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Dogrammatzis C, Waisner H, Kalamvoki M. "Non-Essential" Proteins of HSV-1 with Essential Roles In Vivo: A Comprehensive Review. Viruses 2020; 13:E17. [PMID: 33374862 PMCID: PMC7824580 DOI: 10.3390/v13010017] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 12/17/2020] [Accepted: 12/18/2020] [Indexed: 12/19/2022] Open
Abstract
Viruses encode for structural proteins that participate in virion formation and include capsid and envelope proteins. In addition, viruses encode for an array of non-structural accessory proteins important for replication, spread, and immune evasion in the host and are often linked to virus pathogenesis. Most virus accessory proteins are non-essential for growth in cell culture because of the simplicity of the infection barriers or because they have roles only during a state of the infection that does not exist in cell cultures (i.e., tissue-specific functions), or finally because host factors in cell culture can complement their absence. For these reasons, the study of most nonessential viral factors is more complex and requires development of suitable cell culture systems and in vivo models. Approximately half of the proteins encoded by the herpes simplex virus 1 (HSV-1) genome have been classified as non-essential. These proteins have essential roles in vivo in counteracting antiviral responses, facilitating the spread of the virus from the sites of initial infection to the peripheral nervous system, where it establishes lifelong reservoirs, virus pathogenesis, and other regulatory roles during infection. Understanding the functions of the non-essential proteins of herpesviruses is important to understand mechanisms of viral pathogenesis but also to harness properties of these viruses for therapeutic purposes. Here, we have provided a comprehensive summary of the functions of HSV-1 non-essential proteins.
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Affiliation(s)
| | | | - Maria Kalamvoki
- Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City, KS 66160, USA; (C.D.); (H.W.)
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2
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Deprey K, Becker L, Kritzer J, Plückthun A. Trapped! A Critical Evaluation of Methods for Measuring Total Cellular Uptake versus Cytosolic Localization. Bioconjug Chem 2019; 30:1006-1027. [PMID: 30882208 PMCID: PMC6527423 DOI: 10.1021/acs.bioconjchem.9b00112] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Biomolecules have many properties that make them promising for intracellular therapeutic applications, but delivery remains a key challenge because large biomolecules cannot easily enter the cytosol. Furthermore, quantification of total intracellular versus cytosolic concentrations remains demanding, and the determination of delivery efficiency is thus not straightforward. In this review, we discuss strategies for delivering biomolecules into the cytosol and briefly summarize the mechanisms of uptake for these systems. We then describe commonly used methods to measure total cellular uptake and, more selectively, cytosolic localization, and discuss the major advantages and drawbacks of each method. We critically evaluate methods of measuring "cell penetration" that do not adequately distinguish total cellular uptake and cytosolic localization, which often lead to inaccurate interpretations of a molecule's cytosolic localization. Finally, we summarize the properties and components of each method, including the main caveats of each, to allow for informed decisions about method selection for specific applications. When applied correctly and interpreted carefully, methods for quantifying cytosolic localization offer valuable insight into the bioactivity of biomolecules and potentially the prospects for their eventual development into therapeutics.
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Affiliation(s)
- Kirsten Deprey
- Department of Chemistry, Tufts University, 62 Talbot Avenue, Medford, Massachusetts 02155, United States
| | - Lukas Becker
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Joshua Kritzer
- Department of Chemistry, Tufts University, 62 Talbot Avenue, Medford, Massachusetts 02155, United States
| | - Andreas Plückthun
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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3
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Wu F, Long J, Wang S, Xing J, Li M, Zheng C. Live cell imaging fails to support viral-protein-mediated intercellular trafficking. Arch Virol 2012; 157:1383-6. [PMID: 22527865 DOI: 10.1007/s00705-012-1308-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Accepted: 03/10/2012] [Indexed: 11/24/2022]
Abstract
The herpes simplex virus type I protein VP22 has been reported to have the property of intercellular trafficking. However, there is little direct evidence to demonstrate that VP22 can shuttle freely between living cells. Here, we employ a novel and simple assay using live cell fluorescence microscopy to investigate the intercellular transport property. Our results demonstrated that VP22, bovine herpesvirus-1 VP22, HSV-1 US11 and HIV Tat could not shuttle into neighboring cells via direct contact.
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Affiliation(s)
- Fuqing Wu
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, 44 Xiaohongshan, Wuchang, Wuhan 430071, China
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4
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Zaichick SV, Bohannon KP, Smith GA. Alphaherpesviruses and the cytoskeleton in neuronal infections. Viruses 2011; 3:941-81. [PMID: 21994765 PMCID: PMC3185784 DOI: 10.3390/v3070941] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 06/03/2011] [Accepted: 06/17/2011] [Indexed: 12/13/2022] Open
Abstract
Following infection of exposed peripheral tissues, neurotropic alphaherpesviruses invade nerve endings and deposit their DNA genomes into the nuclei of neurons resident in ganglia of the peripheral nervous system. The end result of these events is the establishment of a life-long latent infection. Neuroinvasion typically requires efficient viral transmission through a polarized epithelium followed by long-distance transport through the viscous axoplasm. These events are mediated by the recruitment of the cellular microtubule motor proteins to the intracellular viral particle and by alterations to the cytoskeletal architecture. The focus of this review is the interplay between neurotropic herpesviruses and the cytoskeleton.
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Affiliation(s)
- Sofia V Zaichick
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
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5
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Zhao HP, Sun JF, Li N, Sun Y, Xia ZH, Wang Y, Cheng D, Qi QF, Jin ML, Qiu HJ. Assessment of the cell-mediated immunity induced by alphavirus replicon-vectored DNA vaccines against classical swine fever in a mouse model. Vet Immunol Immunopathol 2008; 129:57-65. [PMID: 19150136 DOI: 10.1016/j.vetimm.2008.12.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2008] [Revised: 12/01/2008] [Accepted: 12/04/2008] [Indexed: 11/30/2022]
Abstract
We have previously shown that an alphavirus replicon-vectored DNA vaccine (pSFV1CS-E2) encoding the E2 glycoprotein of classical swine fever virus (CSFV) completely protected the immunized pigs from lethal challenge. These animals developed only low or moderate level viral-specific antibody titers before challenge, implying that cell-mediated immunity (CMI) probably played an important role in the protective immunity against CSFV conferred by the DNA vaccine. In this study, the CMI induced by pSFV1CS-E2 and its derivative pSFV1CS-E2-UL49 encoding a fusion protein of CSFV E2 and pseudorabies virus (PRV) VP22 was evaluated in a mouse model by lymphoproliferation assays based on CFSE or WST-8, intracellular cytokine staining, and cytokine ELISA. The results showed that both vaccines induced CSFV-specific lymphoproliferative responses and cytokine production, and pSFV1CS-E2-UL49 induced stronger lymphoproliferative responses and higher cytokine levels than pSFV1CS-E2. These findings suggest that the alphavirus replicon-delivered DNA vaccines are capable of inducing CMI, and PRV VP22 is able to enhance the immunogenicity of the co-delivered antigen.
