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Cafaro A, Schietroma I, Sernicola L, Belli R, Campagna M, Mancini F, Farcomeni S, Pavone-Cossut MR, Borsetti A, Monini P, Ensoli B. Role of HIV-1 Tat Protein Interactions with Host Receptors in HIV Infection and Pathogenesis. Int J Mol Sci 2024; 25:1704. [PMID: 38338977 PMCID: PMC10855115 DOI: 10.3390/ijms25031704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Revised: 01/19/2024] [Accepted: 01/23/2024] [Indexed: 02/12/2024] Open
Abstract
Each time the virus starts a new round of expression/replication, even under effective antiretroviral therapy (ART), the transactivator of viral transcription Tat is one of the first HIV-1 protein to be produced, as it is strictly required for HIV replication and spreading. At this stage, most of the Tat protein exits infected cells, accumulates in the extracellular matrix and exerts profound effects on both the virus and neighbor cells, mostly of the innate and adaptive immune systems. Through these effects, extracellular Tat contributes to the acquisition of infection, spreading and progression to AIDS in untreated patients, or to non-AIDS co-morbidities in ART-treated individuals, who experience inflammation and immune activation despite virus suppression. Here, we review the role of extracellular Tat in both the virus life cycle and on cells of the innate and adaptive immune system, and we provide epidemiological and experimental evidence of the importance of targeting Tat to block residual HIV expression and replication. Finally, we briefly review vaccine studies showing that a therapeutic Tat vaccine intensifies ART, while its inclusion in a preventative vaccine may blunt escape from neutralizing antibodies and block early events in HIV acquisition.
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Affiliation(s)
- Aurelio Cafaro
- National HIV/AIDS Research Center, Istituto Superiore di Sanità, 00161 Rome, Italy; (I.S.); (L.S.); (R.B.); (M.C.); (F.M.); (S.F.); (M.R.P.-C.); (A.B.); (P.M.)
| | | | | | | | | | | | | | | | | | | | - Barbara Ensoli
- National HIV/AIDS Research Center, Istituto Superiore di Sanità, 00161 Rome, Italy; (I.S.); (L.S.); (R.B.); (M.C.); (F.M.); (S.F.); (M.R.P.-C.); (A.B.); (P.M.)
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2
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Gotora PT, van der Sluis R, Williams ME. HIV-1 Tat amino acid residues that influence Tat-TAR binding affinity: a scoping review. BMC Infect Dis 2023; 23:164. [PMID: 36932337 PMCID: PMC10020771 DOI: 10.1186/s12879-023-08123-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 02/27/2023] [Indexed: 03/19/2023] Open
Abstract
HIV-1 remains a global health concern and to date, nearly 38 million people are living with HIV. The complexity of HIV-1 pathogenesis and its subsequent prevalence is influenced by several factors including the HIV-1 subtype. HIV-1 subtype variation extends to sequence variation in the amino acids of the HIV-1 viral proteins. Of particular interest is the transactivation of transcription (Tat) protein due to its key function in viral transcription. The Tat protein predominantly functions by binding to the transactivation response (TAR) RNA element to activate HIV-1 transcriptional elongation. Subtype-specific Tat protein sequence variation influences Tat-TAR binding affinity. Despite several studies investigating Tat-TAR binding, it is not clear which regions of the Tat protein and/or individual Tat amino acid residues may contribute to TAR binding affinity. We, therefore, conducted a scoping review on studies investigating Tat-TAR binding. We aimed to synthesize the published data to determine (1) the regions of the Tat protein that may be involved in TAR binding, (2) key Tat amino acids involved in TAR binding and (3) if Tat subtype-specific variation influences TAR binding. A total of thirteen studies met our inclusion criteria and the key findings were that (1) both N-terminal and C-terminal amino acids outside the basic domain (47-59) may be important in increasing Tat-TAR binding affinity, (2) substitution of the amino acids Lysine and Arginine (47-59) resulted in a reduction in binding affinity to TAR, and (3) none of the included studies have investigated Tat subtype-specific substitutions and therefore no commentary could be made regarding which subtype may have a higher Tat-TAR binding affinity. Future studies investigating Tat-TAR binding should therefore use full-length Tat proteins and compare subtype-specific variations. Studies of such a nature may help explain why we see differential pathogenesis and prevalence when comparing HIV-1 subtypes.
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You Y, Xu L, Li F, Yang F. Proteomic analysis of the Decapod iridescent virus 1. Virus Res 2022; 311:198686. [DOI: 10.1016/j.virusres.2022.198686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 01/12/2022] [Accepted: 01/13/2022] [Indexed: 10/19/2022]
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RGDS- and doxorubicin-modified poly[N-(2-hydroxypropyl)methacrylamide]-coated γ-Fe2O3 nanoparticles for treatment of glioblastoma. Colloid Polym Sci 2021. [DOI: 10.1007/s00396-021-04895-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Pal P, Nguyen QC, Benton AH, Marquart ME, Janorkar AV. Drug‐Loaded Elastin‐Like Polypeptide–Collagen Hydrogels with High Modulus for Bone Tissue Engineering. Macromol Biosci 2019; 19:e1900142. [DOI: 10.1002/mabi.201900142] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 06/21/2019] [Indexed: 12/15/2022]
Affiliation(s)
- Pallabi Pal
- Biomedical Materials ScienceSchool of DentistryUniversity of Mississippi Medical Center 2500 North State Street Jackson MS 39216 USA
| | - Quynh C. Nguyen
- Biomedical Materials ScienceSchool of DentistryUniversity of Mississippi Medical Center 2500 North State Street Jackson MS 39216 USA
| | - Angela H. Benton
- Microbiology and ImmunologySchool of MedicineUniversity of Mississippi Medical Center 2500 North State Street Jackson MS 39216 USA
| | - Mary E. Marquart
- Microbiology and ImmunologySchool of MedicineUniversity of Mississippi Medical Center 2500 North State Street Jackson MS 39216 USA
| | - Amol V. Janorkar
- Biomedical Materials ScienceSchool of DentistryUniversity of Mississippi Medical Center 2500 North State Street Jackson MS 39216 USA
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Independent control of matrix adhesiveness and stiffness within a 3D self-assembling peptide hydrogel. Acta Biomater 2018; 70:110-119. [PMID: 29410241 DOI: 10.1016/j.actbio.2018.01.031] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 01/15/2018] [Accepted: 01/24/2018] [Indexed: 12/30/2022]
Abstract
A cell's insoluble microenvironment has increasingly been shown to exert influence on its function. In particular, matrix stiffness and adhesiveness strongly impact behaviors such as cell spreading and differentiation, but materials that allow for independent control of these parameters within a fibrous, stromal-like microenvironment are very limited. In the current work, we devise a self-assembling peptide (SAP) system that facilitates user-friendly control of matrix stiffness and RGD (Arg-Gly-Asp) concentration within a hydrogel possessing a microarchitecture similar to stromal extracellular matrix. In this system, the RGD-modified SAP sequence KFE-RGD and the scrambled sequence KFE-RDG can be directly swapped for one another to change RGD concentration at a given matrix stiffness and total peptide concentration. Stiffness is controlled by altering total peptide concentration, and the unmodified base peptide KFE-8 can be included to further increase this stiffness range due to its higher modulus. With this tunable system, we demonstrate that human mesenchymal stem cell morphology and differentiation are influenced by both gel stiffness and the presence of functional cell binding sites in 3D culture. Specifically, cells 24 hours after encapsulation were only able to spread out in stiffer matrices containing KFE-RGD. Upon addition of soluble adipogenic factors, soft gels facilitated the greatest adipogenesis as determined by the presence of lipid vacuoles and PPARγ-2 expression, while increasing KFE-RGD concentration at a given stiffness had a negative effect on adipogenesis. This three-component hydrogel system thus allows for systematic investigation of matrix stiffness and RGD concentration on cell behavior within a fibrous, three-dimensional matrix. STATEMENT OF SIGNIFICANCE Physical cues from a cell's surrounding environment-such as the density of cell binding sites and the stiffness of the surrounding material-are increasingly being recognized as key regulators of cell function. Currently, most synthetic biomaterials used to independently tune these parameters lack the fibrous structure characteristic of stromal extracellular matrix, which can be important to cells naturally residing within stromal tissues. In this manuscript, we describe a 3D hydrogel encapsulation system that provides user-friendly control over matrix stiffness and binding site concentration within the context of a stromal-like microarchitecture. Binding site concentration and gel stiffness both influenced cell spreading and differentiation, highlighting the utility of this system to study the independent effects of these material properties on cell function.
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Nakharuthai C, Areechon N, Srisapoome P. Molecular characterization, functional analysis, and defense mechanisms of two CC chemokines in Nile tilapia (Oreochromis niloticus) in response to severely pathogenic bacteria. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2016; 59:207-228. [PMID: 26853931 DOI: 10.1016/j.dci.2016.02.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Revised: 02/03/2016] [Accepted: 02/03/2016] [Indexed: 06/05/2023]
Abstract
Two full-length cDNAs encoding CC chemokine genes in Nile tilapia (Oreochromis niloticus) (On-CC1 and On-CC2) were cloned and characterized. On-CC1 and On-CC2 showed signature cysteine motifs consisting of four cysteines. The expression levels of On-CC1 and On-CC2 were analyzed by RT-PCR, which showed that low expression of these two genes was only observed in the peripheral blood leukocytes (PBLs) and spleen of normal fish. Expression levels of these two molecules were quantified in 13 tissues of fish infected with virulent strains of Streptococcus agalactiae and Flavobacterium columnare. Most tissues, especially PBLs, the spleen and the liver, expressed significantly higher mRNA levels than the controls, particularly at 12 and 24 h after infection (P < 0.05). The current study strongly indicates that CC chemokine genes in Nile tilapia are crucially involved in the early immune responses to pathogens. Functional analyses clearly demonstrated that 10 and 100 μg/ml of recombinant rOn-CC1 and rOn-CC2 proteins efficiently enhanced the phagocytic activity (in vitro) of Nile tilapia phagocytes. Finally, Southern blot analysis and searching in Ensembl databases demonstrated that two different functional CC chemokine genes and other pseudogene fragments were discovered in the Nile tilapia genome.
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Affiliation(s)
- Chatsirin Nakharuthai
- Laboratory of Aquatic Animal Health Management, Department of Aquaculture, Faculty of Fisheries, Kasetsart University, Thailand; Center of Advanced Studies for Agriculture and Food, Kasetsart University Institute for Advanced Studies, Kasetsart University, Bangkok 10900, Thailand
| | - Nontawith Areechon
- Laboratory of Aquatic Animal Health Management, Department of Aquaculture, Faculty of Fisheries, Kasetsart University, Thailand; Center of Advanced Studies for Agriculture and Food, Kasetsart University Institute for Advanced Studies, Kasetsart University, Bangkok 10900, Thailand
| | - Prapansak Srisapoome
- Laboratory of Aquatic Animal Health Management, Department of Aquaculture, Faculty of Fisheries, Kasetsart University, Thailand; Center of Advanced Studies for Agriculture and Food, Kasetsart University Institute for Advanced Studies, Kasetsart University, Bangkok 10900, Thailand.
