51
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Spanò V, Montalbano A, Carbone A, Scudieri P, Galietta LJV, Barraja P. An overview on chemical structures as ΔF508-CFTR correctors. Eur J Med Chem 2019; 180:430-448. [PMID: 31326599 DOI: 10.1016/j.ejmech.2019.07.037] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 07/09/2019] [Accepted: 07/10/2019] [Indexed: 10/26/2022]
Abstract
Deletion of phenylalanine at position 508 (F508del) in the CFTR protein, is the most common mutation causing cystic fibrosis (CF). F508del causes misfolding and rapid degradation of CFTR protein a defect that can be targeted with pharmacological agents termed "correctors". Correctors belong to various chemical classes but are generally small molecules based on nitrogen sulfur or oxygen heterocycles. The mechanism of action of correctors is generally unknown but there is experimental evidence that some of them can directly act on mutant CFTR improving folding and stability. Here we overview the characteristics of the various F508del correctors described so far to obtain indications on key chemical structures and modifications that are required for mutant protein rescue.
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Affiliation(s)
- Virginia Spanò
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Via Archirafi 32, 90123, Palermo, Italy
| | - Alessandra Montalbano
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Via Archirafi 32, 90123, Palermo, Italy
| | - Anna Carbone
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Via Archirafi 32, 90123, Palermo, Italy
| | - Paolo Scudieri
- Telethon Institute of Genetics and Medicine (TIGEM), Campi Flegrei 34, 80078, Pozzuoli, NA, Italy
| | - Luis J V Galietta
- Telethon Institute of Genetics and Medicine (TIGEM), Campi Flegrei 34, 80078, Pozzuoli, NA, Italy; Department of Translational Medical Sciences (DISMET), University of Naples, "Federico II", 80131, Naples, Italy
| | - Paola Barraja
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Via Archirafi 32, 90123, Palermo, Italy.
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52
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Huang Y, Arora K, Mun KS, Yang F, Moon C, Yarlagadda S, Jegga A, Weaver T, Naren AP. Targeting DNAJB9, a novel ER luminal co-chaperone, to rescue ΔF508-CFTR. Sci Rep 2019; 9:9808. [PMID: 31285458 PMCID: PMC6614449 DOI: 10.1038/s41598-019-46161-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 06/19/2019] [Indexed: 01/30/2023] Open
Abstract
The molecular mechanism of Endoplasmic Reticulum-associated degradation (ERAD) of Cystic fibrosis transmembrane-conductance regulator (CFTR) is largely unknown. Particularly, it is unknown what ER luminal factor(s) are involved in ERAD. Herein, we used ProtoArray to identify an ER luminal co-chaperone, DNAJB9, which can directly interact with CFTR. For both WT- and ΔF508 (deletion of phenylalanine at position 508, the most common CF-causing mutant)-CFTR, knockdown of DNAJB9 by siRNA increased their expression levels on the cell surface and, consequently, upregulated their function. Furthermore, genetic ablation of DNAJB9 in WT mice increased CFTR expression and enhanced CFTR-dependent fluid secretion in enteroids. Importantly, DNAJB9 deficiency upregulated enteroids' fluid secretion in CF mice (homozygous for ΔF508), and silencing one allele of DNAJB9 is sufficient to rescue ΔF508-CFTR in vitro and in vivo, suggesting that DNAJB9 may be a rate-limiting factor in CFTR ERAD pathway. Our studies identified the first ER luminal co-chaperone involved in CFTR ERAD, and DNAJB9 could be a novel therapeutic target for CF.
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Affiliation(s)
- Yunjie Huang
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States
| | - Kavisha Arora
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States
| | - Kyu Shik Mun
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States
| | - Fanmuyi Yang
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States
| | - ChangSuk Moon
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States
| | - Sunitha Yarlagadda
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States
| | - Anil Jegga
- Division of Biomedical Informatics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States
| | - Timothy Weaver
- Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States
| | - Anjaparavanda P Naren
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, United States.
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53
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Donato M, Geisler M. HSP
90 and co‐chaperones: a multitaskers’ view on plant hormone biology. FEBS Lett 2019; 593:1415-1430. [DOI: 10.1002/1873-3468.13499] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 06/12/2019] [Accepted: 06/12/2019] [Indexed: 12/30/2022]
Affiliation(s)
- Martin Donato
- Department of Biology University of Fribourg Switzerland
| | - Markus Geisler
- Department of Biology University of Fribourg Switzerland
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54
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Hanrahan JW, Sato Y, Carlile GW, Jansen G, Young JC, Thomas DY. Cystic Fibrosis: Proteostatic correctors of CFTR trafficking and alternative therapeutic targets. Expert Opin Ther Targets 2019; 23:711-724. [PMID: 31169041 DOI: 10.1080/14728222.2019.1628948] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Introduction: Cystic fibrosis (CF) is the most frequent lethal orphan disease and is caused by mutations in the CFTR gene. The most frequent mutation F508del-CFTR affects multiple organs; infections and subsequent infections and complications in the lung lead to death. Areas covered: This review focuses on new targets and mechanisms that are attracting interest for the development of CF therapies. The F508del-CFTR protein is retained in the endoplasmic reticulum (ER) but has some function if it can traffic to the plasma membrane. Cell-based assays have been used to screen chemical libraries for small molecule correctors that restore its trafficking. Pharmacological chaperones are correctors that bind directly to the F508del-CFTR mutant and promote its folding and trafficking. Other correctors fall into a heterogeneous class of proteostasis modulators that act indirectly by altering cellular homeostasis. Expert opinion: Pharmacological chaperones have so far been the most successful correctors of F508del-CFTR trafficking, but their level of correction means that more than one corrector is required. Proteostasis modulators have low levels of correction but hold promise because some can correct several different CFTR mutations. Identification of their cellular targets and the potential for development may lead to new therapies for CF.
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Affiliation(s)
- John W Hanrahan
- a Department of Physiology , McGill University , Montréal , QC , Canada.,c Research Institute of the McGill University Health Centre , McGill University , Montréal , QC , Canada
| | - Yukiko Sato
- a Department of Physiology , McGill University , Montréal , QC , Canada.,b Cystic Fibrosis Translational Research centre , McGill University , Montréal , QC , Canada
| | - Graeme W Carlile
- b Cystic Fibrosis Translational Research centre , McGill University , Montréal , QC , Canada.,d Department of Biochemistry , McGill University , Montréal , QC , Canada
| | - Gregor Jansen
- d Department of Biochemistry , McGill University , Montréal , QC , Canada
| | - Jason C Young
- b Cystic Fibrosis Translational Research centre , McGill University , Montréal , QC , Canada.,d Department of Biochemistry , McGill University , Montréal , QC , Canada
| | - David Y Thomas
- b Cystic Fibrosis Translational Research centre , McGill University , Montréal , QC , Canada.,d Department of Biochemistry , McGill University , Montréal , QC , Canada.,e Department of Human Genetics , McGill University , Montréal , QC , Canada
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55
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Marinko J, Huang H, Penn WD, Capra JA, Schlebach JP, Sanders CR. Folding and Misfolding of Human Membrane Proteins in Health and Disease: From Single Molecules to Cellular Proteostasis. Chem Rev 2019; 119:5537-5606. [PMID: 30608666 PMCID: PMC6506414 DOI: 10.1021/acs.chemrev.8b00532] [Citation(s) in RCA: 162] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Indexed: 12/13/2022]
Abstract
Advances over the past 25 years have revealed much about how the structural properties of membranes and associated proteins are linked to the thermodynamics and kinetics of membrane protein (MP) folding. At the same time biochemical progress has outlined how cellular proteostasis networks mediate MP folding and manage misfolding in the cell. When combined with results from genomic sequencing, these studies have established paradigms for how MP folding and misfolding are linked to the molecular etiologies of a variety of diseases. This emerging framework has paved the way for the development of a new class of small molecule "pharmacological chaperones" that bind to and stabilize misfolded MP variants, some of which are now in clinical use. In this review, we comprehensively outline current perspectives on the folding and misfolding of integral MPs as well as the mechanisms of cellular MP quality control. Based on these perspectives, we highlight new opportunities for innovations that bridge our molecular understanding of the energetics of MP folding with the nuanced complexity of biological systems. Given the many linkages between MP misfolding and human disease, we also examine some of the exciting opportunities to leverage these advances to address emerging challenges in the development of therapeutics and precision medicine.
