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He L, Yang J, Hao Y, Yang X, Shi X, Zhang D, Zhao D, Yan W, Bie X, Chen L, Chen G, Zhao S, Liu X, Zheng H, Zhang K. DDX20: A Multifunctional Complex Protein. Molecules 2023; 28:7198. [PMID: 37894677 PMCID: PMC10608988 DOI: 10.3390/molecules28207198] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 09/18/2023] [Accepted: 09/28/2023] [Indexed: 10/29/2023] Open
Abstract
DEAD-box decapping enzyme 20 (DDX20) is a putative RNA-decapping enzyme that can be identified by the conserved motif Asp-Glu-Ala-Asp (DEAD). Cellular processes involve numerous RNA secondary structure alterations, including translation initiation, nuclear and mitochondrial splicing, and assembly of ribosomes and spliceosomes. DDX20 reportedly plays an important role in cellular transcription and post-transcriptional modifications. On the one hand, DDX20 can interact with various transcription factors and repress the transcriptional process. On the other hand, DDX20 forms the survival motor neuron complex and participates in the assembly of snRNP, ultimately affecting the RNA splicing process. Finally, DDX20 can potentially rely on its RNA-unwinding enzyme function to participate in microRNA (miRNA) maturation and act as a component of the RNA-induced silencing complex. In addition, although DDX20 is not a key component in the innate immune system signaling pathway, it can affect the nuclear factor kappa B (NF-κB) and p53 signaling pathways. In particular, DDX20 plays different roles in tumorigenesis development through the NF-κB signaling pathway. This process is regulated by various factors such as miRNA. DDX20 can influence processes such as viral replication in cells by interacting with two proteins in Epstein-Barr virus and can regulate the replication process of several viruses through the innate immune system, indicating that DDX20 plays an important role in the innate immune system. Herein, we review the effects of DDX20 on the innate immune system and its role in transcriptional and post-transcriptional modification processes, based on which we provide an outlook on the future of DDX20 research in innate immunity and viral infections.
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Affiliation(s)
- Lu He
- State Key Laboratory for Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, China
- Gansu Province Research Center for Basic Disciplines of Pathogen Biology, Lanzhou 730046, China
| | - Jinke Yang
- State Key Laboratory for Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, China
- Gansu Province Research Center for Basic Disciplines of Pathogen Biology, Lanzhou 730046, China
| | - Yu Hao
- State Key Laboratory for Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, China
- Gansu Province Research Center for Basic Disciplines of Pathogen Biology, Lanzhou 730046, China
| | - Xing Yang
- State Key Laboratory for Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, China
- Gansu Province Research Center for Basic Disciplines of Pathogen Biology, Lanzhou 730046, China
| | - Xijuan Shi
- State Key Laboratory for Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, China
- Gansu Province Research Center for Basic Disciplines of Pathogen Biology, Lanzhou 730046, China
| | - Dajun Zhang
- State Key Laboratory for Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, China
- Gansu Province Research Center for Basic Disciplines of Pathogen Biology, Lanzhou 730046, China
| | - Dengshuai Zhao
- State Key Laboratory for Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, China
- Gansu Province Research Center for Basic Disciplines of Pathogen Biology, Lanzhou 730046, China
| | - Wenqian Yan
- State Key Laboratory for Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, China
- Gansu Province Research Center for Basic Disciplines of Pathogen Biology, Lanzhou 730046, China
| | - Xintian Bie
- State Key Laboratory for Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, China
- Gansu Province Research Center for Basic Disciplines of Pathogen Biology, Lanzhou 730046, China
| | - Lingling Chen
- State Key Laboratory for Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, China
- Gansu Province Research Center for Basic Disciplines of Pathogen Biology, Lanzhou 730046, China
| | - Guohui Chen
- State Key Laboratory for Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, China
- Gansu Province Research Center for Basic Disciplines of Pathogen Biology, Lanzhou 730046, China
| | - Siyue Zhao
- State Key Laboratory for Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, China
- Gansu Province Research Center for Basic Disciplines of Pathogen Biology, Lanzhou 730046, China
| | - Xiangtao Liu
- State Key Laboratory for Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, China
- Gansu Province Research Center for Basic Disciplines of Pathogen Biology, Lanzhou 730046, China
| | - Haixue Zheng
- State Key Laboratory for Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, China
- Gansu Province Research Center for Basic Disciplines of Pathogen Biology, Lanzhou 730046, China
| | - Keshan Zhang
- State Key Laboratory for Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou 730000, China
- Gansu Province Research Center for Basic Disciplines of Pathogen Biology, Lanzhou 730046, China
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Li J, Zhang Z, Lv J, Ma Z, Pan L, Zhang Y. Global Phosphoproteomics Analysis of IBRS-2 Cells Infected With Senecavirus A. Front Microbiol 2022; 13:832275. [PMID: 35154063 PMCID: PMC8826396 DOI: 10.3389/fmicb.2022.832275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 01/05/2022] [Indexed: 11/24/2022] Open
Abstract
Phosphorylation is a widespread posttranslational modification that regulates numerous biological processes. Viruses can alter the physiological activities of host cells to promote virus particle replication, and manipulating phosphorylation is one of the mechanisms. Senecavirus A (SVA) is the causative agent of porcine idiopathic vesicular disease. Although numerous studies on SVA have been performed, comprehensive phosphoproteomics analysis of SVA infection is lacking. The present study performed a quantitative mass spectrometry-based phosphoproteomics survey of SVA infection in Instituto Biologico-Rim Suino-2 (IBRS-2) cells. Three parallel experiments were performed, and 4,520 phosphosites were quantified on 2,084 proteins. Gene Ontology (GO) functional enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses showed that many phosphorylated proteins were involved in apoptosis and spliceosome pathways, and subcellular structure localization analysis revealed that more than half were located in the nucleus. Motif analysis of proteins with differentially regulated phosphosites showed that proline, aspartic acid, and glutamic acid were the most abundant residues in the serine motif, while proline and arginine were the most abundant in the threonine motif. Forty phosphosites on 27 proteins were validated by parallel reaction monitoring (PRM) phosphoproteomics, and 30 phosphosites in 21 proteins were verified. Nine proteins with significantly altered phosphosites were further discussed, and eight [SRRM2, CDK13, DDX20, DDX21, BAD, ELAVL1, PDZ-binding kinase (PBK), and STAT3] may play a role in SVA infection. Finally, kinase activity prediction showed 10 kinases’ activity was reversed following SVA infection. It is the first phosphoproteomics analysis of SVA infection of IBRS-2 cells, and the results greatly expand our knowledge of SVA infection. The findings provide a basis for studying the interactions of other picornaviruses and their mammalian host cells.
