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A p53-independent apoptotic mechanism of adenoviral mutant E1A was involved in its selective antitumor activity for human cancer. Oncotarget 2018; 7:48309-48320. [PMID: 27340782 PMCID: PMC5217019 DOI: 10.18632/oncotarget.10221] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 06/06/2016] [Indexed: 11/25/2022] Open
Abstract
The conserved regions (CR) of adenoviral E1A had been shown to be necessary for disruption of pRb-E2F transcription factor complexes and induction of the S phase. Here we constructed a mutant adenoviral E1A with Rb-binding ability absent (E1A 30-60aa and 120-127aa deletion, mE1A) and investigated its antitumor capacities in vitro and in vivo. The mE1A suppressed the viability of tumor cells as efficiently as the wild type E1A, and there was no cytotoxic effect on normal cells. Although the mE1A arrested tumor cell cycle with the same manner as E1A, the former played a different role on cell cycle regulation compared with E1A in normal cells, which might contribute to its selective antitumor activity. E1A and mE1A had accumulated inactive p53, decreased the expression of mdm2, Cdkn1a (also named p21), increased p21's nuclear distribution and induced tumor cell apoptosis in a p53-indenpent manner. Further, E1A or mE1A significantly suppressed tumor growth in subcutaneous hepatocellular carcinoma xenograft models. Especially, tumor-bearing mice treated with mE1A had higher survival rate than those treated with E1A. Our data demonstrated that mutant adenoviral E1A significantly induced tumor cell apoptosis in a p53-indenpednt manner and had selective tumor suppressing ability. The observations of adenoviral E1A mutant had provided a novel mechanism for E1A's complex activities during infection.
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MERS-CoV and H5N1 influenza virus antagonize antigen presentation by altering the epigenetic landscape. Proc Natl Acad Sci U S A 2018; 115:E1012-E1021. [PMID: 29339515 PMCID: PMC5798318 DOI: 10.1073/pnas.1706928115] [Citation(s) in RCA: 120] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Convergent evolution dictates that diverse groups of viruses will target both similar and distinct host pathways to manipulate the immune response and improve infection. In this study, we sought to leverage this uneven viral antagonism to identify critical host factors that govern disease outcome. Utilizing a systems-based approach, we examined differential regulation of IFN-γ-dependent genes following infection with robust respiratory viruses including influenza viruses [A/influenza/Vietnam/1203/2004 (H5N1-VN1203) and A/influenza/California/04/2009 (H1N1-CA04)] and coronaviruses [severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome CoV (MERS-CoV)]. Categorizing by function, we observed down-regulation of gene expression associated with antigen presentation following both H5N1-VN1203 and MERS-CoV infection. Further examination revealed global down-regulation of antigen-presentation gene expression, which was confirmed by proteomics for both H5N1-VN1203 and MERS-CoV infection. Importantly, epigenetic analysis suggested that DNA methylation, rather than histone modification, plays a crucial role in MERS-CoV-mediated antagonism of antigen-presentation gene expression; in contrast, H5N1-VN1203 likely utilizes a combination of epigenetic mechanisms to target antigen presentation. Together, the results indicate a common mechanism utilized by H5N1-VN1203 and MERS-CoV to modulate antigen presentation and the host adaptive immune response.
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53
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Nagendraprabhu P, Khatiwada S, Chaulagain S, Delhon G, Rock DL. A parapoxviral virion protein targets the retinoblastoma protein to inhibit NF-κB signaling. PLoS Pathog 2017; 13:e1006779. [PMID: 29244863 PMCID: PMC5747488 DOI: 10.1371/journal.ppat.1006779] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 12/29/2017] [Accepted: 11/28/2017] [Indexed: 12/14/2022] Open
Abstract
Poxviruses have evolved multiple strategies to subvert signaling by Nuclear Factor κB (NF-κB), a crucial regulator of host innate immune responses. Here, we describe an orf virus (ORFV) virion-associated protein, ORFV119, which inhibits NF-κB signaling very early in infection (≤ 30 min post infection). ORFV119 NF-κB inhibitory activity was found unimpaired upon translation inhibition, suggesting that virion ORFV119 alone is responsible for early interference in signaling. A C-terminal LxCxE motif in ORFV119 enabled the protein to interact with the retinoblastoma protein (pRb) a multifunctional protein best known for its tumor suppressor activity. Notably, experiments using a recombinant virus containing an ORFV119 mutation which abrogates its interaction with pRb together with experiments performed in cells lacking or with reduced pRb levels indicate that ORFV119 mediated inhibition of NF-κB signaling is largely pRb dependent. ORFV119 was shown to inhibit IKK complex activation early in infection. Consistent with IKK inhibition, ORFV119 also interacted with TNF receptor associated factor 2 (TRAF2), an adaptor protein recruited to signaling complexes upstream of IKK in infected cells. ORFV119-TRAF2 interaction was enhanced in the presence of pRb, suggesting that ORFV119-pRb complex is required for efficient interaction with TRAF2. Additionally, transient expression of ORFV119 in uninfected cells was sufficient to inhibit TNFα-induced IKK activation and NF-κB signaling, indicating that no other viral proteins are required for the effect. Infection of sheep with ORFV lacking the ORFV119 gene led to attenuated disease phenotype, indicating that ORFV119 contributes to virulence in the natural host. ORFV119 represents the first poxviral protein to interfere with NF-κB signaling through interaction with pRb.
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Affiliation(s)
- Ponnuraj Nagendraprabhu
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana- Champaign, Urbana, IL, United States of America
| | - Sushil Khatiwada
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana- Champaign, Urbana, IL, United States of America
| | - Sabal Chaulagain
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana- Champaign, Urbana, IL, United States of America
| | - Gustavo Delhon
- School of Veterinary and Biomedical Sciences, Center for Virology, University of Nebraska-Lincoln, Lincoln, NE, United States of America
- * E-mail: (GD); (DLR)
| | - Daniel L. Rock
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana- Champaign, Urbana, IL, United States of America
- * E-mail: (GD); (DLR)
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Zemke NR, Berk AJ. The Adenovirus E1A C Terminus Suppresses a Delayed Antiviral Response and Modulates RAS Signaling. Cell Host Microbe 2017; 22:789-800.e5. [PMID: 29241042 PMCID: PMC5736016 DOI: 10.1016/j.chom.2017.11.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 08/01/2017] [Accepted: 11/17/2017] [Indexed: 01/22/2023]
Abstract
The N-terminal half of adenovirus e1a assembles multimeric complexes with host proteins that repress innate immune responses and force host cells into S-phase. In contrast, the functions of e1a's C-terminal interactions with FOXK, DCAF7, and CtBP are unknown. We found that these interactions modulate RAS signaling, and that a single e1a molecule must bind all three of these host proteins to suppress activation of a subset of IFN-stimulated genes (ISGs). These ISGs were otherwise induced in primary respiratory epithelial cells at 12 hr p.i. This delayed activation of ISGs required IRF3 and coincided with an ∼10-fold increase in IRF3 from protein stabilization. The induced IRF3 bound to chromatin and localized to the promoters of activated ISGs. While IRF3, STAT1/2, and IRF9 all greatly increased in concentration, there were no corresponding mRNA increases, suggesting that e1a regulates the stabilities of these key activators of innate immune responses, as shown directly for IRF3.
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Affiliation(s)
- Nathan R Zemke
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095-1570, USA
| | - Arnold J Berk
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095-1570, USA; Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095-1570, USA.
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The E1B19K-deleted oncolytic adenovirus mutant AdΔ19K sensitizes pancreatic cancer cells to drug-induced DNA-damage by down-regulating Claspin and Mre11. Oncotarget 2017; 7:15703-24. [PMID: 26872382 PMCID: PMC4941271 DOI: 10.18632/oncotarget.7310] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 01/27/2016] [Indexed: 11/25/2022] Open
Abstract
Adenovirus-mediated sensitization of cancer cells to cytotoxic drugs depends on simultaneous interactions of early viral genes with cell death and survival pathways. It is unclear what cellular factors mediate these interactions in the presence of DNA-damaging drugs. We found that adenovirus prevents Chk1-mediated checkpoint activation through inactivation of Mre11 and downregulation of the pChk1 adaptor-protein, Claspin, in cells with high levels of DNA-damage induced by the cytotoxic drugs gemcitabine and irinotecan. The mechanisms for Claspin downregulation involve decreased transcription and increased degradation, further attenuating pChk1-mediated signalling. Live cell imaging demonstrated that low doses of gemcitabine caused multiple mitotic aberrations including multipolar spindles, micro- and multi-nucleation and cytokinesis failure. A mutant virus with the anti-apoptotic E1B19K-gene deleted (AdΔ19K) further enhanced cell killing, Claspin downregulation, and potentiated drug-induced DNA damage and mitotic aberrations. Decreased Claspin expression and inactivation of Mre11 contributed to the enhanced cell killing in combination with DNA-damaging drugs. These results reveal novel mechanisms that are utilised by adenovirus to ensure completion of its life cycle in the presence of cellular DNA damage. Taken together, our findings reveal novel cellular targets that may be exploited when developing improved anti-cancer therapeutics.
