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Kaczmarek MP. Heterogenous circulating miRNA changes in ME/CFS converge on a unified cluster of target genes: A computational analysis. PLoS One 2023; 18:e0296060. [PMID: 38157384 PMCID: PMC10756525 DOI: 10.1371/journal.pone.0296060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 12/02/2023] [Indexed: 01/03/2024] Open
Abstract
Myalgic Encephalomyelitis / Chronic Fatigue Syndrome is a debilitating, multisystem disease of unknown mechanism, with a currently ongoing search for its endocrine mediators. Circulating microRNAs (miRNA) are a promising candidate for such a mediator and have been reported as significantly different in the patient population versus healthy controls by multiple studies. None of these studies, however, agree with each other on which specific miRNA are under- or over-expressed. This discrepancy is the subject of the computational study presented here, in which a deep dive into the predicted gene targets and their functional interactions is conducted, revealing that the aberrant circulating miRNAs in ME/CFS, although different between patients, seem to mainly target the same specific set of genes (p ≈ 0.0018), which are very functionally related to each other (p ≲ 0.0001). Further analysis of these functional relations, based on directional pathway information, points to impairments in exercise hyperemia, angiogenic adaptations to hypoxia, antioxidant defenses, and TGF-β signaling, as well as a shift towards mitochondrial fission, corroborating and explaining previous direct observations in ME/CFS. Many transcription factors and epigenetic modulators are implicated as well, with currently uncertain downstream combinatory effects. As the results show significant similarity to previous research on latent herpesvirus involvement in ME/CFS, the possibility of a herpesvirus origin of these miRNA changes is also explored through further computational analysis and literature review, showing that 8 out of the 10 most central miRNAs analyzed are known to be upregulated by various herpesviruses. In total, the results establish an appreciable and possibly central role for circulating microRNAs in ME/CFS etiology that merits further experimental research.
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Panda M, Kalita E, Rao A, Prajapati VK. Mechanism of cell cycle regulation and cell proliferation during human viral infection. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2023; 135:497-525. [PMID: 37061340 DOI: 10.1016/bs.apcsb.2022.11.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Over the history of the coevolution of Host viral interaction, viruses have customized the host cellular machinery into their use for viral genome replication, causing effective infection and ultimately aiming for survival. They do so by inducing subversions to the host cellular pathways like cell cycle via dysregulation of important cell cycle checkpoints by viral encoded proteins, arresting the cell cycle machinery, blocking cytokinesis as well as targeting subnuclear bodies, thus ultimately disorienting the cell proliferation. Both DNA and RNA viruses have been active participants in such manipulation resulting in serious outcomes of cancer. They achieve this by employing different mechanisms-Protein-protein interaction, protein-phosphorylation, degradation, redistribution, viral homolog, and viral regulation of APC at different stages of cell cycle events. Several DNA viruses cause the quiescent staged cells to undergo cell cycle which increases nucleotide pools logistically significantly persuading viral replication whereas few other viruses arrest a particular stage of cell cycle. This allows the latter group to sustain the infection which allows them to escape host immune response and support viral multiplication. Mechanical study of signaling such viral mediated pathways could give insight into understanding the etiology of tumorigenesis and progression. Overall this chapter highlights the possible strategies employed by DNA/RNA viral families which impact the normal cell cycle but facilitate viral infected cell replication. Such information could contribute to comprehending viral infection-associated disorders to further depth.
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Affiliation(s)
- Mamta Panda
- Department of Biochemistry, School of Life Sciences, Central University of Rajasthan, Bandarsindri, Kishangarh, Ajmer, Rajasthan, India
| | - Elora Kalita
- Department of Biochemistry, School of Life Sciences, Central University of Rajasthan, Bandarsindri, Kishangarh, Ajmer, Rajasthan, India
| | - Abhishek Rao
- Department of Biochemistry, School of Life Sciences, Central University of Rajasthan, Bandarsindri, Kishangarh, Ajmer, Rajasthan, India
| | - Vijay Kumar Prajapati
- Department of Biochemistry, School of Life Sciences, Central University of Rajasthan, Bandarsindri, Kishangarh, Ajmer, Rajasthan, India; Department of Biochemistry, School of Biological Sciences, Central University of Punjab, Bathinda, Punjab, India.
