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Morris DR, Levenson CW. Zinc regulation of transcriptional activity during retinoic acid-induced neuronal differentiation. J Nutr Biochem 2013; 24:1940-4. [PMID: 24029070 DOI: 10.1016/j.jnutbio.2013.06.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 05/30/2013] [Accepted: 06/07/2013] [Indexed: 12/13/2022]
Abstract
Zinc deficiency impairs the proliferation and differentiation of stem cells in the central nervous system that participate in neurogenesis. To examine the molecular mechanisms responsible for the role of this essential nutrient in neuronal precursor cells and neuronal differentiation, we identified zinc-dependent changes in the DNA-binding activity of zinc finger proteins and other transcription factors in proliferating human Ntera-2 neuronal precursor cells undergoing retinoic acid-stimulated differentiation into a neuronal phenotype. We found that zinc deficiency altered binding activity of 28 transcription factors including retinoid X receptor (RXR) known to participate in neuronal differentiation. Alterations in zinc finger transcription factor activity were not simply the result of removal of zinc from these proteins during zinc deficiency, as the activity of other zinc-binding transcription factors such as the glucocorticoid receptor was increased by as much as twofold over zinc-adequate conditions, and nonzinc-binding transcription factors such as nuclear factor-1 and heat shock transcription factor-1 were increased by as much as fourfold over control. Western analysis did not detect significant decreases in total RXR protein abundance in neuronal precursors, suggesting that the decrease in DNA-binding activity was not simply the result of a reduction in RXR levels in neuronal precursor cells. Rather, use of a reporter gene construct containing retinoic acid response elements upstream from a luciferase coding sequence revealed that zinc deficiency results in decreased transcriptional activity of RXR and reductions in retinoic acid-mediated gene transcription during neuronal differentiation. These results show that zinc deficiency has implications for both developmental and adult neurogenesis.
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Affiliation(s)
- Deborah R Morris
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL 32306-4300, USA
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52
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Calamini B, Morimoto RI. Protein homeostasis as a therapeutic target for diseases of protein conformation. Curr Top Med Chem 2013; 12:2623-40. [PMID: 23339312 DOI: 10.2174/1568026611212220014] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 09/26/2012] [Accepted: 09/26/2012] [Indexed: 12/12/2022]
Abstract
Protein misfolding and aggregation are widely implicated in an increasing number of human diseases providing for new therapeutic opportunities targeting protein homeostasis (proteostasis). The cellular response to proteotoxicity is highly regulated by stress signaling pathways, molecular chaperones, transport and clearance machineries that function as a proteostasis network (PN) to protect the stability and functional properties of the proteome. Consequently, the PN is essential at the cellular and organismal level for development and lifespan. However, when challenged during aging, stress, and disease, the folding and clearance machineries can become compromised leading to both gain-of-function and loss-of-function proteinopathies. Here, we assess the role of small molecules that activate the heat shock response, the unfolded protein response, and clearance mechanisms to increase PN capacity and protect cellular proteostasis against proteotoxicity. We propose that this strategy to enhance cell stress pathways and chaperone activity establishes a cytoprotective state against misfolding and/or aggregation and represents a promising therapeutic avenue to prevent the cellular damage associated with the variety of protein conformational diseases.
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Affiliation(s)
- Barbara Calamini
- Department of Neurobiology and Center for Drug Discovery, Duke University, Durham, NC, USA
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53
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Bueno MTD, Richard S. SUMOylation negatively modulates target gene occupancy of the KDM5B, a histone lysine demethylase. Epigenetics 2013; 8:1162-75. [PMID: 23970103 DOI: 10.4161/epi.26112] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The histone lysine demethylase KDM5B plays key roles in gene repression by demethylating trimethylated lysine 4 of histone H3 (H3K4me3), a modification commonly found at the promoter region of actively transcribed genes. KDM5B is known to regulate the expression of genes involved in cell cycle progression; however, little is known about the post-translational modifications that regulate KDM5B. Herein, we report that KDM5B is SUMOylated at lysine residues 242 and 278 and that the ectopic expression of the hPC2 SUMO E3 ligase enhances this SUMOylation. Interestingly, the levels of KDM5B and its SUMOylated forms are regulated during the cell cycle. KDM5B is modulated by RNF4, an E3 ubiquitin ligase that targets SUMO-modified proteins to proteasomal degradation. Digital gene expression analyses showed that cells expressing the SUMOylation-deficient KDM5B harbor repressed mRNA expression profiles of cell cycle and DNA repair genes. Chromatin immunoprecipitations confirmed some of these genes as KDM5B targets, as they displayed reduced H3K4me3 levels in cells ectopically expressing KDM5B. We propose that SUMOylation by hPC2 regulates the activity of KDM5B.
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Affiliation(s)
- Murilo T D Bueno
- Terry Fox Molecular Oncology Group and the Bloomfield Center for Research on Aging; Sir Mortimer B Davis Jewish General Hospital; Lady Davis Institute for Medical Research; Montréal, QC Canada; Department of Medicine and Oncology; McGill University; Montréal, QC Canada
| | - Stéphane Richard
- Terry Fox Molecular Oncology Group and the Bloomfield Center for Research on Aging; Sir Mortimer B Davis Jewish General Hospital; Lady Davis Institute for Medical Research; Montréal, QC Canada; Department of Medicine and Oncology; McGill University; Montréal, QC Canada
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54
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Silveirinha V, Stephens GJ, Cimarosti H. Molecular targets underlying SUMO-mediated neuroprotection in brain ischemia. J Neurochem 2013; 127:580-91. [PMID: 23786482 DOI: 10.1111/jnc.12347] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 06/14/2013] [Accepted: 06/17/2013] [Indexed: 01/11/2023]
Abstract
SUMOylation (small ubiquitin-like modifier conjugation) is an important post-translational modification which is becoming increasingly implicated in the altered protein dynamics associated with brain ischemia. The function of SUMOylation in cells undergoing ischemic stress and the identity of small ubiquitin-like modifier (SUMO) targets remain in most cases unknown. However, the emerging consensus is that SUMOylation of certain proteins might be part of an endogenous neuroprotective response. This review brings together the current understanding of the underlying mechanisms and downstream effects of SUMOylation in brain ischemia, including processes such as autophagy, mitophagy and oxidative stress. We focus on recent advances and controversies regarding key central nervous system proteins, including those associated with the nucleus, cytoplasm and plasma membrane, such as glucose transporters (GLUT1, GLUT4), excitatory amino acid transporter 2 glutamate transporters, K+ channels (K2P1, Kv1.5, Kv2.1), GluK2 kainate receptors, mGluR8 glutamate receptors and CB1 cannabinoid receptors, which are reported to be SUMO-modified. A discussion of the roles of these molecular targets for SUMOylation could play following an ischemic event, particularly with respect to their potential neuroprotective impact in brain ischemia, is proposed.
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Affiliation(s)
- Vasco Silveirinha
- School of Pharmacy, Hopkins Building, University of Reading, Whiteknights, Reading, UK
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55
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Abstract
The heat shock response is a highly conserved primitive response that is essential for survival against a wide range of stresses, including extremes of temperature. Fever is a more recently evolved response, during which organisms raise their core body temperature and temporarily subject themselves to thermal stress in the face of infections. The present review documents studies showing the potential overlap between the febrile response and the heat shock response and how both activate the same common transcriptional programme (although with different magnitudes) including the stress-activated transcription factor, heat shock factor-1, to modify host defences in the context of infection, inflammation and injury. The review focuses primarily on how hyperthermia within the febrile range that often accompanies infections and inflammation acts as a biological response modifier and modifies innate immune responses. The characteristic 2-3 °C increase in core body temperature during fever activates and utilises elements of the heat shock response pathway to modify cytokine and chemokine gene expression, cellular signalling and immune cell mobilisation to sites of inflammation, infection and injury. Interestingly, typical proinflammatory agonists such as Toll-like receptor agonists modify the heat shock-induced transcriptional programme and expression of HSP genes following co-exposure to febrile range hyperthermia or heat shock, suggesting a complex reciprocal regulation between the inflammatory pathway and the heat shock response pathway.
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Affiliation(s)
- Ishwar S Singh
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA.
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56
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Function of the C. elegans T-box factor TBX-2 depends on SUMOylation. Cell Mol Life Sci 2013; 70:4157-68. [PMID: 23595631 PMCID: PMC3802552 DOI: 10.1007/s00018-013-1336-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Revised: 03/19/2013] [Accepted: 04/02/2013] [Indexed: 01/22/2023]
Abstract
T-box transcription factors are critical developmental regulators in all multi-cellular organisms, and altered T-box factor activity is associated with a variety of human congenital diseases and cancers. Despite the biological significance of T-box factors, their mechanism of action is not well understood. Here we examine whether SUMOylation affects the function of the C. elegans Tbx2 sub-family T-box factor TBX-2. We have previously shown that TBX-2 interacts with the E2 SUMO-conjugating enzyme UBC-9, and that loss of TBX-2 or UBC-9 produces identical defects in ABa-derived pharyngeal muscle development. We now show that TBX-2 is SUMOylated in mammalian cell assays, and that both UBC-9 interaction and SUMOylation depends on two SUMO consensus sites located in the T-box DNA binding domain and near the TBX-2 C-terminus, respectively. In co-transfection assays, a TBX-2:GAL4 fusion protein represses expression of a 5xGal4:tk:luciferase construct. However, this activity does not require SUMOylation, indicating SUMO is not generally required for TBX-2 repressor activity. In C. elegans, reducing SUMOylation enhances the phenotype of a temperature-sensitive tbx-2 mutant and results in ectopic expression of a gene normally repressed by TBX-2, demonstrating that SUMOylation is important for TBX-2 function in vivo. Finally, we show mammalian orthologs of TBX-2, Tbx2, and Tbx3, can also be SUMOylated, suggesting SUMOylation may be a conserved mechanism controlling T-box factor activity.
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57
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Deficient sumoylation of yeast 2-micron plasmid proteins Rep1 and Rep2 associated with their loss from the plasmid-partitioning locus and impaired plasmid inheritance. PLoS One 2013; 8:e60384. [PMID: 23555963 PMCID: PMC3610928 DOI: 10.1371/journal.pone.0060384] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Accepted: 02/26/2013] [Indexed: 11/19/2022] Open
Abstract
The 2-micron plasmid of the budding yeast Saccharomyces cerevisiae encodes copy-number amplification and partitioning systems that enable the plasmid to persist despite conferring no advantage to its host. Plasmid partitioning requires interaction of the plasmid Rep1 and Rep2 proteins with each other and with the plasmid-partitioning locus STB. Here we demonstrate that Rep1 stability is reduced in the absence of Rep2, and that both Rep proteins are sumoylated. Lysine-to-arginine substitutions in Rep1 and Rep2 that inhibited their sumoylation perturbed plasmid inheritance without affecting Rep protein stability or two-hybrid interaction between Rep1 and Rep2. One-hybrid and chromatin immunoprecipitation assays revealed that Rep1 was required for efficient retention of Rep2 at STB and that sumoylation-deficient mutants of Rep1 and Rep2 were impaired for association with STB. The normal co-localization of both Rep proteins with the punctate nuclear plasmid foci was also lost when Rep1 was sumoylation-deficient. The correlation of Rep protein sumoylation status with plasmid-partitioning locus association suggests a theme common to eukaryotic chromosome segregation proteins, sumoylated forms of which are found enriched at centromeres, and between the yeast 2-micron plasmid and viral episomes that depend on sumoylation of their maintenance proteins for persistence in their hosts.