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Exosome-associated release, uptake, and neurotoxicity of HIV-1 Tat protein. J Neurovirol 2016; 22:774-788. [PMID: 27173397 DOI: 10.1007/s13365-016-0451-6] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 04/18/2016] [Accepted: 05/02/2016] [Indexed: 12/17/2022]
Abstract
HIV-1 Tat is an indispensible transactivator for HIV gene transcription and replication. It has been shown to exit cells as a free protein and enter neighboring cells or interact with surface receptors of neighboring cells to regulate gene expression and cell function. In this study, we report, for the first time, exosome-associated Tat release and uptake. Using a HIV-1 LTR-driven luciferase reporter-based cell assay and Western blotting or in combination with exosome inhibitor, OptiPrep gradient fractionation, and exosome depletion, we demonstrated significant presence of HIV-1 Tat in exosomes derived from Tat-expressing primary astrocytes, Tat-transfected U373.MG and 293T, and HIV-infected MT4. We further showed that exosome-associated Tat from Tat-expressing astrocytes was capable of causing neurite shortening and neuron death, further supporting that this new form of extracellular Tat is biologically active. Lastly, we constructed a Tat mutant deleted of its basic domain and determined the role of the basic domain in Tat trafficking into exosomes. Basic domain-deleted Tat exhibited no apparent effects on Tat trafficking into exosomes, while maintained its dominant-negative function in Tat-mediated LTR transactivation. Taken together, these results show a significant fraction of Tat is secreted and present in the form of exosomes and may contribute to the stability of extracellular Tat and broaden the spectrum of its target cells.
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Roy CN, Khandaker I, Oshitani H. Intersubtype Genetic Variation of HIV-1 Tat Exon 1. AIDS Res Hum Retroviruses 2015; 31:641-8. [PMID: 25748226 DOI: 10.1089/aid.2014.0346] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
HIV-1 Tat is a regulatory protein that plays a pivotal role in viral transcription and replication. Our study aims to investigate the genetic variation of Tat exon 1 in all subtypes of HIV-1: A, B, C, D, F, G, H, J, and K. We performed phylogenetic, mutation, and selection pressure analyses on a total of 1,179 sequences of different subtypes of HIV-1 Tat obtained from the Los Alamos National Laboratory (LANL). The mean nucleotide divergences (%) among the analyzed sequences of subtypes A, B, C, D, F, G, H, J, and K were 88, 89, 90, 88, 86, 89, 88, 97, and 97, respectively. We revealed that subtype B evolved relatively faster than other subtypes. The second and fifth domains were found comparatively more variable among all subtypes. Site-by-site tests of positive selection revealed that several positions in all subtypes were under significant positive selection. Positively selected sites were found in the acidic domain at positions 3, 4, and 19, in the cysteine-rich domains at positions 24, 29, 32, and 36, in the core domain at position 40, and in the basic domain for the rest of the positions for all subtypes. Positions 58 and 68 in the basic domain were positively selected in subtypes A, B, C and B, C, F, respectively. We also observed high variability within positively selected sites in amino acid positions. Our study findings on HIV-1 Tat genetic variability may contribute to a better understanding of HIV-1 evolution as well as to the development of effective Tat-targeted therapeutics and vaccines.
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Affiliation(s)
- Chandra Nath Roy
- Department of Virology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Irona Khandaker
- Department of Virology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Hitoshi Oshitani
- Department of Virology, Tohoku University Graduate School of Medicine, Sendai, Japan
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Roy CN, Khandaker I, Furuse Y, Oshitani H. Molecular characterization of full-length Tat in HIV-1 subtypes B and C. Bioinformation 2015; 11:151-60. [PMID: 25914449 PMCID: PMC4403036 DOI: 10.6026/97320630011151] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 03/02/2015] [Indexed: 12/13/2022] Open
Abstract
HIV-1Tat (trans-acting activator of transcription) plays essential roles in the replication through viral mRNA and genome transcription from the HIV-1 LTR promoter. However, Tat undergoes continuous amino acid substitutions. As a consequence, the virus escapes from host immunity indicating that genetic diversity of Tat protein in major HIV-1 subtypes is required to be continuously monitored. We analyzed available full-length HIV-1 sequences of subtypes B (n=493) and C (n=280) strains circulating worldwide. We observed 81% and 84% nucleotide sequence identities of HIV-1 Tat for subtypes B and C, respectively. Based on phylogenetic and mutation analyses, global diversity of subtype B was apparently higher compared to that of subtype C. Positively selected sites, such as positions Ser68 and Ser70 in both subtypes, were located in the Tat-transactivation responsive RNA (TAR) interaction domain. We also found positively selected sites in exon 2, such as positions Ser75, Pro77, Asp80, Pro81 and Ser87 for both subtypes. Our study provides useful information on the full-length HIV-1 Tat sequences in globally circulating strains.
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Affiliation(s)
- Chandra Nath Roy
- Department of Virology, Tohoku University Graduate School of Medicine, 2-1 Seiryomachi, Aoba-ku, Sendai city, Miyagi, Japan-9808575
| | - Irona Khandaker
- Department of Virology, Tohoku University Graduate School of Medicine, 2-1 Seiryomachi, Aoba-ku, Sendai city, Miyagi, Japan-9808575
| | - Yuki Furuse
- Department of Virology, Tohoku University Graduate School of Medicine, 2-1 Seiryomachi, Aoba-ku, Sendai city, Miyagi, Japan-9808575
| | - Hitoshi Oshitani
- Department of Virology, Tohoku University Graduate School of Medicine, 2-1 Seiryomachi, Aoba-ku, Sendai city, Miyagi, Japan-9808575
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Bouwman RD, Palser A, Parry CM, Coulter E, Rasaiyaah J, Kellam P, Jenner RG. Human immunodeficiency virus Tat associates with a specific set of cellular RNAs. Retrovirology 2014; 11:53. [PMID: 24990269 PMCID: PMC4086691 DOI: 10.1186/1742-4690-11-53] [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] [Received: 12/04/2013] [Accepted: 06/18/2014] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Human Immunodeficiency Virus 1 (HIV-1) exhibits a wide range of interactions with the host cell but whether viral proteins interact with cellular RNA is not clear. A candidate interacting factor is the trans-activator of transcription (Tat) protein. Tat is required for expression of virus genes but activates transcription through an unusual mechanism; binding to an RNA stem-loop, the transactivation response element (TAR), with the host elongation factor P-TEFb. HIV-1 Tat has also been shown to alter the expression of host genes during infection, contributing to viral pathogenesis but, whether Tat also interacts with cellular RNAs is unknown. RESULTS Using RNA immunoprecipitation coupled with microarray analysis, we have discovered that HIV-1 Tat is associated with a specific set of human mRNAs in T cells. mRNAs bound by Tat share a stem-loop structural element and encode proteins with common biological roles. In contrast, we do not find evidence that Tat associates with microRNAs or the RNA-induced silencing complex (RISC). The interaction of Tat with cellular RNA requires an intact RNA binding domain and Tat RNA binding is linked to an increase in RNA abundance in cell lines and during infection of primary CD4+ T cells by HIV. CONCLUSIONS We conclude that Tat interacts with a specific set of human mRNAs in T cells, many of which show changes in abundance in response to Tat and HIV infection. This work uncovers a previously unrecognised interaction between HIV and its host that may contribute to viral alteration of the host cellular environment.
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Affiliation(s)
| | | | | | | | | | | | - Richard G Jenner
- MRC Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London, London WC1E 6BT, UK.
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Immunological role of C4 CC chemokine-1 from snakehead murrel Channa striatus. Mol Immunol 2013; 57:292-301. [PMID: 24231766 DOI: 10.1016/j.molimm.2013.10.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Revised: 10/09/2013] [Accepted: 10/15/2013] [Indexed: 11/22/2022]
Abstract
In this study, we have reported a cDNA sequence of C4 CC chemokine identified from snakehead murrel (also known as striped murrel) Channa striatus (named as CsCC-Chem-1) normalized cDNA library constructed by Genome Sequencing FLX™ Technology (GS-FLX™). CsCC-Chem-1 is 641 base pairs (bp) long that contain 438 bp open reading frame (ORF). The ORF encodes a polypeptide of 146 amino acids with a molecular mass of 15 kDa. The polypeptide contains a small cytokine domain at 30-88. The domain carries the CC motif at Cys(33)-Cys(34). In addition, CsCC-Chem-1 consists of another two cysteine residues at C(59) and C(73), which, together with C(33) and C(34), make CsCC-Chem-1 as a C4-CC chemokine. CsCC-Chem-1 also contains a 'TCCT' motif at 32-35 as CC signature motif; this new motif may represent new characteristic features, which may lead to some unknown function that needs to be further focused on. Phylogenitically, CsCC-Chem-1 clustered together with CC-Chem-1 from rock bream Oplegnathus fasciatus and European sea bass Dicentrarchus labrax. Significantly (P<0.05) highest gene expression was noticed in spleen and is up-regulated upon fungus (Aphanomyces invadans), bacteria (Aeromonas hydrophila) and virus (poly I:C) infection at various time points. The gene expression results indicate the influence of CsCC-Chem-1 in the immune system of murrel. Overall, the gene expression study showed that the CsCC-Chem-1 is a capable gene to increase the cellular response against various microbial infections. Further, we cloned the coding sequence of CsCC-Chem-1 in pMAL vector and purified the recombinant protein to study the functional properties. The cell proliferation activity of recombinant CsCC-Chem-1 protein showed a significant metabolic activity in a concentration dependent manner. Moreover, the chemotaxis assay showed the capability of recombinant CsCC-Chem-1 protein which can induce the migration of spleen leukocytes in C. striatus. However, this remains to be verified further at molecular and proteomic level.
