kinase and PLCgamma. The activation of PLCgamma by oxidative radical stress elevates the cellular Ca2+ levels by flux from the intracellular Ca2+ pool and from the extracellular space. Such reactions in the upstream signalling cascade, in concert, result in the activation of several transcription factors. On the other hand, reductants generally suppress the upstream signalling cascade resulting in the suppression of transcription factors. However, it is well known that cysteine residues in a reduced state are essential for the activity of many transcription factors. In fact, in vitro, oxidation of NFkappaB results in its activation, whereas reductants promote its activity. Thus, cellular signalling pathways are generally subjected to dual redox regulation in which redox has opposite effects on upstream signalling systems and downstream transcription factors. Not only are the cellular signalling pathways subjected to redox regulation, but also the signalling systems regulate the cellular redox state. When cells are activated by extracellular stimuli, the cells produce ROS, which in turn stimulate other cellular signalling pathways, indicating that ROS act as second messengers. It is thus evident that there is cross talk between the cellular signalling system and the cellular redox state. Cell death and life also are subjected to such dual redox regulation and cross talk. Death signals induce apoptosis through the activation of caspases in the cells. Oxidative radical stress induces the activation of caspases, whereas the oxidation of caspases results in their inactivation. Furthermore, some cell-death signals induce the production of ROS in the cells, and the ROS produced in turn stimulate the cell-death machinery. All this evidence shows that the cell's fate is determined by cross talk between the cellular signalling pathways and the cellular redox state through a complicated regulation mechanism.
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Affiliation(s)
- H Kamata
- Department of Life Science, Faculty of Science, Himeji Institute of Technology, Hyogo, Japan.
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42
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Rumsey WL, Abbott B, Bertelsen D, Mallamaci M, Hagan K, Nelson D, Erecinska M. Adaptation to hypoxia alters energy metabolism in rat heart. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:H71-80. [PMID: 9887019 DOI: 10.1152/ajpheart.1999.276.1.h71] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study characterized metabolic changes in the heart associated with long-term exposure to hypoxia, a potent stimulus for pulmonary hypertension and right ventricular hypertrophy. When anesthetized rats adapted to chronic hypoxia spontaneously respired room air, their mean right intraventricular peak systolic pressure (RVSP) was twice that in normal control animals with the same arterial PO2. RVSP was linearly related to right ventricular mass (r = 0.78). Oxidative capacity (O2 consumption) of homogenates of right and left ventricles from both groups of rats was measured with one of the following substrates: pyruvate, glutamate, acetate, and palmitoyl-L-carnitine. Oxidation of all substrates was significantly greater in the left than in the right ventricle in normal rats but not in hypoxia-adapted animals, where it was the same, within the experimental error. O2 consumption by the left ventricle was greater in control than in experimental rats, but right ventricular O2 consumption was similar in the two groups. Maximal reaction velocity of cytochrome-c oxidase was about the same in the two ventricles, and there were no significant differences between control and hypoxia-adapted animals. HPLC analyses showed significantly higher aspartate levels and aspartate-to glutamate concentration ratios in both ventricles of hypoxic rats than in corresponding tissues from controls, indicative of a decreased flux through the malate-aspartate shuttle under conditions of O2 limitation. Myocardial glutamine levels were lower in hypoxic rats, and glutamine-to-glutamate concentration ratios decreased, although primarily in the pressure-overloaded right ventricle. These findings indicate that normal energy metabolism in the left ventricle differs from that in the right and that the differences, particularly those of amino acid metabolism, are markedly influenced by chronic exposure to hypoxia.
