1
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Yao L, Jiang Z, Wang Y, Hu Y, Hao G, Zhong W, Wan S, Xin X. High air humidity dampens salicylic acid pathway and NPR1 function to promote plant disease. EMBO J 2023; 42:e113499. [PMID: 37728254 PMCID: PMC10620762 DOI: 10.15252/embj.2023113499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 08/16/2023] [Accepted: 08/18/2023] [Indexed: 09/21/2023] Open
Abstract
The occurrence of plant disease is determined by interactions among host, pathogen, and environment. Air humidity shapes various aspects of plant physiology and high humidity has long been known to promote numerous phyllosphere diseases. However, the molecular basis of how high humidity interferes with plant immunity to favor disease has remained elusive. Here we show that high humidity is associated with an "immuno-compromised" status in Arabidopsis plants. Furthermore, accumulation and signaling of salicylic acid (SA), an important defense hormone, are significantly inhibited under high humidity. NPR1, an SA receptor and central transcriptional co-activator of SA-responsive genes, is less ubiquitinated and displays a lower promoter binding affinity under high humidity. The cellular ubiquitination machinery, particularly the Cullin 3-based E3 ubiquitin ligase mediating NPR1 protein ubiquitination, is downregulated under high humidity. Importantly, under low humidity the Cullin 3a/b mutant plants phenocopy the low SA gene expression and disease susceptibility that is normally observed under high humidity. Our study uncovers a mechanism by which high humidity dampens a major plant defense pathway and provides new insights into the long-observed air humidity influence on diseases.
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Affiliation(s)
- Lingya Yao
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and EcologyChinese Academy of SciencesShanghaiChina
- University of the Chinese Academy of SciencesBeijingChina
| | - Zeyu Jiang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and EcologyChinese Academy of SciencesShanghaiChina
- University of the Chinese Academy of SciencesBeijingChina
| | - Yiping Wang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and EcologyChinese Academy of SciencesShanghaiChina
- University of the Chinese Academy of SciencesBeijingChina
| | - Yezhou Hu
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and EcologyChinese Academy of SciencesShanghaiChina
- University of the Chinese Academy of SciencesBeijingChina
| | - Guodong Hao
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and EcologyChinese Academy of SciencesShanghaiChina
- University of the Chinese Academy of SciencesBeijingChina
| | - Weili Zhong
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and EcologyChinese Academy of SciencesShanghaiChina
- University of the Chinese Academy of SciencesBeijingChina
| | - Shiwei Wan
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and EcologyChinese Academy of SciencesShanghaiChina
- University of the Chinese Academy of SciencesBeijingChina
| | - Xiu‐Fang Xin
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and EcologyChinese Academy of SciencesShanghaiChina
- University of the Chinese Academy of SciencesBeijingChina
- Chinese Academy of Sciences (CAS) and CAS John Innes Centre of Excellence for Plant and Microbial SciencesShanghaiChina
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2
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Rieu P, Arnoux-Courseaux M, Tichtinsky G, Parcy F. Thinking outside the F-box: how UFO controls angiosperm development. THE NEW PHYTOLOGIST 2023; 240:945-959. [PMID: 37664990 DOI: 10.1111/nph.19234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 07/19/2023] [Indexed: 09/05/2023]
Abstract
The formation of inflorescences and flowers is essential for the successful reproduction of angiosperms. In the past few decades, genetic studies have identified the LEAFY transcription factor and the UNUSUAL FLORAL ORGANS (UFO) F-box protein as two major regulators of flower development in a broad range of angiosperm species. Recent research has revealed that UFO acts as a transcriptional cofactor, redirecting the LEAFY floral regulator to novel cis-elements. In this review, we summarize the various roles of UFO across species, analyze past results in light of new discoveries and highlight the key questions that remain to be solved.
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Affiliation(s)
- Philippe Rieu
- Laboratoire Physiologie Cellulaire et Végétale, Université Grenoble Alpes, CNRS, CEA, INRAE, IRIG-DBSCI-LPCV, 17 ave des martyrs, F-38054, Grenoble, France
| | - Moïra Arnoux-Courseaux
- Laboratoire Physiologie Cellulaire et Végétale, Université Grenoble Alpes, CNRS, CEA, INRAE, IRIG-DBSCI-LPCV, 17 ave des martyrs, F-38054, Grenoble, France
| | - Gabrielle Tichtinsky
- Laboratoire Physiologie Cellulaire et Végétale, Université Grenoble Alpes, CNRS, CEA, INRAE, IRIG-DBSCI-LPCV, 17 ave des martyrs, F-38054, Grenoble, France
| | - François Parcy
- Laboratoire Physiologie Cellulaire et Végétale, Université Grenoble Alpes, CNRS, CEA, INRAE, IRIG-DBSCI-LPCV, 17 ave des martyrs, F-38054, Grenoble, France
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3
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Dolde U, Muzzopappa F, Delesalle C, Neveu J, Erdel F, Vert G. LEAFY homeostasis is regulated via ubiquitin-dependent degradation and sequestration in cytoplasmic condensates. iScience 2023; 26:106880. [PMID: 37260753 PMCID: PMC10227421 DOI: 10.1016/j.isci.2023.106880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 04/06/2023] [Accepted: 05/11/2023] [Indexed: 06/02/2023] Open
Abstract
The transcription factor LEAFY (LFY) plays crucial roles in flower development by activating floral homeotic genes. Activation of LFY targets requires the combined action of LFY and the E3 ubiquitin ligase UFO, although the precise underlying mechanism remains unclear. Here, we show that LFY accumulates in biomolecular condensates within the cytoplasm, while recombinant LFY forms condensates with similar properties in vitro. UFO interacts with LFY within these condensates and marks it for degradation. LFY levels in the nucleus are buffered against changes in total LFY levels induced by proteasome inhibition, UFO overexpression, or mutation of lysine residues in a disordered region of LFY. Perturbation of cytoplasmic LFY condensates by 1,6-hexanediol treatment induces the relocalization of LFY to the nucleus and the subsequent activation of the LFY target AP3 in flowers. Our data suggest that nucleocytoplasmic partitioning, condensation, and ubiquitin-dependent degradation regulate LFY levels in the nucleus to control its activity.
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Affiliation(s)
- Ulla Dolde
- Plant Science Research Laboratory (LRSV), UMR5546 CNRS/University of Toulouse/Toulouse-INP, 24 chemin de Borde Rouge, 31320 Auzeville Tolosane, France
| | - Fernando Muzzopappa
- Center for Integrative Biology (CBI), Molecular, Cellular and Developmental Biology UMR5077 CNRS/University of Toulouse, 169 Avenue Marianne Grunberg-Manago, 31062 Toulouse Cedex, France
| | - Charlotte Delesalle
- Plant Science Research Laboratory (LRSV), UMR5546 CNRS/University of Toulouse/Toulouse-INP, 24 chemin de Borde Rouge, 31320 Auzeville Tolosane, France
| | - Julie Neveu
- Plant Science Research Laboratory (LRSV), UMR5546 CNRS/University of Toulouse/Toulouse-INP, 24 chemin de Borde Rouge, 31320 Auzeville Tolosane, France
| | - Fabian Erdel
- Center for Integrative Biology (CBI), Molecular, Cellular and Developmental Biology UMR5077 CNRS/University of Toulouse, 169 Avenue Marianne Grunberg-Manago, 31062 Toulouse Cedex, France
| | - Grégory Vert
- Plant Science Research Laboratory (LRSV), UMR5546 CNRS/University of Toulouse/Toulouse-INP, 24 chemin de Borde Rouge, 31320 Auzeville Tolosane, France
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4
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Szőke A, Sárkány O, Schermann G, Kapuy O, Diernfellner ACR, Brunner M, Gyöngyösi N, Káldi K. Adaptation to glucose starvation is associated with molecular reorganization of the circadian clock in Neurospora crassa. eLife 2023; 12:79765. [PMID: 36625037 PMCID: PMC9831608 DOI: 10.7554/elife.79765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 12/12/2022] [Indexed: 01/11/2023] Open
Abstract
The circadian clock governs rhythmic cellular functions by driving the expression of a substantial fraction of the genome and thereby significantly contributes to the adaptation to changing environmental conditions. Using the circadian model organism Neurospora crassa, we show that molecular timekeeping is robust even under severe limitation of carbon sources, however, stoichiometry, phosphorylation and subcellular distribution of the key clock components display drastic alterations. Protein kinase A, protein phosphatase 2 A and glycogen synthase kinase are involved in the molecular reorganization of the clock. RNA-seq analysis reveals that the transcriptomic response of metabolism to starvation is highly dependent on the positive clock component WC-1. Moreover, our molecular and phenotypic data indicate that a functional clock facilitates recovery from starvation. We suggest that the molecular clock is a flexible network that allows the organism to maintain rhythmic physiology and preserve fitness even under long-term nutritional stress.
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Affiliation(s)
- Anita Szőke
- Department of Physiology, Semmelweis UniversityBudapestHungary
| | - Orsolya Sárkány
- Department of Physiology, Semmelweis UniversityBudapestHungary
| | - Géza Schermann
- Department of Neurovascular Cellbiology, University Hospital BonnBonnGermany
| | - Orsolya Kapuy
- Department of Molecular Biology, Semmelweis UniversityBudapestHungary
| | | | | | - Norbert Gyöngyösi
- Department of Molecular Biology, Semmelweis UniversityBudapestHungary
| | - Krisztina Káldi
- Department of Physiology, Semmelweis UniversityBudapestHungary
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5
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Vriend J, Klonisch T. Genes of the Ubiquitin Proteasome System Qualify as Differential Markers in Malignant Glioma of Astrocytic and Oligodendroglial Origin. Cell Mol Neurobiol 2022; 43:1425-1452. [PMID: 35896929 PMCID: PMC10079750 DOI: 10.1007/s10571-022-01261-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 07/11/2022] [Indexed: 11/25/2022]
Abstract
We have mined public genomic datasets to identify genes coding for components of the ubiquitin proteasome system (UPS) that may qualify as potential diagnostic and therapeutic targets in the three major glioma types, astrocytoma (AS), glioblastoma (GBM), and oligodendroglioma (ODG). In the Sun dataset of glioma (GEO ID: GSE4290), expression of the genes UBE2S and UBE2C, which encode ubiquitin conjugases important for cell-cycle progression, distinguished GBM from AS and ODG. KEGG analysis showed that among the ubiquitin E3 ligase genes differentially expressed, the Notch pathway was significantly over-represented, whereas among the E3 ligase adaptor genes the Hippo pathway was over-represented. We provide evidence that the UPS gene contributions to the Notch and Hippo pathway signatures are related to stem cell pathways and can distinguish GBM from AS and ODG. In the Sun dataset, AURKA and TPX2, two cell-cycle genes coding for E3 ligases, and the cell-cycle gene coding for the E3 adaptor CDC20 were upregulated in GBM. E3 ligase adaptor genes differentially expressed were also over-represented for the Hippo pathway and were able to distinguish classic, mesenchymal, and proneural subtypes of GBM. Also over-expressed in GBM were PSMB8 and PSMB9, genes encoding subunits of the immunoproteasome. Our transcriptome analysis provides a strong rationale for UPS members as attractive therapeutic targets for the development of more effective treatment strategies in malignant glioma. Ubiquitin proteasome system and glioblastoma: E1-ubiquitin-activating enzyme, E2-ubiquitin-conjugating enzyme, E3-ubiquitin ligase. Ubiquitinated substrates of E3 ligases may be degraded by the proteasome. Expression of genes for specific E2 conjugases, E3 ligases, and genes for proteasome subunits may serve as differential markers of subtypes of glioblastoma.
