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Kremsdorf D, Lekbaby B, Bablon P, Sotty J, Augustin J, Schnuriger A, Pol J, Soussan P. Alternative splicing of viral transcripts: the dark side of HBV. Gut 2021; 70:2373-2382. [PMID: 34535538 DOI: 10.1136/gutjnl-2021-324554] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 09/06/2021] [Indexed: 02/06/2023]
Abstract
Regulation of alternative splicing is one of the most efficient mechanisms to enlarge the proteomic diversity in eukaryotic organisms. Many viruses hijack the splicing machinery following infection to accomplish their replication cycle. Regarding the HBV, numerous reports have described alternative splicing events of the long viral transcript (pregenomic RNA), which also acts as a template for viral genome replication. Alternative splicing of HBV pregenomic RNAs allows the synthesis of at least 20 spliced variants. In addition, almost all these spliced forms give rise to defective particles, detected in the blood of infected patients. HBV-spliced RNAs have long been unconsidered, probably due to their uneasy detection in comparison to unspliced forms as well as for their dispensable role during viral replication. However, recent data highlighted the relevance of these HBV-spliced variants through (1) the trans-regulation of the alternative splicing of viral transcripts along the course of liver disease; (2) the ability to generate defective particle formation, putative biomarker of the liver disease progression; (3) modulation of viral replication; and (4) their intrinsic propensity to encode for novel viral proteins involved in liver pathogenesis and immune response. Altogether, tricky regulation of HBV alternative splicing may contribute to modulate multiple viral and cellular processes all along the course of HBV-related liver disease.
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Affiliation(s)
- Dina Kremsdorf
- Institut National de la Santé et de la Recherche Médicale U938, Centre de Recherche de Saint Antoine, Sorbonne Université-Faculté Saint Antoine, Paris, France
| | - Bouchra Lekbaby
- Institut National de la Santé et de la Recherche Médicale U938, Centre de Recherche de Saint Antoine, Sorbonne Université-Faculté Saint Antoine, Paris, France
| | - Pierre Bablon
- Institut National de la Santé et de la Recherche Médicale U938, Centre de Recherche de Saint Antoine, Sorbonne Université-Faculté Saint Antoine, Paris, France
| | - Jules Sotty
- Institut National de la Santé et de la Recherche Médicale U938, Centre de Recherche de Saint Antoine, Sorbonne Université-Faculté Saint Antoine, Paris, France
| | - Jérémy Augustin
- Institut National de la Santé et de la Recherche Médicale U938, Centre de Recherche de Saint Antoine, Sorbonne Université-Faculté Saint Antoine, Paris, France
| | - Aurélie Schnuriger
- Institut National de la Santé et de la Recherche Médicale U938, Centre de Recherche de Saint Antoine, Sorbonne Université-Faculté Saint Antoine, Paris, France.,Assistance Publique - Hôpitaux de Paris, Département de Virologie, GHU Paris-Est, Paris, France
| | - Jonathan Pol
- Institut National de la Santé et de la Recherche Médicale U1138, Centre de Recherche des Cordeliers, Université de Paris, Sorbonne Université, Paris, France.,Metabolomics ann Cell Biology Platforms, Gustave Roussy Cancer Campus, Villejuif, France
| | - Patrick Soussan
- Institut National de la Santé et de la Recherche Médicale U938, Centre de Recherche de Saint Antoine, Sorbonne Université-Faculté Saint Antoine, Paris, France .,Assistance Publique - Hôpitaux de Paris, Département de Virologie, GHU Paris-Est, Paris, France
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Sengupta I, Das D, Singh SP, Chakravarty R, Das C. Host transcription factor Speckled 110 kDa (Sp110), a nuclear body protein, is hijacked by hepatitis B virus protein X for viral persistence. J Biol Chem 2017; 292:20379-20393. [PMID: 29046350 DOI: 10.1074/jbc.m117.796839] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 10/13/2017] [Indexed: 12/20/2022] Open
Abstract
Promyelocytic leukemia nuclear bodies (PML-NB) are sub-nuclear organelles that are the hub of numerous proteins. DNA/RNA viruses often hijack the cellular factors resident in PML-NBs to promote their proliferation in host cells. Hepatitis B virus (HBV), belonging to Hepadnaviridae family, remains undetected in early infection as it does not induce the innate immune response and is known to be the cause of several hepatic diseases leading to cirrhosis and hepatocellular carcinoma. The association of PML-NB proteins and HBV is being addressed in a number of recent studies. Here, we report that the PML-NB protein Speckled 110 kDa (Sp110) is SUMO1-modified and undergoes a deSUMOylation-driven release from the PML-NB in the presence of HBV. Intriguingly, Sp110 knockdown significantly reduced viral DNA load in the culture supernatant by activation of the type I interferon-response pathway. Furthermore, we found that Sp110 differentially regulates several direct target genes of hepatitis B virus protein X (HBx), a viral co-factor. Subsequently, we identified Sp110 as a novel interactor of HBx and found this association to be essential for the exit of Sp110 from the PML-NB during HBV infection and HBx recruitment on the promoter of these genes. HBx, in turn, modulates the recruitment of its associated transcription cofactors p300/HDAC1 to these co-regulated genes, thereby altering the host gene expression program in favor of viral persistence. Thus, we report a mechanism by which HBV can evade host immune response by hijacking the PML-NB protein Sp110, and therefore, we propose it to be a novel target for antiviral therapy.
