1
|
Karri S, Cornu D, Serot C, Biri L, Hatton A, Dréanot E, Rullaud C, Pranke I, Sermet-Gaudelus I, Hinzpeter A, Bidou L, Namy O. TLN468 changes the pattern of tRNA used to read through premature termination codons in CFTR. J Cyst Fibros 2024:S1569-1993(24)00802-6. [PMID: 39098506 DOI: 10.1016/j.jcf.2024.07.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 07/22/2024] [Accepted: 07/24/2024] [Indexed: 08/06/2024]
Abstract
Nonsense mutations account for 12 % of cystic fibrosis (CF) cases. The presence of a premature termination codon (PTC) leads to gene inactivation, which can be countered by the use of drugs stimulating PTC readthrough, restoring production of the full-length protein. We recently identified a new readthrough inducer, TLN468, more efficient than gentamicin. We measured the readthrough induced by these two drugs with different cystic fibrosis transmembrane conductance regulator (CFTR) PTCs. We then determined the amino acids inserted at the S1196X, G542X, W846X and E1417X PTCs of CFTR during readthrough induced by gentamicin or TLN468. TLN468 significantly promoted the incorporation of one specific amino acid, whereas gentamicin did not greatly modify the proportions of the various amino acids incorporated relative to basal conditions. The function of the engineered missense CFTR channels corresponding to these four PTCs was assessed with and without potentiator. For the recoded CFTR, except for E1417Q and G542W, the PTC readthrough induced by TLN468 allowed the expression of CFTR variants that were correctly processed and had significant activity that was enhanced by CFTR modulators. These results suggest that it would be relevant to assess the therapeutic benefit of TLN468 PTC suppression in combination with CFTR modulators in preclinical assays.
Collapse
Affiliation(s)
- Sabrina Karri
- CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, Gif-sur-Yvette, 91198, France
| | - David Cornu
- CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, Gif-sur-Yvette, 91198, France
| | - Claudia Serot
- CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, Gif-sur-Yvette, 91198, France
| | - Lynda Biri
- CNRS, INSERM, Institut Necker Enfants Malades-INEM, Université Paris Cité, Paris, F-75015, France
| | - Aurélie Hatton
- CNRS, INSERM, Institut Necker Enfants Malades-INEM, Université Paris Cité, Paris, F-75015, France
| | - Elise Dréanot
- CNRS, INSERM, Institut Necker Enfants Malades-INEM, Université Paris Cité, Paris, F-75015, France
| | - Camille Rullaud
- CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, Gif-sur-Yvette, 91198, France
| | - Iwona Pranke
- CNRS, INSERM, Institut Necker Enfants Malades-INEM, Université Paris Cité, Paris, F-75015, France
| | - Isabelle Sermet-Gaudelus
- CNRS, INSERM, Institut Necker Enfants Malades-INEM, Université Paris Cité, Paris, F-75015, France
| | - Alexandre Hinzpeter
- CNRS, INSERM, Institut Necker Enfants Malades-INEM, Université Paris Cité, Paris, F-75015, France
| | - Laure Bidou
- CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, Gif-sur-Yvette, 91198, France; Sorbonne Université, 4 Place Jussieu, Paris, 75005, France
| | - Olivier Namy
- CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, Gif-sur-Yvette, 91198, France.
| |
Collapse
|
2
|
Diana A, Polizzi AM, De Luisi A, Pantaleo MG, Leonetti G, Simonetti S, Bukvic N, Iacoviello M, Bucci R, Gentile M, Resta N. First report of whole CFTR gene duplication in a healthy newborn carrying R74W and V855I variants on the same allele. J Cyst Fibros 2024; 23:690-692. [PMID: 38320874 DOI: 10.1016/j.jcf.2024.01.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 11/16/2023] [Accepted: 01/29/2024] [Indexed: 02/08/2024]
Abstract
Cystic fibrosis (CF) is the most common severe autosomal recessive genetic disorder among Caucasians. The improvement of genetic techniques has allowed the identification of an increasing number of genetic variants, including large rearrangements such as duplications. We report the first case of a whole CFTR gene duplication in a healthy newborn, who had normal sweat test, also carrying R74W and V855I variants on the same allele. Familial segregation analysis and the observed frequencies of all the CFTR gene variants, revealed that R74W and V855I were probably both present in a cis arrangement on the allele also containing the duplication (i.e., in a double complex allele). Since R74W is a "variant of varying clinical consequence" its arrangement in trans with one pathogenic variant may not be sufficient to cause a classic CF disease phenotype. Moreover, its duplication could even be an advantage that could compensate for the effect of the alteration.
Collapse
Affiliation(s)
- Anna Diana
- Medical Genetics Section, Department of Precision and Regenerative Medicine and Ionian Area (DiMePRe-J), University Hospital Consortium Corporation Polyclinics of Bari, 70124 Bari, Italy
| | - Angela Maria Polizzi
- Medical Genetics Section, Department of Precision and Regenerative Medicine and Ionian Area (DiMePRe-J), University Hospital Consortium Corporation Polyclinics of Bari, 70124 Bari, Italy
| | - Annunziata De Luisi
- Medical Genetics Section, Department of Precision and Regenerative Medicine and Ionian Area (DiMePRe-J), University Hospital Consortium Corporation Polyclinics of Bari, 70124 Bari, Italy
| | - Maria Giuseppina Pantaleo
- Medical Genetics Section, Department of Precision and Regenerative Medicine and Ionian Area (DiMePRe-J), University Hospital Consortium Corporation Polyclinics of Bari, 70124 Bari, Italy
| | - Giuseppina Leonetti
- Cystic Fibrosis Regional Center, University Hospital Consortium Corporation Polyclinics of Bari, 70124 Bari, Italy
| | - Simonetta Simonetti
- Clinical Patology and Neonatal Screening, Hospital "Giovanni XXIII", University Hospital Consortium Corporation Polyclinics of Bari, Bari, Italy
| | - Nenad Bukvic
- Medical Genetics Section, Department of Precision and Regenerative Medicine and Ionian Area (DiMePRe-J), University Hospital Consortium Corporation Polyclinics of Bari, 70124 Bari, Italy
| | - Matteo Iacoviello
- Medical Genetics Section, Department of Precision and Regenerative Medicine and Ionian Area (DiMePRe-J), University Hospital Consortium Corporation Polyclinics of Bari, 70124 Bari, Italy
| | - Roberta Bucci
- Medical Genetics Section, Department of Precision and Regenerative Medicine and Ionian Area (DiMePRe-J), University Hospital Consortium Corporation Polyclinics of Bari, 70124 Bari, Italy; Medical Genetics Unit, Department of Human Reproductive Medicine, ASL Bari, Bari, Italy
| | - Mattia Gentile
- Medical Genetics Unit, Department of Human Reproductive Medicine, ASL Bari, Bari, Italy
| | - Nicoletta Resta
- Medical Genetics Section, Department of Precision and Regenerative Medicine and Ionian Area (DiMePRe-J), University Hospital Consortium Corporation Polyclinics of Bari, 70124 Bari, Italy.
| |
Collapse
|
3
|
Krasnova M, Efremova A, Bukhonin A, Zhekaite E, Bukharova T, Melyanovskaya Y, Goldshtein D, Kondratyeva E. The Effect of Complex Alleles of the CFTR Gene on the Clinical Manifestations of Cystic Fibrosis and the Effectiveness of Targeted Therapy. Int J Mol Sci 2023; 25:114. [PMID: 38203285 PMCID: PMC10779438 DOI: 10.3390/ijms25010114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 12/11/2023] [Accepted: 12/14/2023] [Indexed: 01/12/2024] Open
Abstract
The authors of this article analyzed the available literature with the results of studying the prevalence of complex alleles of the CFTR gene among patients with cystic fibrosis, and their pathogenicity and influence on targeted therapy with CFTR modulators. Cystic fibrosis (CF) is a multisystemic autosomal recessive disease caused by a defect in the expression of the CFTR protein, and more than 2000 genetic variants are known. Clinically significant variants are divided into seven classes. Information about the frequency of complex alleles appears in a number of registers, along with the traditional presentation of data on genetic variants. Complex alleles (those with the presence of more than two nucleotide variants on one allele) can complicate the diagnosis of the disease, and change the clinical manifestations of cystic fibrosis and the response to treatment, since each variant in the complex allele can contribute to the functional activity of the CFTR protein, changing it both in terms of increasing and decreasing function. The role of complex alleles is often underestimated, and their frequency has not been studied. At the moment, characteristic frequently encountered complex alleles have been found for several populations of patients with cystic fibrosis, but the prevalence and pathogenicity of newly detected complex alleles require additional research. In this review, more than 35 complex alleles of the CFTR gene from existing research studies were analyzed, and an analysis of their influence on the manifestations of the disease and the effectiveness of CFTR modulators was also described.
Collapse
Affiliation(s)
| | - Anna Efremova
- Research Centre for Medical Genetics, Moscow 115522, Russia; (M.K.); (A.B.); (E.Z.); (T.B.); (Y.M.); (D.G.); (E.K.)
| | | | | | | | | | | | | |
Collapse
|
4
|
Kleinfelder K, Somenza E, Farinazzo A, Conti J, Lotti V, Latorre RV, Rodella L, Massella A, Tomba F, Bertini M, Sorio C, Melotti P. CFTR Modulators Rescue the Activity of CFTR in Colonoids Expressing the Complex Allele p.[R74W;V201M;D1270N]/dele22_24. Int J Mol Sci 2023; 24:ijms24065199. [PMID: 36982273 PMCID: PMC10048957 DOI: 10.3390/ijms24065199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/24/2023] [Accepted: 03/02/2023] [Indexed: 03/11/2023] Open
Abstract
An Italian, 46-year-old female patient carrying the complex allele p.[R74W;V201M;D1270N] in trans with CFTR dele22_24 was diagnosed at the Cystic Fibrosis (CF) Center of Verona as being affected by CF-pancreatic sufficient (CF-PS) in 2021. The variant V201M has unknown significance, while both of the other variants of this complex allele have variable clinical consequences, according to the CFTR2 database, with reported clinical benefits for treatment with ivacaftor + tezacaftor and ivacaftor + tezacaftor + elexacaftor in patients carrying the R74W-D1270N complex allele, which are currently approved (in USA, not yet in Italy). She was previously followed up by pneumologists in northern Italy because of frequent bronchitis, hemoptysis, recurrent rhinitis, Pseudomonas aeruginosa lung colonization, bronchiectasis/atelectasis, bronchial arterial embolization and moderately compromised lung function (FEV1: 62%). Following a sweat test with borderline results, she was referred to the Verona CF Center where she presented abnormal values in both optical beta-adrenergic sweat tests and intestinal current measurement (ICM). These results were consistent with a diagnosis of CF. CFTR function analyses were also performed in vitro by forskolin-induced swelling (FIS) assay and short-circuit currents (Isc) in the monolayers of the rectal organoids. Both of these assays showed significantly increased CFTR activity following treatment with the CFTR modulators. Western-blot analysis revealed increased fully glycosylated CFTR protein after treatment with correctors, in line with the functional analysis. Interestingly, tezacaftor, together with elexacaftor, rescued the total organoid area under steady-state conditions, even in the absence of the CFTR agonist forskolin. In conclusion, in ex vivo and in vitro assays, we measured a residual function that was significantly enhanced by in vitro incubation with CFTR modulators, especially by ivacaftor + tezacaftor + elexacaftor, suggesting this combination as a potentially optimal treatment for this case.
