1
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Oppenheimer KG, Hager NA, McAtee CK, Filiztekin E, Shang C, Warnick JA, Bruchez MP, Brodsky JL, Prosser DC, Kwiatkowski AV, O'Donnell AF. Optimization of the fluorogen-activating protein tag for quantitative protein trafficking and colocalization studies in S. cerevisiae. Mol Biol Cell 2024; 35:mr5. [PMID: 38809589 DOI: 10.1091/mbc.e24-04-0174] [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] [Indexed: 05/30/2024] Open
Abstract
Spatial and temporal tracking of fluorescent proteins (FPs) in live cells permits visualization of proteome remodeling in response to extracellular cues. Historically, protein dynamics during trafficking have been visualized using constitutively active FPs fused to proteins of interest. While powerful, such FPs label all cellular pools of a protein, potentially masking the dynamics of select subpopulations. To help study protein subpopulations, bioconjugate tags, including the fluorogen activation proteins (FAPs), were developed. FAPs are comprised of two components: a single-chain antibody (SCA) fused to the protein of interest and a malachite-green (MG) derivative, which fluoresces only when bound to the SCA. Importantly, the MG derivatives can be either cell-permeant or -impermeant, thus permitting isolated detection of SCA-tagged proteins at the cell surface and facilitating quantitative endocytic measures. To expand FAP use in yeast, we optimized the SCA for yeast expression, created FAP-tagging plasmids, and generated FAP-tagged organelle markers. To demonstrate FAP efficacy, we coupled the SCA to the yeast G-protein coupled receptor Ste3. We measured Ste3 endocytic dynamics in response to pheromone and characterized cis- and trans-acting regulators of Ste3. Our work significantly expands FAP technology for varied applications in S. cerevisiae.
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Affiliation(s)
| | - Natalie A Hager
- Department of Biological Sciences, University of Pittsburgh, PA 15260
| | - Ceara K McAtee
- Department of Biological Sciences, University of Pittsburgh, PA 15260
| | - Elif Filiztekin
- Department of Biological Sciences, University of Pittsburgh, PA 15260
| | - Chaowei Shang
- Department of Biological Sciences, University of Pittsburgh, PA 15260
| | - Justina A Warnick
- Department of Biological Sciences, University of Pittsburgh, PA 15260
| | - Marcel P Bruchez
- Molecular Biosensor and Imaging Center, Carnegie Mellon University, Pittsburgh, PA 15213
| | - Jeffrey L Brodsky
- Department of Biological Sciences, University of Pittsburgh, PA 15260
| | - Derek C Prosser
- Department of Biology, Virginia Commonwealth University, Richmond, VA 23284
| | - Adam V Kwiatkowski
- Department of Cell Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
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2
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Kok M, Hartnett-Scott K, Happe CL, MacDonald ML, Aizenman E, Brodsky JL. The expression system influences stability, maturation efficiency, and oligomeric properties of the potassium-chloride co-transporter KCC2. Neurochem Int 2024; 174:105695. [PMID: 38373478 PMCID: PMC10923169 DOI: 10.1016/j.neuint.2024.105695] [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: 09/08/2023] [Revised: 02/02/2024] [Accepted: 02/06/2024] [Indexed: 02/21/2024]
Abstract
The neuron-specific K+/Cl- co-transporter 2, KCC2, which is critical for brain development, regulates γ-aminobutyric acid-dependent inhibitory neurotransmission. Consistent with its function, mutations in KCC2 are linked to neurodevelopmental disorders, including epilepsy, schizophrenia, and autism. KCC2 possesses 12 transmembrane spans and forms an intertwined dimer. Based on its complex architecture and function, reduced cell surface expression and/or activity have been reported when select disease-associated mutations are present in the gene encoding the protein, SLC12A5. These data suggest that KCC2 might be inherently unstable, as seen for other complex polytopic ion channels, thus making it susceptible to cellular quality control pathways that degrade misfolded proteins. To test these hypotheses, we examined KCC2 stability and/or maturation in five model systems: yeast, HEK293 cells, primary rat neurons, and rat and human brain synaptosomes. Although studies in yeast revealed that KCC2 is selected for endoplasmic reticulum-associated degradation (ERAD), experiments in HEK293 cells supported a more subtle role for ERAD in maintaining steady-state levels of KCC2. Nevertheless, this system allowed for an analysis of KCC2 glycosylation in the ER and Golgi, which serves as a read-out for transport through the secretory pathway. In turn, KCC2 was remarkably stable in primary rat neurons, suggesting that KCC2 folds efficiently in more native systems. Consistent with these data, the mature glycosylated form of KCC2 was abundant in primary rat neurons as well as in rat and human brain. Together, this work details the first insights into the influence that the cellular and membrane environments have on several fundamental KCC2 properties, acknowledges the advantages and disadvantages of each system, and helps set the stage for future experiments to assess KCC2 in a normal or disease setting.