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58
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Kim M, Chen Z, Shim MS, Lee MS, Kim JE, Kwon YE, Yoo TJ, Kim JY, Bang JY, Carlson BA, Seol JH, Hatfield DL, Lee BJ. SUMO modification of NZFP mediates transcriptional repression through TBP binding. Mol Cells 2013; 35:70-8. [PMID: 23269432 PMCID: PMC3887854 DOI: 10.1007/s10059-013-2281-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Revised: 11/16/2012] [Accepted: 11/19/2012] [Indexed: 01/27/2023] Open
Abstract
The negatively regulating zinc finger protein (NZFP) is an essential transcription repressor required for early development during gastrulation in Xenopus laevis. In this study, we found that NZFP interacts with the small ubiquitin-like modifier (SUMO) conjugation E2 enzyme, Ubc9, and contains three putative SUMO conjugation sites. Studies with NZFP mutants containing mutations at the putative SUMO conjugation sites showed that these sites were able to be modified independently with SUMO. NZFP was found to be localized in the same nuclear bodies with SUMO-1. However, sumoylation of NZFP did not play a role either in the translocation of NZFP into the nucleus or on nuclear body formation. While wild type NZFP showed significant transcriptional repression, SUMO-conjugation site mutants manifested a decrease in transcriptional repression activity which is reversely proportional to the amount of sumoylation. The sumoylation defective mutant lost its TBP binding activity, while wild type NZFP interacted with TBP and inhibited transcription complex formation. These results strongly suggest that the sumoylation of NZFP facilitates NZFP to bind to TBP and the NZFP/TBP complex then represses the transcription of the target gene by inhibiting basal transcription complex formation.
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Affiliation(s)
- Mijin Kim
- School of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, Seoul 151-742,
Korea
| | - Zifan Chen
- School of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, Seoul 151-742,
Korea
| | - Myoung Sup Shim
- School of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, Seoul 151-742,
Korea
| | - Myoung Sook Lee
- School of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, Seoul 151-742,
Korea
| | - Ji Eon Kim
- School of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, Seoul 151-742,
Korea
| | - Young Eun Kwon
- School of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, Seoul 151-742,
Korea
| | - Tack Jin Yoo
- School of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, Seoul 151-742,
Korea
| | - Jin Young Kim
- School of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, Seoul 151-742,
Korea
| | - Je Young Bang
- Interdisciplinary Program of Bioinformatics, Seoul National University, Seoul 151-742,
Korea
| | - Bradley A. Carlson
- Molecular Biology of Selenium Section, Laboratory of Cancer Prevention, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892,
USA
| | - Jae Hong Seol
- School of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, Seoul 151-742,
Korea
| | - Dolph L. Hatfield
- Molecular Biology of Selenium Section, Laboratory of Cancer Prevention, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892,
USA
| | - Byeong Jae Lee
- School of Biological Sciences, Institute of Molecular Biology and Genetics, Seoul National University, Seoul 151-742,
Korea
- Interdisciplinary Program of Bioinformatics, Seoul National University, Seoul 151-742,
Korea
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59
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Miller MJ, Scalf M, Rytz TC, Hubler SL, Smith LM, Vierstra RD. Quantitative proteomics reveals factors regulating RNA biology as dynamic targets of stress-induced SUMOylation in Arabidopsis. Mol Cell Proteomics 2012. [PMID: 23197790 DOI: 10.1074/mcp.m112.025056] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The stress-induced attachment of small ubiquitin-like modifier (SUMO) to a diverse collection of nuclear proteins regulating chromatin architecture, transcription, and RNA biology has been implicated in protecting plants and animals against numerous environmental challenges. In order to better understand stress-induced SUMOylation, we combined stringent purification of SUMO conjugates with isobaric tag for relative and absolute quantification mass spectrometry and an advanced method to adjust for sample-to-sample variation so as to study quantitatively the SUMOylation dynamics of intact Arabidopsis seedlings subjected to stress. Inspection of 172 SUMO substrates during and after heat shock (37 °C) revealed that stress mostly increases the abundance of existing conjugates, as opposed to modifying new targets. Some of the most robustly up-regulated targets participate in RNA processing and turnover and RNA-directed DNA modification, thus implicating SUMO as a regulator of the transcriptome during stress. Many of these targets were also strongly SUMOylated during ethanol and oxidative stress, suggesting that their modification is crucial for general stress tolerance. Collectively, our quantitative data emphasize the importance of SUMO to RNA-related processes protecting plants from adverse environments.
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Affiliation(s)
- Marcus J Miller
- Department of Genetics, 425-G Henry Mall, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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60
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Liu HW, Zhang J, Heine GF, Arora M, Gulcin Ozer H, Onti-Srinivasan R, Huang K, Parvin JD. Chromatin modification by SUMO-1 stimulates the promoters of translation machinery genes. Nucleic Acids Res 2012; 40:10172-86. [PMID: 22941651 PMCID: PMC3488252 DOI: 10.1093/nar/gks819] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
SUMOylation of transcription factors and chromatin proteins is in many cases a negative mark that recruits factors that repress gene expression. In this study, we determined the occupancy of Small Ubiquitin-like MOdifier (SUMO)-1 on chromatin in HeLa cells by use of chromatin affinity purification coupled with next-generation sequencing. We found SUMO-1 localization on chromatin was dynamic throughout the cell cycle. Surprisingly, we observed that from G1 through late S phase, but not during mitosis, SUMO-1 marks the chromatin just upstream of the transcription start site on many of the most active housekeeping genes, including genes encoding translation factors and ribosomal subunit proteins. Moreover, we found that SUMO-1 distribution on promoters was correlated with H3K4me3, another general chromatin activation mark. Depletion of SUMO-1 resulted in downregulation of the genes that were marked by SUMO-1 at their promoters during interphase, supporting the concept that the marking of promoters by SUMO-1 is associated with transcriptional activation of genes involved in ribosome biosynthesis and in the protein translation process.
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Affiliation(s)
- Hui-wen Liu
- The Department of Biomedical Informatics and the Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH 43210, USA
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61
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West JD, Wang Y, Morano KA. Small molecule activators of the heat shock response: chemical properties, molecular targets, and therapeutic promise. Chem Res Toxicol 2012; 25:2036-53. [PMID: 22799889 DOI: 10.1021/tx300264x] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
All cells have developed various mechanisms to respond and adapt to a variety of environmental challenges, including stresses that damage cellular proteins. One such response, the heat shock response (HSR), leads to the transcriptional activation of a family of molecular chaperone proteins that promote proper folding or clearance of damaged proteins within the cytosol. In addition to its role in protection against acute insults, the HSR also regulates lifespan and protects against protein misfolding that is associated with degenerative diseases of aging. As a result, identifying pharmacological regulators of the HSR has become an active area of research in recent years. Here, we review progress made in identifying small molecule activators of the HSR, what cellular targets these compounds interact with to drive response activation, and how such molecules may ultimately be employed to delay or reverse protein misfolding events that contribute to a number of diseases.
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Affiliation(s)
- James D West
- Biochemistry and Molecular Biology Program, Departments of Biology and Chemistry, The College of Wooster, Wooster, Ohio 44691, USA.
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62
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Ishihara K, Fatma N, Bhargavan B, Chhunchha B, Kubo E, Dey S, Takamura Y, Kumar A, Singh DP. Lens epithelium-derived growth factor deSumoylation by Sumo-specific protease-1 regulates its transcriptional activation of small heat shock protein and the cellular response. FEBS J 2012; 279:3048-70. [PMID: 22748127 DOI: 10.1111/j.1742-4658.2012.08686.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Lens epithelium-derived growth factor (LEDGF), a ubiquitously expressed nuclear protein, acts by interacting with DNA and protein and is involved in widely varying cellular functions. Despite its importance, the mechanism(s) that regulate naturally occurring LEDGF activity are unidentified. In the present study, we report that LEDGF is constitutively Sumoylated, and that the dynamical regulatory mechanism(s) (i.e. Sumoylation and deSumoylation) act as a molecular switch in modulating the DNA-binding and transcriptional activity of LEDGF with the functional consequences. Using bioinformatics analysis coupled with in vitro and in vivo Sumoylation assays, we found that lysine (K) 364 of LEDGF was Sumoylated, repressing its transcriptional activity. Conversely, mutation of K364 to arginine (R) or deSumoylation by small ubiquitin-like modifier (Sumo)-specific protease-1, a nuclear deSumoylase, enhanced the transactivation capacity of LEDGF and its cellular abundance. The enhancements were directly correlated with an increase in the DNA-binding activity and small heat shock protein transcription of LEDGF, whereas the process was reversed in cells overexpressing Sumo1. Interestingly, cells expressing Sumoylation-deficient pEGFP-K364R protein showed increased cellular survival compared to wild-type LEDGF protein. The findings provide insights into the regulation and regulatory functions of LEDGF in Sumoylation-dependent transcriptional control that may be essential for modifying the physiology of cells to maintain cellular homeostasis. These studies also provide new evidence of the important role of post-translational modification in controlling LEDGF function.
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Affiliation(s)
- Keiichi Ishihara
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, NE, USA
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63
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Schwede A, Kramer S, Carrington M. How do trypanosomes change gene expression in response to the environment? PROTOPLASMA 2012; 249:223-238. [PMID: 21594757 PMCID: PMC3305869 DOI: 10.1007/s00709-011-0282-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Accepted: 05/02/2011] [Indexed: 05/30/2023]
Abstract
All organisms are able to modulate gene expression in response to internal and external stimuli. Trypanosomes represent a group that diverged early during the radiation of eukaryotes and do not utilise regulated initiation of transcription by RNA polymerase II. Here, the mechanisms present in trypanosomes to alter gene expression in response to stress and change of host environment are discussed and contrasted with those operating in yeast and cultured mammalian cells.
