ABCMdb

ABCC7 p.Arg258Gly

ClinVar:	c.772A>G , p.Arg258Gly ? , not provided
CF databases:	c.772A>G , p.Arg258Gly (CFTR1) ? , This mutation was identified by DGGE and direct sequencing. This patient is an infertile male with CBAVD.
Predicted by SNAP2:	A: D (95%), C: D (95%), D: D (95%), E: D (95%), F: D (95%), G: D (95%), H: D (95%), I: D (95%), K: D (95%), L: D (95%), M: D (95%), N: D (95%), P: D (95%), Q: D (95%), S: D (95%), T: D (95%), V: D (95%), W: D (95%), Y: D (95%),
Predicted by PROVEAN:	A: D, C: D, D: D, E: D, F: D, G: D, H: D, I: D, K: N, L: D, M: D, N: D, P: D, Q: D, S: D, T: D, V: D, W: D, Y: D,

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[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.

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369 H139R, G149R, D192G and R258G in the two first CLs inhibited maturation and transport of CFTR to the cell surface. Login to comment

[hide] Expression and function of human MRP1 (ABCC1) is d... J Biol Chem. 2011 Mar 4;286(9):7202-13. Epub 2010 Dec 20. Iram SH, Cole SP
Expression and function of human MRP1 (ABCC1) is dependent on amino acids in cytoplasmic loop 5 and its interface with nucleotide binding domain 2.
J Biol Chem. 2011 Mar 4;286(9):7202-13. Epub 2010 Dec 20., 2011-03-04 [PMID:21177244]

Abstract [show]
Multidrug resistance protein 1 (MRP1) is an ATP-binding cassette transporter that effluxes drugs and organic anions across the plasma membrane. The 17 transmembrane helices of MRP1 are linked by extracellular and cytoplasmic loops (CLs), but their role in coupling the ATPase activity of MRP1 to the translocation of its substrates is poorly understood. Here we have examined the importance of CL5 by mutating eight conserved charged residues and the helix-disrupting Gly(511) in this region. Ala substitution of Lys(513), Lys(516), Glu(521), and Glu(535) markedly reduced MRP1 levels. Because three of these residues are predicted to lie at the interface of CL5 and the second nucleotide binding domain (NBD2), a critical role is indicated for this region in the plasma membrane expression of MRP1. Further support for this idea was obtained by mutating NBD2 amino acids His(1364) and Arg(1367) at the CL5 interface, which also resulted in reduced MRP1 levels. In contrast, mutation of Arg(501), Lys(503), Glu(507), Arg(532), and Gly(511) had no effect on MRP1 levels. Except for K503A, however, transport by these mutants was reduced by 50 to 75%, an effect largely attributable to reduced substrate binding and affinity. Studies with (32)P-labeled azido-ATP also indicated that whereas ATP binding by the G511I mutant was unchanged, vanadate-induced trapping of azido-ADP was reduced, indicating changes in the catalytic activity of MRP1. Together, these data demonstrate the multiple roles for CL5 in the membrane expression and function of MRP1.

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251 Similarly, a deletion mutation (⌬E278) and two missense mutations (R258G and E292K) in CFTR/ABCC7 that involve amino acids analogous to MRP1-Glu521 , -Arg501 , and -Glu535 , respectively, are associated with cystic fibrosis (48). Login to comment

[hide] Proportion of cystic fibrosis gene mutations not d... JAMA. 1999 Jun 16;281(23):2217-24. Mak V, Zielenski J, Tsui LC, Durie P, Zini A, Martin S, Longley TB, Jarvi KA
Proportion of cystic fibrosis gene mutations not detected by routine testing in men with obstructive azoospermia.
JAMA. 1999 Jun 16;281(23):2217-24., 1999-06-16 [PMID:10376575]

Abstract [show]
CONTEXT: Infertile men with obstructive azoospermia may have mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, many of which are rare in classic cystic fibrosis and not evaluated in most routine mutation screening. OBJECTIVE: To assess how often CFTR mutations or sequence alterations undetected by routine screening are detected with more extensive screening in obstructive azoospermia. DESIGN: Routine screening for the 31 most common CFTR mutations associated with the CF phenotype in white populations, testing for the 5-thymidine variant of the polythymidine tract of intron 8 (IVS8-5T) by allele-specific oligonucleotide hybridization, and screening of all exons through multiplex heteroduplex shift analysis followed by direct DNA sequencing. SETTING: Male infertility clinic of a Canadian university-affiliated hospital. SUBJECTS: Of 198 men with obstructive (n = 149) or nonobstructive (n = 49; control group) azoospermia, 64 had congenital bilateral absence of the vas deferens (CBAVD), 10 had congenital unilateral absence of the vas deferens (CUAVD), and 75 had epididymal obstruction (56/75 were idiopathic). MAIN OUTCOME MEASURE: Frequency of mutations found by routine and nonroutine tests in men with obstructive vs nonobstructive azoospermia. RESULTS: Frequency of mutations and the IVS8-5T variant in the nonobstructive azoospermia group (controls) (2% and 5.1% allele frequency, respectively) did not differ significantly from that in the general population (2% and 5.2%, respectively). In the CBAVD group, 72 mutations were found by DNA sequencing and IVS8-5T testing (47 and 25, respectively; P<.001 and P = .002 vs controls) vs 39 by the routine panel (P<.001 vs controls). In the idiopathic epididymal obstruction group, 24 mutations were found by DNA sequencing and IVS8-5T testing (12 each; P=.01 and P=.14 vs controls) vs 5 by the routine panel (P=.33 vs controls). In the CUAVD group, 2 mutations were found by routine testing (P=.07 vs controls) vs 4 (2 each, respectively; P=.07 and P=.40 vs controls) by DNA sequencing and IVS8-5T testing. The routine panel did not identify 33 (46%) of 72, 2 (50%) of 4, and 19 (79%) of 24 detectable CFTR mutations and IVS8-5T in the CBAVD, CUAVD, and idiopathic epididymal obstruction groups, respectively. CONCLUSIONS: Routine testing for CFTR mutations may miss mild or rare gene alterations. The barrier to conception for men with obstructive infertility has been overcome by assisted reproductive technologies, thus raising the concern of iatrogenically transmitting pathogenic CFTR mutations to the progeny.

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45 (%) Men With 2 Mutations ⌬F508/IVS8-5T 7 (11) ⌬F508/IVS8-5T 1 (10) ⌬F508/IVS8-5T 1 (1.8) ⌬F508/R117H 6 (9) W1282X/IVS8-5T 1 (1.8) ⌬F508/L206W 1 (1.6) G544S/IVS8-5T 1 (1.8) ⌬F508/M952T 1 (1.6) V754M/-741T→G 1 (1.8) ⌬F508/P67L 1 (1.6) R75Q/R258G 1 (1.8) ⌬F508/S549R 1 (1.6) R334W/R334W 1 (1.6) R117H/R117H 1 (1.6) R117H/IVS8-5T 1 (1.6) R347P/IVS8-5T 1 (1.6) N1303K/IVS8-5T 1 (1.6) 1677delTA/IVS8-5T 1 (1.6) R117L/IVS8-5T 1 (1.6) D979A/IVS8-5T 1 (1.6) IVS8-5T/IVS8-5T 1 (1.6) Men With 1 Mutation IVS8-5T/N 10 (16) ⌬F508/N 1 (10) IVS8-5T/N 9 (16) ⌬F508/N 1 (2) ⌬F508/N 6 (9) IVS8-5T/N 1 (10) ⌬F508/N 1 (1.8) G542X/N 1 (2) W1282X/N 2 (3) R75Q/N 1 (1.8) IVS8-5T/N 5 (10) L206W/N 1 (1.6) W1282X/N 1 (1.8) 4016insT/N 1 (1.6) R117H/N 1 (1.8) 2423delG/N 1 (1.8) Men With No Mutations 18 (28) 7 (70) 37 (66) 42 (86) *N indicates that no CFTR mutations or variants were detected. Login to comment
58 (%) 31 Mutation panel† ⌬F508 23 (18) ⌬F508 2 (10) ⌬F508 2 (1.8) ⌬F508 1 (1) R117H 9 (7) W1282X 2 (1.8) G542X 1 (1) W1282X 2 (1.6) R117H 1 (0.9) R334W 2 (1.6) S549R 1 (0.8) R347P 1 (0.8) N1303K 1 (0.8) Extensive screen† ⌬F508 23 (18) ⌬F508 2 (10) ⌬F508 2 (1.8) ⌬F508 1Mutations included in R117H 9 (7) W1282X 2 (1.8) G542X 131 mutation panel W1282X 2 (1.6) R117H 1 (0.9) R334W 2 (1.6) S549R 1 (0.8) R347P 1 (0.8) N1303K 1 (0.8) L206W 2 (1.6)‡ R75Q 2 (1.8)‡Mutations not included in P67L 1 (0.8)‡ G544S 1 (0.9)‡31 mutation panel 1677delTA 1 (0.8)‡ 2423delG 1 (0.9)‡ R117L 1 (0.8)‡ V754M 1 (0.9)‡ 4016insT 1 (0.8)‡ -741T→G 1 (0.9)‡ D979A 1 (0.8)§ R258G 1 (0.9)§ M952T 1 (0.8)¶ IVS8-5T 25 (20)# 2 (10) 12 (11) 5 (5) Detectable mutations 72 (56)# 4 (20) 24 (21)# 7 (7) Detectable mutations missed by 31 mutation panel 33 (46) 2 (50) 19 (79) Detectable non-IVS8-5T mutations missed by 31 mutation panel 8 (17) 0 (0) 7 (58) *Percentages indicate allele frequency. Login to comment
73 Of the 7 additional mutations, G544S, 2423delG, V754M, and -741T→G are associated with the CF phenotype and R258G with the CBAVD phenotype, while R75Q (identified in 2 subjects), previously thought to be a benign polymorphism, may in fact confer phenotypic features of CF.2 Therefore, of the 24 alleles with CFTR mutations in men with idiopathic epididymal obstruction, 5 (21%) were identified by routine CFTR mutation analysis, 12 (50%) by IVS8-5T allele-specificoligonucleotideanalysis,and 12 (50%) by complete analysis of all CFTR exons. Login to comment
85 These mild CFTR gene mutations are associated with pancreatic sufficiency and tend to be class 4 through 5 mutations: R117H, R334W, R347P, L206W,andP67L.Thethirdgroupcon- sists of mutations identified exclusively in some men with obstructive azoospermia; however, because these sequencealterationsareextremelyrare, it is only speculated that they contribute to this phenotype.7,10,12 These CFTR genesequencechangesincludeD979A, R258G, and M952T. Login to comment