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Affiliation(s)
- Jieyi Li
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Animal Virology of Ministry of Agriculture, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Zhongwang Zhang
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Animal Virology of Ministry of Agriculture, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
- Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonose, Yangzhou University, Yangzhou, China
- *Correspondence: Zhongwang Zhang,
| | - Jianliang Lv
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Animal Virology of Ministry of Agriculture, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
- Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonose, Yangzhou University, Yangzhou, China
| | - Zhongyuan Ma
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Animal Virology of Ministry of Agriculture, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Li Pan
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Animal Virology of Ministry of Agriculture, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
- Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonose, Yangzhou University, Yangzhou, China
- Li Pan,
| | - Yongguang Zhang
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Animal Virology of Ministry of Agriculture, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
- Lanzhou Institute of Husbandry and Pharmaceutical Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
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Mühe J, Wang F. Species-specific functions of Epstein-Barr virus nuclear antigen 2 (EBNA2) reveal dual roles for initiation and maintenance of B cell immortalization. PLoS Pathog 2017; 13:e1006772. [PMID: 29261800 PMCID: PMC5754137 DOI: 10.1371/journal.ppat.1006772] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 01/04/2018] [Accepted: 11/27/2017] [Indexed: 01/08/2023] Open
Abstract
Epstein-Barr virus (EBV) and related lymphocryptoviruses (LCV) from non-human primates infect B cells, transform their growth to facilitate life-long viral persistence in the host, and contribute to B cell oncogenesis. Co-evolution of LCV with their primate hosts has led to species-specificity so that LCVs preferentially immortalize B cells from their natural host in vitro. We investigated whether the master regulator of transcription, EBV nuclear antigen 2 (EBNA2), is involved in LCV species-specificity. Using recombinant EBVs, we show that EBNA2 orthologues of LCV isolated from chimpanzees, baboons, cynomolgus or rhesus macaques cannot replace EBV EBNA2 for the immortalization of human B cells. Thus, LCV species-specificity is functionally linked to viral proteins expressed during latent, growth-transforming infection. In addition, we identified three independent domains within EBNA2 that act through species-specific mechanisms. Importantly, the EBNA2 orthologues and species-specific EBNA2 domains separate unique roles for EBNA2 in the initiation of B cell immortalization from those responsible for maintaining the immortalized state. Investigating LCV species-specificity provides a novel approach to identify critical steps underlying EBV-induced B cell growth transformation, persistent infection, and oncogenesis.
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Affiliation(s)
- Janine Mühe
- Department of Medicine, Brigham & Women's Hospital, Boston, United States of America
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, United States of America
| | - Fred Wang
- Department of Medicine, Brigham & Women's Hospital, Boston, United States of America
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, United States of America
- * E-mail:
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Abstract
While all herpesviruses can switch between lytic and latent life cycle, which are both driven by specific transcription programs, a unique feature of latent EBV infection is the expression of several distinct and well-defined viral latent transcription programs called latency I, II, and III. Growth transformation of B-cells by EBV in vitro is based on the concerted action of Epstein-Barr virus nuclear antigens (EBNAs) and latent membrane proteins(LMPs). EBV growth-transformed B-cells express a viral transcriptional program, termed latency III, which is characterized by the coexpression of EBNA2 and EBNA-LP with EBNA1, EBNA3A, -3B, and -3C as well as LMP1, LMP2A, and LMP2B. The focus of this review will be to discuss the current understanding of how two of these proteins, EBNA2 and EBNA-LP, contribute to EBV-mediated B-cell growth transformation.
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Affiliation(s)
- Bettina Kempkes
- Department of Gene Vectors, Helmholtz Center Munich, German Research Center for Environmental Health, Marchioninistr. 25, 81377, Munich, Germany.
| | - Paul D Ling
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, 77030, USA.
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Takata A, Otsuka M, Yoshikawa T, Kishikawa T, Hikiba Y, Obi S, Goto T, Kang YJ, Maeda S, Yoshida H, Omata M, Asahara H, Koike K. MicroRNA-140 acts as a liver tumor suppressor by controlling NF-κB activity by directly targeting DNA methyltransferase 1 (Dnmt1) expression. Hepatology 2013; 57:162-70. [PMID: 22898998 PMCID: PMC3521841 DOI: 10.1002/hep.26011] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Accepted: 07/18/2012] [Indexed: 12/23/2022]
Abstract
UNLABELLED MicroRNAs (miRNAs) are small RNAs that regulate the expression of specific target genes. While deregulated miRNA expression levels have been detected in many tumors, whether miRNA functional impairment is also involved in carcinogenesis remains unknown. We investigated whether deregulation of miRNA machinery components and subsequent functional impairment of miRNAs are involved in hepatocarcinogenesis. Among miRNA-containing ribonucleoprotein complex components, reduced expression of DDX20 was frequently observed in human hepatocellular carcinomas, in which enhanced nuclear factor-κB (NF-κB) activity is believed to be closely linked to carcinogenesis. Because DDX20 normally suppresses NF-κB activity by preferentially regulating the function of the NF-κB-suppressing miRNA-140, we hypothesized that impairment of miRNA-140 function may be involved in hepatocarcinogenesis. DNA methyltransferase 1 (Dnmt1) was identified as a direct target of miRNA-140, and increased Dnmt1 expression in DDX20-deficient cells hypermethylated the promoters of metallothionein genes, resulting in decreased metallothionein expression leading to enhanced NF-κB activity. MiRNA-140-knockout mice were prone to hepatocarcinogenesis and had a phenotype similar to that of DDX20 deficiency, suggesting that miRNA-140 plays a central role in DDX20 deficiency-related pathogenesis. CONCLUSION These results indicate that miRNA-140 acts as a liver tumor suppressor, and that impairment of miRNA-140 function due to a deficiency of DDX20, a miRNA machinery component, could lead to hepatocarcinogenesis.
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Affiliation(s)
- Akemi Takata
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
| | - Motoyuki Otsuka
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
| | - Takeshi Yoshikawa
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
| | - Takahiro Kishikawa
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
| | - Yohko Hikiba
- Division of Gastroenterology, Institute for Adult Diseases, Asahi Life Foundation, Tokyo 100-0005, Japan
| | - Shuntaro Obi
- Department of Hepatology, Kyoundo Hospital, Tokyo 101-0062, Japan
| | - Tadashi Goto
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
| | - Young Jun Kang
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Shin Maeda
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
| | - Haruhiko Yoshida
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
| | - Masao Omata
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
| | - Hiroshi Asahara
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA,Department of Systems BioMedicine, Tokyo Medical and Dental University, Tokyo 113-8510, Japan,CREST, Japan Science and Technology Agency (JST), Tokyo 113-0033, Japan
| | - Kazuhiko Koike
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
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Liu CD, Chen YL, Min YL, Zhao B, Cheng CP, Kang MS, Chiu SJ, Kieff E, Peng CW. The nuclear chaperone nucleophosmin escorts an Epstein-Barr Virus nuclear antigen to establish transcriptional cascades for latent infection in human B cells. PLoS Pathog 2012; 8:e1003084. [PMID: 23271972 PMCID: PMC3521654 DOI: 10.1371/journal.ppat.1003084] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 10/29/2012] [Indexed: 11/18/2022] Open
Abstract
Epstein-Barr Virus (EBV) is an oncogenic γ-herpesvirus that capably establishes both latent and lytic modes of infection in host cells and causes malignant diseases in humans. Nuclear antigen 2 (EBNA2)-mediated transcription of both cellular and viral genes is essential for the establishment and maintenance of the EBV latency program in B lymphocytes. Here, we employed a protein affinity pull-down and LC-MS/MS analysis to identify nucleophosmin (NPM1) as one of the cellular proteins bound to EBNA2. Additionally, the specific domains that are responsible for protein-protein interactions were characterized as EBNA2 residues 300 to 360 and the oligomerization domain (OD) of NPM1. As in c-MYC, dramatic NPM1 expression was induced in EBV positively infected B cells after three days of viral infection, and both EBNA2 and EBNALP were implicated in the transactivation of the NPM1 promoter. Depletion of NPM1 with the lentivirus-expressed short-hairpin RNAs (shRNAs) effectively abrogated EBNA2-dependent transcription and transformation outgrowth of lymphoblastoid cells. Notably, the ATP-bound state of NPM1 was required to induce assembly of a protein complex containing EBNA2, RBP-Jκ, and NPM1 by stabilizing the interaction of EBNA2 with RBP-Jκ. In a NPM1-knockdown cell line, we demonstrated that an EBNA2-mediated transcription defect was fully restored by the ectopic expression of NPM1. Our findings highlight the essential role of NPM1 in chaperoning EBNA2 onto the latency-associated membrane protein 1 (LMP1) promoters, which is coordinated with the subsequent activation of transcriptional cascades through RBP-Jκ during EBV infection. These data advance our understanding of EBV pathology and further imply that NPM1 can be exploited as a therapeutic target for EBV-associated diseases.