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Affiliation(s)
- Justin
T. Marinko
- Department
of Biochemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
- Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Hui Huang
- Department
of Biochemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
- Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Wesley D. Penn
- Department
of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - John A. Capra
- Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37240, United States
- Department
of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37245, United States
| | - Jonathan P. Schlebach
- Department
of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Charles R. Sanders
- Department
of Biochemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
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56
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Roushar FJ, Gruenhagen TC, Penn WD, Li B, Meiler J, Jastrzebska B, Schlebach JP. Contribution of Cotranslational Folding Defects to Membrane Protein Homeostasis. J Am Chem Soc 2018; 141:204-215. [PMID: 30537820 DOI: 10.1021/jacs.8b08243] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Membrane proteins are prone to misfolding and degradation within the cell, yet the nature of the conformational defects involved in this process remain poorly understood. The earliest stages of membrane protein folding are mediated by the Sec61 translocon, a molecular machine that facilitates the lateral partitioning of the polypeptide into the membrane. Proper membrane integration is an essential prerequisite for folding of the nascent chain. However, the marginal energetic drivers of this reaction suggest the translocon may operate with modest fidelity. In this work, we employed biophysical modeling in conjunction with quantitative biochemical measurements in order to evaluate the extent to which cotranslational folding defects influence membrane protein homeostasis. Protein engineering was employed to selectively perturb the topological energetics of human rhodopsin, and the expression and cellular trafficking of engineered variants were quantitatively compared. Our results reveal clear relationships between topological energetics and the efficiency of rhodopsin biogenesis, which appears to be limited by the propensity of a polar transmembrane domain to achieve its correct topological orientation. Though the polarity of this segment is functionally constrained, we find that its topology can be stabilized in a manner that enhances biogenesis without compromising the functional properties of rhodopsin. Furthermore, sequence alignments reveal this topological instability has been conserved throughout the course of evolution. These results suggest that topological defects significantly contribute to the inefficiency of membrane protein folding in the cell. Additionally, our findings suggest that the marginal stability of rhodopsin may represent an evolved trait.
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Affiliation(s)
- Francis J Roushar
- Department of Chemistry , Indiana University , Bloomington , Indiana 47405 , United States
| | - Timothy C Gruenhagen
- Department of Chemistry , Indiana University , Bloomington , Indiana 47405 , United States
| | - Wesley D Penn
- Department of Chemistry , Indiana University , Bloomington , Indiana 47405 , United States
| | - Bian Li
- Department of Chemistry , Vanderbilt University , Nashville , Tennessee 37235 , United States
| | - Jens Meiler
- Department of Chemistry , Vanderbilt University , Nashville , Tennessee 37235 , United States
| | - Beata Jastrzebska
- Department of Pharmacology , Case Western Reserve University , Cleveland , Ohio 44106 , United States
| | - Jonathan P Schlebach
- Department of Chemistry , Indiana University , Bloomington , Indiana 47405 , United States
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57
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Brand JD, Lazrak A, Trombley JE, Shei RJ, Adewale AT, Tipper JL, Yu Z, Ashtekar AR, Rowe SM, Matalon S, Harrod KS. Influenza-mediated reduction of lung epithelial ion channel activity leads to dysregulated pulmonary fluid homeostasis. JCI Insight 2018; 3:123467. [PMID: 30333319 DOI: 10.1172/jci.insight.123467] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 09/06/2018] [Indexed: 02/06/2023] Open
Abstract
Severe influenza (IAV) infection can develop into bronchopneumonia and edema, leading to acquired respiratory distress syndrome (ARDS) and pathophysiology. Underlying causes for pulmonary edema and aberrant fluid regulation largely remain unknown, particularly regarding the role of viral-mediated mechanisms. Herein, we show that distinct IAV strains reduced the functions of the epithelial sodium channel (ENaC) and the cystic fibrosis transmembrane regulator (CFTR) in murine respiratory and alveolar epithelia in vivo, as assessed by measurements of nasal potential differences and single-cell electrophysiology. Reduced ion channel activity was distinctly limited to virally infected cells in vivo and not bystander uninfected lung epithelium. Multiple lines of evidence indicated ENaC and CFTR dysfunction during the acute infection period; however, only CFTR dysfunction persisted beyond the infection period. ENaC, CFTR, and Na,K-ATPase activities and protein levels were also reduced in virally infected human airway epithelial cells. Reduced ENaC and CFTR led to changes in airway surface liquid morphology of human tracheobronchial cultures and airways of IAV-infected mice. Pharmacologic correction of CFTR function ameliorated IAV-induced physiologic changes. These changes are consistent with mucous stasis and pulmonary edema; furthermore, they indicate that repurposing therapeutic interventions correcting CFTR dysfunction may be efficacious for treatment of IAV lung pathophysiology.
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Affiliation(s)
- Jeffrey D Brand
- Department of Anesthesiology and Perioperative Medicine, Division of Molecular and Translational Biomedicine
| | - Ahmed Lazrak
- Department of Anesthesiology and Perioperative Medicine, Division of Molecular and Translational Biomedicine
| | - John E Trombley
- Department of Anesthesiology and Perioperative Medicine, Division of Molecular and Translational Biomedicine
| | - Ren-Jay Shei
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care, and.,Gregory Fleming James Cystic Fibrosis Research Center, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - A Timothy Adewale
- Gregory Fleming James Cystic Fibrosis Research Center, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jennifer L Tipper
- Department of Anesthesiology and Perioperative Medicine, Division of Molecular and Translational Biomedicine
| | - Zhihong Yu
- Department of Anesthesiology and Perioperative Medicine, Division of Molecular and Translational Biomedicine
| | - Amit R Ashtekar
- Department of Anesthesiology and Perioperative Medicine, Division of Molecular and Translational Biomedicine
| | - Steven M Rowe
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care, and.,Gregory Fleming James Cystic Fibrosis Research Center, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Sadis Matalon
- Department of Anesthesiology and Perioperative Medicine, Division of Molecular and Translational Biomedicine
| | - Kevin S Harrod
- Department of Anesthesiology and Perioperative Medicine, Division of Molecular and Translational Biomedicine
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58
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Fay JF, Aleksandrov LA, Jensen TJ, Cui LL, Kousouros JN, He L, Aleksandrov AA, Gingerich DS, Riordan JR, Chen JZ. Cryo-EM Visualization of an Active High Open Probability CFTR Anion Channel. Biochemistry 2018; 57:6234-6246. [PMID: 30281975 DOI: 10.1021/acs.biochem.8b00763] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) anion channel, crucial to epithelial salt and water homeostasis, and defective due to mutations in its gene in patients with cystic fibrosis, is a unique member of the large family of ATP-binding cassette transport proteins. Regulation of CFTR channel activity is stringently controlled by phosphorylation and nucleotide binding. Structural changes that underlie transitions between active and inactive functional states are not yet fully understood. Indeed the first 3D structures of dephosphorylated, ATP-free, and phosphorylated ATP-bound states were only recently reported. Here we have determined the structure of inactive and active states of a thermally stabilized CFTR, the latter with a very high channel open probability, confirmed after reconstitution into proteoliposomes. These structures, obtained at nominal resolution of 4.3 and 6.6 Å, reveal a unique repositioning of the transmembrane helices and regulatory domain density that provide insights into the structural transition between active and inactive functional states of CFTR. Moreover, we observe an extracellular vestibule that may provide anion access to the pore due to the conformation of transmembrane helices 7 and 8 that differs from the previous orthologue CFTR structures. In conclusion, our work contributes detailed structural information on an active, open state of the CFTR anion channel.
