title: Exogenous sphingosine 1-phosphate and sphingosine kinase activated by endothelin-1 induced myometrial contraction through differential mechanisms.
abstract: Sphingosine 1-phosphate (S1P), a bioactive sphingolipid involved in diverse biological processes, is generated by sphingosine kinase (SphK) and acts via intracellular and/or extracellular mechanisms. We used biochemical, pharmacological, and physiological approaches to investigate in rat myometrium the contractile effect of exogenous S1P and the possible contribution of SphK in endothelin-1 (ET-1)-mediated contraction. S1P stimulated uterine contractility (EC(50) = 1 microM and maximal response = 5 microM) by a pertussis toxin-insensitive and a phospholipse C (PLC)-independent pathway. Phosphorylated FTY720, which interacts with all S1P receptors, except S1P(2) receptors, failed to mimic S1P contractile response, indicating that the effects of S1P involved S1P(2) receptors that are expressed in myometrium. Contraction mediated by S1P and ET-1 required extracellular calcium and Rho kinase activation. Inhibition of SphK reduced ET-1-mediated contraction. ET-1, via ET(A) receptors coupled to pertussis toxin-insensitive G proteins, stimulated SphK1 activity and induced its translocation to the membranes. Myometrial contraction triggered by ET-1 is consecutive to the sequential activation of PLC, protein kinase C, SphK1 and Rho kinase. Prolonged exposure of the myometrium to S1P downregulated S1P(2) receptors and abolished the contraction induced by exogenous S1P. However, in these conditions, the tension triggered by ET-1 was not reduced, indicating that SphK activated by ET-1 contributed to its contractile effect via a S1P(2) receptor-independent process. Our findings demonstrated that exogenous S1P and SphK activity regulated myometrial contraction and may be of physiological relevance in the regulation of uterine motility during gestation and parturition.
authors.affiliation: Signalisation et Régulations Cellulaires, Institut de Biochimie, Biophysique Moleculaire et Cellulaire, CNRS UMR 8619, Bâtiment 430, Université de Paris-Sud, 91405 Orsay cedex, France. denis.leiber@erc.u-psud.fr
authors.forename: Denis
authors.initials: D
authors.lastname: Leiber
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Banno
authors.forename: Zahra
authors.initials: Z
authors.lastname: Tanfin
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000502:physiology; D003600:Cytosol / Q000378:metabolism; D019332:Endothelin-1 / Q000494:pharmacology*; D004789:Enzyme Activation; D045604:Extracellular Fluid / Q000378:metabolism; D005260:Female; D019204:GTP-Binding Proteins / Q000187:drug effects / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008246:Lysophospholipids / Q000494:pharmacology*; D009215:Myometrium / Q000187:drug effects / Q000201:enzymology / Q000502:physiology; D037342:Pertussis Toxin / Q000494:pharmacology; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011956:Receptors, Cell Surface / Q000378:metabolism / Q000502:physiology; D049349:Receptors, Lysosphingolipid / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D010738:Type C Phospholipases / Q000378:metabolism; D014590:Uterine Contraction / Q000502:physiology; D020741:rho GTP-Binding Proteins / Q000378:metabolism; D054460:rho-Associated Kinases; D000099157:Sphingosine Kinase
chemical_list: D002118:Calcium; D019332:Endothelin-1; D019204:GTP-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008246:Lysophospholipids; D037342:Pertussis Toxin; D017853:Phosphotransferases (Alcohol Group Acceptor); D011493:Protein Kinase C; D017346:Protein Serine-Threonine Kinases; D011956:Receptors, Cell Surface; D049349:Receptors, Lysosphingolipid; D013110:Sphingosine; D010738:Type C Phospholipases; D020741:rho GTP-Binding Proteins; D054460:rho-Associated Kinases; D000099157:Sphingosine Kinase; C060506:sphingosine 1-phosphate