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Schnell A, Tamm S, Hedtfeld S, Rodriguez Gonzalez C, Hoerning A, Lachmann N, Stanke F, Dittrich AM, Munder A. Analysis of CFTR mRNA and Protein in Peripheral Blood Mononuclear Cells via Quantitative Real-Time PCR and Western Blot. Int J Mol Sci 2024; 25:6367. [PMID: 38928073 PMCID: PMC11203434 DOI: 10.3390/ijms25126367] [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: 12/21/2023] [Revised: 05/31/2024] [Accepted: 06/06/2024] [Indexed: 06/28/2024] Open
Abstract
The Cystic Fibrosis Conductance Transmembrane Regulator gene encodes for the CFTR ion channel, which is responsible for the transport of chloride and bicarbonate across the plasma membrane. Mutations in the gene result in impaired ion transport, subsequently leading to perturbed secretion in all exocrine glands and, therefore, the multi-organ disease cystic fibrosis (CF). In recent years, several studies have reported on CFTR expression in immune cells as demonstrated by immunofluorescence, flow cytometry, and immunoblotting. However, these data are mainly restricted to single-cell populations and show significant variation depending on the methodology used. Here, we investigated CFTR transcription and protein expression using standardized protocols in a comprehensive panel of immune cells. Methods: We applied a high-resolution Western blot protocol using a combination of highly specific monoclonal CFTR antibodies that have been optimized for the detection of CFTR in epithelial cells and healthy primary immune cell subpopulations sorted by flow cytometry and used immortalized cell lines as controls. The specificity of CFTR protein detection was controlled by peptide competition and enzymatic Peptide-N-Glycosidase-F (PNGase) digest. CFTR transcripts were analyzed using quantitative real-time PCR and normalized to the level of epithelial T84 cells as a reference. Results: CFTR mRNA expression could be shown for primary CD4+ T cells, NK cells, as well as differentiated THP-1 and Jurkat T cells. In contrast, we failed to detect CFTR transcripts for CD14+ monocytes and undifferentiated THP-1 cells, as well as for B cells and CD8+ T cells. Prominent immunoreactive bands were detectable by immunoblotting with the combination of four CFTR antibodies targeting different epitopes of the CFTR protein. However, in biosamples of non-epithelial origin, these CFTR-like protein bands could be unmasked as false positives through peptide competition or PNGase digest, meaning that the observed mRNA transcripts were not necessarily translated into CFTR proteins, which could be detected via immunoblotting. Our results confirm that mRNA expression in immune cells is many times lower than in that cells of epithelial origin. The immunoreactive signals in immune cells turned out to be false positives, and may be provoked by the presence of a high-affinity protein with a similar epitope. Non-specific binding (e.g., Fab-interaction with glycosyl branches) might also contribute to false positive signals. Our findings highlight the necessity of accurate controls, such as CFTR-negative cells, as well as peptide competition and glycolytic digest in order to identify genuine CFTR protein by immunoblotting. Our data suggest, furthermore, that CFTR protein expression data from techniques such as histology, for which the absence of a molecular weight or other independent control prevents the unmasking of false positive immunoreactive signals, must be interpreted carefully as well.
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Affiliation(s)
- Alexander Schnell
- Department of Pediatric and Adolescent Medicine, University Hospital Erlangen, 91054 Erlangen, Germany;
| | - Stephanie Tamm
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, 30625 Hannover, Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, 30625 Hannover, Germany
| | - Silke Hedtfeld
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, 30625 Hannover, Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, 30625 Hannover, Germany
| | - Claudio Rodriguez Gonzalez
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, 30625 Hannover, Germany
| | - Andre Hoerning
- Department of Pediatric and Adolescent Medicine, University Hospital Erlangen, 91054 Erlangen, Germany;
| | - Nico Lachmann
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, 30625 Hannover, Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, 30625 Hannover, Germany
- Fraunhofer Institute for Toxicology and Experimental Medicine, 30625 Hannover, Germany
| | - Frauke Stanke
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, 30625 Hannover, Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, 30625 Hannover, Germany
| | - Anna-Maria Dittrich
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, 30625 Hannover, Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, 30625 Hannover, Germany
| | - Antje Munder
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, 30625 Hannover, Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, 30625 Hannover, Germany
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Berges J, Graeber SY, Hämmerling S, Yu Y, Krümpelmann A, Stahl M, Hirtz S, Scheuermann H, Mall MA, Sommerburg O. Effects of lumacaftor-ivacaftor therapy on cystic fibrosis transmembrane conductance regulator function in F508del homozygous patients with cystic fibrosis aged 2-11 years. Front Pharmacol 2023; 14:1188051. [PMID: 37324488 PMCID: PMC10266342 DOI: 10.3389/fphar.2023.1188051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 05/18/2023] [Indexed: 06/17/2023] Open
Abstract
Rationale: Lumacaftor/ivacaftor was approved for the treatment of patients with cystic fibrosis who are homozygous for F508del aged 2 years and older following positive results from phase three trials. However, the improvement in CFTR function associated with lumacaftor/ivacaftor has only been studied in patients over 12 years of age, while the rescue potential in younger children is unknown. Methods: In a prospective study, we aimed to evaluate the effect of lumacaftor/ivacaftor on the CFTR biomarkers sweat chloride concentration and intestinal current measurement as well as clinical outcome parameters in F508del homozygous CF patients 2-11 years before and 8-16 weeks after treatment initiation. Results: A total of 13 children with CF homozygous for F508del aged 2-11 years were enrolled and 12 patients were analyzed. Lumacaftor/ivacaftor treatment reduced sweat chloride concentration by 26.8 mmol/L (p = 0.0006) and showed a mean improvement in CFTR activity, as assessed by intestinal current measurement in the rectal epithelium, of 30.5% compared to normal (p = 0.0015), exceeding previous findings of 17.7% of normal in CF patients homozygous for F508del aged 12 years and older. Conclusion: Lumacaftor/ivacaftor partially restores F508del CFTR function in children with CF who are homozygous for F508del, aged 2-11 years, to a level of CFTR activity seen in patients with CFTR variants with residual function. These results are consistent with the partial short-term improvement in clinical parameters.
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Affiliation(s)
- Julian Berges
- Division of Pediatric Pulmonology and Allergology and Cystic Fibrosis Center, Department of Pediatrics, University of Heidelberg, Heidelberg, Germany
- Department of Translational Pulmonology, Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research (DZL), University of Heidelberg, Heidelberg, Germany
| | - Simon Y. Graeber
- Department of Pediatric Respiratory Medicine, Immunology and Critical Care Medicine and Cystic Fibrosis Center, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- Berlin Institute of Health at Charité—Universitätsmedizin Berlin, Berlin, Germany
- German Center for Lung Research (DZL), Associated Partner Site, Berlin, Germany
| | - Susanne Hämmerling
- Division of Pediatric Pulmonology and Allergology and Cystic Fibrosis Center, Department of Pediatrics, University of Heidelberg, Heidelberg, Germany
- Department of Translational Pulmonology, Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research (DZL), University of Heidelberg, Heidelberg, Germany
| | - Yin Yu
- Division of Pediatric Pulmonology and Allergology and Cystic Fibrosis Center, Department of Pediatrics, University of Heidelberg, Heidelberg, Germany
- Department of Translational Pulmonology, Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research (DZL), University of Heidelberg, Heidelberg, Germany
| | - Arne Krümpelmann
- Division of Pediatric Pulmonology and Allergology and Cystic Fibrosis Center, Department of Pediatrics, University of Heidelberg, Heidelberg, Germany
- Department of Translational Pulmonology, Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research (DZL), University of Heidelberg, Heidelberg, Germany
| | - Mirjam Stahl
- Department of Pediatric Respiratory Medicine, Immunology and Critical Care Medicine and Cystic Fibrosis Center, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- Berlin Institute of Health at Charité—Universitätsmedizin Berlin, Berlin, Germany
- German Center for Lung Research (DZL), Associated Partner Site, Berlin, Germany
| | - Stephanie Hirtz
- Division of Pediatric Pulmonology and Allergology and Cystic Fibrosis Center, Department of Pediatrics, University of Heidelberg, Heidelberg, Germany
- Department of Translational Pulmonology, Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research (DZL), University of Heidelberg, Heidelberg, Germany
| | - Heike Scheuermann
- Division of Pediatric Pulmonology and Allergology and Cystic Fibrosis Center, Department of Pediatrics, University of Heidelberg, Heidelberg, Germany
- Department of Translational Pulmonology, Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research (DZL), University of Heidelberg, Heidelberg, Germany
| | - Marcus A. Mall
- Department of Pediatric Respiratory Medicine, Immunology and Critical Care Medicine and Cystic Fibrosis Center, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- Berlin Institute of Health at Charité—Universitätsmedizin Berlin, Berlin, Germany
- German Center for Lung Research (DZL), Associated Partner Site, Berlin, Germany
| | - Olaf Sommerburg
- Division of Pediatric Pulmonology and Allergology and Cystic Fibrosis Center, Department of Pediatrics, University of Heidelberg, Heidelberg, Germany
- Department of Translational Pulmonology, Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research (DZL), University of Heidelberg, Heidelberg, Germany
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3
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Stanke F, Pallenberg ST, Tamm S, Hedtfeld S, Eichhorn EM, Minso R, Hansen G, Welte T, Sauer-Heilborn A, Ringshausen FC, Junge S, Tümmler B, Dittrich AM. Changes in cystic fibrosis transmembrane conductance regulator protein expression prior to and during elexacaftor-tezacaftor-ivacaftor therapy. Front Pharmacol 2023; 14:1114584. [PMID: 36778025 PMCID: PMC9911415 DOI: 10.3389/fphar.2023.1114584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 01/16/2023] [Indexed: 01/28/2023] Open
Abstract
Background: Defects in expression, maturation or function of the epithelial membrane glycoprotein CFTR are causative for the progressive disease cystic fibrosis. Recently, molecular therapeutics that improve CFTR maturation and functional defects have been approved. We aimed to verify whether we could detect an improvement of CFTR protein expression and maturation by triple therapy with elexacaftor-tezacaftor-ivacaftor (ELX/TEZ/IVA). Methods: Rectal suction biopsies of 21 p.Phe508del homozygous or compound heterozygous CF patients obtained pre- and during treatment with ELX/TEZ/IVA were analyzed by CFTR Western blot that was optimized to distinguish CFTR glycoisoforms. Findings: CFTR western immunoblot analysis revealed that-compared to baseline-the levels of CFTR protein increased by at least twofold in eight out of 12 patients upon treatment with ELX/TEZ/IVA compared to baseline (p < 0.02). However, polydispersity of the mutant CFTR protein was lower than that of the fully glycosylated wild type CFTR Golgi isoform, indicating an incompletely glycosylated p.Phe508el CFTR protein isoform C* in patients with CF which persists after ELX/TEZ/IVA treatment. Interpretation: Treatment with ELX/TEZ/IVA increased protein expression by facilitating the posttranslational processing of mutant CFTR but apparently did not succeed in generating the polydisperse spectrum of N-linked oligosaccharides that is characteristic for the wild type CFTR band C glycoisoform. Our results caution that the lower amounts or immature glycosylation of the C* glycoisoform observed in patients' biomaterial might not translate to fully restored function of mutant CFTR necessary for long-term provision of clinical benefit.