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Affiliation(s)
- Morgan Kok
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Karen Hartnett-Scott
- Department of Neurobiology and the Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Cassandra L Happe
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Matthew L MacDonald
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Elias Aizenman
- Department of Neurobiology and the Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Jeffrey L Brodsky
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA.
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3
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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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4
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Larsen MB, Choi JJ, Wang X, Myerburg MM, Frizzell RA, Bertrand CA. Separating the contributions of SLC26A9 and CFTR to anion secretion in primary human bronchial epithelia. Am J Physiol Lung Cell Mol Physiol 2021; 321:L1147-L1160. [PMID: 34668421 PMCID: PMC8715023 DOI: 10.1152/ajplung.00563.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 10/01/2021] [Accepted: 10/15/2021] [Indexed: 11/22/2022] Open
Abstract
Aberrant anion secretion across the bronchial epithelium is associated with airway disease, most notably in cystic fibrosis. Although the cystic fibrosis transmembrane conductance regulator (CFTR) is recognized as the primary source of airway anion secretion, alternative anion transport mechanisms play a contributing role. An alternative anion transporter of growing interest is SLC26A9, a constitutively active chloride channel that has been shown to interact with CFTR and may also contribute to bicarbonate secretion. Interest in SLC26A9 has been fueled by genome-wide association studies that suggest it is a significant modifier of CF disease severity. Despite this growing evidence that SLC26A9 plays an important role in the airway, its presence and function in bronchial epithelia remain poorly understood, in part, because its activity is difficult to separate from the activity of CFTR. Here, we present results using primary human bronchial epithelia (HBE) from multiple patient sources to confirm that SLC26A9 mRNA is present in HBE and that its constitutive channel activity is unaffected by knockdown of CFTR. Furthermore, SLC26A9 and CFTR show differential responses to common inhibitors of anion secretion. Finally, we assess the impact of bicarbonate on the activity of SLC26A9 and CFTR. These results confirm that SLC26A9 is the primary source of constitutive anion secretion across HBE, and should inform future studies focused on activation of SLC26A9 as an alternative anion channel in CF. These results should provide a strong foundation to investigate how single-nucleotide polymorphisms in SLC26A9 modulate airway disease.
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Affiliation(s)
- Mads B Larsen
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Jeannie J Choi
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Xiaohui Wang
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Michael M Myerburg
- Department of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Raymond A Frizzell
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Carol A Bertrand
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
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5
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Peters KW, Gong X, Frizzell RA. Cystic Fibrosis Transmembrane Conductance Regulator Folding Mutations Reveal Differences in Corrector Efficacy Linked to Increases in Immature Cystic Fibrosis Transmembrane Conductance Regulator Expression. Front Physiol 2021; 12:695767. [PMID: 34764878 PMCID: PMC8576290 DOI: 10.3389/fphys.2021.695767] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 07/05/2021] [Indexed: 11/17/2022] Open
Abstract
Background: Most cystic fibrosis is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene that lead to protein misfolding and degradation by the ubiquitin–proteasome system. Previous studies demonstrated that PIAS4 facilitates the modification of wild-type (WT) and F508del CFTR by small ubiquitin-like modifier (SUMO)-1, enhancing CFTR biogenesis by slowing immature CFTR degradation and producing increased immature CFTR band B. Methods: We evaluated two correction strategies using misfolding mutants, including the common variant, F508del. We examined the effects on mutant expression of co-expression with PIAS4 (E3 SUMO ligase), and/or the corrector, C18. To study the impact of these correction conditions, we transfected CFBE410- cells, a bronchial epithelial cell line, with a CFTR mutant plus: (1) empty vector, (2) empty vector plus overnight 5 μM C18, (3) PIAS4, and (4) PIAS4 plus C18. We assessed expression at steady state by immunoblot of CFTR band B, and if present, band C, and the corresponding C:B band ratio. The large PIAS4-induced increase in band B expression allowed us to ask whether C18 could act on the now abundant immature protein to enhance correction above the control level, as reported by the C:B ratio. Results: The data fell into three mutant CFTR categories as follows: (1) intransigent: no observable band C under any condition (i.e., C:B = 0); (2) throughput responsive: a C:B ratio less than control, but suggesting that the increased band C resulted from PIAS4-induced increases in band B production; and (3) folding responsive: a C:B ratio greater than control, reflecting C18-induced folding greater than that expected from increased throughput due to the PIAS4-induced band B level. Conclusion: These results suggest that the immature forms of CFTR folding intermediates occupy different loci within the energetic/kinetic folding landscape of CFTR. The evaluation of their properties could assist in the development of correctors that can target the more difficult-to-fold mutant conformations that occupy different sites within the CFTR folding pathway.
