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McDonald EF, Kim M, Olson JA, Meiler J, Plate L. Proteostasis Landscapes of Selective versus Poorly Responsive CFTR Variants Reveals Structural Vulnerabilities to Correction. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.10.602964. [PMID: 39026768 PMCID: PMC11257600 DOI: 10.1101/2024.07.10.602964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Cystic Fibrosis (CF) is a lethal genetic disorder caused by variants in CF transmembrane conductance regulator (CFTR). Many disease variants are treatable with corrector compounds, which enhance the folding and trafficking of CFTR. However, correctors fail to elicit a response for every CFTR variant. Approximately 3% of persons with CF harbor poorly responsive CFTR variants. Here, we reveal that a group of poorly responsive variants overlap with selectively responsive variants in a critical domain interface (nucleotide-binding domain 1/intracellular loop 4 - NBD1/ICL4). Affinity purification mass spectrometry proteomics was used to profile the protein homeostasis (proteostasis) changes of CFTR variants during corrector treatment to assess modulated interactions with protein folding and maturation pathways. Responsive variant interactions converged on similar proteostasis pathways during correction. In contrast, poorly responsive variants subtly diverged, revealing a partial restoration of protein quality control surveillance and a capacity to correct some mutations. Computational structural modeling showed that corrector VX-445 failed to confer enough NBD1 stability to poorly responsive variants. NBD1 secondary stabilizing mutations rescued poorly responsive variants, revealing structural vulnerabilities in NBD1 required for treating poor responders. Our study provides a framework for discerning the underlying protein quality control and structural defects of CFTR variants not reached with existing drugs. These insights can help expand therapeutics to all susceptible CFTR variants to enhance personalized medicine efforts.
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Affiliation(s)
- Eli Fritz McDonald
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - Minsoo Kim
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
- Chemical and Physical Biology Program, Vanderbilt University, Nashville, TN 37240, USA
| | - John A Olson
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
- Chemical and Physical Biology Program, Vanderbilt University, Nashville, TN 37240, USA
| | - Jens Meiler
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37240, USA
- Institute for Drug Discovery, Leipzig University, Leipzig, SAC 04103, Germany
| | - Lars Plate
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37240, USA
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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2
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Laghmani K. Protein Quality Control of NKCC2 in Bartter Syndrome and Blood Pressure Regulation. Cells 2024; 13:818. [PMID: 38786040 PMCID: PMC11120568 DOI: 10.3390/cells13100818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Revised: 05/03/2024] [Accepted: 05/09/2024] [Indexed: 05/25/2024] Open
Abstract
Mutations in NKCC2 generate antenatal Bartter syndrome type 1 (type 1 BS), a life-threatening salt-losing nephropathy characterized by arterial hypotension, as well as electrolyte abnormalities. In contrast to the genetic inactivation of NKCC2, inappropriate increased NKCC2 activity has been associated with salt-sensitive hypertension. Given the importance of NKCC2 in salt-sensitive hypertension and the pathophysiology of prenatal BS, studying the molecular regulation of this Na-K-2Cl cotransporter has attracted great interest. Therefore, several studies have addressed various aspects of NKCC2 regulation, such as phosphorylation and post-Golgi trafficking. However, the regulation of this cotransporter at the pre-Golgi level remained unknown for years. Similar to several transmembrane proteins, export from the ER appears to be the rate-limiting step in the cotransporter's maturation and trafficking to the plasma membrane. The most compelling evidence comes from patients with type 5 BS, the most severe form of prenatal BS, in whom NKCC2 is not detectable in the apical membrane of thick ascending limb (TAL) cells due to ER retention and ER-associated degradation (ERAD) mechanisms. In addition, type 1 BS is one of the diseases linked to ERAD pathways. In recent years, several molecular determinants of NKCC2 export from the ER and protein quality control have been identified. The aim of this review is therefore to summarize recent data regarding the protein quality control of NKCC2 and to discuss their potential implications in BS and blood pressure regulation.
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Affiliation(s)
- Kamel Laghmani
- Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université de Paris, F-75006 Paris, France;
- CNRS, ERL8228, F-75006 Paris, France
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3
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Farinha CM, Santos L, Ferreira JF. Cell type-specific regulation of CFTR trafficking-on the verge of progress. Front Cell Dev Biol 2024; 12:1338892. [PMID: 38505263 PMCID: PMC10949533 DOI: 10.3389/fcell.2024.1338892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Accepted: 02/21/2024] [Indexed: 03/21/2024] Open
Abstract
Trafficking of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein is a complex process that starts with its biosynthesis and folding in the endoplasmic reticulum. Exit from the endoplasmic reticulum (ER) is coupled with the acquisition of a compact structure that can be processed and traffic through the secretory pathway. Once reaching its final destination-the plasma membrane, CFTR stability is regulated through interaction with multiple protein partners that are involved in its post-translation modification, connecting the channel to several signaling pathways. The complexity of the process is further boosted when analyzed in the context of the airway epithelium. Recent advances have characterized in detail the different cell types that compose the surface epithelium and shifted the paradigm on which cells express CFTR and on their individual and combined contribution to the total expression (and function) of this chloride/bicarbonate channel. Here we review CFTR trafficking and its relationship with the knowledge on the different cell types of the airway epithelia. We explore the crosstalk between these two areas and discuss what is still to be clarified and how this can be used to develop more targeted therapies for CF.
