Delta F508-CFTR channels: kinetics, activation by forskolin, and potentiation by xanthines
| Autor: | I. B. Nepomuceno, Mauri E. Krouse, Yang Xia, Heather A. Wakelee, Hao G. Nguyen, C. M. Haws, T. Law, Jeffrey J. Wine |
|---|---|
| Rok vydání: | 1996 |
| Předmět: |
Delta
congenital hereditary and neonatal diseases and abnormalities medicine.medical_specialty Glycosylation Time Factors IBMX Physiology Cystic Fibrosis Transmembrane Conductance Regulator Cell Line Mice chemistry.chemical_compound 1-Methyl-3-isobutylxanthine Internal medicine Cyclic AMP medicine Animals Ion transporter Forskolin biology Chemistry Colforsin Cell Biology respiratory system Adenosine Molecular biology digestive system diseases Cystic fibrosis transmembrane conductance regulator respiratory tract diseases Electrophysiology Endocrinology Cell culture Xanthines Mutation biology.protein Intracellular Iodine medicine.drug |
| Zdroj: | American Journal of Physiology-Cell Physiology. 270:C1544-C1555 |
| ISSN: | 1522-1563 0363-6143 |
| DOI: | 10.1152/ajpcell.1996.270.5.c1544 |
| Popis: | Trafficking, activation, and kinetics of delta F508-cystic fibrosis transmembrane conductance regulator (CFTR) and CFTR were compared in stably transduced C127I mouse mammary epithelial cells. Western blots detected a small amount of fully glycosylated delta F508-CFTR Efflux of 125I was stimulated by forskolin with the same mean effective concentration (EC50; approximately 0.5 microM) for CFTR and delta F508-CFTR cells, but the maximum response was reduced more than fivefold and its latency increased approximately threefold in delta F508-CFTR cells. In delta F508-CFTR cells, 3-isobutyl-1-methylxanthine (IBMX; EC50 = 1.45 microM) and 8-cyclopentyl-1,3-dipropylxanthine (CPX; EC50 = 58 microM) increased the peak forskolin-stimulated efflux rate approximately 2.5-fold and decreased the time to peak. A sevenfold increase in intracellular adenosine 3',5'-cyclic monophosphate (cAMP) levels accompanied potentiation of forskolin-induced 125I efflux by IBMX but not by CPX. Elevation of intracellular cAMP increased linear voltage-independent whole cell currents 30-fold in CFTR and 4-fold in delta F508-CFTR cells; the response rate in delta F508-CFTR cells was much slower. Single-channel currents were detected in 57 of 68 cell-attached patches from forskolin-prestimulated CFTR cells vs. 6 of 35 patches in delta F508-CFTR cells. Mean number of active channels per patch was 4.1 for CFTR [open probability (Po) = 0.34] and 0.2 for delta F508-CFTR (Po = 0.11). The lower Po of delta F508-CFTR resulted from an approximately threefold longer mean interburst interval. We estimate that forskolin-stimulated chloride conductance of delta F508-CFTR C127I cells is < 5% of CFTR cells. CPX is approximately 25-fold more potent than IBMX in potentiating delta F508-CFTR and may operate by a mechanism other than elevation of cAMP. |
| Databáze: | OpenAIRE |
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