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Zhang X, Yan LN, Liu BY, Zhou CM, Yu XJ. The hnRNP A2B1 is important for the replication of SFTSV and other RNA viruses. Microbiol Spectr 2024:e0082924. [PMID: 39166862 DOI: 10.1128/spectrum.00829-24] [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: 04/02/2024] [Accepted: 07/27/2024] [Indexed: 08/23/2024] Open
Abstract
The heterogeneous nuclear ribonucleoprotein (hnRNP A2B1) is a key component of the hnRNP complex involving RNA modulation in eukaryotic cells and it has also been reported to be involved in the replication of the hepatitis E virus, influenza A virus, and hepatitis B virus. However, it is not clear whether the role of the hnRNP A2B1 in viral replication is conserved among RNA viruses and what is the mechanism of hnRNP A2B1 in RNA virus replication. In this study, we first used severe fever with thrombocytopenia syndrome virus (SFTSV), a tick-borne RNA virus that causes a severe viral hemorrhagic fever as well as other RNA viruses including VSV-GFP, SeV, EV71, and ZIKV to demonstrate that knockout hnRNPA2B1 gene inhibited viral RNA replication and overexpression of hnRNP A2B1 could restore the RNA levels of all tested RNA viruses. These results suggest that hnRNPA2B1 upregulation of viral replication is conserved among RNA viruses. Next, we demonstrated that hnRNP A2B1 was translocated from the nucleus to the cytoplasm under RNA virus infection including SFTSV, VSV-GFP, SeV, EV71, and ZIKV, suggesting translocation of hnRNP A2B1 from the nucleus to the cytoplasm is crucial for RNA virus replication. We then used SFTSV as a model to demonstrate the mechanism of hnRNP A2B1 in the promotion of RNA virus replication. We found that overexpression of SFTSV nucleoprotein can also cause hnRNP A2B1 translocation from the nucleus to the cytoplasm and that the SFTSV NP interacted with the RNA recognition motif 1 domain of hnRNP A2B1. We further demonstrated that the hnRNP A2B1 interacted with the 5' UTR of SFTSV RNA. In conclusion, we revealed that the hnRNP A2B1 upregulation of viral RNA replication is conserved among RNA viruses; the mechanism of hnRNP A2B1 in promotion of SFTSV viral RNA replication is that SFTSV NP interacted with the hnRNPA2B1 to retain it in the cytoplasm where the hnRNP A2B1 interacted with the 5' UTR of SFTSV RNA to promote the viral RNA replication.IMPORTANCESevere fever with thrombocytopenia syndrome virus (SFTSV) is a tick-borne RNA virus with a high mortality rate of up to 30%. In this study, we first used SFTSV as a model to demonstrate that the role of hnRNPA2B1 in viral replication is conserved in SFTSV. Then we used other RNA viruses, including VSV-GFP, SeV, EV71, and ZIKV, to repeat the experiment and demonstrated the same results as SFTSV in all tested RNA viruses. By knocking out the hnRNPA2B1 gene, SFTSV RNA replication was inhibited, and overexpression of hnRNPA2B1 restored RNA levels of SFTSV and other tested RNA viruses. We revealed a novel mechanism where the SFTSV nucleoprotein interacts with hnRNPA2B1, retaining it in the cytoplasm. This interaction promotes viral RNA replication by binding to the 5' UTR of SFTSV RNA. The findings suggest that targeting hnRNPA2B1 could be a potential strategy for developing broad-spectrum antiviral therapies, given its conserved role across different RNA viruses. This research provides significant insights into the replication mechanisms of RNA viruses and highlights potential targets for antiviral interventions.
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Affiliation(s)
- Xu Zhang
- State Key Laboratory of Virology, School of Public Health, Wuhan University, Wuhan, China
| | - Li-Na Yan
- Department of Infectious Diseases, Tangdu Hospital, Air Force Medical University, Xi'an, China
| | - Bin-Yan Liu
- Center for Environment and Health in Water Source Area of South-to-North Water Diversion, School of Public Health, Hubei University of Medicine, Shiyan, China
| | - Chuan-Min Zhou
- The First Hospital of Hebei Medical University, Shijiazhuang, China
| | - Xue-Jie Yu
- State Key Laboratory of Virology, School of Public Health, Wuhan University, Wuhan, China
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2
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Graham SV. HPV and RNA Binding Proteins: What We Know and What Remains to Be Discovered. Viruses 2024; 16:783. [PMID: 38793664 PMCID: PMC11126060 DOI: 10.3390/v16050783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Revised: 05/08/2024] [Accepted: 05/12/2024] [Indexed: 05/26/2024] Open
Abstract
Papillomavirus gene regulation is largely post-transcriptional due to overlapping open reading frames and the use of alternative polyadenylation and alternative splicing to produce the full suite of viral mRNAs. These processes are controlled by a wide range of cellular RNA binding proteins (RPBs), including constitutive splicing factors and cleavage and polyadenylation machinery, but also factors that regulate these processes, for example, SR and hnRNP proteins. Like cellular RNAs, papillomavirus RNAs have been shown to bind many such proteins. The life cycle of papillomaviruses is intimately linked to differentiation of the epithelial tissues the virus infects. For example, viral late mRNAs and proteins are expressed only in the most differentiated epithelial layers to avoid recognition by the host immune response. Papillomavirus genome replication is linked to the DNA damage response and viral chromatin conformation, processes which also link to RNA processing. Challenges with respect to elucidating how RBPs regulate the viral life cycle include consideration of the orchestrated spatial aspect of viral gene expression in an infected epithelium and the epigenetic nature of the viral episomal genome. This review discusses RBPs that control viral gene expression, and how the connectivity of various nuclear processes might contribute to viral mRNA production.
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Affiliation(s)
- Sheila V Graham
- MRC-University of Glasgow Centre for Virus Research, School of Infection and Immunity, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow G61 1QH, UK
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3
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Schwartz S, Wu C, Kajitani N. RNA elements that control human papillomavirus mRNA splicing-targets for therapy? J Med Virol 2024; 96:e29473. [PMID: 38362929 DOI: 10.1002/jmv.29473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 01/31/2024] [Accepted: 02/05/2024] [Indexed: 02/17/2024]
Abstract
Human papillomaviruses (HPVs) cause more than 4.5% of all cancer in the world and more than half of these cases are attributed to human papillomavirus type 16 (HPV16). Prophylactic vaccines are available but antiviral drugs are not. Novel targets for therapy are urgently needed. Alternative RNA splicing is extensively used by HPVs to express all their genes and HPV16 is no exception. This process must function to perfection since mis-splicing could perturb the HPV gene expression program by altering mRNA levels or by generating dysfunctional mRNAs. Cis-acting RNA elements on the viral mRNAs and their cognate cellular trans-acting factors control papillomavirus RNA splicing. The precise but delicate nature of the splicing process renders splicing sensitive to interference. As such, papillomavirus RNA splicing is a potential target for therapy. Here we summarize our current understanding of cis-acting HPV16 RNA elements that control HPV16 mRNA splicing via cellular proteins and discuss how they may be exploited as targets for therapy to papillomavirus infections and cancer.
