Trafficking of GFP-tagged ΔF508-CFTR to the plasma membrane in a polarized epithelial cell line

D Loffing-Cueni, J Loffing, C Shaw… - … of Physiology-Cell …, 2001 - journals.physiology.org
D Loffing-Cueni, J Loffing, C Shaw, AM Taplin, M Govindan, CR Stanton, BA Stanton
American Journal of Physiology-Cell Physiology, 2001journals.physiology.org
The ΔF508 mutation reduces the amount of cystic fibrosis transmembrane conductance
regulator (CFTR) expressed in the plasma membrane of epithelial cells. However, a reduced
temperature, butyrate compounds, and “chemical chaperones” allow ΔF508-CFTR to traffic
to the plasma membrane and increase Cl− permeability in heterologous and nonpolarized
cells. Because trafficking is affected by the polarized state of epithelial cells and is cell-type
dependent, our goal was to determine whether these maneuvers induce ΔF508-CFTR …
The ΔF508 mutation reduces the amount of cystic fibrosis transmembrane conductance regulator (CFTR) expressed in the plasma membrane of epithelial cells. However, a reduced temperature, butyrate compounds, and “chemical chaperones” allow ΔF508-CFTR to traffic to the plasma membrane and increase Cl permeability in heterologous and nonpolarized cells. Because trafficking is affected by the polarized state of epithelial cells and is cell-type dependent, our goal was to determine whether these maneuvers induce ΔF508-CFTR trafficking to the apical plasma membrane in polarized epithelial cells. To this end, we generated and characterized a line of polarized Madin-Darby canine kidney (MDCK) cells stably expressing ΔF508-CFTR tagged with green fluorescent protein (GFP). A reduced temperature, glycerol, butyrate, or DMSO had no effect on 8-(4-chlorophenylthio)-cAMP (CPT-cAMP)-stimulated transepithelial Cl secretion across polarized monolayers. However, when the basolateral membrane was permeabilized, butyrate, but not the other experimental maneuvers, increased the CPT-cAMP-stimulated Cl current across the apical plasma membrane. Thus butyrate increased the amount of functional ΔF508-CFTR in the apical plasma membrane. Butyrate failed to stimulate transepithelial Cl secretion because of inhibitory effects on Cl uptake across the basolateral membrane. These observations suggest that studies on heterologous and nonpolarized cells should be interpreted cautiously. The GFP tag on ΔF508-CFTR will allow investigation of ΔF508-CFTR trafficking in living, polarized MDCK epithelial cells in real time.
American Physiological Society