1
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Grimes AC, Chen Y, Bansal H, Aguilar C, Perez Prado L, Quezada G, Estrada J, Tomlinson GE. Genetic markers for treatment-related pancreatitis in a cohort of Hispanic children with acute lymphoblastic leukemia. Support Care Cancer 2020; 29:725-731. [PMID: 32447501 DOI: 10.1007/s00520-020-05530-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 05/14/2020] [Indexed: 12/15/2022]
Abstract
PURPOSE Treatment-related pancreatitis (TRP) is a serious complication occurring in children with acute lymphoblastic leukemia (ALL). Those affected are at high risk for severe organ toxicity and treatment delays that can impact outcomes. TRP is associated with asparaginase, a standard therapeutic agent in childhood ALL. Native American ancestry, older age, high-risk leukemia, and increased use of asparaginase are linked to pancreatitis risk. However, dedicated genetic studies evaluating pancreatitis in childhood ALL include few Hispanics. Thus, the genetic basis for higher risk of pancreatitis among Hispanic children with ALL remains unknown. METHODS Cases of children with ALL treated in from 1994 through 2013 were reviewed and identified 14, all Hispanic, who developed pancreatitis related to asparaginase therapy. Forty-six controls consisting of Hispanic children treated on the same regimens without pancreatitis were selected for comparison. Total DNA isolated from whole blood was used for targeted DNA sequencing of 23 selected genes, including genes associated with pancreatitis without ALL and genes involved in asparagine metabolism. RESULTS Non-synonymous polymorphisms and frameshift deletions were detected in 15 genes. Most children with TRP had variants in ABAT, ASNS, and CFTR. Notably, children with TRP harbored many more CFTR variants (71.4%) compared with controls (39.1%). Among these, V470M (rs213950) was most frequent (OR 4.27, p = 0.025). CONCLUSIONS This is the first study of genetic factors in treatment-related pancreatitis in Hispanic children with ALL. Identifying correlative variants in ethnically vulnerable populations may improve screening to identify which patients with ALL are at greatest risk for pancreatitis.
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Affiliation(s)
- Allison C Grimes
- Department of Pediatrics, University of Texas Health Science Center San Antonio, San Antonio, TX, USA
- Greehey Children's Cancer Research Institute, University of Texas Health Science Center San Antonio, San Antonio, TX, USA
| | - Yidong Chen
- Greehey Children's Cancer Research Institute, University of Texas Health Science Center San Antonio, San Antonio, TX, USA
- Department of Population Health Sciences, University of Texas Health Science Center San Antonio, San Antonio, TX, USA
| | - Hima Bansal
- Greehey Children's Cancer Research Institute, University of Texas Health Science Center San Antonio, San Antonio, TX, USA
| | - Christine Aguilar
- Department of Pediatrics, University of Texas Health Science Center San Antonio, San Antonio, TX, USA
- Greehey Children's Cancer Research Institute, University of Texas Health Science Center San Antonio, San Antonio, TX, USA
| | - Luz Perez Prado
- Greehey Children's Cancer Research Institute, University of Texas Health Science Center San Antonio, San Antonio, TX, USA
| | - Gerardo Quezada
- Methodist Children's Hospital, San Antonio, TX, USA
- Children's Hospital of San Antonio, San Antonio, TX, USA
| | | | - Gail E Tomlinson
- Department of Pediatrics, University of Texas Health Science Center San Antonio, San Antonio, TX, USA.
- Greehey Children's Cancer Research Institute, University of Texas Health Science Center San Antonio, San Antonio, TX, USA.
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2
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Ivey G, Youker RT. Disease-relevant mutations alter amino acid co-evolution networks in the second nucleotide binding domain of CFTR. PLoS One 2020; 15:e0227668. [PMID: 31978131 PMCID: PMC6980524 DOI: 10.1371/journal.pone.0227668] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2018] [Accepted: 12/25/2019] [Indexed: 01/23/2023] Open
Abstract
Cystic Fibrosis (CF) is an inherited disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) ion channel. Mutations in CFTR cause impaired chloride ion transport in the epithelial tissues of patients leading to cardiopulmonary decline and pancreatic insufficiency in the most severely affected patients. CFTR is composed of twelve membrane-spanning domains, two nucleotide-binding domains (NBDs), and a regulatory domain. The most common mutation in CFTR is a deletion of phenylalanine at position 508 (ΔF508) in NBD1. Previous research has primarily concentrated on the structure and dynamics of the NBD1 domain; However numerous pathological mutations have also been found in the lesser-studied NBD2 domain. We have investigated the amino acid co-evolved network of interactions in NBD2, and the changes that occur in that network upon the introduction of CF and CF-related mutations (S1251N(T), S1235R, D1270N, N1303K(T)). Extensive coupling between the α- and β-subdomains were identified with residues in, or near Walker A, Walker B, H-loop and C-loop motifs. Alterations in the predicted residue network varied from moderate for the S1251T perturbation to more severe for N1303T. The S1235R and D1270N networks varied greatly compared to the wildtype, but these CF mutations only affect ion transport preference and do not severely disrupt CFTR function, suggesting dynamic flexibility in the network of interactions in NBD2. Our results also suggest that inappropriate interactions between the β-subdomain and Q-loop could be detrimental. We also identified mutations predicted to stabilize the NBD2 residue network upon introduction of the CF and CF-related mutations, and these predicted mutations are scored as benign by the MUTPRED2 algorithm. Our results suggest the level of disruption of the co-evolution predictions of the amino acid networks in NBD2 does not have a straightforward correlation with the severity of the CF phenotypes observed.