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Affiliation(s)
- He-Ping Zhao
- Division of Swine Infectious Diseases, National Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, The Chinese Academy of Agricultural Sciences, Harbin, Heilongjiang, China
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6
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Efficient secretion of the herpes simplex virus tegument protein VP22 from living mammalian cells. Arch Virol 2008; 153:1191-5. [DOI: 10.1007/s00705-008-0094-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2007] [Accepted: 03/17/2008] [Indexed: 11/25/2022]
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Sciortino MT, Taddeo B, Giuffrè-Cuculletto M, Medici MA, Mastino A, Roizman B. Replication-competent herpes simplex virus 1 isolates selected from cells transfected with a bacterial artificial chromosome DNA lacking only the UL49 gene vary with respect to the defect in the UL41 gene encoding host shutoff RNase. J Virol 2007; 81:10924-32. [PMID: 17670820 PMCID: PMC2045545 DOI: 10.1128/jvi.01239-07] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
To generate a null U(L)49 gene mutant of herpes simplex virus 1 (HSV-1), we deleted from the viral DNA, encoded as a bacterial artificial chromosome (BAC), the U(L)49 open reading frame and, in a second step, restored it. Upon transfection into Vero cells, the BAC-DeltaU(L)49 DNA yielded foci of degenerated cells that could not be expanded and a few replication-competent clones. The replication-competent viral clones derived from independent transfections yielded viruses that expressed genes with some delay, produced smaller plaques, and gave lower yields than wild-type virus. A key finding is that the independently derived replication-competent viruses lacked the virion host shutoff (vhs) activity expressed by the RNase encoded by the U(L)41 gene. One mutant virus expressed no vhs protein, whereas two others, derived from independent transfections, produced truncated vhs proteins consistent with the spontaneous in-frame deletion. In contrast, cells infected with the virus recovered upon transfection of the BAC-U(L)49R DNA (R-U(L)49) accumulated a full-length vhs protein, indicating that in the parental BAC-DeltaU(L)49 DNA, the U(L)41 gene was intact. We conclude that expression of the vhs protein in the absence of U(L)49 protein is lethal, a conclusion bolstered by the evidence reported elsewhere that in transfected cells vhs requires both VP16 and VP22, the product of U(L)49, to be neutralized.
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Affiliation(s)
- Maria Teresa Sciortino
- University of Chicago, Viral Oncology Laboratory, 910 East 58th St., Chicago, IL 60637, USA
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8
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Taddeo B, Sciortino MT, Zhang W, Roizman B. Interaction of herpes simplex virus RNase with VP16 and VP22 is required for the accumulation of the protein but not for accumulation of mRNA. Proc Natl Acad Sci U S A 2007; 104:12163-8. [PMID: 17620619 PMCID: PMC1924560 DOI: 10.1073/pnas.0705245104] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The virion host shutoff (vhs) protein encoded by the U(L)41 gene of herpes simplex virus 1 is an endoribonuclease. The enzyme is introduced into the cell during unpackaging of the virion upon entry and selectively degrades mRNA for several hours. The RNase activity ceases after the onset of synthesis of late (gamma) viral proteins. Here we report that vhs protein does not accumulate in cells transiently transfected with only a plasmid encoding the U(L)41 gene. However, vhs does accumulate in cells cotransfected with plasmids expressing two other tegument proteins, VP16 and VP22. vhs does not directly interact with VP22 but, instead, binds VP22 only in the presence of VP16. In contrast to these findings, the amounts of vhs mRNA accumulating in the cells transfected solely with vhs are not significantly different from those detected in cells coexpressing vhs, VP16, and VP22. We conclude from these studies that the steady state of vhs mRNA, reflecting synthesis and turnover of mRNA, is not affected by the interaction of vhs protein with VP16 with VP22. A model is proposed in which the vhs protein may function to sequester mRNAs in compartments inaccessible to the cellular translational machinery and that VP16 and VP22 rescue the mRNAs by interacting with the vhs protein.
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Affiliation(s)
- Brunella Taddeo
- *The Marjorie Kovler Viral Oncology Laboratories, University of Chicago, 910 East 58th Street, Chicago, IL 60637; and
| | - Maria Teresa Sciortino
- Department of Microbiological, Genetic, and Molecular Sciences, University of Messina, Salita Sperone, 31, 98166 Messina, Italy
| | - Weiran Zhang
- *The Marjorie Kovler Viral Oncology Laboratories, University of Chicago, 910 East 58th Street, Chicago, IL 60637; and
| | - Bernard Roizman
- *The Marjorie Kovler Viral Oncology Laboratories, University of Chicago, 910 East 58th Street, Chicago, IL 60637; and
- To whom correspondence should be addressed. E-mail:
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9
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Lemken ML, Wolf C, Wybranietz WA, Schmidt U, Smirnow I, Bühring HJ, Mack AF, Lauer UM, Bitzer M. Evidence for intercellular trafficking of VP22 in living cells. Mol Ther 2007; 15:310-9. [PMID: 17235309 DOI: 10.1038/sj.mt.6300013] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The intercellular trafficking property of the herpes simplex virus type 1 tegument protein VP22 makes it a promising tool for overcoming low transduction efficiencies in gene therapy. However, recent reports suggest not only that VP22 cannot facilitate intercellular spreading and that trafficking of VP22 fusion proteins results from artifacts of cell fixation only. To provide direct evidence for the presence or absence of VP22-mediated intercellular trafficking, we generated an adenoviral vector with a dual expression cassette for VP22 fused to green fluorescent protein (VP22 GFP) and DsRed under the control of distinct human cytomegalovirus immediate-early enhancer/promoter regions. Using this vector, we were able to distinguish clearly between primary transduced cells and cells taking up VP22GFP by intercellular trafficking. To our knowledge, for the first time, we could demonstrate by live-cell confocal fluorescence microscopy that VP22GFP can be found intracellularly in unfixed recipient cells. The extent of VP22 spread was similar in paraformaldehyde-fixed cells and unfixed cells as demonstrated by fluorescence-activated cell sorting analysis. We thus confirmed the ability of VP22-mediated intercellular trafficking in live unfixed cells.