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56
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Balakrishnan L, Milavetz B. Epigenetic Regulation of Viral Biological Processes. Viruses 2017; 9:v9110346. [PMID: 29149060 PMCID: PMC5707553 DOI: 10.3390/v9110346] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 11/13/2017] [Accepted: 11/15/2017] [Indexed: 12/21/2022] Open
Abstract
It is increasingly clear that DNA viruses exploit cellular epigenetic processes to control their life cycles during infection. This review will address epigenetic regulation in members of the polyomaviruses, adenoviruses, human papillomaviruses, hepatitis B, and herpes viruses. For each type of virus, what is known about the roles of DNA methylation, histone modifications, nucleosome positioning, and regulatory RNA in epigenetic regulation of the virus infection will be discussed. The mechanisms used by certain viruses to dysregulate the host cell through manipulation of epigenetic processes and the role of cellular cofactors such as BRD4 that are known to be involved in epigenetic regulation of host cell pathways will also be covered. Specifically, this review will focus on the role of epigenetic regulation in maintaining viral episomes through the generation of chromatin, temporally controlling transcription from viral genes during the course of an infection, regulating latency and the switch to a lytic infection, and global dysregulation of cellular function.
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Affiliation(s)
- Lata Balakrishnan
- Department of Biology, Indiana University Purdue University Indianapolis, Indianapolis, IN 46202, USA.
| | - Barry Milavetz
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58203, USA.
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Avgousti DC, Della Fera AN, Otter CJ, Herrmann C, Pancholi NJ, Weitzman MD. Adenovirus Core Protein VII Downregulates the DNA Damage Response on the Host Genome. J Virol 2017; 91:e01089-17. [PMID: 28794020 PMCID: PMC5625504 DOI: 10.1128/jvi.01089-17] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 08/01/2017] [Indexed: 11/20/2022] Open
Abstract
Viral manipulation of cellular proteins allows viruses to suppress host defenses and generate infectious progeny. Due to the linear double-stranded DNA nature of the adenovirus genome, the cellular DNA damage response (DDR) is considered a barrier to successful infection. The adenovirus genome is packaged with protein VII, a virally encoded histone-like core protein that is suggested to protect incoming viral genomes from detection by the cellular DNA damage machinery. We showed that protein VII localizes to host chromatin during infection, leading us to hypothesize that protein VII may affect DNA damage responses on the cellular genome. Here we show that protein VII at cellular chromatin results in a significant decrease in accumulation of phosphorylated H2AX (γH2AX) following irradiation, indicating that protein VII inhibits DDR signaling. The oncoprotein SET was recently suggested to modulate the DDR by affecting access of repair proteins to chromatin. Since protein VII binds SET, we investigated a role for SET in DDR inhibition by protein VII. We show that knockdown of SET partially rescues the protein VII-induced decrease in γH2AX accumulation on the host genome, suggesting that SET is required for inhibition. Finally, we show that knockdown of SET also allows ATM to localize to incoming viral genomes bound by protein VII during infection with a mutant lacking early region E4. Together, our data suggest that the protein VII-SET interaction contributes to DDR evasion by adenovirus. Our results provide an additional example of a strategy used by adenovirus to abrogate the host DDR and show how viruses can modify cellular processes through manipulation of host chromatin.IMPORTANCE The DNA damage response (DDR) is a cellular network that is crucial for maintaining genome integrity. DNA viruses replicating in the nucleus challenge the resident genome and must overcome cellular responses, including the DDR. Adenoviruses are prevalent human pathogens that can cause a multitude of diseases, such as respiratory infections and conjunctivitis. Here we describe how a small adenovirus core protein that localizes to host chromatin during infection can globally downregulate the DDR. Our study focuses on key players in the damage signaling pathway and highlights how viral manipulation of chromatin may influence access of DDR proteins to the host genome.
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Affiliation(s)
- Daphne C Avgousti
- Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
- Division of Protective Immunity and Division of Cancer Pathobiology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Ashley N Della Fera
- Division of Protective Immunity and Division of Cancer Pathobiology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Clayton J Otter
- Division of Protective Immunity and Division of Cancer Pathobiology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Christin Herrmann
- Division of Protective Immunity and Division of Cancer Pathobiology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
- Cell and Molecular Biology Graduate Group, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Neha J Pancholi
- Division of Protective Immunity and Division of Cancer Pathobiology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
- Cell and Molecular Biology Graduate Group, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Matthew D Weitzman
- Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
- Division of Protective Immunity and Division of Cancer Pathobiology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
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58
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Kitajima S, Takahashi C. Intersection of retinoblastoma tumor suppressor function, stem cells, metabolism, and inflammation. Cancer Sci 2017; 108:1726-1731. [PMID: 28865172 PMCID: PMC5581511 DOI: 10.1111/cas.13312] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 06/28/2017] [Accepted: 06/30/2017] [Indexed: 12/27/2022] Open
Abstract
The Retinoblastoma (RB) tumor suppressor regulates G1/S transition during cell cycle progression by modulating the activity of E2F transcription factors. The RB pathway plays a central role in the suppression of most cancers, and RB mutation was initially discovered by virtue of its role in tumor initiation. However, as cancer genome sequencing has evolved to profile more advanced and treatment‐resistant cancers, it has become increasingly clear that, in the majority of cancers, somatic RB inactivation occurs during tumor progression. Furthermore, despite the presence of deregulation of cell cycle control due to an INK4A deletion, additional CCND amplification and/or other mutations in the RB pathway, mutation or deletion of the RB gene is often observed during cancer progression. Of note, RB inactivation during cancer progression not only facilitates G1/S transition but also enhances some characteristics of malignancy, including altered drug sensitivity and a return to the undifferentiated state. Recently, we reported that RB inactivation enhances pro‐inflammatory signaling through stimulation of the interleukin‐6/STAT3 pathway, which directly promotes various malignant features of cancer cells. In this review, we highlight the consequences of RB inactivation during cancer progression, and discuss the biological and pathological significance of the interaction between RB and pro‐inflammatory signaling.
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Affiliation(s)
- Shunsuke Kitajima
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
| | - Chiaki Takahashi
- Division of Oncology and Molecular Biology, Cancer Research Institute, Kanazawa University, Kanazawa, Ishikawa, Japan
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59
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Simultaneous Single-Cell In Situ Analysis of Human Adenovirus Type 5 DNA and mRNA Expression Patterns in Lytic and Persistent Infection. J Virol 2017; 91:JVI.00166-17. [PMID: 28298601 DOI: 10.1128/jvi.00166-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 03/06/2017] [Indexed: 12/14/2022] Open
Abstract
An efficient adenovirus infection results in high-level accumulation of viral DNA and mRNAs in the infected cell population. However, the average viral DNA and mRNA content in a heterogeneous cell population does not necessarily reflect the same abundance in individual cells. Here, we describe a novel padlock probe-based rolling-circle amplification technique that enables simultaneous detection and analysis of human adenovirus type 5 (HAdV-5) genomic DNA and virus-encoded mRNAs in individual infected cells. We demonstrate that the method is applicable for detection and quantification of HAdV-5 DNA and mRNAs in short-term infections in human epithelial cells and in long-term infections in human B lymphocytes. Single-cell evaluation of these infections revealed high heterogeneity and unique cell subpopulations defined by differential viral DNA content and mRNA expression. Further, our single-cell analysis shows that the specific expression pattern of viral E1A 13S and 12S mRNA splice variants is linked to HAdV-5 DNA content in the individual cells. Furthermore, we show that expression of a mature form of the HAdV-5 histone-like protein VII affects virus genome detection in HAdV-5-infected cells. Collectively, padlock probes combined with rolling-circle amplification should be a welcome addition to the method repertoire for the characterization of the molecular details of the HAdV life cycle in individual infected cells.IMPORTANCE Human adenoviruses (HAdVs) have been extensively used as model systems to study various aspects of eukaryotic gene expression and genome organization. The vast majority of the HAdV studies are based on standard experimental procedures carried out using heterogeneous cell populations, where data averaging often masks biological differences. As every cell is unique, characteristics and efficiency of an HAdV infection can vary from cell to cell. Therefore, the analysis of HAdV gene expression and genome organization would benefit from a method that permits analysis of individual infected cells in the heterogeneous cell population. Here, we show that the padlock probe-based rolling-circle amplification method can be used to study concurrent viral DNA accumulation and mRNA expression patterns in individual HAdV-5-infected cells. Hence, this versatile method can be applied to detect the extent of infection and virus gene expression changes in different HAdV-5 infections.
