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Ohta K, Saka N, Fukasawa M, Nishio M. Hazara orthonairovirus nucleoprotein facilitates viral cell-to-cell spread by modulating tight junction protein, claudin-1. Front Microbiol 2023; 14:1192956. [PMID: 37287449 PMCID: PMC10243194 DOI: 10.3389/fmicb.2023.1192956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 05/02/2023] [Indexed: 06/09/2023] Open
Abstract
Background Tight junctions act as a barrier that prevents invasion of pathogens through epithelial cells. This study aims to elucidate the correlation between tight junctions and nairoviruses using Hazara orthonairovirus (HAZV) as a surrogate model for Crimean-Congo hemorrhagic fever virus. Methods mRNA, total protein, and cell surface protein levels of tight junction proteins were examined by quantitative real-time reverse transcription polymerase chain reaction, immunoblot and flow cytometry, respectively. HAZV growth was measured by plaque assay. Immunofluorescence assay was used to examine viral cell-to-cell spread. The interaction between HAZV nucleoprotein and claudin-1 was analyzed by immunoprecipitation. Results HAZV infection induced mRNA of several tight junction proteins, especially claudin-1. HAZV infection also induced cell surface expression of claudin-1 protein. Claudin-1 overexpression inhibited the growth of HAZV by blocking its cell-to-cell spread. In contrast, HAZV nucleoprotein completely inhibited HAZV-induced cell surface expression of claudin-1, and this inhibition required interaction between HAZV nucleoprotein and claudin-1. Conclusion HAZV nucleoprotein was shown to bind to claudin-1 to negatively regulate its cell surface expression, and so can promote cell-to-cell spread of HAZV. This is the first presentation of a possible mechanism behind how nairoviruses counteract tight junction barrier function.
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Affiliation(s)
- Keisuke Ohta
- Department of Microbiology, School of Medicine, Wakayama Medical University, Wakayama, Japan
| | - Naoki Saka
- Department of Microbiology, School of Medicine, Wakayama Medical University, Wakayama, Japan
| | - Masayoshi Fukasawa
- Department of Biochemistry and Cell Biology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Machiko Nishio
- Department of Microbiology, School of Medicine, Wakayama Medical University, Wakayama, Japan
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2
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León Machado JA, Steimle V. The MHC Class II Transactivator CIITA: Not (Quite) the Odd-One-Out Anymore among NLR Proteins. Int J Mol Sci 2021; 22:1074. [PMID: 33499042 PMCID: PMC7866136 DOI: 10.3390/ijms22031074] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 01/15/2021] [Accepted: 01/19/2021] [Indexed: 12/14/2022] Open
Abstract
In this review, we discuss the major histocompatibility complex (MHC) class II transactivator (CIITA), which is the master regulator of MHC class II gene expression. CIITA is the founding member of the mammalian nucleotide-binding and leucine-rich-repeat (NLR) protein family but stood apart for a long time as the only transcriptional regulator. More recently, it was found that its closest homolog, NLRC5 (NLR protein caspase activation and recruitment domain (CARD)-containing 5), is a regulator of MHC-I gene expression. Both act as non-DNA-binding activators through multiple protein-protein interactions with an MHC enhanceosome complex that binds cooperatively to a highly conserved combinatorial cis-acting module. Thus, the regulation of MHC-II expression is regulated largely through the differential expression of CIITA. In addition to the well-defined role of CIITA in MHC-II GENE regulation, we will discuss several other aspects of CIITA functions, such as its role in cancer, its role as a viral restriction element contributing to intrinsic immunity, and lastly, its very recently discovered role as an inhibitor of Ebola and SARS-Cov-2 virus replication. We will briefly touch upon the recently discovered role of NLRP3 as a transcriptional regulator, which suggests that transcriptional regulation is, after all, not such an unusual feature for NLR proteins.
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Affiliation(s)
| | - Viktor Steimle
- Département de Biologie, Université de Sherbrooke, 2500 Boul., Sherbrooke, QC J1K 2R1, Canada;
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Bruchez A, Sha K, Johnson J, Chen L, Stefani C, McConnell H, Gaucherand L, Prins R, Matreyek KA, Hume AJ, Mühlberger E, Schmidt EV, Olinger GG, Stuart LM, Lacy-Hulbert A. MHC class II transactivator CIITA induces cell resistance to Ebola virus and SARS-like coronaviruses. Science 2020; 370:241-247. [PMID: 32855215 PMCID: PMC7665841 DOI: 10.1126/science.abb3753] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 08/20/2020] [Indexed: 01/01/2023]
Abstract
Recent outbreaks of Ebola virus (EBOV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have exposed our limited therapeutic options for such diseases and our poor understanding of the cellular mechanisms that block viral infections. Using a transposon-mediated gene-activation screen in human cells, we identify that the major histocompatibility complex (MHC) class II transactivator (CIITA) has antiviral activity against EBOV. CIITA induces resistance by activating expression of the p41 isoform of invariant chain CD74, which inhibits viral entry by blocking cathepsin-mediated processing of the Ebola glycoprotein. We further show that CD74 p41 can block the endosomal entry pathway of coronaviruses, including SARS-CoV-2. These data therefore implicate CIITA and CD74 in host defense against a range of viruses, and they identify an additional function of these proteins beyond their canonical roles in antigen presentation.
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MESH Headings
- Antigens, Differentiation, B-Lymphocyte/genetics
- Antigens, Differentiation, B-Lymphocyte/physiology
- Betacoronavirus/physiology
- COVID-19
- Cell Line, Tumor
- Coronavirus Infections/immunology
- Coronavirus Infections/virology
- DNA Transposable Elements
- Ebolavirus/physiology
- Endosomes/virology
- Genetic Testing
- Hemorrhagic Fever, Ebola/immunology
- Hemorrhagic Fever, Ebola/virology
- Histocompatibility Antigens Class II/genetics
- Histocompatibility Antigens Class II/physiology
- Host-Pathogen Interactions/genetics
- Host-Pathogen Interactions/immunology
- Humans
- Nuclear Proteins/genetics
- Nuclear Proteins/physiology
- Pandemics
- Pneumonia, Viral/immunology
- Pneumonia, Viral/virology
- SARS-CoV-2
- Trans-Activators/genetics
- Trans-Activators/physiology
- Transcription, Genetic
- Virus Internalization
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Affiliation(s)
- Anna Bruchez
- Benaroya Research Institute, Seattle, WA 98101, USA
| | - Ky Sha
- Benaroya Research Institute, Seattle, WA 98101, USA
| | - Joshua Johnson
- National Institute of Allergy and Infectious Diseases (NIAID) Integrated Research Facility, Frederick, MD 21702, USA
| | - Li Chen
- Massachusetts General Hospital, Boston, MA 02114, USA
| | | | | | | | - Rachel Prins
- Benaroya Research Institute, Seattle, WA 98101, USA
| | - Kenneth A Matreyek
- Department of Genome Sciences, University of Washington, Seattle, WA 98109, USA
| | - Adam J Hume
- Boston University School of Medicine, Boston, MA 02118, USA
- National Emerging Infectious Diseases Laboratories, Boston University, Boston, MA 02118, USA
| | - Elke Mühlberger
- Boston University School of Medicine, Boston, MA 02118, USA
- National Emerging Infectious Diseases Laboratories, Boston University, Boston, MA 02118, USA
| | | | - Gene G Olinger
- National Institute of Allergy and Infectious Diseases (NIAID) Integrated Research Facility, Frederick, MD 21702, USA
- Boston University School of Medicine, Boston, MA 02118, USA
- National Emerging Infectious Diseases Laboratories, Boston University, Boston, MA 02118, USA
- MRIGlobal, Gaithersburg, MD 20878, USA
| | - Lynda M Stuart
- Benaroya Research Institute, Seattle, WA 98101, USA
- Bill and Melinda Gates Foundation, Seattle, WA 98109, USA
| | - Adam Lacy-Hulbert
- Benaroya Research Institute, Seattle, WA 98101, USA.
- Department of Immunology, University of Washington, Seattle, WA 98109, USA
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4
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Development of potent class II transactivator gene delivery systems capable of inducing de novo MHC II expression in human cells, in vitro and ex vivo. Gene Ther 2017; 24:342-352. [PMID: 28414303 DOI: 10.1038/gt.2017.25] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 02/01/2017] [Accepted: 02/06/2017] [Indexed: 01/17/2023]
Abstract
Class II transactivator (CIITA) induces transcription of major histocompatibility complex (MHC) II genes and can potentially be used to improve genetic immunotherapies by converting non-immune cells into cells capable of presenting antigens to CD4+ T cells. However, CIITA expression is tightly controlled and it remains unclear whether distinct non-immune cells differ in this transactivator regulation. Here we describe the development of gene delivery systems capable of promoting the efficient CIITA expression in non-immune cell lines and in primary human cells of an ex vivo skin explant model. Different human cell types undergoing CIITA overexpression presented high-level de novo expression of MHC II, validating the delivery systems as suitable tools for the CIITA evaluation as a molecular adjuvant for gene therapies.
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5
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Evidence that Receptor Destruction by the Sendai Virus Hemagglutinin-Neuraminidase Protein Is Responsible for Homologous Interference. J Virol 2016; 90:7640-6. [PMID: 27279623 DOI: 10.1128/jvi.01087-16] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 06/04/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Receptor destruction has been considered one of the mechanisms of homologous Sendai virus (SeV) interference. However, direct evidence of receptor destruction upon virus infection and its relevance to interference is missing. To investigate a precise mechanism of homologous interference, we established SeV persistently infected cells. The persistently infected cells inhibited superinfection by homologous SeV but supported replication of human parainfluenza virus 2 (hPIV2) and influenza A virus (IAV). We confirmed that SeV particles could not attach to or penetrate the infected cells and that the hemagglutinin-neuraminidase (HN) protein of SeV was involved in the interference. Lectin blot assays showed that the α2,3-linked sialic acids were specifically reduced in the SeV-infected cells, but the level of α2,6-linked sialic acids had not changed. As infection with IAV removed both α2,3- and α2,6-linked sialic acids, especially α2,3-linked sialic acids, IAV-infected cells inhibited superinfection of SeV. These results provide concrete evidence that destruction of the specific SeV receptor, α2,3-linked sialic acids, is relevant to homologous interference by SeV. IMPORTANCE Viral interference is a classically observed phenomenon, but the precise mechanism is not clear. Using SeV interference, we provide concrete evidence that reduction of the α2,3-linked sialic acid receptor by the HN of SeV is closely related with viral interference. Since SeV infection resulted in decrease of only α2,3-linked sialic acids, IAV, which also utilized α2,6-linked sialic acids to initiate infection, superinfected the SeV-infected cells. In contrast, SeV could not superinfect the IAV-infected cells because both α2,3- and α2,6-linked sialic acids were removed. These results indicate that receptor destruction critically contributes to viral interference.