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Affiliation(s)
- Frauke Stanke
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, Hannover, Germany,*Correspondence: Frauke Stanke,
| | - Sophia T. Pallenberg
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany
| | - Stephanie Tamm
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, Hannover, Germany
| | - Silke Hedtfeld
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany
| | - Ella M. Eichhorn
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany
| | - Rebecca Minso
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany
| | - Gesine Hansen
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, Hannover, Germany
| | - Tobias Welte
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, Hannover, Germany,Department of Respiratory Medicine, Hannover Medical School, Hannover, Germany
| | | | - Felix C. Ringshausen
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, Hannover, Germany,Department of Respiratory Medicine, Hannover Medical School, Hannover, Germany
| | - Sibylle Junge
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany
| | - Burkhard Tümmler
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, Hannover, Germany
| | - Anna-Maria Dittrich
- Department of Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, Hannover, Germany
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4
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Sermet-Gaudelus I, Girodon E, Vermeulen F, Solomon G, Melotti P, Graeber S, Bronsveld I, Rowe S, Wilschanski M, Tümmler B, Cutting G, Gonska T. ECFS standards of care on CFTR-related disorders: Diagnostic criteria of CFTR dysfunction. J Cyst Fibros 2022; 21:922-936. [DOI: 10.1016/j.jcf.2022.09.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Revised: 09/06/2022] [Accepted: 09/14/2022] [Indexed: 11/06/2022]
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5
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Wong SL, Awatade NT, Astore MA, Allan KM, Carnell MJ, Slapetova I, Chen PC, Setiadi J, Pandzic E, Fawcett LK, Widger JR, Whan RM, Griffith R, Ooi CY, Kuyucak S, Jaffe A, Waters SA. Molecular Dynamics and Theratyping in Airway and Gut Organoids Reveal R352Q-CFTR Conductance Defect. Am J Respir Cell Mol Biol 2022; 67:99-111. [PMID: 35471184 PMCID: PMC9273222 DOI: 10.1165/rcmb.2021-0337oc] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
A significant challenge to making targeted cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapies accessible to all individuals with cystic fibrosis (CF) are many mutations in the CFTR gene that can cause CF, most of which remain uncharacterized. Here, we characterized the structural and functional defects of the rare CFTR mutation R352Q, with a potential role contributing to intrapore chloride ion permeation, in patient-derived cell models of the airway and gut. CFTR function in differentiated nasal epithelial cultures and matched intestinal organoids was assessed using an ion transport assay and forskolin-induced swelling assay, respectively. CFTR potentiators (VX-770, GLPG1837, and VX-445) and correctors (VX-809, VX-445, with or without VX-661) were tested. Data from R352Q-CFTR were compared with data of 20 participants with mutations with known impact on CFTR function. R352Q-CFTR has residual CFTR function that was restored to functional CFTR activity by CFTR potentiators but not the corrector. Molecular dynamics simulations of R352Q-CFTR were carried out, which indicated the presence of a chloride conductance defect, with little evidence supporting a gating defect. The combination approach of in vitro patient-derived cell models and in silico molecular dynamics simulations to characterize rare CFTR mutations can improve the specificity and sensitivity of modulator response predictions and aid in their translational use for CF precision medicine.
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Affiliation(s)
- Sharon L Wong
- University of New South Wales, 7800, School of Women's and Children's Health, Faculty of Medicine, Sydney, New South Wales, Australia.,University of New South Wales, 7800, Molecular and Integrative Cystic Fibrosis Research Centre (miCF_RC), Sydney, New South Wales, Australia
| | - Nikhil T Awatade
- University of New South Wales, 7800, School of Women's and Children's Health, Faculty of Medicine, Sydney, New South Wales, Australia.,University of New South Wales, 7800, Molecular and Integrative Cystic Fibrosis Research Centre (miCF_RC), Sydney, New South Wales, Australia
| | - Miro A Astore
- The University of Sydney, 4334, School of Physics, Sydney, New South Wales, Australia
| | - Katelin M Allan
- University of New South Wales, 7800, School of Women's and Children's Health, Faculty of Medicine, Sydney, New South Wales, Australia.,University of New South Wales, 7800, Molecular and Integrative Cystic Fibrosis Research Centre (miCF_RC), Sydney, New South Wales, Australia
| | - Michael J Carnell
- University of New South Wales, 7800, Biomedical Imaging Facility, Mark Wainwright Analytical Centre, Sydney, New South Wales, Australia
| | - Iveta Slapetova
- University of New South Wales, 7800, Biomedical Imaging Facility, Mark Wainwright Analytical Centre, Sydney, New South Wales, Australia
| | - Po-Chia Chen
- The University of Sydney, 4334, School of Physics, Sydney, New South Wales, Australia
| | - Jeffry Setiadi
- The University of Sydney, 4334, School of Physics, Sydney, New South Wales, Australia
| | - Elvis Pandzic
- University of New South Wales, 7800, Biomedical Imaging Facility, Mark Wainwright Analytical Cen, Sydney, New South Wales, Australia
| | - Laura K Fawcett
- University of New South Wales, 7800, School of Women's and Children's Health, Faculty of Medicine, Sydney, New South Wales, Australia.,University of New South Wales, 7800, Molecular and Integrative Cystic Fibrosis Research Centre (miCF_RC), Sydney, New South Wales, Australia.,Sydney Children's Hospital Randwick, 63623, Department of Respiratory Medicine, Randwick, New South Wales, Australia
| | - John R Widger
- University of New South Wales, 7800, School of Women's and Children's Health, Faculty of Medicine, Sydney, New South Wales, Australia.,University of New South Wales, 7800, Molecular and Integrative Cystic Fibrosis Research Centre (miCF_RC), Sydney, New South Wales, Australia.,Sydney Children's Hospital Randwick, 63623, Department of Respiratory Medicine, Randwick, New South Wales, Australia
| | - Renee M Whan
- University of New South Wales, 7800, Biomedical Imaging Facility, Mark Wainwright Analytical Centre, Sydney, New South Wales, Australia
| | - Renate Griffith
- University of New South Wales, 7800, School of Chemistry, Sydney, New South Wales, Australia
| | - Chee Y Ooi
- Sydney Children's Hospital Randwick, Gastroenterology, Sydney, New South Wales, Australia
| | - Serdar Kuyucak
- The University of Sydney, 4334, School of Physics, Sydney, New South Wales, Australia
| | - Adam Jaffe
- Sydney Children`s Hospital, Respiratory Medicine, Sydney, New South Wales, Australia.,University of New South Wales, 7800, School of Women`s and Children`s Health, Sydney, New South Wales, Australia
| | - Shafagh A Waters
- Sydney Children's Hospital, Department of Respiratory Medicine, Sydney, New South Wales, Australia.,Univeristy of New South Wales, School of Women's and Children's Health, Sydney, New South Wales, Australia;
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Lingwood C. Therapeutic Uses of Bacterial Subunit Toxins. Toxins (Basel) 2021; 13:toxins13060378. [PMID: 34073185 PMCID: PMC8226680 DOI: 10.3390/toxins13060378] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/17/2021] [Accepted: 05/18/2021] [Indexed: 02/07/2023] Open
Abstract
