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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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Choy W, Lagman C, Lee SJ, Bui TT, Safaee M, Yang I. Impact of Human Immunodeficiency Virus in the Pathogenesis and Outcome of Patients with Glioblastoma Multiforme. Brain Tumor Res Treat 2016; 4:77-86. [PMID: 27867916 PMCID: PMC5114196 DOI: 10.14791/btrt.2016.4.2.77] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 07/10/2016] [Accepted: 07/18/2016] [Indexed: 12/25/2022] Open
Abstract
Background Improvement in antiviral therapies have been accompanied by an increased frequency of non-Acquired Immune Deficiency Syndrome (AIDS) defining malignancies, such as glioblastoma multiforme. Here, we investigated all reported cases of human immunodeficiency virus (HIV)-positive patients with glioblastoma and evaluated their clinical outcomes. A comprehensive review of the molecular pathogenetic mechanisms underlying glioblastoma development in the setting of HIV/AIDS is provided. Methods We performed a PubMed search using keywords “HIV glioma” AND “glioblastoma,” and “AIDS glioma” AND “glioblastoma.” Case reports and series describing HIV-positive patients with glioblastoma (histologically-proven World Health Organization grade IV astrocytoma) and reporting on HAART treatment status, clinical follow-up, and overall survival (OS), were included for the purposes of quantitative synthesis. Patients without clinical follow-up data or OS were excluded. Remaining articles were assessed for data extraction eligibility. Results A total of 17 patients met our inclusion criteria. Of these patients, 14 (82.4%) were male and 3 (17.6%) were female, with a mean age of 39.5±9.2 years (range 19–60 years). Average CD4 count at diagnosis of glioblastoma was 358.9±193.4 cells/mm3. Tumor progression rather than AIDS-associated complications dictated patient survival. There was a trend towards increased median survival with HAART treatment (12.0 vs 7.5 months, p=0.10) Conclusion Our data suggests that HAART is associated with improved survival in patients with HIV-associated glioblastoma, although the precise mechanisms underlying this improvement remain unclear.
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Affiliation(s)
- Winward Choy
- Department of Neurosurgery, University of California, Los Angeles, Los Angeles, CA, USA
| | - Carlito Lagman
- Department of Neurosurgery, University of California, Los Angeles, Los Angeles, CA, USA
| | - Seung J Lee
- Department of Neurosurgery, University of California, Los Angeles, Los Angeles, CA, USA
| | - Timothy T Bui
- Department of Neurosurgery, University of California, Los Angeles, Los Angeles, CA, USA
| | - Michael Safaee
- Department of Neurosurgery, University of California, Los Angeles, Los Angeles, CA, USA
| | - Isaac Yang
- Department of Neurosurgery, University of California, Los Angeles, Los Angeles, CA, USA.; Jonsson Comprehensive Cancer Center, University of California, Los Angeles, Los Angeles, CA, USA
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Kobbi L, Dias J, Comisso M, Mirande M. Association of human mitochondrial lysyl-tRNA synthetase with HIV-1 GagPol does not require other viral proteins. BIOCHIMIE OPEN 2016; 2:52-61. [PMID: 29632838 PMCID: PMC5889485 DOI: 10.1016/j.biopen.2016.02.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 02/25/2016] [Indexed: 01/31/2023]
Abstract
In human, the cytoplasmic (cLysRS) and mitochondrial (mLysRS) species of lysyl-tRNA synthetase are encoded by a single gene. Following HIV-1 infection, mLysRS is selectively taken up into viral particles along with the three tRNALys isoacceptors. The GagPol polyprotein precursor is involved in this process. With the aim to reconstitute in vitro the HIV-1 tRNA3Lys packaging complex, we first searched for the putative involvement of another viral protein in the selective viral hijacking of mLysRS only. After screening all the viral proteins, we observed that Vpr and Rev have the potential to interact with mLysRS, but that this association does not take place at the level of the assembly of mLysRS into the packaging complex. We also show that tRNA3Lys can form a ternary complex with the two purified proteins mLysRS and the Pol domain of GagPol, which mimicks its packaging complex. HIV-1 Rev and Vpr proteins have the capacity to bind human mitochondrial LysRS. In the complex between HIV-1 Pol and mitochondrial LysRS, Rev and Vpr are excluded. Association of Pol with mLysRS recapitulates the tRNA3Lys packaging complex of HIV-1.