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Affiliation(s)
- Marie-Luise Lemken
- Department of Internal Medicine I, University Clinic Tübingen, Tübingen, Germany
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10
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11
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Lee KC, Hamstra DA, Bullarayasamudram S, Bhojani MS, Moffat BA, Dornfeld KJ, Ross BD, Rehemtulla A. Fusion of the HSV-1 tegument protein vp22 to cytosine deaminase confers enhanced bystander effect and increased therapeutic benefit. Gene Ther 2006; 13:127-37. [PMID: 16163381 DOI: 10.1038/sj.gt.3302631] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2005] [Revised: 05/07/2005] [Accepted: 06/30/2005] [Indexed: 11/09/2022]
Abstract
A major limitation in cancer gene therapy, specifically gene-dependent enzyme prodrug therapy (GDEPT), is inefficient gene delivery and expression. The suicide gene cytosine deaminase (CD) and its substrate, 5-fluorocytosine (5-FC), have been extensively explored due to the inherent 'bystander' effect achieved through diffusion of the toxic metabolite 5-fluorouracil (5-FU). In this study, we aimed to enhance this 'bystander' effect by fusing the Saccharomyces cerevisiae CD to the HSV-1 tegument protein vp22, a novel translocating protein. Two constructs were created: one with vp22 fused to CD (vp22CD) and a second wherein a truncated vp22, lacking the necessary residues for trafficking, fused to CD (delvp22CD). The generated 9L stable lines exhibited similar growth rates, enzyme expression, CD activity, and sensitivity to 5-FC and 5-FU. However, mixed population colony formation assays demonstrated greater bystander effect with the vp22CD fusion as compared to delvp22CD. This enhancement was maintained in vivo where 9L tumors expressing 20 or 50% vp22CD exhibited increased growth delay compared to the respective delvp22CD tumors. Moreover, adenoviral transduction of established wild-type 9L tumors showed increased growth delay with vp22CD (Ad-EF_vp22CD) as compared to equivalent CD (Ad-EF_CD) transduced tumors. Finally, confirming the increased efficacy, (19)F magnetic resonance spectroscopy (MRS) of vp22CD-expressing tumors demonstrated increased 5-FU levels as compared to tumors expressing the nontranslocating CD. These results together demonstrated that fusion of vp22 to CD resulted in CD translocation, which in turn amplified conversion of 5-FC to 5-FU in vivo and enhanced the therapeutic benefit of this GDEPT strategy.
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Affiliation(s)
- K C Lee
- Department of Biological Chemistry, The University of Michigan Medical Center, Ann Arbor, 48109, USA
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12
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Zheng CF, Brownlie R, Huang DY, Babiuk LA, van Drunen Littel-van den Hurk S. Intercellular trafficking of the major tegument protein VP22 of bovine herpesvirus-1 and its application to improve a DNA vaccine. Arch Virol 2005; 151:985-93. [PMID: 16374718 DOI: 10.1007/s00705-005-0694-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2005] [Accepted: 11/16/2005] [Indexed: 10/25/2022]
Abstract
Intercellular spread of bovine herpesvirus-1 (BHV-1) VP22 was demonstrated in living COS-7 cells transfected with a plasmid expressing VP22-YFP (yellow fluorescence protein) and CFP (cyan fluorescence protein) bicistronically. The intercellular trafficking property of VP22 was localized to the C-terminal portion of the molecule (amino acids 121-258; VP22-C). Plasmids encoding a truncated form of BHV-1 glycoprotein D (tgD) fused to VP22, VP22-C, or the N-terminal portion of VP22 (amino acids 1-120; VP22-N) were constructed. Mice immunized with plasmid encoding tgD-VP22 or tgD-VP22-C developed stronger immune responses when compared to animals immunized with plasmid encoding tgD or tgD fused to tgD-VP22-N.
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Affiliation(s)
- C F Zheng
- Vaccine and Infectious Disease Organization, University of Saskatchewan, Saskatoon, Canada
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13
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Zavaglia D, Lin EH, Guidetti M, Pluquet O, Hainaut P, Favrot MC, Coll JL. Poor intercellular transport and absence of enhanced antiproliferative activity after non-viral gene transfer of VP22-P53 or P53-VP22 fusions into p53 null cell lines in vitro or in vivo. J Gene Med 2005; 7:936-44. [PMID: 15754307 DOI: 10.1002/jgm.741] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND The herpes simplex virus type 1 (HSV-1) VP22 protein has the property to mediate intercellular trafficking of heterologous proteins fused to its C- or N-terminus. We have previously shown improved delivery and enhanced therapeutic effect in vitro and in vivo with a P27-VP22 fusion protein. In this report, we were interested in studying the spread and biological activity of VP22 fused to the P53 tumor suppressor. METHODS Expression of the VP22-P53 and P53-VP22 fusion proteins was shown by Western blot and intercellular spreading was monitored by immunofluorescence on transiently transfected cells. In vitro antiproliferative activity of wild-type (wt) P53 and P53-VP22 was assessed by proliferation assays and transactivating ability was studied by a reporter gene test and a gel-shift assay. Antitumor activity was also tested in vivo by intratumoral injections of naked DNA in a model of subcutaneous tumors implanted in nude mice. RESULTS Our results show that the C-terminal fusion or the N-terminal P53-VP22 fusion proteins are not able to spread as efficiently as VP22. Moreover, we demonstrate that VP22-P53 does not possess any transactivating ability. P53-VP22 has an antiproliferative activity, but this activity is not superior to the one of P53 alone, in vitro or in vivo. CONCLUSIONS Our study indicates that a gene transfer strategy using VP22 cannot be considered as a universal system to improve the delivery of any protein.
