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Costanzo F, Martínez Diez M, Santamaría Nuñez G, Díaz-Hernandéz JI, Genes Robles CM, Díez Pérez J, Compe E, Ricci R, Li TK, Coin F, Martínez Leal JF, Garrido-Martin EM, Egly JM. Promoters of ASCL1- and NEUROD1-dependent genes are specific targets of lurbinectedin in SCLC cells. EMBO Mol Med 2022; 14:e14841. [PMID: 35263037 PMCID: PMC8988166 DOI: 10.15252/emmm.202114841] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 02/16/2022] [Accepted: 02/17/2022] [Indexed: 01/22/2023] Open
Abstract
Small‐Cell Lung Cancer (SCLC) is an aggressive neuroendocrine malignancy with a poor prognosis. Here, we focus on the neuroendocrine SCLC subtypes, SCLC‐A and SCLC‐N, whose transcription addiction was driven by ASCL1 and NEUROD1 transcription factors which target E‐box motifs to activate up to 40% of total genes, the promoters of which are maintained in a steadily open chromatin environment according to ATAC and H3K27Ac signatures. This leverage is used by the marine agent lurbinectedin, which preferentially targets the CpG islands located downstream of the transcription start site, thus arresting elongating RNAPII and promoting its degradation. This abrogates the expression of ASCL1 and NEUROD1 and of their dependent genes, such as BCL2, INSM1, MYC, and AURKA, which are responsible for relevant SCLC tumorigenic properties such as inhibition of apoptosis and cell survival, as well as for a part of its neuroendocrine features. In summary, we show how the transcription addiction of these cells becomes their Achilles’s heel, and how this is effectively exploited by lurbinectedin as a novel SCLC therapeutic endeavor.
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Affiliation(s)
- Federico Costanzo
- Department of Functional Genomics and Cancer, IGBMC, CNRS/INSERM/University of Strasbourg, Equipe labellisée Ligue contre le Cancer, Strasbourg, France.,Cell Biology Department, Research and Development, Pharmamar SA, Colmenar Viejo, Spain
| | - Marta Martínez Diez
- Cell Biology Department, Research and Development, Pharmamar SA, Colmenar Viejo, Spain
| | - Gema Santamaría Nuñez
- Cell Biology Department, Research and Development, Pharmamar SA, Colmenar Viejo, Spain
| | | | - Carlos Mario Genes Robles
- Department of Functional Genomics and Cancer, IGBMC, CNRS/INSERM/University of Strasbourg, Equipe labellisée Ligue contre le Cancer, Strasbourg, France
| | - Javier Díez Pérez
- Cell Biology Department, Research and Development, Pharmamar SA, Colmenar Viejo, Spain
| | - Emmanuel Compe
- Department of Functional Genomics and Cancer, IGBMC, CNRS/INSERM/University of Strasbourg, Equipe labellisée Ligue contre le Cancer, Strasbourg, France.,Laboratoire de Biochimie et de Biologie Moléculaire, Nouvel Hôpital Civil, Strasbourg, France
| | - Romeo Ricci
- Department of Functional Genomics and Cancer, IGBMC, CNRS/INSERM/University of Strasbourg, Equipe labellisée Ligue contre le Cancer, Strasbourg, France.,Laboratoire de Biochimie et de Biologie Moléculaire, Nouvel Hôpital Civil, Strasbourg, France
| | - Tsai-Kun Li
- College of Medicine, Center for Genomics and Precision Medicine, National Taiwan University, Taipei city, Taiwan
| | - Frédéric Coin
- Department of Functional Genomics and Cancer, IGBMC, CNRS/INSERM/University of Strasbourg, Equipe labellisée Ligue contre le Cancer, Strasbourg, France.,Laboratoire de Biochimie et de Biologie Moléculaire, Nouvel Hôpital Civil, Strasbourg, France
| | | | | | - Jean Marc Egly
- Department of Functional Genomics and Cancer, IGBMC, CNRS/INSERM/University of Strasbourg, Equipe labellisée Ligue contre le Cancer, Strasbourg, France.,College of Medicine, Center for Genomics and Precision Medicine, National Taiwan University, Taipei city, Taiwan
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Chymkowitch P, Le May N, Charneau P, Compe E, Egly JM. The phosphorylation of the androgen receptor by TFIIH directs the ubiquitin/proteasome process. EMBO J 2010; 30:468-79. [PMID: 21157430 DOI: 10.1038/emboj.2010.337] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Accepted: 11/22/2010] [Indexed: 11/09/2022] Open
Abstract
In response to hormonal stimuli, a cascade of hierarchical post-translational modifications of nuclear receptors are required for the correct expression of target genes. Here, we show that the transcription factor TFIIH, via its cdk7 kinase, phosphorylates the androgen receptor (AR) at position AR/S515. Strikingly, this phosphorylation is a key step for an accurate transactivation that includes the cyclic recruitment of the transcription machinery, the MDM2 E3 ligase, the subsequent ubiquitination of AR at the promoter of target genes and its degradation by the proteasome machinery. Impaired phosphorylation disrupts the transactivation, as observed in cells either overexpressing the non-phosphorylated AR/S515A, isolated from xeroderma pigmentosum patient (bearing a mutation in XPD subunit of TFIIH), or in which cdk7 kinase was silenced. Indeed, besides affecting the cyclic recruitment of the transcription machinery, the AR phosphorylation defect favourizes to the recruitment of the E3 ligase CHIP instead of MDM2, at the PSA promoter, that will further attract the proteasome machinery. These observations illustrate how the TFIIH phosphorylation might participate to the transactivation by regulating the nuclear receptors turnover.
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Affiliation(s)
- Pierre Chymkowitch
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique, INSERM, Université de Strasbourg, Illkirch cedex, France
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3
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Keppler BR, Archer TK, Kinyamu HK. Emerging roles of the 26S proteasome in nuclear hormone receptor-regulated transcription. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2010; 1809:109-18. [PMID: 20728592 DOI: 10.1016/j.bbagrm.2010.08.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 08/10/2010] [Accepted: 08/16/2010] [Indexed: 02/07/2023]
Abstract
The mechanisms by which nuclear hormone receptors (NHRs) regulate transcription are highly dynamic and require interplay between a myriad of regulatory protein complexes including the 26S proteasome. Protein degradation is the most well-established role of the proteasome; however, an increasing body of evidence suggests that the 26S proteasome may regulate transcription in proteolytic and nonproteolytic mechanisms. Here we review how these mechanisms may apply to NHR-mediated transcriptional regulation. This article is part of a Special Issue entitled The 26S Proteasome: When degradation is just not enough!
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Affiliation(s)
- Brian R Keppler
- Chromatin and Gene Expression Section, Laboratory of Molecular Carcinogenesis, NIEHS/NIH, Research Triangle Park, NC 27709, USA
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Bhat KP, Truax AD, Brooks JK, Greer SF. Association of the 19S proteasomal ATPases with the ATPase-binding domain of CIITA is essential for CIITA stability and MHC class II expression. Immunol Cell Biol 2010; 88:807-16. [PMID: 20351748 DOI: 10.1038/icb.2010.45] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Major histocompatibility class II (MHC class II) molecules are glycoproteins that present extracellular antigens to CD4(+) T cells and are essential for initiation of adaptive immune responses. MHC class II expression requires recruitment of a master regulator, the class II transactivator (CIITA), to the MHC class II promoter. Others and we have earlier linked CIITA to the ubiquitin-proteasome system by showing that mono-ubiquitination of CIITA increases its transactivity, whereas poly-ubiquitination of CIITA leads to its degradation. We have further shown that the 26S proteasome also has non-proteolytic functions in MHC class II transcription, as 19S ATPase subunits of the 26S proteasome positively regulate MHC class II transcription and are necessary for stable promoter binding of CIITA. Although these basic requirements of the proteasome to initiate MHC class II transcription are known, how CIITA is recruited, stabilized, and degraded remains unclear. Here, we identify a novel N-terminal 19S ATPase-binding domain of CIITA. The ATPase-binding domain lies within the proline/serine/threonine-rich region of CIITA and encompasses a majority of the CIITA degron sequence. Absence of the ATPase-binding domain increases the half-life of CIITA, but blocks MHC class II surface expression, indicating that CIITA requires interaction with the 19S ATPases for both appropriate deployment and destruction.
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Affiliation(s)
- Kavita Purnanda Bhat
- Division of Cellular and Molecular Biology and Physiology, Department of Biology, Georgia State University, Atlanta, GA 30302, USA
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Konstantinova IM, Tsimokha AS, Mittenberg AG. Role of proteasomes in cellular regulation. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 267:59-124. [PMID: 18544497 DOI: 10.1016/s1937-6448(08)00602-3] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The 26S proteasome is the key enzyme of the ubiquitin-dependent pathway of protein degradation. This energy-dependent nanomachine is composed of a 20S catalytic core and associated regulatory complexes. The eukaryotic 20S proteasomes demonstrate besides several kinds of peptidase activities, the endoribonuclease, protein-chaperone and DNA-helicase activities. Ubiquitin-proteasome pathway controls the levels of the key regulatory proteins in the cell and thus is essential for life and is involved in regulation of crucial cellular processes. Proteasome population in the cell is structurally and functionally heterogeneous. These complexes are subjected to tightly organized regulation, particularly, to a variety of posttranslational modifications. In this review we will summarize the current state of knowledge regarding proteasome participation in the control of cell cycle, apoptosis, differentiation, modulation of immune responses, reprogramming of these particles during these processes, their heterogeneity and involvement in the main levels of gene expression.