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Planès R, Bahraoui E. HIV-1 Tat protein induces the production of IDO in human monocyte derived-dendritic cells through a direct mechanism: effect on T cells proliferation. PLoS One 2013; 8:e74551. [PMID: 24073214 PMCID: PMC3779232 DOI: 10.1371/journal.pone.0074551] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 08/02/2013] [Indexed: 12/21/2022] Open
Abstract
During HIV-1 infection, an increase of indoleamine 2,3 dioxygenase (IDO) expression, and dendritic cells (DC) dysfunction were often associated with AIDS disease progression. In this work, we investigated the effect of HIV-1 Tat protein on the expression of IDO, in MoDCs. We show that Tat induces IDO protein expression and activity in a dose dependent manner by acting at the cell membrane. Using Tat-mutants, we show that the N-Terminal domain, Tat 1–45, but not the central region, Tat 30–72, is sufficient to induce the expression of active IDO. Tat protein is also able to induce several cytokines in MoDCs, including IFN-γ, a strong inducer of IDO. In order to understand whether IDO is induced directly by Tat protein or indirectly following IFN-γ production, complementary experiments were performed and showed that: i) at the kinetic level, Tat induced IDO expression before the production of IFN-γ ii) treatment of MoDCs with Tat-conditioned medium was unable to stimulate IDO expression, iii) coculture of MoDCs in a transwell cell system did not allow IDO expression in MoDCs not previously treated by Tat, iv) direct contact between Tat-treated and untreated MoDCs was not sufficient to induce IDO expression in a Tat-independent manner, and v) treatment of MoDCs in the presence of IFN-γ pathway inhibitors, Jak I and Ly294002, inhibited IFN-γ-induced IDO but had no effect on Tat-induced IDO. At the functional level, our data showed that treatment of MoDCs with Tat led to the inhibition of their capacity to stimulate T cell proliferation. This impairement was totally abolished when the stimulation was performed in the presence of 1MT, an inhibitor of IDO activity, arguing for the implication of the kynurenine pathway. By inducing IDO, Tat protein may be considered, as a viral pathogenic factor, in the dysregulation of the DC functions during HIV-1 infection.
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Affiliation(s)
- Rémi Planès
- INSERM, U1043, Toulouse, France
- CNRS, U5282, Toulouse, France
- Université Paul Sabatier, EA 3038, Toulouse, France
| | - Elmostafa Bahraoui
- INSERM, U1043, Toulouse, France
- CNRS, U5282, Toulouse, France
- Université Paul Sabatier, EA 3038, Toulouse, France
- * E-mail:
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Zou S, Fitting S, Hahn YK, Welch SP, El-Hage N, Hauser KF, Knapp PE. Morphine potentiates neurodegenerative effects of HIV-1 Tat through actions at μ-opioid receptor-expressing glia. Brain 2011; 134:3616-31. [PMID: 22102648 DOI: 10.1093/brain/awr281] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Individuals infected with human immunodeficiency virus-1 who abuse opiates can have a higher incidence of virus-associated neuropathology. Human immunodeficiency virus does not infect neurons, but viral proteins such as transactivator of transcription and glycoprotein 120, originating from infected glia, are neurotoxic. Moreover, functional changes in glial cells that enhance inflammation and reduce trophic support are increasingly implicated in human immunodeficiency virus neuropathology. In previous studies, co-exposure with morphine enhanced transactivator of transcription neurotoxicity towards cultured striatal neurons. Since those cultures contained µ-opioid receptor-expressing astroglia and microglia, and since glia are the principal site of infection in the central nervous system, we hypothesized that morphine synergy might be glially mediated. A 60 hour, repeated measures paradigm and multiple co-culture models were used to investigate the cellular basis for opiate-enhanced human immunodeficiency virus neurotoxicity. Morphine co-exposure significantly enhanced transactivator of transcription-induced neuron death when glia were present. Synergistic effects of morphine on transactivator of transcription neurotoxicity were greatest with neuron-glia contact, but also occurred to a lesser extent with glial conditioned medium. Importantly, synergy was lost if glia, but not neurons, lacked µ-opioid receptors, indicating that opiate interactions with human immunodeficiency virus converge at the level of µ-opioid receptor-expressing glia. Morphine enhanced transactivator of transcription-induced inflammatory effectors released by glia, elevating reactive oxygen species, increasing 3-nitrotyrosine production by microglia, and reducing the ability of glia to buffer glutamate. But neuron survival was reduced even more with glial contact than with exposure to conditioned medium, suggesting that noxious elements associated with cell contact augment the toxicity due to soluble factors. Similar morphine-transactivator of transcription synergy was also observed in studies with the clade C sequence of HIV-1 transactivator of transcription, which did not cause neuron death unless morphine was present. Several paradoxical observations related to opiate effects were noted when µ-opioid receptors were specifically ablated from either glia or neurons. This suggests that µ-opioid receptor loss in isolated cell types can fundamentally distort cell-to-cell signalling, revealing opponent processes that may exist in individual cell types. Our findings show the critical role of glia in orchestrating neurotoxic interactions of morphine and transactivator of transcription, and support the emerging concept that combined exposure to opiates and human immunodeficiency virus drives enhanced pathology within the central nervous system.
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Affiliation(s)
- Shiping Zou
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, VA 23298, USA
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Suzuki M, El-Hage N, Zou S, Hahn YK, Sorrell ME, Sturgill JL, Conrad DH, Knapp PE, Hauser KF. Fractalkine/CX3CL1 protects striatal neurons from synergistic morphine and HIV-1 Tat-induced dendritic losses and death. Mol Neurodegener 2011; 6:78. [PMID: 22093090 PMCID: PMC3287119 DOI: 10.1186/1750-1326-6-78] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Accepted: 11/17/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Fractalkine/CX3CL1 and its cognate receptor CX3CR1 are abundantly expressed in the CNS. Fractalkine is an unusual C-X3-C motif chemokine that is important in neuron-microglial communication, a co-receptor for HIV infection, and can be neuroprotective. To assess the effects of fractalkine on opiate-HIV interactive neurotoxicity, wild-type murine striatal neurons were co-cultured with mixed glia from the striata of wild-type or Cx3cr1 knockout mice ± HIV-1 Tat and/or morphine. Time-lapse digital images were continuously recorded at 20 min intervals for up to 72 h using computer-aided microscopy to track the same cells repeatedly. RESULTS Co-exposure to Tat and morphine caused synergistic increases in neuron death, dendritic pruning, and microglial motility as previously reported. Exogenous fractalkine prevented synergistic Tat and morphine-induced dendritic losses and neuron death even though the inflammatory mediator TNF-α remained significantly elevated. Antibody blockade of CX3CR1 mimicked the toxic effects of morphine plus Tat, but did not add to their toxicity; while fractalkine failed to protect wild-type neurons co-cultured with Cx3cr1-/--null glia against morphine and Tat toxicity. Exogenous fractalkine also normalized microglial motility, which is elevated by Tat and morphine co-exposure, presumably limiting microglial surveillance that may lead to toxic effects on neurons. Fractalkine immunofluorescence was expressed in neurons and to a lesser extent by other cell types, whereas CX3CR1 immunoreactivity or GFP fluorescence in cells cultured from the striatum of Cx3cr1-/- (Cx3cr1GFP/GFP) mice were associated with microglia. Immunoblotting shows that fractalkine levels were unchanged following Tat and/or morphine exposure and there was no increase in released fractalkine as determined by ELISA. By contrast, CX3CR1 protein levels were markedly downregulated. CONCLUSIONS The results suggest that deficits in fractalkine-CX3CR1 signaling contribute to the synergistic neurotoxic effects of opioids and Tat. Importantly, exogenous fractalkine can selectively protect neurons from the injurious effects of chronic opioid-HIV-1 Tat co-exposure, and this suggests a potential therapeutic course for neuroAIDS. Although the cellular mechanisms underlying neuroprotection are not certain, findings that exogenous fractalkine reduces microglial motility and fails to protect neurons co-cultured with Cx3cr1-/- mixed glia suggest that fractalkine may act by interfering with toxic microglial-neuron interactions.
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Affiliation(s)
- Masami Suzuki
- Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, Richmond, VA 23298-0613, USA
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16
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Johri MK, Mishra R, Chhatbar C, Unni SK, Singh SK. Tits and bits of HIV Tat protein. Expert Opin Biol Ther 2011; 11:269-83. [PMID: 21204735 DOI: 10.1517/14712598.2011.546339] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
INTRODUCTION HIV-Tat protein displays an array of functions that are essential for HIV replication. The structural flexibility of Tat protein has been regarded as one of the unique features responsible for sustaining diverse functions, from facilitated membrane-crossing ability to strong affinity for RNA binding. AREAS COVERED RNA binding ability and presence of multiple interacting domains in the same protein are very important properties of HIV-Tat protein. Tat protein has shown great ability to influence cellular and viral gene expression. We discuss the functions of HIV Tat protein, describing its structural significance, secretion and uptake of HIV Tat protein by immune cells, post-translational modifications and role of HIV Tat protein in HIV pathogenesis. EXPERT OPINION Perturbation in expression of many cytokines and chemokines by HIV-Tat protein exhibits downstream immune suppressive function as well as activation of several apoptotic genes. This explains the massive death of immune cells due to bystander effect of HIV Tat protein among HIV-infected patients.
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Affiliation(s)
- Manish K Johri
- Laboratory of Neurovirology & Inflammation Biology, Section of Infectious Diseases, Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad-500007, (A.P), India
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17
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Zhu RL, Lei XY, Ke F, Yuan XP, Zhang QY. Genome of turbot rhabdovirus exhibits unusual non-coding regions and an additional ORF that could be expressed in fish cell. Virus Res 2010; 155:495-505. [PMID: 21185339 DOI: 10.1016/j.virusres.2010.12.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Revised: 12/05/2010] [Accepted: 12/09/2010] [Indexed: 10/18/2022]
Abstract
Genomic sequence of Scophthalmus maximus rhabdovirus (SMRV) isolated from diseased turbot has been characterized. The complete genome of SMRV comprises 11,492 nucleotides and encodes five typical rhabdovirus genes N, P, M, G and L. In addition, two open reading frames (ORF) are predicted overlapping with P gene, one upstream of P and smaller than P (temporarily called Ps), and another in P gene which may encodes a protein similar to the vesicular stomatitis virus C protein. The C ORF is contained within the P ORF. The five typical proteins share the highest sequence identities (48.9%) with the corresponding proteins of rhabdoviruses in genus Vesiculovirus. Phylogenetic analysis of partial L protein sequence indicates that SMRV is close to genus Vesiculovirus. The first 13 nucleotides at the ends of the SMRV genome are absolutely inverse complementarity. The gene junctions between the five genes show conserved polyadenylation signal (CATGA(7)) and intergenic dinucleotide (CT) followed by putative transcription initiation sequence A(A/G)(C/G)A(A/G/T), which are different from known rhabdoviruses. The entire Ps ORF was cloned and expressed, and used to generate polyclonal antibody in mice. One obvious band could be detected in SMRV-infected carp leucocyte cells (CLCs) by anti-Ps/C serum via Western blot, and the subcellular localization of Ps-GFP fusion protein exhibited cytoplasm distribution as multiple punctuate or doughnut shaped foci of uneven size.
