ABCMdb

ABCC7 p.Gly314Glu

ClinVar:	c.940G>C , p.Gly314Arg ? , not provided c.941G>T , p.Gly314Val ? , not provided c.941G>A , p.Gly314Glu ? , not provided
CF databases:	c.941G>T , p.Gly314Val (CFTR1) D , This mutation was found in a CF patient homozygous for this mutation. He was diagnosed as CF at 32 years. c.940G>C , p.Gly314Arg (CFTR1) D , This mutation was detected by chemical mismatch and sequencing. The mutation is a G to C change at nucleotide 1072. This results in a glycine to arginine substitution at amino acid 314 (G314R). It is in exon 7 and it eliminates a DdeI restriction site. This mutation was found in a patient with an American Indian/Caucasian mother and Dutch/French father. This patient has a [delta]F508 mutation on the other chromosomes and is pancreatic insufficient. This mutation was not found in 25 normal chromosomes and 25 CF chromosomes. c.941G>A , p.Gly314Glu (CFTR1) ? , This mutation, in exon 7 of the CFTR gene, was found by direct sequencing and the second mutation is [delta]F508. The patient is 7 years old. Diagnosis of CF was established at the age of five after severe lung infection. Sweat gland tests were positive. She is receiveing pancreatic enzyme supplements and long-term antibiotic treatment.
Predicted by SNAP2:	A: D (85%), C: D (91%), D: D (95%), E: D (66%), F: D (95%), H: D (95%), I: D (95%), K: D (95%), L: D (95%), M: D (95%), N: D (91%), P: D (95%), Q: D (95%), R: D (71%), S: D (80%), T: D (91%), V: D (95%), W: D (95%), Y: D (95%),
Predicted by PROVEAN:	A: N, C: N, D: N, E: N, F: N, H: N, I: N, K: N, L: N, M: N, N: N, P: N, Q: N, R: N, S: N, T: N, V: N, W: N, Y: N,

[switch to compact view]
Comments [show]

None has been submitted yet.

Publications
[hide] Novel pharmacologic therapies for cystic fibrosis. J Clin Invest. 1999 Feb;103(4):447-52. Zeitlin PL
Novel pharmacologic therapies for cystic fibrosis.
J Clin Invest. 1999 Feb;103(4):447-52., [PMID:10021451]

Abstract [show]

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
128 Class IV mutants such as R117H, G314E, R334W, and R347P are associated with normal PKA-dependent phosphorylation and ATP binding. Login to comment

[hide] Cystic fibrosis transmembrane conductance regulato... J Gen Physiol. 1999 Dec;114(6):799-818. Smith SS, Steinle ED, Meyerhoff ME, Dawson DC
Cystic fibrosis transmembrane conductance regulator. Physical basis for lyotropic anion selectivity patterns.
J Gen Physiol. 1999 Dec;114(6):799-818., [PMID:10578016]

Abstract [show]
The cystic fibrosis transmembrane conductance regulator (CFTR) Cl channel exhibits lyotropic anion selectivity. Anions that are more readily dehydrated than Cl exhibit permeability ratios (P(S)/P(Cl)) greater than unity and also bind more tightly in the channel. We compared the selectivity of CFTR to that of a synthetic anion-selective membrane [poly(vinyl chloride)-tridodecylmethylammonium chloride; PVC-TDMAC] for which the nature of the physical process that governs the anion-selective response is more readily apparent. The permeability and binding selectivity patterns of CFTR differed only by a multiplicative constant from that of the PVC-TDMAC membrane; and a continuum electrostatic model suggested that both patterns could be understood in terms of the differences in the relative stabilization of anions by water and the polarizable interior of the channel or synthetic membrane. The calculated energies of anion-channel interaction, derived from measurements of either permeability or binding, varied as a linear function of inverse ionic radius (1/r), as expected from a Born-type model of ion charging in a medium characterized by an effective dielectric constant of 19. The model predicts that large anions, like SCN, although they experience weaker interactions (relative to Cl) with water and also with the channel, are more permeant than Cl because anion-water energy is a steeper function of 1/r than is the anion-channel energy. These large anions also bind more tightly for the same reason: the reduced energy of hydration allows the net transfer energy (the well depth) to be more negative. This simple selectivity mechanism that governs permeability and binding acts to optimize the function of CFTR as a Cl filter. Anions that are smaller (more difficult to dehydrate) than Cl are energetically retarded from entering the channel, while the larger (more readily dehydrated) anions are retarded in their passage by "sticking" within the channel.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
290 In the case of CFTR, it is possible to envision two sorts of CFTR pores: those that bind anions, exemplified by the wild-type channel, and those that do not, exemplified by mutant CFTRs like G314E or Q (Mansoura et al., 1998) and R347D (Tabcharani et al., 1993). Login to comment
288 In the case of CFTR, it is possible to envision two sorts of CFTR pores: those that bind anions, exemplified by the wild-type channel, and those that do not, exemplified by mutant CFTRs like G314E or Q (Mansoura et al., 1998) and R347D (Tabcharani et al., 1993). Login to comment

[hide] Pharmacologic restoration of delta F508 CFTR-media... Kidney Int. 2000 Mar;57(3):832-7. Zeitlin PL
Pharmacologic restoration of delta F508 CFTR-mediated chloride current.
Kidney Int. 2000 Mar;57(3):832-7., [PMID:10720936]

Abstract [show]
Cystic fibrosis (CF) is an autosomal inherited disorder caused by over 800 different mutations in the CFTR gene. The most common mutation, delta F508, causes a trafficking arrest in the endoplasmic reticulum and the CFTR protein is degraded. Restoration of CFTR trafficking in vitro restores cAMP-mediated chloride transport at the cell surface. The hypothesis of this discussion is that the short chain fatty acids, butyrate and 4-phenylbutyrate, up-regulate mature CFTR at the plasma membrane. Evidence that these compounds regulate CFTR production and maturation in part through effects on molecular chaperones in CF cells in culture is discussed. The oral drug, 4-phenylbutyrate, was tested in a Phase I clinical trial in CF subjects and further trials are underway. Other new therapeutic approaches directed at different classes of mutations in CFTR are also discussed. Chemical and pharmacologic agents that regulate endogenous gene expression at different steps in the biosynthetic processing pathway of a membrane glycoprotein will be needed to comprehensively treat a complex inherited disorder like cystic fibrosis.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
101 CF nasal epithelia alone or in combination with isoproterenol demonstrated a modest hyperpolarization in the CLASS IV CONDUCTION MUTATIONS AREnasal potential difference response to low chloride in ASSOCIATED WITH A MILD PHENOTYPEnormal volunteers, but not in CF patients homozygous Class IV mutants such as R117H, G314E, R334 W, andfor ⌬F508. Login to comment

[hide] Future pharmacological treatment of cystic fibrosi... Respiration. 2000;67(4):351-7. Zeitlin PL
Future pharmacological treatment of cystic fibrosis.
Respiration. 2000;67(4):351-7., [PMID:10940786]

Abstract [show]
Cystic fibrosis (CF) is an autosomal recessive disorder that is caused by over 850 different mutations in the CF gene. It is useful to group these mutations according to the defect that results in the CFTR mRNA or protein. New pharmacological treatments targeted towards specific mutations that are relatively common are being developed. Class I mutations do not produce CFTR protein because of a premature stop signal in the CFTR DNA. These null mutations can be corrected by certain aminoglycosides which cause the aberrant stop signal to be skipped. Mutations leading to a CFTR protein that attains an unstable structure shortly after translation in the endoplasmic reticulum form class II. Class II mutations can be restored to the protein trafficking pathway by manipulation of chaperone protein/CFTR interactions with chemical chaperones or drugs that affect gene regulation such as the butyrates. Production of a CFTR with reduced Cl(-) transport on the basis of abnormal regulation of the chloride channel is the basis of class III. Genistein can overcome this block in regulation. Mutations that partially reduce chloride conductance through CFTR (class IV) can be stimulated with milrinone, which is a phosphodiesterase inhibitor. Finally, mutations that lead to a severe reduction in normal CFTR protein form class V. Increased levels of CFTR could be generated with the butyrates or supplemented with gene therapy. Although most of the reported mutations in CFTR are rare and unclassified, it may be possible to use genotype-phenotype correlations to determine the best approach.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
22 Examples of CFTR mutations organized by classification of the defect in CFTR biosynthesis Type Genotype Phenotype Defect Cell diagram Drugs that may improve phenotype G542X 621+1 G → T 3905insT W1282X R553X 1717-1 G → A PI no CFTR protein no cell surface chloride transport gentamicin G418 Class II [64] 'F508 N1303K (P574H)a (A455E)a PI defective CFTR processing defective CFTR trafficking no cell surface chloride transport chemical chaperones CPX phenylbutyrate deoxyspergualin Class III [64] G551D G551S PI defective chloride channel regulation reduced or absent cell surface chloride transport genistein pyrophosphate Class IV [64, 66] R117H R334W G314E R347P ('F508)a P574H PS reduced chloride conductance reduced levels of cell surface chloride transport genistein milrinone phenylbutyrate Class V [64] 3849+10 kb C → T 2789+5 G → A 3272-26 A → G A455E 3120+1 G → A 1811+1.6 kb A → G 5Tb PS normal CFTR channels reduced numbers of normal CFTR reduced cell surface chloride transport genistein milrinone phenylbutyrate a Some mutants have features of more than one class of defect. Login to comment