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Affiliation(s)
- Lydia Kobbi
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Université Paris-Sud, 1 avenue de la Terrasse, 91190 Gif-sur-Yvette, France
| | - José Dias
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Université Paris-Sud, 1 avenue de la Terrasse, 91190 Gif-sur-Yvette, France
| | - Martine Comisso
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Université Paris-Sud, 1 avenue de la Terrasse, 91190 Gif-sur-Yvette, France
| | - Marc Mirande
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Université Paris-Sud, 1 avenue de la Terrasse, 91190 Gif-sur-Yvette, France
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Pilkington GR, Purzycka KJ, Bear J, Le Grice SFJ, Felber BK. Gammaretrovirus mRNA expression is mediated by a novel, bipartite post-transcriptional regulatory element. Nucleic Acids Res 2014; 42:11092-106. [PMID: 25190459 PMCID: PMC4176177 DOI: 10.1093/nar/gku798] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Post-transcriptional regulatory mechanisms of several complex and simple retroviruses and retroelements have been elucidated, with the exception of the gammaretrovirus family. We found that, similar to the other retroviruses, gag gene expression of MuLV and XMRV depends on post-transcriptional regulation mediated via an RNA sequence overlapping the pro-pol open reading frame, termed the Post-Transcriptional Element (PTE). PTE function can be replaced by heterologous RNA export elements, e.g. CTE of simian type D retroviruses. Alternatively, Gag particle production is achieved using an RNA/codon optimized gag gene. PTE function is transferable and can replace HIV Rev-RRE-regulated expression of HIV gag. Analysis of PTE by SHAPE revealed a highly structured RNA comprising seven stem-loop structures, with the 5′ and 3′ stem-loops forming an essential bipartite signal. MuLV and XMRV PTE share 98% identity and have highly similar RNA structures, with changes mostly located to single-stranded regions. PTE identification strongly suggests that all retroviruses and retroelements share common strategies of post-transcriptional gene regulation to produce Gag. Expression depends on complex RNA structures embedded within retroviral mRNA, in coding regions or the 3′ untranslated region. These specific structures serve as recognition signals for either cellular or viral proteins.
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Affiliation(s)
- Guy R Pilkington
- Human Retrovirus Pathogenesis Section, Vaccine Branch, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702, USA
| | - Katarzyna J Purzycka
- RT Biochemistry Section, Drug Resistance Program, National Cancer Institute at Frederick, Frederick, MD 21702, USA Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, 61-704, Poland
| | - Jenifer Bear
- Human Retrovirus Pathogenesis Section, Vaccine Branch, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702, USA
| | - Stuart F J Le Grice
- RT Biochemistry Section, Drug Resistance Program, National Cancer Institute at Frederick, Frederick, MD 21702, USA
| | - Barbara K Felber
- Human Retrovirus Pathogenesis Section, Vaccine Branch, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702, USA
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Felber BK, Valentin A, Rosati M, Bergamaschi C, Pavlakis GN. HIV DNA Vaccine: Stepwise Improvements Make a Difference. Vaccines (Basel) 2014; 2:354-79. [PMID: 26344623 PMCID: PMC4494255 DOI: 10.3390/vaccines2020354] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Revised: 04/11/2014] [Accepted: 04/18/2014] [Indexed: 12/15/2022] Open
Abstract
Inefficient DNA delivery methods and low expression of plasmid DNA have been major obstacles for the use of plasmid DNA as vaccine for HIV/AIDS. This review describes successful efforts to improve DNA vaccine methodology over the past ~30 years. DNA vaccination, either alone or in combination with other methods, has the potential to be a rapid, safe, and effective vaccine platform against AIDS. Recent clinical trials suggest the feasibility of its translation to the clinic.
