title: Nitroxyl-mediated disulfide bond formation between cardiac myofilament cysteines enhances contractile function.
abstract: BACKGROUND
  In the myocardium, redox/cysteine modification of proteins regulating Ca(2+) cycling can affect contraction and may have therapeutic value. Nitroxyl (HNO), the one-electron-reduced form of nitric oxide, enhances cardiac function in a manner that suggests reversible cysteine modifications of the contractile machinery.
  
  
  OBJECTIVE
  To determine the effects of HNO modification in cardiac myofilament proteins.
  
  
  RESULTS
  The HNO-donor, 1-nitrosocyclohexyl acetate, was found to act directly on the myofilament proteins, increasing maximum force (F(max)) and reducing the concentration of Ca(2+) for 50% activation (Ca(50)) in intact and skinned cardiac muscles. The effects of 1-nitrosocyclohexyl acetate are reversible by reducing agents and distinct from those of another HNO donor, Angeli salt, which was previously reported to increase F(max) without affecting Ca50. Using a new mass spectrometry capture technique based on the biotin switch assay, we identified and characterized the formation by HNO of a disulfide-linked actin-tropomyosin and myosin heavy chain-myosin light chain 1. Comparison of the 1-nitrosocyclohexyl acetate and Angeli salt effects with the modifications induced by each donor indicated the actin-tropomyosin and myosin heavy chain-myosin light chain 1 interactions independently correlated with increased Ca(2+) sensitivity and force generation, respectively.
  
  
  CONCLUSIONS
  HNO exerts a direct effect on cardiac myofilament proteins increasing myofilament Ca(2+) responsiveness by promoting disulfide bond formation between critical cysteine residues. These findings indicate a novel, redox-based modulation of the contractile apparatus, which positively impacts myocardial function, providing further mechanistic insight for HNO as a therapeutic agent.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA. wgao3@jhmi.edu
authors.forename: Wei Dong
authors.initials: WD
authors.lastname: Gao
authors.forename: Christopher I
authors.initials: CI
authors.lastname: Murray
authors.forename: Ye
authors.initials: Y
authors.lastname: Tian
authors.forename: Xin
authors.initials: X
authors.lastname: Zhong
authors.forename: Jenna F
authors.initials: JF
authors.lastname: DuMond
authors.forename: Xiaoxu
authors.initials: X
authors.lastname: Shen
authors.forename: Brian A
authors.initials: BA
authors.lastname: Stanley
authors.forename: D Brian
authors.initials: DB
authors.lastname: Foster
authors.forename: David A
authors.initials: DA
authors.lastname: Wink
authors.forename: S Bruce
authors.initials: SB
authors.lastname: King
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Van Eyk
authors.forename: Nazareno
authors.initials: N
authors.lastname: Paolocci
mesh_terms: D000085:Acetates / Q000378:metabolism / Q000494:pharmacology; D000199:Actins / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D003545:Cysteine / Q000737:chemistry / Q000378:metabolism; D019281:Dimerization; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism*; D006333:Heart Failure / Q000378:metabolism / Q000503:physiopathology; D066298:In Vitro Techniques; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D009124:Muscle Proteins / Q000737:chemistry / Q000378:metabolism; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009210:Myofibrils / Q000187:drug effects / Q000502:physiology*; D018994:Myosin Light Chains / Q000737:chemistry / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D009589:Nitrogen Oxides / Q000737:chemistry / Q000378:metabolism*; D009603:Nitroso Compounds / Q000378:metabolism / Q000494:pharmacology; D010084:Oxidation-Reduction; D051381:Rats
chemical_list: C554428:1-nitrosocyclohexyl acetate; D000085:Acetates; D000199:Actins; D004220:Disulfides; D009124:Muscle Proteins; D018994:Myosin Light Chains; D009589:Nitrogen Oxides; D009603:Nitroso Compounds; C076659:myosin light chain I; D009569:Nitric Oxide; C039900:nitroxyl; D003545:Cysteine; D002118:Calcium