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6
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Beaulieu YB, Leon Machado JA, Ethier S, Gaudreau L, Steimle V. Degradation, Promoter Recruitment and Transactivation Mediated by the Extreme N-Terminus of MHC Class II Transactivator CIITA Isoform III. PLoS One 2016; 11:e0148753. [PMID: 26871568 PMCID: PMC4752451 DOI: 10.1371/journal.pone.0148753] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 01/22/2016] [Indexed: 12/17/2022] Open
Abstract
Multiple relationships between ubiquitin-proteasome mediated protein turnover and transcriptional activation have been well documented, but the underlying mechanisms are still poorly understood. One way to induce degradation is via ubiquitination of the N-terminal α-amino group of proteins. The major histocompatibility complex (MHC) class II transactivator CIITA is the master regulator of MHC class II gene expression and we found earlier that CIITA is a short-lived protein. Using stable and transient transfections of different CIITA constructs into HEK-293 and HeLa cell lines, we show here that the extreme N-terminal end of CIITA isoform III induces both rapid degradation and transactivation. It is essential that this sequence resides at the N-terminal end of the protein since blocking of the N-terminal end with an epitope-tag stabilizes the protein and reduces transactivation potential. The first ten amino acids of CIITA isoform III act as a portable degron and transactivation sequence when transferred as N-terminal extension to truncated CIITA constructs and are also able to destabilize a heterologous protein. The same is observed with the N-terminal ends of several known N-terminal ubiquitination substrates, such as Id2, Cdt1 and MyoD. Arginine and proline residues within the N-terminal ends contribute to rapid turnover. The N-terminal end of CIITA isoform III is responsible for efficient in vivo recruitment to the HLA-DRA promoter and increased interaction with components of the transcription machinery, such as TBP, p300, p400/Domino, the 19S ATPase S8, and the MHC-II promoter binding complex RFX. These experiments reveal a novel function of free N-terminal ends of proteins in degradation-dependent transcriptional activation.
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Affiliation(s)
- Yves B. Beaulieu
- Département de biologie, Université de Sherbrooke, Sherbrooke, Qc, Canada
| | | | - Sylvain Ethier
- Département de biologie, Université de Sherbrooke, Sherbrooke, Qc, Canada
| | - Luc Gaudreau
- Département de biologie, Université de Sherbrooke, Sherbrooke, Qc, Canada
| | - Viktor Steimle
- Département de biologie, Université de Sherbrooke, Sherbrooke, Qc, Canada
- * E-mail:
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7
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Goto H, Ihira H, Morishita K, Tsuchiya M, Ohta K, Yumine N, Tsurudome M, Nishio M. Enhanced growth of influenza A virus by coinfection with human parainfluenza virus type 2. Med Microbiol Immunol 2015; 205:209-18. [PMID: 26582554 PMCID: PMC7086786 DOI: 10.1007/s00430-015-0441-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 11/08/2015] [Indexed: 12/18/2022]
Abstract
It has been reported that dual or multiple viruses can coinfect epithelial cells of the respiratory tract. However, little has been reported on in vitro interactions of coinfected viruses. To explore how coinfection of different viruses affects their biological property, we examined growth of influenza A virus (IAV) and human parainfluenza virus type 2 (hPIV2) during coinfection of Vero cells. We found that IAV growth was enhanced by coinfection with hPIV2. The enhanced growth of IAV was not reproduced by coinfection with an hPIV2 mutant with reduced cell fusion activity, or by ectopic expression of the V protein of hPIV2. In contrast, induction of cell fusion by ectopic expression of the hPIV2 HN and F proteins augments IAV growth. hPIV2 coinfection supported IAV growth in cells originated from the respiratory epithelium. The enhancement correlated closely with cell fusion ability of hPIV2 in those cells. These results indicate that cell fusion induced by hPIV2 infection is beneficial to IAV replication and that enhanced viral replication by coinfection with different viruses can modify their pathological consequences.
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Affiliation(s)
- Hideo Goto
- Department of Microbiology, School of Medicine, Wakayama Medical University, Wakayama, Japan
| | - Hironobu Ihira
- Department of Microbiology, School of Medicine, Wakayama Medical University, Wakayama, Japan
| | - Keiichi Morishita
- Department of Microbiology, School of Medicine, Wakayama Medical University, Wakayama, Japan
| | - Mitsuki Tsuchiya
- Department of Microbiology, School of Medicine, Wakayama Medical University, Wakayama, Japan
| | - Keisuke Ohta
- Department of Microbiology, School of Medicine, Wakayama Medical University, Wakayama, Japan
| | - Natsuko Yumine
- Department of Microbiology, School of Medicine, Wakayama Medical University, Wakayama, Japan
| | - Masato Tsurudome
- Department of Microbiology and Molecular Genetics, Mie University Graduate School of Medicine, Mie, Japan
| | - Machiko Nishio
- Department of Microbiology, School of Medicine, Wakayama Medical University, Wakayama, Japan.
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8
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Mottok A, Woolcock B, Chan FC, Tong KM, Chong L, Farinha P, Telenius A, Chavez E, Ramchandani S, Drake M, Boyle M, Ben-Neriah S, Scott DW, Rimsza LM, Siebert R, Gascoyne RD, Steidl C. Genomic Alterations in CIITA Are Frequent in Primary Mediastinal Large B Cell Lymphoma and Are Associated with Diminished MHC Class II Expression. Cell Rep 2015; 13:1418-1431. [PMID: 26549456 DOI: 10.1016/j.celrep.2015.10.008] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 08/17/2015] [Accepted: 10/04/2015] [Indexed: 02/06/2023] Open
Abstract
Primary mediastinal large B cell lymphoma (PMBCL) is an aggressive non-Hodgkin's lymphoma, predominantly affecting young patients. We analyzed 45 primary PMBCL tumor biopsies and 3 PMBCL-derived cell lines for the presence of genetic alterations involving the major histocompatibility complex (MHC) class II transactivator CIITA and found frequent aberrations consisting of structural genomic rearrangements, missense, nonsense, and frame-shift mutations (53% of primary tumor biopsies and all cell lines). We also detected intron 1 mutations in 47% of the cases, and detailed sequence analysis strongly suggests AID-mediated aberrant somatic hypermutation as the mutational mechanism. Furthermore, we demonstrate that genomic lesions in CIITA result in decreased protein expression and reduction of MHC class II surface expression, creating an immune privilege phenotype in PMBCL. In summary, we establish CIITA alterations as a common mechanism of immune escape through reduction of MHC class II expression in PMBCL, with potential implications for future treatments targeting microenvironment-related biology.
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Affiliation(s)
- Anja Mottok
- Centre for Lymphoid Cancer, Department of Lymphoid Cancer Research, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada; Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC V6T 2B5, Canada
| | - Bruce Woolcock
- Centre for Lymphoid Cancer, Department of Lymphoid Cancer Research, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
| | - Fong Chun Chan
- Centre for Lymphoid Cancer, Department of Lymphoid Cancer Research, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada; Bioinformatics Training Program, University of British Columbia, Vancouver, BC V5Z 4S6, Canada
| | - King Mong Tong
- Centre for Lymphoid Cancer, Department of Lymphoid Cancer Research, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
| | - Lauren Chong
- Centre for Lymphoid Cancer, Department of Lymphoid Cancer Research, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada; Bioinformatics Training Program, University of British Columbia, Vancouver, BC V5Z 4S6, Canada
| | - Pedro Farinha
- Centre for Lymphoid Cancer, Department of Lymphoid Cancer Research, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
| | - Adèle Telenius
- Centre for Lymphoid Cancer, Department of Lymphoid Cancer Research, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
| | - Elizabeth Chavez
- Centre for Lymphoid Cancer, Department of Lymphoid Cancer Research, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
| | - Suvan Ramchandani
- Centre for Lymphoid Cancer, Department of Lymphoid Cancer Research, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
| | - Marie Drake
- Centre for Lymphoid Cancer, Department of Lymphoid Cancer Research, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
| | - Merrill Boyle
- Centre for Lymphoid Cancer, Department of Lymphoid Cancer Research, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
| | - Susana Ben-Neriah
- Centre for Lymphoid Cancer, Department of Lymphoid Cancer Research, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
| | - David W Scott
- Centre for Lymphoid Cancer, Department of Lymphoid Cancer Research, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada
| | - Lisa M Rimsza
- Department of Pathology, University of Arizona, Tucson, AZ 85724, USA
| | - Reiner Siebert
- Institute of Human Genetics, Christian-Albrechts-University Kiel and University Hospital Schleswig-Holstein, Campus Kiel, Kiel 24105, Germany
| | - Randy D Gascoyne
- Centre for Lymphoid Cancer, Department of Lymphoid Cancer Research, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada; Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC V6T 2B5, Canada
| | - Christian Steidl
- Centre for Lymphoid Cancer, Department of Lymphoid Cancer Research, BC Cancer Agency, Vancouver, BC V5Z 1L3, Canada; Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC V6T 2B5, Canada.
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9
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Antipsychotic treatment modulates glutamate transport and NMDA receptor expression. Eur Arch Psychiatry Clin Neurosci 2014; 264 Suppl 1:S67-82. [PMID: 25214389 DOI: 10.1007/s00406-014-0534-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 09/02/2014] [Indexed: 12/21/2022]
Abstract
Schizophrenia patients often suffer from treatment-resistant cognitive and negative symptoms, both of which are influenced by glutamate neurotransmission. Innovative therapeutic strategies such as agonists at metabotropic glutamate receptors or glycin reuptake inhibitors try to modulate the brain's glutamate network. Interactions of amino acids with monoamines have been described on several levels, and first- and second-generation antipsychotic agents (FGAs, SGAs) are known to exert modulatory effects on the glutamatergic system. This review summarizes the current knowledge on effects of FGAs and SGAs on glutamate transport and receptor expression derived from pharmacological studies. Such studies serve as a control for molecular findings in schizophrenia brain tissue and are clinically relevant. Moreover, they may validate animal models for psychosis, foster basic research on antipsychotic substances and finally lead to a better understanding of how monoaminergic and amino acid neurotransmissions are intertwined. In the light of these results, important differences dependent on antipsychotic substances, dosage and duration of treatment became obvious. While some post-mortem findings might be confounded with multifold drug effects, others are unlikely to be influenced by antipsychotic treatment and could represent important markers of schizophrenia pathophysiology. In similarity to the convergence of toxic and psychotomimetic effects of dopaminergic, serotonergic and anti-glutamatergic substances, the therapeutic mechanisms of SGAs might merge on a yet to be defined molecular level. In particular, serotonergic effects of SGAs, such as an agonism at 5HT1A receptors, represent important targets for further clinical research.
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10
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Neerincx A, Jakobshagen K, Utermöhlen O, Büning H, Steimle V, Kufer TA. The N-Terminal Domain of NLRC5 Confers Transcriptional Activity for MHC Class I and II Gene Expression. THE JOURNAL OF IMMUNOLOGY 2014; 193:3090-100. [DOI: 10.4049/jimmunol.1401065] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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11
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Ulbricht T, Alzrigat M, Horch A, Reuter N, von Mikecz A, Steimle V, Schmitt E, Krämer OH, Stamminger T, Hemmerich P. PML promotes MHC class II gene expression by stabilizing the class II transactivator. ACTA ACUST UNITED AC 2012; 199:49-63. [PMID: 23007646 PMCID: PMC3461510 DOI: 10.1083/jcb.201112015] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Promyelocytic leukemia (PML) nuclear bodies selectively associate with transcriptionally active genomic regions, including the gene-rich major histocompatibility (MHC) locus. In this paper, we have explored potential links between PML and interferon (IFN)-γ-induced MHC class II expression. IFN-γ induced a substantial increase in the spatial proximity between PML bodies and the MHC class II gene cluster in different human cell types. Knockdown experiments show that PML is required for efficient IFN-γ-induced MHC II gene transcription through regulation of the class II transactivator (CIITA). PML mediates this function through protection of CIITA from proteasomal degradation. We also show that PML isoform II specifically forms a stable complex with CIITA at PML bodies. These observations establish PML as a coregulator of IFN-γ-induced MHC class II expression.