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Affiliation(s)
- Barbara K Felber
- Human Retrovirus Pathogenesis Section, Vaccine Branch, Center for Cancer Research, National Cancer Institute at Frederick, P.O. Box B, Frederick, MD 21702, USA.
| | - Antonio Valentin
- Human Retrovirus Section, Vaccine Branch, Center for Cancer Research, National Cancer Institute at Frederick, P.O. Box B, Frederick, MD 21702, USA.
| | - Margherita Rosati
- Human Retrovirus Section, Vaccine Branch, Center for Cancer Research, National Cancer Institute at Frederick, P.O. Box B, Frederick, MD 21702, USA.
| | - Cristina Bergamaschi
- Human Retrovirus Pathogenesis Section, Vaccine Branch, Center for Cancer Research, National Cancer Institute at Frederick, P.O. Box B, Frederick, MD 21702, USA.
| | - George N Pavlakis
- Human Retrovirus Section, Vaccine Branch, Center for Cancer Research, National Cancer Institute at Frederick, P.O. Box B, Frederick, MD 21702, USA.
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Vincendeau M, Nagel D, Brenke JK, Brack-Werner R, Hadian K. Heterogenous nuclear ribonucleoprotein Q increases protein expression from HIV-1 Rev-dependent transcripts. Virol J 2013; 10:151. [PMID: 23679954 PMCID: PMC3673855 DOI: 10.1186/1743-422x-10-151] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 03/19/2013] [Indexed: 02/05/2023] Open
Abstract
Background Heterogenous nuclear ribonucleoproteins (hnRNPs) control many processes of the gene expression machinery including mRNA transcription, splicing, export, stability and translation. Recent data show interaction of the HIV-1 Rev regulatory protein with a subset of hnRNP proteins, that includes hnRNP Q, suggesting that hnRNPs can contribute to regulation of HIV-1 gene expression by Rev. Findings In this work we address the effect of hnRNP Q on Rev-dependent gene expression. We show that hnRNP Q overexpression increased levels of proteins produced from a Rev-dependent reporter gene in the presence of Rev. Increased protein levels did not correlate with changes in either the levels or the nucleocytoplasmic distribution of Rev-dependent reporter mRNAs. Similar observations were made in persistently HIV-1 infected HeLa cells. In these cells, hnRNP Q overexpression increased levels of the HIV-1 Gag-p24 protein, while levels of viral Rev-dependent mRNAs were not affected. Conclusion Our data indicate that hnRNP Q can stimulate the protein production of Rev-dependent mRNAs without changing mRNA levels and mRNA export, respectively. This suggests that hnRNP Q can boost HIV gene expression at the level of protein production.
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Affiliation(s)
- Michelle Vincendeau
- Institute of Virology, Helmholtz Zentrum München, Research Center for Environmental Health, Ingolstaedter Landstraße 1, 85764 Neuherberg, Germany
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NEAT1 long noncoding RNA and paraspeckle bodies modulate HIV-1 posttranscriptional expression. mBio 2013; 4:e00596-12. [PMID: 23362321 PMCID: PMC3560530 DOI: 10.1128/mbio.00596-12] [Citation(s) in RCA: 293] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Most of the human genome is transcribed into protein-noncoding RNAs (ncRNAs), including small ncRNAs and long ncRNAs (lncRNAs). Over the past decade, rapidly emerging evidence has increasingly supported the view that lncRNAs serve key regulatory and functional roles in mammal cells. HIV-1 replication relies on various cell functions. To date, while the involvement of host protein factors and microRNAs (miRNAs) in the HIV-1 life cycle has been extensively studied, the relationship between lncRNAs and HIV-1 remains uncharacterized. Here, we have profiled 83 disease-related lncRNAs in HIV-1-infected T cells. We found NEAT1 to be one of several lncRNAs whose expression is changed by HIV-1 infection, and we have characterized its role in HIV-1 replication. We In the abstract, added definition of INS OK, or should "cis-acting" be added?report here that the knockdown of NEAT1 enhances virus production through increased nucleus-to-cytoplasm export of Rev-dependent instability element (INS)-containing HIV-1 mRNAs. IMPORTANCE Long protein-noncoding RNAs (lncRNAs) play roles in regulating gene expression and modulating protein activities. There is emerging evidence that lncRNAs are involved in the replication of viruses. To our knowledge, this report is the first to characterize a role contributed by an lncRNA, NEAT1, to HIV-1 replication. NEAT1 is essential for the integrity of the nuclear paraspeckle substructure. Based on our findings from NEAT1 knockdown, we have identified the nuclear paraspeckle body as another important subcellular organelle for HIV-1 replication.