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Transcriptional Control and the Ubiquitin–Proteasome System. THE UBIQUITIN SYSTEM IN HEALTH AND DISEASE 2008. [DOI: 10.1007/2789_2008_102] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Ulvila J, Parikka M, Kleino A, Sormunen R, Ezekowitz RA, Kocks C, Rämet M. Double-stranded RNA is internalized by scavenger receptor-mediated endocytosis in Drosophila S2 cells. J Biol Chem 2006; 281:14370-5. [PMID: 16531407 DOI: 10.1074/jbc.m513868200] [Citation(s) in RCA: 194] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Double-stranded RNA (dsRNA) fragments are readily internalized and processed by Drosophila S2 cells, making these cells a widely used tool for the analysis of gene function by gene silencing through RNA interference (RNAi). The underlying mechanisms are insufficiently understood. To identify components of the RNAi pathway in S2 cells, we developed a screen based on rescue from RNAi-induced lethality. We identified Argonaute 2, a core component of the RNAi machinery, and three gene products previously unknown to be involved in RNAi in Drosophila: DEAD-box RNA helicase Belle, 26 S proteasome regulatory subunit 8 (Pros45), and clathrin heavy chain, a component of the endocytic machinery. Blocking endocytosis in S2 cells impaired RNAi, suggesting that dsRNA fragments are internalized by receptor-mediated endocytosis. Indeed, using a candidate gene approach, we identified two Drosophila scavenger receptors, SR-CI and Eater, which together accounted for more than 90% of the dsRNA uptake into S2 cells. When expressed in mammalian cells, SR-CI was sufficient to mediate internalization of dsRNA fragments. Our data provide insight into the mechanism of dsRNA internalization by Drosophila cells. These results have implications for dsRNA delivery into mammalian cells.
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Affiliation(s)
- Johanna Ulvila
- Department of Pediatrics and Biocenter Oulu, University of Oulu, FIN-90014, Oulu, Finland
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Abstract
1alpha,25-Dihydroxyvitamin D(3) [1,25-(OH)(2)D(3)], the active metabolite of vitamin D(3), is known for the maintenance of mineral homeostasis and normal skeletal architecture. However, apart from these traditional calcium-related actions, 1,25-(OH)(2)D(3) and its synthetic analogs are being increasingly recognized for their potent antiproliferative, prodifferentiative, and immunomodulatory activities. These actions of 1,25-(OH)(2)D(3) are mediated through vitamin D receptor (VDR), which belongs to the superfamily of steroid/thyroid hormone nuclear receptors. Physiological and pharmacological actions of 1,25-(OH)(2)D(3) in various systems, along with the detection of VDR in target cells, have indicated potential therapeutic applications of VDR ligands in inflammation (rheumatoid arthritis, psoriatic arthritis), dermatological indications (psoriasis, actinic keratosis, seborrheic dermatitis, photoaging), osteoporosis (postmenopausal and steroid-induced osteoporosis), cancers (prostate, colon, breast, myelodysplasia, leukemia, head and neck squamous cell carcinoma, and basal cell carcinoma), secondary hyperparathyroidism, and autoimmune diseases (systemic lupus erythematosus, type I diabetes, multiple sclerosis, and organ transplantation). As a result, VDR ligands have been developed for the treatment of psoriasis, osteoporosis, and secondary hyperparathyroidism. Furthermore, encouraging results have been obtained with VDR ligands in clinical trials of prostate cancer and hepatocellular carcinoma. This review deals with the molecular aspects of noncalcemic actions of vitamin D analogs that account for the efficacy of VDR ligands in the above-mentioned indications.
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Affiliation(s)
- Sunil Nagpal
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN 46285, USA.
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Girão H, Pereira P, Taylor A, Shang F. Subcellular redistribution of components of the ubiquitin-proteasome pathway during lens differentiation and maturation. Invest Ophthalmol Vis Sci 2005; 46:1386-92. [PMID: 15790906 PMCID: PMC1382281 DOI: 10.1167/iovs.04-0563] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To determine the subcellular distribution of components of the ubiquitin-proteasome pathway (UPP) in lens epithelium and differentiating fibers and to evaluate potential roles of the UPP in eliminating nuclei and other organelles during maturation of lens fibers. METHODS Adult bovine lens cryosections were stained for immunofluorescence and analyzed by confocal microscopy. The specificities of the antibodies used in this study were determined by Western blot. results Cryosections of bovine lenses show that E1 and Ubc1 were present in both the cytoplasm and the nucleus in epithelial cells, whereas Ubc3 and ubiquitin conjugates were mostly confined to the nucleus, and Ubc4/5 was preferentially localized in clusters in the vicinity of the nuclear membrane. The 19S and 20S proteasome complexes were preferentially localized in the cytoplasm. When the epithelial cells differentiated into fiber cells at the transition zone, all components of the UPP were primarily present in the nucleus, with the exception of Ubc4/5, which was associated with the nuclear membrane. conclusions The results show that during lens fiber differentiation and maturation, components of the UPP are redistributed at subcellular levels. Subcellular localization of an enzyme indicates where the reaction takes place. The primary nuclear localization of the UPP components in the differentiating fibers supports the hypothesis that the UPP may play a role in elimination of nuclei and other organelles during differentiation and maturation of lens fibers.
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Affiliation(s)
- Henrique Girão
- Center of Ophthalmology, Biomedical Institute for Research in Light and Image, University of Coimbra, Portugal
- Laboratory for Nutrition and Vision Research, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, Massachusetts
| | - Paulo Pereira
- Center of Ophthalmology, Biomedical Institute for Research in Light and Image, University of Coimbra, Portugal
- Laboratory for Nutrition and Vision Research, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, Massachusetts
| | - Allen Taylor
- Laboratory for Nutrition and Vision Research, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, Massachusetts
| | - Fu Shang
- Laboratory for Nutrition and Vision Research, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, Massachusetts
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Abstract
The thyroid hormone receptor (TR) directly regulates the transcription of thyroid hormone-responsive genes in response to changing levels of thyroid hormone. Mechanistically TR utilizes a complex set of binding interactions, with hormone, response elements, and coregulatory proteins, to provide specific local control of patterns of transcriptional response that are partially responsible for inducing the tissue-selective responses to the circulating hormone. One of the apparently dominant phenomena in the regulation of thyroid hormone responses is the protein interactions between TR and its coregulators. This review summarizes the current state of knowledge with respect to the identity of these coregulators, their interaction with TR, and the consequences of those interactions.
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Affiliation(s)
- Jamie M R Moore
- Department of Late Stage Formulation Development, Genentech, South San Francisco, California 94080, USA
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11
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Wang QE, Wani MA, Chen J, Zhu Q, Wani G, El-Mahdy MA, Wani AA. Cellular ubiquitination and proteasomal functions positively modulate mammalian nucleotide excision repair. Mol Carcinog 2005; 42:53-64. [PMID: 15547920 DOI: 10.1002/mc.20065] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The ubiquitin-proteasome pathway is fundamental to synchronized continuation of many cellular processes, for example, cell-cycle progression, stress response, and cell differentiation. Recent studies have shown that the ubiquitin-proteasome pathway functions in the regulation of nucleotide excision repair (NER) in yeast. In order to investigate the role of the ubiquitin-proteasome pathway in the NER of mammalian cells, global genomic repair (GGR), and transcription-coupled repair (TCR) were examined in a mouse ts20 cell line that harbors a temperature-sensitive ubiquitin-activating enzyme (E1). We found that E1 inactivation-induced ubiquitination deficiency decreased both GGR and TCR, indicating that the ubiquitination system is involved in the optimization of entire NER machinery in mammalian cells. We specifically inhibited the function of 19S proteasome subunit by overexpressing 19S regulatory complex hSug1 or its mutant protein hSug1mk in repair competent human fibroblast, OSU-2, cells and compared their capacity for NER. The results showed that 19S regulatory complex positively modulates NER in cells. In addition, we treated OSU-2 cells with the inhibitors of 20S subunit function, MG132 and lactacystin, and demonstrated that the catalytic activity of 20S subunit is also required for efficient NER. Moreover, the UV-induced recruitment of repair factor xeroderma pigmentosum protein C (XPC) to damage sites was negatively affected by treatment of repair competent cells with MG132. Taken together, we conclude that the ubiquitin-proteasome pathway has a positive regulatory role for optimal NER capacity in mammalian cells and appears to act through facilitating the recruitment of repair factors to DNA damage sites.
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Affiliation(s)
- Qi-En Wang
- Department of Radiology, The Ohio State University, Columbus, Ohio 43210, USA
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Verma S, Ismail A, Gao X, Fu G, Li X, O'Malley BW, Nawaz Z. The ubiquitin-conjugating enzyme UBCH7 acts as a coactivator for steroid hormone receptors. Mol Cell Biol 2004; 24:8716-26. [PMID: 15367689 PMCID: PMC516762 DOI: 10.1128/mcb.24.19.8716-8726.2004] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We investigated the role of the ubiquitin-conjugating enzyme UBCH7 in nuclear receptor transactivation. Using transient transfection assays, we demonstrated that UBCH7 modulates the transcriptional activity of progesterone receptor (PR) and glucocorticoid, androgen, and retinoic acid receptors in a hormone-dependent manner and that the ubiquitin conjugation activity of UBCH7 is required for its ability to potentiate transactivation by steroid hormone receptors (SHR). However, UBCH7 showed no significant effect on the transactivation functions of p53 and VP-16 activation domain. Depletion of endogenous UBCH7 protein by small interfering RNAs suggests that UBCH7 is required for the proper function of SHR. Furthermore, a chromatin immunoprecipitation assay demonstrated the hormone-dependent recruitment of UBCH7 onto estrogen receptor- and PR-responsive promoters. Additionally, we show that UBCH7 and E6-associated protein (E6-AP) synergistically enhance PR transactivation. We also demonstrate that UBCH7 interacts with steroid receptor coactivator 1 (SRC-1) and that UBCH7 coactivation function is dependent on SRC-1. Taken together, our results reveal the possible role of UBCH7 in steroid receptor transactivation and provide insights into the mechanism of action of UBCH7 in receptor function.