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Affiliation(s)
- Cheng-Der Liu
- Department of Life Sciences, Tzu-Chi University, Hualien, Taiwan
| | - Ya-Lin Chen
- Department of Life Sciences, Tzu-Chi University, Hualien, Taiwan
| | - Yi-Li Min
- Department of Life Sciences, Tzu-Chi University, Hualien, Taiwan
| | - Bo Zhao
- Department of Medicine and Microbiology and Molecular Genetics, Channing Laboratory, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Chi-Ping Cheng
- Department of Life Sciences, Tzu-Chi University, Hualien, Taiwan
| | - Myung-Soo Kang
- Department of Medicine and Microbiology and Molecular Genetics, Channing Laboratory, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Shu-Jun Chiu
- Department of Life Sciences, Tzu-Chi University, Hualien, Taiwan
| | - Elliott Kieff
- Department of Medicine and Microbiology and Molecular Genetics, Channing Laboratory, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Chih-Wen Peng
- Department of Life Sciences, Tzu-Chi University, Hualien, Taiwan
- * E-mail:
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Binding of the heterogeneous ribonucleoprotein K (hnRNP K) to the Epstein-Barr virus nuclear antigen 2 (EBNA2) enhances viral LMP2A expression. PLoS One 2012; 7:e42106. [PMID: 22879910 PMCID: PMC3411732 DOI: 10.1371/journal.pone.0042106] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Accepted: 07/02/2012] [Indexed: 12/31/2022] Open
Abstract
The Epstein-Barr Virus (EBV) -encoded EBNA2 protein, which is essential for the in vitro transformation of B-lymphocytes, interferes with cellular processes by binding to proteins via conserved sequence motifs. Its Arginine-Glycine (RG) repeat element contains either symmetrically or asymmetrically di-methylated arginine residues (SDMA and ADMA, respectively). EBNA2 binds via its SDMA-modified RG-repeat to the survival motor neurons protein (SMN) and via the ADMA-RG-repeat to the NP9 protein of the human endogenous retrovirus K (HERV-K (HML-2) Type 1). The hypothesis of this work was that the methylated RG-repeat mimics an epitope shared with cellular proteins that is used for interaction with target structures. With monoclonal antibodies against the modified RG-repeat, we indeed identified cellular homologues that apparently have the same surface structure as methylated EBNA2. With the SDMA-specific antibodies, we precipitated the Sm protein D3 (SmD3) which, like EBNA2, binds via its SDMA-modified RG-repeat to SMN. With the ADMA-specific antibodies, we precipitated the heterogeneous ribonucleoprotein K (hnRNP K). Specific binding of the ADMA- antibody to hnRNP K was demonstrated using E. coli expressed/ADMA-methylated hnRNP K. In addition, we show that EBNA2 and hnRNP K form a complex in EBV- infected B-cells. Finally, hnRNP K, when co-expressed with EBNA2, strongly enhances viral latent membrane protein 2A (LMP2A) expression by an unknown mechanism as we did not detect a direct association of hnRNP K with DNA-bound EBNA2 in gel shift experiments. Our data support the notion that the methylated surface of EBNA2 mimics the surface structure of cellular proteins to interfere with or co-opt their functional properties.
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Takata A, Otsuka M, Yoshikawa T, Kishikawa T, Kudo Y, Goto T, Yoshida H, Koike K. A miRNA machinery component DDX20 controls NF-κB via microRNA-140 function. Biochem Biophys Res Commun 2012; 420:564-9. [PMID: 22445758 DOI: 10.1016/j.bbrc.2012.03.034] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 03/07/2012] [Indexed: 01/20/2023]
Abstract
Hepatocellular carcinoma is the third leading cause of cancer mortality worldwide, but the molecular mechanisms in tumorigenesis remain largely unknown. Previously, a DEAD-box protein DDX20, a component of microRNA-containing ribonucleoprotein complexes, was identified as a liver tumor suppressor candidate in an oncogenomics-based in vivo RNAi screen. However, the molecular mechanisms were unknown. Here, we show that deficiency of DDX20 results in the enhancement of NF-κB activity, a crucial intracellular signaling pathway closely linked with hepatocarcinogenesis. While DDX20 normally suppresses NF-κB activity by regulating NF-κB-suppressing miRNA-140 function, this suppressive effect was lost in DDX20-deficient cells. The impairment of miRNA function due to DDX20 deficiency appears to be miRNA species-specific at the point of loading miRNAs into the RNA-induced silencing complex. These results indicate that DDX20 deficiency enhances NF-κB activity by impairing the NF-κB-suppressive action of microRNAs, and suggest that dysregulation of the microRNA machinery components may also be involved in pathogenesis in various human diseases.
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Affiliation(s)
- Akemi Takata
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
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Cai Q, Guo Y, Xiao B, Banerjee S, Saha A, Lu J, Glisovic T, Robertson ES. Epstein-Barr virus nuclear antigen 3C stabilizes Gemin3 to block p53-mediated apoptosis. PLoS Pathog 2011; 7:e1002418. [PMID: 22174681 PMCID: PMC3234233 DOI: 10.1371/journal.ppat.1002418] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Accepted: 10/20/2011] [Indexed: 01/10/2023] Open
Abstract
The Epstein-Barr nuclear antigen 3C (EBNA3C), one of the essential latent antigens for Epstein-Barr virus (EBV)-induced immortalization of primary human B lymphocytes in vitro, has been implicated in regulating cell proliferation and anti-apoptosis via interaction with several cellular and viral factors. Gemin3 (also named DDX20 or DP103) is a member of DEAD RNA helicase family which exhibits diverse cellular functions including DNA transcription, recombination and repair, and RNA metabolism. Gemin3 was initially identified as a binding partner to EBNA2 and EBNA3C. However, the mechanism by which EBNA3C regulates Gemin3 function remains unclear. Here, we report that EBNA3C directly interacts with Gemin3 through its C-terminal domains. This interaction results in increased stability of Gemin3 and its accumulation in both B lymphoma cells and EBV transformed lymphoblastoid cell lines (LCLs). Moreover, EBNA3C promotes formation of a complex with p53 and Gemin3 which blocks the DNA-binding affinity of p53. Small hairpin RNA based knockdown of Gemin3 in B lymphoma or LCL cells remarkably attenuates the ability of EBNA3C to inhibit the transcription activity of p53 on its downstream genes p21 and Bax, as well as apoptosis. These findings provide the first evidence that Gemin3 may be a common target of oncogenic viruses for driving cell proliferation and anti-apoptotic activities. Gemin3 (DDX20 or DP103) is a member of the DEAD-box family of RNA helicases involved in various cellular processes including DNA transcription and RNA processing. The Epstein-Barr virus (EBV) encoded nuclear antigen 3C (EBNA3C) is essential for EBV-induced immortalization of primary human B-lymphocytes in vitro. In this study, we discovered that Gemin3 directly binds to the tumor suppressor p53, and acts as a negative regulator blocking p53 functions. Importantly, EBNA3C induces Gemin3 accumulation and enhances the formation of the complex of Gemin3 and p53 in EBV- transformed primary human B lymphocytes. Remarkably, inhibition of Gemin3 production leads to cell death of B lymphoma cells, particularly EBNA3C positive cells. This is the first evidence which shows that Gemin3 directly impairs p53 function in EBV positive cells, and that Gemin3 could be a potential target for EBV-associated cancer therapy.