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Dong Z, Zhang X, Xiao M, Li K, Wang J, Chen P, Hu Z, Lu C, Pan M. Baculovirus LEF-11 interacts with BmIMPI to induce cell cycle arrest in the G2/M phase for viral replication. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2022; 188:105231. [PMID: 36464350 DOI: 10.1016/j.pestbp.2022.105231] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 07/23/2022] [Accepted: 09/08/2022] [Indexed: 06/17/2023]
Abstract
Viruses arrest the host cell cycle and using multiple functions of host cells is an important approach for their replication. Baculovirus arrests infected insect cells at both the late S and G2/M phase, but the strategy employed by baculovirus is not clearly understood. Our research suggests that the Bombyx mori nucleopolyhedrovirus (BmNPV) could arrest the cell cycle in the G2/M phase to promote virus replication, and also that the viral protein LEF-11 could inhibit host cell proliferation and arrest the cell cycle by inhibiting the cell cycle checkpoint proteins BmCyclinB and BmCDK1. Furthermore, we found that LEF-11 interacts with BmIMPI to regulate cell proliferation, but not by direct interaction with BmCyclinB or BmCDK1. In addition, our findings showed that BmIMPI was important and necessary for LEF-11 induced cell cycle arrest in the G2/M phase. Moreover, BmIMPI was found to interact with BmCyclinB and BmCDK1, and down-regulate the expression of BmCyclinB and BmCDK1 to compromise the cell cycle and cell proliferation. Taken together, the data presented demonstrated that baculovirus LEF-11 regulates BmIMPI to inhibit host cell proliferation and provide a new insight into the molecular mechanisms employed by viruses to induce cell cycle arrest.
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Affiliation(s)
- Zhanqi Dong
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China; Key Laboratory for Sericulture Functional Genomics and Biotechnology of Agricultural Ministry, Southwest University, Chongqing 400716, China
| | - Xinling Zhang
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China
| | - Miao Xiao
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China
| | - KeJie Li
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China
| | - Jie Wang
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China
| | - Peng Chen
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China; Key Laboratory for Sericulture Functional Genomics and Biotechnology of Agricultural Ministry, Southwest University, Chongqing 400716, China
| | - Zhigang Hu
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China
| | - Cheng Lu
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China; Key Laboratory for Sericulture Functional Genomics and Biotechnology of Agricultural Ministry, Southwest University, Chongqing 400716, China.
| | - Minhui Pan
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China; Key Laboratory for Sericulture Functional Genomics and Biotechnology of Agricultural Ministry, Southwest University, Chongqing 400716, China.
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Shimada K, Kobayashi N, Oka N, Takahashi M, Kondo K. Cooperative activation of the human herpesvirus 6B U79/80 early gene promoter by immediate-early proteins IE1B and IE2B. Microbiol Immunol 2020; 64:747-761. [PMID: 32910457 DOI: 10.1111/1348-0421.12844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 08/31/2020] [Accepted: 09/06/2020] [Indexed: 12/01/2022]
Abstract
The human herpesvirus 6B (HHV-6B) U79/80 gene belongs to the early gene class and appears as early as 3 hr postinfection. It is one of the most abundantly expressed transcripts and a useful diagnostic marker for viral reactivation. However, the expression mechanisms of the U79/80 gene remain unclear. To identify the viral factor(s) that activates the U79/80 promoter along with other HHV-6B core early gene promoters, p41, DNA polymerase, and U41, we examined the activities of U79/80 and other early gene promoters. In HHV-6B-infected MT-4 cells, U79/80 promoter activity was the highest among early gene promoters. In addition, we identified that HHV-6B immediate-early (IE)2B protein is one of the viral proteins involved in the activation of the U79/80 and other early gene promoters. Although the IE2B could independently activate these early gene promoters, the presence of IE1B significantly augmented the activities of early gene promoters. We also found that IE2B bound three human cytomegalovirus IE2-binding consensus, cis repression signal (CRS), within the U79/80 promoter. Moreover, the U79/80 promoter was activated by cellular factors, which are highly expressed in MT-4 cells, instead of HeLa cells because it was upregulated by mock infection and in the absence of IE2B. These results suggested that the activation mechanism of the U79/80 gene differs from other HHV-6B core early genes, apparently supporting its rapid and abundant expression. Therefore, the U79/80 early gene is an actually suitable biomarker of HHV-6B reactivation.