The B subunit pentamer verotoxin (VT aka Shiga toxin-Stx) binding to its cellular glycosphingolipid (GSL) receptor, globotriaosyl ceramide (Gb3) mediates internalization and the subsequent receptor mediated retrograde intracellular traffic of the AB5 subunit holotoxin to the endoplasmic reticulum. Subunit separation and cytosolic A subunit transit via the ER retrotranslocon as a misfolded protein mimic, then inhibits protein synthesis to kill cells, which can cause hemolytic uremic syndrome clinically. This represents one of the most studied systems of prokaryotic hijacking of eukaryotic biology. Similarly, the interaction of cholera AB5 toxin with its GSL receptor, GM1 ganglioside, is the key component of the gastrointestinal pathogenesis of cholera and follows the same retrograde transport pathway for A subunit cytosol access. Although both VT and CT are the cause of major pathology worldwide, the toxin–receptor interaction is itself being manipulated to generate new approaches to control, rather than cause, disease. This arena comprises two areas: anti neoplasia, and protein misfolding diseases. CT/CTB subunit immunomodulatory function and anti-cancer toxin immunoconjugates will not be considered here. In the verotoxin case, it is clear that Gb3 (and VT targeting) is upregulated in many human cancers and that there is a relationship between GSL expression and cancer drug resistance. While both verotoxin and cholera toxin similarly hijack the intracellular ERAD quality control system of nascent protein folding, the more widespread cell expression of GM1 makes cholera the toxin of choice as the means to more widely utilise ERAD targeting to ameliorate genetic diseases of protein misfolding. Gb3 is primarily expressed in human renal tissue. Glomerular endothelial cells are the primary VT target but Gb3 is expressed in other endothelial beds, notably brain endothelial cells which can mediate the encephalopathy primarily associated with VT2-producing E. coli infection. The Gb3 levels can be regulated by cytokines released during EHEC infection, which complicate pathogenesis. Significantly Gb3 is upregulated in the neovasculature of many tumours, irrespective of tumour Gb3 status. Gb3 is markedly increased in pancreatic, ovarian, breast, testicular, renal, astrocytic, gastric, colorectal, cervical, sarcoma and meningeal cancer relative to the normal tissue. VT has been shown to be effective in mouse xenograft models of renal, astrocytoma, ovarian, colorectal, meningioma, and breast cancer. These studies are herein reviewed. Both CT and VT (and several other bacterial toxins) access the cell cytosol via cell surface ->ER transport. Once in the ER they interface with the protein folding homeostatic quality control pathway of the cell -ERAD, (ER associated degradation), which ensures that only correctly folded nascent proteins are allowed to progress to their cellular destinations. Misfolded proteins are translocated through the ER membrane and degraded by cytosolic proteosome. VT and CT A subunits have a C terminal misfolded protein mimic sequence to hijack this transporter to enter the cytosol. This interface between exogenous toxin and genetically encoded endogenous mutant misfolded proteins, provides a new therapeutic basis for the treatment of such genetic diseases, e.g., Cystic fibrosis, Gaucher disease, Krabbe disease, Fabry disease, Tay-Sachs disease and many more. Studies showing the efficacy of this approach in animal models of such diseases are presented.
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Affiliation(s)
- Clifford Lingwood
- Division of Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada;
- Departments of Laboratory Medicine & Pathobiology, and Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
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7
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Forskolin-induced swelling of intestinal organoids correlates with disease severity in adults with cystic fibrosis and homozygous F508del mutations. J Cyst Fibros 2019; 19:614-619. [PMID: 31735562 DOI: 10.1016/j.jcf.2019.10.022] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 10/01/2019] [Accepted: 10/22/2019] [Indexed: 12/12/2022]
Abstract
BACKGROUND CFTR function measurements in intestinal organoids may help to better characterise individual disease expression in F508del homozygous people. Our objective was to study correlations between CFTR function as measured with forskolin-induced swelling in rectal organoids with clinical parameters in adult patients with homozygous F508del mutations. METHODS Multicentre observational study. Thirty-four adults underwent rectal biopsy, pulmonary function tests (FEV1 and FVC), chest X-ray and chest CT. Body-mass index (BMI) was assessed at study visit and exacerbation rate was determined during five years prior to study visit. Organoids were cultured and measured after stimulation with 5 µm forskolin for three hours to quantitate CFTR residual function. FINDINGS FIS was positively correlated with FEV1 (r = 0.36, 95% CI 0.02-0.62, p = 0.04) and BMI (r = 0.42, 95% CI 0.09-0.66, p = 0.015). FIS was negatively correlated with PRAGMA-CF CT score for% of disease (r = -0.37, 95% CI -0.62- -0.03, p = 0.049). We found no significant correlation between FIS and chest radiography score for CF (r = -0.16, 95% CI -0.48-0.20, p = 0.44). We observed a trend between higher FIS and a lower mean number of exacerbations over the last 5 years of observation, but this was not statistically significant (Poisson regression, p = 0.089). INTERPRETATION FIS of intestinal organoids varied between subjects with homozygous F508del and correlated with pulmonary and nutritional parameters. These findings suggest that differences at low CFTR residual function may contribute to clinical heterogeneity in F508del homozygous patients and small changes in CFTR residual function might impact long-term disease expression.
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8
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Graeber SY, Dopfer C, Naehrlich L, Gyulumyan L, Scheuermann H, Hirtz S, Wege S, Mairbäurl H, Dorda M, Hyde R, Bagheri-Hanson A, Rueckes-Nilges C, Fischer S, Mall MA, Tümmler B. Effects of Lumacaftor-Ivacaftor Therapy on Cystic Fibrosis Transmembrane Conductance Regulator Function in Phe508del Homozygous Patients with Cystic Fibrosis. Am J Respir Crit Care Med 2019; 197:1433-1442. [PMID: 29327948 DOI: 10.1164/rccm.201710-1983oc] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
RATIONALE The combination of the CFTR (cystic fibrosis transmembrane conductance regulator) corrector lumacaftor with the potentiator ivacaftor has been approved for the treatment of patients with cystic fibrosis homozygous for the Phe508del CFTR mutation. The phase 3 trials examined clinical outcomes but did not evaluate CFTR function in patients. OBJECTIVES To examine the effect of lumacaftor-ivacaftor on biomarkers of CFTR function in Phe508del homozygous patients with cystic fibrosis aged 12 years and older. METHODS This prospective observational study assessed clinical outcomes including FEV1% predicted and body mass index, and CFTR biomarkers including sweat chloride concentration, nasal potential difference, and intestinal current measurement before and 8-16 weeks after initiation of lumacaftor-ivacaftor. MEASUREMENTS AND MAIN RESULTS A total of 53 patients were enrolled in the study, and 52 patients had baseline and follow-up measurements. After initiation of lumacaftor-ivacaftor sweat chloride concentrations were reduced by 17.8 mmol/L (interquartile range [IQR], -25.9 to -6.1; P < 0.001), nasal potential difference showed partial rescue of CFTR function in nasal epithelia to a level of 10.2% (IQR, 0.0-26.1; P < 0.011), and intestinal current measurement showed functional improvement in rectal epithelia to a level of 17.7% of normal (IQR, 10.8-29.0; P < 0.001). All patients improved in at least one CFTR biomarker, but no correlations were found between CFTR biomarker responses and clinical outcomes. CONCLUSIONS Lumacaftor-ivacaftor results in partial rescue of Phe508del CFTR function to levels comparable to the lower range of CFTR activity found in patients with residual function mutations. Functional improvement was detected even in the absence of short-term improvement of FEV1% predicted and body mass index. Clinical trial registered with www.clinicaltrials.gov (NCT02807415).