[hide] Type I, II, III, IV, and V cystic fibrosis transme... Curr Opin Pulm Med. 2000 Nov;6(6):521-9. Choo-Kang LR, Zeitlin PL
Type I, II, III, IV, and V cystic fibrosis transmembrane conductance regulator defects and opportunities for therapy.
Curr Opin Pulm Med. 2000 Nov;6(6):521-9., [PMID:11100963]

Abstract [show]
Recent advances in cellular and molecular biology have furthered the understanding of several genetic diseases, including cystic fibrosis. Mutations that cause cystic fibrosis are now understood in terms of the specific molecular consequences to the cystic fibrosis transmembrane conductance regulator (CFTR) protein expression and function. This knowledge has spawned interest in the development of therapies aimed directly at correcting the defective CFTR itself. In this article, we review the molecular defect underlying each recognized class of CFTR mutation and the potential therapies currently under investigation. Opportunities for protein-repair therapy appear to be vast and range from naturally occurring compounds, such as isoflavonoids, to pharmaceuticals already in clinical use, including aminoglycoside antibiotics, butyrate analogues, phosphodiesterase inhibitors, and adenosine nucleotides. Future therapies may resemble designer compounds like benzo[c]quinoliziniums or take the form of small peptide replacements. Given the heterogeneity and progressive nature of cystic fibrosis, however, optimal benefit from protein-repair therapy will most likely require the initiation of combined therapies early in the course of disease to avoid irreparable organ damage.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
106 These CFTR mutants including R117H, G314E, R334W, and R347P demonstrate a reduction in their chloride conductance or abnormal channel gating (see Fig. 2). Login to comment

[hide] Relationship between anion binding and anion perme... J Physiol. 2001 Feb 15;531(Pt 1):51-66. Linsdell P
Relationship between anion binding and anion permeability revealed by mutagenesis within the cystic fibrosis transmembrane conductance regulator chloride channel pore.
J Physiol. 2001 Feb 15;531(Pt 1):51-66., 2001-02-15 [PMID:11179391]

Abstract [show]
1. Anion binding within the pores of wild-type and mutant cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channels, expressed in two different mammalian cell lines, was assayed using patch clamp recording. Specifically, experiments measured both the conductance of different anions and the ability of other permeant anions to block Cl- permeation through the pore. 2. Under symmetrical ionic conditions, wild-type CFTR channels showed the conductance sequence Cl- > NO3- > Br- > or = formate > F- > SCN- congruent to ClO4-. 3. High SCN- conductance was not observed, nor was there an anomalous mole fraction effect of SCN- on conductance under the conditions used. Iodide currents could not be measured under symmetrical ionic conditions, but under bi-ionic conditions I- conductance appeared low. 4. Chloride currents through CFTR channels were blocked by low concentrations (10 mM) of SCN-, I- and ClO4-, implying relatively tight binding of these anions within the pore. 5. Two mutations in CFTR which alter the anion permeability sequence, F337S and T338A, also altered the anion conductance sequence. Furthermore, block by SCN-, I- and ClO4- were weakened in both mutants. Both these effects are consistent with altered anion binding within the pore. 6. The effects of mutations on anion permeability and relative anion conductance suggested that, for most anions, increased permeability was associated with increased conductance. This indicates that the CFTR channel pore does not achieve its anion selectivity by selective anion binding within the mutated region. Instead, it is suggested that entry of anions into the region around F337 and T338 facilitates their passage through the pore. In wild-type CFTR channels, anion entry into this crucial pore region is probably dominated by anion hydration energies.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
34 The hypothesis that anion permeability and anion binding are separable facets of the permeation process in the CFTR Cl¦ channel is supported by the fact that several mutations within the pore have been shown to alter anion binding without strongly affecting anion permeability (e.g. K335E, Anderson et al. 1991; R347D, Tabcharani et al. 1993; G314E, Mansoura et al. 1998). Login to comment
200 Several mutations within the pore of CFTR alter permeant anion binding without strongly affecting anion selectivity (in terms of permeability ratios) (e.g. K335E, Anderson et al. 1991; G314E, Mansoura et al. 1998), suggesting that these mutations affect anion binding sites not intimately involved in the anion selectivity process (Smith et al. 1999; Linsdell et al. 2000). Login to comment

[hide] Voltage-sensitive gating induced by a mutation in ... Am J Physiol Lung Cell Mol Physiol. 2002 Jan;282(1):L135-45. Zhang ZR, Zeltwanger S, Smith SS, Dawson DC, McCarty NA
Voltage-sensitive gating induced by a mutation in the fifth transmembrane domain of CFTR.
Am J Physiol Lung Cell Mol Physiol. 2002 Jan;282(1):L135-45., [PMID:11741825]

Abstract [show]
A mutation in the fifth transmembrane domain of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel (V317E) resulted in whole cell currents that exhibited marked outward rectification on expression in Xenopus oocytes. However, the single-channel unitary current (i)-voltage (V) relationship failed to account for the rectification of whole cell currents. In excised patches containing one to a few channels, the time-averaged single-channel current (I)-V relationship (I = N x P(o) x i, where N is the number of active channels and P(o) is open probability) of V317E CFTR displayed outward rectification, whereas that of wild-type CFTR was linear, indicating that the P(o) of V317E CFTR is voltage dependent. The decrease in P(o) at negative potentials was due to both a decreased burst duration and a decreased opening rate that could not be ameliorated by a 10-fold increase in ATP concentration. This behavior appears to reflect a true voltage dependence of the gating process because the P(o)-V relationship did not depend on the direction of Cl(-) movement. The results are consistent with the introduction, by a point mutation, of a novel voltage-dependent gating mode that may provide a useful tool for probing the portions of the protein that move in response to ATP-dependent gating.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
314 Other glutamate substitutions in TM domains 1, 5, 6, and 12 have been investigated [G91E, G314E, and K335E (16); S341E and T1134E (20)], but none of these exhibited voltage-dependent gating (McCarty and Dawson, unpublished observations). Login to comment

[hide] Towards the pharmacogenomics of cystic fibrosis. Pharmacogenomics. 2002 Jan;3(1):75-87. Sangiuolo F, D'Apice MR, Bruscia E, Lucidi V, Novelli G
Towards the pharmacogenomics of cystic fibrosis.
Pharmacogenomics. 2002 Jan;3(1):75-87., [PMID:11966405]

Abstract [show]
Cystic fibrosis (CF) is the most common lethal recessive genetic disease affecting children in Europe and the US. CF is a multiorgan disease and may present a variety of clinical symptoms, like chronic obstructive lung disease, exocrine pancreatic insufficiency (PI) and elevated sweat chloride concentration. CF mutations have also been found in other related clinical diseases such as congenital bilateral absence of the vas deferens (CBAVD), disseminated bronchiectasis and chronic pancreatitis. These clinical overlaps pose etiopathogenetic, diagnostic and therapeutic questions. Despite stunning advances in genomic technologies and drug discovery, drug therapy often improves disease symptoms but does not cure the disease. One of the main causes of this failure in CF cure may be attributable to genetic variability and to the scarce knowledge of CF biochemistry. Therefore, knowing the genotype of a patient might help improve drug efficacy, reduce toxicity and suggests innovative genomic-based therapy approaches.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
114 R117H R334W G314E R347P ∆F508 P574H PS Reduced chloride conductance Reduced levels of cell surface chloride transport Genistein Milrinone Phenylbutyrate UTP INS36217 Moli1901 Class V Mutations causing defects in CFTR channel expression levels. Login to comment

[hide] Use of MALDI-TOF mass spectrometry in a 51-mutatio... Genet Med. 2004 Sep-Oct;6(5):426-30. Buyse IM, McCarthy SE, Lurix P, Pace RP, Vo D, Bartlett GA, Schmitt ES, Ward PA, Oermann C, Eng CM, Roa BB
Use of MALDI-TOF mass spectrometry in a 51-mutation test for cystic fibrosis: evidence that 3199del6 is a disease-causing mutation.
Genet Med. 2004 Sep-Oct;6(5):426-30., [PMID:15371908]

