title: Disruption of caveolae blocks ischemic preconditioning-mediated S-nitrosylation of mitochondrial proteins.
abstract: OBJECTIVE
  Nitric oxide (NO) and protein S-nitrosylation (SNO) play important roles in ischemic preconditioning (IPC)-induced cardioprotection. Mitochondria are key regulators of preconditioning, and most proteins showing an increase in SNO with IPC are mitochondrial. The aim of this study was to address how IPC transduces NO/SNO signaling to mitochondria in the heart.
  
  
  RESULTS
  In this study using Langendorff perfused mouse hearts, we found that IPC-induced cardioprotection was blocked by treatment with either N-nitro-L-arginine methyl ester (L-NAME, a constitutive NO synthase inhibitor), ascorbic acid (a reducing agent to decompose SNO), or methyl-?-cyclodextrin (M?CD, a cholesterol sequestering agent to disrupt caveolae). IPC not only activated AKT/eNOS signaling but also led to translocation of eNOS to mitochondria. M?CD treatment disrupted caveolar structure, leading to dissociation of eNOS from caveolin-3 and blockade of IPC-induced activation of the AKT/eNOS signaling pathway. A significant increase in mitochondrial SNO was found in IPC hearts compared to perfusion control, and the disruption of caveolae by M?CD treatment not only abolished IPC-induced cardioprotection, but also blocked the IPC-induced increase in SNO.
  
  
  METHODS
  These results provide mechanistic insight into how caveolae/eNOS/NO/SNO signaling mediates cardioprotection induced by IPC.
  
  
  CONCLUSIONS
  Altogether these results suggest that caveolae transduce eNOS/NO/SNO cardioprotective signaling in the heart.
authors.affiliation: Systems Biology Center, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA. sun1@mail.nih.gov
authors.forename: Junhui
authors.initials: J
authors.lastname: Sun
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Kohr
authors.forename: Tiffany
authors.initials: T
authors.lastname: Nguyen
authors.forename: Angel M
authors.initials: AM
authors.lastname: Aponte
authors.forename: Patricia S
authors.initials: PS
authors.lastname: Connelly
authors.forename: Shervin G
authors.initials: SG
authors.lastname: Esfahani
authors.forename: Marjan
authors.initials: M
authors.lastname: Gucek
authors.forename: Mathew P
authors.initials: MP
authors.lastname: Daniels
authors.forename: Charles
authors.initials: C
authors.lastname: Steenbergen
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Murphy
mesh_terms: D000818:Animals; D021941:Caveolae / Q000378:metabolism*; D051244:Caveolin 3 / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D006321:Heart / Q000187:drug effects; D019157:Ischemic Preconditioning, Myocardial; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D010084:Oxidation-Reduction; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012508:Sarcolemma / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D047392:beta-Cyclodextrins / Q000494:pharmacology
chemical_list: D051244:Caveolin 3; D024101:Mitochondrial Proteins; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D009569:Nitric Oxide; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; D051057:Proto-Oncogene Proteins c-akt