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60
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Abstract
In this review, Dyson summarizes some recent developments in pRB research and focuses on progress toward answers for the three fundamental questions that sit at the heart of the pRB literature: What does pRB do? How does the inactivation of RB change the cell? How can our knowledge of RB function be exploited to provide better treatment for cancer patients? The retinoblastoma susceptibility gene (RB1) was the first tumor suppressor gene to be molecularly defined. RB1 mutations occur in almost all familial and sporadic forms of retinoblastoma, and this gene is mutated at variable frequencies in a variety of other human cancers. Because of its early discovery, the recessive nature of RB1 mutations, and its frequency of inactivation, RB1 is often described as a prototype for the class of tumor suppressor genes. Its gene product (pRB) regulates transcription and is a negative regulator of cell proliferation. Although these general features are well established, a precise description of pRB's mechanism of action has remained elusive. Indeed, in many regards, pRB remains an enigma. This review summarizes some recent developments in pRB research and focuses on progress toward answers for the three fundamental questions that sit at the heart of the pRB literature: What does pRB do? How does the inactivation of RB change the cell? How can our knowledge of RB function be exploited to provide better treatment for cancer patients?
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61
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Yoo SY, Badrinath N, Woo HY, Heo J. Oncolytic Virus-Based Immunotherapies for Hepatocellular Carcinoma. Mediators Inflamm 2017; 2017:5198798. [PMID: 28512387 PMCID: PMC5415860 DOI: 10.1155/2017/5198798] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 03/08/2017] [Indexed: 02/07/2023] Open
Abstract
Hepatocellular carcinoma is highly refractory cancer which is resistant to conventional chemotherapy and radiotherapy, carrying a dismal prognosis. Although many anticancer drugs have been developed for treating HCC, sorafenib is the only effective treatment, but it only prolongs survival duration for about 3 months. Recently, oncolytic virotherapy has shown promising results in treating HCCs and the effects can be more enhanced by adopting immune modulatory molecules. This review discusses the current status of treating HCC and the effective strategy of oncolytic virus-based immunotherapy for the treatment of HCCs.
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Affiliation(s)
- So Young Yoo
- BIO-IT Foundry Technology Institute, Pusan National University, Busan 46241, Republic of Korea
- Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan 50612, Republic of Korea
- Department of Internal Medicine, College of Medicine, Pusan National University and Medical Research Institute, Yangsan 50612, Republic of Korea
- Biomedical Research Institute, Pusan National University Hospital, Busan 49241, Republic of Korea
| | - Narayanasamy Badrinath
- BIO-IT Foundry Technology Institute, Pusan National University, Busan 46241, Republic of Korea
- Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan 50612, Republic of Korea
| | - Hyun Young Woo
- Department of Internal Medicine, College of Medicine, Pusan National University and Medical Research Institute, Yangsan 50612, Republic of Korea
- Biomedical Research Institute, Pusan National University Hospital, Busan 49241, Republic of Korea
| | - Jeong Heo
- Department of Internal Medicine, College of Medicine, Pusan National University and Medical Research Institute, Yangsan 50612, Republic of Korea
- Biomedical Research Institute, Pusan National University Hospital, Busan 49241, Republic of Korea
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62
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Attar N, Kurdistani SK. Exploitation of EP300 and CREBBP Lysine Acetyltransferases by Cancer. Cold Spring Harb Perspect Med 2017; 7:cshperspect.a026534. [PMID: 27881443 DOI: 10.1101/cshperspect.a026534] [Citation(s) in RCA: 137] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
p300 and CREB-binding protein (CBP), two homologous lysine acetyltransferases in metazoans, have a myriad of cellular functions. They exert their influence mainly through their roles as transcriptional regulators but also via nontranscriptional effects inside and outside of the nucleus on processes such as DNA replication and metabolism. The versatility of p300/CBP as molecular tools has led to their exploitation by viral oncogenes for cellular transformation and by cancer cells to achieve and maintain an oncogenic phenotype. How cancer cells use p300/CBP in their favor varies depending on the cellular context and is evident by the growing list of loss- and gain-of-function genetic alterations in p300 and CBP in solid tumors and hematological malignancies. Here, we discuss the biological functions of p300/CBP and how disruption of these functions by mutations and alterations in expression or subcellular localization contributes to the cancer phenotype.
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Affiliation(s)
- Narsis Attar
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, California 90095.,Molecular Biology Institute, David Geffen School of Medicine, University of California, Los Angeles, California 90095
| | - Siavash K Kurdistani
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, California 90095.,Molecular Biology Institute, David Geffen School of Medicine, University of California, Los Angeles, California 90095.,Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, California 90095.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine, University of California, Los Angeles, California 90095
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63
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Ishak CA, Marshall AE, Passos DT, White CR, Kim SJ, Cecchini MJ, Ferwati S, MacDonald WA, Howlett CJ, Welch ID, Rubin SM, Mann MRW, Dick FA. An RB-EZH2 Complex Mediates Silencing of Repetitive DNA Sequences. Mol Cell 2016; 64:1074-1087. [PMID: 27889452 DOI: 10.1016/j.molcel.2016.10.021] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 08/17/2016] [Accepted: 10/17/2016] [Indexed: 12/21/2022]
Abstract
Repetitive genomic regions include tandem sequence repeats and interspersed repeats, such as endogenous retroviruses and LINE-1 elements. Repressive heterochromatin domains silence expression of these sequences through mechanisms that remain poorly understood. Here, we present evidence that the retinoblastoma protein (pRB) utilizes a cell-cycle-independent interaction with E2F1 to recruit enhancer of zeste homolog 2 (EZH2) to diverse repeat sequences. These include simple repeats, satellites, LINEs, and endogenous retroviruses as well as transposon fragments. We generated a mutant mouse strain carrying an F832A mutation in Rb1 that is defective for recruitment to repetitive sequences. Loss of pRB-EZH2 complexes from repeats disperses H3K27me3 from these genomic locations and permits repeat expression. Consistent with maintenance of H3K27me3 at the Hox clusters, these mice are developmentally normal. However, susceptibility to lymphoma suggests that pRB-EZH2 recruitment to repetitive elements may be cancer relevant.
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Affiliation(s)
- Charles A Ishak
- London Regional Cancer Program, London, ON N6A 4L6, Canada; Department of Biochemistry, Western University, London, ON N6A 3K7, Canada
| | - Aren E Marshall
- London Regional Cancer Program, London, ON N6A 4L6, Canada; Department of Biochemistry, Western University, London, ON N6A 3K7, Canada
| | - Daniel T Passos
- London Regional Cancer Program, London, ON N6A 4L6, Canada; Department of Biochemistry, Western University, London, ON N6A 3K7, Canada
| | - Carlee R White
- Children's Health Research Institute, London, ON N6A 4L6, Canada; Department of Biochemistry, Western University, London, ON N6A 3K7, Canada
| | - Seung J Kim
- London Regional Cancer Program, London, ON N6A 4L6, Canada; Department of Biochemistry, Western University, London, ON N6A 3K7, Canada
| | - Matthew J Cecchini
- London Regional Cancer Program, London, ON N6A 4L6, Canada; Department of Pathology and Laboratory Medicine, Western University, London, ON N6A 3K7, Canada
| | - Sara Ferwati
- London Regional Cancer Program, London, ON N6A 4L6, Canada; Department of Biochemistry, Western University, London, ON N6A 3K7, Canada
| | - William A MacDonald
- Magee-Womens Research Institute, Pittsburgh, PA 15213, USA; Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Christopher J Howlett
- Department of Pathology and Laboratory Medicine, Western University, London, ON N6A 3K7, Canada
| | - Ian D Welch
- Animal Care Services, University of British Columbia, Vancouver, BC V6T1Z4, Canada
| | - Seth M Rubin
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Mellissa R W Mann
- Magee-Womens Research Institute, Pittsburgh, PA 15213, USA; Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Frederick A Dick
- London Regional Cancer Program, London, ON N6A 4L6, Canada; Children's Health Research Institute, London, ON N6A 4L6, Canada; Department of Biochemistry, Western University, London, ON N6A 3K7, Canada.