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Affiliation(s)
- Seema Verma
- Cancer Center, Criss III, Room 352, Creighton University, 2500 California Plaza, Omaha, NE 68178, USA
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Bastien J, Rochette-Egly C. Nuclear retinoid receptors and the transcription of retinoid-target genes. Gene 2004; 328:1-16. [PMID: 15019979 DOI: 10.1016/j.gene.2003.12.005] [Citation(s) in RCA: 555] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2003] [Accepted: 12/02/2003] [Indexed: 11/18/2022]
Abstract
The pleiotropic effects of retinoids are mediated by nuclear retinoid receptors (RARs and RXRs) which are ligand-activated transcription factors. In response to retinoid binding, RAR/RXR heterodimers undergo major conformational changes and orchestrate the transcription of specific gene networks, through binding to specific DNA response elements and recruiting cofactor complexes that act to modify local chromatin structure and/or engage the basal transcription machinery. Then the degradation of RARs and RXRs by the ubiquitin-proteasome controls the magnitude and the duration of the retinoid response. RARs and RXRs also integrate a variety of signaling pathways through phosphorylation events which cooperate with the ligand for the control of retinoid-target genes transcription. These different modes of regulation reveal unexpected levels of complexity in the dynamics of retinoid-dependent transcription.
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Affiliation(s)
- Julie Bastien
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, UMR 7104, 1 rue Laurent Fries, BP 10142, Illkirch Cedex 67404, France
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Hara K, Shiota M, Kido H, Watanabe K, Nagata K, Toyoda T. Inhibition of the protease activity of influenza virus RNA polymerase PA subunit by viral matrix protein. Microbiol Immunol 2003; 47:521-6. [PMID: 12953845 DOI: 10.1111/j.1348-0421.2003.tb03413.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Influenza virus PA is a subunit of RNA-dependent RNA polymerase. We demonstrated that PA has a unique chymotrypsin-like serine protease activity with Ser624 as an active site. To obtain further insight into the role of the protease activity of PA in viral proliferation, we examined the interaction between PA and matrix protein (M1). Both M1 purified from virion and hexa-histidine-tagged M1 expressed in Escherichia coli bound to PA. Hexa-histidine-tagged M1 pulled down PA. The interaction of PA with M1 was sensitive to ionic strength, suggesting that the interaction is formed by electrostatic force. Using Suc-Leu-Leu-Val-Tyr-MCA, a specific substrate for PA protease, M1 was demonstrated to inhibit the amidolytic activity of PA, whereas M1 did not inhibit that of chymotrypsin or trypsin at all. These results suggest that M1 binds to and inhibits the amidolytic activity of PA.
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Affiliation(s)
- Koyu Hara
- Department of Virology, Kurume University School of Medicine, Kurume, Fukuoka 830-0011, Japan
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Zhang X, Grand RJA, McCabe CJ, Franklyn JA, Gallimore PH, Turnell AS. Transcriptional regulation of the human glycoprotein hormone common alpha subunit gene by cAMP-response-element-binding protein (CREB)-binding protein (CBP)/p300 and p53. Biochem J 2002; 368:191-201. [PMID: 12164786 PMCID: PMC1222971 DOI: 10.1042/bj20020634] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2002] [Revised: 08/05/2002] [Accepted: 08/07/2002] [Indexed: 12/13/2022]
Abstract
We have investigated the functional interactions between adenovirus early region 1A (AdE1A) protein, the co-activators cAMP-response-element-binding protein (CREB)-binding protein (CBP)/p300 and SUG1, and the transcriptional repressor retinoblastoma (Rb) in mediating T3-dependent repression. Utilizing the human glycoprotein hormone common alpha-subunit (alpha-subunit) promoter and AdE1A mutants with selective binding capacity to these molecules we have determined an essential role for CBP/p300. In normal circumstances, wild-type 12 S AdE1A inhibited alpha-subunit activity. In contrast, adenovirus mutants that retain both the SUG1- and Rb-binding sites, but lack the CBP/p300-binding site, were unable to repress promoter activity. We have also identified a role for the tumour-suppressor gene product p53 in regulation of the alpha-subunit promoter. Akin to 12 S AdE1A, exogenous p53 expression repressed alpha-subunit activity. This function resided in the ability of p53 to interact with CBP/p300; an N-terminal mutant incapable of interacting with CBP/p300 did not inhibit alpha-subunit activity. Stabilization of endogenous p53 by UV irradiation also correlated positively with reduced alpha-subunit activity. Intriguingly, T3 stimulated endogenous p53 transcriptional activity, implicating p53 in T3-dependent signalling pathways. These data indicate that CBP/p300 and p53 are key regulators of alpha-subunit activity.
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Affiliation(s)
- Xian Zhang
- Cancer Research U.K. Institute for Cancer Studies, The Medical School, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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Giannì M, Bauer A, Garattini E, Chambon P, Rochette-Egly C. Phosphorylation by p38MAPK and recruitment of SUG-1 are required for RA-induced RAR gamma degradation and transactivation. EMBO J 2002; 21:3760-9. [PMID: 12110588 PMCID: PMC126119 DOI: 10.1093/emboj/cdf374] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2002] [Revised: 05/22/2002] [Accepted: 05/24/2002] [Indexed: 01/29/2023] Open
Abstract
The nuclear retinoic acid receptor RAR gamma 2 undergoes proteasome-dependent degradation upon ligand binding. Here we provide evidence that the domains that signal proteasome-mediated degradation overlap with those that activate transcription, i.e. the activation domains AF-1 and AF-2. The AF-1 domain signals RAR gamma 2 degradation through its phosphorylation by p38MAPK in response to RA. The AF-2 domain acts via the recruitment of SUG-1, which belongs to the 19S regulatory subunit of the 26S proteasome. Blocking RAR gamma 2 degradation through inhibition of either the p38MAPK pathway or the 26S proteasome function impairs its RA-induced transactivation activity. Thus, the turnover of RAR gamma 2 is linked to transactivation.
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Affiliation(s)
- Maurizio Giannì
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP/Collège de France, BP 163, 67404 Illkirch cedex, France and Laboratorio di Biologia Molecolare, Istituto di Ricerche Farmacologiche Mario Negri, Via Eritrea 62, 20157 Milano, Italy Present address: Laboratorio di Biologia Molecolare, Istituto di Ricerche Farmacologiche Mario Negri, Via Eritrea 62, 20157 Milano, Italy Corresponding author e-mail:
| | - Annie Bauer
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP/Collège de France, BP 163, 67404 Illkirch cedex, France and Laboratorio di Biologia Molecolare, Istituto di Ricerche Farmacologiche Mario Negri, Via Eritrea 62, 20157 Milano, Italy Present address: Laboratorio di Biologia Molecolare, Istituto di Ricerche Farmacologiche Mario Negri, Via Eritrea 62, 20157 Milano, Italy Corresponding author e-mail:
| | - Enrico Garattini
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP/Collège de France, BP 163, 67404 Illkirch cedex, France and Laboratorio di Biologia Molecolare, Istituto di Ricerche Farmacologiche Mario Negri, Via Eritrea 62, 20157 Milano, Italy Present address: Laboratorio di Biologia Molecolare, Istituto di Ricerche Farmacologiche Mario Negri, Via Eritrea 62, 20157 Milano, Italy Corresponding author e-mail:
| | - Pierre Chambon
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP/Collège de France, BP 163, 67404 Illkirch cedex, France and Laboratorio di Biologia Molecolare, Istituto di Ricerche Farmacologiche Mario Negri, Via Eritrea 62, 20157 Milano, Italy Present address: Laboratorio di Biologia Molecolare, Istituto di Ricerche Farmacologiche Mario Negri, Via Eritrea 62, 20157 Milano, Italy Corresponding author e-mail:
| | - Cécile Rochette-Egly
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP/Collège de France, BP 163, 67404 Illkirch cedex, France and Laboratorio di Biologia Molecolare, Istituto di Ricerche Farmacologiche Mario Negri, Via Eritrea 62, 20157 Milano, Italy Present address: Laboratorio di Biologia Molecolare, Istituto di Ricerche Farmacologiche Mario Negri, Via Eritrea 62, 20157 Milano, Italy Corresponding author e-mail:
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17
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Dawson S, Apcher S, Mee M, Higashitsuji H, Baker R, Uhle S, Dubiel W, Fujita J, Mayer RJ. Gankyrin is an ankyrin-repeat oncoprotein that interacts with CDK4 kinase and the S6 ATPase of the 26 S proteasome. J Biol Chem 2002; 277:10893-902. [PMID: 11779854 DOI: 10.1074/jbc.m107313200] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
A yeast two-hybrid screen with the human S6 (TBP7, RPT3) ATPase of the 26 S proteasome has identified gankyrin, a liver oncoprotein, as an interacting protein. Gankyrin interacts with both free and regulatory complex-associated S6 ATPase and is not stably associated with the 26 S particle. Deletional mutagenesis shows that the C-terminal 78 amino acids of the S6 ATPase are necessary and sufficient to mediate the interaction with gankyrin. Deletion of an orthologous gene in Saccharomyces cerevisiae suggests that it is dispensable for cell growth and viability. Overexpression and precipitation of tagged gankyrin from cultured cells detects a complex containing co-transfected tagged S6 ATPase (or endogenous S6) and endogenous cyclin D-dependent kinase CDK4. The proteasomal ATPases are part of the AAA (ATPases associated with diverse cellular activities) family, members of which are molecular chaperones; gankyrin complexes may therefore influence CDK4 function during oncogenesis.