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Affiliation(s)
- Jerry Vriend
- Department of Human Anatomy and Cell Science, Max Rady College of Medicine, Max Rady Faculty of Health Sciences, University of Manitoba, Rm34, BMSB, 745 Bannatyne Ave, Winnipeg, MB, R3E0J9, Canada.
| | - Thomas Klonisch
- Department of Human Anatomy and Cell Science, Max Rady College of Medicine, Max Rady Faculty of Health Sciences, University of Manitoba, Rm34, BMSB, 745 Bannatyne Ave, Winnipeg, MB, R3E0J9, Canada
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6
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Budroni V, Versteeg GA. Negative Regulation of the Innate Immune Response through Proteasomal Degradation and Deubiquitination. Viruses 2021; 13:584. [PMID: 33808506 PMCID: PMC8066222 DOI: 10.3390/v13040584] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 03/26/2021] [Accepted: 03/27/2021] [Indexed: 12/25/2022] Open
Abstract
The rapid and dynamic activation of the innate immune system is achieved through complex signaling networks regulated by post-translational modifications modulating the subcellular localization, activity, and abundance of signaling molecules. Many constitutively expressed signaling molecules are present in the cell in inactive forms, and become functionally activated once they are modified with ubiquitin, and, in turn, inactivated by removal of the same post-translational mark. Moreover, upon infection resolution a rapid remodeling of the proteome needs to occur, ensuring the removal of induced response proteins to prevent hyperactivation. This review discusses the current knowledge on the negative regulation of innate immune signaling pathways by deubiquitinating enzymes, and through degradative ubiquitination. It focusses on spatiotemporal regulation of deubiquitinase and E3 ligase activities, mechanisms for re-establishing proteostasis, and degradation through immune-specific feedback mechanisms vs. general protein quality control pathways.
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Affiliation(s)
| | - Gijs A. Versteeg
- Max Perutz Labs, Department of Microbiology, Immunobiology, and Genetics, University of Vienna, Vienna Biocenter (VBC), 1030 Vienna, Austria;
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7
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Spielmann J, Vert G. The many facets of protein ubiquitination and degradation in plant root iron-deficiency responses. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:2071-2082. [PMID: 32945865 DOI: 10.1093/jxb/eraa441] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 09/16/2020] [Indexed: 06/11/2023]
Abstract
Organisms need to deal with the absolute requirement for metals and also their possible toxicity. This is achieved through an intricate network of signaling pathways that are integrated to ultimately fine-tune iron uptake and metabolism. The mechanisms by which plants cope with iron limitation and the associated genomic responses are well characterized. On top of this transcriptional cascade is another level of regulation involving the post-translational protein modification and degradation. The ubiquitination and/or degradation of several transcription factors in the iron-deficiency signaling pathways and metal transporters has recently come to light. In this review we discuss the mechanisms and possible roles of protein modification and turnover in the regulation of root iron-deficiency responses. We also highlight the tight coupling between metal sensing by E3 ubiquitin ligases or bifunctional transporters and protein degradation.
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Affiliation(s)
- Julien Spielmann
- Plant Science Research Laboratory (LRSV), UMR5546 CNRS/Université Toulouse 3, 24 chemin de Borde Rouge, Auzeville-Tolosane, France
| | - Grégory Vert
- Plant Science Research Laboratory (LRSV), UMR5546 CNRS/Université Toulouse 3, 24 chemin de Borde Rouge, Auzeville-Tolosane, France
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8
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Vriend J, Rastegar M. Ubiquitin ligases and medulloblastoma: genetic markers of the four consensus subgroups identified through transcriptome datasets. Biochim Biophys Acta Mol Basis Dis 2020; 1866:165839. [PMID: 32445667 DOI: 10.1016/j.bbadis.2020.165839] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 04/23/2020] [Accepted: 05/13/2020] [Indexed: 01/05/2023]
Abstract
The ubiquitin proteasome system regulates key cellular processes in normal and in cancer cells. Herein, we review published data on the role of ubiquitin ligases in the four major subgroups of medulloblastoma (MB). While conventional literature serves as an initial source of information on cellular pathways in MB, large publicly available datasets of gene expression can be used to add information not previously identified in the literature. By analysing the publicly available Cavalli dataset, we show that increased expression of ZNRF3 characterizes the WNT subgroup of MB. The ZNRF3 gene codes for an E3 ligase associated with WNT receptors. Loss of a copy of chromosome 6 in a subtype of the WNT group was associated with decreased expression of the gene encoding the E3 ligase RNF146. While the E3 ligase SMURF regulates SHH receptors, increased expression of the gene encoding the Cullin Ring E3 adaptor PPP2R2C was statistically a better genetic marker of the SHH group. Genes whose expression was statistically strongly related to Group 3 included the E3 ligase gene TRIM58, and the gene for the E3 ligase adaptor, PPP2R2B. Group 4 MB was associated with expression of genes encoding several E3 ligases and E3 ligase adaptors involved in ribosome biogenesis. Increased expression of the genes encoding the E3 ligase adaptors and transcription repressors ZBTB18 and ZBTB38 were also noted in subgroup 4. These data suggest that several E3 ligases and their adaptors should be investigated as therapeutic targets for subgroup specific MB brain tumors.
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Affiliation(s)
- Jerry Vriend
- Department of Human Anatomy and Cell Science, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada.
| | - Mojgan Rastegar
- Department of Biochemistry and Medical Genetics and Regenerative Medicine Program, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba R3E 0J9, Canada
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9
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Beker MC, Caglayan B, Caglayan AB, Kelestemur T, Yalcin E, Caglayan A, Kilic U, Baykal AT, Reiter RJ, Kilic E. Interaction of melatonin and Bmal1 in the regulation of PI3K/AKT pathway components and cellular survival. Sci Rep 2019; 9:19082. [PMID: 31836786 PMCID: PMC6910929 DOI: 10.1038/s41598-019-55663-0] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 11/22/2019] [Indexed: 01/08/2023] Open
Abstract
The circadian rhythm is driven by a master clock within the suprachiasmatic nucleus which regulates the rhythmic secretion of melatonin. Bmal1 coordinates the rhythmic expression of transcriptome and regulates biological activities, involved in cell metabolism and aging. However, the role of Bmal1 in cellular- survival, signaling, its interaction with intracellular proteins, and how melatonin regulates its expression is largely unclear. Here we observed that melatonin increases the expression of Bmal1 and both melatonin and Bmal1 increase cellular survival after oxygen glucose deprivation (OGD) while the inhibition of Bmal1 resulted in the decreased cellular survival without affecting neuroprotective effects of melatonin. By using a planar surface immunoassay for PI3K/AKT signaling pathway components, we revealed that both melatonin and Bmal1 increased phosphorylation of AKT, ERK-1/2, PDK1, mTOR, PTEN, GSK-3αβ, and p70S6K. In contrast, inhibition of Bmal1 resulted in decreased phosphorylation of these proteins, which the effect of melatonin on these signaling molecules was not affected by the absence of Bmal1. Besides, the inhibition of PI3K/AKT decreased Bmal1 expression and the effect of melatonin on Bmal1 after both OGD in vitro and focal cerebral ischemia in vivo. Our data demonstrate that melatonin controls the expression of Bmal1 via PI3K/AKT signaling, and Bmal1 plays critical roles in cellular survival via activation of survival kinases.
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Affiliation(s)
- Mustafa C Beker
- Regenerative and Restorative Medicine Research Center, Istanbul Medipol University, 34810, Istanbul, Turkey
- Department of Physiology, School of Medicine, Istanbul Medipol University, 34810, Istanbul, Turkey
| | - Berrak Caglayan
- Regenerative and Restorative Medicine Research Center, Istanbul Medipol University, 34810, Istanbul, Turkey
- Department of Medical Biology, International School of Medicine, Istanbul Medipol University, 34810, Istanbul, Turkey
| | - Ahmet B Caglayan
- Regenerative and Restorative Medicine Research Center, Istanbul Medipol University, 34810, Istanbul, Turkey
- Department of Physiology, School of Medicine, Istanbul Medipol University, 34810, Istanbul, Turkey
| | - Taha Kelestemur
- Regenerative and Restorative Medicine Research Center, Istanbul Medipol University, 34810, Istanbul, Turkey
- Department of Physiology, School of Medicine, Istanbul Medipol University, 34810, Istanbul, Turkey
| | - Esra Yalcin
- Regenerative and Restorative Medicine Research Center, Istanbul Medipol University, 34810, Istanbul, Turkey
- Department of Physiology, School of Medicine, Istanbul Medipol University, 34810, Istanbul, Turkey
| | - Aysun Caglayan
- Regenerative and Restorative Medicine Research Center, Istanbul Medipol University, 34810, Istanbul, Turkey
- Department of Physiology, School of Medicine, Istanbul Medipol University, 34810, Istanbul, Turkey
| | - Ulkan Kilic
- Department of Medical Biology, School of Medicine, University of Health Sciences, 34668, Istanbul, Turkey
| | - Ahmet T Baykal
- Department of Medical Biochemistry, School of Medicine, Acibadem Mehmet Ali Aydinlar University, 34752, Istanbul, Turkey
| | - Russel J Reiter
- Department of Cell Systems and Anatomy, UT Health San Antonio, 78229, Texas, USA
| | - Ertugrul Kilic
- Regenerative and Restorative Medicine Research Center, Istanbul Medipol University, 34810, Istanbul, Turkey.
- Department of Physiology, School of Medicine, Istanbul Medipol University, 34810, Istanbul, Turkey.