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Affiliation(s)
- Kathryn W Peters
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Xiaoyan Gong
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Raymond A Frizzell
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
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6
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Goeckeler-Fried JL, Aldrin Denny R, Joshi D, Hill C, Larsen MB, Chiang AN, Frizzell RA, Wipf P, Sorscher EJ, Brodsky JL. Improved correction of F508del-CFTR biogenesis with a folding facilitator and an inhibitor of protein ubiquitination. Bioorg Med Chem Lett 2021; 48:128243. [PMID: 34246753 DOI: 10.1016/j.bmcl.2021.128243] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 06/16/2021] [Accepted: 06/30/2021] [Indexed: 11/25/2022]
Abstract
A growing number of diseases are linked to the misfolding of integral membrane proteins, and many of these proteins are targeted for ubiquitin-proteasome-dependent degradation. One such substrate is a mutant form of the Cystic Fibrosis Transmembrane Conductance Regulator (F508del-CFTR). Protein folding "correctors" that repair the F508del-CFTR folding defect have entered the clinic, but they are unlikely to protect the entire protein from degradation. To increase the pool of F508del-CFTR protein that is available for correction by existing treatments, we determined a structure-activity relationship to improve the efficacy and reduce the toxicity of an inhibitor of the E1 ubiquitin activating enzyme that facilitates F508del-CFTR maturation. A resulting lead compound lacked measurable toxicity and improved the ability of an FDA-approved corrector to augment F508del-CFTR folding, transport the protein to the plasma membrane, and maintain its activity. These data support a proof-of-concept that modest inhibition of substrate ubiquitination improves the activity of small molecule correctors to treat CF and potentially other protein conformational disorders.
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Affiliation(s)
| | - Rajiah Aldrin Denny
- Department of Inflammation & Immunology, Pfizer Inc., Cambridge, MA 02139, USA
| | - Disha Joshi
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322 USA
| | - Clare Hill
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Mads B Larsen
- Department of Pediatrics, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA 15224, USA
| | - Annette N Chiang
- Department of Biological Science, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Raymond A Frizzell
- Department of Pediatrics, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA 15224, USA
| | - Peter Wipf
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Eric J Sorscher
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322 USA
| | - Jeffrey L Brodsky
- Department of Biological Science, University of Pittsburgh, Pittsburgh, PA 15260, USA.
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7
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Perkins LA, Bruchez MP. Fluorogen activating protein toolset for protein trafficking measurements. Traffic 2020; 21:333-348. [PMID: 32080949 PMCID: PMC7462100 DOI: 10.1111/tra.12722] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 02/17/2020] [Accepted: 02/18/2020] [Indexed: 12/11/2022]
Abstract
Throughout the past decade the use of fluorogen activating proteins (FAPs) has expanded with several unique reporter dyes that support a variety of methods to specifically quantify protein trafficking events. The platform's capabilities have been demonstrated in several systems and shared for widespread use. This review will highlight the current FAP labeling techniques for protein traffic measurements and focus on the use of the different designed fluorogenic dyes for selective and specific labeling applications.
