Contribution of CFTR to apical-basolateral fluid transport in cultured human alveolar epithelial type II cells.
Previous studies in intact lung suggest that CFTR may play a role in cAMP-regulated fluid transport from the distal air spaces of the lung. However, the potential contribution of different epithelial cells (alveolar epithelial type I, type II, or bronchial epithelial cells) to CFTR-regulated fluid transport is unknown. In this study we determined whether the CFTR gene is expressed in human lung alveolar epithelial type II (AT II) cells and whether the CFTR chloride channel contributes to cAMP-regulated fluid transport in cultured human AT II cells. Human AT II cells were isolated and cultured on collagen I-coated Transwell membranes for 120-144 h with an air-liquid interface. The cultured cells retained typical AT II-like features based on morphologic studies. Net basal fluid transport was 0.9+/-0.1 mul.cm-2.h-1 and increased to 1.35+/-0.11 mul.cm-2.h-1 (mean+/-SE, n=18, P<0.05) by stimulation with cAMP agonists. The CFTR inhibitor, CFTRinh-172, inhibited cAMP stimulated but not basal fluid transport. In short-circuit current (Isc) studies with an apical-to-basolateral transepithelial Cl- gradient, apical application of CFTRinh-172 reversed the forskolin-induced decrease in Isc. Real time RT-PCR demonstrated CFTR transcript expression in human AT II cells at a level similar to that in airway epithelial cells. We conclude that CFTR is expressed in cultured human AT II cells and may contribute to cAMP-regulated apical-basolateral fluid transport.
Fang
Xiaohui
X
Cardiovascular Research Inst., Department of Medicine/Physiology, Univ. of California, San Francisco, CA 94143-0130, USA. xiaohui.fang@ucsf.edu
Song
Yuanlin
Y
Hirsch
Jan
J
Galietta
Luis J V
LJ
Pedemonte
Nicoletta
N
Zemans
Rachel L
RL
Dolganov
Gregory
G
Verkman
A S
AS
Matthay
Michael A
MA
D001693:Biological Transport, Active; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000502:physiology; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000037:antagonists & inhibitors / Q000502:physiology*; D017097:Electric Impedance; D004847:Epithelial Cells / Q000378:metabolism*; D053503:Epithelial Sodium Channels; D020869:Gene Expression Profiling; D006801:Humans; D010539:Permeability; D010641:Phenotype; D011650:Pulmonary Alveoli / Q000166:cytology* / Q000378:metabolism; D015222:Sodium Channels / Q000502:physiology
C505032:CFTR protein, human; D053503:Epithelial Sodium Channels; D015222:Sodium Channels; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D000242:Cyclic AMP