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Affiliation(s)
- Tobias Ulbricht
- Leibniz Institute for Age Research, Fritz-Lipmann Institute, 07745 Jena, Germany
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12
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Neerincx A, Rodriguez GM, Steimle V, Kufer TA. NLRC5 controls basal MHC class I gene expression in an MHC enhanceosome-dependent manner. THE JOURNAL OF IMMUNOLOGY 2012; 188:4940-50. [PMID: 22490867 DOI: 10.4049/jimmunol.1103136] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Nucleotide-binding domain and leucine-rich repeat (NLR) proteins play important roles in innate immune responses as pattern-recognition receptors. Although most NLR proteins act in cell autonomous immune pathways, some do not function as classical pattern-recognition receptors. One such NLR protein is the MHC class II transactivator, the master regulator of MHC class II gene transcription. In this article, we report that human NLRC5, which we recently showed to be involved in viral-mediated type I IFN responses, shuttles to the nucleus and activates MHC class I gene expression. Knockdown of NLRC5 in different human cell lines and primary dermal fibroblasts leads to reduced MHC class I expression, whereas introduction of NLRC5 into cell types with very low expression of MHC class I augments MHC class I expression to levels comparable to those found in lymphocytes. Expression of NLRC5 positively correlates with MHC class I expression in human tissues. Functionally, we show that both the N-terminal effector domain of NLRC5 and its C-terminal leucine-rich repeat domain are needed for activation of MHC class I expression. Moreover, nuclear shuttling and function depend on a functional Walker A motif. Finally, we identified a promoter sequence in the MHC class I promoter, the X1 box, to be involved in NLRC5-mediated MHC class I gene activation. Taken together, this suggested that NLRC5 acts in a manner similar to class II transactivator to drive MHC expression and revealed NLRC5 as an important regulator of basal MHC class I expression.
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Affiliation(s)
- Andreas Neerincx
- Institute for Medical Microbiology, Immunology, and Hygiene, University of Cologne, 50931 Cologne, Germany
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13
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Gambari R. Recent patents on therapeutic applications of the transcription factor decoy approach. Expert Opin Ther Pat 2012; 21:1755-71. [PMID: 22017413 DOI: 10.1517/13543776.2011.629605] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
INTRODUCTION Transcription is considered as an important target of drugs employed in biomedicine. Therefore, novel strategies to inhibit the biological effects of transcription factors (TFs) are of interest, such as targeting promoters with triple-helix-forming oligonucleotides and antisense targeting of mRNAs coding for TFs. AREAS COVERED The objective of this review is to describe studies considering inhibition of TF functions with molecules mimicking TF binding sites (transcription factor decoy approach, TFD) and to summarize the patents on possible clinical applications of this approach. EXPERT OPINION Treatment of cells with TFD molecules leads to inhibition (or activation) of genes regulated by the target transcription factors. The studies and patents on this specific issue have taken in great consideration the delivery strategy, which is a very important parameter. The TFD strategy has been proven effective in vivo. The stability of the TFD molecules in vivo should be carefully considered, as well as the possible toxicity and/or possible effects on innate and adaptive immune response. In order to improve clinical parameters, many patents suggest the use of the TFD molecules in combination with drugs already employed in therapy. We are expecting in the near future relevant clinical trials based on the TFD strategy.
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Affiliation(s)
- Roberto Gambari
- University of Ferrara, Interdisciplinary Center for the Study of Inflammation, ER-GenTech and BioPharmaNet, Department of Biochemistry and Molecular Biology, Ferrara, Italy.
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Nizet Y, Gillet L, Schroeder H, Lecuivre C, Louahed J, Renauld JC, Gianello P, Vanderplasschen A. Antibody production by injection of living cells expressing non self antigens as cell surface type II transmembrane fusion protein. J Immunol Methods 2011; 367:70-7. [PMID: 21354163 DOI: 10.1016/j.jim.2011.02.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 02/08/2011] [Accepted: 02/17/2011] [Indexed: 10/18/2022]
Abstract
Antigen expression and purification are laborious, time consuming and frequently difficult steps in the process of antibody production. In the present study, we developed a method avoiding these two steps. This method relies on the injection of histocompatible living cells stably expressing the antigen as a cell surface type II transmembrane fusion protein. A vector, nicknamed pCD1-CD134L, was constructed to express the antigen fused at the carboxyterminal end of the human CD134 ligand (CD134L) type II transmembrane protein on the surface of eucaryotic cells. This vector was shown to induce cell surface expression of epitopes from human c-Myc (soluble protein), uterogloblin-related protein 1 (secreted protein) and CD94 (type II transmembrane protein). Using this vector, we developed a method to produce antibodies without antigen production. The flowchart of this method is as follows: (i) cloning of the antigen in the pCD1-CD134L vector; (ii) production of a histocompatible cell line stably expressing the CD134L-antigen fusion protein; (iii) testing for cell surface expression of the fusion protein by targeting the CD134L carrier; and (iv) prime-boost immunisation with living cells expressing the fusion protein. This method was successfully used for production of polyclonal antibodies raised against Ixodes ricinus calreticulin (secreted protein) in mice and for production of monoclonal antibodies raised against an epitope of Vaccinia virus A56 (type I transmembrane protein) protein in rat. The present study is the first to demonstrate the use of a type II transmembrane protein as a carrier for cell surface display of antigens.
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Affiliation(s)
- Yannick Nizet
- Experimental Immunology Unit, Université Catholique de Louvain, Brussels, Belgium.
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15
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Lemaire MM, Vanhaudenarde A, Nizet Y, Dumoutier L, Renauld JC. Induction of autoantibodies against mouse soluble proteins after immunization with living cells presenting the autoantigen at the cell surface in fusion with a human type 2 transmembrane protein. J Immunol Methods 2011; 367:56-62. [PMID: 21334341 DOI: 10.1016/j.jim.2011.02.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Accepted: 02/03/2011] [Indexed: 11/17/2022]
Abstract
Induction of autoantibodies towards immune regulatory proteins, such as cytokines or their receptors, is a powerful strategy for functional studies on the role of these factors in vivo. Here we describe a new procedure to elicit autoantibodies by taking advantage of tumor cells as a vaccine against peptides presented at their surface in fusion with the human CD134L transmembrane protein. P1.HTR, an immunogenic variant of the P815 mastocytoma cell line, was used to generate stably transfected cell clones with expression vectors encoding the human CD134L transmembrane protein fused with either mouse IL-22BP or IL-9. Following repeated injections of living tumor cells expressing the mIL-22BP construct, mice developed autoantibodies that bind to mIL-22BP and inhibit its interaction with IL-22 in vitro. Mice similarly immunized against mIL-9 produced high titers of autoantibodies that block the activity of this cytokine in the TS1 bioassay. This procedure also inhibits IL-9 activity in vivo as no increase of serum MMCP-1 mast cell protease concentration was observed following IL-9 administration to immunized mice. As an alternative to the injection of living tumor cells expressing the CD134L-antigen fusion protein, intramuscular electrotransfer of the corresponding DNA construct also induced autoantibodies. These results validate this method as a simple and convenient approach to knock down the in vivo activity of soluble regulatory proteins, including cytokines and their receptors.
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Affiliation(s)
- Muriel M Lemaire
- Ludwig Institute for Cancer Research, Brussels branch, Avenue Hippocrate, 74, B-1200 Brussels, Belgium
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16
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Xu Y, Harton JA, Smith BD. CIITA mediates interferon-gamma repression of collagen transcription through phosphorylation-dependent interactions with co-repressor molecules. J Biol Chem 2007; 283:1243-1256. [PMID: 17991736 DOI: 10.1074/jbc.m707180200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previously, we have demonstrated that major histocompatibility class II trans-activator (CIITA) is crucial in mediating interferon-gamma (IFN-gamma)-induced repression of collagen type I gene transcription. Here we report that CIITA represses collagen transcription through a phosphorylation-dependent interaction between its proline/serine/threonine domain and co-repressor molecules such as histone deacetylase (HDAC2) and Sin3B. Mutation of a serine (S373A) in CIITA, within a glycogen synthase kinase 3 (GSK3) consensus site, decreases repression of collagen transcription by blocking interaction with Sin3B. In vitro phosphorylation of CIITA by GSK3 relies on a casein kinase I site three amino acids C-terminal to the GSK3 site in CIITA. Both GSK3 and casein kinase I inhibitors alleviate collagen repression and disrupt IFN-gamma-mediated recruitment of Sin3B and HDAC2 to the collagen start site. Therefore, we have identified the region within CIITA responsible for mediating IFN-gamma-induced inhibition of collagen synthesis.
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Affiliation(s)
- Yong Xu
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Jonathan A Harton
- Center for Immunology and Microbial Disease, Albany Medical College, Albany, New York 12208
| | - Barbara D Smith
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118.
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17
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Strähle L, Marq JB, Brini A, Hausmann S, Kolakofsky D, Garcin D. Activation of the beta interferon promoter by unnatural Sendai virus infection requires RIG-I and is inhibited by viral C proteins. J Virol 2007; 81:12227-37. [PMID: 17804509 PMCID: PMC2169027 DOI: 10.1128/jvi.01300-07] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
As infection with wild-type (wt) Sendai virus (SeV) normally activates beta interferon (IFN-beta) very poorly, two unnatural SeV infections were used to study virus-induced IFN-beta activation in mouse embryonic fibroblasts: (i) SeV-DI-H4, which is composed mostly of small, copyback defective interfering (DI) genomes and whose infection overproduces short 5'-triphosphorylated trailer RNAs (pppRNAs) and underproduces viral V and C proteins, and (ii) SeV-GFP(+/-), a coinfection that produces wt amounts of viral gene products but that also produces both green fluorescent protein (GFP) mRNA and its complement, which can form double-stranded RNA (dsRNA) with capped 5' ends. We found that (i) virus-induced signaling to IFN-beta depended predominantly on RIG-I (as opposed to mda-5) for both SeV infections, i.e., that RIG-I senses both pppRNAs and dsRNA without 5'-triphosphorylated ends, and (ii) it is the viral C protein (as opposed to V) that is primarily responsible for countering RIG-I-dependent signaling to IFN-beta. Nondefective SeV that cannot specifically express C proteins not only cannot prevent the effects of transfected poly(I-C) or (ppp)RNAs on IFN-beta activation but also synergistically enhances these effects. SeV-V(minus) infection, in contrast, behaves mostly like wt SeV and counteracts the effects of transfected poly(I-C) or (ppp)RNAs.