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Affiliation(s)
- Carlos M. Farinha
- Faculty of Sciences, BioISI—Biosystems and Integrative Sciences Institute, University of Lisboa, Lisboa, Portugal
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4
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Santinelli R, Benz N, Guellec J, Quinquis F, Kocas E, Thomas J, Montier T, Ka C, Luczka-Majérus E, Sage E, Férec C, Coraux C, Trouvé P. The Inhibition of the Membrane-Bound Transcription Factor Site-1 Protease (MBTP1) Alleviates the p.Phe508del-Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Defects in Cystic Fibrosis Cells. Cells 2024; 13:185. [PMID: 38247876 PMCID: PMC10814821 DOI: 10.3390/cells13020185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 12/27/2023] [Accepted: 01/11/2024] [Indexed: 01/23/2024] Open
Abstract
Cystic Fibrosis (CF) is present due to mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene, the most frequent variant being p.phe508del. The CFTR protein is a chloride (Cl-) channel which is defective and almost absent of cell membranes when the p.Phe508del mutation is present. The p.Phe508del-CFTR protein is retained in the endoplasmic reticulum (ER) and together with inflammation and infection triggers the Unfolded Protein Response (UPR). During the UPR, the Activating Transcription Factor 6 (ATF6) is activated with cleavage and then decreases the expression of p.Phe508del-CFTR. We have previously shown that the inhibition of the activation of ATF6 alleviates the p.Phe508del-CFTR defects in cells overexpressing the mutated protein. In the present paper, our aim was to inhibit the cleavage of ATF6, and thus its activation in a human bronchial cell line with endogenous p.Phe508del-CFTR expression and in bronchial cells from patients, to be more relevant to CF. This was achieved by inhibiting the protease MBTP1 which is responsible for the cleavage of ATF6. We show here that this inhibition leads to increased mRNA and p.Phe508del-CFTR expression and, consequently, to increased Cl-efflux. We also explain the mechanisms linked to these increases with the modulation of genes when MBTP1 is inhibited. Indeed, RT-qPCR assays show that genes such as HSPA1B, CEBPB, VIMP, PFND2, MAPK8, XBP1, INSIG1, and CALR are modulated. In conclusion, we show that the inhibition of MBTP1 has a beneficial effect in relevant models to CF and that this is due to the modulation of genes involved in the disease.
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Affiliation(s)
- Raphaël Santinelli
- Univ Brest, Inserm, EFS, UMR 1078, 22 Avenue Camille Desmoulins, F-29200 Brest, France; (R.S.); (N.B.); (J.G.); (F.Q.); (E.K.); (J.T.); (T.M.); (C.K.); (C.F.)
| | - Nathalie Benz
- Univ Brest, Inserm, EFS, UMR 1078, 22 Avenue Camille Desmoulins, F-29200 Brest, France; (R.S.); (N.B.); (J.G.); (F.Q.); (E.K.); (J.T.); (T.M.); (C.K.); (C.F.)
| | - Julie Guellec
- Univ Brest, Inserm, EFS, UMR 1078, 22 Avenue Camille Desmoulins, F-29200 Brest, France; (R.S.); (N.B.); (J.G.); (F.Q.); (E.K.); (J.T.); (T.M.); (C.K.); (C.F.)
| | - Fabien Quinquis
- Univ Brest, Inserm, EFS, UMR 1078, 22 Avenue Camille Desmoulins, F-29200 Brest, France; (R.S.); (N.B.); (J.G.); (F.Q.); (E.K.); (J.T.); (T.M.); (C.K.); (C.F.)
| | - Ervin Kocas
- Univ Brest, Inserm, EFS, UMR 1078, 22 Avenue Camille Desmoulins, F-29200 Brest, France; (R.S.); (N.B.); (J.G.); (F.Q.); (E.K.); (J.T.); (T.M.); (C.K.); (C.F.)
| | - Johan Thomas
- Univ Brest, Inserm, EFS, UMR 1078, 22 Avenue Camille Desmoulins, F-29200 Brest, France; (R.S.); (N.B.); (J.G.); (F.Q.); (E.K.); (J.T.); (T.M.); (C.K.); (C.F.)
| | - Tristan Montier
- Univ Brest, Inserm, EFS, UMR 1078, 22 Avenue Camille Desmoulins, F-29200 Brest, France; (R.S.); (N.B.); (J.G.); (F.Q.); (E.K.); (J.T.); (T.M.); (C.K.); (C.F.)
| | - Chandran Ka
- Univ Brest, Inserm, EFS, UMR 1078, 22 Avenue Camille Desmoulins, F-29200 Brest, France; (R.S.); (N.B.); (J.G.); (F.Q.); (E.K.); (J.T.); (T.M.); (C.K.); (C.F.)
| | - Emilie Luczka-Majérus
- Inserm UMR-S 1250, University of Reims Champagne-Ardenne (URCA), SFR Cap-Santé, F-51100 Reims, France; (E.L.-M.); (C.C.)
| | - Edouard Sage
- Université Paris-Saclay, INRAE, UVSQ, VIM, F-78350 Jouy-en-Josas, France;
| | - Claude Férec
- Univ Brest, Inserm, EFS, UMR 1078, 22 Avenue Camille Desmoulins, F-29200 Brest, France; (R.S.); (N.B.); (J.G.); (F.Q.); (E.K.); (J.T.); (T.M.); (C.K.); (C.F.)
| | - Christelle Coraux
- Inserm UMR-S 1250, University of Reims Champagne-Ardenne (URCA), SFR Cap-Santé, F-51100 Reims, France; (E.L.-M.); (C.C.)
| | - Pascal Trouvé
- Univ Brest, Inserm, EFS, UMR 1078, 22 Avenue Camille Desmoulins, F-29200 Brest, France; (R.S.); (N.B.); (J.G.); (F.Q.); (E.K.); (J.T.); (T.M.); (C.K.); (C.F.)
