ISOLATION OF A CDNA FOR THE CATALYTIC SUBUNIT OF RAT-LIVER GLUCOSE-6-PHOSPHATASE - REGULATION OF GENE-EXPRESSION IN FAO HEPATOMA-CELLS BY INSULIN, DEXAMETHASONE AND CAMP

cDNA clones coding for the catalytic subunit of rat liver glucose-6-ph osphatase (EC 3.1.3.9) were isolated from a rat liver cDNA library in lambda gt(11) phage. The sequence of the cDNA and the amino acid seque nce derived from it were greater than 90% identical to the correspondi ng sequences for the mouse and human forms of liver glucose-6-phosphat ase. Northern blot analysis of RNA from FAO hepatoma cells revealed th at dexamethasone induced the glucose-6-phosphatase mRNA while insulin suppressed its expression. When both hormones were added together insu lin completely suppressed the effect of glucocorticoid. cAMP addition alone decreased the abundance of glucose-6-phosphatase mRNA. The resul ts demonstrate multihormonal regulation of gene expression of hepatic glucose-6-phosphatase and support a dominant role for insulin. (C) 199 4 Academic Press, Inc.