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Affiliation(s)
- Gabrianne Ivey
- Kyder Christian Academy, Franklin, North Carolina, United States of America
- Southwestern Community College, Sylva, North Carolina, United States of America
| | - Robert T. Youker
- Department of Biology, Western Carolina University, Cullowhee, North Carolina, United States of America
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3
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Bickers SC, Sayewich JS, Kanelis V. Intrinsically disordered regions regulate the activities of ATP binding cassette transporters. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183202. [PMID: 31972165 DOI: 10.1016/j.bbamem.2020.183202] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 01/16/2020] [Accepted: 01/17/2020] [Indexed: 12/11/2022]
Abstract
ATP binding cassette (ABC) proteins are a large family of membrane proteins present in all kingdoms of life. These multi-domain proteins are comprised, at minimum, of two membrane-spanning domains (MSD1, MSD2) and two cytosolic nucleotide binding domains (NBD1, NBD2). ATP binding and hydrolysis at the NBDs enables ABC proteins to actively transport solutes across membranes, regulate activities of other proteins, or function as channels. Like most eukaryotic membrane proteins, ABC proteins contain intrinsically disordered regions (IDRs). These conformationally dynamic regions in ABC proteins possess residual structure, are sites of phosphorylation, and mediate protein-protein interactions. Here, we review the role of IDRs in regulating ABC protein activity.
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Affiliation(s)
- Sarah C Bickers
- Department of Chemistry, University of Toronto, Toronto, ON, Canada; Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Jonathan S Sayewich
- Department of Chemistry, University of Toronto, Toronto, ON, Canada; Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Voula Kanelis
- Department of Chemistry, University of Toronto, Toronto, ON, Canada; Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, ON, Canada; Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada.
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4
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Veit G, Xu H, Dreano E, Avramescu RG, Bagdany M, Beitel LK, Roldan A, Hancock MA, Lay C, Li W, Morin K, Gao S, Mak PA, Ainscow E, Orth AP, McNamara P, Edelman A, Frenkiel S, Matouk E, Sermet-Gaudelus I, Barnes WG, Lukacs GL. Structure-guided combination therapy to potently improve the function of mutant CFTRs. Nat Med 2018; 24:1732-1742. [PMID: 30297908 PMCID: PMC6301090 DOI: 10.1038/s41591-018-0200-x] [Citation(s) in RCA: 96] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 08/08/2018] [Indexed: 12/17/2022]
Abstract
Available corrector drugs are unable to effectively rescue the folding defects of CFTR-ΔF508 (or CFTR-F508del), the most common disease-causing mutation of the cystic fibrosis transmembrane conductance regulator, a plasma membrane (PM) anion channel, and thus to substantially ameliorate clinical phenotypes of cystic fibrosis (CF). To overcome the corrector efficacy ceiling, here we show that compounds targeting distinct structural defects of CFTR can synergistically rescue mutant expression and function at the PM. High-throughput cell-based screens and mechanistic analysis identified three small-molecule series that target defects at nucleotide-binding domain (NBD1), NBD2 and their membrane-spanning domain (MSD) interfaces. Although individually these compounds marginally improve ΔF508-CFTR folding efficiency, function and stability, their combinations lead to ~50-100% of wild-type-level correction in immortalized and primary human airway epithelia and in mouse nasal epithelia. Likewise, corrector combinations were effective against rare missense mutations in various CFTR domains, probably acting via structural allostery, suggesting a mechanistic framework for their broad application.
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Affiliation(s)
- Guido Veit
- Department of Physiology, McGill University, Montréal, Quebec, Canada.
| | - Haijin Xu
- Department of Physiology, McGill University, Montréal, Quebec, Canada
| | - Elise Dreano
- Institut Necker-Enfants Malades (INEM)-INSERM U1151, Paris, France
| | - Radu G Avramescu
- Department of Physiology, McGill University, Montréal, Quebec, Canada
| | - Miklos Bagdany
- Department of Physiology, McGill University, Montréal, Quebec, Canada
| | - Lenore K Beitel
- Department of Physiology, McGill University, Montréal, Quebec, Canada
| | - Ariel Roldan
- Department of Physiology, McGill University, Montréal, Quebec, Canada
| | - Mark A Hancock
- SPR-MS Facility, McGill University, Montréal, Quebec, Canada
| | - Cecilia Lay
- Genomic Institute of the Novartis Research Foundation, San Diego, CA, USA
| | - Wei Li
- Genomic Institute of the Novartis Research Foundation, San Diego, CA, USA
| | - Katelin Morin
- Genomic Institute of the Novartis Research Foundation, San Diego, CA, USA
| | - Sandra Gao
- Genomic Institute of the Novartis Research Foundation, San Diego, CA, USA
| | - Puiying A Mak
- Genomic Institute of the Novartis Research Foundation, San Diego, CA, USA
| | - Edward Ainscow
- Genomic Institute of the Novartis Research Foundation, San Diego, CA, USA
| | - Anthony P Orth
- Genomic Institute of the Novartis Research Foundation, San Diego, CA, USA
| | - Peter McNamara
- Genomic Institute of the Novartis Research Foundation, San Diego, CA, USA
| | | | - Saul Frenkiel
- Department of Otolaryngology - Head and Neck Surgery, McGill University, Montréal, Quebec, Canada
| | - Elias Matouk
- Adult Cystic Fibrosis Clinic, Montreal Chest Institute, McGill University, Montréal, Quebec, Canada
| | | | - William G Barnes
- Genomic Institute of the Novartis Research Foundation, San Diego, CA, USA
| | - Gergely L Lukacs
- Department of Physiology, McGill University, Montréal, Quebec, Canada. .,Department of Biochemistry, McGill University, Montréal, Quebec, Canada. .,Groupe de Recherche Axé sur la Structure des Protéines (GRASP), McGill University, Montréal, Quebec, Canada.