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Affiliation(s)
- Kazuya Shimada
- Department of Virology, The Jikei University School of Medicine, Minato-ku, Tokyo, Japan
| | - Nobuyuki Kobayashi
- Department of Virology, The Jikei University School of Medicine, Minato-ku, Tokyo, Japan
| | - Naomi Oka
- Department of Virology, The Jikei University School of Medicine, Minato-ku, Tokyo, Japan
| | - Mayumi Takahashi
- Department of Virology, The Jikei University School of Medicine, Minato-ku, Tokyo, Japan
| | - Kazuhiro Kondo
- Department of Virology, The Jikei University School of Medicine, Minato-ku, Tokyo, Japan
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Sepúlveda N, Carneiro J, Lacerda E, Nacul L. Myalgic Encephalomyelitis/Chronic Fatigue Syndrome as a Hyper-Regulated Immune System Driven by an Interplay Between Regulatory T Cells and Chronic Human Herpesvirus Infections. Front Immunol 2019; 10:2684. [PMID: 31824487 PMCID: PMC6883905 DOI: 10.3389/fimmu.2019.02684] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 10/31/2019] [Indexed: 12/13/2022] Open
Abstract
Autoimmunity and chronic viral infections are recurrent clinical observations in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), a complex disease with an unknown cause. Given these observations, the regulatory CD4+ T cells (Tregs) show promise to be good candidates for the underlying pathology due to their capacity to suppress the immune responses against both self and microbial antigens. Here, we discussed the overlooked role of these cells in the chronicity of Human Herpes Virus 6 (HHV6), Herpes Simplex 1 (HSV1), and Epstein–Barr virus (EBV), as often reported as triggers of ME/CFS. Using simulations of the cross-regulation model for the dynamics of Tregs, we illustrated that mild infections might lead to a chronically activated immune responses under control of Tregs if the responding clone has a high autoimmune potential. Such infections promote persistent inflammation and possibly fatigue. We then hypothesized that ME/CFS is a condition characterized by a predominance of this type of infections under control of Tregs. In contrast, healthy individuals are hypothesized to trigger immune responses of a virus-specific clone with a low autoimmune potential. According to this hypothesis, simple model simulations of the CD4+ T-cell repertoire could reproduce the increased density and percentages of Tregs observed in patients suffering from the disease, when compared to healthy controls. A deeper analysis of Tregs in the pathogenesis of ME/CFS will help to assess the validity of this hypothesis.
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Affiliation(s)
- Nuno Sepúlveda
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom.,Centre of Statistics and Its Applications, University of Lisbon, Lisbon, Portugal
| | - Jorge Carneiro
- Quantitative Organism Biology Group, Gulbenkian Institute of Science, Oeiras, Portugal
| | - Eliana Lacerda
- Department of Clinical Research, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Luis Nacul
- Department of Clinical Research, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
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Fan Y, Sanyal S, Bruzzone R. Breaking Bad: How Viruses Subvert the Cell Cycle. Front Cell Infect Microbiol 2018; 8:396. [PMID: 30510918 PMCID: PMC6252338 DOI: 10.3389/fcimb.2018.00396] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 10/22/2018] [Indexed: 01/10/2023] Open
Abstract
Interactions between the host and viruses during the course of their co-evolution have not only shaped cellular function and the immune system, but also the counter measures employed by viruses. Relatively small genomes and high replication rates allow viruses to accumulate mutations and continuously present the host with new challenges. It is therefore, no surprise that they either escape detection or modulate host physiology, often by redirecting normal cellular pathways to their own advantage. Viruses utilize a diverse array of strategies and molecular targets to subvert host cellular processes, while evading detection. These include cell-cycle regulation, major histocompatibility complex-restricted antigen presentation, intracellular protein transport, apoptosis, cytokine-mediated signaling, and humoral immune responses. Moreover, viruses routinely manipulate the host cell cycle to create a favorable environment for replication, largely by deregulating cell cycle checkpoints. This review focuses on our current understanding of the molecular aspects of cell cycle regulation that are often targeted by viruses. Further study of their interactions should provide fundamental insights into cell cycle regulation and improve our ability to exploit these viruses.