[hide] Heterogeneity for mutations in the CFTR gene and c... Hum Reprod. 2000 Jul;15(7):1476-83. Casals T, Bassas L, Egozcue S, Ramos MD, Gimenez J, Segura A, Garcia F, Carrera M, Larriba S, Sarquella J, Estivill X
Heterogeneity for mutations in the CFTR gene and clinical correlations in patients with congenital absence of the vas deferens.
Hum Reprod. 2000 Jul;15(7):1476-83., [PMID:10875853]

Abstract [show]
Congenital absence of the vas deferens (CAVD) is a heterogeneous disorder, largely due to mutations in the cystic fibrosis (CFTR) gene. Patients with unilateral absence of the vas deferens (CUAVD) and patients with CAVD in association with renal agenesis appear to have a different aetiology to those with isolated CAVD. We have studied 134 Spanish CAVD patients [110 congenital bilateral absence of the vas deferens (CBAVD) and 24 CUAVD], 16 of whom (six CBAVD, 10 CUAVD) had additional renal anomalies. Forty-two different CFTR mutations were identified, seven of them being novel. Some 45% of the CFTR mutations were specific to CAVD, and were not found in patients with cystic fibrosis or in the general Spanish population. CFTR mutations were detected in 85% of CBAVD patients and in 38% of those with CUAVD. Among those patients with renal anomalies, 31% carried one CFTR mutation. Anomalies in seminal vesicles and ejaculatory ducts were common in patients with CAVD. The prevalence of cryptorchidism and inguinal hernia appeared to be increased in CAVD patients, as well as nasal pathology and frequent respiratory infections. This study confirms the molecular heterogeneity of CFTR mutations in CAVD, and emphasizes the importance of an extensive CFTR analysis in these patients. In contrast with previous studies, this report suggests that CFTR might have a role in urogenital anomalies.

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97 Dilatation V232D/V232D 9T/9T 1 of ejaculatory ducts, often resembling utricular cysts, was S945L/R258G 7T/7T 1 demonstrable also in some men, all of whom were azoospermicG551D/F1074L 5T/7T 1 A1006E/L383S 5T/7T 1 (Figure 1). Login to comment

[hide] Adenosine triphosphate-binding cassette superfamil... Biol Reprod. 2001 Aug;65(2):394-400. Larriba S, Bassas L, Egozcue S, Gimenez J, Ramos MD, Briceno O, Estivill X, Casals T
Adenosine triphosphate-binding cassette superfamily transporter gene expression in severe male infertility.
Biol Reprod. 2001 Aug;65(2):394-400., [PMID:11466205]

Abstract [show]
Cystic fibrosis transmembrane regulator (CFTR), multidrug-resistant (MDR)1, and multidrug resistance-associated (MRP) proteins belong to the ATP-binding cassette (ABC) transporter superfamily. A compensatory regulation of MDR1 and CFTR gene expression has been observed in CFTR knockout rodent intestine and in an epithelial cell line of human colon, whereas a high homology and similar anion binding site are shared by MRP and CFTR proteins. To provide better insight into the relationship among the expression behavior in vivo of the three genes in human testis, analysis of MDR1 and MRP gene expression in testicular biopsies was performed and related to the presence of CFTR gene mutations in congenital absence of the vas deferens (CAVD: n = 20) and non-CAVD (n = 30) infertile patients with azoospermia or severe oligozoospermia. A CFTR mutation analysis performed in both groups of patients supported the involvement of CFTR gene mutations in CAVD phenotype (85%) and in defective spermatogenesis (19%). Quantitative reverse transcription-polymerase chain reaction analysis of testicular tissue showed a CFTR-independent MDR1 and MRP gene expression in human testis, suggesting that the mechanisms underlying CFTR gene regulation in testis are different from those in intestine. These findings should contribute to the understanding of patterns of in vivo expression of CFTR, MDR1, and MRP genes in CFTR-related infertility.

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87 Phenotypical and genotypical description of CAVD and non-CAVD infertile patients.a No. patient Phenotype FSH (U/L) Non-CFTR infertility-associated factors Testicular biopsy CFTR mutation M470V polymorphism CAVD infertility 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 CBAVD CBAVD CBAVD CBAVD CBAVD CBAVD CBAVD CBAVD CBAVD CBAVD CBAVD CBAVD CBAVD CBAVD CBAVD CBAVD CUAVD CUAVD CUAVD CUAVD 3.1 7.3 3.1 2.4 1.9 3.5 5.7 4.3 3.6 ND 2.2 4.8 11.3 2.1 ND 7.6 5.3 6.5 3.9 21.4 None None None None None None None None None None None None None None None None None None None Yes 1 Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes V232D/V232D F508del/R117H F508del/R117H G542X/2789ϩ5GϾA F508del/D1270N ϩ R74W F508del/D1270N ϩ R74W S945L/R258G F508del/5T F508del/5T L206W/5T R117H/N F508del/N Y1014C/N 5T/N N/N N/N Y1092X/R258G 621ϩ1GϾT/5T Q890R/N N/N M/M M/M M/M M/M M/V M/V M/V M/M M/V M/V M/V M/V M/V M/V M/M V/V V/V M/V V/V M/M Non-CAVD infertility 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 TF (SA) TF (SA) TF (SA) TF (SA) TF (SA) TF (SA) TF (SA) TF (SA) TF (SA) TF (SSO) TF (SSO) TF (SSO) TF (SSO) TF (SSO) TF (SSO) TF (SSO) TF (SSO) TF (SSO) TF (SSO) TF (SA) TF (SA) TF (SSO) OA OA OA OA OA OA OA OA 42.0 15.9 34.8 8.9 26.3 6.4 7.8 15.6 8.7 3.2 3.9 12.6 4.7 1.3 5.6 3.9 6.1 9.3 8.8 19.3 9.6 ND 3.3 5.9 6.6 3.6 1.9 4.2 2.0 4.4 None None None None None None None None None None None None None None None None Yes 2 Yes 2 Yes 2, 3 Yes 4 Yes 5 Yes 6 None None None None None Yes 1 Yes 7 Yes 8 Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes F508del/N R334W/N N/N N/N N/N N/N N/N N/N N/N R75Q/N N/N N/N N/N N/N N/N N/N N/N N/N N/N N/N N/N N/N 5T/5T N/N N/N N/N N/N N/N N/N N/N M/M V/V M/V M/V M/V M/V V/V V/V V/V V/V M/V M/V M/V ND V/V M/M M/V M/M M/V M/M M/V V/V M/V M/V M/V V/V V/V M/V M/V V/V a CFTR mutations and M470V allele are also described for each patient. Login to comment
94 CFTR Analysis We have identified 14 different CFTR mutations (R117H, L206W, V232D, R258G, F508del, G542X, 621ϩ1GϾT, Q890R, S945L, Y1014C, Y1092X, D1270N, 2789ϩ5GϾA, IVS8-6[5T]) in 17 of 20 patients of the CAVD group, giving a CFTR mutation frequency of 85%. Login to comment

[hide] Analysis of cystic fibrosis transmembrane conducta... Am J Med Genet A. 2003 Jul 1;120A(1):72-6. Timmreck LS, Gray MR, Handelin B, Allito B, Rohlfs E, Davis AJ, Gidwani G, Reindollar RH
Analysis of cystic fibrosis transmembrane conductance regulator gene mutations in patients with congenital absence of the uterus and vagina.
Am J Med Genet A. 2003 Jul 1;120A(1):72-6., 2003-07-01 [PMID:12794695]

Abstract [show]
The relationship between cystic fibrosis transmembrane conductance regulator gene (CFTR) mutations and congenital absence of the uterus and vagina (CAUV) was examined. CFTR mutations have previously been associated with congenital bilateral absence of the vas deferens (CBAVD). CBAVD is caused by a disruption in the vas deferens, a Wolffian duct derivative. Because the embryologic development of the Mullerian ducts directly depends on the prior normal development of the Wolffian ducts, the same gene products may be necessary for normal embryologic development of both ductal systems. This study evaluated the role of CFTR mutations in the development of CAUV. DNA samples from 25 patients with CAUV were tested for the presence of 33 of the most common CFTR mutations. Protein-coding DNA fragments from the CFTR gene were amplified in vitro by the polymerase chain reaction (PCR) and analyzed for mutations using allele-specific oligonucleotide (ASO) probes. Two patients were heterozygous for CFTR mutations. One was heterozygous for the W1282X mutation and the other was heterozygous for the DeltaF508 mutation. The incidence of the 33 CFTR mutations found in the patients with CAUV (8%) was twice that found in the general population (4%), but much less than the incidence of CFTR mutations in men with CBAVD (80%). This data suggests that it is unlikely for CFTR mutations to cause CAUV in females as they cause CBAVD in some males. Furthermore, the data suggest that CAUV in females may be the same disorder as CBAVD in males who do not have CFTR mutations.