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5
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Angelbello AJ, Chen JL, Childs-Disney JL, Zhang P, Wang ZF, Disney MD. Using Genome Sequence to Enable the Design of Medicines and Chemical Probes. Chem Rev 2018; 118:1599-1663. [PMID: 29322778 DOI: 10.1021/acs.chemrev.7b00504] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Rapid progress in genome sequencing technology has put us firmly into a postgenomic era. A key challenge in biomedical research is harnessing genome sequence to fulfill the promise of personalized medicine. This Review describes how genome sequencing has enabled the identification of disease-causing biomolecules and how these data have been converted into chemical probes of function, preclinical lead modalities, and ultimately U.S. Food and Drug Administration (FDA)-approved drugs. In particular, we focus on the use of oligonucleotide-based modalities to target disease-causing RNAs; small molecules that target DNA, RNA, or protein; the rational repurposing of known therapeutic modalities; and the advantages of pharmacogenetics. Lastly, we discuss the remaining challenges and opportunities in the direct utilization of genome sequence to enable design of medicines.
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Affiliation(s)
- Alicia J Angelbello
- Departments of Chemistry and Neuroscience, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Jonathan L Chen
- Departments of Chemistry and Neuroscience, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Jessica L Childs-Disney
- Departments of Chemistry and Neuroscience, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Peiyuan Zhang
- Departments of Chemistry and Neuroscience, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Zi-Fu Wang
- Departments of Chemistry and Neuroscience, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Matthew D Disney
- Departments of Chemistry and Neuroscience, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
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6
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Stiegler SC, Rübbelke M, Korotkov VS, Weiwad M, John C, Fischer G, Sieber SA, Sattler M, Buchner J. A chemical compound inhibiting the Aha1-Hsp90 chaperone complex. J Biol Chem 2017; 292:17073-17083. [PMID: 28851842 PMCID: PMC5641884 DOI: 10.1074/jbc.m117.797829] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 07/20/2017] [Indexed: 11/06/2022] Open
Abstract
The eukaryotic Hsp90 chaperone machinery comprises many co-chaperones and regulates the conformation of hundreds of cytosolic client proteins. Therefore, it is not surprising that the Hsp90 machinery has become an attractive therapeutic target for diseases such as cancer. The compounds used so far to target this machinery affect the entire Hsp90 system. However, it would be desirable to achieve a more selective targeting of Hsp90-co-chaperone complexes. To test this concept, in this-proof-of-principle study, we screened for modulators of the interaction between Hsp90 and its co-chaperone Aha1, which accelerates the ATPase activity of Hsp90. A FRET-based assay that monitored Aha1 binding to Hsp90 enabled identification of several chemical compounds modulating the effect of Aha1 on Hsp90 activity. We found that one of these inhibitors can abrogate the Aha1-induced ATPase stimulation of Hsp90 without significantly affecting Hsp90 ATPase activity in the absence of Aha1. NMR spectroscopy revealed that this inhibitory compound binds the N-terminal domain of Hsp90 close to its ATP-binding site and overlapping with a transient Aha1-interaction site. We also noted that this inhibitor does not dissociate the Aha1-Hsp90 complex but prevents the specific interaction with the N-terminal domain of Hsp90 required for catalysis. In consequence, the inhibitor affected the activation and processing of Hsp90-Aha1-dependent client proteins in vivo We conclude that it is possible to abrogate a specific co-chaperone function of Hsp90 without inhibiting the entire Hsp90 machinery. This concept may also hold true for other co-chaperones of Hsp90.
