1
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Marino-Merlo F, Grelli S, Mastino A, Lai M, Ferrari P, Nicolini A, Pistello M, Macchi B. Human T-Cell Leukemia Virus Type 1 Oncogenesis between Active Expression and Latency: A Possible Source for the Development of Therapeutic Targets. Int J Mol Sci 2023; 24:14807. [PMID: 37834255 PMCID: PMC10572738 DOI: 10.3390/ijms241914807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Revised: 09/16/2023] [Accepted: 09/28/2023] [Indexed: 10/15/2023] Open
Abstract
The human T-cell leukemia virus type 1 (HTLV-1) is the only known human oncogenic retrovirus. HTLV-1 can cause a type of cancer called adult T-cell leukemia/lymphoma (ATL). The virus is transmitted through the body fluids of infected individuals, primarily breast milk, blood, and semen. At least 5-10 million people in the world are infected with HTLV-1. In addition to ATL, HTLV-1 infection can also cause HTLV-I-associated myelopathy (HAM/TSP). ATL is characterized by a low viral expression and poor prognosis. The oncogenic mechanism triggered by HTLV-1 is extremely complex and the molecular pathways are not fully understood. However, viral regulatory proteins Tax and HTLV-1 bZIP factor (HBZ) have been shown to play key roles in the transformation of HTLV-1-infected T cells. Moreover, several studies have shown that the final fate of HTLV-1-infected transformed Tcell clones is the result of a complex interplay of HTLV-1 oncogenic protein expression with cellular transcription factors that subvert the cell cycle and disrupt regulated cell death, thereby exerting their transforming effects. This review provides updated information on the mechanisms underlying the transforming action of HTLV-1 and highlights potential therapeutic targets to combat ATL.
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Affiliation(s)
- Francesca Marino-Merlo
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, 98166 Messina, Italy;
| | - Sandro Grelli
- Department of Experimental Medicine, University of Rome “Tor Vergata”, 00133 Rome, Italy;
| | - Antonio Mastino
- The Institute of Translational Pharmacology, CNR, 00133 Rome, Italy;
| | - Michele Lai
- Retrovirus Center and Virology Section, Department of Translational Research, University of Pisa, 56100 Pisa, Italy; (M.L.); (M.P.)
| | - Paola Ferrari
- Unit of Oncology, Department of Medical and Oncological Area, Azienda Ospedaliera—Universitaria Pisana, 56125 Pisa, Italy;
| | - Andrea Nicolini
- Department of Oncology, Transplantations and New Technologies in Medicine, University of Pisa, 56126 Pisa, Italy
| | - Mauro Pistello
- Retrovirus Center and Virology Section, Department of Translational Research, University of Pisa, 56100 Pisa, Italy; (M.L.); (M.P.)
| | - Beatrice Macchi
- Department of Chemical Science and Technology, University of Rome “Tor Vergata”, 00133 Rome, Italy;
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2
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Georgieva ER, Borbat PP, Fanouraki C, Freed JH. High-yield production in E. coli and characterization of full-length functional p13 II protein from human T-cell leukemia virus type 1. Protein Expr Purif 2020; 173:105659. [PMID: 32360379 DOI: 10.1016/j.pep.2020.105659] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 04/20/2020] [Accepted: 04/26/2020] [Indexed: 10/24/2022]
Abstract
Human T-cell leukemia virus type 1 is an oncovirus that causes aggressive adult T-cell leukemia but is also responsible for severe neurodegenerative and endocrine disorders. Combatting HTLV-1 infections requires a detailed understanding of the viral mechanisms in the host. Therefore, in vitro studies of important virus-encoded proteins would be critical. Our focus herein is on the HTLV-1-encoded regulatory protein p13II, which interacts with the inner mitochondrial membrane, increasing its permeability to cations (predominantly potassium, K+). Thereby, this protein affects mitochondrial homeostasis. We report on our progress in developing specific protocols for heterologous expression of p13II in E. coli, and methods for its purification and characterization. We succeeded in producing large quantities of highly-pure full-length p13II, deemed to be its fully functional form. Importantly, our particular approach based on the fusion of ubiquitin to the p13II C-terminus was instrumental in increasing the persistently low expression of soluble p13II in its native form. We subsequently developed approaches for protein spin labeling and a conformation study using double electron-electron resonance (DEER) spectroscopy and a fluorescence-based cation uptake assay for p13II in liposomes. Our DEER results point to large protein conformation changes occurring upon transition from the soluble to the membrane-bound state. The functional assay on p13II-assisted transport of thallium (Tl+) through the membrane, wherein Tl+ substituted for K+, suggests transmembrane potential involvement in p13II function. Our study lays the foundation for expansion of in vitro functional and structural investigations on p13II and would aid in the development of structure-based protein inhibitors and markers.