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10
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Skelly MJ, Furniss JJ, Grey H, Wong KW, Spoel SH. Dynamic ubiquitination determines transcriptional activity of the plant immune coactivator NPR1. eLife 2019; 8:47005. [PMID: 31589140 PMCID: PMC6850887 DOI: 10.7554/elife.47005] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 10/05/2019] [Indexed: 01/27/2023] Open
Abstract
Activation of systemic acquired resistance in plants is associated with transcriptome reprogramming induced by the unstable coactivator NPR1. Immune-induced ubiquitination and proteasomal degradation of NPR1 are thought to facilitate continuous delivery of active NPR1 to target promoters, thereby maximising gene expression. Because of this potentially costly sacrificial process, we investigated if ubiquitination of NPR1 plays transcriptional roles prior to its proteasomal turnover. Here we show ubiquitination of NPR1 is a progressive event in which initial modification by a Cullin-RING E3 ligase promotes its chromatin association and expression of target genes. Only when polyubiquitination of NPR1 is enhanced by the E4 ligase, UBE4, it is targeted for proteasomal degradation. Conversely, ubiquitin ligase activities are opposed by UBP6/7, two proteasome-associated deubiquitinases that enhance NPR1 longevity. Thus, immune-induced transcriptome reprogramming requires sequential actions of E3 and E4 ligases balanced by opposing deubiquitinases that fine-tune activity of NPR1 without strict requirement for its sacrificial turnover.
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Affiliation(s)
- Michael J Skelly
- Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - James J Furniss
- Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Heather Grey
- Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Ka-Wing Wong
- Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Steven H Spoel
- Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
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11
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Brignall R, Moody AT, Mathew S, Gaudet S. Considering Abundance, Affinity, and Binding Site Availability in the NF-κB Target Selection Puzzle. Front Immunol 2019; 10:609. [PMID: 30984185 PMCID: PMC6450194 DOI: 10.3389/fimmu.2019.00609] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 03/07/2019] [Indexed: 12/21/2022] Open
Abstract
The NF-κB transcription regulation system governs a diverse set of responses to various cytokine stimuli. With tools from in vitro biochemical characterizations, to omics-based whole genome investigations, great strides have been made in understanding how NF-κB transcription factors control the expression of specific sets of genes. Nonetheless, these efforts have also revealed a very large number of potential binding sites for NF-κB in the human genome, and a puzzle emerges when trying to explain how NF-κB selects from these many binding sites to direct cell-type- and stimulus-specific gene expression patterns. In this review, we surmise that target gene transcription can broadly be thought of as a function of the nuclear abundance of the various NF-κB dimers, the affinity of NF-κB dimers for the regulatory sequence and the availability of this regulatory site. We use this framework to place quantitative information that has been gathered about the NF-κB transcription regulation system into context and thus consider questions it answers, and questions it raises. We end with a brief discussion of some of the future prospects that new approaches could bring to our understanding of how NF-κB transcription factors orchestrate diverse responses in different biological contexts.
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Affiliation(s)
- Ruth Brignall
- Center for Cancer Systems Biology and Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, United States.,Department of Genetics, Harvard Medical School, Blavatnik Institute, Boston, MA, United States
| | - Amy T Moody
- Center for Cancer Systems Biology and Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, United States.,Department of Genetics, Harvard Medical School, Blavatnik Institute, Boston, MA, United States.,Laboratory for Systems Pharmacology, Harvard Medical School, Blavatnik Institute, Boston, MA, United States.,Department of Microbiology, Tufts University School of Medicine, Boston, MA, United States
| | - Shibin Mathew
- Center for Cancer Systems Biology and Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, United States.,Department of Genetics, Harvard Medical School, Blavatnik Institute, Boston, MA, United States
| | - Suzanne Gaudet
- Center for Cancer Systems Biology and Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, United States.,Department of Genetics, Harvard Medical School, Blavatnik Institute, Boston, MA, United States
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12
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Miricescu A, Goslin K, Graciet E. Ubiquitylation in plants: signaling hub for the integration of environmental signals. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:4511-4527. [PMID: 29726957 DOI: 10.1093/jxb/ery165] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 04/27/2018] [Indexed: 05/20/2023]
Abstract
A fundamental question in biology is how organisms integrate the plethora of environmental cues that they perceive to trigger a co-ordinated response. The regulation of protein stability, which is largely mediated by the ubiquitin-proteasome system in eukaryotes, plays a pivotal role in these processes. Due to their sessile lifestyle and the need to respond rapidly to a multitude of environmental factors, plants are thought to be especially dependent on proteolysis to regulate cellular processes. In this review, we present the complexity of the ubiquitin system in plants, and discuss the relevance of the proteolytic and non-proteolytic roles of this system in the regulation and co-ordination of plant responses to environmental signals. We also discuss the role of the ubiquitin system as a key regulator of plant signaling pathways. We focus more specifically on the functions of E3 ligases as regulators of the jasmonic acid (JA), salicylic acid (SA), and ethylene hormone signaling pathways that play important roles to mount a co-ordinated response to multiple environmental stresses. We also provide examples of new players in this field that appear to integrate different cues and signaling pathways.
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Affiliation(s)
- Alexandra Miricescu
- Department of Biology, National University of Ireland Maynooth, Maynooth, Ireland
| | - Kevin Goslin
- Department of Biology, National University of Ireland Maynooth, Maynooth, Ireland
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13
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Geng S, Miyagi A, Umen JG. Evolutionary divergence of the sex-determining gene MID uncoupled from the transition to anisogamy in volvocine algae. Development 2018; 145:dev.162537. [PMID: 29549112 DOI: 10.1242/dev.162537] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 03/13/2018] [Indexed: 12/28/2022]
Abstract
Volvocine algae constitute a unique comparative model for investigating the evolution of oogamy from isogamous mating types. The sex- or mating type-determining gene MID encodes a conserved RWP-RK transcription factor found in either the MT- or male mating locus of dioecious volvocine species. We previously found that MID from the isogamous species Chlamydomonas reinhardtii (CrMID) could not induce ectopic spermatogenesis when expressed heterologously in Volvox carteri females, suggesting coevolution of Mid function with gamete dimorphism. Here we found that ectopic expression of MID from the anisogamous species Pleodorina starrii (PsMID) could efficiently induce spermatogenesis when expressed in V. carteri females and, unexpectedly, that GpMID from the isogamous species Gonium pectorale was also able to induce V. carteri spermatogenesis. Neither VcMID nor GpMID could complement a C. reinhardtii mid mutant, at least partly owing to instability of heterologous Mid proteins. Our data show that Mid divergence was not a major contributor to the transition between isogamy and anisogamy/oogamy in volvocine algae, and instead implicate changes in cis-regulatory interactions and/or trans-acting factors of the Mid network in the evolution of sexual dimorphism.
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Affiliation(s)
- Sa Geng
- Donald Danforth Plant Science Center, 975 N. Warson Rd., St. Louis, MO 63132, USA
| | - Ayano Miyagi
- Donald Danforth Plant Science Center, 975 N. Warson Rd., St. Louis, MO 63132, USA
| | - James G Umen
- Donald Danforth Plant Science Center, 975 N. Warson Rd., St. Louis, MO 63132, USA
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14
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Gierisch ME, Pfistner F, Lopez-Garcia LA, Harder L, Schäfer BW, Niggli FK. Proteasomal Degradation of the EWS-FLI1 Fusion Protein Is Regulated by a Single Lysine Residue. J Biol Chem 2016; 291:26922-26933. [PMID: 27875302 DOI: 10.1074/jbc.m116.752063] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 11/01/2016] [Indexed: 12/26/2022] Open
Abstract
E-26 transformation-specific (ETS) proteins are transcription factors directing gene expression through their conserved DNA binding domain. They are implicated as truncated forms or interchromosomal rearrangements in a variety of tumors including Ewing sarcoma, a pediatric tumor of the bone. Tumor cells express the chimeric oncoprotein EWS-FLI1 from a specific t(22;11)(q24;12) translocation. EWS-FLI1 harbors a strong transactivation domain from EWSR1 and the DNA-binding ETS domain of FLI1 in the C-terminal part of the protein. Although Ewing cells are crucially dependent on continuous expression of EWS-FLI1, its regulation of turnover has not been characterized in detail. Here, we identify the EWS-FLI1 protein as a substrate of the ubiquitin-proteasome system with a characteristic polyubiquitination pattern. Using a global protein stability approach, we determined the half-life of EWS-FLI1 to lie between 2 and 4 h, whereas full-length EWSR1 and FLI1 were more stable. By mass spectrometry, we identified two ubiquitin acceptor lysine residues of which only mutation of Lys-380 in the ETS domain of the FLI1 part abolished EWS-FLI1 ubiquitination and stabilized the protein posttranslationally. Expression of this highly stable mutant protein in Ewing cells while simultaneously depleting the endogenous wild type protein differentially modulates two subgroups of target genes to be either EWS-FLI1 protein-dependent or turnover-dependent. The majority of target genes are in an unaltered state and cannot be further activated. Our study provides novel insights into EWS-FLI1 turnover, a critical pathway in Ewing sarcoma pathogenesis, and lays new ground to develop novel therapeutic strategies in Ewing sarcoma.
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Affiliation(s)
- Maria E Gierisch
- From the Department of Oncology and Children's Research Center, University Children's Hospital, Steinwiesstrasse 32, 8032 Zurich, Switzerland
| | - Franziska Pfistner
- From the Department of Oncology and Children's Research Center, University Children's Hospital, Steinwiesstrasse 32, 8032 Zurich, Switzerland
| | - Laura A Lopez-Garcia
- From the Department of Oncology and Children's Research Center, University Children's Hospital, Steinwiesstrasse 32, 8032 Zurich, Switzerland
| | - Lena Harder
- From the Department of Oncology and Children's Research Center, University Children's Hospital, Steinwiesstrasse 32, 8032 Zurich, Switzerland
| | - Beat W Schäfer
- From the Department of Oncology and Children's Research Center, University Children's Hospital, Steinwiesstrasse 32, 8032 Zurich, Switzerland
| | - Felix K Niggli
- From the Department of Oncology and Children's Research Center, University Children's Hospital, Steinwiesstrasse 32, 8032 Zurich, Switzerland
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15
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Kodadek T, McEnaney PJ. Towards vast libraries of scaffold-diverse, conformationally constrained oligomers. Chem Commun (Camb) 2016; 52:6038-59. [PMID: 26996593 PMCID: PMC4846527 DOI: 10.1039/c6cc00617e] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
There is great interest in the development of probe molecules and drug leads that would bind tightly and selectively to protein surfaces that are difficult to target with traditional molecules, such as those involved in protein-protein interactions. The currently available evidence suggests that this will require molecules that are larger and have quite different chemical properties than typical Lipinski-compliant molecules that target enzyme active sites. We describe here efforts to develop vast libraries of conformationally constrained oligomers as a potentially rich source of these molecules.