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Affiliation(s)
- Jonathan F Fay
- University of North Carolina , Chapel Hill , North Carolina 27515 , United States
| | - Luba A Aleksandrov
- University of North Carolina , Chapel Hill , North Carolina 27515 , United States
| | - Timothy J Jensen
- University of North Carolina , Chapel Hill , North Carolina 27515 , United States
| | - Liying L Cui
- University of North Carolina , Chapel Hill , North Carolina 27515 , United States
| | - Joseph N Kousouros
- University of North Carolina , Chapel Hill , North Carolina 27515 , United States
| | - Lihua He
- University of North Carolina , Chapel Hill , North Carolina 27515 , United States
| | - Andrei A Aleksandrov
- University of North Carolina , Chapel Hill , North Carolina 27515 , United States
| | - Drew S Gingerich
- Oregon Health & Science University , Portland , Oregon 97239 , United States
| | - John R Riordan
- University of North Carolina , Chapel Hill , North Carolina 27515 , United States
| | - James Z Chen
- Oregon Health & Science University , Portland , Oregon 97239 , United States
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59
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A minimal helical-hairpin motif provides molecular-level insights into misfolding and pharmacological rescue of CFTR. Commun Biol 2018; 1:154. [PMID: 30302398 PMCID: PMC6162264 DOI: 10.1038/s42003-018-0153-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 08/24/2018] [Indexed: 12/11/2022] Open
Abstract
Our meagre understanding of CFTR misfolding and its reversal by small-molecule correctors hampers the development of mechanism-based therapies of cystic fibrosis. Here we exploit a helical-hairpin construct—the simplest proxy of membrane-protein tertiary contacts—containing CFTR’s transmembrane helices 3 and 4 and its corresponding disease phenotypic mutant V232D to gain molecular-level insights into CFTR misfolding and drug rescue by the corrector Lumacaftor. Using a single-molecule FRET approach to study hairpin conformations in lipid bilayers, we find that the wild-type hairpin is well folded, whereas the V232D mutant assumes an open conformation in bilayer thicknesses mimicking the endoplasmic reticulum. Addition of Lumacaftor reverses the aberrant opening of the mutant hairpin to restore a compact state as in the wild type. The observed membrane escape of the V232D hairpin and its reversal by Lumacaftor complement cell-based analyses of the full-length protein, thereby providing in vivo and in vitro correlates of CFTR misfolding and drug-action mechanisms. Georg Krainer and Antoine Treff et al. use a helical-hairpin construct derived from the cystic fibrosis transmembrane conductance regulator (CFTR) to investigate misfolding caused by the disease-linked V232D mutation. Using single-molecule FRET, they show that the V232D hairpin assumes an open conformation in lipid bilayers, which is reversed by the pharmacological corrector Lumacaftor.
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60
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Fukuda R, Okiyoneda T. Peripheral Protein Quality Control as a Novel Drug Target for CFTR Stabilizer. Front Pharmacol 2018; 9:1100. [PMID: 30319426 PMCID: PMC6170605 DOI: 10.3389/fphar.2018.01100] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 09/10/2018] [Indexed: 12/12/2022] Open
Abstract
Conformationally defective cystic fibrosis transmembrane conductance regulator (CFTR) including rescued ΔF508-CFTR is rapidly eliminated from the plasma membrane (PM) even in the presence of a CFTR corrector and potentiator, limiting the therapeutic effort of the combination therapy. CFTR elimination from the PM is determined by the conformation-dependent ubiquitination as a part of the peripheral quality control (PQC) mechanism. Recently, the molecular machineries responsible for the CFTR PQC mechanism which includes molecular chaperones and ubiquitination enzymes have been revealed. This review summarizes the molecular mechanism of the CFTR PQC and discusses the possibility that the peripheral ubiquitination mechanism becomes a novel drug target to develop the CFTR stabilizer as a novel class of CFTR modulator.
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Affiliation(s)
- Ryosuke Fukuda
- Department of Biomedical Chemistry, School of Science and Technology, Kwansei Gakuin University, Nishinomiya, Japan
| | - Tsukasa Okiyoneda
- Department of Biomedical Chemistry, School of Science and Technology, Kwansei Gakuin University, Nishinomiya, Japan
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61
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Kym PR, Wang X, Pizzonero M, Van der Plas SE. Recent Progress in the Discovery and Development of Small-Molecule Modulators of CFTR. PROGRESS IN MEDICINAL CHEMISTRY 2018; 57:235-276. [PMID: 29680149 DOI: 10.1016/bs.pmch.2018.01.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Cystic fibrosis (CF) is a genetic disorder driven by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. While different mutations lead to varying levels of disease severity, the most common CFTR F508del mutation leads to defects in protein stability, trafficking to the cell membrane and gating of chloride ions. Recently, advances in medicinal chemistry have led to the identification small-molecule drugs that result in significant clinical efficacy in improving lung function in CF patients. Multiple CFTR modulators are required to fix the various defects in the CFTR protein. Small-molecule potentiators increase the open-channel probability and improve the gating of ions through CFTR. Small-molecule correctors stabilize the protein fold of the mutant channel, facilitating protein maturation and translocation to the cellular membrane. Recent data suggest that triple-combination therapy consisting of a potentiator and two correctors that operate through distinct mechanisms will be required to deliver highly significant clinical efficacy for most CF patients. The progress in medicinal chemistry that has led to the identification of novel CFTR potentiators and correctors is presented in this chapter.
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Affiliation(s)
- Phil R Kym
- AbbVie Discovery Chemistry and Technology, North Chicago, IL, United States
| | - Xueqing Wang
- AbbVie Discovery Chemistry and Technology, North Chicago, IL, United States
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62
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Yang Z, Hildebrandt E, Jiang F, Aleksandrov AA, Khazanov N, Zhou Q, An J, Mezzell AT, Xavier BM, Ding H, Riordan JR, Senderowitz H, Kappes JC, Brouillette CG, Urbatsch IL. Structural stability of purified human CFTR is systematically improved by mutations in nucleotide binding domain 1. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1193-1204. [PMID: 29425673 DOI: 10.1016/j.bbamem.2018.02.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 01/19/2018] [Accepted: 02/05/2018] [Indexed: 12/17/2022]
Abstract
The Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is an ABC transporter containing two transmembrane domains forming a chloride ion channel, and two nucleotide binding domains (NBD1 and NBD2). CFTR has presented a formidable challenge to obtain monodisperse, biophysically stable protein. Here we report a comprehensive study comparing effects of single and multiple NBD1 mutations on stability of both the NBD1 domain alone and on purified full length human CFTR. Single mutations S492P, A534P, I539T acted additively, and when combined with M470V, S495P, and R555K cumulatively yielded an NBD1 with highly improved structural stability. Strategic combinations of these mutations strongly stabilized the domain to attain a calorimetric Tm > 70 °C. Replica exchange molecular dynamics simulations on the most stable 6SS-NBD1 variant implicated fluctuations, electrostatic interactions and side chain packing as potential contributors to improved stability. Progressive stabilization of NBD1 directly correlated with enhanced structural stability of full-length CFTR protein. Thermal unfolding of the stabilized CFTR mutants, monitored by changes in intrinsic fluorescence, demonstrated that Tm could be shifted as high as 67.4 °C in 6SS-CFTR, more than 20 °C higher than wild-type. H1402S, an NBD2 mutation, conferred CFTR with additional thermal stability, possibly by stabilizing an NBD-dimerized conformation. CFTR variants with NBD1-stabilizing mutations were expressed at the cell surface in mammalian cells, exhibited ATPase and channel activity, and retained these functions to higher temperatures. The capability to produce enzymatically active CFTR with improved structural stability amenable to biophysical and structural studies will advance mechanistic investigations and future cystic fibrosis drug development.
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Affiliation(s)
- Zhengrong Yang
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Ellen Hildebrandt
- Department of Cell Biology and Biochemistry, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, 3601 4th Street, Stop 6540, Lubbock, TX 79430, USA
| | - Fan Jiang
- Department of Medicine, University of Alabama at Birmingham, 701 19th Street South, Birmingham, AL 35294-0007, USA
| | - Andrei A Aleksandrov
- Department of Biochemistry and Biophysics and Cystic Fibrosis Treatment and Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Netaly Khazanov
- Department of Chemistry, Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Qingxian Zhou
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Jianli An
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Andrew T Mezzell
- Department of Medicine, University of Alabama at Birmingham, 701 19th Street South, Birmingham, AL 35294-0007, USA
| | - Bala M Xavier
- Department of Cell Biology and Biochemistry, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, 3601 4th Street, Stop 6540, Lubbock, TX 79430, USA
| | - Haitao Ding
- Department of Medicine, University of Alabama at Birmingham, 701 19th Street South, Birmingham, AL 35294-0007, USA
| | - John R Riordan
- Department of Biochemistry and Biophysics and Cystic Fibrosis Treatment and Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Hanoch Senderowitz
- Department of Chemistry, Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - John C Kappes
- Department of Medicine, University of Alabama at Birmingham, 701 19th Street South, Birmingham, AL 35294-0007, USA; Birmingham Veterans Affairs Medical Center, Research Service, Birmingham, AL 35233, USA
| | | | - Ina L Urbatsch
- Department of Cell Biology and Biochemistry, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, 3601 4th Street, Stop 6540, Lubbock, TX 79430, USA.