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Affiliation(s)
- Laura Strähle
- Department of Microbiology and Molecular Medicine, University of Geneva School of Medicine, 11 Ave de Champel, CH1211, Geneva, Switzerland
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18
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Cordey S, Roux L. Further characterization of a paramyxovirus transcription initiation signal: search for required nucleotides upstream and importance of the N phase context. J Gen Virol 2007; 88:1555-1564. [PMID: 17412986 DOI: 10.1099/vir.0.82701-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Paramyxovirus genomes contain a linear array of five to ten genes sequentially transcribed by the viral RNA polymerase. mRNA synthesis initiates at a nucleotide signal (gs1) within the genomic promoter located at the genome 3' end. To gain information about the mechanism involved in transcription initiation, a search was carried out for upstream nucleotides required for gs1 and the effects of the gs1 nucleocapsid protein (N) phase context on transcription regulation were determined. For both purposes, tandem promoter mini-genomes carrying a transcription signal ectopically positioned downstream of a replication-only signal were used. The requirement for hygromycin resistance gene expression was used in an attempt to select essential nucleotides within randomized stretches of nucleotides. Nucleotide insertions or deletions were also made on either side of the transcription signal to change its original N phase context in the five remaining possibilities and GFP expression from these modified signals was assessed. Cell cultures resistant to hygromycin treatment were readily obtained following amplification of mini-genomes harbouring randomized sequences. However, selected nucleotides upstream of gs1 could not be identified under conditions where nucleotides within gs1 were selected. In contrast, it was observed that changing the gs1 N phase context progressively decreased transcription by five- to tenfold. These results are discussed in relation to two different mechanisms of transcription initiation.
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Affiliation(s)
- Samuel Cordey
- Department of Microbiology and Molecular Medicine, University of Geneva Medical School, CMU, 1 rue Michel-Servet, CH-1211 Geneva 4, Switzerland
| | - Laurent Roux
- Department of Microbiology and Molecular Medicine, University of Geneva Medical School, CMU, 1 rue Michel-Servet, CH-1211 Geneva 4, Switzerland
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19
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Marq JB, Brini A, Kolakofsky D, Garcin D. Targeting of the Sendai virus C protein to the plasma membrane via a peptide-only membrane anchor. J Virol 2007; 81:3187-97. [PMID: 17229713 PMCID: PMC1866060 DOI: 10.1128/jvi.02465-06] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Several cellular proteins are synthesized in the cytosol on free ribosomes and then associate with membranes due to the presence of short peptide sequences. These membrane-targeting sequences contain sites to which lipid chains are attached, which help direct the protein to a particular membrane domain and anchor it firmly in the bilayer. The intracellular concentration of these proteins in particular cellular compartments, where their interacting partners are also concentrated, is essential to their function. This paper reports that the apparently unmodified N-terminal sequence of the Sendai virus C protein (MPSFLKKILKLRGRR . . .; letters in italics represent hydrophobic residues; underlined letters represent basic residues, which has a strong propensity to form an amphipathic alpha-helix in a hydrophobic environment) also function as a membrane targeting signal and membrane anchor. Moreover, the intracellular localization of the C protein at the plasma membrane is essential for inducing the interferon-independent phosphorylation of Stat1 as part of the viral program to prevent the cellular antiviral response.
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Affiliation(s)
- Jean-Baptiste Marq
- Department of Microbiology and Molecular Medicine, University of Geneva School of Medicine, 11 Ave de Champel, CH-1211 Geneva, Switzerland
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20
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Xu Y, McDonald J, Perloff E, Butticè G, Schreiber BM, Smith BD. Collagen and major histocompatibility class II expression in mesenchymal cells from CIITA hypomorphic mice. Mol Immunol 2006; 44:1709-21. [PMID: 16982097 DOI: 10.1016/j.molimm.2006.07.294] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2006] [Revised: 07/27/2006] [Accepted: 07/28/2006] [Indexed: 11/23/2022]
Abstract
Major histocompatibility class II (MHC II) transactivator (CIITA) is critical for interferon-gamma (IFN-gamma)-induced repression of collagen [Xu, Y., Wang, L., Buttice, G., Sengupta, P.K., Smith, B.D., 2004. Major histocompatibility class II transactivator (CIITA) mediates repression of collagen (COL1A2) transcription by interferon gamma (IFN-gamma). J. Biol. Chem. 279, 41319-41332] and activation of MHC II transcription. To better understand the role of CIITA and IFN-gamma induced repression of collagen, mesenchymal cells (lung fibroblasts, adventitial fibroblasts, and smooth muscle cells) were isolated from a CIITA deficient mouse (C2ta(tm1Ccum)). IFN-gamma induced MHC II expression and repressed collagen type I expression in all three cell types isolated from the wild type background. As expected, IFN-gamma treatment of cells isolated from CIITA deficient mice did not induce MHC II production or activate the MHC II promoter. Interestingly, collagen gene expression and promoter activity was similar to that of wild type. Moreover, IFN-gamma induced CIITA mRNA and a truncated form of CIITA protein in all cells isolated from CIITA deficient mice. Most importantly, truncated CIITA occupied the collagen alpha 2(I) gene (col1a2) transcription start site during IFN-gamma treatment, but it did not occupy the MHC II promoter as judged by chromatin immunoprecipitation assays. Exogenous expression of a similar truncated form of CIITA maintained its ability to repress col1a2 transcription, but lost its ability to activate MHC II gene transcription suggesting a role for the CIITA C-terminal domain in activation, but not repression. IFN-gamma induced primarily types I and IV CIITA isoforms in the mouse cells. All three isoforms of CIITA were capable of repressing col1a2 and activating MHC II gene transcription. These data suggest that the previously described CIITA knockout mouse carries a hypomorphic mutation, rather than a null mutation. The removal of the leucine rich region in CIITA blocks activation of MHC II without altering repression of collagen transcription.
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Affiliation(s)
- Yong Xu
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
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21
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Krawczyk M, Masternak K, Zufferey M, Barras E, Reith W. New functions of the major histocompatibility complex class II-specific transcription factor RFXANK revealed by a high-resolution mutagenesis study. Mol Cell Biol 2005; 25:8607-18. [PMID: 16166641 PMCID: PMC1265745 DOI: 10.1128/mcb.25.19.8607-8618.2005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The transcription factors RFX and CIITA are major players in regulation of the expression of all classical and nonclassical major histocompatibility complex class II (MHC-II) genes. RFX nucleates the formation of a multiprotein complex, called the MHC-II enhanceosome, on MHC-II promoters. Assembly of this enhanceosome is an obligatory step for recruitment of the coactivator CIITA and thus for activation of MHC-II gene transcription. We have analyzed the function of the ankyrin repeat-containing protein RFXANK, which forms the heterotrimeric RFX complex together with RFX5 and RFXAP. We discovered that ANKRA2, the closest paralogue of RFXANK, can substitute for RFXANK in the activation of MHC-II genes and that this ability is mediated by its ankyrin repeat domain (ARD). This finding provided the basis for a high-resolution structure-function analysis of the ARD of RFXANK, which allowed us to map the RFX5 interaction domain and residues critical for assembly of the RFX complex. We also found that mutations in the fourth ankyrin repeat of RFXANK abolish assembly of the enhanceosome on MHC-II promoters in vivo but not in vitro, suggesting a new role of RFXANK in facilitating promoter occupation in the context of chromatin.
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Affiliation(s)
- Michal Krawczyk
- Department of Pathology and Immunology, University of Geneva Medical School, CMU, 1 rue Michel-Servet, CH-1211 Geneva, Switzerland
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22
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Cognet I, Guilhot F, Gabriac M, Chevalier S, Chouikh Y, Herman-Bert A, Guay-Giroux A, Corneau S, Magistrelli G, Elson GC, Gascan H, Gauchat JF. Cardiotrophin-like cytokine labelling using Bir A biotin ligase: A sensitive tool to study receptor expression by immune and non-immune cells. J Immunol Methods 2005; 301:53-65. [PMID: 15936768 DOI: 10.1016/j.jim.2005.03.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2004] [Revised: 03/14/2005] [Accepted: 03/18/2005] [Indexed: 11/19/2022]
Abstract
The recently identified IL-6 family member cardiotrophin-like cytokine (also named novel neurotrophin-1 or B cell stimulating factor-3) forms a secreted complex with cytokine-like factor-1 which binds and activates the tripartite ciliary neurotrophic factor receptor. The striking differences between the phenotype of mice in which either the ciliary neurotrophic factor or its receptor are inactivated suggest that the cardiotrophin-like cytokine/cytokine-like factor-1 complex could be the developmentally important ciliary neurotrophic factor receptor ligand. Cardiotrophin-like cytokine is also produced in the immune system and has been reported to activate B cells in vivo and in vitro. B cells do not express the ciliary neurotrophic factor receptor suggesting the existence of an alternative receptor. We produced the cardiotrophin-like cytokine/cytokine-like factor-1 complex tagged with a Bir A biotin ligase AviTag peptide substrate. This cytokine could be efficiently biotinylated in vitro with Bir A. It was subsequently validated as a sensitive tool for ciliary neurotrophic factor receptor detection by flow cytometry and for magnetic-activated cell sorting. It was also shown to allow the detection of a specific receptor by activated B cells. Whereas binding to cells expressing the ciliary neurotrophic factor receptor could be prevented by competition with ciliary neurotrophic factor, binding to B cells was not. The biotinylated cardiotrophin-like cytokine/cytokine-like factor-1 complex therefore represents a new reagent to study ciliary neurotrophic factor and cardiotrophin-like cytokine receptor expression and for the identification of the putative cardiotrophin-like cytokine B cell receptor. It further validates the use of biotin ligase catalysed biotinylation for the detection of cytokine receptors.
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Affiliation(s)
- Isabelle Cognet
- Département de pharmacologie, Université de Montréal, C.P 6128, succursale Centre-ville, Montreal, QC, Canada H3C 3J7
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23
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24
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Krawczyk M, Peyraud N, Rybtsova N, Masternak K, Bucher P, Barras E, Reith W. Long distance control of MHC class II expression by multiple distal enhancers regulated by regulatory factor X complex and CIITA. THE JOURNAL OF IMMUNOLOGY 2004; 173:6200-10. [PMID: 15528357 DOI: 10.4049/jimmunol.173.10.6200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
MHC class II (MHC-II) genes are regulated by an enhanceosome complex containing two gene-specific transcription factors, regulatory factor X complex (RFX) and CIITA. These factors assemble on a strictly conserved regulatory module (S-X-X2-Y) found immediately upstream of the promoters of all classical and nonclassical MHC-II genes as well as the invariant chain (Ii) gene. To identify new targets of RFX and CIITA, we developed a computational approach based on the unique and highly constrained architecture of the composite S-Y motif. We identified six novel S'-Y' modules situated far away from the promoters of known human RFX- and CIITA-controlled genes. Four are situated at strategic positions within the MHC-II locus, and two are found within the Ii gene. These S'-Y' modules function as transcriptional enhancers, are bona fide targets of RFX and CIITA in B cells and IFN-gamma-induced cells, and induce broad domains of histone hyperacetylation. These results reveal a hitherto unexpected level of complexity involving long distance control of MHC-II expression by multiple distal regulatory elements.