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Affiliation(s)
- Angela Schwede
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW UK
| | - Susanne Kramer
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW UK
| | - Mark Carrington
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW UK
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64
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Truong K, Lee TD, Chen Y. Small ubiquitin-like modifier (SUMO) modification of E1 Cys domain inhibits E1 Cys domain enzymatic activity. J Biol Chem 2012; 287:15154-63. [PMID: 22403398 DOI: 10.1074/jbc.m112.353789] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Although it is well established that ubiquitin-like modifications are tightly regulated, it has been unclear how their E1 activities are controlled. In this study, we found that the SAE2 subunit of the small ubiquitin-like modifier (SUMO) E1 is autoSUMOylated at residue Lys-236, and SUMOylation was catalyzed by Ubc9 at several additional Lys residues surrounding the catalytic Cys-173 of SAE2. AutoSUMOylation of SAE2 did not affect SUMO adenylation or formation of E1·SUMO thioester, but did significantly inhibit the transfer of SUMO from E1 to E2 and overall SUMO conjugations to target proteins due to the altered interaction between E1 and E2. Upon heat shock, SUMOylation of SAE2 was reduced, which corresponded with an increase in global SUMOylation, suggesting that SUMOylation of the Cys domain of SAE2 is a mechanism for "storing" a pool of E1 that can be quickly activated in response to environmental changes. This study is the first to show how E1 activity is controlled by post-translational modifications, and similar regulation likely exists across the homologous E1s of ubiquitin-like modifications.
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Affiliation(s)
- Khue Truong
- Department of Molecular Medicine, Beckman Research Institute of the City of Hope, Duarte, California 91010, USA
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65
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Posttranslational modifications of proteins in the pathobiology of medically relevant fungi. EUKARYOTIC CELL 2011; 11:98-108. [PMID: 22158711 DOI: 10.1128/ec.05238-11] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Posttranslational modifications of proteins drive a wide variety of cellular processes in eukaryotes, regulating cell growth and division as well as adaptive and developmental processes. With regard to the fungal kingdom, most information about posttranslational modifications has been generated through studies of the model yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe, where, for example, the roles of protein phosphorylation, glycosylation, acetylation, ubiquitination, sumoylation, and neddylation have been dissected. More recently, information has begun to emerge for the medically important fungal pathogens Candida albicans, Aspergillus fumigatus, and Cryptococcus neoformans, highlighting the relevance of posttranslational modifications for virulence. We review the available literature on protein modifications in fungal pathogens, focusing in particular upon the reversible peptide modifications sumoylation, ubiquitination, and neddylation.
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66
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Bettermann K, Benesch M, Weis S, Haybaeck J. SUMOylation in carcinogenesis. Cancer Lett 2011; 316:113-25. [PMID: 22138131 DOI: 10.1016/j.canlet.2011.10.036] [Citation(s) in RCA: 121] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Revised: 10/15/2011] [Accepted: 10/26/2011] [Indexed: 10/15/2022]
Abstract
SUMOylation is a post-translational modification characterized by covalent and reversible binding of small ubiquitin-like modifier (SUMO) to a target protein. In mammals, four different isoforms, termed SUMO-1, -2, -3 and -4 have been identified so far. SUMO proteins are critically involved in the modulation of nuclear organization and cell viability. Their expression is significantly increased in processes associated with carcinogenesis such as cell growth, differentiation, senescence, oxidative stress and apoptosis. Little is known about the role of SUMOylation in cancer development. Therefore the present review focuses on possible implications of SUMOylation in carcinogenesis highlighting its impact as an important regulatory cell cycle protein. Moreover, novel opportunities for therapeutic approaches are discussed. The differential expression levels, the target protein preferences and the function of the SUMO pathway in different cancer subtypes raises unexpected issues questioning our understanding of the implication of SUMO in carcinogenesis.
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67
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Zorzi E, Bonvini P. Inducible hsp70 in the regulation of cancer cell survival: analysis of chaperone induction, expression and activity. Cancers (Basel) 2011; 3:3921-56. [PMID: 24213118 PMCID: PMC3763403 DOI: 10.3390/cancers3043921] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 09/26/2011] [Accepted: 10/10/2011] [Indexed: 12/31/2022] Open
Abstract
Understanding the mechanisms that control stress is central to realize how cells respond to environmental and physiological insults. All the more important is to reveal how tumour cells withstand their harsher growth conditions and cope with drug-induced apoptosis, since resistance to chemotherapy is the foremost complication when curing cancer. Intensive research on tumour biology over the past number of years has provided significant insights into the molecular events that occur during oncogenesis, and resistance to anti-cancer drugs has been shown to often rely on stress response and expression of inducible heat shock proteins (HSPs). However, with respect to the mechanisms guarding cancer cells against proteotoxic stresses and the modulatory effects that allow their survival, much remains to be defined. Heat shock proteins are molecules responsible for folding newly synthesized polypeptides under physiological conditions and misfolded proteins under stress, but their role in maintaining the transformed phenotype often goes beyond their conventional chaperone activity. Expression of inducible HSPs is known to correlate with limited sensitivity to apoptosis induced by diverse cytotoxic agents and dismal prognosis of several tumour types, however whether cancer cells survive because of the constitutive expression of heat shock proteins or the ability to induce them when adapting to the hostile microenvironment remains to be elucidated. Clear is that tumours appear nowadays more "addicted" to heat shock proteins than previously envisaged, and targeting HSPs represents a powerful approach and a future challenge for sensitizing tumours to therapy. This review will focus on the anti-apoptotic role of heat shock 70kDa protein (Hsp70), and how regulatory factors that control inducible Hsp70 synthesis, expression and activity may be relevant for response to stress and survival of cancer cells.
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Affiliation(s)
- Elisa Zorzi
- OncoHematology Clinic of Pediatrics, University-Hospital of Padova, 35100 Padova, Italy; E-Mail:
| | - Paolo Bonvini
- OncoHematology Clinic of Pediatrics, University-Hospital of Padova, 35100 Padova, Italy; E-Mail:
- Fondazione Città della Speranza, 36030 Monte di Malo, Vicenza, Italy
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68
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Abstract
When a transcription factor is modified by small ubiquitin-like modifier (SUMO), this usually represses its transcriptional activity. In this issue of Developmental Cell, Lee et al. (2011) use a knockin mouse model to show that SUMO-less SF-1 binds and activates inappropriate targets, causing changes in cell fates and endocrine abnormalities.
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Affiliation(s)
- Feng-Ming Lin
- Texas Heart Institute/St. Luke's Episcopal Hospital, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
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69
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Georges A, Benayoun BA, Marongiu M, Dipietromaria A, L'Hôte D, Todeschini AL, Auer J, Crisponi L, Veitia RA. SUMOylation of the Forkhead transcription factor FOXL2 promotes its stabilization/activation through transient recruitment to PML bodies. PLoS One 2011; 6:e25463. [PMID: 22022399 PMCID: PMC3192040 DOI: 10.1371/journal.pone.0025463] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Accepted: 09/05/2011] [Indexed: 01/28/2023] Open
Abstract
Background FOXL2 is a transcription factor essential for ovarian development and maintenance. It is mutated in the genetic condition called Blepharophimosis Ptosis Epicantus inversus Syndrome (BPES) and in cases of isolated premature ovarian failure. We and others have previously shown that FOXL2 undergoes several post-translational modifications. Methods and Principal Findings Here, using cells in culture, we show that interference with FOXL2 SUMOylation leads to a robust inhibition of its transactivation ability, which correlates with a decreased stability. Interestingly, FOXL2 SUMOylation promotes its transient recruitment to subnuclear structures that we demonstrate to be PML (Promyelocytic Leukemia) Nuclear Bodies. Since PML bodies are known to be sites where post-translational modifications of nuclear factors take place, we used tandem mass spectrometry to identify new post-translational modifications of FOXL2. Specifically, we detected four phosphorylated, one sulfated and three acetylated sites. Conclusions By analogy with other transcription factors, we propose that PML Nuclear Bodies might transiently recruit FOXL2 to the vicinity of locally concentrated enzymes that could be involved in the post-translational maturation of FOXL2. FOXL2 acetylation, sulfation, phosphorylation as well as other modifications yet to be discovered might alter the transactivation capacity of FOXL2 and/or its stability, thus modulating its global intracellular activity.
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Affiliation(s)
- Adrien Georges
- Programme de Pathologie Moléculaire et Cellulaire, Institut Jacques Monod, UMR 7592 CNRS-Université Paris Diderot, Paris, France
- Université Paris-Diderot/Paris VII, Paris, France
- Ecole Normale Supérieure de Paris, Paris, France
| | - Bérénice A. Benayoun
- Programme de Pathologie Moléculaire et Cellulaire, Institut Jacques Monod, UMR 7592 CNRS-Université Paris Diderot, Paris, France
- Université Paris-Diderot/Paris VII, Paris, France
| | - Mara Marongiu
- Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche, Cagliari, Italy
| | - Aurélie Dipietromaria
- Programme de Pathologie Moléculaire et Cellulaire, Institut Jacques Monod, UMR 7592 CNRS-Université Paris Diderot, Paris, France
- Université Paris-Diderot/Paris VII, Paris, France
- Université Paris-Sud/Paris XI, Orsay, France
| | - David L'Hôte
- Programme de Pathologie Moléculaire et Cellulaire, Institut Jacques Monod, UMR 7592 CNRS-Université Paris Diderot, Paris, France
- Université Paris-Diderot/Paris VII, Paris, France
| | - Anne-Laure Todeschini
- Programme de Pathologie Moléculaire et Cellulaire, Institut Jacques Monod, UMR 7592 CNRS-Université Paris Diderot, Paris, France
- Université Paris-Diderot/Paris VII, Paris, France
| | - Jana Auer
- Faculté de Médecine Cochin-Port-Royal, Université Paris Descartes/Paris V, Paris, France
| | - Laura Crisponi
- Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche, Cagliari, Italy
| | - Reiner A. Veitia
- Programme de Pathologie Moléculaire et Cellulaire, Institut Jacques Monod, UMR 7592 CNRS-Université Paris Diderot, Paris, France
- Université Paris-Diderot/Paris VII, Paris, France
- * E-mail:
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70
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Anckar J, Sistonen L. Regulation of HSF1 function in the heat stress response: implications in aging and disease. Annu Rev Biochem 2011; 80:1089-115. [PMID: 21417720 DOI: 10.1146/annurev-biochem-060809-095203] [Citation(s) in RCA: 542] [Impact Index Per Article: 41.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
To dampen proteotoxic stresses and maintain protein homeostasis, organisms possess a stress-responsive molecular machinery that detects and neutralizes protein damage. A prominent feature of stressed cells is the increased synthesis of heat shock proteins (Hsps) that aid in the refolding of misfolded peptides and restrain protein aggregation. Transcriptional activation of the heat shock response is orchestrated by heat shock factor 1 (HSF1), which rapidly translocates to hsp genes and induces their expression. Although the role of HSF1 in protecting cells and organisms against severe stress insults is well established, many aspects of how HSF1 senses qualitatively and quantitatively different forms of stresses have remained poorly understood. Moreover, recent discoveries that HSF1 controls life span have prompted new ways of thinking about an old transcription factor. Here, we review the established role of HSF1 in counteracting cell stress and prospect the role of HSF1 as a regulator of disease states and aging.