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Affiliation(s)
- Elka R Georgieva
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY, 14853, USA.
| | - Peter P Borbat
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY, 14853, USA; ACERT Center for Advanced ESR Technology, Cornell University, Ithaca, NY, 14853, USA
| | - Christina Fanouraki
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY, 14853, USA
| | - Jack H Freed
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY, 14853, USA; ACERT Center for Advanced ESR Technology, Cornell University, Ithaca, NY, 14853, USA
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3
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Bangham CRM, Miura M, Kulkarni A, Matsuoka M. Regulation of Latency in the Human T Cell Leukemia Virus, HTLV-1. Annu Rev Virol 2019; 6:365-385. [PMID: 31283437 DOI: 10.1146/annurev-virology-092818-015501] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The human T cell leukemia virus persists in vivo in 103 to 106 clones of T lymphocytes that appear to survive for the lifetime of the host. The plus strand of the provirus is typically transcriptionally silent in freshly isolated lymphocytes, but the strong, persistently activated cytotoxic T lymphocyte (CTL) response to the viral antigens indicates that the virus is not constantly latent in vivo. There is now evidence that the plus strand is transcribed in intense intermittent bursts that are triggered by cellular stress, modulated by hypoxia and glycolysis, and inhibited by polycomb repressive complex 1 (PRC1). The minus-strand gene hbz is transcribed at a lower, more constant level but is silent in a proportion of infected cells at a given time. Viral genes in the sense and antisense strands of the provirus play different respective roles in latency and de novo infection: Expression of the plus-strand gene tax is essential for de novo infection, whereas hbz appears to facilitate survival of the infected T cell clone in vivo.
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Affiliation(s)
- Charles R M Bangham
- Division of Infectious Diseases, Department of Medicine, Imperial College London, London W2 1PG, United Kingdom;
| | - Michi Miura
- Division of Infectious Diseases, Department of Medicine, Imperial College London, London W2 1PG, United Kingdom;
| | - Anurag Kulkarni
- Division of Infectious Diseases, Department of Medicine, Imperial College London, London W2 1PG, United Kingdom;
| | - Masao Matsuoka
- Laboratory of Virus Control, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto 606-8507, Japan.,Department of Hematology, Rheumatology and Infectious Diseases, Kumamoto University School of Medicine, Kumamoto 860-8556, Japan;
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4
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Georgieva ER. Non-Structural Proteins from Human T-cell Leukemia Virus Type 1 in Cellular Membranes-Mechanisms for Viral Survivability and Proliferation. Int J Mol Sci 2018; 19:ijms19113508. [PMID: 30413005 PMCID: PMC6274929 DOI: 10.3390/ijms19113508] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 11/01/2018] [Accepted: 11/06/2018] [Indexed: 12/27/2022] Open
Abstract
Human T-cell leukemia virus type 1 (HTLV-1) is the causative agent of illnesses, such as adult T-cell leukemia/lymphoma, myelopathy/tropical spastic paraparesis (a neurodegenerative disorder), and other diseases. Therefore, HTLV-1 infection is a serious public health concern. Currently, diseases caused by HTLV-1 cannot be prevented or cured. Hence, there is a pressing need to comprehensively understand the mechanisms of HTLV-1 infection and intervention in host cell physiology. HTLV-1-encoded non-structural proteins that reside and function in the cellular membranes are of particular interest, because they alter cellular components, signaling pathways, and transcriptional mechanisms. Summarized herein is the current knowledge about the functions of the membrane-associated p8I, p12I, and p13II regulatory non-structural proteins. p12I resides in endomembranes and interacts with host proteins on the pathways of signal transduction, thus preventing immune responses to the virus. p8I is a proteolytic product of p12I residing in the plasma membrane, where it contributes to T-cell deactivation and participates in cellular conduits, enhancing virus transmission. p13II associates with the inner mitochondrial membrane, where it is proposed to function as a potassium channel. Potassium influx through p13II in the matrix causes membrane depolarization and triggers processes that lead to either T-cell activation or cell death through apoptosis.
