ABCMdb

ABCC7 p.Ala561Glu

Admin's notes:	Class II-III-VI (maturation defect, gating defect, reduced stability) Veit et al.
ClinVar:	c.1682C>A , p.Ala561Glu D , Pathogenic
CF databases:	c.1682C>A , p.Ala561Glu D , CF-causing ; CFTR1: This mutation was detected by DGGE followed by direct sequencing in one out of 53 non-[delta]F508 CF chromosomes of Portugese origin, associated with haplotype A. A561E was found neither in 28 normal chromosomes nor in 25 [delta]F508 CF chromosomes. The patient, a 17 year old girl who is a compound heterozygote for A561E and [delta]F508, presented at the age of 3 with both pulmonary and gastric symptoms. However, she has developed a mild/moderate CF phenotype.
Predicted by SNAP2:	C: N (61%), D: D (80%), E: N (66%), F: D (80%), G: D (59%), H: D (75%), I: D (71%), K: D (80%), L: D (80%), M: D (66%), N: D (71%), P: D (80%), Q: D (71%), R: D (80%), S: N (53%), T: D (59%), V: D (66%), W: D (85%), Y: D (80%),
Predicted by PROVEAN:	C: D, D: D, E: D, F: D, G: D, H: D, I: D, K: D, L: D, M: D, N: D, P: D, Q: D, R: D, S: D, T: D, V: D, W: D, Y: D,

[switch to compact view]
Comments [show]

II-III-VI (maturation defect, gating defect, reduced stability) <a href="https://www.ncbi.nlm.nih.gov/pubmed/26823392">Veit et al.</a>
admin on 2016-08-19 15:16:22

Publications
[hide] Insight in eukaryotic ABC transporter function by ... FEBS Lett. 2006 Feb 13;580(4):1064-84. Epub 2006 Jan 19. Frelet A, Klein M
Insight in eukaryotic ABC transporter function by mutation analysis.
FEBS Lett. 2006 Feb 13;580(4):1064-84. Epub 2006 Jan 19., 2006-02-13 [PMID:16442101]

Abstract [show]
With regard to structure-function relations of ATP-binding cassette (ABC) transporters several intriguing questions are in the spotlight of active research: Why do functional ABC transporters possess two ATP binding and hydrolysis domains together with two ABC signatures and to what extent are the individual nucleotide-binding domains independent or interacting? Where is the substrate-binding site and how is ATP hydrolysis functionally coupled to the transport process itself? Although much progress has been made in the elucidation of the three-dimensional structures of ABC transporters in the last years by several crystallographic studies including novel models for the nucleotide hydrolysis and translocation catalysis, site-directed mutagenesis as well as the identification of natural mutations is still a major tool to evaluate effects of individual amino acids on the overall function of ABC transporters. Apart from alterations in characteristic sequence such as Walker A, Walker B and the ABC signature other parts of ABC proteins were subject to detailed mutagenesis studies including the substrate-binding site or the regulatory domain of CFTR. In this review, we will give a detailed overview of the mutation analysis reported for selected ABC transporters of the ABCB and ABCC subfamilies, namely HsCFTR/ABCC7, HsSUR/ABCC8,9, HsMRP1/ABCC1, HsMRP2/ABCC2, ScYCF1 and P-glycoprotein (Pgp)/MDR1/ABCB1 and their effects on the function of each protein.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
313 [141] A561E protein mislocalization in the ER SDM, Tf of BHK cells, pulse chase experiments and Cl- efflux assay. Login to comment

[hide] Mutations in the nucleotide binding domain 1 signa... J Biol Chem. 2002 Sep 27;277(39):35896-905. Epub 2002 Jul 10. DeCarvalho AC, Gansheroff LJ, Teem JL
Mutations in the nucleotide binding domain 1 signature motif region rescue processing and functional defects of cystic fibrosis transmembrane conductance regulator delta f508.
J Biol Chem. 2002 Sep 27;277(39):35896-905. Epub 2002 Jul 10., 2002-09-27 [PMID:12110684]

Abstract [show]
The gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR), an ATP binding cassette (ABC) transporter that functions as a phosphorylation- and nucleotide-regulated chloride channel, is mutated in cystic fibrosis (CF) patients. Deletion of a phenylalanine at amino acid position 508 (DeltaF508) in the first nucleotide binding domain (NBD1) is the most prevalent CF-causing mutation and results in defective protein processing and reduced CFTR function, leading to chloride impermeability in CF epithelia and heterologous systems. Using a STE6/CFTRDeltaF508 chimera system in yeast, we isolated two novel DeltaF508 revertant mutations, I539T and G550E, proximal to and within the conserved ABC signature motif of NBD1, respectively. Western blot and functional analysis in mammalian cells indicate that mutations I539T and G550E each partially rescue the CFTRDeltaF508 defect. Furthermore, a combination of both revertant mutations resulted in a 38-fold increase in CFTRDeltaF508-mediated chloride current, representing 29% of wild type channel activity. The G550E mutation increased the sensitivity of CFTRDeltaF508 and wild type CFTR to activation by cAMP agonists and blocked the enhancement of CFTRDeltaF508 channel activity by 2 mm 3-isobutyl-1-methylxanthine. The data show that the DeltaF508 defect can be significantly rescued by second-site mutations in the nucleotide binding domain 1 region, that includes the LSGGQ consensus motif.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
241 It might, thus, be expected that these revertant mutations, identified by virtue of their effects to reverse the ⌬F508 defect, would be specific for suppression of ⌬F508. However, results by others suggest that G550E can partially rescue another processing-defective CF mutant, A561E (61). Login to comment
242 Possibly, the ⌬F508 and A561E mutations cause misfolding in a similar manner, allowing each to be partially compensated by G550E. Login to comment

[hide] Analysis by mass spectrometry of 100 cystic fibros... Hum Reprod. 2002 Aug;17(8):2066-72. Wang Z, Milunsky J, Yamin M, Maher T, Oates R, Milunsky A
Analysis by mass spectrometry of 100 cystic fibrosis gene mutations in 92 patients with congenital bilateral absence of the vas deferens.
Hum Reprod. 2002 Aug;17(8):2066-72., [PMID:12151438]

Abstract [show]
BACKGROUND: Limited mutation analysis for congenital bilateral absence of the vas deferens (CBAVD) has revealed only a minority of men in whom two distinct mutations were detected. We aimed to determine whether a more extensive mutation analysis would be of benefit in genetic counselling and prenatal diagnosis. METHODS: We studied a cohort of 92 men with CBAVD using mass spectrometry and primer oligonucleotide base extension to analyse an approximately hierarchical set of the most common 100 CF mutations. RESULTS: Analysis of 100 CF mutations identified 33/92 (35.9%) patients with two mutations and 29/92 (31.5%) with one mutation, compound heterozygosity accounting for 94% (31/33) of those with two mutations. This panel detected 12.0% more CBAVD men with at least one mutation and identified a second mutation in >50% of those considered to be heterozygotes under the two routine 25 mutation panel analyses. CONCLUSION: Compound heterozygosity of severe/mild mutations accounted for the vast majority of the CBAVD patients with two mutations, and underscores the value of a more extensive CF mutation panel for men with CBAVD. The CF100 panel enables higher carrier detection rates especially for men with CBAVD, their partners, partners of known CF carriers, and those with 'mild' CF with rarer mutations.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
20 Given the frequency of CF mutations, especially in the Caucasian population ( in 25), and the common request by CBAVD men to sire their own offspring by using surgical Table I. The 100 most common cystic fibrosis mutations listed by exon Mutationa Exonb Frequency (%)c G85E 3 0.1 394delTT 3 Swedish E60X 3 Belgium R75X 3 405ϩ1G→A Int 3 R117H 4 0.30 Y122X 4 French 457TAT→G 4 Austria I148T 4 Canada (French Canadian) 574delA 4 444delA 4 R117L 4 621ϩ1G→T Int 4 0.72 711ϩ1G→T Int 5 Ͼ0.1 712-1G→T Int 5 711ϩ5G→A Int 5 Italy (Caucasian) L206W 6a R347P 7 0.24 1078delT 7 Ͼ0.1 R334W 7 Ͼ0.1 1154InsTC 7 T338I 7 Italy R347H 7 Turkey Q359K/T360K 7 Israel (Georgian Jews) I336K 7 R352Q 7 G330X 7 S364P 7 A455E 9 0.20 I507 10 0.21 F508 10 66.02 1609delCA 10 Spain (Caucasian) V520F 10 Q493X 10 C524X 10 G480C 10 Q493R 10 1717-1G→A Int 10 0.58 R553X 11 0.73 G551D 11 1.64 G542X 11 2.42 R560T 11 Ͼ0.1 S549N 11 Q552X 11 Italy S549I 11 Israel (Arabs) A559T 11 African American R553G 11 R560K 11 1812-1G→A Int 11 A561E 12 E585X 12 Y563D 12 Y563N 12 1898ϩ1G→A Int 12 0.22 1898ϩ1G→C Int 12 2183AA→G 13 Italian 2184delA 13 Ͻ0.1 K710X 13 2143delT 13 Moscow (Russian) 2184InsA 13 1949del84 13 Spain (Spanish) 2176InsC 13 2043delG 13 2307insA 13 2789ϩ5G→A Int 14b Ͼ0.1 2869insG 15 S945L 15 Q890X 15 3120G→A 16 2067 Table I. continued Mutationa Exonb Frequency (%)c 3120ϩ1G→A Int 16 African American 3272-26A→G Int 17a R1066C 17b Portugal (Portugese) L1077P 17b R1070Q 17b Bulgarian W1089X 17b M1101K 17b Canada (Hutterite) R1070P 17b R1162X 19 0.29 3659delC 19 Ͼ0.1 3849G→A 19 3662delA 19 3791delC 19 3821delT 19 Russian Q1238X 19 S1235R 19 France, South S1196X 19 K1177R 19 3849ϩ10kbC→T Int 19 0.24 3849ϩ4A→G Int 19 W1282X 20 1.22 S1251N 20 Dutch, Belgian 3905insT 20 Swiss, Acadian, Amish G1244E 20 R1283M 20 Welsh W1282R 20 D1270N 20 S1255X 20 African American 4005ϩ1G→A Int 20 N1303K 21 1.34 W1316X 21 aMutations were chosen according to their frequencies (Cystic Fibrosis Genetic Analysis Consortium, 1994; Zielenski and Tsui, 1995; Estivill et al., 1997). Login to comment

[hide] Rapid detection of CFTR gene rearrangements impact... J Med Genet. 2004 Nov;41(11):e118. Niel F, Martin J, Dastot-Le Moal F, Costes B, Boissier B, Delattre V, Goossens M, Girodon E
Rapid detection of CFTR gene rearrangements impacts on genetic counselling in cystic fibrosis.
J Med Genet. 2004 Nov;41(11):e118., [PMID:15520400]

Abstract [show]

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
207 Gender Current age Phenotype Genotype Origin Age at diagnosis Pancr. status Lung disease Other Sweat test Allele 1 Allele 2 rearrangement involving exon(s) Parental Geographic 1 M 10 years 1 month PI Severe 114 F508del 1 Father North eastern Italy 2 M 16 years Birth PI Severe 130 A561E 2 Father Southern Italy 3 M 10 years 1 year PI Severe + R553X 17b Mother France 4 F 13 years 4 years PI Severe NP + F508del 14b-17b Father Eastern France 5 F 24 years 1 month PI Severe 100 F508del 17a-17b Mother ND 6 F 21 years Childhood PI Moderate + F508del 17a-17b Father Eastern France 7 M 35 years 1 year PI Severe CBAVD, NP 103 F508del 17a-17b Father Eastern France 8* 2 F Deceased at 2 and 6 months Birth PI Severe ND F508del 17a-17b Father Eastern France 9 F Deceased at 15 years 5 years PI Severe 300 1812- 1GRA 3-10,14b-16À Mother Kabylie (Algeria)/ Brittany (France) 10 M 37 years 37 years PS None CBAVD ND R117H(-7T) 1-24 Mother France 11 M Deceased at 31 years 3 months PI Severe DB 90 G542X 4-8 Mother Eastern France CBAVD, congenital bilateral absence of the vas deferens; DB, disseminated bronchiectasis; del, deletion; dup, duplication; F, female; M, male; NP, nasal polyposis; Pancr., pancreatic; PI, pancreatic insufficiency; PS, pancreatic sufficiency. Login to comment

[hide] Revertant mutants G550E and 4RK rescue cystic fibr... Proc Natl Acad Sci U S A. 2006 Nov 21;103(47):17891-6. Epub 2006 Nov 10. Roxo-Rosa M, Xu Z, Schmidt A, Neto M, Cai Z, Soares CM, Sheppard DN, Amaral MD
Revertant mutants G550E and 4RK rescue cystic fibrosis mutants in the first nucleotide-binding domain of CFTR by different mechanisms.
Proc Natl Acad Sci U S A. 2006 Nov 21;103(47):17891-6. Epub 2006 Nov 10., 2006-11-21 [PMID:17098864]