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Affiliation(s)
- David Zavaglia
- Groupe de Recherche sur le Cancer du Poumon, INSERM U578, Institut Albert Bonniot, 38706 La Tronche, France
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Hakkarainen T, Wahlfors T, Meriläinen O, Loimas S, Hemminki A, Wahlfors J. VP22 does not significantly enhance enzyme prodrug cancer gene therapy as a part of a VP22-HSVTk-GFP triple fusion construct. J Gene Med 2005; 7:898-907. [PMID: 15759279 DOI: 10.1002/jgm.737] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND VP22 is a herpes simplex virus type 1 (HSV-1) tegument protein that has been suggested to spread from cell to cell, alone or as a part of fusion proteins. Creating controversy, some reports indicate that VP22 cannot facilitate significant intercellular spreading. To study the capacity of VP22 to cause spreading and enhance thymidine kinase/ganciclovir cancer gene therapy, we constructed a novel triple fusion protein containing VP22, HSV thymidine kinase and green fluorescent protein (VP22-Tk-GFP). This fusion protein has three functional domains in the same polypeptide, thus making it possible to reliably compare the causality between transduction rate and cell killing efficiency in vitro and in vivo. METHODS VP22-Tk-GFP was cloned into lenti- and adenoviral vectors and used for expression studies, analyses for VP22-mediated protein spreading, and to study the effect of VP22 to thymidine kinase/ganciclovir-mediated cytotoxicity. The function of VP22-Tk-GFP was also investigated in vivo. RESULTS The triple fusion protein was expressed correctly in vitro, but intercellular trafficking was not observed in any of the studied cell lines. However, under certain conditions, VP22-Tk-GFP sensitized cells more efficiently to ganciclovir than Tk-GFP. In vivo there was a trend for increased inhibition of tumor growth with VP22-Tk-GFP when ganciclovir was present, but the difference with Tk-GFP was not statistically significant. CONCLUSIONS Based on our results, VP22 fusion proteins do not seem to traffic intercellularly at detectable levels in most tumor cell types. Even though VP22 enhanced cytotoxicity in one cell line in vitro, the effect in vivo was modest. Therefore, our results do not support the utility of VP22 as an enhancer of enzyme prodrug cancer gene therapy.
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Affiliation(s)
- Tanja Hakkarainen
- A. I. Virtanen Institute, Department of Biotechnology and Molecular Medicine, University of Kuopio, FIN-70211 Kuopio, Finland
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15
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Perkins SD, Hartley MG, Lukaszewski RA, Phillpotts RJ, Stevenson FK, Bennett AM. VP22 enhances antibody responses from DNA vaccines but not by intercellular spread. Vaccine 2005; 23:1931-40. [PMID: 15734065 DOI: 10.1016/j.vaccine.2004.10.033] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2004] [Accepted: 10/18/2004] [Indexed: 11/29/2022]
Abstract
In some species DNA vaccines elicit potent humoral and cellular immune responses. However, their performance in humans and non-human primates is less impressive. There are suggestions in the literature that an increase in the intercellular distribution of protein expressed from a DNA vaccine may enhance immunogenicity. We incorporated the Herpes Simplex Virus type 1 (HSV) VP22 gene, which encodes a protein that has been described as promoting intercellular spread, into a DNA vector in which it was fused to enhanced green fluorescent protein (EGFP). Following transfection of the plasmid DNA into mammalian cells, distribution of the fusion protein VP22-EGFP was not increased compared to EGFP alone. Furthermore, we found no evidence to suggest that VP22 was capable of mediating intercellular spread. However, when these constructs were used as DNA vaccines to immunise mice, antibody levels specific to EGFP were significantly enhanced when EGFP was fused to VP22. These data suggest that amplification of the immune response may occur via mechanisms other than VP22-mediated intercellular spread of antigen.
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Affiliation(s)
- Stuart D Perkins
- Biomedical Sciences Department, Defence Science and Technology Laboratory, Porton Down, Salisbury, Wiltshire SP4 OJQ, UK.
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16
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Zheng C, Babiuk LA, van Drunen Littel-van den Hurk S. Bovine herpesvirus 1 VP22 enhances the efficacy of a DNA vaccine in cattle. J Virol 2005; 79:1948-53. [PMID: 15650221 PMCID: PMC544085 DOI: 10.1128/jvi.79.3.1948-1953.2005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
For this study, the intercellular trafficking ability of bovine herpesvirus 1 (BHV-1) VP22 was applied to improve the efficacy of a DNA vaccine in calves. A plasmid encoding a truncated version of glycoprotein D (tgD) fused to VP22 was constructed. The plasmid encoding tgD-VP22 elicited significantly enhanced and more balanced immune responses than those induced by a plasmid encoding tgD. Furthermore, protection against a BHV-1 challenge was obtained in calves immunized with the plasmid encoding tgD-VP22, as shown by significant reductions in viral excretion. However, less significant protection was observed for animals vaccinated with the tgD-expressing plasmid, correlating with the lower level of immunity observed prechallenge. This is the first report of the use of VP22 as a transport molecule in the context of a DNA vaccine for a large animal species.
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Affiliation(s)
- Chunfu Zheng
- Vaccine and Infectious Disease Organization, University of Saskatchewan, 120 Veterinary Rd., Saskatoon, SK S7N 5E3, Canada
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17
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Dietz GPH, Bähr M. Delivery of bioactive molecules into the cell: the Trojan horse approach. Mol Cell Neurosci 2005; 27:85-131. [PMID: 15485768 DOI: 10.1016/j.mcn.2004.03.005] [Citation(s) in RCA: 358] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2003] [Revised: 02/17/2004] [Accepted: 03/16/2004] [Indexed: 01/12/2023] Open
Abstract
In recent years, vast amounts of data on the mechanisms of neural de- and regeneration have accumulated. However, only in disproportionally few cases has this led to efficient therapies for human patients. Part of the problem is to deliver cell death-averting genes or gene products across the blood-brain barrier (BBB) and cellular membranes. The discovery of Antennapedia (Antp)-mediated transduction of heterologous proteins into cells in 1992 and other "Trojan horse peptides" raised hopes that often-frustrating attempts to deliver proteins would now be history. The demonstration that proteins fused to the Tat protein transduction domain (PTD) are capable of crossing the BBB may revolutionize molecular research and neurobiological therapy. However, it was only recently that PTD-mediated delivery of proteins with therapeutic potential has been achieved in models of neural degeneration in nerve trauma and ischemia. Several groups have published the first positive results using protein transduction domains for the delivery of therapeutic proteins in relevant animal models of human neurological disorders. Here, we give an extensive review of peptide-mediated protein transduction from its early beginnings to new advances, discuss their application, with particular focus on a critical evaluation of the limitations of the method, as well as alternative approaches. Besides applications in neurobiology, a large number of reports using PTD in other systems are included as well. Because each protein requires an individual purification scheme that yields sufficient quantities of soluble, transducible material, the neurobiologist will benefit from the experiences of other researchers in the growing field of protein transduction.
