1
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Wu M, Chen JH. CFTR dysfunction leads to defective bacterial eradication on cystic fibrosis airways. Front Physiol 2024; 15:1385661. [PMID: 38699141 PMCID: PMC11063615 DOI: 10.3389/fphys.2024.1385661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Accepted: 04/04/2024] [Indexed: 05/05/2024] Open
Abstract
Dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) anion channel by genetic mutations causes the inherited disease cystic fibrosis (CF). CF lung disease that involves multiple disorders of epithelial function likely results from loss of CFTR function as an anion channel conducting chloride and bicarbonate ions and its function as a cellular regulator modulating the activity of membrane and cytosol proteins. In the absence of CFTR activity, abundant mucus accumulation, bacterial infection and inflammation characterize CF airways, in which inflammation-associated tissue remodeling and damage gradually destroys the lung. Deciphering the link between CFTR dysfunction and bacterial infection in CF airways may reveal the pathogenesis of CF lung disease and guide the development of new treatments. Research efforts towards this goal, including high salt, low volume, airway surface liquid acidosis and abnormal mucus hypotheses are critically reviewed.
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Affiliation(s)
| | - Jeng-Haur Chen
- College of Life Sciences, Zhejiang Normal University, Jinhua, Zhejiang, China
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2
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Ramananda Y, Naren AP, Arora K. Functional Consequences of CFTR Interactions in Cystic Fibrosis. Int J Mol Sci 2024; 25:3384. [PMID: 38542363 PMCID: PMC10970640 DOI: 10.3390/ijms25063384] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 03/09/2024] [Accepted: 03/12/2024] [Indexed: 09/01/2024] Open
Abstract
Cystic fibrosis (CF) is a fatal autosomal recessive disorder caused by the loss of function mutations within a single gene for the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR). CFTR is a chloride channel that regulates ion and fluid transport across various epithelia. The discovery of CFTR as the CF gene and its cloning in 1989, coupled with extensive research that went into the understanding of the underlying biological mechanisms of CF, have led to the development of revolutionary therapies in CF that we see today. The highly effective modulator therapies have increased the survival rates of CF patients and shifted the epidemiological landscape and disease prognosis. However, the differential effect of modulators among CF patients and the presence of non-responders and ineligible patients underscore the need to develop specialized and customized therapies for a significant number of patients. Recent advances in the understanding of the CFTR structure, its expression, and defined cellular compositions will aid in developing more precise therapies. As the lifespan of CF patients continues to increase, it is becoming critical to clinically address the extra-pulmonary manifestations of CF disease to improve the quality of life of the patients. In-depth analysis of the molecular signature of different CF organs at the transcriptional and post-transcriptional levels is rapidly advancing and will help address the etiological causes and variability of CF among patients and develop precision medicine in CF. In this review, we will provide an overview of CF disease, leading to the discovery and characterization of CFTR and the development of CFTR modulators. The later sections of the review will delve into the key findings derived from single-molecule and single-cell-level analyses of CFTR, followed by an exploration of disease-relevant protein complexes of CFTR that may ultimately define the etiological course of CF disease.
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Affiliation(s)
- Yashaswini Ramananda
- Department of Pediatrics, Division of Pulmonary Medicine, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA;
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Anjaparavanda P. Naren
- Department of Pediatrics, Division of Pulmonary Medicine, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA;
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Kavisha Arora
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
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3
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Zhao S, Luo J, Hu J, Wang H, Zhao N, Cao M, Zhang C, Hu R, Liu L. Role of Ezrin in Asthma-Related Airway Inflammation and Remodeling. Mediators Inflamm 2022; 2022:6255012. [PMID: 36530558 PMCID: PMC9750775 DOI: 10.1155/2022/6255012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 11/22/2022] [Accepted: 11/22/2022] [Indexed: 08/13/2023] Open
Abstract
Ezrin is an actin binding protein connecting the cell membrane and the cytoskeleton, which is crucial to maintaining cell morphology, intercellular adhesion, and cytoskeleton remodeling. Asthma involves dysfunction of inflammatory cells, cytokines, and airway structural cells. Recent studies have shown that ezrin, whose function is affected by extensive phosphorylation and protein interactions, is closely associated with asthma, may be a therapeutic target for asthma treatment. In this review, we summarize studies on ezrin and discuss its role in asthma-related airway inflammation and remodeling.
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Affiliation(s)
- Shumei Zhao
- Affiliated Hospital of Nanjing University of Chinese Medicine, Jiangsu Province Hospital of Chinese Medicine, Nanjing 210029, China
- Nanjing University of Chinese Medicine, Nanjing 210029, China
| | - Jiaqi Luo
- Affiliated Hospital of Nanjing University of Chinese Medicine, Jiangsu Province Hospital of Chinese Medicine, Nanjing 210029, China
- Nanjing University of Chinese Medicine, Nanjing 210029, China
| | - Jun Hu
- Affiliated Hospital of Nanjing University of Chinese Medicine, Jiangsu Province Hospital of Chinese Medicine, Nanjing 210029, China
- Nanjing University of Chinese Medicine, Nanjing 210029, China
| | - Hesheng Wang
- Affiliated Hospital of Nanjing University of Chinese Medicine, Jiangsu Province Hospital of Chinese Medicine, Nanjing 210029, China
- Nanjing University of Chinese Medicine, Nanjing 210029, China
| | - Ningwei Zhao
- Affiliated Hospital of Nanjing University of Chinese Medicine, Jiangsu Province Hospital of Chinese Medicine, Nanjing 210029, China
- Shimadzu Biomedical Research Laboratory, Shanghai 200233, China
| | - Meng Cao
- Nanjing University of Chinese Medicine, Nanjing 210029, China
- Affiliated Hospital of Integrated Traditional Chinese and Western Medicine Nanjing University of Chinese Medicine, Nanjing 210028, China
| | - Cong Zhang
- Affiliated Hospital of Nanjing University of Chinese Medicine, Jiangsu Province Hospital of Chinese Medicine, Nanjing 210029, China
- Nanjing University of Chinese Medicine, Nanjing 210029, China
| | - Rongkui Hu
- Affiliated Hospital of Nanjing University of Chinese Medicine, Jiangsu Province Hospital of Chinese Medicine, Nanjing 210029, China
- Nanjing University of Chinese Medicine, Nanjing 210029, China
| | - Lanying Liu
- Affiliated Hospital of Nanjing University of Chinese Medicine, Jiangsu Province Hospital of Chinese Medicine, Nanjing 210029, China
- Nanjing University of Chinese Medicine, Nanjing 210029, China
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4
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Bidaud-Meynard A, Bossard F, Schnúr A, Fukuda R, Veit G, Xu H, Lukacs GL. Transcytosis maintains CFTR apical polarity in the face of constitutive and mutation-induced basolateral missorting. J Cell Sci 2019; 132:jcs.226886. [PMID: 30975917 DOI: 10.1242/jcs.226886] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Accepted: 04/02/2019] [Indexed: 12/22/2022] Open
Abstract
Apical polarity of cystic fibrosis transmembrane conductance regulator (CFTR) is essential for solute and water transport in secretory epithelia and can be impaired in human diseases. Maintenance of apical polarity in the face of CFTR non-polarized delivery and inefficient apical retention of mutant CFTRs lacking PDZ-domain protein (NHERF1, also known as SLC9A3R1) interaction, remains enigmatic. Here, we show that basolateral CFTR delivery originates from biosynthetic (∼35%) and endocytic (∼65%) recycling missorting. Basolateral channels are retrieved via basolateral-to-apical transcytosis (hereafter denoted apical transcytosis), enhancing CFTR apical expression by two-fold and suppressing its degradation. In airway epithelia, CFTR transcytosis is microtubule-dependent but independent of Myo5B, Rab11 proteins and NHERF1 binding to its C-terminal DTRL motif. Increased basolateral delivery due to compromised apical recycling and accelerated internalization upon impaired NHERF1-CFTR association is largely counterbalanced by efficient CFTR basolateral internalization and apical transcytosis. Thus, transcytosis represents a previously unrecognized, but indispensable, mechanism for maintaining CFTR apical polarity that acts by attenuating its constitutive and mutation-induced basolateral missorting.
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Affiliation(s)
| | - Florian Bossard
- Department of Physiology, McGill University, Montréal, QC, H3G 1Y6, Canada
| | - Andrea Schnúr
- Department of Physiology, McGill University, Montréal, QC, H3G 1Y6, Canada
| | - Ryosuke Fukuda
- Department of Physiology, McGill University, Montréal, QC, H3G 1Y6, Canada
| | - Guido Veit
- Department of Physiology, McGill University, Montréal, QC, H3G 1Y6, Canada
| | - Haijin Xu
- Department of Physiology, McGill University, Montréal, QC, H3G 1Y6, Canada
| | - Gergely L Lukacs
- Department of Physiology, McGill University, Montréal, QC, H3G 1Y6, Canada .,Department of Biochemistry, McGill University, Montréal, QC, H3G 1Y6, Canada
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5
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Yin LM, Duan TT, Ulloa L, Yang YQ. Ezrin Orchestrates Signal Transduction in Airway Cells. Rev Physiol Biochem Pharmacol 2019; 174:1-23. [PMID: 28702704 DOI: 10.1007/112_2017_4] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Ezrin is a critical structural protein that organizes receptor complexes and orchestrates their signal transduction. In this study, we review the ezrin-meditated regulation of critical receptor complexes, including the epidermal growth factor receptor (EGFR), CD44, vascular cell adhesion molecule (VCAM), and the deleted in colorectal cancer (DCC) receptor. We also analyze the ezrin-meditated regulation of critical pathways associated with asthma, such as the RhoA, Rho-associated protein kinase (ROCK), and protein kinase A (cAMP/PKA) pathways. Mounting evidence suggests that ezrin plays a role in controlling airway cell function and potentially contributes to respiratory diseases. Ezrin can participate in asthma pathogenesis by affecting bronchial epithelium repair, T lymphocyte regulation, and the contraction of the airway smooth muscle cells. These studies provide new insights for the design of novel therapeutic strategies for asthma treatment.
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Affiliation(s)
- Lei-Miao Yin
- Laboratory of Molecular Biology, Shanghai Research Institute of Acupuncture and Meridian, Yue Yang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, 200030, China
| | - Ting-Ting Duan
- Laboratory of Molecular Biology, Shanghai Research Institute of Acupuncture and Meridian, Yue Yang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, 200030, China
| | - Luis Ulloa
- Laboratory of Molecular Biology, Shanghai Research Institute of Acupuncture and Meridian, Yue Yang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, 200030, China. .,Department of Surgery, Center of Immunology and Inflammation, Rutgers-New Jersey Medical School, Rutgers University, Newark, NJ, 07101, USA.
| | - Yong-Qing Yang
- Laboratory of Molecular Biology, Shanghai Research Institute of Acupuncture and Meridian, Yue Yang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, 200030, China.
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6
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Lim SH, Legere EA, Snider J, Stagljar I. Recent Progress in CFTR Interactome Mapping and Its Importance for Cystic Fibrosis. Front Pharmacol 2018; 8:997. [PMID: 29403380 PMCID: PMC5785726 DOI: 10.3389/fphar.2017.00997] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 12/26/2017] [Indexed: 12/25/2022] Open
Abstract
Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is a chloride channel found in secretory epithelia with a plethora of known interacting proteins. Mutations in the CFTR gene cause cystic fibrosis (CF), a disease that leads to progressive respiratory illness and other complications of phenotypic variance resulting from perturbations of this protein interaction network. Studying the collection of CFTR interacting proteins and the differences between the interactomes of mutant and wild type CFTR provides insight into the molecular machinery of the disease and highlights possible therapeutic targets. This mini review focuses on functional genomics and proteomics approaches used for systematic, high-throughput identification of CFTR-interacting proteins to provide comprehensive insight into CFTR regulation and function.