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63
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Correcting CFTR folding defects by small-molecule correctors to cure cystic fibrosis. Curr Opin Pharmacol 2017; 34:83-90. [PMID: 29055231 DOI: 10.1016/j.coph.2017.09.014] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 09/15/2017] [Accepted: 09/26/2017] [Indexed: 12/18/2022]
Abstract
Pharmacological intervention to treat the lethal genetic disease cystic fibrosis has become reality, even for the severe, most common folding mutant F508del CFTR. CFTR defects range from absence of the protein, misfolding that leads to degradation rather than cell-surface localization (such as F508del), to functional chloride-channel defects on the cell surface. Corrector and potentiator drugs improve cell-surface location and channel activity, respectively, and combination therapy of two correctors and a potentiator have shown synergy. Several combinations are in the drug-development pipeline and although the primary defect is not repaired, rescue levels are reaching those resembling a cure for CF. Combination therapy with correctors may also improve functional CFTR mutants and benefit patients on potentiator therapy.
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Xavier BM, Hildebrandt E, Jiang F, Ding H, Kappes JC, Urbatsch IL. Substitution of Yor1p NBD1 residues improves the thermal stability of Human Cystic Fibrosis Transmembrane Conductance Regulator. Protein Eng Des Sel 2017; 30:729-741. [PMID: 29053845 PMCID: PMC5914393 DOI: 10.1093/protein/gzx054] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 09/08/2017] [Accepted: 09/15/2017] [Indexed: 01/05/2023] Open
Abstract
The Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is a plasma membrane chloride channel protein that regulates vertebrate fluid homeostasis. The inefficiency of wild type human CFTR protein folding/trafficking is exacerbated by genetic mutations that can cause protein misfolding in the endoplasmic reticulum (ER) and subsequent degradation. This project investigates small changes in protein sequence that can alter the thermal stability of the large multi-domain CFTR protein. We target a conserved 70-residue α-subdomain located in the first nucleotide-binding domain that hosts the common misfolding mutation ∆F508. To investigate substitutions that can stabilize this domain, we constructed chimeras between human CFTR and its closest yeast homolog Yor1p. The α-subdomain of Yor1p was replaced with that of CFTR in Saccharomyces cerevisiae. Cellular localization of green fluorescence protein-tagged Yor1p-CFTR chimeras was analyzed by fluorescence microscopy and quantitative multispectral imaging flow cytometry, steady-state protein levels were compared by SDS-PAGE and protein function probed by a phenotypic oligomycin resistance assay. The chimeras exhibited ER retention in yeast characteristic of defective protein folding/processing. Substitution of seven CFTR α-subdomain residues that are highly conserved in Yor1p and other transporters but differ in CFTR (S495P/R516K/F533L/A534P/K536G/I539T/R553K) improved Yor1p-CFTR chimera localization to the yeast plasma membrane. When introduced into human CFTR expressed in mammalian cells, the same substitutions improve the purified protein thermal stability. This stabilized human CFTR protein will be directly useful for structural and biophysical studies that have been limited by the thermal sensitivity of wild type CFTR. The insights into critical structural residues within CFTR could facilitate development of effective therapeutics for CF-causing mutations.
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Affiliation(s)
- B M Xavier
- Department of Cell Biology and Biochemistry, and Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - E Hildebrandt
- Department of Cell Biology and Biochemistry, and Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - F Jiang
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - H Ding
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - J C Kappes
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Veterans Affairs Medical Center, Research Service, Birmingham, AL 35294, USA
| | - I L Urbatsch
- Department of Cell Biology and Biochemistry, and Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
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65
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Farinha CM, Canato S. From the endoplasmic reticulum to the plasma membrane: mechanisms of CFTR folding and trafficking. Cell Mol Life Sci 2017; 74:39-55. [PMID: 27699454 PMCID: PMC11107782 DOI: 10.1007/s00018-016-2387-7] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 09/28/2016] [Indexed: 01/10/2023]
Abstract
CFTR biogenesis starts with its co-translational insertion into the membrane of endoplasmic reticulum and folding of the cytosolic domains, towards the acquisition of a fully folded compact native structure. Efficiency of this process is assessed by the ER quality control system that allows the exit of folded proteins but targets unfolded/misfolded CFTR to degradation. If allowed to leave the ER, CFTR is modified at the Golgi and reaches the post-Golgi compartments to be delivered to the plasma membrane where it functions as a cAMP- and phosphorylation-regulated chloride/bicarbonate channel. CFTR residence at the membrane is a balance of membrane delivery, endocytosis, and recycling. Several adaptors, motor, and scaffold proteins contribute to the regulation of CFTR stability and are involved in continuously assessing its structure through peripheral quality control systems. Regulation of CFTR biogenesis and traffic (and its dysregulation by mutations, such as the most common F508del) determine its overall activity and thus contribute to the fine modulation of chloride secretion and hydration of epithelial surfaces. This review covers old and recent knowledge on CFTR folding and trafficking from its synthesis to the regulation of its stability at the plasma membrane and highlights how several of these steps can be modulated to promote the rescue of mutant CFTR.
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Affiliation(s)
- Carlos M Farinha
- BioISI-Biosystems and Integrative Sciences Institute, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016, Lisbon, Portugal.
| | - Sara Canato
- BioISI-Biosystems and Integrative Sciences Institute, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016, Lisbon, Portugal
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66
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Veit G, Avramescu RG, Chiang AN, Houck SA, Cai Z, Peters KW, Hong JS, Pollard HB, Guggino WB, Balch WE, Skach WR, Cutting GR, Frizzell RA, Sheppard DN, Cyr DM, Sorscher EJ, Brodsky JL, Lukacs GL. From CFTR biology toward combinatorial pharmacotherapy: expanded classification of cystic fibrosis mutations. Mol Biol Cell 2016; 27:424-33. [PMID: 26823392 PMCID: PMC4751594 DOI: 10.1091/mbc.e14-04-0935] [Citation(s) in RCA: 386] [Impact Index Per Article: 48.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
More than 2000 mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) have been described that confer a range of molecular cell biological and functional phenotypes. Most of these mutations lead to compromised anion conductance at the apical plasma membrane of secretory epithelia and cause cystic fibrosis (CF) with variable disease severity. Based on the molecular phenotypic complexity of CFTR mutants and their susceptibility to pharmacotherapy, it has been recognized that mutations may impose combinatorial defects in CFTR channel biology. This notion led to the conclusion that the combination of pharmacotherapies addressing single defects (e.g., transcription, translation, folding, and/or gating) may show improved clinical benefit over available low-efficacy monotherapies. Indeed, recent phase 3 clinical trials combining ivacaftor (a gating potentiator) and lumacaftor (a folding corrector) have proven efficacious in CF patients harboring the most common mutation (deletion of residue F508, ΔF508, or Phe508del). This drug combination was recently approved by the U.S. Food and Drug Administration for patients homozygous for ΔF508. Emerging studies of the structural, cell biological, and functional defects caused by rare mutations provide a new framework that reveals a mixture of deficiencies in different CFTR alleles. Establishment of a set of combinatorial categories of the previously defined basic defects in CF alleles will aid the design of even more efficacious therapeutic interventions for CF patients.