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Affiliation(s)
- Stefan Schwartz
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Chengjun Wu
- School of Health and Life Sciences, University of Health and Rehabilitation Sciences, Qingdao, China
| | - Naoko Kajitani
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
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4
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Kirk A, Graham SV. The human papillomavirus late life cycle and links to keratinocyte differentiation. J Med Virol 2024; 96:e29461. [PMID: 38345171 DOI: 10.1002/jmv.29461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 12/21/2023] [Accepted: 01/25/2024] [Indexed: 02/15/2024]
Abstract
Regulation of human papillomavirus (HPV) gene expression is tightly linked to differentiation of the keratinocytes the virus infects. HPV late gene expression is confined to the cells in the upper layers of the epithelium where the virus capsid proteins are synthesized. As these proteins are highly immunogenic, and the upper epithelium is an immune-privileged site, this spatial restriction aids immune evasion. Many decades of work have contributed to the current understanding of how this restriction occurs at a molecular level. This review will examine what is known about late gene expression in HPV-infected lesions and will dissect the intricacies of late gene regulation. Future directions for novel antiviral approaches will be highlighted.
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Affiliation(s)
- Anna Kirk
- Centre for Virus Research, University of Glasgow, Glasgow, UK
| | - Sheila V Graham
- Centre for Virus Research, University of Glasgow, Glasgow, UK
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5
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Zhang L, Ma J, Zhou D, Zhou J, Hu B, Ma X, Tang J, Bai Y, Chen H, Jing Y. Single-Nucleus Transcriptome Profiling of Locally Advanced Cervical Squamous Cell Cancer Identifies Neural-Like Progenitor Program Associated with the Efficacy of Radiotherapy. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2300348. [PMID: 37424047 PMCID: PMC10477877 DOI: 10.1002/advs.202300348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 05/23/2023] [Indexed: 07/11/2023]
Abstract
Radiotherapy is the first-line treatment for locally advanced cervical squamous cell cancer (CSCC). However, ≈50% of patients fail to respond to therapy and, in some cases, tumors progress after radical radiotherapy. Here, single-nucleus RNA-seq is performed to construct high-resolution molecular landscapes of various cell types in CSCC before and during radiotherapy, to better understand radiotherapy related molecular responses within tumor microenvironment. The results show that expression levels of a neural-like progenitor (NRP) program in tumor cells are significantly higher after radiotherapy and these are enriched in the tumors of nonresponding patients. The enrichment of the NRP program in malignant cells from the tumors of nonresponders in an independent cohort analyzed by bulk RNA-seq is validated. In addition, an analysis of The Cancer Genome Atlas dataset shows that NRP expression is associated with poor prognosis in CSCC patients. In vitro experiments on the CSCC cell line demonstrate that downregulation of neuregulin 1 (NRG1), a key gene from NRP program, is associated with decreased cell growth and increased sensitivity to radiation. Immunohistochemistry staining in cohort 3 validated key genes, NRG1 and immediate early response 3 from immunomodulatory program, as radiosensitivity regulators. The findings reveal that the expression of NRP in CSCC can be used to predict the efficacy of radiotherapy.
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Affiliation(s)
- Lei Zhang
- Department of Radiation OncologyRenji HospitalSchool of MedicineShanghai Jiao Tong UniversityShanghai200127China
| | - Jun Ma
- Eye InstituteEye & ENT HospitalShanghai Medical CollegeFudan UniversityShanghai200031China
| | - Di Zhou
- Department of Radiation OncologyRenji HospitalSchool of MedicineShanghai Jiao Tong UniversityShanghai200127China
| | - Junjun Zhou
- Department of Radiation OncologyRenji HospitalSchool of MedicineShanghai Jiao Tong UniversityShanghai200127China
| | - Bin Hu
- Department of Radiation OncologyRenji HospitalSchool of MedicineShanghai Jiao Tong UniversityShanghai200127China
| | - Xiumei Ma
- Department of Radiation OncologyRenji HospitalSchool of MedicineShanghai Jiao Tong UniversityShanghai200127China
| | - Jianming Tang
- Department of Radiation OncologyThe First Hospital of Lanzhou UniversityLanzhou UniversityLanzhou730000China
| | - Yongrui Bai
- Department of Radiation OncologyRenji HospitalSchool of MedicineShanghai Jiao Tong UniversityShanghai200127China
| | - Haiyan Chen
- Department of Radiation OncologyRenji HospitalSchool of MedicineShanghai Jiao Tong UniversityShanghai200127China
| | - Ying Jing
- Center for Intelligent Medicine ResearchGreater Bay Area Institute of Precision Medicine (Guangzhou)Fudan UniversityGuangzhou511458China
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6
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Hao L, Zhang J, Liu Z, Zhang Z, Mao T, Guo J. Role of the RNA-binding protein family in gynecologic cancers. Am J Cancer Res 2023; 13:3799-3821. [PMID: 37693158 PMCID: PMC10492115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Accepted: 08/15/2023] [Indexed: 09/12/2023] Open
Abstract
Gynecological cancers pose a threat to women's health. Although early-stage gynecological cancers show good outcomes after standardized treatment, the prognosis of patients with advanced, met-astatic, and recurrent cancers is poor. RNA-binding proteins (RBPs) are important cellular proteins that interact with RNA through RNA-binding domains and participate extensively in post-transcriptional regulatory processes, such as mRNA alternative splicing, polyadenylation, intracellular localization and stability, and translation. Abnormal RBP expression affects the normal function of oncogenes and tumor suppressor genes in many malignancies, thus leading to the occurrence or progression of cancers. Similarly, RBPs play crucial roles in gynecological carcinogenesis. We summarize the role of RBPs in gynecological malignancies and explore their potential in the diagnosis and treatment of cancers. The findings summarized in this review may provide a guide for future research on the functions of RBPs.
