A RETINOIC ACID RESPONSE ELEMENT IS PART OF A PLEIOTROPIC DOMAIN IN THE PHOSPHOENOLPYRUVATE CARBOXYKINASE GENE

Several hormones, including insulin, glucagon, and glucocorticoids, regulate the expression of the rate-limiting gluconeogenic enzyme, phosphoenolpyruvate carboxykinase [GTP:oxaloacetate carboxy-lyase (transphosphorylating); EC 4.1.1.32; PEPCK] in liver. In this report we demonstrate that retinoic acid (RA) also regulates PEPCK expression by inducing a 3-fold increase in the rate of transcription of the PEPCK gene. A RA response element located between -468 and -431 in the PEPCK promoter mediates a 7-fold increase in expression of a chimeric construct containing the basal PEPCK promoter ligated to the chloramphenicol acetyltransferase reporter gene. This element confers RA responsiveness through the heterologous thymidine kinase promoter and functions relatively independent of position and orientation. An 18-base-pair core sequence (-451 to -434) (i) mediates an effect of RA on PEPCK gene expression and contains motifs found in two other RA response elements; (ii) corresponds to AF1, an accessory factor element that is an integral component of the complex glucocorticoid response unit in the PEPCK gene promoter; (iii) is in a region involved in the development expression of the PEPCK gene; and (iv) shows homology to elements involved in the tissue-specific regulation of genes, including the hepatic apolipoprotein genes and the alpha-1-antitrypsin gene.