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Cytoplasmic utilization of human immunodeficiency virus type 1 genomic RNA is not dependent on a nuclear interaction with gag. J Virol 2012; 86:2990-3002. [PMID: 22258250 DOI: 10.1128/jvi.06874-11] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In some retroviruses, such as Rous sarcoma virus and prototype foamy virus, Gag proteins are known to shuttle between the nucleus and the cytoplasm and are implicated in nuclear export of the viral genomic unspliced RNA (gRNA) for subsequent encapsidation. A similar function has been proposed for human immunodeficiency virus type 1 (HIV-1) Gag based on the identification of nuclear localization and export signals. However, the ability of HIV-1 Gag to transit through the nucleus has never been confirmed. In addition, the lentiviral Rev protein promotes efficient nuclear gRNA export, and previous reports indicate a cytoplasmic interaction between Gag and gRNA. Therefore, functional effects of HIV-1 Gag on gRNA and its usage were explored. Expression of gag in the absence of Rev was not able to increase cytoplasmic gRNA levels of subgenomic, proviral, or lentiviral vector constructs, and gene expression from genomic reporter plasmids could not be induced by Gag provided in trans. Furthermore, Gag lacking the reported nuclear localization and export signals was still able to mediate an efficient packaging process. Although small amounts of Gag were detectable in the nuclei of transfected cells, a Crm1-dependent nuclear export signal in Gag could not be confirmed. Thus, our study does not provide any evidence for a nuclear function of HIV-1 Gag. The encapsidation process of HIV-1 therefore clearly differs from that of Rous sarcoma virus and prototype foamy virus.
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9
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Abstract
The post-transcriptional export of spliced and unspliced HIV-1 (human immunodeficiency virus type 1) RNAs from the nucleus to the cytoplasm is a complex process. Part of the complexity arises from the fact that eukaryotic cells normally retain unspliced RNAs in the nucleus preventing their exit into the cytoplasm. HIV-1 has evolved a protein, Rev, that participates in the export of unspliced / partially spliced viral RNAs from the nucleus. It has been documented that several cellular factors cooperate in trans with Rev, and certain cis-RNA motifs / features are important for transcripts to be recognized by Rev and its co-factors. Here, the post-transcriptional activities of Rev are discussed in the context of a recent finding that an RNA cap methyltransferase contributes to the expression of unspliced / partially spliced HIV-1 transcripts.
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Affiliation(s)
- Venkat S R K Yedavalli
- Molecular Virology Section, Laboratory of Molecular Microbiology, National Institutes of Allergy and Infectious Diseases, the National Institutes of Health, Bethesda, MD, USA
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Legiewicz M, Zolotukhin AS, Pilkington GR, Purzycka KJ, Mitchell M, Uranishi H, Bear J, Pavlakis GN, Le Grice SFJ, Felber BK. The RNA transport element of the murine musD retrotransposon requires long-range intramolecular interactions for function. J Biol Chem 2010; 285:42097-104. [PMID: 20978285 DOI: 10.1074/jbc.m110.182840] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Retrovirus replication requires specialized transport mechanisms to export genomic mRNA from the nucleus to the cytoplasm of the infected cell. This regulation is mediated by a combination of viral and/or cellular factors that interact with cis-acting RNA export elements linking the viral RNA to the cellular CRM1 or NXF1 nuclear export pathways. Endogenous type D murine LTR retrotransposons (musD) were reported to contain an RNA export element located upstream of the 3'-LTR. Although functionally equivalent, the musD export element, termed the musD transport element, is distinct from the other retroviral RNA export elements, such as the constitutive transport element of simian/Mason-Pfizer monkey retroviruses and the RNA transport element found in rodent intracisternal A-particle LTR retrotransposons. We demonstrate here that the minimal RNA transport element (musD transport element) of musD comprises multiple secondary structure elements that presumably serve as recognition signals for the cellular export machinery. We identified two classes of tertiary interactions, namely kissing loops and a pseudoknot. This work constitutes the first example of an RNA transport element requiring such structural motifs to mediate nuclear export.