Abstract [show]
The revertant mutations G550E and 4RK [the simultaneous mutation of four arginine-framed tripeptides (AFTs): R29K, R516K, R555K, and R766K] rescue the cell surface expression and function of F508del-cystic fibrosis (CF) transmembrane conductance regulator (-CFTR), the most common CF mutation. Here, we investigate their mechanism of action by using biochemical and functional assays to examine their effects on F508del and three CF mutations (R560T, A561E, and V562I) located within a conserved region of the first nucleotide-binding domain (NBD1) of CFTR. Like F508del, R560T and A561E disrupt CFTR trafficking. G550E rescued the trafficking defect of A561E but not that of R560T. Of note, the processing and function of V562I were equivalent to that of wild-type (wt)-CFTR, suggesting that V562I is not a disease-causing mutation. Biochemical studies revealed that 4RK generates higher steady-state levels of mature CFTR (band C) for wt- and V562I-CFTR than does G550E. Moreover, functional studies showed that the revertants rescue the gating defect of F508del-CFTR with different efficacies. 4RK modestly increased F508del-CFTR activity by prolonging channel openings, whereas G550E restored F508del-CFTR activity to wt levels by altering the duration of channel openings and closings. Thus, our data suggest that the revertants G550E and 4RK might rescue F508del-CFTR by distinct mechanisms. G550E likely alters the conformation of NBD1, whereas 4RK allows F508del-CFTR to escape endoplasmic reticulum retention/retrieval mediated by AFTs. We propose that AFTs might constitute a checkpoint for endoplasmic reticulum quality control.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
1 Here, we investigate their mechanism of action by using biochemical and functional assays to examine their effects on F508del and three CF mutations (R560T, A561E, and V562I) located within a conserved region of the first nucleotide-binding domain (NBD1) of CFTR. Like F508del, R560T and A561E disrupt CFTR trafficking. Login to comment
2 G550E rescued the trafficking defect of A561E but not that of R560T. Login to comment
37 47 ͉ 17891-17896 and 4RK act by different mechanisms. To explore this possibility, we tested the effects of G550E and 4RK on three additional CF mutations within NBD1: R560T, A561E, and V562I.ʈ We selected for study these CF mutants because (i) these residues constitute a hot spot for disease-causing mutations (seven mutations are associated with these three residues࿣ ); (ii) A561E and R560T are the second and fourth most frequent mutations among Portuguese and Irish CF patients, respectively (28); (iii) like G550E and R555K (one of the 4RK mutants), these mutations affect residues located between the LSGGQ and Walker B motifs of NBD1, which are highly conserved across species; and (iv) they all lie within the same ␣-helix (H5; G550-Y563) within the ATP-binding cassette ␣-subdomain of NBD1 (29, 30). Login to comment
38 To test the hypothesis that G550E and 4RK act by different mechanisms, we used biochemical and functional assays to investigate how these revertants rescue F508del-, R560T-, A561E-, and V562I-CFTR. Login to comment
41 For the reasons outlined in the Introduction, we chose to analyze the CF mutations R560T, A561E, and V562I. Login to comment
42 Although we previously demonstrated that A561E is processed defectively (31), no trafficking data are available for mutations at R560 and V562. Login to comment
44 Fig. 1A demonstrates that like F508del- and A561E-CFTR, R560T-CFTR generated only a discrete Ϸ145 kDa band (band B). Login to comment
47 Next, we investigated whether the revertants G550E and 4RK rescue the defective biosynthesis of R560T- and A561E-CFTR. Login to comment
49 Fig. 1A shows that G550E and 4RK were much less effective at rescuing A561E-CFTR compared with their effects on F508del-CFTR. Login to comment
50 In fact, band C of both A561E-4RK- and A561E- G550E-CFTR was detected only after a 24 h incubation with 2 mM 4-phenylbutyrate (4-PB), an enhancer of CFTR expression through transcriptional activation (Fig. 1B) (32). Login to comment
51 Quantification of the data reveals that, after this treatment with 4-PB, Ϸ30% of A561E-CFTR was rescued by either revertant, whereas for F508del-CFTR the value was Ϸ65%. Login to comment
55 The mature form of CFTR (band C) was clearly observed for F508del- and A561E-CFTR (Fig. 1D) in the presence of G550E and 4RK, but G550E failed to correct the defective biosynthesis of R560T-CFTR (Fig. 1 A and D). Login to comment
70 (A) WB of total protein (30 ␮g) from BHK cells stably expressing wt-, F508del-, R560T-, A561E-, or V562I-CFTR, alone or in cis with 4RK and G550E. Login to comment
75 (D) BHK cells expressing F508del-, R560T-, or A561E-CFTR alone or in cis with the revertants 4RK and G550E were analyzed by CFTR IP after pulse-labeling for 3 h. Labeled arrows indicate the positions of bands A, B, and C. Thus, the higher steady-state levels of band C for 4RK variants of both wtand V562I-CFTR (Fig. 1A) are explained only in part by a slight (but not significant) increase in the efficiency of processing band B to band C. Surprised that the revertants did not exert stronger effects on the processing of CFTR, we wondered how they might influence CFTR Cl-channel function. Login to comment
79 Consistent with the biochemical data (Fig. 1), these agonists had no effect on F508del-, R560T-, or A561E-CFTR (Fig. 3 B-D) but evoked a striking efflux of I- from V562I-CFTR (Fig. 3E), which has a time course equivalent to that of wt-CFTR and 1.3-fold greater (Fig. 3F). Login to comment
84 In contrast to F508del-CFTR, G550E did not restore CFTR function to R560T and both revertants rescued only modestly the CFTR function of A561E (Fig. 3 C, D, and F). Login to comment
96 (A-E) Time courses of I-efflux from BHK cells stably expressing wt- (A), F508del- (B), R560T- (C), A561E- (D), and V562I- (E) CFTR in the absence and presence of the 4RK and G550E mutations. Login to comment
127 Like F508del, R560T and A561E disrupt CFTR processing, whereas V562I traffics normally to the cell surface, forming a Cl-channel with properties indistinguishable from those of wt-CFTR. Login to comment
128 The revertants 4RK and G550E rescue the cell surface expression of A561E, albeit not as effectively as F508del, whereas G550E is without effect on R560T. Login to comment
129 Of note, G550E, but not 4RK, rescues the defective channel gating of F508del, suggesting that G550E and 4RK rescue the expression and function of F508del by distinct mechanisms. To understand the structural basis by which R560T and A561E disrupt the processing of CFTR (refs. Login to comment
177 This explains the observed rescue of the cell surface expression of F508del- and A561E-CFTR by the 4RK revertant. Login to comment
178 However, such an explanation does not imply correction of the folding defects of F508del- and A561E-CFTR. Login to comment

[hide] Cystic fibrosis and formes frustes of CFTR-related... Respiration. 2007;74(3):241-51. Southern KW
Cystic fibrosis and formes frustes of CFTR-related disease.
Respiration. 2007;74(3):241-51., [PMID:17534127]

Abstract [show]
Cystic fibrosis (CF) is the commonest genetic cause of bronchiectasis in the Caucasian population. Since identification of the putative gene in 1989, the molecular basis of the condition has become clearer with characterisation of the unique pathophysiology. The small airways are the primary site of lung disease, with an intense but localised inflammatory picture, dominated by neutrophils. The clinical heterogeneity is explained to some degree by the distinct molecular consequences of the many mutations that have been recognised to affect the CF transmembrane conductance regulator (CFTR) gene; however other genes appear to modify the phenotype as well as environmental exposure. It has become increasingly apparent that certain conditions may result from CFTR dysfunction without fulfilling diagnostic criteria for CF. In some cases this may result in single organ disease for which the term CF (or CFTR)-related disease has been advocated. Congenital bilateral absence of the vas deferens is the most clearly characterised of these. In other cases where a mild CF phenotype is apparent, atypical CF is probably a better term. It remains unclear whether carrier status predisposes to certain conditions such as chronic rhinosinusitis or pancreatitis.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
60 Classes of CFTR mutations, with molecular and phenotypic consequences Class Molecular consequence Example Phenotypic consequence I nonsense or frameshift mutations that result in no significant protein product G542X typical CF phenotype II protein product does not negotiate intracellular trafficking pathways phe508del R1066C A561E typical CF phenotype III protein product transported to the cell membrane but no significant ion transport function G551D typical CF phenotype IV protein product transported to cell membrane and functions at a low level R117H R334W associated with pancreatic sufficiency V reduced mRNA expression, protein product normal 5T variant of intron poly T region. Login to comment

[hide] Cystic fibrosis in a southern Brazilian population... Clin Genet. 2007 Sep;72(3):218-23. Faucz FR, Gimenez J, Ramos MD, Pereira-Ferrari L, Estivill X, Raskin S, Casals T, Culpi L
Cystic fibrosis in a southern Brazilian population: characteristics of 90% of the alleles.
Clin Genet. 2007 Sep;72(3):218-23., [PMID:17718859]

Abstract [show]
Cystic fibrosis (CF) is a genetic disease that frequently leads to death in infancy among Europeans and their descendants. The goals of the present study were to analyze the molecular aspects of CFTR gene characterizing mutations, their frequencies, and the haplotypes formed by four CFTR gene intragenic markers, IVS8-6(T)n, IVS8CA, IVS17bTA and IVS17bCA, in a southern Brazilian population of Caucasian origin. DNA samples from 56 non-related CF patients were analyzed using scanning techniques (single strand conformation polymorphism and denaturing gradient gel electrophoresis), restriction fragment length polymorphism and direct DNA sequencing to identify the mutations. Our results revealed a total of 25 different CF mutations representing nearly 90% of CF alleles, two being novel mutations. Microsatellite haplotypes were defined for CF and normal alleles. The mutational spectrum and the associated haplotypes described for the first time in this study should prove relevant for genetic counselling and CF population screening in Brazil. Moreover, our results suggest the presence of a major Mediterranean component in the contemporary Brazilian CF patient pool.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
99 The fact that the mutation spectrum is closer to that found in Italian patients than in Portuguese patients is intriguing, although the Portuguese influence could be more subtle, considering that A561E, the second most common mutation in Portugal (3.2%) (10) was also found in our series (0.9%). Login to comment

[hide] CFTR mutations in cystic fibrosis patients from Mu... Clin Genet. 2009 Dec;76(6):577-9. Epub 2009 Oct 21. Moya-Quiles MR, Mondejar-Lopez P, Pastor-Vivero MD, Gonzalez-Gallego I, Juan-Fita MJ, Egea-Mellado JM, Carbonell P, Casals T, Fernandez-Sanchez A, Sanchez-Solis M, Glover G
CFTR mutations in cystic fibrosis patients from Murcia region (southeastern Spain): implications for genetic testing.
Clin Genet. 2009 Dec;76(6):577-9. Epub 2009 Oct 21., [PMID:19845690]

Abstract [show]

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
17 of chromosomes Frequency (%) F508dela E.10 67 36.8 G542Xa E.11 22 12.1 A1006E E.17a 10 5.5 K710X E.13 10 5.5 2789+5G>Aa I.14b 9 4.9 L206W E.6a 7 3.8 1811+1.6kbA>G I.11 6 3.3 R334Wa E.7 5 2.7 2869insG E.15 5 2.7 I507dela E.10 4 2.2 N1303Ka E.21 4 2.2 R347Pa E.7 3 1.6 711+1G>Ta I.5 3 1.6 3849+10kbC>Ta I.19 3 1.6 Q890X E.15 3 1.6 R117Ha E.4 2 1.1 R1162Xa E.19 2 1.1 2183AA>Ga E.13 2 1.1 A561E E.12 2 1.1 R560G E.11 2 1.1 1717-1G>Aa I.10 1 0.5 E1308X E.21 1 0.5 E585X E.12 1 0.5 L997F E.17a 1 0.5 1677delTA E.10 1 0.5 R1158X E.19 1 0.5 W202X E.6a 1 0.5 R74W+D1270N E.3 + E.20 1 0.5 G576A+R668C E.12 + E.13 1 0.5 Unknown 2 1.1 Total 182 100 aCFTR mutations identified with the PCR OLA CF Genotyping Assay . Login to comment

[hide] Detection of CFTR mutations using temporal tempera... Electrophoresis. 2004 Aug;25(15):2593-601. Wong LJ, Alper OM
Detection of CFTR mutations using temporal temperature gradient gel electrophoresis.
Electrophoresis. 2004 Aug;25(15):2593-601., [PMID:15300780]