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69 Mutations continue to be identified in association with CBAVD: A800G, G149R, R258G, E193K [Mercier et al., 1995], D1270N, and G576A [Ravnik-Glavac et al., 2000], to name a few. Login to comment

[hide] Different CFTR mutational spectrum in alcoholic an... Pancreas. 2004 May;28(4):374-9. Casals T, Aparisi L, Martinez-Costa C, Gimenez J, Ramos MD, Mora J, Diaz J, Boadas J, Estivill X, Farre A
Different CFTR mutational spectrum in alcoholic and idiopathic chronic pancreatitis?
Pancreas. 2004 May;28(4):374-9., [PMID:15097853]

Abstract [show]
OBJECTIVE: Cystic fibrosis transmembrane conductance regulator (CFTR) mutations are responsible for cystic fibrosis (CF) and have been postulated as a predisposing risk factor to chronic pancreatitis (CP), but controversial results demand additional support. We have therefore investigated the role of the CFTR gene in a cohort of 68 CP patients. METHODS: We have performed the CFTR gene analysis using 2 screening techniques. Fragments showing abnormal migration patterns were characterized by sequencing. Patients were classified in alcoholic (ACP) (n = 37) and idiopathic (ICP) (n = 31) chronic pancreatitis. Clinical features of CP and CF were evaluated. RESULTS: Sixteen mutations/variants were identified in 27 patients (40%), most of them (35%) presenting a single CFTR mutant gene. The 1716G/A variant showed the highest frequency accounting for 22% in ICP and 5% in ACP, in contrast with other more common mutations such as F508del found in 8% of ACP and the 5T variant identified in 7% of patients. Acute pancreatitis, abdominal pain, tobacco, pancreatic calcifications, and pancreatic pseudocysts showed significant higher values in ACP than ICP patients. No significant differences were found between patients with and without CFTR mutations. CONCLUSIONS: Apart from reinforcing previous findings our data highlight the increased susceptibility of CFTR heterozygous to developing CP. Heterozygosity, combined with other factors, places these individuals at greater risk.

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63 Time Years BMI Alcohol Alcohol Time Years Tobacco Pancreatic Features Hepatobiliary Disease CFTR Genotype Sweat Test mmol/L FEV1/FVC % Predicted Male Fertility Alcoholic Chronic Pancreatitis (n = 15) 1 M/52 15 24.5 110g/d 27 yes AP, P, Ps, DM, PI Chronic hepatitisa F508del/S1235R 18 105/107 yes 2 M/72 15 23.4 85g/d 22 yes AP, P, C, PS no F508del/1716G/A 72 90/104 yes 3 M/53 10 21.9 135g/d 20 yes P, C, DM, PI no F508del/- 54 71/89 yes 4 M/64 18 20.7 250g/d 27 yes AP, P, C, Ps, DM, PI cirrhosis, lithiasis W1282X/- 68 71/78 unproved 5 M/44 13 22.0 95g/d 6 yes AP, P, C, Ps, DM, PI lithiasis R170C/- 16 105/111 yes 6 M/62 12 22.1 >60g/d >5 yes AP, P, C, Ps, DM, PS no R258G/- 82 73/82 yes 7 M/38 9 18.0 210g/d 15 yes AP, P, C, Ps, PS no M281T/- 62 132/126 yes 8 M/40 11 - >60g/d >5 yes AP, P, C, Ps, PS lithiasis R297Q/- 46 103/99 yes 9 M/42 2 21.4 150g/d 20 yes AP, P, C, Ps, PS no 1716G/A/- 19 93/102 yes 10 M/44 3 22.2 95g/d 22 yes AP, P, DM, PS no R668C/- 58 105/102 yes 11 M/59 6 21.8 90g/d 18 yes PS lithiasis L997F/- 85 69/84 nd 12 M/72 16 - >60g/d >5 no P, C, DM, PI lithiasis R1162L/- - - yes 13 M/35 8 21.0 90g/d 7 yes AP, P, C, PS no 5T-12TG-V470/- 13 106/114 unproved 14 M/60 14 28.0 80g/d 20 no AP, P, C, Ps, DM, PI no 5T-11TG/- 28 80/77 yes 15 M/65 12 24.4 100g/d 23 yes AP, P, C, DM, PS no 5T-11TG/ 40 86/110 yes Idiopathic Chronic Pancreatitis (n = 12) 16 M/21 5 - no - yes AP, P, PS no 1716G/A/R170H 40 normal yes 17 M/59 4 24.2 no - no PS chronic hepatitisb 1716G/A/- 40 146/128 yes 18 M/63 14 21.4 no - no DM, PI no 1716G/A/- 34 144/126 yes 19 M/70 18 19.9 no - yes AP, P, DM, PI chronic hepatitisa 1716G/A/- 60 36/47 yes 20 M/65 1 27.7 no - yes P, Ps, DM, PI no 1716G/A/- 38 79/78 yes 21 M/76 8 24.1 no - no AP, P, DM, PS no 1716G/A/- 60 81/109 yes 22 M/25 2 25.0 no - yes AP, P, PS no 1716G/A/- 48 94/86 nd 23 F/42 10 22.6 no - yes P, C, PS lithiasis P205S/- 72 111/109 - 24 F/81 21 34.6 no - no P, C, DM, PI lithiasis D443Y+G+R*/- 42 121/108 - 25 F/72 8 23.3 no - yes AP, C, PS no L997F/- 40 100/93 - 26 M/9 2 19.2 no - no AP, P, PS no 5T-11TG/- 30 101/110 nd 27 M/63 6 - no - no C, DM, PI cirrhosis 5T-11TG/- - - yes a C virus hepatitis. Login to comment

[hide] Rescue of DeltaF508 and other misprocessed CFTR mu... Mol Pharm. 2005 Sep-Oct;2(5):407-13. Loo TW, Bartlett MC, Clarke DM
Rescue of DeltaF508 and other misprocessed CFTR mutants by a novel quinazoline compound.
Mol Pharm. 2005 Sep-Oct;2(5):407-13., [PMID:16196493]

Abstract [show]
Cystic fibrosis (CF) is most commonly caused by deletion of Phe508 in the cystic fibrosis transmembrane conductance regulator protein (DeltaF508 CFTR). The misfolded DeltaF508 CFTR protein is retained in the endoplasmic reticulum (misprocessed mutant) and is rapidly degraded. Studies on misprocessed mutants of P-glycoprotein (P-gp), a sister protein of CFTR, however, have shown that specific substrates and modulators can act as specific chemical/pharmacological chaperones to rescue the protein. A major goal in CF research is the identification of compounds that can be used at low concentrations to rescue misprocessed CFTR mutants. Here, we show that a novel quinazoline derivative, 4-cyclohexyloxy-2-{1-[4-(4-methoxy-benzenesulfonyl)piperazin-1-yl]ethyl}qu inazoline (CF(cor)-325), rescued DeltaF508 CFTR. Incubation of BHK cells stably expressing human DeltaF508 CFTR with 1-10 microM CF(cor)-325 resulted in maturation and delivery of a functional molecule to the cell surface as determined by the iodide efflux assay. The misprocessed CFTR mutants R258G, S945L, and H949Y were also rescued by CF(cor)-325 in either BHK or HEK 293 cells. CF(cor)-325 appeared to be specific for DeltaF508 CFTR because another quinazoline derivative, prazosin, did not rescue the misprocessed CFTR mutants. CF(cor)-325 could also rescue misprocessed mutants of P-gp. The compound was a P-gp inhibitor as it inhibited vinblastine-stimulated ATPase activity. P-gp-mediated vinblastine resistance was also reduced about 10-fold with 300 nM CF(cor)-325. These results show that CF(cor)-325 is a particularly important lead compound for treatment of CF because low concentrations can be used to rescue many misprocessed CFTR mutants.

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No. Sentence Comment
5 Incubation of BHK cells stably expressing human ∆F508 CFTR with 1-10 µM CFcor-325 resulted in maturation and delivery of a functional molecule to the cell surface as determined by the iodide efflux assay. The misprocessed CFTR mutants R258G, S945L, and H949Y were also rescued by CFcor-325 in either BHK or HEK 293 cells. Login to comment
26 Wild-type, ∆F508, H139R, G149R, R258G, S945L, and H949Y CFTR cDNAs were inserted into the pcDNA3 (Invitrogen, Oakville, ON) vector as described previously.13,14 Wild-type and mutant G268V P-gp cDNAs were inserted into the pMT21 vector (Genetics Institute) as described previously.15 Baby hamster kidney (BHK) cells stably expressing CFTR or P-gp were generated by cotransfection with cDNA and pWL-neo (Stratagene, Cedar Creek, TX). Login to comment
132 (C) BHK cells expressing misprocessed CFTR mutants H139R, G149R, R258G, S945L, H949Y, or wild-type CFTR were incubated for 48 h with (+) or without (-) 3 µM CFcor-325. Whole cell extracts were subjected to immunoblot analysis with a rabbit polyclonal antibody against CFTR. Login to comment
144 BHK cells expressing mutants H139R, G149R, and R258G in the first transmembrane domain (TMD1)30 or mutants S945L and H949Y in TMD213 were treated with or without 3 µM CFcor-325 for 48 h. Whole cell SDS extracts were then subjected to immunoblot analysis. Login to comment
145 The presence of CFcor-325 significantly enhanced maturation of mutants R258G, S945L, and H949Y (Figure 2C). Login to comment
178 It was possible to promote maturation of some mutants that had mutations in different domains of CFTR including NBD1 (∆F508), TMD1 (R258G in the second intracellular loop), and TMD2 (S945L and H949Y in the third intracellular loop). Login to comment
24 Wild-type, ∆F508, H139R, G149R, R258G, S945L, and H949Y CFTR cDNAs were inserted into the pcDNA3 (Invitrogen, Oakville, ON) vector as described previously.13,14 Wild-type and mutant G268V P-gp cDNAs were inserted into the pMT21 vector (Genetics Institute) as described previously.15 Baby hamster kidney (BHK) cells stably expressing CFTR or P-gp were generated by cotransfection with cDNA and pWL-neo (Stratagene, Cedar Creek, TX). Login to comment
130 (C) BHK cells expressing misprocessed CFTR mutants H139R, G149R, R258G, S945L, H949Y, or wild-type CFTR were incubated for 48 h with (+) or without (-) 3 µM CFcor-325. Whole cell extracts were subjected to immunoblot analysis with a rabbit polyclonal antibody against CFTR. Login to comment
142 BHK cells expressing mutants H139R, G149R, and R258G in the first transmembrane domain (TMD1)30 or mutants S945L and H949Y in TMD213 were treated with or without 3 µM CFcor-325 for 48 h. Whole cell SDS extracts were then subjected to immunoblot analysis. Login to comment
143 The presence of CFcor-325 significantly enhanced maturation of mutants R258G, S945L, and H949Y (Figure 2C). Login to comment
176 It was possible to promote maturation of some mutants that had mutations in different domains of CFTR including NBD1 (∆F508), TMD1 (R258G in the second intracellular loop), and TMD2 (S945L and H949Y in the third intracellular loop). Login to comment