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Affiliation(s)
- Ying Fan
- HKU-Pasteur Research Pole, LKS Faculty of Medicine, School of Public Health, The University of Hong Kong, Hong Kong, Hong Kong.,MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Sumana Sanyal
- HKU-Pasteur Research Pole, LKS Faculty of Medicine, School of Public Health, The University of Hong Kong, Hong Kong, Hong Kong.,LKS Faculty of Medicine, School of Biomedical Sciences, The University of Hong Kong, Hong Kong, Hong Kong
| | - Roberto Bruzzone
- HKU-Pasteur Research Pole, LKS Faculty of Medicine, School of Public Health, The University of Hong Kong, Hong Kong, Hong Kong.,Department of Cell Biology and Infection, Institut Pasteur, Paris, France
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Mori J, Kawabata A, Tang H, Tadagaki K, Mizuguchi H, Kuroda K, Mori Y. Human Herpesvirus-6 U14 Induces Cell-Cycle Arrest in G2/M Phase by Associating with a Cellular Protein, EDD. PLoS One 2015; 10:e0137420. [PMID: 26340541 PMCID: PMC4560387 DOI: 10.1371/journal.pone.0137420] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 08/17/2015] [Indexed: 11/19/2022] Open
Abstract
The human herpesvirus-6 (HHV-6) infection induces cell-cycle arrest. In this study, we found that the HHV-6-encoded U14 protein induced cell-cycle arrest at G2/M phase via an association with the cellular protein EDD, a mediator of DNA-damage signal transduction. In the early phase of HHV-6 infection, U14 colocalized with EDD dots in the nucleus, and similar colocalization was also observed in cells transfected with a U14 expression vector. When the carboxyl-terminal region of U14 was deleted, no association of U14 and EDD was observed, and the percentage of cells in G2/M decreased relative to that in cells expressing wild-type U14, indicating that the C-terminal region of U14 and the U14-EDD association are critical for the cell-cycle arrest induced by U14. These results indicate that U14 is a G2/M checkpoint regulator encoded by HHV-6.
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Affiliation(s)
- Junko Mori
- Division of Clinical Virology, Kobe University Graduate School of Medicine, Kobe, 6500017, Japan
| | - Akiko Kawabata
- Division of Clinical Virology, Kobe University Graduate School of Medicine, Kobe, 6500017, Japan
| | - Huamin Tang
- Division of Clinical Virology, Kobe University Graduate School of Medicine, Kobe, 6500017, Japan
- Department of Immunology, Nanjing Medical University, Nanjing, 210029, China
| | - Kenjiro Tadagaki
- Department of Biochemistry and Molecular Biology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 6028566, Japan
| | - Hiroyuki Mizuguchi
- Laboratory of Biochemistry and Molecular Biology, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, 5650871, Japan
| | - Kazumichi Kuroda
- Division of Microbiology, Department of Pathology and Microbiology, Nihon University School of Medicine, Tokyo, 1738610, Japan
| | - Yasuko Mori
- Division of Clinical Virology, Kobe University Graduate School of Medicine, Kobe, 6500017, Japan
- Laboratory of Virology and Vaccinology, National Institute of Biomedical Innovation, Osaka, 5670085, Japan
- * E-mail:
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Frenkel N, Sharon E, Zeigerman H. Roseoloviruses manipulate host cell cycle. Curr Opin Virol 2014; 9:162-6. [PMID: 25462449 DOI: 10.1016/j.coviro.2014.10.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Revised: 10/05/2014] [Accepted: 10/07/2014] [Indexed: 10/24/2022]
Abstract
During lytic infections HHV-6A and HHV-6B disrupt E2F1-Rb complexes by Rb degradation, releasing E2F1 and driving the infected cells toward the S-phase. Whereas upon infection E2F1 and its cofactor DP1 were up-regulated, additional E2F responsive genes were expressed differentially in various cells. E2F binding sites were identified in promoters of several HHV-6 genes, including the U27 and U79 associated with viral DNA replication, revealing high dependence on the binding site and the effect of the E2F1 transcription factor. Viral genes regulation by E2F1 can synchronize viral replication with the optimal cell cycle phase, enabling utilization of host resources for successful viral replication. Furthermore, it was found that infection by roseoloviruses leads to cell cycle arrest, mostly in the G2/M-phase.