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5
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McDonald EF, Meiler J, Plate L. CFTR Folding: From Structure and Proteostasis to Cystic Fibrosis Personalized Medicine. ACS Chem Biol 2023; 18:2128-2143. [PMID: 37730207 PMCID: PMC10595991 DOI: 10.1021/acschembio.3c00310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 08/02/2023] [Indexed: 09/22/2023]
Abstract
Cystic fibrosis (CF) is a lethal genetic disease caused by mutations in the chloride ion channel cystic fibrosis transmembrane conductance regulator (CFTR). Class-II mutants of CFTR lack intermolecular interactions important for CFTR structural stability and lead to misfolding. Misfolded CFTR is detected by a diverse suite of proteostasis factors that preferentially bind and route mutant CFTR toward premature degradation, resulting in reduced plasma membrane CFTR levels and impaired chloride ion conductance associated with CF. CF treatment has been vastly improved over the past decade by the availability of small molecules called correctors. Correctors directly bind CFTR, stabilize its structure by conferring thermodynamically favorable interactions that compensate for mutations, and thereby lead to downstream folding fidelity. However, each of over 100 Class-II CF causing mutations causes unique structural defects and shows a unique response to drug treatment, described as theratype. Understanding CFTR structural defects, the proteostasis factors evaluating those defects, and the stabilizing effects of CFTR correctors will illuminate a path toward personalized medicine for CF. Here, we review recent advances in our understanding of CFTR folding, focusing on structure, corrector binding sites, the mechanisms of proteostasis factors that evaluate CFTR, and the implications for CF personalized medicine.
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Affiliation(s)
- Eli Fritz McDonald
- Department
of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
- Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Jens Meiler
- Department
of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
- Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37240, United States
- Department
of Pharmacology, Vanderbilt University, Nashville, Tennessee 37240, United States
- Institute
for Drug Discovery, Leipzig University, Leipzig, SAC 04103, Germany
| | - Lars Plate
- Department
of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department
of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department
of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
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6
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Kim M, McDonald EF, Sabusap CMP, Timalsina B, Joshi D, Hong JS, Rab A, Sorscher EJ, Plate L. Elexacaftor/VX-445-mediated CFTR interactome remodeling reveals differential correction driven by mutation-specific translational dynamics. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.04.527134. [PMID: 36778339 PMCID: PMC9915750 DOI: 10.1101/2023.02.04.527134] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Cystic fibrosis (CF) is one of the most prevalent lethal genetic diseases with over 2000 identified mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Pharmacological chaperones such as Lumacaftor (VX-809), Tezacaftor (VX-661) and Elexacaftor (VX-445) treat mutation-induced defects by stabilizing CFTR and are called correctors. These correctors improve proper folding and thus facilitate processing and trafficking to increase the amount of functional CFTR on the cell surface. Yet, CFTR variants display differential responses to each corrector. Here, we report variants P67L and L206W respond similarly to VX-809 but divergently to VX-445 with P67L exhibiting little rescue when treated with VX-445. We investigate the underlying cellular mechanisms of how CFTR biogenesis is altered by correctors in these variants. Affinity purification-mass spectrometry (AP-MS) multiplexed with isobaric Tandem Mass Tags (TMT) was used to quantify CFTR protein-protein interaction changes between variants P67L and L206W. VX-445 facilitates unique proteostasis factor interactions especially in translation, folding, and degradation pathways in a CFTR variant-dependent manner. A number of these interacting proteins knocked down by siRNA, such as ribosomal subunit proteins, moderately rescued fully glycosylated P67L. Importantly, these knock-downs sensitize P67L to VX-445 and further enhance the correction of this variant. Our results provide a better understanding of VX-445 biological mechanism of action and reveal cellular targets that may sensitize unresponsive CFTR variants to known and available correctors.