Abstract [show]
PURPOSE: We developed a 51-mutation extended cystic fibrosis (CF) panel that incorporates the 25 previously recommended CFTR mutations, plus 26 additional mutations including 3199del6, which was associated with I148T. METHODS: This assay utilizes an integrated matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry system. RESULTS: CF testing was performed on over 5,000 individuals, including a 3-year-old Hispanic-American patient with a compound heterozygous G542X/3199del6 genotype. He is negative for I148T, or other mutations assessed by CFTR gene sequencing. CONCLUSION: These results demonstrate the successful implementation of MALDI-TOF mass spectrometry in CF clinical testing, and establish 3199del6 as a disease-causing CF mutation.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
41 In the second case, an ASO result of a heterozygous G314E mutation was further characterized by MALDI-TOF mass spectrometry as a different allelic variant, G314A (data not shown). Login to comment
77 This assay also demonstrated heterozygosity for the G542X mutation, and reflex testing for the 5T variant at CFTR intron 8 showed a genotype of 7T/9T in this patient (data not Table 3 Description of the 16 multiplex assays designed to analyze 51 CFTR mutations Multiplex Mutations Exon 1 1078delT, G314E, R352Q, G330X 7 2 R347H, R347P, R334W, 1717-1A 7, 11 3 R553X, S549N, R1162X 11, 19 4 A559T, R560T, G551D 11 5 G542X, S549R, 621ϩ1T, Y122X 4, 11 6 W1282X, 3876delA, 3905insT, D1152H 18, 20 7 3849ϩ4G, 3659delC, 1898ϩ1A 12, 19 8 405ϩ1A, 405ϩ3C, 3120A, 3120ϩ1A 3, 16 9 394delTT, E60X, G85E 3 10 A455E, ⌬F508a 9, 10 11 G480C, Q493X, V520F 10 12 711ϩ1T, G178R, 3199del6 5, 17a 13 2143delT, 2184delA, K710X, F316L 7, 13 14 I148T, R117H, R117C 4 15 N1303K, 2789ϩ5A, 3849ϩ10kbT 14b, intron19, 21 16 ⌬I507a 10 17 5Tb intron 8 a F508C and I507V, I506V, I506M variants are tested for concurrently with the ⌬F508 and ⌬I507 assays respectively. Login to comment
93 Two previously unreported missense alleles were identified: G314A (allelic to G314E) and A455V (allelic to A455E). Login to comment

[hide] Pharmacological induction of CFTR function in pati... Pediatr Pulmonol. 2005 Sep;40(3):183-96. Kerem E
Pharmacological induction of CFTR function in patients with cystic fibrosis: mutation-specific therapy.
Pediatr Pulmonol. 2005 Sep;40(3):183-96., [PMID:15880796]

Abstract [show]
CFTR mutations cause defects of CFTR protein production and function by different molecular mechanisms. Mutations can be classified according to the mechanisms by which they disrupt CFTR function. This understanding of the different molecular mechanisms of CFTR dysfunction provides the scientific basis for the development of targeted drugs for mutation-specific therapy of cystic fibrosis (CF). Class I mutations are nonsense mutations that result in the presence of a premature stop codon that leads to the production of unstable mRNA, or the release from the ribosome of a short, truncated protein that is not functional. Aminoglycoside antibiotics can suppress premature termination codons by disrupting translational fidelity and allowing the incorporation of an amino acid, thus permitting translation to continue to the normal termination of the transcript. Class II mutations cause impairment of CFTR processing and folding in the Golgi. As a result, the mutant CFTR is retained in the endoplasmic reticulum (ER) and eventually targeted for degradation by the quality control mechanisms. Chemical and molecular chaperones such as sodium-4-phenylbutyrate can stabilize protein structure, and allow it to escape from degradation in the ER and be transported to the cell membrane. Class III mutations disrupt the function of the regulatory domain. CFTR is resistant to phosphorylation or adenosine tri-phosphate (ATP) binding. CFTR activators such as alkylxanthines (CPX) and the flavonoid genistein can overcome affected ATP binding through direct binding to a nucleotide binding fold. In patients carrying class IV mutations, phosphorylation of CFTR results in reduced chloride transport. Increases in the overall cell surface content of these mutants might overcome the relative reduction in conductance. Alternatively, restoring native chloride pore characteristics pharmacologically might be effective. Activators of CFTR at the plasma membrane may function by promoting CFTR phosphorylation, by blocking CFTR dephosphorylation, by interacting directly with CFTR, and/or by modulation of CFTR protein-protein interactions. Class V mutations affect the splicing machinery and generate both aberrantly and correctly spliced transcripts, the levels of which vary among different patients and among different organs of the same patient. Splicing factors that promote exon inclusion or factors that promote exon skipping can promote increases of correctly spliced transcripts, depending on the molecular defect. Inconsistent results were reported regarding the required level of corrected or mutated CFTR that had to be reached in order to achieve normal function.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
58 C-D565G II DF508 D1507 S549R S549I S549N S549R S945D S945L H1054D G1061R L1065P R1066C R1066M L1077P H1085R N1303K G85E III G551D S492F V520F R553G R560T R560S Y569D IV R117H, R117C, R117P, R117L D1152H, L88S, G91R, E92K, Q98R, P205S, L206W, L227R, F311L, G314E, R334W, R334Q, I336K, T338I, L346P, R347C, R347H, R347L, R347P, L927P, R1070W, R1070Q V 3849 þ 10 kb C ! Login to comment

[hide] Diversity of the basic defect of homozygous CFTR m... J Med Genet. 2008 Jan;45(1):47-54. Stanke F, Ballmann M, Bronsveld I, Dork T, Gallati S, Laabs U, Derichs N, Ritzka M, Posselt HG, Harms HK, Griese M, Blau H, Mastella G, Bijman J, Veeze H, Tummler B
Diversity of the basic defect of homozygous CFTR mutation genotypes in humans.
J Med Genet. 2008 Jan;45(1):47-54., [PMID:18178635]

Abstract [show]
BACKGROUND: Knowledge of how CFTR mutations other than F508del translate into the basic defect in cystic fibrosis (CF) is scarce due to the low incidence of homozygous index cases. METHODS: 17 individuals who are homozygous for deletions, missense, stop or splice site mutations in the CFTR gene were investigated for clinical symptoms of CF and assessed in CFTR function by sweat test, nasal potential difference and intestinal current measurement. RESULTS: CFTR activity in sweat gland, upper airways and distal intestine was normal for homozygous carriers of G314E or L997F and in the range of F508del homozygotes for homozygous carriers of E92K, W1098L, R553X, R1162X, CFTRdele2(ins186) or CFTRdele2,3(21 kb). Homozygotes for M1101K, 1898+3 A-G or 3849+10 kb C-T were not consistent CF or non-CF in the three bioassays. 14 individuals exhibited some chloride conductance in the airways and/or in the intestine which was identified by the differential response to cAMP and DIDS as being caused by CFTR or at least two other chloride conductances. DISCUSSION: CFTR mutations may lead to unusual electrophysiological or clinical manifestations. In vivo and ex vivo functional assessment of CFTR function and in-depth clinical examination of the index cases are indicated to classify yet uncharacterised CFTR mutations as either disease-causing lesions, risk factors, modifiers or neutral variants.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
3 Results: CFTR activity in sweat gland, upper airways and distal intestine was normal for homozygous carriers of G314E or L997F and in the range of F508del homozygotes for homozygous carriers of E92K, W1098L, R553X, R1162X, CFTRdele2(ins186) or CFTRdele2,3(21 kb). Login to comment
59 The missense mutation E92K results from a G-to-A transition in the first base of exon 4 and hence may not also lead to the substitution of a glutamate by a lysine but also may affect splicing as it has been observed for the stop mutation E92X.21 The G314E and the M1101K homozygotes exhibited an intermediate chloride secretory phenotype between typical CF and typical non-CF. Login to comment
61 The transport rates were in the upper CF range (E92K, W1098L, one M1101K sibling), in the intermediate range between CF and non-CF (the other two M1101K siblings) or in the normal range (L997F, G314E) (fig 1C). Login to comment
62 The tissue specimens from two M1101K homozygous siblings expressed two patterns of chloride secretory responses that are consistent with the presence of both CFTR and the alternative chloride channel ORCC (fig 1E, table 5).7 Since the outcome of NPD, ICM, sweat test and clinical examination was normal in the G314E or L997F homozygotes, the diagnosis of CF that had been based on mutation reports in the literature,18 19 positive family anamnesis or suggestive respiratory symptoms, was withdrawn for these two individuals. Login to comment
70 Splice site mutations, for example, were associated with progressive lung disease and a Table 2 Assessment of basic defect (A): sweat tests and nasal potential difference (NPD) measurements (mV) Patient number CFTR genotype Sweat chloride concentration (mval/l) Basal PD (mV) Change in PD (mV) Day of assessment Prior tests (age) Amiloride Chloride-free + isoproterenol Out-of-frame deletion 1 CFTRdele2,3(21 kb)/CFTRdele2,3(21 kb) 103 95 (10 mo) 260 22 210 Nonsense mutation 2 R553X/R553X 96 100 (16 mo) 262 34 27 3 R1162X/R1162X 98 110 (2 y 1 mo) 248 23 24 4 R1162X/R1162X 104 112 (1 mo) 239 30 0 Splice-site mutation 5 1898+3 A-G/1898+3 A-G 73 69 (4 mo) 233 21 23 6 3849+10 kb C-T/3849+10 kb C-T 92 64 (20 y 5 mo) 244 30 212 49 (28 y 4 mo) 7 3849+10 kb C-T/3849+10 kb C-T 20 50 (11 y 2 mo) 227 12 +3 In-frame deletion 8 CFTRdele2(ins186)/CFTRdele2(ins186) 102 134 (4 mo) 245 30 21 9 CFTRdele2(ins186)/CFTRdele2(ins186) 100 119 (9 y) 248 31 28 10 CFTRdele2(ins186)/CFTRdele2(ins186) 131 100 (4 y) 258 41 212 Missense mutation 11 E92K/E92K 118 93 (8 mo) 252 20 211 12 G314E/G314E 15 43 (6 y 2 mo) 219 4 216 13 L997F/L997F 8 14 W1098L/W1098L 107 118 (2 mo) 15 M1101K/M1101K 108 120 256 33 216 16 M1101K/M1101K 130 120 264 26 215 17 M1101K/M1101K 118 229 13 210 F508del/F508del (n = 74)7 106¡22 256¡10 28¡9 28¡5 non-CF (n = 25) 16¡9 220¡10 11¡6 230¡8 Sibpairs: patients 3 & 4, 6 & 7, 9 & 10, 15, 16 & 17. Login to comment
86 The non-conservative amino acid substitutions L997F and G314E did not impair chloride conductance in sweat glands, airways and intestine. Login to comment
89 Several well characterised severe mutations occur in the evolutionarily conserved Walker (G1244E, G1249E) or dodecapeptide motifs (G551D, G1349D) of the ABC transporter CFTR.1 The missense mutants G622D23 in the regulatory domain and G314E in the fifth transmembrane region led to no clinical symptoms of CF. Login to comment
97 ICM recordings of individuals homozygous for CFTRdele2,3(21 kb) (A), 1898+3 A-G (B), G314E (C), R1162X (D), M1101K (E) or of a healthy non-CF individual (F). Login to comment