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Affiliation(s)
- Sang Hyun Lim
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | | | - Jamie Snider
- Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada
| | - Igor Stagljar
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.,Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada
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7
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Okamoto CT. Regulation of Transporters and Channels by Membrane-Trafficking Complexes in Epithelial Cells. Cold Spring Harb Perspect Biol 2017; 9:a027839. [PMID: 28246186 PMCID: PMC5666629 DOI: 10.1101/cshperspect.a027839] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The vectorial secretion and absorption of fluid and solutes by epithelial cells is dependent on the polarized expression of membrane solute transporters and channels at the apical and basolateral membranes. The establishment and maintenance of this polarized expression of transporters and channels are affected by divers protein-trafficking complexes. Moreover, regulation of the magnitude of transport is often under control of physiological stimuli, again through the interaction of transporters and channels with protein-trafficking complexes. This review highlights the value in utilizing transporters and channels as cargo to characterize core trafficking machinery by which epithelial cells establish and maintain their polarized expression, and how this machinery regulates fluid and solute transport in response to physiological stimuli.
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Affiliation(s)
- Curtis T Okamoto
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California 90089-9121
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8
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Chin S, Hung M, Bear CE. Current insights into the role of PKA phosphorylation in CFTR channel activity and the pharmacological rescue of cystic fibrosis disease-causing mutants. Cell Mol Life Sci 2017; 74:57-66. [PMID: 27722768 PMCID: PMC11107731 DOI: 10.1007/s00018-016-2388-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [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: 12/21/2022]
Abstract
Cystic fibrosis transmembrane conductance regulator (CFTR) channel gating is predominantly regulated by protein kinase A (PKA)-dependent phosphorylation. In addition to regulating CFTR channel activity, PKA phosphorylation is also involved in enhancing CFTR trafficking and mediating conformational changes at the interdomain interfaces of the protein. The major cystic fibrosis (CF)-causing mutation is the deletion of phenylalanine at position 508 (F508del); it causes many defects that affect CFTR trafficking, stability, and gating at the cell surface. Due to the multiple roles of PKA phosphorylation, there is growing interest in targeting PKA-dependent signaling for rescuing the trafficking and functional defects of F508del-CFTR. This review will discuss the effects of PKA phosphorylation on wild-type CFTR, the consequences of CF mutations on PKA phosphorylation, and the development of therapies that target PKA-mediated signaling.
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Affiliation(s)
- Stephanie Chin
- Programme of Molecular Structure and Function, Research Institute, Hospital for Sick Children, Toronto, Canada
- Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Maurita Hung
- Programme of Molecular Structure and Function, Research Institute, Hospital for Sick Children, Toronto, Canada
| | - Christine E Bear
- Programme of Molecular Structure and Function, Research Institute, Hospital for Sick Children, Toronto, Canada.
- Department of Biochemistry, University of Toronto, Toronto, Canada.
- Department of Physiology, University of Toronto, Toronto, Canada.
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9
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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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10
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Yurkiv VA, Melikhov VI, Shubin VS. Effect of Ionophores on Activity of Na +,Cl -(HCO 3- )-ATPase. Bull Exp Biol Med 2016; 161:763-766. [PMID: 27783300 DOI: 10.1007/s10517-016-3504-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Indexed: 12/01/2022]
Abstract
We studied the effects of ionophores on activity of Na+,Cl-(HCO 3- )-ATPase. The most significant effect on the activity of this enzyme was produced by protonophore 2,4-dinitrophenol. The effect of this drug largely depended on the cation and anion composition and pH of the incubation medium and its pH. Activity of Na+,Cl-(HCO 3- )-ATPase increased at neutral and weakly alkaline pH and decreased at pH below 6.5-6.7. In control animals (without histamine injection) with very weak or absent Na+,Cl-(HCO 3- )-ATPase activity, the observed effect of the protonophore on ATPase activity was also virtually absent. The stimulatory effect of other ionophores (monensine, valinomycin, and A23187) was significantly weaker and depended on pH of the incubation medium, its cationic and anionic composition, and concentration of these ionophores.
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Affiliation(s)
- V A Yurkiv
- Research Institute of General Pathology and Pathophysiology, Russian Academy of Sciences, Moscow, Russia
| | - V I Melikhov
- Research Institute of General Pathology and Pathophysiology, Russian Academy of Sciences, Moscow, Russia
| | - V S Shubin
- Research Institute of General Pathology and Pathophysiology, Russian Academy of Sciences, Moscow, Russia.
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11
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Sun Y, Huang P. Adenosine A2B Receptor: From Cell Biology to Human Diseases. Front Chem 2016; 4:37. [PMID: 27606311 PMCID: PMC4995213 DOI: 10.3389/fchem.2016.00037] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 08/11/2016] [Indexed: 12/26/2022] Open
Abstract
Extracellular adenosine is a ubiquitous signaling molecule that modulates a wide array of biological processes. Recently, significant advances have been made in our understanding of A2B adenosine receptor (A2BAR). In this review, we first summarize some of the general characteristics of A2BAR, and then we describe the multiple binding partners of the receptor, such as newly identified α-actinin-1 and p105, and discuss how these associated proteins could modulate A2BAR's functions, including certain seemingly paradoxical functions of the receptor. Growing evidence indicates a critical role of A2BAR in cancer, renal disease, and diabetes, in addition to its importance in the regulation of vascular diseases, and lung disease. Here, we also discuss the role of A2BAR in cancer, renal disease, and diabetes and the potential of the receptor as a target for treating these three diseases.
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Affiliation(s)
- Ying Sun
- Department of Biology, South University of Science and Technology of ChinaShenzhen, China; Shenzhen Key Laboratory of Cell Microenvironment, South University of Science and Technology of ChinaShenzhen, China
| | - Pingbo Huang
- Division of Life Science, Hong Kong University of Science and TechnologyHong Kong, China; Division of Biomedical Engineering, Hong Kong University of Science and TechnologyHong Kong, China; State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and TechnologyHong Kong, China
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12
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Lobo MJ, Amaral MD, Zaccolo M, Farinha CM. EPAC1 activation by cAMP stabilizes CFTR at the membrane by promoting its interaction with NHERF1. J Cell Sci 2016; 129:2599-612. [PMID: 27206858 DOI: 10.1242/jcs.185629] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 05/17/2016] [Indexed: 01/14/2023] Open
Abstract
Cyclic AMP (cAMP) activates protein kinase A (PKA) but also the guanine nucleotide exchange factor 'exchange protein directly activated by cAMP' (EPAC1; also known as RAPGEF3). Although phosphorylation by PKA is known to regulate CFTR channel gating - the protein defective in cystic fibrosis - the contribution of EPAC1 to CFTR regulation remains largely undefined. Here, we demonstrate that in human airway epithelial cells, cAMP signaling through EPAC1 promotes CFTR stabilization at the plasma membrane by attenuating its endocytosis, independently of PKA activation. EPAC1 and CFTR colocalize and interact through protein adaptor NHERF1 (also known as SLC9A3R1). This interaction is promoted by EPAC1 activation, triggering its translocation to the plasma membrane and binding to NHERF1. Our findings identify a new CFTR-interacting protein and demonstrate that cAMP activates CFTR through two different but complementary pathways - the well-known PKA-dependent channel gating pathway and a new mechanism regulating endocytosis that involves EPAC1. The latter might constitute a novel therapeutic target for treatment of cystic fibrosis.
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Affiliation(s)
- Miguel J Lobo
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, Lisboa 1749-016, Portugal Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford OX1 3QX, UK
| | - Margarida D Amaral
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, Lisboa 1749-016, Portugal
| | - Manuela Zaccolo
- Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford OX1 3QX, UK
| | - Carlos M Farinha
- University of Lisboa, Faculty of Sciences, BioISI - Biosystems & Integrative Sciences Institute, Campo Grande, Lisboa 1749-016, Portugal
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13
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The adenosine A2B receptor is involved in anion secretion in human pancreatic duct Capan-1 epithelial cells. Pflugers Arch 2016; 468:1171-1181. [PMID: 26965147 PMCID: PMC4943985 DOI: 10.1007/s00424-016-1806-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 02/25/2016] [Accepted: 03/01/2016] [Indexed: 12/13/2022]
Abstract
Adenosine modulates a wide variety of biological processes via adenosine receptors. In the exocrine pancreas, adenosine regulates transepithelial anion secretion in duct cells and is considered to play a role in acini-to-duct signaling. To identify the functional adenosine receptors and Cl− channels important for anion secretion, we herein performed experiments on Capan-1, a human pancreatic duct cell line, using open-circuit Ussing chamber and gramicidin-perforated patch-clamp techniques. The luminal addition of adenosine increased the negative transepithelial potential difference (Vte) in Capan-1 monolayers with a half-maximal effective concentration value of approximately 10 μM, which corresponded to the value obtained on whole-cell Cl− currents in Capan-1 single cells. The effects of adenosine on Vte, an equivalent short-circuit current (Isc), and whole-cell Cl− currents were inhibited by CFTRinh-172, a cystic fibrosis transmembrane conductance regulator (CFTR) Cl− channel inhibitor. The adenosine A2B receptor agonist, BAY 60-6583, increased Isc and whole-cell Cl− currents through CFTR Cl− channels, whereas the A2A receptor agonist, CGS 21680, had negligible effects. The A2B receptor antagonist, PSB 603, inhibited the response of Isc to adenosine. Immunohistochemical analysis showed that the A2A and A2B receptors colocalized with Ezrin in the luminal membranes of Capan-1 monolayers and in rat pancreatic ducts. Adenosine elicited the whole-cell Cl− currents in guinea pig duct cells. These results demonstrate that luminal adenosine regulates anion secretion by activating CFTR Cl− channels via adenosine A2B receptors on the luminal membranes of Capan-1 cells. The present study endorses that purinergic signaling is important in the regulation of pancreatic secretion.
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Sauvanet C, Wayt J, Pelaseyed T, Bretscher A. Structure, Regulation, and Functional Diversity of Microvilli on the Apical Domain of Epithelial Cells. Annu Rev Cell Dev Biol 2015; 31:593-621. [DOI: 10.1146/annurev-cellbio-100814-125234] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Cécile Sauvanet
- Department of Molecular Biology and Genetics and Weill Institute for Molecular and Cell Biology, Cornell University, Ithaca, New York 14853;
| | - Jessica Wayt
- Department of Molecular Biology and Genetics and Weill Institute for Molecular and Cell Biology, Cornell University, Ithaca, New York 14853;
| | - Thaher Pelaseyed
- Department of Molecular Biology and Genetics and Weill Institute for Molecular and Cell Biology, Cornell University, Ithaca, New York 14853;
| | - Anthony Bretscher
- Department of Molecular Biology and Genetics and Weill Institute for Molecular and Cell Biology, Cornell University, Ithaca, New York 14853;
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15
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Peitzman ER, Zaidman NA, Maniak PJ, O'Grady SM. Carvedilol binding to β2-adrenergic receptors inhibits CFTR-dependent anion secretion in airway epithelial cells. Am J Physiol Lung Cell Mol Physiol 2015; 310:L50-8. [PMID: 26566905 DOI: 10.1152/ajplung.00296.2015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 11/06/2015] [Indexed: 01/14/2023] Open
Abstract
Carvedilol functions as a nonselective β-adrenergic receptor (AR)/α1-AR antagonist that is used for treatment of hypertension and heart failure. Carvedilol has been shown to function as an inverse agonist, inhibiting G protein activation while stimulating β-arrestin-dependent signaling and inducing receptor desensitization. In the present study, short-circuit current (Isc) measurements using human airway epithelial cells revealed that, unlike β-AR agonists, which increase Isc, carvedilol decreases basal and 8-(4-chlorophenylthio)adenosine 3',5'-cyclic monophosphate-stimulated current. The decrease in Isc resulted from inhibition of the cystic fibrosis transmembrane conductance regulator (CFTR). The carvedilol effect was abolished by pretreatment with the β2-AR antagonist ICI-118551, but not the β1-AR antagonist atenolol or the α1-AR antagonist prazosin, indicating that its inhibitory effect on Isc was mediated through interactions with apical β2-ARs. However, the carvedilol effect was blocked by pretreatment with the microtubule-disrupting compound nocodazole. Furthermore, immunocytochemistry experiments and measurements of apical CFTR expression by Western blot analysis of biotinylated membranes revealed a decrease in the level of CFTR protein in monolayers treated with carvedilol but no significant change in monolayers treated with epinephrine. These results demonstrate that carvedilol binding to apical β2-ARs inhibited CFTR current and transepithelial anion secretion by a mechanism involving a decrease in channel expression in the apical membrane.
