Valproic acid enhances gene expression from viral gene transfer vectors
Department of Microbiology and Immunology, University of Rochester, Rochester, New York, United StatesJournal of Virological Methods (Impact Factor: 1.78). 05/2005; 125(1):23-33. DOI: 10.1016/j.jviromet.2004.11.023
Viral vectors represent an efficient delivery method for in vitro and in vivo gene transfer, and their utility may be further enhanced through the use of pharmacologic agents that increase gene expression. Here, we demonstrate that valproic acid (VPA), a drug which is widely used for the treatment of epilepsy and mood disorders, enhances and prolongs expression of exogenous genes in cells transduced with various gene transfer agents, including adenovirus, adeno-associated virus and herpesvirus vectors. This effect occurs in a wide range of cell types, including both primary cells and cell lines, and appears to be associated with VPA's ability to function as a histone deacetylase inhibitor (HDACi). VPA treatment also enhanced adenovirally-vectored expression of a luciferase reporter gene in mice, as demonstrated by in vivo imaging. VPA was also less cytotoxic than a commonly used HDAC inhibitor, TSA, suggesting its use as a safer alternative. Taken together, these results suggest that VPA treatment may represent a useful approach to various gene transfer approaches in which enhanced transgene expression is desirable.
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- "VPA does not quantitatively affect pDNA uptake and/or stability following PEI-mediated transfection (Wulhfard et al. 2010). Additional HDAC inhibitors tested for transient transfection improvement include trichostatin A which has shown to enhance LacZ (Fan et al. 2005), IgG (Backliwal et al. 2008c), and GFP and Luciferase expression using both plasmid DNA and a BacMam virus DNA templates (Spenger et al. 2004). The effect of several transfection enhancers on the production of Gag-based virus-like particles (VLPs) in HEK 293 cultures is investigated in this work using design of experiment methodology. "
ABSTRACT: The manufacturing of biopharmaceuticals in mammalian cells typically relies on the use of stable producer cell lines. However, in recent years, transient gene expression has emerged as a suitable technology for rapid production of biopharmaceuticals. Transient gene expression is particularly well suited for early developmental phases, where several potential therapeutic targets need to be produced and tested in vivo. As a relatively new bioprocessing modality, a number of opportunities exist for improving cell culture productivity upon transient transfection. For instance, several compounds have shown positive effects on transient gene expression. These transfection enhancers either facilitate entry of PEI/DNA transfection complexes into the cell or nucleus or increase levels of gene expression. In this work, the potential of combining transfection enhancers to increase Gag-based virus-like particle production levels upon transfection of suspension-growing HEK 293 cells is evaluated. Using Plackett-Burman design of experiments, it is first tested the effect of eight transfection enhancers: trichostatin A, valproic acid, sodium butyrate, dimethyl sulfoxide (DMSO), lithium acetate, caffeine, hydroxyurea, and nocodazole. An optimal combination of compounds exhibiting the highest effect on gene expression levels was subsequently identified using a surface response experimental design. The optimal consisted on the addition of 20 mM lithium acetate, 3.36 mM valproic acid, and 5.04 mM caffeine which increased VLP production levels 3.8-fold, while maintaining cell culture viability at 94 %.
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- "Fan and colleagues reported that treatment with VPA resulted in increased expression of exogenous genes in cells transduced with various viral-based gene transfer vectors, including adenovirus, adeno-associated virus and herpesvirus vectors 28. Recently, the effect of VPA on adenovirus vector-mediated transduction was reported. "
ABSTRACT: Virus vector-mediated gene transfer has been developed as a treatment for cystic fibrosis (CF) airway disease, a lethal inherited disorder caused by somatic mutations in the cystic fibrosis transmembrane conductance regulator gene. The pathological proinflammatory environment of CF as well as the naïve and adaptive immunity induced by the virus vector itself limits the effectiveness of gene therapy for CF airway. Here, we report the use of an HDAC inhibitor, valproic acid (VPA), to enhance the activity of the regulatory T cells (Treg) and to improve the expression of virus vector-mediated gene transfer to the respiratory epithelium. Our study demonstrates the potential utility of VPA, a drug used for over 50 years in humans as an anticonvulsant and mood-stabilizer, in controlling inflammation and improving the efficacy of gene transfer in CF airway.Gene Therapy advance online publication, 2 January 2014; doi:10.1038/gt.2013.78.
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- "We examined MIE gene-expression levels after increasing MIEP activity by using transcriptional activators known to upregulate MIEP activity (Choi et al., 2005; Fan et al., 2005; Hummel and Abecassis, 2002). These transcriptional activators, Valproic "
ABSTRACT: Many signaling circuits face a fundamental tradeoff between accelerating their response speed while maintaining final levels below a cytotoxic threshold. Here, we describe a transcriptional circuitry that dynamically converts signaling inputs into faster rates without amplifying final equilibrium levels. Using time-lapse microscopy, we find that transcriptional activators accelerate human cytomegalovirus (CMV) gene expression in single cells without amplifying steady-state expression levels, and this acceleration generates a significant replication advantage. We map the accelerator to a highly self-cooperative transcriptional negative-feedback loop (Hill coefficient ∼7) generated by homomultimerization of the virus's essential transactivator protein IE2 at nuclear PML bodies. Eliminating the IE2-accelerator circuit reduces transcriptional strength through mislocalization of incoming viral genomes away from PML bodies and carries a heavy fitness cost. In general, accelerators may provide a mechanism for signal-transduction circuits to respond quickly to external signals without increasing steady-state levels of potentially cytotoxic molecules.
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