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Affiliation(s)
- Gudio Veit
- Department of Physiology, McGill University, Montréal, QC H3G 1Y6, Canada
| | - Radu G Avramescu
- Department of Physiology, McGill University, Montréal, QC H3G 1Y6, Canada
| | - Annette N Chiang
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260
| | - Scott A Houck
- Marsico Lung Institute, School of Medicine, University of North Carolina, Chapel Hill, NC 27514
| | - Zhiwei Cai
- School of Physiology & Pharmacology, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Kathryn W Peters
- Department of Cell Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
| | - Jeong S Hong
- Department of Cellular, Developmental, and Integrative Biology, University of Alabama, Birmingham, AL 35294
| | - Harvey B Pollard
- Department of Anatomy, Physiology and Genetics and Center for Medical Proteomics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814
| | - William B Guggino
- Department of Physiology, Johns Hopkins University, Baltimore, MD 21205
| | - William E Balch
- Department of Chemical Physiology, Skaggs Institute of Chemical Physiology, Scripps Research Institute, La Jolla, CA 92037
| | - William R Skach
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, OR 97239
| | - Garry R Cutting
- McKusick-Nathans Institute of Genetic Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD 21205
| | - Raymond A Frizzell
- Department of Cell Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
| | - David N Sheppard
- School of Physiology & Pharmacology, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Douglas M Cyr
- Marsico Lung Institute, School of Medicine, University of North Carolina, Chapel Hill, NC 27514
| | - Eric J Sorscher
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322
| | - Jeffrey L Brodsky
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260
| | - Gergely L Lukacs
- Department of Physiology, McGill University, Montréal, QC H3G 1Y6, Canada Department of Biochemistry, McGill University, Montréal, QC H3G 1Y6, Canada GRASP, McGill University, Montréal, QC H3G 1Y6, Canada
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67
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Bartoszewski R, Króliczewski J, Piotrowski A, Jasiecka AJ, Bartoszewska S, Vecchio-Pagan B, Fu L, Sobolewska A, Matalon S, Cutting GR, Rowe SM, Collawn JF. Codon bias and the folding dynamics of the cystic fibrosis transmembrane conductance regulator. Cell Mol Biol Lett 2016; 21:23. [PMID: 28536625 PMCID: PMC5415761 DOI: 10.1186/s11658-016-0025-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 10/13/2016] [Indexed: 12/20/2022] Open
Abstract
Synonymous or silent mutations are often overlooked in genetic analyses for disease-causing mutations unless they are directly associated with potential splicing defects. More recent studies, however, indicate that some synonymous single polynucleotide polymorphisms (sSNPs) are associated with changes in protein expression, and in some cases, protein folding and function. The impact of codon usage and mRNA structural changes on protein translation rates and how they can affect protein structure and function is just beginning to be appreciated. Examples are given here that demonstrate how synonymous mutations alter the translational kinetics and protein folding and/or function. The mechanism for how this occurs is based on a model in which codon usage modulates the translational rate by introducing pauses caused by nonoptimal or rare codons or by introducing changes in the mRNA structure, and this in turn influences co-translational folding. Two examples of this include the multidrug resistance protein (p-glycoprotein) and the cystic fibrosis transmembrane conductance regulator gene (CFTR). CFTR is also used here as a model to illustrate how synonymous mutations can be examined using in silico predictive methods to identify which sSNPs have the potential to change protein structure. The methodology described here can be used to help identify "non-silent" synonymous mutations in other genes.
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Affiliation(s)
- Rafal Bartoszewski
- Department of Biology and Pharmaceutical Botany, Medical University of Gdansk, Hallera 107, 80-416 Gdansk, Poland
| | - Jaroslaw Króliczewski
- Laboratory of Chemical Biology, Faculty of Biotechnology, University of Wroclaw, Wroclaw, Poland
| | - Arkadiusz Piotrowski
- Department of Biology and Pharmaceutical Botany, Medical University of Gdansk, Hallera 107, 80-416 Gdansk, Poland
| | - Anna Janaszak Jasiecka
- Department of Biology and Pharmaceutical Botany, Medical University of Gdansk, Hallera 107, 80-416 Gdansk, Poland
| | - Sylwia Bartoszewska
- Department of Inorganic Chemistry, Medical University of Gdansk, Gdansk, Poland
| | - Briana Vecchio-Pagan
- Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, USA
| | - Lianwu Fu
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, USA.,Gregory Fleming James Cystic Fibrosis Center, University of Alabama at Birmingham, Birmingham, USA
| | - Aleksandra Sobolewska
- Department of Biology and Pharmaceutical Botany, Medical University of Gdansk, Hallera 107, 80-416 Gdansk, Poland
| | - Sadis Matalon
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, USA.,Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, USA.,Gregory Fleming James Cystic Fibrosis Center, University of Alabama at Birmingham, Birmingham, USA
| | - Garry R Cutting
- Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, USA
| | - Steven M Rowe
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, USA.,Departments of Medicine and Pediatrics, University of Alabama at Birmingham, Birmingham, USA.,Gregory Fleming James Cystic Fibrosis Center, University of Alabama at Birmingham, Birmingham, USA
| | - James F Collawn
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, USA.,Gregory Fleming James Cystic Fibrosis Center, University of Alabama at Birmingham, Birmingham, USA
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68
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Le Henaff C, Faria Da Cunha M, Hatton A, Tondelier D, Marty C, Collet C, Zarka M, Geoffroy V, Zatloukal K, Laplantine E, Edelman A, Sermet-Gaudelus I, Marie PJ. Genetic deletion of keratin 8 corrects the altered bone formation and osteopenia in a mouse model of cystic fibrosis. Hum Mol Genet 2016; 25:1281-93. [PMID: 26769674 DOI: 10.1093/hmg/ddw009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 01/06/2016] [Indexed: 12/23/2022] Open
Abstract
Patients with cystic fibrosis (CF) display low bone mass and alterations in bone formation. Mice carrying the F508del genetic mutation in the cystic fibrosis conductance regulator (Cftr) gene display reduced bone formation and decreased bone mass. However, the underlying molecular mechanisms leading to these skeletal defects are unknown, which precludes the development of an efficient anti-osteoporotic therapeutic strategy. Here we report a key role for the intermediate filament protein keratin 8 (Krt8), in the osteoblast dysfunctions in F508del-Cftr mice. We found that murine and human osteoblasts express Cftr and Krt8 at low levels. Genetic studies showed that Krt8 deletion (Krt8(-/-)) in F508del-Cftr mice increased the levels of circulating markers of bone formation, corrected the expression of osteoblast phenotypic genes, promoted trabecular bone formation and improved bone mass and microarchitecture. Mechanistically, Krt8 deletion in F508del-Cftr mice corrected overactive NF-κB signaling and decreased Wnt-β-catenin signaling induced by the F508del-Cftr mutation in osteoblasts. In vitro, treatment with compound 407, which specifically disrupts the Krt8-F508del-Cftr interaction in epithelial cells, corrected the abnormal NF-κB and Wnt-β-catenin signaling and the altered phenotypic gene expression in F508del-Cftr osteoblasts. In vivo, short-term treatment with 407 corrected the altered Wnt-β-catenin signaling and bone formation in F508del-Cftr mice. Collectively, the results show that genetic or pharmacologic targeting of Krt8 leads to correction of osteoblast dysfunctions, altered bone formation and osteopenia in F508del-Cftr mice, providing a therapeutic strategy targeting the Krt8-F508del-CFTR interaction to correct the abnormal bone formation and bone loss in cystic fibrosis.
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Affiliation(s)
- Carole Le Henaff
- INSERM UMR-1132, Paris, France, University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | | | - Aurélie Hatton
- INSERM U-1151, Team 2, University Paris Descartes, Paris, France
| | | | - Caroline Marty
- INSERM UMR-1132, Paris, France, University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Corinne Collet
- INSERM UMR-1132, Paris, France, University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Mylène Zarka
- INSERM UMR-1132, Paris, France, University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Valérie Geoffroy
- INSERM UMR-1132, Paris, France, University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Kurt Zatloukal
- Institute of Pathology, Medical University of Graz, Graz, Austria and
| | - Emmanuel Laplantine
- Laboratoire de Signalisation et Pathogenèse, Institut Pasteur, Paris, France
| | | | | | - Pierre J Marie
- INSERM UMR-1132, Paris, France, University Paris Diderot, Sorbonne Paris Cité, Paris, France,
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69
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Hegyi P, Wilschanski M, Muallem S, Lukacs GL, Sahin-Tóth M, Uc A, Gray MA, Rakonczay Z, Maléth J. CFTR: A New Horizon in the Pathomechanism and Treatment of Pancreatitis. Rev Physiol Biochem Pharmacol 2016; 170:37-66. [PMID: 26856995 DOI: 10.1007/112_2015_5002] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Cystic fibrosis transmembrane conductance regulator (CFTR) is an ion channel that conducts chloride and bicarbonate ions across epithelial cell membranes. Mutations in the CFTR gene diminish the ion channel function and lead to impaired epithelial fluid transport in multiple organs such as the lung and the pancreas resulting in cystic fibrosis. Heterozygous carriers of CFTR mutations do not develop cystic fibrosis but exhibit increased risk for pancreatitis and associated pancreatic damage characterized by elevated mucus levels, fibrosis, and cyst formation. Importantly, recent studies demonstrated that pancreatitis causing insults, such as alcohol, smoking, or bile acids, strongly inhibit CFTR function. Furthermore, human studies showed reduced levels of CFTR expression and function in all forms of pancreatitis. These findings indicate that impairment of CFTR is critical in the development of pancreatitis; therefore, correcting CFTR function could be the first specific therapy in pancreatitis. In this review, we summarize recent advances in the field and discuss new possibilities for the treatment of pancreatitis.
