title: Sphingosine-1-phosphate reduces ischaemia-reperfusion injury by phosphorylating the gap junction protein Connexin43.
abstract: OBJECTIVE
  Increasing evidence points to lipoprotein composition rather than reverse cholesterol transport in the cardioprotective properties of high-density lipoproteins (HDLs). HDL binding to receptors at the surface of cardiomyocytes activates signalling pathways promoting survival, but downstream targets are largely unknown. Here, we investigate the pathways by which the sphingosine-1-phosphate (S1P) constituent of HDL limits cell death induced by cardiac ischaemia-reperfusion (I/R).
  
  
  RESULTS
  Apolipoprotein M (ApoM) transgenic (Apom-Tg) mice, in which plasma S1P is increased by 296%, and wild-type (WT) mice were subjected to in vivo I/R. Infarct size, neutrophil infiltration into the infarcted area, and serum Troponin I were less pronounced in Apom-Tg mice. In vitro experiments suggest that this cardioprotection depends on direct effects of S1P on cardiomyocytes, whereas leucocyte recruitment seems only indirectly affected. Importantly, short-term S1P treatment at the onset of reperfusion was sufficient to reduce I/R injury in isolated perfused hearts. Mechanistic in vitro and ex vivo studies revealed that 5 min of S1P treatment induced phosphorylation of the gap junction protein Connexin43 (Cx43) on Serine368 (S368), which was mediated by S1P2 and S1P3, but not by S1P1, receptors in cardiomyocytes. Finally, S1P-induced reduction of infarct size after ex vivo I/R was lost in hearts of mice with a truncated C-terminus of Cx43 (Cx43(K258/KO)) or in which the S368 is mutated to a non-phosphorylatable alanine (Cx43(S368A/S368A)).
  
  
  CONCLUSIONS
  Our study reveals an important molecular pathway by which modulating the apoM/S1P axis has a therapeutic potential in the fight against I/R injury in the heart.
authors.affiliation: Department of Pathology and Immunology, University of Geneva, CMU, F06.2747.a, Rue Michel-Servet 1, Geneva 1211, Switzerland sandrine.morel@unige.ch.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Morel
authors.affiliation: Department of Clinical Biochemistry, Rigshospitalet, Copenhagen 2100, Denmark Department of Biomedical Sciences, Copenhagen 2200, Denmark.
authors.forename: Christina
authors.initials: C
authors.lastname: Christoffersen
authors.affiliation: Department of Biomedical Sciences, Copenhagen 2200, Denmark The Danish National Research Foundation Centre for Cardiac Arrhythmia, Copenhagen 2200, Denmark.
authors.forename: Lene N
authors.initials: LN
authors.lastname: Axelsen
authors.affiliation: Department of Medical Specialties-Cardiology, University of Geneva, Geneva 1211, Switzerland.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Montecucco
authors.affiliation: Department of Pathology and Immunology, University of Geneva, CMU, F06.2747.a, Rue Michel-Servet 1, Geneva 1211, Switzerland.
authors.forename: Viviane
authors.initials: V
authors.lastname: Rochemont
authors.affiliation: Department of Medical Specialties-Endocrinology, Diabetology, Hypertension and Nutrition, University of Geneva, Geneva 1211, Switzerland.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Frias
authors.affiliation: Department of Medical Specialties-Cardiology, University of Geneva, Geneva 1211, Switzerland.
authors.forename: Francois
authors.initials: F
authors.lastname: Mach
authors.affiliation: Department of Medical Specialties-Endocrinology, Diabetology, Hypertension and Nutrition, University of Geneva, Geneva 1211, Switzerland.
authors.forename: Richard W
authors.initials: RW
authors.lastname: James
authors.affiliation: Department of Cellular and Physiological Science, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
authors.forename: Christian C
authors.initials: CC
authors.lastname: Naus
authors.affiliation: Department of Pediatrics, University of Geneva, Geneva 1211, Switzerland Department of Cell Physiology and Metabolism, University of Geneva, Geneva 1211, Switzerland.
authors.forename: Marc
authors.initials: M
authors.lastname: Chanson
authors.affiliation: Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Lampe
authors.affiliation: Department of Biomedical Sciences, Copenhagen 2200, Denmark The Danish National Research Foundation Centre for Cardiac Arrhythmia, Copenhagen 2200, Denmark.
authors.forename: Morten S
authors.initials: MS
authors.lastname: Nielsen
authors.affiliation: Department of Clinical Biochemistry, Rigshospitalet, Copenhagen 2100, Denmark Department of Biomedical Sciences, Copenhagen 2200, Denmark Department of Clinical Medicine, University of Copenhagen, Copenhagen 2100, Denmark.
authors.forename: Lars B
authors.initials: LB
authors.lastname: Nielsen
authors.affiliation: Department of Pathology and Immunology, University of Geneva, CMU, F06.2747.a, Rue Michel-Servet 1, Geneva 1211, Switzerland Department of Medical Specialties-Cardiology, University of Geneva, Geneva 1211, Switzerland.
authors.forename: Brenda R
authors.initials: BR
authors.lastname: Kwak
mesh_terms: D000818:Animals; D001053:Apolipoproteins / Q000235:genetics; D000075243:Apolipoproteins M; D002316:Cardiotonic Agents / Q000494:pharmacology; D018031:Connexin 43 / Q000235:genetics / Q000378:metabolism*; D017630:Connexins / Q000235:genetics / Q000378:metabolism*; D008075:Lipoproteins, HDL / Q000378:metabolism; D008246:Lysophospholipids / Q000235:genetics / Q000378:metabolism*; D018345:Mice, Knockout; D017202:Myocardial Ischemia / Q000378:metabolism*; D015428:Myocardial Reperfusion Injury / Q000517:prevention & control*; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism; D010766:Phosphorylation; D049349:Receptors, Lysosphingolipid / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000235:genetics / Q000378:metabolism
chemical_list: C501623:ApoM protein, mouse; D001053:Apolipoproteins; D000075243:Apolipoproteins M; D002316:Cardiotonic Agents; D018031:Connexin 43; D017630:Connexins; D008075:Lipoproteins, HDL; D008246:Lysophospholipids; D049349:Receptors, Lysosphingolipid; C060506:sphingosine 1-phosphate; D013110:Sphingosine
keywords: Connexin43; Ischaemia–reperfusion injury; Sphingosine-1-phosphate