title: AMPK antagonizes hepatic glucagon-stimulated cyclic AMP signalling via phosphorylation-induced activation of cyclic nucleotide phosphodiesterase 4B.
abstract: Biguanides such as metformin have previously been shown to antagonize hepatic glucagon-stimulated cyclic AMP (cAMP) signalling independently of AMP-activated protein kinase (AMPK) via direct inhibition of adenylate cyclase by AMP. Here we show that incubation of hepatocytes with the small-molecule AMPK activator 991 decreases glucagon-stimulated cAMP accumulation, cAMP-dependent protein kinase (PKA) activity and downstream PKA target phosphorylation. Moreover, incubation of hepatocytes with 991 increases the Vmax of cyclic nucleotide phosphodiesterase 4B (PDE4B) without affecting intracellular adenine nucleotide concentrations. The effects of 991 to decrease glucagon-stimulated cAMP concentrations and activate PDE4B are lost in hepatocytes deleted for both catalytic subunits of AMPK. PDE4B is phosphorylated by AMPK at three sites, and by site-directed mutagenesis, Ser304 phosphorylation is important for activation. In conclusion, we provide a new mechanism by which AMPK antagonizes hepatic glucagon signalling via phosphorylation-induced PDE4B activation.
authors.affiliation: Université catholique de Louvain and de Duve Institute, Avenue Hippocrate, 75, 1200 Brussels, Belgium.
authors.forename: M
authors.initials: M
authors.lastname: Johanns
authors.affiliation: Université catholique de Louvain and de Duve Institute, Avenue Hippocrate, 75, 1200 Brussels, Belgium.
authors.forename: Y-C
authors.initials: YC
authors.lastname: Lai
authors.affiliation: Université catholique de Louvain and de Duve Institute, Avenue Hippocrate, 75, 1200 Brussels, Belgium.
authors.forename: M-F
authors.initials: MF
authors.lastname: Hsu
authors.affiliation: Université catholique de Louvain and de Duve Institute, Avenue Hippocrate, 75, 1200 Brussels, Belgium.
authors.forename: R
authors.initials: R
authors.lastname: Jacobs
authors.affiliation: Université catholique de Louvain and de Duve Institute, Avenue Hippocrate, 75, 1200 Brussels, Belgium.
authors.forename: D
authors.initials: D
authors.lastname: Vertommen
authors.affiliation: Faculté de Médecine, Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire (IRIBHM), Université Libre de Bruxelles (ULB), Route de Lennik, 808, 1070 Brussels, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Van Sande
authors.affiliation: Faculté de Médecine, Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire (IRIBHM), Université Libre de Bruxelles (ULB), Route de Lennik, 808, 1070 Brussels, Belgium.
authors.forename: J E
authors.initials: JE
authors.lastname: Dumont
authors.affiliation: Cellular Stress Group, MRC Clinical Sciences Centre, Imperial College London, Hammersmith Hospital, DuCane Road, London W12 0NN, UK.
authors.forename: A
authors.initials: A
authors.lastname: Woods
authors.affiliation: Cellular Stress Group, MRC Clinical Sciences Centre, Imperial College London, Hammersmith Hospital, DuCane Road, London W12 0NN, UK.
authors.forename: D
authors.initials: D
authors.lastname: Carling
authors.affiliation: Université catholique de Louvain and de Duve Institute, Avenue Hippocrate, 75, 1200 Brussels, Belgium.
authors.forename: L
authors.initials: L
authors.lastname: Hue
authors.affiliation: INSERM U1016, Institut Cochin, 75014 Paris, France.|CNRS UMR8104, 75014 Paris, France.|Université Paris Descartes, Sorbonne Paris Cité, 75014 Paris, France.
authors.forename: B
authors.identifier: http://orcid.org/0000-0002-0121-0224
authors.initials: B
authors.lastname: Viollet
authors.affiliation: INSERM U1016, Institut Cochin, 75014 Paris, France.|CNRS UMR8104, 75014 Paris, France.|Université Paris Descartes, Sorbonne Paris Cité, 75014 Paris, France.
authors.forename: M
authors.initials: M
authors.lastname: Foretz
authors.affiliation: Université catholique de Louvain and de Duve Institute, Avenue Hippocrate, 75, 1200 Brussels, Belgium.
authors.forename: M H
authors.initials: MH
authors.lastname: Rider
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D020816:Amino Acid Motifs; D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism*; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D020536:Enzyme Activators / Q000378:metabolism; D005934:Glucagon / Q000378:metabolism*; D022781:Hepatocytes / Q000201:enzymology* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010766:Phosphorylation; D015398:Signal Transduction
chemical_list: D020536:Enzyme Activators; D005934:Glucagon; D000242:Cyclic AMP; D055372:AMP-Activated Protein Kinases; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; C543000:PDE4B protein, mouse