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Affiliation(s)
- Qiliang Cai
- Department of Microbiology and the Tumor Virology Program, Abramson Comprehensive Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Yi Guo
- Department of Microbiology and the Tumor Virology Program, Abramson Comprehensive Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Key Laboratory of AIDS Immunology, Ministry of Health, The First Affiliated Hospital, China Medical University, Shenyang, Liaoning, People's Republic of China
| | - Bingyi Xiao
- Department of Microbiology and the Tumor Virology Program, Abramson Comprehensive Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Shuvomoy Banerjee
- Department of Microbiology and the Tumor Virology Program, Abramson Comprehensive Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Abhik Saha
- Department of Microbiology and the Tumor Virology Program, Abramson Comprehensive Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Jie Lu
- Department of Microbiology and the Tumor Virology Program, Abramson Comprehensive Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Tina Glisovic
- Howard Hughes Medical Institute and Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Erle S. Robertson
- Department of Microbiology and the Tumor Virology Program, Abramson Comprehensive Cancer Center, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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Gross H, Barth S, Pfuhl T, Willnecker V, Spurk A, Gurtsevitch V, Sauter M, Hu B, Noessner E, Mueller-Lantzsch N, Kremmer E, Grässer FA. The NP9 protein encoded by the human endogenous retrovirus HERV-K(HML-2) negatively regulates gene activation of the Epstein-Barr virus nuclear antigen 2 (EBNA2). Int J Cancer 2011; 129:1105-15. [PMID: 21710493 DOI: 10.1002/ijc.25760] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Accepted: 10/25/2010] [Indexed: 11/06/2022]
Abstract
Epstein-Barr virus (EBV) is a human tumour virus that efficiently growth-transforms primary human B-lymphocytes in vitro. The viral nuclear antigen 2 (EBNA2) is essential for immortalisation of B-cells and stimulates viral and cellular gene expression through interaction with DNA-bound transcription factors. Like its cellular homologue Notch, it associates with the DNA-bound repressor RBPJκ (CSL/CBF1) thereby converting RBPJκ into the active state. For instance, both EBNA2 and Notch activate the cellular HES1 promoter. In EBV-transformed lymphocytes, the RNA of the NP9 protein encoded by human endogenous retrovirus HERV-K(HML-2) Type 1 is strongly up-regulated. The NP9 protein is detectable both in EBV-positive Raji cells, a Burkitt's lymphoma cell line, and in IB4, an EBV-transformed human lymphoblastoid cell line. NP9 binds to LNX that forms a complex with the Notch regulator Numb. Therefore, the function of NP9 vis-à-vis Notch and EBNA2 was analysed. Here, we show that NP9 binds to EBNA2 and negatively affects the EBNA2-mediated activation of the viral C- and LMP2A promoters. In contrast, NP9 did neither interfere in the activation of the HES1 promoter by Notch nor the induction of the viral LMP1 promoter by EBNA2. In an electrophoretic mobility shift analysis, NP9 reduced the binding of EBNA2 to DNA-bound RBPJκ by about 50%. The down-regulation of EBNA2-activity by NP9 might represent a cellular defence mechanism against viral infection or could, alternatively, represent an adaptation of the virus to prevent excessive viral protein production that might otherwise be harmful for the infected cell.
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Affiliation(s)
- Henrik Gross
- Institut für Virologie, Universitätsklinikum des Saarlandes, 66421 Homburg, Germany
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11
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Gross H, Barth S, Palermo RD, Mamiani A, Hennard C, Zimber-Strobl U, West MJ, Kremmer E, Grässer FA. Asymmetric Arginine dimethylation of Epstein-Barr virus nuclear antigen 2 promotes DNA targeting. Virology 2009; 397:299-310. [PMID: 19969318 DOI: 10.1016/j.virol.2009.11.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2009] [Revised: 09/01/2009] [Accepted: 11/10/2009] [Indexed: 11/16/2022]
Abstract
The Epstein-Barr virus (EBV) growth-transforms B-lymphocytes. The virus-encoded nuclear antigen 2 (EBNA2) is essential for transformation and activates gene expression by association with DNA-bound transcription factors such as RBPJkappa (CSL/CBF1). We have previously shown that EBNA2 contains symmetrically dimethylated Arginine (sDMA) residues. Deletion of the RG-repeat results in a reduced ability of the virus to immortalise B-cells. We now show that the RG repeat also contains asymmetrically dimethylated Arginines (aDMA) but neither non-methylated (NMA) Arginines nor citrulline residues. We demonstrate that only aDMA-containing EBNA2 is found in a complex with DNA-bound RBPJkappa in vitro and preferentially associates with the EBNA2-responsive EBV C, LMP1 and LMP2A promoters in vivo. Inhibition of methylation in EBV-infected cells results in reduced expression of the EBNA2-regulated viral gene LMP1, providing additional evidence that methylation is a prerequisite for DNA-binding by EBNA2 via association with the transcription factor RBPJkappa.
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Affiliation(s)
- Henrik Gross
- Institut für Virologie, Haus 47, Universitätsklinikum, 66421 Homburg/Saar, Germany
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12
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Barth S, Pfuhl T, Mamiani A, Ehses C, Roemer K, Kremmer E, Jäker C, Höck J, Meister G, Grässer FA. Epstein-Barr virus-encoded microRNA miR-BART2 down-regulates the viral DNA polymerase BALF5. Nucleic Acids Res 2007; 36:666-75. [PMID: 18073197 PMCID: PMC2241876 DOI: 10.1093/nar/gkm1080] [Citation(s) in RCA: 259] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
MicroRNAs (miRNAs) have been implicated in sequence-specific cleavage, translational repression or deadenylation of specific target mRNAs resulting in post-transcriptional gene silencing. Epstein–Barr virus (EBV) encodes 23 miRNAs of unknown function. Here we show that the EBV-encoded miRNA miR-BART2 down-regulates the viral DNA polymerase BALF5. MiR-BART2 guides cleavage within the 3′-untranslated region (3′UTR) of BALF5 by virtue of its complete complementarity to its target. Induction of the lytic viral replication cycle results in a reduction of the level of miR-BART2 with a strong concomitant decrease of cleavage of the BALF5 3′UTR. Expression of miR-BART2 down-regulates the activity of a luciferase reporter gene containing the BALF5 3′UTR. Forced expression of miR-BART2 during lytic replication resulted in a 40–50% reduction of the level of BALF5 protein and a 20% reduction of the amount of virus released from EBV-infected cells. Our results are compatible with the notion that EBV-miR-BART2 inhibits transition from latent to lytic viral replication.