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Affiliation(s)
- Elka R Georgieva
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
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5
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Silic-Benussi M, Scattolin G, Cavallari I, Minuzzo S, Del Bianco P, Francescato S, Basso G, Indraccolo S, D'Agostino DM, Ciminale V. Selective killing of human T-ALL cells: an integrated approach targeting redox homeostasis and the OMA1/OPA1 axis. Cell Death Dis 2018; 9:822. [PMID: 30069011 PMCID: PMC6070521 DOI: 10.1038/s41419-018-0870-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 06/06/2018] [Accepted: 07/11/2018] [Indexed: 01/18/2023]
Abstract
Approximately 20% of pediatric T-cell acute lymphoblastic leukemia (T-ALL) patients are currently incurable due to primary or secondary resistance to glucocorticoid-based therapies. Here we employed an integrated approach to selectively kill T-ALL cells by increasing mitochondrial reactive oxygen species (ROS) using NS1619, a benzimidazolone that activates the K+ (BK) channel, and dehydroepiandrosterone (DHEA), which blunts ROS scavenging through inhibition of the pentose phosphate pathway. These compounds selectively killed T-ALL cell lines, patient-derived xenografts and primary cells from patients with refractory T-ALL, but did not kill normal human thymocytes. T-ALL cells treated with NS1619 and DHEA showed activation of the ROS-responsive transcription factor NRF2, indicating engagement of antioxidant pathways, as well as increased cleavage of OPA1, a mitochondrial protein that promotes mitochondrial fusion and regulates apoptosis. Consistent with these observations, transmission electron microscopy analysis indicated that NS1619 and DHEA increased mitochondrial fission. OPA1 cleavage and cell death were inhibited by ROS scavengers and by siRNA-mediated knockdown of the mitochondrial protease OMA1, indicating the engagement of a ROS-OMA1-OPA1 axis in T-ALL cells. Furthermore, NS1619 and DHEA sensitized T-ALL cells to TRAIL-induced apoptosis. In vivo, the combination of dexamethasone and NS1619 significantly reduced the growth of a glucocorticoid-resistant patient-derived T-ALL xenograft. Taken together, our findings provide proof-of-principle for an integrated ROS-based pharmacological approach to target refractory T-ALL.
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Affiliation(s)
- Micol Silic-Benussi
- Veneto Institute of Oncology IOV - IRCCS, Padua, Italy.,Department of Surgery, Oncology, and Gastroenterology, University of Padova, via Gattamelata 64, 35128, Padova, Italy
| | - Gloria Scattolin
- Department of Surgery, Oncology, and Gastroenterology, University of Padova, via Gattamelata 64, 35128, Padova, Italy
| | | | - Sonia Minuzzo
- Department of Surgery, Oncology, and Gastroenterology, University of Padova, via Gattamelata 64, 35128, Padova, Italy
| | | | - Samuela Francescato
- Haemato-Oncology Division, Department of Woman and Child Health, University of Padova, via Giustiniani 3, 35128, Padova, Italy
| | - Giuseppe Basso
- Haemato-Oncology Division, Department of Woman and Child Health, University of Padova, via Giustiniani 3, 35128, Padova, Italy
| | | | - Donna M D'Agostino
- Department of Biomedical Sciences, University of Padova, via Ugo Bassi 58/B, 35131, Padova, Italy
| | - Vincenzo Ciminale
- Veneto Institute of Oncology IOV - IRCCS, Padua, Italy. .,Department of Surgery, Oncology, and Gastroenterology, University of Padova, via Gattamelata 64, 35128, Padova, Italy.
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6
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Lee H, Cho YY, Lee GY, You D, Yoo YD, Kim YJ. A direct role for hepatitis B virus X protein in inducing mitochondrial membrane permeabilization. J Viral Hepat 2018; 25:412-420. [PMID: 29193612 PMCID: PMC7167162 DOI: 10.1111/jvh.12831] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 10/14/2017] [Indexed: 01/03/2023]
Abstract
Hepatitis B virus X protein (HBx) acts as a multifunctional protein that regulates intracellular signalling pathways during HBV infection. It has mainly been studied in terms of its interaction with cellular proteins. Here, we show that HBx induces membrane permeabilization independently of the mitochondrial permeability transition pore complex. We generated mitochondrial outer membrane-mimic liposomes to observe the direct effects of HBx on membranes. We found that HBx induced membrane permeabilization, and the region comprising the transmembrane domain and the mitochondrial-targeting sequence was sufficient for this process. Membrane permeabilization was inhibited by nonselective channel blockers or by N-(n-nonyl)deoxynojirimycin (NN-DNJ), a viroporin inhibitor. Moreover, NN-DNJ inhibited HBx-induced mitochondrial depolarization in Huh-7 cells. Based on the results of this study, we can postulate that the HBx protein itself is sufficient to induce mitochondrial membrane permeabilization. Our finding provides important information for a strategy of HBx targeting during HBV treatment.