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Affiliation(s)
- Simon Y Graeber
- 1 Department of Translational Pulmonology.,2 Division of Pediatric Pulmonology and Allergy and Cystic Fibrosis Center, Department of Pediatrics, and.,3 Translational Lung Research Center Heidelberg, German Center for Lung Research, University of Heidelberg, Heidelberg, Germany.,4 Department of Pediatric Pulmonology and Immunology and Cystic Fibrosis Center, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Christian Dopfer
- 5 Clinic of Pediatric Pneumology, Allergology, and Neonatology and.,6 Biomedical Research in Endstage and Obstructive Lung Disease Hannover, German Center for Lung Research, Hannover Medical School, Hannover, Germany
| | - Lutz Naehrlich
- 7 Department of Pediatrics, Justus-Liebig-University Giessen, Giessen, Germany.,8 Universities of Giessen and Marburg Lung Center, German Center for Lung Research, Giessen, Germany
| | - Lena Gyulumyan
- 5 Clinic of Pediatric Pneumology, Allergology, and Neonatology and
| | | | | | - Sabine Wege
- 9 Department of Pneumology and Respiratory Critical Care Medicine, Thoraxklinik, University Hospital Heidelberg, Heidelberg, Germany; and
| | - Heimo Mairbäurl
- 3 Translational Lung Research Center Heidelberg, German Center for Lung Research, University of Heidelberg, Heidelberg, Germany.,9 Department of Pneumology and Respiratory Critical Care Medicine, Thoraxklinik, University Hospital Heidelberg, Heidelberg, Germany; and.,10 Medical Clinic VII, Sports Medicine, Heidelberg University Hospital, Heidelberg, Germany
| | - Marie Dorda
- 5 Clinic of Pediatric Pneumology, Allergology, and Neonatology and.,6 Biomedical Research in Endstage and Obstructive Lung Disease Hannover, German Center for Lung Research, Hannover Medical School, Hannover, Germany
| | - Rebecca Hyde
- 5 Clinic of Pediatric Pneumology, Allergology, and Neonatology and.,6 Biomedical Research in Endstage and Obstructive Lung Disease Hannover, German Center for Lung Research, Hannover Medical School, Hannover, Germany
| | | | - Claudia Rueckes-Nilges
- 7 Department of Pediatrics, Justus-Liebig-University Giessen, Giessen, Germany.,8 Universities of Giessen and Marburg Lung Center, German Center for Lung Research, Giessen, Germany
| | - Sebastian Fischer
- 5 Clinic of Pediatric Pneumology, Allergology, and Neonatology and.,6 Biomedical Research in Endstage and Obstructive Lung Disease Hannover, German Center for Lung Research, Hannover Medical School, Hannover, Germany
| | - Marcus A Mall
- 1 Department of Translational Pulmonology.,2 Division of Pediatric Pulmonology and Allergy and Cystic Fibrosis Center, Department of Pediatrics, and.,3 Translational Lung Research Center Heidelberg, German Center for Lung Research, University of Heidelberg, Heidelberg, Germany.,4 Department of Pediatric Pulmonology and Immunology and Cystic Fibrosis Center, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Burkhard Tümmler
- 5 Clinic of Pediatric Pneumology, Allergology, and Neonatology and.,6 Biomedical Research in Endstage and Obstructive Lung Disease Hannover, German Center for Lung Research, Hannover Medical School, Hannover, Germany
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9
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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.
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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
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10
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de Winter-de Groot KM, Janssens HM, van Uum RT, Dekkers JF, Berkers G, Vonk A, Kruisselbrink E, Oppelaar H, Vries R, Clevers H, Houwen RH, Escher JC, Elias SG, de Jonge HR, de Rijke YB, Tiddens HA, van der Ent CK, Beekman JM. Stratifying infants with cystic fibrosis for disease severity using intestinal organoid swelling as a biomarker of CFTR function. Eur Respir J 2018; 52:13993003.02529-2017. [DOI: 10.1183/13993003.02529-2017] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 07/20/2018] [Indexed: 12/18/2022]
Abstract
Forskolin-induced swelling (FIS) of intestinal organoids from individuals with cystic fibrosis (CF) measures function of the cystic fibrosis transmembrane conductance regulator (CFTR), the protein mutated in CF.We investigated whether FIS corresponds with clinical outcome parameters and biomarkers of CFTR function in 34 infants diagnosed with CF. Relationships with FIS were studied for indicators of pulmonary and gastrointestinal disease.Children with low FIS had higher levels of immunoreactive trypsinogen (p=0.030) and pancreatitis-associated protein (p=0.039), more often had pancreatic insufficiency (p<0.001), had more abnormalities on chest computed tomography (p=0.049), and had lower z-scores for maximal expiratory flow at functional residual capacity (p=0.033) when compared to children with high FIS values. FIS significantly correlated with sweat chloride concentration (SCC) and intestinal current measurement (ICM) (r= −0.82 and r=0.70, respectively; both p<0.001). Individual assessment of SCC, ICM and FIS suggested that FIS can help to classify individual disease severity.Thus, stratification by FIS identified subgroups that differed in pulmonary and gastrointestinal outcome parameters. FIS of intestinal organoids correlated well with established CFTR-dependent biomarkers such as SCC and ICM, and performed adequately at group and individual level in this proof-of-concept study.
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11
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Arora K, Huang Y, Mun K, Yarlagadda S, Sundaram N, Kessler MM, Hannig G, Kurtz CB, Silos-Santiago I, Helmrath M, Palermo JJ, Clancy JP, Steinbrecher KA, Naren AP. Guanylate cyclase 2C agonism corrects CFTR mutants. JCI Insight 2017; 2:93686. [PMID: 28978796 DOI: 10.1172/jci.insight.93686] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 08/29/2017] [Indexed: 01/06/2023] Open
Abstract
Cystic fibrosis (CF) is a genetic disorder in which epithelium-generated fluid flow from the lung, intestine, and pancreas is impaired due to mutations disrupting CF transmembrane conductance regulator (CFTR) channel function. CF manifestations of the pancreas and lung are present in the vast majority of CF patients, and 15% of CF infants are born with obstructed gut or meconium ileus. However, constipation is a significantly underreported outcome of CF disease, affecting 47% of the CF patients, and management becomes critical in the wake of increasing life span of CF patients. In this study, we unraveled a potentially novel molecular role of a membrane-bound cyclic guanosine monophosphate-synthesizing (cGMP-synthesizing) intestinal enzyme, guanylate cyclase 2C (GCC) that could be targeted to ameliorate CF-associated intestinal fluid deficit. We demonstrated that GCC agonism results in functional rescue of murine F508del/F508del and R117H/R117H Cftr and CFTR mutants in CF patient-derived intestinal spheres. GCC coexpression and activation facilitated processing and ER exit of F508del CFTR and presented a potentially novel rescue modality in the intestine, similar to the CF corrector VX-809. Our findings identify GCC as a biological CFTR corrector and potentiator in the intestine.
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Affiliation(s)
- Kavisha Arora
- Division of Pulmonary Medicine, Department of Pediatrics, and
| | - Yunjie Huang
- Division of Pulmonary Medicine, Department of Pediatrics, and
| | - Kyushik Mun
- Division of Pulmonary Medicine, Department of Pediatrics, and
| | | | - Nambirajan Sundaram
- Department of Pediatric General and Thoracic Surgery, Cincinnati Children's Hospital Medical Center (CCHMC), Cincinnati, Ohio, USA
| | | | | | | | | | - Michael Helmrath
- Department of Pediatric General and Thoracic Surgery, Cincinnati Children's Hospital Medical Center (CCHMC), Cincinnati, Ohio, USA
| | - Joseph J Palermo
- Division of Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, and
| | - John P Clancy
- Division of Pulmonary Medicine, Department of Pediatrics, and
| | - Kris A Steinbrecher
- Division of Gastroenterology, Hepatology and Nutrition, CCHMC, Cincinnati, Ohio, USA
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12
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Hohwieler M, Perkhofer L, Liebau S, Seufferlein T, Müller M, Illing A, Kleger A. Stem cell-derived organoids to model gastrointestinal facets of cystic fibrosis. United European Gastroenterol J 2017; 5:609-624. [PMID: 28815024 PMCID: PMC5548342 DOI: 10.1177/2050640616670565] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Accepted: 08/25/2016] [Indexed: 12/16/2022] Open
Abstract
Cystic fibrosis (CF) is one of the most frequently occurring inherited human diseases caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) which lead to ample defects in anion transport and epithelial fluid secretion. Existing models lack both access to early stages of CF development and a coeval focus on the gastrointestinal CF phenotypes, which become increasingly important due increased life span of the affected individuals. Here, we provide a comprehensive overview of gastrointestinal facets of CF and the opportunity to model these in various systems in an attempt to understand and treat CF. A particular focus is given on forward-leading organoid cultures, which may circumvent current limitations of existing models and thereby provide a platform for drug testing and understanding of disease pathophysiology in gastrointestinal organs.