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Affiliation(s)
- Minsoo Kim
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States of America
- Program in Chemical and Physical Biology, Vanderbilt University, Nashville, TN, United States of America
| | - Eli Fritz McDonald
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States of America
| | | | - Bibek Timalsina
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States of America
| | - Disha Joshi
- Department of Pediatrics, Emory University, Atlanta, GA, United States of America
| | - Jeong S. Hong
- Department of Pediatrics, Emory University, Atlanta, GA, United States of America
| | - Andras Rab
- Department of Pediatrics, Emory University, Atlanta, GA, United States of America
| | - Eric J. Sorscher
- Department of Pediatrics, Emory University, Atlanta, GA, United States of America
| | - Lars Plate
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States of America
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, United States of America
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, United States of America
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7
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DNAJA1- and conformational mutant p53-dependent inhibition of cancer cell migration by a novel compound identified through a virtual screen. Cell Death Dis 2022; 8:437. [PMID: 36316326 PMCID: PMC9622836 DOI: 10.1038/s41420-022-01229-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 10/17/2022] [Accepted: 10/19/2022] [Indexed: 11/06/2022]
Abstract
Cancers are frequently addicted to oncogenic missense mutant p53 (mutp53). DNAJA1, a member of heat shock protein 40 (HSP40), also known as J-domain proteins (JDPs), plays a crucial role in the stabilization and oncogenic activity of misfolded or conformational mutp53 by binding to and preventing mutp53 from proteasomal degradation. However, strategies to deplete mutp53 are not well-established, and no HSP40/JDPs inhibitors are clinically available. To identify compounds that bind to DNAJA1 and induce mutp53 degradation, we performed an in silico docking study of ~10 million of compounds from the ZINC database for the J-domain of DNAJA1. A compound 7-3 was identified, and its analogue A11 effectively reduced the levels of DNAJA1 and conformational mutp53 with minimal effects on the levels of wild-type p53 and DNA-contact mutp53. A11 suppressed migration and filopodia formation in a manner dependent on DNAJA1 and conformational mutp53. A mutant DNAJA1 with alanine mutations at predicted amino acids (tyrosine 7, lysine 44, and glutamine 47) failed to bind to A11. Cells expressing the mutant DNAJA1 became insensitive to A11-mediated depletion of DNAJA1 and mutp53 as well as A11-mediated inhibition of cell migration. Thus, A11 is the first HSP40/JDP inhibitor that has not been previously characterized for depleting DNAJA1 and subsequently conformational mutp53, leading to inhibition of cancer cell migration. A11 can be exploited for a novel treatment against cancers expressing conformational mutp53.
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8
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The Astonishing Large Family of HSP40/DnaJ Proteins Existing in Leishmania. Genes (Basel) 2022; 13:genes13050742. [PMID: 35627127 PMCID: PMC9141911 DOI: 10.3390/genes13050742] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/14/2022] [Accepted: 04/21/2022] [Indexed: 02/04/2023] Open
Abstract
Abrupt environmental changes are faced by Leishmania parasites during transmission from a poikilothermic insect vector to a warm-blooded host. Adaptation to harsh environmental conditions, such as nutrient deprivation, hypoxia, oxidative stress and heat shock needs to be accomplished by rapid reconfiguration of gene expression and remodeling of protein interaction networks. Chaperones play a central role in the maintenance of cellular homeostasis, and they are responsible for crucial tasks such as correct folding of nascent proteins, protein translocation across different subcellular compartments, avoiding protein aggregates and elimination of damaged proteins. Nearly one percent of the gene content in the Leishmania genome corresponds to members of the HSP40 family, a group of proteins that assist HSP70s in a variety of cellular functions. Despite their expected relevance in the parasite biology and infectivity, little is known about their functions or partnership with the different Leishmania HSP70s. Here, we summarize the structural features of the 72 HSP40 proteins encoded in the Leishmania infantum genome and their classification into four categories. A review of proteomic data, together with orthology analyses, allow us to postulate cellular locations and possible functional roles for some of them. A detailed study of the members of this family would provide valuable information and opportunities for drug discovery and improvement of current treatments against leishmaniasis.
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9
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Brusa I, Sondo E, Falchi F, Pedemonte N, Roberti M, Cavalli A. Proteostasis Regulators in Cystic Fibrosis: Current Development and Future Perspectives. J Med Chem 2022; 65:5212-5243. [PMID: 35377645 PMCID: PMC9014417 DOI: 10.1021/acs.jmedchem.1c01897] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In cystic fibrosis (CF), the deletion of phenylalanine 508 (F508del) in the CF transmembrane conductance regulator (CFTR) leads to misfolding and premature degradation of the mutant protein. These defects can be targeted with pharmacological agents named potentiators and correctors. During the past years, several efforts have been devoted to develop and approve new effective molecules. However, their clinical use remains limited, as they fail to fully restore F508del-CFTR biological function. Indeed, the search for CFTR correctors with different and additive mechanisms has recently increased. Among them, drugs that modulate the CFTR proteostasis environment are particularly attractive to enhance therapy effectiveness further. This Perspective focuses on reviewing the recent progress in discovering CFTR proteostasis regulators, mainly describing the design, chemical structure, and structure-activity relationships. The opportunities, challenges, and future directions in this emerging and promising field of research are discussed, as well.
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Affiliation(s)
- Irene Brusa
- Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy.,Computational & Chemical Biology, Istituto Italiano di Tecnologia, 16163 Genova, Italy
| | - Elvira Sondo
- UOC Genetica Medica, IRCCS Istituto Giannina Gaslini, 16147 Genova, Italy
| | | | | | - Marinella Roberti
- Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy
| | - Andrea Cavalli
- Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy.,Computational & Chemical Biology, Istituto Italiano di Tecnologia, 16163 Genova, Italy
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10
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Iazzi M, Astori A, St-Germain J, Raught B, Gupta GD. Proximity Profiling of the CFTR Interaction Landscape in Response to Orkambi. Int J Mol Sci 2022; 23:2442. [PMID: 35269585 PMCID: PMC8910062 DOI: 10.3390/ijms23052442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 02/19/2022] [Accepted: 02/21/2022] [Indexed: 01/27/2023] Open
Abstract
Deletion of phenylalanine 508 (∆F508) of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) anion channel protein is the leading cause of Cystic Fibrosis (CF). Here, we report the analysis of CFTR and ∆F508-CFTR interactomes using BioID (proximity-dependent biotin identification), a technique that can also detect transient associations. We identified 474 high-confidence CFTR proximity-interactors, 57 of which have been previously validated, with the remainder representing novel interaction space. The ∆F508 interactome, comprising 626 proximity-interactors was markedly different from its wild type counterpart, with numerous alterations in protein associations categorized in membrane trafficking and cellular stress functions. Furthermore, analysis of the ∆F508 interactome in cells treated with Orkambi identified several interactions that were altered as a result of this drug therapy. We examined two candidate CFTR proximity interactors, VAPB and NOS1AP, in functional assays designed to assess surface delivery and overall chloride efflux. VAPB depletion impacted both CFTR surface delivery and chloride efflux, whereas NOS1AP depletion only affected the latter. The wild type and ∆F508-CFTR interactomes represent rich datasets that could be further mined to reveal additional candidates for the functional rescue of ∆F508-CFTR.