[hide] Mutations that permit residual CFTR function delay... Respir Res. 2010 Oct 8;11:140. Green DM, McDougal KE, Blackman SM, Sosnay PR, Henderson LB, Naughton KM, Collaco JM, Cutting GR
Mutations that permit residual CFTR function delay acquisition of multiple respiratory pathogens in CF patients.
Respir Res. 2010 Oct 8;11:140., [PMID:20932301]

Abstract [show]
BACKGROUND: Lung infection by various organisms is a characteristic feature of cystic fibrosis (CF). CFTR genotype effects acquisition of Pseudomonas aeruginosa (Pa), however the effect on acquisition of other infectious organisms that frequently precede Pa is relatively unknown. Understanding the role of CFTR in the acquisition of organisms first detected in patients may help guide symptomatic and molecular-based treatment for CF. METHODS: Lung infection, defined as a single positive respiratory tract culture, was assessed for 13 organisms in 1,381 individuals with CF. Subjects were divided by predicted CFTR function: 'Residual': carrying at least one partial function CFTR mutation (class IV or V) and 'Minimal' those who do not carry a partial function mutation. Kaplan-Meier estimates were created to assess CFTR effect on age of acquisition for each organism. Cox proportional hazard models were performed to control for possible cofactors. A separate Cox regression was used to determine whether defining infection with Pa, mucoid Pa or Aspergillus (Asp) using alternative criteria affected the results. The influence of severity of lung disease at the time of acquisition was evaluated using stratified Cox regression methods by lung disease categories. RESULTS: Subjects with 'Minimal' CFTR function had a higher hazard than patients with 'Residual' function for acquisition of 9 of 13 organisms studied (HR ranging from 1.7 to 3.78 based on the organism studied). Subjects with minimal CFTR function acquired infection at a younger age than those with residual function for 12 of 13 organisms (p-values ranging: < 0.001 to 0.017). Minimal CFTR function also associated with younger age of infection when 3 alternative definitions of infection with Pa, mucoid Pa or Asp were employed. Risk of infection is correlated with CFTR function for 8 of 9 organisms in patients with good lung function (>90%ile) but only 1 of 9 organisms in those with poorer lung function (<50%ile). CONCLUSIONS: Residual CFTR function correlates with later onset of respiratory tract infection by a wide spectrum of organisms frequently cultured from CF patients. The protective effect conferred by residual CFTR function is diminished in CF patients with more advanced lung disease.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
74 For Pa, the hazard ratio Table 1 Classification of CFTR alleles Category Mutation Specific mutations Class I Defective Protein Synthesis (nonsense, frameshift, aberrant splicing) 1078delT, 1154 insTC, 1525-2A > G, 1717-1G > A, 1898+1G > A, 2184delA, 2184 insA, 3007delG, 3120+1G > A, 3659delC, 3876delA, 3905insT, 394delTT, 4010del4, 4016insT, 4326delTC, 4374+1G > T, 441delA, 556delA, 621+1G > T, 621-1G > T, 711+1G > T, 875+1G > C, E1104X, E585X, E60X, E822X, G542X, G551D/R553X, Q493X, Q552X, Q814X, R1066C, R1162X, R553X, V520F, W1282X, Y1092X Class II Abnormal Processing and Trafficking A559T, D979A, ΔF508, ΔI507, G480C, G85E, N1303K, S549I, S549N, S549R Class III Defective Channel Regulation/Gating G1244E, G1349D, G551D, G551S, G85E, H199R, I1072T, I48T, L1077P, R560T, S1255P, S549 (R75Q) Class IV Decreased Channel Conductance A800G, D1152H, D1154G, D614G, delM1140, E822K, G314E, G576A, G622D, G85E, H620Q, I1139V, I1234V, L1335P, M1137V, P67L, R117C, R117P, R117H, R334W, R347H, R347P, R347P/ R347H, R792G, S1251N, V232D Class V Reduced Synthesis and/or Trafficking 2789+5G > A, 3120G > A, 3272-26A > G, 3849+10kbC > T, 5T variant, 621+3A > G, 711+3A > G, A445E, A455E, IVS8 poly T, P574H was increased 3 fold for those with 'Minimal` function when compared to those with 'Residual` function. Login to comment

[hide] CFTR: mechanism of anion conduction. Physiol Rev. 1999 Jan;79(1 Suppl):S47-75. Dawson DC, Smith SS, Mansoura MK
CFTR: mechanism of anion conduction.
Physiol Rev. 1999 Jan;79(1 Suppl):S47-75., [PMID:9922376]

Abstract [show]
CFTR: Mechanism of Anion Conduction. Physiol. Rev. 79, Suppl.: S47-S75, 1999. - The purpose of this review is to collect together the results of recent investigations of anion conductance by the cystic fibrosis transmembrane conductance regulator along with some of the basic background that is a prerequisite for developing some physical picture of the conduction process. The review begins with an introduction to the concepts of permeability and conductance and the Nernst-Planck and rate theory models that are used to interpret these parameters. Some of the physical forces that impinge on anion conductance are considered in the context of permeability selectivity and anion binding to proteins. Probes of the conduction process are considered, particularly permeant anions that bind tightly within the pore and block anion flow. Finally, structure-function studies are reviewed in the context of some predictions for the origin of pore properties.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
248 This effect is, in fact, seen in CFTR mutations (Fig. 3) is a function of the well depth, Gw 0 Gb , i.e. like G314E, which destabilizes relative anion binding, but also reduces single-channel conductance rather than increasing single-channel conductance as would be ex- bi Å expͫ0(Gw 0 Gb) RT ͬ (31) pected if only the well depth were affected (Mansoura and Dawson, unpublished data). Login to comment
425 Iodide permeation ing must be interpreted with caution for a number of reasons. First, it has been demonstrated (101) that the In any survey of the permeation of monatomic and polyatomic anions through CFTR, iodide stands out asCFTR mutations (e.g., G314Q or G314E) result in CFTR channels that exhibit markedly reduced anion binding, exhibiting some unique, or perhaps exaggerated, properties. Login to comment
597 Transmembrane segment 2 and TM6 sequences formed anion-selective channels in bilayers,the site of two patient mutations, and found that SCN block of CFTR was abolished in G314E and G314Q CFTR, whereas peptides based on TM1, TM3, TM4, and TM5 did not. Login to comment

[hide] Membrane-integration characteristics of two ABC tr... J Mol Biol. 2009 Apr 17;387(5):1153-64. Epub 2009 Feb 21. Enquist K, Fransson M, Boekel C, Bengtsson I, Geiger K, Lang L, Pettersson A, Johansson S, von Heijne G, Nilsson I
Membrane-integration characteristics of two ABC transporters, CFTR and P-glycoprotein.
J Mol Biol. 2009 Apr 17;387(5):1153-64. Epub 2009 Feb 21., [PMID:19236881]