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Affiliation(s)
- Ruo-Lin Zhu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Wuhan 430072, China
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18
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Kiebala M, Polesskaya O, Yao Z, Perry SW, Maggirwar SB. Nuclear factor-kappa B family member RelB inhibits human immunodeficiency virus-1 Tat-induced tumor necrosis factor-alpha production. PLoS One 2010; 5:e11875. [PMID: 20686703 PMCID: PMC2912378 DOI: 10.1371/journal.pone.0011875] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Accepted: 07/06/2010] [Indexed: 12/02/2022] Open
Abstract
Human Immunodeficiency Virus-1 (HIV-1)-associated neurocognitive disorder (HAND) is likely neuroinflammatory in origin, believed to be triggered by inflammatory and oxidative stress responses to cytokines and HIV protein gene products such as the HIV transactivator of transcription (Tat). Here we demonstrate increased messenger RNA for nuclear factor-kappa B (NF-κB) family member, transcription factor RelB, in the brain of doxycycline-induced Tat transgenic mice, and increased RelB synthesis in Tat-exposed microglial cells. Since genetic ablation of RelB in mice leads to multi-organ inflammation, we hypothesized that Tat-induced, newly synthesized RelB inhibits cytokine production by microglial cells, possibly through the formation of transcriptionally inactive RelB/RelA complexes. Indeed, tumor necrosis factor-alpha (TNFα) production in monocytes isolated from RelB deficient mice was significantly higher than in monocytes isolated from RelB expressing controls. Moreover, RelB overexpression in microglial cells inhibited Tat-induced TNFα synthesis in a manner that involved transcriptional repression of the TNFα promoter, and increased phosphorylation of RelA at serine 276, a prerequisite for increased RelB/RelA protein interactions. The Rel-homology-domain within RelB was necessary for this interaction. Overexpression of RelA itself, in turn, significantly increased TNFα promoter activity, an effect that was completely blocked by RelB overexpression. We conclude that RelB regulates TNFα cytokine synthesis by competitive interference binding with RelA, which leads to downregulation of TNFα production. Moreover, because Tat activates both RelB and TNFα in microglia, and because Tat induces inflammatory TNFα synthesis via NF-κB, we posit that RelB serves as a cryoprotective, anti-inflammatory, counter-regulatory mechanism for pathogenic NF-κB activation. These findings identify a novel regulatory pathway for controlling HIV-induced microglial activation and cytokine production that may have important therapeutic implications for the management of HAND.
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Affiliation(s)
- Michelle Kiebala
- Department of Microbiology and Immunology, the University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Oksana Polesskaya
- Department of Microbiology and Immunology, the University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Zhenqiang Yao
- Department of Pathology and Laboratory Medicine, the University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Seth W. Perry
- Center for Neural Development and Disease, Department of Neurology, the University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Sanjay B. Maggirwar
- Department of Microbiology and Immunology, the University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
- * E-mail:
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Shi CY, Jia KT, Yang B, Huang J. Complete genome sequence of a Megalocytivirus (family Iridoviridae) associated with turbot mortality in China. Virol J 2010; 7:159. [PMID: 20630106 PMCID: PMC2912838 DOI: 10.1186/1743-422x-7-159] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2010] [Accepted: 07/15/2010] [Indexed: 11/18/2022] Open
Abstract
Background Turbot reddish body iridovirus (TRBIV) causes serious systemic diseases with high mortality in the cultured turbot, Scophthalmus maximus. We here sequenced and analyzed the complete genome of TRBIV, which was identified in Shandong province, China. Results The genome of TRBIV is a linear double-stranded DNA of 110,104 base pairs, comprising 55% G + C. Total 115 open reading frames were identified, encoding polypeptides ranging from 40 to 1168 amino acids. Amino acid sequences analysis revealed that 39 of the 115 potential gene products of TRBIV show significant homology to other iridovirus proteins. Phylogenetic analysis of conserved genes indicated that TRBIV is closely related to infectious spleen and kidney necrosis virus (ISKNV), rock bream iridovirus (RBIV), orange-spotted grouper iridovirus (OSGIV), and large yellow croaker iridovirus (LYCIV). The results indicated that TRBIV belongs to the genus Megalocytivirus (family Iridoviridae). Conclusions The determination of the genome of TRBIV will provide useful information for comparative study of Megalocytivirus and developing strategies to control outbreaks of TRBIV-induced disease.
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Affiliation(s)
- Cheng-Yin Shi
- Key Laboratory for Sustainable Utilization of Marine Fisheries Resource, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Qingdao 266071, China
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20
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Sengupta A, Carlson BA, Labunskyy VM, Gladyshev VN, Hatfield DL. Selenoprotein T deficiency alters cell adhesion and elevates selenoprotein W expression in murine fibroblast cells. Biochem Cell Biol 2010; 87:953-61. [PMID: 19935881 DOI: 10.1139/o09-064] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mammalian selenoproteins have diverse functions, cellular locations, and evolutionary histories, but all use the amino acid selenocysteine (Sec), often present in the enzyme's active site. Only about half of mammalian selenoproteins have been functionally characterized, with most being oxidoreductases. The cellular role of selenoprotein T (SelT), manifesting a CxxU motif in a thioredoxin-like fold and localized to Golgi and the endoplasmic reticulum, is not known. To examine its biological function, we knocked down SelT expression in mouse fibroblast cells and found that SelT deficiency alters cell adhesion and enhances the expression of several oxidoreductase genes, while decreasing the expression of genes involved in cell structure organization, suggesting the involvement of SelT in redox regulation and cell anchorage. Furthermore, we found that the loss of SelT elevates expression of another selenoprotein, selenoprotein W (SepW1). SelT and SepW1 belong to the same protein family, suggesting that SepW1 may functionally compensate for SelT.
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Affiliation(s)
- Aniruddha Sengupta
- Molecular Biology of Selenium Section, Laboratory of Cancer Prevention, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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21
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Wan QJ, Gong J, Huang XH, Huang YH, Zhou S, Ou-Yang ZL, Cao JH, Ye LL, Qin QW. Identification and characterization of a novel capsid protein encoded by Singapore grouper iridovirus ORF038L. Arch Virol 2010; 155:351-9. [PMID: 20130938 DOI: 10.1007/s00705-010-0594-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2009] [Accepted: 12/16/2009] [Indexed: 11/26/2022]
Abstract
Singapore grouper iridovirus (SGIV) is an important pathogen isolated from grouper, Epinephelus tauvina, and characterized as a novel ranavirus. To better understand the function of viral structural genes involved in SGIV infection and virus-host interactions, a candidate gene, VP38 (ORF038L), was investigated in this study. SGIV VP38 was found to encode a 170-aa peptide containing an RGD motif, and it showed significant identity only to members of the genus Iridovirus, family Iridoviridae, except megalocytivirus. The VP38 gene was identified by temporal expression pattern analysis and drug inhibition assay as a late (L) gene. Immunofluorescence localization revealed that P38 was distributed predominately in the cytoplasm and that association of VP38 with viral factories increased at the late stage of SGIV infection. Consistent results from immunoelectron microscopy (IEM) and western blot analysis revealed that SGIV VP38 is a viral capsid protein. Furthermore, antibodies specific for SGIV VP38 exhibited substantial SGIV-neutralizing activity in vitro, suggesting that VP38 might play an important role in SGIV infectivity.
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Affiliation(s)
- Qing Jiao Wan
- State Key Laboratory of Biocontrol, School of Life Science, Sun Yat-sen University, 135 West Xingang Road, Guangzhou, China
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22
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Barrett JW, Werden SJ, Wang F, McKillop WM, Jimenez J, Villeneuve D, McFadden G, Dekaban GA. Myxoma virus M130R is a novel virulence factor required for lethal myxomatosis in rabbits. Virus Res 2009; 144:258-65. [PMID: 19477207 DOI: 10.1016/j.virusres.2009.05.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2009] [Revised: 05/14/2009] [Accepted: 05/14/2009] [Indexed: 11/18/2022]
Abstract
Myxoma virus (MV) is a highly lethal, rabbit-specific poxvirus that induces a disease called myxomatosis in European rabbits. In an effort to understand the function of predicted immunomodulatory genes we have deleted various viral genes from MV and tested the ability of these knockout viruses to induce lethal myxomatosis. MV encodes a unique 15 kD cytoplasmic protein (M130R) that is expressed late (12h post infection) during infection. M130R is a non-essential gene for MV replication in rabbit, monkey or human cell lines. Construction of a targeted gene knockout virus (vMyx130KO) and infection of susceptible rabbits demonstrate that the M130R knockout virus is attenuated and that loss of M130R expression allows the rabbit host immune system to effectively respond to and control the lethal effects of MV. M130R expression is a bona fide poxviral virulence factor necessary for full and lethal development of myxomatosis.
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Affiliation(s)
- John W Barrett
- Biotherapeutics Research Group, Robarts Research Institute and Department of Microbiology and Immunology, University of Western Ontario, London, Ontario N6A 5K8, Canada
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23
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Massodi I, Bidwell GL, Davis A, Tausend A, Credit K, Flessner M, Raucher D. Inhibition of ovarian cancer cell metastasis by a fusion polypeptide Tat-ELP. Clin Exp Metastasis 2009; 26:251-60. [PMID: 19169893 DOI: 10.1007/s10585-009-9237-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2008] [Accepted: 01/12/2009] [Indexed: 10/21/2022]
Abstract
Tumor cell metastasis is a complex, multi-step process that is a major cause of death and morbidity amongst cancer patients. Cell adhesion plays a critical role in the development of metastatic cancer, and it is mediated by interactions between receptors on the cell surface and ligands of the extracellular matrix or other surfaces. Therefore, inhibition of the cell adhesion process appears to be an effective method of preventing metastasis. This work describes a genetically engineered polypeptide with the potential to prevent cell adhesion and inhibit metastasis. We have found that the cell penetrating peptide Tat, fused with elastin-like polypeptide (ELP) inhibited adhesion, spreading, invasion and migration of SKOV-3 ovarian cancer cells in cell culture. Furthermore, we have also confirmed that Tat-ELP has anti-metastatic potential in an experimental ovarian cancer metastasis model in vivo, causing approximately 80% reduction in the tumor burden. Since cell attachment is an important step in tumor cell invasion and metastasis, these results suggest a novel role of Tat-ELP as a therapeutic intervention in cancer metastasis.
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Affiliation(s)
- Iqbal Massodi
- Department of Biochemistry, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216, USA
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24
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Allard SD, Pletinckx K, Breckpot K, Heirman C, Bonehill A, Michiels A, van Baalen CA, Gruters RA, Osterhaus ADME, Lacor P, Thielemans K, Aerts JL. Functional T-cell responses generated by dendritic cells expressing the early HIV-1 proteins Tat, Rev and Nef. Vaccine 2008; 26:3735-41. [PMID: 18539368 DOI: 10.1016/j.vaccine.2008.04.077] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2007] [Revised: 04/16/2008] [Accepted: 04/17/2008] [Indexed: 11/24/2022]
Abstract
The limitations of highly active anti-retroviral therapy (HAART) have necessitated the development of alternative therapeutic strategies. One of the approaches that has gained prominence in recent years is therapeutic vaccination. We decided to assess the capacity of mature dendritic cells, derived from blood monocytes of HIV-1 infected patients, to generate functional T-cell responses. For this purpose, we constructed a chimeric mRNA encoding the proteins Tat, Rev and Nef. The TaReNef encoding information was linked to the HLA class II-targeting sequence of DC-LAMP. Broadly directed HIV-specific CD4(+) and CD8(+) cytotoxic T cells exhibiting a poly-functional cytokine secretion pattern were generated by co-culturing with autologous chimeric mRNA electroporated dendritic cells. Thus, administration of ex vivo generated dendritic cells expressing the early proteins Tat, Rev and Nef might offer a promising approach for therapeutic vaccination in HIV-1 infection.