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Affiliation(s)
- Linlin Hao
- Department of Tumor Radiotherapy, The Second Hospital of Jilin UniversityChangchun 130041, Jilin, China
| | - Jian Zhang
- School of Life Sciences, Department of Biology, Southern University of Science and TechnologyShenzhen 518055, Guangdong, China
| | - Zhongshan Liu
- Department of Tumor Radiotherapy, The Second Hospital of Jilin UniversityChangchun 130041, Jilin, China
| | - Zhiliang Zhang
- Department of Tumor Radiotherapy, The Second Hospital of Jilin UniversityChangchun 130041, Jilin, China
| | - Tiezhu Mao
- Department of Tumor Radiotherapy, The Second Hospital of Jilin UniversityChangchun 130041, Jilin, China
| | - Jie Guo
- Department of Tumor Radiotherapy, The Second Hospital of Jilin UniversityChangchun 130041, Jilin, China
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7
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Seaman WT, Madden V, Webster-Cyriaque J. HIVtat Alters Epithelial Differentiation State and Increases HPV16 Infectivity in Oral Keratinocytes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.08.531567. [PMID: 36945374 PMCID: PMC10028910 DOI: 10.1101/2023.03.08.531567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/10/2023]
Abstract
Human Papillomavirus (HPV)-associated oral disease has increased during the era of HIV antiretroviral therapy. HPV and HIV proteins may be co-present at mucosal surfaces. Recent published studies have determined that HIVtat is secreted in the saliva and has been detected in oral mucosa even in the context of antiretroviral therapy. We hypothesized that HIVtat promoted oral HPV pathogenesis. Clinical HPV16 cloned episomes were introduced into differentiated oral epithelial cells (OKF6tert1). HIVtat mediated transactivation, DNA damage, oxidative stress, and effects on cellular differentiation were assessed. Detection of keratin 10 and of loricrin confirmed terminal differentiation. Sodium butyrate-treated (NaB) cells demonstrated an eight-fold increase in cross-linked involucrin, suggesting full terminal differentiation. HIVtat modulated this differentiation both in the presence and absence of NaB. Later viral events, including E6* and E1^E4 gene expression were assessed. HIVtat mediated relief of repressed L1 expression that mapped to a known inhibitory region (nucleotides 5561-6820). Viruses from HIVtat co-expressing cells exhibited robust de novo HPV16 infection. In conclusion, a novel oral keratinocyte monolayer system supported replication of an HPV16 clinical isolate where direct HIVtat and oral HPV interactions enhanced HPV de novo infection.
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8
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Kim GN, Yu KL, Kim HI, You JC. Investigation of the effect of SRSF9 overexpression on HIV-1 production. BMB Rep 2022; 55:639-644. [PMID: 36330710 PMCID: PMC9813430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Indexed: 12/29/2022] Open
Abstract
Serine-arginine-rich splicing factors (SRSFs) are members of RNA processing proteins in the serine-arginine-rich (SR) family that could regulate the alternative splicing of the human immunodeficiency virus-1 (HIV-1). Whether SRSF9 has any effect on HIV-1 regulation requires elucidation. Here, we report for the first time the effects and mechanisms of SRSF9 on HIV-1 regulation. The overexpression of SRSF9 inhibits viral production and infectivity in both HEK293T and MT-4 cells. Deletion analysis of SRSF9 determined that the RNA regulation motif domain of SRSF9 is important for anti-HIV-1 effects. Furthermore, overexpression of SRSF9 increases multiple spliced forms of viral mRNA, such as Vpr mRNA. These data suggest that SRSF9 overexpression inhibits HIV-1 production by inducing the imbalanced HIV-1 mRNA splicing that could be exploited further for a novel HIV-1 therapeutic molecule. [BMB Reports 2022; 55(12): 639-644].
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Affiliation(s)
- Ga-Na Kim
- Department of Pathology, National Research Laboratory for Molecular Virology, College of Medicine, The Catholic University of Korea, Seoul 05505, Korea
| | - Kyung-Lee Yu
- Department of Pathology, National Research Laboratory for Molecular Virology, College of Medicine, The Catholic University of Korea, Seoul 05505, Korea
| | - Hae-In Kim
- Department of Pathology, National Research Laboratory for Molecular Virology, College of Medicine, The Catholic University of Korea, Seoul 05505, Korea
| | - Ji Chang You
- Department of Pathology, National Research Laboratory for Molecular Virology, College of Medicine, The Catholic University of Korea, Seoul 05505, Korea,Corresponding author. Tel: +82-2-3147-8734; Fax: +82-2-3147-9282; E-mail:
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9
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Bhattarai K, Holcik M. Diverse roles of heterogeneous nuclear ribonucleoproteins in viral life cycle. FRONTIERS IN VIROLOGY 2022. [DOI: 10.3389/fviro.2022.1044652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Understanding the host-virus interactions helps to decipher the viral replication strategies and pathogenesis. Viruses have limited genetic content and rely significantly on their host cell to establish a successful infection. Viruses depend on the host for a broad spectrum of cellular RNA-binding proteins (RBPs) throughout their life cycle. One of the major RBP families is the heterogeneous nuclear ribonucleoproteins (hnRNPs) family. hnRNPs are typically localized in the nucleus, where they are forming complexes with pre-mRNAs and contribute to many aspects of nucleic acid metabolism. hnRNPs contain RNA binding motifs and frequently function as RNA chaperones involved in pre-mRNA processing, RNA splicing, and export. Many hnRNPs shuttle between the nucleus and the cytoplasm and influence cytoplasmic processes such as mRNA stability, localization, and translation. The interactions between the hnRNPs and viral components are well-known. They are critical for processing viral nucleic acids and proteins and, therefore, impact the success of the viral infection. This review discusses the molecular mechanisms by which hnRNPs interact with and regulate each stage of the viral life cycle, such as replication, splicing, translation, and assembly of virus progeny. In addition, we expand on the role of hnRNPs in the antiviral response and as potential targets for antiviral drug research and development.
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10
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Tang YS, So WK, Ng KLA, Mok KPC, Shaw PC. Interaction of Influenza A Nucleoprotein with Host hnRNP-C Is Implicated in Viral Replication. Int J Mol Sci 2022; 23:13613. [PMID: 36362400 PMCID: PMC9655074 DOI: 10.3390/ijms232113613] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 10/27/2022] [Accepted: 11/04/2022] [Indexed: 08/18/2023] Open
Abstract
The host interactome of influenza viral proteins is ever-expanding. In this work, we report the identification of host heterogeneous nuclear ribonucleoprotein C (hnRNP-C) as an interacting partner of influenza A virus nucleoprotein (NP). We confirmed that this interaction exists across different influenza A subtypes and strains. Using biochemical methods, we determined that hnRNP-C interacts with NP via its C-terminal auxiliary domain. Further, we determined that the hnRNP-C is a negative regulator of influenza viral growth. Its interaction with NP is implicated in the promotion of host cell apoptosis during viral infection. It is the first time that the interaction between influenza nucleoprotein and host heterogeneous nuclear ribonucleoprotein C is characterized in detail. Overall, these findings not only characterize the interaction between NP and its host interacting partner hnRNP-C but also clarify the functional significance of this interaction. This work may lead to a new therapeutic target for the development of anti-influenza drugs.