Abstract [show]
To what extent do corresponding transmembrane helices in related integral membrane proteins have different membrane-insertion characteristics? Here, we compare, side-by-side, the membrane insertion characteristics of the 12 transmembrane helices in the adenosine triphosphate-binding cassette (ABC) transporters, P-glycoprotein (P-gp) and the cystic fibrosis transmembrane conductance regulator (CFTR). Our results show that 10 of the 12 CFTR transmembrane segments can insert independently into the ER membrane. In contrast, only three of the P-gp transmembrane segments are independently stable in the membrane, while the majority depend on the presence of neighboring loops and/or transmembrane segments for efficient insertion. Membrane-insertion characteristics can thus vary widely between related proteins.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
113 For CFTR, we chose mutations located in TM1CFTR (F87L, G91R), TM3CFTR (P205S, L206W), TM4CFTR (C225R), TM5CFTR (DF311, G314E), TM6CFTR (R334L/W, I336K/R/D, I340N/S, L346P, R347L/H), TM8CFTR (S909I, S912L), TM9CFTR (I1005R, A1006E), TM10CFTR (Y1032N), and TM12CFTR (M1137R, ΔM1140, M1140K), or close to the TM region of TM1CFTR (R74W, L102R/P), TMF2CFTR (R117P/L, L137P), and TM11CFTR (M1101K/R). Login to comment
109 For CFTR, we chose mutations located in TM1CFTR (F87L, G91R), TM3CFTR (P205S, L206W), TM4CFTR (C225R), TM5CFTR (DF311, G314E), TM6CFTR (R334L/W, I336K/R/D, I340N/S, L346P, R347L/H), TM8CFTR (S909I, S912L), TM9CFTR (I1005R, A1006E), TM10CFTR (Y1032N), and TM12CFTR (M1137R, ƊM1140, M1140K), or close to the TM region of TM1CFTR (R74W, L102R/P), TMF2CFTR (R117P/L, L137P), and TM11CFTR (M1101K/R). Login to comment

[hide] Cystic fibrosis: insight into CFTR pathophysiology... Clin Biochem. 2012 Oct;45(15):1132-44. doi: 10.1016/j.clinbiochem.2012.05.034. Epub 2012 Jun 12. Lubamba B, Dhooghe B, Noel S, Leal T
Cystic fibrosis: insight into CFTR pathophysiology and pharmacotherapy.
Clin Biochem. 2012 Oct;45(15):1132-44. doi: 10.1016/j.clinbiochem.2012.05.034. Epub 2012 Jun 12., [PMID:22698459]

Abstract [show]
Cystic fibrosis is the most common life-threatening recessively inherited disease in Caucasians. Due to early provision of care in specialized reference centers and more comprehensive care, survival has improved over time. Despite great advances in supportive care and in our understanding of its pathophysiology, there is still no cure for the disease. Therapeutic strategies aimed at rescuing the abnormal protein are either being sought after or under investigation. This review highlights salient insights into pathophysiology and candidate molecules suitable for CFTR pharmacotherapy. Clinical trials using Ataluren, VX-809 and ivacaftor have provided encouraging data. Preclinical data with inhibitors of phosphodiesterase type 5, such as sildenafil and analogs, have highlighted their potential for CFTR pharmacotherapy. Because sildenafil and analogs are in clinical use for other clinical applications, research on this class of drugs might speed up the development of new therapies for CF.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
982 Class Mutation prototypes Consequences Severe CF phenotype I G542X, W1282X, R553X, 3950delT CFTR is not synthesized because of stop codons or splicing defects II F508del, N1303K CFTR is synthesized but in an immature form (only partly glycosylated, misfolded, not released from the endoplasmic reticulum) and is mostly degraded by the ubiquitin-proteasomal pathway III G551D CFTR is synthesized and transported to the plasma membrane, but its activation and regulation by ATP or cAMP are disrupted Milder CF phenotype IV R334W, G314E, R347P, D1152H CFTR is synthesized and expressed at the plasma membrane, but chloride conductance is reduced V 3849+10 kb C>T, 3272-26 A>G CFTR synthesis or processing is partly defective Severe CF phenotype VI 1811+1.6 kb A>G CFTR is synthesized, but membrane stability or conductance of ions other than chloride is reduced Fig. 2. Login to comment

[hide] Cystic fibrosis: a multiple exocrinopathy caused b... Am J Med. 1998 Jun;104(6):576-90. Schwiebert EM, Benos DJ, Fuller CM
Cystic fibrosis: a multiple exocrinopathy caused by dysfunctions in a multifunctional transport protein.
Am J Med. 1998 Jun;104(6):576-90., [PMID:9674722]

Abstract [show]

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
243 Other mutations in TMD1 which affect function and cause disease include other arginines in predicted ␣-helix 6, R334W, R347P, and R347E (97,98) and a glycine, G314E, in ␣-helix 5 (99). Login to comment

[hide] Cystic fibrosis transmembrane conductance regulato... Biophys J. 1998 Mar;74(3):1320-32. Mansoura MK, Smith SS, Choi AD, Richards NW, Strong TV, Drumm ML, Collins FS, Dawson DC
Cystic fibrosis transmembrane conductance regulator (CFTR) anion binding as a probe of the pore.
Biophys J. 1998 Mar;74(3):1320-32., [PMID:9512029]

