• Molecules and Cells
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• v.21 no.1
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• pp.104-111
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• 2006

Gene therapy with nonviral vectors using the suicide gene/prodrug activating system of herpes simplex virus type-1 thymidine kinase (HSV1-TK)/ganciclovir (GCV) is inefficient in killing malignant tumor cells due to two major factors: (a) an unsatisfactory bystander effect; (b) short-lived expression of the protein. To study the capacity of the protein transduction domain (PTD) of HIV-1 TAT protein to enhance HSV1-TK/GCV cancer gene therapy, we constructed three fusion proteins TAT-TK, TK-TAT and TK. TAT-TK retained as much enzyme activity as TK, whereas that of TK-TAT was much lower. TAT-TK can enter HepG2 cells and much of it is translocated to the nucleus. The transduced HepG2 cells are killed by exogenously added GCV and have bystander effects on untransduced HepG2 cells. Most importantly, the introduced recombinant protein is stable and remains functional for several days at least, probably because nuclear localization protects it from the cytoplasmic degradation machinery and provides access to the nuclear transcription machinery. Our results indicate that TAT fusion proteins traffic intercellularly and have enhanced stability and prodrug cell killing activity. We conclude that TAT has potential for enhancing enzyme prodrug treatment of liver cancers.

• Molecules and Cells
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• v.19 no.2
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• pp.191-197
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• 2005

The human immunodeficiency virus type 1 (HIV-1) Tat protein transduction domain (PTD) is responsible for highly efficient protein transduction across plasma membranes. In a previous study, we showed that Tat-Cu,Zn-superoxide dismutase (Tat-SOD) can be directly transduced into mammalian cells across the lipid membrane barrier. In this study, we fused the human SOD gene with a Tat PTD transduction vector at its N- and/or C-terminus. The fusion proteins (Tat-SOD, SOD-Tat, Tat-SOD-Tat) were purified from Escherichia coli and their ability to enter cells in vitro and in vivo compared by Western blotting and immunohistochemistry. The transduction efficiencies and biological activities of the SOD fusion protein with the Tat PTD at either terminus were equivalent and lower than the fusion protein with the Tat PTD at both termini. The availability of a more efficient SOD fusion protein provides a powerful vehicle for therapy in human diseases related to this anti-oxidant enzyme and to reactive oxygen species.

• IMMUNE NETWORK
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• v.11 no.3
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• pp.182-189
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• 2011

Background: Cytotoxic T lymphocytes (CTLs) appear to play an important role in the control and prevention of human cytomegalovirus (HCMV) infection. The pp65 antigen is a structural protein, which has been defined as a potential target for effective immunity against HCMV infection. Incorporation of an 11 amino acid region of the HIV TAT protein transduction domain (Tat) into protein facilitates rapid, efficient entry into cells. Methods: To establish a strategy for the generation of HCMV-specific CTLs in vitro, recombinant truncated N- and C-terminal pp65 protein (pp65 N&C) and N- and C-terminal pp65 protein fused with Tat (Tat/pp65 N&C) was produced in E.coli system. Peripheral blood mononuclear cells were stimulated with dendritic cells (DCs) pulsed with pp65 N&C or Tat/pp65 N&C protein and immune responses induced was examined using IFN-${\gamma}$ ELISPOT assay, cytotoxicity assay and tetramer staining. Results: DCs pulsed with Tat/pp65N&C protein could induce higher T-cell responses in vitro compared with pp65N&C. Moreover, the DCs pulsed with Tat/pp65 N&C could stimulate both of $CD8^+$ and $CD4^+$ T-cell responses. The T cells induced by DCs pulsed with Tat/pp65 N&C showed higher cytotoxicity than that of pp65-pulsed DCs against autologous lymphoblastoid B-cell line (LCL) expressing the HCMV-pp65 antigen. Conclusion: Our results suggest that DCs pulsed with Tat/pp65 N&C protein effectively induced pp65-specific CTL in vitro. Tat fusion recombinant protein may be useful for the development of adoptive T-cell immunotherapy and DC-based vaccines.