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Affiliation(s)
- Melissa Iazzi
- Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada;
| | - Audrey Astori
- Department of Medical Biophysics, University of Toronto, Toronto, ON M5S 1A1, Canada; (A.A.); (J.S.-G.); (B.R.)
| | - Jonathan St-Germain
- Department of Medical Biophysics, University of Toronto, Toronto, ON M5S 1A1, Canada; (A.A.); (J.S.-G.); (B.R.)
| | - Brian Raught
- Department of Medical Biophysics, University of Toronto, Toronto, ON M5S 1A1, Canada; (A.A.); (J.S.-G.); (B.R.)
| | - Gagan D. Gupta
- Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada;
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11
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Kaida A, Iwakuma T. Regulation of p53 and Cancer Signaling by Heat Shock Protein 40/J-Domain Protein Family Members. Int J Mol Sci 2021; 22:13527. [PMID: 34948322 PMCID: PMC8706882 DOI: 10.3390/ijms222413527] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 12/13/2021] [Accepted: 12/14/2021] [Indexed: 12/27/2022] Open
Abstract
Heat shock proteins (HSPs) are molecular chaperones that assist diverse cellular activities including protein folding, intracellular transportation, assembly or disassembly of protein complexes, and stabilization or degradation of misfolded or aggregated proteins. HSP40, also known as J-domain proteins (JDPs), is the largest family with over fifty members and contains highly conserved J domains responsible for binding to HSP70 and stimulation of the ATPase activity as a co-chaperone. Tumor suppressor p53 (p53), the most frequently mutated gene in human cancers, is one of the proteins that functionally interact with HSP40/JDPs. The majority of p53 mutations are missense mutations, resulting in acquirement of unexpected oncogenic activities, referred to as gain of function (GOF), in addition to loss of the tumor suppressive function. Moreover, stability and levels of wild-type p53 (wtp53) and mutant p53 (mutp53) are crucial for their tumor suppressive and oncogenic activities, respectively. However, the regulatory mechanisms of wtp53 and mutp53 are not fully understood. Accumulating reports demonstrate regulation of wtp53 and mutp53 levels and/or activities by HSP40/JDPs. Here, we summarize updated knowledge related to the link of HSP40/JDPs with p53 and cancer signaling to improve our understanding of the regulation of tumor suppressive wtp53 and oncogenic mutp53 GOF activities.
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Affiliation(s)
- Atsushi Kaida
- Department of Oral Radiation Oncology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo 113-8510, Japan;
- Department of Cancer Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Tomoo Iwakuma
- Department of Cancer Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA
- Department of Pediatrics, Children’s Mercy Research Institute, Kansas City, MO 64108, USA
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Sabbadini R, Pesce E, Parodi A, Mustorgi E, Bruzzone S, Pedemonte N, Casale M, Millo E, Cichero E. Probing Allosteric Hsp70 Inhibitors by Molecular Modelling Studies to Expedite the Development of Novel Combined F508del CFTR Modulators. Pharmaceuticals (Basel) 2021; 14:ph14121296. [PMID: 34959696 PMCID: PMC8709398 DOI: 10.3390/ph14121296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 12/07/2021] [Accepted: 12/09/2021] [Indexed: 11/16/2022] Open
Abstract
Cystic fibrosis (CF) is caused by different mutations related to the cystic fibrosis transmembrane regulator protein (CFTR), with F508del being the most common. Pioneering the development of CFTR modulators, thanks to the development of effective correctors or potentiators, more recent studies deeply encouraged the administration of triple combination therapeutics. However, combinations of molecules interacting with other proteins involved in functionality of the CFTR channel recently arose as a promising approach to address a large rescue of F508del-CFTR. In this context, the design of compounds properly targeting the molecular chaperone Hsp70, such as the allosteric inhibitor MKT-077, proved to be effective for the development of indirect CFTR modulators, endowed with ability to amplify the accumulation of the rescued protein. Herein we performed structure-based studies of a number of allosteric HSP70 inhibitors, considering the recent X-ray crystallographic structure of the human enzyme. This allowed us to point out the main interaction supporting the binding mode of MKT-077, as well as of the related analogues. In particular, cation-π and π-π stacking with the conserve residue Tyr175 deeply stabilized inhibitor binding at the HSP70 cavity. Molecular docking studies had been followed by QSAR analysis and then by virtual screening of aminoaryl thiazoles (I-IIIa) as putative HSP70 inhibitors. Their effectiveness as CFTR modulators has been verified by biological assays, in combination with VX-809, whose positive results confirmed the reliability of the whole applied computational method. Along with this, the "in-silico" prediction of absorption, distribution, metabolism, and excretion (ADME) properties highlighted, once more, that AATs may represent a chemical class to be further investigated for the rational design of novel combination of compounds for CF treatment.