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Affiliation(s)
- Simon Dawson
- Laboratory of Intracellular Proteolysis, School of Biomedical Sciences, University of Nottingham Medical School, Queen's Medical Centre, Nottingham NG7 2UH, United Kingdom.
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18
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Gallimore PH, Turnell AS. Adenovirus E1A: remodelling the host cell, a life or death experience. Oncogene 2001; 20:7824-35. [PMID: 11753665 DOI: 10.1038/sj.onc.1204913] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- P H Gallimore
- CRC Institute for Cancer Studies, The Medical School, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
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19
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Ingley E, Chappell D, Poon SY, Sarna MK, Beaumont JG, Williams JH, Stillitano JP, Tsai S, Leedman PJ, Tilbrook PA, Klinken SP. Thyroid hormone receptor-interacting protein 1 modulates cytokine and nuclear hormone signaling in erythroid cells. J Biol Chem 2001; 276:43428-34. [PMID: 11544260 DOI: 10.1074/jbc.m106645200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Erythropoietin (Epo) and thyroid hormone (T(3)) are key molecules in the development of red blood cells. We have shown previously that the tyrosine kinase Lyn is involved in differentiation signals emanating from an activated erythropoietin receptor. Here we demonstrate that Lyn interacts with thyroid hormone receptor-interacting protein 1 (Trip-1), a transcriptional regulator associated with the T(3) receptor, providing a link between the Epo and T(3) signaling pathways. Trip-1 co-localized with Lyn and the T(3) receptor alpha in the cytoplasm/plasma membrane of erythroid cells but translocated to discrete nuclear foci shortly after Epo-induced differentiation. Our data reveal that T(3) stimulated the proliferation of immature erythroid cells, and inhibited maturation promoted by erythropoietin. Removal of T(3) reduced cell division and enhanced terminal differentiation. This was accompanied by large increases in the cell cycle inhibitor p27(Kip1) and by increasing expression of erythroid transcription factors GATA-1, EKLF, and NF-E2. Strikingly, a truncated Trip-1 inhibited both erythropoietin-induced maturation and T(3)-initiated cell division. This mutant Trip-1 acted in a dominant negative fashion by eliminating endogenous Lyn, elevating p27(Kip1), and blocking T(3) response elements. These data demonstrate that Trip-1 can simultaneously modulate responses involving both cytokine and nuclear receptors.
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Affiliation(s)
- E Ingley
- Laboratory for Cancer Medicine, Western Australian Institute for Medical Research, Royal Perth Hospital and the Department of Biochemistry, University of Western Australia, Perth, Western Australia 6000, Australia
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20
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Ishizuka T, Satoh T, Monden T, Shibusawa N, Hashida T, Yamada M, Mori M. Human immunodeficiency virus type 1 Tat binding protein-1 is a transcriptional coactivator specific for TR. Mol Endocrinol 2001; 15:1329-43. [PMID: 11463857 DOI: 10.1210/mend.15.8.0680] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The DNA-binding domain of nuclear hormone receptors functions as an interaction interface for other transcription factors. Using the DNA-binding domain of TRbeta1 as bait in the yeast two-hybrid system, we cloned the Tat binding protein-1 that was originally isolated as a protein binding to the human immunodeficiency virus type 1 Tat transactivator. Tat binding protein-1 has subsequently been identified as a member of the ATPase family and a component of the 26S proteasome. Tat binding protein-1 interacted with the DNA-binding domain but not with the ligand binding domain of TR in vivo and in vitro. TR bound to the amino-terminal portion of Tat binding protein-1 that contains a leucine zipper-like structure. In mammalian cells, Tat binding protein-1 potentiated the ligand-dependent transactivation by TRbeta1 and TRalpha1 via thyroid hormone response elements. Both the intact DNA-binding domain and activation function-2 of the TR were required for the transcriptional enhancement in the presence of Tat binding protein-1. Tat binding protein-1 did not augment the transactivation function of the RAR, RXR, PPARgamma, or ER. The intrinsic activation domain in Tat binding protein-1 resided within the carboxyl-terminal conserved ATPase domain, and a mutation of a putative ATP binding motif but not a helicase motif in the carboxyl-terminal conserved ATPase domain abolished the activation function. Tat binding protein-1 synergistically activated the TR-mediated transcription with the steroid receptor coactivator 1, p120, and cAMP response element-binding protein, although Tat binding protein-1 did not directly interact with these coactivators in vitro. In contrast, the N-terminal portion of Tat binding protein-1 directly interacted in vitro and in vivo with the TR-interacting protein 1 possessing an ATPase activity that interacts with the activation function-2 of liganded TR. Collectively, Tat binding protein-1 might function as a novel DNA-binding domain-binding transcriptional coactivator specific for the TR probably in cooperation with other activation function-2-interacting cofactors such as TR-interacting protein 1.
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Affiliation(s)
- T Ishizuka
- First Department of Internal Medicine, Gunma University School of Medicine 3-39-15, Maebashi 371-8511, Japan
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21
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Ferdous A, Gonzalez F, Sun L, Kodadek T, Johnston SA. The 19S regulatory particle of the proteasome is required for efficient transcription elongation by RNA polymerase II. Mol Cell 2001; 7:981-91. [PMID: 11389845 DOI: 10.1016/s1097-2765(01)00250-7] [Citation(s) in RCA: 220] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
It is generally thought that the primary or even sole activity of the 19S regulatory particle of the 26S proteasome is to facilitate the degradation of polyubiquitinated proteins by the 20S-core subunit. However, we present evidence that the 19S complex is required for efficient elongation of RNA polymerase II (RNAP II) in vitro and in vivo. First, yeast strains carrying alleles of SUG1 and SUG2, encoding 19S components, exhibit phenotypes indicative of elongation defects. Second, in vitro transcription is inhibited by antibodies raised against Sug1, or by heat-inactivating temperature-sensitive Sug1 mutants with restoration of elongation by addition of immunopurified 19S complex. Finally, Cdc68, a known elongation factor, coimmunoprecipitates with the 19S complex, indicating a physical interaction. Inhibition of the 20S proteolytic core of the proteasome has no effect on elongation. This work defines a nonproteolytic role for the 19S complex in RNAP II transcription.
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Affiliation(s)
- A Ferdous
- Departments of Internal Medicine and Biochemistry, Ryburn Center for Molecular Cardiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX7 5390-8573, USA
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22
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Abstract
The HBV X protein (HBx) is implicated in infection and development of hepatocellular carcinoma. HBx has a pleiotropic effect on cells, suggesting multiple targets in the virus-host cell interaction. We employed the cytoplasmic-based two-hybrid screen and identified the HIV Tat-binding protein 1 (Tbp1) as a novel HBx interacting protein. Tbp1 interacts in vivo with HBx both in yeast and in animal cells. This interaction maps to the functionally important ATP-binding motif of Tbp1. Furthermore, HBx and Tbp1 interaction is functionally significant and regulates HBV transcription. Tbp1 homologues, such as Sug1, are known members of the proteasome 19S regulatory cap particle and have also been implicated in transcription coactivation. Remarkably, Tbp1 and Sug1 interact with multiple viral effector proteins including HIV Tat, SV40 large T antigen, and adenovirus E1A, establishing these proteins as important targets of the viral oncogenes.
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Affiliation(s)
- O Barak
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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23
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Hara K, Shiota M, Kido H, Ohtsu Y, Kashiwagi T, Iwahashi J, Hamada N, Mizoue K, Tsumura N, Kato H, Toyoda T. Influenza virus RNA polymerase PA subunit is a novel serine protease with Ser624 at the active site. Genes Cells 2001; 6:87-97. [PMID: 11260254 DOI: 10.1046/j.1365-2443.2001.00399.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Influenza virus RNA polymerase is a multifunctional enzyme that catalyses both transcription and replication of the RNA genome. The function of the influenza virus RNA polymerase PA subunit in viral replication is poorly understood, although the enzyme is known to be required for cRNA --> vRNA synthesis. The protease related activity of PA has been discussed ever since protease-inducing activity was demonstrated in transfection experiments. RESULTS PA protein was highly purified from insect cells infected with the recombinant baculovirus carrying PA cDNA, and a novel chymotrypsin-type serine protease activity was identified with the synthetic peptide, Suc-LLVY-MCA, in the PA protein. [3H]DFP was crosslinked with PA and a mutational analysis revealed that serine624 was as an active site for the protease activity. CONCLUSIONS These results constitute the demonstration of protease activity in PA subunit of the influenza virus RNA polymerase complexes.
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Affiliation(s)
- K Hara
- Departments of Virology, Kurume University School of Medicine, Kurume 830-0011, Japan
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24
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Yanagi S, Shimbara N, Tamura TA. Tissue and cell distribution of a mammalian proteasomal ATPase, MSS1, and its complex formation with the basal transcription factors. Biochem Biophys Res Commun 2000; 279:568-73. [PMID: 11118327 DOI: 10.1006/bbrc.2000.3969] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The proteasome is an eukaryotic multi-subunit protease complex composed of one 20S core component and two 19S regulatory complexes. The regulatory complex contains 6 putative ATPases. We investigated tissue and cell distribution of one of these ATPases, MSS1 (mammalian suppressor of sgv1). MSS1 was ubiquitously present in rat tissues as was the 20S core component of proteasome. However, the ratio of MSS1 to 20S varied greatly among tissues and MSS1 was concentrated in the thymus. Glycerol gradient sedimentation analysis revealed that MSS1 is included in protein complexes whose density is lighter than that of the proteasome. MSS1 was distributed in mammalian cells ubiquitously, while proteasome was rather concentrated in the nuclei. Hence, a novel molecular status of MSS1 distinct from proteasome is implicated. Interestingly, multiple basal transcription factors for RNA polymerase II, including TBP, TFIIB, TFIIH, and TFIIF, were found to be associated with MSS1. These results suggest that MSS1, in addition to proteolysis, plays a role in DNA metabolism including transcriptional regulation.