• Journal of Microbiology
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• v.42 no.4
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• pp.328-335
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• 2004

The human immunodeficiency virus type 1 (HIV-I) Tat protein transduction domain (PTD), which con­tains rich arginine and lysine residues, is responsible for the highly efficient transduction of protein through the plasma membrane. In addition, it can be secreted from infected cells and has the ability to enter neighboring cells. When the PTD of Tat is fused to proteins and exogenously added to cells, the fusion protein can cross plasma membranes. Recent reports indicate that the endogenously expressed Tat fusion protein can demonstrate biodistribution of several proteins. However, intercellular transport and protein transduction have not been observed in some studies. Therefore, this study exam­ined the intercellular transport and protein transduction of the Tat protein. The results showed no evi­dence of intercellular transport (biodistribution) in a cell culture. Instead, the Tat fusion peptides were found to have a significant effect on the transduction and intercellular localization properties. This sug­gests that the HIV-1 PTD passes through the plasma membrane in one direction.

• BMB Reports
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• v.54 no.9
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• pp.458-463
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• 2021

Cytokines activate inflammatory signals and are major mediators in progressive β-cell damage, which leads to type 1 diabetes mellitus. We recently showed that the cell-permeable Tat-CIAPIN1 fusion protein inhibits neuronal cell death induced by oxidative stress. However, how the Tat-CIAPIN1 protein affects cytokine-induced β-cell damage has not been investigated yet. Thus, we assessed whether the Tat-CIAPIN1 protein can protect RINm5F β-cells against cytokine-induced cytotoxicity. In cytokine-exposed RINm5F β-cells, the transduced Tat-CIAPIN1 protein elevated cell survivals and reduced reactive oxygen species (ROS) and DNA fragmentation levels. The Tat-CIAPIN1 protein reduced mitogen-activated protein kinases (MAPKs) and NF-κB activation levels and elevated Bcl-2 protein, whereas Bax and cleaved Caspase-3 proteins were decreased by this fusion protein. Thus, the protection of RINm5F β-cells by the Tat-CIAPIN1 protein against cytokine-induced cytotoxicity can suggest that the Tat-CIAPIN1 protein might be used as a therapeutic inhibitor against RINm5F β-cell damage.

• BMB Reports
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• v.39 no.1
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• pp.76-83
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• 2006

Pyridoxine-5-P oxidase catalyses the terminal step in the biosynthesis of pyridoxal-S-P, the biologically active form of vitamin $B_6$ Which acts as an essential cofactor. Here, a human brain pyridoxine-5-P oxidase gene was fused with a gene fragment encoding the HIV-1 Tat protein transduction domain (RKKRRQRRR) in a bacterial expression vector to produce a genetic in-frame Tat-pyridoxine-5-P oxidase fusion protein. Expressed and purified Tat-pyridoxine-5-P oxidase fusion protein transduced efficiently into PC12 cells in a time- and dose-dependent manner when added exogenously to culture media. Once inside the cells, the transduced Tat-pyridoxine-5-P oxidase protein showed catalytic activity and was stable for 48 h. Moreover, the formation of pyridoxal-5-P was increased by adding exogenous Tat-pyridoxine-5-P oxidase to media pre-treated with the vitamin $B_6$ precursor pyridoxine. In addition, the intracellular concentration of pyridoxal-S-P was markedly increased when Tat-pyridoxal kinase was transduced together with Tat-pyridoxine-5-P oxidase into cells. These results suggest that the transduction of Tat-pyridoxine-5-P oxidase fusion protein presents a means of regulating the level of pyridoxal-5-P and of replenishing this enzyme in various neurological disorders related to vitamin $B_6$.

• BMB Reports
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• v.41 no.7
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• pp.537-541
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• 2008

Epilepsy is characterized by the presence of spontaneous episodes of abnormal neuronal discharges and its pathogenic mechanisms remain poorly understood. Recently, we found that the expression of creatine kinase (CK) was markedly decreased in an epilepsy animal model using proteomic analysis. A human CK gene was fused with a HIV-1 Tat peptide to generate an in-frame Tat-CK fusion protein. The purified Tat-CK fusion protein was efficiently transduced into PC12 cells in a time- and dose-dependent manner when added exogenously to culture media. Once inside the cells, the transduced Tat-CK fusion protein was stable for 48 h. Moreover, the Tat-CK fusion protein markedly increased endogenous CK activity levels within the cells. These results suggest that Tat-CK provides a strategy for the therapeutic delivery of proteins in various human diseases including the delivery of CK for potential epilepsy treatment.