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Affiliation(s)
- Sabine D Allard
- The Laboratory of Molecular and Cellular Therapy, Department of Physiology and Immunology, Medical School of the Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium.
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25
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Zakutskiĭ AN, Chalisova NI, Subbotina TF. [Functional arginine-containing amino acid sequences in peptides and proteins]. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2008; 34:149-59. [PMID: 18522270 DOI: 10.1134/s1068162008020015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
L-arginine is a source of nitrogen oxide and plays a great role in a number of other biochemical processes. Functions and prospects for practical application of five groups of arginine-containing amino acid sequences and synthetic polyarginine sequences are considered. The physiological characteristics of well-known arginine-containing peptides, such as RGD peptides, kyotorphin, and tuftsin, are described in detail. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2008, vol. 34, no. 2; see also http://www.maik.ru
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26
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Clade-specific differences in neurotoxicity of human immunodeficiency virus-1 B and C Tat of human neurons: significance of dicysteine C30C31 motif. Ann Neurol 2008; 63:366-76. [DOI: 10.1002/ana.21292] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Agrawal L, Louboutin JP, Strayer DS. Preventing HIV-1 tat-induced neuronal apoptosis using antioxidant enzymes: Mechanistic and therapeutic implications. Virology 2007; 363:462-72. [PMID: 17336361 DOI: 10.1016/j.virol.2007.02.004] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2007] [Accepted: 02/01/2007] [Indexed: 12/20/2022]
Abstract
HIV-1 proteins, especially gp120 and Tat, elicit reactive oxygen species (ROS) and cause neuron apoptosis. We used antioxidant enzymes, Cu/Zn superoxide dismutase (SOD1) and glutathione peroxidase (GPx1) to study signaling and neuroprotection from Tat-induced apoptosis. SOD1 converts superoxide to peroxide; GPx1 converts peroxide to water. Primary human neurons were transduced with SV40-derived vectors carrying SOD1 and GPx1, then HIV-1 Tat protein was added. Both SV(SOD1) and SV(GPx1) delivered substantial transgene expression. Tat decreased endogenous cellular, but not transduced, SOD1 and GPx1. Tat rapidly increased neuron [Ca(2+)](i), which effect was not altered by SV(SOD1) or SV(GPx1). However, both vectors together blocked Tat-induced [Ca(2+)](i) fluxes. Similarly, neither SV(SOD1) nor SV(GPx1) protected neurons from Tat-induced apoptosis, but both vectors together did. Tat therefore activates multiple signaling pathways, in one of which superoxide acts as an intermediate while the other utilizes peroxide. Gene delivery to protect neurons from Tat must therefore target both.
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Affiliation(s)
- Lokesh Agrawal
- Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Room 251, 1020 Locust Street, Philadelphia, PA 19107, USA
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28
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Sui Z, Sniderhan LF, Schifitto G, Phipps RP, Gelbard HA, Dewhurst S, Maggirwar SB. Functional Synergy between CD40 Ligand and HIV-1 Tat Contributes to Inflammation: Implications in HIV Type 1 Dementia. THE JOURNAL OF IMMUNOLOGY 2007; 178:3226-36. [PMID: 17312171 DOI: 10.4049/jimmunol.178.5.3226] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
HIV type 1 (HIV-1)-associated dementia (HAD) is believed to occur due to aberrant activation of monocyte-derived macrophages and brain-resident microglial cells by viral proteins as well as by the proinflammatory mediators released by infected cells. To investigate the inflammatory aspects of the disease, we examined the levels of soluble CD40L (sCD40L) in paired samples of plasma and cerebrospinal fluid obtained from 25 HIV-infected individuals. A significantly higher level of sCD40L was detected in both cerebrospinal fluid and plasma from HIV-infected patients with cognitive impairment, compared with their nonimpaired counterparts. The contribution of sCD40L to the pathogenesis of HAD was then examined by in vitro experiments. rCD40L synergized with HIV-1 Tat to increase TNF-alpha release from primary human monocytes and microglia, in an NF-kappaB-dependent manner. The mechanistic basis for this synergism was attributed to a Tat-mediated up-regulation of CD40 in monocytes and microglia. Finally, the CD40L-mediated increase in TNF-alpha production by monocytes was shown to be biologically important; immunodepletion experiments revealed that TNF-alpha was essential for the neurotoxic effects of conditioned medium recovered from Tat/CD40L-treated monocytes. Taken together, our results show that CD40 signaling in microglia and monocytes can synergize with the effects of Tat, further amplifying inflammatory processes within the CNS and influencing neuronal survival.
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Affiliation(s)
- Ziye Sui
- Interdepartmental Program in Neuroscience, University of Rochester School of Medicine, 601 Elmwood Avenue, Rochester, NY 14642, USA
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29
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Neri E, Musante V, Pittaluga A. Effects of the HIV-1 viral protein TAT on central neurotransmission: role of group I metabotropic glutamate receptors. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2007; 82:339-56. [PMID: 17678970 DOI: 10.1016/s0074-7742(07)82018-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Human immunodeficiency virus 1 (HIV-1)-associated dementia (HAD) represents a common complication of HIV-1 infection. Antiretroviral therapy has diminished its incidence, but it is insufficient to eradicate the problem. HAD depends on the presence of the virus in central nervous system (CNS), but the molecular mechanisms involved are not completely understood. It is widely accepted that proteins shed by the virus, such as the envelope glycoprotein gp120 and the nonstructural viral protein Tat, may themselves cause alterations to CNS. By one side, viral proteins are toxic to neurons because of their ability (1) to act as excitotoxins and (2) to evoke the release of endogenous neurotoxins and/or proinflammatory cytokines. By the other side, evidences are emerging that viral components can alter neuronal functions either by modifying the release of neurotransmitters or by influencing the functions of classical receptors controlling central neurotransmission. We here review some results concerning the effects of Tat on cholinergic and noradrenergic neurotransmission in human and rat cortex. The protein can induce the release of acetylcholine from both human and rat cortical cholinergic nerve terminals in a specie-specific manner. In human cholinergic terminals, Tat-mediated releasing effect depends on activation of receptors belonging to I group of metabotropic glutamate receptors (mGluRs), while in rat terminals Tat-induced effect involves the activation of a so far unknown receptor. The protein, unable on its own to release noradrenaline from human and rat cortical noradrenergic nerve endings, potentiates the release of amine induced by presynaptic NMDA receptors. Also in this case, Tat effect involves activation of a receptor belonging to the group I mGluRs, in particular of the mGluR1 subtype. The finding that group I mGluRs may represent a preferential target of the protein in CNS may be relevant to the proposal of new therapeutic approaches for the cure of HAD.
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Affiliation(s)
- Elisa Neri
- Department of Experimental Medicine, Pharmacology and Toxicology Section, University of Genova, Genova, Italy
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Siddappa NB, Venkatramanan M, Venkatesh P, Janki MV, Jayasuryan N, Desai A, Ravi V, Ranga U. Transactivation and signaling functions of Tat are not correlated: biological and immunological characterization of HIV-1 subtype-C Tat protein. Retrovirology 2006; 3:53. [PMID: 16916472 PMCID: PMC1564039 DOI: 10.1186/1742-4690-3-53] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2006] [Accepted: 08/18/2006] [Indexed: 12/04/2022] Open
Abstract
Background Of the diverse subtypes of Human Immunodeficiency Virus Type-1 (HIV-1), subtype-C strains cause a large majority of infections worldwide. The reasons for the global dominance of HIV-1 subtype-C infections are not completely understood. Tat, being critical for viral infectivity and pathogenesis, may differentially modulate pathogenic properties of the viral subtypes. Biochemical studies on Tat are hampered by the limitations of the current purification protocols. Tat purified using standard protocols often is competent for transactivation activity but defective for a variety of other biological functions. Keeping this limitation in view, we developed an efficient protein purification strategy for Tat. Results Tat proteins obtained using the novel strategy described here were free of contaminants and retained biological functions as evaluated in a range of assays including the induction of cytokines, upregulation of chemokine coreceptor, transactivation of the viral promoter and rescue of a Tat-defective virus. Given the highly unstable nature of Tat, we evaluated the effect of the storage conditions on the biological function of Tat following purification. Tat stored in a lyophilized form retained complete biological activity regardless of the storage temperature. To understand if variations in the primary structure of Tat could influence the secondary structure of the protein and consequently its biological functions, we determined the CD spectra of subtype-C and -B Tat proteins. We demonstrate that subtype-C Tat may have a relatively higher ordered structure and be less flexible than subtype-B Tat. We show that subtype-C Tat as a protein, but not as a DNA expression vector, was consistently inferior to subtype-B Tat in a variety of biological assays. Furthermore, using ELISA, we evaluated the anti-Tat antibody titers in a large number of primary clinical samples (n = 200) collected from all four southern Indian states. Our analysis of the Indian populations demonstrated that Tat is non-immunodominant and that a large variation exists in the antigen-specific antibody titers. Conclusion Our report not only describes a simple protein purification strategy for Tat but also demonstrates important structural and functional differences between subtype-B and -C Tat proteins. Furthermore, this is the first report of protein purification and characterization of subtype-C Tat.
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Affiliation(s)
- Nagadenahalli Byrareddy Siddappa
- Molecular Virology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
- Department of Neurovirology, National Institute of Mental Health and Neurosciences, Bangalore, India
| | - Mohanram Venkatramanan
- Molecular Virology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
| | - Prasanna Venkatesh
- Molecular Virology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
| | | | | | - Anita Desai
- Department of Neurovirology, National Institute of Mental Health and Neurosciences, Bangalore, India
| | - Vasanthapuram Ravi
- Department of Neurovirology, National Institute of Mental Health and Neurosciences, Bangalore, India
| | - Udaykumar Ranga
- Molecular Virology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
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Ao J, Chen X. Identification and characterization of a novel gene encoding an RGD-containing protein in large yellow croaker iridovirus. Virology 2006; 355:213-22. [PMID: 16916530 DOI: 10.1016/j.virol.2006.07.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2006] [Revised: 06/29/2006] [Accepted: 07/06/2006] [Indexed: 11/22/2022]
Abstract
Many virus-encoded RGD-containing proteins have been reported to play important roles in virus attachment and entry. Here we report the identification and functional characterization of a gene encoding an RGD-containing protein (037L) from large yellow croaker iridovirus (LYCIV), a causative agent of epizootics among large yellow croaker, Pseudosciaena crocea. The 037L gene is 1347 bp long and encodes a protein of 449 amino acids containing a biologically active RGD tri-peptide predicted with SURFC and STRIDE software. Temporal analysis of 037L gene transcription showed that this gene was a late gene. Subcellular localization of 037L in insect Hi5 cells using baculovirus vector system indicated that 037L might be a membrane-tropistic protein and functionally associated with the cytoplasma-membrane. The recombinant 037L expressed in E. coli could effectively induce the morphological changes of BF-2 cells and promote cellular aggregation, demonstrating that it can bind with surface molecules of BF-2 cells. The neutralization assay showed that LYCIV infection of BF-2 cells was significantly inhibited by anti-037L IgG, as determined by a real-time PCR of viral concentrations in the culture supernatants of LYCIV-infected cells, suggesting that it might have an important role in virus infectivity. This is the first report of the functional gene involved in virus infection and virus-host interaction in Megalocytivirus.