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Affiliation(s)
- Meike Hohwieler
- Department of Internal Medicine 1, University Medical Centre Ulm, Ulm, Germany
| | - Lukas Perkhofer
- Department of Internal Medicine 1, University Medical Centre Ulm, Ulm, Germany
| | - Stefan Liebau
- Institute of Neuroanatomy, Eberhard Karls University Tuebingen, Oesterbergstr. 3, 72074 Tuebingen, Germany
| | - Thomas Seufferlein
- Department of Internal Medicine 1, University Medical Centre Ulm, Ulm, Germany
| | - Martin Müller
- Department of Internal Medicine 1, University Medical Centre Ulm, Ulm, Germany
| | - Anett Illing
- Department of Internal Medicine 1, University Medical Centre Ulm, Ulm, Germany
| | - Alexander Kleger
- Department of Internal Medicine 1, University Medical Centre Ulm, Ulm, Germany
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13
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Vecchio-Pagán B, Blackman SM, Lee M, Atalar M, Pellicore MJ, Pace RG, Franca AL, Raraigh KS, Sharma N, Knowles MR, Cutting GR. Deep resequencing of CFTR in 762 F508del homozygotes reveals clusters of non-coding variants associated with cystic fibrosis disease traits. Hum Genome Var 2016; 3:16038. [PMID: 27917292 PMCID: PMC5121184 DOI: 10.1038/hgv.2016.38] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 09/13/2016] [Accepted: 09/14/2016] [Indexed: 01/09/2023] Open
Abstract
Extensive phenotypic variability is commonly observed in individuals with Mendelian disorders, even among those with identical genotypes in the disease-causing gene. To determine whether variants within and surrounding CFTR contribute to phenotypic variability in cystic fibrosis (CF), we performed deep sequencing of CFTR in 762 patients homozygous for the common CF-causing variant, F508del. In phase 1, ~200 kb encompassing CFTR and extending 10 kb 5' and 5 kb 3' of the gene was sequenced in 486 F508del homozygotes selected from the extremes of sweat chloride concentration. In phase 2, a 510 kb region, which included the entire topologically associated domain of CFTR, was sequenced in 276 F508del homozygotes drawn from extremes of lung function. An additional 163 individuals who carried F508del and a different CF-causing variant were sequenced to inform haplotype construction. Region-based burden testing of both common and rare variants revealed seven regions of significance (α=0.01), five of which overlapped known regulatory elements or chromatin interactions. Notably, the -80 kb locus known to interact with the CFTR promoter was associated with variation in both CF traits. Haplotype analysis revealed a single rare recombination event (1.9% frequency) in intron 15 of CFTR bearing the F508del variant. Otherwise, the majority of F508del chromosomes were markedly similar, consistent with a single origin of the F508del allele. Together, these high-resolution variant analyses of the CFTR locus suggest a role for non-coding regulatory motifs in trait variation among individuals carrying the common CF allele.
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Affiliation(s)
- Briana Vecchio-Pagán
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Scott M Blackman
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Division of Pediatric Endocrinology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Melissa Lee
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Melis Atalar
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Matthew J Pellicore
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Rhonda G Pace
- Cystic Fibrosis-Pulmonary Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Arianna L Franca
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Karen S Raraigh
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Neeraj Sharma
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Michael R Knowles
- Cystic Fibrosis-Pulmonary Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Garry R Cutting
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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14
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Abstract
Cystic Fibrosis (CF) is a rare, multisystem disease leading to significant morbidity and mortality. CF is caused by defects in the cystic fibrosis transmembrane conductance regulator protein (CFTR), a chloride and bicarbonate transporter. Early diagnosis and access to therapies provides benefits in nutrition, pulmonary health, and cognitive ability. Several screening and diagnostic tests are available to support a diagnosis. We discuss the characteristics of screening and diagnostic tests for CF and guideline-based algorithms using these tools to establish a diagnosis. We discuss classification and management of common "diagnostic dilemmas," including the CFTR-related metabolic syndrome and other CFTR-associated diseases.
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Affiliation(s)
- John Brewington
- Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, MLC 2021, 3333 Burnet Avenue, Cincinnati, OH 45229, USA
| | - J P Clancy
- Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, MLC 2021, 3333 Burnet Avenue, Cincinnati, OH 45229, USA.
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15
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Bagheri-Hanson A, Nedwed S, Rueckes-Nilges C, Naehrlich L. Intestinal current measurement versus nasal potential difference measurements for diagnosis of cystic fibrosis: a case-control study. BMC Pulm Med 2014; 14:156. [PMID: 25280757 PMCID: PMC4199064 DOI: 10.1186/1471-2466-14-156] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 09/29/2014] [Indexed: 12/16/2022] Open
Abstract
Background Nasal potential difference (NPD) and intestinal current measurement (ICM) are functional CFTR tests that are used as adjunctive diagnostic tools for cystic fibrosis (CF). Smoking has a systemic negative impact on CFTR function. A diagnostic comparison between NPD and ICM and the impact of smoking on both CFTR tests has not been done. Methods The sweat chloride test, NPD, and ICM were performed in 18 patients with CF (sweat chloride >60 mmol/l), including 6 pancreatic sufficient (PS) patients, and 13 healthy controls, including 8 smokers. The NPD CFTR response to Cl-free and isoproterenol perfusion (Δ0Cl- + Iso) was compared to the ICM CFTR response to forskolin/IBMX, carbachol, and histamine (ΔIsc, forskolin/IBMX+ carbachol+histamine). Results The mean NPD CFTR response and ICM CFTR response between patients with CF and healthy controls was significantly different (p <0.001), but not between patients with CF who were PS and those who were pancreatic insufficient (PI). Smokers have a decreased CFTR response measured by NPD (p = 0.049). For ICM there is a trend towards decreased CFTR response (NS). Three healthy control smokers had NPD responses within the CF-range. In contrast to NPD, there was no overlap of the ICM response between patients with CF and controls. Conclusions ICM is superior to NPD in distinguishing between patients with CF who have a sweat chloride > 60 mmol/l and healthy controls, including smokers. Neither NPD nor ICM differentiated between patients with CF who were PS from those who were PI. Smoking has a negative impact on CFTR function in healthy controls measured by NPD and challenges the diagnostic interpretation of NPD, but not ICM. Electronic supplementary material The online version of this article (doi:10.1186/1471-2466-14-156) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | - Lutz Naehrlich
- Department of Pediatrics, Justus-Liebig-University Giessen, Feulgenstrasse 12, 35385 Giessen, Germany.
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16
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Stanke F, van Barneveld A, Hedtfeld S, Wölfl S, Becker T, Tümmler B. The CF-modifying gene EHF promotes p.Phe508del-CFTR residual function by altering protein glycosylation and trafficking in epithelial cells. Eur J Hum Genet 2013; 22:660-6. [PMID: 24105369 PMCID: PMC3992571 DOI: 10.1038/ejhg.2013.209] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Revised: 07/26/2013] [Accepted: 08/09/2013] [Indexed: 01/07/2023] Open
Abstract
The three-base-pair deletion c.1521_1523delCTT (p.Phe508del, F508del) in the cystic fibrosis transmembrane conductance regulator (CFTR) is the most frequent disease-causing lesion in cystic fibrosis (CF). The CFTR gene encodes a chloride and bicarbonate channel at the apical membrane of epithelial cells. Altered ion transport of CFTR-expressing epithelia can be used to differentiate manifestations of the so-called CF basic defect. Recently, an 11p13 region has been described as a CF modifier by the North American CF Genetic Modifier Study Consortium. Selecting the epithelial-specific transcription factor EHF (ets homologous factor) as the likely candidate gene on 11p13, we have genotyped two intragenic microsatellites in EHF to replicate the 11p13 finding in the patient cohort of the European CF Twin and Sibling Study. We could observe an association of rare EHF haplotypes among homozygotes for c.1521_1523delCTT in CFTR, which exhibit a CF-untypical manifestation of the CF basic defect such as CFTR-mediated residual chloride secretion and low response to amiloride. We have reviewed transcriptome data obtained from intestinal epithelial samples of homozygotes for c.1521_1523delCTT in CFTR, which were stratified for their EHF genetic background. Transcripts that were upregulated among homozygotes for c.1521_1523delCTT in CFTR, who carry two rare EHF alleles, were enriched for genes that alter protein glycosylation and trafficking, both mechanisms being pivotal for the effective targeting of fully functional p.Phe508del-CFTR to the apical membrane of epithelial cells. We conclude that EHF modifies the CF phenotype by altering capabilities of the epithelial cell to correctly process the folding and trafficking of mutant p.Phe508del-CFTR.