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Affiliation(s)
- Niza Frenkel
- Department of Cell Research and Immunology and the S. Daniel Abraham Institute for Molecular Virology, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Eyal Sharon
- Department of Cell Research and Immunology and the S. Daniel Abraham Institute for Molecular Virology, Tel Aviv University, Tel Aviv 69978, Israel
| | - Haim Zeigerman
- Department of Cell Research and Immunology and the S. Daniel Abraham Institute for Molecular Virology, Tel Aviv University, Tel Aviv 69978, Israel
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Tacyildiz N, Dincaslan HU, Ozdemir H, Yavuz G, Unal E, Ikinciogullari A, Dogu F, Guloglu D, Suskan E, Kose K. The seroprevalence of Kaposi's sarcoma associated herpes virus and human herpes virus-6 in pediatric patients with cancer and healthy children in a Turkish pediatric oncology center. Indian J Med Paediatr Oncol 2014; 35:221-5. [PMID: 25336794 PMCID: PMC4202619 DOI: 10.4103/0971-5851.142039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Many studies have tried to be establish a pathogenic role for human herpesvirus-6 and -8 (HHV-6, HHV-8) in malignant diseases, but whether these viruses plays a role in these pathologies remains unclear. HHV-6 and HHV-8 seropositivity were shown in a healthy population. There is no published data in Turkey about seroprevalence of these viruses. We aimed to determine the seroprevalence of HHV-6 and HHV-8 in pediatric cancer patients and to compare with healthy Turkish children's viral seroprevalence. PATIENTS AND METHODS Ninety-three pediatric cancer patients and 43 age-matched healthy children were included in the study. All sera were screened for antibodies to HHV-6 and HHV-8 by ELISA. RESULTS HHV-8 immunoglobulin G (IgG) was positive in 3.3% of lymphoma patients, in 4.8% of acute lymphoblastic leukemia (ALL) patients, in 4.8% of retinoblastoma patients and in 7% of healthy children. There was no significant difference in HHV-8 seroprevelance between these groups. HHV-6 seroprevalence was 81% in ALL patients, 70% in lymphoma group, 81% in retinoblastoma patients and 69.8% in healthy children. Although there was no significant difference in HHV-6 prevalence between healthy children and pediatric cancer patients, HHV-6 seropositivity tended to be higher in retinoblastoma patients under age of 4 years (odds ratio: 2.925). CONCLUSION HHV-6 seroprevalence was higher than HHV-8 seropositivity in our study. Viral studies related HHV-6 seroprevelance in retinoblastoma patients would be useful to clarify if there is any etiological association between HHV-6 and retinoblastoma.
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Affiliation(s)
- Nurdan Tacyildiz
- Department of Pediatrics Oncology, Ankara University Medical School, Ankara, Turkey
| | | | - Halil Ozdemir
- Department of Pediatric Infection Diseases, Ankara University Medical School, Ankara, Turkey
| | - Gulsan Yavuz
- Department of Pediatrics Oncology, Ankara University Medical School, Ankara, Turkey
| | - Emel Unal
- Department of Pediatrics Oncology, Ankara University Medical School, Ankara, Turkey
| | - Aydan Ikinciogullari
- Department of Pediatric Immunology, Ankara University Medical School, Ankara, Turkey
| | - Figen Dogu
- Department of Pediatric Immunology, Ankara University Medical School, Ankara, Turkey
| | - Deniz Guloglu
- Department of Pediatric Immunology, Ankara University Medical School, Ankara, Turkey
| | - Emine Suskan
- Department of Pediatrics, Ankara University Medical School, Ankara, Turkey
| | - Kenan Kose
- Department of Biostatistics, Ankara University Medical School, Ankara, Turkey
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Schleimann MH, Hoberg S, Solhøj Hansen A, Bundgaard B, Witt CT, Kofod-Olsen E, Höllsberg P. The DR6 protein from human herpesvirus-6B induces p53-independent cell cycle arrest in G2/M. Virology 2014; 452-453:254-63. [PMID: 24606703 DOI: 10.1016/j.virol.2014.01.028] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 01/09/2014] [Accepted: 01/30/2014] [Indexed: 11/24/2022]
Abstract
HHV-6B infection inhibits cell proliferation in G2/M, but no protein has so far been recognized to exert this function. Here we identify the protein product of direct repeat 6, DR6, as an inhibitor of G2/M cell-cycle progression. Transfection of DR6 reduced the total number of cells compared with mock-transfected cells. Lentiviral transduction of DR6 inhibited host cell DNA synthesis in a p53-independent manner, and this inhibition was DR6 dose-dependent. A deletion of 66 amino acids from the N-terminal part of DR6 prevented efficient nuclear translocation and the ability to inhibit DNA synthesis. DR6-induced accumulation of cells in G2/M was accompanied by an enhanced expression of cyclin B1 that accumulated predominantly in the cytoplasm. Pull-down of cyclin B1 brought down pCdk1 with the inactivating phosphorylation at Tyr15. Together, DR6 delays cell cycle with an accumulation of cells in G2/M and thus might be involved in HHV-6B-induced cell-cycle arrest.
