ABCMdb

PMID: 23463513

Cebotaru L, Woodward O, Cebotaru V, Guggino WB
Transcomplementation by a truncation mutant of cystic fibrosis transmembrane conductance regulator (CFTR) enhances DeltaF508 processing through a biomolecular interaction.
J Biol Chem. 2013 Apr 12;288(15):10505-12. doi: 10.1074/jbc.M112.420489. Epub 2013 Mar 5., [PubMed]

Sentences

No. Mutations Sentence Comment

9 ABCC7 p.Ser341Ala Further experiments with the conduction mutant S341A show conclusively that currents are indeed generated by rescued channel function of èc;F508 CFTR. Login to comment 20 ABCC7 p.Gly551Asp VX-770 is a potentiator, designed to activate CFTR gating mutants such as G551D (6). Login to comment 22 ABCC7 p.Gly551Asp For example, G551D mutant reaches the plasma membrane but has too little channel activity to support normal CFTR function (7). Login to comment 24 ABCC7 p.Gly551Asp VX-770 has had remarkable success in reducing pulmonary exacerbations, sweat chloride, and promoting weight gain in patients bearing the G551D mutation (8). Login to comment 28 ABCC7 p.Gly551Asp In an initial study of CF patients with èc;F508 CFTR, VX-809 (10) had a smaller effect on sweat chloride compared with the effect of VX-770 on G551D patients VX-770 (8), and did not show any effects on pulmonary function or rescue of èc;F508 CFTR in rectal biopsies. Login to comment 170 ABCC7 p.Ser341Ala To explore more definitely which form of CFTR is generating the currents, we utilized the conduction mutant S341A. Login to comment 173 ABCC7 p.Ser341Ala S341A has been shown to alter the ion selectivity of CFTR (30). Login to comment 174 ABCC7 p.Ser341Ala Fig. 9 shows that the S341A mutation in wild type CFTR dramatically reduces the whole cell currents without affecting protein expression. Login to comment 175 ABCC7 p.Ser341Ala With this result in hand, we then tested the double mutant èc;F508/ S341A CFTR (Fig 10). Login to comment 177 ABCC7 p.Ser341Ala Interestingly, when èc;27-264 CFTR containing the wild-type CFTR conduction pore and the double mutant èc;F508/ S341A CFTR are cotransfected there are again hardly any currents detected despite the presence of ample amounts of protein. Login to comment 187 ABCC7 p.Ser341Ala Functional study of S341A CFTR in CHO cells. Login to comment 188 ABCC7 p.Ser341Ala S341A CFTR-expressing CHO cells have smaller whole cell currents than CHO cells expressing Waf9; CFTR (A and B). Login to comment 189 ABCC7 p.Ser341Ala C, summary I/V data; afe;S.E. (S341A CFTR, red circles, n afd; 4; Waf9;CFTR, black squares, n afd; 3). Login to comment 201 ABCC7 p.Ser341Ala We showed in a previous study of èc;264 CFTR our earlier truncation mutant transfected into IB3-1 bronchial epithelial cells that single channel currents occurred with open probability and conductance similar to wild-type CFTR (17) but the exact origin of the currents was FIGURE10.Dualexpressionofèc;508CFTRandèc;27-264CFTRresultsinèc;F508CFTR-mediatedwholecellcurrents.Expressionofèc;508/S341ACFTRalong with èc;27-264 CFTR results in robust expression, with slightly elevated B and C bands as compared with èc;508 CFTR/èc;27-264 CFTR expression (A), but with reduced whole cell currents (B) as compared with currents from cells expressing èc;508 CFTR/èc;27-264 CFTR (B), consistent with the previously described conductance defect in S341A CFTR (34). Login to comment 202 ABCC7 p.Ser341Ala C, summary I/V data for CHO cells expressing èc;508/S341A CFTR and èc;27-264 CFTR (n afd; 7; red squares) and èc;508 CFTR and èc;27-264 CFTR (n afd; 5; black circles); afe; S.E. Login to comment 216 ABCC7 p.Ser341Ala In this study, we address this question with the conduction mutant S341A. Login to comment 218 ABCC7 p.Ser341Ala S341A has been shown to alter the ion selectivity of CFTR and the sensitivity to chloride channel blockers (30). Login to comment 220 ABCC7 p.Ser341Ala Because we could rescue the èc;F508/S341A CFTR protein but not rescue channel currents because of the altered conduction pore, results showed conclusively that the current is indeed generated by rescued èc;F508-CFTR channel gating. Login to comment