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Affiliation(s)
- Frauke Stanke
- 1] Department of Pediatrics, Hannover Medical School, Hannover, Germany [2] Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research, Hannover, Germany
| | - Andrea van Barneveld
- 1] Department of Pediatrics, Hannover Medical School, Hannover, Germany [2] Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research, Hannover, Germany
| | - Silke Hedtfeld
- 1] Department of Pediatrics, Hannover Medical School, Hannover, Germany [2] Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research, Hannover, Germany
| | - Stefan Wölfl
- Institute for Pharmacy and Molecular Biotechnology, Ruperto-Carola University of Heidelberg, Heidelberg, Germany
| | - Tim Becker
- 1] German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany [2] Institute of Medical Biometry, Informatics and Epidemiology, University of Bonn, Bonn, Germany
| | - Burkhard Tümmler
- 1] Department of Pediatrics, Hannover Medical School, Hannover, Germany [2] Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research, Hannover, Germany
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17
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Kotha K, Clancy JP. Ivacaftor treatment of cystic fibrosis patients with the G551D mutation: a review of the evidence. Ther Adv Respir Dis 2013; 7:288-96. [DOI: 10.1177/1753465813502115] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Cystic fibrosis (CF) is a recessive disorder caused by mutations in the gene that encodes the CF transmembrane conductance regulator (CFTR) protein. CFTR protein is a chloride and bicarbonate channel that is critical for normal epithelial ion transport and hydration of epithelial surfaces. Current CF care is supportive, but recent breakthroughs have occurred with the advent of novel therapeutic strategies that assist the function of mutant CFTR proteins. The development and key clinical trial results of ivacaftor, a small molecule that targets gating defects in disease-causing CFTR mutations including G551D CFTR, are summarized in this review. The G551D mutation is reasonably common in the CF patient population and produces a CFTR protein that localizes normally to the plasma membrane, but fails to open in response to cellular cues. Ivacaftor treatment produces dramatic improvements in lung function, weight, lung disease stability, patient-reported outcomes, and CFTR biomarkers in patients with CF harboring the G551D CFTR mutation compared with placebo controls and patients with two copies of the common F508del CFTR mutation. The unprecedented success of ivacaftor treatment for the G551D CF patient population has generated excitement in the CF care community regarding the expansion of its use to other CF patient populations with primary or secondary gating defects.
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Affiliation(s)
- Kavitha Kotha
- Division of Pulmonary Medicine, Department of Pediatrics, Cincinnati Children’s Hospital Medical Center and the University of Cincinnati, Cincinnati, OH, USA
| | - John P. Clancy
- Division of Pulmonary Medicine, Cincinnati Children’s Hospital Medical Center, ML 2021, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, USA
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18
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Servidoni MF, Sousa M, Vinagre AM, Cardoso SR, Ribeiro MA, Meirelles LR, de Carvalho RB, Kunzelmann K, Ribeiro AF, Ribeiro JD, Amaral MD. Rectal forceps biopsy procedure in cystic fibrosis: technical aspects and patients perspective for clinical trials feasibility. BMC Gastroenterol 2013; 13:91. [PMID: 23688510 PMCID: PMC3679995 DOI: 10.1186/1471-230x-13-91] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2012] [Accepted: 05/16/2013] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Measurements of CFTR function in rectal biopsies ex vivo have been used for diagnosis and prognosis of Cystic Fibrosis (CF) disease. Here, we aimed to evaluate this procedure regarding: i) viability of the rectal specimens obtained by biopsy forceps for ex vivo bioelectrical and biochemical laboratory analyses; and ii) overall assessment (comfort, invasiveness, pain, sedation requirement, etc.) of the rectal forceps biopsy procedure from the patients perspective to assess its feasibility as an outcome measure in clinical trials. METHODS We compared three bowel preparation solutions (NaCl 0.9%, glycerol 12%, mannitol), and two biopsy forceps (standard and jumbo) in 580 rectal specimens from 132 individuals (CF and non-CF). Assessment of the overall rectal biopsy procedure (obtained by biopsy forceps) by patients was carried out by telephone surveys to 75 individuals who underwent the sigmoidoscopy procedure. RESULTS Integrity and friability of the tissue specimens correlate with their transepithelial resistance (r = -0.438 and -0.305, respectively) and are influenced by the bowel preparation solution and biopsy forceps used, being NaCl and jumbo forceps the most compatible methods with the electrophysiological analysis. The great majority of the individuals (76%) did not report major discomfort due to the short procedure time (max 15 min) and considered it relatively painless (79%). Importantly, most (88%) accept repeating it at least for one more time and 53% for more than 4 times. CONCLUSIONS Obtaining rectal biopsies with a flexible endoscope and jumbo forceps after bowel preparation with NaCl solution is a safe procedure that can be adopted for both adults and children of any age, yielding viable specimens for CFTR bioelectrical/biochemical analyses. The procedure is well tolerated by patients, demonstrating its feasibility as an outcome measure in clinical trials.
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Affiliation(s)
- Maria F Servidoni
- Gastrocentro - Endoscopy Unit - State University of Campinas (Unicamp) - Cidade Universitária Zeferino Vaz - Barão Geraldo, Campinas, SP 13083-872, Brazil
- Post-graduate Course, Pediatrics Department, State University of Campinas (Unicamp) - Cidade Universitária Zeferino Vaz - Barão Geraldo, Campinas, SP 13083-872, Brazil
| | - Marisa Sousa
- University of Lisboa - Faculty of Sciences, BioFIG - Centre for Biodiversity, Functional and Integrative Genomics, Campo Grande, 1749-016, Lisbon, Portugal
- Department of Genetics, National Institute of Health – Av. Padre Cruz, 1649-016, Lisbon, Portugal
| | - Adriana M Vinagre
- Faculty of Medical Sciences - State University of Campinas (Unicamp) - Cidade Universitária Zeferino Vaz - Barão Geraldo, Campinas, SP 13083-872, Brazil
| | - Silvia R Cardoso
- Post-graduate Course, Pediatrics Department, State University of Campinas (Unicamp) - Cidade Universitária Zeferino Vaz - Barão Geraldo, Campinas, SP 13083-872, Brazil
- Endoscopy Unit – University Hospital of Campinas, Campinas, Brazil
| | - Maria A Ribeiro
- CIPED - Research Center in Pediatrics - State University of Campinas (Unicamp) - Cidade Universitária Zeferino Vaz - Barão Geraldo, Campinas, SP 13083-872, Brazil
| | - Luciana R Meirelles
- Pathological Anatomy Department, University Hospital of Campinas (Unicamp) - Cidade Universitária Zeferino Vaz - Barão Geraldo, Campinas, SP 13083-872, Brazil
| | - Rita B de Carvalho
- Pathological Anatomy Department, University Hospital of Campinas (Unicamp) - Cidade Universitária Zeferino Vaz - Barão Geraldo, Campinas, SP 13083-872, Brazil
| | - Karl Kunzelmann
- Institut für Physiologie - Universität Regensburg, Universitat Strasse 31, D-93053, Regensburg, Germany
| | - Antônio F Ribeiro
- Post-graduate Course, Pediatrics Department, State University of Campinas (Unicamp) - Cidade Universitária Zeferino Vaz - Barão Geraldo, Campinas, SP 13083-872, Brazil
- Faculty of Medical Sciences - State University of Campinas (Unicamp) - Cidade Universitária Zeferino Vaz - Barão Geraldo, Campinas, SP 13083-872, Brazil
- CIPED - Research Center in Pediatrics - State University of Campinas (Unicamp) - Cidade Universitária Zeferino Vaz - Barão Geraldo, Campinas, SP 13083-872, Brazil
| | - José D Ribeiro
- Post-graduate Course, Pediatrics Department, State University of Campinas (Unicamp) - Cidade Universitária Zeferino Vaz - Barão Geraldo, Campinas, SP 13083-872, Brazil
- Faculty of Medical Sciences - State University of Campinas (Unicamp) - Cidade Universitária Zeferino Vaz - Barão Geraldo, Campinas, SP 13083-872, Brazil
- CIPED - Research Center in Pediatrics - State University of Campinas (Unicamp) - Cidade Universitária Zeferino Vaz - Barão Geraldo, Campinas, SP 13083-872, Brazil
| | - Margarida D Amaral
- University of Lisboa - Faculty of Sciences, BioFIG - Centre for Biodiversity, Functional and Integrative Genomics, Campo Grande, 1749-016, Lisbon, Portugal
- Department of Genetics, National Institute of Health – Av. Padre Cruz, 1649-016, Lisbon, Portugal
- Edifício C8, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016, Lisbon, Portugal
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19
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Sousa M, Servidoni MF, Vinagre AM, Ramalho AS, Bonadia LC, Felício V, Ribeiro MA, Uliyakina I, Marson FA, Kmit A, Cardoso SR, Ribeiro JD, Bertuzzo CS, Sousa L, Kunzelmann K, Ribeiro AF, Amaral MD. Measurements of CFTR-mediated Cl- secretion in human rectal biopsies constitute a robust biomarker for Cystic Fibrosis diagnosis and prognosis. PLoS One 2012; 7:e47708. [PMID: 23082198 PMCID: PMC3474728 DOI: 10.1371/journal.pone.0047708] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2012] [Accepted: 09/14/2012] [Indexed: 01/14/2023] Open
Abstract
Background Cystic Fibrosis (CF) is caused by ∼1,900 mutations in the CF transmembrane conductance regulator (CFTR) gene encoding for a cAMP-regulated chloride (Cl−) channel expressed in several epithelia. Clinical features are dominated by respiratory symptoms, but there is variable organ involvement thus causing diagnostic dilemmas, especially for non-classic cases. Methodology/Principal Findings To further establish measurement of CFTR function as a sensitive and robust biomarker for diagnosis and prognosis of CF, we herein assessed cholinergic and cAMP-CFTR-mediated Cl− secretion in 524 freshly excised rectal biopsies from 118 individuals, including patients with confirmed CF clinical diagnosis (n = 51), individuals with clinical CF suspicion (n = 49) and age-matched non-CF controls (n = 18). Conclusive measurements were obtained for 96% of cases. Patients with “Classic CF”, presenting earlier onset of symptoms, pancreatic insufficiency, severe lung disease and low Shwachman-Kulczycki scores were found to lack CFTR-mediated Cl− secretion (<5%). Individuals with milder CF disease presented residual CFTR-mediated Cl− secretion (10–57%) and non-CF controls show CFTR-mediated Cl− secretion ≥30–35% and data evidenced good correlations with various clinical parameters. Finally, comparison of these values with those in “CF suspicion” individuals allowed to confirm CF in 16/49 individuals (33%) and exclude it in 28/49 (57%). Statistical discriminant analyses showed that colonic measurements of CFTR-mediated Cl− secretion are the best discriminator among Classic/Non-Classic CF and non-CF groups. Conclusions/Significance Determination of CFTR-mediated Cl− secretion in rectal biopsies is demonstrated here to be a sensitive, reproducible and robust predictive biomarker for the diagnosis and prognosis of CF. The method also has very high potential for (pre-)clinical trials of CFTR-modulator therapies.
