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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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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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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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Zheng Y, Cui X, Nilsson K, Yu H, Gong L, Wu C, Schwartz S. Efficient production of HPV16 E2 protein from HPV16 late mRNAs spliced from SD880 to SA2709. Virus Res 2020; 285:198004. [PMID: 32380211 DOI: 10.1016/j.virusres.2020.198004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 04/29/2020] [Accepted: 04/29/2020] [Indexed: 12/31/2022]
Abstract
Human papillomaviruses (HPVs) produce a large number of alternatively spliced mRNAs, including a number of differently spliced mRNAs with the potential to produce E2 protein. To identify the alternatively spliced HPV16 mRNA with the highest ability to produce E2 protein, we have generated E2 cDNA expression plasmids representing the most common, alternatively spliced E2 mRNAs, and assessed their translational potential. Our results revealed that an mRNA initiated at the HPV16 late promoter p670 and spliced from the HPV16 5'-splice site SD880 to the HPV16 3'-splice site SA2709, located immediately upstream of the E2 ATG, produced higher levels of E2 than any of the other alternatively spliced, E2-encoding mRNAs. Utilization of a known, alternative 3'-splice site located upstream of the E2 ATG named SA2582, generated mRNAs with lower ability to produce E2 than mRNAs spliced to SA2709. Finally, analysis of HPV16 mRNA splicing demonstrated that SA2709 was more efficiently spliced to the upstream 5'-splice site SD880 than to the upstream 5'-splice site SD226. In conclusion, the HPV16 mRNA with the greatest ability to produce E2 protein is generated from the HPV16 late promoter and is spliced between HPV16 5'-splice site SD880 and HPV16 3'-splice site SA2709.
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Affiliation(s)
- Yunji Zheng
- Department of Laboratory Medicine, Lund University, BMC-B13, 221 84, Lund, Sweden
| | - Xiaoxu Cui
- Department of Laboratory Medicine, Lund University, BMC-B13, 221 84, Lund, Sweden
| | - Kersti Nilsson
- 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 Institute of Sport and Health Sciences, Beijing Sport University, Xinxi Road 48, Haidian District, 100084, Beijing, China
| | - Chengjun Wu
- Department of Laboratory Medicine, Lund University, BMC-B13, 221 84, Lund, Sweden; The First Affiliated Hospital of Shandong First Medical University, No.16766 Jingshi Road, Jinan, Shandong Province, 250014, China; Institute of Basic Medicine, Shandong First Medical University & Shandong Academy of Medical Sciences, No.18877 Jingshi Road, Jinan, Shandong Province, 250062, China.
| | - Stefan Schwartz
- Department of Laboratory Medicine, Lund University, BMC-B13, 221 84, Lund, Sweden.
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Development of Novel Single-Chain Antibodies against the Hydrophobic HPV-16 E5 Protein. BIOMED RESEARCH INTERNATIONAL 2018; 2018:5809028. [PMID: 30027096 PMCID: PMC6031085 DOI: 10.1155/2018/5809028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Revised: 05/24/2018] [Accepted: 05/29/2018] [Indexed: 11/18/2022]
Abstract
The human papilloma virus type 16 infects genital mucosa with high prevalence in the oncogenesis of cervical and oropharyngeal cancers. The E5 protein of this virus is a small hydrophobic protein, whose expression generally decreases as the infection progresses to malignancy. These characteristics point to a role of E5 in the establishment of HPV infection and the initiation into cell transformation. The study of the HPV-16 E5 functions has been hindered because of the lack of antibodies. Detection is very difficult because of its hydrophobic nature, membrane location, and very low levels of expression. Thus, the objective of this study was to select single-chain antibodies against the full size E5 protein, which was coexpressed with maltose-binding protein. We report that the E5 protein was recognized by the antibody and was validated in W12 cells by fluorescent microscopy, including a colocalization with one of its host substrates. The use of this antibody could increase our knowledge about the functions of the oncogenic HPV-16 E5 protein during the earliest stages of keratinocyte infection in human.
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