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Affiliation(s)
- H‐R. Lee
- Laboratory of Molecular Cell BiologyGraduate School of MedicineKorea University College of MedicineKorea UniversitySeoulKorea,Department of Biosystems and BiotechnologyCollege of Life Sciences and BiotechnologyKorea UniversitySeoulKorea
| | - Y. Y. Cho
- Department of Internal Medicine and Liver Research InstituteSeoul National University College of MedicineSeoulKorea
| | - G. Y. Lee
- Laboratory of Molecular Cell BiologyGraduate School of MedicineKorea University College of MedicineKorea UniversitySeoulKorea
| | - D‐g. You
- Laboratory of Molecular Cell BiologyGraduate School of MedicineKorea University College of MedicineKorea UniversitySeoulKorea
| | - Y. D. Yoo
- Laboratory of Molecular Cell BiologyGraduate School of MedicineKorea University College of MedicineKorea UniversitySeoulKorea
| | - Y. J. Kim
- Department of Internal Medicine and Liver Research InstituteSeoul National University College of MedicineSeoulKorea
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7
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Cavallari I, Scattolin G, Silic-Benussi M, Raimondi V, D'Agostino DM, Ciminale V. Mitochondrial Proteins Coded by Human Tumor Viruses. Front Microbiol 2018; 9:81. [PMID: 29467726 PMCID: PMC5808139 DOI: 10.3389/fmicb.2018.00081] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 01/12/2018] [Indexed: 12/26/2022] Open
Abstract
Viruses must exploit the cellular biosynthetic machinery and evade cellular defense systems to complete their life cycles. Due to their crucial roles in cellular bioenergetics, apoptosis, innate immunity and redox balance, mitochondria are important functional targets of many viruses, including tumor viruses. The present review describes the interactions between mitochondria and proteins coded by the human tumor viruses human T-cell leukemia virus type 1, Epstein-Barr virus, Kaposi's sarcoma-associated herpesvirus, human hepatitis viruses B and C, and human papillomavirus, and highlights how these interactions contribute to viral replication, persistence and transformation.
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Affiliation(s)
| | - Gloria Scattolin
- Department of Surgery, Oncology, and Gastroenterology, University of Padova, Padova, Italy
| | | | | | | | - Vincenzo Ciminale
- Veneto Institute of Oncology IOV-IRRCS, Padova, Italy.,Department of Surgery, Oncology, and Gastroenterology, University of Padova, Padova, Italy
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8
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You DG, Lee HR, Kim WK, Kim HJ, Lee GY, Yoo YD. Hepatitis C virus p7 induces mitochondrial depolarization of isolated liver mitochondria. Mol Med Rep 2017; 16:9533-9538. [PMID: 29039530 DOI: 10.3892/mmr.2017.7809] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 03/20/2017] [Indexed: 11/06/2022] Open
Abstract
Hepatitis C virus (HCV)‑encoded protein p7 is a viroporin that acts as an ion channel and is indispensable for HCV particle production. Although the main target of HCV p7 is the endoplasmic reticulum, it also targets mitochondria. HCV‑infected cells show mitochondrial depolarization and ATP depletion; however, the function of HCV p7 in mitochondria is not fully understood. The present study demonstrated that treatment of isolated mouse liver mitochondria with the synthesized HCV p7 protein induced mitochondrial dysfunction. It also demonstrated that HCV p7 targeted isolated mouse liver mitochondria and induced mitochondrial depolarization. In addition, HCV p7 triggered matrix acidification and, ultimately, a decrease in ATP synthesis in isolated mitochondria. These findings indicate that targeting of mitochondria by HCV p7 in infected cells causes mitochondrial dysfunction to support HCV particle production. The present study provided evidence for the role of HCV p7 in mitochondria, and may lead to the development of novel strategies for HCV therapy.
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Affiliation(s)
- Deok-Gyun You
- Laboratory of Molecular Cell Biology, Graduate School of Medicine, College of Medicine, Korea University, Seoul 02841, Republic of Korea
| | - Hye-Ra Lee
- Laboratory of Molecular Cell Biology, Graduate School of Medicine, College of Medicine, Korea University, Seoul 02841, Republic of Korea
| | - Won-Ki Kim
- Department of Neuroscience, College of Medicine, Korea University, Seoul 02841, Republic of Korea
| | - Hyung Jung Kim
- Department of Internal Medicine, Yonsei University College of Medicine, Yonsei University Health System, Seoul 03722, Republic of Korea
| | - Gi Young Lee
- Laboratory of Molecular Cell Biology, Graduate School of Medicine, College of Medicine, Korea University, Seoul 02841, Republic of Korea
| | - Young Do Yoo
- Laboratory of Molecular Cell Biology, Graduate School of Medicine, College of Medicine, Korea University, Seoul 02841, Republic of Korea
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9
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Abstract
Eukaryotic cells have evolved a myriad of ion channels, transporters, and pumps to maintain and regulate transmembrane ion gradients. As intracellular parasites, viruses also have evolved ion channel proteins, called viroporins, which disrupt normal ionic homeostasis to promote viral replication and pathogenesis. The first viral ion channel (influenza M2 protein) was confirmed only 23 years ago, and since then studies on M2 and many other viroporins have shown they serve critical functions in virus entry, replication, morphogenesis, and immune evasion. As new candidate viroporins and viroporin-mediated functions are being discovered, we review the experimental criteria for viroporin identification and characterization to facilitate consistency within this field of research. Then we review recent studies on how the few Ca(2+)-conducting viroporins exploit host signaling pathways, including store-operated Ca(2+) entry, autophagy, and inflammasome activation. These viroporin-induced aberrant Ca(2+) signals cause pathophysiological changes resulting in diarrhea, vomiting, and proinflammatory diseases, making both the viroporin and host Ca(2+) signaling pathways potential therapeutic targets for antiviral drugs.