Collapse
Affiliation(s)
- Karina Kleinfelder
- Department of Medicine, Division of General Pathology, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy
| | - Elena Somenza
- Department of Medicine, Division of General Pathology, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy
| | - Alessia Farinazzo
- Department of Medicine, Division of General Pathology, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy
| | - Jessica Conti
- Department of Medicine, Division of General Pathology, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy
| | - Virginia Lotti
- Department of Medicine, Division of General Pathology, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy
| | - Roberta Valeria Latorre
- Department of Medicine, Division of General Pathology, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy
| | - Luca Rodella
- Endoscopic Surgery Unit, Azienda Ospedaliera Universitaria Integrata Verona, 37126 Verona, Italy
| | - Arianna Massella
- Endoscopic Surgery Unit, Azienda Ospedaliera Universitaria Integrata Verona, 37126 Verona, Italy
| | - Francesco Tomba
- Endoscopic Surgery Unit, Azienda Ospedaliera Universitaria Integrata Verona, 37126 Verona, Italy
| | - Marina Bertini
- Cystic Fibrosis Centre, Azienda Ospedaliera Universitaria Integrata Verona, Piazzale Stefani, 1, 37126 Verona, Italy
| | - Claudio Sorio
- Department of Medicine, Division of General Pathology, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy
- Correspondence: (C.S.); (P.M.)
| | - Paola Melotti
- Cystic Fibrosis Centre, Azienda Ospedaliera Universitaria Integrata Verona, Piazzale Stefani, 1, 37126 Verona, Italy
- Correspondence: (C.S.); (P.M.)
| |
Collapse
|
5
|
Baatallah N, Elbahnsi A, Chevalier B, Castanier S, Mornon JP, Pranke I, Edelman A, Sermet-Gaudelus I, Callebaut I, Hinzpeter A. Acting on the CFTR Membrane-Spanning Domains Interface Rescues Some Misfolded Mutants. Int J Mol Sci 2022; 23:ijms232416225. [PMID: 36555865 PMCID: PMC9780841 DOI: 10.3390/ijms232416225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 12/09/2022] [Accepted: 12/13/2022] [Indexed: 12/24/2022] Open
Abstract
ABC transporters are large membrane proteins sharing a complex architecture, which comprises two nucleotide-binding domains (NBDs) and two membrane-spanning domains (MSDs). These domains are susceptible to mutations affecting their folding and assembly. In the CFTR (ABCC7) protein, a groove has been highlighted in the MSD1 at the level of the membrane inner leaflet, containing both multiple mutations affecting folding and a binding site for pharmaco-chaperones that stabilize this region. This groove is also present in ABCB proteins, however it is covered by a short elbow helix, while in ABCC proteins it remains unprotected, due to a lower position of the elbow helix in the presence of the ABCC-specific lasso motif. Here, we identified a MSD1 second-site mutation located in the vicinity of the CFTR MSD1 groove that partially rescued the folding defect of cystic fibrosis causing mutations located within MSD1, while having no effect on the most frequent mutation, F508del, located within NBD1. A model of the mutated protein 3D structure suggests additional interaction between MSD1 and MSD2, strengthening the assembly at the level of the MSD intracellular loops. Altogether, these results provide insightful information in understanding key features of the folding and function of the CFTR protein in particular, and more generally, of type IV ABC transporters.
Collapse
Affiliation(s)
- Nesrine Baatallah
- INSERM, U1151, Institut Necker Enfants Malades (INEM), Faculté de Médecine, Université Paris Cité, CNRS, UMR 8253, 75015 Paris, France
| | - Ahmad Elbahnsi
- Sorbonne Université, Muséum National d’Histoire Naturelle, UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, 75005 Paris, France
| | - Benoit Chevalier
- INSERM, U1151, Institut Necker Enfants Malades (INEM), Faculté de Médecine, Université Paris Cité, CNRS, UMR 8253, 75015 Paris, France
| | - Solène Castanier
- INSERM, U1151, Institut Necker Enfants Malades (INEM), Faculté de Médecine, Université Paris Cité, CNRS, UMR 8253, 75015 Paris, France
| | - Jean-Paul Mornon
- Sorbonne Université, Muséum National d’Histoire Naturelle, UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, 75005 Paris, France
| | - Iwona Pranke
- INSERM, U1151, Institut Necker Enfants Malades (INEM), Faculté de Médecine, Université Paris Cité, CNRS, UMR 8253, 75015 Paris, France
| | - Aleksander Edelman
- INSERM, U1151, Institut Necker Enfants Malades (INEM), Faculté de Médecine, Université Paris Cité, CNRS, UMR 8253, 75015 Paris, France
| | - Isabelle Sermet-Gaudelus
- INSERM, U1151, Institut Necker Enfants Malades (INEM), Faculté de Médecine, Université Paris Cité, CNRS, UMR 8253, 75015 Paris, France
| | - Isabelle Callebaut
- Sorbonne Université, Muséum National d’Histoire Naturelle, UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, 75005 Paris, France
- Correspondence: (I.C.); (A.H.)
| | - Alexandre Hinzpeter
- INSERM, U1151, Institut Necker Enfants Malades (INEM), Faculté de Médecine, Université Paris Cité, CNRS, UMR 8253, 75015 Paris, France
- Correspondence: (I.C.); (A.H.)
| |
Collapse
|
6
|
Hatton A, Bergougnoux A, Zybert K, Chevalier B, Mesbahi M, Altéri JP, Walicka-Serzysko K, Postek M, Taulan-Cadars M, Edelman A, Hinzpeter A, Claustres M, Girodon E, Raynal C, Sermet-Gaudelus I, Sands D. Reclassifying inconclusive diagnosis after newborn screening for cystic fibrosis. Moving forward. J Cyst Fibros 2021; 21:448-455. [PMID: 34949556 DOI: 10.1016/j.jcf.2021.12.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 12/07/2021] [Accepted: 12/08/2021] [Indexed: 10/19/2022]
Abstract
BACKGROUND Newborn screening for Cystic Fibrosis (CF) is associated with situations where the diagnosis of CF or CFTR related disorders (CFTR-RD) cannot be clearly ruled out. MATERIALS/PATIENTS AND METHODS We report a case series of 23 children with unconclusive diagnosis after newborn screening for CF and a mean follow-up of 7.7 years (4-13). Comprehensive investigations including whole CFTR gene sequencing, in vivo intestinal current measurement (ICM), nasal potential difference (NPD), and in vitro functional studies of variants of unknown significance, helped to reclassify the patients. RESULTS Extensive genetic testing identified, in trans with a CF causing mutation, variants with varying clinical consequences and 3 variants of unknown significance (VUS). Eighteen deep intronic variants were identified by deep resequencing of the whole CFTR gene in 13 patients and were finally considered as non-pathogenic. All patients had normal CFTR dependent chloride transport in ICM. NPD differentiated 3 different profiles: CF-like tracings qualifying the patients as CF, such as F508del/D1152H patients; normal responses, suggesting an extremely low likelihood of developing a CFTR-RD such as F508del/TG11T5 patients; partial CFTR dysfunction above 20% of the normal, highlighting a remaining risk of developing CFTR-RD such as F508del/F1052V patients. The 3 VUS were reclassified as variant with defective maturation (D537N), defective expression (T582I) or with no clinical consequence (M952T). CONCLUSION This study demonstrates the usefulness of combining genetic and functional investigations to assess the possibility of evolving to CF or CFTR-RD in babies with inconclusive diagnosis at neonatal screening.
Collapse
Affiliation(s)
- Aurelie Hatton
- INSERM U1151, Institut Necker Enfants Malades, Université de Paris, 149 rue de Sévres, Paris 75015, France; Université de Paris, Paris, France
| | - Anne Bergougnoux
- PhyMedExp, INSERM U1046, CNRS UMR 9214, University of Montpellier, Montpellier, France; CHU de Montpellier, Laboratoire de Génétique Moléculaire, Montpellier, France
| | - Katarzyna Zybert
- Cystic Fibrosis Department, Institute of Mother and Child, Warsaw, Poland
| | - Benoit Chevalier
- INSERM U1151, Institut Necker Enfants Malades, Université de Paris, 149 rue de Sévres, Paris 75015, France; Université de Paris, Paris, France
| | - Myriam Mesbahi
- INSERM U1151, Institut Necker Enfants Malades, Université de Paris, 149 rue de Sévres, Paris 75015, France; Université de Paris, Paris, France
| | - Jean Pierre Altéri
- CHU de Montpellier, Laboratoire de Génétique Moléculaire, Montpellier, France
| | | | - Magdalena Postek
- Cystic Fibrosis Department, Institute of Mother and Child, Warsaw, Poland
| | - Magali Taulan-Cadars
- PhyMedExp, INSERM U1046, CNRS UMR 9214, University of Montpellier, Montpellier, France; Université de Montpellier, Montpellier, France
| | - Aleksander Edelman
- INSERM U1151, Institut Necker Enfants Malades, Université de Paris, 149 rue de Sévres, Paris 75015, France; Université de Paris, Paris, France
| | - Alexandre Hinzpeter
- INSERM U1151, Institut Necker Enfants Malades, Université de Paris, 149 rue de Sévres, Paris 75015, France; Université de Paris, Paris, France
| | | | - Emmanuelle Girodon
- INSERM U1151, Institut Necker Enfants Malades, Université de Paris, 149 rue de Sévres, Paris 75015, France; Laboratoire de Génétique et Biologie Moléculaires, Hôpital Cochin, APHP Centre, Université de Paris, Paris, France
| | - Caroline Raynal
- PhyMedExp, INSERM U1046, CNRS UMR 9214, University of Montpellier, Montpellier, France; CHU de Montpellier, Laboratoire de Génétique Moléculaire, Montpellier, France
| | - Isabelle Sermet-Gaudelus
- INSERM U1151, Institut Necker Enfants Malades, Université de Paris, 149 rue de Sévres, Paris 75015, France; Université de Paris, Paris, France; Centre de Référence Maladies Rares, Mucoviscidose et maladies apparentées, Hôpital Necker Enfants Malades, Paris, France; European Reference Network-Lung, France.
| | - Dorota Sands
- Cystic Fibrosis Department, Institute of Mother and Child, Warsaw, Poland
| |
Collapse
|
7
|
Baatallah N, Elbahnsi A, Mornon JP, Chevalier B, Pranke I, Servel N, Zelli R, Décout JL, Edelman A, Sermet-Gaudelus I, Callebaut I, Hinzpeter A. Pharmacological chaperones improve intra-domain stability and inter-domain assembly via distinct binding sites to rescue misfolded CFTR. Cell Mol Life Sci 2021; 78:7813-7829. [PMID: 34714360 PMCID: PMC11071985 DOI: 10.1007/s00018-021-03994-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 10/11/2021] [Accepted: 10/15/2021] [Indexed: 12/14/2022]
Abstract
Protein misfolding is involved in a large number of diseases, among which cystic fibrosis. Complex intra- and inter-domain folding defects associated with mutations in the cystic fibrosis transmembrane regulator (CFTR) gene, among which p.Phe508del (F508del), have recently become a therapeutical target. Clinically approved correctors such as VX-809, VX-661, and VX-445, rescue mutant protein. However, their binding sites and mechanisms of action are still incompletely understood. Blind docking onto the 3D structures of both the first membrane-spanning domain (MSD1) and the first nucleotide-binding domain (NBD1), followed by molecular dynamics simulations, revealed the presence of two potential VX-809 corrector binding sites which, when mutated, abrogated rescue. Network of amino acids in the lasso helix 2 and the intracellular loops ICL1 and ICL4 allosterically coupled MSD1 and NBD1. Corrector VX-445 also occupied two potential binding sites on MSD1 and NBD1, the latter being shared with VX-809. Binding of both correctors on MSD1 enhanced the allostery between MSD1 and NBD1, hence the increased efficacy of the corrector combination. These correctors improve both intra-domain folding by stabilizing fragile protein-lipid interfaces and inter-domain assembly via distant allosteric couplings. These results provide novel mechanistic insights into the rescue of misfolded proteins by small molecules.