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Affiliation(s)
| | - Nathan A Zaidman
- Department of Integrative Biology and Physiology, University of Minnesota, St. Paul, Minnesota
| | - Peter J Maniak
- Department of Animal Science, University of Minnesota, St. Paul, Minnesota; and
| | - Scott M O'Grady
- Department of Animal Science, University of Minnesota, St. Paul, Minnesota; and Department of Integrative Biology and Physiology, University of Minnesota, St. Paul, Minnesota
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16
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Sauvanet C, Garbett D, Bretscher A. The function and dynamics of the apical scaffolding protein E3KARP are regulated by cell-cycle phosphorylation. Mol Biol Cell 2015; 26:3615-27. [PMID: 26310448 PMCID: PMC4603932 DOI: 10.1091/mbc.e15-07-0498] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 08/18/2015] [Indexed: 11/11/2022] Open
Abstract
We examine the dynamics and function of the apical scaffolding protein E3KARP/NHERF2, which consists of two PDZ domains and a tail containing an ezrin-binding domain. The exchange rate of E3KARP is greatly enhanced during mitosis due to phosphorylation at Ser-303 in its tail region. Whereas E3KARP can substitute for the function of the closely related scaffolding protein EBP50/NHERF1 in the formation of interphase microvilli, E3KARP S303D cannot. Moreover, the S303D mutation enhances the in vivo dynamics of the E3KARP tail alone, whereas in vitro the interaction of E3KARP with active ezrin is unaffected by S303D, implicating another factor regulating dynamics in vivo. A-Raf is found to be required for S303 phosphorylation in mitotic cells. Regulation of the dynamics of EBP50 is known to be dependent on its tail region but modulated by PDZ domain occupancy, which is not the case for E3KARP. Of interest, in both cases, the mechanisms regulating dynamics involve the tails, which are the most diverged region of the paralogues and probably evolved independently after a gene duplication event that occurred early in vertebrate evolution.
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Affiliation(s)
- Cécile Sauvanet
- Department of Molecular Biology and Genetics, Weill Institute for Molecular and Cell Biology, Cornell University, Ithaca, NY 14853
| | - Damien Garbett
- Department of Molecular Biology and Genetics, Weill Institute for Molecular and Cell Biology, Cornell University, Ithaca, NY 14853
| | - Anthony Bretscher
- Department of Molecular Biology and Genetics, Weill Institute for Molecular and Cell Biology, Cornell University, Ithaca, NY 14853
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17
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Soave D, Corvol H, Panjwani N, Gong J, Li W, Boëlle PY, Durie PR, Paterson AD, Rommens JM, Strug LJ, Sun L. A Joint Location-Scale Test Improves Power to Detect Associated SNPs, Gene Sets, and Pathways. Am J Hum Genet 2015; 97:125-38. [PMID: 26140448 PMCID: PMC4572492 DOI: 10.1016/j.ajhg.2015.05.015] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Accepted: 05/26/2015] [Indexed: 11/28/2022] Open
Abstract
Gene-based, pathway, and other multivariate association methods are motivated by the possibility of GxG and GxE interactions; however, accounting for such interactions is limited by the challenges associated with adequate modeling information. Here we propose an easy-to-implement joint location-scale (JLS) association testing framework for single-variant and multivariate analysis that accounts for interactions without explicitly modeling them. We apply the JLS method to a gene-set analysis of cystic fibrosis (CF) lung disease, which is influenced by multiple environmental and genetic factors. We identify and replicate an association between the constituents of the apical plasma membrane and CF lung disease (p = 0.0099 and p = 0.0180, respectively) and highlight a role for the SLC9A3-SLC9A3R1/2-EZR complex in contributing to CF lung disease. Many association studies could benefit from re-analysis with the JLS method that leverages complex genetic architecture for SNP, gene, and pathway identification. Analytical verification, simulation, and additional proof-of-principle applications support our approach.
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Affiliation(s)
- David Soave
- Division of Biostatistics, Dalla Lana School of Public Health, University of Toronto, Toronto, ON M5T 3M7, Canada; Program in Genetics and Genome Biology, Research Institute, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Harriet Corvol
- Assistance Publique-Hôpitaux de Paris (AP-HP), Trousseau Hospital, Pediatric Pulmonology Department; Institut National de la Santé et la Recherche Médicale (INSERM), UMR_S 938, CDR Saint-Antoine, 75012 Paris, France; Sorbonne Universités, Université Pierre et Marie Curie (UPMC) Paris 06, 75005 Paris, France
| | - Naim Panjwani
- Program in Genetics and Genome Biology, Research Institute, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Jiafen Gong
- Program in Genetics and Genome Biology, Research Institute, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Weili Li
- Division of Biostatistics, Dalla Lana School of Public Health, University of Toronto, Toronto, ON M5T 3M7, Canada; Program in Genetics and Genome Biology, Research Institute, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Pierre-Yves Boëlle
- Sorbonne Universités, Université Pierre et Marie Curie (UPMC) Paris 06, 75005 Paris, France; AP-HP, Saint-Antoine Hospital, Biostatistics Department, INSERM, UMR_S 1136, 75012 Paris, France
| | - Peter R Durie
- Program in Physiology and Experimental Medicine, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Department of Pediatrics, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Andrew D Paterson
- Program in Genetics and Genome Biology, Research Institute, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Division of Epidemiology, Dalla Lana School of Public Health, University of Toronto, Toronto, ON M5T 3M7, Canada
| | - Johanna M Rommens
- Program in Genetics and Genome Biology, Research Institute, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Lisa J Strug
- Division of Biostatistics, Dalla Lana School of Public Health, University of Toronto, Toronto, ON M5T 3M7, Canada; Program in Genetics and Genome Biology, Research Institute, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada.
| | - Lei Sun
- Division of Biostatistics, Dalla Lana School of Public Health, University of Toronto, Toronto, ON M5T 3M7, Canada; Department of Statistical Sciences, University of Toronto, Toronto, ON M5S 3G3, Canada.
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18
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Trouvé P, Kerbiriou M, Teng L, Benz N, Taiya M, Le Hir S, Férec C. G551D-CFTR needs more bound actin than wild-type CFTR to maintain its presence in plasma membranes. Cell Biol Int 2015; 39:978-85. [PMID: 25712891 DOI: 10.1002/cbin.10456] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 02/23/2015] [Accepted: 02/23/2015] [Indexed: 12/16/2022]
Abstract
Cystic Fibrosis is due to mutations in the CFTR gene. The missense mutation G551D (approx. 5% of cases) encodes a CFTR chloride channel with normal cell surface expression but with an altered chloride channel activity, leading to a severe phenotype. Our aim was to identify specific interacting proteins of G551D-CFTR which could explain the channel defect. Wild-type CFTR (Wt-CFTR) was co-immunoprecipitated from stably transfected HeLa cells and resolved by 2D gel electrophoresis. Among the detected spots, one was expressed at a high level. Mass Spectrometry revealed that it corresponded to actin which is known to be involved in the CFTR's channel function. To assess whether actin could be involved in the altered G551D-CFTR function, its basal expression was studied. Because actin expression was the same in wt- and in G551D-CFTR expressing cells, its interaction with both wt- and G551D-CFTR was studied by co-immunoprecipitation, and we found that a higher amount of actin was bound onto G551D-CFTR than onto Wt-CFTR. The role of actin upon wt- and G551D-CFTR function was further studied by patch-clamp experiments after cytochalasin D treatment of the cells. We found a decrease of the very weak currents in G551D-CFTR expressing cells. Because a higher amount of actin is bound onto G551D-CFTR than onto Wt-CFTR, it is likely to be not involved in the mutated CFTR's defect. Nevertheless, because actin is necessary to maintain the very weak global currents observed in G551D-CFTR expressing HeLa cells, we conclude that more actin is necessary to maintain G551D-CFTR in the plasma membrane than for Wt-CFTR.
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Affiliation(s)
- Pascal Trouvé
- Inserm, UMR1078, Brest, F-29218, France.,Université de Bretagne Occidentale, Faculté de Médecine et des sciences de la santé, Brest, F-29200, France
| | - Mathieu Kerbiriou
- Inserm, UMR1078, Brest, F-29218, France.,Université de Bretagne Occidentale, Faculté de Médecine et des sciences de la santé, Brest, F-29200, France
| | - Ling Teng
- Inserm, UMR1078, Brest, F-29218, France.,Université de Bretagne Occidentale, Faculté de Médecine et des sciences de la santé, Brest, F-29200, France
| | - Nathalie Benz
- Inserm, UMR1078, Brest, F-29218, France.,Association de Biogénétique Gaëtan Salaün - Bretagne, Brest, F-29200, France
| | - Mehdi Taiya
- Service commun de spectrométrie de masse, Université de Bretagne Occidentale, Brest, F-29200, France
| | - Sophie Le Hir
- Inserm, UMR1078, Brest, F-29218, France.,C.H.U. Brest, Hôpital Morvan, Laboratoire de Génétique Moléculaire, Brest, F-29200, France
| | - Claude Férec
- Inserm, UMR1078, Brest, F-29218, France.,Université de Bretagne Occidentale, Faculté de Médecine et des sciences de la santé, Brest, F-29200, France.,C.H.U. Brest, Hôpital Morvan, Laboratoire de Génétique Moléculaire, Brest, F-29200, France.,Etablissement Français du Sang - Bretagne, Brest, F-29200, France
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19
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Involvement of the Cdc42 pathway in CFTR post-translational turnover and in its plasma membrane stability in airway epithelial cells. PLoS One 2015; 10:e0118943. [PMID: 25768293 PMCID: PMC4359135 DOI: 10.1371/journal.pone.0118943] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 01/07/2015] [Indexed: 12/21/2022] Open
Abstract
Cystic fibrosis transmembrane conductance regulator (CFTR) is a chloride channel that is expressed on the apical plasma membrane (PM) of epithelial cells. The most common deleterious allele encodes a trafficking-defective mutant protein undergoing endoplasmic reticulum-associated degradation (ERAD) and presenting lower PM stability. In this study, we investigated the involvement of the Cdc42 pathway in CFTR turnover and trafficking in a human bronchiolar epithelial cell line (CFBE41o-) expressing wild-type CFTR. Cdc42 is a small GTPase of the Rho family that fulfils numerous cell functions, one of which is endocytosis and recycling process via actin cytoskeleton remodelling. When we treated cells with chemical inhibitors such as ML141 against Cdc42 and wiskostatin against the downstream effector N-WASP, we observed that CFTR channel activity was inhibited, in correlation with a decrease in CFTR amount at the cell surface and an increase in dynamin-dependent CFTR endocytosis. Anchoring of CFTR to the cortical cytoskeleton was then presumably impaired by actin disorganization. When we performed siRNA-mediated depletion of Cdc42, actin polymerization was not impacted, but we observed actin-independent consequences upon CFTR. Total and PM CFTR amounts were increased, resulting in greater activation of CFTR. Pulse-chase experiments showed that while CFTR degradation was slowed, CFTR maturation through the Golgi apparatus remained unaffected. In addition, we observed increased stability of CFTR in PM and reduction of its endocytosis. This study highlights the involvement of the Cdc42 pathway at several levels of CFTR biogenesis and trafficking: (i) Cdc42 is implicated in the first steps of CFTR biosynthesis and processing; (ii) it contributes to the stability of CFTR in PM via its anchoring to cortical actin; (iii) it promotes CFTR endocytosis and presumably its sorting toward lysosomal degradation.