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64
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Muñoz-Fontela C, Mandinova A, Aaronson SA, Lee SW. Emerging roles of p53 and other tumour-suppressor genes in immune regulation. Nat Rev Immunol 2016; 16:741-750. [PMID: 27667712 DOI: 10.1038/nri.2016.99] [Citation(s) in RCA: 244] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Tumour-suppressor genes are indispensable for the maintenance of genomic integrity. Recently, several of these genes, including those encoding p53, PTEN, RB1 and ARF, have been implicated in immune responses and inflammatory diseases. In particular, the p53 tumour- suppressor pathway is involved in crucial aspects of tumour immunology and in homeostatic regulation of immune responses. Other studies have identified roles for p53 in various cellular processes, including metabolism and stem cell maintenance. Here, we discuss the emerging roles of p53 and other tumour-suppressor genes in tumour immunology, as well as in additional immunological settings, such as virus infection. This relatively unexplored area could yield important insights into the homeostatic control of immune cells in health and disease and facilitate the development of more effective immunotherapies. Consequently, tumour-suppressor genes are emerging as potential guardians of immune integrity.
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Affiliation(s)
- César Muñoz-Fontela
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Martinistrasse 52, 20251 Hamburg, Germany
| | - Anna Mandinova
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Building 149 13th Street, Charlestown, Massachusetts 02129, USA.,Harvard Stem Cell Institute, 7 Divinity Avenue, Cambridge, Massachusetts 02138, USA.,Broad Institute of Harvard and MIT, 7 Cambridge Center, Cambridge, Massachusetts 02142, USA
| | - Stuart A Aaronson
- Department of Oncological Sciences, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, New York 10029, USA
| | - Sam W Lee
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Building 149 13th Street, Charlestown, Massachusetts 02129, USA.,Broad Institute of Harvard and MIT, 7 Cambridge Center, Cambridge, Massachusetts 02142, USA
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65
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Crow MS, Lum KK, Sheng X, Song B, Cristea IM. Diverse mechanisms evolved by DNA viruses to inhibit early host defenses. Crit Rev Biochem Mol Biol 2016; 51:452-481. [PMID: 27650455 PMCID: PMC5285405 DOI: 10.1080/10409238.2016.1226250] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
In mammalian cells, early defenses against infection by pathogens are mounted through a complex network of signaling pathways shepherded by immune-modulatory pattern-recognition receptors. As obligate parasites, the survival of viruses is dependent on the evolutionary acquisition of mechanisms that tactfully dismantle and subvert the cellular intrinsic and innate immune responses. Here, we review the diverse mechanisms by which viruses that accommodate DNA genomes are able to circumvent activation of cellular immunity. We start by discussing viral manipulation of host defense protein levels by either transcriptional regulation or protein degradation. We next review viral strategies used to repurpose or inhibit these cellular immune factors by molecular hijacking or by regulating their post-translational modification status. Additionally, we explore the infection-induced temporal modulation of apoptosis to facilitate viral replication and spread. Lastly, the co-evolution of viruses with their hosts is highlighted by the acquisition of elegant mechanisms for suppressing host defenses via viral mimicry of host factors. In closing, we present a perspective on how characterizing these viral evasion tactics both broadens the understanding of virus-host interactions and reveals essential functions of the immune system at the molecular level. This knowledge is critical in understanding the sources of viral pathogenesis, as well as for the design of antiviral therapeutics and autoimmunity treatments.
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Affiliation(s)
- Marni S. Crow
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544
| | - Krystal K. Lum
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544
| | - Xinlei Sheng
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544
| | - Bokai Song
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544
| | - Ileana M. Cristea
- Department of Molecular Biology, Princeton University, Lewis Thomas Laboratory, Washington Road, Princeton, NJ 08544
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66
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Dutta R, Tiu B, Sakamoto KM. CBP/p300 acetyltransferase activity in hematologic malignancies. Mol Genet Metab 2016; 119:37-43. [PMID: 27380996 DOI: 10.1016/j.ymgme.2016.06.013] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 06/29/2016] [Accepted: 06/29/2016] [Indexed: 02/08/2023]
Abstract
CREB binding protein (CBP) and p300 are critical regulators of hematopoiesis through both their transcriptional coactivator and acetyltransferase activities. Loss or mutation of CBP/p300 results in hematologic deficiencies in proliferation and differentiation as well as disruption of hematopoietic stem cell renewal and the microenvironment. Aberrant lysine acetylation mediated by CBP/p300 has recently been implicated in the genesis of multiple hematologic cancers. Understanding the effects of disrupting the acetyltransferase activity of CBP/p300 could pave the way for new therapeutic approaches to treat patients with these diseases.
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Affiliation(s)
- Ritika Dutta
- Division of Hematology/Oncology, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA
| | - Bruce Tiu
- Division of Hematology/Oncology, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA
| | - Kathleen M Sakamoto
- Division of Hematology/Oncology, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA.
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67
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Avgousti DC, Herrmann C, Kulej K, Pancholi NJ, Sekulic N, Petrescu J, Molden RC, Blumenthal D, Paris AJ, Reyes ED, Ostapchuk P, Hearing P, Seeholzer SH, Worthen GS, Black BE, Garcia BA, Weitzman MD. A core viral protein binds host nucleosomes to sequester immune danger signals. Nature 2016; 535:173-7. [PMID: 27362237 PMCID: PMC4950998 DOI: 10.1038/nature18317] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 05/11/2016] [Indexed: 01/06/2023]
Abstract
Viral proteins mimic host protein structure and function to redirect cellular processes and subvert innate defenses. Small basic proteins compact and regulate both viral and cellular DNA genomes. Nucleosomes are the repeating units of cellular chromatin and play an important part in innate immune responses. Viral-encoded core basic proteins compact viral genomes, but their impact on host chromatin structure and function remains unexplored. Adenoviruses encode a highly basic protein called protein VII that resembles cellular histones. Although protein VII binds viral DNA and is incorporated with viral genomes into virus particles, it is unknown whether protein VII affects cellular chromatin. Here we show that protein VII alters cellular chromatin, leading us to hypothesize that this has an impact on antiviral responses during adenovirus infection in human cells. We find that protein VII forms complexes with nucleosomes and limits DNA accessibility. We identified post-translational modifications on protein VII that are responsible for chromatin localization. Furthermore, proteomic analysis demonstrated that protein VII is sufficient to alter the protein composition of host chromatin. We found that protein VII is necessary and sufficient for retention in the chromatin of members of the high-mobility-group protein B family (HMGB1, HMGB2 and HMGB3). HMGB1 is actively released in response to inflammatory stimuli and functions as a danger signal to activate immune responses. We showed that protein VII can directly bind HMGB1 in vitro and further demonstrated that protein VII expression in mouse lungs is sufficient to decrease inflammation-induced HMGB1 content and neutrophil recruitment in the bronchoalveolar lavage fluid. Together, our in vitro and in vivo results show that protein VII sequesters HMGB1 and can prevent its release. This study uncovers a viral strategy in which nucleosome binding is exploited to control extracellular immune signaling.