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Affiliation(s)
- Lydia A. Perkins
- School of MedicineUniversity of PittsburghPittsburghPennsylvaniaUSA
| | - Marcel P. Bruchez
- The Department of Biological SciencesCarnegie MellonPittsburghPennsylvaniaUSA
- Department of ChemistryCarnegie MellonPittsburghPennsylvaniaUSA
- Molecular and Biosensor Imaging CenterCarnegie MellonPittsburghPennsylvaniaUSA
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8
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Transforming Growth Factor-β1 Selectively Recruits microRNAs to the RNA-Induced Silencing Complex and Degrades CFTR mRNA under Permissive Conditions in Human Bronchial Epithelial Cells. Int J Mol Sci 2019; 20:ijms20194933. [PMID: 31590401 PMCID: PMC6801718 DOI: 10.3390/ijms20194933] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 09/27/2019] [Accepted: 10/05/2019] [Indexed: 12/23/2022] Open
Abstract
Mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene lead to cystic fibrosis (CF). The most common mutation F508del inhibits folding and processing of CFTR protein. FDA-approved correctors rescue the biosynthetic processing of F508del-CFTR protein, while potentiators improve the rescued CFTR channel function. Transforming growth factor (TGF-β1), overexpressed in many CF patients, blocks corrector/potentiator rescue by inhibiting CFTR mRNA in vitro. Increased TGF-β1 signaling and acquired CFTR dysfunction are present in other lung diseases. To study the mechanism of TGF-β1 repression of CFTR, we used molecular, biochemical, and functional approaches in primary human bronchial epithelial cells from over 50 donors. TGF-β1 destabilized CFTR mRNA in cells from lungs with chronic disease, including CF, and impaired F508del-CFTR rescue by new-generation correctors. TGF-β1 increased the active pool of selected micro(mi)RNAs validated as CFTR inhibitors, recruiting them to the RNA-induced silencing complex (RISC). Expression of F508del-CFTR globally modulated TGF-β1-induced changes in the miRNA landscape, creating a permissive environment required for degradation of F508del-CFTR mRNA. In conclusion, TGF-β1 may impede the full benefit of corrector/potentiator therapy in CF patients. Studying miRNA recruitment to RISC under disease-specific conditions may help to better characterize the miRNAs utilized by TGF-β1 to destabilize CFTR mRNA.
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9
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Britton ZT, London TB, Carrell J, Dosanjh B, Wilkinson T, Bowen MA, Wu H, Dall’Acqua WF, Marelli M, Mazor Y. Tag-on-Demand: exploiting amber codon suppression technology for the enrichment of high-expressing membrane protein cell lines. Protein Eng Des Sel 2019; 31:389-398. [DOI: 10.1093/protein/gzy032] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 11/16/2018] [Accepted: 12/18/2018] [Indexed: 12/20/2022] Open
Affiliation(s)
- Zachary T Britton
- Antibody Discovery and Protein Engineering, MedImmune, Gaithersburg, MD, USA
| | - Timothy B London
- Antibody Discovery and Protein Engineering, MedImmune, Cambridge, UK
- Current affiliation: TC BioPharm Limited, Glasgow, UK
| | - Jeffrey Carrell
- Respiratory, Inflammation and Autoimmune, MedImmune, Gaithersburg, MD, USA
| | - Bhupinder Dosanjh
- Antibody Discovery and Protein Engineering, MedImmune, Cambridge, UK
| | - Trevor Wilkinson
- Antibody Discovery and Protein Engineering, MedImmune, Cambridge, UK
| | - Michael A Bowen
- Antibody Discovery and Protein Engineering, MedImmune, Gaithersburg, MD, USA
| | - Herren Wu
- Antibody Discovery and Protein Engineering, MedImmune, Gaithersburg, MD, USA
| | | | - Marcello Marelli
- Antibody Discovery and Protein Engineering, MedImmune, Gaithersburg, MD, USA
| | - Yariv Mazor
- Antibody Discovery and Protein Engineering, MedImmune, Gaithersburg, MD, USA
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10
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Gong X, Liao Y, Ahner A, Larsen MB, Wang X, Bertrand CA, Frizzell RA. Different SUMO paralogues determine the fate of wild-type and mutant CFTRs: biogenesis versus degradation. Mol Biol Cell 2018; 30:4-16. [PMID: 30403549 PMCID: PMC6337916 DOI: 10.1091/mbc.e18-04-0252] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