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Affiliation(s)
- Péter Hegyi
- Institute for Translational Medicine and 1st Department of Medicine, University of Pécs, Pécs, Hungary.
- MTA-SZTE Translational Gastroenterology Research Group, Szeged, Hungary.
- First Department of Medicine, University of Szeged, Szeged, Hungary.
| | - Michael Wilschanski
- Pediatric Gastroenterology Unit, Hadassah Medical Center, Hebrew University, Jerusalem, Israel
| | - Shmuel Muallem
- National Institute of Dental and Craniofacial Research, Bethesda, MD, USA
| | | | - Miklós Sahin-Tóth
- Department of Molecular and Cell Biology, Boston University Henry M. Goldman School of Dental Medicine, Boston, MA, USA
| | - Aliye Uc
- Department of Pediatrics, University of Iowa, Carver College of Medicine, Iowa City, IA, USA
| | - Michael A Gray
- Institute for Cell & Molecular Biosciences, University Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Zoltán Rakonczay
- First Department of Medicine, University of Szeged, Szeged, Hungary
- Department of Pathophysiology, University of Szeged, Szeged, Hungary
| | - József Maléth
- First Department of Medicine, University of Szeged, Szeged, Hungary
- MTA-SZTE Translational Gastroenterology Research Group, Szeged, Hungary
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70
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Min D, Jefferson RE, Bowie JU, Yoon TY. Mapping the energy landscape for second-stage folding of a single membrane protein. Nat Chem Biol 2015; 11:981-7. [PMID: 26479439 DOI: 10.1038/nchembio.1939] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 09/14/2015] [Indexed: 12/15/2022]
Abstract
Membrane proteins are designed to fold and function in a lipid membrane, yet folding experiments within a native membrane environment are challenging to design. Here we show that single-molecule forced unfolding experiments can be adapted to study helical membrane protein folding under native-like bicelle conditions. Applying force using magnetic tweezers, we find that a transmembrane helix protein, Escherichia coli rhomboid protease GlpG, unfolds in a highly cooperative manner, largely unraveling as one physical unit in response to mechanical tension above 25 pN. Considerable hysteresis is observed, with refolding occurring only at forces below 5 pN. Characterizing the energy landscape reveals only modest thermodynamic stability (ΔG = 6.5 kBT) but a large unfolding barrier (21.3 kBT) that can maintain the protein in a folded state for long periods of time (t1/2 ∼3.5 h). The observed energy landscape may have evolved to limit the existence of troublesome partially unfolded states and impart rigidity to the structure.
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Affiliation(s)
- Duyoung Min
- National Creative Research Initiative Center for Single-Molecule Systems Biology, KAIST, Daejeon, South Korea.,Department of Physics, KAIST, Daejeon, South Korea
| | - Robert E Jefferson
- Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, California, USA
| | - James U Bowie
- Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, California, USA
| | - Tae-Young Yoon
- National Creative Research Initiative Center for Single-Molecule Systems Biology, KAIST, Daejeon, South Korea.,Department of Physics, KAIST, Daejeon, South Korea
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71
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Londino JD, Lazrak A, Noah JW, Aggarwal S, Bali V, Woodworth BA, Bebok Z, Matalon S. Influenza virus M2 targets cystic fibrosis transmembrane conductance regulator for lysosomal degradation during viral infection. FASEB J 2015; 29:2712-25. [PMID: 25795456 PMCID: PMC4478808 DOI: 10.1096/fj.14-268755] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 02/26/2015] [Indexed: 12/24/2022]
Abstract
We sought to determine the mechanisms by which influenza infection of human epithelial cells decreases cystic fibrosis transmembrane conductance regulator (CFTR) expression and function. We infected human bronchial epithelial (NHBE) cells and murine nasal epithelial (MNE) cells with various strains of influenza A virus. Influenza infection significantly reduced CFTR short circuit currents (Isc) and protein levels at 8 hours postinfection. We then infected CFTR expressing human embryonic kidney (HEK)-293 cells (HEK-293 CFTRwt) with influenza virus encoding a green fluorescent protein (GFP) tag and performed whole-cell and cell-attached patch clamp recordings. Forskolin-stimulated, GlyH-101-sensitive CFTR conductances, and CFTR open probabilities were reduced by 80% in GFP-positive cells; Western blots also showed significant reduction in total and plasma membrane CFTR levels. Knockdown of the influenza matrix protein 2 (M2) with siRNA, or inhibition of its activity by amantadine, prevented the decrease in CFTR expression and function. Lysosome inhibition (bafilomycin-A1), but not proteasome inhibition (lactacystin), prevented the reduction in CFTR levels. Western blots of immunoprecipitated CFTR from influenza-infected cells, treated with BafA1, and probed with antibodies against lysine 63-linked (K-63) or lysine 48-linked (K-48) polyubiquitin chains supported lysosomal targeting. These results highlight CFTR damage, leading to early degradation as an important contributing factor to influenza infection-associated ion transport defects.
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Affiliation(s)
- James David Londino
- *Department of Anesthesiology, Pulmonary Injury and Repair Center, and Department of Cell, Developmental and Integrative Biology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA; Southern Research Institute, Birmingham, Alabama, USA; and Department of Surgery, Division of Otolaryngology, School of Medicine, University of Alabama, Birmingham, Alabama, USA
| | - Ahmed Lazrak
- *Department of Anesthesiology, Pulmonary Injury and Repair Center, and Department of Cell, Developmental and Integrative Biology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA; Southern Research Institute, Birmingham, Alabama, USA; and Department of Surgery, Division of Otolaryngology, School of Medicine, University of Alabama, Birmingham, Alabama, USA
| | - James W Noah
- *Department of Anesthesiology, Pulmonary Injury and Repair Center, and Department of Cell, Developmental and Integrative Biology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA; Southern Research Institute, Birmingham, Alabama, USA; and Department of Surgery, Division of Otolaryngology, School of Medicine, University of Alabama, Birmingham, Alabama, USA
| | - Saurabh Aggarwal
- *Department of Anesthesiology, Pulmonary Injury and Repair Center, and Department of Cell, Developmental and Integrative Biology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA; Southern Research Institute, Birmingham, Alabama, USA; and Department of Surgery, Division of Otolaryngology, School of Medicine, University of Alabama, Birmingham, Alabama, USA
| | - Vedrana Bali
- *Department of Anesthesiology, Pulmonary Injury and Repair Center, and Department of Cell, Developmental and Integrative Biology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA; Southern Research Institute, Birmingham, Alabama, USA; and Department of Surgery, Division of Otolaryngology, School of Medicine, University of Alabama, Birmingham, Alabama, USA
| | - Bradford A Woodworth
- *Department of Anesthesiology, Pulmonary Injury and Repair Center, and Department of Cell, Developmental and Integrative Biology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA; Southern Research Institute, Birmingham, Alabama, USA; and Department of Surgery, Division of Otolaryngology, School of Medicine, University of Alabama, Birmingham, Alabama, USA
| | - Zsuzsanna Bebok
- *Department of Anesthesiology, Pulmonary Injury and Repair Center, and Department of Cell, Developmental and Integrative Biology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA; Southern Research Institute, Birmingham, Alabama, USA; and Department of Surgery, Division of Otolaryngology, School of Medicine, University of Alabama, Birmingham, Alabama, USA
| | - Sadis Matalon
- *Department of Anesthesiology, Pulmonary Injury and Repair Center, and Department of Cell, Developmental and Integrative Biology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA; Southern Research Institute, Birmingham, Alabama, USA; and Department of Surgery, Division of Otolaryngology, School of Medicine, University of Alabama, Birmingham, Alabama, USA
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72
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Mall MA, Galietta LJV. Targeting ion channels in cystic fibrosis. J Cyst Fibros 2015; 14:561-70. [PMID: 26115565 DOI: 10.1016/j.jcf.2015.06.002] [Citation(s) in RCA: 117] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 05/28/2015] [Accepted: 06/01/2015] [Indexed: 12/12/2022]
Abstract
Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene cause a characteristic defect in epithelial ion transport that plays a central role in the pathogenesis of cystic fibrosis (CF). Hence, pharmacological correction of this ion transport defect by targeting of mutant CFTR, or alternative ion channels that may compensate for CFTR dysfunction, has long been considered as an attractive approach to a causal therapy of this life-limiting disease. The recent introduction of the CFTR potentiator ivacaftor into the therapy of a subgroup of patients with specific CFTR mutations was a major milestone and enormous stimulus for seeking effective ion transport modulators for all patients with CF. In this review, we discuss recent breakthroughs and setbacks with CFTR modulators designed to rescue mutant CFTR including the common mutation F508del. Further, we examine the alternative chloride channels TMEM16A and SLC26A9, as well as the epithelial sodium channel ENaC as alternative targets in CF lung disease, which remains the major cause of morbidity and mortality in patients with CF. Finally, we will focus on the hurdles that still need to be overcome to make effective ion transport modulation therapies available for all patients with CF irrespective of their CFTR genotype.
