Gene expression in transgenic mice using neural promoters

Construction and Quantitative Evaluation of a Tissue-Specific Sleeping Beauty by EDL2-Specific Transposase Expression in Esophageal Squamous Carcinoma Cell Line KYSE-30

Gene delivery to esophageal tissue could provide novel treatments for diseases, such as cancer. The Sleeping Beauty (SB) transposon system, as a natural and non-viral tool, is efficient at transferring transgene into the human genome for human cell genetic engineering. The plasmid-based SB transposon can insert into chromosomes through an accurate recombinase-mediated mechanism, providing long-term expression of transgene integrated into the target cells. In this study, we aimed to investigate the activity of ED-L2 tissue-specific promoter that was engineered from the Epstein-Barr Virus (EBV) and combined with the hyperactive SB100X transposase to achieve the stable expression of T2-Onc3 transposon in esophageal squamous epithelial cells. Here we constructed an SB transposon-based plasmid system to obtain the stable expression of transposon upon introduction of a hyperactive SB transposase under the control of tissue-specific ED-L2 promoter via the lipid-based delivery method in the cultured esophageal squamous cell carcinoma cells. Among established human and mouse cell lines, the (ED-L2)-SB100X transposase was active only in human esophageal stratified squamous epithelial and differentiated keratinocytes derived from skin (KYSE-30 and HaCaT cell lines), where it revealed high promoter activity. Data offered that the 782 bp sequence of ED-L2 promoter has a key role in its activity in vitro. The (ED-L2)-SB100X transposase mediated stable integration of T2-Onc3 in KYSE-30 cells, thereby providing further evidence of the tissue specificity of ED-L2 promoter. The KYSE-30 cells modified with the SB system integrate on average 187 copies of the T2-Onc3 transposon in its genome. In aggregate, the (ED-L2)-SB100X transposase can be efficiently applied for the tissue-specific stable expression of a transgene in human KYSE-30 cells using SB transposon.

Increase in the titer of lentiviral vectors expressing potassium channels by current blockade during viral vector production

Background

High titers of lentiviral vectors are required for the efficient transduction of a gene of interest. During preparation of lentiviral the vectors, the protein of interest is inevitably expressed in the viral vector-producing cells. This expression may affect the production of the lentiviral vector.

Methods

We prepared lentiviral vectors expressing inwardly rectifying potassium channel (Lv-Kir2.1), its dominant-negative form (Lv-Kir-DN), and other K⁺ channels, using the ubiquitously active β-actin and neuron-specific synapsin I promoters.

Results

The titer of Lv-Kir-DN was higher than that of Lv-Kir2.1, suggesting a negative effect of induced K⁺ currents on viral titer. We then blocked Kir2.1 currents with the selective blocker Ba²⁺ during Lv-Kir2.1 production, and obtained about a 5-fold increase in the titer. Higher extracellular K⁺ concentrations increased the titer of Lv-Kir2.1 about 9-fold. With a synapsin I promoter Ba²⁺ increased the titer because of the moderate expression of Kir2.1 channel. Channel blockade also increased the titers of the lentivirus expressing Kv1.4 and TREK channels, but not HERG. The increase in titer correlated with the K⁺ currents generated by the channels expressed.

Conclusion

In the production of lentivirus expressing K⁺ channels, titers are increased by blocking K⁺ currents in the virus-producing cells. This identifies a crucial issue in the production of viruses expressing membrane channels, and should facilitate basic and gene therapeutic research on channelopathies.