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Affiliation(s)
- Daphne C. Avgousti
- Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA
- Division of Cancer Pathobiology, Children's Hospital of Philadelphia, Philadelphia, PA USA
| | - Christin Herrmann
- Division of Cancer Pathobiology, Children's Hospital of Philadelphia, Philadelphia, PA USA
- Cell and Molecular Biology Graduate Group, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA
| | - Katarzyna Kulej
- Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA
- Division of Cancer Pathobiology, Children's Hospital of Philadelphia, Philadelphia, PA USA
| | - Neha J. Pancholi
- Division of Cancer Pathobiology, Children's Hospital of Philadelphia, Philadelphia, PA USA
- Cell and Molecular Biology Graduate Group, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA
| | - Nikolina Sekulic
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA
- Epigenetics Program, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA
- Currently: Biotechnology Centre of Oslo and Department of Chemistry, University of Oslo, Oslo, Norway
| | - Joana Petrescu
- Division of Cancer Pathobiology, Children's Hospital of Philadelphia, Philadelphia, PA USA
- Villanova University, Villanova, PA USA
| | - Rosalynn C. Molden
- Epigenetics Program, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA
| | - Daniel Blumenthal
- Division of Cell Pathology, Children's Hospital of Philadelphia, Philadelphia, PA USA
| | - Andrew J. Paris
- Division of Pulmonary, Allergy, and Critical Care Medicine, Hospital of the University of Pennsylvania, and the Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Emigdio D. Reyes
- Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA
- Division of Cancer Pathobiology, Children's Hospital of Philadelphia, Philadelphia, PA USA
| | - Philomena Ostapchuk
- Department of Molecular Genetics and Microbiology, School of Medicine, Stony Brook University, Stony Brook, New York USA
| | - Patrick Hearing
- Department of Molecular Genetics and Microbiology, School of Medicine, Stony Brook University, Stony Brook, New York USA
| | - Steven H. Seeholzer
- Protein and Proteomics Core, Children's Hospital of Philadelphia, Philadelphia, PA USA
| | - G. Scott Worthen
- Division of Neonatology, Children’s Hospital of Philadelphia, Philadelphia, and Department of Pediatrics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Ben E. Black
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA
- Epigenetics Program, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA
| | - Benjamin A. Garcia
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA
- Epigenetics Program, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA
| | - Matthew D. Weitzman
- Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA
- Division of Cancer Pathobiology, Children's Hospital of Philadelphia, Philadelphia, PA USA
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68
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Zhao LJ, Loewenstein PM, Green M. The adenoviral E1A N-terminal domain represses MYC transcription in human cancer cells by targeting both p300 and TRRAP and inhibiting MYC promoter acetylation of H3K18 and H4K16. Genes Cancer 2016; 7:98-109. [PMID: 27382434 PMCID: PMC4918948 DOI: 10.18632/genesandcancer.99] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Human cancers frequently arise from increased expression of proto-oncogenes, such as MYC and HER2. Understanding the cellular pathways regulating the transcription and expression of proto-oncogenes is important for targeted therapies for cancer treatment. Adenoviral (Ad) E1A 243R (243 aa residues) is a viral oncoprotein that interacts with key regulators of gene transcription and cell proliferation. We have shown previously that the 80 amino acid N-terminal transcriptional repression domain of E1A 243R (E1A 1-80) can target the histone acetyltransferase (HAT) p300 and repress HER2 in the HER2-overexpressing human breast cancer cell line SKBR3. Expression of E1A 1-80 induces death of SKBR3 and other cancer cell lines. In this study, we performed total cell RNA sequence analysis and identified MYC as the regulatory gene for cellular proliferation most strongly repressed by E1A 1-80. By RT-quantitative PCR analysis we show that repression of MYC in SKBR3 cells occurs early after expression of E1A 1-80, suggesting that MYC may be an early responder of E1A 1-80-mediated transcriptional repression. Of interest, while E1A 1-80 repression of MYC occurs in all eight human cancer cell lines examined, repression of HER2 is cell-type dependent. We demonstrate by ChIP analysis that MYC transcriptional repression by E1A 1-80 is associated with inhibition of acetylation of H3K18 and H4K16 on the MYC promoter, as well as inhibition of RNA Pol II binding to the MYC promoter. Deletion mutant analysis of E1A 1-80 suggests that both p300/CBP and TRRAP are involved in E1A 1-80 repression of MYC transcription. Further, E1A 1-80 interaction with p300/CBP and TRRAP is correlated with inhibition of H3K18 and H4K16 acetylation on the MYC promoter, respectively. Our results indicate that E1A 1-80 may target two important pathways for histone modification to repress transcription in human cancer cells.
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Affiliation(s)
- Ling-Jun Zhao
- Institute for Molecular Virology, Department of Microbiology and Molecular Immunology, Saint Louis University School of Medicine, Doisy Research Center, St. Louis, Missouri, USA
| | - Paul M Loewenstein
- Institute for Molecular Virology, Department of Microbiology and Molecular Immunology, Saint Louis University School of Medicine, Doisy Research Center, St. Louis, Missouri, USA
| | - Maurice Green
- Institute for Molecular Virology, Department of Microbiology and Molecular Immunology, Saint Louis University School of Medicine, Doisy Research Center, St. Louis, Missouri, USA
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69
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Pifer PM, Farris JC, Thomas AL, Stoilov P, Denvir J, Smith DM, Frisch SM. Grainyhead-like 2 inhibits the coactivator p300, suppressing tubulogenesis and the epithelial-mesenchymal transition. Mol Biol Cell 2016; 27:2479-92. [PMID: 27251061 PMCID: PMC4966987 DOI: 10.1091/mbc.e16-04-0249] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 05/27/2016] [Indexed: 11/17/2022] Open
Abstract
GRHL2 suppresses EMT to give a default epithelial phenotype. GRHL2 inhibits this process through the histone acetyltransferase coactivator p300, repressing the partial EMT and preventing induction of MMPs. The results demonstrate novel roles for p300 and GRHL2 in promoting or suppressing EMT in morphogenesis and tumor progression. Developmental morphogenesis and tumor progression require a transient or stable breakdown of epithelial junctional complexes to permit programmed migration, invasion, and anoikis resistance, characteristics endowed by the epithelial–mesenchymal transition (EMT). The epithelial master-regulatory transcription factor Grainyhead-like 2 (GRHL2) suppresses and reverses EMT, causing a mesenchymal–epithelial transition to the default epithelial phenotype. Here we investigated the role of GRHL2 in tubulogenesis of Madin–Darby canine kidney cells, a process requiring transient, partial EMT. GRHL2 was required for cystogenesis, but it suppressed tubulogenesis in response to hepatocyte growth factor. Surprisingly, GRHL2 suppressed this process by inhibiting the histone acetyltransferase coactivator p300, preventing the induction of matrix metalloproteases and other p300-dependent genes required for tubulogenesis. A 13–amino acid region of GRHL2 was necessary for inhibition of p300, suppression of tubulogenesis, and interference with EMT. The results demonstrate that p300 is required for partial or complete EMT occurring in tubulogenesis or tumor progression and that GRHL2 suppresses EMT in both contexts through inhibition of p300.
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Affiliation(s)
- Phillip M Pifer
- Mary Babb Randolph Cancer Center, West Virginia University, Morgantown, WV 26506
| | - Joshua C Farris
- Mary Babb Randolph Cancer Center, West Virginia University, Morgantown, WV 26506
| | - Alyssa L Thomas
- Mary Babb Randolph Cancer Center, West Virginia University, Morgantown, WV 26506
| | - Peter Stoilov
- Department of Biochemistry, West Virginia University, Morgantown, WV 26506
| | - James Denvir
- Department of Biochemistry and Microbiology, Marshall University, Huntington, WV 25755
| | - David M Smith
- Department of Biochemistry, West Virginia University, Morgantown, WV 26506
| | - Steven M Frisch
- Mary Babb Randolph Cancer Center, West Virginia University, Morgantown, WV 26506 Department of Biochemistry, West Virginia University, Morgantown, WV 26506
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70
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King CR, Cohen MJ, Fonseca GJ, Dirk BS, Dikeakos JD, Mymryk JS. Functional and Structural Mimicry of Cellular Protein Kinase A Anchoring Proteins by a Viral Oncoprotein. PLoS Pathog 2016; 12:e1005621. [PMID: 27137912 PMCID: PMC4854477 DOI: 10.1371/journal.ppat.1005621] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 04/19/2016] [Indexed: 11/18/2022] Open
Abstract
The oncoproteins of the small DNA tumor viruses interact with a plethora of cellular regulators to commandeer control of the infected cell. During infection, adenovirus E1A deregulates cAMP signalling and repurposes it for activation of viral gene expression. We show that E1A structurally and functionally mimics a cellular A-kinase anchoring protein (AKAP). E1A interacts with and relocalizes protein kinase A (PKA) to the nucleus, likely to virus replication centres, via an interaction with the regulatory subunits of PKA. Binding to PKA requires the N-terminus of E1A, which bears striking similarity to the amphipathic α-helical domain present in cellular AKAPs. E1A also targets the same docking-dimerization domain of PKA normally bound by cellular AKAPs. In addition, the AKAP like motif within E1A could restore PKA interaction to a cellular AKAP in which its normal interaction motif was deleted. During infection, E1A successfully competes with endogenous cellular AKAPs for PKA interaction. E1A's role as a viral AKAP contributes to viral transcription, protein expression and progeny production. These data establish HAdV E1A as the first known viral AKAP. This represents a unique example of viral subversion of a crucial cellular regulatory pathway via structural mimicry of the PKA interaction domain of cellular AKAPs.