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Soboleski MR, Oaks J, Halford WP. Green fluorescent protein is a quantitative reporter of gene expression in individual eukaryotic cells. FASEB J 2005; 19:440-2. [PMID: 15640280 PMCID: PMC1242169 DOI: 10.1096/fj.04-3180fje] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Green fluorescent protein (GFP) has gained widespread use as a tool to visualize spatial and temporal patterns of gene expression in vivo. However, it is not generally accepted that GFP can also be used as a quantitative reporter of gene expression. We report that GFP is a reliable reporter of gene expression in individual eukaryotic cells when fluorescence is measured by flow cytometry. Two pieces of evidence support this conclusion: GFP fluorescence increases in direct proportion to the GFP gene copy number delivered to cells by a replication-defective adenovirus vector, Ad.CMV-GFP, and the intensity of GFP fluorescence is directly proportional to GFP mRNA abundance in cells. This conclusion is further supported by the fact that the induction of GFP gene expression from two inducible promoters (i.e., the TRE and ICP0 promoters) is readily detected by flow cytometric measurement of GFP fluorescent intensity. Collectively, the results presented herein indicate that GFP fluorescence is a reliable and quantitative reporter of underlying differences in gene expression.
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Affiliation(s)
- Mark R. Soboleski
- Department of Microbiology and Immunology, Tulane University Medical School, New Orleans, LA 70112
| | - Jason Oaks
- Department of Microbiology and Immunology, Tulane University Medical School, New Orleans, LA 70112
| | - William P. Halford
- Department of Microbiology and Immunology, Tulane University Medical School, New Orleans, LA 70112
- *Corresponding author: William P. Halford, Department of Veterinary Molecular Biology, 960 Technology Boulevard, Bozeman, MT 59718, Phone: (406) 994-6374, FAX: (406) 994-4303, Electronic mail:
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19
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Manoj S, Babiuk LA, van Drunen Littel-van den Hurk S. Approaches to enhance the efficacy of DNA vaccines. Crit Rev Clin Lab Sci 2004; 41:1-39. [PMID: 15077722 DOI: 10.1080/10408360490269251] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
DNA vaccines consist of antigen-encoding bacterial plasmids that are capable of inducing antigen-specific immune responses upon inoculation into a host. This method of immunization is advantageous in terms of simplicity, adaptability, and cost of vaccine production. However, the entry of DNA vaccines and expression of antigen are subjected to physical and biochemical barriers imposed by the host. In small animals such as mice, the host-imposed impediments have not prevented DNA vaccines from inducing long-lasting, protective humoral, and cellular immune responses. In contrast, these barriers appear to be more difficult to overcome in large animals and humans. The focus of this article is to summarize the limitations of DNA vaccines and to provide a comprehensive review on the different strategies developed to enhance the efficacy of DNA vaccines. Several of these strategies, such as altering codon bias of the encoded gene, changing the cellular localization of the expressed antigen, and optimizing delivery and formulation of the plasmid, have led to improvements in DNA vaccine efficacy in large animals. However, solutions for increasing the amount of plasmid that eventually enters the nucleus and is available for transcription of the transgene still need to be found. The overall conclusions from these studies suggest that, provided these critical improvements are made, DNA vaccines may find important clinical and practical applications in the field of vaccination.
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Affiliation(s)
- Sharmila Manoj
- Vaccine and Infectious Disease Organization, University of Saskatchewan, Saskatoon, Canada
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20
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Tréhin R, Merkle HP. Chances and pitfalls of cell penetrating peptides for cellular drug delivery. Eur J Pharm Biopharm 2004; 58:209-23. [PMID: 15296950 DOI: 10.1016/j.ejpb.2004.02.018] [Citation(s) in RCA: 153] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2003] [Accepted: 02/24/2004] [Indexed: 11/17/2022]
Abstract
Over the past decade, several classes and/or prototypes of cell penetrating peptides (CPP) have been identified and investigated in multiple aspects. CPP represent peptides, which show the ability to cross the plasma membrane of mammalian cells, and may thus give rise to the intracellular delivery of problematic therapeutic cargos, such as peptides, proteins, oligonucleotides, plasmids and even nanometer-sized particles, which otherwise cannot cross the plasma membrane. Most of the currently recognized CPP are of cationic nature and derived from viral, insect or mammalian proteins endowed with membrane translocation properties. The exact mechanisms underlying the translocation of CPP across the cellular membrane are still poorly understood. However, several similarities in translocation can be found. Early studies on CPP translocation mechanisms tended to suggest that the internalization of these peptides was neither significantly inhibited by low temperature, depletion of the cellular adenosine triphosphate (ATP) pool, nor by inhibitors of endocytosis. Moreover, chemical modification of the peptide sequence, such as the synthesis of retro-, enantio- or retroenantio-analogs, appeared not to affect the internalization properties. Therefore, translocation was concluded to result from direct, physical transfer through the lipid bilayer of the cell membrane. Later studies, however, showed convincing evidence for the involvement of endocytosis as the dominating mechanism for cellular internalization. In addition to describing the general properties of the commonly recognized classes of CPP, in this review we will also point out some limitations and typical pitfalls of CPP as carriers for therapeutics. In particular we will comment on emerging discrepancies with the current dogma, on cell-to-cell variability, biological barrier permeability, metabolic fate, toxicity and immunogenicity of CPP.
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Affiliation(s)
- Rachel Tréhin
- Center for Molecular Imaging Research (CMIR), Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA.
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21
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Pastori RL, Klein D, Ribeiro MM, Ricordi C. DELIVERY OF PROTEINS AND PEPTIDES INTO LIVE CELLS BY MEANS OF PROTEIN TRANSDUCTION DOMAINS: POTENTIAL APPLICATION TO ORGAN AND CELL TRANSPLANTATION. Transplantation 2004; 77:1627-31. [PMID: 15201657 DOI: 10.1097/01.tp.0000119589.12467.20] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Ricardo L Pastori
- Diabetes Research Institute, University of Miami School of Medicine, Miami, FL 33136, USA.
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22
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Leifert JA, Holler PD, Harkins S, Kranz DM, Whitton JL. The cationic region from HIV tat enhances the cell-surface expression of epitope/MHC class I complexes. Gene Ther 2003; 10:2067-73. [PMID: 14595379 DOI: 10.1038/sj.gt.3302115] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The potential of genetic immunization has been acknowledged for almost a decade, but disappointing immunogenicity in humans has delayed its introduction into the clinical arena. To try to increase the potency of genetic immunization, we and others have evaluated 'translocatory' proteins, which are thought to exit living cells by an uncharacterized pathway, and enter neighboring cells in an energy-independent manner. Several laboratories, including our own, have begun to question these remarkable properties. Our previous studies showed that the ability of an epitope to induce major histocompatibility complex (MHC) class I restricted CD8(+) T cells was, indeed, enhanced by its being attached to the proposed translocatory sequence of the HIV-1 tat protein. However, we found little evidence that the increased immunogenicity resulted from transfer of the fusion peptide between living cells, and we proposed that it resulted instead from an increased epitope/MHC expression on the surface of transfected cells. Here, we directly test this hypothesis. We show that cells cotransfected with plasmids encoding an epitope, and the relevant MHC class I allele, can stimulate epitope-specific T cells, and that attachment of the epitope to a putative translocatory sequence - which we term herein an 'integral cationic region' (ICR) - leads to a marked increase in stimulatory activity. This elevated stimulatory capacity does not result from a nonspecific increase in MHC class I expression. We use a high-affinity T-cell receptor (TcR) specific for the epitope/MHC combination to quantitate directly the cell-surface expression of the immunogenic complex, and we show that the attachment of the tat ICR to an epitope results in a substantial enhancement of its cell-surface presentation. These data suggest an alternative explanation for the immune enhancement seen with ICRs.