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Affiliation(s)
- S Yanagi
- Department of Biology, Faculty of Science, Chiba University, Japan
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25
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Löw P, Hastings RA, Dawson SP, Sass M, Billett MA, Mayer RJ, Reynolds SE. Localisation of 26S proteasomes with different subunit composition in insect muscles undergoing programmed cell death. Cell Death Differ 2000; 7:1210-7. [PMID: 11175258 DOI: 10.1038/sj.cdd.4400743] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The 26S proteasome is a large multisubunit complex involved in degrading both cytoplasmic and nuclear proteins. We have investigated the subcellular distribution of four regulatory ATPase subunits (S6 (TBP7/MS73), S6' (TBP1), S7 (MSS1), and S10b (SUG2)) together with components of 20S proteasomes in the intersegmental muscles (ISM) of Manduca sexta during developmentally programmed cell death (PCD). Immunogold electron microscopy shows that S6 is located in the heterochromatic part of nuclei of ISM fibres. S6' is present in degraded material only outside intact fibres. S7 can be detected in nuclei, cytoplasm and also in degraded material. S10b, on the other hand, is initially found in nuclei and subsequently in degraded cytoplasmic locations during PCD. 20S proteasomes are present in all areas where ATPase subunits are detected, consistent with the presence of intact 26S proteasomes. These results are discussed in terms of heterogeneity of 26S proteasomes, 26S proteasome disassembly and the possible role of ATPases in non-proteasome complexes in the process of PCD. Cell Death and Differentiation (2000) 7, 1210 - 1217.
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Affiliation(s)
- P Löw
- Department of General Zoology, Eötvös University, Budapest, Hungary.
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26
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Kopf E, Plassat JL, Vivat V, de Thé H, Chambon P, Rochette-Egly C. Dimerization with retinoid X receptors and phosphorylation modulate the retinoic acid-induced degradation of retinoic acid receptors alpha and gamma through the ubiquitin-proteasome pathway. J Biol Chem 2000; 275:33280-8. [PMID: 10869350 DOI: 10.1074/jbc.m002840200] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
In eukaryotic cells, the ubiquitin-proteasome pathway is the major mechanism for targeted degradation of proteins. We show that, in F9 cells and in transfected COS-1 cells, the nuclear retinoid receptors, retinoic acid receptor gamma2 (RARgamma2), RARalpha1, and retinoid X receptor alpha1 (RXRalpha1) are degraded in a retinoic acid-dependent manner through the ubiquitin-proteasome pathway. The degradation of RARgamma2 is entirely dependent on its phosphorylation and on its heterodimerization with liganded RXRalpha1. In contrast, RARalpha1 degradation can occur in the absence of heterodimerization, whereas it is inhibited by phosphorylation, and heterodimerization reverses that inhibition. RXRalpha1 degradation is also modulated by heterodimerization. Thus, each partner of RARgamma/RXRalpha and RARalpha/RXRalpha heterodimers modulates the degradation of the other. We conclude that the ligand-dependent degradation of RARs and RXRs by the ubiquitin-proteasome pathway, which is regulated by heterodimerization and by phosphorylation, could be important for the regulation of the magnitude and duration of the effects of retinoid signals.
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Affiliation(s)
- E Kopf
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP/Collège de France, BP 163, 67404 Illkirch Cedex, CU de Strasbourg, France
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27
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Turnell AS, Grand RJ, Gorbea C, Zhang X, Wang W, Mymryk JS, Gallimore PH. Regulation of the 26S proteasome by adenovirus E1A. EMBO J 2000; 19:4759-73. [PMID: 10970867 PMCID: PMC302057 DOI: 10.1093/emboj/19.17.4759] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have identified the N-terminus of adenovirus early region 1A (AdE1A) as a region that can regulate the 26S proteasome. Specifically, in vitro and in vivo co-precipitation studies have revealed that the 19S regulatory components of the proteasome, Sug1 (S8) and S4, bind through amino acids (aa) 4-25 of Ad5 E1A. In vivo expression of wild-type (wt) AdE1A, in contrast to the N-terminal AdE1A mutant that does not bind the proteasome, reduces ATPase activity associated with anti-S4 immunoprecipitates relative to mock-infected cells. This reduction in ATPase activity correlates positively with the ability of wt AdE1A, but not the N-terminal deletion mutant, to significantly reduce the ability of HPV16 E6 to target p53 for ubiquitin-mediated proteasomal degradation. AdE1A/proteasomal complexes are present in both the cytoplasm and the nucleus, suggesting that AdE1A interferes with both nuclear and cytoplasmic proteasomal degradation. We have also demonstrated that wt AdE1A and the N-terminal AdE1A deletion mutant are substrates for proteasomal-mediated degradation. AdE1A degradation is not, however, mediated through ubiquitylation, but is regulated through phosphorylation of residues within a C-terminal PEST region (aa 224-238).
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Affiliation(s)
- A S Turnell
- CRC Institute for Cancer Studies, The Medical School, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
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28
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Voges D, Zwickl P, Baumeister W. The 26S proteasome: a molecular machine designed for controlled proteolysis. Annu Rev Biochem 2000; 68:1015-68. [PMID: 10872471 DOI: 10.1146/annurev.biochem.68.1.1015] [Citation(s) in RCA: 1377] [Impact Index Per Article: 57.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In eukaryotic cells, most proteins in the cytosol and nucleus are degraded via the ubiquitin-proteasome pathway. The 26S proteasome is a 2.5-MDa molecular machine built from approximately 31 different subunits, which catalyzes protein degradation. It contains a barrel-shaped proteolytic core complex (the 20S proteasome), capped at one or both ends by 19S regulatory complexes, which recognize ubiquitinated proteins. The regulatory complexes are also implicated in unfolding and translocation of ubiquitinated targets into the interior of the 20S complex, where they are degraded to oligopeptides. Structure, assembly and enzymatic mechanism of the 20S complex have been elucidated, but the functional organization of the 19S complex is less well understood. Most subunits of the 19S complex have been identified, however, specific functions have been assigned to only a few. A low-resolution structure of the 26S proteasome has been obtained by electron microscopy, but the precise arrangement of subunits in the 19S complex is unclear.
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Affiliation(s)
- D Voges
- Max-Planck-Institut für Biochemie, Martinsried, Germany
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29
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Affiliation(s)
- C M Klinge
- Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, Louisville, KY 40292, USA.
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30
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De Graeve F, Bahr A, Chatton B, Kedinger C. A murine ATFa-associated factor with transcriptional repressing activity. Oncogene 2000; 19:1807-19. [PMID: 10777215 DOI: 10.1038/sj.onc.1203492] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The ATFa proteins, which are members of the CREB/ATF family of transcription factors, have previously been shown to interact with the adenovirus E1a oncoprotein and to mediate its transcriptional activity; they heterodimerize with Jun, Fos or related transcription factors, possibly altering their DNA-binding specificity; they also stably bind JNK2, a stress-induced protein kinase. Here we report the identification and characterization of a novel protein isolated in a yeast two-hybrid screen using the N-terminal half of ATFa as a bait. This 1306-residue protein (mAM, for mouse ATFa-associated Modulator) is rather acidic (pHi 4.5) and contains high proportions of Ser/Thr (21%) and Pro (11%) residues. It colocalizes and interacts with ATFa in mammalian cells, contains a bipartite nuclear localization signal and possesses an ATPase activity. Transfection experiments show that mAM is able to downregulate transcriptional activity, in an ATPase-independent manner. Our results indicate that mAM interacts with several components of the basal transcription machinery (TFIIE and TFIIH), including RNAPII itself. Together, these findings suggest that mAM may be involved in the fine-tuning of ATFa-regulated gene expression, by interfering with the assembly or stability of specific preinitiation transcription complexes.
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Affiliation(s)
- F De Graeve
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, Illkirch, Communauté Urbaine de Strasbourg, France
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31
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Rong SB, Väliaho J, Vihinen M. Structural Basis of Bloom Syndrome (BS) Causing Mutations in the BLM Helicase Domain. Mol Med 2000. [DOI: 10.1007/bf03402111] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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32
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Karata K, Inagawa T, Wilkinson AJ, Tatsuta T, Ogura T. Dissecting the role of a conserved motif (the second region of homology) in the AAA family of ATPases. Site-directed mutagenesis of the ATP-dependent protease FtsH. J Biol Chem 1999; 274:26225-32. [PMID: 10473576 DOI: 10.1074/jbc.274.37.26225] [Citation(s) in RCA: 166] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Escherichia coli FtsH is an ATP-dependent protease that belongs to the AAA protein family. The second region of homology (SRH) is a highly conserved motif among AAA family members and distinguishes these proteins in part from the wider family of Walker-type ATPases. Despite its conservation across the AAA family of proteins, very little is known concerning the function of the SRH. To address this question, we introduced point mutations systematically into the SRH of FtsH and studied the activities of the mutant proteins. Highly conserved amino acid residues within the SRH were found to be critical for the function of FtsH, with mutations at these positions leading to decreased or abolished ATPase activity. The effects of the mutations on the protease activity of FtsH correlated strikingly with their effects on the ATPase activity. The ATPase-deficient SRH mutants underwent an ATP-induced conformational change similar to wild type FtsH, suggesting an important role for the SRH in ATP hydrolysis but not ATP binding. Analysis of the data in the light of the crystal structure of the hexamerization domain of N-ethylmaleimide-sensitive fusion protein suggests a plausible mechanism of ATP hydrolysis by the AAA ATPases, which invokes an intermolecular catalytic role for the SRH.
