title: Nitric Oxide Regulates Skeletal Muscle Fatigue, Fiber Type, Microtubule Organization, and Mitochondrial ATP Synthesis Efficiency Through cGMP-Dependent Mechanisms.
abstract: Skeletal muscle nitric oxide-cyclic guanosine monophosphate (NO-cGMP) pathways are impaired in Duchenne and Becker muscular dystrophy partly because of reduced nNOSμ and soluble guanylate cyclase (GC) activity. However, GC function and the consequences of reduced GC activity in skeletal muscle are unknown. In this study, we explore the functions of GC and NO-cGMP signaling in skeletal muscle.
  
  
  
  GC1, but not GC2, expression was higher in oxidative than glycolytic muscles. GC1 was found in a complex with nNOSμ and targeted to nNOS compartments at the Golgi complex and neuromuscular junction. Baseline GC activity and GC agonist responsiveness was reduced in the absence of nNOS. Structural analyses revealed aberrant microtubule directionality in GC1-/-muscle. Functional analyses of GC1-/-muscles revealed reduced fatigue resistance and postexercise force recovery that were not due to shifts in type IIA-IIX fiber balance. Force deficits in GC1-/-muscles were also not driven by defects in resting mitochondrial adenosine triphosphate (ATP) synthesis. However, increasing muscle cGMP with sildenafil decreased ATP synthesis efficiency and capacity, without impacting mitochondrial content or ultrastructure.
  
  
  
  GC may represent a new target for alleviating muscle fatigue and that NO-cGMP signaling may play important roles in muscle structure, contractility, and bioenergetics.
  
  
  
  These findings suggest that GC activity is nNOS dependent and that muscle-specific control of GC expression and differential GC targeting may facilitate NO-cGMP signaling diversity. They suggest that nNOS regulates muscle fiber type, microtubule organization, fatigability, and postexercise force recovery partly through GC1 and suggest that NO-cGMP pathways may modulate mitochondrial ATP synthesis efficiency. Antioxid. Redox Signal. 26, 966-985.
authors.affiliation: 1 Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine , Miami, Florida.
authors.forename: Younghye
authors.initials: Y
authors.lastname: Moon
authors.affiliation: 1 Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine , Miami, Florida.
authors.forename: Jordan E
authors.initials: JE
authors.lastname: Balke
authors.affiliation: 1 Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine , Miami, Florida.
authors.forename: Derik
authors.initials: D
authors.lastname: Madorma
authors.affiliation: 2 Department of Bioengineering, University of Washington , Seattle, Washington.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Siegel
authors.affiliation: 2 Department of Bioengineering, University of Washington , Seattle, Washington.
authors.forename: Gary
authors.initials: G
authors.lastname: Knowels
authors.affiliation: 3 Department for Molecular Biomedical Research and Biomedical Molecular Biology, Ghent University , Ghent, Belgium .
authors.forename: Peter
authors.initials: P
authors.lastname: Brouckaert
authors.affiliation: 4 Department of Anesthesia, Critical Care and Pain Medicine, Anesthesia Center for Critical Care Research , Massachusetts General Hospital, Boston, Massachusetts.
authors.forename: Emmanuel S
authors.initials: ES
authors.lastname: Buys
authors.affiliation: 2 Department of Bioengineering, University of Washington , Seattle, Washington.|5 Department of Radiology, University of Washington , Seattle, Washington.
authors.forename: David J
authors.initials: DJ
authors.lastname: Marcinek
authors.affiliation: 1 Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine , Miami, Florida.
authors.forename: Justin M
authors.initials: JM
authors.lastname: Percival
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D006152:Cyclic GMP / Q000378:metabolism*; D005786:Gene Expression Regulation; D006162:Guanylate Cyclase / Q000378:metabolism; D006801:Humans; D051379:Mice; D008870:Microtubules / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism; D018763:Muscle Fatigue; D018482:Muscle, Skeletal / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I / Q000235:genetics*
chemical_list: D009569:Nitric Oxide; D000255:Adenosine Triphosphate; D052248:Nitric Oxide Synthase Type I; C496321:Nos1 protein, mouse; D006162:Guanylate Cyclase; D006152:Cyclic GMP
keywords: PDE5; fatigue; microtubules; mitochondria; nNOS; soluble guanylate cyclase