Abstract [show]
We compared the effects of mutations in transmembrane segments (TMs) TM1, TM5, and TM6 on the conduction and activation properties of the cystic fibrosis transmembrane conductance regulator (CFTR) to determine which functional property was most sensitive to mutations and, thereby, to develop a criterion for measuring the importance of a particular residue or TM for anion conduction or activation. Anion substitution studies provided strong evidence for the binding of permeant anions in the pore. Anion binding was highly sensitive to point mutations in TM5 and TM6. Permeability ratios, in contrast, were relatively unaffected by the same mutations, so that anion binding emerged as the conduction property most sensitive to structural changes in CFTR. The relative insensitivity of permeability ratios to CFTR mutations was in accord with the notion that anion-water interactions are important determinants of permeability selectivity. By the criterion of anion binding, TM5 and TM6 were judged to be likely to contribute to the structure of the anion-selective pore, whereas TM1 was judged to be less important. Mutations in TM5 and TM6 also dramatically reduced the sensitivity of CFTR to activation by 3-isobutyl 1-methyl xanthine (IBMX), as expected if these TMs are intimately involved in the physical process that opens and closes the channel.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
28 Another residue in TM1, K95, was implicated as being important for anion selectivity (Anderson et al., 1991), but mutants at this locus did not give rise to robust expression in Xenopus oocytes. TM5 has a relatively high frequency of patient mutations compared with the other 11 putative TMs (Cystic Fibrosis Genetic Analysis Consortium, unpublished data), and two missense patient mutations, G314E (Golla et al., 1994) and G314R (Nasr et al., 1996), have been identified at G314. Login to comment
62 Expression levels Wild-type and 11 mutant CFTR constructs were used in this study: G91A, G91E, G91R, G314A, G314D, G314E, G314Q, K335R, K335A, K335D, and K335E. Login to comment
115 Most dramatic here was the substitution of glutamic acid (G314E), which raised conductance ratios for SCN, NO3, and Br. Login to comment
116 It was of particular interest that the introduction of a glutamine (G314Q) also produced increased conductance ratios for the highly permeant anions and I, whereas the aspartic-acid-substituted construct (G314D) was not different from wtCFTR. Login to comment
120 As an example, the I-V plots shown in Fig. 2, A and B, illustrate the effect of [SCN]o substitution on wild-type and G314E CFTR. Login to comment
122 In the G314E mutant the attenuation of gCl by 2% [SCN]o was virtually abolished. Login to comment
136 In the case of the G314E and G314Q mutants, however, the SCN effect appeared to be moderately voltage dependent (Fig. 2 TABLE 2 Summary of permeability and conductance ratios from anion substitution experiments n SCN NO3 Br HCOO I A. Login to comment
137 Permeability Ratios Wild type 4-9 3.42 Ϯ 0.28 1.42 Ϯ 0.04 1.22 Ϯ 0.02 0.39 Ϯ 0.01 0.44 Ϯ 0.03 G91A 3-6 3.24 Ϯ 0.26 1.53 Ϯ 0.04 1.27 Ϯ 0.02 0.37 Ϯ 0.04 0.40 Ϯ 0.04 G91E 3-7 3.50 Ϯ 0.54 1.59 Ϯ 0.04 1.27 Ϯ 0.01 0.35 Ϯ 0.01 0.51 Ϯ 0.04 G91R 3-4 5.26 ؎ 0.46* 1.60 Ϯ 0.03 1.40 ؎ 0.01* 0.32 Ϯ 0.04 0.64 ؎ 0.04* G314A 3-4 2.87 Ϯ 0.17 1.45 Ϯ 0.03 1.19 Ϯ 0.02 0.31 Ϯ 0.03 0.33 Ϯ 0.03 G314D 4 3.42 Ϯ 0.34 1.44 Ϯ 0.05 1.25 Ϯ 0.04 0.33 Ϯ 0.03 0.51 Ϯ 0.05 G314E 3-4 3.72 Ϯ 0.56 1.65 ؎ 0.09* 1.35 ؎ 0.03* 0.49 Ϯ 0.04 0.53 Ϯ 0.04 G314Q 3-4 3.89 Ϯ 0.37 1.62 Ϯ 0.11 1.27 Ϯ 0.04 0.36 Ϯ 0.03 0.62 Ϯ 0.05 K335R 3-5 3.44 Ϯ 0.29 1.35 Ϯ 0.04 1.22 Ϯ 0.03 0.40 Ϯ 0.05 0.41 Ϯ 0.07 K335A 5-6 5.34 ؎ 0.58* 1.48 Ϯ 0.06 1.28 Ϯ 0.04 0.37 Ϯ 0.03 0.60 Ϯ 0.06 K335D 4-6 3.02 Ϯ 0.19 1.50 Ϯ 0.03 1.10 ؎ 0.02* 0.54 ؎ 0.04* 0.65 ؎ 0.06* K335E 5-8 3.64 Ϯ 0.21 1.48 Ϯ 0.06 1.29 Ϯ 0.03 0.46 Ϯ 0.04 1.10 ؎ 0.04* B. Conductance Ratios Wild type 4-9 0.14 Ϯ 0.02 0.75 Ϯ 0.02 0.64 Ϯ 0.02 0.52 Ϯ 0.03 0.18 Ϯ 0.03 G91A 3-6 0.14 Ϯ 0.01 0.77 Ϯ 0.02 0.61 Ϯ 0.02 0.47 Ϯ 0.02 0.19 Ϯ 0.02 G91E 3-7 0.15 Ϯ 0.03 0.73 Ϯ 0.02 0.60 Ϯ 0.01 0.50 Ϯ 0.04 0.30 Ϯ 0.02 G91R 3-4 0.14 Ϯ 0.00 0.84 Ϯ 0.01 0.63 Ϯ 0.01 0.32 ؎ 0.01* 0.14 Ϯ 0.01 G314A 3-4 0.30 Ϯ 0.09 0.89 ؎ 0.01* 0.66 Ϯ 0.01 0.48 Ϯ 0.09 0.24 Ϯ 0.01 G314D 4 0.28 Ϯ 0.05 0.82 Ϯ 0.01 0.70 Ϯ 0.02 0.49 Ϯ 0.06 0.27 Ϯ 0.03 G314E 3-4 0.62 ؎ 0.07* 1.18 ؎ 0.04* 0.84 ؎ 0.05* 0.42 Ϯ 0.05 0.29 Ϯ 0.09 G314Q 3-4 0.63 ؎ 0.02* 1.01 ؎ 0.04* 0.82 ؎ 0.03* 0.50 Ϯ 0.02 0.42 ؎ 0.02* K335R 3-5 0.14 Ϯ 0.01 0.76 Ϯ 0.03 0.61 Ϯ 0.02 0.59 Ϯ 0.06 0.16 Ϯ 0.03 K335A 6 0.20 Ϯ 0.03 0.77 Ϯ 0.02 0.61 Ϯ 0.02 0.45 Ϯ 0.03 0.21 Ϯ 0.02 K335D 4-6 0.65 ؎ 0.04* 1.25 ؎ 0.02* 0.89 ؎ 0.02* 0.61 Ϯ 0.06 0.58 ؎ 0.06* K335E 5-8 0.50 ؎ 0.06* 1.19 ؎ 0.03* 0.89 ؎ 0.02* 0.53 Ϯ 0.03 0.48 ؎ 0.03* (A) The apparent permeability ratios (PS/PCl) for each substitute anion were calculated from the shift in reversal potential using the Goldman-Hodgkin-Katz relation (noted in Materials and Methods). Login to comment
147 The data in Table 3 show that for wtCFTR and G314Q and G314E, two of the most severely affected constructs, PSCN/PCl calculated from the shift in Vr was independent of the fractional abundance of [SCN]o. Login to comment
150 Of the three substitutions for G91, the arginine (G91R) altered the RR most dramatically, increasing it nearly sevenfold, although the negatively charged glutamate (G91E) FIGURE 2 The effect of replacement of [Cl- ]o by [SCN- ]o is shown for wtCFTR (A) and G314E (B). Login to comment
169 TABLE 4 Quantitative analyses of the macroscopic I-V shape changes Mutant ⌬ Net charge n RR g(ϩ30)/g(-30) RR/RRWT Wild type 5 1.220 Ϯ 0.06 1.00 G91A 0 4 1.293 Ϯ 0.06 1.06 G91E -1 5 1.512 ؎ 0.10* 1.24 G91R 1 4 8.041 ؎ 0.87* 6.59 G314A 0 4 1.201 Ϯ 0.09 0.98 G314D -1 4 1.362 Ϯ 0.08 1.12 G314E -1 7 1.405 >e; 0.08 1.15 G314Q 0 5 1.376 Ϯ 0.10 1.13 K335R 0 4 1.209 Ϯ 0.06 0.99 K335A -1 4 1.295 Ϯ 0.07 1.06 K335D -2 5 0.762 ؎ 0.02* 0.62 K335E -2 4 0.919 ؎ 0.02* 0.75 The slope conductance was measured at ϩ30 mV and -30 mV with respect to the reversal potential. Login to comment
171 TABLE 3 The permeability ratio (PSCN/PCl) is independent of the mole fraction of [SCN]0 for wtCFTR and the G314 variants [SCN]/{[SCN]ϩ[Cl]} n PSCN/PCl 0.02 0.05 0.10 0.20 0.50 0.90 Wild type 12 3.82 Ϯ 0.50 4.43 Ϯ 0.57 4.58 Ϯ 0.48 4.69 Ϯ 0.43 4.66 Ϯ 0.38 4.44 Ϯ 0.35 G314A 9 4.32 Ϯ 0.73 3.78 Ϯ 0.53 3.81 Ϯ 0.47 3.79 Ϯ 0.34 3.82 Ϯ 0.29 3.72 Ϯ 0.25 G314D 3 2.99 Ϯ 0.26 2.56 Ϯ 1.05 2.82 Ϯ 1.07 2.68 Ϯ 0.97 2.87 Ϯ 0.65 2.89 Ϯ 0.43 G314E 6 4.48 Ϯ 1.05 4.01 Ϯ 0.69 4.17 Ϯ 0.62 4.15 Ϯ 0.59 3.96 Ϯ 0.41 3.82 Ϯ 0.40 G314Q 3 5.39 Ϯ 0.57 4.49 Ϯ 0.58 4.69 Ϯ 1.26 4.05 Ϯ 1.26 3.86 Ϯ 1.47 3.68 Ϯ 1.51 The permeability ratios were calculated from the shift in reversal potential using the Goldman-Hodgkin-Katz equation. Login to comment
173 TABLE 5 Concentration-dependent activation of wtCFTR, G91, G314, and K335 variants by IBMX in the presence of 10 ␮M forskolin Mutant n K1/2(IBMX) (mM) Wild type 15 0.35 Ϯ 0.04 G91A 5 0.42 Ϯ 0.06 G91E 8 0.51 ؎ 0.06* G91R 5 0.49 Ϯ 0.09 G314A 10 1.21 ؎ 0.11* G314D 3 1.35 ؎ 0.16* G314E 8 6.39 ؎ 1.35* G314Q 4 14.26 ؎ 6.64* K335R 4 0.46 Ϯ 0.04 K335A 2 0.35 Ϯ 0.15 K335D 7 0.87 ؎ 0.13* K335E 3 0.95 ؎ 0.07* The steady-state slope conductance was measured at -60 mV as increasing concentrations of IBMX (0.02-5.0 mM) were added to the perfusate in the continued presence of 10 mM forskolin. Login to comment
175 Note that this fitting procedure allows us to estimate K1/2 values for even the most insensitive constructs, G314E and G314Q, despite the fact that these values were greater than the highest concentration of IBMX used in this study. Login to comment
178 The K1/2 seen with either G314E or G314Q was comparable to that seen with nucleotide-binding mutations such as G551D that are associated with severe CF (Wilkinson et al., 1996). Login to comment
195 The pattern of the effect of anion substitution was identical for Br, NO3, and SCN, and the conductance ratio for all three ions was increased in G314E and G314Q CFTR channels. Login to comment
198 The results presented here are consistent with the notion that the binding of anions within the CFTR pore is a sensitive indicator of changes in pore structure whereas permeability ratios appear to be rather insensitive to similar TABLE 6 Qualitative summary of the functional consequences of mutations at G91, G314, and K335 Property G91 (TM1) K335 (TM6) G314 (TM5) G91A G91E G91R K335R K335A K335D K335E G314A G314D G314E G314Q I-V shape - - ϩϩϩ - - ϩϩ ϩ - - - - Psub/PCl - - - - - - ϩϩ - - - - gsub/gCl - - - - - ϩϩϩ ϩϩϩ ϩϩ - ϩϩϩ ϩϩϩ SCN- binding - - - - - ϩϩϩ ϩϩϩ ϩϩ - ϩϩϩϩ ϩϩϩϩ Activation - - - - - ϩϩ ϩϩ ϩϩϩ ϩϩϩ ϩϩϩϩ ϩϩϩϩ Results are expressed as follows: -, function of the CFTR construct with the indicated substitution was indistinguishable from wild type; ϩ to ϩϩϩϩ, semiquantitative indication of the magnitude of the change in the function compared with wild type. Login to comment
233 The increased conductance ratios seen in G314E, G314Q, and to a lesser extent, G314A channels are compatible with the hypothesis that substitution for G314 distorted an anion binding site such that the affinities for Br, NO3, and SCN were all reduced relative to Cl. Login to comment
263 In contrast, G314E CFTR exhibited a dramatic decrease in anion binding and sensitivity to activation by IBMX but no change in I-V shape. Login to comment
121 As an example, the I-V plots shown in Fig. 2, A and B, illustrate the effect of [SCN]o substitution on wild-type and G314E CFTR. Login to comment
123 In the G314E mutant the attenuation of gCl by 2% [SCN]o was virtually abolished. Login to comment
138 Permeability Ratios Wild type 4-9 3.42 afe; 0.28 1.42 afe; 0.04 1.22 afe; 0.02 0.39 afe; 0.01 0.44 afe; 0.03 G91A 3-6 3.24 afe; 0.26 1.53 afe; 0.04 1.27 afe; 0.02 0.37 afe; 0.04 0.40 afe; 0.04 G91E 3-7 3.50 afe; 0.54 1.59 afe; 0.04 1.27 afe; 0.01 0.35 afe; 0.01 0.51 afe; 0.04 G91R 3-4 5.26 d1e; 0.46* 1.60 afe; 0.03 1.40 d1e; 0.01* 0.32 afe; 0.04 0.64 d1e; 0.04* G314A 3-4 2.87 afe; 0.17 1.45 afe; 0.03 1.19 afe; 0.02 0.31 afe; 0.03 0.33 afe; 0.03 G314D 4 3.42 afe; 0.34 1.44 afe; 0.05 1.25 afe; 0.04 0.33 afe; 0.03 0.51 afe; 0.05 G314E 3-4 3.72 afe; 0.56 1.65 d1e; 0.09* 1.35 d1e; 0.03* 0.49 afe; 0.04 0.53 afe; 0.04 G314Q 3-4 3.89 afe; 0.37 1.62 afe; 0.11 1.27 afe; 0.04 0.36 afe; 0.03 0.62 afe; 0.05 K335R 3-5 3.44 afe; 0.29 1.35 afe; 0.04 1.22 afe; 0.03 0.40 afe; 0.05 0.41 afe; 0.07 K335A 5-6 5.34 d1e; 0.58* 1.48 afe; 0.06 1.28 afe; 0.04 0.37 afe; 0.03 0.60 afe; 0.06 K335D 4-6 3.02 afe; 0.19 1.50 afe; 0.03 1.10 d1e; 0.02* 0.54 d1e; 0.04* 0.65 d1e; 0.06* K335E 5-8 3.64 afe; 0.21 1.48 afe; 0.06 1.29 afe; 0.03 0.46 afe; 0.04 1.10 d1e; 0.04* B. Conductance Ratios Wild type 4-9 0.14 afe; 0.02 0.75 afe; 0.02 0.64 afe; 0.02 0.52 afe; 0.03 0.18 afe; 0.03 G91A 3-6 0.14 afe; 0.01 0.77 afe; 0.02 0.61 afe; 0.02 0.47 afe; 0.02 0.19 afe; 0.02 G91E 3-7 0.15 afe; 0.03 0.73 afe; 0.02 0.60 afe; 0.01 0.50 afe; 0.04 0.30 afe; 0.02 G91R 3-4 0.14 afe; 0.00 0.84 afe; 0.01 0.63 afe; 0.01 0.32 d1e; 0.01* 0.14 afe; 0.01 G314A 3-4 0.30 afe; 0.09 0.89 d1e; 0.01* 0.66 afe; 0.01 0.48 afe; 0.09 0.24 afe; 0.01 G314D 4 0.28 afe; 0.05 0.82 afe; 0.01 0.70 afe; 0.02 0.49 afe; 0.06 0.27 afe; 0.03 G314E 3-4 0.62 d1e; 0.07* 1.18 d1e; 0.04* 0.84 d1e; 0.05* 0.42 afe; 0.05 0.29 afe; 0.09 G314Q 3-4 0.63 d1e; 0.02* 1.01 d1e; 0.04* 0.82 d1e; 0.03* 0.50 afe; 0.02 0.42 d1e; 0.02* K335R 3-5 0.14 afe; 0.01 0.76 afe; 0.03 0.61 afe; 0.02 0.59 afe; 0.06 0.16 afe; 0.03 K335A 6 0.20 afe; 0.03 0.77 afe; 0.02 0.61 afe; 0.02 0.45 afe; 0.03 0.21 afe; 0.02 K335D 4-6 0.65 d1e; 0.04* 1.25 d1e; 0.02* 0.89 d1e; 0.02* 0.61 afe; 0.06 0.58 d1e; 0.06* K335E 5-8 0.50 d1e; 0.06* 1.19 d1e; 0.03* 0.89 d1e; 0.02* 0.53 afe; 0.03 0.48 d1e; 0.03* (A) The apparent permeability ratios (PS/PCl) for each substitute anion were calculated from the shift in reversal potential using the Goldman-Hodgkin-Katz relation (noted in Materials and Methods). Login to comment
148 The data in Table 3 show that for wtCFTR and G314Q and G314E, two of the most severely affected constructs, PSCN/PCl calculated from the shift in Vr was independent of the fractional abundance of [SCN]o. Login to comment
151 Of the three substitutions for G91, the arginine (G91R) altered the RR most dramatically, increasing it nearly sevenfold, although the negatively charged glutamate (G91E) FIGURE 2 The effect of replacement of [Clafa; ]o by [SCNafa; ]o is shown for wtCFTR (A) and G314E (B). Login to comment