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Affiliation(s)
- K Karata
- Department of Molecular Cell Biology, Institute of Molecular Embryology, Kumamoto University School of Medicine, Kumamoto 862-0976, Japan
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33
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Hastings RA, Eyheralde I, Dawson SP, Walker G, Reynolds SE, Billett MA, Mayer RJ. A 220-kDa activator complex of the 26 S proteasome in insects and humans. A role in type II programmed insect muscle cell death and cross-activation of proteasomes from different species. J Biol Chem 1999; 274:25691-700. [PMID: 10464306 DOI: 10.1074/jbc.274.36.25691] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The S10b (SUG2) ATPase cDNA has been cloned by reverse transcription-polymerase chain reaction/rapid amplification of cDNA ends from mRNA of intersegmental muscles of the tobacco horn moth (Manduca sexta). The S10b ATPase is a component of the 26 S proteasome, and its concentration and that of its mRNA increase dramatically during development in a manner similar to other ATPases of the 19 S regulator of the 26 S proteasome. The S10b and S6' (TBP1) ATPases are also present in a complex of approximately 220 kDa in intersegmental muscles. The 220-kDa complex markedly activates (2-10-fold) the 26 S proteasome, even when bound to anti-S10b antibodies immobilized on Sepharose, and increases in concentration approximately 5-fold like the 26 S proteasome in the intersegmental muscles in preparation for the programmed death of the muscle cells. A similar activator complex is present in human brain and placenta. Free activator complexes cross-activate: the Manduca complex activates rat skeletal muscle 26 S proteasomes, and the placental complex activates Manduca 26 S proteasomes. The placental activator complex contains S10b and S6', but not p27. This 220-kDa activator complex has been evolutionarily conserved between species from insect to man and may have a fundamental role in proteasome regulation.
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Affiliation(s)
- R A Hastings
- Laboratory for Intracellular Proteolysis, Molecular and Cellular Biology Section, School of Biomedical Sciences, Faculty of Medicine, University of Nottingham Medical School, Clifton Boulevard, Nottingham NG7 2UH, United Kingdom
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34
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Makino Y, Yoshida T, Yogosawa S, Tanaka K, Muramatsu M, Tamura TA. Multiple mammalian proteasomal ATPases, but not proteasome itself, are associated with TATA-binding protein and a novel transcriptional activator, TIP120. Genes Cells 1999; 4:529-39. [PMID: 10526239 DOI: 10.1046/j.1365-2443.1999.00277.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND SUG1 belongs to proteasomal ATPase. Previous studies have demonstrated that SUG1 is associated with TBP. It is assumed to be involved in transcriptional regulation in addition to proteolysis. In this study, we investigated the association of mammalian SUG1 with TBP in more detail. RESULTS Pull-down experiments with TBP revealed multiple TBP-interacting proteins (TIPs) that were recovered dependent upon the presence of C-terminal conserved domain of TBP. By 2-D electrophoresis, we identified SUG1 in TIPs. By using far-Western analysis, we identified two proteins that could directly bind to TBP: SUG1 and another proteasomal ATPase (S4). Protein microsequencing and Western blotting identified all the remaining proteasomal ATPases (MSS1, TBP1, TBP7, and SUG2) in the TIP preparations. We present evidence that TBP and at least SUG1, MSS1, and S4 form a complex in the cell. However, no evidence of association of TBP with the 26S proteasome or its 19S regulatory unit was obtained. The molecular mass of the TBP/ATPases-complex, which also included a novel transcription regulatory factor, TIP120, was estimated to be approximately 800 kDa. CONCLUSION These results suggest that there is a novel multisubunit complex containing TBP and proteasomal ATPases. Based on our findings, we hypothesize that proteasomal ATPases are involved in transcriptional regulation in addition to proteolysis.
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Affiliation(s)
- Y Makino
- Department of Biology, Faculty of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
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35
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Lunkes A, Trottier Y, Fagart J, Schultz P, Zeder-Lutz G, Moras D, Mandel JL. Properties of polyglutamine expansion in vitro and in a cellular model for Huntington's disease. Philos Trans R Soc Lond B Biol Sci 1999; 354:1013-9. [PMID: 10434300 PMCID: PMC1692598 DOI: 10.1098/rstb.1999.0453] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Eight neurodegenerative diseases have been shown to be caused by the expansion of a polyglutamine stretch in specific target proteins that lead to a gain in toxic property. Most of these diseases have some features in common. A pathological threshold of 35-40 glutamine residues is observed in five of the diseases. The mutated proteins (or a polyglutamine-containing subfragment) form ubiquitinated aggregates in neurons of patients or mouse models, in most cases within the nucleus. We summarize the properties of a monoclonal antibody that recognizes specifically, in a Western blot, polyglutamine stretches longer than 35 glutamine residues with an affinity that increases with polyglutamine length. This indicates that the pathological threshold observed in five diseases corresponds to a conformational change creating a pathological epitope, most probably involved in the aggregation property of the carrier protein. We also show that a fragment of a normal protein carrying 38 glutamine residues is able to aggregate into regular fibrils in vitro. Finally, we present a cellular model in which the induced expression of a mutated full-length huntingtin protein leads to the formation of nuclear inclusions that share many characteristics with those observed in patients: those inclusions are ubiquitinated and contain only an N-terminal fragment of huntingtin. This model should thus be useful in studying a processing step that is likely to be important in the pathogenicity of mutated huntingtin.
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Affiliation(s)
- A Lunkes
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS/INSERM/ULP, Illkirch, CU de Strasbourg, France
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36
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Russell SJ, Reed SH, Huang W, Friedberg EC, Johnston SA. The 19S regulatory complex of the proteasome functions independently of proteolysis in nucleotide excision repair. Mol Cell 1999; 3:687-95. [PMID: 10394357 DOI: 10.1016/s1097-2765(01)80001-0] [Citation(s) in RCA: 164] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The 26S proteasome degrades proteins targeted by the ubiquitin pathway, a function thought to explain its role in cellular processes. The proteasome interacts with the ubiquitin-like N terminus of Rad23, a nucleotide excision repair (NER) protein, in Saccharomyces cerevisiae. Deletion of the ubiquitin-like domain causes UV radiation sensitivity. Here, we show that the ubiquitin-like domain of Rad23 is required for optimal activity of an in vitro NER system. Inhibition of proteasomal ATPases diminishes NER activity in vitro and increases UV sensitivity in vivo. Surprisingly, blockage of protein degradation by the proteasome has no effect on the efficiency of NER. This establishes that the regulatory complex of the proteasome has a function independent of protein degradation.
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Affiliation(s)
- S J Russell
- Department of Medicine and Biochemistry, University of Texas Southwestern Medical Center, Dallas 75235, USA
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37
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Deconstructing a Disease: RAR, Its Fusion Partners, and Their Roles in the Pathogenesis of Acute Promyelocytic Leukemia. Blood 1999. [DOI: 10.1182/blood.v93.10.3167.410k44_3167_3215] [Citation(s) in RCA: 808] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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38
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Mannhaupt G, Schnall R, Karpov V, Vetter I, Feldmann H. Rpn4p acts as a transcription factor by binding to PACE, a nonamer box found upstream of 26S proteasomal and other genes in yeast. FEBS Lett 1999; 450:27-34. [PMID: 10350051 DOI: 10.1016/s0014-5793(99)00467-6] [Citation(s) in RCA: 256] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We identified a new, unique upstream activating sequence (5'-GGTGGCAAA-3') in the promoters of 26 out of the 32 proteasomal yeast genes characterized to date, which we propose to call proteasome-associated control element. By using the one-hybrid method, we show that the factor binding to the proteasome-associated control element is Rpn4p, a protein containing a C2H2-type finger motif and two acidic domains. Electrophoretic mobility shift assays using proteasome-associated control element sequences from two regulatory proteasomal genes confirmed specific binding of purified Rpn4p to these sequences. The role of Rpn4p to function as a transregulator in yeast is corroborated by its ability of stimulating proteasome-associated control element-driven lacZ expression and by experiments using the RPT4 and RPT6 gene promoters coupled to the bacterial cat gene as a reporter. Additionally, we found the proteasome-associated control element to occur in a number of promoters to genes which are related to the ubiquitin-proteasome pathway in yeast.
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Affiliation(s)
- G Mannhaupt
- Adolf-Butenandt-Institut der Ludwig-Maximilians-Universität München, Germany
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39
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Nawaz Z, Lonard DM, Dennis AP, Smith CL, O'Malley BW. Proteasome-dependent degradation of the human estrogen receptor. Proc Natl Acad Sci U S A 1999; 96:1858-62. [PMID: 10051559 PMCID: PMC26701 DOI: 10.1073/pnas.96.5.1858] [Citation(s) in RCA: 438] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
In eukaryotic cells, the ubiquitin-proteasome pathway is the major mechanism for the targeted degradation of proteins with short half-lives. The covalent attachment of ubiquitin to lysine residues of targeted proteins is a signal for the recognition and rapid degradation by the proteasome, a large multi-subunit protease. In this report, we demonstrate that the human estrogen receptor (ER) protein is rapidly degraded in mammalian cells in an estradiol-dependent manner. The treatment of mammalian cells with the proteasome inhibitor MG132 inhibits activity of the proteasome and blocks ER degradation, suggesting that ER protein is turned over through the ubiquitin-proteasome pathway. In addition, we show that in vitro ER degradation depends on ubiquitin-activating E1 enzyme (UBA) and ubiquitin-conjugating E2 enzymes (UBCs), and the proteasome inhibitors MG132 and lactacystin block ER protein degradation in vitro. Furthermore, the UBA/UBCs and proteasome inhibitors promote the accumulation of higher molecular weight forms of ER. The UBA and UBCs, which promote ER degradation in vitro, have no significant effect on human progesterone receptor and human thyroid hormone receptor beta proteins.