Collapse
Affiliation(s)
- Nesrine Baatallah
- INSERM, U1151, Institut Necker Enfants Malades, INEM, Paris, France
- CNRS UMR 8253 - Faculté de Médecine, Université de Paris, Paris, France
| | - Ahmad Elbahnsi
- Sorbonne Université, Muséum National d'Histoire Naturelle, UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, 75005, Paris, France
- Department of Applied Physics of Science for Life Laboratory, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Jean-Paul Mornon
- Sorbonne Université, Muséum National d'Histoire Naturelle, UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, 75005, Paris, France
| | - Benoit Chevalier
- INSERM, U1151, Institut Necker Enfants Malades, INEM, Paris, France
- CNRS UMR 8253 - Faculté de Médecine, Université de Paris, Paris, France
| | - Iwona Pranke
- INSERM, U1151, Institut Necker Enfants Malades, INEM, Paris, France
- CNRS UMR 8253 - Faculté de Médecine, Université de Paris, Paris, France
| | - Nathalie Servel
- INSERM, U1151, Institut Necker Enfants Malades, INEM, Paris, France
- CNRS UMR 8253 - Faculté de Médecine, Université de Paris, Paris, France
| | - Renaud Zelli
- Univ. Grenoble Alpes, CNRS, DPM, 38000, Grenoble, France
| | | | - Aleksander Edelman
- INSERM, U1151, Institut Necker Enfants Malades, INEM, Paris, France
- CNRS UMR 8253 - Faculté de Médecine, Université de Paris, Paris, France
| | - Isabelle Sermet-Gaudelus
- INSERM, U1151, Institut Necker Enfants Malades, INEM, Paris, France
- CNRS UMR 8253 - Faculté de Médecine, Université de Paris, Paris, France
| | - Isabelle Callebaut
- Sorbonne Université, Muséum National d'Histoire Naturelle, UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, 75005, Paris, France.
| | - Alexandre Hinzpeter
- INSERM, U1151, Institut Necker Enfants Malades, INEM, Paris, France.
- CNRS UMR 8253 - Faculté de Médecine, Université de Paris, Paris, France.
| |
Collapse
|
8
|
Martin N, Bergougnoux A, Baatallah N, Chevalier B, Varilh J, Baux D, Costes B, Fanen P, Raynal C, Sermet-Gaudelus I, Girodon E, Taulan-Cadars M, Hinzpeter A. Exon identity influences splicing induced by exonic variants and in silico prediction efficacy. J Cyst Fibros 2020; 20:464-472. [PMID: 33341408 DOI: 10.1016/j.jcf.2020.12.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 09/22/2020] [Accepted: 12/03/2020] [Indexed: 01/09/2023]
Abstract
BACKGROUND Minigenes and in silico prediction tools are commonly used to assess the impact on splicing of CFTR variants. Exon skipping is often neglected though it could impact the efficacy of targeted therapies. The aim of the study was to identify exon skipping associated with CFTR variants and to evaluate in silico predictions of seven freely available software. METHODS CFTR basal exon skipping was evaluated on endogenous mRNA extracted from non-CF nasal cells and on two CFTR minigene banks. In silico tools and minigene systems were used to evaluate the impact of CFTR exonic variants on exon skipping. RESULTS Data showed that out of 65 CFTR variants tested, 26 enhanced exon skipping and that in silico prediction efficacy was of 50%-66%. Some in silico tools presented predictions with a bias towards the occurrence of splicing events while others presented a bias towards the absence of splicing events (non-detection including true negatives and false negatives). Classification of exons depending on their basal exon skipping level increased prediction rates up to 80%. CONCLUSION This study indicates that taking basal exon skipping into account could orientate the choice of the in silico tools to improve prediction rates. It also highlights the need to validate effects using in vitro assays or mRNA studies in patients. Eventually, it shows that variant-guided therapy should also target exon skipping associated with variants.
Collapse
Affiliation(s)
- Natacha Martin
- INSERM, U955, Institut de Recherche Henri Mondor, IMRB, Créteil, France
| | - Anne Bergougnoux
- CHU de Montpellier, Laboratoire de Génétique Moléculaire, Montpellier, France; Université de Montpellier, Laboratoire de Génétique de Maladies Rares, EA7402 Montpellier, France
| | - Nesrine Baatallah
- INSERM U1151, Institut Necker Enfants Malades, INEM, Paris, France; Université Paris Descartes, Paris, France
| | - Benoit Chevalier
- INSERM U1151, Institut Necker Enfants Malades, INEM, Paris, France; Université Paris Descartes, Paris, France
| | - Jessica Varilh
- Université de Montpellier, Laboratoire de Génétique de Maladies Rares, EA7402 Montpellier, France
| | - David Baux
- CHU de Montpellier, Laboratoire de Génétique Moléculaire, Montpellier, France; Université de Montpellier, Laboratoire de Génétique de Maladies Rares, EA7402 Montpellier, France
| | - Bruno Costes
- INSERM, U955, Institut de Recherche Henri Mondor, IMRB, Créteil, France
| | - Pascale Fanen
- INSERM, U955, Institut de Recherche Henri Mondor, IMRB, Créteil, France; Department of Genetics, GH Henri Mondor, APHP, Créteil, France
| | - Caroline Raynal
- CHU de Montpellier, Laboratoire de Génétique Moléculaire, Montpellier, France; Université de Montpellier, Laboratoire de Génétique de Maladies Rares, EA7402 Montpellier, France
| | - Isabelle Sermet-Gaudelus
- INSERM U1151, Institut Necker Enfants Malades, INEM, Paris, France; Université Paris Descartes, Paris, France
| | - Emmanuelle Girodon
- INSERM U1151, Institut Necker Enfants Malades, INEM, Paris, France; Laboratoire de Génétique et Biologie Moléculaires, Hôpital Cochin, APHP Centre-Université de Paris, Paris, France
| | - Magali Taulan-Cadars
- Université de Montpellier, Laboratoire de Génétique de Maladies Rares, EA7402 Montpellier, France.
| | - Alexandre Hinzpeter
- INSERM U1151, Institut Necker Enfants Malades, INEM, Paris, France; Université Paris Descartes, Paris, France.
| |
Collapse
|
9
|
Degrugillier F, Aissat A, Prulière-Escabasse V, Bizard L, Simonneau B, Decrouy X, Jiang C, Rotin D, Fanen P, Simon S. Phosphorylation of the Chaperone-Like HspB5 Rescues Trafficking and Function of F508del-CFTR. Int J Mol Sci 2020; 21:ijms21144844. [PMID: 32650630 PMCID: PMC7402320 DOI: 10.3390/ijms21144844] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 07/02/2020] [Accepted: 07/04/2020] [Indexed: 02/07/2023] Open
Abstract
Cystic Fibrosis is a lethal monogenic autosomal recessive disease linked to mutations in Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein. The most frequent mutation is the deletion of phenylalanine at position 508 of the protein. This F508del-CFTR mutation leads to misfolded protein that is detected by the quality control machinery within the endoplasmic reticulum and targeted for destruction by the proteasome. Modulating quality control proteins as molecular chaperones is a promising strategy for attenuating the degradation and stabilizing the mutant CFTR at the plasma membrane. Among the molecular chaperones, the small heat shock protein HspB1 and HspB4 were shown to promote degradation of F508del-CFTR. Here, we investigated the impact of HspB5 expression and phosphorylation on transport to the plasma membrane, function and stability of F508del-CFTR. We show that a phosphomimetic form of HspB5 increases the transport to the plasma membrane, function and stability of F508del-CFTR. These activities are further enhanced in presence of therapeutic drugs currently used for the treatment of cystic fibrosis (VX-770/Ivacaftor, VX-770+VX-809/Orkambi). Overall, this study highlights the beneficial effects of a phosphorylated form of HspB5 on F508del-CFTR rescue and its therapeutic potential in cystic fibrosis.
Collapse
Affiliation(s)
- Fanny Degrugillier
- Univ Paris Est Creteil, INSERM, IMRB, F-94010 Creteil, France; (F.D.); (A.A.); (V.P.-E.); (L.B.); (B.S.); (X.D.); (P.F.)
| | - Abdel Aissat
- Univ Paris Est Creteil, INSERM, IMRB, F-94010 Creteil, France; (F.D.); (A.A.); (V.P.-E.); (L.B.); (B.S.); (X.D.); (P.F.)
- AP-HP, Hôpital Henri Mondor, Département de Génétique, F-94010 Creteil, France
| | - Virginie Prulière-Escabasse
- Univ Paris Est Creteil, INSERM, IMRB, F-94010 Creteil, France; (F.D.); (A.A.); (V.P.-E.); (L.B.); (B.S.); (X.D.); (P.F.)
- Centre Hospitalier Intercommunal de Creteil, Service d’ORL et de Chirurgie Cervico-Faciale, F-94010 Creteil, France
| | - Lucie Bizard
- Univ Paris Est Creteil, INSERM, IMRB, F-94010 Creteil, France; (F.D.); (A.A.); (V.P.-E.); (L.B.); (B.S.); (X.D.); (P.F.)
| | - Benjamin Simonneau
- Univ Paris Est Creteil, INSERM, IMRB, F-94010 Creteil, France; (F.D.); (A.A.); (V.P.-E.); (L.B.); (B.S.); (X.D.); (P.F.)
| | - Xavier Decrouy
- Univ Paris Est Creteil, INSERM, IMRB, F-94010 Creteil, France; (F.D.); (A.A.); (V.P.-E.); (L.B.); (B.S.); (X.D.); (P.F.)
| | - Chong Jiang
- The Hospital for Sick Children and the University of Toronto, Toronto, ON M5G 0A4, Canada; (C.J.); (D.R.)
| | - Daniela Rotin
- The Hospital for Sick Children and the University of Toronto, Toronto, ON M5G 0A4, Canada; (C.J.); (D.R.)
| | - Pascale Fanen
- Univ Paris Est Creteil, INSERM, IMRB, F-94010 Creteil, France; (F.D.); (A.A.); (V.P.-E.); (L.B.); (B.S.); (X.D.); (P.F.)
- AP-HP, Hôpital Henri Mondor, Département de Génétique, F-94010 Creteil, France
| | - Stéphanie Simon
- Univ Paris Est Creteil, INSERM, IMRB, F-94010 Creteil, France; (F.D.); (A.A.); (V.P.-E.); (L.B.); (B.S.); (X.D.); (P.F.)