[hide] Molecular characterization of the cystic fibrosis ... Genet Med. 2007 Mar;9(3):163-72. Grangeia A, Sa R, Carvalho F, Martin J, Girodon E, Silva J, Ferraz L, Barros A, Sousa M
Molecular characterization of the cystic fibrosis transmembrane conductance regulator gene in congenital absence of the vas deferens.
Genet Med. 2007 Mar;9(3):163-72., [PMID:17413420]

Abstract [show]
PURPOSE: Approximately 20% of patients with congenital absence of the vas deferens remain without two mutations identified. We applied a strategy of serial screening steps to 45 patients with congenital absence of the vas deferens and characterized cystic fibrosis transmembrane conductance regulator gene mutations in all cases. METHODS: DNA samples of 45 patients with congenital absence of the vas deferens were screened by successive different molecular genetics approaches. RESULTS: Initial screening for the 31 most frequent cystic fibrosis mutations, IVS8 poly(TG)m, poly(T)n, and M470V polymorphisms, identified 8 different mutations in 40 patients (88.9%). Extensive cystic fibrosis transmembrane conductance regulator gene analysis by denaturing gradient gel electrophoresis, denaturing high-performance liquid chromatography, and DNA sequencing detected 17 further mutations, of which three were novel. Cystic fibrosis transmembrane conductance regulator gene rearrangements were searched by semiquantitative fluorescent multiplex polymerase chain reaction, which detected a CFTRdele2,3 (21 kb) large deletion and confirmed two homozygous mutations. Overall, 42 patients (93.3%) had two mutations and 3 patients (6.7%) had one mutation detected. CONCLUSIONS: The present screening strategy allowed a higher mutation detection rate than previous studies, with at least one cystic fibrosis transmembrane conductance regulator gene mutation found in all patients with congenital absence of the vas deferens.

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93 DeltaF508 was the second most common mutation, representing 21 (23.3%) of total alleles, followed by R334W (6, Table 1 CFTR gene mutations and polymorphisms in patients with congenital absence of the vas deferens Mutation Location Nucleotide alteration Effect Method 1 CFTRdele2,3 Exons 2-3 Deletion of exons 2 and 3 Frameshift QFM-PCR 2 R117H Exon 4 G¡A at 482 AA substitution 31 mutation panel 3 P205S Exon 6a C¡T at 745 AA substitution DGGE/dHPLC 4 L206W Exon 6a T¡G at 749 AA substitution DGGE/dHPLC 5 R258G Exon 6b A¡G at 904 AA substitution DGGE/dHPLC 6 R334W Exon 7 C¡T at 1132 AA substitution 31 mutation panel 7 T5 allele Intron 8 Deletion of 2T at 1342-12 to -6 Aberrant splicing DGGE/DNA sequencing 8 P439S Exon 9 C¡T at 1447 AA substitution DGGE/dHPLC 9 D443Ya Exon 9 G¡T at 1459 AA substitution DGGE/dHPLC 10 I507del Exon 10 Deletion of 3 bp at 1648-1653 AA deletion 31 mutation panel 11 DeltaF508 Exon 10 Deletion of 3 bp at 1652-1655 AA deletion 31 mutation panel 12 G542X Exon 11 G¡T at 1756 Truncation 31 mutation panel 13 V562I Exon 12 G¡A at 1816 AA substitution DGGE/dHPLC 14 G576Aa Exon 12 G¡C at 1859 Aberrant splicing DGGE/dHPLC 15 D614G Exon 13 A¡G at 1973 AA substitution DGGE/dHPLC 16 R688Ca Exon 13 C¡T at 2134 AA substitution DGGE/dHPLC 17 V754M Exon 13 G¡A at 2392 AA substitution DGGE/dHPLC 18 E831X Exon 14a G¡T at 2623 Truncation DGGE/dHPLC 19 3272-26AϾG Intron 17a A¡G at 3272-26 Aberrant splicing DGGE/dHPLC 20 2789ϩ5G¡A Intron 14b G¡A at 2789ϩ5 Aberrant splicing 31 mutation panel 21 V1108L Exon 17b G¡C at 3454 AA substitution DGGE/dHPLC 22 L1227S Exon 19 T¡C at 3812 AA substitution DGGE/dHPLC 23 S1235R Exon 19 T¡G at 3837 AA substitution DGGE/dHPLC 24 P1290S Exon 20 C¡T at 4000 AA substitution DGGE/dHPLC 25 N1303K Exon 21 C¡G at 4041 AA substitution 31 mutation panel 26 E1401K Exon 23 G¡A at 4333 AA substitution DGGE/dHPLC Polymorphisms 1 TG repeats Intron 8 9-13 copies at 1342-12 to -35 Sequence variation DGGE/DNA sequencing 2 M470V Exon 10 A or G at 1540 Sequence variation DNA sequencing 3 125G/C Exon 1 G¡C at 125 Sequence variation DGGE/dHPLC 4 1001ϩ11T/C Intron 6b C¡4T at 1001ϩ11 Sequence variation DGGE/dHPLC 5 1716G/A Exon 10 G¡A at 1716 Sequence variation DGGE/dHPLC 6 1899-136T/G Intron 12 T¡G at 1899-136 Sequence variation DGGE/dHPLC 7 T854T Exon 14a T¡G at 2694 Sequence variation DGGE/dHPLC 8 3601-65C/A Intron 18 C¡A at 3601-65 Sequence variation DGGE/dHPLC 9 4521G/A Exon 24 G¡A at 4521 Sequence variation DGGE/dHPLC QFM-PCR, semiquantitative fluorescent multiplex polymerase chain reaction; bp, base pair; DGGE, denaturing gradient gel electrophoresis; dHPLC, denaturing high-performance liquid chromatography. Login to comment
101 The missense M470V polymorphism was evaluated in all 45 pa- tientswithCAVD(Table2).TheallelicfrequencyoftheM470variant Table 2 CFTR genotypes identified in patients with congenital absence of the vas deferens CFTR mutation genotypes [(TG)mTn] genotype M470V Patients N % DeltaF508 (TG)10T9 (TG)12T5 M V 11 24.4 DeltaF508 (TG)10T9 (TG)11T5 M M 1 2.2 DeltaF508 R117H (TG)10T9 (TG)10T7 M M 2 4.4 G542X (TG)10T9 (TG)12T5 M V 2a 4.4 DeltaF508 R334W (TG)10T9 (TG)11T7 M V 1 2.2 DeltaF508 D443Y-G576A-R668C (TG)10T9 (TG)10T7 M M 1 2.2 DeltaF508 D614G (TG)10T9 (TG)11T7 M V 1 2.2 DeltaF508 E831X (TG)10T9 (TG)11T7 M V 1 2.2 DeltaF508 L1227S (TG)10T9 (TG)11T7 M M 1 2.2 DeltaF508 E1401K (TG)10T9 (TG)11T7 M V 1 2.2 I507del D614G (TG)11T7 (TG)10T7 M V 1 2.2 N1303K L206W (TG)10T9 (TG)9T9 M M 1 2.2 R117H P205S (TG)11T7 (TG)10T7 M V 1 2.2 R117H R334W (TG)10T7 (TG)11T7 M V 1 2.2 R334W P439S (TG)11T7 (TG)11T7 M V 1 2.2 R334W R334Wb (TG)11T7 (TG)11T7 V V 1 2.2 R334W V562I (TG)11T7 (TG)11T5 V M 1 2.2 D443Y-G576A-R668C 3272-26A¡G (TG)10T7 (TG)10T7 M M 1 2.2 G576A-R668C V754Mb (TG)10T7 (TG)11T7 M M 1 2.2 S1235R S1235Rb (TG)13T5 (TG)13T5 M M 1 2.2 2789ϩ5G¡A S1235Rb (TG)10T7 (TG)13T5 M M 1 2.2 3272-26A¡G P1290S (TG)11T7 (TG)10T7 M V 1 2.2 P205S (TG)11T7 (TG)12T5 V V 1 2.2 G576A-R668C b (TG)10T7 (TG)11T5 M M 1 2.2 V1108L b (TG)11T7 (TG)11T5 V M 1 2.2 N1303K (TG)10T9 (TG)12T5 M V 1 2.2 3272-26A¡G b (TG)10T7 (TG)12T5 M V 1 2.2 CFTRdele2,3 b (TG)11T7 (TG)13T5 V M 1 2.2 b (TG)11T5 (TG)12T5 M V 1 2.2 b (TG)13T5 (TG)12T5 M V 1 2.2 DeltaF508 - (TG)10T9 (TG)11T7 M V 1a 2.2 L206W -b (TG)9T9 (TG)11T7 M V 1 2.2 R258G -b (TG)11T7 (TG)11T7 V V 1 2.2 a CUAVD. Login to comment
110 Large Table 3 Allelic frequencies of CFTR mutations in patients with congenital absence of the vas deferens CBAVD CUAVD Total Patients 42 3 45 Alleles 84 6 90 Mutations N % N % N % 1 T5 allele 26a 31 2 33.3 28 31.1 2 DeltaF508 20 23.8 1 16.7 21 23.3 3 R334W 6a 7.1 0 0 6 6.7 4 R117H 4 4.8 0 0 4 4.4 5 G576A 4b 4.8 0 0 4 4.4 6 R688C 4b 4.8 0 0 4 4.4 7 S1235R 3a 3.6 0 0 3 3.3 8 3272-26A¡G 3 3.6 0 0 3 3.3 9 P205S 2 2.4 0 0 2 2.2 10 L206W 2 2.4 0 0 2 2.2 11 D443Y 2b 2.4 0 0 2 2.2 13 D614G 2 2.4 0 0 2 2.2 14 N1303K 2 2.4 0 0 2 2.2 12 G542X 0 0 2 33.3 2 2.2 15 R258G 1 1.2 0 0 1 1.1 16 P439S 1 1.2 0 0 1 1.1 17 I507del 1 1.2 0 0 1 1.1 18 V562I 1 1.2 0 0 1 1.1 19 V754M 1 1.2 0 0 1 1.1 20 E831X 1 1.2 0 0 1 1.1 21 2789ϩ5G¡A 1 1.2 0 0 1 1.1 22 V1108L 1 1.2 0 0 1 1.1 23 L1227S 1 1.2 0 0 1 1.1 24 P1290S 1 1.2 0 0 1 1.1 25 E1401K 1 1.2 0 0 1 1.1 26 CFTRdele2,3 1 1.2 0 0 1 1.1 CBAVD, congenital bilateral absence of the vas deferens; CUAVD, congenital unilateral absence of the vas deferens. Login to comment