• Journal of Microbiology and Biotechnology
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• v.10 no.6
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• pp.797-804
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• 2000

The human immunodeficiency virus type 1 (HIV-1) Tat is one of the viral gene products essential for HIV replication. The exogenous Tat protein is transduced through the plasma membrane and then accumulated in a cell. The basic domain of the Tat protein, which is rich in arginine and lysine residues and called the protein transduction domain (PTD), has been identified to be responsible for this transduction activity. To better understand the nature of the transduction mediated by this highly basic domain of HIV-1 Tat, the Green Fluorescent Protein (GFP) was expressed and purified as a fusion protein with a peptide derived from the HIV-1 Tat basic domain in Escherichia coli. The transduction of Tat-GFP into mammalian cells was then determined by a Western blot analysis and fluorescence microscopy. The cells treated with Tat-GFP exhibited dose- and time-dependent increases in their intracellular level of the protein. the effective transduction of denatured Tat-GFP into both the nucleus and the cytoplasm of mammalian cells was also demonstrated, thereby indicating that the unfolding of the transduced protein is required for efficient transduction. Accordingly, the availability of recombinant Tat-GFP can facilitate the simple and specific identification of the protein transduction mediated by the HIV-1 Tat basic domain in living cells either by fluorescence microscopy or by a fluorescence-activated cell sorter analysis.

• IMMUNE NETWORK
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• v.6 no.4
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• pp.192-198
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• 2006

Background: Investigating strategy to enhance efficiency of gene transfer via adenovirus is critical to sustain gene expression in targeted cells or tissues to regulate immune responses. However, the use of adenovirus as a gene delivery method has been limited by the native tropism of the virus. In this study, the critical parameter is to improve the efficient binding of viral particles to the plasma membrane prior to cellular uptake. Methods: Human immunodeficiency virus (HIV-1) trans-acting activator of transcription (TAT), a protein transduction domain, was fused to the ectodomain of the coxsackie-adenovirus receptor (CAR). The CAR-TAT protein was produced from a Drosophila Schneider 2 cells (S2) transfected with CAR-TAT genes. The function of CARTAT was analyzed the efficiency of adenoviral gene transfer by flow cytometry, and then immunizing AdVGFP with CAR-TAT was transduced on dendritic cells (DCs). Results: S2 transfectants secreting CAR-TAT fusion protein has been stable over a period of 6 months and its expression was verified by western blot. Addition of CAR-TAT induced higher transduction efficiency for AdVGFP at every MOI tested. When mice were vaccinated with DC of which adenoviral transduction was mediated by CAR-TAT, the number of IFN-${\gamma}$ secreting T-cells was increased as compared with those DCs transduced without CAR-TAT. Conclusion: Our data provide evidence that CAR-TAT fusion protein enhances adenoviral transduction and immunogenecity of transgenes on DCs and may influence on the development of adenoviral-mediated anti-tumor immunotherapy.

• BMB Reports
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• v.42 no.5
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• pp.286-292
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• 2009

Arginine deiminase (ADI), an arginine-degrading enzyme, has anti-proliferative and anti-tumor activities and is capable of inhibiting the production of nitric oxide (NO). Modulation of nitric oxide (NO) production is considered a promising approach for the treatment of various diseases including cancer, inflammation and neuronal disorders. In this study, an ADI gene was fused with an HIV-1 Tat peptide in a bacterial expression vector to produce an genetic in-frame Tat-ADI fusion protein. When added exogenously to the culture media, the expressed and purified Tat-ADI fusion proteins were efficiently transduced into macrophage Raw 264.7 cells in a time- and dose-dependent manner. Furthermore, transduced Tat-ADI fusion proteins markedly increased cell viability in cells treated with lipopolysaccharide (LPS). This increase in viability was mediated by an inhibition of NO production. These results suggest that this Tat-ADI fusion protein can be used in protein therapies of NO-related disorders such as cancer, inflammation and neuronal diseases.