title: Chronic AMPK activation evokes the slow, oxidative myogenic program and triggers beneficial adaptations in mdx mouse skeletal muscle.
abstract: A therapeutic approach for Duchenne muscular dystrophy (DMD) is to up-regulate utrophin in skeletal muscle in an effort to compensate for the lack of dystrophin. We previously hypothesized that promotion of the slow, oxidative myogenic program, which triggers utrophin up-regulation, can attenuate the dystrophic pathology in mdx animals. Since treatment of healthy mice with the AMP-activated protein kinase (AMPK) activator 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR) enhances oxidative capacity and elicits a fast-to-slow fiber-type transition, we evaluated the effects of chronic AMPK stimulation on skeletal muscle phenotype and utrophin expression in mdx mice. Daily AICAR administration (500 mg/kg/day, 30 days) of 5-7-week-old mdx animals induced an elevation in mitochondrial cytochrome c oxidase enzyme activity, an increase in myosin heavy-chain type IIa-positive fibers and slower twitch contraction kinetics in the fast, glycolytic extensor digitorum longus muscle. Utrophin expression was significantly enhanced in response to AICAR, which occurred coincident with an elevated β-dystroglycan expression along the sarcolemma. These adaptations were associated with an increase in sarcolemmal structural integrity under basal conditions, as well as during damaging eccentric contractions ex vivo. Notably, peroxisome proliferator-activated receptor γ co-activator-1α (PGC-1α) and silent information regulator two ortholog 1 protein contents were significantly higher in muscle from mdx mice compared with wild-type littermates and AICAR further increased PGC-1α expression. Our data show that AICAR-evoked muscle plasticity results in beneficial phenotypic adaptations in mdx mice and suggest that the contextually novel application of this compound for muscular dystrophy warrants further study.
authors.affiliation: Department of Cellular and Molecular Medicine, Faculty of Medicine, Centre for Neuromuscular Disease, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Ljubicic
authors.forename: Pedro
authors.initials: P
authors.lastname: Miura
authors.forename: Matthew
authors.initials: M
authors.lastname: Burt
authors.forename: Louise
authors.initials: L
authors.lastname: Boudreault
authors.forename: Shiemaa
authors.initials: S
authors.lastname: Khogali
authors.forename: John A
authors.initials: JA
authors.lastname: Lunde
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Renaud
authors.forename: Bernard J
authors.initials: BJ
authors.lastname: Jasmin
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D002460:Cell Line; D049030:Dystroglycans / Q000235:genetics / Q000378:metabolism; D051379:Mice; D018101:Mice, Inbred mdx; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism*; D047495:PPAR gamma / Q000235:genetics / Q000378:metabolism; D012265:Ribonucleotides / Q000494:pharmacology*; D012508:Sarcolemma / Q000235:genetics / Q000378:metabolism
chemical_list: D047495:PPAR gamma; D012265:Ribonucleotides; D049030:Dystroglycans; D000620:Aminoimidazole Carboxamide; D055372:AMP-Activated Protein Kinases; C031143:AICA ribonucleotide