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Affiliation(s)
- Yun-Sang Tang
- Centre for Protein Sciences and Crystallography, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Wai-Kin So
- Centre for Protein Sciences and Crystallography, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Ka-Leung Andy Ng
- Office of University General Education, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Ka-Pun Chris Mok
- The Jockey Club School of Public Health and Primary Care, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China
- Li Ka Shing Institute of Health Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Pang-Chui Shaw
- Centre for Protein Sciences and Crystallography, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Hong Kong SAR, China
- Li Dak Sum Yip Yio Chin R&D Centre for Chinese Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China
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11
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Kajitani N, Schwartz S. The role of RNA-binding proteins in the processing of mRNAs produced by carcinogenic papillomaviruses. Semin Cancer Biol 2022; 86:482-496. [PMID: 35181475 DOI: 10.1016/j.semcancer.2022.02.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 02/10/2022] [Accepted: 02/11/2022] [Indexed: 02/08/2023]
Abstract
Human papillomaviruses (HPV) are epitheliotropic DNA tumor viruses that are prevalent in the human population. A subset of the HPVs termed high-risk HPVs (HR-HPVs) are causative agents of anogenital cancers and head-and-neck cancers. Cancer is the result of persistent high-risk HPV infections that have not been cleared by the immune system of the host. These infections are characterized by dysregulated HPV gene expression, in particular constitutive high expression of the HPV E6 and E7 oncogenes and absence of the highly immunogenic viral L1 and L2 capsid proteins. HPVs make extensive use of alternative mRNA splicing to express its genes and are therefore highly dependent on cellular RNA-binding proteins for proper gene expression. Levels of RNA-binding proteins are altered in HPV-containing premalignant cervical lesions and in cervical cancer. Here we review our current knowledge of RNA-binding proteins that control HPV gene expression. We focus on RNA-binding proteins that control expression of the E6 and E7 oncogenes since they initiate and drive development of cancer and on the immunogenic L1 and L2 proteins as there silencing may contribute to immune evasion during carcinogenesis. Furthermore, cellular RNA-binding proteins are essential for HPV gene expression and as such may be targets for therapy to HPV infections and HPV-driven cancers.
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Affiliation(s)
- Naoko Kajitani
- Department of Medical Biochemistry and Microbiology (IMBIM), Uppsala University, BMC-B9, 751 23, Uppsala, Sweden; Department of Laboratory Medicine, Lund University, BMC-B13, 221 84, Lund, Sweden
| | - Stefan Schwartz
- Department of Medical Biochemistry and Microbiology (IMBIM), Uppsala University, BMC-B9, 751 23, Uppsala, Sweden; Department of Laboratory Medicine, Lund University, BMC-B13, 221 84, Lund, Sweden.
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12
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Yu L, Majerciak V, Zheng ZM. HPV16 and HPV18 Genome Structure, Expression, and Post-Transcriptional Regulation. Int J Mol Sci 2022; 23:ijms23094943. [PMID: 35563334 PMCID: PMC9105396 DOI: 10.3390/ijms23094943] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 04/14/2022] [Accepted: 04/15/2022] [Indexed: 12/18/2022] Open
Abstract
Human papillomaviruses (HPV) are a group of small non-enveloped DNA viruses whose infection causes benign tumors or cancers. HPV16 and HPV18, the two most common high-risk HPVs, are responsible for ~70% of all HPV-related cervical cancers and head and neck cancers. The expression of the HPV genome is highly dependent on cell differentiation and is strictly regulated at the transcriptional and post-transcriptional levels. Both HPV early and late transcripts differentially expressed in the infected cells are intron-containing bicistronic or polycistronic RNAs bearing more than one open reading frame (ORF), because of usage of alternative viral promoters and two alternative viral RNA polyadenylation signals. Papillomaviruses proficiently engage alternative RNA splicing to express individual ORFs from the bicistronic or polycistronic RNA transcripts. In this review, we discuss the genome structures and the updated transcription maps of HPV16 and HPV18, and the latest research advances in understanding RNA cis-elements, intron branch point sequences, and RNA-binding proteins in the regulation of viral RNA processing. Moreover, we briefly discuss the epigenetic modifications, including DNA methylation and possible APOBEC-mediated genome editing in HPV infections and carcinogenesis.
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13
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Cui X, Hao C, Gong L, Kajitani N, Schwartz S. HnRNP D activates production of HPV16 E1 and E6 mRNAs by promoting intron retention. Nucleic Acids Res 2022; 50:2782-2806. [PMID: 35234917 PMCID: PMC8934624 DOI: 10.1093/nar/gkac132] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Revised: 01/26/2022] [Accepted: 02/11/2022] [Indexed: 12/13/2022] Open
Abstract
Human papillomavirus type 16 (HPV16) E1 and E6 proteins are produced from mRNAs with retained introns, but it has been unclear how these mRNAs are generated. Here, we report that hnRNP D act as a splicing inhibitor of HPV16 E1/E2- and E6/E7-mRNAs thereby generating intron-containing E1- and E6-mRNAs, respectively. N- and C-termini of hnRNP D contributed to HPV16 mRNA splicing control differently. HnRNP D interacted with the components of splicing machinery and with HPV16 RNA to exert its inhibitory function. As a result, the cytoplasmic levels of intron-retained HPV16 mRNAs were increased in the presence of hnRNP D. Association of hnRNP D with HPV16 mRNAs in the cytoplasm was observed, and this may correlate with unexpected inhibition of HPV16 E1- and E6-mRNA translation. Notably, hnRNP D40 interacted with HPV16 mRNAs in an HPV16-driven tonsillar cancer cell line and in HPV16-immortalized human keratinocytes. Furthermore, knockdown of hnRNP D in HPV16-driven cervical cancer cells enhanced production of the HPV16 E7 oncoprotein. Our results suggest that hnRNP D plays significant roles in the regulation of HPV gene expression and HPV-associated cancer development.