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Affiliation(s)
- Sandrine C Stiegler
- From the Center for Integrated Protein Science Munich, Department of Chemistry, Technische Universität München, D-85747 Garching, Germany
| | - Martin Rübbelke
- From the Center for Integrated Protein Science Munich, Department of Chemistry, Technische Universität München, D-85747 Garching, Germany
- the Institute of Structural Biology, Helmholtz Zentrum München, 85764 Neuherberg, Germany
| | - Vadim S Korotkov
- From the Center for Integrated Protein Science Munich, Department of Chemistry, Technische Universität München, D-85747 Garching, Germany
| | - Matthias Weiwad
- the Max Planck Research Unit for Enzymology of Protein Folding, 06120 Halle/Saale, Germany, and
| | - Christine John
- From the Center for Integrated Protein Science Munich, Department of Chemistry, Technische Universität München, D-85747 Garching, Germany
| | - Gunter Fischer
- the Max Planck Research Unit for Enzymology of Protein Folding, 06120 Halle/Saale, Germany, and
| | - Stephan A Sieber
- From the Center for Integrated Protein Science Munich, Department of Chemistry, Technische Universität München, D-85747 Garching, Germany
| | - Michael Sattler
- From the Center for Integrated Protein Science Munich, Department of Chemistry, Technische Universität München, D-85747 Garching, Germany
- the Institute of Structural Biology, Helmholtz Zentrum München, 85764 Neuherberg, Germany
| | - Johannes Buchner
- From the Center for Integrated Protein Science Munich, Department of Chemistry, Technische Universität München, D-85747 Garching, Germany,
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7
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Linsdell P. Architecture and functional properties of the CFTR channel pore. Cell Mol Life Sci 2017; 74:67-83. [PMID: 27699452 PMCID: PMC11107662 DOI: 10.1007/s00018-016-2389-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [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: 12/12/2022]
Abstract
The main function of the cystic fibrosis transmembrane conductance regulator (CFTR) is as an ion channel for the movement of small anions across epithelial cell membranes. As an ion channel, CFTR must form a continuous pathway across the cell membrane-referred to as the channel pore-for the rapid electrodiffusional movement of ions. This review summarizes our current understanding of the architecture of the channel pore, as defined by electrophysiological analysis and molecular modeling studies. This includes consideration of the characteristic functional properties of the pore, definition of the overall shape of the entire extent of the pore, and discussion of how the molecular structure of distinct regions of the pore might control different facets of pore function. Comparisons are drawn with closely related proteins that are not ion channels, and also with structurally unrelated proteins with anion channel function. A simple model of pore function is also described.
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Affiliation(s)
- Paul Linsdell
- Department of Physiology and Biophysics, Dalhousie University, PO Box 15000, Halifax, NS, B3H 4R2, Canada.
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8
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Abstract
Allosteric transition, defined as conformational changes induced by ligand binding, is one of the fundamental properties of proteins. Allostery has been observed and characterized in many proteins, and has been recently utilized to control protein function via regulation of protein activity. Here, we review the physical and evolutionary origin of protein allostery, as well as its importance to protein regulation, drug discovery, and biological processes in living systems. We describe recently developed approaches to identify allosteric pathways, connected sets of pairwise interactions that are responsible for propagation of conformational change from the ligand-binding site to a distal functional site. We then present experimental and computational protein engineering approaches for control of protein function by modulation of allosteric sites. As an example of application of these approaches, we describe a synergistic computational and experimental approach to rescue the cystic-fibrosis-associated protein cystic fibrosis transmembrane conductance regulator, which upon deletion of a single residue misfolds and causes disease. This example demonstrates the power of allosteric manipulation in proteins to both elucidate mechanisms of molecular function and to develop therapeutic strategies that rescue those functions. Allosteric control of proteins provides a tool to shine a light on the complex cascades of cellular processes and facilitate unprecedented interrogation of biological systems.
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Affiliation(s)
- Nikolay V Dokholyan
- Department of Biochemistry and Biophysics, University of North Carolina , Chapel Hill, North Carolina 27599, United States
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9
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Hall JD, Wang H, Byrnes LJ, Shanker S, Wang K, Efremov IV, Chong PA, Forman-Kay JD, Aulabaugh AE. Binding screen for cystic fibrosis transmembrane conductance regulator correctors finds new chemical matter and yields insights into cystic fibrosis therapeutic strategy. Protein Sci 2016; 25:360-73. [PMID: 26444971 DOI: 10.1002/pro.2821] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 10/01/2015] [Indexed: 11/08/2022]
Abstract
The most common mutation in cystic fibrosis (CF) patients is deletion of F508 (ΔF508) in the first nucleotide binding domain (NBD1) of the CF transmembrane conductance regulator (CFTR). ΔF508 causes a decrease in the trafficking of CFTR to the cell surface and reduces the thermal stability of isolated NBD1; it is well established that both of these effects can be rescued by additional revertant mutations in NBD1. The current paradigm in CF small molecule drug discovery is that, like revertant mutations, a path may exist to ΔF508 CFTR correction through a small molecule chaperone binding to NBD1. We, therefore, set out to find small molecule binders of NBD1 and test whether it is possible to develop these molecules into potent binders that increase CFTR trafficking in CF-patient-derived human bronchial epithelial cells. Several fragments were identified that bind NBD1 at either the CFFT-001 site or the BIA site. However, repeated attempts to improve the affinity of these fragments resulted in only modest gains. Although these results cannot prove that there is no possibility of finding a high-affinity small molecule binder of NBD1, they are discouraging and lead us to hypothesize that the nature of these two binding sites, and isolated NBD1 itself, may not contain the features needed to build high-affinity interactions. Future work in this area may, therefore, require constructs including other domains of CFTR in addition to NBD1, if high-affinity small molecule binding is to be achieved.
