ABCMdb

PMID: 21647592

Kongsuphol P, Schreiber R, Kraidith K, Kunzelmann K
CFTR induces extracellular acid sensing in Xenopus oocytes which activates endogenous Ca(2)-activated Cl conductance.
Pflugers Arch. 2011 Sep;462(3):479-87. Epub 2011 Jun 7., [PubMed]

Sentences

No. Mutations Sentence Comment

6 ABCC7 p.Gly551Asp The gating mutant G551D-CFTR conferred proton sensitivity, while deltaF508-CFTR enabled proton activation of TMEM16A only in Xenopus oocytes, which, unlike HEK293 cells, allow deltaF508-CFTR to be trafficked to the cell membrane. Login to comment 8 ABCC7 p.Glu1474* Because expression of CFTR-E1474X did not confer proton sensitivity, we propose that CFTR translocates a proton receptor to the plasma membrane via its PDZ-binding domain. Login to comment 32 ABCC7 p.Gly551Asp Oocytes were injected with 10 ng (47 nl double-distilled water) of cRNA encoding wt, ΔF508, or G551D CFTR. Login to comment 68 ABCC7 p.Gly551Asp Moreover, the gating mutant G551D-CFTR also produced a similar whole cell conductance upon extracellular acidosis (Fig. 1b-e). Login to comment 69 ABCC7 p.Gly551Asp ABCC7 p.Gly551Asp IBMX/forskolin had little effects on G551D-CFTR, while genistein (50 μM) activated a G551D-CFTR conductance of 16.1±2.3 nS (n=5; Fig. 1d, e). Login to comment 70 ABCC7 p.Gly551Asp Taken together, expression of wtCFTR, ΔF508-CFTR, and G551D-CFTR enable activation of an outwardly rectifying conductance by extracellular acidosis that is not observed in non-transfected or mock-transfected cells. Login to comment 83 ABCC7 p.Gly551Asp b Original recordings from oocytes injected with water (control) or expressing wtCFTR, ΔF508-CFTR, or G551D-CFTR before and after exposure to acidic extracellular bath solution (pH 5.5). Login to comment 85 ABCC7 p.Gly551Asp d Original recordings from oocytes injected with water (control) or expressing wtCFTR, ΔF508-CFTR, or G551D-CFTR before and after stimulation with IBMX (1 mM) and forskolin (2 μM) (black bars). Login to comment 119 ABCC7 p.Gly551Asp Similar results were obtained for ΔF508-CFTR and G551D-CFTR (Fig. 8c, d). Login to comment 121 ABCC7 p.Glu1474* In order to further support the concept of membrane translocation of a proton receptor by CFTR, we expressed a C-terminally truncated CFTR that lacks of the PDZBD (CFTR-E1474X) and that should no longer be able Fig. 6 The H+ -activated current is blocked by inhibitors of CaCC. a Original recording obtained from an oocyte expressing wtCFTR and exposed to extracellular pH 5.5 in the absence or presence of DIDS (100 μM) or NFA (100 μM). Login to comment 133 ABCC7 p.Glu1474* When expressed in Xenopus oocytes, CFTR-E1474X generated a cAMP-activated whole cell conductance of 23±3.2 μS (n=6), indicating membrane expression of functional CFTR. Login to comment 134 ABCC7 p.Glu1474* However, in the presence of CFTR-E1474X, Ca2+ - activated Cl- currents-conductance were no longer activated by extracellular acidic pH (ΔG=0±0.1 μS; n=6). Login to comment 139 ABCC7 p.Gly551Asp Activation of CaCC was independent of stimulation of CFTR and was also found for the gating mutant G551D-CFTR and for the trafficking mutant ΔF508-CFTR. Login to comment 140 ABCC7 p.Gly551Asp G551D-CFTR is a CFTR mutant which is well expressed in cell membranes but does not open upon stimulation with cAMP/PKA [5, 35]. Login to comment 143 ABCC7 p.Gly551Asp b Summary of whole cell conductances obtained from control oocytes and from wtCFTR-expressing oocytes exposed to LPA in the presence of extracellular pH 7.5 or pH 5.5. c Original current recordings from oocytes expressing ΔF508-CFTR or G551D-CFTR when exposed to extracellular LPA. Login to comment 144 ABCC7 p.Gly551Asp d Summary of whole cell conductances obtained from oocytes expressing ΔF508-CFTR or G551D-CFTR when exposed to LPA in the presence of extracellular pH 7.5 or pH 5.5. Login to comment