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Affiliation(s)
- Stephanie Barth
- Institute of Virology, University of Saarland Medical School, 66424 Homburg, Germany
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13
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Battle DJ, Kasim M, Wang J, Dreyfuss G. SMN-independent subunits of the SMN complex. Identification of a small nuclear ribonucleoprotein assembly intermediate. J Biol Chem 2007; 282:27953-9. [PMID: 17640873 DOI: 10.1074/jbc.m702317200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The survival of motor neurons (SMN) complex is essential for the biogenesis of small nuclear ribonucleoprotein (snRNP) complexes in eukaryotic cells. Reduced levels of SMN cause the motor neuron degenerative disease, spinal muscular atrophy. We identify here stable subunits of the SMN complex that do not contain SMN. Sedimentation and immunoprecipitation experiments using cell extracts reveal at least three complexes composed of Gemin3, -4, and -5; Gemin6, -7, and unrip; and SMN with Gemin2, as well as free Gemin5. Complexes containing Gemin3-Gemin4-Gemin5 and Gemin6-Gemin7-unrip persist at similar levels when SMN is reduced. In cells, immunofluorescence microscopy shows differential localization of Gemin5 after cell stress. We further show that the Gemin5-containing subunits bind small nuclear RNA independently of the SMN complex and without a requirement for exogenous ATP. ATP hydrolysis is, however, required for displacement of small nuclear RNAs from the Gemin5-containing subunits and their assembly into snRNPs. These findings demonstrate a modular nature of the SMN complex and identify a new intermediate in the snRNP assembly process.
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Affiliation(s)
- Daniel J Battle
- Howard Hughes Medical Institute and Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6148, USA
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14
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Abstract
The molecular basis of spinal muscular atrophy (SMA), an autosomal recessive neuromuscular disorder, is the homozygous loss of the survival motor neuron gene 1 (SMN1). A nearly identical copy of the SMN1 gene, called SMN2, modulates the disease severity. The functional difference between both genes is a translationally silent mutation that, however, disrupts an exonic splicing enhancer causing exon 7 skipping in most SMN2 transcripts. Only 10% of SMN2 transcripts encode functional full-length protein identical to SMN1. Transcriptional activation, facilitation of correct SMN2 splicing, or stabilization of the protein are considered as strategies for SMA therapy. Among various drugs, histone deacetylase inhibitors such as valproic acid (VPA) or 4-phenylbutyrate (PBA) have been shown to increase SMN2-derived RNA and protein levels. Recently, in vivo activation of the SMN gene was shown in VPA-treated SMA patients and carriers. Clinical trials are underway to investigate the effect of VPA and PBA on motor function in SMA patients.
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Affiliation(s)
- Brunhilde Wirth
- Institute of Human Genetics, Institute of Genetics and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
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15
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Eggert C, Chari A, Laggerbauer B, Fischer U. Spinal muscular atrophy: the RNP connection. Trends Mol Med 2006; 12:113-21. [PMID: 16473550 DOI: 10.1016/j.molmed.2006.01.005] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2005] [Revised: 12/22/2005] [Accepted: 01/27/2006] [Indexed: 02/01/2023]
Abstract
Degenerated motor neurons in the spinal cord are the pathological hallmark of spinal muscular atrophy (SMA). SMA is caused by mutations in the ubiquitously expressed survival motor neuron 1 (SMN1) gene, which lead to reduced levels of functional SMN protein. Many different functions have been assigned to SMN, including assembly of ribonucleoproteins (RNPs), splicing, transcription and axonal mRNA transport. Recently, tissue from SMA patients and animal models has been used to determine which function of SMN is affected in SMA patients. A surprising picture has emerged: the impaired assembly of RNP subunits of the spliceosome seems to be responsible for SMA pathogenesis. Here, we present a model of how this defect might cause motor-neuron degeneration and consider potential therapies.
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Affiliation(s)
- Christian Eggert
- Theodor Boveri Institute, Biocenter at the University of Würzburg, Am Hubland, D-97074 Würzburg, Germany
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16
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Voss MD, Beha A, Tennagels N, Tschank G, Herling AW, Quint M, Gerl M, Metz-Weidmann C, Haun G, Korn M. Gene expression profiling in skeletal muscle of Zucker diabetic fatty rats: implications for a role of stearoyl-CoA desaturase 1 in insulin resistance. Diabetologia 2005; 48:2622-30. [PMID: 16284748 DOI: 10.1007/s00125-005-0025-2] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2005] [Accepted: 07/12/2005] [Indexed: 11/26/2022]
Abstract
AIMS/HYPOTHESIS Insulin resistance in skeletal muscle is a hallmark of type 2 diabetes. Therefore, we sought to identify and validate genes involved in the development of insulin resistance in skeletal muscle. MATERIALS Differentially regulated genes in skeletal muscle of male obese insulin-resistant, and lean insulin-sensitive Zucker diabetic fatty (ZDF) rats were determined using Affymetrix microarrays. Based on these data, various aspects of glucose disposal, insulin signalling and fatty acid composition were analysed in a muscle cell line overexpressing stearoyl-CoA desaturase 1 (SCD1). RESULTS Gene expression profiling in insulin-resistant skeletal muscle revealed the most pronounced changes in gene expression for genes involved in lipid metabolism. Among these, Scd1 showed increased expression in insulin-resistant animals, correlating with increased amounts of palmitoleoyl-CoA. This was further investigated in a muscle cell line that overexpressed SCD1 and accumulated lipids, revealing impairments of glucose uptake and of different steps of the insulin signalling cascade. We also observed differential effects of high-glucose and fatty acid treatment on glucose uptake and long-chain fatty acyl-CoA profiles, and in particular an accumulation of palmitoleoyl-CoA in cells overexpressing SCD1. CONCLUSIONS/INTERPRETATION Insulin-resistant skeletal muscle of ZDF rats is characterised by a specific gene expression profile with increased levels of Scd1. An insulin-resistant phenotype similar to that obtained by treatment with palmitate and high glucose can be induced in vitro by overexpression of SCD1 in muscle cells. This supports the hypothesis that elevated SCD1 expression is a possible cause of insulin resistance and type 2 diabetes.
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Affiliation(s)
- M D Voss
- Sanofi-Aventis Deutschland GmbH, Science and Medical Affairs, TD Metabolism, Industriepark Hoechst, 65926 Frankfurt am Main, Germany.
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17
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Ning S, Huye LE, Pagano JS. Interferon regulatory factor 5 represses expression of the Epstein-Barr virus oncoprotein LMP1: braking of the IRF7/LMP1 regulatory circuit. J Virol 2005; 79:11671-6. [PMID: 16140744 PMCID: PMC1212628 DOI: 10.1128/jvi.79.18.11671-11676.2005] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
We have reported evidence for a positive regulatory circuit between interferon regulatory factor 7 (IRF7) and the Epstein-Barr virus (EBV) oncoprotein 1 (LMP1) (S. Ning, A. M. Hahn, and J. S. Pagano, J. Virol. 77:9359-9368, 2003). To explore a possible braking mechanism for this circuit, several type II EBV-infected cell lines that express different levels of LMP1 and IRF7 proteins and therefore are convenient for studying modulation of expression of LMP1 were analyzed. Endogenous levels of IRF7 and LMP1 were directly correlated. Transient expression of an IRF7 dominant-negative mutant decreased LMP1 levels. Endogenous IRF5 and IRF7 proteins were shown to physically associate in EBV-positive cells. Transient expression of IRF5 decreased activation of the LMP1 promoter by IRF7 in a dose-dependent manner. Finally, transfection of either an IRF5 dominant-negative construct or IRF5 small interfering RNA in these cells resulted in increases in endogenous levels of LMP1. These results indicate that IRF5 can downregulate IRF7's induction of expression of LMP1 most likely by interacting with IRF7 and provide a means of modulating a regulatory circuit between IRF7 and LMP1.
