title: Activation of Pak1/Akt/eNOS signaling following sphingosine-1-phosphate release as part of a mechanism protecting cardiomyocytes against ischemic cell injury.
abstract: We investigated whether plasma long-chain sphingoid base (LCSB) concentrations are altered by transient cardiac ischemia during percutaneous coronary intervention (PCI) in humans and examined the signaling through the sphingosine-1-phosphate (S1P) cascade as a mechanism underlying the S1P cardioprotective effect in cardiac myocytes. Venous samples were collected from either the coronary sinus (n = 7) or femoral vein (n = 24) of 31 patients at 1 and 5 min and 12 h, following induction of transient myocardial ischemia during elective PCI. Coronary sinus levels of LCSB were increased by 1,072% at 1 min and 941% at 5 min (n = 7), while peripheral blood levels of LCSB were increased by 579% at 1 min, 617% at 5 min, and 436% at 12 h (n = 24). In cultured cardiac myocytes, S1P, sphingosine (SPH), and FTY720, a sphingolipid drug candidate, showed protective effects against CoCl induced hypoxia/ischemic cell injury by reducing lactate dehydrogenase activity. Twenty-five nanomolars of FTY720 significantly increased phospho-Pak1 and phospho-Akt levels by 56 and 65.6% in cells treated with this drug for 15 min. Further experiments demonstrated that FTY720 triggered nitric oxide release from cardiac myocytes is through pertussis toxin-sensitive phosphatidylinositol 3-kinase/Akt/endothelial nitric oxide synthase signaling. In ex vivo hearts, ischemic preconditioning was cardioprotective in wild-type control mice (Pak1(f/f)), but this protection appeared to be ineffective in cardiomyocyte-specific Pak1 knockout (Pak1(cko)) hearts. The present study provides the first direct evidence of the behavior of plasma sphingolipids following transient cardiac ischemia with dramatic and early increases in LCSB in humans. We also demonstrated that S1P, SPH, and FTY720 have protective effects against hypoxic/ischemic cell injury, likely a Pak1/Akt1 signaling cascade and nitric oxide release. Further study on a mouse model of cardiac specific deletion of Pak1 demonstrates a crucial role of Pak1 in cardiac protection against ischemia/reperfusion injury.
authors.affiliation: Hull and York Medical School, Academic Cardiology, Kingston-upon-Hull, United Kingdom.
authors.forename: Emmanuel Eroume A
authors.initials: EE
authors.lastname: Egom
authors.forename: Tamer M A
authors.initials: TM
authors.lastname: Mohamed
authors.forename: Mamas A
authors.initials: MA
authors.lastname: Mamas
authors.forename: Ying
authors.initials: Y
authors.lastname: Shi
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.forename: Debora
authors.initials: D
authors.lastname: Chirico
authors.forename: Sally E
authors.initials: SE
authors.lastname: Stringer
authors.forename: Yunbo
authors.initials: Y
authors.lastname: Ke
authors.forename: Mohamed
authors.initials: M
authors.lastname: Shaheen
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.forename: Sanoj
authors.initials: S
authors.lastname: Chacko
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.forename: R John
authors.initials: RJ
authors.lastname: Solaro
authors.forename: Farzin
authors.initials: F
authors.lastname: Fath-Ordoubadi
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: Cartwright
authors.forename: Ming
authors.initials: M
authors.lastname: Lei
mesh_terms: D000328:Adult; D000368:Aged; D015906:Angioplasty, Balloon, Coronary; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000139:chemically induced / Q000503:physiopathology; D001711:Biotransformation; D015153:Blotting, Western; D002316:Cardiotonic Agents; D015687:Cell Hypoxia / Q000502:physiology; D002470:Cell Survival / Q000502:physiology; D054059:Coronary Occlusion / Q000378:metabolism; D005260:Female; D000068876:Fingolimod Hydrochloride; D006801:Humans; D066298:In Vitro Techniques; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008246:Lysophospholipids / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000502:physiology; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000235:genetics / Q000502:physiology*; D051058:Oncogene Protein v-akt / Q000235:genetics / Q000502:physiology*; D037342:Pertussis Toxin / Q000494:pharmacology; D011409:Propylene Glycols / Q000494:pharmacology; D051381:Rats; D013107:Sphingolipids / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D054462:p21-Activated Kinases / Q000235:genetics / Q000502:physiology*
chemical_list: D002316:Cardiotonic Agents; D008246:Lysophospholipids; D011409:Propylene Glycols; D013107:Sphingolipids; C060506:sphingosine 1-phosphate; D009569:Nitric Oxide; D007770:L-Lactate Dehydrogenase; D052250:Nitric Oxide Synthase Type III; D037342:Pertussis Toxin; D051058:Oncogene Protein v-akt; C515903:PAK1 protein, human; D054462:p21-Activated Kinases; D000068876:Fingolimod Hydrochloride; D013110:Sphingosine