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Affiliation(s)
- Cason R King
- Department of Microbiology & Immunology, University of Western Ontario, London, Ontario, Canada
| | - Michael J Cohen
- Department of Microbiology & Immunology, University of Western Ontario, London, Ontario, Canada
| | - Gregory J Fonseca
- Department of Microbiology & Immunology, University of Western Ontario, London, Ontario, Canada
| | - Brennan S Dirk
- Department of Microbiology & Immunology, University of Western Ontario, London, Ontario, Canada
| | - Jimmy D Dikeakos
- Department of Microbiology & Immunology, University of Western Ontario, London, Ontario, Canada
| | - Joe S Mymryk
- Department of Microbiology & Immunology, University of Western Ontario, London, Ontario, Canada.,Department of Oncology, University of Western Ontario, London, Ontario, Canada.,London Regional Cancer Program and Lawson Health Research Institute, London, Ontario, Canada
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71
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Shi S, Liu K, Chen Y, Zhang S, Lin J, Gong C, Jin Q, Yang XJ, Chen R, Ji Z, Han A. Competitive Inhibition of Lysine Acetyltransferase 2B by a Small Motif of the Adenoviral Oncoprotein E1A. J Biol Chem 2016; 291:14363-14372. [PMID: 27143356 DOI: 10.1074/jbc.m115.697300] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Indexed: 12/26/2022] Open
Abstract
The adenovirus early region 1A (E1A) oncoprotein hijacks host cells via direct interactions with many key cellular proteins, such as KAT2B, also known as PCAF (p300/CBP associated factor). E1A binds the histone acetyltransferase (HAT) domain of KAT2B to repress its transcriptional activation. However, the molecular mechanism by which E1A inhibits the HAT activity is not known. Here we demonstrate that a short and relatively conserved N-terminal motif (cNM) in the intrinsically disordered E1A protein is crucial for KAT2B interaction, and inhibits its HAT activity through a direct competition with acetyl-CoA, but not its substrate histone H3. Molecular modeling together with a series of mutagenesis experiments suggests that the major helix of E1A cNM binds to a surface of the acetyl-CoA pocket of the KAT2B HAT domain. Moreover, transient expression of the cNM peptide is sufficient to inhibit KAT2B-specific H3 acetylation H3K14ac in vivo Together, our data define an essential motif cNM in N-terminal E1A as an acetyl-CoA entry blocker that directly associates with the entrance of acetyl-CoA binding pocket to block the HAT domain access to its cofactor.
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Affiliation(s)
- Shasha Shi
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiang'an, Xiamen 361102, China
| | - Ke Liu
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiang'an, Xiamen 361102, China
| | - Yanheng Chen
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiang'an, Xiamen 361102, China
| | - Shijun Zhang
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiang'an, Xiamen 361102, China
| | - Juanyu Lin
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiang'an, Xiamen 361102, China
| | - Chenfang Gong
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiang'an, Xiamen 361102, China
| | - Quanwen Jin
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiang'an, Xiamen 361102, China
| | - Xiang-Jiao Yang
- Goodman Cancer Centre, McGill University, and Department of Medicine, McGill University Health Center, Montreal, Quebec H3A 1A3, Canada
| | - Ruichuan Chen
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiang'an, Xiamen 361102, China.
| | - Zhiliang Ji
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiang'an, Xiamen 361102, China.
| | - Aidong Han
- State Key Laboratory for Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiang'an, Xiamen 361102, China.
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72
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Tang Z, Yu W, Zhang C, Zhao S, Yu Z, Xiao X, Tang R, Xuan Y, Yang W, Hao J, Xu T, Zhang Q, Huang W, Deng W, Guo W. CREB-binding protein regulates lung cancer growth by targeting MAPK and CPSF4 signaling pathway. Mol Oncol 2016; 10:317-29. [PMID: 26628108 PMCID: PMC5528962 DOI: 10.1016/j.molonc.2015.10.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 10/19/2015] [Indexed: 12/14/2022] Open
Abstract
CBP (CREB-binding protein) is a transcriptional co-activator which possesses HAT (histone acetyltransferases) activity and participates in many biological processes, including embryonic development, growth control and homeostasis. However, its roles and the underlying mechanisms in the regulation of carcinogenesis and tumor development remain largely unknown. Here we investigated the molecular mechanisms and potential targets of CBP involved in tumor growth and survival in lung cancer cells. Elevated expression of CBP was detected in lung cancer cells and tumor tissues compared to the normal lung cells and tissues. Knockdown of CBP by siRNA or inhibition of its HAT activity using specific chemical inhibitor effectively suppressed cell proliferation, migration and colony formation and induced apoptosis in lung cancer cells by inhibiting MAPK and activating cytochrome C/caspase-dependent signaling pathways. Co-immunoprecipitation and immunofluorescence analyses revealed the co-localization and interaction between CBP and CPSF4 (cleavage and polyadenylation specific factor 4) proteins in lung cancer cells. Knockdown of CPSF4 inhibited hTERT transcription and cell growth induced by CBP, and vice versa, demonstrating the synergetic effect of CBP and CPSF4 in the regulation of lung cancer cell growth and survival. Moreover, we found that high expression of both CBP and CPSF4 predicted a poor prognosis in the patients with lung adenocarcinomas. Collectively, our results indicate that CBP regulates lung cancer growth by targeting MAPK and CPSF4 signaling pathways.
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Affiliation(s)
- Zhipeng Tang
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, China
| | - Wendan Yu
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, China
| | - Changlin Zhang
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China
| | - Shilei Zhao
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, China
| | - Zhenlong Yu
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, China
| | - Xiangsheng Xiao
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China
| | - Ranran Tang
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, China
| | - Yang Xuan
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, China
| | - Wenjing Yang
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, China
| | - Jiaojiao Hao
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, China
| | - Tingting Xu
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, China
| | - Qianyi Zhang
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, China
| | - Wenlin Huang
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China; State Key Laboratory of Targeted Drug for Tumors of Guangdong Province, Guangzhou Double Bioproduct Inc., Guangzhou, China
| | - Wuguo Deng
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China; State Key Laboratory of Targeted Drug for Tumors of Guangdong Province, Guangzhou Double Bioproduct Inc., Guangzhou, China.
| | - Wei Guo
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, China.
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73
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Zhang Q, Shi K, Yoo D. Suppression of type I interferon production by porcine epidemic diarrhea virus and degradation of CREB-binding protein by nsp1. Virology 2016; 489:252-68. [PMID: 26773386 PMCID: PMC7111358 DOI: 10.1016/j.virol.2015.12.010] [Citation(s) in RCA: 149] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2015] [Revised: 10/20/2015] [Accepted: 12/19/2015] [Indexed: 12/25/2022]
Abstract
Type I interferons (IFN-α/β) are the major components of the innate immune response of hosts, and in turn many viruses have evolved to modulate the host response during infection. We found that the IFN-β production was significantly suppressed during PEDV infection in cells. To identify viral IFN antagonists and to study their suppressive function, viral coding sequences for the entire structural and nonstructural proteins were cloned and expressed. Of 16 PEDV nonstructural proteins (nsps), nsp1, nsp3, nsp7, nsp14, nsp15 and nsp16 were found to inhibit the IFN-β and IRF3 promoter activities. The sole accessory protein ORF3, structure protein envelope (E), membrane (M), and nucleocapsid (N) protein were also shown to inhibit such activities. PEDV nsp1 did not interfere the IRF3 phosphorylation and nuclear translocation but interrupted the enhanceosome assembly of IRF3 and CREB-binding protein (CBP) by degrading CBP. A further study showed that the CBP degradation by nsp1 was proteasome-dependent. Our data demonstrate that PEDV modulates the host innate immune responses by degrading CBP and suppressing ISGs expression.
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Affiliation(s)
- Qingzhan Zhang
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana 61802, IL, USA
| | - Kaichuang Shi
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana 61802, IL, USA
| | - Dongwan Yoo
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana 61802, IL, USA.