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Affiliation(s)
- Jingqun Ao
- Key Laboratory of Marine Biogenetic Resources, Third Institute of Oceanography, State Oceanic Administration, 178 Daxue Road, Xiamen 361005, PR China
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Li L, Lin S, Yang F. Characterization of an envelope protein (VP110) of White spot syndrome virus. J Gen Virol 2006; 87:1909-1915. [PMID: 16760393 DOI: 10.1099/vir.0.81730-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A protein of 110 kDa (termed VP110) from the envelope fraction of White spot syndrome virus (WSSV) was identified by SDS-PAGE and mass spectrometry. The resulting amino acid sequence matched an open reading frame (wsv035) containing an Arg–Gly–Asp (RGD) motif in the WSSV genome database. To validate the mass-spectrometry result, the C-terminal segment of the wsv035 open reading frame was expressed in Escherichia coli as a fusion protein, which was used to produce specific antibody. Analysis by Western blotting and immunoelectron microscopy demonstrated that VP110 was an envelope protein of WSSV. An interaction analysis was performed between VP110 and the host cells, using a fluorescence assay and a competitive-inhibition assay. The results showed that VP110 was capable of attaching to host cells and that adhesion could be inhibited by synthetic RGDT peptides, suggesting that the RGD motif in the VP110 sequence may play a role in WSSV infection.
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Affiliation(s)
- Li Li
- Key Laboratory of Marine Biogenetic Resources, Third Institute of Oceanography, 178 Daxue Road, Xiamen 361005, People's Republic of China
| | - Shumei Lin
- Key Laboratory of Marine Biogenetic Resources, Third Institute of Oceanography, 178 Daxue Road, Xiamen 361005, People's Republic of China
| | - Feng Yang
- Key Laboratory of Marine Biogenetic Resources, Third Institute of Oceanography, 178 Daxue Road, Xiamen 361005, People's Republic of China
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Turk G, Carobene M, Monczor A, Rubio AE, Gómez-Carrillo M, Salomón H. Higher transactivation activity associated with LTR and Tat elements from HIV-1 BF intersubtype recombinant variants. Retrovirology 2006; 3:14. [PMID: 16483381 PMCID: PMC1402313 DOI: 10.1186/1742-4690-3-14] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2005] [Accepted: 02/16/2006] [Indexed: 01/02/2023] Open
Abstract
Background HIV-1 is characterized by its rapid genetic evolution and high diversity as a consequence of its error-prone reverse transcriptase and genetic recombination. This latter mechanism is responsible for the creation of circulating recombinant forms (CRFs) found in nature. Previous studies from our lab group have shown that the epidemic in Argentina is characterized by one highly prevalent circulating recombinant form, CRF12_BF, and many related BF recombinant forms. Since transcriptional transactivation of the HIV-1 long terminal repeat (LTR) promoter element requires the essential viral Tat protein, since these genetic structures underwent recombination in variants widely spread in South America, the aim of this work was to study transcriptional activity associated with the recombinant LTR and Tat elements. Results Differential transcriptional activity was measured for the BF recombinant LTR/Tat complex that is present in widely spread viral variants was demonstrated. This analysis demonstrated a higher activity for the BF complex when compared to its B subtype counterpart. Conclusion This study indicates structural and functional consequences of recombination events within the LTR promoter and Tat transactivator protein of a naturally occurring HIV-1 recombinant form.
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Affiliation(s)
- Gabriela Turk
- National Reference Center for AIDS, Department of Microbiology, School of Medicine, University of Buenos Aires, Buenos Aires, Argentina
| | - Mauricio Carobene
- National Reference Center for AIDS, Department of Microbiology, School of Medicine, University of Buenos Aires, Buenos Aires, Argentina
| | - Ana Monczor
- National Reference Center for AIDS, Department of Microbiology, School of Medicine, University of Buenos Aires, Buenos Aires, Argentina
| | - Andrea Elena Rubio
- National Reference Center for AIDS, Department of Microbiology, School of Medicine, University of Buenos Aires, Buenos Aires, Argentina
| | - Manuel Gómez-Carrillo
- National Reference Center for AIDS, Department of Microbiology, School of Medicine, University of Buenos Aires, Buenos Aires, Argentina
| | - Horacio Salomón
- National Reference Center for AIDS, Department of Microbiology, School of Medicine, University of Buenos Aires, Buenos Aires, Argentina
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Kittiworakarn J, Lecoq A, Moine G, Thai R, Lajeunesse E, Drevet P, Vidaud C, Ménez A, Léonetti M. HIV-1 Tat Raises an Adjuvant-free Humoral Immune Response Controlled by Its Core Region and Its Ability to Form Cysteine-mediated Oligomers. J Biol Chem 2006; 281:3105-15. [PMID: 16321975 DOI: 10.1074/jbc.m509899200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Proteins are poor immunogens that require an adjuvant to raise an immune response. Here we show that the human immunodeficiency virus, type 1 Tat protein possesses an autoadjuvant property, and we have identified the determinants and the molecular events that are associated with this unusual property. Using a series of chemically synthesized Tat101 derivatives, we show that the core region controls the autoadjuvant phenomenon independently of the B-cell recognition and T-cell stimulation that are associated with epitopes respectively located on the N-terminal region and the cysteine-rich region. We also show that cysteine-mediated oligomerization is a key molecular event of the adjuvant-free antibody response. In particular, a Tat dimer formed by the oxidation of two cysteine residues, at position 34 only, raises an adjuvant-free antibody response that is comparable with that observed with the wild-type protein. Unlike the parent protein, the Tat dimer has no transactivating activity and remains homogeneous for several weeks in solution. This construct might be of value for the design of an adjuvant-free Tat-based vaccine. Furthermore, we suggest that the specific autoadjuvanticity determinant of Tat could be used to provide other proteins with adjuvant-free immunogenicity.
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Affiliation(s)
- Jongrak Kittiworakarn
- Département d'Ingénierie et d'Etudes des Protéines, C.E. SACLAY, CEA, 91191 Gif-sur-Yvette CEDEX, France
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Urbinati C, Mitola S, Tanghetti E, Kumar C, Waltenberger J, Ribatti D, Presta M, Rusnati M. Integrin alphavbeta3 as a target for blocking HIV-1 Tat-induced endothelial cell activation in vitro and angiogenesis in vivo. Arterioscler Thromb Vasc Biol 2005; 25:2315-20. [PMID: 16166568 DOI: 10.1161/01.atv.0000186182.14908.7b] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE The transactivating factor (Tat) of HIV-1 binds to alphavbeta3 integrin present on endothelial cells contributing to neovascularization. Here, we investigated the biological consequences of Tat/alphavbeta3 interaction and the antagonist effect of an Arg-Gly-Asp (RGD)-based peptidomimetic. METHODS AND RESULTS Binding of Tat to endothelial alphavbeta3 triggers focal adhesion kinase and nuclear factor-kappaB activation, leading to endothelial cell proliferation, membrane ruffling, and motility in vitro and neovascularization in vivo. The RGD-peptidomimetic SCH221153 inhibits Tat/alphavbeta3 interaction in a solid phase binding assay and endothelial cell adhesion to immobilized Tat with a potency higher than that of RGD-containing peptides. Accordingly, SCH221153 inhibits Tat/alphavbeta3-dependent focal adhesion kinase and nuclear factor-kappaB activation, proliferation, membrane ruffling, and motility in endothelial cells. Finally, SCH221153 inhibits the angiogenic response triggered by Tat in the chick-embryo chorioallantoic membrane without affecting physiological vascularization. SCH221153 exerts these inhibitory effects without affecting the interaction of Tat with endothelial heparan sulfate proteoglycans or with the vascular endothelial growth factor receptor-2/kinase domain-containing receptor. In all the assays the negative control SCH216687 was ineffective. CONCLUSIONS These data provide new insights on the mechanism of endothelial cell activation by Tat and point to RGD peptidomimetics as prototypes for the development of novel Tat antagonists.
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MESH Headings
- Animals
- Aorta/cytology
- Benzimidazoles/pharmacology
- Cattle
- Cell Line, Transformed
- Chick Embryo
- Chickens
- Endothelium, Vascular/cytology
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/virology
- Gene Products, tat/antagonists & inhibitors
- Gene Products, tat/metabolism
- HIV Infections/drug therapy
- HIV Infections/metabolism
- HIV Infections/physiopathology
- HIV-1
- Humans
- In Vitro Techniques
- Integrin alphaVbeta3/metabolism
- Neovascularization, Pathologic/drug therapy
- Neovascularization, Pathologic/metabolism
- Neovascularization, Pathologic/virology
- Oligopeptides/metabolism
- Peptide Fragments/antagonists & inhibitors
- Peptide Fragments/metabolism
- Signal Transduction/drug effects
- Swine
- Umbilical Veins/cytology
- tat Gene Products, Human Immunodeficiency Virus
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Affiliation(s)
- Chiara Urbinati
- Department of Biomedical Sciences and Biotechnology, University of Brescia, Italy
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Peruzzi F, Bergonzini V, Aprea S, Reiss K, Sawaya BE, Rappaport J, Amini S, Khalili K. Cross talk between growth factors and viral and cellular factors alters neuronal signaling pathways: implication for HIV-associated dementia. ACTA ACUST UNITED AC 2005; 50:114-25. [PMID: 15936090 DOI: 10.1016/j.brainresrev.2005.05.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2004] [Revised: 03/10/2005] [Accepted: 05/02/2005] [Indexed: 12/14/2022]
Abstract
HIV-associated dementia (HAD) is a serious neurological disorder affecting about 7% of people with AIDS. In the brain, HIV-1 infects a restricted number of cell types, being primarily present in macrophages and microglial cells, less abundant in astrocytes, and rarely seen in oligodendrocytes and neurons. Lack of a productive HIV-1 infection of neuronal cells suggests the presence of an indirect pathway by which the virus may determine the brain pathology and neuronal dysfunction seen in AIDS patients. Among the participants in this event, viral proteins including gp120 and Tat, along with host factors including cytokines, chemokines, and several signaling pathways have received considerable attention. In this article, we discuss the most recent concepts pertaining to the mechanisms of HIV-1-induced neuronal dysfunction by highlighting the interplay between signal transduction pathways activated by viral and host factors and their consequences in neuronal cell function.
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Affiliation(s)
- Francesca Peruzzi
- Center for Neurovirology and Cancer Biology, Temple University, 1900 12th North Street, Philadelphia, PA 19122, USA.