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Affiliation(s)
- Roberto Sabbadini
- Department of Pharmacy, Section of Medicinal Chemistry, School of Medical and Pharmaceutical Sciences, University of Genoa, Viale Benedetto XV, 3, 16132 Genoa, Italy;
| | - Emanuela Pesce
- UOC Genetica Medica, IRCCS Istituto Giannina Gaslini, Via Gerolamo Gaslini, 5, 16147 Genova, Italy; (E.P.); (N.P.)
| | - Alice Parodi
- Department of Experimental Medicine, Section of Biochemistry, University of Genoa, Viale Benedetto XV 1, 16132 Genoa, Italy; (A.P.); (S.B.)
| | - Eleonora Mustorgi
- Department of Pharmacy, Section of Chemistry and Food and Pharmaceutical Technologies, University of Genoa, Viale Cembrano, 4, 16148 Genoa, Italy; (E.M.); (M.C.)
| | - Santina Bruzzone
- Department of Experimental Medicine, Section of Biochemistry, University of Genoa, Viale Benedetto XV 1, 16132 Genoa, Italy; (A.P.); (S.B.)
| | - Nicoletta Pedemonte
- UOC Genetica Medica, IRCCS Istituto Giannina Gaslini, Via Gerolamo Gaslini, 5, 16147 Genova, Italy; (E.P.); (N.P.)
| | - Monica Casale
- Department of Pharmacy, Section of Chemistry and Food and Pharmaceutical Technologies, University of Genoa, Viale Cembrano, 4, 16148 Genoa, Italy; (E.M.); (M.C.)
| | - Enrico Millo
- Department of Experimental Medicine, Section of Biochemistry, University of Genoa, Viale Benedetto XV 1, 16132 Genoa, Italy; (A.P.); (S.B.)
- Correspondence: (E.M.); (E.C.); Tel.: +10-335-3032-3033 (E.M.); +39-010-353-8350 (E.C.)
| | - Elena Cichero
- Department of Pharmacy, Section of Medicinal Chemistry, School of Medical and Pharmaceutical Sciences, University of Genoa, Viale Benedetto XV, 3, 16132 Genoa, Italy;
- Correspondence: (E.M.); (E.C.); Tel.: +10-335-3032-3033 (E.M.); +39-010-353-8350 (E.C.)
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With or without You: Co-Chaperones Mediate Health and Disease by Modifying Chaperone Function and Protein Triage. Cells 2021; 10:cells10113121. [PMID: 34831344 PMCID: PMC8619055 DOI: 10.3390/cells10113121] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 11/05/2021] [Accepted: 11/09/2021] [Indexed: 01/18/2023] Open
Abstract
Heat shock proteins (HSPs) are a family of molecular chaperones that regulate essential protein refolding and triage decisions to maintain protein homeostasis. Numerous co-chaperone proteins directly interact and modify the function of HSPs, and these interactions impact the outcome of protein triage, impacting everything from structural proteins to cell signaling mediators. The chaperone/co-chaperone machinery protects against various stressors to ensure cellular function in the face of stress. However, coding mutations, expression changes, and post-translational modifications of the chaperone/co-chaperone machinery can alter the cellular stress response. Importantly, these dysfunctions appear to contribute to numerous human diseases. Therapeutic targeting of chaperones is an attractive but challenging approach due to the vast functions of HSPs, likely contributing to the off-target effects of these therapies. Current efforts focus on targeting co-chaperones to develop precise treatments for numerous diseases caused by defects in protein quality control. This review focuses on the recent developments regarding selected HSP70/HSP90 co-chaperones, with a concentration on cardioprotection, neuroprotection, cancer, and autoimmune diseases. We also discuss therapeutic approaches that highlight both the utility and challenges of targeting co-chaperones.
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Differential Effects of STCH and Stress-Inducible Hsp70 on the Stability and Maturation of NKCC2. Int J Mol Sci 2021. [PMID: 33672238 DOI: 10.3390/ijms22042207.] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Mutations in the Na-K-2Cl co-transporter NKCC2 lead to type I Bartter syndrome, a life-threatening kidney disease. We previously showed that export from the ER constitutes the limiting step in NKCC2 maturation and cell surface expression. Yet, the molecular mechanisms involved in this process remain obscure. Here, we report the identification of chaperone stress 70 protein (STCH) and the stress-inducible heat shock protein 70 (Hsp70), as two novel binding partners of the ER-resident form of NKCC2. STCH knock-down increased total NKCC2 expression whereas Hsp70 knock-down or its inhibition by YM-01 had the opposite effect. Accordingly, overexpressing of STCH and Hsp70 exerted opposite actions on total protein abundance of NKCC2 and its folding mutants. Cycloheximide chase assay showed that in cells over-expressing STCH, NKCC2 stability and maturation are heavily impaired. In contrast to STCH, Hsp70 co-expression increased NKCC2 maturation. Interestingly, treatment by protein degradation inhibitors revealed that in addition to the proteasome, the ER associated degradation (ERAD) of NKCC2 mediated by STCH, involves also the ER-to-lysosome-associated degradation pathway. In summary, our data are consistent with STCH and Hsp70 having differential and antagonistic effects with regard to NKCC2 biogenesis. These findings may have an impact on our understanding and potential treatment of diseases related to aberrant NKCC2 trafficking and expression.