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20
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Suda J, Rockey DC, Karvar S. Phosphorylation dynamics of radixin in hypoxia-induced hepatocyte injury. Am J Physiol Gastrointest Liver Physiol 2015; 308:G313-24. [PMID: 25501552 DOI: 10.1152/ajpgi.00369.2014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The most prominent ezrin-radixin-moesin protein in hepatocytes is radixin, which is localized primarily at the canalicular microvilli and appears to be important in regulation of cell polarity and in localizing the multidrug resistance-associated protein 2 (Mrp-2) function. Our aim was to investigate how hypoxia affects radixin distribution and Mrp-2 function. We created wild-type and mutant constructs (in adenoviral vectors), which were expressed in WIF-B cells. The cellular distribution of Mrp-2 and radixin was visualized by fluorescence microscopy, and a 5-chloromethylfluorescein diacetate (CMFDA) assay was used to measure Mrp-2 function. Under usual conditions, cells infected with wild-type radixin, nonphosphorylatable radixin-T564A, and radixin-T564D (active phospho-mimicking mutant) were found to be heavily expressed in canalicular membrane compartment vacuoles, typically colocalizing with Mrp-2. In contrast, after hypoxia for 24 h, both endogenous and overexpressed wild-type radixin and the radixin-T564A mutant were found to be translocated to the cytoplasmic space. However, distribution of the radixin-T564D mutant, which mimics constant phosphorylation, was remarkably different, being associated with canalicular membranes even in hypoxic conditions. This dominant-active construct also prevented dissociation of radixin from the plasma membrane. Hypoxia also led to Mrp-2 mislocalization and caused Mrp-2 to be dissociated from radixin; the radixin phospho-mimicking mutant (T564D) abrogated this effect of hypoxia. Finally, hypoxia diminished the secretory response (measured using the CMFDA assay) in WIF-B cells, and the dominant-active construct (radixin-T567D) rescued this phenotype. Taken collectively, these findings suggest that radixin regulates Mrp-2 localization and function in hepatocytes and is important in hypoxic liver injury.
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Affiliation(s)
- Jo Suda
- Division of Gastrointestinal and Liver Diseases, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Don C Rockey
- Division of Gastroenterology and Hepatology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - Serhan Karvar
- Division of Gastroenterology and Hepatology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
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21
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Abstract
Thyroid follicular epithelial cells produce thyroxine (T4) and its physiologically active derivative, 3,3',5-triiodothyronine (T3), hormones that regulate critical developmental and metabolic functions. In order for the thyroid to form hormone precursor, iodide, the defining element in thyroid hormone, must cross both blood-facing and luminal sides of the follicular epithelium. The pathway for uptake from blood is well understood, but the mechanism(s) that enable iodide to cross the luminally facing apical membrane remain obscure. This chapter considers the physiological properties of several molecularly characterized anion transport proteins, all of which potentially contribute to the overall mechanism of apical iodide efflux.
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Affiliation(s)
- Peying Fong
- Department of Anatomy and Physiology, Kansas State University College of Veterinary Medicine, Manhattan, Kansas, USA.
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22
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Karvar S, Suda J, Zhu L, Rockey DC. Distribution dynamics and functional importance of NHERF1 in regulation of Mrp-2 trafficking in hepatocytes. Am J Physiol Cell Physiol 2014; 307:C727-37. [PMID: 25163515 DOI: 10.1152/ajpcell.00011.2014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Na(+)/H(+) exchanger regulatory factor 1 (NHERF1) is a multifunctional scaffolding protein that interacts with receptors and ion transporters in its PDZ domains and with the ezrin-radixin-moesin (ERM) family of proteins in its COOH terminus. The role of NHERF1 in hepatocyte function remains largely unknown. We examine the distribution and physiological significance of NHERF1 and multidrug resistance-associated protein 2 (Mrp-2) in hepatocytes. A WT radixin binding site mutant (F355R) and NHERF1 PDZ1 and PDZ2 domain adenoviral mutant constructs were tagged with yellow fluorescent protein and expressed in polarized hepatocytes to study localization and function of NHERF1. Cellular distribution of NHERF1 and radixin was visualized by fluorescence microscopy. A 5-chloromethylfluorescein diacetate (CMFDA) assay was used to characterize Mrp-2 function. Similar to Mrp-2, WT NHERF1 and the NHERF1 PDZ2 deletion mutant were localized to the canalicular membrane. In contrast, the radixin binding site mutant (F355R) and the NHERF1 PDZ1 deletion mutant, which interacts poorly with Mrp-2, were rarely associated with the canalicular membrane. Knockdown of NHERF1 led to dramatically impaired CMFDA secretory response. Use of CMFDA showed that the NHERF1 PDZ1 and F355R mutants were devoid of a secretory response, while WT NHERF1-infected cells exhibited increased secretion of glutathione-methylfluorescein. The data indicate that NHERF1 interacts with Mrp-2 via the PDZ1 domain of NHERF1 and, furthermore, that NHERF1 is essential for maintaining the localization and function of Mrp-2.
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Affiliation(s)
- Serhan Karvar
- Division of Gastroenterology and Hepatology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina;
| | - Jo Suda
- Division of Gastrointestinal and Liver Diseases, Keck School of Medicine, University of Southern California, Los Angeles, California; and
| | - Lixin Zhu
- Digestive Diseases and Nutrition Center, University at Buffalo, State University of New York, Buffalo, New York
| | - Don C Rockey
- Division of Gastroenterology and Hepatology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
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Stimulation of β2-adrenergic receptor increases CFTR function and decreases ATP levels in murine hematopoietic stem/progenitor cells. J Cyst Fibros 2014; 14:26-33. [PMID: 25178873 DOI: 10.1016/j.jcf.2014.08.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 07/15/2014] [Accepted: 08/11/2014] [Indexed: 01/27/2023]
Abstract
BACKGROUND The chloride channel CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) is expressed by many cell types, including hematopoietic stem/progenitor cells (HSPCs). In this study, we sought to better comprehend the regulation of CFTR activity in HSPCs, namely by beta-adrenergic stimuli. METHODS The expression of β2-adrenergic receptor (β2-AR) in murine Sca-1(+) HSPCs was investigated by immunofluorescence/confocal microscopy and flow-cytometric analysis. Association with CFTR was assessed by immunoprecipitation. HSPCs were evaluated for ATP content and CFTR activity by means of luminometric and spectrofluorometric methods, respectively, upon stimulation with salbutamol. RESULTS HSPCs express β2-AR over the whole plasma membrane and are associated in cellula with both the immature and mature forms of CFTR. β2-AR was predominantly expressed by HSPCs with bigger size. CFTR channel activity was increased by salbutamol treatment and this activation was inhibited by either a specific CFTR inhibitor (CFTRinh172) or a β2-AR receptor inhibitor (ICI 118,551). Intracellular ATP levels were reduced by salbutamol stimulation and this effect was reversed when ICI 118,551 or CFTR inhibitors were present. A trend in the increase of extracellular ATP upon salbutamol stimulation was observed. CONCLUSIONS In HSPCs, CFTR is regulated by β2-adrenergic receptor stimulation determining intracellular ATP depletion.
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24
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Nishimura T, Higuchi K, Sai Y, Sugita Y, Yoshida Y, Tomi M, Wada M, Wakayama T, Tamura A, Tsukita S, Soga T, Nakashima E. Fetal growth retardation and lack of hypotaurine in ezrin knockout mice. PLoS One 2014; 9:e105423. [PMID: 25144766 PMCID: PMC4140781 DOI: 10.1371/journal.pone.0105423] [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: 02/03/2014] [Accepted: 07/24/2014] [Indexed: 01/13/2023] Open
Abstract
Ezrin is a membrane-associated cytoplasmic protein that serves to link cell-membrane proteins with the actin-based cytoskeleton, and also plays a role in regulation of the functional activities of some transmembrane proteins. It is expressed in placental trophoblasts. We hypothesized that placental ezrin is involved in the supply of nutrients from mother to fetus, thereby influencing fetal growth. The aim of this study was firstly to clarify the effect of ezrin on fetal growth and secondly to determine whether knockout of ezrin is associated with decreased concentrations of serum and placental nutrients. Ezrin knockout mice (Ez−/−) were confirmed to exhibit fetal growth retardation. Metabolome analysis of fetal serum and placental extract of ezrin knockout mice by means of capillary electrophoresis–time-of-flight mass spectrometry revealed a markedly decreased concentration of hypotaurine, a precursor of taurine. However, placental levels of cysteine and cysteine sulfinic acid (precursors of hypotaurine) and taurine were not affected. Lack of hypotaurine in Ez−/− mice was confirmed by liquid chromatography with tandem mass spectrometry. Administration of hypotaurine to heterogenous dams significantly decreased the placenta-to-maternal plasma ratio of hypotaurine in wild-type fetuses but only slightly decreased it in ezrin knockout fetuses, indicating that the uptake of hypotaurine from mother to placenta is saturable and that disruption of ezrin impairs the uptake of hypotaurine by placental trophoblasts. These results indicate that ezrin is required for uptake of hypotaurine from maternal serum by placental trophoblasts, and plays an important role in fetal growth.
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Affiliation(s)
- Tomohiro Nishimura
- Division of Pharmaceutics, Faculty of Pharmacy, Keio University, Minato-ku, Tokyo, Japan
| | - Kei Higuchi
- Division of Pharmaceutics, Faculty of Pharmacy, Keio University, Minato-ku, Tokyo, Japan
| | - Yoshimichi Sai
- Division of Pharmaceutics, Faculty of Pharmacy, Keio University, Minato-ku, Tokyo, Japan
- Department of Pharmacy, Kanazawa University Hospital, Kanazawa, Japan
| | - Yuki Sugita
- Division of Pharmaceutics, Faculty of Pharmacy, Keio University, Minato-ku, Tokyo, Japan
| | - Yuko Yoshida
- Division of Pharmaceutics, Faculty of Pharmacy, Keio University, Minato-ku, Tokyo, Japan
| | - Masatoshi Tomi
- Division of Pharmaceutics, Faculty of Pharmacy, Keio University, Minato-ku, Tokyo, Japan
| | - Masami Wada
- Division of Pharmaceutics, Faculty of Pharmacy, Keio University, Minato-ku, Tokyo, Japan
- Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Tomohiko Wakayama
- Department of Histology and Embryology, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
| | - Atsushi Tamura
- Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Sachiko Tsukita
- Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Tomoyoshi Soga
- Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, Japan
| | - Emi Nakashima
- Division of Pharmaceutics, Faculty of Pharmacy, Keio University, Minato-ku, Tokyo, Japan
- * E-mail:
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25
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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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26
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Koeppen K, Coutermarsh BA, Madden DR, Stanton BA. Serum- and glucocorticoid-induced protein kinase 1 (SGK1) increases the cystic fibrosis transmembrane conductance regulator (CFTR) in airway epithelial cells by phosphorylating Shank2E protein. J Biol Chem 2014; 289:17142-50. [PMID: 24811177 DOI: 10.1074/jbc.m114.555599] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The glucocorticoid dexamethasone increases cystic fibrosis transmembrane conductance regulator (CFTR) abundance in human airway epithelial cells by a mechanism that requires serum- and glucocorticoid-induced protein kinase 1 (SGK1) activity. The goal of this study was to determine whether SGK1 increases CFTR abundance by phosphorylating Shank2E, a PDZ domain protein that contains two SGK1 phosphorylation consensus sites. We found that SGK1 phosphorylates Shank2E as well as a peptide containing the first SGK1 consensus motif of Shank2E. The dexamethasone-induced increase in CFTR abundance was diminished by overexpression of a dominant-negative Shank2E in which the SGK1 phosphorylation sites had been mutated. siRNA-mediated reduction of Shank2E also reduced the dexamethasone-induced increase in CFTR abundance. Taken together, these data demonstrate that the glucocorticoid-induced increase in CFTR abundance requires phosphorylation of Shank2E at an SGK1 consensus site.