Abstract [show]
Cystic fibrosis (CF), caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, is one of the most common autosomal recessive diseases with variable incidences and mutation spectra among different ethnic groups. Current commercially available mutation panels designed for the analysis of known recurrent mutations have a detection rate between 38 to 95%, depending upon the ethnic background of the patient. We describe the application of a novel mutation detection method, temporal temperature gradient gel electrophoresis (TTGE), to the study of the molecular genetics of Hispanic CF patients. TTGE effectively identified numerous rare and novel mutations and polymorphisms. One interesting observation is that the majority of the novel mutations are splice site, frame shift, or nonsense mutations that cause severe clinical phenotypes. Our data demonstrate that screening of the 27 exons and intron/exon junctions of the CFTR gene by TTGE greatly improves the molecular diagnosis of Hispanic CF patients.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
89 For example, the p.Q98X and p.Q98R mutations in exon 4; and p.S466X and p.S492F mutations in exon 10, were detected in the temperature range of 52-607C and 51- 577C, respectively. The p.G542X, p.R553X, p.S549N, and p.A559T in exon 11; p.A561E, c.189811G.A, and c.189813A.G in exon 12; and p.W1204X in exon 19; were detected in the temperature range of 51 to 567C. Login to comment
133 Identification of rare and novel mutations and polymorphisms Base substitution Mutation Exon or intron Homozygote or heterozygote Polymorphism or mutation # Alleles identified 1 c.124_146del23bp Frameshift 1 Heterozygote Mutation 1 2 c.296+2T>A Splice Int 2 Heterozygote Mutation 1 3 c.296+28A/G Int 2 Homozygote Polymorphism 2 4 c.355CT p.R75X 3 Heterozygote Mutation 2 5 c.360_365insT Frameshift 3 Heterozygote Mutation 1 6 c.379_381insT Frameshift 3 Heterozygote Mutation 1 7 c.406-1G>A Splice Int 4 Heterozygote Mutation 2 8 c.424C.T p.Q98X 4 Heterozygote Mutation 1 9 c.425A.G p.Q98R 4 Heterozygote Mutation 3 10 c.586A.G p.M152V 4 Homozygote Mutation 2 11 c.663delT Frameshift 5 Heterozygote Mutation 3 12 c.667C>A p.Q179K 5 Heterozygote Mutation, 1 13 c.745C.T p.P205S 6a Heterozygote Mutation 5 14 c.875140A/G 6a Heterozygote Polymorphism 11 15 c.935delA Frameshift 6b Heterozygote Mutation 2 16 c.124811G.A Splice Int 7 Heterozygote Mutation 2 17 c.1285ins TA Frameshift 8 Heterozygote Mutation 4 Homozygote Mutation 2 18 c.1342+196C/T Int 8 Heterozygote Polymorphism 4 Homozygote 2 19 c.1461insAGAT Frameshift 9 Heterozygote Mutation 1 20 c.1525-61A/G 10 Heterozygote Polymorphism 22 21 c.1529C.A/G p.S466X 10 Heterozygote Mutation 1 22 c.1607C.T p.S492F 10 Heterozygote Mutation 3 23 c.1814C.T p.A561E 12 Heterozygote Mutation 1 24 c.189813A.G Splice Int 12 Heterozygote Mutation 1 25 c.18981152T/A Int 12 Heterozygote Polymorphism 5 26 c.1924del 7bp Frameshift 13 Heterozygote Mutation 1 27 c.1949del84 Frameshift 13 Heterozygote Mutation 1 28 c.2055del9toA Frameshift 13 Homozygote Mutation 2 29 c.2105_2117 Frameshift 13 Heterozygote Mutation 4 del13insAGAAA 30 c.2108delA Frameshift 13 Heterozygote Mutation 1 31 c.2184insA Frameshift 13 Heterozygote Mutation 2 32 c.2184delA Frameshift 13 Heterozygote Mutation 1 33 c.2289_2295 Frameshift 13 Heterozygote Mutation 1 del7insGT 34 c.2694T.G p.T854T 14a Heterozygote Polymorphism 10 35 c.2752+12G/C Int 14a Heterozygote Polymorphism 2 36 c.2800C.T p.Q890X 15 Homozygote Mutation 2 37 c.3171delC Frameshift 17a Heterozygote Mutation 1 38 c.3179T>C p.F1016S 17a Heterozygote Mutation 1 39 c.3199del 6bp Frameshift 17a Heterozygote Mutation 1 40 c.3212T.C p.I1027T 17a Heterozygote Mutation 1 41 c.3272-26A.G Splice Int17a Heterozygote Mutation 4 42 c.3271delGG Frameshift 17a Heterozygote Mutation 1 43 c.3313G.C p.G1061R 17b Heterozygote Mutation 1 44 c.3328C.T p.R1066C 17b Heterozygote Mutation 2 45 c.3362T.C p.L1077P 17b Heterozygote Mutation 1 46 c.3431A.C p.Q1100P 17b Heterozygote Mutation 1 47 c.3500-2A>T Splice Int 17b Heterozygote Mutation 1 48 c.3743G.A p.W1204X 19 Heterozygote Mutation 1 Homozygote Mutation 2 49 c.3601-65C/A Int 19 Heterozygote Polymorphism 14 50 c.3863G.A p.G1244E 20 Heterozygote Mutation 3 Table 3. Login to comment

[hide] Spectrum of mutations in the CFTR gene in cystic f... Ann Hum Genet. 2007 Mar;71(Pt 2):194-201. Alonso MJ, Heine-Suner D, Calvo M, Rosell J, Gimenez J, Ramos MD, Telleria JJ, Palacio A, Estivill X, Casals T
Spectrum of mutations in the CFTR gene in cystic fibrosis patients of Spanish ancestry.
Ann Hum Genet. 2007 Mar;71(Pt 2):194-201., [PMID:17331079]

Abstract [show]
We analyzed 1,954 Spanish cystic fibrosis (CF) alleles in order to define the molecular spectrum of mutations in the CFTR gene in Spanish CF patients. Commercial panels showed a limited detection power, leading to the identification of only 76% of alleles. Two scanning techniques, denaturing gradient gel electrophoresis (DGGE) and single strand conformation polymorphism/hetroduplex (SSCP/HD), were carried out to detect CFTR sequence changes. In addition, intragenic markers IVS8CA, IVS8-6(T)n and IVS17bTA were also analyzed. Twelve mutations showed frequencies above 1%, p.F508del being the most frequent mutation (51%). We found that eighteen mutations need to be studied to achieve a detection level of 80%. Fifty-one mutations (42%) were observed once. In total, 121 disease-causing mutations were identified, accounting for 96% (1,877 out of 1,954) of CF alleles. Specific geographic distributions for the most common mutations, p.F508del, p.G542X, c.1811 + 1.6kbA > G and c.1609delCA, were confirmed. Furthermore, two other relatively common mutations (p.V232D and c.2789 + 5G > A) showed uneven geographic distributions. This updated information on the spectrum of CF mutations in Spain will be useful for improving genetic testing, as well as to facilitate counselling in people of Spanish ancestry. In addition, this study contributes to defining the molecular spectrum of CF in Europe, and corroborates the high molecular mutation heterogeneity of Mediterranean populations.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
52 Mutation 0.46-0.35 9 c.1078delT #, p.R347P # 8 p.G85V, c.621 + 1G > T #, p.S549R (T > G) #, p.R553X #, c.3849 + 10kbC > T # 7 p.R347H #, c.1812-1G > A, p.R709X 0.30-0.10 6 p.H199Y, p.P205S, 5 p.R117H #, p.G551D #, p.W1089X, p.Y1092X, CFTR50kbdel 4 c.296 + 3insT, c.1717-1G > A #, c.1949del84, c.3849 + 1G > A 3 p.E92K, c.936delTA, c.1717-8G > A, c.1341G > A, p.A561E, c.2603delT, p.G1244E, [p.D1270N; p.R74W] 2 p.Q2X, p.P5L, CFTRdele2,3, p.S50P, p.E60K, c.405 + 1G > A, c.1677delTA, p.L558S, p.G673X, p.R851X, p.Y1014C, p.Q1100P, p.M1101K, p.D1152H, CFTRdele19, p.G1244V, p.Q1281X, p.Y1381X <0,1 1 c.124del23bp, p.Q30X, p.W57X, c.406-1G > A, p.Q98R, p.E115del, c.519delT, p.L159S, c.711 + 3A > T, p.W202X, c.875 + 1G > A, p.E278del, p.W361R, c.1215delG, p.L365P, p.A399D, c.1548delG, p.K536X, p.R560G, c.1782delA, p.L571S, [p.G576A; p.R668C], p.T582R, p.E585X, c.1898 + 1G > A, c.1898 + 3A > G, c.2051delTT, p.E692X, p.R851L, c.2711delT, c.2751 + 3A > G, c.2752-26A > G, p.D924N, p.S945L, c.3121-1G > A, p.V1008D, p.L1065R, [p.R1070W; p.R668C], [p.F1074L; 5T], p.H1085R, p.R1158X, c.3659delC #, c.3667del4, c.3737delA, c.3860ins31, c.3905insT #, c.4005 + 1G > A, p.T1299I, p.E1308X, p.Q1313X, c.4095 + 2T > A, rearrangements study (n = 4) Mutations identified in CF families with mixed European origin: c.182delT, p.L1254X, c.4010del4. Login to comment

[hide] The K+ channel opener 1-EBIO potentiates residual ... PLoS One. 2011;6(8):e24445. Epub 2011 Aug 31. Roth EK, Hirtz S, Duerr J, Wenning D, Eichler I, Seydewitz HH, Amaral MD, Mall MA
The K+ channel opener 1-EBIO potentiates residual function of mutant CFTR in rectal biopsies from cystic fibrosis patients.
PLoS One. 2011;6(8):e24445. Epub 2011 Aug 31., [PMID:21909392]

Abstract [show]
BACKGROUND: The identification of strategies to improve mutant CFTR function remains a key priority in the development of new treatments for cystic fibrosis (CF). Previous studies demonstrated that the K(+) channel opener 1-ethyl-2-benzimidazolone (1-EBIO) potentiates CFTR-mediated Cl(-) secretion in cultured cells and mouse colon. However, the effects of 1-EBIO on wild-type and mutant CFTR function in native human colonic tissues remain unknown. METHODS: We studied the effects of 1-EBIO on CFTR-mediated Cl(-) secretion in rectal biopsies from 47 CF patients carrying a wide spectrum of CFTR mutations and 57 age-matched controls. Rectal tissues were mounted in perfused micro-Ussing chambers and the effects of 1-EBIO were compared in control tissues, CF tissues expressing residual CFTR function and CF tissues with no detectable Cl(-) secretion. RESULTS: Studies in control tissues demonstrate that 1-EBIO activated CFTR-mediated Cl(-) secretion in the absence of cAMP-mediated stimulation and potentiated cAMP-induced Cl(-) secretion by 39.2+/-6.7% (P<0.001) via activation of basolateral Ca(2)(+)-activated and clotrimazole-sensitive KCNN4 K(+) channels. In CF specimens, 1-EBIO potentiated cAMP-induced Cl(-) secretion in tissues with residual CFTR function by 44.4+/-11.5% (P<0.001), but had no effect on tissues lacking CFTR-mediated Cl(-) conductance. CONCLUSIONS: We conclude that 1-EBIO potentiates Cl(-)secretion in native CF tissues expressing CFTR mutants with residual Cl(-) channel function by activation of basolateral KCNN4 K(+) channels that increase the driving force for luminal Cl(-) exit. This mechanism may augment effects of CFTR correctors and potentiators that increase the number and/or activity of mutant CFTR channels at the cell surface and suggests KCNN4 as a therapeutic target for CF.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
46 CFabsent CFresidual CFTR genotype Number of individuals CFTR genotype Number of individuals F508del/F508del 10 F508del/Y161C 1 F508del/W57X 1 F508del/V232D 1 F508del/G85E 3 F508del/R334W 2 F508del/120del23 1 F508del/T338I 1 F508del/182delT 1 F508del/I1234V 1 F508del/G542X 1 F508del/3272-26 A.G 1 F508del/A561E 1 F508del/3849+10 kb C.T 1 F508del/Y1092X 1 F508del/4005 +5727 A.G 1 F508del/N1303K 1 F508del/G576A 1 F508del/1525-1 G.A 2 N1303K/R334W 1 F508del/Q39X 1 F1052V/M1137R 1 F508del/Q552X 1 1898+3 A.G/ 1898+3 A.G 1 G85E/G85E 1 R334W/3199del6 1 Q552X/R1162X 1 R334W/X 1 A561E/A561E 2 dele2,3/X 1 R764X/1717-1 G.A 1 R1158X/2183AA.G 1 R1158X/R560T 1 doi:10.1371/journal.pone.0024445.t001 luminal and basolateral surfaces of the epithelium were perfused continuously with a solution of the following composition (mmol/ L): NaCl 145, KH2PO4 0.4, K2HPO4 1.6, D-glucose 5, MgCl2 1, Ca-gluconate 1.3, pH 7.4, at 37uC. Login to comment

[hide] CFTR Cl- channel function in native human colon co... Gastroenterology. 2004 Oct;127(4):1085-95. Hirtz S, Gonska T, Seydewitz HH, Thomas J, Greiner P, Kuehr J, Brandis M, Eichler I, Rocha H, Lopes AI, Barreto C, Ramalho A, Amaral MD, Kunzelmann K, Mall M
CFTR Cl- channel function in native human colon correlates with the genotype and phenotype in cystic fibrosis.
Gastroenterology. 2004 Oct;127(4):1085-95., [PMID:15480987]