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Affiliation(s)
| | - Søren Hoberg
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | | | | | | | | | - Per Höllsberg
- Department of Biomedicine, Aarhus University, Aarhus, Denmark.
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11
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Human herpesvirus 6 (HHV-6) alters E2F1/Rb pathways and utilizes the E2F1 transcription factor to express viral genes. Proc Natl Acad Sci U S A 2013; 111:451-6. [PMID: 24335704 DOI: 10.1073/pnas.1308854110] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
E2F transcription factors play pivotal roles in controlling the expression of genes involved in cell-cycle progression. Different viruses affect E2F1/retinoblastoma (Rb) interactions by diverse mechanisms releasing E2F1 from its suppressor Rb, enabling viral replication. We show that in T cells infected with human herpesvirus 6A (HHV-6A), the E2F1 protein and its cofactor DP1 increased, whereas the Rb protein underwent massive degradation without hyperphosphorylation at three sites known to control E2F/Rb association. Although E2F1 and DP1 increased without Rb suppression, the E2F1 target genes-including cyclin A, cyclin E, and dihydrofolate reductase-were not up-regulated. To test whether the E2F1/DP1 complexes were used for viral transcription, we scanned the viral genome for genes containing the E2F binding site in their promoters. In the present work, we concentrated on the U27 and U79 genes known to act in viral DNA synthesis. We constructed amplicon-6 vectors containing a GFP reporter gene driven by WT viral promoter or by promoter mutated in the E2F binding site. We found that the expression of the fusion U27 promoter was dependent on the presence of the E2F binding site. Test of the WT U79 promoter yielded >10-fold higher expression of the GFP reporter gene than the mutant U79 promoter with abrogated E2F binding site. Moreover, by using siRNA to E2F1, we found that E2F1 was essential for the activity of the U79 promoter. These findings revealed a unique pathway in HHV-6 replication: The virus causes Rb degradation and uses the increased E2F1 and DP1 factors to transcribe viral genes.
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12
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Li L, Gu B, Zhou F, Chi J, Feng D, Xie F, Wang F, Ma C, Li M, Wang J, Yao K. Cell cycle perturbations induced by human herpesvirus 6 infection and their effect on virus replication. Arch Virol 2013; 159:365-70. [PMID: 24013234 PMCID: PMC7086940 DOI: 10.1007/s00705-013-1826-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 07/08/2013] [Indexed: 11/28/2022]
Abstract
In this study, we demonstrate that infection of HSB-2 cells with human herpesvirus 6 (HHV-6) resulted in the accumulation of infected cells in the G2/M phase of the cell cycle. Analysis of various cell-cycle-regulatory proteins indicated that the levels of cyclins A2, B1, and E1 were increased in HHV-6-infected cells, but there was no difference in cyclin D1 levels between mock-infected and HHV-6-infected cells. Our data also showed that inducing G2/M phase arrest in cells infected by HHV-6 provided favorable conditions for viral replication.
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Affiliation(s)
- Lingyun Li
- Department of Developmental Genetics, Nanjing Medical University, Nanjing, 210029, Jiangsu, China
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13
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Li L, Gu B, Zhou F, Chi J, Wang F, Liu G, Ding C, Xie F, Qing J, Guo Y, Yao K. Human herpesvirus 6A infects human embryonic fibroblasts and induces G2/M arrest and cell death. J Med Virol 2012; 84:657-63. [PMID: 22337306 DOI: 10.1002/jmv.23226] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Human herpesvirus 6 (HHV-6) is a beta-herpesvirus capable of infecting cells from different origin. In this study, infection with HHV-6A of human embryonic fibroblasts (HEFs) was performed. Infected cells showed obvious cytopathic effects (CPE). PCR and immunohistochemical tests also confirmed that HEFs are susceptible to HHV-6A infection. The biological effects of HHV-6A infection on HEFs were studied. Infected cells showed decreased proliferation as measured by [(3)H] thymidine incorporation and cell counting. Further analysis demonstrated that infection with HHV-6A leads to cell cycle arrest at G2/M phase and increasing cell death. This is the first demonstration that infection of HEFs with HHV-6A causes profound alterations of cell properties.