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Affiliation(s)
- J A Leifert
- Department of Neuropharmacology, The Scripps Research Institute, La Jolla, CA 92037, USA
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23
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Kueltzo LA, Middaugh CR. Nonclassical transport proteins and peptides: an alternative to classical macromolecule delivery systems. J Pharm Sci 2003; 92:1754-72. [PMID: 12949995 DOI: 10.1002/jps.10448] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The number of peptides and proteins known to exhibit nonclassical transport activity has increased significantly in recent years. In most cases, these entities have been studied in relation to their ability to deliver high molecular weight compounds, including proteins and DNA, for the ultimate purpose of developing new drug delivery strategies. In this review, an overview of the various types of vectors is presented. The in vitro and in vivo delivery successes of this technology, as well as preliminary therapeutic efforts, are described. Although a comprehensive mechanism of nonclassical transport has not yet been clearly established, we propose a straightforward model based on the cationic nature of the vectors and the need for lack of highly organized structure. In this hypothesis we suggest that the movement of polycations is mediated by a network of extra- and intracellular polyanions while transport across the bilayer is facilitated by cation-pi interactions between the vectors' basic groups and aromatic amino acid side chains in the bilayer spanning helices of membrane proteins.
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Affiliation(s)
- Lisa A Kueltzo
- Department of Pharmaceutical Chemistry, University of Kansas, 2095 Constant Ave., Lawrence, Kansas 66047, USA
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24
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Leifert JA, Whitton JL. "Translocatory proteins" and "protein transduction domains": a critical analysis of their biological effects and the underlying mechanisms. Mol Ther 2003; 8:13-20. [PMID: 12842424 DOI: 10.1016/s1525-0016(03)00151-5] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
It has been suggested that several proteins, termed "translocatory" or "messenger" proteins, can move between living cells-exiting the cell of synthesis via an uncharacterized secretory pathway and entering adjacent cells by a nonendocytic mechanism that is active even at 4 degrees C. These activities, which have been mapped to short, highly basic regions termed "protein transduction domains" (PTDs), have engendered considerable interest in the gene therapy and vaccine research communities. If these proteins, and PTDs, are to be used in human or veterinary medicine, it is vital that the mechanisms underlying their effects be understood. This article presents a critical evaluation of the current literature and describes recent findings that indicate that the effects of these sequences might be explained by well-established biological principles.
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Affiliation(s)
- Jens A Leifert
- Department of Neuropharmacology, CVN-9, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, USA
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25
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Lundberg M, Wikström S, Johansson M. Cell surface adherence and endocytosis of protein transduction domains. Mol Ther 2003; 8:143-50. [PMID: 12842437 DOI: 10.1016/s1525-0016(03)00135-7] [Citation(s) in RCA: 230] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Protein transduction domains (PTD), such as the HIV TAT and the herpes simplex virus VP22 proteins, are reported to translocate across the membranes of mammalian cells. The mechanism of PTD membrane translocation has largely remained elusive, but recent studies suggest that the reported PTD translocation is due to a fixation artifact. We have constructed and expressed the PTDs VP22, TAT, polyarginine, and polylysine fused to the green fluorescent protein to visualize these proteins in both living and fixed cells. The investigated PTDs strongly adhered to the surface of living cells and were internalized by constitutive endocytosis. No cytosolic or nuclear import of the proteins was detected. In contrast, the PTD-GFP fusion proteins were redistributed to the cytosol and nucleus directly after fixation. Our findings suggest that the PTDs only mediate cell surface adherence, a property shared with many other positively charged macromolecules. The cell surface adherence results in endocytosis and accumulation of proteins in endosomes. We suggest that the biological effects observed for PTD fusion proteins are due to cell surface interactions and internalization of the proteins into cells by classical endocytosis.
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Affiliation(s)
- Mathias Lundberg
- Division of Clinical Virology F68, Karolinska Institute, Huddinge University Hospital, S-14186, Stockholm, Sweden
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26
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Zavaglia D, Favrot MC, Eymin B, Tenaud C, Coll JL. Intercellular trafficking and enhanced in vivo antitumour activity of a non-virally delivered P27-VP22 fusion protein. Gene Ther 2003; 10:314-25. [PMID: 12595890 DOI: 10.1038/sj.gt.3301904] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
VP22, a structural protein from herpes simplex virus type I, exhibits the unique property of intercellular trafficking. This protein is exported from primary expressing cells and subsequently imported into neighbouring cells. This property is conserved when VP22 is genetically fused to a protein, making it a promising tool to enhance the delivery of a gene product. We chose to study the intercellular transport and biological effect of a fusion protein between the putative tumour suppressor gene p27(Kip1) and VP22. We show that in vitro, P27VP22 is able to spread as efficiently as VP22. Functionality of the P27VP22 protein was demonstrated by its ability to inhibit cyclin/CDK2 complexes activity. In proliferation and clonogenicity assays, transfection with the P27VP22 plasmid resulted in a stronger cell growth inhibition when compared to transfection with the p27(Kip1) vector. In vivo, sub cutaneous tumours established in nude mice were injected with naked DNA encoding P27 or P27VP22. Our results show that P27VP22 can spread in vivo and that injections of the P27VP22 plasmid resulted in a significantly greater antitumour activity than injections of the P27 plasmid. This study confirms the usefulness of VP22-mediated delivery and suggests that P27VP22 may have applications in cancer gene therapy.