Abstract [show]
BACKGROUND & AIMS: Cystic fibrosis (CF) is caused by over 1000 mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene and presents with a widely variable phenotype. Genotype-phenotype studies identified CFTR mutations that were associated with pancreatic sufficiency (PS). Residual Cl- channel function was shown for selected PS mutations in heterologous cells. However, the functional consequences of most CFTR mutations in native epithelia are not well established. METHODS: To elucidate the relationships between epithelial CFTR function, CFTR genotype, and patient phenotype, we measured cyclic adenosine monophosphate (cAMP)-mediated Cl- secretion in rectal biopsy specimens from 45 CF patients who had at least 1 non-DeltaF508 mutation carrying a wide spectrum of CFTR mutations. We compared CFTR genotypes and clinical manifestations of CF patients who expressed residual CFTR-mediated Cl- secretion with patients in whom Cl- secretion was absent. RESULTS: Residual anion secretion was detected in 40% of CF patients, and was associated with later disease onset (P < 0.0001), higher frequency of PS (P < 0.0001), and less severe lung disease (P < 0.05). Clinical outcomes correlated with the magnitude of residual CFTR activity, which was in the range of approximately 12%-54% of controls. CONCLUSIONS: Specific CFTR mutations confer residual CFTR function to rectal epithelia, which is related closely to a mild disease phenotype. Quantification of rectal CFTR-mediated Cl- secretion may be a sensitive test to predict the prognosis of CF disease and identify CF patients who would benefit from therapeutic strategies that would increase residual CFTR activity.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
78 Relationship Between the CFTR Genotype and Cl- Channel Function in Native Rectal Epithelia CFTR genotype Number of individuals Sweat Cl-concentration (mmol/L)a cAMP-mediated response Carbachol-induced plateau response or maximal lumen-negative response Isc-cAMP (␮A/cm2) Cl- secretion (% of control) Isc-carbachol (␮A/cm2) Cl- secretion (% of control) Cl- secretion absent R1162X/Q552X 1 71 17.1 0 0.7 0 W1282X/3121-2AϾG 1 112 1.9 0 0.6 0 1898 ϩ 1G Ͼ T/1609delCA 2b 114, 118 25.4, 13.4 0, 0 0, 0.7 0, 0 ⌬F508/Q39X 2b 127, 129 2.6, 4.4 0, 0 1.7, 3.7 0, 0 ⌬F508/G542X 1 102 29.0 0 6.6 0 ⌬F508/R553X 3 112, 102, 109 13.1, 4.5, 23.8 0, 0, 0 1.5, 4.4, 1.0 0, 0, 0 ⌬F508/E585X 1 115 1.4 0 1.1 0 ⌬F508/Q637X 1 100 2.9 0 1.2 0 ⌬F508/Y1092X 1 119 0.0 0 -0.3 0 ⌬F508/120del23c 1 72 20.1 0 3.3 0 ⌬F508/182delT 1 116 10.8 0 5.2 0 ⌬F508/3905insT 2 88, 96 8.4, 5.6 0, 0 2.3, -1.1 0, 1 ⌬F508/V520F 1 68 1.2 0 1.7 0 ⌬F508/A561E 3 113, 146, 100 17.0, 17.0, 16.0 0, 0, 0 2.1, 1.5, 3.7 0, 0, 0 ⌬F508/R1066C 1 138 0.0 0 0.0 0 ⌬F508/N1303K 3 100, 117, 94 1.7, 4.1, 1.5 0, 0, 0 -0.6, 2.2, 0.8 0, 0, 0 A561E/A561E 2 101, 116 6.6, 2.0 0, 0 7.3, 3.3 0, 0 Residual Cl- secretiond G542X/I148N 1 75 -50.1 54 -22.2 12 1898 ϩ 3A Ͼ G/1898 ϩ 3A Ͼ G 1 82 -36.8 39 -12.9 7 ⌬F508/3272-26A Ͼ G 1 116 -17.8 19 -27.2 14 ⌬F508/S108F 1 118 -15.8 17 -12.3 7 ⌬F508/R117H 1 90 -35.9 38 -207.7 109 ⌬F508/Y161Cc 1 44 -35.1 37 -45.9 25 ⌬F508/P205S 1 80 -23.3 25 -10.4 5 ⌬F508/V232D 1 120 -16.9 18 -26.9 14 ⌬F508/R334W 1 92 -22.1 23 -21.1 11 ⌬F508/R334W 1 101 -24.5 26 -37.4 20 ⌬F508/T338I 1 73 -44.4 47 -79.4 42 ⌬F508/G576A 1 40 -16.9 18 -115.5 61 ⌬F508/I1234V 1 113 -13.6 15 -8.6 5 G576A/G85E 1 95 -26.1 28 -61.6 32 F1052V/M1137R 1 47 -36.7 39 -146.6 77 M1101K/M1101K 1 94 -11.1 12 -4.8 3 S1159F/S1159F 1 67 -47.9 51 -38.7 21 N1303K/R334W 1 91 -30.3 32 -47.7 25 NOTE. CFTR Cl- channel function was determined in rectal epithelia from Cl- secretory responses induced by IBMX/forskolin (Isc-cAMP) and after co-activation with carbachol (Isc-carbachol). Login to comment
101 Functional Classification and Protein Location of CFTR Mutations Mutation type Severe mutations (protein location) Mild mutations (protein location) Missense V520F, A561E (NBD1) G85E (MSD1, TM1) R1066C (MSD2, CL4) S108F, R117H (MSD1, EL1) N1303K (NBD2) I148N, Y161Ca (MSD1, CL1) P205S (MSD1, TM3) V232D (MSD1, TM4) R334W, T338I (MSD1, TM6) G576A (NBD1) I1234V (NBD2) F1052V, M1101K (MSD2, CL4) M1137R (MSD2, TM12) S1159F (pre-NBD2) Splice 1898 ϩ 1G Ͼ T (R domain) 1898 ϩ 3A Ͼ G (R domain) 3121-2A Ͼ G (MSD2, TM9) 3272-26A Ͼ G (MSD2, TM10) Single amino acid deletion ⌬F508 (NBD1) Nonsense Q39X (N-terminus) G542X, Q552X, R553X, E585X (NBD1) Q637X (R domain) Y1092X (MSD2, CL4) R1162X (pre-NBD2) W1282X (NBD2) Frameshift 120del23a 182delT (N-terminus) 1609delCA (NBD1) 3905insT (NBD2) NOTE. Severe mutation, Cl- secretion absent; mild mutation, residual cAMP-mediated Cl- secretion. Login to comment
114 CFTR-mediated Cl- secretion was absent (or below the level of detection) in all CF patients compound heterozygous for class I and II mutations, including ⌬F508, nonsense, frameshift, and missense mutations that result in defective processing (A561E, R1066C, Table 3. Login to comment

[hide] Spectrum of CFTR mutations in cystic fibrosis and ... Hum Mutat. 2000;16(2):143-56. Claustres M, Guittard C, Bozon D, Chevalier F, Verlingue C, Ferec C, Girodon E, Cazeneuve C, Bienvenu T, Lalau G, Dumur V, Feldmann D, Bieth E, Blayau M, Clavel C, Creveaux I, Malinge MC, Monnier N, Malzac P, Mittre H, Chomel JC, Bonnefont JP, Iron A, Chery M, Georges MD
Spectrum of CFTR mutations in cystic fibrosis and in congenital absence of the vas deferens in France.
Hum Mutat. 2000;16(2):143-56., [PMID:10923036]

Abstract [show]
We have collated the results of cystic fibrosis (CF) mutation analysis conducted in 19 laboratories in France. We have analyzed 7, 420 CF alleles, demonstrating a total of 310 different mutations including 24 not reported previously, accounting for 93.56% of CF genes. The most common were F508del (67.18%; range 61-80), G542X (2.86%; range 1-6.7%), N1303K (2.10%; range 0.75-4.6%), and 1717-1G>A (1.31%; range 0-2.8%). Only 11 mutations had relative frequencies >0. 4%, 140 mutations were found on a small number of CF alleles (from 29 to two), and 154 were unique. These data show a clear geographical and/or ethnic variation in the distribution of the most common CF mutations. This spectrum of CF mutations, the largest ever reported in one country, has generated 481 different genotypes. We also investigated a cohort of 800 French men with congenital bilateral absence of the vas deferens (CBAVD) and identified a total of 137 different CFTR mutations. Screening for the most common CF defects in addition to assessment for IVS8-5T allowed us to detect two mutations in 47.63% and one in 24.63% of CBAVD patients. In a subset of 327 CBAVD men who were more extensively investigated through the scanning of coding/flanking sequences, 516 of 654 (78. 90%) alleles were identified, with 15.90% and 70.95% of patients carrying one or two mutations, respectively, and only 13.15% without any detectable CFTR abnormality. The distribution of genotypes, classified according to the expected effect of their mutations on CFTR protein, clearly differed between both populations. CF patients had two severe mutations (87.77%) or one severe and one mild/variable mutation (11.33%), whereas CBAVD men had either a severe and a mild/variable (87.89%) or two mild/variable (11.57%) mutations.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
108 g D44G, 300delA, W57X, 405+1G>A, D110H, E116K, 541del4, 542del7, L137R, 621+2T>G, I175V, H199R, H199Y, C225X, V232D, Q290X, E292X, G314V, T338I, 1221delCT, W401X, Q452P, I502T, 1716+2T>C, G544S, R560S, A561E, V562I, Y569D, 1898+3A>G, 1898+5G>A, G628R(G>A), 2143delT, G673X, R851X, Q890X, S977F, 3129del4, 3154delG, 3271+1G>A, G1061R, R1066L, R1070W, 3601-17T>C, S1196X, 3732delA, G1249R, 3898insC, 4374+1G>A, del25kb. Login to comment

[hide] High heterogeneity for cystic fibrosis in Spanish ... Hum Genet. 1997 Dec;101(3):365-70. Casals T, Ramos MD, Gimenez J, Larriba S, Nunes V, Estivill X
High heterogeneity for cystic fibrosis in Spanish families: 75 mutations account for 90% of chromosomes.
Hum Genet. 1997 Dec;101(3):365-70., [PMID:9439669]

Abstract [show]
We have analyzed 640 Spanish cystic fibrosis (CF) families for mutations in the CFTR gene by direct mutation analysis, microsatellite haplotypes, denaturing gradient gel electrophoresis, single-strand conformation analysis and direct sequencing. Seventy-five mutations account for 90.2% of CF chromosomes. Among these we have detected seven novel CFTR mutations, including four missense (G85V, T582R, R851L and F1074L), two nonsense (E692X and Q1281X) and one splice site mutation (711+3A-->T). Three variants, two in intronic regions (406-112A/T and 3850-129T/C) and one in the coding region (741C/T) were also identified. Mutations G85V, T582R, R851L, E692X and Q1281X are severe, with lung and pancreatic involvement; 711+3A-->T could be responsible for a pancreatic sufficiency/insufficiency variable phenotype; and F1074L was associated with a mild phenotype. These data demonstrate the highest molecular heterogeneity reported so far in CF, indicating that a wide mutation screening is necessary to characterize 90% of the Spanish CF alleles.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
33 Eight mutations have frequencies 366 Table 1 Seventy-five CFTR mutations identified in 640 Spanish families with cystic fibrosis (CF) Mutation Exon/intron CF alleles % ∆F508 E.10 681 53.20 G542X E.11 108 8.43 N1303K E.21 34 2.65 1811+1.6kbA→Ga I.11 24 1.87 711+1G→T I.5 22 1.71 R1162Xa E.19 21 1.64 R334Wa E.7 21 1.64 R1066C E.17b 14 1.09 1609delCAa E.10 13 1.01 Q890X E.15 13 1.01 G85E E.3 12 0.94 712-1G→Ta I.5 11 0.86 2789+5G→A I.14b 11 0.86 ∆I507 E.10 10 0.78 W1282X E.20 10 0.78 2869insGa E.15 9 0.70 L206W E.6a 7 0.54 R709X E.13 7 0.54 621+1G→T I.4 6 0.47 3272-26A→G I.17a 6 0.47 R347H E.7 5 0.39 2183AA→G E.13 5 0.39 K710X E.13 5 0.39 2176insC E.13 5 0.39 3849+10kbC→T I.19 5 0.39 P205Sa E.6a 4 0.31 1078delT E.7 4 0.31 R553X E.11 4 0.31 G551D E.11 4 0.31 1812-1G→Aa I.11 4 0.31 CFdel#1a E.4-7/11-18 4 0.31 V232D E.6a 3 0.23 936delTAa E.6b 3 0.23 1717-8G→A I.10 3 0.23 1949del84 E.13 3 0.23 W1089X E.17b 3 0.23 R347P E.7 3 0.23 del E.3a E.3 2 0.16 R117H E.4 2 0.16 L558S E.11 2 0.16 A561E E.12 2 0.16 2603delT E.13 2 0.16 Y1092X E.17b 2 0.16 Q1100Pa E.17b 2 0.16 M1101K E.17b 2 0.16 delE.19a E.19 2 0.16 G1244E E.20 2 0.16 P5La E.1 1 0.08 Q30Xa E.2 1 0.08 G85Va E.3 1 0.08 E92Ka E.4 1 0.08 A120Ta E.4 1 0.08 I148T E.4 1 0.08 711+3A→Ta I.5 1 0.08 H199Y E.6a 1 0.08 875+1G→A I.6a 1 0.08 Table 1 (continued) Mutation Exon/intron CF alleles % 1717-1G→A I.10 1 0.08 L571S E.12 1 0.08 T582Ra E.12 1 0.08 E585X E.12 1 0.08 1898+3A→G I.12 1 0.08 G673X E.13 1 0.08 E692Xa E.13 1 0.08 R851X E.14a 1 0.08 R851La E.14a 1 0.08 A1006E E.17a 1 0.08 L1065Ra E.17b 1 0.08 F1074La E.17b 1 0.08 R1158X E.19 1 0.08 3667del4a E.19 1 0.08 3860ins31a E.20 1 0.08 3905insT E.20 1 0.08 4005+1G→A I.20 1 0.08 Q1281Xa E.20 1 0.08 Q1313X E.21 1 0.08 Known mutations (75) 1155 90.23 Unknown mutations 125 9.77 a Mutations discovered by the CF group of the Medical and Molecular Genetics Centre - IRO, Barcelona, Spain that range between 0.5% and 0.9%, representing 6.0% of the CF chromosomes. Login to comment

