1 May 2008 Activation of caspase-3 noninvolved in the bystander effect of the herpes simplex virus thymidine kinase gene/ganciclovir (HSV-tk/GCV) system
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J. of Biomedical Optics, 13(3), 031209 (2008). doi:10.1117/1.2937830
Abstract
Use of the herpes simplex virus thymidine kinase gene/ganciclovir (HSV-tk/GCV) system is one of the promising approaches in the rapidly growing area of gene therapy. The "bystander effect," a phenomenon in which HSV-tk+ cells exposed to GCV are toxic to adjacent HSV-tk-; cells, was reported to play an important role in suicide gene therapy. However, the mechanism by which HSV-tk/GCV induces the bystander effect is poorly understood. We monitored the activation of caspase-3 in living cells induced by the HSV-tk/GCV system using a genetically encoded fluorescence resonance energy transfer (FRET) probe CD3, a caspase-3 recognition site fused with a cyan fluorescent protien (CFP) and a red fluorescent protein (DsRed) which we reported and named in a previous paper. Fluorescence protein (FP)–based multicolor cellular labeling, combined with the multichannel fluorescence imaging and FRET imaging techniques, provides a novel and improved approach to directly determine whether the activation of caspase-3 involved in the HSV-tk/GCV system induces cell apoptosis in tk gene-expressing cells and their neighboring cells. FRET ratio images of CD3, and fluorescence images of the fusion protein of thymidine kinase linked with green fluorescent protein (TK-GFP), indicated that HSV-tk/GCV system–induced apoptosis in human adenoid cystic carcinoma (ACC-M) cells was via a caspase-3 pathway, and the activation of caspase-3 was not involved in the bystander effect of HSV-tk/GCV system.
Zhihong Zhang, Juqiang Lin, Jun Chu, Yan Ma, Shaoqun Zeng, Qingming Luo, "Activation of caspase-3 noninvolved in the bystander effect of the herpes simplex virus thymidine kinase gene/ganciclovir (HSV-tk/GCV) system," Journal of Biomedical Optics 13(3), 031209 (1 May 2008). http://dx.doi.org/10.1117/1.2937830
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KEYWORDS
Fluorescence resonance energy transfer

Cell death

Luminescence

Multichannel imaging systems

Green fluorescent protein

Imaging systems

Proteins

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