A pathway for cystic fibrosis transmembrane conductance regulator (CFTR) degradation is initiated by Hsp27, which cooperates with Ubc9 and binds to the common F508del mutant to modify it with SUMO-2/3. These SUMO paralogues form polychains, which are recognized by the ubiquitin ligase, RNF4, for proteosomal degradation. Here, protein array analysis identified the SUMO E3, protein inhibitor of activated STAT 4 (PIAS4), which increased wild-type (WT) and F508del CFTR biogenesis in CFBE airway cells. PIAS4 increased immature CFTR threefold and doubled expression of mature CFTR, detected by biochemical and functional assays. In cycloheximide chase assays, PIAS4 slowed immature F508del degradation threefold and stabilized mature WT CFTR at the plasma membrance. PIAS4 knockdown reduced WT and F508del CFTR expression by 40–50%, suggesting a physiological role in CFTR biogenesis. PIAS4 modified F508del CFTR with SUMO-1 in vivo and reduced its conjugation to SUMO-2/3. These SUMO paralogue-specific effects of PIAS4 were reproduced in vitro using purified F508del nucleotide-binding domain 1 and SUMOylation reaction components. PIAS4 reduced endogenous ubiquitin conjugation to F508del CFTR by ∼50% and blocked the impact of RNF4 on mutant CFTR disposal. These findings indicate that different SUMO paralogues determine the fates of WT and mutant CFTRs, and they suggest that a paralogue switch during biogenesis can direct these proteins to different outcomes: biogenesis versus degradation.
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Affiliation(s)
- Xiaoyan Gong
- Departments of Pediatrics and Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224
| | - Yong Liao
- Departments of Pediatrics and Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224
| | - Annette Ahner
- Departments of Pediatrics and Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224
| | - Mads Breum Larsen
- Departments of Pediatrics and Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224
| | - Xiaohui Wang
- Departments of Pediatrics and Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224
| | - Carol A Bertrand
- Departments of Pediatrics and Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224
| | - Raymond A Frizzell
- Departments of Pediatrics and Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224
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11
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Jaykumar AB, Caceres PS, Ortiz PA. Single-molecule labeling for studying trafficking of renal transporters. Am J Physiol Renal Physiol 2018; 315:F1243-F1249. [PMID: 30043625 DOI: 10.1152/ajprenal.00082.2017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The ability to detect and track single molecules presents the advantage of visualizing the complex behavior of transmembrane proteins with a time and space resolution that would otherwise be lost with traditional labeling and biochemical techniques. Development of new imaging probes has provided a robust method to study their trafficking and surface dynamics. This mini-review focuses on the current technology available for single-molecule labeling of transmembrane proteins, their advantages, and limitations. We also discuss the application of these techniques to the study of renal transporter trafficking in light of recent research.
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Affiliation(s)
- Ankita Bachhawat Jaykumar
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital , Detroit, Michigan.,Department of Physiology, Wayne State University School of Medicine , Detroit, Michigan
| | - Paulo S Caceres
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital , Detroit, Michigan
| | - Pablo A Ortiz
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital , Detroit, Michigan.,Department of Physiology, Wayne State University School of Medicine , Detroit, Michigan
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12
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Emmerstorfer-Augustin A, Augustin CM, Shams S, Thorner J. Tracking yeast pheromone receptor Ste2 endocytosis using fluorogen-activating protein tagging. Mol Biol Cell 2018; 29:2720-2736. [PMID: 30207829 PMCID: PMC6249837 DOI: 10.1091/mbc.e18-07-0424] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
To observe internalization of the yeast pheromone receptor Ste2 by fluorescence microscopy in live cells in real time, we visualized only those molecules present at the cell surface at the time of agonist engagement (rather than the total cellular pool) by tagging this receptor at its N-terminus with an exocellular fluorogen-activating protein (FAP). A FAP is a single-chain antibody engineered to bind tightly a nonfluorescent, cell-impermeable dye (fluorogen), thereby generating a fluorescent complex. The utility of FAP tagging to study trafficking of integral membrane proteins in yeast, which possesses a cell wall, had not been examined previously. A diverse set of signal peptides and propeptide sequences were explored to maximize expression. Maintenance of the optimal FAP-Ste2 chimera intact required deletion of two, paralogous, glycosylphosphatidylinositol (GPI)-anchored extracellular aspartyl proteases (Yps1 and Mkc7). FAP-Ste2 exhibited a much brighter and distinct plasma membrane signal than Ste2-GFP or Ste2-mCherry yet behaved quite similarly. Using FAP-Ste2, new information was obtained about the mechanism of its internalization, including novel insights about the roles of the cargo-selective endocytic adaptors Ldb19/Art1, Rod1/Art4, and Rog3/Art7.