- Correspondence: ; Tel.: +33-1-49-81-68-55
| |
Collapse
|
10
|
Chevalier B, Hinzpeter A. The influence of CFTR complex alleles on precision therapy of cystic fibrosis. J Cyst Fibros 2019; 19 Suppl 1:S15-S18. [PMID: 31883651 DOI: 10.1016/j.jcf.2019.12.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 11/14/2019] [Accepted: 12/14/2019] [Indexed: 10/25/2022]
Abstract
CFTR is an extensively studied gene and multiple sequence variants have been identified, many of which still need to be defined as neutral or disease causing. Complex alleles are defined when at least two variants are identified on the same allele. Each pathogenic variant can affect distinct steps of the CFTR biogenesis. As CFTR modulators are being developed to alleviate specific defects, pathogenic variants need to be characterized to propose adequate treatments. Conversely, cis-variants can affect treatment response when defects are additive or if they alter the binding or efficacy of the modulator. Hence, complex alleles increase the complexity of CFTR variant classification and need to be assigned as neutral, disease causing or modulating treatment efficacy. This review was based on a symposium session presented at the 16th ECFS Basic Science Conference, Dubrovnik, Croatia, 27 to 30 March, 2019.
Collapse
Affiliation(s)
- Benoit Chevalier
- INSERM U1151, Institut Necker Enfants Malades, Paris, France; Université Paris Descartes, Paris, France.
| | - Alexandre Hinzpeter
- INSERM U1151, Institut Necker Enfants Malades, Paris, France; Université Paris Descartes, Paris, France.
| |
Collapse
|
11
|
Schucht S, Minso R, Lex C, Reiss J, Stanke F, Tamm S, van Barneveld A, Tümmler B. Functional analysis of the p.[Arg74Trp;Val201Met;Asp1270Asn]/p.Phe508del CFTR mutation genotype in human native colon. Mol Genet Genomic Med 2019; 7:e00526. [PMID: 30600599 PMCID: PMC6393651 DOI: 10.1002/mgg3.526] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 11/07/2018] [Indexed: 11/20/2022] Open
Abstract
Background The impact of complex alleles on CFTR processing and function has yet not been investigated in native human tissue. Methods Intestinal current measurements (ICM) followed by CFTR immunoblot were performed on rectal biopsies taken from two siblings who are compound heterozygous for the CFTR mutations p.Phe508del and the complex allele p.[Arg74Trp;Val201Met;Asp1270Asn]. Results Normal and subnormal chloride secretory responses in the ICM were associated with normal and fourfold reduced amounts of the mature glycoform band C CFTR, respectively, consistent with the unequal clinical phenotype of the siblings. Conclusion The combined use of bioassay and protein analysis is particularly meaningful to resolve the CFTR phenotype of “indeterminate” borderline CFTR genotypes on a case‐to‐case basis.
Collapse
Affiliation(s)
- Sylvia Schucht
- Pediatric Pulmonary and Allergology Outpatient Clinic, Paediatric Cardiology and Intensive Care Medicine, Universitätsmedizin Göttingen, Göttingen, Germany
| | - Rebecca Minso
- Clinical Research Group 'Molecular Pathology of Cystic Fibrosis', Clinic for Paediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany
| | - Christiane Lex
- Pediatric Pulmonary and Allergology Outpatient Clinic, Paediatric Cardiology and Intensive Care Medicine, Universitätsmedizin Göttingen, Göttingen, Germany
| | - Jochen Reiss
- Institute for Human Genetics, Universitätsmedizin Göttingen, Göttingen, Germany
| | - Frauke Stanke
- Clinical Research Group 'Molecular Pathology of Cystic Fibrosis', Clinic for Paediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany.,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research, Hannover, Germany
| | - Stephanie Tamm
- Clinical Research Group 'Molecular Pathology of Cystic Fibrosis', Clinic for Paediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany
| | - Andrea van Barneveld
- Clinical Research Group 'Molecular Pathology of Cystic Fibrosis', Clinic for Paediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany
| | - Burkhard Tümmler
- Clinical Research Group 'Molecular Pathology of Cystic Fibrosis', Clinic for Paediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany.,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research, Hannover, Germany
| |
Collapse
|
12
|
Baatallah N, Bitam S, Martin N, Servel N, Costes B, Mekki C, Chevalier B, Pranke I, Simonin J, Girodon E, Hoffmann B, Mornon JP, Callebaut I, Sermet-Gaudelus I, Fanen P, Edelman A, Hinzpeter A. Cis variants identified in F508del complex alleles modulate CFTR channel rescue by small molecules. Hum Mutat 2018; 39:506-514. [PMID: 29271547 DOI: 10.1002/humu.23389] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 12/13/2017] [Accepted: 12/15/2017] [Indexed: 12/17/2022]
Abstract
Molecules correcting the trafficking (correctors) and gating defects (potentiators) of the cystic fibrosis causing mutation c.1521_1523delCTT (p.Phe508del) begin to be a useful treatment for CF patients bearing p.Phe508del. This mutation has been identified in different genetic contexts, alone or in combination with variants in cis. Until now, 21 exonic variants in cis of p.Phe508del have been identified, albeit at a low frequency. The aim of this study was to evaluate their impact on the efficacy of CFTR-directed corrector/potentiator therapy (Orkambi). The analysis by minigene showed that two out of 15 cis variants tested increased exon skipping (c.609C > T and c.2770G > A). Four cis variants were studied functionally in the absence of p.Phe508del, one of which was found to be deleterious for protein maturation c.1399C > T (p.Leu467Phe). In the presence of p.Phe508del, this variant was the only to prevent the response to Orkambi treatment. This study showed that some patients carrying p.Phe508del complex alleles are predicted to poorly respond to corrector/potentiator treatments. Our results underline the importance to validate treatment efficacy in the context of complex alleles.
Collapse
Affiliation(s)
- Nesrine Baatallah
- INSERM U1151, Institut Necker Enfants Malades, INEM, Paris, France.,Université Paris Descartes, Paris, France
| | - Sara Bitam
- INSERM U1151, Institut Necker Enfants Malades, INEM, Paris, France.,Université Paris Descartes, Paris, France
| | - Natacha Martin
- INSERM, U955, Institut de Recherche Henri Mondor, IMRB, Créteil, France
| | - Nathalie Servel
- INSERM U1151, Institut Necker Enfants Malades, INEM, Paris, France.,Université Paris Descartes, Paris, France
| | - Bruno Costes
- INSERM, U955, Institut de Recherche Henri Mondor, IMRB, Créteil, France.,Université Paris-Est, Créteil, France
| | - Chadia Mekki
- Department of Genetics, GH Henri Mondor, APHP, Créteil, France
| | - Benoit Chevalier
- INSERM U1151, Institut Necker Enfants Malades, INEM, Paris, France.,Université Paris Descartes, Paris, France
| | - Iwona Pranke
- INSERM U1151, Institut Necker Enfants Malades, INEM, Paris, France.,Université Paris Descartes, Paris, France
| | - Juliette Simonin
- INSERM U1151, Institut Necker Enfants Malades, INEM, Paris, France.,Université Paris Descartes, Paris, France
| | - Emmanuelle Girodon
- INSERM U1151, Institut Necker Enfants Malades, INEM, Paris, France.,Laboratoire de Génétique et Biologie Moléculaires, HUPC Hôpital Cochin, AP-HP, Paris, France
| | - Brice Hoffmann
- CNRS UMR7590, Sorbonne Universités, Université Pierre et Marie Curie-Paris6-MNHN-IRD-IUC, Paris, France
| | - Jean-Paul Mornon
- CNRS UMR7590, Sorbonne Universités, Université Pierre et Marie Curie-Paris6-MNHN-IRD-IUC, Paris, France
| | - Isabelle Callebaut
- CNRS UMR7590, Sorbonne Universités, Université Pierre et Marie Curie-Paris6-MNHN-IRD-IUC, Paris, France
| | - Isabelle Sermet-Gaudelus
- INSERM U1151, Institut Necker Enfants Malades, INEM, Paris, France.,Université Paris Descartes, Paris, France
| | - Pascale Fanen
- INSERM, U955, Institut de Recherche Henri Mondor, IMRB, Créteil, France.,Université Paris-Est, Créteil, France.,Department of Genetics, GH Henri Mondor, APHP, Créteil, France
| | - Aleksander Edelman
- INSERM U1151, Institut Necker Enfants Malades, INEM, Paris, France.,Université Paris Descartes, Paris, France
| | - Alexandre Hinzpeter
- INSERM U1151, Institut Necker Enfants Malades, INEM, Paris, France.,Université Paris Descartes, Paris, France
| |
Collapse
|
13
|
Pranke I, Bidou L, Martin N, Blanchet S, Hatton A, Karri S, Cornu D, Costes B, Chevalier B, Tondelier D, Girodon E, Coupet M, Edelman A, Fanen P, Namy O, Sermet-Gaudelus I, Hinzpeter A. Factors influencing readthrough therapy for frequent cystic fibrosis premature termination codons. ERJ Open Res 2018; 4:00080-2017. [PMID: 29497617 PMCID: PMC5827411 DOI: 10.1183/23120541.00080-2017] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 12/22/2017] [Indexed: 01/17/2023] Open
Abstract
Premature termination codons (PTCs) are generally associated with severe forms of genetic diseases. Readthrough of in-frame PTCs using small molecules is a promising therapeutic approach. Nonetheless, the outcome of preclinical studies has been low and variable. Treatment efficacy depends on: 1) the level of drug-induced readthrough, 2) the amount of target transcripts, and 3) the activity of the recoded protein. The aim of the present study was to identify, in the cystic fibrosis transmembrane conductance regulator (CFTR) model, recoded channels from readthrough therapy that may be enhanced using CFTR modulators. First, drug-induced readthrough of 15 PTCs was measured using a dual reporter system under basal conditions and in response to gentamicin and negamycin. Secondly, exon skipping associated with these PTCs was evaluated with a minigene system. Finally, incorporated amino acids were identified by mass spectrometry and the function of the predicted recoded CFTR channels corresponding to these 15 PTCs was measured. Nonfunctional channels were subjected to CFTR-directed ivacaftor-lumacaftor treatments. The results demonstrated that CFTR modulators increased activity of recoded channels, which could also be confirmed in cells derived from a patient. In conclusion, this work will provide a framework to adapt treatments to the patient's genotype by identifying the most efficient molecule for each PTC and the recoded channels needing co-therapies to rescue channel function.
