Cystic fibrosis transmembrane conductance regulator activation by cAMP-independent mechanisms.
Recent studies have demonstrated that several compounds with diverse structures can activate wild-type cystic fibrosis transmembrane conductance regulator (CFTR) by non-receptor-mediated mechanisms. Some of these compounds have been shown to enhance cAMP-dependent activation of DeltaF508-CFTR. This study was undertaken to compare the mechanisms by which genistein, IBMX, milrinone, 8-cyclopentyl-1, 3-dipropylxanthine (CPX), the benzimidazolone NS004, and calyculin A increase CFTR activity. Our studies demonstrate that, in transfected NIH-3T3 cells, maximal enhancements of forskolin-dependent DeltaF508-CFTR activity are greatest with genistein, IBMX, and NS004. Milrinone, genistein, CPX, NS004, and calyculin A do not increase cellular cAMP. Because forskolin and calyculin A increase in vivo phosphorylation of cAMP binding response element (CREB), the inability of milrinone, genistein, CPX, and NS004 to increase CREB phosphorylation suggests that they do not stimulate protein kinase A or inhibit phosphatase activity. Our data suggest that the mechanisms by which genistein and NS004 activate CFTR differ. We also demonstrate that, in NIH-3T3 cells, IBMX-dependent enhancement of cAMP-dependent CFTR activity is not due to an increase in cellular cAMP and may involve a mechanism like that of genistein.
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Department of Clinical Science, Alfred I. duPont Hospital for Children, Thomas Jefferson University, Wilmington, Delaware 19803, USA.
Raman
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Guo
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Reenstra
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D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D016475:3T3 Cells; D000818:Animals; D001562:Benzimidazoles / Q000494:pharmacology; D002733:Chlorophenols / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019833:Genistein / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D008387:Marine Toxins; D051379:Mice; D010080:Oxazoles / Q000494:pharmacology; D010748:Phosphopeptides / Q000302:isolation & purification / Q000378:metabolism; D010766:Phosphorylation; D011994:Recombinant Proteins / Q000187:drug effects / Q000378:metabolism; D017384:Sequence Deletion; D014162:Transfection; D014970:Xanthines / Q000494:pharmacology
D001562:Benzimidazoles; C505032:CFTR protein, human; D002733:Chlorophenols; D017362:Cyclic AMP Response Element-Binding Protein; D004791:Enzyme Inhibitors; D008387:Marine Toxins; D010080:Oxazoles; D010748:Phosphopeptides; D011994:Recombinant Proteins; D014970:Xanthines; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D005576:Colforsin; C083230:NS 004; C059041:calyculin A; C051360:1,3-dipropyl-8-cyclopentylxanthine; D019833:Genistein; D000242:Cyclic AMP; D015056:1-Methyl-3-isobutylxanthine