[hide] Independent contribution of common CFTR variants t... Pancreas. 2010 Mar;39(2):209-15. de Cid R, Ramos MD, Aparisi L, Garcia C, Mora J, Estivill X, Farre A, Casals T
Independent contribution of common CFTR variants to chronic pancreatitis.
Pancreas. 2010 Mar;39(2):209-15., [PMID:19812525]

Abstract [show]
OBJECTIVE: We have assessed whether CFTR gene has a major impact on chronic pancreatitis (CP) pathogenesis than that provided by the CFTR mutations. For this aim, we have evaluated clinical parameters, CFTR mutations, and 3 potential regulatory CFTR variants (coding single-nucleotide polymorphisms): c.1540A>G, c.2694T>G, and c.4521G>A. METHODS: CFTR gene analysis was performed in a cohort of 136 CP patients and 93 controls from Spanish population using current scanning techniques (single-strand conformation polymorphism/heteroduplex, denaturing gradient gel electrophoresis, and denaturing high-performance liquid chromatography) and direct sequencing. RESULTS: A higher frequency of CFTR mutations were observed in patients (39%) than in controls (15%; P < or = 0.001), differences being mostly attributable to the prevalence of the cystic fibrosis (CF)-causing mutations (P = 0.009). The analysis of variants has shown statistically significant differences between patients and controls for c.4521G>A (Pcorrected = 0.036). Furthermore, the multi-marker analysis revealed that the 1540A;2694G;4521A (AGA) haplotype was more prevalent in CP than controls (Pcorrected = 0.042). Remarkably, this association was unrelated to CF-causing mutations (P = 0.006). CONCLUSIONS: Our results corroborate the higher susceptibility of CF carriers to CP and, furthermore, suggest that the AGA haplotype could contribute to an increased risk in the development of CP irrespective of other CF-causing mutations.

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81 CFTR Genotypes in Chronic Pancreatitis Patients and General Population Pt/Phenotype CFTR Genotype Pt/Phenotype CFTR Genotype 1/ACP F508del† , I1027T/j 19/ACP* R668C/j 2/ACP* F508del† /j 20/ACP D836Y/j 3/ACP F508del† , I1027T/Y1014C 21/ACP* L997F† /j 4/ACP F508del† /1716G9A 22/ACP* R1162L/j 5/ACP* F508del† /1716G9A 23/ACP 5T-11TG/j 6/ACP* F508del† /S1235R 24/ACP 5T-11TG/j 7/ACP G542X† /j 25/ACP 5T-11TG/j 8/ACP* W1282X† /j 26/ACP* 5T-11TG/j 9/ACP 5T-12TG† /5T-11TG 27/ACP* 5T-11TG/j 10/ACP* 5T-12TG† /j 28/ACP 1716G9A/4374+13A9G 11/ACP R75Q/j 29/ACP 1716G9A/j 12/ACP R75Q/j 30/ACP 1716G9A/j 13/ACP Y122C/Y122C 31/ACP 1716G9A/j 14/ACP* R170C/j 32/ACP 1716G9A/j 15/ACP* R258G/j 33/ACP* 1716G9A/j 16/ACP* M281T/j 34/ACP 2377C9T/j 17/ACP* R297Q† /- 35/ACP* 2377C9T/j 18/ACP T351S/- 36/ACP 3499+37G9A/j 1/ICP F508del† /- 10/ICP* 1716G9A/j 2/ICP D443Y,G576A,R668C† /j 11/ICP* 1716G9A/j 3/ICP* D443Y,G576A,R668C† /j 12/ICP 1716G9A/j 4/ICP* P205S† /j 13/ICP* 1716G9A/j 5/ICP* L997F† /j 14/ICP* 1716G9A/j 6/ICP* R170H/1716G9A 15/ICP* 1716G9A/j 7/ICP 109A9G/j 16/ICP* 1716G9A/j 8/ICP* 5T-11TG/j 17/ICP 1716G9A/j 9/ICP* 5T-11TG/j 1/GP 5T-12TG† /j 8/GP 1716G9A/j 2/GP 5T-12TG† /j 9/GP 1716G9A/j 3/GP A534E† /j 10/GP 1716G/A/j 4/GP 5T-11TG/V562I 11/GP 1716G9A/j 5/GP 5T-11TG/j 12/GP 1716G9A/j 6/GP 5T-11TG/j 13/GP 3690A9G/j 7/GP 1716G9A/j 14/GP 3690A9G/j Corresponding mutation nomenclature (Human Genome Variation Society and Cystic Fibrosis Mutation Data Base): c.1584G9A (1716G9A), c.1210-7_1210-6delTT (5T), 1210-34_1210-13TG (11TG), g.-23A9G (109A9G), c.4242+13A9G (4374+13A9G), c.2245C9T (2377C9T), c.3367+ 37G9A (3499+37G9A), and c.3558A9G (3690A9G). Login to comment

[hide] New horizons in the treatment of cystic fibrosis. Br J Pharmacol. 2011 May;163(1):173-83. doi: 10.1111/j.1476-5381.2010.01137.x. Cuthbert AW
New horizons in the treatment of cystic fibrosis.
Br J Pharmacol. 2011 May;163(1):173-83. doi: 10.1111/j.1476-5381.2010.01137.x., [PMID:21108631]

Abstract [show]
Cystic fibrosis (CF) is a lethal, recessive, genetic disease affecting approximately 1 in 2500 live births among Caucasians. The CF gene codes for a cAMP/PKA-dependent, ATP-requiring, membrane chloride ion channel, generally found in the apical membranes of many secreting epithelia and known as CFTR (cystic fibrosis transmembrane conductance regulator). There are currently over 1700 known mutations affecting CFTR, many of which give rise to a disease phenotype. Around 75% of CF alleles contain the DeltaF508 mutation in which a triplet codon has been lost, leading to a missing phenylalanine at position 508 in the protein. This altered protein fails to be trafficked to the correct location in the cell and is generally destroyed by the proteasome. The small amount that does reach the correct location functions poorly. Clearly the cohort of patients with at least one DeltaF508 allele are a major target for therapeutic intervention. It is now over two decades since the CF gene was discovered and during this time the properties of CFTR have been intensely investigated. At long last there appears to be progress with the pharmaco-therapeutic approach. Ongoing clinical trials have produced fascinating results in which clinical benefit appears to have been achieved. To arrive at this point ingenious ways have been devised to screen very large chemical libraries for one of two properties: (i) agents promoting trafficking of mutant CFTR to, and insertion into the membrane, and known as correctors or (ii) agents which activate appropriately located mutant CFTR, known as potentiators. The best compounds emerging from these programmes are then used as chemical scaffolds to synthesize other compounds with appropriate pharmaceutical properties, hopefully with their pharmacological activity maintained or even enhanced. In summary, this approach attempts to make the mutant CFTR function in place of the real CFTR. A major function of CFTR in healthy airways is to maintain an adequate airway surface liquid (ASL) layer. In CF the position is further confounded since epithelial sodium channels (ENaC) are no longer regulated and transport salt and water out of the airways to exacerbate the lack of ASL. Thus an additional possibility for treatment of CF is to use agents that inhibit ENaC either alone or as adjuncts to CFTR correctors and/or potentiators. Yet a further way in which a pharmacological approach to CF can be considered is to recruit alternative chloride channels, such as calcium-activated chloride channel (CaCC), to act as surrogates for CFTR. A number of P2Y(2) receptor agonists have been investigated that operate by increasing Ca(2+)(i) which in turn activates CaCC. Some of these compounds are currently in clinical trials. The knowledge base surrounding the structure and function of CFTR that has accumulated in the last 20 years is impressive. Translational research feeding from this is now yielding compounds that provide real prospects for a pharmacotherapy for this disease.