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Affiliation(s)
- Thomas Kodadek
- Departments of Chemistry and Cancer Biology, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA.
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16
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Maneix L, Catic A. Touch and go: nuclear proteolysis in the regulation of metabolic genes and cancer. FEBS Lett 2016; 590:908-23. [PMID: 26832397 PMCID: PMC4833644 DOI: 10.1002/1873-3468.12087] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 01/15/2016] [Accepted: 01/26/2016] [Indexed: 01/07/2023]
Abstract
The recruitment of transcription factors to promoters and enhancers is a critical step in gene regulation. Many of these proteins are quickly removed from DNA after they completed their function. Metabolic genes in particular are dynamically regulated and continuously adjusted to cellular requirements. Transcription factors controlling metabolism are therefore under constant surveillance by the ubiquitin–proteasome system, which can degrade DNA‐bound proteins in a site‐specific manner. Several of these metabolic transcription factors are critical to cancer cells, as they promote uncontrolled growth and proliferation. This review highlights recent findings in the emerging field of nuclear proteolysis and outlines novel paradigms for cancer treatment, with an emphasis on multiple myeloma.
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Affiliation(s)
- Laure Maneix
- Huffington Center on Aging, Baylor College of Medicine, Houston, TX, USA.,Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, USA
| | - André Catic
- Huffington Center on Aging, Baylor College of Medicine, Houston, TX, USA.,Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, USA.,Stem Cells and Regenerative Medicine Center, Baylor College of Medicine, Houston, TX, USA.,Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
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17
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Beaulieu YB, Leon Machado JA, Ethier S, Gaudreau L, Steimle V. Degradation, Promoter Recruitment and Transactivation Mediated by the Extreme N-Terminus of MHC Class II Transactivator CIITA Isoform III. PLoS One 2016; 11:e0148753. [PMID: 26871568 PMCID: PMC4752451 DOI: 10.1371/journal.pone.0148753] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 01/22/2016] [Indexed: 12/17/2022] Open
Abstract
Multiple relationships between ubiquitin-proteasome mediated protein turnover and transcriptional activation have been well documented, but the underlying mechanisms are still poorly understood. One way to induce degradation is via ubiquitination of the N-terminal α-amino group of proteins. The major histocompatibility complex (MHC) class II transactivator CIITA is the master regulator of MHC class II gene expression and we found earlier that CIITA is a short-lived protein. Using stable and transient transfections of different CIITA constructs into HEK-293 and HeLa cell lines, we show here that the extreme N-terminal end of CIITA isoform III induces both rapid degradation and transactivation. It is essential that this sequence resides at the N-terminal end of the protein since blocking of the N-terminal end with an epitope-tag stabilizes the protein and reduces transactivation potential. The first ten amino acids of CIITA isoform III act as a portable degron and transactivation sequence when transferred as N-terminal extension to truncated CIITA constructs and are also able to destabilize a heterologous protein. The same is observed with the N-terminal ends of several known N-terminal ubiquitination substrates, such as Id2, Cdt1 and MyoD. Arginine and proline residues within the N-terminal ends contribute to rapid turnover. The N-terminal end of CIITA isoform III is responsible for efficient in vivo recruitment to the HLA-DRA promoter and increased interaction with components of the transcription machinery, such as TBP, p300, p400/Domino, the 19S ATPase S8, and the MHC-II promoter binding complex RFX. These experiments reveal a novel function of free N-terminal ends of proteins in degradation-dependent transcriptional activation.
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Affiliation(s)
- Yves B. Beaulieu
- Département de biologie, Université de Sherbrooke, Sherbrooke, Qc, Canada
| | | | - Sylvain Ethier
- Département de biologie, Université de Sherbrooke, Sherbrooke, Qc, Canada
| | - Luc Gaudreau
- Département de biologie, Université de Sherbrooke, Sherbrooke, Qc, Canada
| | - Viktor Steimle
- Département de biologie, Université de Sherbrooke, Sherbrooke, Qc, Canada
- * E-mail:
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18
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Vriend J, Reiter RJ. Breast cancer cells: Modulation by melatonin and the ubiquitin-proteasome system--a review. Mol Cell Endocrinol 2015; 417:1-9. [PMID: 26363225 DOI: 10.1016/j.mce.2015.09.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 09/01/2015] [Indexed: 02/07/2023]
Abstract
Melatonin inhibits human breast cancer cells stimulated with estrogen. This antiproliferative action depends on the presence of the estrogen receptor alpha (ERα) in the human MCF-7 cell line and is strictly dose-dependent. Since researchers concerned with melatonin and breast cancer have not considered the relevance of the ubiquitin-proteasome system to this research in this review we do so. The fact that the first breast cancer susceptibility gene to be identified, Brca1, functions as a ubiquitin ligase indicates that the ubiquitin-proteasome system has a role in regulating susceptibility to breast cancer. While mutations of this gene increase the incidence of breast cancer, the wild type gene suppresses estrogen-dependent transcriptional events relying on the estrogen receptor ERα. Three other ubiquitin ligases, SCF(Skp2), E6AP and APC, interact directly with ERα at the ERE and AP-1 promoters of ERα target genes. Melatonin, like proteasome inhibitors, decreases estrogen-induced gene transcription. Indeed, it has been reported that melatonin specifically inhibits estrogen-induced transcription mediated by ERα at the ERE and AP1 gene promoters. Herein, we present a model in which the inhibitory action of melatonin on MCF-7 cells is mediated, directly or indirectly, by the ubiquitin-proteasome system. In this model ERα, apoptotic proteins, and cell cycle proteins, all influenced by melatonin, are substrates of key ubiquitin ligases including SCF(Skp2), E6AP, and SCF(B-TrCP). Since dysfunction of the ubiquitin-proteasome system is a risk factor for breast cancer, this model provides a context in which to test the clinical potential, and limitations, of melatonin and proteasome inhibitors.
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Affiliation(s)
- Jerry Vriend
- Department of Human Anatomy and Cell Science, University of Manitoba, Winnipeg, MB, Canada.
| | - Russel J Reiter
- Department of Cellular and Structural Biology, UT Health Science Center San Antonio, TX, USA
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19
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Upadhyay A, Amanullah A, Chhangani D, Mishra R, Mishra A. Selective multifaceted E3 ubiquitin ligases barricade extreme defense: Potential therapeutic targets for neurodegeneration and ageing. Ageing Res Rev 2015; 24:138-59. [PMID: 26247845 DOI: 10.1016/j.arr.2015.07.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2015] [Revised: 06/24/2015] [Accepted: 07/30/2015] [Indexed: 12/24/2022]
Abstract
Efficient and regular performance of Ubiquitin Proteasome System and Autophagy continuously eliminate deleterious accumulation of nonnative protiens. In cellular quality control system, E3 ubiquitin ligases are significant employees for defense mechanism against abnormal toxic proteins. Few findings indicate that lack of functions of E3 ubiquitin ligases can be a causative factor of neurodevelopmental disorders, neurodegeneration, cancer and ageing. However, the detailed molecular pathomechanism implying E3 ubiquitin ligases in cellular functions in multifactorial disease conditions are not well understood. This article systematically represents the unique characteristics, molecular nature, and recent developments in the knowledge of neurobiological functions of few crucial E3 ubiquitin ligases. Here, we review recent literature on the roles of E6-AP, HRD1 and ITCH E3 ubiquitin ligases in the neuro-pathobiological mechanisms, with precise focus on the processes of neurodegeneration, and thereby propose new lines of potential targets for therapeutic interventions.
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20
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Hill K. Post-translational modifications of hormone-responsive transcription factors: the next level of regulation. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:4933-45. [PMID: 26041319 DOI: 10.1093/jxb/erv273] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Plants exhibit a high level of developmental plasticity and growth is responsive to multiple developmental and environmental cues. Hormones are small endogenous signalling molecules which are fundamental to this phenotypic plasticity. Post-translational modifications of proteins are a central feature of the signal transduction pathways that regulate gene transcription in response to hormones. Modifications that affect the function of transcriptional regulators may also serve as a mechanism to incorporate multiple signals, mediate cross-talk, and modulate specific responses. This review discusses recent research that suggests hormone-responsive transcription factors are subject to multiple modifications which imply an additional level of regulation conferred by enzymes that mediate specific modifications, such as phosphorylation, ubiquitination, SUMOylation, and S-nitrosylation. These modifications can affect protein stability, sub-cellular localization, interactions with co-repressors and activators, and DNA binding. The focus here is on direct cross-talk involving transcription factors downstream of auxin, brassinosteroid, and gibberellin signalling. However, many of the concepts discussed are more broadly relevant to questions of how plants can modify their growth by regulating subsets of genes in response to multiple cues.
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Affiliation(s)
- Kristine Hill
- Plant Sciences Division and Centre for Plant Integrative Biology, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
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21
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Pireyre M, Burow M. Regulation of MYB and bHLH transcription factors: a glance at the protein level. MOLECULAR PLANT 2015; 8:378-88. [PMID: 25667003 DOI: 10.1016/j.molp.2014.11.022] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 11/10/2014] [Accepted: 11/24/2014] [Indexed: 05/07/2023]
Abstract
In complex, constantly changing environments, plants have developed astonishing survival strategies. These elaborated strategies rely on rapid and precise gene regulation mediated by transcription factors (TFs). TFs represent a large fraction of plant genomes and among them, MYBs and basic helix-loop-helix (bHLHs) have unique inherent properties specific to plants. Proteins of these two TF families can act as homo- or heterodimers, associate with proteins from other protein families, or form MYB/bHLH complexes to regulate distinct cellular processes. The ability of MYBs and bHLHs to interact with multiple protein partners has evolved to keep up with the increased metabolic complexity of multi-cellular organisms. Association and disassociation of dynamic TF complexes in response to developmental and environmental cues are controlled through a plethora of regulatory mechanisms specifically modulating TF activity. Regulation of TFs at the protein level is critical for efficient and precise control of their activity, and thus provides the mechanistic basis for a rapid on-and-off switch of TF activity. In this review, examples of post-translational modifications, protein-protein interactions, and subcellular mobilization of TFs are discussed with regard to the relevance of these regulatory mechanisms for the specific activation of MYBs and bHLHs in response to a given environmental stimulus.
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Affiliation(s)
- Marie Pireyre
- DynaMo DNRF Center of Excellence, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark
| | - Meike Burow
- DynaMo DNRF Center of Excellence, Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark.