Collapse
Affiliation(s)
- Iwona Pranke
- INSERM, U1151, Institut Necker Enfants Malades, INEM, Paris, France
- Université Paris Descartes, Paris, France
- Both authors contributed equally
| | - Laure Bidou
- Sorbonne Universités, Université Pierre et Marie Curie, UPMC, Paris, France
- Institute for Integrative Biology of the Cell, I2BC, CEA, CNRS, Université Paris Sud, Université Paris-Saclay, Gif-sur-Yvette, France
- Both authors contributed equally
| | - Natacha Martin
- INSERM, U955, Institut de Recherche Henri Mondor, Créteil, France
| | - Sandra Blanchet
- Institute for Integrative Biology of the Cell, I2BC, CEA, CNRS, Université Paris Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Aurélie Hatton
- INSERM, U1151, Institut Necker Enfants Malades, INEM, Paris, France
- Université Paris Descartes, Paris, France
| | - Sabrina Karri
- Institute for Integrative Biology of the Cell, I2BC, CEA, CNRS, Université Paris Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - David Cornu
- Institute for Integrative Biology of the Cell, I2BC, CEA, CNRS, Université Paris Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Bruno Costes
- INSERM, U955, Institut de Recherche Henri Mondor, Créteil, France
- Université Paris-Est, Créteil, France
| | - Benoit Chevalier
- INSERM, U1151, Institut Necker Enfants Malades, INEM, Paris, France
- Université Paris Descartes, Paris, France
| | - Danielle Tondelier
- INSERM, U1151, Institut Necker Enfants Malades, INEM, Paris, France
- Université Paris Descartes, Paris, France
| | - Emmanuelle Girodon
- INSERM, U1151, Institut Necker Enfants Malades, INEM, Paris, France
- Laboratoire de Génétique et Biologie Moléculaires, HUPC Hôpital Cochin, AP-HP, Paris, France
| | - Matthieu Coupet
- Institute for Integrative Biology of the Cell, I2BC, CEA, CNRS, Université Paris Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Aleksander Edelman
- INSERM, U1151, Institut Necker Enfants Malades, INEM, Paris, France
- Université Paris Descartes, Paris, France
| | - Pascale Fanen
- INSERM, U955, Institut de Recherche Henri Mondor, Créteil, France
- Université Paris-Est, Créteil, France
- Dept of Genetics, GH Henri Mondor, AP-HP, Créteil, France
| | - Olivier Namy
- Institute for Integrative Biology of the Cell, I2BC, CEA, CNRS, Université Paris Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Isabelle Sermet-Gaudelus
- INSERM, U1151, Institut Necker Enfants Malades, INEM, Paris, France
- Université Paris Descartes, Paris, France
| | - Alexandre Hinzpeter
- INSERM, U1151, Institut Necker Enfants Malades, INEM, Paris, France
- Université Paris Descartes, Paris, France
| |
Collapse
|
14
|
Terlizzi V, Castaldo G, Salvatore D, Lucarelli M, Raia V, Angioni A, Carnovale V, Cirilli N, Casciaro R, Colombo C, Di Lullo AM, Elce A, Iacotucci P, Comegna M, Scorza M, Lucidi V, Perfetti A, Cimino R, Quattrucci S, Seia M, Sofia VM, Zarrilli F, Amato F. Genotype-phenotype correlation and functional studies in patients with cystic fibrosis bearing CFTR complex alleles. J Med Genet 2016; 54:224-235. [PMID: 27738188 DOI: 10.1136/jmedgenet-2016-103985] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 09/12/2016] [Accepted: 09/22/2016] [Indexed: 01/08/2023]
Abstract
BACKGROUND The effect of complex alleles in cystic fibrosis (CF) is poorly defined for the lack of functional studies. OBJECTIVES To describe the genotype-phenotype correlation and the results of either in vitro and ex vivo studies performed on nasal epithelial cells (NEC) in a cohort of patients with CF carrying cystic fibrosis transmembrane conductance regulator (CFTR) complex alleles. METHODS We studied 70 homozygous, compound heterozygous or heterozygous for CFTR mutations: p.[Arg74Trp;Val201Met;Asp1270Asn], n=8; p.[Ile148Thr;Ile1023_Val1024del], n=5; p.[Arg117Leu;Leu997Phe], n=6; c.[1210-34TG[12];1210-12T[5];2930C>T], n=3; p.[Arg74Trp;Asp1270Asn], n=4; p.Asp1270Asn, n=2; p.Ile148Thr, n=6; p.Leu997Phe, n=36. In 39 patients, we analysed the CFTR gating activity on NEC in comparison with patients with CF (n=8) and carriers (n=4). Finally, we analysed in vitro the p.[Arg74Trp;Val201Met;Asp1270Asn] complex allele. RESULTS The p.[Ile148Thr;Ile1023_Val1024del] caused severe CF in five compound heterozygous with a class I-II mutation. Their CFTR activity on NEC was comparable with patients with two class I-II mutations (mean 7.3% vs 6.9%). The p.[Arg74Trp;Asp1270Asn] and the p.Asp1270Asn have scarce functional effects, while p.[Arg74Trp;Val201Met;Asp1270Asn] caused mild CF in four of five subjects carrying a class I-II mutation in trans, or CFTR-related disorders (CFTR-RD) in three having in trans a class IV-V mutation. The p.[Arg74Trp;Val201Met;Asp1270Asn] causes significantly (p<0.001) higher CFTR activity compared with compound heterozygous for class I-II mutations. Furthermore, five of six compounds heterozygous with the p.[Arg117Leu;Leu997Phe] had mild CF, whereas the p.Leu997Phe, in trans with a class I-II CFTR mutation, caused CFTR-RD or a healthy status (CFTR activity: 21.3-36.9%). Finally, compounds heterozygous for the c.[1210-34TG[12];1210-12T[5];2930C>T] and a class I-II mutation had mild CF or CFTR-RD (gating activity: 18.5-19.0%). CONCLUSIONS The effect of complex alleles partially depends on the mutation in trans. Although larger studies are necessary, the CFTR activity on NEC is a rapid contributory tool to classify patients with CFTR dysfunction.
Collapse
Affiliation(s)
- Vito Terlizzi
- Dipartimento di Pediatria, Centro Regionale Toscano per la Fibrosi Cistica, Azienda Ospedaliero-Universitaria Meyer, Florence, Italy
| | - Giuseppe Castaldo
- CEINGE-Biotecnologie Avanzate, Naples, Italy.,Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli Federico II, Naples, Italy
| | | | - Marco Lucarelli
- Dipartimento di Biotecnologie Cellulari ed Ematologia, Istituto Pasteur Fondazione Cenci Bolognetti, Sapienza Università e Policlinico Umberto I, Rome, Italy
| | - Valeria Raia
- Centro Regionale Fibrosi Cistica, Sezione Pediatrica, Dipartimento di Scienze Mediche Traslazionali, Università di Napoli Federico II, Naples, Italy
| | - Adriano Angioni
- Laboratorio di Genetica Medica, Ospedale Pediatrico Bambino Gesù, Rome, Italy
| | - Vincenzo Carnovale
- Dipartimento di Scienze Mediche Traslazionali, Centro Regionale Fibrosi Cistica, Sezione Adulti, Università di Napoli Federico II, Naples, Italy
| | - Natalia Cirilli
- Dipartimento Materno-Infantile, Ospedali Riuniti Ancona, Centro Regionale Fibrosi Cistica, Ancona, Italy
| | - Rosaria Casciaro
- Dipartimento di Pediatria, Centro Regionale Fibrosi Cistica, IRCCS G. Gaslini, Genova, Italy
| | - Carla Colombo
- Centro Regionale Fibrosi Cistica, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Università degli Studi di Milano, Milan, Italy
| | - Antonella Miriam Di Lullo
- CEINGE-Biotecnologie Avanzate, Naples, Italy.,Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli Federico II, Naples, Italy.,Dipartimento di Neuroscienze, Sezione di ORL, Università di Napoli Federico II, Naples, Italy
| | | | - Paola Iacotucci
- Dipartimento di Scienze Mediche Traslazionali, Centro Regionale Fibrosi Cistica, Sezione Adulti, Università di Napoli Federico II, Naples, Italy
| | - Marika Comegna
- CEINGE-Biotecnologie Avanzate, Naples, Italy.,Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli Federico II, Naples, Italy
| | - Manuela Scorza
- CEINGE-Biotecnologie Avanzate, Naples, Italy.,Dipartimento di Biotecnologie e Bioscienze, Università di Milano Bicocca, Milan, Italy
| | - Vincenzina Lucidi
- Unità di Fibrosi Cistica, IRCCS Ospedale Pediatrico Bambin Gesù, Rome, Italy
| | | | - Roberta Cimino
- Dipartimento di Scienze Neurologiche, Riproduttive ed Odontostomatologiche, Università di Napoli Federico II, Naples, Italy
| | - Serena Quattrucci
- Centro Fibrosi Cistica, Sapienza Università e Policlinico Umberto I, Rome, Italy
| | - Manuela Seia
- Laboratorio Genetica Medica, Ospedale Maggiore Policlinico, Milano, Italy
| | | | - Federica Zarrilli
- Dipartimento di Bioscienze e Territorio, Università del Molise, Isernia, Italy
| | - Felice Amato
- CEINGE-Biotecnologie Avanzate, Naples, Italy.,Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli Federico II, Naples, Italy
| |
Collapse
|
15
|
The novel complex allele [A238V;F508del] of the CFTR gene: clinical phenotype and possible implications for cystic fibrosis etiological therapies. J Hum Genet 2016; 61:473-81. [PMID: 26911355 DOI: 10.1038/jhg.2016.15] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Revised: 01/29/2016] [Accepted: 01/31/2016] [Indexed: 02/08/2023]
Abstract
Few mutations in cis have been annotated for F508del homozygous patients. Southern Italy patients who at a first analysis appeared homozygous for the F508del mutation (n=63) or compound heterozygous for the F508del and another mutation in the cystic fibrosis transmembrane conductance regulator gene (n=155) were searched for the A238V mutation in exon 6. The allelic frequency of the complex allele [A238V;F508del] was 0.04. When the whole data set was used (comprised also of 56 F508del/F508del and 34 F508del/other mutation controls), no differences reached the statistical significance in the clinical parameters, except chloride concentrations which were lower in [A238V;F508del]/other mutation compared with F508del/other mutation (P=0.03). The two study groups presented less complications than the control groups. Within the minimal data set (34 F508del/F508del, 27 F508del/other mutation, 4 [A238V;F508del]/F508del cases and 5 [A238V;F508del]/other mutation cases); that is, presenting all the variables in each patient, forced expiratory volume in 1 s and forced vital capacity presented a trend to lower levels in the study groups in comparison with the F508del/F508del group, and C-reactive protein approximated statistically significant higher levels in the [A238V;F508del]/other mutation as compared with F508del/F508del patients (P=0.09). The analysis of statistical dependence among the variables showed a significant anticorrelation between chloride and body mass index in the [A238V;F508del]/other mutation group. In conclusion, the complex allele [A238V;F508del] seems to be associated with less general complications than in the control groups, on the other hand possibly giving a worse pulmonary phenotype and higher systemic/local inflammatory response. These findings have implications for the correct recruitment and clinical response of F508del patients in the clinical trials testing the new etiological drugs for cystic fibrosis.
Collapse
|
16
|
El Khouri E, Le Pavec G, Toledano MB, Delaunay-Moisan A. RNF185 is a novel E3 ligase of endoplasmic reticulum-associated degradation (ERAD) that targets cystic fibrosis transmembrane conductance regulator (CFTR). J Biol Chem 2013; 288:31177-91. [PMID: 24019521 DOI: 10.1074/jbc.m113.470500] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
In the endoplasmic reticulum (ER), misfolded or improperly assembled proteins are exported to the cytoplasm and degraded by the ubiquitin-proteasome pathway through a process called ER-associated degradation (ERAD). ER-associated E3 ligases, which coordinate substrate recognition, export, and proteasome targeting, are key components of ERAD. Cystic fibrosis transmembrane conductance regulator (CFTR) is one ERAD substrate targeted to co-translational degradation by the E3 ligase RNF5/RMA1. RNF185 is a RING domain-containing polypeptide homologous to RNF5. We show that RNF185 controls the stability of CFTR and of the CFTRΔF508 mutant in a RING- and proteasome-dependent manner but does not control that of other classical ERAD model substrates. Reciprocally, its silencing stabilizes CFTR proteins. Turnover analyses indicate that, as RNF5, RNF185 targets CFTR to co-translational degradation. Importantly, however, simultaneous depletion of RNF5 and RNF185 profoundly blocks CFTRΔF508 degradation not only during translation but also after synthesis is complete. Our data thus identify RNF185 and RNF5 as a novel E3 ligase module that is central to the control of CFTR degradation.