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Affiliation(s)
- Joseph M Hyser
- Alkek Center for Metagenomic and Microbiome Research.,Department of Molecular Virology and Microbiology, and
| | - Mary K Estes
- Department of Molecular Virology and Microbiology, and.,Department of Medicine, Baylor College of Medicine, Houston, Texas 77030-3411;
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10
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Discovery and characterization of auxiliary proteins encoded by type 3 simian T-cell lymphotropic viruses. J Virol 2014; 89:931-51. [PMID: 25355890 DOI: 10.1128/jvi.02150-14] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
UNLABELLED Human T-cell lymphotropic virus type 1 (HTLV-1) and HTLV-2 encode auxiliary proteins that play important roles in viral replication, viral latency, and immune escape. The presence of auxiliary protein-encoding open reading frames (ORFs) in HTLV-3, the latest HTLV to be discovered, is unknown. Simian T-cell lymphotropic virus type 3 (STLV-3) is almost identical to HTLV-3. Given the lack of HTLV-3-infected cell lines, we took advantage of STLV-3-infected cells and of an STLV-3 molecular clone to search for the presence of auxiliary transcripts. Using reverse transcriptase PCR (RT-PCR), we first uncovered the presence of three unknown viral mRNAs encoding putative proteins of 5, 8, and 9 kDa and confirmed the presence of the previously reported RorfII transcript. The existence of these viral mRNAs was confirmed by using splice site-specific RT-PCR with ex vivo samples. We showed that p5 is distributed throughout the cell and does not colocalize with a specific organelle. The p9 localization is similar to that of HTLV-1 p12 and induced a strong decrease in the calreticulin signal, similarly to HTLV-1 p12. Although p8, RorfII, and Rex-3 share an N-terminal sequence that is predicted to contain a nucleolar localization signal (NoLS), only p8 is found in the nucleolus. The p8 location in the nucleolus is linked to a bipartite NoLS. p8 and, to a lesser extent, p9 repressed viral expression but did not alter Rex-3-dependent mRNA export. Using a transformation assay, we finally showed that none of the STLV-3 auxiliary proteins had the ability to induce colony formation, while both Tax-3 and antisense protein of HTLV-3 (APH-3) promoted cellular transformation. Altogether, these results complete the characterization of the newly described primate T-lymphotropic virus type 3 (PTLV-3). IMPORTANCE Together with their simian counterparts, HTLVs form the primate T-lymphotropic viruses. HTLVs arose from interspecies transmission between nonhuman primates and humans. HTLV-1 and HTLV-2 encode auxiliary proteins that play important roles in viral replication, viral latency, and immune escape. The presence of ORFs encoding auxiliary proteins in HTLV-3 or STLV-3 genomes was unknown. Using in silico analyses, ex vivo samples, or in vitro experiments, we have uncovered the presence of 3 previously unknown viral mRNAs encoding putative proteins and confirmed the presence of a previously reported viral transcript. We characterized the intracellular localization of the four proteins. We showed that two of these proteins repress viral expression but that none of them have the ability to induce colony formation. However, both Tax and the antisense protein APH-3 promote cell transformation. Our results allowed us to characterize 4 new retroviral proteins for the first time.
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Choi YB, Harhaj EW. Functional implications of mitochondrial reactive oxygen species generated by oncogenic viruses. ACTA ACUST UNITED AC 2014; 9:423-436. [PMID: 25580106 DOI: 10.1007/s11515-014-1332-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Between 15-20% of human cancers are associated with infection by oncogenic viruses. Oncogenic viruses, including HPV, HBV, HCV and HTLV-1, target mitochondria to influence cell proliferation and survival. Oncogenic viral gene products also trigger the production of reactive oxygen species which can elicit oxidative DNA damage and potentiate oncogenic host signaling pathways. Viral oncogenes may also subvert mitochondria quality control mechanisms such as mitophagy and metabolic adaptation pathways to promote virus replication. Here, we will review recent progress on viral regulation of mitophagy and metabolic adaptation and their roles in viral oncogenesis.