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22
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Vriend J, Reiter RJ. Melatonin feedback on clock genes: a theory involving the proteasome. J Pineal Res 2015; 58:1-11. [PMID: 25369242 DOI: 10.1111/jpi.12189] [Citation(s) in RCA: 167] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 10/30/2014] [Indexed: 12/11/2022]
Abstract
The expression of 'clock' genes occurs in all tissues, but especially in the suprachiasmatic nuclei (SCN) of the hypothalamus, groups of neurons in the brain that regulate circadian rhythms. Melatonin is secreted by the pineal gland in a circadian manner as influenced by the SCN. There is also considerable evidence that melatonin, in turn, acts on the SCN directly influencing the circadian 'clock' mechanisms. The most direct route by which melatonin could reach the SCN would be via the cerebrospinal fluid of the third ventricle. Melatonin could also reach the pars tuberalis (PT) of the pituitary, another melatonin-sensitive tissue, via this route. The major 'clock' genes include the period genes, Per1 and Per2, the cryptochrome genes, Cry1 and Cry2, the clock (circadian locomotor output cycles kaput) gene, and the Bmal1 (aryl hydrocarbon receptor nuclear translocator-like) gene. Clock and Bmal1 heterodimers act on E-box components of the promoters of the Per and Cry genes to stimulate transcription. A negative feedback loop between the cryptochrome proteins and the nucleus allows the Cry and Per proteins to regulate their own transcription. A cycle of ubiquitination and deubiquitination controls the levels of CRY protein degraded by the proteasome and, hence, the amount of protein available for feedback. Thus, it provides a post-translational component to the circadian clock mechanism. BMAL1 also stimulates transcription of REV-ERBα and, in turn, is also partially regulated by negative feedback by REV-ERBα. In the 'black widow' model of transcription, proteasomes destroy transcription factors that are needed only for a particular period of time. In the model proposed herein, the interaction of melatonin and the proteasome is required to adjust the SCN clock to changes in the environmental photoperiod. In particular, we predict that melatonin inhibition of the proteasome interferes with negative feedback loops (CRY/PER and REV-ERBα) on Bmal1 transcription genes in both the SCN and PT. Melatonin inhibition of the proteasome would also tend to stabilize BMAL1 protein itself in the SCN, particularly at night when melatonin is naturally elevated. Melatonin inhibition of the proteasome could account for the effects of melatonin on circadian rhythms associated with molecular timing genes. The interaction of melatonin with the proteasome in the hypothalamus also provides a model for explaining the dramatic 'time of day' effect of melatonin injections on reproductive status of seasonal breeders. Finally, the model predicts that a proteasome inhibitor such as bortezomib would modify circadian rhythms in a manner similar to melatonin.
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Affiliation(s)
- Jerry Vriend
- Department of Human Anatomy and Cell Science, University of Manitoba, Winnipeg, MB, Canada
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23
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Furniss JJ, Spoel SH. Cullin-RING ubiquitin ligases in salicylic acid-mediated plant immune signaling. FRONTIERS IN PLANT SCIENCE 2015; 6:154. [PMID: 25821454 PMCID: PMC4358073 DOI: 10.3389/fpls.2015.00154] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 02/26/2015] [Indexed: 05/19/2023]
Abstract
Plant immune responses against biotrophic pathogens are regulated by the signaling hormone salicylic acid (SA). SA establishes immunity by regulating a variety of cellular processes, including programmed cell death (PCD) to isolate and kill invading pathogens, and development of systemic acquired resistance (SAR) which provides long-lasting, broad-spectrum resistance throughout the plant. Central to these processes is post-translational modification of SA-regulated signaling proteins by ubiquitination, i.e., the covalent addition of small ubiquitin proteins. Emerging evidence indicates SA-induced protein ubiquitination is largely orchestrated by Cullin-RING ligases (CRLs), which recruit specific substrates for ubiquitination using interchangeable adaptors. Ligation of ubiquitin chains interlinked at lysine 48 leads to substrate degradation by the 26S proteasome. Here we discuss how CRL-mediated degradation of both nucleotide-binding/leucine-rich repeat domain containing immune receptors and SA-induced transcription regulators are critical for functional PCD and SAR responses, respectively. By placing these recent findings in context of knowledge gained in other eukaryotic model species, we highlight potential alternative roles for processive ubiquitination in regulating the activity of SA-mediated immune responses.
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Affiliation(s)
| | - Steven H. Spoel
- *Correspondence: Steven H. Spoel, Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JR, UK
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24
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Sung MH, Guertin MJ, Baek S, Hager GL. DNase footprint signatures are dictated by factor dynamics and DNA sequence. Mol Cell 2014; 56:275-285. [PMID: 25242143 DOI: 10.1016/j.molcel.2014.08.016] [Citation(s) in RCA: 141] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Revised: 05/05/2014] [Accepted: 08/15/2014] [Indexed: 12/13/2022]
Abstract
Genomic footprinting has emerged as an unbiased discovery method for transcription factor (TF) occupancy at cognate DNA in vivo. A basic premise of footprinting is that sequence-specific TF-DNA interactions are associated with localized resistance to nucleases, leaving observable signatures of cleavage within accessible chromatin. This phenomenon is interpreted to imply protection of the critical nucleotides by the stably bound protein factor. However, this model conflicts with previous reports of many TFs exchanging with specific binding sites in living cells on a timescale of seconds. We show that TFs with short DNA residence times have no footprints at bound motif elements. Moreover, the nuclease cleavage profile within a footprint originates from the DNA sequence in the factor-binding site, rather than from the protein occupying specific nucleotides. These findings suggest a revised understanding of TF footprinting and reveal limitations in comprehensive reconstruction of the TF regulatory network using this approach.
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Affiliation(s)
- Myong-Hee Sung
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, NIH, Building 41, 41 Library Drive, Bethesda, MD 20892, USA
| | - Michael J Guertin
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, NIH, Building 41, 41 Library Drive, Bethesda, MD 20892, USA
| | - Songjoon Baek
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, NIH, Building 41, 41 Library Drive, Bethesda, MD 20892, USA
| | - Gordon L Hager
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, NIH, Building 41, 41 Library Drive, Bethesda, MD 20892, USA.
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25
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The 26S proteasome and initiation of gene transcription. Biomolecules 2014; 4:827-47. [PMID: 25211636 PMCID: PMC4192674 DOI: 10.3390/biom4030827] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 08/20/2014] [Accepted: 09/01/2014] [Indexed: 11/17/2022] Open
Abstract
Transcription activation is the foremost step of gene expression and is modulated by various factors that act in synergy. Misregulation of this process and its associated factors has severe effects and hence requires strong regulatory control. In recent years, growing evidence has highlighted the 26S proteasome as an important contributor to the regulation of transcription initiation. Well known for its role in protein destruction, its contribution to protein synthesis was initially viewed with skepticism. However, studies over the past several years have established the proteasome as an important component of transcription initiation through proteolytic and non-proteolytic activities. In this review, we discuss findings made so far in understanding the connections between transcription initiation and the 26S proteasome complex.
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26
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Faresse N. Post-translational modifications of the mineralocorticoid receptor: How to dress the receptor according to the circumstances? J Steroid Biochem Mol Biol 2014; 143:334-42. [PMID: 24820770 DOI: 10.1016/j.jsbmb.2014.04.015] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 04/07/2014] [Accepted: 04/28/2014] [Indexed: 12/22/2022]
Abstract
Aldosterone or glucocorticoid stimulation of the mineralocorticoid receptor (MR) is involved in numerous physiological responses, including ions and water homeostasis, blood pressure control and metabolism. The understanding of MR signaling regulation in the patho/physiological context took a new direction the last few years with a focus on the post-translational modifications of MR. Depending on its environment, cellular expression, activity or its binding partners, the MR is submitted to several post-translational modifications such as phosphorylation, ubiquitylation, sumoylation and acetylation that regulate its localization, activity and/or stability. A complex interplay between all these modifications allows a fine tuning of MR signaling depending on the physiological context. This review reports recent knowledge about post-translational modifications of MR and describes the enzymes and the molecular mechanisms involved.
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Affiliation(s)
- Nourdine Faresse
- University of Zurich, Institute of Anatomy, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
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27
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Gyöngyösi N, Káldi K. Interconnections of reactive oxygen species homeostasis and circadian rhythm in Neurospora crassa. Antioxid Redox Signal 2014; 20:3007-23. [PMID: 23964982 DOI: 10.1089/ars.2013.5558] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
SIGNIFICANCE Both circadian rhythm and the production of reactive oxygen species (ROS) are fundamental features of aerobic eukaryotic cells. The circadian clock enhances the fitness of organisms by enabling them to anticipate cycling changes in the surroundings. ROS generation in the cell is often altered in response to environmental changes, but oscillations in ROS levels may also reflect endogenous metabolic fluctuations governed by the circadian clock. On the other hand, an effective regulation and timing of antioxidant mechanisms may be crucial in the defense of cellular integrity. Thus, an interaction between the circadian timekeeping machinery and ROS homeostasis or signaling in both directions may be of advantage at all phylogenetic levels. RECENT ADVANCES The Frequency-White Collar-1 and White Collar-2 oscillator (FWO) of the filamentous fungus Neurospora crassa is well characterized at the molecular level. Several members of the ROS homeostasis were found to be controlled by the circadian clock, and ROS levels display circadian rhythm in Neurospora. On the other hand, multiple data indicate that ROS affect the molecular oscillator. CRITICAL ISSUES Increasing evidence suggests the interplay between ROS homeostasis and oscillators that may be partially or fully independent of the FWO. In addition, ROS may be part of a complex cellular network synchronizing non-transcriptional oscillators with timekeeping machineries based on the classical transcription-translation feedback mechanism. FUTURE DIRECTIONS Further investigations are needed to clarify how the different layers of the bidirectional interactions between ROS homeostasis and circadian regulation are interconnected.
