title: Sphingosine-1-Phosphate Is a Novel Regulator of Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Activity.
abstract: The cystic fibrosis transmembrane conductance regulator (CFTR) attenuates sphingosine-1-phosphate (S1P) signaling in resistance arteries and has emerged as a prominent regulator of myogenic vasoconstriction. This investigation demonstrates that S1P inhibits CFTR activity via adenosine monophosphate-activated kinase (AMPK), establishing a potential feedback link. In Baby Hamster Kidney (BHK) cells expressing wild-type human CFTR, S1P (1μmol/L) attenuates forskolin-stimulated, CFTR-dependent iodide efflux. S1P's inhibitory effect is rapid (within 30 seconds), transient and correlates with CFTR serine residue 737 (S737) phosphorylation. Both S1P receptor antagonism (4μmol/L VPC 23019) and AMPK inhibition (80μmol/L Compound C or AMPK siRNA) attenuate S1P-stimluated (i) AMPK phosphorylation, (ii) CFTR S737 phosphorylation and (iii) CFTR activity inhibition. In BHK cells expressing the ΔF508 CFTR mutant (CFTRΔF508), the most common mutation causing cystic fibrosis, both S1P receptor antagonism and AMPK inhibition enhance CFTR activity, without instigating discernable correction. In summary, we demonstrate that S1P/AMPK signaling transiently attenuates CFTR activity. Since our previous work positions CFTR as a negative S1P signaling regulator, this signaling link may positively reinforce S1P signals. This discovery has clinical ramifications for the treatment of disease states associated with enhanced S1P signaling and/or deficient CFTR activity (e.g. cystic fibrosis, heart failure). S1P receptor/AMPK inhibition could synergistically enhance the efficacy of therapeutic strategies aiming to correct aberrant CFTR trafficking.
authors.affiliation: Department of Physiology, University of Toronto, Medical Science Building, 1 King's College Circle, Toronto, M5S 1A8 Canada.
authors.forename: Firhan A
authors.initials: FA
authors.lastname: Malik
authors.affiliation: Department of Physiology, University of Toronto, Medical Science Building, 1 King's College Circle, Toronto, M5S 1A8 Canada; Department of Brain Ischemia and Neurodegeneration, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Rosello 161, 6th floor, 08036 Barcelona, Spain.
authors.forename: Anja
authors.initials: A
authors.lastname: Meissner
authors.affiliation: Department of Physiology, University of Toronto, Medical Science Building, 1 King's College Circle, Toronto, M5S 1A8 Canada.
authors.forename: Illya
authors.initials: I
authors.lastname: Semenkov
authors.affiliation: Department of Biochemistry, University of Toronto, Medical Science Building, 1 King's College Circle, Toronto, M5S 1A8 Canada; Programme in Molecular Structure and Function in the Research Institute, The Hospital for Sick Children, 555 University Avenue, Toronto, MG5 1X8 Canada.
authors.forename: Steven
authors.initials: S
authors.lastname: Molinski
authors.affiliation: Department of Biochemistry, University of Toronto, Medical Science Building, 1 King's College Circle, Toronto, M5S 1A8 Canada; Programme in Molecular Structure and Function in the Research Institute, The Hospital for Sick Children, 555 University Avenue, Toronto, MG5 1X8 Canada.
authors.forename: Stan
authors.initials: S
authors.lastname: Pasyk
authors.affiliation: Department of Physiology, University of Toronto, Medical Science Building, 1 King's College Circle, Toronto, M5S 1A8 Canada; Programme in Molecular Structure and Function in the Research Institute, The Hospital for Sick Children, 555 University Avenue, Toronto, MG5 1X8 Canada.
authors.forename: Saumel
authors.initials: S
authors.lastname: Ahmadi
authors.affiliation: Lilly Research Laboratories, Indianapolis, Indiana 46285, United States of America.
authors.forename: Hai H
authors.initials: HH
authors.lastname: Bui
authors.affiliation: Department of Physiology, University of Toronto, Medical Science Building, 1 King's College Circle, Toronto, M5S 1A8 Canada; Department of Biochemistry, University of Toronto, Medical Science Building, 1 King's College Circle, Toronto, M5S 1A8 Canada; Programme in Molecular Structure and Function in the Research Institute, The Hospital for Sick Children, 555 University Avenue, Toronto, MG5 1X8 Canada.
authors.forename: Christine E
authors.initials: CE
authors.lastname: Bear
authors.affiliation: Department of Physiology, University of Toronto, Medical Science Building, 1 King's College Circle, Toronto, M5S 1A8 Canada; Toronto Centre for Microvascular Medicine, University of Toronto and The Li Ka Shing Knowledge Institute at St. Michael's Hospital, 209 Victoria Street, Toronto, M5B 1T8 Canada.
authors.forename: Darcy
authors.initials: D
authors.lastname: Lidington
authors.affiliation: Department of Physiology, University of Toronto, Medical Science Building, 1 King's College Circle, Toronto, M5S 1A8 Canada; Toronto Centre for Microvascular Medicine, University of Toronto and The Li Ka Shing Knowledge Institute at St. Michael's Hospital, 209 Victoria Street, Toronto, M5B 1T8 Canada; Heart & Stroke / Richard Lewar Centre of Excellence for Cardiovascular Research, University of Toronto, 50 College Street, Toronto, M5S 3E2 Canada.
authors.forename: Steffen-Sebastian
authors.initials: SS
authors.lastname: Bolz
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007454:Iodides / Q000378:metabolism; D008246:Lysophospholipids / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation; D049349:Receptors, Lysosphingolipid / Q000378:metabolism; D015398:Signal Transduction; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D007454:Iodides; D008246:Lysophospholipids; D049349:Receptors, Lysosphingolipid; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; C060506:sphingosine 1-phosphate; D055372:AMP-Activated Protein Kinases; D013110:Sphingosine