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Affiliation(s)
- Michal Legiewicz
- RT Biochemistry Section, NCI-Frederick, National Institutes of Health, Frederick, Maryland 21702-1201, USA
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Control of HIV replication in astrocytes by a family of highly conserved host proteins with a common Rev-interacting domain (Risp). AIDS 2010; 24:2433-42. [PMID: 20827171 DOI: 10.1097/qad.0b013e32833e8758] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVE In human astrocytes, restriction of HIV replication involves inhibition of HIV Rev activity. We previously identified a Rev-interacting human protein fragment (16.4.1) that can reduce Rev activity. The 16.4.1 sequence is contained in a group of highly similar host cell proteins, which we call the Risp family. Here we investigate whether the Risp family is connected to HIV replication in astrocytes. METHODS Cell/tissue lysates were analyzed for Risp expression by western blot with various anti-Risp antibodies. The interaction of astrocytic Risp members with Rev was investigated by affinity chromatography. Astrocytes were transfected with expression plasmids containing cDNAs encoding full-length Risp or the isolated 16.4.1 region for Risp overexpression or with siRNAs designed for Risp knock-down. Rev activity was investigated with a Rev-reporter assay. RNA levels were quantified by real-time RT-PCR, HIV Gag levels by p24ELISA. RESULTS Expression of the Risp family was demonstrated in human brain tissues and astrocytes. Astrocytes were shown to produce Risp family members that interact with Rev. Production of HIV Gag proteins and Rev-dependent RNAs in persistently infected astrocytes increased upon Risp knock-down and decreased upon Risp overexpression. Risp knock-down increased Rev activity and raised proportions of Rev proteins in the nucleus of astrocytes. CONCLUSION Our results link the Risp family to restriction of HIV production and inhibition of Rev activity in astrocytes. We conclude that the Risp family represents a novel family of host factors that can control HIV replication and may be important for the containment of HIV infection in brain reservoirs.
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12
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von Gegerfelt A, Valentin A, Alicea C, Van Rompay KKA, Marthas ML, Montefiori DC, Pavlakis GN, Felber BK. Emergence of simian immunodeficiency virus-specific cytotoxic CD4+ T cells and increased humoral responses correlate with control of rebounding viremia in CD8-depleted macaques infected with Rev-independent live-attenuated simian immunodeficiency virus. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2010; 185:3348-58. [PMID: 20702730 PMCID: PMC7316374 DOI: 10.4049/jimmunol.1000572] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Indian rhesus macaques infected with the Rev-independent live-attenuated SIVmac239 strains control viremia to undetectable levels, have persistent but low cellular and humoral anti-SIV responses, and show no signs of immune deficiency. To analyze the immune mechanisms responsible for viral control, five macaques infected at day 1 after birth were subjected to CD8(+) cell depletion at 6.7 y postinfection. This resulted in viremia increases to 3.7-5.5 log(10) RNA copies, supporting a role of CD8-mediated responses in the control of viral replication. The rebounding viremia was rapidly controlled to levels below the threshold of detection, and occurred in the absence of SIV-specific CD8(+) T cells and significant CD8(+) T cell recovery in four of the five animals, suggesting that other mechanisms are involved in the immunological control of viremia. Monitoring immune responses at the time of viral control demonstrated a burst of circulating SIV-specific CD4(+) T cells characterized as CD45RA(-)CD28(+)CD95(+)CCR7(-) and also granzyme B(+), suggesting cytotoxic ability. Control of viremia was also concomitant with increases in humoral responses to Gag and Env, including a transient increase in neutralizing Abs against the neutralization-resistant SIVmac239 in four of five animals. These data demonstrate that a combination of cellular responses mediated by CD4(+) T cells and humoral responses was associated with the rapid control of the rebounding viremia in macaques infected by the Rev-independent live-attenuated SIV, even in the absence of measurable SIV-specific CD8(+) T cells in the blood, emphasizing the importance of different components of the immune response for full control of SIV infection.