Collapse
Affiliation(s)
- Elma El Khouri
- From the Laboratoire Stress Oxydant et Cancers, Service de Biologie Intégrative et Génétique Moléculaire (SBiGeM), Institut de Biologie et de Technologies de Saclay (IBiTec-S), Commissariat à l'Energie Atomique-Saclay, 91191 Gif-sur-Yvette, Cedex, France
| | | | | | | |
Collapse
|
17
|
El-Seedy A, Girodon E, Norez C, Pajaud J, Pasquet MC, de Becdelièvre A, Bienvenu T, des Georges M, Cabet F, Lalau G, Bieth E, Blayau M, Becq F, Kitzis A, Fanen P, Ladeveze V. CFTR mutation combinations producing frequent complex alleles with different clinical and functional outcomes. Hum Mutat 2012; 33:1557-65. [PMID: 22678879 DOI: 10.1002/humu.22129] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 05/21/2012] [Indexed: 11/10/2022]
Abstract
Genotype-phenotype correlations in cystic fibrosis (CF) may be difficult to establish because of phenotype variability, which is associated with certain CF transmembrane conductance regulator (CFTR) gene mutations and the existence of complex alleles. To elucidate the clinical significance of complex alleles involving p.Gly149Arg, p.Asp443Tyr, p.Gly576Ala, and p.Arg668Cys, we performed a collaborative genotype-phenotype correlation study, collected epidemiological data, and investigated structure-function relationships for single and natural complex mutants, p.[Gly576Ala;Arg668Cys], p.[Gly149Arg;Gly576Ala;Arg668Cys], and p.[Asp443Tyr;Gly576Ala;Arg668Cys]. Among 153 patients carrying at least one of these mutations, only three had classical CF and all carried p.Gly149Arg in the triple mutant. Sixty-four had isolated infertility and seven were healthy individuals with a severe mutation in trans, but none had p.Gly149Arg. Functional studies performed on all single and natural complex mutants showed that (1) p.Gly149Arg results in a severe misprocessing defect; (2) p.Asp443Tyr moderately alters CFTR maturation; and (3) p.Gly576Ala, a known splicing mutant, and p.Arg668Cys mildly alter CFTR chloride conductance. Overall, the results consistently show the contribution of p.Gly149Arg to the CF phenotype, and suggest that p.[Arg668Cys], p.[Gly576Ala;Arg668Cys], and p.[Asp443Tyr;Gly576Ala;Arg668Cys] are associated with CFTR-related disorders. The present study emphasizes the importance of comprehensive genotype-phenotype and functional studies in elucidating the impact of mutations on clinical phenotype.
Collapse
Affiliation(s)
- Ayman El-Seedy
- Institut de Physiologie et Biologie Cellulaires, Centre National de la Recherche Scientifique Formation de Recherche en Evolution FRE 3511, Université de Poitiers, Poitiers, France
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Lucarelli M, Narzi L, Pierandrei S, Bruno SM, Stamato A, d'Avanzo M, Strom R, Quattrucci S. A new complex allele of the CFTR gene partially explains the variable phenotype of the L997F mutation. Genet Med 2011; 12:548-55. [PMID: 20706124 DOI: 10.1097/gim.0b013e3181ead634] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
PURPOSE To evaluate the role of complex alleles, with two or more mutations in cis position, of the cystic fibrosis transmembrane conductance regulator (CFTR) gene in the definition of the genotype-phenotype relationship in cystic fibrosis (CF), and to evaluate the functional significance of the highly controversial L997F CFTR mutation. METHODS We evaluated the diagnosis of CF or CFTR-related disorders in 12 unrelated subjects with highly variable phenotypes. According to a first CFTR mutational analysis, subjects appeared to be compound heterozygotes for a classic mutation and the L997F mutation. A further CFTR mutational analysis was conducted by means of a protocol of extended sequencing, particularly suited to the detection of complex alleles. RESULTS We detected a new [R117L; L997F] CFTR complex allele in the four subjects with the highest sweat test values and CF. The eight subjects without the complex allele showed the most varied biochemical and clinical outcome and were diagnosed as having mild CF, CFTR-related disorders, or even no disease. CONCLUSIONS The new complex allele partially explains the variable phenotype in CF subjects with the L997F mutation. CFTR complex alleles are likely to have a role in the definition of the genotype-phenotype relationship in CF. Whenever apparently identical CFTR-mutated genotypes are found in subjects with divergent phenotypes, an extensive mutational search is mandatory.
Collapse
Affiliation(s)
- Marco Lucarelli
- Department of Cellular Biotechnologies and Hematology, Sapienza University of Rome, Rome, Italy.
| | | | | | | | | | | | | | | |
Collapse
|
19
|
de Prada Merino A, Bütschi FN, Bouchardy I, Beckmann JS, Morris MA, Hafen GM, Fellmann F. [R74W;R1070W;D1270N]: A new complex allele responsible for cystic fibrosis. J Cyst Fibros 2010; 9:447-9. [DOI: 10.1016/j.jcf.2010.08.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Accepted: 08/19/2010] [Indexed: 10/19/2022]
|
20
|
Hinzpeter A, Aissat A, Sondo E, Costa C, Arous N, Gameiro C, Martin N, Tarze A, Weiss L, de Becdelièvre A, Costes B, Goossens M, Galietta LJ, Girodon E, Fanen P. Alternative splicing at a NAGNAG acceptor site as a novel phenotype modifier. PLoS Genet 2010; 6. [PMID: 20949073 PMCID: PMC2951375 DOI: 10.1371/journal.pgen.1001153] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Accepted: 09/09/2010] [Indexed: 11/18/2022] Open
Abstract
Approximately 30% of alleles causing genetic disorders generate premature termination codons (PTCs), which are usually associated with severe phenotypes. However, bypassing the deleterious stop codon can lead to a mild disease outcome. Splicing at NAGNAG tandem splice sites has been reported to result in insertion or deletion (indel) of three nucleotides. We identified such a mechanism as the origin of the mild to asymptomatic phenotype observed in cystic fibrosis patients homozygous for the E831X mutation (2623G>T) in the CFTR gene. Analyses performed on nasal epithelial cell mRNA detected three distinct isoforms, a considerably more complex situation than expected for a single nucleotide substitution. Structure-function studies and in silico analyses provided the first experimental evidence of an indel of a stop codon by alternative splicing at a NAGNAG acceptor site. In addition to contributing to proteome plasticity, alternative splicing at a NAGNAG tandem site can thus remove a disease-causing UAG stop codon. This molecular study reveals a naturally occurring mechanism where the effect of either modifier genes or epigenetic factors could be suspected. This finding is of importance for genetic counseling as well as for deciding appropriate therapeutic strategies. Mild disease outcomes associated with premature termination codons can result from at least three different mechanisms, but none of these mechanisms explain the mild phenotype observed in some patients. Subtle differences in alternative transcripts have recently been reported at NAGNAG tandem acceptor motifs, which can be detected in 30% of human genes. We provide the first experimental evidence of premature termination codon removal by alternative splicing at a NAGNAG acceptor splice site. Our study emphasizes the biological significance of such alternative splicing in the context of disease-causing mutations and defines a new phenotype-modifying mechanism that buffers nonsense mutations.
Collapse
Affiliation(s)
| | - Abdel Aissat
- INSERM, Unité U955, Créteil, France
- Université Paris-Est, Faculté de Médecine, UMR-S 955, Créteil, France
| | - Elvira Sondo
- Laboratorio di Genetica Molecolare, Istituto G. Gaslini, Genova, Italy
| | - Catherine Costa
- INSERM, Unité U955, Créteil, France
- AP-HP, Groupe Henri-Mondor Albert-Chenevier, Service de Biochimie-Génétique, Créteil, France
| | | | - Christine Gameiro
- AP-HP, Groupe Henri-Mondor Albert-Chenevier, Service de Biochimie-Génétique, Créteil, France
| | | | - Agathe Tarze
- INSERM, Unité U955, Créteil, France
- Université Paris-Est, Faculté de Médecine, UMR-S 955, Créteil, France
| | - Laurence Weiss
- Service de Pédiatrie I, Hôpitaux Universitaires de Strasbourg, Hôpital de Hautepierre, Strasbourg, France
| | - Alix de Becdelièvre
- INSERM, Unité U955, Créteil, France
- Université Paris-Est, Faculté de Médecine, UMR-S 955, Créteil, France
- AP-HP, Groupe Henri-Mondor Albert-Chenevier, Service de Biochimie-Génétique, Créteil, France
| | - Bruno Costes
- Université Paris-Est, Faculté de Médecine, UMR-S 955, Créteil, France
| | - Michel Goossens
- INSERM, Unité U955, Créteil, France
- Université Paris-Est, Faculté de Médecine, UMR-S 955, Créteil, France
- AP-HP, Groupe Henri-Mondor Albert-Chenevier, Service de Biochimie-Génétique, Créteil, France
| | - Luis J. Galietta
- Laboratorio di Genetica Molecolare, Istituto G. Gaslini, Genova, Italy
| | - Emmanuelle Girodon
- INSERM, Unité U955, Créteil, France
- AP-HP, Groupe Henri-Mondor Albert-Chenevier, Service de Biochimie-Génétique, Créteil, France
| | - Pascale Fanen
- INSERM, Unité U955, Créteil, France
- Université Paris-Est, Faculté de Médecine, UMR-S 955, Créteil, France
- AP-HP, Groupe Henri-Mondor Albert-Chenevier, Service de Biochimie-Génétique, Créteil, France
- * E-mail:
| |
Collapse
|
21
|
p.Ser1235Arg should no longer be considered as a cystic fibrosis mutation: results from a large collaborative study. Eur J Hum Genet 2010; 19:36-42. [PMID: 20717170 DOI: 10.1038/ejhg.2010.137] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Among the 1700 mutations reported in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, a missense mutation, p.Ser1235Arg, is a relatively frequent finding. To clarify its clinical significance, we collected data from 104 subjects heterozygous for the mutation p.Ser1235Arg from the French CF network, addressed for various indications including classical CF, atypical phenotypes or carrier screening in subjects with or without a family history. Among them, 26 patients (5 having CF, 10 CBAVD (congenital bilateral absence of the vas deferens) and 11 with CF-like symptoms) and 14 healthy subjects were compound heterozygous for a second CFTR mutation. An exhaustive CFTR gene analysis identified a second mutation in cis of p.Ser1235Arg in all CF patients and in 81.8% CBAVD patients. Moreover, epidemiological data from >2100 individuals found a higher frequency of p.Ser1235Arg in the general population than in CF or CBAVD patients. These data, added to the fact that in silico analysis and functional assays suggest a benign nature of this substitution, give several lines of evidence against an association of p.Ser1235Arg with CF or CBAVD.