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Affiliation(s)
- Lingyun Li
- Department of Microbiology and Immunology, Nanjing Medical University, Nanjing, China
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Human herpesvirus 6 suppresses T cell proliferation through induction of cell cycle arrest in infected cells in the G2/M phase. J Virol 2011; 85:6774-83. [PMID: 21525341 DOI: 10.1128/jvi.02577-10] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Human herpesvirus 6 (HHV-6) is an important immunosuppressive and immunomodulatory virus that primarily infects immune cells and strongly suppresses the proliferation of infected cells. However, the mechanisms responsible for the regulation and suppression mediated by HHV-6 are still unknown. In this study, we examined the ability of HHV-6A to manipulate cell cycle progression in infected cells and explored the potential molecular mechanisms. We demonstrated that infection with HHV-6A imposed a growth-inhibitory effect on HSB-2 cells by inducing cell cycle arrest at the G(2)/M phase. We then showed that the activity of the Cdc2-cyclin B1 complex was significantly decreased in HHV-6A-infected HSB-2 cells. Furthermore, we found that inactivation of Cdc2-cyclin B1 in HHV-6A-infected cells occurred through the inhibitory Tyr15 phosphorylation resulting from elevated Wee1 expression and inactivated Cdc25C. The reduction of Cdc2-cyclin B1 activity in HHV-6-infected cells was also partly due to the increased expression of the cell cycle-regulatory molecule p21 in a p53-dependent manner. In addition, HHV-6A infection activated the DNA damage checkpoint kinases Chk2 and Chk1. Our data suggest that HHV-6A infection induces G(2)/M arrest in infected T cells via various molecular regulatory mechanisms. These results further demonstrate the potential mechanisms involved in immune suppression and modulation mediated by HHV-6 infection, and they provide new insights relevant to the development of novel vaccines and immunotherapeutic approaches.
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Traylen CM, Patel HR, Fondaw W, Mahatme S, Williams JF, Walker LR, Dyson OF, Arce S, Akula SM. Virus reactivation: a panoramic view in human infections. Future Virol 2011; 6:451-463. [PMID: 21799704 DOI: 10.2217/fvl.11.21] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Viruses are obligate intracellular parasites, relying to a major extent on the host cell for replication. An active replication of the viral genome results in a lytic infection characterized by the release of new progeny virus particles, often upon the lysis of the host cell. Another mode of virus infection is the latent phase, where the virus is 'quiescent' (a state in which the virus is not replicating). A combination of these stages, where virus replication involves stages of both silent and productive infection without rapidly killing or even producing excessive damage to the host cells, falls under the umbrella of a persistent infection. Reactivation is the process by which a latent virus switches to a lytic phase of replication. Reactivation may be provoked by a combination of external and/or internal cellular stimuli. Understanding this mechanism is essential in developing future therapeutic agents against viral infection and subsequent disease. This article examines the published literature and current knowledge regarding the viral and cellular proteins that may play a role in viral reactivation. The focus of the article is on those viruses known to cause latent infections, which include herpes simplex virus, varicella zoster virus, Epstein-Barr virus, human cytomegalovirus, human herpesvirus 6, human herpesvirus 7, Kaposi's sarcoma-associated herpesvirus, JC virus, BK virus, parvovirus and adenovirus.