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15
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Differential Effects of STCH and Stress-Inducible Hsp70 on the Stability and Maturation of NKCC2. Int J Mol Sci 2021; 22:ijms22042207. [PMID: 33672238 PMCID: PMC7926544 DOI: 10.3390/ijms22042207] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Revised: 02/13/2021] [Accepted: 02/20/2021] [Indexed: 12/16/2022] Open
Abstract
Mutations in the Na-K-2Cl co-transporter NKCC2 lead to type I Bartter syndrome, a life-threatening kidney disease. We previously showed that export from the ER constitutes the limiting step in NKCC2 maturation and cell surface expression. Yet, the molecular mechanisms involved in this process remain obscure. Here, we report the identification of chaperone stress 70 protein (STCH) and the stress-inducible heat shock protein 70 (Hsp70), as two novel binding partners of the ER-resident form of NKCC2. STCH knock-down increased total NKCC2 expression whereas Hsp70 knock-down or its inhibition by YM-01 had the opposite effect. Accordingly, overexpressing of STCH and Hsp70 exerted opposite actions on total protein abundance of NKCC2 and its folding mutants. Cycloheximide chase assay showed that in cells over-expressing STCH, NKCC2 stability and maturation are heavily impaired. In contrast to STCH, Hsp70 co-expression increased NKCC2 maturation. Interestingly, treatment by protein degradation inhibitors revealed that in addition to the proteasome, the ER associated degradation (ERAD) of NKCC2 mediated by STCH, involves also the ER-to-lysosome-associated degradation pathway. In summary, our data are consistent with STCH and Hsp70 having differential and antagonistic effects with regard to NKCC2 biogenesis. These findings may have an impact on our understanding and potential treatment of diseases related to aberrant NKCC2 trafficking and expression.
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Nadel CM, Ran X, Gestwicki JE. Luminescence complementation assay for measurement of binding to protein C-termini in live cells. Anal Biochem 2020; 611:113947. [PMID: 32918866 DOI: 10.1016/j.ab.2020.113947] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 08/28/2020] [Accepted: 09/04/2020] [Indexed: 11/28/2022]
Abstract
Protein-protein interactions (PPIs) involving the extreme C-terminus serve important scaffolding and regulatory functions. Here, we leveraged NanoBiT technology to build a luminescent complementation assay for use in studying this subcategory of PPI. As a model system, we fused one component of NanoBiT to the disordered C-terminus of heat shock protein (Hsp70) and the other to its binding partner, the tetratricopeptide repeat (TPR) domain of CHIP/STUB1. We found that HEK293 cells that stably express these chimeras under a doxycycline promoter produced a robust luminescence signal. This signal was sensitive to mutations and it was further tuned by the expression of competitive C-termini. Using this system, we identified a promising, membrane permeable inhibitor of the Hsp70-CHIP interaction. More broadly, we anticipate that NanoBiT is well-suited for studying PPIs that involve C-termini.
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Affiliation(s)
- Cory M Nadel
- Department of Pharmaceutical Chemistry and the Institute for Neurodegenerative Disease, University of California San Francisco, San Francisco, CA, 94158, USA
| | - Xu Ran
- Department of Pharmaceutical Chemistry and the Institute for Neurodegenerative Disease, University of California San Francisco, San Francisco, CA, 94158, USA
| | - Jason E Gestwicki
- Department of Pharmaceutical Chemistry and the Institute for Neurodegenerative Disease, University of California San Francisco, San Francisco, CA, 94158, USA.
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Abildgaard AB, Gersing SK, Larsen-Ledet S, Nielsen SV, Stein A, Lindorff-Larsen K, Hartmann-Petersen R. Co-Chaperones in Targeting and Delivery of Misfolded Proteins to the 26S Proteasome. Biomolecules 2020; 10:E1141. [PMID: 32759676 PMCID: PMC7463752 DOI: 10.3390/biom10081141] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 07/31/2020] [Accepted: 08/02/2020] [Indexed: 12/11/2022] Open
Abstract
Protein homeostasis (proteostasis) is essential for the cell and is maintained by a highly conserved protein quality control (PQC) system, which triages newly synthesized, mislocalized and misfolded proteins. The ubiquitin-proteasome system (UPS), molecular chaperones, and co-chaperones are vital PQC elements that work together to facilitate degradation of misfolded and toxic protein species through the 26S proteasome. However, the underlying mechanisms are complex and remain partly unclear. Here, we provide an overview of the current knowledge on the co-chaperones that directly take part in targeting and delivery of PQC substrates for degradation. While J-domain proteins (JDPs) target substrates for the heat shock protein 70 (HSP70) chaperones, nucleotide-exchange factors (NEFs) deliver HSP70-bound substrates to the proteasome. So far, three NEFs have been established in proteasomal delivery: HSP110 and the ubiquitin-like (UBL) domain proteins BAG-1 and BAG-6, the latter acting as a chaperone itself and carrying its substrates directly to the proteasome. A better understanding of the individual delivery pathways will improve our ability to regulate the triage, and thus regulate the fate of aberrant proteins involved in cell stress and disease, examples of which are given throughout the review.