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Affiliation(s)
- Marcus A Mall
- Department of Translational Pulmonology, Translational Lung Research Center Heidelberg (TLRC), Member of the German Center for Lung Research (DZL), University of Heidelberg, Heidelberg, Germany; Division of Pediatric Pulmonology & Allergy and Cystic Fibrosis Center, Department of Pediatrics, University of Heidelberg, Heidelberg, Germany.
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The safety dance: biophysics of membrane protein folding and misfolding in a cellular context. Q Rev Biophys 2014; 48:1-34. [PMID: 25420508 DOI: 10.1017/s0033583514000110] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Most biological processes require the production and degradation of proteins, a task that weighs heavily on the cell. Mutations that compromise the conformational stability of proteins place both specific and general burdens on cellular protein homeostasis (proteostasis) in ways that contribute to numerous diseases. Efforts to elucidate the chain of molecular events responsible for diseases of protein folding address one of the foremost challenges in biomedical science. However, relatively little is known about the processes by which mutations prompt the misfolding of α-helical membrane proteins, which rely on an intricate network of cellular machinery to acquire and maintain their functional structures within cellular membranes. In this review, we summarize the current understanding of the physical principles that guide membrane protein biogenesis and folding in the context of mammalian cells. Additionally, we explore how pathogenic mutations that influence biogenesis may differ from those that disrupt folding and assembly, as well as how this may relate to disease mechanisms and therapeutic intervention. These perspectives indicate an imperative for the use of information from structural, cellular, and biochemical studies of membrane proteins in the design of novel therapeutics and in personalized medicine.
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74
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He L, Aleksandrov AA, An J, Cui L, Yang Z, Brouillette CG, Riordan JR. Restoration of NBD1 thermal stability is necessary and sufficient to correct ∆F508 CFTR folding and assembly. J Mol Biol 2014; 427:106-20. [PMID: 25083918 DOI: 10.1016/j.jmb.2014.07.026] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 07/09/2014] [Accepted: 07/11/2014] [Indexed: 11/29/2022]
Abstract
Cystic fibrosis transmembrane conductance regulator (CFTR) (ABCC7), unique among ABC exporters as an ion channel, regulates ion and fluid transport in epithelial tissues. Loss of function due to mutations in the cftr gene causes cystic fibrosis. The most common cystic-fibrosis-causing mutation, the deletion of F508 (ΔF508) from the first nucleotide binding domain (NBD1) of CFTR, results in misfolding of the protein and clearance by cellular quality control systems. The ΔF508 mutation has two major impacts on CFTR: reduced thermal stability of NBD1 and disruption of its interface with membrane-spanning domains (MSDs). It is unknown if these two defects are independent and need to be targeted separately. To address this question, we varied the extent of stabilization of NBD1 using different second-site mutations and NBD1 binding small molecules with or without NBD1/MSD interface mutation. Combinations of different NBD1 changes had additive corrective effects on ∆F508 maturation that correlated with their ability to increase NBD1 thermostability. These effects were much larger than those caused by interface modification alone and accounted for most of the correction achieved by modifying both the domain and the interface. Thus, NBD1 stabilization plays a dominant role in overcoming the ΔF508 defect. Furthermore, the dual target approach resulted in a locked-open ion channel that was constitutively active in the absence of the normally obligatory dependence on phosphorylation by protein kinase A. Thus, simultaneous targeting of both the domain and the interface, as well as being non-essential for correction of biogenesis, may disrupt normal regulation of channel function.
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Affiliation(s)
- Lihua He
- Department of Biochemistry and Biophysics, Cystic Fibrosis Treatment and Research Center, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Andrei A Aleksandrov
- Department of Biochemistry and Biophysics, Cystic Fibrosis Treatment and Research Center, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Jianli An
- Center for Structural Biology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Liying Cui
- Department of Biochemistry and Biophysics, Cystic Fibrosis Treatment and Research Center, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Zhengrong Yang
- Center for Structural Biology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA; Department of Chemistry, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Christie G Brouillette
- Center for Structural Biology, University of Alabama at Birmingham, Birmingham, AL, 35294, USA; Department of Chemistry, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - John R Riordan
- Department of Biochemistry and Biophysics, Cystic Fibrosis Treatment and Research Center, University of North Carolina, Chapel Hill, NC, 27599, USA.
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75
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Pranke IM, Sermet-Gaudelus I. Biosynthesis of cystic fibrosis transmembrane conductance regulator. Int J Biochem Cell Biol 2014; 52:26-38. [DOI: 10.1016/j.biocel.2014.03.020] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2014] [Revised: 03/19/2014] [Accepted: 03/20/2014] [Indexed: 01/19/2023]
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76
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Favia M, Mancini MT, Bezzerri V, Guerra L, Laselva O, Abbattiscianni AC, Debellis L, Reshkin SJ, Gambari R, Cabrini G, Casavola V. Trimethylangelicin promotes the functional rescue of mutant F508del CFTR protein in cystic fibrosis airway cells. Am J Physiol Lung Cell Mol Physiol 2014; 307:L48-61. [PMID: 24816489 DOI: 10.1152/ajplung.00305.2013] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Cystic fibrosis transmembrane conductance regulator (CFTR) carrying the F508del mutation is retained in endoplasmic reticulum and fails to traffic to the cell surface where it functions as a protein kinase A (PKA)-activated chloride channel. Pharmacological correctors that rescue the trafficking of F508del CFTR may overcome this defect; however, the rescued F508del CFTR still displays reduced chloride permeability. Therefore, a combined administration of correctors and potentiators of the gating defect is ideal. We recently found that 4,6,4'-trimethylangelicin (TMA), besides inhibiting the expression of the IL-8 gene in airway cells in which the inflammatory response was challenged with Pseudomonas aeruginosa, also potentiates the cAMP/PKA-dependent activation of wild-type CFTR or F508del CFTR that has been restored to the plasma membrane. Here, we demonstrate that long preincubation with nanomolar concentrations of TMA is able to effectively rescue both F508del CFTR-dependent chloride secretion and F508del CFTR cell surface expression in both primary or secondary airway cell monolayers homozygous for F508del mutation. The correction effect of TMA seems to be selective for CFTR and persisted for 24 h after washout. Altogether, the results suggest that TMA, besides its anti-inflammatory and potentiator activities, also displays corrector properties.