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Affiliation(s)
- D Zavaglia
- Groupe de Recherche sur le Cancer du Pumon, Equipe INSERM 9924, Institut Albert Bonnoit, La Tronche cedex, France
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27
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Cashman SM, Sadowski SL, Morris DJ, Frederick J, Kumar-Singh R. Intercellular trafficking of adenovirus-delivered HSV VP22 from the retinal pigment epithelium to the photoreceptors--implications for gene therapy. Mol Ther 2002; 6:813-23. [PMID: 12498777 DOI: 10.1006/mthe.2002.0806] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Adenovirus (Ad)-mediated gene transfer is a promising technology for therapy of a wide variety of genetic disorders of the retina. The tropism of Ad vectors limits their utility to cells that express the coxsackie-adenovirus receptor. Upon ocular delivery, Ad vectors primarily infect the retinal pigment epithelium (RPE) and the Müller cells of the retina. However, the most frequent blinding diseases such as retinitis pigmentosa and age-related macular degeneration are associated with the expression of mutant proteins in the photoreceptors. In this study we demonstrate that adenovirus-delivered heterologous proteins fused to the herpes simplex virus tegument protein VP22 can translocate from infected cells to uninfected cells in culture and in vivo. We tested three different ocular cell lines, specifically Y79, RPE-J, and Chang C. We show that there is a 3.25-fold increase in the number of Y79 cells that take up GFP mediated by the intercellular trafficking properties of VP22. Our data are based on FACS analysis of living cells and there was no need for cell fixation for the effect to be observed. When adenovirus expressing a VP22-GFP fusion was injected into the subretinal space of adult mice, the VP22-GFP fusion peptides translocated from the RPE to all of the other layers of the retina, including the outer nuclear layer, which contains the photoreceptor cell bodies. Our study has significant implications for a wide variety of diseases of the retina and other organ systems.
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Affiliation(s)
- Siobhan M Cashman
- Department of Ophthalmology, University of Utah, Salt Lake City, Utah 84112-5330, USA
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28
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Lundberg M, Johansson M. Positively charged DNA-binding proteins cause apparent cell membrane translocation. Biochem Biophys Res Commun 2002; 291:367-71. [PMID: 11846414 DOI: 10.1006/bbrc.2002.6450] [Citation(s) in RCA: 177] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Several positively charged DNA-binding proteins such as the human immunodeficiency virus Tat protein, the Antennapedia (Antp) homeobox protein, and the herpes simplex virus VP22 protein have been reported to translocate across cell membranes and accumulate in cell nuclei. The import occurs by a poorly understood mechanism that appears to be receptor- and energy-independent. We showed that both VP22 and the positively charged histone H1 adhered to the cell membrane of living cells and were not removed by extensive washing. However, after fixation the proteins relocated to the cell nucleus. The nuclear accumulation of VP22 and histone H1 after fixation shows that positively charged proteins may appear to translocate across the cell membrane because of a fixation artifact. The majority of studies on "membrane permeable" proteins and peptides have been performed using fixation techniques, and our study shows that influx of these proteins may occur during fixation rather than in living cells.
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Affiliation(s)
- Mathias Lundberg
- Medical Nobel Institute for Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
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29
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Fischer PM, Krausz E, Lane DP. Cellular delivery of impermeable effector molecules in the form of conjugates with peptides capable of mediating membrane translocation. Bioconjug Chem 2001; 12:825-41. [PMID: 11716670 DOI: 10.1021/bc0155115] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Most molecules that are not actively imported by living cells are impermeable to cell membranes, including practically all macromolecules and even many small molecules whose physicochemical properties prevent passive membrane diffusion. The use of peptide vectors capable of transporting such molecules into cells in the form of covalent conjugates has become an increasingly attractive solution to this problem. Not only has this technology permitted the study of modulating intracellular target proteins, but it has also gained importance as an alternative to conventional cellular transfection with oligonucleotides. Peptide vectors derived from viral, bacterial, insect, and mammalian proteins endowed with membrane translocation properties have now been proposed as delivery vectors. These are discussed comprehensively and critically in terms of relative utility, applications to compound classes and specific molecules, and relevant conjugation chemistry. Although in most cases the mechanisms of membrane translocation are still unclear, physicochemical studies have been carried out with a number of peptide delivery vectors. Unifying and distinguishing mechanistic features of the various vectors are discussed. Until a few years ago speculations that it might be possible to deliver peptides, proteins, oligonucleotides, and impermeable small molecules with the aid of cellular delivery peptides not only to target cells in vitro, but in vivo, was received with scepticism. However, the first studies showing pharmacological applications of conjugates between macromolecules and peptide delivery vectors are now being reported, and therapies based on such conjugates are beginning to appear feasible.
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Affiliation(s)
- P M Fischer
- Cyclacel Limited, Dundee Technopole, James Lindsay Place, Dundee DD1 5JJ, Scotland, UK.
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30
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Wybranietz WA, Gross CD, Phelan A, O'Hare P, Spiegel M, Graepler F, Bitzer M, Stähler P, Gregor M, Lauer UM. Enhanced suicide gene effect by adenoviral transduction of a VP22-cytosine deaminase (CD) fusion gene. Gene Ther 2001; 8:1654-64. [PMID: 11895004 DOI: 10.1038/sj.gt.3301564] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The low transduction efficiency of viral and nonviral vectors is a major limitation in tumour gene therapy. The HSV-1 tegument protein VP22 has been shown to exhibit a novel intercellular transport property. VP22 wild-type as well as VP22 fusion proteins efficiently spread from the original expressing cell to numerous neighbouring cells, so that protein transport by VP22 chimaeric polypeptides into the surrounding cells offers a possible compensation for the inadequate gene transfer efficiencies. To improve the therapeutic efficacy of the E. coli cytosine deaminase (CD) suicide gene we made use of the VP22 transport property in CD transducing adenoviral (Ad) vectors. C- and N-terminal fusions of CD linked in-frame with VP22 were generated and cloned into recombinant adenoviral vectors. Following in vitro transduction immunofluorescence analysis of Ad-transduced producer cells coplated with naive cells confirmed that the characteristic foci pattern of central producer and adjoining neighbour cells displaying nuclear staining was retained. After transduction of rat hepatoma cells with adenoviral vectors and subsequent incubation with the prodrug 5-FC, we observed enhanced cell cytotoxicity when comparing the CD-VP22 fusion (Ad-CD-VP22) with Ad-vectors expressing the CD gene only (Ad-CD). Thereby employment of Ad-vectors encoding VP22 fusion proteins opens up new possibilities to potentiate the efficiency of suicide gene therapy for the treatment of solid tumours.