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251 In one of these, VRT-325 rescued CFTR mutants R258G, S945L and H949Y as well as DF508 CFTR (Loo et al., 2005). Login to comment

[hide] Pharmacological therapy for cystic fibrosis: from ... J Cyst Fibros. 2011 Jun;10 Suppl 2:S129-45. Becq F, Mall MA, Sheppard DN, Conese M, Zegarra-Moran O
Pharmacological therapy for cystic fibrosis: from bench to bedside.
J Cyst Fibros. 2011 Jun;10 Suppl 2:S129-45., [PMID:21658632]

Abstract [show]
With knowledge of the molecular behaviour of the cystic fibrosis transmembrane conductance regulator (CFTR), its physiological role and dysfunction in cystic fibrosis (CF), therapeutic strategies are now being developed that target the root cause of CF rather than disease symptoms. Here, we review progress towards the development of rational new therapies for CF. We highlight the discovery of small molecules that rescue the cell surface expression and defective channel gating of CF mutants, termed CFTR correctors and CFTR potentiators, respectively. We draw attention to alternative approaches to restore epithelial ion transport to CF epithelia, including inhibitors of the epithelial Na(+) channel (ENaC) and activators of the Ca(2+)-activated Cl(-) channel TMEM16A. The expertise required to translate small molecules identified in the laboratory to drugs for CF patients depends on our ability to coordinate drug development at an international level and our ability to provide pertinent biological information using suitable disease models.

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100 [29] BHK cells F508del, R258G, S945L, H949Y cAMP-stimulated iodide efflux, biochemistry VRT-325 (1-10 μM) rescued F508del-CFTR and other mutants after 48 h incubation of BHK cells at 37°C. VRT-325 also rescues misprocessed P-gp mutants and acts as P-gp inhibitor. Login to comment

[hide] Validation of high-resolution DNA melting analysis... J Mol Diagn. 2008 Sep;10(5):424-34. Epub 2008 Aug 7. Audrezet MP, Dabricot A, Le Marechal C, Ferec C
Validation of high-resolution DNA melting analysis for mutation scanning of the cystic fibrosis transmembrane conductance regulator (CFTR) gene.
J Mol Diagn. 2008 Sep;10(5):424-34. Epub 2008 Aug 7., [PMID:18687795]

Abstract [show]
High-resolution melting analysis of polymerase chain reaction products for mutation scanning, which began in the early 2000s, is based on monitoring of the fluorescence released during the melting of double-stranded DNA labeled with specifically developed saturation dye, such as LC-Green. We report here the validation of this method to scan 98% of the coding sequence of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. We designed 32 pairs of primers to amplify and analyze the 27 exons of the gene. Thanks to the addition of a small GC-clamp at the 5' ends of the primers, one single melting domain and one identical annealing temperature were obtained to co-amplify all of the fragments. A total of 307 DNA samples, extracted by the salt precipitation method, carrying 221 mutations and 21 polymorphisms, plus 20 control samples free from variations (confirmed by denaturing high-performance liquid chromatography analysis), was used. With the conditions described in this study, 100% of samples that carry heterozygous mutations and 60% of those with homozygous mutations were identified. The study of a cohort of 136 idiopathic chronic pancreatitis patients enabled us to prospectively evaluate this technique. Thus, high-resolution melting analysis is a robust and sensitive single-tube technique for screening mutations in a gene and promises to become the gold standard over denaturing high-performance liquid chromatography, particularly for highly mutated genes such as CFTR, and appears suitable for use in reference diagnostic laboratories.

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51 Sequences of the Primers Used for CFTR Analysis by HRM, GC Size, Amplicon Length, Number of Positive Controls Validated for Each Exon, and Positive Controls for Routine Analysis Exon Primer Sequences GC length Amplicon length (bp) Introns Number of heterozygous- positive controls Number of homozygous- positive controls Recommended control 1 LSCFE1Fmod 5Ј-CCGCCGCCGTTGAGCGGCAGGCACC-3Ј 8 200 bp 74 4 125GϾC LSCFE1Rmod 5Ј-CCGCCGCCGGCACGTGTCTTT CCGAAGCT-3Ј 8 19 M1I 2 2i5b 5Ј-CAAATCTGTATGGAGACC-3Ј 0 194 bp 39 5 R31C 2i3Љ 5Ј-CAACTAAACAATGTACATGAAC-3Ј 0 4 296ϩ1GϾT 3 LSCFe3Fmod LSCFe3Rmod 5Ј-CGCCGTTAAGGGAAATAGGACAA CTAAAATA-3Ј 5 276 bp 44 10 2 R75Q 5Ј-CCGCCGATTCACCAGATTTCGTAGTC-3Ј 6 66 G85V 4 LSCFe4FmodC 5Ј-CCGCCGCCGCCCGTGTTGAAATT CTCAGGGT-3Ј 12 361 bp 52 14 1 R117H LSCFe4RmodC 5Ј-CCGCCGCCCACATGTACGATAC AGAATATATGTGCC-3Ј 9 26 574delA 5 LSCFE5Fmod 5Ј-CCGCCGGTTGAAATTATCTAACTTTCC-3Ј 6 201 bp 13 8 624delT LSCFE5Rmod 5Ј-CCGAACTCCGCCTTTCCAGTTGT-3Ј 3 48 711ϩ1GϾT 6a LSCF6aFmod2 5Ј-CCGCCGGGGTGGAAGAT ACAATGACACCTG-3Ј 5 317 bp 25 8 C225X LSCF6aRmod2 5Ј-CCGCCGCCGCGATGCATAGAG CAGTCCTGGTT-3Ј 11 66 L206W 6b LSCFE6bFmod 5Ј-CGCGCCGCCGGATTTAC AGAGATCAGAGAG-3Ј 10 239 bp 0 2 1 R258G LSCFE6Brmod 5Ј-CCGCCGCCGAGGTGGA GTCTACCATGA-3Ј 8 66 1001ϩ11CϾT 7 LSCFE7Fmod2 5Ј-CCGCCGCCCTCTCCCTGAATTT TATTGTTATTGTTT-3Ј 13 326 bp 7 11 1078delT LSCFE7Rmod2 5Ј-CCCGCCGCCCTATAATGCAG CATTATGGT-3Ј 10 7 1248ϩ1GϾT 8 LSCFE8Fmod 5Ј-CCGGAATGCATTAATGCTAT TCTGATTC-3Ј 4 199 bp 32 7 W401X LSCFE8Rmod 5Ј-CCCGCAGTTAGGTGTTTAG AGCAAACAA-3Ј 4 18 1249-5AϾG 9 LSCFe9Fmod2 5Ј-CCGCCGCCGGGAATTATTTGAGAA AGCAAAACA-3Ј 8 279 bp 0 3 D443Y LSCFe9Rmod2 5Ј-CCGCCGCGAAAATACCTTCCAG CACTACAAACTAGAAA-3Ј 8 57 A455E 10 LSCF10FmodD 5Ј-CGCCGTTATGGGAGAACTGG AGCCTTCAGAG-3Ј 5 275 bp 0 15 1 F508del LSCF10RmodD 5Ј-CCGCAGACTAACCGATTGAAT ATGGAGCC-3Ј 4 68 E528E 11 h11i5 5Ј-TGCCTTTCAAATTCAGATTGAGC-3Ј 0 197 bp 42 13 2 G542X 11i3ter 5Ј-ACAGCAAATGCTTGCTAGACC-3Ј 0 17 G551D 12 LSCFE12Fmod 5Ј-CGCGTCATCTACACTAGATGACCAG-3Ј 4 244 bp 43 15 G576A 1898 ϩ 1GϾALSCFE12Rmod 5Ј-CCGGAGGTAAAATGCAATCTATGATG-3Ј 3 63 13 LSCF13AFmod 5Ј-CCGCCGCCGGAGACATATTG CAATAAAGTAT-3Ј 9 38 20 I601F LSCF13ARmod 5Ј-GCCTGTCCAGGAGACAGGA GCATCTC-3Ј 2 R668C LSCF13BFmod 5Ј-CCGCCGCAATCCTAACTGAG ACCTTACACCG-3Ј 2 R668C LSCF13BRmod 5Ј-CCGCCGATCAGGTTCAGGA CAGACTGC-3Ј 3 346 bp 2184insA LSCF13CFmod 5Ј-CCGCGGTGATCAGCACTGGCCC-3Ј 6 301 bp 77 L749L LSCF13CRmod 5Ј-CCGCGCGCGCGGCCAGTTTCTTG AGATAACCTTCT-3Ј 13 259 bp V754M LSCF13DFmod 5Ј-CGTGTCACTGGCCCCTCAGGC-3Ј 1 221 bp I807M LSCF13DRmof 5Ј-CCGCCGCCGCTAATCCTATGA TTTTAGTAAAT-3Ј 9 220 bp 2622ϩ1GϾA LSCf13FFmod 5Ј-CGCGGTGCAGAAAGAAGAAAT TCAATCCTAACTG-3Ј 4 R668C LSCF13FRmod 5Ј-CCGCCGTGCCATTCATTTGT AAGGGAGTCT-3Ј 6 2184insA 14a LSCF14aFmodB 5Ј-CCGACCACAATGGTGGCAT GAAACTG-3Ј 3 239 bp 35 7 1 T854T LSCF14aRmodB 5Ј-CCGCCGACTTTAAATCCAGTAAT ACTTTACAATAGAACA-3Ј 6 7 W846X 14b LSCF14bFmod 5Ј-CCGGAGGAATAGGTGAAGAT-3Ј 2 179 bp 38 4 2752-5GϾT LSCF14bRmodb 5Ј-CCGTACATACAAACATAGTGGATT-3Ј 3 59 2789ϩ5GϾT 15 LSCFE15Fmod 5Ј-CGCGCCGTGTATTGGAAA TTCAGTAAGTAACTTTGG-3Ј 7 412 bp 33 16 T908S LSCFE15Rmod 5Ј-CCGCAGCCAGCACTGCCAT TAGAAA-3Ј 4 68 S945L (table continues) phisms that we have chosen to exclude. Login to comment

