title: Glycogen debranching enzyme association with beta-subunit regulates AMP-activated protein kinase activity.
abstract: AMP-activated protein kinase (AMPK) regulates both glycogen and lipid metabolism functioning as an intracellular energy sensor. In this study, we identified a 160-kDa protein in mouse skeletal muscle lysate by using a glutathione-S-transferase (GST)-AMPK fusion protein pull-down assay. Mass spectrometry and a Mascot search revealed this protein to be a glycogen debranching enzyme (GDE). The association between AMPK and GDE was observed not only in the overexpression system but also endogenously. Next, we showed the beta1-subunit of AMPK to be responsible for the association with GDE. Furthermore, experiments using deletion mutants of the beta1-subunit of AMPK revealed amino acids 68-123 of the beta1-subunit to be sufficient for GDE binding. W100G and K128Q, both beta1-subunit mutants, are reportedly incapable of binding to glycogen, but both bound GDE, indicating that the association between AMPK and GDE does not involve glycogen. Rather, the AMPK-GDE association is likely to be direct. Overexpression of amino acids 68-123 of the beta1-subunit inhibited the association between endogenous AMPK and GDE. Although GDE activity was unaffected, basal phosphorylation and kinase activity of AMPK, as well as phosphorylation of acetyl-CoA carboxylase, were significantly increased. Thus it is likely that the AMPK-GDE association is a novel mechanism regulating AMPK activity and the resultant fatty acid oxidation and glucose uptake.
authors.affiliation: Department of Internal Medicine, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Sakoda
authors.forename: Midori
authors.initials: M
authors.lastname: Fujishiro
authors.forename: Junko
authors.initials: J
authors.lastname: Fujio
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Shojima
authors.forename: Takehide
authors.initials: T
authors.lastname: Ogihara
authors.forename: Akifumi
authors.initials: A
authors.lastname: Kushiyama
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Fukushima
authors.forename: Motonobu
authors.initials: M
authors.lastname: Anai
authors.forename: Hiraku
authors.initials: H
authors.lastname: Ono
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Kikuchi
authors.forename: Nanao
authors.initials: N
authors.lastname: Horike
authors.forename: Amelia Y I
authors.initials: AY
authors.lastname: Viana
authors.forename: Yasunobu
authors.initials: Y
authors.lastname: Uchijima
authors.forename: Hiroki
authors.initials: H
authors.lastname: Kurihara
authors.forename: Tomoichiro
authors.initials: T
authors.lastname: Asano
mesh_terms: D055372:AMP-Activated Protein Kinases; D000818:Animals; D000906:Antibodies; D019556:COS Cells; D002522:Chlorocebus aethiops; D004789:Enzyme Activation / Q000502:physiology; D005982:Glutathione Transferase / Q000235:genetics; D006003:Glycogen / Q000378:metabolism; D006004:Glycogen Debranching Enzyme System / Q000378:metabolism*; D006801:Humans; D007668:Kidney / Q000166:cytology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009097:Multienzyme Complexes; D011485:Protein Binding / Q000502:physiology; D011494:Protein Kinases / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D021122:Protein Subunits / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D011817:Rabbits; D051381:Rats; D017207:Rats, Sprague-Dawley; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000906:Antibodies; D006004:Glycogen Debranching Enzyme System; D009097:Multienzyme Complexes; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins; D006003:Glycogen; D005982:Glutathione Transferase; D011494:Protein Kinases; C526182:PRKAB1 protein, human; D017346:Protein Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases