Isolated human Fos promoter in plasmid DNA is overactive

Changes in intracellular concentrations of Na + and K + are shown to alter Fos gene expression. Here, we obtained a genetic construct encoding TurboGFP-dest1 gene under control of the human Fos promoter (−549; +155) and studied its expression in HEK293T. Amplification of the Fos promoter sequence from genomic DNA was only efficient in the presence of Li + ions. Ouabain and medium with replacement of Na + with Li + ions resulted in the accumulation of Na + and Li + in cells, respectively. These stimuli increased the mRNA level of endogenous Fos and the average fluorescence intensity of TurboGFP-dest1 in transfected cells. The mRNA level of TurboGFP-dest1 was extremely higher than the mRNA level of endogenous Fos and was little affected by the stimuli.