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Affiliation(s)
- Agneta von Gegerfelt
- Human Retrovirus Section, Vaccine Branch, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702
| | - Antonio Valentin
- Human Retrovirus Section, Vaccine Branch, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702
| | - Candido Alicea
- Human Retrovirus Pathogenesis Section, Vaccine Branch, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702
| | - Koen K. A. Van Rompay
- California National Primate Research Center, University of California, Davis, Davis, CA 95616
| | - Marta L. Marthas
- California National Primate Research Center, University of California, Davis, Davis, CA 95616
| | - David C. Montefiori
- Department of Surgery, Laboratory for AIDS Vaccine Research and Development, Duke University Medical Center, Durham, NC 27710
| | - George N. Pavlakis
- Human Retrovirus Section, Vaccine Branch, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702
| | - Barbara K. Felber
- Human Retrovirus Pathogenesis Section, Vaccine Branch, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702
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Abstract
Herein we describe a mutant of the two-exon HIV-1 Tat protein, termed Nullbasic, that potently inhibits multiple steps of the HIV-1 replication cycle. Nullbasic was created by replacing the entire arginine-rich basic domain of wild type Tat with glycine/alanine residues. Like similarly mutated one-exon Tat mutants, Nullbasic exhibited transdominant negative effects on Tat-dependent transactivation. However, unlike previously reported mutants, we discovered that Nullbasic also strongly suppressed the expression of unspliced and singly-spliced viral mRNA, an activity likely caused by redistribution and thus functional inhibition of HIV-1 Rev. Furthermore, HIV-1 virion particles produced by cells expressing Nullbasic had severely reduced infectivity, a defect attributable to a reduced ability of the virions to undergo reverse transcription. Combination of these inhibitory effects on transactivation, Rev-dependent mRNA transport and reverse transcription meant that permissive cells constitutively expressing Nullbasic were highly resistant to a spreading infection by HIV-1. Nullbasic and its activities thus provide potential insights into the development of potent antiviral therapeutics that target multiple stages of HIV-1 infection.
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Hadian K, Vincendeau M, Mäusbacher N, Nagel D, Hauck SM, Ueffing M, Loyter A, Werner T, Wolff H, Brack-Werner R. Identification of a heterogeneous nuclear ribonucleoprotein-recognition region in the HIV Rev protein. J Biol Chem 2009; 284:33384-91. [PMID: 19808671 DOI: 10.1074/jbc.m109.021659] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Rev protein is a key regulator of human immunodeficiency virus type 1 (HIV-1) gene expression. Rev is primarily known as an adaptor protein for nuclear export of HIV RNAs. However, Rev also contributes to numerous other processes by less well known mechanisms. Understanding the functional nature of Rev requires extensive knowledge of its cellular interaction partners. Here we demonstrate that Rev interacts with members of a large family of multifunctional host cell factors called hnRNPs. Rev employs amino acids 9-14 for specific binding to the heterogeneous nuclear ribonucleoproteins (hnRNP) A1, Q, K, R, and U. In addition, Rev interacts with hnRNP E1 and E2 by a different mechanism. The set of hnRNPs recognized by the N terminus of Rev feature RGG boxes. Exemplary testing of hnRNP A1 revealed a critical role of arginine residues within the RGG box for interaction with Rev. Finally, we demonstrate that expression levels of hnRNP A1, Q, K, R, and U influence HIV-1 production by persistently infected astrocytes, linking these hnRNPs to HIV replication. The novel interaction of HIV-1 Rev with functionally diverse hnRNPs lends further support to the idea that Rev is a multifunctional protein and may be involved in coupling HIV replication to diverse cellular processes and promoting virus-host cell interactions.