[hide] Unusually common cystic fibrosis mutation in Portu... Biochem Biophys Res Commun. 2003 Nov 21;311(3):665-71. Mendes F, Roxo Rosa M, Dragomir A, Farinha CM, Roomans GM, Amaral MD, Penque D
Unusually common cystic fibrosis mutation in Portugal encodes a misprocessed protein.
Biochem Biophys Res Commun. 2003 Nov 21;311(3):665-71., [PMID:14623323]

Abstract [show]
A561E, a novel cystic fibrosis (CF) associated mutation in the first nucleotide binding domain of CFTR, is the second most common CF mutation in Portugal. Properties of the A561E-CFTR protein were studied by immunoblotting, pulse-chase, immunocytochemistry, and MQAE halide-efflux assay in stably transfected BHK cells. Altogether, results presented here suggest that A561E causes protein mislocalization in the endoplasmic reticulum where the mutant protein must be trapped by the quality control mechanism. We conclude that A561E originates a protein trafficking defect, thus belonging to class II of CFTR mutations. As it is the case for F508del-CFTR (the most common CF mutant), low temperature treatment partially rescues a functional A561E-CFTR channel, suggesting that substitution of glutamic acid for alanine at position 561 does not completely abolish CFTR function. Pharmacological strategies previously reported for treatment of CF patients with the F508del mutation could thus be also effective in CF patients bearing the A561E mutation.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
0 Unusually common cystic fibrosis mutation in Portugal encodes a misprocessed protein Filipa Mendes,a M o onica Roxo Rosa,a,c Anca Dragomir,b Carlos M. Farinha,a,c Godfried M. Roomans,b Margarida D. Amaral,a,c and Deborah Penquea,* a Centro de Gen e etica Humana, Instituto Nacional de Sa u ude Dr Ricardo Jorge, Lisboa 1649-016, Portugal b Department of Medical Cell Biology, University of Uppsala, Uppsala, Sweden c Departamento de Qu mica e Bioqu mica, Faculdade de Ci^ e encias, Universidade de Lisboa, Portugal Received 8 October 2003 Abstract A561E, a novel cystic fibrosis (CF) associated mutation in the first nucleotide binding domain of CFTR, is the second most common CF mutation in Portugal. Login to comment
1 Properties of the A561E-CFTR protein were studied by immunoblotting, pulse-chase, immunocytochemistry, and MQAE halide-efflux assay in stably transfected BHK cells. Login to comment
2 Altogether, results presented here suggest that A561E causes protein mislocalization in the endoplasmic reticulum where the mutant protein must be trapped by the quality control mechanism. Login to comment
3 We conclude that A561E originates a protein trafficking defect, thus belonging to class II of CFTR mutations. Login to comment
4 As it is the case for F508del-CFTR (the most common CF mutant), low temperature treatment partially rescues a functional A561E-CFTR channel, suggesting that substitution of glutamic acid for alanine at position 561 does not completely abolish CFTR function. Login to comment
5 Pharmacological strategies previously reported for treatment of CF patients with the F508del mutation could thus be also effective in CF patients bearing the A561E mutation. Login to comment
7 Keywords: Cystic fibrosis; CFTR; A561E mutation; Classes of CFTR mutations Cystic fibrosis (CF) is a common autosomal recessive inherited disorder in the Caucasian population [1,2]. Login to comment
12 One of them is the novel CF missense mutation A561E, in which alanine is replaced by glutamic acid at position 561 of the CFTR polypeptide (http://www.genet.sickkids.on.ca/cftr). Login to comment
13 The A561E mutation accounts for 3% of Portuguese CF genes, being the second most frequent CF mutation in Portugal. Login to comment
26 The aim of the present work was to classify the A561E mutation into one of the functional defect classes of CFTR mutations. Login to comment
27 Therefore, we have stably overexpressed A561E CFTR in a heterologous expression system, baby hamster kidney (BHK) cell lines, and analysed them by immunoblotting, pulse-chase, halide sensitive fluorescent dye assay, and immunocytochemistry in order to characterize the molecular mechanism of the A561E mutation. Login to comment
28 The classification of A561E mutation into one of the classes of CFTR mutations will allow a better understanding of the relationship between the functional alterations and disease phenotype and pave the way for designing appropriate pharmacological interventions in CF patients bearing this particular mutation. Login to comment
31 A561E mutation was created in pBQ 4.7 using Muta-gene phagemid in vitro mutagenesis Kit (BioRad Laboratories, Hercules, CA, USA) according to manufacturer`s recommendations. Login to comment
32 The oligonucleotide 50 -CTTTAGCAAGAGAAG TATACAAAGATGC-30 was used to produce A561E mutation and the mutants were subsequently confirmed by DNA sequence analysis. Login to comment
33 Full-length fragment cut off from A561E CFTR cDNA/pBQ4.7 was subcloned into the eukaryotic expression vector pNUT (kindly provided by J. Riordan, Scottsdale, USA). Login to comment
35 Baby hamster kidney (BHK) cells were stably transfected with A561E-CFTR pNUT recombinant vector by using DOTAP (Boehringer Mannheim GmbH, Mannheim, Germany) following the manufacturer`s recommendations. Login to comment
38 BHK cells stably expressing wild-type (wt)-, F508del-CFTR (both kindly provided by G. Lukacs, Toronto, Canada) or A561E-CFTR were cultivated as described [9,10]. Login to comment
72 Results A561E-CFTR is a misprocessed protein The A561E mutation was subcloned into the higher eukaryotic expression vector pNUT and the recombinant vector was stably expressed in BHK cell lines. Login to comment
74 Fig. 1A shows the Western blotting of a total protein extract from one of these BHK cell clones stably expressing A561E analysed in parallel with extracts of BHK cells expressing wt- or F508del-CFTR as controls. Login to comment
75 Like F508del-CFTR (Fig. 1A, lane 3), A561E-CFTR is only detected as an immature, ER core-glycosylated form of CFTR (band B), of 150 kDa in this heterologous expression cell system (Fig. 1A, lane 4). Login to comment
76 No mature complex-glycosylated forms (band C) of 170-180 kDa were detected for A561E-CFTR. Login to comment
78 Immunolocalization studies revealed that in contrast to the wt-CFTR, which is essentially detected in the cell membrane (Fig. 2A), A561E-CFTR shows the same prominent ER localization (Fig. 2C) as F508del-CFTR (Fig. 2B). Login to comment
79 To assess whether a small amount of A561E-CFTR, below the biochemical and immunocytochemical detection limits, traverses the Golgi to the plasma membrane, we employed the more sensitive single-cell membrane halide permeability assay using the Cl indicator MQAE. Login to comment
81 By contrast, no measurable cAMP-stimulated Cl channel activity was detected in cells expressing A561E- or F508del-CFTR (Fig. 3A, middle and lower panels, respectively). Login to comment
82 Taken together, these data demonstrate that A561E-CFTR is misprocessed and retained intracellularly, thus failing both to localize correctly and to function at the plasma membrane. Login to comment
83 Like F508del, the A561E should thus be included into class II of defective processing CFTR mutations. Login to comment
85 Western-blotting analysis of BHK cells stably expressing wt-, F508del- or A561E-CFTR. Login to comment
87 Cell lysates were prepared (see Materials and methods) from BHK cells non-transfected (50 lg, lane 1), or stably transfected with wt- (30 lg, lane 2), F508del- (50 lg, lane 2) or A561E-CFTR cDNA cloned into pNUT vector (50 lg, lane 4), and resolved on a 6% SDS-polyacrylamide gel before electrophoretic transfer to nitrocellulose for immunodetection of CFTR, using M3A7 anti-CFTR antibody (1:1000). Login to comment
88 The complex-glycosylated forms of CFTR (band C, see arrow) are absent in cells expressing A561E or F508del-CFTR. Login to comment
89 (B) Effect of low temperature on the trafficking defect of A561E- and F508del-CFTR. Login to comment
90 BHK cells stably expressing F508del- or A561E-CFTR were incubated at 26 &#b0;C for 24 h (100 lg/per lane, lanes 3 and 6, respectively) or for 48 h (100 lg/lane, lanes 4 and 7, respectively) prior to evaluation by Western-blotting (as described in (A)), for the presence of mature or immature A561E- or F508del-CFTR. Login to comment
92 As controls, cell lysates from BHK cells expressing wt- (30 lg, lane 1), F508del- (50 lg, lane 2) or A561E-CFTR (50 lg, lane 5) grown at 37 &#b0;C were also analysed in parallel. Login to comment
93 The abundance of complex-glycosylated forms of wt-, F508del-, and A561E-CFTR persisting in the cell (indicated by arrows) was calculated from densitometry of immunoblots. Login to comment
95 Immunolocalization of CFTR in BHK cells expressing wt-, F508del-, or A561E-CFTR. Login to comment
97 At normal temperature of cell culture (37 &#b0;C), A561E-CFTR (C) is detected strictly in the area around the nuclei of the cells like F508del-CFTR (B); while wt-CFTR (A,D) is predominantly located at the plasma membrane. Login to comment
98 At low temperature (26 &#b0;C), some A561E- and F508del-CFTR are rescued to the cell surface (see arrows head in (E) and (F)). Login to comment
101 (A) Characteristic records of MQAE fluorescence (thin lines) and corresponding intracellular Cl concentration (thick lines) in BHK cells stably expressing wt-, F508del- or A561E-CFTR. Login to comment
104 (B) Effect of low temperature on Cl concentration and efflux in BHK cells stably expressing wt-, F508del- or A561E-CFTR. Login to comment
110 The turnover rates of A561E-CFTR are similar to those of F508del-CFTR To study whether A561E-CFTR and F508del-CFTR have the same biogenesis and kinetics degradation, we analysed these two mutants and the wt-protein by pulse-chase technique. Login to comment
113 The newly synthesized immature form of A561E-CFTR migrates with the same molecular mass of wtand F508del-CFTR (Fig. 4A). Login to comment
117 Here, we observed the same phenomenon for A561E-CFTR. Login to comment
118 Multiple pulse-chase experiments (n &#bc; 3) indicate that the t1=2 of immature core-glycosylated A561E-CFTR was very similar to that of F508del-CFTR, around 40 min, which is slightly lower than that of the wt CFTR in BHK cells as described by Luckas et al. [11,14] (Fig. 4C). Login to comment
119 As the immature A561E-CFTR is not converted into band C, its turnover corresponds solely to protein degradation. Login to comment
120 Therefore, we suggest that the A561E mutation does not significantly alter the susceptibility to degradation of the newly synthesized protein. Login to comment
121 Low temperature partially restores A561E-CFTR trafficking defect Reduced temperature is thought to partially revert the folding defect of F508del-CFTR and thus promote the traffic of functional channels to the cell surface [15-18]. Login to comment
122 To examine whether the processing defect of A561E-CFTR can be overcome by low temperature treatment, similar to F508del-CFTR, BHK cells overexpressing this mutant were incubated at 26 &#b0;C for 24 or 48 h and analysed by Western blotting (Fig. 1B). Login to comment
124 Fig. 1B shows that mature forms of A561E and F508del-CFTR (band C) were readily detected in cells incubated at 26 &#b0;C for 24 and 48 h (lanes 6/7 and 3/4, respectively). Login to comment
125 Densitometric analysis revealed that the amount of rescued band C of either A561E or F508del does not increase upon longer incubation (48 h) at 26 &#b0;C. Login to comment
127 At low temperature, some A561E-CFTR and F508del-CFTR were also detectable by immunocyto- Fig. 4. Login to comment
128 Turnover rates of Wt, F508del- and A561E-CFTR in BHK cells. Login to comment
129 (A) Pulse-chase experiments followed by immunoprecipitation of wt-, F508del-, and A561E-CFTR. Login to comment
130 F508del- and A561E-CFTR proteins are synthesized as 140 kDa precursors that are very rapidly (t1=2 < 30 min) degraded with no apparent conversion to mature forms (fully glycosylated) in contrast to wt-CFTR. Login to comment
131 (B) Quantification of fluorographic data of F508del-CFTR and A561E-CFTR experiments (n &#bc; 3/each). Login to comment
133 No significant differences are found between the turnover kinetics of immature forms of both F508del- and A561E-CFTR. Login to comment
135 Additionally, the MQAE fluorescence assay also demonstrates that cells expressing A561E- or F508del-CFTR generate cAMP-stimulated Cl efflux after incubation at low temperature for 24 or 48 h (Fig. 3B), albeit to a lesser extent than that observed for wt-CFTR (Fig. 3C). Login to comment
137 However, the difference in the amplitude of response to cAMP agonists between the cells expressing wt-CFTR and cells expressing CFTR mutants remains significant, even following growth at low temperature suggesting that low thermal treatment only partially corrects the trafficking defect of both A561E- and F508del-CFTR. Login to comment
138 Taken together all data strongly indicate that A561E-CFTR is a temperature-sensitive traffic mutant. Login to comment
139 Functional cAMP-stimulated A561E-CFTR Cl channel activity in the plasma membrane can be promoted by reduced temperature treatment. Login to comment
140 The substitution of glutamic acid for alanine at position 561 of CFTR does not completely abolish CFTR function once the trafficking defect is corrected. Login to comment
145 The novel missense mutation A561E, located in exon 12, is part of a cluster of missense mutations that affect the highly conserved amino acid residues, between the signature (C) and Walker B motifs within the NBD1 of CFTR (Fig. 5). Login to comment
146 In Portugal, A561E is the second most frequent CF mutation, accounting for 3% of CF alleles. Login to comment
147 To date, 14 patients carrying A561E were identified in Portugal; nine are compound heterozygotes with F508del, one with G542X and four are homozygous for A561E mutation (Pacheco et al., personal communication and manuscript in preparation). Login to comment
149 Functional assessment of native colonic epithelia of patients, including one homozygote for A561E and another compound heterozygote for A561E and F508del, showed that CFTR-mediated Cl secretion is absent in the colon of these patients (Hirtz et al. 2003, submitted for publication) [21]. Login to comment
150 In order to explore the molecular mechanism that leads to defective Cl transport in A561E patients we have studied the processing, localization, and function of A561E-CFTR stably overexpressed in BHK cell lines. Login to comment
151 The results presented here clearly demonstrate that A561E has a trafficking defect when heterologously expressed in these cells. Login to comment
152 Like F508del, A561E-CFTR is not processed correctly and, as a consequence, is not delivered to the plasma membrane of these cells. Login to comment
153 Therefore, A561E mutation belongs to the class II of CFTR mutations. Login to comment
154 In BHK cells, A561E-CFTR must not acquire its fully folded native conformation. Login to comment
155 Indeed, placing the A561 residue in the homology model of CFTR NBD1, Dorwart et al. [22] recently suggested that this residue is deeply buried in this domain and that the A561E mutation probably disrupts its efficient folding. Login to comment
156 The core-glycosylated immature form of A561E-CFTR must thus be retained in the ER by its quality control from where it is degraded. Login to comment
157 The properties of A561E-CFTR revert towards those of wt-CFTR as the incubation temperature is reduced to 26 &#b0;C. Login to comment
158 When the processing defect is (partially) corrected, functional cAMP-regulated Cl channels appear in the plasma membrane, indicating that A561E mutation does not completely abolish CFTR function. Login to comment
159 Based on the results reported here, we hypothesize that A561E-CFTR can be also re-directed to the normal protein trafficking pathway by manipulation of chaperone protein/CFTR interactions, with chemical chaperones or other drugs that affect gene regulation such as genistein and xanthine derivatives [20]. Login to comment
160 Thus, the pharmacological therapies that have been tried for CF patients bearing F508del could be also useful to those with the A561E mutation. Login to comment
162 F508del- and A561E-CFTR mutations in NBD1. Login to comment