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Affiliation(s)
- Michal Krawczyk
- University of Geneva Medical School, Centre Médical Universitaire, 1 rue Michel-Servet, CH-1211 Geneva, Switzerland
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25
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Garcin D, Marq JB, Iseni F, Martin S, Kolakofsky D. A short peptide at the amino terminus of the Sendai virus C protein acts as an independent element that induces STAT1 instability. J Virol 2004; 78:8799-811. [PMID: 15280488 PMCID: PMC479069 DOI: 10.1128/jvi.78.16.8799-8811.2004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The Sendai virus C protein acts to dismantle the interferon-induced cellular antiviral state in an MG132-sensitive manner, in part by inducing STAT1 instability. This activity of C maps to the first 23 amino acids (C(1-23)) of the 204-amino-acid (aa)-long protein (C(1-204)). C(1-23) was found to act as an independent viral element that induces STAT1 instability, since this peptide fused to green fluorescent protein (C(1-23)/GFP) is at least as active as C(1-204) in this respect. This peptide also induces the degradation of C(1-23)/GFP and other proteins to which it is fused. Most of C(1-204), and particularly its amino-terminal half, is predicted to be structurally disordered. C(1-23) as a peptide was found to be disordered by circular dichroism, and the first 11 aa have a strong potential to form an amphipathic alpha-helix in low concentrations of trifluoroethanol, which is thought to mimic protein-protein interaction. The critical degradation-determining sequence of C(1-23) was mapped by mutation to eight residues near its N terminus: (4)FLKKILKL(11). All the large hydrophobic residues of (4)FLKKILKL(11), plus its ability to form an amphipathic alpha-helix, were found to be critical for STAT1 degradation. In contrast, C(1-23)/GFP self-degradation did not require (8)ILKL(11), nor the ability to form an alpha-helix throughout this region. Remarkably, C(1-23)/GFP also stimulated C(1-204) degradation, and this degradation in trans required the same peptide determinants as for STAT1. Our results suggest that C(1-204) coordinates its dual activities of regulating viral RNA synthesis and counteracting the host innate antiviral response by sensing both its own intracellular concentration and that of STAT1.
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Affiliation(s)
- Dominique Garcin
- Department of Microbiology and Molecular Medicine, University of Geneva School of Medicine, 11 Ave. de Champel, CH1211 Geneva, Switzerland
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26
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Xu Y, Wang L, Butticè G, Sengupta PK, Smith BD. Major histocompatibility class II transactivator (CIITA) mediates repression of collagen (COL1A2) transcription by interferon gamma (IFN-gamma). J Biol Chem 2004; 279:41319-32. [PMID: 15247294 DOI: 10.1074/jbc.m404174200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Interferon gamma (IFN-gamma) plays an important role during inflammation by repressing collagen and activating major histocompatibility class II (MHC-II) expression. Activation of MHC-II by IFN-gamma requires regulatory factor for X-box 5 (RFX5) complex as well as class II transactivator (CIITA). We have shown that the RFX family binds to the COL1A2 transcription start site, and the RFX5 complex represses COL1A2 gene expression during IFN-gamma response. In this report, we demonstrate that CIITA is a key mediator of COL1A2 repression by IFN-gamma. IFN-gamma up-regulates the expression of CIITA in a time-dependent manner in lung fibroblasts and promotes CIITA protein occupancy on COL1A2 transcription start site in vivo as judged by chromatin immunoprecipitation (ChIP) assays. There are coordinate decreases in the occupancy of RNA polymerase II on the collagen transcription start site with increasing CIITA occupancy during IFN-gamma treatment. In addition, we are able to specifically knockdown the IFN-gamma-stimulated expression of CIITA utilizing short hairpin interference RNA (shRNA) against CIITA. This leads to the alleviation of COL1A2 repression and MHC-II activation by IFN-gamma. RFX5 recruits CIITA to the collagen site as evidenced by DNA affinity chromatography. The presence of RFX5 complex proteins enhances the collagen repression by CIITA reaching levels occurring during IFN-gamma treatment. Co-expression of CIITA with deletion mutations and collagen promoter constructs demonstrates that CIITA represses collagen promoter mainly through its N-terminal region including the acidic domain and the proline/serine/threonine domain. Our data suggest that CIITA is a crucial member of a repressor complex responsible for mediating COL1A2 transcription repression by IFN-gamma.
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Affiliation(s)
- Yong Xu
- Department of Biochemistry, Boston University School of Medicine and the Veterans Administration Boston Healthcare System, Boston, Massachusetts 02118, USA
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27
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Radosevich M, Ono SJ. Novel mechanisms of class II major histocompatibility complex gene regulation. Immunol Res 2003; 27:85-106. [PMID: 12637770 DOI: 10.1385/ir:27:1:85] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Class II MHC molecules present processed peptides from exogenous antigens to CD4+ helper T lymphocytes. In so doing, they are central to immunity, driving both the humoral and cell mediated arms of the immune response. Class II MHC molecules, and the genes encoding them, are expressed primarily in cells of the immune system (B cells, thymic epithelial cells, activated T cells and professional antigen presenting cells). The expression is also under developmental control. Research over the past 20 years have provided a clear understanding of the cis-elements and transcription factors that regulate the expression of Class II MHC genes. Perhaps the most critical advance has been the discovery of CIITA, a non- DNA binding activator of transcription that is a master control gene for class II gene expression. Current research is focused on understanding the situations where class II MHC gene expression occurs in a CIITA-independent pathway, and the molecular basis for this expression. Finally, significant emphasis is being placed on targeting class II MHC transcription factors to either inhibit or stimulate the immune response to transplanted tissue or in cell based vaccines. This communication outlines recent advances in this field and discusses likely areas for future research.
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Affiliation(s)
- Michael Radosevich
- Department of Immunology, Institute of Ophthalmology, University College London, University of London, London, UK
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28
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Quinn G, Bower R, Dos-Santos Cruz G, Giovino M, Xu Y, Patience C, Schuurman HJ. Structural and functional characteristics of a dominant-negative isoform of porcine MHC class II transactivator. EUROPEAN JOURNAL OF IMMUNOGENETICS : OFFICIAL JOURNAL OF THE BRITISH SOCIETY FOR HISTOCOMPATIBILITY AND IMMUNOGENETICS 2003; 30:259-70. [PMID: 12919287 DOI: 10.1046/j.1365-2370.2003.00397.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The MHC class II transactivator, CIITA, is critical for MHC class II gene expression in all species studied to date. We isolated an interferon (IFN)-gamma-inducible isoform of porcine CIITA (pCIITA') encoding a protein of 566 amino acids (aa) with significant homology to human CIITA (hCIITA). Analysis indicated that pCIITA' lacks the entire GTP-binding domain that is important for nuclear translocation and activation of target genes by hCIITA. In pCIITA' this region is replaced by a 14-aa motif with homology to several signalling peptide sequences. Expression of pCIITA' in porcine (ST-IOWA) and human (HeLa) cell lines resulted in suppression of IFN-gamma-stimulated MHC class II gene expression, at the protein and mRNA levels. We also identified two IFN-gamma-inducible variants of hCIITA, hCIITAlo and hCIITA' from Hela cells, both exhibiting dominant-negative suppression of MHC class II gene expression. Interestingly, hCIITA' encodes a predicted protein of 546 aa with a strikingly similar organization to pCIITA' including the 14-aa GTP-binding domain-replacement motif in which 10 out of 14 amino acids are identical to the pig sequence. Expression of hCIITA' and hCIITAlo sequences in Hela cells suppressed IFN-gamma-induced MHC class II gene expression. hCIITAlo, a predicted 303-aa protein with deleted GTP-binding and carboxy-terminal domain, displayed a more subtle suppression of IFN-gamma-induced MHC class II expression. These in vitro data indicate that there may be a role in vivo for isoforms of CIITA that can suppress full-length CIITA-mediated MHC class II gene expression. Both humans and now, potentially, pigs are candidate donors for organ and tissue allografts and xenografts, respectively. Regulation of MHC class II gene expression by manipulation of CIITA isoform expression in humans and pigs may provide a useful strategy for attenuation of T-cell-mediated cellular rejection.
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Affiliation(s)
- G Quinn
- Imutran Limited, A Novartis Pharma AG Co, Cambridge, UK.
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29
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Masternak K, Peyraud N, Krawczyk M, Barras E, Reith W. Chromatin remodeling and extragenic transcription at the MHC class II locus control region. Nat Immunol 2003; 4:132-7. [PMID: 12524537 DOI: 10.1038/ni883] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2002] [Accepted: 12/05/2002] [Indexed: 11/08/2022]
Abstract
In vivo, a wild-type pattern of major histocompatibility complex (MHC) class II expression requires a locus control region (LCR). Whereas the role of promoter-proximal MHC class II regulatory sequences is well established, the function of the distal LCR remained obscure. We show here that this LCR is bound by the MHC class II-specific transactivators regulatory factor X (RFX) and class II transactivator (CIITA). Binding of these factors induces long-range histone acetylation, RNA polymerase II recruitment and the synthesis of extragenic transcripts within the LCR. The finding that RFX and CIITA regulate the function of the MHC class II LCR reveals an unexpected degree of complexity in the mechanisms controlling MHC class II gene expression.
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30
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Garcin D, Marq JB, Goodbourn S, Kolakofsky D. The amino-terminal extensions of the longer Sendai virus C proteins modulate pY701-Stat1 and bulk Stat1 levels independently of interferon signaling. J Virol 2003; 77:2321-9. [PMID: 12551969 PMCID: PMC141115 DOI: 10.1128/jvi.77.4.2321-2329.2003] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The Sendai virus (SeV) C proteins are known to interact with Stat1 to prevent interferon (IFN)-induced pY701-Stat1 formation and IFN signaling. Nevertheless, pY701-Stat1 levels paradoxically increase during SeV infection. The C proteins also induce bulk Stat1 instability in some cells, similar to rubulavirus V proteins. We have found that SeV infection increases pY701-Stat1 levels even in cells in which bulk Stat1 levels strongly decrease. Remarkably, both the decrease in bulk Stat1 levels and the increase in pY701-Stat1 levels were found to be independent of the IFN signaling system, i.e., these events occur in mutant cells in which various components of the IFN signaling system have been disabled. Consistent with this, the C-induced decrease in Stat1 levels does not require Y701 of Stat1. We present evidence that C interacts with Stat1 in two different ways, one that prevents IFN-induced pY701-Stat1 formation and IFN signaling that has already been documented, and another that induces pY701-Stat1 formation (while decreasing bulk Stat1 levels) in a manner that does not require IFN signaling. These two types of Stat1 interaction are also distinguishable by C gene mutations. In particular, the IFN signaling-independent Stat1 interactions specifically require the amino-terminal extensions of the longer C proteins. The actions of the SeV C proteins in counteracting the cellular antiviral response are clearly more extensive than previously appreciated.
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Affiliation(s)
- Dominique Garcin
- Department of Genetics and Microbiology, University of Geneva School of Medicine, Centre Médicale Universitaire, 9 Avenue de Champel, CH-1211 Geneva, Switzerland
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31
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Bontron S, Lin-Marq N, Strubin M. Hepatitis B virus X protein associated with UV-DDB1 induces cell death in the nucleus and is functionally antagonized by UV-DDB2. J Biol Chem 2002; 277:38847-54. [PMID: 12151405 DOI: 10.1074/jbc.m205722200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The hepatitis B virus X protein (HBx) is essential for viral infection and strongly interferes with cell growth and viability in culture. These activities involve interaction of HBx with the DDB1 subunit of UV-damaged DNA-binding factor UV-DDB. UV-DDB consists of DDB1 and a DDB2 subunit that mediates nuclear import and has recognized functions in DNA repair and E2F1-mediated transcription. Here we show that HBx retains DDB1-binding-dependent cytotoxic activities when engineered to accumulate in the nucleus but not when excluded from the nucleus. Nuclear localization of HBx does not require binding to DDB1 and remains unaffected by ectopically expressed UV-DDB subunits, indicating that HBx reaches the nuclear compartment independently of UV-DDB. Unexpectedly, HBx appears to largely exist in association with DDB1 and is in direct competition with DDB2 for binding to DDB1. Hence, HBx-mediated cell death can be relieved by increased levels of DDB2, an effect that is not observed with a naturally occurring mutant of DDB2 that lacks DDB1-binding activity. These findings indicate that HBx acts through a pathway that involves a DDB2-independent nuclear function of DDB1 and that this activity will depend on the relative concentration of DDB1 and DDB2 in cells.
