Stimulation of AMP-activated protein kinase is essential for the induction of drug metabolizing enzymes by phenobarbital in human and mouse liver.
Our previous studies have suggested a role for AMP-activated protein kinase (AMPK) in the induction of CYP2B6 by phenobarbital (PB) in hepatoma-derived cells (Rencurel et al., 2005). In this study, we showed in primary human hepatocytes that: 1) 5'-phosphoribosyl-5-aminoimidazol-4-carboxamide 1-beta-d-ribofuranoside and the biguanide metformin, known activators of AMPK, dose-dependently increase the expression of CYP2B6 and CYP3A4 to an extent similar to that of PB. 2) PB, but not the human nuclear receptor constitutive active/androstane receptor (CAR) ligand 6-(4-chlorophenyl)imidazol[2,1-6][1,3]thiazole-5-carbaldehyde, dose-dependently increase AMPK activity. 3) Pharmacological inhibition of AMPK activity with compound C or dominant-negative forms of AMPK blunt the inductive response to phenobarbital. Furthermore, in transgenic mice with a liver-specific deletion of both the alpha1 and alpha2 AMPK catalytic subunits, basal levels of Cyp2b10 and Cyp3a11 mRNA were increased but not in primary culture of mouse hepatocytes. However, phenobarbital or 1,4 bis[2-(3,5-dichloropyridyloxy)]benzene, a mouse CAR ligand, failed to induce the expression of these genes in the liver or cultured hepatocytes from mice lacking hepatic expression of the alpha1 and alpha2 subunits of AMPK. The distribution of CAR between the nucleus and cytosol was not altered in hepatocytes from mice lacking both AMPK catalytic subunits. These data highlight the essential role of AMPK in the CAR-mediated signal transduction pathway.
Rencurel
Franck
F
Division of Pharmacology-Neurobiology of the Biozentrum, University of Basel, Basel, Switzerland. franck.rencurel@unibas.ch
Foretz
Marc
M
Kaufmann
Michel R
MR
Stroka
Deborah
D
Looser
Renate
R
Leclerc
Isabelle
I
da Silva Xavier
Gabriela
G
Rutter
Guy A
GA
Viollet
Benoit
B
Meyer
Urs A
UA
D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D017931:DNA Primers; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D004790:Enzyme Induction; D022781:Hepatocytes / Q000187:drug effects* / Q000201:enzymology; D006801:Humans; D007150:Immunohistochemistry; D008687:Metformin / Q000494:pharmacology; D051379:Mice; D009097:Multienzyme Complexes / Q000378:metabolism*; D010634:Phenobarbital / Q000494:pharmacology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D012265:Ribonucleotides / Q000494:pharmacology
D017931:DNA Primers; D009097:Multienzyme Complexes; D012265:Ribonucleotides; D000620:Aminoimidazole Carboxamide; D000255:Adenosine Triphosphate; D008687:Metformin; C534978:Prkaa2 protein, mouse; C526181:PRKAA2 protein, human; D017346:Protein Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases; C526180:PRKAA1 protein, human; C031143:AICA ribonucleotide; D010634:Phenobarbital