[hide] Effect of ivacaftor on CFTR forms with missense mu... J Cyst Fibros. 2014 Jan;13(1):29-36. doi: 10.1016/j.jcf.2013.06.008. Epub 2013 Jul 23. Van Goor F, Yu H, Burton B, Hoffman BJ
Effect of ivacaftor on CFTR forms with missense mutations associated with defects in protein processing or function.
J Cyst Fibros. 2014 Jan;13(1):29-36. doi: 10.1016/j.jcf.2013.06.008. Epub 2013 Jul 23., [PMID:23891399]

Abstract [show]
BACKGROUND: Ivacaftor (KALYDECO, VX-770) is a CFTR potentiator that increased CFTR channel activity and improved lung function in patients age 6 years and older with CF who have the G551D-CFTR gating mutation. The aim of this in vitro study was to evaluate the effect of ivacaftor on mutant CFTR protein forms with defects in protein processing and/or channel function. METHODS: The effect of ivacaftor on CFTR function was tested in electrophysiological studies using a panel of Fischer rat thyroid (FRT) cells expressing 54 missense CFTR mutations that cause defects in the amount or function of CFTR at the cell surface. RESULTS: Ivacaftor potentiated multiple mutant CFTR protein forms that produce functional CFTR at the cell surface. These included mutant CFTR forms with mild defects in CFTR processing or mild defects in CFTR channel conductance. CONCLUSIONS: These in vitro data indicated that ivacaftor is a broad acting CFTR potentiator and could be used to help stratify patients with CF who have different CFTR genotypes for studies investigating the potential clinical benefit of ivacaftor.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
44 None M1V A46D E56K P67L R74W G85E E92K D110E D110H R117C R117H E193K L206W R334W I336K T338I S341P R347H R347P R352Q A455E L467P S492F F508del V520F A559T R560S R560T A561E Y569D D579G R668C L927P S945L S977F L997F F1052V H1054D K1060T L1065P R1066C R1066H R1066M A1067T R1070Q R1070W F1074L L1077P H1085R M1101K D1152H S1235R D1270N N1303K 0 100 200 300 400 500 600 * * * CFTR Mutation mRNA (% Normal CFTR) Fig. 1. Login to comment
64 Mutant CFTR form CFTR processing Mature/total % Normal CFTR Normal 0.89 &#b1; 0.01 100.0 &#b1; 18.5 G85E -0.05 &#b1; 0.04 -1.0 &#b1; 0.9 R560S 0.00 &#b1; 0.00 0.0 &#b1; 0.0 R1066C 0.02 &#b1; 0.01 0.0 &#b1; 0.0 S492F 0.00 &#b1; 0.00 0.1 &#b1; 0.1 R560T 0.01 &#b1; 0.01 0.2 &#b1; 0.1 V520F 0.05 &#b1; 0.03 0.3 &#b1; 0.2 M1101K 0.05 &#b1; 0.03 0.3 &#b1; 0.1 A561E 0.08 &#b1; 0.04 0.5 &#b1; 0.2 R1066M 0.02 &#b1; 0.02 0.5 &#b1; 0.4 N1303K 0.02 &#b1; 0.02 0.5 &#b1; 0.3 A559T 0.16 &#b1; 0.09 0.6 &#b1; 0.2 M1V 0.06 &#b1; 0.06 0.7 &#b1; 0.6 Y569D 0.11 &#b1; 0.04 0.6 &#b1; 0.2 R1066H 0.08 &#b1; 0.02a 0.7 &#b1; 0.2a L1065P 0.05 &#b1; 0.05 1.0 &#b1; 0.8 L467P 0.10 &#b1; 0.07 1.2 &#b1; 0.8 L1077P 0.08 &#b1; 0.04 1.5 &#b1; 0.6 A46D 0.21 &#b1; 0.08 1.9 &#b1; 0.5a E92K 0.06 &#b1; 0.05 1.9 &#b1; 1.3 H1054D 0.09 &#b1; 0.04 1.9 &#b1; 0.8 F508del 0.09 &#b1; 0.02a 2.3 &#b1; 0.5a H1085R 0.06 &#b1; 0.01a 3.0 &#b1; 0.7a I336K 0.42 &#b1; 0.05a 6.5 &#b1; 0.7a L206W 0.35 &#b1; 0.10a 6.8 &#b1; 1.7a F1074L 0.52 &#b1; 0.03a 10.9 &#b1; 0.6a A455E 0.26 &#b1; 0.10a 11.5 &#b1; 2.5a E56K 0.29 &#b1; 0.04a 12.2 &#b1; 1.5a R347P 0.48 &#b1; 0.04a 14.6 &#b1; 1.8a R1070W 0.61 &#b1; 0.04a 16.3 &#b1; 0.6a P67L 0.36 &#b1; 0.04a 28.4 &#b1; 6.8a R1070Q 0.90 &#b1; 0.01a 29.5 &#b1; 1.4a S977F 0.97 &#b1; 0.01a 37.3 &#b1; 2.4a A1067T 0.78 &#b1; 0.03a 38.6 &#b1; 6.1a D579G 0.72 &#b1; 0.02a 39.3 &#b1; 3.1a D1270N 1.00 &#b1; 0.00a,c 40.7 &#b1; 1.2a S945L 0.65 &#b1; 0.04a 42.4 &#b1; 8.9a L927P 0.89 &#b1; 0.01a,b 43.5 &#b1; 2.5a,b R117C 0.87 &#b1; 0.02a,b 49.1 &#b1; 2.9a,b T338I 0.93 &#b1; 0.03a,b 54.2 &#b1; 3.7a,b L997F 0.90 &#b1; 0.04a,b 59.8 &#b1; 10.4a,b D110H 0.97 &#b1; 0.01a,b 60.6 &#b1; 1.5a,b S341P 0.79 &#b1; 0.02a 65.0 &#b1; 4.9a,b R668C 0.94 &#b1; 0.03a,b 68.5 &#b1; 1.9a,b R74W 0.78 &#b1; 0.01a 69.0 &#b1; 2.7a,b D110E 0.92 &#b1; 0.05a,b 87.5 &#b1; 9.5a,b R334W 0.91 &#b1; 0.05a,b 97.6 &#b1; 10.0a,b K1060T 0.87 &#b1; 0.02a,b 109.9 &#b1; 28.0a,b R347H 0.96 &#b1; 0.02a,c 120.7 &#b1; 2.8a,b S1235R 0.96 &#b1; 0.00a,c 139.0 &#b1; 9.0a,b E193K 0.84 &#b1; 0.02a,b 143.0 &#b1; 17.1a,b R117H 0.86 &#b1; 0.01a,b 164.5 &#b1; 34.2a,b R352Q 0.98 &#b1; 0.01a,b 179.9 &#b1; 8.0a,c F1052V 0.90 &#b1; 0.01a,b 189.9 &#b1; 33.1a,b D1152H 0.96 &#b1; 0.02a,c 312.0 &#b1; 45.5a,b Notes to Table 1: Quantification of steady-state CFTR maturation expressed as the mean (&#b1;SEM; n = 5-9) ratio of mature CFTR to total CFTR (immature plus mature) or level of mature mutant CFTR relative to mature normal-CFTR (% normal CFTR) in FRT cells individually expressing CFTR mutations. Login to comment
74 Because the level of CFTR mRNA was similar across the panel of cell lines tested, the range in baseline activity and ivacaftor response likely reflects the severity of the functional defect and/or the 0 50 100 150 200 S341P R347P L467P S492F A559T A561E Y569D L1065P R1066C R1066M L1077P M1101K N1303K R560S L927P R560T H1085R V520F E92K M1V F508del H1054D I336K A46D G85E R334W T338I R1066H R352Q R117C L206W R347H S977F S945L A455E F1074L E56K P67L R1070W D110H D579G D110E R1070Q L997F A1067T E193K R117H R74W K1060T R668C D1270N D1152H S1235R F1052V Baseline With ivacaftor * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Chloride transport (% Normal) Mutant CFTR form 0 100 200 300 400 S341P R347P L467P S492F A559T A561E Y569D L1065P R1066C R1066M L1077P M1101K N1303K R560S L927P R560T H1085R V520F E92K M1V F508del H1054D I336K A46D G85E R334W T338I R1066H R352Q R117C L206W R347H S977F S945L A455E F1074L P67L E56K R1070W D110H D579G D110E R1070Q L997F A1067T E193K R117H R74W K1060T R668C D1270N D1152H S1235R F1052V * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Mature CFTR (% Normal) Mutant CFTR form A B Fig. 2. Login to comment
82 Mutation Patientsa Chloride transport (bc;A/cm2 ) Chloride transport (% normal) EC50 Baseline With ivacaftor Baseline With ivacaftor Fold increase over baselineb Normal 204.5 &#b1; 33.3 301.3 &#b1; 33.8c 100.0 &#b1; 16.3 147.3 &#b1; 16.5c 1.5 266 &#b1; 42 G551D 1282 1.5 &#b1; 0.7 113.2 &#b1; 13.0c 1.0 &#b1; 0.5 55.3 &#b1; 6.3c 55.3 312 &#b1; 73 F1052V 12 177.3 &#b1; 13.7 410.2 &#b1; 11.3c 86.7 &#b1; 6.7 200.7 &#b1; 5.6c 2.3 177 &#b1; 14 S1235R ND 160.6 &#b1; 25.7 352.1 &#b1; 43.4c 78.5 &#b1; 12.6 172.2 &#b1; 21.2c 2.2 282 &#b1; 104 D1152H 185 117.3 &#b1; 23.0 282.7 &#b1; 46.9c 57.4 &#b1; 11.2 138.2 &#b1; 22.9c 2.4 178 &#b1; 67 D1270N 32 109.5 &#b1; 20.5 209.5 &#b1; 27.4c 53.6 &#b1; 10.0 102.4 &#b1; 13.4c 1.9 254 &#b1; 56 R668C 45 99.0 &#b1; 9.4 217.6 &#b1; 11.7c 48.4 &#b1; 4.6 106.4 &#b1; 5.7c 2.2 517 &#b1; 105 K1060T ND 89.0 &#b1; 9.8 236.4 &#b1; 20.3c 43.5 &#b1; 4.8 115.6 &#b1; 9.9c 2.7 131 &#b1; 73 R74W 25 86.8 &#b1; 26.9 199.1 &#b1; 16.8c 42.5 &#b1; 13.2 97.3 &#b1; 8.2c 2.3 162 &#b1; 17 R117H 739 67.2 &#b1; 13.3 274.1 &#b1; 32.2c 32.9 &#b1; 6.5 134.0 &#b1; 15.7c 4.1 151 &#b1; 14 E193K ND 62.2 &#b1; 9.8 379.1 &#b1; 1.1c 30.4 &#b1; 4.8 185.4 &#b1; 1.0c 6.1 240 &#b1; 20 A1067T ND 55.9 &#b1; 3.2 164.0 &#b1; 9.7c 27.3 &#b1; 1.6 80.2 &#b1; 4.7c 2.9 317 &#b1; 214 L997F 27 43.7 &#b1; 3.2 145.5 &#b1; 4.0c 21.4 &#b1; 1.6 71.2 &#b1; 2.0c 3.3 162 &#b1; 12 R1070Q 15 42.0 &#b1; 0.8 67.3 &#b1; 2.9c 20.6 &#b1; 0.4 32.9 &#b1; 1.4c 1.6 164 &#b1; 20 D110E ND 23.3 &#b1; 4.7 96.4 &#b1; 15.6c 11.4 &#b1; 2.3 47.1 &#b1; 7.6c 4.1 213 &#b1; 51 D579G 21 21.5 &#b1; 4.1 192.0 &#b1; 18.5c 10.5 &#b1; 2.0 93.9 &#b1; 9.0c 8.9 239 &#b1; 48 D110H 30 18.5 &#b1; 2.2 116.7 &#b1; 11.3c 9.1 &#b1; 1.1 57.1 &#b1; 5.5c 6.2 249 &#b1; 59 R1070W 13 16.6 &#b1; 2.6 102.1 &#b1; 3.1c 8.1 &#b1; 1.3 49.9 &#b1; 1.5c 6.2 158 &#b1; 48 P67L 53 16.0 &#b1; 6.7 88.7 &#b1; 15.7c 7.8 &#b1; 3.3 43.4 &#b1; 7.7c 5.6 195 &#b1; 40 E56K ND 15.8 &#b1; 3.1 63.6 &#b1; 4.4c 7.7 &#b1; 1.5 31.1 &#b1; 2.2c 4.0 123 &#b1; 33 F1074L ND 14.0 &#b1; 3.4 43.5 &#b1; 5.4c 6.9 &#b1; 1.6 21.3 &#b1; 2.6c 3.1 141 &#b1; 19 A455E 120 12.9 &#b1; 2.6 36.4 &#b1; 2.5c 6.3 &#b1; 1.2 17.8 &#b1; 1.2c 2.8 170 &#b1; 44 S945L 63 12.3 &#b1; 3.9 154.9 &#b1; 47.6c 6.0 &#b1; 1.9 75.8 &#b1; 23.3c 12.6 181 &#b1; 36 S977F 9 11.3 &#b1; 6.2 42.5 &#b1; 19.1c 5.5 &#b1; 3.0 20.8 &#b1; 9.3c 3.8 283 &#b1; 36 R347H 65 10.9 &#b1; 3.3 106.3 &#b1; 7.6c 5.3 &#b1; 1.6 52.0 &#b1; 3.7c 9.8 280 &#b1; 35 L206W 81 10.3 &#b1; 1.7 36.4 &#b1; 2.8c 5.0 &#b1; 0.8 17.8 &#b1; 1.4c 3.6 101 &#b1; 13 R117C 61 5.8 &#b1; 1.5 33.7 &#b1; 7.8c 2.9 &#b1; 0.7 16.5 &#b1; 3.8c 5.7 380 &#b1; 136 R352Q 46 5.5 &#b1; 1.0 84.5 &#b1; 7.8c 2.7 &#b1; 0.5 41.3 &#b1; 3.8c 15.2 287 &#b1; 75 R1066H 29 3.0 &#b1; 0.3 8.0 &#b1; 0.8c 1.5 &#b1; 0.1 3.9 &#b1; 0.4c 2.6 390 &#b1; 179 T338I 54 2.9 &#b1; 0.8 16.1 &#b1; 2.4c 1.4 &#b1; 0.4 7.9 &#b1; 1.2c 5.6 334 &#b1; 38 R334W 150 2.6 &#b1; 0.5 10.0 &#b1; 1.4c 1.3 &#b1; 0.2 4.9 &#b1; 0.7c 3.8 259 &#b1; 103 G85E 262 1.6 &#b1; 1.0 1.5 &#b1; 1.2 0.8 &#b1; 0.5 0.7 &#b1; 0.6 NS NS A46D ND 2.0 &#b1; 0.6 1.1 &#b1; 1.1 1.0 &#b1; 0.3 0.5 &#b1; 0.6 NS NS I336K 29 1.8 &#b1; 0.2 7.4 &#b1; 0.1c 0.9 &#b1; 0.1 3.6 &#b1; 0.1c 4 735 &#b1; 204 H1054D ND 1.7 &#b1; 0.3 8.7 &#b1; 0.3c 0.8 &#b1; 0.1 4.2 &#b1; 0.1c 5.3 187 &#b1; 20 F508del 29,018 0.8 &#b1; 0.6 12.1 &#b1; 1.7c 0.4 &#b1; 0.3 5.9 &#b1; 0.8c 14.8 129 &#b1; 38 M1V 9 0.7 &#b1; 1.4 6.5 &#b1; 1.9c 0.4 &#b1; 0.7 3.2 &#b1; 0.9c 8.0 183 &#b1; 85 E92K 14 0.6 &#b1; 0.2 4.3 &#b1; 0.8c 0.3 &#b1; 0.1 2.1 &#b1; 0.4c 7.0 198 &#b1; 46 V520F 58 0.4 &#b1; 0.2 0.5 &#b1; 0.2 0.2 &#b1; 0.1 0.2 &#b1; 0.1 NS NS H1085R ND 0.3 &#b1; 0.2 2.1 &#b1; 0.4 0.2 &#b1; 0.1 1.0 &#b1; 0.2 NS NS R560T 180 0.3 &#b1; 0.3 0.5 &#b1; 0.5 0.1 &#b1; 0.1 0.2 &#b1; 0.2 NS NS L927P 15 0.2 &#b1; 0.1 10.7 &#b1; 1.7c 0.1 &#b1; 0.1 5.2 &#b1; 0.8c 52.0 313 &#b1; 66 R560S ND 0.0 &#b1; 0.1 -0.2 &#b1; 0.2 0.0 &#b1; 0.0 -0.1 &#b1; 0.1 NS NS N1303K 1161 0.0 &#b1; 0.0 1.7 &#b1; 0.3 0.0 &#b1; 0.0 0.8 &#b1; 0.2 NS NS M1101K 79 0.0 &#b1; 0.0 0.0 &#b1; 0.0 0.0 &#b1; 0.0 0.0 &#b1; 0.0 NS NS L1077P 42 0.0 &#b1; 0.0 0.0 &#b1; 0.0 0.0 &#b1; 0.0 0.0 &#b1; 0.0 NS NS R1066M ND 0.0 &#b1; 0.0 0.0 &#b1; 0.0 0.0 &#b1; 0.0 0.0 &#b1; 0.0 NS NS R1066C 100 0.0 &#b1; 0.0 0.0 &#b1; 0.0 0.0 &#b1; 0.0 0.0 &#b1; 0.0 NS NS L1065P 25 0.0 &#b1; 0.0 0.0 &#b1; 0.0 0.0 &#b1; 0.0 0.0 &#b1; 0.0 NS NS Y569D 9 0.0 &#b1; 0.0 0.0 &#b1; 0.0 0.0 &#b1; 0.0 0.0 &#b1; 0.0 NS NS A561E ND 0.0 &#b1; 0.1 0.0 &#b1; 0.1 0.0 &#b1; 0.0 0.0 &#b1; 0.1 NS NS A559T 43 0.0 &#b1; 0.0 0.0 &#b1; 0.0 0.0 &#b1; 0.0 0.0 &#b1; 0.0 NS NS S492F 16 0.0 &#b1; 0.0 1.7 &#b1; 1.2 0.0 &#b1; 0.0 0.8 &#b1; 0.6 NS NS L467P 16 0.0 &#b1; 0.0 0.0 &#b1; 0.0 0.0 &#b1; 0.0 0.0 &#b1; 0.0 NS NS R347P 214 0.0 &#b1; 0.0 0.0 &#b1; 0.0 0.0 &#b1; 0.0 0.0 &#b1; 0.0 NS NS S341P 9 0.0 &#b1; 0.0 0.2 &#b1; 0.2 0.0 &#b1; 0.0 0.1 &#b1; 0.1 NS NS a Number of individuals with the individual mutation in the CFTR-2 database (www.CFTR2.org). Login to comment