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Affiliation(s)
- Kamyar Hadian
- Institute of Virology, Helmholtz Zentrum München, Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg, Germany
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15
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Japanese encephalitis virus-based replicon RNAs/particles as an expression system for HIV-1 Pr55 Gag that is capable of producing virus-like particles. Virus Res 2009; 144:298-305. [PMID: 19406175 DOI: 10.1016/j.virusres.2009.04.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2008] [Revised: 04/16/2009] [Accepted: 04/20/2009] [Indexed: 11/23/2022]
Abstract
Ectopic expression of the structural protein Pr55(Gag) of HIV-1 has been limited by the presence of inhibitory sequences in the gag coding region that must normally be counteracted by HIV-1 Rev and RRE. Here, we describe a cytoplasmic RNA replicon based on the RNA genome of Japanese encephalitis virus (JEV) that is capable of expressing HIV-1 gag without requiring Rev/RRE. This replicon system was constructed by deleting all three JEV structural protein-coding regions (C, prM, and E) from the 5'-proximal region of the genome and simultaneously inserting an HIV-1 gag expression cassette driven by the internal ribosome entry site of encephalomyocarditis virus into the 3'-proximal noncoding region of the genome. Transfection of this JEV replicon RNA led to expression of Pr55(Gag) in the absence of Rev/RRE in the cytoplasm of hamster BHK-21, human HeLa, and mouse NIH/3T3 cells. Production of the Pr55(Gag) derived from this JEV replicon RNA appeared to be increased by approximately 3-fold when compared to that based on an alphavirus replicon RNA. Biochemical and morphological analyses demonstrated that the Pr55(Gag) proteins were released into the culture medium in the form of virus-like particles. We also observed that the JEV replicon RNAs expressing the Pr55(Gag) could be encapsidated into single-round infectious JEV replicon particles when transfected into a stable packaging cell line that provided the three JEV structural proteins in trans. This ectopic expression of the HIV-1 Pr55(Gag) by JEV-based replicon RNAs/particles in diverse cell types may represent a useful molecular platform for various biological applications in medicine and industry.
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Hutten S, Wälde S, Spillner C, Hauber J, Kehlenbach RH. The nuclear pore component Nup358 promotes transportin-dependent nuclear import. J Cell Sci 2009; 122:1100-10. [PMID: 19299463 DOI: 10.1242/jcs.040154] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Nup358 (also known as RanBP2), a component of the cytoplasmic filaments of the nuclear pore complex, has been implicated in various nucleocytoplasmic transport pathways. Here, we identify Nup358 as an important factor for transportin-mediated nuclear import. Depletion of Nup358 resulted in a strong inhibition of nuclear import of the human immunodeficiency virus type 1 (HIV-1) Rev protein. HIV-1 Rev is an RNA-binding protein that is required for CRM1 (also known as exportin 1)-dependent nuclear export of unspliced or partially spliced viral RNA. We show that transportin is the major nuclear import receptor for HIV-1 Rev in HeLa cells. Overexpression of transportin strongly promoted nuclear import of HIV-1 Rev in Nup358-depleted cells, indicating that the import receptor becomes rate-limiting under these conditions. Importantly, the import rate of other transportin-dependent proteins was also significantly reduced in Nup358-depleted cells. Our data therefore suggest a general role for Nup358 in transportin-mediated nuclear import.
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Affiliation(s)
- Saskia Hutten
- Department of Biochemistry I, Faculty of Medicine, Georg-August-University of Göttingen, 37073, Göttingen, Germany
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Rizvi TA, Ali J, Phillip PS, Ghazawi A, Jayanth P, Mustafa F. Role of a heterologous retroviral transport element in the development of genetic complementation assay for mouse mammary tumor virus (MMTV) replication. Virology 2009; 385:464-72. [PMID: 19157480 DOI: 10.1016/j.virol.2008.12.027] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Revised: 11/07/2008] [Accepted: 12/12/2008] [Indexed: 11/27/2022]
Abstract
The mouse mammary tumor virus (MMTV) is a type B retrovirus that is unique from other retroviruses in having multiple "tissue specific" and "hormone inducible" promoters. This unique feature has lead to the increasing interest in studying the biology of MMTV replication with the ultimate goal of developing MMTV based vectors for potentially targeted human gene therapy. In this report, we describe, for the first time, the establishment of an in vivo genetic complementation assay to study various aspects of MMTV replication. In the assay described here, the function of MMTV Rem/RmRE regulatory pathway has been successfully substituted by a heterologous retroviral constitutive transport element (CTE) from Mason Pfizer Monkey Virus (MPMV) for mature MMTV particle production. Our results revealed that in the absence of MPMV CTE or Rem/RmRE, RNA transcribed from MMTV Gag-Pol expression plasmids were efficiently transported to the cytoplasm. However, the presence of CTE was indispensable for Gag-Pol protein expression. In addition, we report the development of MMTV based vectors in which the packageable RNA was transcribed either from MMTV LTR or from a chimeric LTR, which could successfully be packaged and propagated by particles produced from MMTV Gag-Pol expression plasmids containing a heterologous transport element. The role of MPMV CTE in the transport of MMTV transfer vector RNA was not found to be significant. Development of such an assay should not only shed light on how MMTV regulates its gene expression, but also should provide additional molecular tools for delineating the packaging determinants for MMTV, which is imperative for the development of novel vectors for targeted and inducible gene therapy.
