title: Cardiac preconditioning with sphingosine-1-phosphate requires activation of signal transducer and activator of transcription-3.
abstract: OBJECTIVE
  Sphingosine-1-phosphate (S1P) is a cardioprotective agent. Signal transducer and activator of transcription 3 (STAT-3) is a key mediator of many cardioprotective agents. We aimed to explore whether STAT-3 is a key mediator in S1P-induced preconditioning.
  
  
  METHODS
  Langendorff-perfused hearts from Wistar rats and wild-type or cardiomyocyte-specific STAT-3 knockout mice were pre-treated with S1P (10 nmol/l), with or without the STAT-3 pathway inhibitor AG490, before an ischaemia-reperfusion insult. Triphenyltetrazolium chloride and Evans blue staining were used for the determination of infarct size. Western blot analysis was carried out on the S1P pre-treated hearts for detection of cytosolic, nuclear and mitochondrial phosphorylated and total STAT-3 proteins.
  
  
  RESULTS
  Pre-treatment with S1P decreased the infarct size in isolated rat (5 ± 3% vs control 26 ± 8%, p < 0.01) and wild-type mouse hearts (13 ± 1% vs control 33 ± 3%, p < 0.05). This protective effect was abolished in the rat hearts pre-treated with AG490 (30 ± 10%, p = ns vs control) and in the hearts from STAT-3 knockout mice (35 ± 4% vs control 30 ± 3%, p = ns). Levels of phosphorylated STAT-3 were significantly increased in both the nuclear (p < 0.05 vs control) and mitochondrial (p < 0.05 vs control) fractions in the S1P pre-treated hearts, but remained unchanged in the cytosolic fraction (p = ns vs control).
  
  
  CONCLUSIONS
  These novel results demonstrate that pharmacological preconditioning with S1P in the isolated heart is mediated by activation of mitochondrial and nuclear STAT-3, therefore suggesting that S1P may be a novel therapeutic target to modulate mitochondrial and nuclear function in cardiovascular disease in order to protect the heart against ischaemia-reperfusion.
authors.affiliation: Hatter Institute for Cardiovascular Research in Africa, Chris Barnard Building, Medical School Campus, University of Cape Town, Cape Town, South Africa.
authors.forename: Roisin F
authors.initials: RF
authors.lastname: Kelly-Laubscher
authors.affiliation: Hatter Institute for Cardiovascular Research in Africa, Chris Barnard Building, Medical School Campus, University of Cape Town, Cape Town, South Africa.
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: King
authors.affiliation: Hatter Institute for Cardiovascular Research in Africa, Chris Barnard Building, Medical School Campus, University of Cape Town, Cape Town, South Africa.
authors.forename: Damian
authors.initials: D
authors.lastname: Hacking
authors.affiliation: Hatter Institute for Cardiovascular Research in Africa, Chris Barnard Building, Medical School Campus, University of Cape Town, Cape Town, South Africa.
authors.forename: Sarin
authors.initials: S
authors.lastname: Somers
authors.affiliation: Hatter Institute for Cardiovascular Research in Africa, Chris Barnard Building, Medical School Campus, University of Cape Town, Cape Town, South Africa.
authors.forename: Samantha
authors.initials: S
authors.lastname: Hastie
authors.affiliation: Hatter Institute for Cardiovascular Research in Africa, Chris Barnard Building, Medical School Campus, University of Cape Town, Cape Town, South Africa.
authors.forename: Tessa
authors.initials: T
authors.lastname: Stewart
authors.affiliation: Hatter Institute for Cardiovascular Research in Africa, Chris Barnard Building, Medical School Campus, University of Cape Town, Cape Town, South Africa.
authors.forename: Aqeela
authors.initials: A
authors.lastname: Imamdin
authors.affiliation: Hatter Institute for Cardiovascular Research in Africa, Chris Barnard Building, Medical School Campus, University of Cape Town, Cape Town, South Africa.
authors.forename: Gerald
authors.initials: G
authors.lastname: Maarman
authors.affiliation: Hatter Institute for Cardiovascular Research in Africa, Chris Barnard Building, Medical School Campus, University of Cape Town, Cape Town, South Africa.
authors.forename: Sarah
authors.initials: S
authors.lastname: Pedretti
authors.affiliation: Hatter Institute for Cardiovascular Research in Africa, Chris Barnard Building, Medical School Campus, University of Cape Town, Cape Town, South Africa.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Lecour
mesh_terms: D000818:Animals; D002316:Cardiotonic Agents / Q000627:therapeutic use*; D004195:Disease Models, Animal; D019157:Ischemic Preconditioning, Myocardial; D008246:Lysophospholipids / Q000494:pharmacology*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009203:Myocardial Infarction / Q000188:drug therapy*; D009206:Myocardium / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000187:drug effects; D017208:Rats, Wistar; D050796:STAT3 Transcription Factor / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D020032:Tyrphostins / Q000627:therapeutic use*
chemical_list: D002316:Cardiotonic Agents; D008246:Lysophospholipids; D050796:STAT3 Transcription Factor; C494087:Stat3 protein, mouse; C494088:Stat3 protein, rat; D020032:Tyrphostins; C095512:alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide; C060506:sphingosine 1-phosphate; D013110:Sphingosine