Visualization and evaluation of the promoter activities of genes for stress-inducible proteins in response to environmental pollutants

We examined the systematic assay of the reporter gene for the assessment of heavy metals and organic chemical pollutants using the reporter plasmids carrying stress-responsive elements fused to the green fluorescence protein (GFP) gene as follows: metallothionein (MTIIA), heme oxigenase-1 (HO-1), quinone reductase (ARE), and c-fos genes. The treatment of COS7 cells in which the c-fos gene promoter-, ARE-, or HO-1 enhancer-fused GFP with a low concentration of NaAsO² was introduced led to the detection of the fluorescent cells, and an agrichemical paraquat enhanced the fluorescence of ARE or HO-1 enhancer-transfected cells. The cells in which the plasmid carrying the MT-IIA gene promoter (the -765 bp upstream from the transcription initiation site) was introduced highly expressed GFP on treatment with CdCl², ZnSO ⁴, or CuCl². The plasmid carrying seven metal-responsive elements of the MT-IIA gene increased the response of the fluorescence intensity to these heavy metals. These results indicated that the use of the gene promoters and enhancers of the stress-responsive genesfused to GFP contributes to the visualization of pollutantresponsive mammalian cells and can be applied to biomonitoring of environmental pollution.