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Affiliation(s)
- Julius Anckar
- Department of Biosciences, Åbo Akademi University, BioCity, 20520 Turku, Finland.
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71
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Park HC, Choi W, Park HJ, Cheong MS, Koo YD, Shin G, Chung WS, Kim WY, Kim MG, Bressan RA, Bohnert HJ, Lee SY, Yun DJ. Identification and molecular properties of SUMO-binding proteins in Arabidopsis. Mol Cells 2011; 32:143-51. [PMID: 21607647 PMCID: PMC3887670 DOI: 10.1007/s10059-011-2297-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Revised: 04/20/2011] [Accepted: 04/28/2011] [Indexed: 10/18/2022] Open
Abstract
Reversible conjugation of the small ubiquitin modifier (SUMO) peptide to proteins (SUMOylation) plays important roles in cellular processes in animals and yeasts. However, little is known about plant SUMO targets. To identify SUMO substrates in Arabidopsis and to probe for biological functions of SUMO proteins, we constructed 6xHis-3xFLAG fused AtSUMO1 (HFAtSUMO1) controlled by the CaMV35S promoter for transformation into Arabidopsis Col-0. After heat treatment, an increased sumoylation pattern was detected in the transgenic plants. SUMO1-modified proteins were selected after two-dimensional gel electrophoresis (2-DE) image analysis and identified using matrix-assisted laser-desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). We identified 27 proteins involved in a variety of processes such as nucleic acid metabolism, signaling, metabolism, and including proteins of unknown functions. Binding and sumoylation patterns were confirmed independently. Surprisingly, MCM3 (At5G46280), a DNA replication licensing factor, only interacted with and became sumoylated by AtSUMO1, but not by SUMO1ΔGG or AtSUMO3. The results suggest specific interactions between sumoylation targets and particular sumoylation enzymes.
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Affiliation(s)
- Hyeong Cheol Park
- Division of Applied Life Science (Brain Korea 21 Program), and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-701, Korea
- These authors contributed equally to this work
| | - Wonkyun Choi
- Division of Applied Life Science (Brain Korea 21 Program), and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-701, Korea
- These authors contributed equally to this work
| | - Hee Jin Park
- Division of Applied Life Science (Brain Korea 21 Program), and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-701, Korea
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana, USA
- These authors contributed equally to this work
| | - Mi Sun Cheong
- Division of Applied Life Science (Brain Korea 21 Program), and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-701, Korea
| | - Yoon Duck Koo
- Division of Applied Life Science (Brain Korea 21 Program), and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-701, Korea
| | - Gilok Shin
- Division of Applied Life Science (Brain Korea 21 Program), and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-701, Korea
| | - Woo Sik Chung
- Division of Applied Life Science (Brain Korea 21 Program), and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-701, Korea
| | - Woe-Yeon Kim
- Division of Applied Life Science (Brain Korea 21 Program), and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-701, Korea
| | - Min Gab Kim
- Bio-Crops Development Division, Department of Agricultural Biotechnology, National Academy of Agricultural Science, Rural Development Administration, Suwon 441-707, Korea
| | - Ray A. Bressan
- Division of Applied Life Science (Brain Korea 21 Program), and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-701, Korea
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana, USA
- King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia
| | - Hans J. Bohnert
- Division of Applied Life Science (Brain Korea 21 Program), and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-701, Korea
- Departments of Plant Biology and of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, USA
| | - Sang Yeol Lee
- Division of Applied Life Science (Brain Korea 21 Program), and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-701, Korea
| | - Dae-Jin Yun
- Division of Applied Life Science (Brain Korea 21 Program), and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-701, Korea
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72
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Park BS, Song JT, Seo HS. Arabidopsis nitrate reductase activity is stimulated by the E3 SUMO ligase AtSIZ1. Nat Commun 2011; 2:400. [PMID: 21772271 PMCID: PMC3160146 DOI: 10.1038/ncomms1408] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Accepted: 06/21/2011] [Indexed: 11/09/2022] Open
Abstract
Small ubiquitin-related modifier (SUMO) is a small polypeptide that modulates protein activity and regulates hormone signalling, abiotic and biotic responses in plants. Here we show that AtSIZ regulates nitrogen assimilation in Arabidopsis through its E3 SUMO ligase function. Dwarf plants of siz1-2 flower early, show abnormal seed development and have high salicylic acid content and enhanced resistance to bacterial pathogens. These mutant phenotypes are reverted to wild-type phenotypes by exogenous ammonium but not by nitrate, phosphate or potassium. Decreased nitrate reductase activity in siz1-2 plants resulted in low nitrogen concentrations, low nitric oxide production and high nitrate content in comparison with wild-type plants. The nitrate reductases, NIA1 and NIA2, are sumoylated by AtSIZ1, which dramatically increases their activity. Both sumoylated and non-sumoylated NIA1 and NIA2 can form dimers. Our results indicate that AtSIZ1 positively controls nitrogen assimilation by promoting sumoylation of NRs in Arabidopsis.
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Affiliation(s)
- Bong Soo Park
- Department of Plant Science, Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Korea
- Plant Genomics and Breeding Institute, Seoul National University, Seoul 151-921, Korea
| | - Jong Tae Song
- School of Applied Biosciences, Kyungpook National University, Daegu 702-701, Korea
| | - Hak Soo Seo
- Department of Plant Science, Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Korea
- Plant Genomics and Breeding Institute, Seoul National University, Seoul 151-921, Korea
- Bio-MAX Institute, Seoul National University, Seoul 151-818, Korea
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73
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Ting YK, Morikawa K, Kurata Y, Li P, Bahrudin U, Mizuta E, Kato M, Miake J, Yamamoto Y, Yoshida A, Murata M, Inoue T, Nakai A, Shiota G, Higaki K, Nanba E, Ninomiya H, Shirayoshi Y, Hisatome I. Transcriptional activation of the anchoring protein SAP97 by heat shock factor (HSF)-1 stabilizes K(v) 1.5 channels in HL-1 cells. Br J Pharmacol 2011; 162:1832-42. [PMID: 21232033 PMCID: PMC3081125 DOI: 10.1111/j.1476-5381.2011.01204.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND AND PURPOSE The expression of voltage-dependent K+ channels (Kv) 1.5 is regulated by members of the heat shock protein (Hsp) family. We examined whether the heat shock transcription factor 1 (HSF-1) and its inducer geranylgeranylacetone (GGA) could affect the expression of Kv1.5 channels and its anchoring protein, synapse associated protein 97 (SAP97). EXPERIMENTAL APPROACH Transfected mouse atrial cardiomyocytes (HL-1 cells) and COS7 cells were subjected to luciferase reporter gene assay and whole-cell patch clamp. Protein and mRNA extracts were subjected to Western blot and quantitative real-time polymerase chain reaction. KEY RESULTS Heat shock of HL-1 cells induced expression of Hsp70, HSF-1, SAP97 and Kv1.5 proteins. These effects were reproduced by wild-type HSF-1. Both heat shock and expression of HSF-1, but not the R71G mutant, increased the SAP97 mRNA level. Small interfering RNA (siRNA) against SAP97 abolished HSF-1-induced increase of Kv1.5 and SAP97 proteins. A luciferase reporter gene assay revealed that the SAP97 promoter region (from −919 to −740) that contains heat shock elements (HSEs) was required for this induction. Suppression of SIRT1 function either by nicotinamide or siRNA decreased the level of SAP97 mRNA. SIRT1 activation by resveratrol had opposing effects. A treatment of the cells with GGA increased the level of SAP97 mRNA, Kv1.5 proteins and IKur current, which could be modified with either resveratrol or nicotinamide. CONCLUSIONS AND IMPLICATIONS HSF-1 induced transcription of SAP97 through SIRT1-dependent interaction with HSEs; the increase in SAP97 resulted in stabilization of Kv1.5 channels. These effects were mimicked by GGA.
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Affiliation(s)
- Y K Ting
- Division of Regenerative Medicine and Therapeutics, Institute of Regenerative Medicine and Biofunction, Tottori University Graduate School of Medical Science, Yonago, Japan
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74
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Sengupta S, Badhwar I, Upadhyay M, Singh S, Ganesh S. Malin and laforin are essential components of a protein complex that protects cells from thermal stress. J Cell Sci 2011; 124:2277-86. [PMID: 21652633 DOI: 10.1242/jcs.082800] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The heat-shock response is a conserved cellular process characterized by the induction of a unique group of proteins known as heat-shock proteins. One of the primary triggers for this response, at least in mammals, is heat-shock factor 1 (HSF1)--a transcription factor that activates the transcription of heat-shock genes and confers protection against stress-induced cell death. In the present study, we investigated the role of the phosphatase laforin and the ubiquitin ligase malin in the HSF1-mediated heat-shock response. Laforin and malin are defective in Lafora disease (LD), a neurodegenerative disorder associated with epileptic seizures. Using cellular models, we demonstrate that these two proteins, as a functional complex with the co-chaperone CHIP, translocate to the nucleus upon heat shock and that all the three members of this complex are required for full protection against heat-shock-induced cell death. We show further that laforin and malin interact with HSF1 and contribute to its activation during stress by an unknown mechanism. HSF1 is also required for the heat-induced nuclear translocation of laforin and malin. This study demonstrates that laforin and malin are key regulators of HSF1 and that defects in the HSF1-mediated stress response pathway might underlie some of the pathological symptoms in LD.
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Affiliation(s)
- Sonali Sengupta
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India.