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Affiliation(s)
- Z Nawaz
- Department of Cell Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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40
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Shiratori A, Shibata T, Arisawa M, Hanaoka F, Murakami Y, Eki T. Systematic identification, classification, and characterization of the open reading frames which encode novel helicase-related proteins in Saccharomyces cerevisiae by gene disruption and Northern analysis. Yeast 1999; 15:219-53. [PMID: 10077188 DOI: 10.1002/(sici)1097-0061(199902)15:3<219::aid-yea349>3.0.co;2-3] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Helicase-related proteins play important roles in various cellular processes incuding DNA replication, DNA repair, RNA processing and so on. It has been well known that the amino acid sequences of these proteins contain several conserved motifs, and that the open reading frames (ORFs) which encode helicase-related proteins make up several gene families. In this study, we have identified 134 ORFs that encode helicase-like proteins in the Saccharomyces genome, based on similarity with the ORFs of authentic helicase and helicase-related proteins. Multiple alignment of the ORF sequences resulted in the 134 ORFs being classified to 11 clusters. Seven out of 21 previously uncharacterized ORFs (YDL031w, YDL070w, YDL084w, YGL150c, YKL078w, YLR276c, and YMR128w) were identified by systematic gene disruption, to be essential for vegetative growth. Three (YDR332w, YGL064c, and YOL095c) out of the remaining 14 dispensable ORFs exhibited the slow-growth phenotype at 30 degrees C and 37 degrees C. Furthermore, the expression profiles of transcripts from 43 ORFs were examined under seven different growth conditions by Northern analysis and reverse transcription-polymerase chain reaction, indicating that all of the 43 tested ORFs were transcribed. Interestingly, we found that the level of transcript from 34 helicase-like genes was markedly increased by heat shock. This suggests that helicase-like genes may be involved in the biosynthesis of nucleic acids and proteins, and that the genes can be transcriptionally activated by heat shock to compensate for the repressed synthesis of mRNA and protein.
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Affiliation(s)
- A Shiratori
- Cellular Physiology Laboratory, Tsukuba Life Science Center, The Institute of Physical and Chemical Research (RIKEN), Ibaraki, Japan
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41
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Grand RJ, Turnell AS, Mason GG, Wang W, Milner AE, Mymryk JS, Rookes SM, Rivett AJ, Gallimore PH. Adenovirus early region 1A protein binds to mammalian SUG1-a regulatory component of the proteasome. Oncogene 1999; 18:449-58. [PMID: 9927201 DOI: 10.1038/sj.onc.1202304] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Adenovirus early region 1A (Ad E1A) is a multifunctional protein which is essential for adenovirus-mediated transformation and oncogenesis. Whilst E1A is generally considered to exert its influence on recipient cells through regulation of transcription it also increases the level of cellular p53 by increasing the protein half-life. With this in view, we have investigated the relationship of Ad E1A to the proteasome, which is normally responsible for degradation of p53. Here we have shown that both Ad5 and Ad12 E1A 12S and 13S proteins can be co-immunoprecipitated with proteasomes and that the larger Ad12 E1A protein binds strongly to at least three components of the 26S but not 20S proteasome. One of these interacting species has been identified as mammalian SUGI, a proteasome regulatory component which also plays a role in the cell as a mediator of transcription. In vitro assays have demonstrated a direct interaction between Ad12 E1A 13S protein and mouse SUGI. Following infection of human cells with Ad5 wt and Ad5 mutants with lesions in the E1A gene it has been shown that human SUG1 can be co-immunoprecipitated with full-length E1A and with E1A carrying a deletion in conserved region 1 which is the region considered to be responsible for increased expression of p53. We have concluded therefore that Ad EIA binds strongly to SUGI but that this interaction is not responsible for inhibition of proteasome activity. This is consistent with the observation that purified Ad12 E1A inhibits the activity of the purified 20S but not 26S proteasomes. We have also demonstrated that SUGI can be co-immunoprecipitated with SV40 T and therefore we suggest that this may represent a common interaction of transforming proteins of DNA tumour viruses.
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Affiliation(s)
- R J Grand
- CRC Institute for Cancer Studies, University of Birmingham, Edgbaston, UK
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42
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Neuwald AF, Aravind L, Spouge JL, Koonin EV. AAA+: A Class of Chaperone-Like ATPases Associated with the Assembly, Operation, and Disassembly of Protein Complexes. Genome Res 1999. [DOI: 10.1101/gr.9.1.27] [Citation(s) in RCA: 716] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Using a combination of computer methods for iterative database searches and multiple sequence alignment, we show that protein sequences related to the AAA family of ATPases are far more prevalent than reported previously. Among these are regulatory components of Lon and Clp proteases, proteins involved in DNA replication, recombination, and restriction (including subunits of the origin recognition complex, replication factor C proteins, MCM DNA-licensing factors and the bacterial DnaA, RuvB, and McrB proteins), prokaryotic NtrC-related transcription regulators, the Bacillus sporulation protein SpoVJ, Mg2+, and Co2+ chelatases, theHalobacterium GvpN gas vesicle synthesis protein, dynein motor proteins, TorsinA, and Rubisco activase. Alignment of these sequences, in light of the structures of the clamp loader δ′ subunit ofEscherichia coli DNA polymerase III and the hexamerization component of N-ethylmaleimide-sensitive fusion protein, provides structural and mechanistic insights into these proteins, collectively designated the AAA+ class. Whole-genome analysis indicates that this class is ancient and has undergone considerable functional divergence prior to the emergence of the major divisions of life. These proteins often perform chaperone-like functions that assist in the assembly, operation, or disassembly of protein complexes. The hexameric architecture often associated with this class can provide a hole through which DNA or RNA can be thread; this may be important for assembly or remodeling of DNA–protein complexes.
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43
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Sabbah M, Kang KI, Tora L, Redeuilh G. Oestrogen receptor facilitates the formation of preinitiation complex assembly: involvement of the general transcription factor TFIIB. Biochem J 1998; 336 ( Pt 3):639-46. [PMID: 9841876 PMCID: PMC1219915 DOI: 10.1042/bj3360639] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The action of oestrogen hormones is mediated through the oestrogen receptor (ER), a member of a large superfamily of nuclear receptors that function as ligand-activated transcription factors. Sequence-specific transcription factors, including the nuclear receptor superfamily, are thought to interact either directly or indirectly with general transcription factors to regulate transcription. Although numerous studies have focused on the identification of potential co-activators interacting with isolated trans-activation domains of ER, few have investigated the mechanisms by which ER transmits its signal to the basal transcription machinery. We show that ER does not stabilize the binding of the TATA-box binding protein (TBP) of the TFIID complex, or of TFIIB to the promoter, although a stable ER-TBP-TFIIB-promoter complex was detected, suggesting that ER, TBP and TFIIB might interact with each other to form a complex to the promoter. We also demonstrate that ER binds specifically to TFIIB, a key component of the preinitiation complex. Affinity chromatography with immobilized deletion mutants of ER maps a TFIIB interaction region that encompasses the DNA-binding domain. The addition of excess TFIIB to transcription reactions in vitro did not, however, affect the magnitude of transcriptional activation by ER. These results indicate that, in contrast with current models, ER does not activate transcription by increasing the rate of assembly of TFIIB into the transcription complex. An increased concentration of TFIIB was unable, by itself, to overcome the requirement for ER. By using an immobilized promoter-template assay employing nuclear extract from HeLa cells, recombinant human ER increased the stable association of subsequent components of the transcription machinery (TFIIE and TFIIF), in correlation with ER-induced transcription. Our results suggest that ER acts, in an early step, during or immediately after the formation of template-committed complexes containing TFIIB, favouring the recruitment of one or more components of the basic transcription machinery as well as co-activators.
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Affiliation(s)
- M Sabbah
- INSERM U482, Hôpital Saint-Antoine, 184 Rue du Faubourg Saint-Antoine, 75571 Paris Cedex 12, France
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44
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Masuyama H, MacDonald PN. Proteasome-mediated degradation of the vitamin D receptor (VDR) and a putative role for SUG1 interaction with the AF-2 domain of VDR. J Cell Biochem 1998. [DOI: 10.1002/(sici)1097-4644(19981201)71:3<429::aid-jcb11>3.0.co;2-p] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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45
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Enenkel C, Lehmann A, Kloetzel PM. Subcellular distribution of proteasomes implicates a major location of protein degradation in the nuclear envelope-ER network in yeast. EMBO J 1998; 17:6144-54. [PMID: 9799224 PMCID: PMC1170941 DOI: 10.1093/emboj/17.21.6144] [Citation(s) in RCA: 187] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
26S proteasomes are the key enzyme complexes responsible for selective turnover of short-lived and misfolded proteins. Based on the assumption that they are dispersed over the nucleoplasm and cytoplasm in all eukaryotic cells, we wanted to determine the subcellular distribution of 26S proteasomes in living yeast cells. For this purpose, we generated yeast strains that express functional green fluorescent protein (GFP) fusions of proteasomal subunits. An alpha subunit of the proteolytically active 20S core complex of the 26S proteasome, Pre6/YOL038w, as well as an ATPase-type subunit of the regulatory 19S cap complex, Cim5/YOL145w, were tagged with GFP. Both chimeras were shown to be incorporated completely into active 26S proteasomes. Microscopic analysis revealed that GFP-labelled 20S as well as 19S subunits are accumulated mainly in the nuclear envelope (NE)-endoplasmic reticulum (ER) network in yeast. These findings were supported by the co-localization and co-enrichment of 26S proteasomes with NE-ER marker proteins. A major location of proteasomal peptide cleavage activity was visualized in the NE-ER network, indicating that proteasomal degradation takes place mainly in this subcellular compartment in yeast.