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Affiliation(s)
- Marisa Sousa
- BioFIG - Centre for Biodiversity, Functional and Integrative Genomics; Faculty of Sciences, University of Lisboa, Lisboa, Portugal
- Department of Genetics - National Institute of Health, Lisboa, Portugal
| | - Maria F. Servidoni
- Gastrocentro - Endoscopy Unit - State University of Campinas, Campinas, Brazil
- Pediatrics Department - State University of Campinas, Campinas, Brazil
| | - Adriana M. Vinagre
- Faculty of Medical Sciences - State University of Campinas, Campinas, Brazil
| | - Anabela S. Ramalho
- BioFIG - Centre for Biodiversity, Functional and Integrative Genomics; Faculty of Sciences, University of Lisboa, Lisboa, Portugal
- Department of Genetics - National Institute of Health, Lisboa, Portugal
| | - Luciana C. Bonadia
- Faculty of Medical Sciences - State University of Campinas, Campinas, Brazil
| | - Verónica Felício
- BioFIG - Centre for Biodiversity, Functional and Integrative Genomics; Faculty of Sciences, University of Lisboa, Lisboa, Portugal
| | - Maria A. Ribeiro
- CIPED - Research Center in Pediatrics - State University of Campinas, Campinas, Brazil
| | - Inna Uliyakina
- BioFIG - Centre for Biodiversity, Functional and Integrative Genomics; Faculty of Sciences, University of Lisboa, Lisboa, Portugal
- Department of Genetics - National Institute of Health, Lisboa, Portugal
| | - Fernando A. Marson
- Faculty of Medical Sciences - State University of Campinas, Campinas, Brazil
| | - Arthur Kmit
- Faculty of Medical Sciences - State University of Campinas, Campinas, Brazil
| | - Silvia R. Cardoso
- Pediatrics Department - State University of Campinas, Campinas, Brazil
- Endoscopy Unit – University Hospital of Campinas, Campinas, Brazil
| | - José D. Ribeiro
- Pediatrics Department - State University of Campinas, Campinas, Brazil
- Faculty of Medical Sciences - State University of Campinas, Campinas, Brazil
- CIPED - Research Center in Pediatrics - State University of Campinas, Campinas, Brazil
| | - Carmen S. Bertuzzo
- Faculty of Medical Sciences - State University of Campinas, Campinas, Brazil
| | - Lisete Sousa
- CEAUL - Center of Statistics and Applications of the University of Lisboa; Department of Statistics and Operation Research, Faculty of Sciences, University of Lisboa, Lisboa, Portugal
| | - Karl Kunzelmann
- Institut für Physiologie – University of Regensburg, Regensburg, Germany
| | - Antônio F. Ribeiro
- Pediatrics Department - State University of Campinas, Campinas, Brazil
- Faculty of Medical Sciences - State University of Campinas, Campinas, Brazil
- CIPED - Research Center in Pediatrics - State University of Campinas, Campinas, Brazil
| | - Margarida D. Amaral
- BioFIG - Centre for Biodiversity, Functional and Integrative Genomics; Faculty of Sciences, University of Lisboa, Lisboa, Portugal
- Department of Genetics - National Institute of Health, Lisboa, Portugal
- * E-mail:
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20
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Duranton C, Rubera I, Cougnon M, Melis N, Chargui A, Mograbi B, Tauc M. CFTR is involved in the fine tuning of intracellular redox status: physiological implications in cystic fibrosis. THE AMERICAN JOURNAL OF PATHOLOGY 2012; 181:1367-77. [PMID: 22846720 DOI: 10.1016/j.ajpath.2012.06.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Revised: 05/15/2012] [Accepted: 06/11/2012] [Indexed: 01/11/2023]
Abstract
Adaptation to hypoxia is an essential physiological response to decrease in tissue oxygenation. This process is primarily under the control of transcriptional activator hypoxia-inducible factor (HIF1). A better understanding of the intracellular HIF1 stabilization pathway would help in management of various diseases characterized by anemia. Among human pathologies, cystic fibrosis disease is characterized by a chronic anemia that is inadequately compensated by the classical erythroid response mediated by the HIF pathway. Because the kidney expresses CFTR and is a master organ involved in the adaptation to hypoxia, we used renal cells to explore the relationship between CFTR and the HIF1-mediated pathway. To monitor the adaptive response to hypoxia, we engineered a hypoxia-induced fluorescent reporter system to determine whether CFTR modulates hypoxia-induced HIF1 stabilization. We show that CFTR is a regulator of HIF stabilization by controlling the intracellular reactive oxygen species (ROS) level through its ability to transport glutathione (a ROS scavenger) out of the cell. Moreover, we demonstrated in a mouse model that both the pharmacological inhibition and the ΔF508 mutation of CFTR lead to an impairment of the adaptive erythroid response to oxygen deprivation. We conclude that CFTR controls HIF stabilization through control of the level of intracellular ROS that act as signaling agents in the HIF-1 pathway.
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Affiliation(s)
- Christophe Duranton
- Faculties of Sciences LP2M CNRS-3472, University of Nice-Sophia Antipolis, Nice, France
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21
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Xiao F, Li J, Singh AK, Riederer B, Wang J, Sultan A, Park H, Lee MG, Lamprecht G, Scholte BJ, De Jonge HR, Seidler U. Rescue of epithelial HCO3- secretion in murine intestine by apical membrane expression of the cystic fibrosis transmembrane conductance regulator mutant F508del. J Physiol 2012; 590:5317-34. [PMID: 22802588 DOI: 10.1113/jphysiol.2012.232124] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
This study investigated whether expression of the common cystic fibrosis transmembrane conductance regulator (CFTR) mutant F508del in the apical membrane of enterocytes confers increased bicarbonate secretory capacity on the intestinal epithelium of F508del mutant mice compared to that of CFTR knockout (KO) mice. CFTR KO mice, F508del mutant mice (F508del) and wild-type (WT) littermates were bred on the FVB/N background. F508del isolated brush border membrane (BBM) contained approximately 5-10% fully glycosylated band C protein compared to WT BBM. Similarly, the forskolin (FSK)-induced, CFTR-dependent short-circuit current (I(sc)) of F508del mucosa was approximately 5-10% of WT, whereas the HCO(3)(-) secretory response ( ) was almost half that of WT in both duodenum and mid-colon studied in vitro and in vivo. While WT intestine retained full FSK-induced in the absence of luminal Cl(-), the markedly higher than I(sc) in F508del intestine was dependent on the presence of luminal Cl(-), and was blocked by CFTR inhibitors. The Ste20-related proline-alanine-rich kinases (SPAK/OSR1), which are downstream of the with-no-lysine (K) protein kinases (WNK), were rapidly phosphorylated by FSK in WT and F508del, but significantly more slowly in CFTR KO intestine. In conclusion, the data demonstrate that low levels of F508del membrane expression in the intestine of F508del mice significantly increased FSK-induced HCO(3)(-) secretion mediated by Cl(-)/HCO(3)(-) exchange. However, in WT mucosa FSK elicited strong SPAK/OSR1 phosphorylation and Cl(-)-independent HCO(3)(-) efflux. This suggests that therapeutic strategies which deliver F508del to the apical membrane have the potential to significantly enhance epithelial HCO(3)(-) secretion.
