Modulation of CFTR gene expression in HT-29 cells by extracellular hyperosmolarity.
Hypertonicity has pleiotropic effects on cell function, including activation of transporters and regulation of gene expression. It is important to investigate the action of hypertonicity on cystic fibrosis gene expression because cystic fibrosis transmembrane conductance regulator (CFTR), the cAMP-regulated Cl(-) channel, regulates ion transport across the secretory epithelia, which are often in a hypertonic environment. We found that adding >150 mosmol/l NaCl, urea, or mannitol to the culture medium reduced the amount of CFTR mRNA in colon-derived HT-29 cells in a time-dependent manner. Studies with inhibitors of various kinases [H-89 (protein kinase A inhibitor), bisindolylmaleimide (protein kinase C inhibitor), staurosporine (serine/threonine kinase inhibitor) and herbimycin A (tyrosine kinase inhibitor), SB-203580 and PD-098059 (mitogen-activated protein kinase inhibitors)] showed that CFTR gene expression and its decrease by added NaCl required p38 kinase cascade activity. The CFTR gene activity is regulated at the transcriptional level, since adding NaCl diminished the luciferase activity of HeLa cells transiently transfected with the CFTR promoter. This regulation requires protein synthesis. The complexity of the reactions involved in blocking CFTR gene transcription by NaCl strongly suggests that the decrease in CFTR mRNA is part of a general cell response to hyperosmolar stress.
Baudouin-Legros
M
M
Institut National de la Santé et de la Recherche Médicale Unité 467, Faculté de Médecine Necker-Enfants Malades, 75015 Paris, France. legros@necker.fr
Brouillard
F
F
Cougnon
M
M
Tondelier
D
D
Leclerc
T
T
Edelman
A
A
D015152:Blotting, Northern; D002470:Cell Survival / Q000502:physiology; D003513:Cycloheximide / Q000494:pharmacology; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics* / Q000378:metabolism; D003609:Dactinomycin / Q000494:pharmacology; D004234:Diuretics, Osmotic / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005110:Extracellular Space / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology*; D017930:Genes, Reporter; D019073:HT29 Cells; D006367:HeLa Cells; D006801:Humans; D006982:Hypertonic Solutions / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D008156:Luciferases / Q000235:genetics; D008353:Mannitol / Q000494:pharmacology; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D020545:Respiratory Mucosa / Q000737:chemistry / Q000166:cytology / Q000201:enzymology; D015222:Sodium Channels / Q000235:genetics / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology; D014158:Transcription, Genetic / Q000502:physiology; D014882:Water-Electrolyte Balance / Q000187:drug effects / Q000235:genetics*; D048051:p38 Mitogen-Activated Protein Kinases
C505032:CFTR protein, human; D004234:Diuretics, Osmotic; D004791:Enzyme Inhibitors; D006982:Hypertonic Solutions; D007093:Imidazoles; D011500:Protein Synthesis Inhibitors; D011725:Pyridines; D012333:RNA, Messenger; D015222:Sodium Channels; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D003609:Dactinomycin; D008353:Mannitol; D012965:Sodium Chloride; D003513:Cycloheximide; D008156:Luciferases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580