[hide] Disease-associated mutations in cytoplasmic loops ... Biochemistry. 1997 Sep 30;36(39):11966-74. Seibert FS, Jia Y, Mathews CJ, Hanrahan JW, Riordan JR, Loo TW, Clarke DM
Disease-associated mutations in cytoplasmic loops 1 and 2 of cystic fibrosis transmembrane conductance regulator impede processing or opening of the channel.
Biochemistry. 1997 Sep 30;36(39):11966-74., [PMID:9305991]

Abstract [show]
Since little is known about the contribution to function of the N-terminal cytoplasmic loops (CL1, residues 139-194; CL2, residues 242-307) of cystic fibrosis transmembrane conductance regulator (CFTR), all nine point mutations identified in CLs 1 and 2 from patients with cystic fibrosis were reconstructed in the expression vector pcDNA3-CFTR and expressed transiently in COS-1 and HEK-293 cells and stably in Chinese hamster ovary (CHO) cells. Four amino acid substitutions retarded production of mature, fully glycosylated CFTR, suggesting that misprocessing of the channel causes the disease symptoms in the affected patients. Protein maturation could not be promoted by cell culture conditions of reduced temperature (26 degrees C). When properly processed mutants were evaluated for functional defects by the iodide efflux method, the G178R- and E193K-CFTR-expressing cell lines showed impaired anion translocation activities. Patch-clamp studies of single channels revealed that E193K variants had a significantly decreased open probability, which resulted from an increase in the mean closed time of the channels. This contrasted with a previous study of disease-associated point mutations in CL3 that mainly affected the mean open time. None of the maturation-competent CL 1 and 2 mutants had altered conductance. Thus, the N-terminal CLs appear not to contribute to the anion translocation pathway of CFTR; rather, mutations in CL1 can impede transition to the open state. Interestingly, the ability of the non-hydrolyzable ATP analogue adenylyl imidodiphosphate (AMP-PNP) to lock the channel into open bursts was abolished by the I148T and G178R amino acid substitutions.

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107 The remaining amino acid substitutions significantly decreased the yield of band C, with relative amounts of "vector only" (background) < G149R-CFTR < H139R-CFTR < R258G-CFTR < D192G-CFTR , wild-type CFTR (Figure 2, bottom). Login to comment
120 In accordance with reduced levels of processing, the H139R, G149R, D192G, and R258G mutations significantly decreased the anion translocation capability of CFTR, whereas the properly processed I148T, I175V, and R297Q variants allowed iodide movement comparable to that of wild type. Login to comment
153 When reconstructed in heterologous expression systems, four of the amino acid substitutions (H139R, G149R, D192G, and R258G) inhibited maturation and transport of CFTR to the cell surface, so that the protein cannot carry out its regular functions at that location. Login to comment

[hide] Mutations in the cystic fibrosis gene in patients ... N Engl J Med. 1995 Jun 1;332(22):1475-80. Chillon M, Casals T, Mercier B, Bassas L, Lissens W, Silber S, Romey MC, Ruiz-Romero J, Verlingue C, Claustres M, et al.
Mutations in the cystic fibrosis gene in patients with congenital absence of the vas deferens.
N Engl J Med. 1995 Jun 1;332(22):1475-80., [PMID:7739684]

Abstract [show]
BACKGROUND: Congenital bilateral absence of the vas deferens (CBAVD) is a form of male infertility in which mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene have been identified. The molecular basis of CBAVD is not completely understood. Although patients with cystic fibrosis have mutations in both copies of the CFTR gene, most patients with CBAVD have mutations in only one copy of the gene. METHODS: To investigate CBAVD at the molecular level, we have characterized the mutations in the CFTR gene in 102 patients with this condition. None had clinical manifestations of cystic fibrosis. We also analyzed a DNA variant (the 5T allele) in a noncoding region of CFTR that causes reduced levels of the normal CFTR protein. Parents of patients with cystic fibrosis, patients with types of infertility other than CBAVD, and normal subjects were studied as controls. RESULTS: Nineteen of the 102 patients with CBAVD had mutations in both copies of the CFTR gene, and none of them had the 5T allele. Fifty-four patients had a mutation in one copy of CFTR, and 34 of them (63 percent) had the 5T allele in the other CFTR gene. In 29 patients no CFTR mutations were found, but 7 of them (24 percent) had the 5T allele. In contrast, the frequency of this allele in the general population was about 5 percent. CONCLUSIONS: Most patients with CBAVD have mutations in the CFTR gene. The combination of the 5T allele in one copy of the CFTR gene with a cystic fibrosis mutation in the other copy is the most common cause of CBAVD: The 5T allele mutation has a wide range of clinical presentations, occurring in patients with CBAVD or moderate forms of cystic fibrosis and in fertile men.

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74 OF PATIENTS POLYT GENOTYPE† ⌬F508/R668C ⌬F508/D1152H ⌬F508/D1270N ⌬F508/R75L ⌬F508/R117H ⌬F508/L206W ⌬F508/R258G ⌬F508/S1235R ⌬F508/R347H ⌬F508/R347H R117H/G1349D R117H/712-1G→T G149R/R668C R347H/R1066H R553X/R668C R1070W/2869insG ⌬F508/- G542X/- W1282X/- R334W/- K1060T/- R1162X/- N1303K/- A800G/- ⌬F508/- ⌬F508/- ⌬F508/- ⌬E115/- R117H/- R347H/- G542X/- R553X/- 1677delTA/- 2184delA/- 2789ϩ5G→Α/- S1235R/- W1282X/- -/- -/- -/- -/- 2 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 22 4 3 1 1 1 1 1 7 1 1 1 1 2 1 1 1 1 1 1 1 3 3 1 19 9T/7T 9T/7T 9T/7T 9T/7T 9T/7T 9T/9T 9T/7T 9T/7T 9T/7T 9T/9T 7T/7T 7T/9T 9T/7T 9T/7T 7T/7T 7T/7T 9T/5T 9T/5T 7T/5T 7T/5T 7T/5T 7T/5T 9T/5T 5T/5T 9T/7T 9T/9T 7T/7T 7T/7T 7T/7T 9T/7T 9T/7T 7T/7T 7T/7T 7T/7T 7T/7T 7T/9T 7T/7T 9T/5T 7T/5T 5T/5T 7T/7T -/- 3 7T/9T *Data were obtained from the Spanish population analyzed in this study. Login to comment

[hide] Is congenital bilateral absence of vas deferens a ... Am J Hum Genet. 1995 Jan;56(1):272-7. Mercier B, Verlingue C, Lissens W, Silber SJ, Novelli G, Bonduelle M, Audrezet MP, Ferec C
Is congenital bilateral absence of vas deferens a primary form of cystic fibrosis? Analyses of the CFTR gene in 67 patients.
Am J Hum Genet. 1995 Jan;56(1):272-7., [PMID:7529962]

Abstract [show]
Congenital bilateral absence of the vas deferens (CBAVD) is an important cause of sterility in men. Although the genetic basis of this condition is still unclear, it has been shown recently that some of these patients carry mutations in their cystic fibrosis transmembrane conductance regulator (CFTR) genes. To extend this observation, we have analyzed the entire coding sequence of the CFTR gene in a cohort of 67 men with CBAVD, who are otherwise healthy. We have identified four novel missense mutations (A800G, G149R, R258G, and E193K). We have shown that 42% of subjects were carriers of one CFTR allele and that 24% are compound heterozygous for CFTR alleles. Thus, we have been unable to identify 76% of these patients as carrying two CFTR mutations. Furthermore, we have described the segregation of CFTR haplotypes in the family of one CBAVD male; in this family are two male siblings, with identical CFTR loci but displaying different phenotypes, one of them being fertile and the other sterile. The data presented in this family, indicating a discordance between the CBAVD phenotype and a marked carrier (delta F508) chromosome, support the involvement of another gene(s), in the etiology of CBAVD.

