Protein Kinase A Phosphorylates Hepatocyte Nuclear Factor-6 and Stimulates Glucose-6-phosphatase Catalytic Subunit Gene Transcription

Autor: James K. Oeser, Ryan S. Streeper, Lauri A. Hornbuckle, Joshua K. Goldman, Christina A. Svitek, Richard M. O'Brien
Rok vydání: 2001
Předmět:
Chloramphenicol O-Acetyltransferase
Time Factors
Transcription
Genetic
Recombinant Fusion Proteins
DNA Mutational Analysis
Molecular Sequence Data
Biology
Transfection
Biochemistry
Gene Expression Regulation
Enzymologic
Fusion gene
Mice
Genes
Reporter
Catalytic Domain
Sequence Homology
Nucleic Acid
Cyclic AMP
Tumor Cells
Cultured
Animals
Humans
Phosphorylation
Promoter Regions
Genetic
Protein kinase A
Molecular Biology
Homeodomain Proteins
Regulation of gene expression
Binding Sites
Expression vector
Base Sequence
Dose-Response Relationship
Drug
Promoter
Cell Biology
Cyclic AMP-Dependent Protein Kinases
Molecular biology
Hepatocyte Nuclear Factor 6
Kinetics
Liver
Acetyltransferase
Mutation
Glucose-6-Phosphatase
Mutagenesis
Site-Directed
Trans-Activators
Signal transduction
Plasmids
Protein Binding
Signal Transduction
Zdroj: Journal of Biological Chemistry. 276:19111-19118
ISSN: 0021-9258
DOI: 10.1074/jbc.m101442200
Popis: Glucose-6-phosphatase is a multicomponent system that catalyzes the terminal step in gluconeogenesis. To examine the effect of the cAMP signal transduction pathway on expression of the gene encoding the mouse glucose-6-phosphatase catalytic subunit (G6Pase), the liver-derived HepG2 cell line was transiently co-transfected with a series of G6Pase-chloramphenicol acetyltransferase fusion genes and an expression vector encoding the catalytic subunit of cAMP-dependent protein kinase A (PKA). PKA markedly stimulated G6Pase-chloramphenicol acetyltransferase fusion gene expression, and mutational analysis of the G6Pase promoter revealed that multiple cis-acting elements were required for this response. One of these elements was mapped to the G6Pase promoter region between -114 and -99, and this sequence was shown to bind hepatocyte nuclear factor (HNF)-6. This HNF-6 binding site was able to confer a stimulatory effect of PKA on the expression of a heterologous fusion gene; a mutation that abolished HNF-6 binding also abolished the stimulatory effect of PKA. Further investigation revealed that PKA phosphorylated HNF-6 in vitro. Site-directed mutation of three consensus PKA phosphorylation sites in the HNF-6 carboxyl terminus markedly reduced this phosphorylation. These results suggest that the stimulatory effect of PKA on G6Pase fusion gene transcription in HepG2 cells may be mediated in part by the phosphorylation of HNF-6.
Databáze: OpenAIRE
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