Collapse
|
22
|
Brugnon F, Bilan F, Heraud MC, Grizard G, Janny L, Creveaux I. Outcome of intracytoplasmic sperm injection for a couple in which the man is carrier of CFTR p.[R74W;V201M;D1270N] and p.P841R mutations and his spouse a heterozygous carrier of p.F508del mutation of the cystic fibrosis transmembrane conductance regulator gene. Fertil Steril 2008; 90:2004.e23-6. [DOI: 10.1016/j.fertnstert.2008.05.057] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Revised: 05/05/2008] [Accepted: 05/15/2008] [Indexed: 11/25/2022]
|
23
|
Tanguy G, Drévillon L, Arous N, Hasnain A, Hinzpeter A, Fritsch J, Goossens M, Fanen P. CSN5 binds to misfolded CFTR and promotes its degradation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:1189-99. [PMID: 18267124 DOI: 10.1016/j.bbamcr.2008.01.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2007] [Revised: 12/31/2007] [Accepted: 01/07/2008] [Indexed: 12/16/2022]
Abstract
Cystic fibrosis is mainly caused by mutations that interfere with the biosynthetic folding of the cystic fibrosis transmembrane conductance regulator (CFTR) protein. The aim of this study was to find cellular proteins interacting with CFTR and regulating its processing. We have used a genetic screen in yeast to identify such proteins and identified CSN5 that interacted with the third cytoplasmic loop of CFTR. CSN5 is the 5th component of the COP9 signalosome, a complex of eight subunits that shares significant homologies to the lid subcomplex of the 26S proteasome and controls the stability of many proteins. The present study shows that CSN5 associates with the core-glycosylated form of CFTR and suggests that this association targets misfolded CFTR to the degradative pathway. Identifying CSN5 as a new component of the degradative pathway is an important step towards the goal of unraveling the sorting between misfolded and correctly folded CFTR proteins.
Collapse
Affiliation(s)
- Gaëlle Tanguy
- INSERM U841, Département de Génétique, Equipe 11, Hôpital Henri Mondor, 51 avenue du Maréchal de Lattre de Tassigny, Créteil, F-94010, France
| | | | | | | | | | | | | | | |
Collapse
|
24
|
de Gracia J, Mata F, Alvarez A, Casals T, Gatner S, Vendrell M, de la Rosa D, Guarner L, Hermosilla E. Genotype-phenotype correlation for pulmonary function in cystic fibrosis. Thorax 2005; 60:558-63. [PMID: 15994263 PMCID: PMC1747467 DOI: 10.1136/thx.2004.031153] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Since the CFTR gene was cloned, more than 1000 mutations have been identified. To date, a clear relationship has not been established between genotype and the progression of lung damage. A study was undertaken of the relationship between genotype, progression of lung disease, and survival in adult patients with cystic fibrosis (CF). METHODS A prospective cohort of adult patients with CF and two CFTR mutations followed up in an adult cystic fibrosis unit was analysed. Patients were classified according to functional effects of classes of CFTR mutations and were grouped based on the CFTR molecular position on the epithelial cell surface (I-II/I-II, I-II/III-V). Spirometric values, progression of lung disease, probability of survival, and clinical characteristics were analysed between groups. RESULTS Seventy four patients were included in the study. Patients with genotype I-II/I-II had significantly lower current spirometric values (p < 0.001), greater loss of pulmonary function (p < 0.04), a higher proportion of end-stage lung disease (p < 0.001), a higher risk of suffering from moderate to severe lung disease (odds ratio 7.12 (95% CI 1.3 to 40.5)) and a lower probability of survival than patients with genotype I-II/III, I-II/IV and I-II/V (p < 0.001). CONCLUSIONS The presence of class I or II mutations on both chromosomes is associated with worse respiratory disease and a lower probability of survival.
Collapse
Affiliation(s)
- J de Gracia
- Department of Pneumology, Hospital general Vall d'Hebron, Barcelona, Spain.
| | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Clain J, Lehmann-Che J, Duguépéroux I, Arous N, Girodon E, Legendre M, Goossens M, Edelman A, de Braekeleer M, Teulon J, Fanen P. Misprocessing of theCFTRprotein leads to mild cystic fibrosis phenotype. Hum Mutat 2005; 25:360-71. [PMID: 15776432 DOI: 10.1002/humu.20156] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Cystic fibrosis (CF) is mainly caused by mutations that interfere with the biosynthetic folding of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel. The aim of this study was to determine the mechanism of dysfunction of a disease-causing mutation associated with variable phenotypes. In order to attain these objectives, we studied the effect of the p.L206W mutation on CFTR protein production and function, and we examined the genotype-phenotype correlation of [p.L206W]+[p.F508del] patients. We showed that p.L206W is a processing (class II) mutation since the CFTR biosynthetic pathway was severely impaired, whereas single-channel measurements indicated ion conductance similar to the wild-type protein. These data raise the larger question of the phenotypic variability of class II mutants, including p.F508del. Since multiple potential partners could modify the processing of the CFTR protein during its course to the cell surface, environmental and other genetic factors might contribute to this variability.
Collapse
Affiliation(s)
- Jérôme Clain
- Institut National de la Santé et de la Recherche Médicale (INSERM) U. 468, Hôpital Henri Mondor, Créteil, France
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Clain J, Lehmann-Che J, Girodon E, Lipecka J, Edelman A, Goossens M, Fanen P. A neutral variant involved in a complex CFTR allele contributes to a severe cystic fibrosis phenotype. Hum Genet 2005; 116:454-60. [PMID: 15744523 DOI: 10.1007/s00439-004-1246-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2004] [Accepted: 12/12/2004] [Indexed: 11/26/2022]
Abstract
In order to further elucidate the contribution of complex alleles to the wide phenotypic variability of cystic fibrosis (CF), we investigated the structure-function relationships of a severe CF-associated complex allele [p.S912L;p.G1244V]. To evaluate the contribution of each mutation to the phenotype, cystic fibrosis transmembrane conductance regulator (CFTR) mutants were expressed in HeLa cells and analysed for protein processing and Cl- channel activity. Both p.G1244V and [p.S912L;p.G1244V] mutants had normal protein processing but markedly decreased Cl- channel activity compared with wild-type. Notably, the double mutant displayed a dramatic decrease in Cl- channel activity compared with p.G1244V (P<0.001). p.S912L had normal protein processing and no detectable impact on CFTR function. In other respects, the p.S912L variation was identified in compound heterozygosity with p.R709X in a healthy fertile man. Together, these data strongly support the view that p.S912L in isolation should be considered as a neutral variant but one that might significantly impair CFTR function when inherited in cis with another CFTR mutation. Our data also further document the contribution of complex alleles to the wide phenotypic variability of CF. The results of functional studies of such complex alleles in other genetic diseases are discussed.
Collapse
Affiliation(s)
- Jérôme Clain
- Service de Biochimie et Génétique, Hôpital Henri Mondor, Institut National de la Santé et de la Recherche Médicale U.468, AP-HP, 94010, Créteil, France
| | | | | | | | | | | | | |
Collapse
|
27
|
Sugarman EA, Rohlfs EM, Silverman LM, Allitto BA. CFTR mutation distribution among U.S. Hispanic and African American individuals: evaluation in cystic fibrosis patient and carrier screening populations. Genet Med 2005; 6:392-9. [PMID: 15371903 DOI: 10.1097/01.gim.0000139503.22088.66] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
PURPOSE We reviewed CFTR mutation distribution among Hispanic and African American individuals referred for CF carrier screening and compared mutation frequencies to those derived from CF patient samples. METHODS Results from CFTR mutation analyses received from January 2001 through September 2003, were analyzed for four populations: Hispanic individuals with a CF diagnosis (n = 159) or carrier screening indication (n = 15,333) and African American individuals with a CF diagnosis (n = 108) or carrier screening indication (n = 8,973). All samples were tested for the same 87 mutation panel. RESULTS In the Hispanic population, 42 mutations were identified: 30 in the patient population (77.5% detection rate) and 33 among carrier screening referrals. Five mutations not included in the ACMG/ACOG carrier screening panel (3876delA, W1089X, R1066C, S549N, 1949del84) accounted for 7.55% detection in patients and 5.58% among carriers. Among African American referrals, 33 different mutations were identified: 21 in the patient population (74.4% detection) and 23 in the carrier screening population. Together, A559T and 711+5G>A were observed at a detection rate of 3.71% in CF patients and 6.38% in carriers. The mutation distribution seen in both the carrier screening populations reflected an increased frequency of mutations with variable expression such as D1152H, R117H, and L206W. CONCLUSIONS A detailed analysis of CFTR mutation distribution in the Hispanic and African American patient and carrier screening populations demonstrates that a diverse group of mutations is most appropriate for diagnostic and carrier screening in these populations. To best serve the increasingly diverse U.S. population, ethnic-specific mutations should be included in mutation panels.
Collapse
Affiliation(s)
- Elaine A Sugarman
- Genzyme Corporation, Genzyme Genetics, Molecular Diagnostic Laboratory, Westborough, Massachusetts 01581, USA
| | | | | | | |
Collapse
|
28
|
Claustres M, Altiéri JP, Guittard C, Templin C, Chevalier-Porst F, Georges MD. Are p.I148T, p.R74W and p.D1270N cystic fibrosis causing mutations? BMC MEDICAL GENETICS 2004; 5:19. [PMID: 15287992 PMCID: PMC509248 DOI: 10.1186/1471-2350-5-19] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 04/16/2004] [Accepted: 08/02/2004] [Indexed: 11/23/2022]
Abstract
BACKGROUND To contribute further to the classification of three CFTR amino acid changes (p.I148T, p.R74W and p.D1270N) either as CF or CBAVD-causing mutations or as neutral variations. METHODS The CFTR genes from individuals who carried at least one of these changes were extensively scanned by a well established DGGE assay followed by direct sequencing and familial segregation analysis of mutations and polymorphisms. RESULTS Four CF patients (out of 1238) originally identified as carrying the p.I148T mutation in trans with a CF mutation had a second mutation (c.3199del6 or a novel mutation c.3395insA) on the p.I148T allele. We demonstrate here that the deletion c.3199del6 can also be associated with CF without p.I148T. Three CBAVD patients originally identified with the complex allele p.R74W-p.D1270N were also carrying p.V201M on this allele, by contrast with non CF or asymptomatic individuals including the mother of a CF child, who were carrying p.R74W-p.D1270N alone. CONCLUSION These findings question p.I148T or p.R74W-p.D1270N as causing by themselves CF or CBAVD and emphazises the necessity to perform a complete scanning of CFTR genes and to assign the parental alleles when novel missense mutations are identified.