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Affiliation(s)
- Shunbin Ning
- Lineberger Comprehensive Cancer Center, University of North Carolina, School of Medicine, Campus Box 7295, Chapel Hill, NC 27599, USA
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18
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Pfuhl T, Dürr M, Spurk A, Schwalbert B, Nord R, Mysliwietz J, Kremmer E, Grässer FA. Biochemical characterisation of the proteins encoded by the DiGeorge critical region 6 (DGCR6) genes. Hum Genet 2005; 117:70-80. [PMID: 15821931 DOI: 10.1007/s00439-005-1267-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2004] [Accepted: 01/04/2005] [Indexed: 10/25/2022]
Abstract
The DiGeorge critical region 6 (DGCR6) gene exists in two highly homologous copies (DGCR6 and DGCR6L) on chromosome 22q11 and is deleted in patients with velo-cardio-facial syndrome/DiGeorge syndrome (VCFS/DGS). The DGCR6 mRNA levels are increased in metastatic mammary tumour cells and regulate the expression of neighbouring genes at the 22q11 region. Newly developed monoclonal antibodies detected predominantly nuclear phosphoproteins of approximately 25 kDa, with low expression levels in the cytoplasm. Both proteins have half-lives of about 2.5 h. Exogenously expressed DGCR6 and DGCR6L migrated with slightly different mobility in SDS-gels in accordance with two immunoreactive bands observed for the endogenous proteins. DGCR6 is found at low levels in primary human fibroblasts or peripheral blood mononuclear cells, while tumour cells, B-cells transformed by EBV as well as activated normal human T cells, contain elevated levels of the proteins. The proteins are differentially expressed in mammalian tissues, with high protein levels in heart, liver and skeletal muscle. These observations are important as some patients with DGCR6 syndrome exhibit a T-cell deficiency and/or cardiac malformations. As the DGCR6 protein(s) influence gene expression in trans, we analysed the influence of DGCR6/DGCR6L on the Epstein-Barr virus-encoded oncoproteins EBNA2 and EBNA3c in the activation of the viral LMP1 promoter, as well as LMP1-mediated activation of NFkB, but found no effect in either setting.
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Affiliation(s)
- Thorsten Pfuhl
- Institut für Medizinische Mikrobiologie und Hygiene, Abteilung Virologie, Universitätsklinikum des Saarlandes, Homburg/Saar, Germany
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19
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Chen H, Huang J, Wu FY, Liao G, Hutt-Fletcher L, Hayward SD. Regulation of expression of the Epstein-Barr virus BamHI-A rightward transcripts. J Virol 2005; 79:1724-33. [PMID: 15650197 PMCID: PMC544122 DOI: 10.1128/jvi.79.3.1724-1733.2005] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2004] [Accepted: 09/09/2004] [Indexed: 11/20/2022] Open
Abstract
The Epstein-Barr virus (EBV) BamHI-A rightward transcripts, or BARTs, are a family of mRNAs expressed in all EBV latency programs, including EBV-infected B cells in healthy carriers. Despite their ubiquitous expression, the regulation and biological function of BARTs are still unclear. In this study, the BART 5' termini were characterized by using a procedure that selects capped, full-length mRNAs. Two TATA-less promoter regions, designated P1 and P2, were mapped. P1 had relatively high basal activity in both epithelial and B cells, whereas P2 exhibited higher activity in epithelial cells. Upon EBV infection of B cells, transcription from P1 was detected soon after infection, while expression from P2 was delayed. Promoter-reporter assays in transiently transfected cells revealed that P1 and P2 were differentially regulated. Interferon regulatory factor 7 (IRF7) and IRF5 negatively regulated P1 activity. c-Myc and C/EBP family members positively regulated P2. Regulation of P2 by C/EBPs was characterized by electrophoretic mobility shift assay, chromatin immunoprecipitation, and reporter assays. More-abundant BART expression in epithelial cells correlated with the relative expression of positive and negative regulators in these cells.
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Affiliation(s)
- Honglin Chen
- Department of Microbiology, The University of Hong Kong, Hong Kong
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20
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Kwiatkowski BA, Ragoczy T, Ehly J, Schubach WH. Identification and cloning of a novel chromatin-associated protein partner of Epstein–Barr nuclear protein 2. Exp Cell Res 2004; 300:223-33. [PMID: 15383329 DOI: 10.1016/j.yexcr.2004.06.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2003] [Revised: 04/26/2004] [Indexed: 11/21/2022]
Abstract
In a screen for binding partners of the Epstein-Barr virus transformation-related protein EBNA2, we cloned a novel, evolutionarily conserved protein showing similarity to the Drosophila Parallel Sister Chromatids Protein (PASC). We have named this protein "Friend of EBNA2" (FOE). Human FOE encodes a protein of 1227 amino acids with a functional bipartite nuclear localization signal, an arginine-rich motif, a putative nuclear export signal as well as with three highly acidic regions and a predicted coiled-coil domain. FOE and EBNA2 coimmunoprecipitate from lymphocyte nuclear extracts. RNA and protein blots show that FOE is expressed in all human tissues. FOE is a nuclear protein with the bulk of the protein associated with the insoluble nuclear fraction biochemically defined as the nuclear matrix. Indirect immunofluorescence and dynamic imaging studies suggest that FOE associates with transcriptionally active nuclear subregions in interphase cells and concentrates at the ends of formed chromosomes during mitosis.
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Affiliation(s)
- Boguslaw A Kwiatkowski
- Division of Oncology, Department of Medicine, VA Puget Sound Health Care System S-111-ONC, Seattle, WA 98108, USA
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21
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Abstract
The Notch signaling pathway influences cell fate decisions, proliferation versus differentiation and cell survival. Viruses both utilize and manipulate the differentiation state of infected cells, promote or block cell cycling and employ a variety of mechanisms to evade innate cellular anti-viral responses and promote cell survival. In light of these commonalities, it is perhaps not surprising that several viruses have tapped into the Notch pathway to advance their own life cycles. This first became apparent from studies showing targeting of Epstein-Barr virus proteins to the nuclear effector of Notch signaling CSL (CBF1/RBPJk). More recently the Kaposi's sarcoma-associated herpesvirus RTA protein has been found to bind CSL. Notch pathway interactions have also been described for adenovirus SV40 and human papilloma virus. This review focuses on the herpesvirus protein interactions with the Notch pathway and the insights that these interactions have provided.
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Affiliation(s)
- S Diane Hayward
- Viral Oncology Program, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, School of Medicine, CRB 308, 1650 Orleans Street, Baltimore, MD 21231, USA.