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74
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Yasuma K, Yasunaga JI, Takemoto K, Sugata K, Mitobe Y, Takenouchi N, Nakagawa M, Suzuki Y, Matsuoka M. HTLV-1 bZIP Factor Impairs Anti-viral Immunity by Inducing Co-inhibitory Molecule, T Cell Immunoglobulin and ITIM Domain (TIGIT). PLoS Pathog 2016; 12:e1005372. [PMID: 26735971 PMCID: PMC4703212 DOI: 10.1371/journal.ppat.1005372] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 12/08/2015] [Indexed: 12/14/2022] Open
Abstract
Human T-cell leukemia virus type 1 (HTLV-1) infects CD4+ T cells and induces proliferation of infected cells in vivo, which leads to the onset of adult T-cell leukemia (ATL) in some infected individuals. The HTLV-1 bZIP factor (HBZ) gene, which is encoded in the minus strand of HTLV-1, plays critical roles in pathogenesis. In this study, RNA-seq and ChIP-seq analyses using HBZ transduced T cells revealed that HBZ upregulates the expression and promoter acetylation levels of a co-inhibitory molecule, T cell immunoglobulin and ITIM domain (TIGIT), in addition to those of regulatory T cells related genes, Foxp3 and Ccr4. TIGIT was expressed on CD4+ T cells from HBZ-transgenic (HBZ-Tg) mice, and on ATL cells and HTLV-1 infected CD4+ T cells of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) in vivo. Expression of Blimp1 and IL-10 was upregulated in TIGIT+CD4+ cells of HBZ-Tg mice compared with TIGIT-CD4+ T cells, suggesting the correlation between TIGIT expression and IL-10 production. When CD4+ T cells from HBZ-Tg mice were stimulated with TIGIT’s ligand, CD155, their production of the inhibitory cytokine IL-10 was enhanced. Furthermore, dendritic cells from HBZ-Tg mice produced high levels of IL-10 after stimulation. These data suggest that HBZ alters immune system to suppressive state via TIGIT and IL-10. Importantly, TIGIT suppressed T-cell responses to another HTLV-1 virus protein, Tax, in vitro. Blocking of TIGIT and PD-1 slightly increased anti-Tax T-cell activity in some HAM/TSP patients. These results suggest that HBZ-induced TIGIT on HTLV-1 infected cells impairs T-cell responses to viral antigens. This study shows that HBZ-induced TIGIT plays a pivotal role in attenuating host immune responses and shaping a microenvironment favorable to HTLV-1. HTLV-1 is a T-cell-tropic, latently infectious virus that causes a T-cell malignancy, ATL, and inflammatory diseases. The mechanisms by which HTLV-1 evades the immune response and establishes chronic infection are not yet understood. Recent studies have demonstrated that TIGIT, a co-inhibitory molecule, is expressed on tumor infiltrating T cells and T cells during viral infection, which suppresses the anti-tumor and anti-viral immune responses. Furthermore, blockade of co-inhibitory molecules of TIGIT and programmed cell death-1 (PD-1) disrupts immune checkpoints and enhances anti-tumor activity. We found that TIGIT is upregulated by HBZ, and TIGIT impairs anti-virus immune responses through an immunosuppressive cytokine, IL-10. These findings show that HTLV-1 utilizes a co-inhibitory molecule on infected cells to evade the host immune responses. We also found that blocking of TIGIT and PD-1 on peripheral blood mononuclear cells in HTLV-1 infected patients enhances immune responses to virus. These findings suggest a mechanism by which HTLV-1 shapes a microenvironment favorable to its persistence using induced TIGIT. TIGIT is a potential therapeutic target for ATL and HTLV-1 infected patients.
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Affiliation(s)
- Keiko Yasuma
- Laboratory of Virus Control, Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Jun-ichirou Yasunaga
- Laboratory of Virus Control, Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto, Japan
- * E-mail: (JY); (MM)
| | - Keiko Takemoto
- Laboratory of Biological Protection, Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Kenji Sugata
- Laboratory of Virus Control, Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Yuichi Mitobe
- Laboratory of Virus Control, Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Norihiro Takenouchi
- Department of Microbiology, Kansai Medical University, Hirakata, Osaka, Japan
| | - Masanori Nakagawa
- North Medical Center, Kyoto Prefectural University of Medicine, Yosano-cho, Kyoto, Japan
| | - Yutaka Suzuki
- Department of Computational Biology and Medical Science, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, Japan
| | - Masao Matsuoka
- Laboratory of Virus Control, Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto, Japan
- * E-mail: (JY); (MM)
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75
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The Cellular Protein Complex Associated with a Transforming Region of E1A Contains c-MYC. J Virol 2015; 90:1070-9. [PMID: 26559831 DOI: 10.1128/jvi.02039-15] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 11/02/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The cell-transforming activity of human adenovirus 5 (hAd5) E1A is mediated by the N-terminal half of E1A, which interacts with three different major cellular protein complexes, p300/CBP, TRRAP/p400, and pRb family members. Among these protein interactions, the interaction of pRb family proteins with conserved region 2 (CR2) of E1A is known to promote cell proliferation by deregulating the activities of E2F family transcription factors. The functional consequences of interaction with the other two protein complexes in regulating the transforming activity of E1A are not well defined. Here, we report that the E1A N-terminal region also interacted with the cellular proto-oncoprotein c-MYC and the homolog of enhancer of yellow 2 (ENY2). Our results suggested that these proteins interacted with an essential E1A transforming domain spanning amino acid residues 26 to 35 which also interacted with TRRAP and p400. Small interfering RNA (siRNA)-mediated depletion of TRRAP reduced c-MYC interaction with E1A, while p400 depletion did not. In contrast, depletion of TRRAP enhanced ENY2 interaction with E1A, suggesting that ENY2 and TRRAP may interact with E1A in a competitive manner. The same E1A region additionally interacted with the constituents of a deubiquitinase complex consisting of USP22, ATXN7, and ATXN7L3 via TRRAP. Acute short hairpin RNA (shRNA)-mediated depletion of c-MYC reduced the E1A transforming activity, while depletion of ENY2 and MAX did not. These results suggested that the association of c-MYC with E1A may, at least partially, play a role in the E1A transformation activity, independently of MAX. IMPORTANCE The transforming region of adenovirus E1A consists of three short modules which complex with different cellular protein complexes. The mechanism by which one of the transforming modules, CR2, promotes cell proliferation, through inactivating the activities of the pRb family proteins, is better understood than the activities of the other domains. Our analysis of the E1A proteome revealed the presence of the proto-oncoprotein c-MYC and of ENY2. We mapped these interactions to a critical transforming module of E1A that was previously known to interact with the scaffolding molecule TRRAP and the E1A-binding protein p400. We showed that c-MYC interacted with E1A through TRRAP, while ENY2 interacted with it independently. The data reported here indicated that depletion of c-MYC in normal human cells reduced the transforming activity of E1A. Our result raises a novel paradigm in oncogenic transformation by a DNA viral oncogene, the E1A gene, that may exploit the activity of a cellular oncogene, the c-MYC gene, in addition to inactivation of the tumor suppressors, such as pRb.
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76
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Radko S, Jung R, Olanubi O, Pelka P. Effects of Adenovirus Type 5 E1A Isoforms on Viral Replication in Arrested Human Cells. PLoS One 2015; 10:e0140124. [PMID: 26448631 PMCID: PMC4598095 DOI: 10.1371/journal.pone.0140124] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 09/21/2015] [Indexed: 11/22/2022] Open
Abstract
Human adenovirus has evolved to infect and replicate in terminally differentiated human epithelial cells, predominantly those within the airway, the gut, or the eye. To overcome the block to viral DNA replication present in these cells, the virus expresses the Early 1A proteins (E1A). These immediate early proteins drive cells into S-phase and induce expression of all other viral early genes. During infection, several E1A isoforms are expressed with proteins of 289, 243, 217, 171, and 55 residues being present for human adenovirus type 5. Here we examine the contribution that the two largest E1A isoforms make to the viral life cycle in growth-arrested normal human fibroblasts. Viruses that express E1A289R were found to replicate better than those that do not express this isoform. Importantly, induction of several viral genes was delayed in a virus expressing E1A243R, with several viral structural proteins undetectable by western blot. We also highlight the changes in E1A isoforms detected during the course of viral infection. Furthermore, we show that viral DNA replication occurs more efficiently, leading to higher number of viral genomes in cells infected with viruses that express E1A289R. Finally, induction of S-phase specific genes differs between viruses expressing different E1A isoforms, with those having E1A289R leading to, generally, earlier activation of these genes. Overall, we provide an overview of adenovirus replication using modern molecular biology approaches and further insights into the contribution that E1A isoforms make to the life cycle of human adenovirus in arrested human fibroblasts.