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Affiliation(s)
- Katja Koeppen
- From the Department of Microbiology and Immunology and
| | | | - Dean R Madden
- Department of Biochemistry, The Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755
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27
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Ren L, Khanna C. Role of ezrin in osteosarcoma metastasis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 804:181-201. [PMID: 24924175 DOI: 10.1007/978-3-319-04843-7_10] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The cause of death for the vast majority of cancer patients is the development of metastases at sites distant from that of the primary tumor. For most pediatric sarcoma patients such as those with osteosarcoma (OS), despite successful management of the primary tumor through multimodality approaches, the development of metastases, commonly to the lungs, is the cause of death. Significant improvements in long-term outcome for these patients have not been seen in more than 30 years. Furthermore, the long-term outcome for patients who present with metastatic disease is grave [1-5]. New treatment options are needed.Opportunities to improve outcomes for patients who present with metastases and those at-risk for progression and metastasis require an improved understanding of cancer progression and metastasis. With this goal in mind we and others have identified ezrin as a metastasis-associated protein that associated with OS and other cancers. Ezrin is the prototypical ERM (Ezrin/Radixin/Moesin) protein family member. ERMs function as linker proteins connecting the actin cytoskeleton and the plasma membrane. Since our initial identification of ezrin in pediatric sarcoma, an increasing understanding the role of ezrin in metastasis has emerged. Briefly, ezrin appears to allow metastatic cells to overcome a number of stresses experienced during the metastatic cascade, most notably the stress experienced as cells interact with the microenvironment of the secondary site. Cells must rapidly adapt to this environment in order to survive. Evidence now suggests a connection between ezrin expression and a variety of mechanisms linked to this important cellular adaptation including the ability of metastatic cells to initiate the translation of new proteins and to allow the efficient generation of ATP through a variety of sources. This understanding of the role of ezrin in the biology of metastasis is now sufficient to consider ezrin as an important therapeutic target in osteosarcoma patients. This chapter reviews our understanding of ezrin and the related ERM proteins in normal tissues and physiology, summarizes the expression of ezrin in human cancers and associations with clinical parameters of disease progression, reviews reports that detail a biological understanding of ezrin's role in metastatic progression, and concludes with a rationale that may be considered to target ezrin and ezrin biology in osteosarcoma.
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Affiliation(s)
- Ling Ren
- Molecular Oncology Section - Metastasis Biology Group, Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 37 Convent Dr., Rm 2144, Bethesda, MD, 20892, USA,
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Frizzell RA, Hanrahan JW. Physiology of epithelial chloride and fluid secretion. Cold Spring Harb Perspect Med 2013; 2:a009563. [PMID: 22675668 DOI: 10.1101/cshperspect.a009563] [Citation(s) in RCA: 154] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Epithelial salt and water secretion serves a variety of functions in different organ systems, such as the airways, intestines, pancreas, and salivary glands. In cystic fibrosis (CF), the volume and/or composition of secreted luminal fluids are compromised owing to mutations in the gene encoding CFTR, the apical membrane anion channel that is responsible for salt secretion in response to cAMP/PKA stimulation. This article examines CFTR and related cellular transport processes that underlie epithelial anion and fluid secretion, their regulation, and how these processes are altered in CF disease to account for organ-specific secretory phenotypes.
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Affiliation(s)
- Raymond A Frizzell
- Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
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Sun C, Zheng J, Cheng S, Feng D, He J. EBP50 phosphorylation by Cdc2/Cyclin B kinase affects actin cytoskeleton reorganization and regulates functions of human breast cancer cell line MDA-MB-231. Mol Cells 2013; 36:47-54. [PMID: 23775624 PMCID: PMC3887931 DOI: 10.1007/s10059-013-0014-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 04/29/2013] [Accepted: 05/03/2013] [Indexed: 10/26/2022] Open
Abstract
The actin cytoskeleton plays an important role in cell shape determination, adhesion and cell cycle progression. Ezrinradixin-moesin (ERM)-binding phosphoprotein 50 (EBP50), also known as Na(+)-H(+) exchanger regulatory factor 1 (NHERF1), associates with actin cytoskeleton and is related to cell cycle progression. Its Ser279 and Ser301 residues are phosphorylated by cyclin-dependent kinase 2 (cdc2)/cyclin B during the mitosis phase. However, the biological significance of EBP50 phosphorylation mediated by cdc2/cyclin B is not clear. In the present study, MDA-MB-231 cells with low levels of endogenous EBP50 protein were stably transfected with constructs of EBP50 wild type (WT), phosphodeficient (serine 279 and serine 301 mutated to alanine-S279A/S301A) or phospho-mimetic (serine 279 and serine 301 mutated to aspartic acid-S279D/S301D) mutants. Subsequently, multiple phenotypes of these cells were characterized. Failure of cdc2/cyclin B-mediated EBP50 phosphorylation in cells expressing S279A/S301A (AA cells) significantly increased F-actin content, enhanced the adherence of cells to the extracellular matrix, altered cell morphology and caused defects in cytokinesis, as reflected in the formation of giant cells with heteroploid DNA and multinucleation or giant nuclei. Furthermore, knockdown of EBP50 expression in AA cells rescued cell defects such as the cytokinesis failure and abnormal cell morphology. EBP50 S279A/ S301A had a weaker binding affinity with actin than EBP50 S279D/S301D, which might explain the increase of F-actin content in the AA cells. The present results suggest that cdc2/cyclin B-mediated EBP50 phosphorylation may play a role in the regulation of various cell functions by affecting actin cytoskeleton reorganization.
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Affiliation(s)
- Chaoyuan Sun
- Department of Biochemistry and Molecular Biology, Capital Medical University, Beijing 100069,
China
| | - Junfang Zheng
- Department of Biochemistry and Molecular Biology, Capital Medical University, Beijing 100069,
China
| | - Shan Cheng
- Department of Biochemistry and Molecular Biology, Capital Medical University, Beijing 100069,
China
| | - Duiping Feng
- Department of Radiology, First Hospital of Shanxi Medical University, Taiyuan 030001,
China
| | - Junqi He
- Department of Biochemistry and Molecular Biology, Capital Medical University, Beijing 100069,
China
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Insulin-like growth factor 1 (IGF-1) enhances the protein expression of CFTR. PLoS One 2013; 8:e59992. [PMID: 23555857 PMCID: PMC3610909 DOI: 10.1371/journal.pone.0059992] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Accepted: 02/25/2013] [Indexed: 11/19/2022] Open
Abstract
Low levels of insulin-like growth factor 1 (IGF-1) have been observed in the serum of cystic fibrosis (CF) patients. However, the effects of low serum IGF-1 on the cystic fibrosis transmembrane conductance regulator (CFTR), whose defective function is the primary cause of cystic fibrosis, have not been studied. Here, we show in human cells that IGF-1 increases the steady-state levels of mature wildtype CFTR in a CFTR-associated ligand (CAL)- and TC10-dependent manner; moreover, IGF-1 increases CFTR-mediated chloride transport. Using an acceptor photobleaching fluorescence resonance energy transfer (FRET) assay, we have confirmed the binding of CAL and CFTR in the Golgi. We also show that CAL overexpression inhibits forskolin-induced increases in the cell-surface expression of CFTR. We found that IGF-1 activates TC10, and active TC10 alters the functional association between CAL and CFTR. Furthermore, IGF-1 and active TC10 can reverse the CAL-mediated reduction in the cell-surface expression of CFTR. IGF-1 does not increase the expression of ΔF508 CFTR, whose processing is arrested in the ER. This finding is consistent with our observation that IGF-1 alters the functional interaction of CAL and CFTR in the Golgi. However, when ΔF508 CFTR is rescued with low temperature or the corrector VRT-325 and proceeds to the Golgi, IGF-1 can increase the expression of the rescued ΔF508 CFTR. Our data support a model indicating that CAL-CFTR binding in the Golgi inhibits CFTR trafficking to the cell surface, leading CFTR to the degradation pathway instead. IGF-1-activated TC10 changes the interaction of CFTR and CAL, allowing CFTR to progress to the plasma membrane. These findings offer a potential strategy using a combinational treatment of IGF-1 and correctors to increase the post-Golgi expression of CFTR in cystic fibrosis patients bearing the ΔF508 mutation.
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Mondini A, Sassone F, Civello DA, Garavaglia ML, Bazzini C, Rodighiero S, Vezzoli V, Conti F, Torielli L, Capasso G, Paulmichl M, Meyer G. Hypertension-linked mutation of α-adducin increases CFTR surface expression and activity in HEK and cultured rat distal convoluted tubule cells. PLoS One 2012; 7:e52014. [PMID: 23284854 PMCID: PMC3528715 DOI: 10.1371/journal.pone.0052014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 11/08/2012] [Indexed: 11/18/2022] Open
Abstract
The CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) activity and localization are influenced by the cytoskeleton, in particular by actin and its polymerization state. In this study we investigated whether the expression of the hypertensive mutations of α-adducin (G460W-S586C in humans, F316Y in rats), an actin capping protein, led to a functional modification of CFTR activity and surface expression. The experiments were performed on HEK293 T cells cotransfected with CFTR and the human wild type (WT) or G460W mutated α-adducin. In whole-cell patch-clamp experiments, both the CFTR chloride current and the slope of current activation after forskolin addition were significantly higher in HEK cells overexpressing the G460W adducin. A higher plasma membrane density of active CFTR channels was confirmed by cell-attached patch-clamp experiments, both in HEK cells and in cultured primary DCT cells, isolated from MHS (Milan Hypertensive Strain, a Wistar rat (Rattus norvegicus) hypertensive model carrying the F316Y adducin mutation), compared to MNS (Milan Normotensive Strain) rats. Western blot experiments demonstrated an increase of the plasma membrane CFTR protein expression, with a modification of the channel glycosylation state, in the presence of the mutated adducin. A higher retention of CFTR protein in the plasma membrane was confirmed both by FRAP (Fluorescence Recovery After Photobleaching) and photoactivation experiments. The present data indicate that in HEK cells and in isolated DCT cells the presence of the G460W-S586C hypertensive variant of adducin increases CFTR channel activity, possibly by altering its membrane turnover and inducing a retention of the channel in the plasmamembrane. Since CFTR is known to modulate the activity of many others transport systems, the increased surface expression of the channel could have consequences on the whole network of transport in kidney cells.