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28
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Zheng XL. Myocardin and smooth muscle differentiation. Arch Biochem Biophys 2014; 543:48-56. [DOI: 10.1016/j.abb.2013.12.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 12/15/2013] [Accepted: 12/18/2013] [Indexed: 01/08/2023]
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Structural Characterization of a Noncovalent Complex between Ubiquitin and the Transactivation Domain of the Erythroid-Specific Factor EKLF. Structure 2013; 21:2014-24. [DOI: 10.1016/j.str.2013.08.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 08/14/2013] [Accepted: 08/30/2013] [Indexed: 11/20/2022]
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Chanarat S, Sträßer K. Splicing and beyond: the many faces of the Prp19 complex. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:2126-34. [PMID: 23742842 DOI: 10.1016/j.bbamcr.2013.05.023] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Revised: 05/22/2013] [Accepted: 05/24/2013] [Indexed: 12/18/2022]
Abstract
The conserved Prp19 complex (Prp19C) - also known as NineTeen Complex (NTC) - functions in several processes of paramount importance for cellular homeostasis. NTC/Prp19C was discovered as a complex that functions in splicing and more specifically during the catalytic activation of the spliceosome. More recent work revealed that NTC/Prp19C plays a role in transcription elongation in Saccharomyces cerevisiae and in genome maintenance in higher eukaryotes. In addition, mouse PRP19 might ubiquity late proteins targeted for degradation and guide them to the proteasome. Furthermore, NTC/Prp19C has been implicated in lipid droplet biogenesis. In the future, the molecular function of NTC/Prp19C in all of these processes needs to be refined or elucidated. Most of NTC/Prp19C's functions have been shown in only one or few organisms. However, since this complex is highly conserved it is likely that it has the same functions across all species. Moreover, one NTC/Prp19C or different subcomplexes could function in the above-mentioned processes. Intriguingly, NTC/Prp19C might link these different processes to ensure an optimal coordination of cellular processes. Thus, many important questions about the functions of this interesting complex remain to be investigated. In this review we discuss the different functions of NTC/Prp19C focusing on the novel and emerging ones as well as open questions.
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Affiliation(s)
- Sittinan Chanarat
- Department of Molecular Cell Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
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31
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Emerging roles for chromatin as a signal integration and storage platform. Nat Rev Mol Cell Biol 2013; 14:211-24. [PMID: 23524488 DOI: 10.1038/nrm3545] [Citation(s) in RCA: 210] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cells of a multicellular organism, all containing nearly identical genetic information, respond to differentiation cues in variable ways. In addition, cells are plastic, able to execute their specialized function while maintaining the ability to adapt to environmental changes. This is achieved through multiple mechanisms, including the direct regulation of chromatin-based processes in response to stimuli. How signal transduction pathways directly communicate with chromatin to change the epigenetic landscape is poorly understood. The preponderance of covalent modifications on histone tails coupled with a relatively small number of functional outputs raises the possibility that chromatin acts as a site of signal integration and storage.
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Kawedia JD, Yang F, Sartor MA, Gozal D, Czyzyk-Krzeska M, Menon AG. Hypoxia and hypoxia mimetics decrease aquaporin 5 (AQP5) expression through both hypoxia inducible factor-1α and proteasome-mediated pathways. PLoS One 2013; 8:e57541. [PMID: 23469202 PMCID: PMC3586073 DOI: 10.1371/journal.pone.0057541] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Accepted: 01/24/2013] [Indexed: 12/18/2022] Open
Abstract
The alveolar epithelium plays a central role in gas exchange and fluid transport, and is therefore critical for normal lung function. Since the bulk of water flux across this epithelium depends on the membrane water channel Aquaporin 5 (AQP5), we asked whether hypoxia had any effect on AQP5 expression. We show that hypoxia causes a significant (70%) decrease in AQP5 expression in the lungs of mice exposed to hypoxia. Hypoxia and the hypoxia mimetic, cobalt, also caused similar decreases in AQP5 mRNA and protein expression in the mouse lung epithelial cell line MLE-12. The action of hypoxia and cobalt on AQP5 transcription was demonstrated by directly quantifying heternonuclear RNA by real-time PCR. Dominant negative mutants of Hypoxia Inducible Factor (HIF-1α) and HIF-1α siRNA blocked the action of cobalt, showing that HIF-1α is a key component in this mechanism. The proteasome inhibitors, lactacystin or proteasome inhibitor-III completely abolished the effect of hypoxia and cobalt both at the protein and mRNA level indicating that the proteasome pathway is probably involved not only for the stability of HIF-1α protein, but for the stability of unidentified transcription factors that regulate AQP5 transcription. These studies reveal a potentially important physiological mechanism linking hypoxic stress and membrane water channels.
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Affiliation(s)
- Jitesh D Kawedia
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati, Cincinnati, Ohio, United States of America.
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Matsushita A, Inoue H, Goto S, Nakayama A, Sugano S, Hayashi N, Takatsuji H. Nuclear ubiquitin proteasome degradation affects WRKY45 function in the rice defense program. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 73:302-13. [PMID: 23013464 PMCID: PMC3558880 DOI: 10.1111/tpj.12035] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 09/21/2012] [Accepted: 09/21/2012] [Indexed: 05/18/2023]
Abstract
The transcriptional activator WRKY45 plays a major role in the salicylic acid/benzothiadiazole-induced defense program in rice. Here, we show that the nuclear ubiquitin-proteasome system (UPS) plays a role in regulating the function of WRKY45. Proteasome inhibitors induced accumulation of polyubiquitinated WRKY45 and transient up-regulation of WRKY45 target genes in rice cells, suggesting that WRKY45 is constantly degraded by the UPS to suppress defense responses in the absence of defense signals. Mutational analysis of the nuclear localization signal indicated that UPS-dependent WRKY45 degradation occurs in the nuclei. Interestingly, the transcriptional activity of WRKY45 after salicylic acid treatment was impaired by proteasome inhibition. The same C-terminal region in WRKY45 was essential for both transcriptional activity and UPS-dependent degradation. These results suggest that UPS regulation also plays a role in the transcriptional activity of WRKY45. It has been reported that AtNPR1, the central regulator of the salicylic acid pathway in Arabidopsis, is regulated by the UPS. We found that OsNPR1/NH1, the rice counterpart of NPR1, was not stabilized by proteasome inhibition under uninfected conditions. We discuss the differences in post-translational regulation of salicylic acid pathway components between rice and Arabidopsis.
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Liu J, Ma J. Dampened regulates the activating potency of Bicoid and the embryonic patterning outcome in Drosophila. Nat Commun 2013; 4:2968. [PMID: 24336107 PMCID: PMC3902774 DOI: 10.1038/ncomms3968] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Accepted: 11/18/2013] [Indexed: 01/26/2023] Open
Abstract
The Drosophila morphogen gradient of Bicoid (Bcd) initiates anterior-posterior (AP) patterning; however, it is poorly understood how its ability to activate a target gene may have an impact on this process. Here we report an F-box protein, Dampened (Dmpd) as a nuclear cofactor of Bcd that can enhance its activating potency. We establish a quantitative platform to specifically investigate two parameters of a Bcd target gene response, expression amplitude and boundary position. We show that embryos lacking Dmpd have a reduced amplitude of Bcd-activated hunchback (hb) expression at a critical time of development. This is because of a reduced Bcd-dependent transcribing probability. This defect is faithfully propagated further downstream of the AP-patterning network to alter the spatial characteristics of even-skipped (eve) stripes. Thus, unlike another Bcd-interacting F-box protein Fate-shifted (Fsd), which controls AP patterning through regulating the Bcd gradient profile, Dmpd achieves its patterning role through regulating the activating potency of Bcd.
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Affiliation(s)
- Junbo Liu
- Division of Biomedical Informatics Cincinnati Children's Research Foundation 3333 Burnet Avenue Cincinnati, Ohio United States of America
| | - Jun Ma
- Division of Biomedical Informatics Cincinnati Children's Research Foundation 3333 Burnet Avenue Cincinnati, Ohio United States of America
- Division of Developmental Biology Cincinnati Children's Research Foundation 3333 Burnet Avenue Cincinnati, Ohio United States of America
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35
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Ee G, Lehming N. How the ubiquitin proteasome system regulates the regulators of transcription. Transcription 2012; 3:235-9. [PMID: 22885980 DOI: 10.4161/trns.21249] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The ubiquitin proteasome system plays an important role in transcription. Monoubiquitination of activators is believed to aid their function, while the 26S proteasomal degradation of repressors is believed to restrict their function. What remains controversial is the question of whether the degradation of activators aids or restricts their function.
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Affiliation(s)
- Gary Ee
- Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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36
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Faresse N, Vitagliano JJ, Staub O. Differential ubiquitylation of the mineralocorticoid receptor is regulated by phosphorylation. FASEB J 2012; 26:4373-82. [PMID: 22798426 DOI: 10.1096/fj.12-209924] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Aldosterone stimulation of the mineralocorticoid receptor (MR) is involved in numerous physiological responses, including Na+ homeostasis, blood pressure control, and heart failure. Aldosterone binding to MR promotes different post-translational modifications that regulate MR nuclear translocation, gene expression, and finally receptor degradation. Here, we show that aldosterone stimulates rapid phosphorylation of MR via ERK1/2 in a dose-dependent manner (from 0.1 to 10 nM) in renal epithelial cells. This phosphorylation induces an increase of MR apparent molecular weight, with a maximal upward shift of 30 kDa. Strikingly, these modifications are critical for the regulation of the MR ubiquitylation state. Indeed, we find that MR is monoubiquitylated in its basal state, and this status is sustained by the tumor suppressor gene 101 (Tsg101). Phosphorylation leads to disruption of MR/Tsg101 association and monoubiquitin removal. These events prompt polyubiquitin-dependent destabilization of MR and degradation. Preventing MR phosphorylation by ERK1/2 inhibition or mutation of target serines affects the sequential mechanisms of MR ubiquitylation and inhibits the aldosterone-mediated degradation. Our data provide a novel model of negative feedback of aldosterone signaling, involving sequential phosphorylation, monoubiquitin removal and subsequent polyubiquitylation/degradation of MR.
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Affiliation(s)
- Nourdine Faresse
- University of Lausanne, Department of Pharmacology and Toxicology, Rue du Bugnon 27 CH-1005 Lausanne, Switzerland
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37
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Galbraith MD, Donner AJ, Espinosa JM. CDK8: a positive regulator of transcription. Transcription 2012; 1:4-12. [PMID: 21327159 DOI: 10.4161/trns.1.1.12373] [Citation(s) in RCA: 163] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Revised: 05/12/2010] [Accepted: 05/13/2010] [Indexed: 01/09/2023] Open
Abstract
CDK8 belongs to a group of cyclin-dependent kinases involved in transcriptional regulation from yeast to mammals. CDK8 associates with the Mediator complex, but functions outside of Mediator are also likely. Historically, CDK8 has been described mostly as a transcriptional repressor, but a growing body of research provides unequivocal evidence for various roles of CDK8 in gene activation. Several transcriptional programs of biomedical importance employ CDK8 as a co-activator, including the p53 network, the Wnt/β-catenin pathway, the serum response network, and those governed by SMADs and the thyroid hormone receptor, thus highlighting the importance of further investigation into this enigmatic transcriptional regulator.
