The hypertonic environment differentially regulates wild-type CFTR and TNR-CFTR chloride channels.
This study tested the hypotheses that the hypertonic environment of the renal medulla regulates the expression of cystic fibrosis transmembrane conductance regulator protein (CFTR) and its natural splice variant, TNR-CFTR. To accomplish this, Madin-Darby canine kidney (MDCK) stable cell lines expressing TNR-CFTR or CFTR were used. The cells were treated with hypertonic medium made with either NaCl or urea or sucrose (480 mOsm/kg or 560 mOsm/kg) to mimic the tonicity of the renal medulla environment. Western blot data showed that CFTR and TNR-CFTR total cell protein is increased by hypertonic medium, but using the surface biotinylation technique, only CFTR was found to be increased in cell plasma membrane. Confocal microscopy showed TNR-CFTR localization primarily at the endoplasmic reticulum and plasma membrane. In conclusion, CFTR and TNR-CFTR have different patterns of distribution in MDCK cells and they are modulated by a hypertonic environment, suggesting their physiological importance in renal medulla.
Department of Physiology, The Johns Hopkins University, School of Medicine, Baltimore, MD, USA.
Roberta M
RM
Lassance-Soares
Jie
J
Cheng
Kristina
K
Krasnov
Liudmila
L
Cebotaru
Garry R
GR
Cutting
Jackson
J
Souza-Menezes
Marcelo M
MM
Morales
William B
WB
Guggino
D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000032:analysis / Q000378:metabolism*; D004285:Dogs; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006982:Hypertonic Solutions / Q000494:pharmacology*; D018613:Microscopy, Confocal; D020033:Protein Isoforms / Q000032:analysis / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology; D013395:Sucrose / Q000494:pharmacology; D014508:Urea / Q000494:pharmacology
D006982:Hypertonic Solutions; D020033:Protein Isoforms; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D012965:Sodium Chloride; D013395:Sucrose; D014508:Urea