ABCMdb

PMID: 22210114

Dong Q, Ostedgaard LS, Rogers C, Vermeer DW, Zhang Y, Welsh MJ
Human-mouse cystic fibrosis transmembrane conductance regulator (CFTR) chimeras identify regions that partially rescue CFTR-DeltaF508 processing and alter its gating defect.
Proc Natl Acad Sci U S A. 2012 Jan 17;109(3):917-22. Epub 2011 Dec 30., [PubMed]

Sentences

No. Mutations Sentence Comment

8 ABCC7 p.Ile539Thr This distinction was exemplified by the I539T mutation, which improved CFTR- ΔF508 processing but worsened the gating defect. Login to comment 52 ABCC7 p.Ile539Thr Previous reports indicated that an I539T mutation partially improved hCFTR-ΔF508 processing (18-20). Login to comment 54 ABCC7 p.Ile539Thr In addition, we found that combining I539T with human-mouse RE (hmRE) caused hCFTR-ΔF508 to produce more band C than either substitution alone. Login to comment 55 ABCC7 p.Ile539Thr Moreover, the proportion of band C in the chimera containing hmRE plus I539T was similar to that obtained when the entire mNBD1- ΔF508 replaced the human domain. Login to comment 62 ABCC7 p.Ile539Thr ABCC7 p.Ile539Thr Of all the chimeras, only hmMSD2 prevented B C D * * * * ** † C B Wild-type ΔF508 mCFTR hmNBD1 hCFTR hmNBD2 hmMSD2 hmMSD1 hmRI1 hmRI2 hmCenter hmRE hmRI1/RE I539T hmRE/I539T A Chimeras hCFTR Boundary hmNBD1 389-671 hmNBD2 1169-1480 hmMSD1 58-388 hmMSD2 837-1177 hmRI1 389-432 hmRI2 404-436 hmRE 633-671 hmRI1/RE 389-432, 633-671 hmCenter 434-632 WT ΔF WT ΔF WT ΔF WT ΔF WT ΔF WT ΔF WT ΔF WT ΔF WT ΔF WT ΔF WT ΔF WT ΔF WT ΔF Fig. 1. Login to comment 74 ABCC7 p.Ile539Thr ABCC7 p.Ile539Thr ABCC7 p.Ile539Thr † Difference in hmRE/I539T compared with hmRE and I539T (P < 0.05) (hCFTR, n = 15; mCFTR, n = 13; hmNBD1, n = 11; hmNBD2, n = 6; hmMSD1, n = 3; hmMSD2, n = 7; hmRI1, n = 3; hmRI2, n = 2; hmRE, n = 7; hmRI1/RE, n = 5; human-mouse Center, n = 6; hI539T, n = 4; hmRE/I539T, n = 4). Login to comment 77 ABCC7 p.Ile539Thr Interestingly, the I539T mutation, which minimized the effect of ΔF508 on processing, actually accentuated the ΔF508-induced gating defect (Fig. 2A). Login to comment 89 ABCC7 p.Pro1072Thr In ICL4, we found that substituting the human P1072 with the mouse T1072 (P1072T) (Fig. 4A) prevented ΔF508 from further increasing the interburst interval (Fig. 4B). Login to comment 90 ABCC7 p.Gly1069Arg ABCC7 p.Pro1072Ala The P1072A and G1069R variants failed to prevent a ΔF508 effect on interburst interval. Login to comment 94 ABCC7 p.Ile539Thr ABCC7 p.Ile539Thr If that were the case, we rea- hmNBD1 hmRE hmRE/I539T hmRI1/RE mCFTR hCFTR I539T hmRI1 hmRI2 hmCenter Wild-type ΔF508 A C B hmNBD2 hmMSD1 hmMSD2 Fig. 2. Login to comment 112 ABCC7 p.Pro1072Thr Indeed, an mNBD2 eliminated the protective effect of the ICL3 mutation (LNT964-966ISK), and an mNBD1 eliminated the protective effect of the ICL4 mutant P1072T (Fig. 4B). Login to comment 117 ABCC7 p.Ile539Thr However, mutating I539 to the mouse sequence also partially rescued processing, and the mouse RE and I539T were additive in their effects. Login to comment 120 ABCC7 p.Ile539Thr ABCC7 p.Gly550Glu ABCC7 p.Arg553Met ABCC7 p.Arg555Lys (i) A genetic approach identified second-site suppressor mutations, including I539T, G550E, R553M/Q, and R555K (18-21, 25, 26). Login to comment 153 ABCC7 p.Ile539Thr This distinction was exemplified by the I539T mutation. Login to comment 154 ABCC7 p.Ile539Thr I539T improved processing; however, it not only failed to prevent the ΔF508 gating defect but actually further prolonged the interburst interval. Login to comment 155 ABCC7 p.Gly1069Arg ABCC7 p.Pro1072Thr ABCC7 p.Pro1072Thr ABCC7 p.Pro1072Thr ABCC7 p.Pro1072Ala Other substitutions increased the Po of CFTR-ΔF508 by lengthening the burst duration rather than preventing ΔF508 from A G1069R P1072T hmMSD2 mCFTR hCFTR LNT964-966ISK LNT964-966AAA P1072A hmNBD1/P1072T hmNBD2/P1072T Wild-type ΔF508 D C B hmNBD1 LNT964-966ISK hmNBD2 LNT964-966ISK Fig. 4. Login to comment 167 ABCC7 p.Gly550Glu ABCC7 p.Arg555Lys Other examples are the G550E and R555K mutations, which also partially rescued CFTR-ΔF508 processing and increased the Po by lengthening the burst duration. Login to comment 168 ABCC7 p.Gly550Glu Although ΔF508 lengthened the interburst interval for both mutations, G550E reduced the magnitude of that increase (21, 26). Login to comment 169 ABCC7 p.Gly550Glu ABCC7 p.Arg553Met ABCC7 p.Arg553Lys In addition, a variant that combined G550E with R553M and R553K increased processing and current, although the effect on channel kinetics was not tested (33). Login to comment 178 ABCC7 p.Ile539Thr First, finding that I539T enhanced ΔF508-CFTR processing but reduced its channel activity suggests that a drug screening strategy that only detects cell surface CFTR- ΔF508 might miss adverse consequences for channel function. Login to comment 181 ABCC7 p.Ile539Thr In addition, finding that hmRE and I539T together improved CFTR- ΔF508 processing more than either alone suggests that simultaneously targeting more than one NBD1 site might be beneficial. Login to comment 266 ABCC7 p.Gly550Glu Roxo-Rosa M, et al. (2006) Revertant mutants G550E and 4RK rescue cystic fibrosis mutants in the first nucleotide-binding domain of CFTR by different mechanisms. Login to comment 281 ABCC7 p.Pro574His Protein Sci 19: 1932-1947. 35. Ostedgaard LS, Zeiher B, Welsh MJ (1999) Processing of CFTR bearing the P574H mutation differs from wild-type and ΔF508-CFTR. Login to comment