Analysis of ClC-2 channels as an alternative pathway for chloride conduction in cystic fibrosis airway cells

被引:106
作者
Schwiebert, EM
Cid-Soto, LP
Stafford, D
Carter, M
Blaisdell, CJ
Zeitlin, PL
Guggino, WB
Cutting, GR
机构
[1] Johns Hopkins Univ, Sch Med, Ctr Med Genet, Baltimore, MD 21287 USA
[2] Johns Hopkins Univ, Sch Med, Dept Physiol, Baltimore, MD 21287 USA
[3] Johns Hopkins Univ, Sch Med, Dept Pediat, Baltimore, MD 21287 USA
关键词
D O I
10.1073/pnas.95.7.3879
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
Cystic fibrosis (CF) is a lethal inherited disease that results from abnormal chloride conduction in epithelial tissues, ClC-2 chloride channels are expressed in epithelia affected by CF and may provide a key "alternative" target for pharmacotherapy of this disease. To explore this possibility, the expression level of ClC-2 channels was genetically manipulated in airway epithelial cells derived from a cystic fibrosis patient (IB3-1), Whole-cell patch-clamp analysis of cells overexpressing ClC-2 identified hyperpolarization-activated Cl- currents (HACCs) that displayed time-and voltage-dependent activation, and an inwardly rectifying steady-state current-voltage relationship. Reduction. of extracellular pH to 5.0 caused significant increases in HACCs in overexpressing cells, and the appearance of robust currents in parental IB3-1 cells, IB3-1 cells stably transfected with the antisense ClC-2 cDNA showed reduced expression of ClC-2 compared with parental cells by Western blotting, and a significant reduction in the magnitude of pa-dependent HACCs. To determine whether changes in extracellular pH alone could initiate chloride transport via ClC-2 channels, we performed Cl-36(-) efflux studies on overexpressing cells and cells with endogenous expression of ClC-2. Acidic extracellular pH increased Cl-36(-) efflux rates in both cell types, although the ClC-2 overexpressing cells had significantly greater chloride conduction and a longer duration of efflux than the parental cells, Compounds that exploit the pH mechanism of activating endogenous ClC-2 channels may provide a pharmacologic option for increasing chloride conductance in the airways of CF patients.
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页码:3879 / 3884
页数:6
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