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Affiliation(s)
- Justin D Hall
- Structural Biology and Biophysics Group, Pfizer, Groton, Connecticut, 06340
| | - Hong Wang
- Structural Biology and Biophysics Group, Pfizer, Groton, Connecticut, 06340
| | - Laura J Byrnes
- Structural Biology and Biophysics Group, Pfizer, Groton, Connecticut, 06340
| | - Suman Shanker
- Structural Biology and Biophysics Group, Pfizer, Groton, Connecticut, 06340
| | - Kelong Wang
- Structural Biology and Biophysics Group, Pfizer, Groton, Connecticut, 06340
| | - Ivan V Efremov
- Worldwide Medicinal Chemistry, , Pfizer, Cambridge, Massachusetts, 02140
| | - P Andrew Chong
- Molecular Structure and Function Program, Hospital for Sick Kids, Toronto, Ontario, M5G 0A4, Canada.,Department of Biochemistry, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
| | - Julie D Forman-Kay
- Molecular Structure and Function Program, Hospital for Sick Kids, Toronto, Ontario, M5G 0A4, Canada.,Department of Biochemistry, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
| | - Ann E Aulabaugh
- Structural Biology and Biophysics Group, Pfizer, Groton, Connecticut, 06340
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10
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Estácio SG, Martiniano HFMC, Faísca PFN. Thermal unfolding simulations of NBD1 domain variants reveal structural motifs associated with the impaired folding of F508del-CFTR. MOLECULAR BIOSYSTEMS 2016; 12:2834-48. [DOI: 10.1039/c6mb00193a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The deletion of phenylalanine 508 reshapes the conformational space of the NBD1 domain that populates unique intermediate states that provide insights into the molecular events that underlie the impaired folding of F508del-NBD1.
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Affiliation(s)
- Sílvia G. Estácio
- BioISI – Biosystems & Integrative Sciences Institute
- Faculdade de Ciências
- Universidade de Lisboa
- 1749-016 Lisboa
- Portugal
| | - Hugo F. M. C. Martiniano
- BioISI – Biosystems & Integrative Sciences Institute
- Faculdade de Ciências
- Universidade de Lisboa
- 1749-016 Lisboa
- Portugal
| | - Patrícia F. N. Faísca
- BioISI – Biosystems & Integrative Sciences Institute
- Faculdade de Ciências
- Universidade de Lisboa
- 1749-016 Lisboa
- Portugal
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11
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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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12
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Banerji J. Asparaginase treatment side-effects may be due to genes with homopolymeric Asn codons (Review-Hypothesis). Int J Mol Med 2015; 36:607-26. [PMID: 26178806 PMCID: PMC4533780 DOI: 10.3892/ijmm.2015.2285] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 07/15/2015] [Indexed: 12/14/2022] Open
Abstract
The present treatment of childhood T-cell leukemias involves the systemic administration of prokary-otic L-asparaginase (ASNase), which depletes plasma Asparagine (Asn) and inhibits protein synthesis. The mechanism of therapeutic action of ASNase is poorly understood, as are the etiologies of the side-effects incurred by treatment. Protein expression from genes bearing Asn homopolymeric coding regions (N-hCR) may be particularly susceptible to Asn level fluctuation. In mammals, N-hCR are rare, short and conserved. In humans, misfunctions of genes encoding N-hCR are associated with a cluster of disorders that mimic ASNase therapy side-effects which include impaired glycemic control, dislipidemia, pancreatitis, compromised vascular integrity, and neurological dysfunction. This paper proposes that dysregulation of Asn homeostasis, potentially even by ASNase produced by the microbiome, may contribute to several clinically important syndromes by altering expression of N-hCR bearing genes. By altering amino acid abundance and modulating ribosome translocation rates at codon repeats, the microbiomic environment may contribute to genome decoding and to shaping the proteome. We suggest that impaired translation at poly Asn codons elevates diabetes risk and severity.
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Affiliation(s)
- Julian Banerji
- Center for Computational and Integrative Biology, MGH, Simches Research Center, Boston, MA 02114, USA
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13
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Hildebrandt E, Mulky A, Ding H, Dai Q, Aleksandrov AA, Bajrami B, Diego PA, Wu X, Ray M, Naren AP, Riordan JR, Yao X, DeLucas LJ, Urbatsch IL, Kappes JC. A stable human-cell system overexpressing cystic fibrosis transmembrane conductance regulator recombinant protein at the cell surface. Mol Biotechnol 2015; 57:391-405. [PMID: 25577540 PMCID: PMC4405497 DOI: 10.1007/s12033-014-9830-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Recent human clinical trials results demonstrated successful treatment for certain genetic forms of cystic fibrosis (CF). To extend treatment opportunities to those afflicted with other genetic forms of CF disease, structural and biophysical characterization of CF transmembrane conductance regulator (CFTR) is urgently needed. In this study, CFTR was modified with various tags, including a His10 purification tag, the SUMOstar (SUMO*) domain, an extracellular FLAG epitope, and an enhanced green fluorescent protein (EGFP), each alone or in various combinations. Expressed in HEK293 cells, recombinant CFTR proteins underwent complex glycosylation, compartmentalized with the plasma membrane, and exhibited regulated chloride-channel activity with only modest alterations in channel conductance and gating kinetics. Surface CFTR expression level was enhanced by the presence of SUMO* on the N-terminus. Quantitative mass-spectrometric analysis indicated approximately 10% of the total recombinant CFTR (SUMO*-CFTR(FLAG)-EGFP) localized to the plasma membrane. Trial purification using dodecylmaltoside for membrane protein extraction reproducibly recovered 178 ± 56 μg SUMO*-CFTR(FLAG)-EGFP per billion cells at 80% purity. Fluorescence size-exclusion chromatography indicated purified CFTR was monodisperse. These findings demonstrate a stable mammalian cell expression system capable of producing human CFTR of sufficient quality and quantity to augment future CF drug discovery efforts, including biophysical and structural studies.