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Affiliation(s)
- Anita Emmerstorfer-Augustin
- Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3202
| | - Christoph M Augustin
- Department of Mechanical Engineering, University of California, Berkeley, Berkeley, CA 94720-3202
| | - Shadi Shams
- Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3202
| | - Jeremy Thorner
- Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3202
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13
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Ferreira VFC, Oliveira BL, Santos JD, Correia JDG, Farinha CM, Mendes F. Targeting of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Protein with a Technetium-99m Imaging Probe. ChemMedChem 2018; 13:1469-1478. [PMID: 29864241 DOI: 10.1002/cmdc.201800187] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 05/18/2018] [Indexed: 12/28/2022]
Abstract
Cystic fibrosis (CF) is caused by mutations in the gene that encodes the CF transmembrane conductance regulator (CFTR) protein. The most common mutation, F508del, leads to almost total absence of CFTR at the plasma membrane, a defect potentially corrected via drug-based therapies. Herein, we report the first proof-of-principle study of a noninvasive imaging probe able to detect CFTR at the plasma membrane. We radiolabeled the CFTR inhibitor, CFTRinh -172a, with technetium-99m via a pyrazolyl-diamine chelating unit, yielding a novel 99m Tc(CO)3 complex. A non-radioactive surrogate showed that the structural modifications introduced in the inhibitor did not affect its activity. The radioactive complex was able to detect plasma membrane CFTR, shown by its significantly higher uptake in wild-type versus mutated cells. Furthermore, assessment of F508del CFTR pharmacological correction in human cells using the radioactive complex revealed differences in corrector versus control uptake, recapitulating the biochemical correction observed for the protein.
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Affiliation(s)
- Vera F C Ferreira
- C2TN-Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, 2695-066, Bobadela LRS, Portugal
| | - Bruno L Oliveira
- C2TN-Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, 2695-066, Bobadela LRS, Portugal
- Current address: Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, UK
| | - João D Santos
- BioISI-Biosystems and Integrative Sciences Institute, Faculty of Sciences, Universidade de Lisboa, Campo Grande C8, 1749-016, Lisboa, Portugal
| | - João D G Correia
- C2TN-Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, 2695-066, Bobadela LRS, Portugal
| | - Carlos M Farinha
- BioISI-Biosystems and Integrative Sciences Institute, Faculty of Sciences, Universidade de Lisboa, Campo Grande C8, 1749-016, Lisboa, Portugal
| | - Filipa Mendes
- C2TN-Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10, 2695-066, Bobadela LRS, Portugal
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14
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Hutt DM, Mishra SK, Roth DM, Larsen MB, Angles F, Frizzell RA, Balch WE. Silencing of the Hsp70-specific nucleotide-exchange factor BAG3 corrects the F508del-CFTR variant by restoring autophagy. J Biol Chem 2018; 293:13682-13695. [PMID: 29986884 DOI: 10.1074/jbc.ra118.002607] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 07/05/2018] [Indexed: 01/11/2023] Open
Abstract
The protein chaperones heat shock protein 70 (Hsp70) and Hsp90 are required for de novo folding of proteins and protect against misfolding-related cellular stresses by directing misfolded or slowly folding proteins to the ubiquitin/proteasome system (UPS) or autophagy/lysosomal degradation pathways. Here, we examined the role of the Bcl2-associated athanogene (BAG) family of Hsp70-specific nucleotide-exchange factors in the biogenesis and functional correction of genetic variants of the cystic fibrosis transmembrane conductance regulator (CFTR) whose mutations cause cystic fibrosis (CF). We show that siRNA-mediated silencing of BAG1 and -3, two BAG members linked to the clearance of misfolded proteins via the UPS and autophagy pathways, respectively, leads to functional correction of F508del-CFTR and other disease-associated CFTR variants. BAG3 silencing was the most effective, leading to improved F508del-CFTR stability, trafficking, and restoration of cell-surface function, both alone and in combination with the FDA-approved CFTR corrector, VX-809. We also found that the BAG3 silencing-mediated correction of F508del-CFTR restores the autophagy pathway, which is defective in F508del-CFTR-expressing cells, likely because of the maladaptive stress response in CF pathophysiology. These results highlight the potential therapeutic benefits of targeting the cellular chaperone system to improve the functional folding of CFTR variants contributing to CF and possibly other protein-misfolding-associated diseases.