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Affiliation(s)
- Xiaoxu Cui
- Department of Laboratory Medicine, Lund University, BMC-B13, 221 84 Lund, Sweden
| | - Chengyu Hao
- Department of Laboratory Medicine, Lund University, BMC-B13, 221 84 Lund, Sweden
| | - Lijing Gong
- Department of Laboratory Medicine, Lund University, BMC-B13, 221 84 Lund, Sweden.,China Institute of Sport and Health Sciences, Beijing Sport University, Haidian District, Beijing 100084, China
| | - Naoko Kajitani
- Department of Laboratory Medicine, Lund University, BMC-B13, 221 84 Lund, Sweden.,Department of Medical Biochemistry and Microbiology (IMBIM), Uppsala University, BMC-B9, 751 23 Uppsala, Sweden
| | - Stefan Schwartz
- Department of Laboratory Medicine, Lund University, BMC-B13, 221 84 Lund, Sweden.,Department of Medical Biochemistry and Microbiology (IMBIM), Uppsala University, BMC-B9, 751 23 Uppsala, Sweden
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14
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Overexpression of m6A-factors METTL3, ALKBH5, and YTHDC1 alters HPV16 mRNA splicing. Virus Genes 2022; 58:98-112. [PMID: 35190939 PMCID: PMC8948141 DOI: 10.1007/s11262-022-01889-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 02/12/2022] [Indexed: 11/24/2022]
Abstract
We report that overexpression of the m6A-demethylase alkB homolog 5 RNA demethylase (ALKBH5) promoted production of intron retention on the human papillomavirus type 16 (HPV16) E6 mRNAs thereby promoting E6 mRNA production. ALKBH5 also altered alternative splicing of the late L1 mRNA by an exon skipping mechanism. Knock-down of ALKBH5 had the opposite effect on splicing of these HPV16 mRNAs. Overexpression of the m6A-methylase methyltransferase-like protein 3 (METLL3) induced production of intron-containing HPV16 E1 mRNAs over spliced E2 mRNAs and altered HPV16 L1 mRNA splicing in a manner opposite to ALKBH5. Overexpression of the nuclear m6A-“reader” YTH domain-containing protein 1 (YTHDC1), enhanced retention of the E6-encoding intron and promoted E6 mRNA production. We also show that HPV16 mRNAs are bound to YTHDC1 in human cells and that YTHDC1 affected splicing of HPV16 E6/E7 mRNAs produced from the episomal form of the HPV16 genome. Finally, we show that HPV16 mRNAs are m6A-methylated in tonsillar cancer cells. In summary, HPV16 mRNAs are methylated in HPV16-infected tonsillar cancer cells and overexpression of m6A-“writer” METTL3, m6A-“eraser” ALKBH5 and the m6A-“reader” YTHDC1 affected HPV16 mRNA splicing, suggesting that m6A plays an important role in the HPV16 gene expression program, at least in cancer cells.
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15
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Identification of heterogenous nuclear ribonucleoproteins (hnRNPs) and serine- and arginine-rich (SR) proteins that induce human papillomavirus type 16 late gene expression and alter L1 mRNA splicing. Arch Virol 2021; 167:563-570. [PMID: 34860285 PMCID: PMC8843915 DOI: 10.1007/s00705-021-05317-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 10/19/2021] [Indexed: 11/03/2022]
Abstract
We have determined the effect of seven serine- and arginine-rich (SR) proteins and 15 heterogenous nuclear ribonucleoproteins (hnRNPs) on human papillomavirus type 16 (HPV16) late gene expression. Of the seven SR proteins analyzed here, SRSF1, SRSF3, and SRSF9 induced HPV16 late gene expression, and five of the SR proteins affected HPV16 L1 mRNA splicing. Of the 15 hnRNP proteins analyzed here, hnRNP A2, hnRNP F, and hnRNP H efficiently induced HPV16 late gene expression, and all of the hnRNPs affected HPV16 L1 mRNA levels or mRNA splicing. Thus, the majority of SR proteins and hnRNPs have the potential to regulate HPV16 L1 mRNA splicing. Strict control of the expression of the immunogenic L1 and L2 capsid proteins may contribute to the ability of HPV16 to cause persistence.
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16
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Tong L, Chu Z, Gao X, Yang M, Adam FEA, Theodore DWP, Liu H, Wang X, Xiao S, Yang Z. Newcastle disease virus V protein interacts with hnRNP H1 to promote viral replication. Vet Microbiol 2021; 260:109093. [PMID: 34265512 DOI: 10.1016/j.vetmic.2021.109093] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Accepted: 04/19/2021] [Indexed: 11/17/2022]
Abstract
The interactions between host cellular proteins and viral proteins are important for successful infection by viruses. Previous studies from our group have identified various host cellular proteins that can interact with the Newcastle disease virus V protein (Chu et al., 2018a), but their function in NDV replication has not been fully determined. The present study reports that heterogenous nuclear ribonucleoprotein H1 (hnRNP H1) can interact with NDV V protein in yeast. The immunofluorescence results showed that hnRNP H1 and V protein could colocalize in the cytoplasm of a chicken embryo fibroblast cell line (DF-1 cells). Co-immunoprecipitation assays further verified the interaction of these two proteins. The effects of overexpression and knockdown of hnRNP H1 on NDV replication were evaluated in DF-1 cells through real time quantitative PCR (RT-qPCR) and plaque assays. The regulation of V protein on hnRNP H1 expression was also examined. The results indicated that overexpression of hnRNP H1 facilitated NDV replication, while knockdown of hnRNP H1 decreased NDV replication. It was also shown that V protein could regulate hnRNP H1 expression at the protein level instead of the transcription level. The effect of V protein and hnRNP H1 on the DF-1 cell cycle was also tested and the results revealed that V protein may regulate cell proliferation by controlling the expression of hnRNP H1. Taken together, these results suggest that NDV V protein could promote viral replication by interacting with hnRNP H1.
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Affiliation(s)
- Lina Tong
- College of Veterinary Medicine, Northwest A & F University, Yangling, Shaanxi, 712100, China; College of Agriculture and Animal Husbandry, Qinghai University, Xining, Qinghai, 810000, China
| | - Zhili Chu
- College of Veterinary Medicine, Northwest A & F University, Yangling, Shaanxi, 712100, China; School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, Henan, 453003, China
| | - Xiaolong Gao
- College of Agriculture and Animal Husbandry, Qinghai University, Xining, Qinghai, 810000, China
| | - Mengqing Yang
- College of Veterinary Medicine, Northwest A & F University, Yangling, Shaanxi, 712100, China
| | - Fathalrhman Eisa A Adam
- College of Veterinary Medicine, Northwest A & F University, Yangling, Shaanxi, 712100, China
| | | | - Haijin Liu
- College of Veterinary Medicine, Northwest A & F University, Yangling, Shaanxi, 712100, China
| | - Xinglong Wang
- College of Veterinary Medicine, Northwest A & F University, Yangling, Shaanxi, 712100, China
| | - Sa Xiao
- College of Veterinary Medicine, Northwest A & F University, Yangling, Shaanxi, 712100, China
| | - Zengqi Yang
- College of Veterinary Medicine, Northwest A & F University, Yangling, Shaanxi, 712100, China.