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Affiliation(s)
- Ellen Hildebrandt
- Department of Cell Biology and Biochemistry, and Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX 79430
| | - Alok Mulky
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Haitao Ding
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Qun Dai
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Andrei A. Aleksandrov
- Department of Biochemistry & Biophysics, University of North Carolina, Chapel Hill, NC 27599
| | - Bekim Bajrami
- Department of Chemistry, University of Connecticut, Storrs, CT 06269
| | - Pamela Ann Diego
- Department of Chemistry, University of Connecticut, Storrs, CT 06269
| | - Xing Wu
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Marjorie Ray
- Department of Optometry, University of Alabama at Birmingham, Birmingham, AL 35294
| | | | - John R. Riordan
- Department of Biochemistry & Biophysics, University of North Carolina, Chapel Hill, NC 27599
| | - Xudong Yao
- Department of Chemistry, University of Connecticut, Storrs, CT 06269
| | - Lawrence J. DeLucas
- Department of Optometry, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Ina L. Urbatsch
- Department of Cell Biology and Biochemistry, and Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX 79430
| | - John C. Kappes
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294
- Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229
- Birmingham Veterans Affairs Medical Center, Research Service, Birmingham, AL 35233
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Broadbent SD, Wang W, Linsdell P. Interaction between 2 extracellular loops influences the activity of the cystic fibrosis transmembrane conductance regulator chloride channel. Biochem Cell Biol 2014; 92:390-6. [PMID: 25253636 DOI: 10.1139/bcb-2014-0066] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Activity of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel is thought to be controlled by cytoplasmic factors. However, recent evidence has shown that overall channel activity is also influenced by extracellular anions that interact directly with the extracellular loops (ECLs) of the CFTR protein. Very little is known about the structure of the ECLs or how substances interacting with these ECLs might affect CFTR function. We used patch-clamp recording to investigate the accessibility of cysteine-reactive reagents to cysteines introduced throughout ECL1 and 2 key sites in ECL4. Furthermore, interactions between ECL1 and ECL4 were investigated by the formation of disulfide crosslinks between cysteines introduced into these 2 regions. Crosslinks could be formed between R899C (in ECL4) and a number of sites in ECL1 in a manner that was dependent on channel activity, suggesting that the relative orientation of these 2 loops changes on activation. Formation of these crosslinks inhibited channel function, suggesting that relative movement of these ECLs is important to normal channel function. Implications of these findings for the effects of mutations in the ECLs that are associated with cystic fibrosis and interactions with extracellular substances that influence channel activity are discussed.
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Affiliation(s)
- Steven D Broadbent
- Department of Physiology and Biophysics, Dalhousie University, PO Box 15000, Halifax, NS B3H 4R2, Canada
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15
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LaRusch J, Jung J, General IJ, Lewis MD, Park HW, Brand RE, Gelrud A, Anderson MA, Banks PA, Conwell D, Lawrence C, Romagnuolo J, Baillie J, Alkaade S, Cote G, Gardner TB, Amann ST, Slivka A, Sandhu B, Aloe A, Kienholz ML, Yadav D, Barmada MM, Bahar I, Lee MG, Whitcomb DC. Mechanisms of CFTR functional variants that impair regulated bicarbonate permeation and increase risk for pancreatitis but not for cystic fibrosis. PLoS Genet 2014; 10:e1004376. [PMID: 25033378 PMCID: PMC4102440 DOI: 10.1371/journal.pgen.1004376] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2013] [Accepted: 03/10/2014] [Indexed: 02/07/2023] Open
Abstract
CFTR is a dynamically regulated anion channel. Intracellular WNK1-SPAK activation causes CFTR to change permeability and conductance characteristics from a chloride-preferring to bicarbonate-preferring channel through unknown mechanisms. Two severe CFTR mutations (CFTRsev) cause complete loss of CFTR function and result in cystic fibrosis (CF), a severe genetic disorder affecting sweat glands, nasal sinuses, lungs, pancreas, liver, intestines, and male reproductive system. We hypothesize that those CFTR mutations that disrupt the WNK1-SPAK activation mechanisms cause a selective, bicarbonate defect in channel function (CFTRBD) affecting organs that utilize CFTR for bicarbonate secretion (e.g. the pancreas, nasal sinus, vas deferens) but do not cause typical CF. To understand the structural and functional requirements of the CFTR bicarbonate-preferring channel, we (a) screened 984 well-phenotyped pancreatitis cases for candidate CFTRBD mutations from among 81 previously described CFTR variants; (b) conducted electrophysiology studies on clones of variants found in pancreatitis but not CF; (c) computationally constructed a new, complete structural model of CFTR for molecular dynamics simulation of wild-type and mutant variants; and (d) tested the newly defined CFTRBD variants for disease in non-pancreas organs utilizing CFTR for bicarbonate secretion. Nine variants (CFTR R74Q, R75Q, R117H, R170H, L967S, L997F, D1152H, S1235R, and D1270N) not associated with typical CF were associated with pancreatitis (OR 1.5, p = 0.002). Clones expressed in HEK 293T cells had normal chloride but not bicarbonate permeability and conductance with WNK1-SPAK activation. Molecular dynamics simulations suggest physical restriction of the CFTR channel and altered dynamic channel regulation. Comparing pancreatitis patients and controls, CFTRBD increased risk for rhinosinusitis (OR 2.3, p<0.005) and male infertility (OR 395, p<<0.0001). WNK1-SPAK pathway-activated increases in CFTR bicarbonate permeability are altered by CFTRBD variants through multiple mechanisms. CFTRBD variants are associated with clinically significant disorders of the pancreas, sinuses, and male reproductive system.