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38
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Yao T, Ndoja A. Regulation of gene expression by the ubiquitin-proteasome system. Semin Cell Dev Biol 2012; 23:523-9. [PMID: 22430757 DOI: 10.1016/j.semcdb.2012.02.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 02/06/2012] [Accepted: 02/10/2012] [Indexed: 12/26/2022]
Abstract
Transcription is the foremost regulatory point during the process of producing a functional protein. Not only specific genes need to be turned on and off according to growth and environmental conditions, the amounts and quality of transcripts produced are fine-tuned to offer optimal responses. As a result, numerous regulatory mechanisms converge to provide temporal and spatial specificity for this process. In the past decade, the ubiquitin-proteasome system (UPS), which is best known as a pathway for intracellular proteolysis, has emerged as another pivotal player in the control of gene expression. There is increasing evidence that the UPS has both proteolytic and non-proteolytic functions in multiple aspects of the transcription process, including initiation, elongation, mRNA processing as well as chromatin dynamics. In this review, we introduce the many interfaces between the UPS and transcription with focuses on the mechanistic understanding of UPS function in each process.
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Affiliation(s)
- Tingting Yao
- Colorado State University, Biochemistry and Molecular Biology, 1870 Campus Delivery, Fort Collins, CO 80523, USA.
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39
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Liu S, Lv J, Han L, Ichikawa T, Wang W, Li S, Wang XL, Tang D, Cui T. A pro-inflammatory role of deubiquitinating enzyme cylindromatosis (CYLD) in vascular smooth muscle cells. Biochem Biophys Res Commun 2012; 420:78-83. [PMID: 22406061 DOI: 10.1016/j.bbrc.2012.02.118] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Accepted: 02/18/2012] [Indexed: 12/17/2022]
Abstract
CYLD, a deubiquitinating enzyme (DUB), is a critical regulator of diverse cellular processes, ranging from proliferation and differentiation to inflammatory responses, via regulating multiple key signaling cascades such as nuclear factor kappa B (NF-κB) pathway. CYLD has been shown to inhibit vascular lesion formation presumably through suppressing NF-κB activity in vascular cells. However, herein we report a novel role of CYLD in mediating pro-inflammatory responses in vascular smooth muscle cells (VSMCs) via a mechanism independent of NF-κB activity. Adenoviral knockdown of Cyld inhibited basal and the tumor necrosis factor alpha (TNFα)-induced mRNA expression of pro-inflammatory cytokines including monocyte chemotactic protein-1 (Mcp-1), intercellular adhesion molecule (Icam-1) and interleukin-6 (Il-6) in rat adult aortic SMCs (RASMCs). The CYLD deficiency led to increases in the basal NF-κB transcriptional activity in RASMCs; however, did not affect the TNFα-induced NF-κB activity. Intriguingly, the TNFα-induced IκB phosphorylation was enhanced in the CYLD deficient RASMCs. While knocking down of Cyld decreased slightly the basal expression levels of IκBα and IκBβ proteins, it did not alter the kinetics of TNFα-induced IκB protein degradation in RASMCs. These results indicate that CYLD suppresses the basal NF-κB activity and TNFα-induced IκB kinase activation without affecting TNFα-induced NF-κB activity in VSMCs. In addition, knocking down of Cyld suppressed TNFα-induced activation of mitogen activated protein kinases (MAPKs) including extracellular signal-activated kinases (ERK), c-Jun N-terminal kinase (JNK), and p38 in RASMCs. TNFα-induced RASMC migration and monocyte adhesion to RASMCs were inhibited by the Cyld knockdown. Finally, immunochemical staining revealed a dramatic augment of CYLD expression in the injured coronary artery with neointimal hyperplasia. Taken together, our results uncover an unexpected role of CYLD in promoting inflammatory responses in VSMCs via a mechanism involving MAPK activation but independent of NF-κB activity, contributing to the pathogenesis of vascular disease.
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Affiliation(s)
- Shuai Liu
- Shandong University Qilu Hospital Research Center for Cell Therapy, Key Laboratory of Cardiovascular Remodeling and Function Research, Qilu Hospital of Shandong University, Jinan 250012, China
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40
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Campbell M, Izumiya Y. Post-Translational Modifications of Kaposi's Sarcoma-Associated Herpesvirus Regulatory Proteins - SUMO and KSHV. Front Microbiol 2012; 3:31. [PMID: 22347876 PMCID: PMC3278983 DOI: 10.3389/fmicb.2012.00031] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Accepted: 01/18/2012] [Indexed: 01/20/2023] Open
Abstract
KSHV latency can be envisioned as an outcome that is balanced between factors that promote viral gene expression and lytic replication against those that facilitate gene silencing and establish or maintain latency. A large body of work has focused on the activities of the key viral regulatory proteins involved in KSHV latent or lytic states. Moreover, recent studies have also begun to document the importance of epigenetic landscape evolution of the KSHV viral genome during latency and reactivation. However, one area of KSHV molecular virology that remains largely unanswered is the precise role of post-translational modifications on the activities of viral factors that function during latency and reactivation. In this review, we will summarize the post-translational modifications associated with three viral factors whose activities contribute to the viral state. The viral proteins discussed are the two major KSHV encoded transcription factors, K-Rta (KSHV replication and transcriptional activator) and K-bZIP (KSHV basic leucine zipper) and the viral latency-associated nuclear antigen (LANA). A special emphasis will be placed on the role of the sumoylation pathway in the modulation of the KSHV lifecycle. Newly uncovered small ubiquitin-like modifier (SUMO)-associated properties of LANA and K-Rta will also be presented, namely LANA histone targeting SUMO E3 ligase activity and K-Rta SUMO-targeted ubiquitin ligase function.
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Affiliation(s)
- Mel Campbell
- Department of Dermatology, University of California Davis Sacramento, CA, USA
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41
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Lüscher B, Vervoorts J. Regulation of gene transcription by the oncoprotein MYC. Gene 2011; 494:145-60. [PMID: 22227497 DOI: 10.1016/j.gene.2011.12.027] [Citation(s) in RCA: 108] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Revised: 11/27/2011] [Accepted: 12/15/2011] [Indexed: 02/07/2023]
Abstract
The proteins of the MYC/MAX/MAD network are central regulators of many key processes associated with basic cell physiology. These include the regulation of protein biosynthesis, energy metabolism, proliferation, and apoptosis. Molecularly the MYC/MAX/MAD network achieves these broad activities by controlling the expression of many target genes, which are primarily responsible for the diverse physiological consequences elicited by the network. The MYC proteins of the network possess oncogenic activity and their functional deregulation is associated with the majority of human tumors. Over the last years we have witnessed the accumulation of a considerable number of molecular observations that suggest many different biochemical means and tools by which MYC controls gene expression. We will summarize the more recent findings and discuss how these different building blocks might come together to explain how MYC regulates gene transcription. We note that despite the many molecular details known, we do not have an integrated view of how MYC uses the different tools, neither in a spatial nor in a temporal order.
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Affiliation(s)
- Bernhard Lüscher
- Institute of Biochemistry and Molecular Biology, Medical School, RWTH Aachen University, 52057 Aachen, Germany.
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42
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Abstract
The flower of rice diverged from those of model eudicot species such as Arabidopsis, Antirrhinum, or Petunia, and is thus of great interest in developmental and evolutionary biology. Specific to grass species, including rice, are the structural units of the inflorescence called the spikelet and floret, which comprise grass-specific peripheral organs and conserved sexual organs. Recent advances in molecular genetic studies have provided an understanding of the functions of rapidly increasing numbers of genes involved in rice flower development. The genetic framework of rice flower development is in part similar to that of model eudicots. However, rice also probably recruits specific genetic mechanisms, which probably contribute to the establishment of the specific floral architecture of rice. In this review, the molecular genetic mechanisms of rice flowering are outlined, focusing on recent information and in comparison with those of model eudicots.
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Affiliation(s)
- Hitoshi Yoshida
- Rice Research Division, National Institute of Crop Science, National Agriculture and Food Research Organization (NARO), Tsukuba, Ibaraki 305-8518, Japan.
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43
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Dinger ME, Gascoigne DK, Mattick JS. The evolution of RNAs with multiple functions. Biochimie 2011; 93:2013-8. [PMID: 21802485 DOI: 10.1016/j.biochi.2011.07.018] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Accepted: 07/12/2011] [Indexed: 01/21/2023]
Abstract
Increasing numbers of transcripts have been reported to transmit both protein-coding and regulatory information. Apart from challenging our conception of the gene, this observation raises the question as to what extent this phenomenon occurs across the genome and how and why such dual encoding of function has evolved in the eukaryotic genome. To address this question, we consider the evolutionary path of genes in the earliest forms of life on Earth, where it is generally regarded that proteins evolved from a cellular machinery based entirely within RNA. This led to the domination of protein-coding genes in the genomes of microorganisms, although it is likely that RNA never lost its other capacities and functionalities, as evidenced by cis-acting riboswitches and UTRs. On the basis that the subsequent evolution of a more sophisticated regulatory architecture to provide higher levels of epigenetic control and accurate spatiotemporal expression in developmentally complex organisms is a complicated task, we hypothesize: (i) that mRNAs have been and remain subject to secondary selection to provide trans-acting regulatory capability in parallel with protein-coding functions; (ii) that some and perhaps many protein-coding loci, possibly as a consequence of gene duplication, have lost protein-coding functions en route to acquiring more sophisticated trans-regulatory functions; (iii) that many transcripts have become subject to secondary processing to release different products; and (iv) that novel proteins have emerged within loci that previously evolved functionality as regulatory RNAs. In support of the idea that there is a dynamic flux between different types of informational RNAs in both evolutionary and real time, we review recent observations that have arisen from transcriptomic surveys of complex eukaryotes and reconsider how these observations impact on the notion that apparently discrete loci may express transcripts with more than one function. In conclusion, we posit that many eukaryotic loci have evolved the capacity to transact a multitude of overlapping and potentially independent functions as both regulatory and protein-coding RNAs.
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Affiliation(s)
- Marcel E Dinger
- Institute for Molecular Bioscience, University of Queensland, 306 Carmody Road, St Lucia, QLD 4072, Australia.