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El-Hage N, Gurwell JA, Singh IN, Knapp PE, Nath A, Hauser KF. Synergistic increases in intracellular Ca2+, and the release of MCP-1, RANTES, and IL-6 by astrocytes treated with opiates and HIV-1 Tat. Glia 2005; 50:91-106. [PMID: 15630704 PMCID: PMC4301446 DOI: 10.1002/glia.20148] [Citation(s) in RCA: 182] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Recent evidence suggests that injection drug users who abuse heroin are at increased risk of CNS complications from human immunodeficiency virus (HIV) infection. Opiate drugs may intrinsically alter the pathogenesis of HIV by directly modulating immune function and by directly modifying the CNS response to HIV. Despite this, the mechanisms by which opiates increase the neuropathogenesis of HIV are uncertain. In the present study, we describe the effect of morphine and the HIV-1 protein toxin Tat(1-72) on astroglial function in cultures derived from ICR mice. Astroglia maintain the blood-brain barrier and influence inflammatory signaling in the CNS. Astrocytes can express mu-opioid receptors, and are likely targets for abused opiates, which preferentially activate mu-opioid receptors. While Tat alone disrupts astrocyte function, when combined with morphine, Tat causes synergistic increases in [Ca(2+)](i). Moreover, astrocyte cultures treated with morphine and Tat showed exaggerated increases in chemokine release, including monocyte chemoattractant protein-1 (MCP-1) and regulated on activation, normal T cell expressed and secreted (RANTES), as well as interleukin-6 (IL-6). Morphine-Tat interactions were prevented by the mu-opioid receptor antagonist beta-funaltrexamine, or by immunoneutralizing Tat(1-72) or substituting a nontoxic, deletion mutant (Tat(Delta31-61)). Our findings suggest that opiates may increase the vulnerability of the CNS to viral entry (via recruitment of monocytes/macrophages) and ensuing HIV encephalitis by synergistically increasing MCP-1 and RANTES release by astrocytes. The results further suggest that astrocytes are key intermediaries in opiate-HIV interactions and disruptions in astroglial function and inflammatory signaling may contribute to an accelerated neuropathogenesis in HIV-infected individuals who abuse opiates.
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Affiliation(s)
- Nazira El-Hage
- Department of Anatomy & Neurobiology, University of Kentucky College of Medicine, Lexington, KY, 40536 USA
| | - Julie A. Gurwell
- Department of Anatomy & Neurobiology, University of Kentucky College of Medicine, Lexington, KY, 40536 USA
| | - Indrapal N. Singh
- Department of Anatomy & Neurobiology, University of Kentucky College of Medicine, Lexington, KY, 40536 USA
| | - Pamela E. Knapp
- Department of Anatomy & Neurobiology, University of Kentucky College of Medicine, Lexington, KY, 40536 USA
- Spinal Cord and Brain Injury Research Center, University of Kentucky Medical Center, Lexington, KY, 40536 USA
| | - Avindra Nath
- Department of Neurology, Johns Hopkins University, Baltimore, MD, 21287 USA
| | - Kurt F. Hauser
- Department of Anatomy & Neurobiology, University of Kentucky College of Medicine, Lexington, KY, 40536 USA
- Spinal Cord and Brain Injury Research Center, University of Kentucky Medical Center, Lexington, KY, 40536 USA
- Address correspondence and reprint requests to Dr. Kurt F. Hauser, Department of Anatomy & Neurobiology, University of Kentucky College of Medicine, 800 Rose Street, Lexington, KY 40536-0298 USA, ; Phone: (859) 323-6477; FAX: (859) 323-5946)
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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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Tsabar N, Gefen A, Elias S, Frank D. Aggregation of maternal pigment granules is induced by the cytosolic discoidin domain of theXenopus Del1 protein. Dev Dyn 2005; 233:224-32. [PMID: 15765521 DOI: 10.1002/dvdy.20308] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Xenopus oocytes generate pigment granules (melanosomes) that predominantly localize to the animal hemisphere cortex. During embryonic development, these granules are located near the membranes of outer layer ectoderm cells. We report a novel phenotype found during an expression cloning screen in Xenopus laevis embryos. The phenotype is characterized by dissociation of pigment granules from the cell membrane to form large central aggregates. This phenomenon was induced by a truncated form of the Xenopus Del1 (XDel1) protein that contains only the C-terminal discoidin (D2) domain. This truncated form of XDel1 localized to membranes as shown by a chimeric enhanced green fluorescent protein construct. Although a similar localization occurred in immature oocytes, dissociation of pigment granules was limited to the oocyte vegetal hemisphere. The full-length XDel1 cDNA was cloned, and XDel1 mRNA expression was found to be ubiquitous and continuous from early oocyte to tail bud stages, with a transient enrichment in the cement gland. Ectopic expression of various deletion or full-length constructs or antisense morpholino oligonucleotides did not induce any significant developmental phenotypes.
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Affiliation(s)
- Nir Tsabar
- Department of Biochemistry, The Rappaport Family Institute for Research in the Medical Sciences, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 31096, Israel
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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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Régulier EG, Reiss K, Khalili K, Amini S, Zagury JF, Katsikis PD, Rappaport J. T-cell and neuronal apoptosis in HIV infection: implications for therapeutic intervention. Int Rev Immunol 2004; 23:25-59. [PMID: 14690854 DOI: 10.1080/08830180490265538] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The pathogenesis of HIV infection involves the selective loss of CD4+ T cells contributing to immune deficiency. Although loss of T cells leading to immune dysfunction in HIV infection is mediated in part by viral infection, there is a much larger effect on noninfected T cells undergoing apoptosis in response to activation stimuli. In the subset of patients with HIV dementia complex, neuronal injury, loss, and apoptosis are observed. Viral proteins, gp120 and Tat, exhibit proapoptotic activities when applied to T cell and neuronal cultures by direct and indirect mechanisms. The pathways leading to cell death involve the activation of one or more death receptor pathways (i.e., TNF-alpha, Fas, and TRAIL receptors), chemokine receptor signaling, cytokine dysregulation, caspase activation, calcium mobilization, and loss of mitochondrial membrane potential. In this review, the mechanisms involved in T-cell and neuronal apoptosis, as well as antiapoptotic pathways potentially amenable to therapeutic application, are discussed.
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Affiliation(s)
- Emmanuel G Régulier
- Center for Neurovirology and Cancer Biology, Temple University, Philadelphia, Pennsylvania 19122, USA
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42
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Shoham N, Cohen L, Yaniv A, Gazit A. The Tat protein of the human immunodeficiency virus type 1 (HIV-1) interacts with the EGF-like repeats of the Notch proteins and the EGF precursor. Virus Res 2004; 98:57-61. [PMID: 14609630 DOI: 10.1016/j.virusres.2003.08.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Employing the yeast two-hybrid system, the Tat protein of the human immunodeficiency virus (HIV) was shown to interact with a region spanning the EGF-like repeats 1-6 of the mouse Notch1, the human Notch2 and the Drosophila Notch. This observation was confirmed in mammalian cells by demonstrating an interaction between the HIV Tat and the EGF-like repeats 1-6 of the various Notch proteins. The HIV Tat protein interacted also with the full-length mouse Notch1 receptor when co-expressed in mammalian cells. Moreover, the HIV Tat protein interacted also with the EGF-like repeats 1-4-spanning domain of the human EGF precursor. The ability of the HIV Tat protein to interact with the Notch proteins and possibly with other EGF-like repeats-bearing proteins, suggests that such interactions might modulate their physiological functions, thus affecting various AIDS-associated pathologies.
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Affiliation(s)
- Nitza Shoham
- Department of Human Microbiology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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Huigen MCDG, Kamp W, Nottet HSLM. Multiple effects of HIV-1 trans-activator protein on the pathogenesis of HIV-1 infection. Eur J Clin Invest 2004; 34:57-66. [PMID: 14984439 DOI: 10.1111/j.1365-2362.2004.01282.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The HIV-1 trans-activator (Tat) protein is proposed as an important factor in the complex HIV-induced pathogenesis of AIDS. In this paper, multiple effects of this viral protein are described. Originally discovered as an intracellular activator of HIV-1 transcription, Tat was found to regulate viral reverse transcription as well. Trans-activator was found to be secreted by HIV-infected cells and taken up by neighbouring cells. In this way, Tat is able to affect both infected and uninfected cells. Intracellularly, Tat can deregulate the expression of several heterologous cellular and viral genes. Extracellular Tat can contribute to the spreading of HIV-1 and immunosuppression of uninfected cells. Finally, there is evidence that exogenous Tat is involved in AIDS-associated pathologies such as Kaposi's sarcoma and HIV-associated dementia. These capacities together accelerate the progression towards AIDS and make Tat an interesting candidate as a constituent of an anti-AIDS vaccine.
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Affiliation(s)
- M C D G Huigen
- Eijkman-Winkler Center for Microbiology, Infectious Disease and Inflammation, Utrecht, The Netherlands
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Noonan DM, Gringeri A, Meazza R, Rosso O, Mazza S, Muça-Perja M, Le Buanec H, Accolla RS, Albini A, Ferrini S. Identification of immunodominant epitopes in inactivated Tat-vaccinated healthy and HIV-1-infected volunteers. J Acquir Immune Defic Syndr 2003; 33:47-55. [PMID: 12792355 DOI: 10.1097/00126334-200305010-00008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We analyzed the epitopes and the molecular forms of Tat recognized by the antibodies raised by Tat-toxoid vaccination in both healthy and HIV-infected volunteers. Tat-toxoid-vaccinated healthy volunteer sera reacted predominantly with peptides covering amino acids 1 through 24 and 46 through 60, corresponding to the N-terminus and basic domains of Tat. In contrast, whereas all sera from vaccinated HIV-1-positive patients reacted with the N-terminus and (with a single exception) with the basic domain, most of these sera also recognized peptides encompassing distinct domains of Tat, particularly the C-terminus (79-86). The sera of vaccinated individuals recognized both monomeric and oligomeric forms of Tat 1 through 86 or of Tat 1 through 101 and also blocked the ability of cell-released extracellular Tat to transactivate the HIV-1 LTR promoter. Synthetic Tat preincubated with sera from vaccinated individuals lost its functional activity as well. This is probably because of its inability to enter the cells as a result of immune complex formation with anti-Tat IgG. These data demonstrate that Tat-toxoid vaccination induces an efficient antibody response blocking the functional activity of Tat.