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Affiliation(s)
- W L Rumsey
- Zeneca Pharmaceuticals, Wilmington, Delaware 19850, USA
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43
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Grossman LI, Seelan RS, Jaradat SA. Transcriptional regulation of mammalian cytochrome c oxidase genes. Electrophoresis 1998; 19:1254-9. [PMID: 9694260 DOI: 10.1002/elps.1150190805] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The cytochrome c oxidase (COX) holoenzyme is a 13-subunit complex that carries out the terminal step in the electron transport chain. Three of the subunits, which contain the electron transfer function, are coded by mitochondrial DNA and the other ten subunits by nuclear DNA. Since the holoenzyme contains equivalent amounts of each subunit, we and others have examined transcriptional regulation of COX nuclear subunits to explore whether there is a common basis for co-regulation. Each gene is seen to have a unique pattern of recognition by regulatory factors; although some factors bind to more than one gene, not all COX genes seem to be regulated by the same set of factors. Current information about the COX promoters that have been examined is summarized, and the relation of promoter regulation to coordinate gene expression is discussed.
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Affiliation(s)
- L I Grossman
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA.
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44
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Abstract
Oxidation-reduction (redox) based regulation of signal transduction and gene expression is emerging as a fundamental regulatory mechanism in cell biology. Electron flow through side chain functional CH2-SH groups of conserved cysteinyl residues in proteins account for their redox-sensing properties. Because in most intracellular proteins thiol groups are strongly "buffered" against oxidation by the highly reduced environment inside the cell, only accessible protein thiol groups with high thiol-disulfide oxidation potentials are likely to be redox sensitive. The list of redox-sensitive signal transduction pathways is steadily growing, and current information suggests that manipulation of the cell redox state may prove to be an important strategy for the management of AIDS and some forms of cancer. The endogenous thioredoxin and glutathione systems are of central importance in redox signaling. Among the thiol agents tested for their efficacy to modulate cellular redox status, N-acetyl-L-cysteine (NAC) and alpha-lipoic acid hold promise for clinical use. A unique advantage of lipoate is that it is able to utilize cellular reducing equivalents, and thus it harnesses the metabolic power of the cell to continuously regenerate its reductive vicinal dithiol form. Because lipoate can be readily recycled in the cell, it has an advantage over N-acetyl-L-cysteine on a concentration:effect basis. Our current knowledge of redox regulated signal transduction has led to the unfolding of the remarkable therapeutic potential of cellular thiol modulating agents.
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Affiliation(s)
- C K Sen
- Department of Molecular and Cell Biology, University of California, Berkeley 94720-3200, USA.
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45
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Pan J, Xia L, McEver RP. Comparison of promoters for the murine and human P-selectin genes suggests species-specific and conserved mechanisms for transcriptional regulation in endothelial cells. J Biol Chem 1998; 273:10058-67. [PMID: 9545353 DOI: 10.1074/jbc.273.16.10058] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
P-selectin, an adhesion receptor for leukocytes, is constitutively expressed in megakaryocytes and endothelial cells. Tumor necrosis factor-alpha (TNF-alpha) or lipopolysaccharide (LPS) increases synthesis of P-selectin in murine but not in human endothelial cells. To identify potential species-specific and conserved mechanisms for regulation of expression of P-selectin, we cloned the 5'-flanking region of the murine P-selectin gene and compared its features with those previously reported for the human gene. The murine and human genes shared conserved Stat-like, Hox, Ets, GATA, and GT-IIC elements. In the murine gene, a conserved GATA element bound to GATA-2 and functioned as a positive regulatory element, whereas a conserved Ets element bound to GA-binding protein and functioned as a negative regulatory element. Significantly, the murine P-selectin gene had several features not found in the human gene. These included an insertion from -987 to -649 that contained tandem GATA and tandem AP1-like sequences, which resembled enhancers in beta-globin locus control regions. Both tandem elements bound specifically to nuclear proteins. The murine gene lacked the unique kappaB site specific for p50 or p52 homodimers found in the human gene. Instead, it contained two tandem kappaB elements and a variant activating transcription factor/cAMP response element site, which closely resembled sites in the E-selectin gene that are required for TNF-alpha- or LPS-inducible expression. TNF-alpha or LPS augmented expression of a reporter gene driven by the murine, but not the human, P-selectin promoter in transfected endothelial cells. Deletional analysis of the murine 5'-flanking region revealed several sequences that were required for either constitutive or inducible expression. These data suggest that both species-specific and conserved mechanisms regulate transcription of the human and murine P-selectin genes.