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Affiliation(s)
- Anna Mondini
- Department of Life Sciences, Università degli Studi di Milano, Milano, Italy
| | - Francesca Sassone
- Department of Life Sciences, Università degli Studi di Milano, Milano, Italy
| | | | | | - Claudia Bazzini
- Department of Life Sciences, Università degli Studi di Milano, Milano, Italy
| | | | - Valeria Vezzoli
- Department of Life Sciences, Università degli Studi di Milano, Milano, Italy
| | - Fabio Conti
- Prassis Research Institute, Sigma Tau, Settimo M.se, Italy
| | - Lucia Torielli
- Prassis Research Institute, Sigma Tau, Settimo M.se, Italy
| | | | - Markus Paulmichl
- Institut of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
| | - Giuliano Meyer
- Department of Life Sciences, Università degli Studi di Milano, Milano, Italy
- * E-mail:
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Castellani S, Guerra L, Favia M, Di Gioia S, Casavola V, Conese M. NHERF1 and CFTR restore tight junction organisation and function in cystic fibrosis airway epithelial cells: role of ezrin and the RhoA/ROCK pathway. J Transl Med 2012; 92:1527-40. [PMID: 22964850 DOI: 10.1038/labinvest.2012.123] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Tight junctions (TJs) restrict the transit of ions and molecules through the paracellular route and act as a barrier to regulate access of inflammatory cells into the airway lumen. The pathophysiology of cystic fibrosis (CF) lung disease is characterised by abnormal ion and fluid transport across the epithelium and polymorphonuclear (PMN) leukocyte-dominated inflammatory response. Na⁺/H⁺ exchanger regulatory factor 1 (NHERF1) is a protein involved in PKA-dependent activation of CFTR by interacting with CFTR via its PDZ domains and with ezrin via its C-terminal domain. We have previously found that the NHERF1-overexpression dependent rescue CFTR-dependent chloride secretion is due to the re-organisation of the actin cytoskeleton network induced by the formation of the multiprotein complex NHERF1-RhoA-ezrin-actin. In this context, we here studied whether NHERF1 and CFTR are involved in the organisation and function of TJs. F508del CFBE41o⁻ monolayers presented nuclear localisation of zonula occludens (ZO-1) and occludin as well as disorganisation of claudin 1 and junction-associated adhesion molecule 1 as compared with wild-type 16HBE14o⁻ monolayers, paralleled by increased permeability to dextrans and PMN transmigration. Overexpression of either NHERF1 or CFTR in CFBE41o⁻ cells rescued TJ proteins to their proper intercellular location and decreased permeability and PMN transmigration, while this effect was not achieved by overexpressing either NHERF1 deprived of ezrin-binding domain. Further, expression of a phospho-dead ezrin mutant, T567A, increased permeability in both 16HBE14o⁻ cells and in a CFBE clone stably overexpressing NHERF1 (CFBE/sNHERF1), whereas a constitutively active form of ezrin, T567D, achieved the opposite effect in CFBE41o⁻ cells. A dominant-negative form of RhoA (RhoA-N19) also disrupted ZO-1 localisation at the intercellular contacts dislodging it to the nucleus and increased permeability in CFBE/sNHERF1. The inhibitor Y27632 of Rho kinase (ROCK) increased permeability as well. Overall, these data suggest a significant role for the multiprotein complex CFTR-NHERF1-ezrin-actin in maintaining TJ organisation and barrier function, and suggest that the RhoA/ROCK pathway is involved.
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Affiliation(s)
- Stefano Castellani
- Department of Medical and Surgical Sciences, University of Foggia, Foggia, Italy
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Duan Y, Sun Y, Zhang F, Zhang WK, Wang D, Wang Y, Cao X, Hu W, Xie C, Cuppoletti J, Magin TM, Wang H, Wu Z, Li N, Huang P. Keratin K18 increases cystic fibrosis transmembrane conductance regulator (CFTR) surface expression by binding to its C-terminal hydrophobic patch. J Biol Chem 2012; 287:40547-59. [PMID: 23045527 DOI: 10.1074/jbc.m112.403584] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND CFTR function is tightly regulated by many interacting proteins. RESULTS Intermediate filament protein keratin 18 increases the cell surface expression of CFTR by interacting with the C-terminal hydrophobic patch of CFTR. CONCLUSION K18 controls the function of CFTR. SIGNIFICANCE These findings offer novel insights into the regulation of CFTR and suggest that K18 and its dimerization partner, K8, may be modifier genes in cystic fibrosis. Malfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) leads to cystic fibrosis, but the regulation of CFTR is not fully understood. Here, we identified the intermediate filament protein keratin K18 (K18) as a CFTR-binding protein by various approaches. We mapped a highly conserved "hydrophobic patch" ((1413)FLVI(1416)) in the CFTR C-terminus, known to determine plasmalemmal CFTR stability, as the K18-binding site. On the other hand, the C-terminal tail of K18 was found to be a critical determinant for binding CFTR. Overexpression of K18 in cells robustly increased the surface expression of wild-type CFTR, whereas depletion of K18 through RNA interference specifically diminished it. K18 binding increased the surface expression of CFTR by accelerating its apical recycling rate without altering CFTR biosynthesis, maturation, or internalization. Importantly, CFTR surface expression was markedly reduced in duodenal and gallbladder epithelia of K18(-/-) mice. Taken together, our results suggest that K18 increases the cell surface expression of CFTR by interacting with the CFTR C-terminal hydrophobic patch. These findings offer novel insights into the regulation of CFTR and suggest that K18 and its dimerization partner, K8, may be modifier genes in cystic fibrosis.
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Affiliation(s)
- Yuanyuan Duan
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong, China
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Molinski S, Eckford PDW, Pasyk S, Ahmadi S, Chin S, Bear CE. Functional Rescue of F508del-CFTR Using Small Molecule Correctors. Front Pharmacol 2012; 3:160. [PMID: 23055971 PMCID: PMC3458236 DOI: 10.3389/fphar.2012.00160] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Accepted: 08/17/2012] [Indexed: 01/21/2023] Open
Abstract
High-throughput screens for small molecules that are effective in “correcting” the functional expression of F508del-CFTR have yielded several promising hits. Two such compounds are currently in clinical trial. Despite this success, it is clear that further advances will be required in order to restore 50% or greater of wild-type CFTR function to the airways of patients harboring the F508del-CFTR protein. Progress will be enhanced by our better understanding of the molecular and cellular defects caused by the F508del mutation, present in 90% of CF patients. The goal of this chapter is to review the current understanding of defects caused by F508del in the CFTR protein and in CFTR-mediated interactions important for its biosynthesis, trafficking, channel function, and stability at the cell surface. Finally, we will discuss the gaps in our knowledge regarding the mechanism of action of existing correctors, the unmet need to discover compounds which restore proper CFTR structure and function in CF affected tissues and new strategies for therapy development.
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Affiliation(s)
- Steven Molinski
- Programme in Molecular Structure and Function, Research Institute, Hospital for Sick Children Toronto, ON, Canada ; Department of Biochemistry, University of Toronto Toronto, ON, Canada
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Hagiwara K, Nagamori S, Umemura YM, Ohgaki R, Tanaka H, Murata D, Nakagomi S, Nomura KH, Kage-Nakadai E, Mitani S, Nomura K, Kanai Y. NRFL-1, the C. elegans NHERF orthologue, interacts with amino acid transporter 6 (AAT-6) for age-dependent maintenance of AAT-6 on the membrane. PLoS One 2012; 7:e43050. [PMID: 22916205 PMCID: PMC3419730 DOI: 10.1371/journal.pone.0043050] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Accepted: 07/18/2012] [Indexed: 12/11/2022] Open
Abstract
The NHERF (Na(+)/H(+) exchanger regulatory factor) family has been proposed to play a key role in regulating transmembrane protein localization and retention at the plasma membrane. Due to the high homology between the family members, potential functional compensations have been a concern in sorting out the function of individual NHERF numbers. Here, we studied C. elegans NRFL-1 (C01F6.6) (nherf-like protein 1), the sole C. elegans orthologue of the NHERF family, which makes worm a model with low genetic redundancy of NHERF homologues. Integrating bioinformatic knowledge of C. elegans proteins into yeast two-hybrid scheme, we identified NRFL-1 as an interactor of AAT-6, a member of the C. elegans AAT (amino acid transporter) family. A combination of GST pull-down assay, localization study, and co-immunoprecipitation confirmed the binding and characterized the PDZ interaction. AAT-6 localizes to the luminal membrane even in the absence of NRFL-1 when the worm is up to four-day old. A fluorescence recovery after photobleaching (FRAP) analysis suggested that NRFL-1 immobilizes AAT-6 at the luminal membrane. When the nrfl-1 deficient worm is six-day or older, in contrast, the membranous localization of AAT-6 is not observed, whereas AAT-6 tightly localizes to the membrane in worms with NRFL-1. Sorting out the in vivo functions of the C. elegans NHERF protein, we found that NRFL-1, a PDZ-interactor of AAT-6, is responsible for the immobilization and the age-dependent maintenance of AAT-6 on the intestinal luminal membrane.
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Affiliation(s)
- Kohei Hagiwara
- Division of Bio-system Pharmacology, Department of Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan
- School of Medicine, Osaka University, Osaka, Japan
| | - Shushi Nagamori
- Division of Bio-system Pharmacology, Department of Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Yasuhiro M. Umemura
- Division of Bio-system Pharmacology, Department of Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Ryuichi Ohgaki
- Division of Bio-system Pharmacology, Department of Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Hidekazu Tanaka
- Division of Bio-system Pharmacology, Department of Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Daisuke Murata
- Graduate School of Systems Life Sciences, Kyushu University, Fukuoka, Japan
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Saitama, Japan
| | - Saya Nakagomi
- Division of Bio-system Pharmacology, Department of Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Kazuko H. Nomura
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Saitama, Japan
- Department of Biological Sciences, Faculty of Sciences, Kyushu University, Fukuoka, Japan
| | - Eriko Kage-Nakadai
- Department of Physiology, Tokyo Women’s Medical University School of Medicine, Tokyo, Japan
| | - Shohei Mitani
- Department of Physiology, Tokyo Women’s Medical University School of Medicine, Tokyo, Japan
| | - Kazuya Nomura
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Saitama, Japan
- Department of Biological Sciences, Faculty of Sciences, Kyushu University, Fukuoka, Japan
| | - Yoshikatsu Kanai
- Division of Bio-system Pharmacology, Department of Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Saitama, Japan
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Wu Y, Wang S, Li C. In vitro analysis of PDZ-dependent CFTR macromolecular signaling complexes. J Vis Exp 2012:4091. [PMID: 22907480 DOI: 10.3791/4091] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Cystic fibrosis transmembrane conductance regulator (CFTR), a chloride channel located primarily at the apical membranes of epithelial cells, plays a crucial role in transepithelial fluid homeostasis(1-3). CFTR has been implicated in two major diseases: cystic fibrosis (CF)(4) and secretory diarrhea(5). In CF, the synthesis or functional activity of the CFTR Cl- channel is reduced. This disorder affects approximately 1 in 2,500 Caucasians in the United States(6). Excessive CFTR activity has also been implicated in cases of toxin-induced secretory diarrhea (e.g., by cholera toxin and heat stable E. coli enterotoxin) that stimulates cAMP or cGMP production in the gut(7). Accumulating evidence suggest the existence of physical and functional interactions between CFTR and a growing number of other proteins, including transporters, ion channels, receptors, kinases, phosphatases, signaling molecules, and cytoskeletal elements, and these interactions between CFTR and its binding proteins have been shown to be critically involved in regulating CFTR-mediated transepithelial ion transport in vitro and also in vivo(8-19). In this protocol, we focus only on the methods that aid in the study of the interactions between CFTR carboxyl terminal tail, which possesses a protein-binding motif [referred to as PSD95/Dlg1/ZO-1 (PDZ) motif], and a group of scaffold proteins, which contain a specific binding module referred to as PDZ domains. So far, several different PDZ scaffold proteins have been reported to bind to the carboxyl terminal tail of CFTR with various affinities, such as NHERF1, NHERF2, PDZK1, PDZK2, CAL (CFTR-associated ligand), Shank2, and GRASP(20-27). The PDZ motif within CFTR that is recognized by PDZ scaffold proteins is the last four amino acids at the C terminus (i.e., 1477-DTRL-1480 in human CFTR)(20). Interestingly, CFTR can bind more than one PDZ domain of both NHERFs and PDZK1, albeit with varying affinities(22). This multivalency with respect to CFTR binding has been shown to be of functional significance, suggesting that PDZ scaffold proteins may facilitate formation of CFTR macromolecular signaling complexes for specific/selective and efficient signaling in cells(16-18). Multiple biochemical assays have been developed to study CFTR-involving protein interactions, such as co-immunoprecipitation, pull-down assay, pair-wise binding assay, colorimetric pair-wise binding assay, and macromolecular complex assembly assay(16-19,28,29). Here we focus on the detailed procedures of assembling a PDZ motif-dependent CFTR-containing macromolecular complex in vitro, which is used extensively by our laboratory to study protein-protein or domain-domain interactions involving CFTR(16-19,28,29).