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7 We have identified four novel missense mutations (A800G, G149R, R258G, and E193K). Login to comment
65 In addition, we identified the following missense mutations: four R668C, one A800G, one (G628R + S1235R, borne on the same chromosome), one (R74W + D1270N, borne on the same chromosome), six R117H, one F1052V, one R117C, one S1235R, one G149R, one R258G, two R347H, one R1066H, one R75L, and one E193K. Login to comment
77 of Patients Genotypea 1 AF508 + (G628R + S1235R) 1 AF508 + (R74W + D1270N) 2 AF508 + R668C 4 AF508 + R117H 1 AF508 + R258G 1 AF508 + R75L 1 E193K + N1303K 1 R347H + R1066H 1 R117C + W1282X 1 R553X + R668C 1 G149R + R668C 1 R117H+R117H 18 AF508/unidentified 4 W1282X/unidentified 1 G542X/unidentified 1 N1303K/unidentified 1 S1235R/unidentified 1 R347H/unidentified 1 A800G/unidentified 1 F1052V/unidentified 23 unidentified/unidentified a In parentheses are the two mutations located on the same haplotype. Login to comment
87 (iii) The third novel mutation we found is R258G, and the nucleotide change is G-A at position 904 in exon 6b. It corresponds to the substitution of an arginine for a glycine (R258G) This mutation is situated in a region that encodes part of the transmembrane region of the protein, and the mutation results in a change of polarity at codon 258. Login to comment
92 For all four of these new mutations, a segregation analysis was performed in each family, allowing us to show that G149R, R258G, and E193K were carried by a particular allele and that these mutations were not de novo mutations. Login to comment

[hide] Correctors of DeltaF508 CFTR restore global confor... FASEB J. 2013 Feb;27(2):536-45. doi: 10.1096/fj.12-216119. Epub 2012 Oct 26. He L, Kota P, Aleksandrov AA, Cui L, Jensen T, Dokholyan NV, Riordan JR
Correctors of DeltaF508 CFTR restore global conformational maturation without thermally stabilizing the mutant protein.
FASEB J. 2013 Feb;27(2):536-45. doi: 10.1096/fj.12-216119. Epub 2012 Oct 26., [PMID:23104983]

Abstract [show]
Most cystic fibrosis is caused by the deletion of a single amino acid (F508) from CFTR and the resulting misfolding and destabilization of the protein. Compounds identified by high-throughput screening to improve DeltaF508 CFTR maturation have already entered clinical trials, and it is important to understand their mechanisms of action to further improve their efficacy. Here, we showed that several of these compounds, including the investigational drug VX-809, caused a much greater increase (5- to 10-fold) in maturation at 27 than at 37 degrees C (<2-fold), and the mature product remained short-lived (T(1/2) approximately 4.5 h) and thermally unstable, even though its overall conformational state was similar to wild type, as judged by resistance to proteolysis and interdomain cross-linking. Consistent with its inability to restore thermodynamic stability, VX-809 stimulated maturation 2-5-fold beyond that caused by several different stabilizing modifications of NBD1 and the NBD1/CL4 interface. The compound also promoted maturation of several disease-associated processing mutants on the CL4 side of this interface. Although these effects may reflect an interaction of VX-809 with this interface, an interpretation supported by computational docking, it also rescued maturation of mutants in other cytoplasmic loops, either by allosteric effects or via additional sites of action. In addition to revealing the capabilities and some of the limitations of this important investigational drug, these findings clearly demonstrate that DeltaF508 CFTR can be completely assembled and evade cellular quality control systems, while remaining thermodynamically unstable. He, L., Kota, P., Aleksandrov, A. A., Cui, L., Jensen, T., Dokholyan, N. V., Riordan, J. R. Correctors of DeltaF508 CFTR restore global conformational maturation without thermally stabilizing the mutant protein.

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181 B, C) HEK293 cells were transiently transfected with CFTR with misprocessing mutations located in CL1 (H139R), CL2 (R258G), and CL3 (S945L) (B), or in NBD1 (èc;I507 and R560T; C). Login to comment

[hide] Enhancing the Potency of F508del Correction: A Mul... J Pharmacol Clin Toxicol. 2013 Aug 28;1(1):1007. Kirby EF, Heard AS, Wang XR
Enhancing the Potency of F508del Correction: A Multi-Layer Combinational Approach to Drug Discovery for Cystic Fibrosis.
J Pharmacol Clin Toxicol. 2013 Aug 28;1(1):1007., [PMID:24855632]

Abstract [show]
With better understanding of the cellular and molecular pathophysiology underlying cystic fibrosis (CF), novel drugs are being developed that specifically target the molecular defects of the cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-activated chloride channel on the plasma membrane that causes CF. Starting with cell-based high-throughput screening, small molecules have been identified that are able to fix specific molecular defects of various disease-causing CFTR mutants. With the successful development of ivacaftor, a "potentiator" that enhances CFTR chloride channel activity, new types of small-molecule compounds that "correct" the misfolding and misprocessing of the most common CF-causing mutation, F508del, are actively being sought for. Recent studies focused on the potential mechanisms of action of some of the investigational CFTR "correctors" shed new light on how the F508del mutant can be targeted in an attempt to ameliorate the clinical symptoms associated with CF. A multi-layer combinational approach has been proposed to achieve the high-potency correction necessary for significant clinical outcome. The mechanistic insights obtained from such studies will shape the future therapeutics development for the vast majority of CF patients.

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64 VRT-325 was found to rescue not only F508del CFTR but also other CFTR processing mutants such as R258G, S945L, and H949Y, and processing mutants of P-glycoprotein (P-gp), a drug pump that also belongs to the ABC transporter family [29]. Login to comment

[hide] Mechanisms of CFTR functional variants that impair... PLoS Genet. 2014 Jul 17;10(7):e1004376. doi: 10.1371/journal.pgen.1004376. eCollection 2014 Jul. LaRusch J, Jung J, General IJ, Lewis MD, Park HW, Brand RE, Gelrud A, Anderson MA, Banks PA, Conwell D, Lawrence C, Romagnuolo J, Baillie J, Alkaade S, Cote G, Gardner TB, Amann ST, Slivka A, Sandhu B, Aloe A, Kienholz ML, Yadav D, Barmada MM, Bahar I, Lee MG, Whitcomb DC
Mechanisms of CFTR functional variants that impair regulated bicarbonate permeation and increase risk for pancreatitis but not for cystic fibrosis.
PLoS Genet. 2014 Jul 17;10(7):e1004376. doi: 10.1371/journal.pgen.1004376. eCollection 2014 Jul., [PMID:25033378]

Abstract [show]
CFTR is a dynamically regulated anion channel. Intracellular WNK1-SPAK activation causes CFTR to change permeability and conductance characteristics from a chloride-preferring to bicarbonate-preferring channel through unknown mechanisms. Two severe CFTR mutations (CFTRsev) cause complete loss of CFTR function and result in cystic fibrosis (CF), a severe genetic disorder affecting sweat glands, nasal sinuses, lungs, pancreas, liver, intestines, and male reproductive system. We hypothesize that those CFTR mutations that disrupt the WNK1-SPAK activation mechanisms cause a selective, bicarbonate defect in channel function (CFTRBD) affecting organs that utilize CFTR for bicarbonate secretion (e.g. the pancreas, nasal sinus, vas deferens) but do not cause typical CF. To understand the structural and functional requirements of the CFTR bicarbonate-preferring channel, we (a) screened 984 well-phenotyped pancreatitis cases for candidate CFTRBD mutations from among 81 previously described CFTR variants; (b) conducted electrophysiology studies on clones of variants found in pancreatitis but not CF; (c) computationally constructed a new, complete structural model of CFTR for molecular dynamics simulation of wild-type and mutant variants; and (d) tested the newly defined CFTRBD variants for disease in non-pancreas organs utilizing CFTR for bicarbonate secretion. Nine variants (CFTR R74Q, R75Q, R117H, R170H, L967S, L997F, D1152H, S1235R, and D1270N) not associated with typical CF were associated with pancreatitis (OR 1.5, p = 0.002). Clones expressed in HEK 293T cells had normal chloride but not bicarbonate permeability and conductance with WNK1-SPAK activation. Molecular dynamics simulations suggest physical restriction of the CFTR channel and altered dynamic channel regulation. Comparing pancreatitis patients and controls, CFTRBD increased risk for rhinosinusitis (OR 2.3, p<0.005) and male infertility (OR 395, p<<0.0001). WNK1-SPAK pathway-activated increases in CFTR bicarbonate permeability are altered by CFTRBD variants through multiple mechanisms. CFTRBD variants are associated with clinically significant disorders of the pancreas, sinuses, and male reproductive system.

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116 CFTR variant %Cases %Uctrls OR p-value %Cases w/N34S OR w/N34S p-value w/N34S F508C 0.5 0.3 1.58 0.21 0.0 0.00 0.67 R1162L 0.5 0.5 1.13 0.29 1.8 4.03 0.17 I1027T 0.5 0.3 1.99 0.17 0.0 0.00 0.70 R31C 0.3 0.7 0.42 0.088 0.0 0.00 0.52 I148T 0.3 0.4 0.75 0.27 0.0 0.00 0.63 R297Q 0.3 0.2 1.89 0.21 0.0 0.00 0.76 R74W 0.2 0.2 0.85 0.29 0.0 0.00 0.71 F1052V 0.1 0.2 0.63 0.27 0.0 0.00 0.76 I807M 0.1 0.1 1.26 0.30 0.0 0.00 0.83 R258G 0.1 0.1 1.26 0.30 0.0 0.00 0.83 G1069R 0.1 0.0 0.13 0.0 V201M 0.0 0.1 0.17 0.0 0.00 0.83 Of the 81 CFTR mutations tested in the cohort, 43 were observed at least once in cases or controls. Login to comment
269 67 SNPs (125GtoC, 1716G.A, 1717-1G.A, 1898+1G.A, 2183AA.G, 2184delA, 2789+5G.A, 3120+1G.A, 3659delC, 3849+10kbC.T, 621+ 1G.T, 711+5G.A, A455E, D110H, D1152H, D1270N, D443Y, D579G, F1052V, F1074L, F508C, F508del, G1069R, G1244E, G1349D, G178R, G542X, G551D, G551S, I1131L/V, I148T, I336K/T, I507del, I807M, IVS8T5, K1180T, L1065P, L967S, L997F, M1V, M470V, M952I, M952T, N1303K, P67L, Q1463Q, R1070Q, R1162X, R117C, R117H, R170H, R258G, R297Q, R31C, R352Q, R553X, R668C, R74W, R75Q, S1235R, S1255P, S485R, S977F, T338I, T854T, V201M, W1282X) were multiplexed into 6 wells; 14 SNPs (S492F, S945L, R74Q, R560T, R1162L, G85E, I1027T, R334W, R347P, G576A, 711+1G.T, 1001+11C.T, P1290P, 3199del6) were ascertained separately via TaqMan Gene Expression Assays, with repeat confirmation of all positive results. Login to comment