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Affiliation(s)
- Jessica LaRusch
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Jinsei Jung
- Department of Pharmacology and Brain Korea 21 Plus Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea
| | - Ignacio J. General
- Department of Computational & Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Michele D. Lewis
- Division of Gastroenterology and Hepatology, Mayo Clinic, Jacksonville, Florida, United States of America
| | - Hyun Woo Park
- Department of Pharmacology and Brain Korea 21 Plus Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea
| | - Randall E. Brand
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Andres Gelrud
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Michelle A. Anderson
- Department of Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Peter A. Banks
- Division of Gastroenterology, Brigham and Women's Hospital, Boston, Massachusetts, United States of America
| | - Darwin Conwell
- Division of Gastroenterology, Brigham and Women's Hospital, Boston, Massachusetts, United States of America
| | - Christopher Lawrence
- Digestive Disease Center, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Joseph Romagnuolo
- Digestive Disease Center, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - John Baillie
- Department of Medicine, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Samer Alkaade
- Department of Internal Medicine, St. Louis University School of Medicine, St Louis, Missouri, United States of America
| | - Gregory Cote
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Timothy B. Gardner
- Dartmouth-Hitchcock Medical Center, Hanover, New Hampshire, United States of America
| | - Stephen T. Amann
- North Mississippi Medical Center, Tupelo, Mississippi, United States of America
| | - Adam Slivka
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Bimaljit Sandhu
- Division of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University Medical Center, Richmond, Virginia, United States of America
| | - Amy Aloe
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Michelle L. Kienholz
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Dhiraj Yadav
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - M. Michael Barmada
- Department of Human Genetics, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Ivet Bahar
- Department of Computational & Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Min Goo Lee
- Department of Pharmacology and Brain Korea 21 Plus Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea
| | - David C. Whitcomb
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Department of Human Genetics, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Department of Cell Biology and Molecular Physiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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Abstract
AbstractABC transporters comprise a large, diverse, and ubiquitous superfamily of membrane active transporters. Their core architecture is a dimer of dimers, comprising two transmembrane (TM) domains that bind substrate, and two ATP-binding cassettes, which use the cell's energy currency to couple substrate translocation to ATP hydrolysis. Despite the availability of over a dozen resolved structures and a wealth of biochemical and biophysical data, this field is bedeviled by controversy and long-standing mechanistic questions remain unresolved. The prevailing paradigm for the ABC transport mechanism is the Switch Model, in which the ATP-binding cassettes dimerize upon binding two ATP molecules, and thence dissociate upon sequential ATP hydrolysis. This cycle of nucleotide-binding domain (NBD) dimerization and dissociation is coupled to a switch between inward- or outward facing conformations of a single TM channel; this alternating access enables substrate binding on one face of the membrane and its release at the other. Notwithstanding widespread acceptance of the Switch Model, there is substantial evidence that the NBDs do not separate very much, if at all, and thus physical separation of the ATP cassettes observed in crystallographic structures may be an artefact. An alternative Constant Contact Model has been proposed, in which ATP hydrolysis occurs alternately at the two ATP-binding sites, with one of the sites remaining closed and containing occluded nucleotide at all times. In this model, the cassettes remain in contact and the active sites swing open in an alternately seesawing motion. Whilst the concept of NBD association/dissociation in the Switch Model is naturally compatible with a single alternating-access channel, the asymmetric functioning proposed by the Constant Contact model suggests an alternating or reciprocating function in the TMDs. Here, a new model for the function of ABC transporters is proposed in which the sequence of ATP binding, hydrolysis, and product release in each active site is directly coupled to the analogous sequence of substrate binding, translocation and release in one of two functionally separate substrate translocation pathways. Each translocation pathway functions 180° out of phase. A wide and diverse selection of data for both ABC importers and exporters is examined, and the ability of the Switch and Reciprocating Models to explain the data is compared and contrasted. This analysis shows that not only can the Reciprocating Model readily explain the data; it also suggests straightforward explanations for the function of a number of atypical ABC transporters. This study represents the most coherent and complete attempt at an all-encompassing scheme to explain how these important proteins work, one that is consistent with sound biochemical and biophysical evidence.