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Affiliation(s)
- Douglas M Noonan
- Tumor Progression Section, double dagger Immuno-Pharmacology Section, and #Molecular Biology Laboratory, Istituto Nazionale per la Ricerca sul Cancro, Genova, Italy
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45
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Nyhus J, Sommerfelt MA, Sørensen B. Peptide from Tat basic domain shows striking similarity to a region of human T cell transcription factor 1. AIDS Res Hum Retroviruses 2003; 19:345-6. [PMID: 12804007 DOI: 10.1089/088922203764969555] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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46
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Brigati C, Giacca M, Noonan DM, Albini A. HIV Tat, its TARgets and the control of viral gene expression. FEMS Microbiol Lett 2003; 220:57-65. [PMID: 12644228 DOI: 10.1016/s0378-1097(03)00067-3] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The human immunodeficiency virus (HIV-1) (transactivator of transcription (Tat)) protein is a pleiotropic factor that induces a broad range of biological effects in numerous cell types. At the HIV promoter, Tat is a powerful transactivator of gene expression, which acts by both inducing chromatin remodeling and by recruiting elongation-competent transcriptional complexes onto the viral LTR. Besides these transcriptional activities, Tat is released outside the cells and interacts with different cell membrane-associated receptors. Finally, extracellular Tat can be internalized by cells through an active endocytosis process. Here we discuss some of the molecular mechanisms involved in intracellular and extracellular Tat function.
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MESH Headings
- Acetylation
- Acetyltransferases/metabolism
- Bacteriophage lambda/genetics
- Chromatin/genetics
- Chromatin/metabolism
- Endocytosis
- Extracellular Space/metabolism
- Gene Expression Regulation, Viral
- Gene Products, tat/physiology
- Genes, tat
- HIV Long Terminal Repeat
- HIV-1/genetics
- Histone Acetyltransferases
- Histones/metabolism
- Humans
- Intracellular Fluid/metabolism
- Models, Biological
- Positive Transcriptional Elongation Factor B
- Promoter Regions, Genetic/genetics
- Protein Processing, Post-Translational
- Protein Serine-Threonine Kinases/metabolism
- RNA Polymerase II/metabolism
- RNA, Messenger/biosynthesis
- RNA, Viral/metabolism
- Receptors, Virus/physiology
- Regulatory Sequences, Nucleic Acid
- Saccharomyces cerevisiae Proteins/metabolism
- Transcriptional Activation
- tat Gene Products, Human Immunodeficiency Virus
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Affiliation(s)
- Claudio Brigati
- Molecular Oncology Laboratory, National Cancer Research Institute, c/o Centro di Biotecnologie Avanzante, Largo Rosanna Benzi 10, 16132 Genova, Italy
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Wang FZ, Akula SM, Sharma-Walia N, Zeng L, Chandran B. Human herpesvirus 8 envelope glycoprotein B mediates cell adhesion via its RGD sequence. J Virol 2003; 77:3131-47. [PMID: 12584338 PMCID: PMC149745 DOI: 10.1128/jvi.77.5.3131-3147.2003] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human herpesvirus 8 (HHV-8) or Kaposi's sarcoma-associated herpesvirus, implicated in the pathogenesis of Kaposi's sarcoma, utilizes heparan sulfate-like molecules to bind the target cells via its envelope-associated glycoproteins gB and gpK8.1A. HHV-8-gB possesses the Arg-Gly-Asp (RGD) motif, the minimal peptide region of many proteins known to interact with subsets of host cell surface integrins. HHV-8 utilizes alpha3beta1 integrin as one of the receptors for its entry into the target cells via its gB interaction and induces the activation of focal adhesion kinase (FAK) (S. M. Akula, N. P. Pramod, F.-Z. Wang, and B. Chandran, Cell 108:407-419, 2002). Since FAK activation is the first step in the outside-in signaling necessary for integrin-mediated cytoskeletal rearrangements, cell adhesions, motility, and proliferation, the ability of HHV-8-gB to mediate the target cell adhesion was examined. A truncated form of gB without the transmembrane and carboxyl domains (gBdeltaTM) and a gBdeltaTM mutant (gBdeltaTM-RGA) with a single amino acid mutation (RGD to RGA) were expressed in a baculovirus system and purified. Radiolabeled HHV-8-gBdeltaTM, gBdeltaTM-RGA, and deltaTMgpK8.1A proteins bound to the human foreskin fibroblasts (HFFs), human dermal microvascular endothelial (HMVEC-d) cells, human B (BJAB) cells, and Chinese hamster ovary (CHO-K1) cells with equal efficiency, which was blocked by preincubation of proteins with soluble heparin. Maxisorp plate-bound gBdeltaTM protein induced the adhesion of HFFs and HMVEC-d and monkey kidney epithelial (CV-1) cells in a dose-dependent manner. In contrast, the gBdeltaTM-RGA and DeltaTMgpK8.1A proteins did not mediate adhesion. Adhesion mediated by gBdeltaTM was blocked by the preincubation of target cells with RGD-containing peptides or by the preincubation of plate-bound gBdeltaTM protein with rabbit antibodies against gB peptide containing the RGD sequence. In contrast, adhesion was not blocked by the preincubation of plate-bound gBdeltaTM protein with heparin, suggesting that the adhesion is mediated by the RGD amino acids of gB, which is independent of the heparin-binding domain of gB. Integrin-ligand interaction is dependent on divalent cations. Adhesion induced by the gBdeltaTM was blocked by EDTA, thus suggesting the role of integrins in the observed adhesions. Focal adhesion components such as FAK and paxillin were activated by the binding of gBdeltaTM protein to the target cells but not by gBdeltaTM-RGA protein binding. Inhibition of FAK phosphorylation by genistein blocked gBdeltaTM-induced FAK activation and cell adhesion. These findings suggest that HHV-8-gB could mediate cell adhesion via its RGD motif interaction with the cell surface integrin molecules and indicate the induction of cellular signaling pathways, which may play roles in the infection of target cells and in Kaposi's sarcoma pathogenesis.
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Affiliation(s)
- Fu-Zhang Wang
- Department of Microbiology, Molecular Genetics and Immunology, The University of Kansas Medical Center, Kansas City, Kansas 66160, USA
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Abstract
The human immunodeficiency virus Tat protein is essential for virus replication and is a candidate vaccine antigen. Macaques immunized with Tat or chemically modified Tat toxoid having the same clade B sequence developed strong antibody responses. We compared these antisera for their abilities to recognize diverse Tat sequences. An overlapping peptide array covering three clade B and two clade C Tat sequences was constructed to help identify reactive linear epitopes. Sera from Tat-immunized macaques were broadly cross-reactive with clade B and clade C sequences but recognized a clade B-specific epitope in the basic domain. Sera from Tat toxoid-immunized macaques had a more restricted pattern of recognition, reacting mainly with clade B and with only one clade B basic domain sequence, which included the rare amino acids RPPQ at positions 57 to 60. Monoclonal antibodies against the amino terminus or the domain RPPQ sequence blocked Tat uptake into T cells and neutralized Tat in a cell-based transactivation assay. Macaques immunized with Tat or Tat toxoid proteins varied in their responses to minor epitopes, but all developed a strong response to the amino terminus, and antisera were capable of neutralizing Tat in a transactivation assay.
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Affiliation(s)
- Ilia Tikhonov
- Institute of Human Virology, University of Maryland Biotechnology Institute, Baltimore, Maryland 21201, USA
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Ambrosino C, Palmieri C, Puca A, Trimboli F, Schiavone M, Olimpico F, Ruocco MR, di Leva F, Toriello M, Quinto I, Venuta S, Scala G. Physical and functional interaction of HIV-1 Tat with E2F-4, a transcriptional regulator of mammalian cell cycle. J Biol Chem 2002; 277:31448-58. [PMID: 12055184 DOI: 10.1074/jbc.m112398200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Tat protein of the human immunodeficiency virus type-1 (HIV-1) plays a critical role in the regulation of viral transcription and replication. In addition, Tat regulates the expression of a variety of cellular genes and could account for AIDS-associated diseases including Kaposi's Sarcoma and non-Hodgkin's lymphoma by interfering with cellular processes such as proliferation, differentiation, and apoptosis. The molecular mechanisms underlying the pleiotropic activities of Tat may include the generation of functional heterodimers of Tat with cellular proteins. By screening a human B-lymphoblastoid cDNA library in the yeast two-hybrid system, we identified E2F-4, a member of E2F family of transcription factors, as a Tat-binding protein. The interaction between Tat and E2F-4 was confirmed by GST pull-down experiments performed with cellular extracts as well as with in vitro translated E2F-4. The physical association of Tat and E2F-4 was confirmed by in vivo binding experiments where Tat.E2F-4 heterodimers were recovered from Jurkat cells by immunoprecipitation and immunoblotting. By using plasmids expressing mutant forms of Tat and E2F-4, the domains involved in Tat.E2F-4 interaction were identified as the regions encompassing amino acids 1-49 of Tat and amino acids 1-184 of E2F-4. Tat x E2F-4 complexes were shown to bind to E2F cis-regions with increased efficiency compared with E2F-4 alone and to mediate the activity of E2F-dependent promoters including HIV-1 long terminal repeat and cyclin A. The data point to Tat as an adaptor protein that recruits cellular factors such as E2F-4 to exert its multiple biological activities.
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Affiliation(s)
- Concetta Ambrosino
- Department of Clinical and Experimental Medicine, Medical School, University of Catanzaro, 88100 Catanzaro, Italy
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Cota-Gomez A, Flores NC, Cruz C, Casullo A, Aw TY, Ichikawa H, Schaack J, Scheinman R, Flores SC. The human immunodeficiency virus-1 Tat protein activates human umbilical vein endothelial cell E-selectin expression via an NF-kappa B-dependent mechanism. J Biol Chem 2002; 277:14390-9. [PMID: 11827962 DOI: 10.1074/jbc.m108591200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human immunodeficiency virus infection is associated with inflammation and endothelial cell activation that cannot be ascribed to direct infection by the virus or to the presence of opportunistic infections. Factors related to the virus itself, to the host and/or to environmental exposures probably account for these observations. The HIV protein Tat, a viral regulator required for efficient transcription of the viral genome in host cells is secreted from infected cells and taken up by uninfected by-stander cells. Tat can also act as a general transcriptional activator of key inflammatory molecules. We have examined whether Tat contributes to this endothelial cell activation by activating NF-kappaB. Human endothelial cells exposed to Tat in the culture medium activated E-selectin expression with delayed kinetics compared with tumor necrosis factor (TNF). Tat-mediated E-selectin up-regulation required the basic domain of Tat and was inhibited by a Tat antibody. Transfection of human E-selectin promoter-luciferase reporter constructs into Tat-bearing cells or into endothelial cells co-transfected with a Tat expression vector resulted in induction of luciferase expression. Either Tat or TNF activated p65 translocation and binding to an oligonucleotide containing the E-selectin kappaB site 3 sequence. Tat-mediated p65 translocation was also delayed compared with TNF. Neither agent induced new synthesis of p65. A super-repressor adenovirus (AdIkappaBalphaSR) that constitutively sequesters IkappaB in the cytoplasm as well as cycloheximide or actinomycin D inhibited Tat- or TNF-mediated kappaB translocation and E-selectin up-regulation.
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Affiliation(s)
- Adela Cota-Gomez
- Webb-Waring Institute for Cancer, Aging and Antioxidant Research, the Department of Microbiology, School of Pharmacy, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA
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