Partial correction of defective Cl(-) secretion in cystic fibrosis epithelial cells by an analog of squalamine.
Defective cystic fibrosis (CF) transmembrane conductance regulator (CFTR)-mediated Cl(-) transport across the apical membrane of airway epithelial cells is implicated in the pathophysiology of CF lungs. A strategy to compensate for this loss is to augment Cl(-) transport through alternative pathways. We report here that partial correction of this defect could be attained through the incorporation of artificial anion channels into the CF cells. Introduction of GL-172, a synthetic analog of squalamine, into CFT1 cells increased cell membrane halide permeability. Furthermore, when a Cl(-) gradient was generated across polarized monolayers of primary human airway or Fischer rat thyroid cells in an Ussing chamber, addition of GL-172 caused an increase in the equivalent short-circuit current. The magnitude of this change in short-circuit current was ~30% of that attained when CFTR was maximally stimulated with cAMP agonists. Patch-clamp studies showed that addition of GL-172 to CFT1 cells also increased whole cell Cl(-) currents. These currents displayed a linear current-voltage relationship and no time dependence. Additionally, administration of GL-172 to the nasal epithelium of transgenic CF mice induced a hyperpolarization response to perfusion with a low-Cl(-) solution, indicating restoration of Cl(-) secretion. Together, these results demonstrate that in CF airway epithelial cells, administration of GL-172 is capable of partially correcting the defective Cl(-) secretion.
Jiang
C
C
Genzyme Corporation, Framingham, Massachusetts 01701-9322, USA.
Lee
E R
ER
Lane
M B
MB
Xiao
Y F
YF
Harris
D J
DJ
Cheng
S H
SH
D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D002712:Chlorides / Q000378:metabolism*; D002777:Cholestanols / Q000737:chemistry / Q000494:pharmacology*; D003550:Cystic Fibrosis / Q000378:metabolism*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000378:metabolism; D004232:Diuretics / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D017136:Ion Transport; D007476:Ionophores / Q000494:pharmacology; D008564:Membrane Potentials; D051379:Mice; D008822:Mice, Transgenic; D015394:Molecular Structure; D009297:Nasal Mucosa / Q000378:metabolism; D018408:Patch-Clamp Techniques; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D020545:Respiratory Mucosa / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
C505032:CFTR protein, human; D002712:Chlorides; D002777:Cholestanols; D004232:Diuretics; C439483:GL-172 cpd; D007476:Ionophores; D011994:Recombinant Proteins; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D000584:Amiloride; C079655:squalamine