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17
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Kajitani N, Schwartz S. Role of Viral Ribonucleoproteins in Human Papillomavirus Type 16 Gene Expression. Viruses 2020; 12:E1110. [PMID: 33007936 PMCID: PMC7600041 DOI: 10.3390/v12101110] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Revised: 09/25/2020] [Accepted: 09/26/2020] [Indexed: 02/06/2023] Open
Abstract
Human papillomaviruses (HPVs) depend on the cellular RNA-processing machineries including alternative RNA splicing and polyadenylation to coordinate HPV gene expression. HPV RNA processing is controlled by cis-regulatory RNA elements and trans-regulatory factors since the HPV splice sites are suboptimal. The definition of HPV exons and introns may differ between individual HPV mRNA species and is complicated by the fact that many HPV protein-coding sequences overlap. The formation of HPV ribonucleoproteins consisting of HPV pre-mRNAs and multiple cellular RNA-binding proteins may result in the different outcomes of HPV gene expression, which contributes to the HPV life cycle progression and HPV-associated cancer development. In this review, we summarize the regulation of HPV16 gene expression at the level of RNA processing with focus on the interactions between HPV16 pre-mRNAs and cellular RNA-binding factors.
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Affiliation(s)
- Naoko Kajitani
- Department of Laboratory Medicine, Lund University, 22184 Lund, Sweden;
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18
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Cerasuolo A, Buonaguro L, Buonaguro FM, Tornesello ML. The Role of RNA Splicing Factors in Cancer: Regulation of Viral and Human Gene Expression in Human Papillomavirus-Related Cervical Cancer. Front Cell Dev Biol 2020; 8:474. [PMID: 32596243 PMCID: PMC7303290 DOI: 10.3389/fcell.2020.00474] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 05/20/2020] [Indexed: 12/12/2022] Open
Abstract
The spliceosomal complex components, together with the heterogeneous nuclear ribonucleoproteins (hnRNPs) and serine/arginine-rich (SR) proteins, regulate the process of constitutive and alternative splicing, the latter leading to the production of mRNA isoforms coding multiple proteins from a single pre-mRNA molecule. The expression of splicing factors is frequently deregulated in different cancer types causing the generation of oncogenic proteins involved in cancer hallmarks. Cervical cancer is caused by persistent infection with oncogenic human papillomaviruses (HPVs) and constitutive expression of viral oncogenes. The aberrant activity of hnRNPs and SR proteins in cervical neoplasia has been shown to trigger the production of oncoproteins through the processing of pre-mRNA transcripts either derived from human genes or HPV genomes. Indeed, hnRNP and SR splicing factors have been shown to regulate the production of viral oncoprotein isoforms necessary for the completion of viral life cycle and for cell transformation. Target-therapy strategies against hnRNPs and SR proteins, causing simultaneous reduction of oncogenic factors and inhibition of HPV replication, are under development. In this review, we describe the current knowledge of the functional link between RNA splicing factors and deregulated cellular as well as viral RNA maturation in cervical cancer and the opportunity of new therapeutic strategies.
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Affiliation(s)
| | | | | | - Maria Lina Tornesello
- Molecular Biology and Viral Oncology Unit, Istituto Nazionale Tumouri IRCCS–Fondazione G. Pascale, Naples, Italy
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19
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Nilsson K, Wu C, Schwartz S. Role of the DNA Damage Response in Human Papillomavirus RNA Splicing and Polyadenylation. Int J Mol Sci 2018; 19:E1735. [PMID: 29895741 PMCID: PMC6032147 DOI: 10.3390/ijms19061735] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 05/29/2018] [Accepted: 06/08/2018] [Indexed: 12/16/2022] Open
Abstract
Human papillomaviruses (HPVs) have evolved to use the DNA repair machinery to replicate its DNA genome in differentiated cells. HPV activates the DNA damage response (DDR) in infected cells. Cellular DDR factors are recruited to the HPV DNA genome and position the cellular DNA polymerase on the HPV DNA and progeny genomes are synthesized. Following HPV DNA replication, HPV late gene expression is activated. Recent research has shown that the DDR factors also interact with RNA binding proteins and affects RNA processing. DDR factors activated by DNA damage and that associate with HPV DNA can recruit splicing factors and RNA binding proteins to the HPV DNA and induce HPV late gene expression. This induction is the result of altered alternative polyadenylation and splicing of HPV messenger RNA (mRNA). HPV uses the DDR machinery to replicate its DNA genome and to activate HPV late gene expression at the level of RNA processing.
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Affiliation(s)
- Kersti Nilsson
- Department of Laboratory Medicine, Lund University, 221 84 Lund, Sweden.
| | - Chengjun Wu
- Department of Laboratory Medicine, Lund University, 221 84 Lund, Sweden.
| | - Stefan Schwartz
- Department of Laboratory Medicine, Lund University, 221 84 Lund, Sweden.
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20
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Adenosine causes read-through into the late region of the HPV16 genome in a guanosine-dependent manner. Virology 2018; 521:1-19. [PMID: 29864673 DOI: 10.1016/j.virol.2018.05.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 05/24/2018] [Accepted: 05/25/2018] [Indexed: 11/21/2022]
Abstract
Adenosine plays an important role in cell death and differentiation as well as in tumorigenesis and the intra- and extra-cellular levels range from nanomolar to millimolar levels under various physiological or pathophysiological conditions. Here we report that adenosine can activate HPV16 late gene expression in a dose- and time-dependent manner, but only in the presence of guanosine. This activation occurred within hours after addition of the nucleosides and was primarily dependent on the ENT1 nucleoside transporter protein. Induction of HPV16 late gene expression was mainly the result of increased read-through at the early HPV16 polyadenylation signal into the late region of the HPV16 genome, thereby producing HPV16 late L2 mRNAs. The effect of guanosine and adenosine on HPV16 late gene expression was mediated by the increased binding to HPV16 mRNAs and nuclear export of the cellular HuR protein. Our results demonstrate that nucleosides can affect HPV16 gene expression.