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75
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Pandey D, Chen F, Patel A, Wang CY, Dimitropoulou C, Patel VS, Rudic RD, Stepp DW, Fulton DJ. SUMO1 negatively regulates reactive oxygen species production from NADPH oxidases. Arterioscler Thromb Vasc Biol 2011; 31:1634-42. [PMID: 21527745 DOI: 10.1161/atvbaha.111.226621] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
OBJECTIVE Increased protein SUMOylation (small ubiquitin-related modifier [SUMO]) provides protection from cellular stress, including oxidative stress, but the mechanisms involved are incompletely understood. The NADPH oxidases (Nox) are a primary source of reactive oxygen species (ROS) and oxidative stress, and thus our goal was to determine whether SUMO regulates NADPH oxidase activity. METHODS AND RESULTS Increased expression of SUMO1 potently inhibited the activity of Nox1 to Nox5. In contrast, inhibition of endogenous SUMOylation with small interfering RNA to SUMO1 or ubiquitin conjugating enzyme 9 or with the inhibitor anacardic acid increased ROS production from human embryonic kidney-Nox5 cells, human vascular smooth muscle cells, and neutrophils. The suppression of ROS production was unique to SUMO1, and it required a C-terminal diglycine and the SUMO-specific conjugating enzyme ubiquitin conjugating enzyme 9. SUMO1 did not modify intracellular calcium or Nox5 phosphorylation but reduced ROS output in an isolated enzyme assay, suggesting direct effects of SUMOylation on enzyme activity. However, we could not detect the presence of SUMO1 conjugation on Nox5 using a variety of approaches. Moreover, the mutation of more than 17 predicted and conserved lysine residues on Nox5 did not alter the inhibitory actions of SUMO1. CONCLUSIONS Together, these results suggest that SUMO is an important regulatory mechanism that indirectly represses the production of ROS to ameliorate cellular stress.
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Affiliation(s)
- Deepesh Pandey
- Vascular Biology Center, Medical College of Georgia, Augusta, GA 30912, USA
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76
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Vabulas RM, Raychaudhuri S, Hayer-Hartl M, Hartl FU. Protein folding in the cytoplasm and the heat shock response. Cold Spring Harb Perspect Biol 2011; 2:a004390. [PMID: 21123396 DOI: 10.1101/cshperspect.a004390] [Citation(s) in RCA: 284] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Proteins generally must fold into precise three-dimensional conformations to fulfill their biological functions. In the cell, this fundamental process is aided by molecular chaperones, which act in preventing protein misfolding and aggregation. How this machinery assists newly synthesized polypeptide chains in navigating the complex folding energy landscape is now being understood in considerable detail. The mechanisms that ensure the maintenance of a functional proteome under normal and stress conditions are also of great medical relevance, as the aggregation of proteins that escape the cellular quality control underlies a range of debilitating diseases, including many age-of-onset neurodegenerative disorders.
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Affiliation(s)
- R Martin Vabulas
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany
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77
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Leach MD, Stead DA, Argo E, Brown AJ. Identification of sumoylation targets, combined with inactivation of SMT3, reveals the impact of sumoylation upon growth, morphology, and stress resistance in the pathogen Candida albicans. Mol Biol Cell 2011; 22:687-702. [PMID: 21209325 PMCID: PMC3046064 DOI: 10.1091/mbc.e10-07-0632] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 11/24/2010] [Accepted: 12/21/2010] [Indexed: 11/23/2022] Open
Abstract
Posttranslational modifications of proteins play critical roles in the control of cellular differentiation, development, and environmental adaptation. In particular, the covalent attachment of the small ubiquitin-like modifier, SUMO, to target proteins (sumoylation) regulates cell cycle progression, transcription, nucleocytoplasmic transport, and stress responses. Here we combine proteomic, molecular, and cellular approaches to examine the roles of sumoylation in the major fungal pathogen of humans, Candida albicans. Using an N-terminally FLAG-tagged SUMO, 31 sumoylated proteins were identified in C. albicans with roles in stress responses (e.g., Hsp60, Hsp70 family members, Hsp104), the cytoskeleton and polarized growth (e.g., Tub1, Cct7, Mlc1), secretion, and endocytosis (e.g., Lsp1, Sec24, Sec7). The output from this proteomic screen was entirely consistent with the phenotypes of C. albicans mutants in which the single SUMO-encoding locus (SMT3) was inactivated or down-regulated. C. albicans smt3/smt3 cells displayed defects in growth, morphology, cell separation, nuclear segregation, and chitin deposition, suggesting important roles for sumoylation in cell cycle control. Smt3/smt3 cells also displayed sensitivity to thermal, oxidative, and cell wall stresses as well as to the antifungal drug caspofungin. Mutation of consensus sumoylation sites in Hsp60 and Hsp104 affected the resistance of C. albicans to thermal stress. Furthermore, signaling via the cell integrity pathway was defective in C. albicans smt3/smt3 cells. These observations provide mechanistic explanations for many of the observed phenotypic effects of Smt3 inactivation upon C. albicans growth and environmental adaptation. Clearly sumoylation plays key roles in fundamental cellular processes that underpin the pathogenicity of this medically important fungus.
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Affiliation(s)
- Michelle D. Leach
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, United Kingdom
| | - David A. Stead
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, United Kingdom
| | - Evelyn Argo
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, United Kingdom
| | - Alistair J.P. Brown
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, United Kingdom
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78
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Björk JK, Sistonen L. Regulation of the members of the mammalian heat shock factor family. FEBS J 2010; 277:4126-39. [PMID: 20945529 DOI: 10.1111/j.1742-4658.2010.07828.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Regulation of gene expression is fundamental in all living organisms and is facilitated by transcription factors, the single largest group of proteins in humans. For cell- and stimulus-specific gene regulation, strict control of the transcription factors themselves is crucial. Heat shock factors are a family of transcription factors best known as master regulators of induced gene expression during the heat shock response. This evolutionary conserved cellular stress response is characterized by massive production of heat shock proteins, which function as cytoprotective molecular chaperones against various proteotoxic stresses. In addition to promoting cell survival under stressful conditions, heat shock factors are involved in the regulation of life span and progression of cancer and they are also important for developmental processes such as gametogenesis, neurogenesis and maintenance of sensory organs. Here, we review the regulatory mechanisms steering the activities of the mammalian heat shock factors 1–4.
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Affiliation(s)
- Johanna K Björk
- Department of Biosciences, Åbo Akademi University, Turku, Finland
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79
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Anaphase-promoting complex/cyclosome participates in the acute response to protein-damaging stress. Mol Cell Biol 2010; 30:5608-20. [PMID: 20937767 DOI: 10.1128/mcb.01506-09] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The ubiquitin E3 ligase anaphase-promoting complex/cyclosome (APC/C) drives degradation of cell cycle regulators in cycling cells by associating with the coactivators Cdc20 and Cdh1. Although a plethora of APC/C substrates have been identified, only a few transcriptional regulators are described as direct targets of APC/C-dependent ubiquitination. Here we show that APC/C, through substrate recognition by both Cdc20 and Cdh1, mediates ubiquitination and degradation of heat shock factor 2 (HSF2), a transcription factor that binds to the Hsp70 promoter. The interaction between HSF2 and the APC/C subunit Cdc27 and coactivator Cdc20 is enhanced by moderate heat stress, and the degradation of HSF2 is induced during the acute phase of the heat shock response, leading to clearance of HSF2 from the Hsp70 promoter. Remarkably, Cdc20 and the proteasome 20S core α2 subunit are recruited to the Hsp70 promoter in a heat shock-inducible manner. Moreover, the heat shock-induced expression of Hsp70 is increased when Cdc20 is silenced by a specific small interfering RNA (siRNA). Our results provide the first evidence for participation of APC/C in the acute response to protein-damaging stress.
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80
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Bodén M, Dellaire G, Burrage K, Bailey TL. A Bayesian network model of proteins' association with promyelocytic leukemia (PML) nuclear bodies. J Comput Biol 2010; 17:617-30. [PMID: 20426694 DOI: 10.1089/cmb.2009.0140] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The modularity that nuclear organization brings has the potential to explain the function of aggregates of proteins and RNA. Promyelocytic leukemia nuclear bodies are implicated in important regulatory processes. To understand the complement of proteins associated with these intra-nuclear bodies, we construct a Bayesian network model that integrates sequence and protein-protein interaction data. The model predicts association with promyelocytic leukemia nuclear bodies accurately when interaction data is available. At a false positive rate of 10%, the true positive rate is almost 50%, indicated by an independent nuclear proteome reference set. The model provides strong support for further expanding the protein complement with several important regulators and a richer functional repertoire. Using special support vector machine (SVM)-nodes (equipped with string kernels), the Bayesian network is also able to produce predictions on the basis of sequence only, with an accuracy superior to that of baseline models. Supplementary Material is available online at www.liebertonline.com.
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Affiliation(s)
- Mikael Bodén
- Institute for Molecular Bioscience, University of Queensland, St. Lucia, Queensland, Australia.
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81
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Cohen-Peer R, Schuster S, Meiri D, Breiman A, Avni A. Sumoylation of Arabidopsis heat shock factor A2 (HsfA2) modifies its activity during acquired thermotholerance. PLANT MOLECULAR BIOLOGY 2010; 74:33-45. [PMID: 20521085 DOI: 10.1007/s11103-010-9652-1] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2009] [Accepted: 05/13/2010] [Indexed: 05/20/2023]
Abstract
Post-translational modification of target proteins by the small ubiquitin-like modifier protein (SUMO) regulate many cellular processes. In this work we show SUMOylation of the heat shock transcription factor, AtHsfA2, in connection with the plant's response to heat stress and acquired thermotolerance. Using the Yeast two hybrid and the bimolecular fluorescence complementation system, we have found that AtSUMO1 physically interacts with AtHsfA2. Further investigation allowed us to determine that Lys 315 of AtHsfA2 is the main SUMOylation site. Overexpression of AtSUMO1 led to a decrease in AtHsfA2 transcriptional activation of heat shock promoters. We have examined the effect of AtSUMO1 on AtHsfA2 during heat shock treatments. The phenotype of seedlings overexpressing AtSUMO1 resembled the phenotype of AtHsfA2 knock out seedlings, which were more sensitive than wild type seedlings to repeated heat treatment. Furthermore, AtSUMO1 overexpressing seedlings exhibited lower expression levels of small heat shock proteins as compared with wild type seedlings after heat treatment. Based on our findings, we suggest that AtSUMO1 is involved in the regulation of AtHsfA2 in acquired thermotolerance.
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82
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Abstract
ING2 (inhibitor of growth 2) is a candidate tumor-suppressor gene involved in cell cycle control, apoptosis and senescence. Although the functions of ING2 within the chromatin remodeling complex Sin3A/histone deacetylase (HDAC) and in the p53 pathway have been described, how ING2 itself is regulated remains unknown. In this study we report for the first time that ING2 can be sumoylated by small ubiquitin-like modifier 1 (SUMO1) on lysine 195 both in vitro and in vivo. Strikingly, ING2 sumoylation enhances its association with Sin3a. We provide evidences that ING2 can bind to the promoter of genes to mediate their expression and that sumoylation of ING2 is required for this binding to some of these genes. Among them, we identified the gene TMEM71 (transmembrane protein 71), whose expression is regulated by ING2 sumoylation. ING2 must be sumoylated to bind to the promoter of TMEM71 and to recruit the Sin3A chromatin-modifying complex to this promoter, in order to regulate TMEM71 transcription. Hence, sumoylation of ING2 enhances its binding to the Sin3A/HDAC complex and is required to regulate gene transcriptions.