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Affiliation(s)
- J Pan
- Department of Medicine, W. K. Warren Medical Research Institute, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
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46
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Chinenov Y, Schmidt T, Yang XY, Martin ME. Identification of redox-sensitive cysteines in GA-binding protein-alpha that regulate DNA binding and heterodimerization. J Biol Chem 1998; 273:6203-9. [PMID: 9497343 DOI: 10.1074/jbc.273.11.6203] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The transcription factor GA-binding protein (GABP) is composed of two subunits, GABPalpha and GABPbeta. The DNA-binding subunit, GABPalpha, is a member of the Ets family of transcription factors, characterized by the conserved Ets-domain that mediates DNA binding and associates with GABPbeta, which lacks a discernible DNA binding domain, through ankyrin repeats in the NH2 terminus of GABPbeta. We previously demonstrated that GABP is subject to redox regulation in vitro and in vivo through four COOH-terminal cysteines in GABPalpha. To determine the roles of individual cysteines in GABP redox regulation, we generated a series of serine substitution mutants by site-directed mutagenesis and identified three redox-sensitive cysteine residues in GABPalpha (Cys388, Cys401, and Cys421). Sulfhydryl modification of Cys388 and Cys401 inhibits DNA binding by GABPalpha, whereas, modification of Cys421 has no effect on GABPalpha DNA binding but inhibits dimerization with GABPbeta. The positions of Cys388 and Cys401 within the known Ets-domain structure suggest two very different mechanisms for redox regulation of DNA binding. Sulfhydryl modification of Cys388 could directly interfere with DNA binding or might alter the positioning of the DNA-binding helix 3. Modification of Cys401 may inhibit DNA binding through stabilization of an inhibitory helix similar to that described in the Ets-1 protein. Thus, GABP is regulated through at least two redox-sensitive activities, DNA binding and heterodimerization.
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Affiliation(s)
- Y Chinenov
- Department of Biochemistry, University of Missouri at Columbia, Columbia, Missouri 65212, USA
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A Proteasome Inhibitor, an Antioxidant, or a Salicylate, but not a Glucocorticoid, Blocks Constitutive and Cytokine-Inducible Expression of P-Selectin in Human Endothelial Cells. Blood 1998. [DOI: 10.1182/blood.v91.5.1625.1625_1625_1632] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Proteasome inhibitors, antioxidants, salicylates, or glucocorticoids block the cytokine-induced expression of the endothelial cell adhesion molecules E-selectin, vascular cell adhesion molecule-1, and intercellular adhesion molecule-1. These pharmacological agents have been assumed to inhibit the expression of adhesion molecules primarily by blocking activation of the transcription factor NF-κB. We found that the proteasome inhibitor ALLN, the antioxidant PDTC, or sodium salicylate, but not the glucocorticoid dexamethasone, inhibited both the constitutive and the interleukin-4– or oncostatin M–induced expression of the adhesion molecule P-selectin in human endothelial cells. ALLN, PDTC, or sodium salicylate decreased P-selectin expression without a detectable requirement for inhibition of NF-κB activation or for an intact κB element in the P-selectin gene. These results extend the potential anti-inflammatory utility of such drugs to inhibition of P-selectin expression and suggest that they have important actions that do not involve the NF-κB system.
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A Proteasome Inhibitor, an Antioxidant, or a Salicylate, but not a Glucocorticoid, Blocks Constitutive and Cytokine-Inducible Expression of P-Selectin in Human Endothelial Cells. Blood 1998. [DOI: 10.1182/blood.v91.5.1625] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
AbstractProteasome inhibitors, antioxidants, salicylates, or glucocorticoids block the cytokine-induced expression of the endothelial cell adhesion molecules E-selectin, vascular cell adhesion molecule-1, and intercellular adhesion molecule-1. These pharmacological agents have been assumed to inhibit the expression of adhesion molecules primarily by blocking activation of the transcription factor NF-κB. We found that the proteasome inhibitor ALLN, the antioxidant PDTC, or sodium salicylate, but not the glucocorticoid dexamethasone, inhibited both the constitutive and the interleukin-4– or oncostatin M–induced expression of the adhesion molecule P-selectin in human endothelial cells. ALLN, PDTC, or sodium salicylate decreased P-selectin expression without a detectable requirement for inhibition of NF-κB activation or for an intact κB element in the P-selectin gene. These results extend the potential anti-inflammatory utility of such drugs to inhibition of P-selectin expression and suggest that they have important actions that do not involve the NF-κB system.