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21
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Nilsson K, Wu C, Kajitani N, Yu H, Tsimtsirakis E, Gong L, Winquist EB, Glahder J, Ekblad L, Wennerberg J, Schwartz S. The DNA damage response activates HPV16 late gene expression at the level of RNA processing. Nucleic Acids Res 2018; 46:5029-5049. [PMID: 29596642 PMCID: PMC6007495 DOI: 10.1093/nar/gky227] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 03/15/2018] [Accepted: 03/19/2018] [Indexed: 12/13/2022] Open
Abstract
We show that the alkylating cancer drug melphalan activated the DNA damage response and induced human papillomavirus type 16 (HPV16) late gene expression in an ATM- and Chk1/2-dependent manner. Activation of HPV16 late gene expression included inhibition of the HPV16 early polyadenylation signal that resulted in read-through into the late region of HPV16. This was followed by activation of the exclusively late, HPV16 splice sites SD3632 and SA5639 and production of spliced late L1 mRNAs. Altered HPV16 mRNA processing was paralleled by increased association of phosphorylated BRCA1, BARD1, BCLAF1 and TRAP150 with HPV16 DNA, and increased association of RNA processing factors U2AF65 and hnRNP C with HPV16 mRNAs. These RNA processing factors inhibited HPV16 early polyadenylation and enhanced HPV16 late mRNA splicing, thereby activating HPV16 late gene expression.
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Affiliation(s)
- Kersti Nilsson
- Department of Laboratory Medicine, Lund University, BMC-B13, 221 84 Lund, Sweden
| | - Chengjun Wu
- Department of Laboratory Medicine, Lund University, BMC-B13, 221 84 Lund, Sweden
| | - Naoko Kajitani
- Department of Laboratory Medicine, Lund University, BMC-B13, 221 84 Lund, Sweden
| | - Haoran Yu
- Department of Laboratory Medicine, Lund University, BMC-B13, 221 84 Lund, Sweden
| | | | - Lijing Gong
- Department of Laboratory Medicine, Lund University, BMC-B13, 221 84 Lund, Sweden
- China Academy of Sport and Health Sciences, Beijing Sport University, Xinxi Road 48, Haidian District, 100084 Beijing, China
| | - Ellenor B Winquist
- Department of Laboratory Medicine, Lund University, BMC-B13, 221 84 Lund, Sweden
| | - Jacob Glahder
- Department of Laboratory Medicine, Lund University, BMC-B13, 221 84 Lund, Sweden
| | - Lars Ekblad
- Department of Clinical Sciences Lund, Oncology and Pathology, Lund University, Skane University Hospital, 221 85 Lund, Sweden
| | - Johan Wennerberg
- Department of Clinical Sciences Lund, Oto-rhino-laryngology, Head and Neck Surgery, Lund University, Skane University Hospital, 221 85 Lund, Sweden
| | - Stefan Schwartz
- Department of Laboratory Medicine, Lund University, BMC-B13, 221 84 Lund, Sweden
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22
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Yu H, Gong L, Wu C, Nilsson K, Li-Wang X, Schwartz S. hnRNP G prevents inclusion on the HPV16 L1 mRNAs of the central exon between splice sites SA3358 and SD3632. J Gen Virol 2018; 99:328-343. [PMID: 29458523 DOI: 10.1099/jgv.0.001019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
HPV16 late L1 mRNAs encode a short central exon that is located between HPV16 3'-splice site SA3358 and HPV16 5'-splice site SD3632. While SA3358 is used to produce both HPV16 early mRNAs encoding the E6 and E7 oncogenes, and late mRNAs encoding E4, L1 and L2, SD3632 is used exclusively to produce late L1 mRNA. We have previously identified an 8-nucleotide regulatory RNA element that is required for inclusion of the exon between SA3358 and SD3632 to produce L1 mRNAs at the expense of mRNAs polyadenylated at the HPV16 early polyadenylation signal pAE. Here we show that this HPV16 8-nucleotide splicing enhancer interacts with hnRNP G. Binding of hnRNP G to this element prevents inclusion of the exon between SA3358 and SD3632 on the HPV16 late L1 mRNAs. We concluded that hnRNP G has a splicing inhibitory role and that hnRNP G can control HPV16 mRNA splicing.
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Affiliation(s)
- Haoran Yu
- Department of Laboratory Medicine, Lund university, BMC-B13, 223 62 Lund, Sweden
| | - Lijing Gong
- Department of Laboratory Medicine, Lund university, BMC-B13, 223 62 Lund, Sweden.,China Academy of Sport and Health Sciences, Beijing Sport University, Xinxi Road 48, Haidian District, 100084 Beijing, PR China
| | - Chengjun Wu
- Department of Laboratory Medicine, Lund university, BMC-B13, 223 62 Lund, Sweden
| | - Kersti Nilsson
- Department of Laboratory Medicine, Lund university, BMC-B13, 223 62 Lund, Sweden
| | - Xiaoze Li-Wang
- Department of Laboratory Medicine, Lund university, BMC-B13, 223 62 Lund, Sweden
| | - Stefan Schwartz
- Department of Laboratory Medicine, Lund university, BMC-B13, 223 62 Lund, Sweden
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23
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Kajitani N, Glahder J, Wu C, Yu H, Nilsson K, Schwartz S. hnRNP L controls HPV16 RNA polyadenylation and splicing in an Akt kinase-dependent manner. Nucleic Acids Res 2017; 45:9654-9678. [PMID: 28934469 PMCID: PMC5766200 DOI: 10.1093/nar/gkx606] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Accepted: 07/04/2017] [Indexed: 11/14/2022] Open
Abstract
Inhibition of the Akt kinase activates HPV16 late gene expression by reducing HPV16 early polyadenylation and by activating HPV16 late L1 mRNA splicing. We identified ‘hot spots’ for RNA binding proteins at the early polyA signal and at splice sites on HPV16 late mRNAs. We observed that hnRNP L was associated with sequences at all HPV16 late splice sites and at the early polyA signal. Akt kinase inhibition resulted in hnRNP L dephosphorylation and reduced association of hnRNP L with HPV16 mRNAs. This was accompanied by an increased binding of U2AF65 and Sam68 to HPV16 mRNAs. Furthermore, siRNA knock-down of hnRNP L or Akt induced HPV16 gene expression. Treatment of HPV16 immortalized keratinocytes with Akt kinase inhibitor reduced hnRNP L binding to HPV16 mRNAs and induced HPV16 L1 mRNA production. Finally, deletion of the hnRNP L binding sites in HPV16 subgenomic expression plasmids resulted in activation of HPV16 late gene expression. In conclusion, the Akt kinase inhibits HPV16 late gene expression at the level of RNA processing by controlling the RNA-binding protein hnRNP L. We speculate that Akt kinase activity upholds an intracellular milieu that favours HPV16 early gene expression and suppresses HPV16 late gene expression.