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Affiliation(s)
- Yanning Wu
- Department of Biochemistry & Molecular Biology, Wayne State University School of Medicine, USA
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37
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Wang B, Means CK, Yang Y, Mamonova T, Bisello A, Altschuler DL, Scott JD, Friedman PA. Ezrin-anchored protein kinase A coordinates phosphorylation-dependent disassembly of a NHERF1 ternary complex to regulate hormone-sensitive phosphate transport. J Biol Chem 2012; 287:24148-63. [PMID: 22628548 PMCID: PMC3397842 DOI: 10.1074/jbc.m112.369405] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 05/19/2012] [Indexed: 12/14/2022] Open
Abstract
Congenital defects in the Na/H exchanger regulatory factor-1 (NHERF1) are linked to disordered phosphate homeostasis and skeletal abnormalities in humans. In the kidney, these mutations interrupt parathyroid hormone (PTH)-responsive sequestration of the renal phosphate transporter, Npt2a, with ensuing urinary phosphate wasting. We now report that NHERF1, a modular PDZ domain scaffolding protein, coordinates the assembly of an obligate ternary complex with Npt2a and the PKA-anchoring protein ezrin to facilitate PTH-responsive cAMP signaling events. Activation of ezrin-anchored PKA initiates NHERF1 phosphorylation to disassemble the ternary complex, release Npt2a, and thereby inhibit phosphate transport. Loss-of-function mutations stabilize an inactive NHERF1 conformation that we show is refractory to PKA phosphorylation and impairs assembly of the ternary complex. Compensatory mutations introduced in mutant NHERF1 re-establish the integrity of the ternary complex to permit phosphorylation of NHERF1 and rescue PTH action. These findings offer new insights into a novel macromolecular mechanism for the physiological action of a critical ternary complex, where anchored PKA coordinates the assembly and turnover of the Npt2a-NHERF1-ezrin complex.
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Affiliation(s)
- Bin Wang
- From the Laboratory for G Protein-coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261 and
| | - Chris K. Means
- the Howard Hughes Medical Institute, Department of Pharmacology, University of Washington School of Medicine, Seattle, Washington 98195
| | - Yanmei Yang
- From the Laboratory for G Protein-coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261 and
| | - Tatyana Mamonova
- From the Laboratory for G Protein-coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261 and
| | - Alessandro Bisello
- From the Laboratory for G Protein-coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261 and
| | - Daniel L. Altschuler
- From the Laboratory for G Protein-coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261 and
| | - John D. Scott
- the Howard Hughes Medical Institute, Department of Pharmacology, University of Washington School of Medicine, Seattle, Washington 98195
| | - Peter A. Friedman
- From the Laboratory for G Protein-coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261 and
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38
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Teng L, Kerbiriou M, Taiya M, Le Hir S, Mignen O, Benz N, Trouvé P, Férec C. Proteomic identification of calumenin as a G551D-CFTR associated protein. PLoS One 2012; 7:e40173. [PMID: 22768251 PMCID: PMC3387016 DOI: 10.1371/journal.pone.0040173] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Accepted: 06/06/2012] [Indexed: 12/12/2022] Open
Abstract
Cystic fibrosis (CF) is the most common lethal autosomal recessive disease in the Caucasian population. It is due to mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. To date, over 1910 mutations have been identified in the CFTR gene. Among these mutations, the CF-causing missense mutation G551D-CFTR (approx. 5% of cases) encodes for a CFTR chloride channel with normal expression on the cell surface. Nevertheless, it is associated with severe disease due to its altered channel activation. The aim of the present study was to identify specific interacting proteins of G551D-CFTR. Co-immunoprecipitated proteins with G551D-CFTR were resolved by 2D-gel electrophoresis (2-DE). Mass Spectrometry revealed that calumenin was present in the protein complex linked to G551D-CFTR. Despite its basal expression was not modified in G551D-CFTR expressing cells when compared to Wt-CFTR expressing cells, it was more abundant in the G551D-CFTR complex detected by immunoprecipitation. The calumenin-CFTR interaction was also shown by Surface Plasmon Resonance and further confirmed by computational analysis of the predicted calumenin’s partners. Because in our cellular model calumenin was found in the endoplasmic reticulum (ER) by immunofluorescence experiments, we suggest that calumenin is likely involved in the mutated CFTR’s maturation. In conclusion, we showed for the first time that calumenin binds to CFTR and that it is increased in the G551D-CFTR complex. We suggest that it may be involved in the physiopathology of G551D-CFTR and that G551D-CFTR may follow a specific maturation and trafficking pathway. We also hypothesize that UPR may be triggered independently of the retention of G551D-CFTR in the ER because Grp78/Bip expression is increased in the cells. Finally, we propose here that Calumenin is a new CFTR chaperone.
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Affiliation(s)
- Ling Teng
- Inserm, UMR1078, Brest, France
- Université de Bretagne Occidentale, Faculté de Médecine et des sciences de la santé, Brest, France
| | - Mathieu Kerbiriou
- Inserm, UMR1078, Brest, France
- Université de Bretagne Occidentale, Faculté de Médecine et des sciences de la santé, Brest, France
| | - Mehdi Taiya
- Université de Bretagne Occidentale, Service commun de spectrométrie de masse, Brest, France
| | - Sophie Le Hir
- Inserm, UMR1078, Brest, France
- C.H.R.U. Morvan, Laboratoire de Génétique Moléculaire, Brest, France
| | - Olivier Mignen
- Inserm, UMR1078, Brest, France
- Université de Bretagne Occidentale, Faculté de Médecine et des sciences de la santé, Brest, France
| | - Nathalie Benz
- Inserm, UMR1078, Brest, France
- Association de Biogénétique Gaëtan Salaün, Brest, France
| | - Pascal Trouvé
- Inserm, UMR1078, Brest, France
- Université de Bretagne Occidentale, Faculté de Médecine et des sciences de la santé, Brest, France
- * E-mail: (PT); (CF)
| | - Claude Férec
- Inserm, UMR1078, Brest, France
- Université de Bretagne Occidentale, Faculté de Médecine et des sciences de la santé, Brest, France
- C.H.R.U. Morvan, Laboratoire de Génétique Moléculaire, Brest, France
- Etablissement Français du Sang, Brest, France
- * E-mail: (PT); (CF)
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Fong P. CFTR-SLC26 transporter interactions in epithelia. Biophys Rev 2012; 4:107-116. [PMID: 22685498 PMCID: PMC3369697 DOI: 10.1007/s12551-012-0068-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Accepted: 01/23/2012] [Indexed: 12/18/2022] Open
Abstract
Transport mechanisms that mediate the movements of anions must be coordinated tightly in order to respond appropriately to physiological stimuli. This process is of paramount importance in the function of diverse epithelial tissues of the body, such as, for example, the exocrine pancreatic duct and the airway epithelia. Disruption of any of the finely tuned components underlying the transport of anions such as Cl(-), HCO(3) (-), SCN(-), and I(-) may contribute to a plethora of disease conditions. In many anion-secreting epithelia, the interactions between the cystic fibrosis transmembrane conductance regulator (CFTR) and solute carrier family 26 (SLC26) transporters determine the final exit of anions across the apical membrane and into the luminal compartment. The molecular identification of CFTR and many SLC26 members has enabled the acquisition of progressively more detailed structural information about these transport molecules. Studies employing a vast array of increasingly sophisticated approaches have culminated in a current working model which places these key players within an interactive complex, thereby setting the stage for future work.
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Affiliation(s)
- Peying Fong
- Department of Anatomy and Physiology, Kansas State University College of Veterinary Medicine, 1600 Denison Avenue, Manhattan, KS 66506 USA
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40
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Monterisi S, Favia M, Guerra L, Cardone RA, Marzulli D, Reshkin SJ, Casavola V, Zaccolo M. CFTR regulation in human airway epithelial cells requires integrity of the actin cytoskeleton and compartmentalized cAMP and PKA activity. J Cell Sci 2012; 125:1106-17. [PMID: 22302988 DOI: 10.1242/jcs.089086] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) mutation ΔF508CFTR still causes regulatory defects when rescued to the apical membrane, suggesting that the intracellular milieu might affect its ability to respond to cAMP regulation. We recently reported that overexpression of the Na(+)/H(+) exchanger regulatory factor NHERF1 in the cystic fibrosis (CF) airway cell line CFBE41o-rescues the functional expression of ΔF508CFTR by promoting F-actin organization and formation of the NHERF1-ezrin-actin complex. Here, using real-time FRET reporters of both PKA activity and cAMP levels, we find that lack of an organized subcortical cytoskeleton in CFBE41o-cells causes both defective accumulation of cAMP in the subcortical compartment and excessive cytosolic accumulation of cAMP. This results in reduced subcortical levels and increased cytosolic levels of PKA activity. NHERF1 overexpression in CFBE41o-cells restores chloride secretion, subcortical cAMP compartmentalization and local PKA activity, indicating that regulation of ΔF508CFTR function requires not only stable expression of the mutant CFTR at the cell surface but also depends on both generation of local cAMP signals of adequate amplitude and activation of PKA in proximity of its target. Moreover, we found that the knockdown of wild-type CFTR in the non-CF 16HBE14o-cells results in both altered cytoskeletal organization and loss of cAMP compartmentalization, whereas stable overexpression of wt CFTR in CF cells restores cytoskeleton organization and re-establishes the compartmentalization of cAMP at the plasma membrane. This suggests that the presence of CFTR on the plasma membrane influences the cytoskeletal organizational state and, consequently, cAMP distribution. Our data show that a sufficiently high concentration of cAMP in the subcortical compartment is required to achieve PKA-mediated regulation of CFTR activity.
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Affiliation(s)
- Stefania Monterisi
- Department of General and Environmental Physiology, University of Bari, Bari, 70125, Italy
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41
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Liang X, Da Paula AC, Bozóky Z, Zhang H, Bertrand CA, Peters KW, Forman-Kay JD, Frizzell RA. Phosphorylation-dependent 14-3-3 protein interactions regulate CFTR biogenesis. Mol Biol Cell 2012; 23:996-1009. [PMID: 22278744 PMCID: PMC3302758 DOI: 10.1091/mbc.e11-08-0662] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
cAMP/PKA stimulation elicited posttranslational increases in CFTR expression and the interaction of specific 14-3-3 proteins with phosphorylated sites within the R region. This improved the efficiency of nascent CFTR biogenesis and reduced its interaction with the COPI retrograde retrieval mechanism, making more CFTR available for anion secretion. Cystic fibrosis transmembrane conductance regulator (CFTR) is a cAMP/protein kinase A (PKA)–regulated chloride channel whose phosphorylation controls anion secretion across epithelial cell apical membranes. We examined the hypothesis that cAMP/PKA stimulation regulates CFTR biogenesis posttranslationally, based on predicted 14-3-3 binding motifs within CFTR and forskolin-induced CFTR expression. The 14-3-3β, γ, and ε isoforms were expressed in airway cells and interacted with CFTR in coimmunoprecipitation assays. Forskolin stimulation (15 min) increased 14-3-3β and ε binding to immature and mature CFTR (bands B and C), and 14-3-3 overexpression increased CFTR bands B and C and cell surface band C. In pulse-chase experiments, 14-3-3β increased the synthesis of immature CFTR, reduced its degradation rate, and increased conversion of immature to mature CFTR. Conversely, 14-3-3β knockdown decreased CFTR B and C bands (70 and 55%) and elicited parallel reductions in cell surface CFTR and forskolin-stimulated anion efflux. In vitro, 14-3-3β interacted with the CFTR regulatory region, and by nuclear magnetic resonance analysis, this interaction occurred at known PKA phosphorylated sites. In coimmunoprecipitation assays, forskolin stimulated the CFTR/14-3-3β interaction while reducing CFTR's interaction with coat protein complex 1 (COP1). Thus 14-3-3 binding to phosphorylated CFTR augments its biogenesis by reducing retrograde retrieval of CFTR to the endoplasmic reticulum. This mechanism permits cAMP/PKA stimulation to make more CFTR available for anion secretion.