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Affiliation(s)
- Tahir A Rizvi
- Department of Microbiology & Immunology, Faculty of Medicine and Health Sciences (FMHS), United Arab Emirates University (UAEU), P.O. Box 17666, Al Ain, UAE.
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Keating CP, Hill MK, Hawkes DJ, Smyth RP, Isel C, Le SY, Palmenberg AC, Marshall JA, Marquet R, Nabel GJ, Mak J. The A-rich RNA sequences of HIV-1 pol are important for the synthesis of viral cDNA. Nucleic Acids Res 2008; 37:945-56. [PMID: 19106143 PMCID: PMC2647285 DOI: 10.1093/nar/gkn1015] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The bias of A-rich codons in HIV-1 pol is thought to be a record of hypermutations in viral genomes that lack biological functions. Bioinformatic analysis predicted that A-rich sequences are generally associated with minimal local RNA structures. Using codon modifications to reduce the amount of A-rich sequences within HIV-1 genomes, we have reduced the flexibility of RNA sequences in pol to analyze the functional significance of these A-rich 'structurally poor' RNA elements in HIV-1 pol. Our data showed that codon modification of HIV-1 sequences led to a suppression of virus infectivity by 5-100-fold, and this defect does not correlate with, viral entry, viral protein expression levels, viral protein profiles or virion packaging of genomic RNA. Codon modification of HIV-1 pol correlated with an enhanced dimer stability of the viral RNA genome, which was associated with a reduction of viral cDNA synthesis both during HIV-1 infection and in a cell free reverse transcription assay. Our data provided direct evidence that the HIV-1 A-rich pol sequence is not merely an evolutionary artifact of enzyme-induced hypermutations, and that HIV-1 has adapted to rely on A-rich RNA sequences to support the synthesis of viral cDNA during reverse transcription, highlighting the utility of using 'structurally poor' RNA domains in regulating biological process.
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Affiliation(s)
- Cameron P Keating
- Centre for Virology, Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Victoria, Australia
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The RNA transport element RTE is essential for IAP LTR-retrotransposon mobility. Virology 2008; 377:88-99. [PMID: 18485438 DOI: 10.1016/j.virol.2008.04.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Revised: 03/17/2008] [Accepted: 04/03/2008] [Indexed: 11/21/2022]
Abstract
We previously identified an RNA transport element (RTE) present at a high copy number in the mouse genome. Here, we show that a related element, RTE-D, is part of a mobile LTR-retrotransposon, which belongs to a family of intracisternal A-particle related elements (IAP). We demonstrate that RTE-D is essential for the mobility of the retrotransposon and it can be substituted by other known RNA export signals. RTE-deficient IAP transcripts are retained in the nucleus, while the RTE-containing transcripts accumulate in the cytoplasm allowing Gag protein expression. RTE-D acts as a posttranscriptional control element in a heterologous reporter mRNA and is activated by the cellular RNA binding protein 15 (RBM15), as reported for the previously described RTE. We identified a complex family of RTE-containing IAPs in mouse and mapped the active RTE-D-containing IAPs to the Mmr10 group of LTR-retrotransposons. These data reveal that, despite a complex evolutionary history, retroelements and retroviruses share the dependency on posttranscriptional regulation.
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