[hide] Novel missense mutation (G314R) in a cystic fibros... Hum Mutat. 1996;7(2):151-4. Nasr SZ, Strong TV, Mansoura MK, Dawson DC, Collins FS
Novel missense mutation (G314R) in a cystic fibrosis patient with hepatic failure.
Hum Mutat. 1996;7(2):151-4., [PMID:8829633]

Abstract [show]

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
56 CFTR constructs bearing either the G314A or G314E substitution were associated with readily discernable CAMP-induced C1 currents. Login to comment
57 The G314E substitution has been associated with cystic fibrosis (GollaL et al., 1994). Login to comment
73 Cyclic AMP-activated C1 currents were only barely detectable with this construct, whereas wt and AF508 CFTR, as well as variants bearing more conservative substitutions at the same site (G314A and G314E), were associated with the expression of significant C1 channel function. Login to comment

[hide] Cystic fibrosis: genotypic and phenotypic variatio... Annu Rev Genet. 1995;29:777-807. Zielenski J, Tsui LC
Cystic fibrosis: genotypic and phenotypic variations.
Annu Rev Genet. 1995;29:777-807., [PMID:8825494]

Abstract [show]
Cystic fibrosis (CF) is a common genetic disorder in the Caucasian population. The gene was identified in 1989 on the basis of its map location on chromosome 7. The encoded gene product, named cystic fibrosis transmembrane conductance regulator (CFTR), corresponds to a cAMP-regulated chloride channel found almost exclusively in the secretory epithelial cells. Although the major mutation that results in a single amino acid deletion (F508) accounts for 70% of the disease alleles, more than 550 additional mutant alleles of different forms have been detected. Many of these mutations can be divided into five general classes in terms of their demonstrated or presumed molecular consequences. In addition, a good correlation has been found between CFTR genotype and one of the clinical variables--pancreatic function status. An unexpected finding, however, is the documentation of CFTR mutations in patients with atypical CF disease presentations, including congenital absence of vas deferens and several pulmonary diseases. Thus, the implication of CFTR mutation is more profound than CF alone.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
634 Examples of this group include R l 17H near TM2, G314E in TM5, and R334W and R347P in TM6. Login to comment

[hide] Genetic analysis of Hispanic individuals with cyst... Am J Hum Genet. 1994 Mar;54(3):443-6. Grebe TA, Seltzer WK, DeMarchi J, Silva DK, Doane WW, Gozal D, Richter SF, Bowman CM, Norman RA, Rhodes SN, et al.
Genetic analysis of Hispanic individuals with cystic fibrosis.
Am J Hum Genet. 1994 Mar;54(3):443-6., [PMID:7509564]