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Affiliation(s)
- Xiubin Liang
- Department of Cell Biology and Physiology, University of Pittsburgh, Pittsburgh, PA 15261, USA
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42
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Functional regulation of cystic fibrosis transmembrane conductance regulator-containing macromolecular complexes: a small-molecule inhibitor approach. Biochem J 2011; 435:451-62. [PMID: 21299497 DOI: 10.1042/bj20101725] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
CFTR (cystic fibrosis transmembrane conductance regulator) has been shown to form multiple protein macromolecular complexes with its interacting partners at discrete subcellular microdomains to modulate trafficking, transport and signalling in cells. Targeting protein-protein interactions within these macromolecular complexes would affect the expression or function of the CFTR channel. We specifically targeted the PDZ domain-based LPA2 (type 2 lysophosphatidic acid receptor)-NHERF2 (Na+/H+ exchanger regulatory factor-2) interaction within the CFTR-NHERF2-LPA2-containing macromolecular complexes in airway epithelia and tested its regulatory role on CFTR channel function. We identified a cell-permeable small-molecule compound that preferentially inhibits the LPA2-NHERF2 interaction. We show that this compound can disrupt the LPA2-NHERF2 interaction in cells and thus compromises the integrity of macromolecular complexes. Functionally, it elevates cAMP levels in proximity to CFTR and upregulates its channel activity. The results of the present study demonstrate that CFTR Cl- channel function can be finely tuned by modulating PDZ domain-based protein-protein interactions within the CFTR-containing macromolecular complexes. The present study might help to identify novel therapeutic targets to treat diseases associated with dysfunctional CFTR Cl- channels.
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Ardura JA, Friedman PA. Regulation of G protein-coupled receptor function by Na+/H+ exchange regulatory factors. Pharmacol Rev 2011; 63:882-900. [PMID: 21873413 DOI: 10.1124/pr.110.004176] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Many G protein-coupled receptors (GPCR) exert patterns of cell-specific signaling and function. Mounting evidence now supports the view that cytoplasmic adapter proteins contribute critically to this behavior. Adapter proteins recognize highly conserved motifs such as those for Src homology 3 (SH3), phosphotyrosine-binding (PTB), and postsynaptic density 95/discs-large/zona occludens (PDZ) docking sequences in candidate GPCRs. Here we review the behavior of the Na+/H+ exchange regulatory factor (NHERF) family of PDZ adapter proteins on GPCR signalling, trafficking, and function. Structural determinants of NHERF proteins that allow them to recognize targeted GPCRs are considered. NHERF1 and NHERF2 are capable also of modifying the assembled complex of accessory proteins such as β-arrestins, which have been implicated in regulating GPCR signaling. In addition, NHERF1 and NHERF2 modulate GPCR signaling by altering the G protein to which the receptor binds or affect other regulatory proteins that affect GTPase activity, protein kinase A, phospholipase C, or modify downstream signaling events. Small molecules targeting the site of NHERF1-GPCR interaction are being developed and may become important and selective drug candidates.
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Affiliation(s)
- Juan A Ardura
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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44
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Clapéron A, Mergey M, Fouassier L. Roles of the scaffolding proteins NHERF in liver biology. Clin Res Hepatol Gastroenterol 2011; 35:176-81. [PMID: 21501979 DOI: 10.1016/j.clinre.2010.11.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 11/16/2010] [Accepted: 11/23/2010] [Indexed: 02/04/2023]
Abstract
Scaffold proteins are defined by the presence of specific protein-binding domains (e.g. PDZ domains) that assemble several proteins into functional complexes. Thus, scaffolds are critical for spatio-temporal organization and for proper regulation of intracellular signalling upon specific stimulus. Identified 15years ago, NHERF scaffold proteins contain several PDZ modules and were initially viewed as "passive linkers" between transmembrane proteins and the cortical cytoskeleton underlying the plasma membrane. New NHERF-binding molecules involved in cell signalling have been recently identified. Thus, NHERFs are now viewed as "active" key players in regulating cellular functions. EBP50 and PDZK1, two members of the NHERF family, are highly expressed in the liver where they link receptors, channels, transporters and cytosolic components. This review aims to give an overview of the emerging functions of NHERF proteins in liver physiology.
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45
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Martinez E, Schroeder GN, Berger CN, Lee SF, Robinson KS, Badea L, Simpson N, Hall RA, Hartland EL, Crepin VF, Frankel G. Binding to Na(+) /H(+) exchanger regulatory factor 2 (NHERF2) affects trafficking and function of the enteropathogenic Escherichia coli type III secretion system effectors Map, EspI and NleH. Cell Microbiol 2011; 12:1718-31. [PMID: 20618342 PMCID: PMC3015060 DOI: 10.1111/j.1462-5822.2010.01503.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Enteropathogenic Escherichia coli (EPEC) strains are diarrhoeal pathogens that use a type III secretion system to translocate effector proteins into host cells in order to colonize and multiply in the human gut. Map, EspI and NleH1 are conserved EPEC effectors that possess a C-terminal class I PSD-95/Disc Large/ZO-1 (PDZ)-binding motif. Using a PDZ array screen we identified Na+/H+ exchanger regulatory factor 2 (NHERF2), a scaffold protein involved in tethering and recycling ion channels in polarized epithelia that contains two PDZ domains, as a common target of Map, EspI and NleH1. Using recombinant proteins and co-immunoprecipitation we confirmed that NHERF2 binds each of the effectors. We generated a HeLa cell line stably expressing HA-tagged NHERF2 and found that Map, EspI and NleH1 colocalize and interact with intracellular NHERF2 via their C-terminal PDZ-binding motif. Overexpression of NHERF2 enhanced the formation and persistence of Map-induced filopodia, accelerated the trafficking of EspI to the Golgi and diminished the anti-apoptotic activity of NleH1. The binding of multiple T3SS effectors to a single scaffold protein is unique. Our data suggest that NHERF2 may act as a plasma membrane sorting site, providing a novel regulatory mechanism to control the intracellular spatial and temporal effector protein activity.
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Affiliation(s)
- Eric Martinez
- Centre for Molecular Microbiology and Infection, Imperial College London, UK
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46
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Abstract
Cystic fibrosis transmembrane conductance regulator (CFTR) is a chloride channel localized primarily at the apical surface of epithelial cells lining the airway, gut, exocrine glands, etc., where it is responsible for transepithelial salt and water transport. A growing number of proteins have been reported to interact directly or indirectly with CFTR chloride channel, suggesting that CFTR might regulate the activities of other ion channels, receptors, and transporters, in addition to its role as a chloride conductor. Most interactions occur primarily between the opposing terminal tails (N or C) of CFTR and its binding partners, either directly or mediated through various PDZ domain-containing proteins. This chapter describes methods we developed to cross-link CFTR into a macromolecular complex to identify and analyze the assembly and regulation of CFTR-containing complexes in the plasma membrane.
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47
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Cushing PR, Vouilleme L, Pellegrini M, Boisguerin P, Madden DR. A stabilizing influence: CAL PDZ inhibition extends the half-life of ΔF508-CFTR. Angew Chem Int Ed Engl 2010; 49:9907-11. [PMID: 21105033 PMCID: PMC3033200 DOI: 10.1002/anie.201005585] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
| | - Lars Vouilleme
- Institute of Medical Immunology, Charité – Universitätsmedizin, 10115 Berlin, Germany
| | | | - Prisca Boisguerin
- Institute of Medical Immunology, Charité – Universitätsmedizin, 10115 Berlin, Germany
| | - Dean R. Madden
- Dept. of Biochemistry, Dartmouth Medical School, Hanover, NH 03755, USA
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48
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Cushing PR, Vouilleme L, Pellegrini M, Boisguerin P, Madden DR. A Stabilizing Influence: CAL PDZ Inhibition Extends the Half-Life of ΔF508-CFTR. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.201005585] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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49
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Faria D, Dahimène S, Alessio L, Scott-Ward T, Schreiber R, Kunzelmann K, Amaral MD. Effect of Annexin A5 on CFTR: regulated traffic or scaffolding? Mol Membr Biol 2010; 28:14-29. [PMID: 21067452 DOI: 10.3109/09687688.2010.506264] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Previous studies have implicated annexins in regulating ion channels and in particular annexin A5 (AnxA5) in the traffic of the cystic fibrosis transmembrane conductance regulator (CFTR). In the present study, we further investigated the role of AnxA5 in regulating CFTR function and intracellular trafficking in both Xenopus oocytes and mammalian cells. Although we could confirm the previously reported CFTR/AnnxA5 interaction, we found that in oocytes AnxA5 inhibits CFTR-mediated whole-cell membrane conductance presumably by a mechanism independent of PDZ-binding domain at the C-terminus of CFTR but protein kinase C (PKC)-dependent and results from either endocytosis activation and/or exocytosis block. In contrast, in human cells, co-expression of AnxA5 augmented CFTR whole-cell currents, an effect that was independent of CFTR PDZ-binding domain. We conclude that annexin A5 has multiple effects on CFTR, so that the net effect observed is cell system-dependent. Nevertheless, both effects observed here are consistent with the described role of annexins forming scaffolding platforms at cell membranes, thus contributing to a decrease in their dynamics. Finally, we could not confirm that AnxA5 overexpression rescues traffic/function of the most frequent disease-causing mutant F508del-CFTR, thus concluding that AnxA5 is not a promising tool for correction of the F508del-CFTR defect.
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Affiliation(s)
- Diana Faria
- Department of Physiology, University of Regensburg, Germany
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50
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Zhu L, Crothers J, Zhou R, Forte JG. A possible mechanism for ezrin to establish epithelial cell polarity. Am J Physiol Cell Physiol 2010; 299:C431-43. [PMID: 20505040 DOI: 10.1152/ajpcell.00090.2010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ezrin is an important membrane/actin cytoskeleton linker protein, especially in epithelia. Ezrin has two important binding domains: an NH(2)-terminal region that binds to plasma membrane and a COOH-terminal region that binds to F-actin only after a conformational activation by phosphorylation at Thr567 of ezrin. The present experiments were undertaken to investigate the detailed cellular changes in the time course of expression of ezrin-T567 mutants (nonphosphorylatable T567A and permanent phospho-mimic T567D) in parietal cells and to assess ezrin distribution and its influence on the elaborate membrane recruitment processes of these cells. T567A mutant and wild-type (WT) ezrin were consistently localized to the apical plasma membrane, even with overexpression. On the other hand, T567D went first to apical membrane at early times and low expression levels, then accumulated mainly at the basal surface after 24 h. Overexpression of WT or T567A led to incorporation of internal membranes to apical vacuoles, while overexpression of T567D led to large incorporation of apical and intracellular membranes (including H-K-ATPase) to the basal surface. Differences in polar distribution of ezrin suggest a role for the linker protein in promoting formation and plasticity of membrane surface projections, forming the basis for a novel theory for ezrin as an organizer and regulator of membrane recruitment. A model simulating the cellular distribution of ezrin and its associated membrane- and F-actin-binding forms is given to predict redistributions observed with phosphorylation and mutant overexpression, and it can easily be modified as more specific information regarding binding constants and specific sites becomes available.
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Affiliation(s)
- Lixin Zhu
- Department of Pediatrics, State University of New York at Buffalo, Buffalo, New York, USA
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