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Affiliation(s)
- Young Bong Choi
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns HopkinsSchool of Medicine, Baltimore, MD 21287, USA
| | - Edward William Harhaj
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns HopkinsSchool of Medicine, Baltimore, MD 21287, USA
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12
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Anand SK, Tikoo SK. Viruses as modulators of mitochondrial functions. Adv Virol 2013; 2013:738794. [PMID: 24260034 PMCID: PMC3821892 DOI: 10.1155/2013/738794] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 08/30/2013] [Indexed: 02/07/2023] Open
Abstract
Mitochondria are multifunctional organelles with diverse roles including energy production and distribution, apoptosis, eliciting host immune response, and causing diseases and aging. Mitochondria-mediated immune responses might be an evolutionary adaptation by which mitochondria might have prevented the entry of invading microorganisms thus establishing them as an integral part of the cell. This makes them a target for all the invading pathogens including viruses. Viruses either induce or inhibit various mitochondrial processes in a highly specific manner so that they can replicate and produce progeny. Some viruses encode the Bcl2 homologues to counter the proapoptotic functions of the cellular and mitochondrial proteins. Others modulate the permeability transition pore and either prevent or induce the release of the apoptotic proteins from the mitochondria. Viruses like Herpes simplex virus 1 deplete the host mitochondrial DNA and some, like human immunodeficiency virus, hijack the host mitochondrial proteins to function fully inside the host cell. All these processes involve the participation of cellular proteins, mitochondrial proteins, and virus specific proteins. This review will summarize the strategies employed by viruses to utilize cellular mitochondria for successful multiplication and production of progeny virus.
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Affiliation(s)
- Sanjeev K. Anand
- Vaccine & Infection Disease Organization-International Vaccine Center (VIDO-InterVac), University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, Canada S7E 5E3
- Veterinary Microbiology, University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, Canada S7E 5E3
| | - Suresh K. Tikoo
- Vaccine & Infection Disease Organization-International Vaccine Center (VIDO-InterVac), University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, Canada S7E 5E3
- Veterinary Microbiology, University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, Canada S7E 5E3
- School of Public Health, University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, Canada S7E 5E3
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13
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Lai D, Tan CL, Gunaratne J, Quek LS, Nei W, Thierry F, Bellanger S. Localization of HPV-18 E2 at mitochondrial membranes induces ROS release and modulates host cell metabolism. PLoS One 2013; 8:e75625. [PMID: 24086592 PMCID: PMC3782431 DOI: 10.1371/journal.pone.0075625] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 08/19/2013] [Indexed: 02/05/2023] Open
Abstract
Papillomavirus E2 proteins are predominantly retained in the nuclei of infected cells, but oncogenic (high-risk) HPV-18 and 16 E2 can shuttle between the host nucleus and cytoplasm. We show here that cytoplasmic HPV-18 E2 localizes to mitochondrial membranes, and independent mass spectrometry analyses of the E2 interactome revealed association to the inner mitochondrial membrane including components of the respiratory chain. Mitochondrial E2 association modifies the cristae morphology when analyzed by electron microscopy and increases production of mitochondrial ROS. This ROS release does not induce apoptosis, but instead correlates with stabilization of HIF-1α and increased glycolysis. These mitochondrial functions are not shared by the non-oncogenic (low-risk) HPV-6 E2 protein, suggesting that modification of cellular metabolism by high-risk HPV E2 proteins could play a role in carcinogenesis by inducing the Warburg effect.
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Affiliation(s)
- Deborah Lai
- Papillomavirus Regulation and Cancer, Institute of Medical Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Chye Ling Tan
- Papillomavirus Regulation and Cancer, Institute of Medical Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Jayantha Gunaratne
- Quantitative Proteomics Group, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Ling Shih Quek
- Papillomavirus Regulation and Cancer, Institute of Medical Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Wenlong Nei
- Papillomavirus Regulation and Cancer, Institute of Medical Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Françoise Thierry
- Papillomavirus Regulation and Cancer, Institute of Medical Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Sophie Bellanger
- Papillomavirus Regulation and Cancer, Institute of Medical Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
- * E-mail:
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Bai XT, Nicot C. Overview on HTLV-1 p12, p8, p30, p13: accomplices in persistent infection and viral pathogenesis. Front Microbiol 2012; 3:400. [PMID: 23248621 PMCID: PMC3518833 DOI: 10.3389/fmicb.2012.00400] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Indexed: 12/29/2022] Open
Abstract
The human T-lymphotropic virus type-1 (HTLV-1) is etiologically linked to adult T cell leukemia/lymphoma and tropical spastic paraparesis/HTLV-1-associated myelopathy. While the role of Tax and Rex in viral replication and pathogenesis has been extensively studied, recent evidence suggests that additional viral proteins are essential for the virus life cycle in vivo. In this review, we will summarize possible molecular mechanisms evoked in the literature to explain how p12, p8, p30, and p13 facilitate persistent viral infection of the host. We will explore several stratagems used by HTLV-1 accessory genes to escape immune surveillance, to establish latency, and to deregulate cell cycle and apoptosis to participate in virus-mediated cellular transformation.
