Cyclic AMP-mediated inhibition of transcription of the malic enzyme gene in chick embryo hepatocytes in culture. Characterization of a cis-acting element far upstream of the promoter

• Published in: The Journal of biological chemistry 1997-09, Vol.272 (38), p.23606-23615
• Main Authors: Mounier, C. (McGill University, Montreal, PQ, Canada.), Chen, W, Klautky, S.A, Goodridge, A.G
• Format: Article
• Language: English
• Subjects: ACILTRANSFERASA; ACYLTRANSFERASE; ACYLTRANSFERASES; ADN; ADN RECOMBINADO; ADN RECOMBINE; AMP; Animals; BINDING PROTEINS; CAMP RESPONSE ELEMENT; CELLS; Cells, Cultured; CELLULE; CELULAS; Chick Embryo; CHICKS; CHLORAMPHENICOL ACETYLTRANSFERASE; Cyclic AMP - physiology; DNA; EXPRESION GENICA; EXPRESSION DES GENES; FACTEUR DE TRANSCRIPTION; FACTORES DE TRANSCRIPCION; FOIE; GENE; GENE EXPRESSION; GENES; GENETIC REGULATION; GENETICA; GENETICS; GENETIQUE; HIGADO; INHIBICION; INHIBITION; LIVER; Malate Dehydrogenase - genetics; Nuclear Proteins - metabolism; NUCLEOTIDE SEQUENCE; OXIDOREDUCTASES; OXIDORREDUCTASAS; OXYDOREDUCTASE; POLLITO; POUSSIN; Promoter Regions, Genetic; Protein Binding; PROTEIN KINASE; PROTEINA QUINASA; PROTEINAS AGLUTINANTES; PROTEINE DE LIAISON; PROTEINE KINASE; RECOMBINANT DNA; REGULATORY SEQUENCES; REPORTER GENES; SECUENCIA NUCLEOTIDICA; SEQUENCE NUCLEOTIDIQUE; TRANSCRIPCION; TRANSCRIPTION; Transcription Factor AP-1 - metabolism; TRANSCRIPTION FACTORS; Transcription, Genetic - physiology; Triiodothyronine - physiology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.272.38.23606

Glucagon, acting via cAMP, inhibits transcription of the malic enzyme gene in chick embryo hepatocytes. In transiently transfected hepatocytes, fragments from the 5'-flanking DNA of the malic enzyme gene confer cAMP responsiveness to linked reporter genes. The major inhibitory cAMP response element at -3180/-3174 base pairs (bp) is similar to the consensus binding site for AP1. DNA fragments from -3134/-3115, -1713/-944, and -413/-147 bp also contain inhibitory cAMP response elements. The negative action of cAMP is mimicked by overexpression of the catalytic subunit of protein kinase A, inhibited by overexpression of a specific inhibitor of protein kinase A, and inhibited by overexpression of the T3 receptor; these results indicate involvement of the classical eukaryotic pathway for cAMP action and suggest interaction between the T3 and cAMP pathways. Sequence-specific complexes form between nuclear proteins and a DNA fragment containing -3192/-3158 bp of 5'-flanking DNA. In nuclear extracts prepared from cells treated with chlorophenylthio-cyclic AMP and T3, the complexes have different masses than those formed with extracts from cells treated with T3 alone. Antibodies to c-Fos or ATF-2 inhibit formation of the complex formed by proteins from cells treated with chlorophenylthio-cyclic AMP and T3 but not by those from cells treated with T3 alone. These results suggest an important role for c-Fos and ATF-2 in glucagon-mediated inhibition of transcription of the malic enzyme gene.