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Affiliation(s)
- C Enenkel
- Institut für Biochemie, Humboldt Universität, Universitätsklinikum Charité, Monbijoustrasse 2, D-10117 Berlin, Germany.
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46
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Rubin DM, Glickman MH, Larsen CN, Dhruvakumar S, Finley D. Active site mutants in the six regulatory particle ATPases reveal multiple roles for ATP in the proteasome. EMBO J 1998; 17:4909-19. [PMID: 9724628 PMCID: PMC1170820 DOI: 10.1093/emboj/17.17.4909] [Citation(s) in RCA: 250] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A family of ATPases resides within the regulatory particle of the proteasome. These proteins (Rpt1-Rpt6) have been proposed to mediate substrate unfolding, which may be required for translocation of substrates through the channel that leads from the regulatory particle into the proteolytic core particle. To analyze the role of ATP hydrolysis in protein breakdown at the level of the individual ATPase, we have introduced equivalent site-directed mutations into the ATPbinding motif of each RPT gene. Non-conservative substitutions of the active-site lysine were lethal in four of six cases, and conferred a strong growth defect in two cases. Thus, the ATPases are not functionally redundant, despite their multiplicity and sequence similarity. Degradation of a specific substrate can be inhibited by ATP-binding-site substitutions in many of the Rpt proteins, indicating that they co-operate in the degradation of individual substrates. The phenotypic defects of the different rpt mutants were strikingly varied. The most divergent phenotype was that of the rpt1 mutant, which was strongly growth defective despite showing no general defect in protein turnover. In addition, rpt1 was unique among the rpt mutants in displaying a G1 cell-cycle defect. Proteasomes purified from an rpt2 mutant showed a dramatic inhibition of peptidase activity, suggesting a defect in gating of the proteasome channel. In summary, ATP promotes protein breakdown by the proteasome through multiple mechanisms, as reflected by the diverse phenotypes of the rpt mutants.
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Affiliation(s)
- D M Rubin
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave, Boston, MA 02115, USA
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47
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Mykles DL. Intracellular proteinases of invertebrates: calcium-dependent and proteasome/ubiquitin-dependent systems. INTERNATIONAL REVIEW OF CYTOLOGY 1998; 184:157-289. [PMID: 9697313 DOI: 10.1016/s0074-7696(08)62181-6] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Cytosolic proteinases carry out a variety of regulatory functions by controlling protein levels and/or activities within cells. Calcium-dependent and ubiquitin/proteasome-dependent pathways are common to all eukaryotes. The former pathway consists of a diverse group of Ca(2+)-dependent cysteine proteinases (CDPs; calpains in vertebrate tissues). The latter pathway is highly conserved and consists of ubiquitin, ubiquitin-conjugating enzymes, deubiquitinases, and the proteasome. This review summarizes the biochemical properties and genetics of invertebrate CDPs and proteasomes and their roles in programmed cell death, stress responses (heat shock and anoxia), skeletal muscle atrophy, gametogenesis and fertilization, development and pattern formation, cell-cell recognition, signal transduction and learning, and photoreceptor light adaptation. These pathways carry out bulk protein degradation in the programmed death of the intersegmental and flight muscles of insects and of individuals in a colonial ascidian; molt-induced atrophy of crustacean claw muscle; and responses of brine shrimp, mussels, and insects to environmental stress. Selective proteolysis occurs in response to specific signals, such as in modulating protein kinase A activity in sea hare and fruit fly associated with learning; gametogenesis, differentiation, and development in sponge, echinoderms, nematode, ascidian, and insects; and in light adaptation of photoreceptors in the eyes of squid, insects, and crustaceans. Proteolytic activities and specificities are regulated through proteinase gene expression (CDP isozymes and proteasomal subunits), allosteric regulators, and posttranslational modifications, as well as through specific targeting of protein substrates by a diverse assemblage of ubiquitin-conjugases and deubiquitinases. Thus, the regulation of intracellular proteolysis approaches the complexity and versatility of transcriptional and translational mechanisms.
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Affiliation(s)
- D L Mykles
- Department of Biology, Colorado State University, Fort Collins 80523, USA
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48
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Abstract
The 26S proteasome complex plays a major role in the non-lysosomal degradation of intracellular proteins. Purified 26S proteasomes give a pattern of more than 40 spots on 2D-PAGE gels. The positions of subunits have been identified by mass spectrometry of tryptic peptides and by immunoblotting with subunit-specific antipeptide antibodies. Two-dimensional polyacrylamide gel electrophoresis of proteasomes immunoprecipitated from [32P]phosphate-labelled human embryo lung L-132 cells revealed the presence of at least three major phosphorylated polypeptides among the regulatory subunits as well as the C8 and C9 components of the core 20S proteasome. Comparison with the positions of the regulatory polypeptides revealed a minor phosphorylated form to be S7 (MSS1). Antibodies against S4, S6 (TBP7) and S12 (MOV34) all cross-reacted at the position of major phosphorylated polypeptides suggesting that several of the ATPase subunits may be phosphorylated. The phosphorylation of S4 was confirmed by double immunoprecipitation experiments in which 26S proteasomes were immunoprecipitated as above and dissociated and then S4 was immunoprecipitated with subunit-specific antibodies. Antibodies against the non-ATPase subunit S10, which has been suggested by others to be phosphorylated, did not coincide with the position of a phosphorylated polypeptide. Some differences were observed in the 2D-PAGE pattern of proteasomes immunoprecipitated from cultured cells compared to purified rat liver 26S proteasomes suggesting possible differences in subunit compositions of 26S proteasomes.
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Affiliation(s)
- G G Mason
- Department of Biochemistry, School of Medical Sciences, University of Bristol, UK
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49
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Fraser RA, Heard DJ, Adam S, Lavigne AC, Le Douarin B, Tora L, Losson R, Rochette-Egly C, Chambon P. The putative cofactor TIF1alpha is a protein kinase that is hyperphosphorylated upon interaction with liganded nuclear receptors. J Biol Chem 1998; 273:16199-204. [PMID: 9632676 DOI: 10.1074/jbc.273.26.16199] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ligand-induced gene activation by nuclear receptors (NRs) is a complex process requiring dissociation of corepressors and recruitment of coactivators. The putative transcriptional intermediary factor TIF1alpha has been previously characterized as a nuclear protein that interacts directly with the AF-2 ligand-dependent activating domain present in the ligand-binding domain of numerous steroid and nonsteroid receptors, including the estrogen (ERalpha) and retinoid X (RXRalpha) receptors. We report here that TIF1alpha is both a phosphoprotein and a protein kinase. TIF1alpha coexpressed in COS-1 cells with RXRalpha or ERalpha is phosphorylated and becomes hyperphosphorylated upon ligand treatment. This hyperphosphorylation requires the binding of TIF1alpha to transcriptionally active NRs since it is prevented by mutations either in the core (alpha-helix 12 of the ligand-binding domain) of the AF-2 activating domains of RXRalpha and ERalpha or in the NR box of TIF1alpha that are known to prevent TIF1alpha-NR interactions. Thus, TIF1alpha is a phosphoprotein that undergoes ligand-dependent hyperphosphorylation as a consequence of nuclear receptor binding. We further show that purified recombinant TIF1alpha possesses intrinsic kinase activity and that, in addition to autophosphorylation, TIF1alpha selectively phosphorylates the transcription factors TFIIEalpha, TAFII28, and TAFII55 in vitro. These latter results raise the possibility that TIF1alpha may act, at least in part, by phosphorylating and modifying the activity of components of the transcriptional machinery.
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Affiliation(s)
- R A Fraser
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/Université Louis Pasteur/Collège de France, B. P. 163, 67404 Illkirch Cedex, Strasbourg, France
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50
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Hendil KB, Khan S, Tanaka K. Simultaneous binding of PA28 and PA700 activators to 20 S proteasomes. Biochem J 1998; 332 ( Pt 3):749-54. [PMID: 9620878 PMCID: PMC1219536 DOI: 10.1042/bj3320749] [Citation(s) in RCA: 183] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Two activators, named PA700 and PA28, are known to bind to 20 S proteasomes, forming two different complexes. The PA700-proteasome complex, also known as the 26 S proteasome, can degrade intact proteins, whereas complexes with PA28 can degrade only peptides. Monoclonal antibodies to 20 S proteasomes or the p45 ATPase subunit (Trip1, Sug1) of PA700 precipitated the same set of proteins from HeLa extracts, including six different ATPase subunits of PA700. This shows that p45 is not present in other protein complexes and suggests that all 26 S proteasome particles contain the same set of ATPase subunits. Interferons alpha and gamma had no effect on the composition of the 26 S proteasome, except for the replacement of subunits delta, MB1 and Z with Lmp2, Lmp7 and MECL1 respectively. Surprisingly, antibodies to PA28 precipitated p42, a component of PA700. Conversely, anti-p45 antibodies precipitated not only 26 S proteasomes but also PA28 alpha, beta and gamma, indicating that 20 S proteasomes can simultaneously bind both PA700 and PA28. PA28 alpha beta is known to be involved in antigen presentation. Conceivably, intact substrate proteins are recognized by PA700 and fed into proteasomes whose cleavage specificity is optimized for antigen presentation on MHC class I by PA28 and three interferon inducible proteasome subunits.
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Affiliation(s)
- K B Hendil
- August Krogh Institute, University of Copenhagen, Universitetsparken 13, DK-2100 Copenhagen O, Denmark.
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