Effect of ouabain on CFTR gene expression in human Calu-3 cells.
We have previously shown that ouabain, which changes the electrochemical properties of cell membranes by inhibiting Na(+),K(+)-ATPase, induces the expression of multidrug resistance (MDR-1) gene in several human cell lines. Because the expressions of the MDR-1 and CFTR (which encodes the cAMP-activated Cl(-) channel associated with cystic fibrosis) genes are physiologically regulated in opposing directions, we wanted to determine whether ouabain also decreases CFTR transcripts and subsequently to analyze its mechanism of action. We found that the submicromolar concentrations of ouabain that increase MDR-1 mRNAs decrease the CFTR transcripts with analogous time-dependency in human pulmonary Calu-3 cells. By altering or reproducing the ouabain-induced changes in intracellular ionic activities (decreasing in external Na(+) or K(+) or using Na(+) ionophore), we show that the ouabain-induced regulations of both CFTR and MDR-1 transcripts depend on the Na(+)/K(+) pump inhibition but that the decrease in CFTR mRNAs also proceeds from cytoplasm reactions simultaneously activated by ouabain. These data, which emphasize the complex mechanism of action of ouabain, suggest that changes in intracellular ionic activities modulate CFTR/MDR-1 gene expressions.
Baudouin-Legros
Maryvonne
M
Institut National de la Santé et de la Recherche Médicale U. 467, Faculté de Médecine Necker, 75015 Paris, France. legros@necker.fr
Brouillard
Franck
F
Tondelier
Danielle
D
Hinzpeter
Alexandre
A
Edelman
Aleksander
A
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D002794:Choline / Q000494:pharmacology; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics*; D004077:Digoxin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D016623:Ion Pumps / Q000187:drug effects / Q000235:genetics; D017136:Ion Transport / Q000187:drug effects / Q000235:genetics; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D010042:Ouabain / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D020545:Respiratory Mucosa / Q000187:drug effects / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; C505032:CFTR protein, human; D016623:Ion Pumps; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D010042:Ouabain; D004077:Digoxin; D011493:Protein Kinase C; D000254:Sodium-Potassium-Exchanging ATPase; D002794:Choline