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Affiliation(s)
- W A Wybranietz
- Internal Medicine I, Medical University Clinic Tübingen, Germany
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31
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33
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Aints A, Güven H, Gahrton G, Smith CI, Dilber MS. Mapping of herpes simplex virus-1 VP22 functional domains for inter- and subcellular protein targeting. Gene Ther 2001; 8:1051-6. [PMID: 11526452 DOI: 10.1038/sj.gt.3301493] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2001] [Accepted: 04/20/2001] [Indexed: 11/10/2022]
Abstract
The herpes simplex virus 1 (HSV-1) tegument protein VP22 has been utilised as a vehicle for trafficking proteins. It has a remarkable property of exiting the cell that is producing it and entering the neighbouring cells, which has been used to deliver therapeutic proteins, p53 and herpes simplex virus thymidine kinase (tk). It has a complex pattern of expression and subcellular localisation. Functions of VP22 include intercellular transport, binding to and bundling of microfilaments, inducing cytoskeleton collapse, nuclear translocation during mitosis, and binding to chromatin and nuclear membrane. The regions of VP22 which contain each of these functions have not been characterised. Finding the region carrying the property of intercellular spread would facilitate enhancement of transport function. By constructing a series of deletion constructs of VP22 tagged by the green fluorescent protein (GFP) we have mapped the functions of VP22 to specific regions in the polypeptide as follows: intercellular transport - aa 81-195; binding and reorganisation of cytoskeleton - aa 159-267; nuclear targeting, inhibition of cytoskeleton collapse - aa 81-121; and nuclear targeting and facilitation of intercellular transport - aa 267-301. Separation of VP22 functions enables focus on the mechanism of VP22-mediated transport and improve the transportation efficiency of VP22.
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Affiliation(s)
- A Aints
- Department of Medicine, Clinical Research Centre, Huddinge University Hospital, Karolinska Institutet, Huddinge, Sweden
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34
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Wesche J, Olsnes S. Ability of the Tat basic domain and VP22 to mediate cell binding, but not membrane translocation of the diphtheria toxin A-fragment. Biochemistry 2001; 40:4349-58. [PMID: 11284691 DOI: 10.1021/bi002443l] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A number of proteins are able to enter cells from the extracellular environment, including protein toxins, growth factors, viral proteins, homeoproteins, and others. Many such translocating proteins, or parts of them, appear to be able to carry with them cargo into the cell, and a basic sequence from the HIV-1 Tat protein has been reported to provide intracellular delivery of several fused proteins. For evaluating the efficiency of translocation to the cytosol, this TAT-peptide was fused to the diphtheria toxin A-fragment (dtA), an extremely potent inhibitor of protein synthesis which normally is delivered efficiently to the cytosol by the toxin B-fragment. The fusion of the TAT-peptide to dtA converted the protein to a heparin-binding protein that bound avidly to the cell surface. However, no cytotoxicity of this protein was detected, indicating that the TAT-peptide is unable to efficiently deliver enzymatically active dtA to the cytosol. Interestingly, the fused TAT-peptide potentiated the binding and cytotoxic effect of the corresponding holotoxin. We made a fusion protein between VP22, another membrane-permeant protein, and dtA, and also in this case we detected association with cells in the absence of a cytotoxic effect. The data indicate that transport of dtA into the cell by the TAT-peptide and VP22 is inefficient.
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35
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Kueltzo LA, Middaugh CR. Potential use of non-classical pathways for the transport of macromolecular drugs. Expert Opin Investig Drugs 2000; 9:2039-50. [PMID: 11060791 DOI: 10.1517/13543784.9.9.2039] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Since an increasing number of drug delivery strategies utilising proteins and peptides exhibiting 'non-classical' transport activities have been proposed, studies have begun to establish underlying functional relationships between different vectors. These attempts to find common factors have been hampered by a lack of biophysical data for the various potential protein and peptide transporters, as well as by the structural and functional diversity of the group as a whole. We describe the various types of vectors being considered for use and the preliminary therapeutic successes that have been achieved. Additionally, the various models that have been proposed for non-classical import and export are outlined and discussed in relation to therapeutic delivery. Possible future developments are also discussed.
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Affiliation(s)
- L A Kueltzo
- University of Kansas, Department of Pharmaceutical Chemistry, 2095 Constant Avenue, Lawrence, KS 66047, USA
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36
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Harms JS, Ren X, Oliveira SC, Splitter GA. Distinctions between bovine herpesvirus 1 and herpes simplex virus type 1 VP22 tegument protein subcellular associations. J Virol 2000; 74:3301-12. [PMID: 10708447 PMCID: PMC111831 DOI: 10.1128/jvi.74.7.3301-3312.2000] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The alphaherpesvirus tegument protein VP22 has been characterized with multiple traits including microtubule reorganization, nuclear localization, and nonclassical intercellular trafficking. However, all these data were derived from studies using herpes simplex virus type 1 (HSV-1) and may not apply to VP22 homologs of other alphaherpesviruses. We compared subcellular attributes of HSV-1 VP22 (HVP22) with bovine herpesvirus 1 (BHV-1) VP22 (BVP22) using green fluorescent protein (GFP)-fused VP22 expression vectors. Fluorescence microscopy of cell lines transfected with these constructs revealed differences as well as similarities between the two VP22 homologs. Compared to that of HVP22, the BVP22 microtubule interaction was much less pronounced. The VP22 nuclear interaction varied, with a marbled or halo appearance for BVP22 and a speckled or nucleolus-bound appearance for HVP22. Both VP22 homologs associated with chromatin at various stages of mitosis and could traffic from expressing cells to the nuclei of nonexpressing cells. However, distinct qualitative differences in microtubule, nuclear, and chromatin association as well as trafficking were observed. The differences in VP22 homolog characteristics revealed in this study will help define VP22 function within HSV-1 and BHV-1 infection.
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Affiliation(s)
- J S Harms
- Department of Animal Health and Biomedical Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53706-1581, USA.
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37
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Abstract
We compare methods of detection of intercellular transport of the herpes simplex virus protein VP22 and of a green fluorescent protein (GFP)-VP22 fusion protein. Spread of both proteins was observed by immunofluorescence (IF) using organic fixatives. Spread of both proteins was also detected by IF after paraformaldehyde (PFA) fixation and detergent permeabilization, albeit at reduced levels. However, while spread of GFP-VP22 was observed by examining intrinsic GFP fluorescence after methanol fixation, little spread was observed after PFA fixation, suggesting that the levels of the fusion protein in recipient cells were below the detection limits of intrinsic-fluorescence or that PFA fixation quenches the fluorescence of GFP-VP22. We further considered whether elution of VP22 from methanol-fixed cells and postfixation binding to surrounding cells contributed to the increased detection of spread observed after methanol fixation. The results show that while this could occur, it appeared to be a minor effect not accounting for the observed VP22 cell-to-cell spread in culture.
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Affiliation(s)
- N Brewis
- Marie Curie Research Institute, The Chart, Oxted, Surrey RH8 0TL, United Kingdom
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