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Affiliation(s)
- Christopher M Traylen
- Department of Microbiology & Immunology, Brody School of Medicine at East Carolina University, Greenville, NC 27834, USA
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The DR1 and DR6 first exons of human herpesvirus 6A are not required for virus replication in culture and are deleted in virus stocks that replicate well in T-cell lines. J Virol 2010; 84:2648-56. [PMID: 20053742 DOI: 10.1128/jvi.01951-09] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Human herpesvirus 6A (HHV-6A) and HHV-6B are lymphotropic viruses which replicate in cultured activated cord blood mononuclear cells (CBMCs) and in T-cell lines. Viral genomes are composed of 143-kb unique (U) sequences flanked by approximately 8- to 10-kb left and right direct repeats, DR(L) and DR(R). We have recently cloned HHV-6A (U1102) into bacterial artificial chromosome (BAC) vectors, employing DNA replicative intermediates. Surprisingly, HHV-6A BACs and their parental DNAs were found to contain short approximately 2.7-kb DRs. To test whether DR shortening occurred during passaging in CBMCs or in the SupT1 T-cell line, we compared packaged DNAs from various passages. Restriction enzymes, PCR, and sequencing analyses have shown the following. (i) Early (1992) viral preparations from CBMCs contained approximately 8-kb DRs. (ii) Viruses currently propagated in SupT1 cells contained approximately 2.7-kb DRs. (iii) The deletion spans positions 60 to 5545 in DR(L), including genes encoded by DR1 through the first exon of DR6. The pac-2-pac-1 packaging signals, the DR7 open reading frame (ORF), and the DR6 second exon were not deleted. (iv) The DR(R) sequence was similarly shortened by 5.4 kb. (v) The DR1 through DR6 first exon sequences were deleted from the entire HHV-6A BACs, revealing that they were not translocated into other genome locations. (vi) When virus initially cultured in CBMCs was passaged in SupT1 cells no DR shortening occurred. (vii) Viral stocks possessing short DRs replicated efficiently, revealing the plasticity of herpesvirus genomes. We conclude that the DR deletion occurred once, producing virus with advantageous growth "conquering" the population. The DR1 gene and the first DR6 exon are not required for propagation in culture.
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Cloning human herpes virus 6A genome into bacterial artificial chromosomes and study of DNA replication intermediates. Proc Natl Acad Sci U S A 2009; 106:19138-43. [PMID: 19858479 DOI: 10.1073/pnas.0908504106] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Cloning of large viral genomes into bacterial artificial chromosomes (BACs) facilitates analyses of viral functions and molecular mutagenesis. Previous derivations of viral BACs involved laborious recombinations within infected cells. We describe a single-step production of viral BACs by direct cloning of unit length genomes, derived from circular or head-to-tail concatemeric DNA replication intermediates. The BAC cloning is independent of intracellular recombinations and DNA packaging constraints. We introduced the 160-kb human herpes virus 6A (HHV-6A) genome into BACs by digesting the viral DNA replicative intermediates with the Sfil enzyme that cleaves the viral genome in a single site. The recombinant BACs contained also the puromycin selection gene, GFP, and LoxP sites flanking the BAC sequences. The HHV-6A-BAC vectors were retained stably in puromycin selected 293T cells. In the presence of irradiated helper virus, supplying most likely proteins enhancing gene expression they expressed early and late genes in SupT1 T cells. The method is especially attractive for viruses that replicate inefficiently and for viruses propagated in suspension cells. We have used the fact that the BAC cloning "freezes" the viral DNA replication intermediates to analyze their structure. The results revealed that HHV-6A-BACs contained a single direct repeat (DR) rather than a DR-DR sequence, predicted to arise by circularization of parental genomes with a DR at each terminus. HHV-6A DNA molecules prepared from the infected cells also contained DNA molecules with a single DR. Such forms were not previously described for HHV-6 DNA.
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Lee WG, Demirci U, Khademhosseini A. Microscale electroporation: challenges and perspectives for clinical applications. Integr Biol (Camb) 2009; 1:242-51. [PMID: 20023735 DOI: 10.1039/b819201d] [Citation(s) in RCA: 126] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Microscale engineering plays a significant role in developing tools for biological applications by miniaturizing devices and providing controllable microenvironments for in vitro cell research. Miniaturized devices offer numerous benefits in comparison to their macroscale counterparts, such as lower use of expensive reagents, biomimetic environments, and the ability to manipulate single cells. Microscale electroporation is one of the main beneficiaries of microscale engineering as it provides spatial and temporal control of various electrical parameters. Microscale electroporation devices can be used to reduce limitations associated with the conventional electroporation approaches such as variations in the local pH, electric field distortion, sample contamination, and the difficulties in transfecting and maintaining the viability of desired cell types. Here, we present an overview of recent advances of the microscale electroporation methods and their applications in biology, as well as current challenges for its use for clinical applications. We categorize microscale electroporation into microchannel and microcapillary electroporation. Microchannel-based electroporation can be used for transfecting cells within microchannels under dynamic flow conditions in a controlled and high-throughput fashion. In contrast, microcapillary-based electroporation can be used for transfecting cells within controlled reaction chambers under static flow conditions. Using these categories we examine the use of microscale electroporation for clinical applications related to HIV-1, stem cells, cancer and other diseases and discuss the challenges in further advancing this technology for use in clinical medicine and biology.
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Affiliation(s)
- Won Gu Lee
- Center for Biomedical Engineering, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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