Abstract [show]
We have performed molecular genetic analyses of Hispanic individuals with cystic fibrosis (CF) in the southwestern United States. Of 129 CF chromosomes analyzed, only 46% (59/129) carry delta F508. The G542X mutation was found on 5% (7/129) of CF chromosomes. The 3849 + 10kbC-->T mutation, detected primarily in Ashkenazi Jews, was present on 2% (3/129). R1162X and R334W, mutations identified in Spain and Italy, each occurred on 1.6% (2/129) of CF chromosomes. W1282X and R553X were each detected once. G551D and N1303K were not found. Overall, screening for 22 or more mutations resulted in detection of only 58% of CF transmembrane conductance regulator gene mutations among Hispanic individuals. Analysis of KM19/XV2c haplotypes revealed an unusual distribution. Although the majority of delta F508 mutations are on chromosomes of B haplotypes, the other CF mutations are on A and C haplotypes at higher-than-expected frequencies. These genetic analyses demonstrate significant differences between Hispanic individuals with CF and those of the general North American population. Assessment of carrier/affected risk in Hispanic CF individuals cannot, therefore, be based on the mutation frequencies found through studies of the general population but must be adjusted to better reflect the genetic makeup of this ethnic group. Further studies are necessary to identify the causative mutation(s) in this population and to better delineate genotype/phenotype correlations. These will enable counselors to provide more accurate genetic counseling.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
45 The following CFTR gene mutations were identified by published methods: AF508 (Rommens et al. 1990); G542X (Kerem et al. 1990); GS51D and R553X (Cutting et al. 1990); R1162X (Gasparini et al. 1991); W1282X (Vidaud et al. 1990); N1303K (Osborne et al. 1991); 3849 +lOkbC- T (Highsmith et al., submitted); and R117H, Y122X, 1148T, 621+1G-*oT, 711+1G- T, G314E, 1078AT, R334W, R347P, Q493X, A1507, V520F, 1717 -1G-oA, R560T, and 3569AC (J. DeMarchi et al., submitted). Login to comment
54 COther = A1507, 621+1G- T, R117H, N1303K, 711+1G-*.T, 1717-1G-.A, R560T, Y122X, 1148T, G314E, 1078AT, R347P, Q493X, V520F, and 3659AC. Login to comment
56 The G542X mutation was found in 5.4% of Hispanic CF chromosomes, similar to the 3% frequency in the general population. Login to comment
47 The following CFTR gene mutations were identified by published methods: AF508 (Rommens et al. 1990); G542X (Kerem et al. 1990); GS51D and R553X (Cutting et al. 1990); R1162X (Gasparini et al. 1991); W1282X (Vidaud et al. 1990); N1303K (Osborne et al. 1991); 3849 +lOkbC-T (Highsmith et al., submitted); and R117H, Y122X, 1148T, 621+1G-*oT, 711+1G-T, G314E, 1078AT, R334W, R347P, Q493X, A1507, V520F, 1717 -1G-oA, R560T, and 3569AC (J. DeMarchi et al., submitted). Login to comment

[hide] Therapeutic strategies to correct malfunction of C... Paediatr Respir Rev. 2001 Jun;2(2):159-64. Lim M, Zeitlin PL
Therapeutic strategies to correct malfunction of CFTR.
Paediatr Respir Rev. 2001 Jun;2(2):159-64., [PMID:12531063]

Abstract [show]
Cystic fibrosis (CF) is a systemic autosomal recessive inherited disorder that results from mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Although the gene was cloned 11 years ago, there still is no definitive treatment to correct the functional deficit. Current treatment strategies focus on pancreatic enzyme replacement and control of pulmonary inflammation and infection. This review examines novel strategies still in preclinical development or phase 1 clinical trials. Gene therapy is an evolving area of study that offers the potential for a cure for cystic fibrosis. CF lung disease is a significant barrier to effective gene delivery and transfer, but new vectors show promise in overcoming these limitations. There are also new pharmacological therapies aimed at correcting defects in CFTR processing and function. These are tailored to the specific class of mutation but may offer therapeutic benefit to many patients. They include phenylbutyrate, flavonoids, aminoglycosides and xanthines.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
60 Type Genotype Phenotypea Defect Potential therapeutics Class I G542X PI No CFTR synthesis, aminoglycosides 621 + 1 G ࢐T No cell surface Cl- 3905insT transport W1282X R553X 1717-1 G ࢐ A Class II F508b PI Defective CFTR 4-PBA, flavonoids, N1303K trafficking and chemical chaperones, P574Hb processing xanthines A455Eb Class III G551D PI Defective channel flavonoids, milrinone G551S regulation, reduced or absent Cl-transport Class IV R117H PS Reduced Cl-transport 4-PBA, xanthines, R334W flavonoids G314E R347P F508b P574Hb ClassV 3849 + 10 kb C࢐T PS Reduced number of flavonoids, milrinone, 2789 + 5 G ࢐A normal CFTR proteins 4-PBA 3272 - 26 A ࢐ G Reduced Cl-transport A455Eb 3120+1 G࢐A 1811 + 1.6 kb A ࢐ G a PI indicates pancreatic insufficiency; PS indicates pancreatic sufficiency. Login to comment

[hide] Impact of heterozygote CFTR mutations in COPD pati... Respir Res. 2014 Feb 11;15:18. doi: 10.1186/1465-9921-15-18. Raju SV, Tate JH, Peacock SK, Fang P, Oster RA, Dransfield MT, Rowe SM
Impact of heterozygote CFTR mutations in COPD patients with chronic bronchitis.
Respir Res. 2014 Feb 11;15:18. doi: 10.1186/1465-9921-15-18., [PMID:24517344]

Abstract [show]
BACKGROUND: Cigarette smoking causes Chronic Obstructive Pulmonary Disease (COPD), the 3rd leading cause of death in the U.S. CFTR ion transport dysfunction has been implicated in COPD pathogenesis, and is associated with chronic bronchitis. However, susceptibility to smoke induced lung injury is variable and the underlying genetic contributors remain unclear. We hypothesized that presence of CFTR mutation heterozygosity may alter susceptibility to cigarette smoke induced CFTR dysfunction. Consequently, COPD patients with chronic bronchitis may have a higher rate of CFTR mutations compared to the general population. METHODS: Primary human bronchial epithelial cells derived from F508del CFTR heterozygotes and mice with (CFTR+/-) and without (CFTR+/+) CFTR heterozygosity were exposed to whole cigarette smoke (WCS); CFTR-dependent ion transport was assessed by Ussing chamber electrophysiology and nasal potential difference measurements, respectively. Caucasians with COPD and chronic bronchitis, age 40 to 80 with FEV1/FVC < 0.70 and FEV1 < 60% predicted, were selected for genetic analysis from participants in the NIH COPD Clinical Research Network's Azithromycin for Prevention of Exacerbations of COPD in comparison to 32,900 Caucasian women who underwent prenatal genetic testing. Genetic analysis involved an allele-specific genotyping of 89 CFTR mutations. RESULTS: Exposure to WCS caused a pronounced reduction in CFTR activity in both CFTR (+/+) cells and F508del CFTR (+/-) cells; however, neither the degree of decrement (44.7% wild-type vs. 53.5% F508del heterozygous, P = NS) nor the residual CFTR activity were altered by CFTR heterozygosity. Similarly, WCS caused a marked reduction in CFTR activity measured by NPD in both wild type and CFTR heterozygous mice, but the severity of decrement (91.1% wild type vs. 47.7% CF heterozygous, P = NS) and the residual activity were not significantly affected by CFTR genetic status. Five of 127 (3.9%) COPD patients with chronic bronchitis were heterozygous for CFTR mutations which was not significantly different from controls (4.5%) (P = NS). CONCLUSIONS: The magnitude of WCS induced reductions in CFTR activity was not affected by the presence of CFTR mutation heterozygosity. CFTR mutations do not increase the risk of COPD with chronic bronchitis. CFTR dysfunction due to smoking is primarily an acquired phenomenon and is not affected by the presence of congenital CFTR mutations.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
81 As expected based on genotype-phenotype correlations in the disease [33], HBE cells derived from a F508del CFTR heterozygote had slightly lower CFTR activity at baseline than wild type monolayers as measured by Table 1 List of CFTR mutations analyzed F508del R117H 1717-1G > A R117C G85E R334W 1898 + 1G > A Y122X A455E R347P 2184delA G178R I507del R553X 2789 + 5G > A G314E G542X R560T 3120 + 1G > A G330X G551D W1282X 3659delC R347H N1303K 621 + 1G > T K710X 406-1G > A R1162X 711 + 1G > T E60X G480C R1066C W1089X V520F A559T S1196X Q1238X S1251N S1255X 663delT 935delA 1161delC 1288insTA 2184insA 2307insA 2711delT 2869insG R709X R764X R1158X 574delA Q493X 1898 + 5G > T 3905insT I506T 3849 + 10kbC > T 712-1G > T Q98R Q552X S549N 1078delT H199Y 444delA S549R (T > G) 2143delT P205S 2043delG 1811 + 1.6kbA > G 3272-26A > G L206W 3791delC Y1092X (C > G) 3199del6 F508C 2108delA Y1092X (C > A) D1152H V520I 3667del4 394delTT 3876delA M1101K 1677delTA W1098X (TGA) 1812-1G > A 4016insT 1609delCA 3171delC response to forskolin stimulation (49.3 &#b1; 11.5 bc;A/cm2 in CFTR (+/+) vs. 40.5 &#b1; 5.3 bc;A/cm2 in CFTR (+/-), although this was not statistically significant (Figure 1A,B). Login to comment