ACTIVATION OF PROTEIN PHOSPHATASE 1-ALPHA PROMOTER IN ASCITES HEPATOMA-CELLS

We have already reported the nucleotide sequence of 5'-flanking region of rat PP1 alpha gene and identified the promoter region in NIH3T3 ce lls. Here we determined the promoter activity of PP1 alpha gene in asc ites hepatoma cells and compared with that of hepatocytes. Reporter an alysis showed that the promoter activity was enhanced in an ascites he patoma AH13 compared with normal hepatocytes at two regions, -37 to -1 98 bp and -492 to -848 bp upstream of the translation start site. At - 37 to -198 bp region with high GC content, binding of Spl was markedly increased in all of five ascites hepatomas examined. At -492 to -848 bp region, two bands were clearly detected in two of the five ascites hepatomas, AH13 and AH7974F, by gel shift analysis. These results stro ngly suggest that the increase in PP1 alpha mRNA expression in ascites hepatomas is at least in part due to the enhanced promoter activity o f PP1 alpha gene.