ABCMdb

PMID: 15141088

Cormet-Boyaka E, Jablonsky M, Naren AP, Jackson PL, Muccio DD, Kirk KL
Rescuing cystic fibrosis transmembrane conductance regulator (CFTR)-processing mutants by transcomplementation.
Proc Natl Acad Sci U S A. 2004 May 25;101(21):8221-6. Epub 2004 May 12., 2004-05-25 [PubMed]

Sentences

No. Mutations Sentence Comment

5 ABCC7 p.His1085Arg ABCC7 p.His1085Arg This transcomplementation effect required a specific match between the region flanking the disease-causing mutation and the complementing fragment; e.g., amino fragments complemented ⌬F508-CFTR but not H1085R (a carboxy- processing mutant), whereas a carboxy fragment complemented H1085R but not ⌬F508-CFTR. Login to comment 80 ABCC7 p.Glu60Ala Figs. 1 D and E show that the steady-state amount of mature ⌬F508-CFTR protein can be enhanced substantially by coexpressing this mutant with the N-tail processing mutants (e.g., E60A-CFTR) in COS-7 cells by using a strong viral expression system (vaccinia virus). Login to comment 128 ABCC7 p.Ala455Glu To gauge the potential physiologic significance of this transcomplementation effect, we compared the transport activity and the amount of mature ⌬F508-CFTR protein that could be induced by transcomplementation to that observed for a partial processing mutant that associates with mild CF (A455E) (21). Login to comment 129 ABCC7 p.Ala455Glu Although the transport activity and the amount of mature protein for the rescued ⌬F508-CFTR was considerably less than that observed for wild-type CFTR, both parameters were similar to that detected for the A455E mutant (Fig. 3 C and D). Login to comment 130 ABCC7 p.Ala455Glu The A455E mutant associates with a mild phenotype presumably because it retains partial function [it has been reported that only 5-10% of ''normal`` CFTR activity is required to prevent severe disease (22, 23)]. Login to comment 146 ABCC7 p.His1085Arg All results are representative of 3-10 experiments. by comparing the transcomplementation of the ⌬F508-CFTR mutant to that of a severe processing mutant (H1085R-CFTR) for which the mutation resides in the carboxy-terminal half of the protein (27). Login to comment 147 ABCC7 p.His1085Arg Unlike for ⌬F508-CFTR, the processing of H1085R-CFTR could not be rescued by coexpression with the 1-633 amino fragment (Figs. 4 D and F). Login to comment 148 ABCC7 p.His1085Arg Importantly, however, H1085R-CFTR could be transcomplemented by a carboxy-terminal fragment (837-1,480), which had no effect on the processing of ⌬F508-CFTR or the N-tail processing mutants (Figs. 4 D, E, and F). Login to comment 160 ABCC7 p.Ala455Glu (C) Rescued ⌬F508-CFTR exhibits macroscopic transport activity comparable to that of A455E-CFTR, a partial processing mutant associated with mild disease. Login to comment 163 ABCC7 p.Ala455Glu (Inset) Enlarged view of the permeability responses of cells transfected with A455E () or cotransfectedwithfragment1-633and⌬F508-CFTR(ƒ)tothecAMPmixture. Login to comment 164 ABCC7 p.Ala455Glu (D) Biochemical analysis of the band C forms of transcomplemented ⌬F508-CFTR and A455E-CFTRintransfectedCOS-7cells.Cellswereanalyzedforproteinexpression 48 h after transfection as described in Methods. Login to comment 170 ABCC7 p.His1085Arg (D) ⌬F508-CFTR was not transcomplemented by a carboxy fragment (837-1,480), whereas H1085R-CFTR, a cytosolic-loop-4-processing mutant that associates with severe disease, was complemented by fragment 837-1,480 but not by fragment 1-633. Login to comment 193 ABCC7 p.His1085Arg We thank M. J. Welsh for the H1085R-CFTR construct. Login to comment