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Affiliation(s)
- Naoko Kajitani
- Department of Laboratory Medicine, Lund University, BMC-B13, 223 62 Lund, Sweden
| | - Jacob Glahder
- Department of Laboratory Medicine, Lund University, BMC-B13, 223 62 Lund, Sweden
| | - Chengjun Wu
- Department of Laboratory Medicine, Lund University, BMC-B13, 223 62 Lund, Sweden
| | - Haoran Yu
- Department of Laboratory Medicine, Lund University, BMC-B13, 223 62 Lund, Sweden
| | - Kersti Nilsson
- Department of Laboratory Medicine, Lund University, BMC-B13, 223 62 Lund, Sweden
| | - Stefan Schwartz
- Department of Laboratory Medicine, Lund University, BMC-B13, 223 62 Lund, Sweden
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24
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Graham SV. Keratinocyte Differentiation-Dependent Human Papillomavirus Gene Regulation. Viruses 2017; 9:E245. [PMID: 28867768 PMCID: PMC5618011 DOI: 10.3390/v9090245] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 08/24/2017] [Accepted: 08/25/2017] [Indexed: 12/29/2022] Open
Abstract
Human papillomaviruses (HPVs) cause diseases ranging from benign warts to invasive cancers. HPVs infect epithelial cells and their replication cycle is tightly linked with the differentiation process of the infected keratinocyte. The normal replication cycle involves an early and a late phase. The early phase encompasses viral entry and initial genome replication, stimulation of cell division and inhibition of apoptosis in the infected cell. Late events in the HPV life cycle include viral genome amplification, virion formation, and release into the environment from the surface of the epithelium. The main proteins required at the late stage of infection for viral genome amplification include E1, E2, E4 and E5. The late proteins L1 and L2 are structural proteins that form the viral capsid. Regulation of these late events involves both cellular and viral proteins. The late viral mRNAs are expressed from a specific late promoter but final late mRNA levels in the infected cell are controlled by splicing, polyadenylation, nuclear export and RNA stability. Viral late protein expression is also controlled at the level of translation. This review will discuss current knowledge of how HPV late gene expression is regulated.
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Affiliation(s)
- Sheila V Graham
- MRC-University of Glasgow Centre for Virus Research, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Garscube Estate, Glasgow G61 1QH, UK.
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25
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Splicing and Polyadenylation of Human Papillomavirus Type 16 mRNAs. Int J Mol Sci 2017; 18:ijms18020366. [PMID: 28208770 PMCID: PMC5343901 DOI: 10.3390/ijms18020366] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 01/29/2017] [Accepted: 02/03/2017] [Indexed: 12/24/2022] Open
Abstract
The human papillomavirus type 16 (HPV16) life cycle can be divided into an early stage in which the HPV16 genomic DNA is replicated, and a late stage in which the HPV16 structural proteins are synthesized and virions are produced. A strong coupling between the viral life cycle and the differentiation state of the infected cell is highly characteristic of all HPVs. The switch from the HPV16 early gene expression program to the late requires a promoter switch, a polyadenylation signal switch and a shift in alternative splicing. A number of cis-acting RNA elements on the HPV16 mRNAs and cellular and viral factors interacting with these elements are involved in the control of HPV16 gene expression. This review summarizes our knowledge of HPV16 cis-acting RNA elements and cellular and viral trans-acting factors that regulate HPV16 gene expression at the level of splicing and polyadenylation.
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26
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Graham SV, Faizo AAA. Control of human papillomavirus gene expression by alternative splicing. Virus Res 2016; 231:83-95. [PMID: 27867028 PMCID: PMC5335905 DOI: 10.1016/j.virusres.2016.11.016] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 11/08/2016] [Accepted: 11/10/2016] [Indexed: 11/21/2022]
Abstract
Alternative splicing is a key cellular mechanism controlling HPV gene expression. Many cellular SR proteins and hnRNPs have been identified that bind and control production of viral mRNAs. HPV16 E2 protein controls expression of SR proteins and has splicing-related functions. HPV16 infection through its regulatory effects on splicing factors may significantly alter cellular gene expression and cellular metabolism.
Human papillomaviruses possess circular double stranded DNA genomes of around 8 kb in size from which multiple mRNAs are synthesized during an infectious life cycle. Although at least three viral promoters are used to initiate transcription, viral mRNAs are largely the product of processing of pre-mRNAs by alternative splicing and polyadenylation. The HPV life cycle and viral gene expression are tightly linked to differentiation of the epithelium the virus infects: there is an orchestrated production of viral mRNAs and proteins. In this review we describe viral mRNA expression and the roles of the SR and hnRNP proteins that respectively positively and negatively regulate splicing. We discuss HPV regulation of splicing factors and detail the evidence that the papillomavirus E2 protein has splicing-related activities. We highlight the possibility that HPV-mediated control of splicing in differentiating epithelial cells may be necessary to accomplish the viral replication cycle.
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Affiliation(s)
- Sheila V Graham
- MRC-University of Glasgow Centre for Virus Research; Institute of Infection, Immunity and Inflammation; College of Medical Veterinary and Life Sciences, University of Glasgow, Garscube Estate, Glasgow G61 1QH, Scotland, UK.
| | - Arwa Ali A Faizo
- MRC-University of Glasgow Centre for Virus Research; Institute of Infection, Immunity and Inflammation; College of Medical Veterinary and Life Sciences, University of Glasgow, Garscube Estate, Glasgow G61 1QH, Scotland, UK
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27
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RNA Binding Proteins that Control Human Papillomavirus Gene Expression. Biomolecules 2015; 5:758-74. [PMID: 25950509 PMCID: PMC4496695 DOI: 10.3390/biom5020758] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 04/15/2015] [Accepted: 04/21/2015] [Indexed: 12/23/2022] Open
Abstract
The human papillomavirus (HPV) life cycle is strictly linked to the differentiation program of the infected mucosal epithelial cell. In the basal and lower levels of the epithelium, early genes coding for pro-mitotic proteins and viral replication factors are expressed, while terminal cell differentiation is required for activation of late gene expression and production of viral particles at the very top of the epithelium. Such productive infections are normally cleared within 18–24 months. In rare cases, the HPV infection is stuck in the early stage of the infection. Such infections may give rise to cervical lesions that can progress to cancer, primarily cancer of the uterine cervix. Since cancer progression is strictly linked to HPV gene expression, it is of interest to understand how HPV gene expression is regulated. Cis-acting HPV RNA elements and cellular RNA-binding proteins control HPV mRNA splicing and polyadenylation. These interactions are believed to play a particularly important role in the switch from early to late gene expression, thereby contributing to the pathogenesis of HPV. Indeed, it has been shown that the levels of various RNA binding proteins change in response to differentiation and in response to HPV induced cervical lesions and cancer. Here we have compiled published data on RNA binding proteins involved in the regulation of HPV gene expression.
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