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Affiliation(s)
- Darren M Hutt
- From the Department of Molecular Medicine, Skaggs Institute for Chemical Biology, Scripps Research, La Jolla, California 92037 and
| | - Sanjay Kumar Mishra
- the Departments of Pediatrics and Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15224
| | - Daniela Martino Roth
- From the Department of Molecular Medicine, Skaggs Institute for Chemical Biology, Scripps Research, La Jolla, California 92037 and
| | - Mads Breum Larsen
- the Departments of Pediatrics and Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15224
| | - Frédéric Angles
- From the Department of Molecular Medicine, Skaggs Institute for Chemical Biology, Scripps Research, La Jolla, California 92037 and
| | - Raymond A Frizzell
- the Departments of Pediatrics and Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15224
| | - William E Balch
- From the Department of Molecular Medicine, Skaggs Institute for Chemical Biology, Scripps Research, La Jolla, California 92037 and
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15
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Xu S, Hu HY. Fluorogen-activating proteins: beyond classical fluorescent proteins. Acta Pharm Sin B 2018; 8:339-348. [PMID: 29881673 PMCID: PMC5989828 DOI: 10.1016/j.apsb.2018.02.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Revised: 02/11/2018] [Accepted: 02/18/2018] [Indexed: 01/09/2023] Open
Abstract
Fluorescence imaging is a powerful technique for the real-time noninvasive monitoring of protein dynamics. Recently, fluorogen activating proteins (FAPs)/fluorogen probes for protein imaging were developed. Unlike the traditional fluorescent proteins (FPs), FAPs do not fluoresce unless bound to their specific small-molecule fluorogens. When using FAPs/fluorogen probes, a washing step is not required for the removal of free probes from the cells, thus allowing rapid and specific detection of proteins in living cells with high signal-to-noise ratio. Furthermore, with different fluorogens, living cell multi-color proteins labeling system was developed. In this review, we describe about the discovery of FAPs, the design strategy of FAP fluorogens, the application of the FAP technology and the advances of FAP technology in protein labeling systems.
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Affiliation(s)
- Shengnan Xu
- State Key Laboratory of Bioactive Substances and Function of Natural Medicine, Institute of Materia Medica, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing 100050, China
| | - Hai-Yu Hu
- State Key Laboratory of Bioactive Substances and Function of Natural Medicine, Institute of Materia Medica, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing 100050, China
- Beijing Key Laboratory of Active Substances Discovery and Drugability Evaluation, Institute of Materia Medica, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing 100050, China
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16
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Perkins LA, Fisher GW, Naganbabu M, Schmidt BF, Mun F, Bruchez MP. High-Content Surface and Total Expression siRNA Kinase Library Screen with VX-809 Treatment Reveals Kinase Targets that Enhance F508del-CFTR Rescue. Mol Pharm 2018; 15:759-767. [PMID: 29384380 PMCID: PMC5844356 DOI: 10.1021/acs.molpharmaceut.7b00928] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
![]()
The most promising
F508del-CFTR corrector, VX-809, has been unsuccessful
as an effective, stand-alone treatment for CF patients, but the rescue
effect in combination with other drugs may confer an acceptable level
of therapeutic benefit. Targeting cellular factors that modify trafficking
may act to enhance the cell surface density of F508-CFTR with VX-809
correction. Our goal is to identify druggable kinases that enhance
F508del-CFTR rescue and stabilization at the cell surface beyond that
achievable with the VX-809 corrector alone. To achieve this goal,
we implemented a new high-throughput screening paradigm that quickly
and quantitatively measures surface density and total protein in the
same cells. This allowed for rapid screening for increased surface
targeting and proteostatic regulation. The assay utilizes fluorogen-activating-protein
(FAP) technology with cell excluded and cell permeant fluorogenic
dyes in a quick, wash-free fluorescent plate reader format on live
cells to first measure F508del-CFTR expressed on the surface and then
the total amount of F508del-CFTR protein present. To screen for kinase
targets, we used Dharmacon’s ON-TARGETplus SMARTpool siRNA Kinase library (715 target kinases) with and without
10 μM VX-809 treatment in triplicate at 37 °C. We identified
several targets that had a significant interaction with VX-809 treatment
in enhancing surface density with siRNA knockdown. Select small-molecule
inhibitors of the kinase targets demonstrated augmented surface expression
with VX-809 treatment.