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22
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Gordadze AV, Onunwor CW, Peng R, Poston D, Kremmer E, Ling PD. EBNA2 amino acids 3 to 30 are required for induction of LMP-1 and immortalization maintenance. J Virol 2004; 78:3919-29. [PMID: 15047808 PMCID: PMC374290 DOI: 10.1128/jvi.78.8.3919-3929.2004] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Epstein-Barr virus (EBV) nuclear antigen 2 (EBNA2), a direct transcriptional activator of viral and cellular genes, is required for EBV-induced B-cell transformation. The functional role of conserved regions within the amino terminus of the protein preceding the poly-proline region has yet to be fully characterized. Thus, we tested whether the EBNA2 amino-terminal 30 amino acid residues, containing evolutionarily conserved region 1, are required for stimulating viral and cellular gene expression necessary for B-cell transformation in a viral transcomplementation assay. We found that these residues are required for its ability to induce LMP-1 expression in lymphoblastoid cell lines (LCLs), to stimulate LMP-1 promoter reporter plasmids in transient-cotransfection assays, and to rescue LCL growth following inactivation of endogenous wild-type EBNA2 protein. Deletion of amino acid residues 3 to 30 also impaired its ability to self-associate in coimmunoprecipitation assays. These data indicate that EBNA2 residues 3 to 30 comprise an essential domain required for induction of LMP-1 expression and, consequently, for maintenance of the immortalized phenotype of LCLs. The ability to self-associate into dimers or multimers conferred by this domain may be an important mechanism for these effects.
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Affiliation(s)
- Alexey V Gordadze
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas 77030, USA
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23
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Yue W, Davenport MG, Shackelford J, Pagano JS. Mitosis-specific hyperphosphorylation of Epstein-Barr virus nuclear antigen 2 suppresses its function. J Virol 2004; 78:3542-52. [PMID: 15016877 PMCID: PMC371044 DOI: 10.1128/jvi.78.7.3542-3552.2004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The Epstein-Barr virus (EBV) nuclear antigen 2 (EBNA-2) is a key gene expressed in EBV type III latent infection that can transactivate numerous promoters, including those for all the other type III viral latency genes as well as cellular genes responsible for cell proliferation. EBNA-2 is essential for EBV-mediated immortalization of primary B lymphocytes. We now report that EBNA-2, a phosphoprotein, is hyperphosphorylated specifically in mitosis. Evidence that the cyclin-dependent kinase p34(cdc2) may be involved in this hyperphosphorylation includes (i) coimmunoprecipitation of EBNA-2 and p34(cdc2), suggesting physical association; (ii) temporal correlation between hyperphosphorylation of EBNA-2 and an increase in p34(cdc2) kinase activity; and (iii) ability of purified p34(cdc2)/cyclin B1 kinase to phosphorylate EBNA-2 in vitro. Hyperphosphorylation of EBNA-2 appears to suppress its ability to transactivate the latent membrane protein 1 (LMP-1) promoter by about 50%. The association between EBNA-2 and PU.1 is also decreased by about 50% in M-phase-arrested cells, as shown by coimmunoprecipitation from cell lysates, suggesting that hyperphosphorylation of EBNA-2 impairs its affinity for PU.1. Finally, endogenous LMP-1 mRNA levels in M phase are around 55% of those in asynchronously growing cells. These results suggest that regulation of gene expression during type III latency may be regulated in a cell-cycle-related manner.
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Affiliation(s)
- Wei Yue
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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24
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Farrell CJ, Lee JM, Shin EC, Cebrat M, Cole PA, Hayward SD. Inhibition of Epstein-Barr virus-induced growth proliferation by a nuclear antigen EBNA2-TAT peptide. Proc Natl Acad Sci U S A 2004; 101:4625-30. [PMID: 15070768 PMCID: PMC384797 DOI: 10.1073/pnas.0306482101] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Epstein-Barr virus (EBV) causes infectious mononucleosis and is associated with cancers in immunocompromised populations. Antiviral drugs targeted against lytic viral replication have limited efficacy in these disease settings. EBV infection of peripheral blood mononuclear cells induces growth proliferation and the EBV latency Epstein-Barr virus-encoded nuclear antigen (EBNA)2 transcriptional transactivator (TAT) is essential for this response. EBNA2 targets the cellular DNA-binding protein CBF1 to mimic activated Notch signaling. A 10-aa peptide from the CBF1 interaction domain of EBNA2 was synthesized as a fusion with the protein transduction domain of HIV-1 TAT. The EBNA2-TAT peptide blocked EBNA2-CBF1 interaction in an in vitro GST affinity assay and labeling with fluorescein confirmed that the EBNA2-TAT peptide efficiently entered cultured B cells. Neither EBNA2-TAT, nor a mutant peptide with a 2-aa substitution that was unable to block the EBNA2-CBF1 interaction, significantly affected the growth of non-EBNA2-expressing EBV(-) B cells or Burkitt's lymphoma Akata cells. However, treatment of an EBV-immortalized lymphoblastoid cell line with the EBNA2-TAT peptide stopped cell growth and reduced cell viability. RT-PCR analyses of gene expression in the peptide-treated lymphoblastoid cell line cultures revealed that EBNA2-TAT treatment down-regulated the EBNA2-responsive viral LMP1 and LMP2 genes and cellular CD23, intercellular adhesion molecule 1, BATF, and Cdk1 genes while up-regulating expression of the cyclin-dependent kinase inhibitor p21. EBV-induced outgrowth of B cells from cultured peripheral blood mononuclear cells was also blocked in a dose-responsive manner by the EBNA2-TAT peptide. This study suggests that cell-permeable EBNA2 peptides may have potential as novel anti-EBV therapeutics.
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Affiliation(s)
- Christopher J Farrell
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, 1650 Orleans Street, Baltimore, MD 21231, USA
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25
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Ning S, Hahn AM, Huye LE, Pagano JS. Interferon regulatory factor 7 regulates expression of Epstein-Barr virus latent membrane protein 1: a regulatory circuit. J Virol 2003; 77:9359-68. [PMID: 12915551 PMCID: PMC187426 DOI: 10.1128/jvi.77.17.9359-9368.2003] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
We have shown previously that interferon regulatory factor 7 (IRF7), a multifunctional protein intimately involved in latent Epstein-Barr virus (EBV) infection, is induced as well as activated by EBV latent membrane protein 1 (LMP1), the principal EBV oncoprotein. Since the LMP1 promoter (LMP1p) contains an interferon-stimulated response element (ISRE), we hypothesized that IRF7 might be able to regulate LMP1 expression and thus participate in a regulatory circuit between these two genes. In this study, IRF7 was shown first to activate LMP1p in transient transfection assays. Compared with EBV nuclear antigen 2 (EBNA2), the most potent viral transactivator of LMP1p, IRF7 has a lesser effect (approximately 10% that of EBNA2) on induction of LMP1p. Study with IRF7 deletion mutants showed that IRF7 functional domains have similar effects on both the beta interferon (IFN-beta) and LMP1 promoters in BJAB and 293 cells, and study with IRF7 phosphomimetic mutants showed that IRF7 phosphorylation may be involved in the activation of these two promoters. Further, the ISRE in LMP1p responds to IRF7 induction and IRF7 binds to this element. In the EBV-positive cell line P3HR1, which lacks the complete EBNA2 and EBV-encoded leader protein genes and hence expresses low-level LMP1, IRF7 alone can notably increase the endogenous LMP1 mRNA and protein levels. These results indicate that LMP1 is regulated by this host cell gene in addition to the viral factor, EBNA2, and may help to explain how LMP1 is expressed in type II latency in the absence of EBNA2. Moreover, IRF7 can regulate a viral gene in addition to a host cellular gene such as the IFN-beta gene. Together with the previous data that LMP1 can induce IRF7 expression and facilitate IRF7 phosphorylation and nuclear translocation, these results suggest a positive regulatory circuit between IRF7 and LMP1.