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Affiliation(s)
- Amanda B. Abildgaard
- Department of Biology, The Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark; (A.B.A.); (S.K.G.); (S.L.-L.); (K.L.-L.)
| | - Sarah K. Gersing
- Department of Biology, The Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark; (A.B.A.); (S.K.G.); (S.L.-L.); (K.L.-L.)
| | - Sven Larsen-Ledet
- Department of Biology, The Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark; (A.B.A.); (S.K.G.); (S.L.-L.); (K.L.-L.)
| | - Sofie V. Nielsen
- Department of Biology, Section for Computational and RNA Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark; (S.V.N.); (A.S.)
| | - Amelie Stein
- Department of Biology, Section for Computational and RNA Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark; (S.V.N.); (A.S.)
| | - Kresten Lindorff-Larsen
- Department of Biology, The Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark; (A.B.A.); (S.K.G.); (S.L.-L.); (K.L.-L.)
| | - Rasmus Hartmann-Petersen
- Department of Biology, The Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark; (A.B.A.); (S.K.G.); (S.L.-L.); (K.L.-L.)
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18
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Zhou Y, Cui J, Hu H, Wen Y, Du Z, Du H. Identification of a novel anti‑heat shock cognate 71 kDa protein antibody in patients with Kawasaki disease. Mol Med Rep 2020; 21:1771-1778. [PMID: 32319608 PMCID: PMC7057768 DOI: 10.3892/mmr.2020.10973] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 12/18/2020] [Indexed: 12/19/2022] Open
Abstract
Kawasaki disease (KD) is an idiopathic form of acute systemic vasculitis, which clinically mimics febrile diseases. Although it has been hypothesized that immune system malfunction is associated with KD, its etiology remains unclear. The aim of the present study was to identify a KD‑associated antibody. Immunoproteomic methods were used to identify KD‑associated antigens that could be recognized in the sera of patients with KD. HeLa cells were used as an antigen source and KD sera were used as probe antibodies to determine the binding of the antibodies using an indirect immunofluorescence assay. Western blotting was performed to identify KD‑associated antigens in HeLa whole cell lysates. Eight out of 12 serum samples obtained from patients with KD demonstrated immunoreactive bands at ~70 kDa, which was later determined to be heat shock cognate 71 kDa protein (HSP7C) by mass spectrometry. The diagnostic value of serum anti‑HSP7C antibodies for KD was assessed using ELISA. Using a cut‑off value of 0.267, anti‑HSP7C antibodies were observed to be present in the sera of 60.00% (30/50) of patients with KD, in 21.05% (8/38) of non‑KD febrile controls, and in 5.26% (2/38) of healthy controls. High serum levels of anti‑HSP7C antibodies were detected in the peripheral circulation of patients with KD. To the best of our knowledge, the present study is the first to observe the high expression levels of anti‑HSP7C antibodies in patients with KD. Therefore, anti‑HSP7C antibodies may be used as a diagnostic marker to detect KD.
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Affiliation(s)
- Yabin Zhou
- School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, P.R. China
| | - Jiawen Cui
- School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, P.R. China
| | - Huimin Hu
- Department of Pediatrics, Beijing Children's Hospital, Capital Medical University, Beijing 100045, P.R. China
| | - Yongqiang Wen
- School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, P.R. China
| | - Zhongdong Du
- Department of Pediatrics, Beijing Children's Hospital, Capital Medical University, Beijing 100045, P.R. China
| | - Hongwu Du
- School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing 100083, P.R. China
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Baaklini I, Gonçalves CDC, Lukacs GL, Young JC. Selective Binding of HSC70 and its Co-Chaperones to Structural Hotspots on CFTR. Sci Rep 2020; 10:4176. [PMID: 32144307 PMCID: PMC7060200 DOI: 10.1038/s41598-020-61107-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Accepted: 02/07/2020] [Indexed: 12/17/2022] Open
Abstract
Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) channel cause cystic fibrosis. Chaperones, including HSC70, DNAJA1 and DNAJA2, play key roles in both the folding and degradation of wild-type and mutant CFTR at multiple cellular locations. DNAJA1 and HSC70 promote the folding of newly synthesized CFTR at the endoplasmic reticulum (ER), but are required for the rapid turnover of misfolded channel at the plasma membrane (PM). DNAJA2 and HSC70 are also involved in the ER-associated degradation (ERAD) of misfolded CFTR, while they assist the refolding of destabilized channel at the PM. These outcomes may depend on the binding of chaperones to specific sites within CFTR, which would be exposed in non-native states. A CFTR peptide library was used to identify binding sites for HSC70, DNAJA1 and DNAJA2, validated by competition and functional assays. Each chaperone had a distinct binding pattern, and sites were distributed between the surfaces of the CFTR cytosolic domains, and domain interfaces known to be important for channel assembly. The accessibility of sites to chaperones will depend on the degree of CFTR folding or unfolding. Different folded states may be recognized by unique combinations of HSC70, DNAJA1 and DNAJA2, leading to divergent biological effects.
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Affiliation(s)
- Imad Baaklini
- McGill University, Department of Biochemistry, Montreal, H3G 1Y6, Canada
| | | | - Gergely L Lukacs
- McGill University, Department of Biochemistry, Montreal, H3G 1Y6, Canada.,McGill University, Department of Physiology, Montreal, H3G 1Y6, Canada
| | - Jason C Young
- McGill University, Department of Biochemistry, Montreal, H3G 1Y6, Canada.
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