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Affiliation(s)
- Séverine Bontron
- Department of Genetics and Microbiology, University Medical Centre, Rue Michel-Servet 1, 1211 Geneva 4, Switzerland
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32
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Iseni F, Garcin D, Nishio M, Kedersha N, Anderson P, Kolakofsky D. Sendai virus trailer RNA binds TIAR, a cellular protein involved in virus-induced apoptosis. EMBO J 2002; 21:5141-50. [PMID: 12356730 PMCID: PMC129035 DOI: 10.1093/emboj/cdf513] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Sendai virus (SeV) leader (le) and trailer (tr) RNAs are short transcripts generated during abortive antigenome and genome synthesis, respectively. Recom binant SeV (rSeV) that express tr-like RNAs from the leader region are non-cytopathic and, moreover, prevent wild-type SeV from inducing apoptosis in mixed infections. These rSeV thus appear to have gained a function. Here we report that tr RNA binds to a cellular protein with many links to apoptosis (TIAR) via the AU-rich sequence 5' UUUUAAAUUUU. Duplication of this AU-rich sequence alone within the le RNA confers TIAR binding on this le* RNA and a non-cytopathic phenotype to these rSeV in cell culture. Transgenic overexpression of TIAR during SeV infection promotes apoptosis and reverses the anti-apoptotic effects of le* RNA expression. More over, TIAR overexpression and SeV infection act synergistically to induce apoptosis. These short viral RNAs may act by sequestering TIAR, a multivalent RNA recognition motif (RRM) family RNA-binding protein involved in SeV-induced apoptosis. In this view, tr RNA is not simply a by-product of abortive genome synthesis, but is also an antigenome transcript that modulates the cellular antiviral response.
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Affiliation(s)
| | | | | | - Nancy Kedersha
- Department of Genetics and Microbiology, University of Geneva School of Medicine CMU, 9 Avenue de Champel, CH-1211 Geneva, Switzerland and
Division of Rheumatology and Immunology, Brigham and Women’s Hospital, Harvard Medical School, One Jimmy Fund Way, Boston, MA 02115, USA Corresponding author e-mail:
| | - Paul Anderson
- Department of Genetics and Microbiology, University of Geneva School of Medicine CMU, 9 Avenue de Champel, CH-1211 Geneva, Switzerland and
Division of Rheumatology and Immunology, Brigham and Women’s Hospital, Harvard Medical School, One Jimmy Fund Way, Boston, MA 02115, USA Corresponding author e-mail:
| | - Daniel Kolakofsky
- Department of Genetics and Microbiology, University of Geneva School of Medicine CMU, 9 Avenue de Champel, CH-1211 Geneva, Switzerland and
Division of Rheumatology and Immunology, Brigham and Women’s Hospital, Harvard Medical School, One Jimmy Fund Way, Boston, MA 02115, USA Corresponding author e-mail:
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33
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Sengupta PK, Fargo J, Smith BD. The RFX family interacts at the collagen (COL1A2) start site and represses transcription. J Biol Chem 2002; 277:24926-37. [PMID: 11986307 DOI: 10.1074/jbc.m111712200] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The transcription start site of the collagen alpha2(1) gene (COL1A2) has a sequence-specific binding site for a DNA methylation-responsive binding protein called regulatory factor for X-box 1 (RFX1) (Sengupta, P. K., Erhlich, M., and Smith, B. D. (1999) J. Biol. Chem. 274, 36649-36655). In this report, we demonstrate that RFX1 forms homodimers as well as heterodimers with RFX2 spanning the collagen transcription start site. Methylation at +7 on the coding strand increases RFX1 complex formation in gel shift assays. Methylation on the template strand, however, does not increase RFX1 complex formation. DNA from human fibroblasts contains minimal methylation on the coding strand (<4%) with variable methylation on the template strand. RFX1 acts as a repressor of collagen transcription as judged by in vitro transcription and co-transfection assays with an unmethylated collagen promoter-reporter construct. In addition, an RFX5 complex present in human fibroblasts interacts with the collagen RFX site, which is not sensitive to methylation. This is the first demonstration of RFX5 complex formation on a gene other than major histocompatibility complex (MHC) promoters. Also, RFX5 represses transcription of a collagen promoter-reporter construct in rat fibroblasts that have no detectable RFX5 complex formation or protein. RFX5 complex activates MHC II transcription by interacting with an interferon-gamma (IFN-gamma)-inducible protein, major histocompatibility class II trans-activator (CIITA). Collagen transcription is repressed by IFN-gamma in a dose-dependent manner in human but not in rat fibroblasts. IFN-gamma enhances RFX5 binding activity, and CIITA is present in the RFX5 complex of IFN-gamma-treated human fibroblasts. CIITA repressed collagen gene transcription more effectively in human fibroblasts than in rat fibroblasts, suggesting that the RFX5 complex may, in part, recruit CIITA protein to the collagen transcription start site. Thus the RFX family may be important repressors of collagen gene transcription through a RFX binding site spanning the transcription start site.
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Affiliation(s)
- Pritam K Sengupta
- Department of Biochemistry, Boston University School of Medicine, Massachusetts 02118, USA
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34
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Guicheux J, Palmer G, Relic B, Mezin F, Caverzasio J, Apostolides P, Gauchat JF, Gabay C, Guerne PA. Primary human articular chondrocytes, dedifferentiated chondrocytes, and synoviocytes exhibit differential responsiveness to interleukin-4: correlation with the expression pattern of the common receptor gamma chain. J Cell Physiol 2002; 192:93-101. [PMID: 12115740 DOI: 10.1002/jcp.10121] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Interleukin (IL)-4, which exhibits potent anti-inflammatory activities, is of potential therapeutic value in destructive arthropathies. To further define the response of human joint cells to IL-4, we analyzed the ability of this cytokine to modulate the effects of IL-1beta and growth factors. Freshly isolated chondrocytes, dedifferentiated chondrocytes, and synoviocytes were treated with IL-4 before determination of nitric oxide (NO) and collagenase production in response to IL-1beta, or before proliferation assays in presence of IL-1beta, platelet-derived growth factor (PDGF), or transforming growth factor (TGF)-beta. IL-4 downregulated IL-1beta induced NO production in dedifferentiated chondrocytes and inhibited IL-1beta induced collagenase release, as well as IL-1beta and growth factor induced proliferation in dedifferentiated chondrocytes and synoviocytes. In contrast, IL-4 had no effect in freshly isolated primary chondrocytes and in cartilage explants. The lack of response to IL-4 in primary chondrocytes was associated with impaired signal transduction, as indicated by markedly decreased IL-4 dependent tyrosine phosphorylation of signal transducer and activator of transcription (STAT)-6. It also correlated with differences in the expression pattern of IL-4 receptor (IL-4R) subunits during chondrocyte dedifferentiation. Indeed, whereas the IL-4Ralpha and IL-13Ralpha' subunits were expressed in all cell types, expression of the common receptor gamma chain was restricted to freshly isolated chondrocytes. In conclusion, IL-4 downregulated IL-1beta-induced catabolic events and cell proliferation in dedifferentiated chondrocytes and synoviocytes, but had no effects in freshly isolated chondrocytes. The difference in IL-4 responsiveness between primary and dedifferentiated chondrocytes correlated with changes in proximal signaling events and in the expression pattern of IL-4R subunits during cell dedifferentiation.
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Affiliation(s)
- Jérôme Guicheux
- Division of Rheumatology, Department of Internal Medicine, University Hospital, Geneva, Switzerland
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35
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Renno T, Wilson A, Dunkel C, Coste I, Maisnier-Patin K, Benoit de Coignac A, Aubry JP, Lees RK, Bonnefoy JY, MacDonald HR, Gauchat JF. A role for CD147 in thymic development. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 168:4946-50. [PMID: 11994445 DOI: 10.4049/jimmunol.168.10.4946] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We have previously identified a mAb that binds to a molecule expressed preferentially on the surface of cycling thymocytes. In this study the molecule recognized by this mAb has been identified in the mouse as CD147 (basigin) by expression cloning. We show that CD147 expression correlates with cycling of immature thymocytes even in the absence of TCRbeta selection and that ligation of this molecule on immature fetal thymocytes inhibits their further development into mature T cells.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antibodies, Monoclonal/metabolism
- Antigens, CD
- Antigens, Neoplasm
- Antigens, Surface
- Avian Proteins
- Base Sequence
- Basigin
- Binding Sites, Antibody/genetics
- Blood Proteins
- Cell Cycle/genetics
- Cell Cycle/immunology
- Cell Differentiation/genetics
- Cell Differentiation/immunology
- Cell Line
- Cloning, Molecular
- Female
- Fetus
- Humans
- Membrane Glycoproteins/biosynthesis
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/immunology
- Membrane Glycoproteins/physiology
- Membrane Proteins/genetics
- Membrane Proteins/immunology
- Membrane Proteins/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Molecular Sequence Data
- Organ Culture Techniques
- Receptors, Antigen, T-Cell, alpha-beta/biosynthesis
- Thymus Gland/cytology
- Thymus Gland/embryology
- Thymus Gland/immunology
- Thymus Gland/metabolism
- Tumor Cells, Cultured
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Affiliation(s)
- Toufic Renno
- Centre d'Immunologie Pierre Fabre, 5 Avenue Napoleon III, Saint-Julien en Genevois, 74160 France
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36
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Masternak K, Reith W. Promoter-specific functions of CIITA and the MHC class II enhanceosome in transcriptional activation. EMBO J 2002; 21:1379-88. [PMID: 11889043 PMCID: PMC125922 DOI: 10.1093/emboj/21.6.1379] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Transcription of the major histocompatibility complex class II family of genes is regulated by conserved promoter elements and two gene-specific trans-activators, RFX and CIITA. RFX binds DNA and nucleates the assembly of an enhanceosome, which recruits CIITA through protein--protein interactions. Transcriptional activation is a complex, multi-step process involving chromatin modification and recruitment of the transcription apparatus. To examine the roles of the enhanceosome and CIITA in these processes, we analysed the level of promoter-associated hyperacetylated histones H3 and H4, TBP, TFIIB and RNA poly merase II in cells lacking RFX or CIITA. We compared four genes co-regulated by RFX and CIITA (HLA-DRA, HLA-DPB, HLA-DMB and Ii) and found that the enhanceosome and CIITA make variable, promoter-dependent contributions to histone acetylation and transcription apparatus recruitment. CIITA is generally implicated at multiple levels of the activation process, while the enhanceosome contributes in a CIITA-independent manner only at certain promoters. Our results support the general notion that the impact of a particular activator on transcription in vivo may vary depending on the promoter and the chromatin context.