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83
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Shin YC, Liu BY, Tsai JY, Wu JT, Chang LK, Chang SC. Biochemical characterization of the small ubiquitin-like modifiers of Chlamydomonas reinhardtii. PLANTA 2010; 232:649-662. [PMID: 20544217 DOI: 10.1007/s00425-010-1204-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Accepted: 05/24/2010] [Indexed: 05/28/2023]
Abstract
Dynamic modification of target proteins by small ubiquitin-like modifier (SUMO) is known to modulate many important cellular processes and is required for cell viability and development in all eukaryotes. However, understanding of SUMO systems in plants, especially in unicellular green algae, remains elusive. In this study, Chlamydomonas reinhardtii CrSUMO96, CrSUMO97 and CrSUMO148 were characterized. We show that the formation of polymeric CrSUMO96 and CrSUMO97 chains can be catalyzed either by the human SAE1/SAE2 and Ubc9 SUMOylation system in vitro or by an Escherichia coli chimeric SUMOylation system in vivo. An exposed C-terminal di-glycine motif of CrSUMO96 or CrSUMO97 is essential for functional SUMOylation. The human SUMO-specific protease, SENP1, demonstrates more processing activity for CrSUMO97 than for CrSUMO96. The CrSUMO148 precursor notably has four repeated di-glycine motifs at the C-terminus. This unique feature is not found in other known SUMO proteins. Interestingly, only 83-residual CrSUMO148(1-83) with the first di-glycine motif can form SAE1/SAE2-SUMO complex and further form polymeric chains with the help of Ubc9. More surprisingly, CrSUMO148 precursor is digested by SENP1, solely at the peptide bond after the first di-glycine motif although there are four theoretically identical processing sites in the primary sequence. This process directly generates 83-residual CrSUMO148(1-83) mature protein, which is exactly the form suitable for activation and conjugation. We also show that SENP1 displays similar isopeptidase activity in the deconjugation of polymeric CrSUMO96, CrSUMO97 or CrSUMO148 chains, revealing that the catalytic mechanisms of processing and deconjugation of CrSUMOs by SENP1 may differ.
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Affiliation(s)
- Yung-Cheng Shin
- Department of Biochemical Science and Technology, Institute of Microbiology and Biochemistry, College of Life Science, National Taiwan University, No 1, Sec 4, Roosevelt Road, Taipei 10617, Taiwan
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84
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Hannoun Z, Greenhough S, Jaffray E, Hay RT, Hay DC. Post-translational modification by SUMO. Toxicology 2010; 278:288-93. [PMID: 20674646 DOI: 10.1016/j.tox.2010.07.013] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2010] [Revised: 07/06/2010] [Accepted: 07/21/2010] [Indexed: 11/28/2022]
Abstract
Post-translational modifications (PTMs) are chemical alterations to a protein following translation, regulating stability and function. Reversible phosphorylation is an example of an important and well studied PTM involved in a number of cellular processes. SUMOylation is another PTM known to modify a large number of proteins and plays a role in various cellular processes including: cell cycle regulation, gene transcription, differentiation and cellular localisation. Therefore, understanding the role of SUMOylation in cell biology may allow the development of more efficient models, important in streamlining the drug discovery process. This review will focus on protein SUMOylation and its role in stem cell and somatic cell biology.
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Affiliation(s)
- Zara Hannoun
- Medical Research Council-Centre for Regenerative Medicine, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh EH164SB, UK
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85
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Tvermoes BE, Boyd WA, Freedman JH. Molecular characterization of numr-1 and numr-2: genes that increase both resistance to metal-induced stress and lifespan in Caenorhabditis elegans. J Cell Sci 2010; 123:2124-34. [PMID: 20501697 DOI: 10.1242/jcs.065433] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
To define the mechanisms involved in the molecular response to the carcinogenic metal cadmium, two novel metal-inducible genes from C. elegans were characterized: numr-1 and numr-2 (nuclear localized metal responsive). numr-1 and numr-2 sequences and cellular patterns of expression are identical, indicating that these are functionally equivalent genes. Constitutive transcription of numr-1 and numr-2 is developmentally regulated and occurs in the intestine, in head and tail neurons, and vulva muscles. Exposure to metals induces numr-1 and numr-2 transcription in pharyngeal and intestinal cells. Other environmental stressors do not affect transcription, indicating that these are metal-specific, stress-responsive genes. NUMR-1 and NUMR-2 target to nuclei and colocalize with HSF-1, suggesting that they may be components of nuclear stress granules. Nematodes overexpressing NUMR-1 and NUMR-2 are resistant to stress and live longer than control animals; likewise reducing expression increases sensitivity to metals and decreases neuromuscular functions. Upstream regulatory regions of both genes contain potential binding sites for DAF-16 and SKN-1, which are components of the insulin-IGF-like signaling pathway. This pathway regulates longevity and stress responses in C. elegans. NUMR-1 and NUMR-2 may function to promote resistance to environmental stressors and longevity, which is mediated by the insulin-IGF-like signaling pathway.
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Affiliation(s)
- Brooke E Tvermoes
- Laboratory of Molecular Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27009, USA
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86
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Bueno MTD, Garcia-Rivera JA, Kugelman JR, Morales E, Rosas-Acosta G, Llano M. SUMOylation of the lens epithelium-derived growth factor/p75 attenuates its transcriptional activity on the heat shock protein 27 promoter. J Mol Biol 2010; 399:221-39. [PMID: 20382164 DOI: 10.1016/j.jmb.2010.03.063] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2009] [Revised: 03/28/2010] [Accepted: 03/30/2010] [Indexed: 10/19/2022]
Abstract
Lens epithelium-derived growth factor (LEDGF) proteins p75 and p52 are transcriptional coactivators that connect sequence-specific activators to the basal transcription machinery. We have found that these proteins are posttranslationally modified by SUMO (small ubiquitin-like modifier)-1 and SUMO-3. Three SUMOylation sites, K75, K250, and K254, were mapped on the shared N-terminal region of these molecules, while a fourth site, K364, was identified in the C-terminal part exclusive of LEDGF/p75. The N-terminal SUMO targets are located in evolutionarily conserved charge-rich regions that lack resemblance to the described consensus SUMOylation motif, whereas the C-terminal SUMO target is solvent exposed and situated in a typical consensus motif. SUMOylation did not affect the cellular localization of LEDGF proteins and was not necessary for their chromatin-binding ability, nor did it affect this activity. However, lysine to arginine mutations of the identified SUMO acceptor sites drastically inhibited LEDGF SUMOylation, extended the half-life of LEDGF/p75, and significantly increased its transcriptional activity on the heat shock protein 27 promoter, indicating a negative effect of SUMOylation on the transcriptional activity of LEDGF/p75. Considering that SUMOylation is known to negatively affect the transcriptional activity of all transcription factors known to transactivate heat shock protein 27 expression, these findings support the paradigm establishing SUMOylation as a global neutralizer of cellular processes upregulated upon cellular stress.
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Affiliation(s)
- Murilo T D Bueno
- Department of Biological Sciences, University of Texas at El Paso, 500 West University Avenue, El Paso, TX 79968, USA
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87
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Shah NG, Tulapurkar ME, Singh IS, Shelhamer JH, Cowan MJ, Hasday JD. Prostaglandin E2 potentiates heat shock-induced heat shock protein 72 expression in A549 cells. Prostaglandins Other Lipid Mediat 2010; 93:1-7. [PMID: 20382255 DOI: 10.1016/j.prostaglandins.2010.03.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Revised: 03/23/2010] [Accepted: 03/31/2010] [Indexed: 12/11/2022]
Abstract
The heat shock (HS) response is an important cytoprotective response comprising the expression of heat shock proteins (HSPs) and orchestrated by the heat/stress-induced transcription factor, heat shock factor-1 (HSF-1). Previous studies suggest that the activation threshold and magnitude of the HS response may be modified by treatment with arachidonic acid (AA). We analyzed the effect of exogenous AA and its metabolites, PGE(2), LTD(4), and 15-HETE on HSF-1-dependent gene expression in A549 human respiratory epithelial-like cells. When added at 1microM, PGE(2) much more than LTD(4), but not 15-HETE increased activity of a synthetic HSF-1-dependent reporter after HS exposure (42 degrees C for 2h), but had no effect in the absence of HS. Exposing A549 cells to HS stimulated the release of PGE(2) and treatment with the cyclooxygenase inhibitor, ibuprofen, reduced HS-induced HSF-1-dependent transcription. PGE(2) increased HS-induced HSP72 mRNA and protein expression but EMSA and Western blot analysis failed to show an effect on HSF-1 DNA binding activity or post-translational modification. In summary, we showed that HS stimulates the generation of PGE(2), which augments the generation of HSPs. The clinical consequences of this pathway have yet to be determined.
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Affiliation(s)
- Nirav G Shah
- Division of Pulmonary and Critical Care, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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88
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Abstract
SUMOylation is a highly transient post-translational protein modification. Attachment of SUMO to target proteins occurs via a number of specific activating and ligating enzymes that form the SUMO-substrate complex, and other SUMO-specific proteases that cleave the covalent bond, thus leaving both SUMO and target protein free for the next round of modification. SUMO modification has major effects on numerous aspects of substrate function, including subcellular localisation, regulation of their target genes, and interactions with other molecules. The modified SUMO-protein complex is a very transient state, and it thus facilitates rapid response and actions by the cell, when needed. Like phosphorylation, acetylation and ubiquitination, SUMOylation has been associated with a number of cellular processes. In addition to its nuclear role, important sides of mitochondrial activity, stress response signalling and the decision of cells to undergo senescence or apoptosis, have now been shown to involve the SUMO pathway. With ever increasing numbers of reports linking SUMO to human disease, like neurodegeneration and cancer metastasis, it is highly likely that novel and equally important functions of components of the SUMOylation process in cell signalling pathways will be elucidated in the near future.
