Increases in cytosolic Ca2+ induce dynamin- and calcineurin-dependent internalisation of CFTR.
Cell Mol Life Sci
; 76(5): 977-994, 2019 Mar.
Article
in En
| MEDLINE
| ID: mdl-30547226
ABSTRACT
The cystic fibrosis transmembrane conductance regulator (CFTR) is a cAMP-regulated, apical anion channel that regulates ion and fluid transport in many epithelia including the airways. We have previously shown that cigarette smoke (CS) exposure to airway epithelia causes a reduction in plasma membrane CFTR expression which correlated with a decrease in airway surface hydration. The effect of CS on CFTR was dependent on an increase in cytosolic Ca2+. However, the underlying mechanism for this Ca2+-dependent, internalisation of CFTR is unknown. To gain a better understanding of the effect of Ca2+ on CFTR, we performed whole cell current recordings to study the temporal effect of raising cytosolic Ca2+ on CFTR function. We show that an increase in cytosolic Ca2+ induced a time-dependent reduction in whole cell CFTR conductance, which was paralleled by a loss of cell surface CFTR expression, as measured by confocal and widefield fluorescence microscopy. The decrease in CFTR conductance and cell surface expression were both dynamin-dependent. Single channel reconstitution studies showed that raising cytosolic Ca2+ per se had no direct effect on CFTR. In fact, the loss of CFTR plasma membrane activity correlated with activation of calcineurin, a Ca2+-dependent phosphatase, suggesting that dephosphorylation of CFTR was linked to the loss of surface expression. In support of this, the calcineurin inhibitor, cyclosporin A, prevented the Ca2+-induced decrease in cell surface CFTR. These results provide a hitherto unrecognised role for cytosolic Ca2+ in modulating the residency of CFTR at the plasma membrane through a dynamin- and calcineurin-dependent mechanism.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Calcium
/
Cystic Fibrosis Transmembrane Conductance Regulator
/
Calcineurin
/
Cytosol
/
Dynamins
Limits:
Humans
Language:
En
Journal:
Cell Mol Life Sci
Journal subject:
BIOLOGIA MOLECULAR
Year:
2019
Document type:
Article
Affiliation country:
United kingdom