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Affiliation(s)
- Shunbin Ning
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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Barth S, Liss M, Voss MD, Dobner T, Fischer U, Meister G, Grässer FA. Epstein-Barr virus nuclear antigen 2 binds via its methylated arginine-glycine repeat to the survival motor neuron protein. J Virol 2003; 77:5008-13. [PMID: 12663808 PMCID: PMC152127 DOI: 10.1128/jvi.77.8.5008-5013.2003] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Here we provide evidence that EBNA2 is methylated in vivo and that methylation of EBNA2 is a prerequisite for binding to SMN. We present SMN as a novel binding partner of EBNA2 by showing that EBNA2 colocalizes with SMN in nuclear gems and that both proteins can be coimmunoprecipitated from cellular extract. Furthermore, in vitro methylation of either wild-type EBNA2 or a glutathione S-transferase-EBNA2 fusion protein encompassing the arginine-glycine (RG) repeat element is necessary for in vitro binding to the Tudor domain of SMN. The recently shown functional cooperation of SMN and EBNA2 in transcriptional activation and the previous observation of a severely reduced transformation potential yet strongly enhanced transcriptional activity of an EBNA2 mutant lacking the RG repeat indicate that binding of SMN to EBNA2 is a critical step in B-cell transformation by Epstein-Barr virus.
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Affiliation(s)
- Stephanie Barth
- Institut für Medizinische Mikrobiologie und Hygiene, Abteilung Virologie, Universitätskliniken des Saarlandes, 66421 Homburg/Saar, Germany
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Yan X, Mouillet JF, Ou Q, Sadovsky Y. A novel domain within the DEAD-box protein DP103 is essential for transcriptional repression and helicase activity. Mol Cell Biol 2003; 23:414-23. [PMID: 12482992 PMCID: PMC140651 DOI: 10.1128/mcb.23.1.414-423.2003] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Members of the DEAD-box family of helicases, distinguished by a core characteristic sequence of Asp-Glu-Ala-Asp, are expressed in a wide range of prokaryotes and eukaryotes and exhibit diverse cellular functions, including DNA transcription, recombination and repair, RNA processing, translation, and posttranslational regulation. Although ubiquitous, the function of most DEAD-box proteins is unknown. We and others have recently cloned DP103, which harbors conserved DEAD-box, helicase, and ATPase domains in its N terminus. DP103 (also termed Gemin3 and DDX20) interacts with SF-1, SMN, EBNA2, and EBNA3C in mammalian cells. Here we demonstrate that a discrete domain within the nonconserved C-terminal region of DP103 directly interacts with SF-1. This domain exhibits an autonomous repression function and is necessary and sufficient for repressing the transcriptional activity of SF-1. Furthermore, intact DP103 exhibits helicase activity. Importantly, the C-terminal domain is obligatory but not sufficient for this unwinding activity of DP103. Together, our results support a novel paradigm for transcriptional repression and demonstrate the bifunctional role of the C-terminal domain of DP103.
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Affiliation(s)
- Xiaomei Yan
- Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Jablonka S, Holtmann B, Meister G, Bandilla M, Rossoll W, Fischer U, Sendtner M. Gene targeting of Gemin2 in mice reveals a correlation between defects in the biogenesis of U snRNPs and motoneuron cell death. Proc Natl Acad Sci U S A 2002; 99:10126-31. [PMID: 12091709 PMCID: PMC126635 DOI: 10.1073/pnas.152318699] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Neuronal degeneration in spinal muscular atrophy is caused by reduced expression of the survival motor neuron (SMN) protein. SMN and the tightly interacting Gemin2 form part of a macromolecular complex (SMN complex) that mediates assembly of spliceosomal small nuclear ribonucleoproteins (U snRNPs). We used mouse genetics to investigate the function of this complex in motoneuron maintenance. Reduced Smn/Gemin2 protein levels lead to disturbed U snRNP assembly as indicated by reduced nuclear accumulation of Sm proteins. This finding correlates with enhanced motoneuron degeneration in Gemin2(+/-)/Smn(+/-) mice. Our data provide in vivo evidence that impaired production of U snRNPs contributes to motoneuron degeneration.
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Affiliation(s)
- Sibylle Jablonka
- Institute of Clinical Neurobiology, Josef-Schneider Strasse 11, D-97080 Würzburg, Germany
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Young PJ, Jensen KT, Burger LR, Pintel DJ, Lorson CL. Minute virus of mice small nonstructural protein NS2 interacts and colocalizes with the Smn protein. J Virol 2002; 76:6364-9. [PMID: 12021369 PMCID: PMC136193 DOI: 10.1128/jvi.76.12.6364-6369.2002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The small nonstructural protein NS2 of the minute virus of mice (MVM) is required for efficient viral replication, although its mode of action is unclear. Here we demonstrate that NS2 and survival motor neuron protein (Smn) interact in vitro and in vivo. NS2 and Smn also colocalize in infected nuclei at late times following MVM infection.
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Affiliation(s)
- Philip J Young
- Department of Biology, Arizona State University, Tempe, Arizona 85287, USA
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Hille A, Badu-Antwi A, Holzer D, Grässer FA. Lysine residues of Epstein-Barr virus-encoded nuclear antigen 2 do not confer secondary modifications via ubiquitin or SUMO-like proteins but modulate transcriptional activation. J Gen Virol 2002; 83:1037-1042. [PMID: 11961257 DOI: 10.1099/0022-1317-83-5-1037] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Epstein-Barr virus nuclear antigen 2 (EBNA2) is essential for transformation through activation of viral and cellular genes. Within 487 residues, EBNA2 contains six lysine (K) residues (positions 335, 357, 359, 363, 366 and 480), which were mutated to arginine (R) residues, either individually or in combination, and tested for subcellular localization, mobility by SDS-PAGE and transactivation of three promoters. All mutants featuring the K(480)R mutation within the nuclear localization signal were partially cytoplasmic with a reduced level of transactivation of the latent membrane protein 1 (LMP1) promoter (-327 to +40). The K(366)R mutation also showed a decrease in transactivation of a promoter consisting only of 12 recombination signal-binding protein-Jkappa-binding sites, while all mutants with the K(335)R exchange showed a markedly elevated transactivation with the -327 to +40 construct and all mutants showed slightly reduced transactivation with a -634 to +40 LMP1 promoter. None of the mutants exhibited altered migration in SDS-PAGE, excluding secondary modification, i.e. through SUMO-like proteins.
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Affiliation(s)
- Annette Hille
- Institut für Mikrobiologie und Hygiene, Abteilung Virologie, Haus 47, Universitätskliniken, 66421 Homburg/Saar, Germany1
| | - Akua Badu-Antwi
- Institut für Mikrobiologie und Hygiene, Abteilung Virologie, Haus 47, Universitätskliniken, 66421 Homburg/Saar, Germany1
| | - Daniela Holzer
- Institut für Mikrobiologie und Hygiene, Abteilung Virologie, Haus 47, Universitätskliniken, 66421 Homburg/Saar, Germany1
| | - Friedrich A Grässer
- Institut für Mikrobiologie und Hygiene, Abteilung Virologie, Haus 47, Universitätskliniken, 66421 Homburg/Saar, Germany1
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