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44
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Distinct p53 transcriptional programs dictate acute DNA-damage responses and tumor suppression. Cell 2011; 145:571-83. [PMID: 21565614 DOI: 10.1016/j.cell.2011.03.035] [Citation(s) in RCA: 409] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2010] [Revised: 02/03/2011] [Accepted: 03/18/2011] [Indexed: 12/17/2022]
Abstract
The molecular basis for p53-mediated tumor suppression remains unclear. Here, to elucidate mechanisms of p53 tumor suppression, we use knockin mice expressing an allelic series of p53 transcriptional activation mutants. Microarray analysis reveals that one mutant, p53(25,26), is severely compromised for transactivation of most p53 target genes, and, moreover, p53(25,26) cannot induce G(1)-arrest or apoptosis in response to acute DNA damage. Surprisingly, p53(25,26) retains robust activity in senescence and tumor suppression, indicating that efficient transactivation of the majority of known p53 targets is dispensable for these pathways. In contrast, the transactivation-dead p53(25,26,53,54) mutant cannot induce senescence or inhibit tumorigenesis, like p53 nullizygosity. Thus, p53 transactivation is essential for tumor suppression but, intriguingly, in association with a small set of novel p53 target genes. Together, our studies distinguish the p53 transcriptional programs involved in acute DNA-damage responses and tumor suppression-a critical goal for designing therapeutics that block p53-dependent side effects of chemotherapy without compromising p53 tumor suppression.
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45
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Yu Y, Hayward GS. The ubiquitin E3 ligase RAUL negatively regulates type i interferon through ubiquitination of the transcription factors IRF7 and IRF3. Immunity 2011; 33:863-77. [PMID: 21167755 DOI: 10.1016/j.immuni.2010.11.027] [Citation(s) in RCA: 169] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2010] [Revised: 09/14/2010] [Accepted: 11/29/2010] [Indexed: 11/28/2022]
Abstract
In the course of combating infectious agents, type I interferon (IFN) needs a timely downregulation mechanism to avoid detrimental overreaction. Here we showed a mechanism for restraining type I IFN responses, which relied on a HECT domain ubiquitin (Ub) E3 ligase, RAUL. RAUL limited type I IFN production by directly catalyzing lysine 48-linked polyubiquitination of both interferon regulatory factor 7 (IRF7) and IRF3 followed by proteasome-dependent degradation. Suppression of RAUL by dominant-negative RAUL or siRNA augmented both basal and virus-induced production of type I IFN, which resulted in reduced viral replication. The Kaposi's sarcoma-associated herpes virus immediate-early lytic cycle trigger protein RTA recruited this mechanism to augment its countermeasures against the host antiviral response. These results unveil a previously unrecognized "brake mechanism" for type I IFN that maintains proper low amounts of type I IFN under physiological conditions and restrains its magnitude when the antiviral response intensifies.
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Affiliation(s)
- Yanxing Yu
- Viral Oncology Program, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, 1650 Orleans Street, CRB1 3M09, Baltimore, MD 21231, USA.
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Singh AK, Swarnalatha M, Kumar V. c-ETS1 facilitates G1/S-phase transition by up-regulating cyclin E and CDK2 genes and cooperates with hepatitis B virus X protein for their deregulation. J Biol Chem 2011; 286:21961-70. [PMID: 21515670 DOI: 10.1074/jbc.m111.238238] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Recent studies on the molecular mechanisms responsible for cell cycle deregulation in cancer have puzzled out the role of oncogenes in mediating unscheduled cellular proliferation. This is reminiscence of their activity as proto-oncogenes that drives scheduled cell cycle progression under physiological conditions. Working on the cell cycle regulatory activity of proto-oncogene, we observed that c-ETS1 transcriptionally up-regulated both cyclin E and CDK2 genes, the master regulators of G(1)/S-phase transition. The process was mediated by kinetic coherence of c-ETS1 expression and its recruitment to both promoters during G(1)/S-phase transition. Furthermore, enforced expression of c-ETS1 helped G(0)-arrested cells to progress into G(1)/S-phases apparently due to the activation of cyclin E/CDK2 genes. Physiological induction of c-ETS1 by EGF showed the remodeling of mononucleosomes bound to the c-ETS1 binding site on both promoters during their activation. The exchange of HDAC1 with histone acetyltransferase-p300 was contemporaneous to the chromatin remodeling with consequent increase in histone H3K9 acetylation. Furthermore, the ATP-dependent chromatin remodeler hBRM1 recruitment was also associated with nucleosome remodeling and promoter occupancy of phospho-Ser5 RNA polymerase II. Intriguingly, the activity of the HBx viral oncoprotein was dependent on c-ETS1 in a hepatotropic manner, which led to the activation of cyclin E/CDK2 genes. Thus, cyclin E and CDK2 genes are key physiological effectors of the c-ETS1 proto-oncogene. Furthermore, c-ETS1 is indispensable for the hepatotropic action of HBx in cell cycle deregulation.
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Affiliation(s)
- Anup Kumar Singh
- Virology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, India
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47
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The E3 ligase Itch is a negative regulator of the homeostasis and function of hematopoietic stem cells. Nat Immunol 2011; 12:399-407. [PMID: 21478879 DOI: 10.1038/ni.2021] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Accepted: 03/14/2011] [Indexed: 12/17/2022]
Abstract
Although hematopoietic stem cells (HSCs) are the most thoroughly characterized type of adult stem cell, the intricate molecular machinery that regulates their self-renewal properties remains elusive. Here we showed that the E3 ubiquitin ligase Itch negatively regulated the development and function of HSCs. Itch(-/-) mice had HSCs with enhanced frequency, competence and long-term repopulating activity. Itch-deficient HSCs showed accelerated proliferation rates and sustained progenitor properties, as well as more signaling by the transcription factor Notch1, due to more accumulation of activated Notch1. Knockdown of Notch1 in Itch-mutant HSCs resulted in reversion of the phenotype. Thus, we identify Itch as a previously unknown negative regulator of HSC homeostasis and function.
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Kinases and phosphatases in the mammalian circadian clock. FEBS Lett 2011; 585:1393-9. [DOI: 10.1016/j.febslet.2011.02.038] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Revised: 02/23/2011] [Accepted: 02/28/2011] [Indexed: 12/28/2022]
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Purushothaman S, Annamalai K, Tyagi AK, Surolia A. Diversity in functional organization of class I and class II biotin protein ligase. PLoS One 2011; 6:e16850. [PMID: 21390227 PMCID: PMC3048393 DOI: 10.1371/journal.pone.0016850] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2010] [Accepted: 01/16/2011] [Indexed: 11/28/2022] Open
Abstract
The cell envelope of Mycobacterium tuberculosis
(M.tuberculosis) is composed of a variety of lipids
including mycolic acids, sulpholipids, lipoarabinomannans, etc., which impart
rigidity crucial for its survival and pathogenesis. Acyl CoA carboxylase (ACC)
provides malonyl-CoA and methylmalonyl-CoA, committed precursors for fatty acid
and essential for mycolic acid synthesis respectively. Biotin Protein Ligase
(BPL/BirA) activates apo-biotin carboxyl carrier protein (BCCP) by biotinylating
it to an active holo-BCCP. A minimal peptide (Schatz), an efficient substrate
for Escherichia coli BirA, failed to serve as substrate for
M. tuberculosis Biotin Protein Ligase
(MtBPL). MtBPL specifically biotinylates
homologous BCCP domain, MtBCCP87, but not
EcBCCP87. This is a unique feature of
MtBPL as EcBirA lacks such a stringent
substrate specificity. This feature is also reflected in the lack of
self/promiscuous biotinylation by MtBPL. The N-terminus/HTH
domain of EcBirA has the self-biotinable lysine residue that is
inhibited in the presence of Schatz peptide, a peptide designed to act as a
universal acceptor for EcBirA. This suggests that when biotin
is limiting, EcBirA preferentially catalyzes, biotinylation of
BCCP over self-biotinylation. R118G mutant of EcBirA showed
enhanced self and promiscuous biotinylation but its homologue, R69A
MtBPL did not exhibit these properties. The catalytic
domain of MtBPL was characterized further by limited
proteolysis. Holo-MtBPL is protected from proteolysis by
biotinyl-5′ AMP, an intermediate of MtBPL catalyzed
reaction. In contrast, apo-MtBPL is completely digested by
trypsin within 20 min of co-incubation. Substrate selectivity and inability to
promote self biotinylation are exquisite features of MtBPL and
are a consequence of the unique molecular mechanism of an enzyme adapted for the
high turnover of fatty acid biosynthesis.
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Affiliation(s)
| | | | - Anil K. Tyagi
- Department of Biochemistry, University of
Delhi South Campus, New Delhi, India
| | - Avadhesha Surolia
- Molecular Biophysics Unit, Indian Institute of
Science, Bangalore, India
- National Institute of Immunology, Aruna Asaf
Ali Marg, New Delhi, India
- * E-mail:
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Gatti L, Hoe KL, Hayles J, Righetti SC, Carenini N, Bo LD, Kim DU, Park HO, Perego P. Ubiquitin-proteasome genes as targets for modulation of cisplatin sensitivity in fission yeast. BMC Genomics 2011; 12:44. [PMID: 21247416 PMCID: PMC3032702 DOI: 10.1186/1471-2164-12-44] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Accepted: 01/19/2011] [Indexed: 12/28/2022] Open
Abstract
Background The ubiquitin(Ub)-proteasome pathway is implicated in the regulation of a variety of cellular functions and plays a major role in stress response in eukaryotic cells, by targeting misfolded and damaged proteins for degradation. In addition, in the presence of DNA damage, the Ub-proteasome system regulates proteins involved in sensing, repairing, and/or tolerating the damage. Antitumor agents such as cisplatin can activate the pathway, but the role of specific pathway components in cell sensitivity/response to the drug is not known. Since platinum compounds represent clinically relevant antitumor agents and a major limitation to their use is the development of drug resistance, there is an urgent need for identifying targets for improving their efficacy. Results In the present study, we performed a genome-wide screening for sensitivity to cisplatin using non-essential haploid deletion mutants of the fission yeast Schizosaccharomyces pombe, belonging to a collection of haploid strains constructed through homologous recombination. Using this approach, we identified three Ub-proteasome mutants exhibiting hypersensitivity to cisplatin (ubp16, ubc13 and pmt3) and ten mutants (including ufd2, beta7 20S, rpt6/let1) resistant to the drug. In addition, the importance of lub1 gene emerged from the comparison between the present screening and gene expression profile data previously obtained in fission yeast. Conclusions The factors identified in the present study allowed us to highlight most finely the close relationship between the Ub-proteasome system and DNA damage response mechanisms, thus establishing a comprehensive framework of regulators likely relevant also in higher eukaryotes. Our results provide the proof of principle of the involvement of specific genes modulated by cisplatin treatment in cell response to the drug, suggesting their potential role as targets for modulating cisplatin sensitivity. In this regard, the prospective identification of novel targets for modulation of cisplatin sensitivity in an eukaryotic model organism appears particularly intriguing towards the discovery of strategies to overcome cisplatin resistance in human tumors.
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Affiliation(s)
- Laura Gatti
- Fondazione IRCCS, Istituto Nazionale per Studio e Cura dei Tumori, 20133 Milan, Italy
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