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Affiliation(s)
- Isha Sengupta
- From the Biophysics and Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata-700064
| | - Dipanwita Das
- the Indian Council of Medical Research (ICMR) Virus Unit, Kolkata, Infectious Diseases and Beliaghata General Hospital Campus, Kolkata 700010, and
| | - Shivaram Prasad Singh
- the Kalinga Gastroenterology Foundation, Beam Diagnostics Premises, Cuttack-753001, India
| | - Runu Chakravarty
- the Indian Council of Medical Research (ICMR) Virus Unit, Kolkata, Infectious Diseases and Beliaghata General Hospital Campus, Kolkata 700010, and
| | - Chandrima Das
- From the Biophysics and Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata-700064,
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HBV maintains electrostatic homeostasis by modulating negative charges from phosphoserine and encapsidated nucleic acids. Sci Rep 2016; 6:38959. [PMID: 27958343 PMCID: PMC5154190 DOI: 10.1038/srep38959] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Accepted: 11/14/2016] [Indexed: 12/22/2022] Open
Abstract
Capsid assembly and stability of hepatitis B virus (HBV) core protein (HBc) particles depend on balanced electrostatic interactions between encapsidated nucleic acids and an arginine-rich domain (ARD) of HBc in the capsid interior. Arginine-deficient ARD mutants preferentially encapsidated spliced viral RNA and shorter DNA, which can be fully or partially rescued by reducing the negative charges from acidic residues or serine phosphorylation of HBc, dose-dependently. Similarly, empty capsids without RNA encapsidation can be generated by ARD hyper-phosphorylation in insect, bacteria, and human hepatocytes. De-phosphorylation of empty capsids by phosphatase induced capsid disassembly. Empty capsids can convert into RNA-containing capsids by increasing HBc serine de-phosphorylation. In an HBV replicon system, we observed a reciprocal relationship between viral and non-viral RNA encapsidation, suggesting both non-viral RNA and serine-phosphorylation could serve as a charge balance buffer in maintaining electrostatic homeostasis. In addition, by comparing the biochemistry assay results between a replicon and a non-replicon system, we observed a correlation between HBc de-phosphorylation and viral replication. Balanced electrostatic interactions may be important to other icosahedral particles in nature.
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Bayliss J, Lim L, Thompson AJV, Desmond P, Angus P, Locarnini S, Revill PA. Hepatitis B virus splicing is enhanced prior to development of hepatocellular carcinoma. J Hepatol 2013; 59:1022-8. [PMID: 23811301 DOI: 10.1016/j.jhep.2013.06.018] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 06/04/2013] [Accepted: 06/18/2013] [Indexed: 12/20/2022]
Abstract
BACKGROUND & AIMS The hepatitis B virus (HBV) genome encodes specific sequence elements which promote splicing of viral DNA. It has been previously suggested that spliced HBV (spHBV) variants promote viral replication and protein production, leading to hepatocellular carcinoma (HCC). In this study, we have analysed changes in spHBV over time; providing the first longitudinal analysis of spHBV in relation to the development of HCC. METHODS Serial serum samples were collected from 165 patients with chronic HBV monoinfection, including 58 patients who later developed HCC. Real-time PCR was used to amplify and quantify wt and sp DNA loads. RESULTS spHBV was detected in over 80% of patients with chronic HBV infection. Median serum spHBV levels were significantly higher in HCC patients than HCC-free control patients (p<0.001). Univariate analysis revealed a strong correlation between time to HCC diagnosis and spHBV DNA levels (τ=0.203; p=0.016). Asian HBV genotype (p=0.025) and increased viral load (p<0.001) were also significantly associated with increased spHBV DNA levels. Multiple regression analysis revealed time to diagnosis of HCC, Asian HBV genotypes, and viral load to be associated with increased spHBV DNA (model p<0.001; R(2)=0.189). CONCLUSIONS HBV splicing is a common event during chronic infection and increases prior to diagnosis of HCC. Measurement of HBV splicing may prove a valuable adjunct to be used in the identification of chronically infected patients who are at increased risk of developing HCC.