[hide] New pharmacological approaches for cystic fibrosis... Pharmacol Ther. 2015 Jan;145:19-34. doi: 10.1016/j.pharmthera.2014.06.005. Epub 2014 Jun 14. Bell SC, De Boeck K, Amaral MD
New pharmacological approaches for cystic fibrosis: promises, progress, pitfalls.
Pharmacol Ther. 2015 Jan;145:19-34. doi: 10.1016/j.pharmthera.2014.06.005. Epub 2014 Jun 14., [PMID:24932877]

Abstract [show]
With the discovery of the CFTR gene in 1989, the search for therapies to improve the basic defects of cystic fibrosis (CF) commenced. Pharmacological manipulation provides the opportunity to enhance CF transmembrane conductance regulator (CFTR) protein synthesis and/or function. CFTR modulators include potentiators to improve channel gating (class III mutations), correctors to improve abnormal CFTR protein folding and trafficking (class II mutations) and stop codon mutation read-through drugs relevant for patients with premature stop codons (most class I mutations). After several successful clinical trials the potentiator, ivacaftor, is now licenced for use in adults and children (>six years), with CF bearing the class III G551D mutation and FDA licence was recently expanded to include 8 additional class III mutations. Alternative approaches for class I and class II mutations are currently being studied. Combination drug treatment with correctors and potentiators appears to be required to restore CFTR function of F508del, the most common CFTR mutation. Alternative therapies such as gene therapy and pharmacological modulation of other ion channels may be advantageous because they are mutation-class independent, however progress is less well advanced. Clinical trials for CFTR modulators have been enthusiastically embraced by patients with CF and health care providers. Whilst novel trial end-points are being evaluated allowing CFTR modulators to be efficiently tested, many challenges related to the complexity of CFTR and the biology of the epithelium still need to be overcome.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
493 Class II mutations which besides F508del, include R560T (Roxo-Rosa et al., 2006), A561E (Mendes et al., 2003), R1066C (Seibert et al., 1996) and N1303K (Gregory et al., 1991) amongst others, affect CFTR protein processing due to misfolding which is recognized by endoplasmic reticulum (ER) quality control retention and which targets proteins with abnormal conformations to degradation (Amaral, 2004). Login to comment
544 Mutation Alternative name Allele frequency (% of total known) in ECFSPR 2010 Allele frequency (% of total known mutations) in 2010 ECFSPR F508del 64.5 Most frequent mutation worldwide Southeast to Northwest increasing prevalence in Europe IL 25.5 to DK 82.6 Mutations with an overall EU prevalence above 1% G542X Mediterranean mutation 2.5 GR 6.7, ES 6.0 N1303K Ancient Phoenician mutation 1.9 IT 4.2 W1282X Jewish Ashkenazi mutation 1.2 IL 22.4 G551D Celtic mutation 1.1 IE 7.3 1717-1GNA Italian mutation 1.0 IT 3.7 Mutations with an overall EU prevalence below 0.5% G85E PT 3.5 A455E Dutch mutation NL 3.5 CFTR dele 2,3 Slavic mutation CZ 5.2, BY 6.7 394delTT Nordic mutation SE 7.9, DK 2.0 3905insT Swiss mutation CH 2.4 R1162X Italian mutation IT 7.8 A561E Portuguese mutation PT 3.2 Abbreviations ECFSPR - European Cystic Fibrosis Society Patient Registry. Login to comment
547 Class Type of defect List of mutations attributed to this class Class I Defective protein production Nonsense mutations: G542X, R1162X, RW1282X Deletions and insertions: CFTRdele2,3; 1078delT; 1717-1G ࢐ A; 3659delC; 621+1G N T Class II Defective protein processing G85E, F508del, I507del, R560T, A561E, R1066C, N1303K Class III Defective protein regulation (gating) G178R, S549N, S549R, G551D, G551S, G970R, G1244E, S1251N, S1255P, G1349D Class IV Defective protein conductance R334W, R347P, R117H Class V Reduced amount of functioning protein 2789+5G ࢐ A, 3272-26ANG, 3849+10KbC ࢐ T, A455E Class VI Reduced cell surface stability Rescued F508del, c.120del23 Unclassified All other mutations, including those unknown a F508del-CFTR pocket (at NBD1:ICL4 interface) (Farinha et al., 2013). Login to comment

[hide] Full-open and closed CFTR channels, with lateral t... Cell Mol Life Sci. 2015 Apr;72(7):1377-403. doi: 10.1007/s00018-014-1749-2. Epub 2014 Oct 7. Mornon JP, Hoffmann B, Jonic S, Lehn P, Callebaut I
Full-open and closed CFTR channels, with lateral tunnels from the cytoplasm and an alternative position of the F508 region, as revealed by molecular dynamics.
Cell Mol Life Sci. 2015 Apr;72(7):1377-403. doi: 10.1007/s00018-014-1749-2. Epub 2014 Oct 7., [PMID:25287046]

