Regulation of hepatic 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase gene expression by glucagon.
The control of hepatic 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase gene expression by glucagon was studied. Intraperitoneal administration of glucagon rapidly decreased the fructose 2,6-bisphosphate content by phosphorylation of 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase and diminution of its Vmax. Immunologic studies using a specific liver antibody showed that the amount of enzyme rapidly decreased. Northern blot analysis showed that the isozyme expressed is the adult liver form. The 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase mRNA content decreased, whereas that of phosphoenolpyruvate carboxykinase increased, and that of albumin did not change. Run-on transcription assays with isolated nuclei showed inhibition in the relative transcription rate of the 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase gene and a stimulation of phosphoenolpyruvate carboxykinase gene. The regulation of mRNA stability of 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase by glucagon was also studied. The half-life of mRNA decreased in the presence of glucagon, suggesting that proteins modulated by a glucagon-dependent process are regulating its stability. The time course of mRNA levels correlated with the transcription inhibition of gene and destabilization of mRNA, indicating that glucagon modulates 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase gene expression at both transcriptional and posttranscriptional levels.
Rosa
J L
JL
Departament de Ciències Fisiològiques Humanes i de la Nutrició, Universitat de Barcelona, Hospitalet de Llobregat, Spain.
Ventura
F
F
Tauler
A
A
Bartrons
R
R
D000595:Amino Acid Sequence; D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D005934:Glucagon / Q000494:pharmacology*; D015151:Immunoblotting; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000138:chemical synthesis / Q000276:immunology; D025481:Phosphofructokinase-2; D010744:Phosphoric Monoester Hydrolases / Q000096:biosynthesis* / Q000235:genetics; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D014158:Transcription, Genetic / Q000187:drug effects
D009842:Oligopeptides; D012333:RNA, Messenger; D005934:Glucagon; D003513:Cycloheximide; D017853:Phosphotransferases (Alcohol Group Acceptor); D025481:Phosphofructokinase-2; D010744:Phosphoric Monoester Hydrolases