Negative cyclic AMP response elements in the promoter of the L-type pyruvate kinase gene

L-type pyruvate kinase gene expression is modulated by hormonal and nutriti onal conditions. Here, we show by transient transfections in hepatocytes in primary culture that both the glucose response element and the contiguous hepatocyte nuclear factor 4 (HNF4) binding site (L3) of the promoter were n egative cyclic A;MP (cAMP) response elements and that cAMP-dependent inhibi tion through L3 requires HNF4 binding. Another HNF4 binding site-dependent construct was also inhibited by cAMP. However, HNF4 mutants whose putative PKA-dependent phosphorylation sites have been mutated still conferred cAMP- sensitive transactivation of a L3-dependent reporter gene. Overexpression o f the CREB binding protein (CBP) increased the HNF4-dependent transactivati on but this effect remained sensitive to cAMP inhibition. (C) 1999 Federati on of European Biochemical Societies.