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Affiliation(s)
- Artemisia M Andreou
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas, Heraklion, Crete, Greece
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89
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Mooney SM, Grande JP, Salisbury JL, Janknecht R. Sumoylation of p68 and p72 RNA helicases affects protein stability and transactivation potential. Biochemistry 2010; 49:1-10. [PMID: 19995069 DOI: 10.1021/bi901263m] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The p68 (DDX5) and p72 (DDX17) proteins are members of the DEAD-box (DDX) family of RNA helicases. We show that both p68 and p72 are overexpressed in breast tumors. Bioinformatical analysis revealed that the SUMO pathway is upregulated in breast tumors and that both p68 and p72 contain one consensus sumoylation site, implicating that sumoylation of p68 and p72 increases during breast tumorigenesis and potentially contributes to their overexpression. We determined that p68 and p72 are indeed sumoylated at a single, homologous site. Importantly, sumoylation significantly increased the stability of p68 and p72. In contrast to p72 and consistent with an approximately 3-fold lesser half-life, p68 was found to be polyubiquitylated, and mutation of the sumoylation site increased polyubiquitylation, suggesting that sumoylation increases p68 half-life by reducing proteasomal degradation. Moreover, whereas p68 robustly coactivated transcription from an estrogen response element, its sumoylation mutant showed a drastically reduced coactivation potential. In contrast, the p68 sumoylation status did not affect the ability to enhance p53-mediated MDM2 transcription. On the contrary, preventing sumoylation of p72 caused an increase in its ability to transactivate both estrogen receptor and p53. Furthermore, sumoylation promoted the interaction of p68 and p72 with histone deacetylase 1 but had no effect on binding to histone deacetylases 2 and 3, the coactivator p300, or estrogen receptor and also did not affect homo/heterodimerization of p68/p72. In conclusion, sumoylation exerts pleiotropic effects on p68/p72, which may have important implications in breast cancer by modulating estrogen receptor and p53 activity.
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Affiliation(s)
- Steven M Mooney
- Department of Biochemistry, Mayo Clinic, Rochester, Minnesota 55905, USA
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90
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Meier I, Brkljacic J. The Arabidopsis nuclear pore and nuclear envelope. THE ARABIDOPSIS BOOK 2010; 8:e0139. [PMID: 22303264 PMCID: PMC3244964 DOI: 10.1199/tab.0139] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The nuclear envelope is a double membrane structure that separates the eukaryotic cytoplasm from the nucleoplasm. The nuclear pores embedded in the nuclear envelope are the sole gateways for macromolecular trafficking in and out of the nucleus. The nuclear pore complexes assembled at the nuclear pores are large protein conglomerates composed of multiple units of about 30 different nucleoporins. Proteins and RNAs traffic through the nuclear pore complexes, enabled by the interacting activities of nuclear transport receptors, nucleoporins, and elements of the Ran GTPase cycle. In addition to directional and possibly selective protein and RNA nuclear import and export, the nuclear pore gains increasing prominence as a spatial organizer of cellular processes, such as sumoylation and desumoylation. Individual nucleoporins and whole nuclear pore subcomplexes traffic to specific mitotic locations and have mitotic functions, for example at the kinetochores, in spindle assembly, and in conjunction with the checkpoints. Mutants of nucleoporin genes and genes of nuclear transport components lead to a wide array of defects from human diseases to compromised plant defense responses. The nuclear envelope acts as a repository of calcium, and its inner membrane is populated by functionally unique proteins connected to both chromatin and-through the nuclear envelope lumen-the cytoplasmic cytoskeleton. Plant nuclear pore and nuclear envelope research-predominantly focusing on Arabidopsis as a model-is discovering both similarities and surprisingly unique aspects compared to the more mature model systems. This chapter gives an overview of our current knowledge in the field and of exciting areas awaiting further exploration.
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Affiliation(s)
- Iris Meier
- Department of Plant Cellular and Molecular Biology and Plant Biotechnology Center, The Ohio State University, 520 Aronoff Laboratory, 318 W 12th Avenue, Columbus, OH 43210
- Address correspondence to
| | - Jelena Brkljacic
- Department of Plant Cellular and Molecular Biology and Plant Biotechnology Center, The Ohio State University, 520 Aronoff Laboratory, 318 W 12th Avenue, Columbus, OH 43210
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91
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Xylourgidis N, Fornerod M. Acting out of character: regulatory roles of nuclear pore complex proteins. Dev Cell 2009; 17:617-25. [PMID: 19922867 DOI: 10.1016/j.devcel.2009.10.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Nuclear pore complexes (NPCs) mediate all selective bidirectional transport between the nucleus and the cytoplasm. Additional functions for NPCs and their constituent proteins (nucleoporins) are emerging, some independent of classical transport. Specifically, enzymatic activities at the NPC regulate nucleocytoplasmic transport and use the NPC as a regulatory scaffold. Also, nucleoporins may regulate gene expression by contacting chromatin. Discriminating between effects on transport, scaffolding, and gene expression is a major challenge in understanding the role of the NPC in signaling and development.
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Affiliation(s)
- Nikos Xylourgidis
- Division of Gene Regulation, Netherlands Cancer Institute, Plesmanlaan 121, 1066CX Amsterdam, The Netherlands
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92
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Martin N, Schwamborn K, Schreiber V, Werner A, Guillier C, Zhang XD, Bischof O, Seeler JS, Dejean A. PARP-1 transcriptional activity is regulated by sumoylation upon heat shock. EMBO J 2009; 28:3534-48. [PMID: 19779455 DOI: 10.1038/emboj.2009.279] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2009] [Accepted: 08/27/2009] [Indexed: 11/09/2022] Open
Abstract
Heat shock and other environmental stresses rapidly induce transcriptional responses subject to regulation by a variety of post-translational modifications. Among these, poly(ADP-ribosyl)ation and sumoylation have received growing attention. Here we show that the SUMO E3 ligase PIASy interacts with the poly(ADP-ribose) polymerase PARP-1, and that PIASy mediates heat shock-induced poly-sumoylation of PARP-1. Furthermore, PIASy, and hence sumoylation, appears indispensable for full activation of the inducible HSP70.1 gene. Chromatin immunoprecipitation experiments show that PIASy, SUMO and the SUMO-conjugating enzyme Ubc9 are rapidly recruited to the HSP70.1 promoter upon heat shock, and that they are subsequently released with kinetics similar to PARP-1. Finally, we provide evidence that the SUMO-targeted ubiquitin ligase RNF4 mediates heat-shock-inducible ubiquitination of PARP-1, regulates the stability of PARP-1, and, like PIASy, is a positive regulator of HSP70.1 gene activity. These results, thus, point to a novel mechanism for regulating PARP-1 transcription function, and suggest crosstalk between sumoylation and RNF4-mediated ubiquitination in regulating gene expression in response to heat shock.
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Affiliation(s)
- Nadine Martin
- Department of Cell Biology and Infection, Nuclear Organisation and Oncogenesis Unit, INSERM U579, Institut Pasteur, Paris, France
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93
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Kuo FT, Bentsi-Barnes IK, Barlow GM, Bae J, Pisarska MD. Sumoylation of forkhead L2 by Ubc9 is required for its activity as a transcriptional repressor of the Steroidogenic Acute Regulatory gene. Cell Signal 2009; 21:1935-44. [PMID: 19744555 DOI: 10.1016/j.cellsig.2009.09.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2009] [Revised: 08/27/2009] [Accepted: 09/01/2009] [Indexed: 12/15/2022]
Abstract
Forkhead L2 (FOXL2) is a member of the forkhead/hepatocyte nuclear factor 3 (FKH/HNF3) gene family of transcription factors and acts as a transcriptional repressor of the Steroidogenic Acute Regulatory (StAR) gene, a marker of granulosa cell differentiation. FOXL2 may play a role in ovarian follicle maturation and prevent premature follicle depletion leading to premature ovarian failure. In this study, we found that FOXL2 interacts with Ubc9, an E2-conjugating enzyme that mediates sumoylation, a key mechanism in transcriptional regulation. FOXL2 and Ubc9 are co-expressed in granulosa cells of small and medium ovarian follicles. FOXL2 is sumoylated by Ubc9, and this Ubc9-mediated sumoylation is essential to the transcriptional activity of FOXL2 on the StAR promoter. As FOXL2 is endogenous to granulosa cells, we generated a stable cell line expressing FOXL2 and found that activity of the StAR promoter in this cell line is greatly decreased in the presence of Ubc9. The sumoylation site was identified at lysine 25 of FOXL2. Mutation of lysine 25 to arginine leads to loss of transcriptional repressor activity of FOXL2. Taken together, we propose that Ubc9-mediated sumoylation at lysine 25 of FOXL2 is required for transcriptional repression of the StAR gene and may be responsible for controlling the development of ovarian follicles.
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Affiliation(s)
- Fang-Ting Kuo
- Center for Fertility and Reproductive Medicine, Division of REI, Department of Ob/Gyn, Cedars-Sinai Medical Center, Los Angeles, CA 90048, United States
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94
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Tulapurkar ME, Asiegbu BE, Singh IS, Hasday JD. Hyperthermia in the febrile range induces HSP72 expression proportional to exposure temperature but not to HSF-1 DNA-binding activity in human lung epithelial A549 cells. Cell Stress Chaperones 2009; 14:499-508. [PMID: 19221897 PMCID: PMC2728283 DOI: 10.1007/s12192-009-0103-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2008] [Revised: 01/26/2009] [Accepted: 01/29/2009] [Indexed: 10/21/2022] Open
Abstract
Expression of heat shock proteins (HSPs) is classically activated at temperatures above the physiologic range (>or=42 degrees C) via activation of the stress-activated transcription factor, heat shock factor-1 (HSF-1). Several studies suggest that less extreme hyperthermia, especially within the febrile range, as occurs during fever and exertional/environmental hyperthemia, can also activate HSF-1 and enhance HSP expression. We compared HSP72 protein and mRNA expression in human A549 lung epithelial cells continuously exposed to 38.5 degrees C, 39.5 degrees C, or 41 degrees C or exposed to a classic heat shock (42 degrees C for 2 h). We found that expression of HSP72 protein and mRNA increased linearly as incubation temperature was increased from 37 degrees C to 41 degrees C, but increased abruptly when the incubation temperature was raised to 42 degrees C. A similar response in luciferase activity was observed using A549 cells stably transfected with an HSF-1-responsive luciferase reporter plasmid. However, activation of intranuclear HSF-1 DNA-binding activity was comparable at 38.5 degrees C, 39.5 degrees C, and 41 degrees C and only modestly greater at 42 degrees C but the mobility of HSF1 protein on a denaturing gel was altered with increasing exposure temperature and was distinctly different at 42 degrees C. These findings indicate that the proportional changes in HSF-1-dependent HSP72 expression at febrile-range temperatures are dependent upon exposure time and temperature but not on the degree of HSF-1 DNA-binding activity. Instead, HSF-1-mediated HSP expression following hyperthermia and heat shock appears to be mediated, in addition to HSF-1 activation, by posttranslational modifications of HSF-1 protein.