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Linsdell P. Cystic fibrosis transmembrane conductance regulator chloride channel blockers: Pharmacological, biophysical and physiological relevance. World J Biol Chem 2014; 5:26-39. [PMID: 24600512 PMCID: PMC3942540 DOI: 10.4331/wjbc.v5.i1.26] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 11/15/2013] [Accepted: 12/11/2013] [Indexed: 02/05/2023] Open
Abstract
Dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel causes cystic fibrosis, while inappropriate activity of this channel occurs in secretory diarrhea and polycystic kidney disease. Drugs that interact directly with CFTR are therefore of interest in the treatment of a number of disease states. This review focuses on one class of small molecules that interacts directly with CFTR, namely inhibitors that act by directly blocking chloride movement through the open channel pore. In theory such compounds could be of use in the treatment of diarrhea and polycystic kidney disease, however in practice all known substances acting by this mechanism to inhibit CFTR function lack either the potency or specificity for in vivo use. Nevertheless, this theoretical pharmacological usefulness set the scene for the development of more potent, specific CFTR inhibitors. Biophysically, open channel blockers have proven most useful as experimental probes of the structure and function of the CFTR chloride channel pore. Most importantly, the use of these blockers has been fundamental in developing a functional model of the pore that includes a wide inner vestibule that uses positively charged amino acid side chains to attract both permeant and blocking anions from the cell cytoplasm. CFTR channels are also subject to this kind of blocking action by endogenous anions present in the cell cytoplasm, and recently this blocking effect has been suggested to play a role in the physiological control of CFTR channel function, in particular as a novel mechanism linking CFTR function dynamically to the composition of epithelial cell secretions. It has also been suggested that future drugs could target this same pathway as a way of pharmacologically increasing CFTR activity in cystic fibrosis. Studying open channel blockers and their mechanisms of action has resulted in significant advances in our understanding of CFTR as a pharmacological target in disease states, of CFTR channel structure and function, and of how CFTR activity is controlled by its local environment.
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18
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CFTR structure and cystic fibrosis. Int J Biochem Cell Biol 2014; 52:15-25. [PMID: 24534272 DOI: 10.1016/j.biocel.2014.02.004] [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: 01/08/2014] [Revised: 02/04/2014] [Accepted: 02/06/2014] [Indexed: 12/31/2022]
Abstract
CFTR (cystic fibrosis transmembrane conductance regulator) is a member of the ATP-binding cassette family of membrane proteins. Although almost all members of this family are transporters, CFTR functions as a channel with specificity for anions, in particular chloride and bicarbonate. In this review we look at what is known about CFTR structure and function within the context of the ATP-binding cassette family. We also review current strategies aimed at obtaining the high resolution structure of the protein.
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Kunzelmann K, Mehta A. CFTR: a hub for kinases and crosstalk of cAMP and Ca2+. FEBS J 2013; 280:4417-29. [PMID: 23895508 DOI: 10.1111/febs.12457] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 06/29/2013] [Accepted: 07/02/2013] [Indexed: 12/17/2022]
Abstract
Cystic fibrosis (CF) is caused by mutations in the CF transmembrane conductance regulator (CFTR). The resulting disease is pleiotropic consistent with the idea that CFTR acts as a node within a network of signalling proteins. CFTR is not only a regulator of multiple transport proteins and controlled by numerous kinases but also participates in many signalling pathways that are disrupted after expression of its commonest mutant (F508del-CFTR). It operates in membrane compartments creating a scaffold for cytoskeletal elements, surface receptors, kinases and phosphodiesterases. CFTR is exposed to membrane-local second messengers such that a CFTR-interacting, low cellular energy sensor kinase (AMP- and ADP-activated kinase, AMPK) signals through a high energy phosphohistidine protein kinase (nucleoside diphosphate kinase, NDPK). CFTR also translocates a Ca(2+)-dependent adenylate cyclase to its proximity so that a rigid separation between cAMP-dependent and Ca(2+)-dependent regulation of Cl(-) transport becomes obsolete. In the presence of wild-type CFTR, parallel activation of CFTR and outwardly rectifying anoctamin 6 Cl(-) channels is observed, while the Ca(2+)-activated anoctamin 1 Cl(-) channel is inhibited. In contrast, in CF cells, CFTR is missing/mislocalized and the outwardly rectifying chloride channel is attenuated while Ca(2+)-dependent Cl(-) secretion (anoctamin 1) appears upregulated. Additionally, we consider the idea that F508del-CFTR when trapped in the endoplasmic reticulum augments IP3-mediated Ca(2+) release by providing a shunt pathway for Cl(-). CFTR and the IP3 receptor share the characteristic that they both assemble their partner proteins to increase the plasticity of their hub responses. In CF, the CFTR hub fails to form at the plasma membrane, with widespread detrimental consequences for cell signalling.
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Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) protein is highly expressed in the pancreatic duct epithelia and permits anions and water to enter the ductal lumen. This results in an increased volume of alkaline fluid allowing the highly concentrated proteins secreted by the acinar cells to remain in a soluble state. This work will expound on the pathophysiology and pathology caused by the malfunctioning CFTR protein with special reference to ion transport and acid-base abnormalities both in humans and animal models. We will also discuss the relationship between cystic fibrosis (CF) and pancreatitis, and outline present and potential therapeutic approaches in CF treatment relevant to the pancreas.
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Affiliation(s)
- Michael Wilschanski
- Pediatric Gastroenterology, Hadassah University Hospital, Jerusalem 91240, Israel
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