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Affiliation(s)
- Maria Favia
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Maria T Mancini
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Valentino Bezzerri
- Laboratory of Molecular Pathology, Department of Pathology and Diagnostics, University Hospital Verona, Verona, Italy
| | - Lorenzo Guerra
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Onofrio Laselva
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Anna C Abbattiscianni
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Lucantonio Debellis
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Stephan J Reshkin
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Roberto Gambari
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy; and
| | - Giulio Cabrini
- Laboratory of Molecular Pathology, Department of Pathology and Diagnostics, University Hospital Verona, Verona, Italy
| | - Valeria Casavola
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy; Centre of Excellence in Comparative Genomics, University of Bari, Bari, Italy
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77
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Cebotaru L, Rapino D, Cebotaru V, Guggino WB. Correcting the cystic fibrosis disease mutant, A455E CFTR. PLoS One 2014; 9:e85183. [PMID: 24416359 PMCID: PMC3885674 DOI: 10.1371/journal.pone.0085183] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 12/03/2013] [Indexed: 11/18/2022] Open
Abstract
Cystic fibrosis is caused by more than 1000 mutations, the most common being the ΔF508 mutation. These mutations have been divided into five classes [1], with ΔF508 CFTR in class II. Here we have studied the class V mutation A455E. We report that the mature and immature bands of A455E are rapidly degraded primarily by proteasomes; the short protein half-life of this mutant therefore resembles that of ΔF508 CFTR. A455E could be rescued by treatment of the cells with proteasome inhibitors. Furthermore, co-transfection of A455E with the truncation mutant Δ264 CFTR also rescued the mature C band, indicating that A455E can be rescued by transcomplementation. We found that Δ264 CFTR bound to A455E, forming a bimolecular complex. Treatment with the compound correctors C3 and C4 also rescued A455E. These results are significant because they show that although ΔF508 belongs to a different class than A455E, it can be rescued by the same strategies, offering therapeutic promise to patients with Class V mutations.
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Affiliation(s)
- Liudmila Cebotaru
- Department of Ophthalmology, School of Medicine, The Johns Hopkins University, Baltimore, Maryland, United States of America
- Department of Physiology, School of Medicine, The Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Daniele Rapino
- Department of Ophthalmology, School of Medicine, The Johns Hopkins University, Baltimore, Maryland, United States of America
- Department of Physiology, School of Medicine, The Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Valeriu Cebotaru
- Department of Medicine, School of Medicine, The Johns Hopkins University, Baltimore, Maryland, United States of America
| | - William B. Guggino
- Department of Physiology, School of Medicine, The Johns Hopkins University, Baltimore, Maryland, United States of America
- * E-mail:
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Iram SH, Cole SPC. Differential functional rescue of Lys(513) and Lys(516) processing mutants of MRP1 (ABCC1) by chemical chaperones reveals different domain-domain interactions of the transporter. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:756-65. [PMID: 24231430 DOI: 10.1016/j.bbamem.2013.11.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 10/24/2013] [Accepted: 11/04/2013] [Indexed: 12/15/2022]
Abstract
Multidrug resistance protein 1 (MRP1) extrudes drugs as well as pharmacologically and physiologically important organic anions across the plasma membrane in an ATP-dependent manner. We previously showed that Ala substitutions of Lys(513) and Lys(516) in the cytoplasmic loop (CL5) connecting transmembrane helix 9 (TM9) to TM10 cause misfolding of MRP1, abrogating its expression at the plasma membrane in transfected human embryonic kidney (HEK) cells. Exposure of HEK cells to the chemical chaperones glycerol, DMSO, polyethylene glycol (PEG) and 4-aminobutyric acid (4-PBA) improved levels of K513A to wild-type MRP1 levels but transport activity was only fully restored by 4-PBA or DMSO treatments. Tryptic fragmentation patterns and conformation-dependent antibody immunoreactivity of the transport-deficient PEG- and glycerol-rescued K513A proteins indicated that the second nucleotide binding domain (NBD2) had adopted a more open conformation than in wild-type MRP1. This structural change was accompanied by differences in ATP binding and hydrolysis but no changes in substrate Km. In contrast to K513A, K516A levels in HEK cells were not significantly enhanced by chemical chaperones. In more permissive insect cells, however, K516A levels were comparable to wild-type MRP1. Nevertheless, organic anion transport by K516A in insect cell membranes was reduced by >80% due to reduced substrate Km. Tryptic fragmentation patterns indicated a more open conformation of the third membrane spanning domain of MRP1. Thus, despite their close proximity to one another in CL5, Lys(513) and Lys(516) participate in different interdomain interactions crucial for the proper folding and assembly of MRP1.
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Affiliation(s)
- Surtaj H Iram
- Division of Cancer Biology and Genetics, Queen's University, Kingston, ON K7L 3N6, Canada; Department of Pathology & Molecular Medicine, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Susan P C Cole
- Division of Cancer Biology and Genetics, Queen's University, Kingston, ON K7L 3N6, Canada; Department of Pathology & Molecular Medicine, Queen's University, Kingston, ON K7L 3N6, Canada.
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Ren HY, Grove DE, De La Rosa O, Houck SA, Sopha P, Van Goor F, Hoffman BJ, Cyr DM. VX-809 corrects folding defects in cystic fibrosis transmembrane conductance regulator protein through action on membrane-spanning domain 1. Mol Biol Cell 2013; 24:3016-24. [PMID: 23924900 PMCID: PMC3784376 DOI: 10.1091/mbc.e13-05-0240] [Citation(s) in RCA: 225] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Misfolding of cystic fibrosis transmembrane conductance regulator protein (CFTR) causes the fatal lung disease cystic fibrosis. VX-809 was developed to suppress disease-related folding defects in CFTR. VX-809 suppresses folding defects in CFTR by modulating the conformation of membrane-spanning domain 1. VX-808 is thereby able to partially restore function to F508del-CFTR and other disease-related mutants. Cystic fibrosis (CF) is a fatal genetic disorder associated with defective hydration of lung airways due to the loss of chloride transport through the CF transmembrane conductance regulator protein (CFTR). CFTR contains two membrane-spanning domains (MSDs), two nucleotide-binding domains (NBDs), and a regulatory domain, and its channel assembly requires multiple interdomain contacts. The most common CF-causing mutation, F508del, occurs in NBD1 and results in misfolding and premature degradation of F508del-CFTR. VX-809 is an investigational CFTR corrector that partially restores CFTR function in people who are homozygous for F508del-CFTR. To identify the folding defect(s) in F508del-CFTR that must be repaired to treat CF, we explored the mechanism of VX-809 action. VX-809 stabilized an N-terminal domain in CFTR that contains only MSD1 and efficaciously restored function to CFTR forms that have missense mutations in MSD1. The action of VX-809 on MSD1 appears to suppress folding defects in F508del-CFTR by enhancing interactions among the NBD1, MSD1, and MSD2 domains. The ability of VX-809 to correct F508del-CFTR is enhanced when combined with mutations that improve F508del-NBD1 interaction with MSD2. These data suggest that the use of VX-809 in combination with an additional CFTR corrector that suppresses folding defects downstream of MSD1 may further enhance CFTR function in people with F508del-CFTR.
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Affiliation(s)
- Hong Yu Ren
- Department of Cell Biology and University of North Carolina Cystic Fibrosis Center, School of Medicine, University of North Carolina, Chapel Hill, NC 27599 Vertex Pharmaceuticals, San Diego, CA 92121
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Mechanism-based corrector combination restores ΔF508-CFTR folding and function. Nat Chem Biol 2013; 9:444-54. [PMID: 23666117 DOI: 10.1038/nchembio.1253] [Citation(s) in RCA: 319] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Accepted: 04/08/2013] [Indexed: 01/12/2023]
Abstract
The most common cystic fibrosis mutation, ΔF508 in nucleotide binding domain 1 (NBD1), impairs cystic fibrosis transmembrane conductance regulator (CFTR)-coupled domain folding, plasma membrane expression, function and stability. VX-809, a promising investigational corrector of ΔF508-CFTR misprocessing, has limited clinical benefit and an incompletely understood mechanism, hampering drug development. Given the effect of second-site suppressor mutations, robust ΔF508-CFTR correction most likely requires stabilization of NBD1 energetics and the interface between membrane-spanning domains (MSDs) and NBD1, which are both established primary conformational defects. Here we elucidate the molecular targets of available correctors: class I stabilizes the NBD1-MSD1 and NBD1-MSD2 interfaces, and class II targets NBD2. Only chemical chaperones, surrogates of class III correctors, stabilize human ΔF508-NBD1. Although VX-809 can correct missense mutations primarily destabilizing the NBD1-MSD1/2 interface, functional plasma membrane expression of ΔF508-CFTR also requires compounds that counteract the NBD1 and NBD2 stability defects in cystic fibrosis bronchial epithelial cells and intestinal organoids. Thus, the combination of structure-guided correctors represents an effective approach for cystic fibrosis therapy.
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