title: Proteasome inhibition in skeletal muscle cells unmasks metabolic derangements in type 2 diabetes.
abstract: Two-dimensional difference gel electrophoresis (2-D DIGE)-based proteome analysis has revealed intrinsic insulin resistance in myotubes derived from type 2 diabetic patients. Using 2-D DIGE-based proteome analysis, we identified a subset of insulin-resistant proteins involved in protein turnover in skeletal muscle of type 2 diabetic patients, suggesting aberrant regulation of the protein homeostasis maintenance system underlying metabolic disease. We then validated the role of the ubiquitin-proteasome system (UPS) in myotubes to investigate whether impaired proteasome function may lead to metabolic arrest or insulin resistance. Myotubes derived from muscle biopsies obtained from people with normal glucose tolerance (NGT) or type 2 diabetes were exposed to the proteasome inhibitor bortezomib (BZ; Velcade) without or with insulin. BZ exposure increased protein carbonylation and lactate production yet impaired protein synthesis and UPS function in myotubes from type 2 diabetic patients, marking the existence of an insulin-resistant signature that was retained in cultured myotubes. In conclusion, BZ treatment further exacerbates insulin resistance and unmasks intrinsic features of metabolic disease in myotubes derived from type 2 diabetic patients. Our results highlight the existence of a confounding inherent abnormality in cellular protein dynamics in metabolic disease, which is uncovered through concurrent inhibition of the proteasome system.
authors.affiliation: Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden;
authors.forename: Lubna
authors.initials: L
authors.lastname: Al-Khalili
authors.affiliation: Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden;
authors.forename: Thais
authors.initials: T
authors.lastname: de Castro Barbosa
authors.affiliation: AstraZeneca Research and Development, Mölndal, Sweden; and.
authors.forename: Jörgen
authors.initials: J
authors.lastname: Ostling
authors.affiliation: Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden;
authors.forename: Julie
authors.initials: J
authors.lastname: Massart
authors.affiliation: Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden; Department of Functional Biology, Physiology Area, University of Oviedo, Oviedo, Spain.
authors.forename: Pablo Garrido
authors.initials: PG
authors.lastname: Cuesta
authors.affiliation: Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden;
authors.forename: Megan E
authors.initials: ME
authors.lastname: Osler
authors.affiliation: Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden;
authors.forename: Mutsumi
authors.initials: M
authors.lastname: Katayama
authors.affiliation: AstraZeneca Research and Development, Mölndal, Sweden; and.
authors.forename: Ann-Christin
authors.initials: AC
authors.lastname: Nyström
authors.affiliation: AstraZeneca Research and Development, Mölndal, Sweden; and.
authors.forename: Jan
authors.initials: J
authors.lastname: Oscarsson
authors.affiliation: Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden; Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; Juleen.Zierath@ki.se.
authors.forename: Juleen R
authors.initials: JR
authors.lastname: Zierath
mesh_terms: D001897:Boronic Acids / Q000494:pharmacology; D000069286:Bortezomib; D002478:Cells, Cultured; D003924:Diabetes Mellitus, Type 2 / Q000201:enzymology / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism; D006003:Glycogen / Q000096:biosynthesis; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D007333:Insulin Resistance; D050356:Lipid Metabolism / Q000187:drug effects; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D061988:Proteasome Inhibitors / Q000494:pharmacology; D050050:Protein Carbonylation / Q000187:drug effects; D020543:Proteome / Q000378:metabolism; D011719:Pyrazines / Q000494:pharmacology; D034622:RNA Interference; D015398:Signal Transduction
chemical_list: D001897:Boronic Acids; D004791:Enzyme Inhibitors; D007328:Insulin; D061988:Proteasome Inhibitors; D020543:Proteome; D011719:Pyrazines; D000069286:Bortezomib; D006003:Glycogen; D046988:Proteasome Endopeptidase Complex; D005947:Glucose
keywords: 2-D DIGE; Velcade; bortezomib; carbonylation; glucose incorporation into glycogen; myotubes; palmitate oxidation; proteasome; protein synthesis; ubiquitin