Abstract [show]
In absence of experimental 3D structures, several homology models, based on ABC exporter 3D structures, have provided significant insights into the molecular mechanisms underlying the function of the cystic fibrosis transmembrane conductance regulator (CFTR) protein, a chloride channel whose defects are associated with cystic fibrosis (CF). Until now, these models, however, did not furnished much insights into the continuous way that ions could follow from the cytosol to the extracellular milieu in the open form of the channel. Here, we have built a refined model of CFTR, based on the outward-facing Sav1866 experimental 3D structure and integrating the evolutionary and structural information available today. Molecular dynamics simulations revealed significant conformational changes, resulting in a full-open channel, accessible from the cytosol through lateral tunnels displayed in the long intracellular loops (ICLs). At the same time, the region of nucleotide-binding domain 1 in contact with one of the ICLs and carrying amino acid F508, the deletion of which is the most common CF-causing mutation, was found to adopt an alternative but stable position. Then, in a second step, this first stable full-open conformation evolved toward another stable state, in which only a limited displacement of the upper part of the transmembrane helices leads to a closure of the channel, in a conformation very close to that adopted by the Atm1 ABC exporter, in an inward-facing conformation. These models, supported by experimental data, provide significant new insights into the CFTR structure-function relationships and into the possible impact of CF-causing mutations.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
357 Moreover, a large ''hot spot`` region for natural CFTR mutations is located at the NBD1:ICL4 interface, involving (1) six ICL4 positions (H1054D, G1061R, L1065P, R1066H/R1066C, F1074L, and L1077P), which line the path followed by F508 during the MD1 conformational transition from its initial to its final position, and (2) seven positions in NBD1 (S492F, I507del, F508del, V520F, A559T, R560K/R560T, and A561E) (Fig. 7c). Login to comment

[hide] Measurements of Functional Responses in Human Prim... EBioMedicine. 2014 Dec 17;2(2):147-53. doi: 10.1016/j.ebiom.2014.12.005. eCollection 2015 Feb. Awatade NT, Uliyakina I, Farinha CM, Clarke LA, Mendes K, Sole A, Pastor J, Ramos MM, Amaral MD
Measurements of Functional Responses in Human Primary Lung Cells as a Basis for Personalized Therapy for Cystic Fibrosis.
EBioMedicine. 2014 Dec 17;2(2):147-53. doi: 10.1016/j.ebiom.2014.12.005. eCollection 2015 Feb., [PMID:26137539]

Abstract [show]
BACKGROUND: The best investigational drug to treat cystic fibrosis (CF) patients with the most common CF-causing mutation (F508del) is VX-809 (lumacaftor) which recently succeeded in Phase III clinical trial in combination with ivacaftor. This corrector rescues F508del-CFTR from its abnormal intracellular localization to the cell surface, a traffic defect shared by all Class II CFTR mutants. Our goal here is to test the efficacy of lumacaftor in other Class II mutants in primary human bronchial epithelial (HBE) cells derived from CF patients. METHODS: The effect of lumacaftor was investigated in primary HBE cells from non-CF and CF patients with F508del/F508del, A561E/A561E, N1303K/G542X, F508del/G542X and F508del/Y1092X genotypes by measurements of Forskolin plus Genistein-inducible equivalent short-circuit current (Ieq-SC-Fsk + Gen) in perfused open-circuit Ussing chambers. Efficacy of corrector C18 was also assessed on A561E/A561E and F508del/F508del cells. RESULTS: Our data indicate that A561E (when present in both alleles) responds positively to lumacaftor treatment at equivalent efficacy of F508del in primary HBE cells. Similarly, lumacaftor has a positive impact on Y1092X, but not on N1303K. Our data also show that cells with only one copy of F508del-CFTR respond less to VX-809. Moreover, there is great variability in lumacaftor responses among F508del-homozygous cells from different donors. Compound C18 failed to rescue A561E-CFTR but not in F508del-CFTR, thus plausibly it has a different mechanism of action distinct from lumacaftor. CONCLUSIONS: CF patients with A561E (and likely also those with Y1029X) can potentially benefit from lumacaftor. Moreover, the methodology used here exemplifies how ex vivo approaches may apply personalized therapies to CF and possibly other respiratory diseases.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
3 Methods: The effect of lumacaftor was investigated in primary HBE cells from non-CF and CF patients with F508del/F508del, A561E/A561E, N1303K/G542X, F508del/G542X and F508del/Y1092X genotypes by measurements of Forskolin plus Genistein-inducible equivalent short-circuit current (Ieq-SC-Fsk + Gen) in perfused open-circuit Ussing chambers. Login to comment
4 Efficacy of corrector C18 was also assessed on A561E/A561E and F508del/F508del cells. Login to comment
5 Results: Our data indicate that A561E (when present in both alleles) responds positively to lumacaftor treatment at equivalent efficacy of F508del in primary HBE cells. Similarly, lumacaftor has a positive impact on Y1092X, but not on N1303K. Login to comment
8 Compound C18 failed to rescue A561E-CFTR but not in F508del-CFTR, thus plausibly it has a different mechanism of action distinct from lumacaftor. Login to comment
9 Conclusions: CF patients with A561E (and likely also those with Y1029X) can potentially benefit from lumacaftor. Login to comment
34 Mutations tested here include: A561E, quite frequent in Southern-European and South-American countries like in Portugal (Mendes et al., 2003), Spain (Moya-Quiles et al., 2009) and Brazil (Servidoni et al., 2013) and N1303K, linked to ancient Mediterranean populations (Bobadilla et al., 2002). Login to comment
36 Our data in primary HBE cells show that lumacaftor rescues A561E at equivalent efficacy of F508del, but N1303K is not significantly rescued. Login to comment
38 Compound C18 (lumacaftor analogue, also reported to rescue F508del) failed to rescue A561E-CFTR, thus plausibly rescuing CFTR by a different mechanism of action than lumacaftor. Login to comment
39 We conclude that CF patients with the A561E mutation can potentially benefit from lumacaftor and personalized medicine is the way forward to tackle CF. Login to comment
42 Culture Conditions of Primary Human Bronchial Epithelial Cells Human lung tissues from CF donors with the F508del/F508del (2 donors), A561E/A561E, N1303K/G542X, F508del/G542X and F508del/ Y1092X genotypes, were obtained from the Cardio-Thoracic Surgery Department (University Hospital la Fe, Valencia, Spain) after receiving patient's written consent and approval by the hospital Ethics Committee. Login to comment
58 Response to lumacaftor for Class II Mutants Assessed by CFTR-Mediated Chloride Secretion The effects of 24 h-treatment with lumacaftor were assessed here by determining CFTR-mediated Cl-secretion in HBE cells from CF donors with the following genotypes (Fig. 1): wt/wt control (a, b); F508del/F508del-Donor 1 (c, d); F508del/F508del-Donor 2 (e, f); A561E/A561E (Fig. 1g, h) and also on the additional genotypes (Fig. 2): N1303K/G542X (a, b), F508del/G542X (c, d); F508del/ Y1092X (e, f). Login to comment
61 These results show that Fsk + Gen responses of F508del/F508del (2 donors), A561E/A561E F508del/G542X and F508del/Y1092X cells after VX-809/lumacaftor treatment were significantly different from those under DMSO, while that of N1303K/G542X cells was not significantly different (Fig. 3b). Login to comment
63 Effect of lumacaftor (VX-809) on cAMP-induced Isc-eq in primary cultures of HBE cells from CF patients with class II mutations. Original Ussing chamber (open-circuit) recordings showing transepithelial voltage measurements (Vte) obtained for CF primary airway HBE monolayers with different CFTR genotypes: wt/wt control (a, b); F508del/F508del-donor 1 (c, d); F508del/F508del-donor 2 (e, f); and A561E/A561E (g, h). Login to comment
69 These data again clearly show a positive effect of VX-809 on HBE cells with genotypes F508del/ F508del (both donors), A561E/A561E, F508del/G542X and F508del/ Y1092X but not on N1303K/G542X cells. Login to comment
83 Original tracings and summary of the effect of C18 in A561E/A561E and F508del/F508del primary HBE cells. Login to comment
84 (a, b) represent original Ussing chamber (open-circuit) recordings obtained for the analysis of CF primary airway HBE monolayers with A561E/A561E and F508del/F508del treated with 5 bc;M C18 for 24 h. Login to comment
88 Response of A561E/A561E HBE Cells to lumacaftor and Compound C18 A561E/A561E HBE cells were also treated with C18 compound, described as a lumacaftor analogue (Eckford et al., 2014). Login to comment
89 As demonstrated by the original tracing in Fig. 4a, the responses elicited by either Fsk or Fsk + Gen in A561E/A561E cells pre-incubated with C18 are lower than those in F508del/F508del cells (Fig. 4b) and this difference is statistically different (Fig. 4c). Login to comment
90 Moreover, the response of A561E/ A561E cells after C18 treatment is also significantly lower than that in lumacaftor-treated cells, while those of F508del/F508del cells after C18 and VX-809 are similar (Fig. 1c, Table S4). Login to comment
91 Indeed, the Fold rescue of Ieq-sc-Fsk + Gen in A561E/A561E cells after C18 treatment was 1.93&#d7;, while this value was 6.51&#d7; F508del/F508del cells. Similarly, the percentages of rescue by C18 vs non-CF cells (wt/wt) were ~0.8% and ~5.0% for A561E/A561E F508del/F508del cells, respectively. Login to comment
92 These data also indicate that the response of A561/A561E HBE cells to C18 is lower than to lumacaftor, when these cells are stimulated by Gen, but interestingly, not when stimulated only by Fsk. Login to comment
93 To confirm these data, Western blot was performed in BHK cells stably expressing F508del or A561E mutant protein. Login to comment
94 Data show that VX-809 rescues both F508del and A561E-CFTR, while C18 failed to rescue A561E-CFTR but not in F508del-CFTR protein (Fig. S2). Login to comment
95 These data are thus consistent with those obtained for A561E/A561E cells treated with C18. Login to comment
103 Our data show that the effect of lumacaftor on A561E/A561E HBE cells was equivalent to that of this investigational drug in F508del/ F508del cells. Login to comment
104 Indeed, after the incubation of A561E/A561E cells with 3 bc;M lumacaftor for 24 h, responses obtained in the Ussing chamber were 7-fold higher than when cells were incubated with DMSO-vehicle, representing ~6% of rescue vs non-CF cells. Login to comment
106 These data seem to indicate that the previously characterized trafficking defect of the A561E-CFTR protein (Mendes et al., 2003) can be, as least partially, corrected by lumacaftor. Login to comment
107 Interestingly, a previous study showed that A561E-CFTR can be rescued to the cell surface by the same genetic revertants as F508del-CFTR (Roxo-Rosa et al., 2006). Login to comment
108 In another more recent study, the A561E-CFTR channel was also described to have similar mechanisms of dysfunction and response to potentiators as F508del-CFTR (Wang et al., 2014). Login to comment
111 Our data also lead to the conclusion that the A561E responses to lumacaftor and its analogue C18 do not totally overlap, as observed from the significantly lower Fsk + Gen response of A561E/A561E cells pre-incubated with C18 vs those under lumacaftor. Login to comment
113 Noticeably, however, the Fsk-response of C18-treated A561E/A561E cells is significantly higher than in the DMSO-treated cells (Fig. 4c). Login to comment
115 Nonetheless, C18 also failed to rescue A561E-CFTR as assessed by Western blot, while VX-809 induces a detectable levels of mature A561E-CFTR (Fig. S2). Login to comment
117 In contrast to the effect on A561E/A561E HBE cells, the magnitude of the response of lumacaftor-treated N1303K/G542X cells was just slightly higher by ~2-fold (both under Fsk and Gen) and not statistically different from that in DMSO-treated cells. Login to comment
120 Firstly, N1303K located in the second nucleotide binding domain (NBD2) of CFTR protein, may cause a different structural defect from that of F508del or A561E, both located in NBD1. Login to comment
123 Secondly, it is possible that the response of a single copy of N1303K (the other CFTR allele is G542X, a "null" variant) may be insufficient to observe an effect similar in magnitude to that of A561E/A561E or F508del/F508del cells. Login to comment
130 In conclusion, our data suggest that CF patients bearing the A561E mutation, which is associated with a severe clinical phenotype and quite common in some countries (Mendes et al., 2003), can potentially benefit from lumacaftor treatment. Login to comment

[hide] Predicting CFTR activity with front-runner cystic ... EBioMedicine. 2015 Jan 27;2(2):100-1. doi: 10.1016/j.ebiom.2015.01.013. eCollection 2015 Feb. Becq F
Predicting CFTR activity with front-runner cystic fibrosis drugs.
EBioMedicine. 2015 Jan 27;2(2):100-1. doi: 10.1016/j.ebiom.2015.01.013. eCollection 2015 Feb., [PMID:26137547]

Abstract [show]

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
20 The authors evaluated and compared the efficacy of correctors lumacaftor (VX-809) and its analogue C18 on epithelial cell preparations obtained from donors with different CF genotypes - homozygous for F508del, A561E or heterozygous N1303K/ G542X, F508del/G542X, F508del/Y1092X. Login to comment
22 Although they observed great variability in VX-809 responses among patients, they were able to discriminate CFTR mutants positively responding to the correctors such as A561E and Y1092X and those that failed to respond, such as N1303K. Login to comment