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Affiliation(s)
- Xue Tao Bai
- Department of Pathology and Laboratory Medicine, University of Kansas Medical Center Kansas City, KS, USA
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Nakano K, Watanabe T. HTLV-1 Rex: the courier of viral messages making use of the host vehicle. Front Microbiol 2012; 3:330. [PMID: 22973269 PMCID: PMC3434621 DOI: 10.3389/fmicb.2012.00330] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 08/24/2012] [Indexed: 01/25/2023] Open
Abstract
The human T-cell leukemia virus type 1 (HTLV-1) is a retrovirus causing an aggressive T-cell malignancy, adult T-cell leukemia (ATL). Although HTLV-1 has a compact RNA genome, it has evolved elaborate mechanisms to maximize its coding potential. The structural proteins Gag, Pro, and Pol are encoded in the unspliced form of viral mRNA, whereas the Env protein is encoded in singly spliced viral mRNA. Regulatory and accessory proteins, such as Tax, Rex, p30II, p12, and p13, are translated only from fully spliced mRNA. For effective viral replication, translation from all forms of HTLV-1 transcripts has to be achieved in concert, although unspliced mRNA are extremely unstable in mammalian cells. It has been well recognized that HTLV-1 Rex enhances the stability of unspliced and singly spliced HTLV-1 mRNA by promoting nuclear export and thereby removing them from the splicing site. Rex specifically binds to the highly structured Rex responsive element (RxRE) located at the 3' end of all HTLV-1 mRNA. Rex then binds to the cellular nuclear exporter, CRM1, via its nuclear export signal domain and the Rex-viral transcript complex is selectively exported from the nucleus to the cytoplasm for effective translation of the viral proteins. Yet, the mechanisms by which Rex inhibits the cellular splicing machinery and utilizes the cellular pathways beneficial to viral survival in the host cell have not been fully explored. Furthermore, physiological impacts of Rex against homeostasis of the host cell via interactions with numerous cellular proteins have been largely left uninvestigated. In this review, we focus on the biological importance of HTLV-1 Rex in the HTLV-1 life cycle by following the historical path in the literature concerning this viral post-transcriptional regulator from its discovery to this day. In addition, for future studies, we discuss recently discovered aspects of HTLV-1 Rex as a post-transcriptional regulator and its use in host cellular pathways.
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Affiliation(s)
- Kazumi Nakano
- Laboratory of Tumor Cell Biology, Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo Tokyo, Japan
| | - Toshiki Watanabe
- Laboratory of Tumor Cell Biology, Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo Tokyo, Japan
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Abstract
Viroporins are small virally encoded hydrophobic proteins that oligomerize in the membrane of host cells, leading to the formation of hydrophilic pores. This activity modifies several cellular functions, including membrane permeability, Ca2+ homeostasis, membrane remodelling and glycoprotein trafficking. A classification scheme for viroporins is proposed on the basis of their structure and membrane topology. Thus, class I and class II viroporins are defined according to the number of transmembrane domains in the protein (one and two, respectively), and subclasses are defined according to their orientation in the membrane. The main function of viroporins during viral replication is to participate in virion morphogenesis and release from host cells. In addition, some viroporins are involved in viral entry and genome replication. The structure and activity of several viroporins, such as picornavirus protein 2B (P2B), influenza A virus matrix protein 2 (M2), hepatitis C virus p7 and HIV-1 viral protein U (Vpu), have been analysed in detail. New members of this expanding family of viral proteins have been described, from both RNA and DNA viruses. In addition to having a common general structure, all of these new viroporins have the ability to increase membrane permeability. Viroporins represent ideal targets to block viral replication and the spread of infection. Although a number of selective inhibitors of viroporin ion channels have been analysed in detail, optimized screening systems promise to provide new and more potent antiviral compounds in the near future.
Viroporins belong to a growing family of virally encoded proteins that form aqueous channels in the membranes of host cells. Here, Carrasco and colleagues review the structure and diverse biological functions of these proteins during the viral life cycle, as well as their potential as antiviral therapeutic targets. Viroporins are small, hydrophobic proteins that are encoded by a wide range of clinically relevant animal viruses. When these proteins oligomerize in host cell membranes, they form hydrophilic pores that disrupt a number of physiological properties of the cell. Viroporins are crucial for viral pathogenicity owing to their involvement in several diverse steps of the viral life cycle. Thus, these viral proteins, which include influenza A virus matrix protein 2 (M2), HIV-1 viral protein U (Vpu) and hepatitis C virus p7, represent ideal targets for therapeutic intervention, and several compounds that block their pore-forming activity have been identified. Here, we review recent studies in the field that have advanced our knowledge of the structure and function of this expanding family of viral proteins.