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Affiliation(s)
- Mohan E. Tulapurkar
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, School of Medicine, University of Maryland, Baltimore, MD 21201 USA
| | - Benedict E. Asiegbu
- Division of Neonatology, Department of Pediatrics, School of Medicine, University of Maryland, Baltimore, MD 21201 USA
| | - Ishwar S. Singh
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, School of Medicine, University of Maryland, Baltimore, MD 21201 USA
- Mucosal Biology Research Center, School of Medicine, University of Maryland, Baltimore, MD 21201 USA
- Research Services, Baltimore VA Medical Center, Baltimore, MD USA
| | - Jeffrey D. Hasday
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, School of Medicine, University of Maryland, Baltimore, MD 21201 USA
- Mucosal Biology Research Center, School of Medicine, University of Maryland, Baltimore, MD 21201 USA
- Research Services, Baltimore VA Medical Center, Baltimore, MD USA
- Health Science Facility-II, School of Medicine, University of Maryland, Rm. 327, 20 Penn St., Baltimore, MD 21201 USA
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95
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Ma KW, Au SWN, Waye MMY. Over-expression of SUMO-1 induces the up-regulation of heterogeneous nuclear ribonucleoprotein A2/B1 isoform B1 (hnRNP A2/B1 isoform B1) and uracil DNA glycosylase (UDG) in hepG2 cells. Cell Biochem Funct 2009; 27:228-37. [PMID: 19384898 DOI: 10.1002/cbf.1562] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Sumoylation is one of the post-translational modifications that governs many cellular activities, including subcellular localization targeting, protein-protein interaction, and transcriptional activity regulation. SUMO E3 ligases are responsible for substrate specificity determination in which PIAS is the largest E3 family that consists of five members in human; they are PIAS1, PIAS3, PIASx alpha, PIASx beta, and PIASy. Several studies showed that all these PIAS genes are highly expressed in testis but only a few reports have discussed their expression pattern in other tissues. Though liver is a multifunctional organ and one would expect to find regulation of cellular functions by sumoylation, the identified sumoylation substrates are scarce and few of them correlate with liver cancer. In this report, we have found that PIASx alpha, PIASx beta, and PIASy are highly expressed in liver as well as testis by tissue distribution studies. We thus aimed to identify any SUMO-1 related proteins in liver cancer cells by two-dimensional gel electrophoresis and mass spectrometry. Two up-regulated proteins, heterogeneous nuclear ribonucleoprotein A2/B1 isoform B1 (hnRNP A2/B1 isoform B1) and uracil DNA glycosylase (UDG), have been identified in the EGFP-SUMO-1 over-expressing HepG2 cells. The up-regulation is suggested to be mediated via changes at the translational level or protection from degradation by western blotting and RT-PCR.
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Affiliation(s)
- Kit Wan Ma
- The Croucher Laboratory for Human Genomics, MMW Bldg., the Chinese University of Hong Kong, Shatin, NT, Hong Kong, SAR, China
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96
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Whitesell L, Lindquist S. Inhibiting the transcription factor HSF1 as an anticancer strategy. Expert Opin Ther Targets 2009; 13:469-78. [PMID: 19335068 DOI: 10.1517/14728220902832697] [Citation(s) in RCA: 171] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
BACKGROUND In mammals, the cytoprotective heat-shock response is regulated primarily by heat shock factor 1 (HSF1). Unfortunately, the effects of HSF1 also support the ability of cancer cells to accommodate imbalances in signaling and alterations in DNA, protein and energy metabolism associated with oncogenesis. The malignant lifestyle confers dependence on this 'non-oncogene', suggesting a therapeutic role for HSF1 inhibitors. OBJECTIVE/METHODS We begin with an overview of how HSF1 affects cancer biology and how its activity is regulated. We then summarize progress in discovery and development of HSF1 inhibitors, their current limitations and potential as anticancer agents with a fundamentally different scope of action from other clinically validated modulators of protein homeostasis. RESULTS/CONCLUSIONS It is likely that within the next 5 years usable inhibitors of HSF1 will be identified and in early pre-clinical evaluation.
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Affiliation(s)
- Luke Whitesell
- Whitehead Institute, 9 Cambridge Center, Cambridge, MA 02142, USA.
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Xu Z, Chan HY, Lam WL, Lam KH, Lam LSM, Ng TB, Au SWN. SUMO proteases: redox regulation and biological consequences. Antioxid Redox Signal 2009; 11:1453-84. [PMID: 19186998 DOI: 10.1089/ars.2008.2182] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Small-ubiquitin modifier (SUMO) has emerged as a novel modification system that governs the activities of a wide spectrum of protein substrates. SUMO-specific proteases (SENP) are of particular interest, as they are responsible for both the maturation of SUMO precursors and for their deconjugation. The interruption of SENPs has been implicated in embryonic defects and carcinoma cells, indicating that a proper balance of SUMO conjugation and deconjugation is crucial. Recent advances in molecular and cellular biology have highlighted the distinct subcellular localization, and endopeptidase and isopeptidase activities of SENPs, suggesting that they are nonredundant. A better understanding of the molecular basis of SUMO recognition and hydrolytic cleavage has been obtained from the crystal structures of SENP-substrate complexes. While a number of proteomic studies have shown an upregulation of sumoylation, attention is now increasingly being directed towards the regulatory mechanism of sumoylation, in particular the oxidative effect. Findings on the oxidation-induced intermolecular disulfide of E1-E2 ligases and SENP1/2 have improved our understanding of the mechanism by which modification is switched up or down. More intriguingly, a growing body of evidence suggests that sumoylation cross-talks with other modifications, and that the upstream and downstream signaling pathway is co-regulated by more than one modifier.
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Affiliation(s)
- Zheng Xu
- Centre for Protein Science and Crystallography, Department of Biochemistry and Molecular Biotechnology Program, Faculty of Science, The Chinese University of Hong Kong, Hong Kong
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98
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Extracellular signal-regulated kinase mitogen-activated protein kinase signaling initiates a dynamic interplay between sumoylation and ubiquitination to regulate the activity of the transcriptional activator PEA3. Mol Cell Biol 2009; 29:3204-18. [PMID: 19307308 DOI: 10.1128/mcb.01128-08] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Many transcription factors are controlled through SUMO modification, and in the majority of cases this modification results in enhancements in their repressive properties. In some instances, SUMO modification and its associated repressive activities can be reversed by the action of intracellular signaling pathways, leading to enhanced transcriptional capacities of transcription factors. Here we have investigated sumoylation of the ETS domain transcription factor PEA3 and its interplay with the extracellular signal-regulated kinase (ERK) mitogen-activated protein (MAP) kinase signaling pathway. PEA3 is modified by SUMO in vitro and in vivo on multiple sites in its N-terminal region. Activation of the ERK MAP kinase pathway promotes sumoylation of PEA3. Importantly, sumoylation of PEA3 is required for maximal activation of target gene promoters, including MMP-1 and COX-2. Molecularly, sumoylation is selectively required for synergistic activation of target gene expression with the coactivator CBP. Moreover, sumoylation of PEA3 is required for ubiquitination of PEA3 and promotes its degradation, suggesting that SUMO-mediated recycling of PEA3 plays a role in PEA3-mediated promoter activation. Thus, in contrast to the majority of other transcription factors studied, sumoylation of PEA3 plays a positive role in PEA3-mediated transcriptional activation and the ERK MAP kinase pathway cooperates with rather than antagonizes this process.
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Laoong-u-thai Y, Zhao B, Phongdara A, Ako H, Yang J. Identifications of SUMO-1 cDNA and its expression patterns in Pacific white shrimp Litopeanaeus vannamei. Int J Biol Sci 2009; 5:205-14. [PMID: 19240809 PMCID: PMC2646264 DOI: 10.7150/ijbs.5.205] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2009] [Accepted: 02/14/2009] [Indexed: 11/05/2022] Open
Abstract
Small ubiquitin-like modifiers (SUMO) work in a similar way as ubiquitin to alter the biological properties of a target protein by conjugation. A shrimp SUMO cDNA named LvSUMO-1 was identified in Litopenaeus vannamei. LvSUMO-1 cDNA contains a coding sequence of 282 nucleotides with untranslated regions of 37 bp at 5'-end and 347 bp at 3'-end, respectively. The deduced 93 amino acids exhibit 83% identity with the Western Honeybee SUMO-1, and more than 65% homologies with human and mouse SUMO-1. LvSUMO-1 mRNA is expressed in most L. vannamei tissues with the highest level in hepatopancrease. The mRNA expression of LvSUMO-1 over development stages in L. Vammamei is distinguished by a low level in nauplius stage and relatively high level in postlarva stage with continuous expression until juvenile stage. The LvSUMO-1 protein and its conjugated proteins are detected in both cytoplasm and nucleus in several tissues. Interestingly, LvSUMO-1 mRNA levels are high in abdominal muscle during the premolt stage, wherein it has significant activities of protein degradation, suggesting its possible role in the regulation of shrimp muscle protein degradation.
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Affiliation(s)
- Yanisa Laoong-u-thai
- Department of Human Nutrition, Food and Animal Sciences, University of Hawaii at Manoa, Honolulu, HI 96822, USA
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100
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Wu F, Zhu S, Ding Y, Beck WT, Mo YY. MicroRNA-mediated regulation of Ubc9 expression in cancer cells. Clin Cancer Res 2009; 15:1550-7. [PMID: 19223510 DOI: 10.1158/1078-0432.ccr-08-0820] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
PURPOSE As an E2-conjugating enzyme for sumoylation, Ubc9 plays a critical role in sumoylation-mediated cellular pathways, ultimately impacting cell growth and cancer development. The aim of this study was to investigate the regulation of Ubc9 in cancer cells. EXPERIMENTAL DESIGN Immunohistochemistry and Western blot were used to determine Ubc9 expression in paraffin-embedded tumor tissue and frozen specimens of the matched tumors from the same patient, respectively. To establish the causal relationship between miR-30e and Ubc9 expression, we overexpressed miR-30e and then determined the resultant effects on Ubc9 expression. To determine whether miR-30e directly targets Ubc9, we did luciferase assays using luciferase reporters carrying the 3'-untranslated region (3'-UTR) of the Ubc9 gene. RESULTS We found that Ubc9 is up-regulated in breast, head and neck, and lung cancer specimens. In addition, an examination of eight pairs of matched breast tumor specimens by Western blot analysis revealed that, on average, the level of Ubc9 is 5.7-fold higher in tumor than in the matched normal breast tissue. Of interest, we present evidence that Ubc9 is subjected to posttranscriptional regulation by microRNA, and the miR-30 family, such as miR-30e, negatively regulates Ubc9 expression. In contrast to Ubc9, miR-30e is underexpressed in tumors. Moreover, ectopic expression of miR-30e suppresses cell growth, which can be partially reversed by Ubc9. Finally, using luciferase-Ubc9-3'-UTR reporters, we show that Ubc9 is a direct target for miR-30e by interactions with the putative miR-30e binding sites. CONCLUSION These results provide new insight into regulation of Ubc9 in cancer cells.
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Affiliation(s)
- Fangting Wu
- Department of Medical Microbiology, Immunology and Cell Biology, Southern Illinois University School of Medicine, Springfield, Illinois 62794, USA
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