title: AMP-activated protein kinase phosphorylates and inactivates liver glycogen synthase.
abstract: Recombinant muscle GYS1 (glycogen synthase 1) and recombinant liver GYS2 were phosphorylated by recombinant AMPK (AMP-activated protein kinase) in a time-dependent manner and to a similar stoichiometry. The phosphorylation site in GYS2 was identified as Ser7, which lies in a favourable consensus for phosphorylation by AMPK. Phosphorylation of GYS1 or GYS2 by AMPK led to enzyme inactivation by decreasing the affinity for both UDP-Glc (UDP-glucose) [assayed in the absence of Glc-6-P (glucose-6-phosphate)] and Glc-6-P (assayed at low UDP-Glc concentrations). Incubation of freshly isolated rat hepatocytes with the pharmacological AMPK activators AICA riboside (5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside) or A769662 led to persistent GYS inactivation and Ser7 phosphorylation, whereas inactivation by glucagon treatment was transient. In hepatocytes from mice harbouring a liver-specific deletion of the AMPK catalytic α1/α2 subunits, GYS2 inactivation by AICA riboside and A769662 was blunted, whereas inactivation by glucagon was unaffected. The results suggest that GYS inactivation by AMPK activators in hepatocytes is due to GYS2 Ser7 phosphorylation.
authors.affiliation: de Duve Institute, Université catholique de Louvain, Avenue Hippocrate 75, bte B1.74.02, B-1200 Brussels, Belgium.
authors.forename: Laurent
authors.initials: L
authors.lastname: Bultot
authors.forename: Bruno
authors.initials: B
authors.lastname: Guigas
authors.forename: Alexander
authors.initials: A
authors.lastname: Von Wilamowitz-Moellendorff
authors.forename: Liliane
authors.initials: L
authors.lastname: Maisin
authors.forename: Didier
authors.initials: D
authors.lastname: Vertommen
authors.forename: Nusrat
authors.initials: N
authors.lastname: Hussain
authors.forename: Monique
authors.initials: M
authors.lastname: Beullens
authors.forename: Joan J
authors.initials: JJ
authors.lastname: Guinovart
authors.forename: Marc
authors.initials: M
authors.lastname: Foretz
authors.forename: Benoît
authors.initials: B
authors.lastname: Viollet
authors.forename: Kei
authors.initials: K
authors.lastname: Sakamoto
authors.forename: Louis
authors.initials: L
authors.lastname: Hue
authors.forename: Mark H
authors.initials: MH
authors.lastname: Rider
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000737:chemistry / Q000378:metabolism*; D000595:Amino Acid Sequence; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D020240:Apraxia, Ideomotor; D001713:Biphenyl Compounds; D002478:Cells, Cultured; D016384:Consensus Sequence; D017868:Cyclic AMP-Dependent Protein Kinases / Q000737:chemistry; D004789:Enzyme Activation / Q000187:drug effects; D020536:Enzyme Activators / Q000494:pharmacology; D006006:Glycogen Synthase / Q000737:chemistry / Q000378:metabolism*; D022781:Hepatocytes / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D006801:Humans; D008099:Liver / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D011753:Pyrones / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012265:Ribonucleotides / Q000494:pharmacology; D013876:Thiophenes / Q000494:pharmacology
chemical_list: D001713:Biphenyl Compounds; D020536:Enzyme Activators; D011753:Pyrones; D012265:Ribonucleotides; D013876:Thiophenes; D000620:Aminoimidazole Carboxamide; D006006:Glycogen Synthase; D017868:Cyclic AMP-Dependent Protein Kinases; D055372:AMP-Activated Protein Kinases; C031143:AICA ribonucleotide; C512408:4-hydroxy-3-(4-(2-hydroxyphenyl)phenyl)-6-oxo-7H-thieno(2,3-b)pyridine-5-carbonitrile