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Affiliation(s)
- Julianne Bayliss
- Division of Molecular Research and Development, Victorian Infectious Diseases Reference Laboratory, North Melbourne, Victoria 3051, Australia.
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Wang Z, Wu L, Cheng X, Liu S, Li B, Li H, Kang F, Wang J, Xia H, Ping C, Nassal M, Sun D. Replication-competent infectious hepatitis B virus vectors carrying substantially sized transgenes by redesigned viral polymerase translation. PLoS One 2013; 8:e60306. [PMID: 23589756 PMCID: PMC3615001 DOI: 10.1371/journal.pone.0060306] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Accepted: 02/25/2013] [Indexed: 12/13/2022] Open
Abstract
Viral vectors are engineered virus variants able to deliver nonviral genetic information into cells, usually by the same routes as the parental viruses. For several virus families, replication-competent vectors carrying reporter genes have become invaluable tools for easy and quantitative monitoring of replication and infection, and thus also for identifying antivirals and virus susceptible cells. For hepatitis B virus (HBV), a small enveloped DNA virus causing B-type hepatitis, such vectors are not available because insertions into its tiny 3.2 kb genome almost inevitably affect essential replication elements. HBV replicates by reverse transcription of the pregenomic (pg) RNA which is also required as bicistronic mRNA for the capsid (core) protein and the reverse transcriptase (Pol); their open reading frames (ORFs) overlap by some 150 basepairs. Translation of the downstream Pol ORF does not involve a conventional internal ribosome entry site (IRES). We reasoned that duplicating the overlap region and providing artificial IRES control for translation of both Pol and an in-between inserted transgene might yield a functional tricistronic pgRNA, without interfering with envelope protein expression. As IRESs we used a 22 nucleotide element termed Rbm3 IRES to minimize genome size increase. Model plasmids confirmed its activity even in tricistronic arrangements. Analogous plasmids for complete HBV genomes carrying 399 bp and 720 bp transgenes for blasticidin resistance (BsdR) and humanized Renilla green fluorescent protein (hrGFP) produced core and envelope proteins like wild-type HBV; while the hrGFP vector replicated poorly, the BsdR vector generated around 40% as much replicative DNA as wild-type HBV. Both vectors, however, formed enveloped virions which were infectious for HBV-susceptible HepaRG cells. Because numerous reporter and effector genes with sizes of around 500 bp or less are available, the new HBV vectors should become highly useful tools to better understand, and combat, this important pathogen.
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Affiliation(s)
- Zihua Wang
- The Liver Disease Diagnosis and Treatment Center of PLA, Bethune International Peace Hospital, Shijiazhuang, PR China
- The Third Military Medical University, Chongqing, PR China
| | - Li Wu
- The Liver Disease Diagnosis and Treatment Center of PLA, Bethune International Peace Hospital, Shijiazhuang, PR China
| | - Xin Cheng
- The Liver Disease Diagnosis and Treatment Center of PLA, Bethune International Peace Hospital, Shijiazhuang, PR China
| | - Shizhu Liu
- The Liver Disease Diagnosis and Treatment Center of PLA, Bethune International Peace Hospital, Shijiazhuang, PR China
| | - Baosheng Li
- The Liver Disease Diagnosis and Treatment Center of PLA, Bethune International Peace Hospital, Shijiazhuang, PR China
| | - Haijun Li
- The Liver Disease Diagnosis and Treatment Center of PLA, Bethune International Peace Hospital, Shijiazhuang, PR China
| | - Fubiao Kang
- The Liver Disease Diagnosis and Treatment Center of PLA, Bethune International Peace Hospital, Shijiazhuang, PR China
| | - Junping Wang
- The Liver Disease Diagnosis and Treatment Center of PLA, Bethune International Peace Hospital, Shijiazhuang, PR China
| | - Huan Xia
- The Liver Disease Diagnosis and Treatment Center of PLA, Bethune International Peace Hospital, Shijiazhuang, PR China
| | - Caiyan Ping
- The Liver Disease Diagnosis and Treatment Center of PLA, Bethune International Peace Hospital, Shijiazhuang, PR China
| | - Michael Nassal
- University Hospital Freiburg, Internal Medicine II/Molecular Biology, Freiburg, Germany
- * E-mail: (DS); (MN)
| | - Dianxing Sun
- The Liver Disease Diagnosis and Treatment Center of PLA, Bethune International Peace Hospital, Shijiazhuang, PR China
- * E-mail: (DS); (MN)
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