Reduction of airway anion secretion via CFTR in sphingomyelin pathway.
The present study concerns the involvement of the ceramide produced through sphingomyelinase (SMase)-mediated catalysis in airway anion secretion of Calu-3 cells. Short-circuit current (Isc) measurement revealed that isoproterenol (ISO, 0.1 microM)-induced anion secretion was prevented by pretreatment with SMase (0.3 U/ml, for 30 min) from the basolateral but not the apical side, although basal and 1-ethyl-2-benzimidazolinone (1-EBIO, a Ca2+-activated K+ channel opener)-induced Isc were unaffected. The effects of SMase were reproduced in responses to forskolin (20 microM) or 8-bromo-cAMP (2 mM). C2-ceramide, a cell-permeable analog, also repressed the 8-bromo-cAMP-induced responses. Nystatin permeabilization studies confirmed that the SMase- and C2-ceramide-induced repressions were due to hindrance of augmentation of cystic fibrosis transmembrane conductance regulator (CFTR)-mediated conductance across the apical membrane. Further, SMase failed to influence K+ conductance across the basolateral membrane. These results suggest that the ceramide originating from basolateral sphingomyelin acts on activated CFTR from the cytosolic side, hindering anion secretion.
Ito
Yasushi
Y
Division of Respiratory Medicine, Department of Medicine, Nagoya University Graduate School of Medicine, Nagoya, Japan. itoyasu@med.nagoya-u.ac.jp
Sato
Shinji
S
Ohashi
Takamasa
T
Nakayama
Shinsuke
S
Shimokata
Kaoru
K
Kume
Hiroaki
H
D000838:Anions; D002460:Cell Line; D002518:Ceramides / Q000378:metabolism; D002712:Chlorides / Q000737:chemistry; D000242:Cyclic AMP / Q000378:metabolism; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism*; D004594:Electrophysiology; D006801:Humans; D008956:Models, Chemical; D011188:Potassium / Q000737:chemistry; D015398:Signal Transduction; D013108:Sphingomyelin Phosphodiesterase / Q000737:chemistry; D013109:Sphingomyelins / Q000737:chemistry / Q000378:metabolism*; D013997:Time Factors; D014132:Trachea / Q000166:cytology
D000838:Anions; C505032:CFTR protein, human; D002518:Ceramides; D002712:Chlorides; D013109:Sphingomyelins; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D000242:Cyclic AMP; D013108:Sphingomyelin Phosphodiesterase; D011188:Potassium