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Affiliation(s)
- Sandi Radko
- Department of Microbiology, University of Manitoba, 45 Chancellor’s Circle, Buller Building Room 427, Winnipeg, Manitoba, R3T 2N2, Canada
| | - Richard Jung
- Department of Microbiology, University of Manitoba, 45 Chancellor’s Circle, Buller Building Room 427, Winnipeg, Manitoba, R3T 2N2, Canada
| | - Oladunni Olanubi
- Department of Microbiology, University of Manitoba, 45 Chancellor’s Circle, Buller Building Room 427, Winnipeg, Manitoba, R3T 2N2, Canada
| | - Peter Pelka
- Department of Microbiology, University of Manitoba, 45 Chancellor’s Circle, Buller Building Room 427, Winnipeg, Manitoba, R3T 2N2, Canada
- * E-mail:
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77
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Deficiencies in Cellular Processes Modulated by the Retinoblastoma Protein Do Not Account for Reduced Human Cytomegalovirus Replication in Its Absence. J Virol 2015; 89:11965-74. [PMID: 26378180 DOI: 10.1128/jvi.01718-15] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2015] [Accepted: 09/10/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Despite encoding multiple viral proteins that modulate the retinoblastoma (Rb) protein in a manner classically defined as inactivation, human cytomegalovirus (HCMV) requires the presence of the Rb protein to replicate efficiently. In uninfected cells, Rb controls numerous pathways that the virus also commandeers during infection. These include cell cycle progression, senescence, mitochondrial biogenesis, apoptosis, and glutaminolysis. We investigated whether a potential inability of HCMV to regulate these Rb-controlled pathways in the absence of the Rb protein was the reason for reduced viral productive replication in Rb knockdown cells. We found that HCMV was equally able to modulate these pathways in the parental Rb-expressing and Rb-depleted cells. Our results suggest that Rb may be required to enhance a specific viral process during HCMV productive replication. IMPORTANCE The retinoblastoma (Rb) tumor suppressor is well established as a repressor of E2F-dependent transcription. Rb hyperphosphorylation, degradation, and binding by viral oncoproteins are also codified. Recent reports indicate Rb can be monophosphorylated, repress the transcription of antiviral genes in association with adenovirus E1A, modulate cellular responses to polycomb-mediated epigenetic methylations in human papillomavirus type 16 E7 expressing cells, and increase the efficiency of human cytomegalovirus (HCMV) productive replication. Since Rb function also now extends to regulation of mitochondrial function (apoptosis, metabolism), it is clear that our current understanding of this protein is insufficient to explain its roles in virus-infected cells and tumors. Work here reinforces this concept, showing the known roles of Rb are insufficient to explain its positive impact on HCMV replication. Therefore, HCMV, along with other viral systems, provide valuable tools to probe functions of Rb that might be modulated with therapeutics for cancers with viral or nonviral etiologies.
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78
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Herpesvirus saimiri MicroRNAs Preferentially Target Host Cell Cycle Regulators. J Virol 2015; 89:10901-11. [PMID: 26292323 DOI: 10.1128/jvi.01884-15] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Accepted: 08/12/2015] [Indexed: 12/31/2022] Open
Abstract
UNLABELLED In latently infected marmoset T cells, Herpesvirus saimiri (HVS) expresses six microRNAs (known as miR-HSURs [H. saimiri U-rich RNAs]). The viral miR-HSURs are processed from chimeric primary transcripts, each containing a noncoding U-rich RNA (HSUR) and a pre-miRNA hairpin. To uncover the functions of miR-HSURs, we identified mRNA targets in infected cells using high-throughput sequencing of RNA isolated by cross-linking immunoprecipitation (HITS-CLIP). HITS-CLIP revealed hundreds of robust Argonaute (Ago) binding sites mediated by miR-HSURs that map to the host genome but few in the HVS genome. Gene ontology analysis showed that several pathways regulating the cell cycle are enriched among cellular targets of miR-HSURs. Interestingly, miR-HSUR4-3p represses expression of the p300 transcriptional coactivator by binding the open reading frame of its mRNA. miR-HSUR5-3p directly regulates BiP, an endoplasmic reticulum (ER)-localized chaperone facilitating maturation of major histocompatibility complex class I (MHC-I) and the antiviral response. miR-HSUR5-3p also robustly downregulates WEE1, a key negative regulator of cell cycle progression, leading to reduced phosphorylation of its substrate, cyclin-dependent kinase (Cdk1). Consistently, inhibition of miR-HSUR5-3p in HVS-infected cells decreases their proliferation. Together, our results shed light on the roles of viral miRNAs in cellular transformation and viral latency. IMPORTANCE Viruses express miRNAs during various stages of infection, suggesting that viral miRNAs play critical roles in the viral life cycle. Compared to protein-coding genes, the functions of viral miRNAs are not well understood. This is because it has been challenging to identify their mRNA targets. Here, we focused on the functions of the recently discovered HVS miRNAs, called miR-HSURs. HVS is an oncogenic gammaherpesvirus that causes acute T-cell lymphomas and leukemias in New World primates and transforms human T cells. A better understanding of HVS biology will help advance our knowledge of virus-induced oncogenesis. Because numerous cellular miRNAs play crucial roles in cancer, viral miRNAs from the highly oncogenic HVS might also be important for transformation. Here, we found that the miR-HSURs preferentially modulate expression of host cell cycle regulators, as well as antiviral response factors. Our work provides further insight into the functions of herpesviral miRNAs in virus-induced oncogenesis and latency.
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79
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Marazzi I, Garcia-Sastre A. Interference of viral effector proteins with chromatin, transcription, and the epigenome. Curr Opin Microbiol 2015; 26:123-9. [PMID: 26232586 DOI: 10.1016/j.mib.2015.06.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 06/08/2015] [Accepted: 06/09/2015] [Indexed: 10/23/2022]
Abstract
Pathogens exploit cellular functions to create an environment conducive to their persistence and propagation. Viruses and bacteria express effector-proteins or virulence factors, known to interfere at the molecular level with regulatory 'checkpoints' of numerous physiological events in the cell. A newly prominent area of research is the identification of pathogenic effector proteins that function on the host chromatin, their subversion/interference with chromatin regulatory processes, the short/long/heritable effects on the infected cell and the ultimate consequence of their expression at the organismal level.
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Affiliation(s)
- Ivan Marazzi
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
| | - Adolfo Garcia-Sastre
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Department of Medicine, Division of Infectious Diseases, Icahn School of Medicine at Mount Sinai, NY, USA.
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80
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Abstract
Human adenoviruses (HAdV) are the cause of many acute infections, mostly in the respiratory and gastrointestinal (GI) tracts, as well as conjunctivitis. HAdV diseases in immunocompetent individuals are mostly self-limiting; however, in immunocompromised individuals, especially in pediatric units, HAdV infections are the cause of high morbidity and mortality. Despite the significant clinical impact, there are currently no approved antiviral therapies for HAdV infections. Here, we provide an overview of the different targets that could be considered for the design of specific drugs against HAdV, as well as the available in vitro and in vivo tools for the screening and evaluation of candidate molecules.
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81
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The retinoblastoma tumor suppressor promotes efficient human cytomegalovirus lytic replication. J Virol 2015; 89:5012-21. [PMID: 25694602 DOI: 10.1128/jvi.00175-15] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 02/13/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The retinoblastoma (Rb) tumor suppressor controls cell cycle, DNA damage, apoptotic, and metabolic pathways. DNA tumor virus oncoproteins reduce Rb function by either inducing Rb degradation or physically disrupting complexes between Rb and its myriad binding proteins. Human cytomegalovirus (HCMV), a betaherpesvirus being investigated for potential roles in human cancers, encodes multiple lytic-phase proteins that inactivate Rb in distinct ways, leading to the hypothesis that reduced Rb levels and/or activity would benefit HCMV lytic infection. Paradoxically, we found that Rb knockdown prior to infection, whether transient or constitutive, impaired HCMV lytic infection at multiple stages, notably viral DNA replication, late protein expression, and infectious virion production. The existence of differentially modified forms of Rb, the temporally and functionally distinct means by which HCMV proteins interact with Rb, and the necessity of Rb for efficient HCMV lytic replication combine to highlight the complex relationship between the virus and this critical tumor suppressor. IMPORTANCE Initial work examining viral protein modulation of cell cycle progression and oncogenic transformation revealed that these proteins inactivated the function of cellular tumor suppressor proteins. However, subsequent work, including experiments described here using human cytomegalovirus, demonstrate a more nuanced interaction that includes the necessity of cellular tumor suppressors for efficient viral replication. Understanding the positive impacts that cellular tumor suppressors have on viral infections may reveal new activities of these well-studied yet incompletely understood proteins. The basis for oncolytic viral therapy is the selective replication of viruses in transformed cells in which tumor suppressor function may be compromised. Understanding how tumor suppressors support viral infections may allow for the generation of modified oncolytic viruses with greater selective tumor cell replication and killing.
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