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Affiliation(s)
- Krzysztof Masternak
- Department of Genetics and Microbiology, University of Geneva Medical School, 1 rue Michel-Servet, CH-1211 Genève 4, Switzerland
Present address: NovImmune S.A., 64 avenue de la Roseraie, CH-1211 Genève 4, Switzerland Corresponding author e-mail:
| | - Walter Reith
- Department of Genetics and Microbiology, University of Geneva Medical School, 1 rue Michel-Servet, CH-1211 Genève 4, Switzerland
Present address: NovImmune S.A., 64 avenue de la Roseraie, CH-1211 Genève 4, Switzerland Corresponding author e-mail:
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37
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Stauffer Y, Marguerat S, Meylan F, Ucla C, Sutkowski N, Huber B, Pelet T, Conrad B. Interferon-alpha-induced endogenous superantigen. a model linking environment and autoimmunity. Immunity 2001; 15:591-601. [PMID: 11672541 DOI: 10.1016/s1074-7613(01)00212-6] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
We earlier proposed that a human endogenous retroviral (HERV) superantigen (SAg) IDDMK(1,2)22 may cause type I diabetes by activating autoreactive T cells. Viral infections and induction of interferon-alpha (IFN-alpha) are tightly associated with the onset of autoimmunity. Here we establish a link between viral infections and IFN-alpha-regulated SAg expression of the polymorphic and defective HERV-K18 provirus. HERV-K18 has three alleles, IDDMK(1,2)22 and two full-length envelope genes, that all encode SAgs. Expression of HERV-K18 SAgs is inducible by IFN-alpha and this is sufficient to stimulate V beta 7 T cells to levels comparable to transfectants constitutively expressing HERV-K18 SAgs. Endogenous SAgs induced via IFN-alpha by viral infections is a novel mechanism through which environmental factors may cause disease in genetically susceptible individuals.
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Affiliation(s)
- Y Stauffer
- Department of Genetics and Microbiology, University of Geneva Medical School, 1211 Geneva 4, Switzerland
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38
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Peretti M, Villard J, Barras E, Zufferey M, Reith W. Expression of the three human major histocompatibility complex class II isotypes exhibits a differential dependence on the transcription factor RFXAP. Mol Cell Biol 2001; 21:5699-709. [PMID: 11486010 PMCID: PMC87290 DOI: 10.1128/mcb.21.17.5699-5709.2001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2001] [Accepted: 06/11/2001] [Indexed: 11/20/2022] Open
Abstract
Major histocompatibility complex class II (MHCII) molecules play a pivotal role in the immune system because they direct the development and activation of CD4(+) T cells. There are three human MHCII isotypes, HLA-DR, HLA-DQ, and HLA-DP. Key transcription factors controlling MHCII genes have been identified by virtue of the fact that they are mutated in a hereditary immunodeficiency resulting from a lack of MHCII expression. RFXAP-one of the factors affected in this disease-is a subunit of RFX, a DNA-binding complex that recognizes the X box present in all MHCII promoters. To facilitate identification of conserved regions in RFXAP, we isolated the mouse gene. We then delimited conserved domains required to restore endogenous MHCII expression in cell lines lacking a functional RFXAP gene. Surprisingly, we found that 80% of RFXAP is dispensable for the reactivation of DR expression. Only a short C-terminal segment of the protein is essential for this isotype. In contrast, optimal expression of DQ and DP requires a larger C-terminal segment. These results define an RFXAP domain with an MHCII isotype-specific function. Expression of the three MHCII isotypes exhibits a differential requirement for this domain. We show that this is due to a differential dependence on this domain for promoter occupation and recruitment of the coactivator CIITA in vivo.
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Affiliation(s)
- M Peretti
- Department of Genetics and Microbiology, University of Geneva Medical School, CMU, 1 rue Michel-Servet, 1211 Geneva, Switzerland
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39
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Lin-Marq N, Bontron S, Leupin O, Strubin M. Hepatitis B virus X protein interferes with cell viability through interaction with the p127-kDa UV-damaged DNA-binding protein. Virology 2001; 287:266-74. [PMID: 11531405 DOI: 10.1006/viro.2001.1036] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The hepatitis B virus X protein (HBx) is essential for establishing natural viral infection and has been implicated in the development of liver cancer associated with chronic infection. The basis for HBx function in either process is not understood. In cell culture, HBx exhibits pleiotropic activities affecting transcription, DNA repair, cell growth, and apoptotic cell death. Numerous cellular proteins including the p127-kDa subunit of UV-damaged DNA-binding activity have been reported to interact with HBx but the functional significance of these interactions remains unclear. Here we show that the binding of HBx to p127 interferes with cell viability. Mutational analysis reveals that HBx contacts p127 via a region to which no function has been assigned previously. An HBx variant bearing a single-charge reversal substitution within this region loses p127 binding and concomitant cytotoxicity. This mutant regains activity when directly fused to p127. These studies confirm that p127 is an important cellular target of HBx, and they indicate that HBx does not exert its effect by sequestering p127, and thereby preventing its normal function, but instead by conferring to p127 a deleterious activity.
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Affiliation(s)
- N Lin-Marq
- Department of Genetics and Microbiology, University Medical Centre, Rue Michel-Servet 1, Geneva 4, 1211, Switzerland
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40
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Kretsovali A, Spilianakis C, Dimakopoulos A, Makatounakis T, Papamatheakis J. Self-association of class II transactivator correlates with its intracellular localization and transactivation. J Biol Chem 2001; 276:32191-7. [PMID: 11413136 DOI: 10.1074/jbc.m103164200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Class II transactivator (CIITA) is the master regulator of major histocompatibility complex class II genes that regulates both B lymphocyte-specific and interferon gamma-inducible expression. Here we identify protein regions and examine mechanisms that determine the intracellular distribution of CIITA. We show that two separate regions of CIITA mediate nuclear export: amino acids 1-114 and 408-550. Both regions interact with the export receptor CRM-1. The CIITA region spanning amino acids 408-550 of CIITA also determines its ability for homotypic self-association as well as heterotypic interactions with other regions residing at the amino and carboxyl termini of the protein. These observations are in line with data demonstrating that co-expression of amino- and carboxyl-terminal parts of CIITA promote subcellular relocalization and, remarkably, rescue transcriptional activation by individually inert molecules. CIITA point mutations that impair nuclear import and abolish its activation function show reduced self-association. We propose that the concerted action of homo- and heterotypic interactions of CIITA determine proper protein configuration that in turn controls its nucleocytoplasmic trafficking.
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Affiliation(s)
- A Kretsovali
- Foundation for Research and Technology, Institute of Molecular Biology and Biotechnology, Heraklion, 711 10 Crete, Greece.
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41
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Landmann S, Mühlethaler-Mottet A, Bernasconi L, Suter T, Waldburger JM, Masternak K, Arrighi JF, Hauser C, Fontana A, Reith W. Maturation of dendritic cells is accompanied by rapid transcriptional silencing of class II transactivator (CIITA) expression. J Exp Med 2001; 194:379-91. [PMID: 11514596 PMCID: PMC2193505 DOI: 10.1084/jem.194.4.379] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Cell surface expression of major histocompatibility complex class II (MHCII) molecules is increased during the maturation of dendritic cells (DCs). This enhances their ability to present antigen and activate naive CD4(+) T cells. In contrast to increased cell surface MHCII expression, de novo biosynthesis of MHCII mRNA is turned off during DC maturation. We show here that this is due to a remarkably rapid reduction in the synthesis of class II transactivator (CIITA) mRNA and protein. This reduction in CIITA expression occurs in human monocyte-derived DCs and mouse bone marrow-derived DCs, and is triggered by a variety of different maturation stimuli, including lipopolysaccharide, tumor necrosis factor alpha, CD40 ligand, interferon alpha, and infection with Salmonella typhimurium or Sendai virus. It is also observed in vivo in splenic DCs in acute myelin oligodendrocyte glycoprotein induced experimental autoimmune encephalitis. The arrest in CIITA expression is the result of a transcriptional inactivation of the MHC2TA gene. This is mediated by a global repression mechanism implicating histone deacetylation over a large domain spanning the entire MHC2TA regulatory region.
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Affiliation(s)
- Salomé Landmann
- Department of Genetics and Microbiology, University of Geneva Medical School, CMU, 1211 Geneva, Switzerland
| | - Annick Mühlethaler-Mottet
- Department of Genetics and Microbiology, University of Geneva Medical School, CMU, 1211 Geneva, Switzerland
| | - Luca Bernasconi
- Section of Clinical Immunology, University Hospital Zürich, 8044 Zürich, Switzerland
| | - Tobias Suter
- Section of Clinical Immunology, University Hospital Zürich, 8044 Zürich, Switzerland
| | - Jean-Marc Waldburger
- Department of Genetics and Microbiology, University of Geneva Medical School, CMU, 1211 Geneva, Switzerland
| | - Krzysztof Masternak
- Department of Genetics and Microbiology, University of Geneva Medical School, CMU, 1211 Geneva, Switzerland
| | - Jean-François Arrighi
- Division of Immunology and Allergy, Department of Dermatology, University Hospital Geneva, 1211 Geneva, Switzerland
| | - Conrad Hauser
- Division of Immunology and Allergy, Department of Dermatology, University Hospital Geneva, 1211 Geneva, Switzerland
| | - Adriano Fontana
- Section of Clinical Immunology, University Hospital Zürich, 8044 Zürich, Switzerland
| | - Walter Reith
- Department of Genetics and Microbiology, University of Geneva Medical School, CMU, 1211 Geneva, Switzerland
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42
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Abstract
The bare lymphocyte syndrome (BLS) is a hereditary immunodeficiency resulting from the absence of major histocompatibility complex class II (MHCII) expression. Considering the central role of MHCII molecules in the development and activation of CD4(+) T cells, it is not surprising that the immune system of the patients is severely impaired. BLS is the prototype of a "disease of gene regulation." The affected genes encode RFXANK, RFX5, RFXAP, and CIITA, four regulatory factors that are highly specific and essential for MHCII genes. The first three are subunits of RFX, a trimeric complex that binds to all MHCII promoters. CIITA is a non-DNA-binding coactivator that functions as the master control factor for MHCII expression. The study of RFX and CIITA has made major contributions to our comprehension of the molecular mechanisms controlling MHCII genes and has made this system into a textbook model for the regulation of gene expression.
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Affiliation(s)
- W Reith
- Jeantet Laboratory of Molecular Genetics, Department of Genetics and Microbiology, University of Geneva Medical School, 1 rue Michel-Servet, Geneva 4, 1211 Switzerland.
