CFTR modulates programmed cell death by decreasing intracellular pH in Chinese hamster lung fibroblasts.
To study the potential influence of cystic fibrosis conductance regulator (CFTR) on intracellular pH regulation during apoptosis induction, we used PS120 Chinese hamster lung fibroblasts devoid of the Na(+)/H(+) exchanger (NHE1 isoform) transfected with constructs, allowing the expression of CFTR and/or NHE1. Kinetics of lovastatin-induced apoptosis were measured by orcein staining, double staining with Hoechst-33258, propidium iodide, DNA fragmentation, and annexin V labeling. In PS120 control cells, the percentage of apoptotic cells after 40 h of lovastatin treatment was 23 +/- 3%, whereas in PS120 CFTR-transfected cells, this percentage was 40 +/- 4%. In PS120 NHE1 cells, the transfection with CFTR did not modify the percentage of apoptotic cells after 40 h (control: 19 +/- 3%, n = 8; CFTR: 17 +/- 1%, n = 8), indicating that blocking intracellular acidification by overexpressing the Na(+)/H(+) exchanger inhibited the enhancement of apoptosis induced by CFTR. In all cell lines, the initial pH values were identical (pH = 7.46 +/- 0.04, n = 9), and treatment with lovastatin led to intracellular acidification. However, the pH value after 40 h was lower in PS120 CFTR-transfected cells (pH = 6.85 +/- 0.02, n = 10) than in PS120 cells (pH = 7.15 +/- 0.03, n = 10). To further investigate the origin of this increased intracellular acidification observed in CFTR-transfected cells, the activity of the DIDS-inhibitable Cl(-)/HCO exchanger was studied. 8-Bromoadenosine 3',5'-cyclic monophosphate incubation resulted in Cl(-)/HCO exchanger activation in PS120 CFTR-transfected cells but had no effect on PS120 cells. Together, our results suggest that CFTR can enhance apoptosis in Chinese hamster lung fibroblasts, probably due to the modulation of the Cl(-)/HCO exchanger, resulting in a more efficient intracellular acidification.
Barrière
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Unité Mixte de Recherche-Centre National de la Recherche Scientifique 6548, Université de Nice-Sophia Antipolis, 06108 Nice Cedex 2, France.
Poujeol
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Tauc
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Blasi
J M
JM
Counillon
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L
Poujeol
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D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D020533:Angiogenesis Inhibitors / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002460:Cell Line; D018118:Chloride Channels / Q000187:drug effects / Q000502:physiology; D002712:Chlorides / Q000378:metabolism; D006224:Cricetinae; D003412:Cricetulus; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D053938:DNA Fragmentation; D005347:Fibroblasts; D005942:Gluconates / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007454:Iodides / Q000494:pharmacology; D007700:Kinetics; D008148:Lovastatin / Q000494:pharmacology; D008168:Lung; D009579:Nitrobenzoates / Q000494:pharmacology; D011994:Recombinant Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics / Q000502:physiology*; D014162:Transfection
D020533:Angiogenesis Inhibitors; D018118:Chloride Channels; D002712:Chlorides; D005942:Gluconates; D007454:Iodides; D009579:Nitrobenzoates; D011994:Recombinant Proteins; D017923:Sodium-Hydrogen Exchangers; C069139:growth factor-activatable Na-H exchanger NHE-1; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D015124:8-Bromo Cyclic Adenosine Monophosphate; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D008148:Lovastatin; C030691:gluconic acid