Identification of elements involved in the transcription control of human CAP43/NDRG1 promoter

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Human CAP43/NDRG1 gene has been shown to be involved in cell differentiation, metastasis, and myelin sheath synthesis. The transactivation of this gene correlates with various stimuli, such as hypoxia, nickel, cobolt, okadiac acid and calcium elevations. To identify cis elements involved in the transcription control of the gene, DNase I hypersensitive site mapping was conducted and the activity of the promoter region in luciferase reporter assay were studied. Two nuclease sensitive sites were revealed: one located at the core promoter region of the CAP43 gene. Reporter assays showed an early growth response gene 1 (Egr1) binding site was involved in the transactivation of the promoter construct by okadaic acid. Further electrophoretic mobility shift assay and supershift assay showed Erg1 formed a complex with this element. The other nuclease sensitive site was located in the first intron and behaved as a repressive element. Removal of this element resulted in a decrease in the basal activity of the promoter construct and partial loss of the transactivation by okadaic acid. A protein-DNA complex formed with this intron element; this complex decreased in VHL deficient O-786 cells and reintroduction of the wild type VHL could restore the presence of the complex. (Supported by grant numbers ES00260, ES10344, and T32-ES07324 from National Institute of Environmental Health Sciences, CA16087 from the National Cancer Institute.)