C/EBP alpha is a major activator for the transcription of rat Cu/Zn superoxide dismutase gene in liver cell.

The rat Cu/Zn superoxide dismutase (SOD1) is expressed in all tissues. Sequence analysis of the SOD1 promoter region showed that none of the cis-elements of hepatocyte-specific nuclear factors (HNF) were observed. The cis-element of C/EBP alpha in the proximal region of the SOD1 promoter and the high level of C/EBP alpha in the liver tissue led us to focus on the transcriptional regulation of the SOD1 gene by C/EBP alpha. Cotransfection assays with the plasmid expressing transcription factor C/EBP alpha showed that C/EBP alpha transactivated SOD1 gene by 27 fold. The marked transactivation and direct binding of C/EBP alpha to the SOD1 promoter were confirmed by deletion analyses and mobility shift assays. These results suggested that C/EBP alpha plays a major role in the tissue distribution of SOD1.