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Affiliation(s)
- Fang Xiao
- Department of Gastoenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
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22
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He L, Skirkanich J, Moronetti L, Lewis R, Lamitina T. The cystic-fibrosis-associated ΔF508 mutation confers post-transcriptional destabilization on the C. elegans ABC transporter PGP-3. Dis Model Mech 2012; 5:930-9. [PMID: 22569626 PMCID: PMC3484874 DOI: 10.1242/dmm.008987] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Membrane proteins make up ∼30% of the proteome. During the early stages of maturation, this class of proteins can experience localized misfolding in distinct cellular compartments, such as the cytoplasm, endoplasmic reticulum (ER) lumen and ER membrane. ER quality control (ERQC) mechanisms monitor folding and determine whether a membrane protein is appropriately folded or is misfolded and warrants degradation. ERQC plays crucial roles in human diseases, such as cystic fibrosis, in which deletion of a single amino acid (F508) results in the misfolding and degradation of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl– channel. We introduced the ΔF508 mutation into Caenorhabditis elegans PGP-3, a 12-transmembrane ABC transporter with 15% identity to CFTR. When expressed in intestinal epithelial cells, PGP-3wt was stable and efficiently trafficked to the apical plasma membrane through a COPII-dependent mechanism. However, PGP-3ΔF508 was post-transcriptionally destabilized, resulting in reduced total and apical membrane protein levels. Genetic or physiological activation of the osmotic stress response pathway, which causes accumulation of the chemical chaperone glycerol, stabilized PGP-3ΔF508. Efficient degradation of PGP-3ΔF508 required the function of several C. elegans ER-associated degradation (ERAD) homologs, suggesting that destabilization occurs through an ERAD-type mechanism. Our studies show that the ΔF508 mutation causes post-transcriptional destabilization and degradation of PGP-3 in C. elegans epithelial cells. This model, combined with the power of C. elegans genetics, provides a new opportunity to genetically dissect metazoan ERQC.
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Affiliation(s)
- Liping He
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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Li Y, Ganta S, Fong P. Endogenous surface expression of ΔF508-CFTR mediates cAMP-stimulated Cl(-) current in CFTR(ΔF508/ΔF508) pig thyroid epithelial cells. Exp Physiol 2011; 97:115-24. [PMID: 21948195 DOI: 10.1113/expphysiol.2011.060756] [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]
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) is both an anion channel and a regulator of other transport proteins. Mutations in the CFTR gene underlie the human disease, cystic fibrosis. The most common CFTR mutation, ΔF508, produces a misfolded protein which traffics improperly. The availability of transgenic CFTR(ΔF508/ΔF508) pigs allows measurement of the impact of ΔF508 in native tissue. Thyroid epithelia respond to cAMP-elevating agents by increasing anion transport, a process reliant on functional CFTR. To assess whether endogenous levels of ΔF508-CFTR mediate thyroid transport, primary thyroid epithelial cultures (pThECs) were grown from newborn CFTR(+/+) (wild-type) and CFTR(ΔF508/ΔF508) (ΔF) pig thyroids and the stimulated, secretory components of short-circuit current (I(sc)) compared. Surface biotinylation studies assessed the surface presentation of ΔF508-CFTR. Baseline I(sc) levels of both wild-type and ΔF pThECs consisted of an amiloride-sensitive component. In ΔF pThECs, this mirrored previous measurements in CFTR(-/-) (knockout) pThECs. Surprisingly, elevation of cAMP transiently increased I(sc) to peak levels ∼65% of those achieved by wild-type. In contrast, knockout pThECs were indifferent to cAMP activation. In ΔF pThECs, total ΔF508-CFTR expression was ∼9% that of wild-type, consistent with misfolding and enhanced degradation. Surface biotinylation studies indicated that ∼4% of the total ΔF508 resided at the surface and did not increase with cAMP elevation. The present findings show that low endogenous levels of pig ΔF508-CFTR can mediate substantial anion transport by thyroid epithelia. These data suggest that both wild-type and ΔF508-CFTR regulate additional thyroid transporters, and together co-ordinate the overall I(sc) response.
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Affiliation(s)
- Yonghai Li
- Department of Anatomy and Physiology, Kansas State University College of Veterinary Medicine, 1600 Denison Avenue, Manhattan, KS 66506, USA
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24
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Ostedgaard LS, Meyerholz DK, Chen JH, Pezzulo AA, Karp PH, Rokhlina T, Ernst SE, Hanfland RA, Reznikov LR, Ludwig PS, Rogan MP, Davis GJ, Dohrn CL, Wohlford-Lenane C, Taft PJ, Rector MV, Hornick E, Nassar BS, Samuel M, Zhang Y, Richter SS, Uc A, Shilyansky J, Prather RS, McCray PB, Zabner J, Welsh MJ, Stoltz DA. The ΔF508 mutation causes CFTR misprocessing and cystic fibrosis-like disease in pigs. Sci Transl Med 2011; 3:74ra24. [PMID: 21411740 DOI: 10.1126/scitranslmed.3001868] [Citation(s) in RCA: 160] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Cystic fibrosis (CF) is an autosomal recessive disease caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) anion channel. The most common CF-associated mutation is ΔF508, which deletes a phenylalanine in position 508. In vitro studies indicate that the resultant protein, CFTR-ΔF508, is misprocessed, although the in vivo consequences of this mutation remain uncertain. To better understand the effects of the ΔF508 mutation in vivo, we produced CFTR(ΔF508/ΔF508) pigs. Our biochemical, immunocytochemical, and electrophysiological data on CFTR-ΔF508 in newborn pigs paralleled in vitro predictions. They also indicated that CFTR(ΔF508/ΔF508) airway epithelia retain a small residual CFTR conductance, with maximal stimulation producing ~6% of wild-type function. Cyclic adenosine 3',5'-monophosphate (cAMP) agonists were less potent at stimulating current in CFTR(Δ)(F508/)(Δ)(F508) epithelia, suggesting that quantitative tests of maximal anion current may overestimate transport under physiological conditions. Despite residual CFTR function, four older CFTR(ΔF508/ΔF508) pigs developed lung disease similar to human CF. These results suggest that this limited CFTR activity is insufficient to prevent lung or gastrointestinal disease in CF pigs. These data also suggest that studies of recombinant CFTR-ΔF508 misprocessing predict in vivo behavior, which validates its use in biochemical and drug discovery experiments. These findings help elucidate the molecular pathogenesis of the common CF mutation and will guide strategies for developing new therapeutics.
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Affiliation(s)
- Lynda S Ostedgaard
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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25
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Stanke F, Hedtfeld S, Becker T, Tümmler B. An association study on contrasting cystic fibrosis endophenotypes recognizes KRT8 but not KRT18 as a modifier of cystic fibrosis disease severity and CFTR mediated residual chloride secretion. BMC MEDICAL GENETICS 2011; 12:62. [PMID: 21548936 PMCID: PMC3107781 DOI: 10.1186/1471-2350-12-62] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Accepted: 05/06/2011] [Indexed: 12/23/2022]
Abstract
Background F508del-CFTR, the most frequent disease-causing mutation among Caucasian cystic fibrosis (CF) patients, has been characterised as a mutant defective in protein folding, processing and trafficking. We have investigated the two neighbouring cytokeratin genes KRT8 and KRT18 in a candidate gene approach to ask whether variants in KRT8 and/or KRT18 modify the impaired ion conductance known as the CF basic defect, and whether they are associated with correct trafficking of mutant CFTR and disease severity of CF. Methods We have selected contrasting F508del-CFTR homozygous patient subpopulations stratified for disease severity, comparing 13 concordant mildly affected sib pairs vs. 12 concordant severely affected sib pairs, or manifestation of the CF basic defect in intestinal epithelium, comparing 22 individuals who exhibit CFTR-mediated residual chloride secretion vs. 14 individuals who do not express any chloride secretion, for an association. The KRT8/KRT18 locus was initially interrogated with one informative microsatellite marker. Subsequently, a low density SNP map with four SNPs in KRT8 and two SNPs in KRT18, each selected for high polymorphism content, was used to localize the association signal. Results KRT8, but not KRT18, showed an association with CF disease severity (Pbest = 0.00131; Pcorr = 0.0185) and CFTR mediated residual chloride secretion (Pbest = 0.0004; Pcorr = 0.0069). Two major four-marker-haplotypes spanning 13 kb including the entire KRT8 gene accounted for 90% of chromosomes, demonstrating strong linkage disequilibrium at that locus. Absence of chloride secretion was associated with the recessive haplotype 1122 at rs1907671, rs4300473, rs2035878 and rs2035875. The contrasting haplotype 2211 was dominant for the presence of CFTR mediated residual chloride secretion. In consistency, the KRT8 haplotype 2211 was associated with mild CF disease while 1122 was observed as risk haplotype. Analysis of microsatellite allele distributions on the SNP background suggests that the mild KRT8 haplotype 2211 is phylogenetically older than its severe counterpart. Conclusions The two opposing KRT8 alleles which have been identified as a benign and as a risk allele in this work are likely effective in the context of epithelial cell differentiation. As the mild KRT8 allele is associated with CFTR mediated residual chloride secretion among F508del-CFTR homozygotes, the KRT8/KRT18 heterodimeric intermediary filaments of the cytoskeleton apparently are an essential component for the proper targeting of CFTR to the apical membrane in epithelial cells.
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Affiliation(s)
- Frauke Stanke
- Department of Pediatrics, Hannover Medical School, Hannover, Germany.
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