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43
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Kanazawa S, Peterlin BM. Combinations of dominant-negative class II transactivator, p300 or CDK9 proteins block the expression of MHC II genes. Int Immunol 2001; 13:951-8. [PMID: 11431425 DOI: 10.1093/intimm/13.7.951] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The class II transactivator (CIITA) regulates not only the transcription of HLA-DR, -DQ, -DP, but also invariant chain, DMA and DMB genes. A hybrid mutant CIITA protein, which contained residues from positions 302 to 1130 in CIITA fused to the enhanced green fluorescent protein (EdCIITA), inhibited the function of the wild-type protein. EdCIITA extinguished the inducible and constitutive expression of MHC II genes in epithelial cells treated with IFN-gamma and B lymphoblastoid cells respectively. Also, it blocked T cell activation by superantigen. This inhibition correlated with the localization of EdCIITA but not CIITA in the cytoplasm of cells. However, when EdCIITA was co-expressed with a dominant-negative form of the nucleoporin Nup214/CAN, it also accumulated in the nucleus. These data suggest that EdCIITA not only competes with the wild-type protein for the binding to MHC II promoters but sequesters a critical co-factor of CIITA in the cytoplasm. CIITA also recruits the histone acetyltransferase cAMP responsive element binding protein (CREB) binding protein and positive transcription elongation factor b (p-TEFb) for the transcription of MHC II genes. Dominant-negative p300 (DNp300) or CDK9 (DNCDK9) proteins inhibited the function of CIITA and of the DRA promoter. Thus, combinations of EdCIITA and DNp300 and/or DNCDK9 proteins extinguished the transcription of MHC II genes. They might become useful for future genetic therapeutic approaches in organ transplantation and autoimmune diseases.
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Affiliation(s)
- S Kanazawa
- Department of Medicine, Howard Hughes Medical Institute, University of California, San Francisco, CA 94143-0703, USA
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Li G, Harton JA, Zhu X, Ting JP. Downregulation of CIITA function by protein kinase a (PKA)-mediated phosphorylation: mechanism of prostaglandin E, cyclic AMP, and PKA inhibition of class II major histocompatibility complex expression in monocytic lines. Mol Cell Biol 2001; 21:4626-35. [PMID: 11416140 PMCID: PMC87128 DOI: 10.1128/mcb.21.14.4626-4635.2001] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Prostaglandins, pleiotropic immune modulators that induce protein kinase A (PKA), inhibit gamma interferon induction of class II major histocompatibility complex (MHC) genes. We show that phosphorylation of CIITA by PKA accounts for this inhibition. Treatment with prostaglandin E or 8-bromo-cyclic AMP or transfection with PKA inhibits the activity of CIITA in both mouse and human monocytic cell lines. This inhibition is independent of other transcription factors for the class II MHC promoter. These same treatments also greatly reduced the induction of class II MHC mRNA by CIITA. PKA phosphorylation sites were identified using site-directed mutagenesis and phosphoamino acid analysis. Phosphorylation at CIITA serines 834 and 1050 accounts for the inhibitory effects of PKA on CIITA-driven class II MHC transcription. This is the first demonstration that the posttranslational modification of CIITA mediates inhibition of class II MHC transcription.
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Affiliation(s)
- G Li
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7295, USA
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Poudrier J, Graber P, Herren S, Berney C, Gretener D, Kosco-Vilbois MH, Gauchat JF. A novel monoclonal antibody, C41, reveals IL-13Ralpha1 expression by murine germinal center B cells and follicular dendritic cells. Eur J Immunol 2000; 30:3157-64. [PMID: 11093130 DOI: 10.1002/1521-4141(200011)30:11<3157::aid-immu3157>3.0.co;2-h] [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: 12/13/2022]
Abstract
Responsiveness to IL-13 involves at least two chains, IL-4Ralpha and IL-13Ralpha1. Although mouse B cells express IL-4Ralpha, little is known about their expression of IL-13Ralpha chains. To investigate this topic further, we have generated a monoclonal antibody (C41) specific for murine IL-13Ralpha1. Using C41, IL-13Ralpha1 expression was detected on germinal center (GC) B cells by flow cytometry and immunohistochemistry. In addition, IL-13Ralpha1 was observed on follicular dendritic cells, but not interdigitating dendritic cells in the T cell areas. Furthermore, resting B cells also expressed IL-13Ralpha1, and in the presence of IL-13 produced increased amounts of IgM in response to in vitro CD40 stimulation. However, C41 was unable to neutralize this bioactivity. The distribution of IL-13Ralpha1 on murine B cells and during GC reactions suggests a role for IL-13 during B cell differentiation.
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Affiliation(s)
- J Poudrier
- Department of Immunology, Serono Pharmaceutical Research Institute, Geneva, Switzerland
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Hake SB, Masternak K, Kammerbauer C, Janzen C, Reith W, Steimle V. CIITA leucine-rich repeats control nuclear localization, in vivo recruitment to the major histocompatibility complex (MHC) class II enhanceosome, and MHC class II gene transactivation. Mol Cell Biol 2000; 20:7716-25. [PMID: 11003667 PMCID: PMC86349 DOI: 10.1128/mcb.20.20.7716-7725.2000] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The major histocompatibility complex (MHC) class II transactivator CIITA plays a pivotal role in the control of the cellular immune response through the quantitative regulation of MHC class II expression. We have analyzed a region of CIITA with similarity to leucine-rich repeats (LRRs). CIITA LRR alanine mutations abolish both the transactivation capacity of full-length CIITA and the dominant-negative phenotype of CIITA mutants with N-terminal deletions. We demonstrate direct interaction of CIITA with the MHC class II promoter binding protein RFX5 and could also detect novel interactions with RFXANK, NF-YB, and -YC. However, none of these interactions is influenced by CIITA LRR mutagenesis. On the other hand, chromatin immunoprecipitation shows that in vivo binding of CIITA to the MHC class II promoter is dependent on LRR integrity. LRR mutations lead to an impaired nuclear localization of CIITA, indicating that a major function of the CIITA LRRs is in nucleocytoplasmic translocation. There is, however, evidence that the CIITA LRRs are also involved more directly in MHC class II gene transactivation. CIITA interacts with a novel protein of 33 kDa in a manner sensitive to LRR mutagenesis. CIITA is therefore imported into the nucleus by an LRR-dependent mechanism, where it activates transcription through multiple protein-protein interactions with the MHC class II promoter binding complex.
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Affiliation(s)
- S B Hake
- Hans-Spemann-Laboratories, Max-Planck-Institute of Immunology, D79108 Freiburg, D79008 Freiburg, Germany
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47
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Harton JA, Ting JP. Class II transactivator: mastering the art of major histocompatibility complex expression. Mol Cell Biol 2000; 20:6185-94. [PMID: 10938095 PMCID: PMC86093 DOI: 10.1128/mcb.20.17.6185-6194.2000] [Citation(s) in RCA: 168] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2000] [Accepted: 05/18/2000] [Indexed: 11/20/2022] Open
Affiliation(s)
- J A Harton
- Department of Microbiology and Immunology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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Masternak K, Muhlethaler-Mottet A, Villard J, Zufferey M, Steimle V, Reith W. CIITA is a transcriptional coactivator that is recruited to MHC class II promoters by multiple synergistic interactions with an enhanceosome complex. Genes Dev 2000; 14:1156-66. [PMID: 10809673 PMCID: PMC316580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
By virtue of its control over major histocompatibility complex class II (MHC-II) gene expression, CIITA represents a key molecule in the regulation of adaptive immune responses. It was first identified as a factor that is defective in MHC-II deficiency, a hereditary disease characterized by the absence of MHC-II expression. CIITA is a highly regulated transactivator that governs all spatial, temporal, and quantitative aspects of MHC-II expression. It has been proposed to act as a non-DNA-binding transcriptional coactivator, but evidence that it actually functions at the level of MHC-II promoters was lacking. By means of chromatin immunoprecipitation assays, we show here for the first time that CIITA is physically associated with MHC-II, as well as HLA-DM, Ii, MHC-I, and beta(2)m promoters in vivo. To dissect the mechanism by which CIITA is recruited to the promoter, we have developed a DNA-dependent coimmunoprecipitation assay and a pull-down assay using immobilized promoter templates. We demonstrate that CIITA recruitment depends on multiple, synergistic protein-protein interactions with DNA-bound factors constituting the MHC-II enhanceosome. CIITA therefore represents a paradigm for a novel type of regulatory and gene-specific transcriptional cofactor.
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Affiliation(s)
- K Masternak
- Department of Genetics and Microbiology, University of Geneva Medical School, 1211 Geneva, Switzerland
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Masternak K, Muhlethaler-Mottet A, Villard J, Zufferey M, Steimle V, Reith W. CIITA is a transcriptional coactivator that is recruited to MHC class II promoters by multiple synergistic interactions with an enhanceosome complex. Genes Dev 2000. [DOI: 10.1101/gad.14.9.1156] [Citation(s) in RCA: 149] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
By virtue of its control over major histocompatibility complex class II (MHC-II) gene expression, CIITA represents a key molecule in the regulation of adaptive immune responses. It was first identified as a factor that is defective in MHC-II deficiency, a hereditary disease characterized by the absence of MHC-II expression. CIITA is a highly regulated transactivator that governs all spatial, temporal, and quantitative aspects of MHC-II expression. It has been proposed to act as a non-DNA-binding transcriptional coactivator, but evidence that it actually functions at the level of MHC-II promoters was lacking. By means of chromatin immunoprecipitation assays, we show here for the first time that CIITA is physically associated with MHC-II, as well asHLA–DM, Ii, MHC-I, and β2mpromoters in vivo. To dissect the mechanism by which CIITA is recruited to the promoter, we have developed a DNA-dependent coimmunoprecipitation assay and a pull-down assay using immobilized promoter templates. We demonstrate that CIITA recruitment depends on multiple, synergistic protein–protein interactions with DNA-bound factors constituting the MHC-II enhanceosome. CIITA therefore represents a paradigm for a novel type of regulatory and gene-specific transcriptional cofactor.
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50
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Villard J, Peretti M, Masternak K, Barras E, Caretti G, Mantovani R, Reith W. A functionally essential domain of RFX5 mediates activation of major histocompatibility complex class II promoters by promoting cooperative binding between RFX and NF-Y. Mol Cell Biol 2000; 20:3364-76. [PMID: 10779326 PMCID: PMC85629 DOI: 10.1128/mcb.20.10.3364-3376.2000] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/1999] [Accepted: 02/18/2000] [Indexed: 11/20/2022] Open
Abstract
Major histocompatibility complex class II (MHC-II) molecules occupy a pivotal position in the adaptive immune system, and correct regulation of their expression is therefore of critical importance for the control of the immune response. Several regulatory factors essential for the transcription of MHC-II genes have been identified by elucidation of the molecular defects responsible for MHC-II deficiency, a hereditary immunodeficiency disease characterized by regulatory defects abrogating MHC-II expression. Three of these factors, RFX5, RFXAP, and RFXANK, combine to form the RFX complex, a regulatory protein that binds to the X box DNA sequence present in all MHC-II promoters. In this study we have undertaken a dissection of the structure and function of RFX5, the largest subunit of the RFX complex. The results define two distinct domains serving two different essential functions. A highly conserved N-terminal region of RFX5 is required for its association with RFXANK and RFXAP, for assembly of the RFX complex in vivo and in vitro, and for binding of this complex to its X box target site in the MHC-II promoter. This N-terminal region is, however, not sufficient for activation of MHC-II expression. This requires an additional domain within the C-terminal region of RFX5. This C-terminal domain mediates cooperative binding between the RFX complex and NF-Y, a transcription factor binding to the Y box sequence of MHC-II promoters. This provides direct evidence that RFX5-mediated cooperative binding between RFX and NF-Y plays an essential role in the transcriptional activation of MHC-II genes.
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Affiliation(s)
- J Villard
- Department of Genetics and Microbiology, University of Geneva Medical School, CH-1211 Geneva 4, Switzerland.
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