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Yu M, Yang XY, Schmidt T, Chinenov Y, Wang R, Martin ME. GA-binding protein-dependent transcription initiator elements. Effect of helical spacing between polyomavirus enhancer a factor 3(PEA3)/Ets-binding sites on initiator activity. J Biol Chem 1997; 272:29060-7. [PMID: 9360980 DOI: 10.1074/jbc.272.46.29060] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Many eukaryotic RNA polymerase II promoters contain initiator elements which direct accurate transcription in a TATA-independent manner. The PEA3/Ets-binding site (PEA3/EBS) is a common enhancer element in eukaryotic genes and is also found near the transcriptional start sites of many TATA-less promoters. We demonstrate that two PEA3/EBSs driving expression of the luciferase reporter gene, function as a minimal transcriptional initiator element. Maximal levels of transcription was achieved when two PEA3/EBSs, in either orientation, were located on the same face of the DNA helix, and the sites could be separated by up to three helical turns. In vitro transcription start sites directed by PEA3/EBS elements were clustered on either side of the upstream PEA3/EBS and were abolished by immunodepletion of GA-binding protein (GABP) from FM3A cell nuclear extracts. In vivo, co-transfection of GABPalpha and GABPbeta expression vectors enhanced reporter gene expression driven from PEA3/EBS initiator elements. Like other initiator elements, the PEA3/EBS elements were activated synergistically by upstream Sp1-binding sites. Thus, our results establish GABP as both a transcriptional activator factor and as an initiator factor.
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Affiliation(s)
- M Yu
- Department of Biochemistry, University of Missouri at Columbia, Columbia, Missouri 65212, USA
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Breen GA, Jordan EM. Regulation of the nuclear gene that encodes the alpha-subunit of the mitochondrial F0F1-ATP synthase complex. Activation by upstream stimulatory factor 2. J Biol Chem 1997; 272:10538-42. [PMID: 9099698 DOI: 10.1074/jbc.272.16.10538] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
We have previously identified several positive cis-acting regulatory regions in the promoters of the bovine and human nuclear-encoded mitochondrial F0F1-ATP synthase alpha-subunit genes (ATPA). One of these cis-acting regions contains the sequence 5'-CACGTG-3' (an E-box), to which a number of transcription factors containing a basic helix-loop-helix motif can bind. This E-box element is required for maximum activity of the ATPA promoter in HeLa cells. The present study identifies the human transcription factor, upstream stimulatory factor 2 (USF2), as a nuclear factor that binds to the ATPA E-box and demonstrates that USF2 plays a critical role in the activation of the ATPA gene in vivo. Evidence includes the following. Antiserum directed against USF2 recognized factors present in HeLa nuclear extracts that interact with the ATPA promoter in mobility shift assays. Wild-type USF2 proteins synthesized from expression vectors trans-activated the ATPA promoter through the E-box, whereas truncated USF2 proteins devoid of the amino-terminal activation domains did not. Importantly, expression of a dominant-negative mutant of USF2 lacking the basic DNA binding domain but able to dimerize with endogenous USF proteins significantly reduced the level of activation of the ATPA promoter caused by ectopically coexpressed USF2, demonstrating the importance of endogenous USF2 in activation of the ATPA gene.
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Affiliation(s)
- G A Breen
- Department of Molecular and Cell Biology, The University of Texas at Dallas, Richardson, Texas 75083-0688, USA.
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