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Olière S, Douville R, Sze A, Belgnaoui SM, Hiscott J. Modulation of innate immune responses during human T-cell leukemia virus (HTLV-1) pathogenesis. Cytokine Growth Factor Rev 2011; 22:197-210. [DOI: 10.1016/j.cytogfr.2011.08.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Orf-I and orf-II-encoded proteins in HTLV-1 infection and persistence. Viruses 2011; 3:861-85. [PMID: 21994758 PMCID: PMC3185781 DOI: 10.3390/v3060861] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Revised: 05/25/2011] [Accepted: 05/26/2011] [Indexed: 01/10/2023] Open
Abstract
The 3′ end of the human T-cell leukemia/lymphoma virus type-1 (HTLV-1) genome contains four overlapping open reading frames (ORF) that encode regulatory proteins. Here, we review current knowledge of HTLV-1 orf-I and orf-II protein products. Singly spliced mRNA from orf-I encodes p12, which can be proteolytically cleaved to generate p8, while differential splicing of mRNA from orf-II results in production of p13 and p30. These proteins have been demonstrated to modulate transcription, apoptosis, host cell activation and proliferation, virus infectivity and transmission, and host immune responses. Though these proteins are not essential for virus replication in vitro, p8, p12, p13, and p30 have an important role in the establishment and maintenance of HTLV-1 infection in vivo.
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Van Prooyen N, Andresen V, Gold H, Bialuk I, Pise-Masison C, Franchini G. Hijacking the T-cell communication network by the human T-cell leukemia/lymphoma virus type 1 (HTLV-1) p12 and p8 proteins. Mol Aspects Med 2010; 31:333-43. [PMID: 20673780 DOI: 10.1016/j.mam.2010.07.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Revised: 07/22/2010] [Accepted: 07/23/2010] [Indexed: 12/14/2022]
Abstract
The non-structural proteins encoded by the orf-I, II, III, and IV genes of the human T-cell leukemia/lymphoma virus type 1 (HTLV-1) genome, are critical for the modulation of cellular gene expression and T-cell proliferation, the escape from cytotoxic T-cells and natural killer cells, and virus expression. In here, we review the main functions of the HTLV-1 orf-I products. The 12kDa product from orf-I (p12) is proteolytically cleaved within the endoplasmic reticulum (ER) to generate the 8kDa protein (p8). At the steady state, both proteins are expressed at similar levels in transfected T-cells. The p12 protein remains in the ER and cis-Golgi, whereas the p8 protein traffics to the cell surface and is recruited to the immunological synapse. The p12 and the p8 proteins have seemingly opposite effects on T-cells; the ER resident p12, modulates T-cell activation and proliferation, whereas p8 induces T-cell anergy. The p8 protein also increases the formation of cellular conduits, is transferred to neighboring T-cells, and increases virus transmission. The requirement for HTLV-1 infectivity of orf-I is demonstrated by the loss of virus infectivity in macaques exposed to an engineered virus, whereby expression of orf-I was ablated. Altogether the current knowledge demonstrates that the concerted activity of p8 and p12 is essential for the persistence of virus infected cells in the host.
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Affiliation(s)
- Nancy Van Prooyen
- Animal Models and Retroviral Vaccine Section, Vaccine Branch, National Cancer Institute, National Institute of Health, Bethesda, MD 20892-5065, USA
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Redox regulation of T-cell turnover by the p13 protein of human T-cell leukemia virus type 1: distinct effects in primary versus transformed cells. Blood 2010; 116:54-62. [DOI: 10.1182/blood-2009-07-235861] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
AbstractThe present study investigated the function of p13, a mitochondrial protein of human T-cell leukemia virus type 1 (HTLV-1). Although necessary for viral propagation in vivo, the mechanism of function of p13 is incompletely understood. Drawing from studies in isolated mitochondria, we analyzed the effects of p13 on mitochondrial reactive oxygen species (ROS) in transformed and primary T cells. In transformed cells (Jurkat, HeLa), p13 did not affect ROS unless the cells were subjected to glucose deprivation, which led to a p13-dependent increase in ROS and cell death. Using RNA interference we confirmed that expression of p13 also influences glucose starvation-induced cell death in the context of HTLV-1–infected cells. ROS measurements showed an increasing gradient from resting to mitogen-activated primary T cells to transformed T cells (Jurkat). Expression of p13 in primary T cells resulted in their activation, an effect that was abrogated by ROS scavengers. These findings suggest that p13 may have a distinct impact on cell turnover depending on the inherent ROS levels; in the context of the HTLV-1 propagation strategy, p13 could increase the pool of “normal” infected cells while culling cells acquiring a transformed phenotype, thus favoring lifelong persistence of the virus in the host.
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