Positive and negative regulatory elements in the upstream region of the rat Cu/Zn superoxide dismutase gene

Cu/Zn-superoxide dismutase (SOD1) catalyses the dismutation of superoxide r adicals and neutralizes the oxidative effects of Various chemicals. Deletio n analysis of the upstream region of the rat SOD1 gene revealed that the pr omoter contains a positive regulatory element (PRE) and a negative regulato ry element (NRE), which encompass the regions from -576 to -412 and from -4 12 to -305 respectively from the site of initiation of transcription. These DNA elements showed enhancer and silencer activities respectively in the n atural context and in a heterologous promoter system. Using an electrophore tic-mobility-shift assay and a supershift assay with a specific antibody, t he cis-elements of the PRE and NRE were identified as binding sites for tra nscription factors Elk1 and YY1 (Ying-Yang 1) respectively. Consistent with the presumed roles of the PRE and NRE, Elk I increased SOD1 gene transcrip tion about 4-5-fold, whereas YY1 exerted a negative effect of about 6-fold. Mutations of the Elk1- and YY1-binding sites led to diminution and elevati on respectively of transcriptional activities, both in the natural context and in heterologous promoter systems. These results suggest that the transc ription factors Elk1 and YY1, binding in the PRE and NRE respectively, co-o rdinate the expression of the SOD1 gene.