Collapse
Affiliation(s)
- Mireille Claustres
- Laboratoire de Génétique Moléculaire, Institut Universitaire de Recherche Clinique et Centre Hospitalier Universitaire, 641 avenue du Doyen Gaston Giraud, 34093 Montpellier, France
| | - Jean-Pierre Altiéri
- Laboratoire de Génétique Moléculaire, Institut Universitaire de Recherche Clinique et Centre Hospitalier Universitaire, 641 avenue du Doyen Gaston Giraud, 34093 Montpellier, France
| | - Caroline Guittard
- Laboratoire de Génétique Moléculaire, Institut Universitaire de Recherche Clinique et Centre Hospitalier Universitaire, 641 avenue du Doyen Gaston Giraud, 34093 Montpellier, France
| | - Carine Templin
- Laboratoire de Génétique Moléculaire, Institut Universitaire de Recherche Clinique et Centre Hospitalier Universitaire, 641 avenue du Doyen Gaston Giraud, 34093 Montpellier, France
| | - Françoise Chevalier-Porst
- Laboratoire de Biochimie pédiatrique, Centre Hospitalier Universitaire Paul-Brousse, 69000 Lyon, France
| | - Marie Des Georges
- Laboratoire de Génétique Moléculaire, Institut Universitaire de Recherche Clinique et Centre Hospitalier Universitaire, 641 avenue du Doyen Gaston Giraud, 34093 Montpellier, France
| |
Collapse
|
29
|
Hicks K, Beadling W, Shrimpton AE. Cystic fibrosis: S158N (605G --> A) is a rare genetic variant found in coupling with deltaF508. GENETIC TESTING 2003; 7:73-6. [PMID: 12820707 DOI: 10.1089/109065703321560985] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A single nucleotide change at codon 158 in exon 4 of the CFTR gene ABCC7 was detected in an asymptomatic individual who carried deltaF508 and had a family history of cystic fibrosis (CF). Further study, using linkage, revealed that S158N was coupled with deltaF508, both having been inherited from the same parent. The clinical implications of double mutations in the same allele are discussed.
Collapse
Affiliation(s)
- Karen Hicks
- Department of Clinical Pathology, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | | | | |
Collapse
|
30
|
Rohlfs EM, Zhou Z, Sugarman EA, Heim RA, Pace RG, Knowles MR, Silverman LM, Allitto BA. The I148T CFTR allele occurs on multiple haplotypes: a complex allele is associated with cystic fibrosis. Genet Med 2002; 4:319-23. [PMID: 12394343 DOI: 10.1097/00125817-200209000-00001] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
PURPOSE To determine whether intragenic changes modulate the cystic fibrosis (CF) phenotype in individuals who are positive for the I148T allele. METHODS The genes from individuals who carried at least one copy of the I148T allele were analyzed for additional changes that may be acting as genetic modifiers. RESULTS Seven of eight individuals with a known or suspected diagnosis of CF who carried I148T in combination with a severe CF mutation also carried 3199del6. Eight apparently healthy adult individuals who were compound heterozygous for I148T and a severe CF mutation or homozygous for I148T did not carry the deletion ( = 0.0014). The I148T allele occurs on at least three haplotypes: an IVS-8 9T background, a 7T background, or a 9T + 3199del6 background. The 3199del6 allele was not identified in 386 non-CF chromosomes. CONCLUSIONS It is concluded that I148T occurs on at least three haplotypes and the complex allele I148T + 9T + 3199del6 is associated with a classic CF phenotype.
Collapse
Affiliation(s)
- Elizabeth M Rohlfs
- Genzyme Genetics, Molecular Diagnostic Laboratory, Framingham, Massachusetts 01701, USA
| | | | | | | | | | | | | | | |
Collapse
|
31
|
Girodon E, Sternberg D, Chazouillères O, Cazeneuve C, Huot D, Calmus Y, Poupon R, Goossens M, Housset C. Cystic fibrosis transmembrane conductance regulator (CFTR) gene defects in patients with primary sclerosing cholangitis. J Hepatol 2002; 37:192-7. [PMID: 12127423 DOI: 10.1016/s0168-8278(02)00161-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
BACKGROUND/AIMS Because biliary tract lesions that resemble those of primary sclerosing cholangitis (PSC) may occur in cystic fibrosis (CF), we examined the prevalence and influence of CF transmembrane conductance regulator (CFTR) gene mutations in PSC patients. METHODS Genomic DNA was analyzed in 29 consecutive PSC patients and in 115 healthy control individuals. A scanning method followed by direct DNA sequencing was used to scan the CFTR coding regions. RESULTS Four patients (13.8%) were heterozygous for a CFTR mutation, including a new putative severe CF-causing mutation (N782K), and three mild defects (L997F, D1270N, and S1235R). The comparison of PSC patients with healthy controls showed no significant difference in the frequency of CFTR mutations (P=0.415). In addition, two patients (6.9%) were heterozygous for the IVS8-5T allele, which is not significantly different from the 5-6%-prevalence in the general population. Unusual clinical features including a severe outcome in childhood, with a lethal outcome at age 22, and biliary aspergillosis were recorded in patients with a CFTR mutation. CONCLUSIONS The proportion of CF carriers is not significantly higher in PSC patients than in the general population. The possibility that CFTR mutations may contribute to a severe clinical course in PSC patients is worth further examining.
Collapse
Affiliation(s)
- Emmanuelle Girodon
- Service de Biochimie et de Génétique, AP-HP and INSERM U468, Hôpital Henri Mondor, 94010 Créteil, France.
| | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Muller F, Simon-Bouy B, Girodon E, Monnier N, Malinge MC, Serre JL. Predicting the risk of cystic fibrosis with abnormal ultrasound signs of fetal bowel: results of a French molecular collaborative study based on 641 prospective cases. AMERICAN JOURNAL OF MEDICAL GENETICS 2002; 110:109-15. [PMID: 12116247 DOI: 10.1002/ajmg.10431] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Hyperechogenic fetal bowel is prenatally detected by ultrasound during the second trimester of pregnancy in 0.1-1.8% of fetuses. It has been described as a normal variant but has often been associated with severe diseases, notably cystic fibrosis (CF). The aim of our study was to determine the risk of CF in a prospective study of 641 fetuses with ultrasonographically abnormal fetal bowel and the residual risk when only one mutation is detected in the fetus. Fetal cells and/or parental blood cells were screened for CFTR mutations. Two screening steps were used, the first covering the mutations most frequently observed in French CF patients (mutation detection rate of 70-90%) and, when a CF mutation was detected, a DGGE-sequencing strategy. We observed a 3.1% risk of CF when a digestive tract anomaly was prenatally observed at routine ultrasound examination. The risk was higher when hyperechogenicity was associated with bowel dilatation (5/29; 17%) or with the absence of gall bladder (2/8; 25%). The residual risk of CF was 11% when only one CF mutation was detected by the first screening step, thereby justifying in-depth screening. Mutations associated with severe CF (DeltaF508 mutation) were more frequently observed in these ultrasonographically and prenatally detected CF cases. However, the frequency of heterozygous cases was that observed in the normal population, which demonstrates that heterozygous carriers of CF mutations are not at increased risk for hyperechogenic bowel. In conclusion, fetal bowel anomalies indicate a risk of severe cystic fibrosis and justify careful CFTR molecular analysis.
Collapse
Affiliation(s)
- F Muller
- SESEP, Université de Versailles, Versailles, France.
| | | | | | | | | | | |
Collapse
|
33
|
Clain J, Fritsch J, Lehmann-Che J, Bali M, Arous N, Goossens M, Edelman A, Fanen P. Two mild cystic fibrosis-associated mutations result in severe cystic fibrosis when combined in cis and reveal a residue important for cystic fibrosis transmembrane conductance regulator processing and function. J Biol Chem 2001; 276:9045-9. [PMID: 11118444 DOI: 10.1074/jbc.m008979200] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The number of complex cystic fibrosis transmembrane conductance regulator (CFTR) genotypes identified as having double-mutant alleles with two mutations inherited in cis has been growing. We investigated the structure-function relationships of a severe cystic fibrosis (CF)-associated double mutant (R347H-D979A) to evaluate the contribution of each mild mutation to the phenotype. CFTR mutants expressed in HeLa cells were analyzed for protein biosynthesis and Cl(-) channel activity. Our data show that R347H is associated with mild defective Cl(-) channel activity and that the D979A defect leads to misprocessing. The mutant R347H-D979A combines both defects for a dramatic decrease in Cl(-) current. To decipher the molecular mechanism of this phenotype, single and double mutants with different charge combinations at residues 347 and 979 were constructed as charged residues were involved in this complex genotype. These studies revealed that residue 979, located in the third cytoplasmic loop, is critical for CFTR processing and Cl(-) channel activity highlighting the role of charged residues. These results have also important implications for CF, as they show that two mutations in cis can act in concert to alter dramatically CFTR function contributing to the wide phenotypic variability of CF disease.
Collapse
Affiliation(s)
- J Clain
- INSERM U.468, Hôpital Henri Mondor, 94010 Créteil, INSERM U.467, Faculté de Médecine Necker, 75015 Paris, and CNRS UPR.1524, Hôpital Saint Vincent dePaul, 75674 Paris, France
| | | | | | | | | | | | | | | |
Collapse
|
34
|
Mickle JE, Milewski MI, Macek M, Cutting GR. Effects of cystic fibrosis and congenital bilateral absence of the vas deferens-associated mutations on cystic fibrosis transmembrane conductance regulator-mediated regulation of separate channels. Am J Hum Genet 2000; 66:1485-95. [PMID: 10762539 PMCID: PMC1378012 DOI: 10.1086/302893] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/1999] [Accepted: 02/16/2000] [Indexed: 12/13/2022] Open
Abstract
The protein defective in cystic fibrosis (CF), the CF transmembrane-conductance regulator (CFTR), functions as an epithelial chloride channel and as a regulator of separate ion channels. Although the consequences that disease-causing mutations have on the chloride-channel function have been studied extensively, little is known about the effects that mutations have on the regulatory function. To address this issue, we transiently expressed CFTR-bearing mutations associated with CF or its milder phenotype, congenital bilateral absence of the vas deferens, and determined whether mutant CFTR could regulate outwardly rectifying chloride channels (ORCCs). CFTR bearing a CF-associated mutation in the first nucleotide-binding domain (NBD1), DeltaF508, functioned as a chloride channel but did not regulate ORCCs. However, CFTR bearing disease-associated mutations in other domains retained both functions, regardless of the associated phenotype. Thus, a relationship between loss of CFTR regulatory function and disease severity is evident for NBD1, a region of CFTR that appears important for regulation of separate channels.
Collapse
Affiliation(s)
- J E Mickle
- Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | | | | | | |
Collapse
|
35
|
Abstract
Cystic fibrosis transmembrane conductance regulator (CFTR) gene studies are now one of the most frequent activities in clinical molecular genetics laboratories. The number of requests is growing, owing to the increasingly wide range of recognized CFTR gene diseases (cystic fibrosis, congenital bilateral absence of the vas deferens, disseminated bronchiectasis, allergic bronchopulmonary aspergillosis and chronic pancreatitis), and the availability of efficient molecular tools for detecting mutations. A growing number of tests capable of simultaneously detecting several frequent CF mutations are being developed, and commercial kits are now available. The most recent kits detect nearly 90% of defective alleles in Caucasians, a rate high enough for carrier screening and for the majority of diagnostic requests. However, because of the wide variety of molecular defects documented in the CFTR gene, only a limited number of laboratories have mastered the entire panoply of necessary techniques, while other laboratories have to refer certain cases to specialized centers with complementary and/or scanning tools at their disposal. A good knowledge of CFTR diseases and their molecular mechanisms, together with expertise in the various techniques, is crucial for interpreting the results. Diagnostic strategies must take into account the indication, the patient's ethnic origin, and the time available in the framework of genetic counseling. This review presents the methods most frequently used for detecting CFTR gene mutations, and discusses the strategies most suited to the different clinical settings.
Collapse
Affiliation(s)
- E Girodon-Boulandet
- Service de Biochimie et de Génétique, INSERM U468, Hôpital Henri-Mondor, Créteil, France
| | | | | |
Collapse
|