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Affiliation(s)
| | | | - Matharishwan Naganbabu
- Department of Chemistry , University of California , Berkeley , California 94720 , United States
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17
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Perkins LA, Yan Q, Schmidt BF, Kolodieznyi D, Saurabh S, Larsen MB, Watkins SC, Kremer L, Bruchez MP. Genetically Targeted Ratiometric and Activated pH Indicator Complexes (TRApHIC) for Receptor Trafficking. Biochemistry 2018; 57:861-871. [PMID: 29283245 DOI: 10.1021/acs.biochem.7b01135] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Fluorescent protein-based pH sensors are useful tools for measuring protein trafficking through pH changes associated with endo- and exocytosis. However, commonly used pH-sensing probes are ubiquitously expressed with their protein of interest throughout the cell, hindering our ability to focus on specific trafficking pools of proteins. We developed a family of excitation ratiometric, activatable pH responsive tandem dyes, consisting of a pH sensitive Cy3 donor linked to a fluorogenic malachite green acceptor. These cell-excluded dyes are targeted and activated upon binding to a genetically expressed fluorogen-activating protein and are suitable for selective labeling of surface proteins for analysis of endocytosis and recycling in live cells using both confocal and superresolution microscopy. Quantitative profiling of the endocytosis and recycling of tagged β2-adrenergic receptor (B2AR) at a single-vesicle level revealed differences among B2AR agonists, consistent with more detailed pharmacological profiling.
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Affiliation(s)
| | - Qi Yan
- Sharp Edge Laboratories , Pittsburgh, Pennsylvania 15203, United States
| | | | | | - Saumya Saurabh
- Department of Developmental Biology, Stanford University , Stanford, California 94305, United States
| | - Mads Breum Larsen
- Center for Biologic Imaging, Department of Cell Biology and Physiology, School of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania 15213, United States
| | - Simon C Watkins
- Center for Biologic Imaging, Department of Cell Biology and Physiology, School of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania 15213, United States
| | - Laura Kremer
- Institute of Human Genetics, Helmholtz Zentrum München , Munich, Germany
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18
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Li C, Tebo AG, Gautier A. Fluorogenic Labeling Strategies for Biological Imaging. Int J Mol Sci 2017; 18:ijms18071473. [PMID: 28698494 PMCID: PMC5535964 DOI: 10.3390/ijms18071473] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 07/03/2017] [Accepted: 07/06/2017] [Indexed: 12/27/2022] Open
Abstract
The spatiotemporal fluorescence imaging of biological processes requires effective tools to label intracellular biomolecules in living systems. This review presents a brief overview of recent labeling strategies that permits one to make protein and RNA strongly fluorescent using synthetic fluorogenic probes. Genetically encoded tags selectively binding the exogenously applied molecules ensure high labeling selectivity, while high imaging contrast is achieved using fluorogenic chromophores that are fluorescent only when bound to their cognate tag, and are otherwise dark. Beyond avoiding the need for removal of unbound synthetic dyes, these approaches allow the development of sophisticated imaging assays, and open exciting prospects for advanced imaging, particularly for multiplexed imaging and super-resolution microscopy.
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Affiliation(s)
- Chenge Li
- École Normale Supérieure, PSL Research University, UPMC Univ Paris 06, CNRS, Département de Chimie, PASTEUR, 24 rue Lhomond, 75005 Paris, France.
- Sorbonne Universités, UPMC Univ Paris 06, ENS, CNRS, PASTEUR, 75005 Paris, France.
| | - Alison G Tebo
- École Normale Supérieure, PSL Research University, UPMC Univ Paris 06, CNRS, Département de Chimie, PASTEUR, 24 rue Lhomond, 75005 Paris, France.
- Sorbonne Universités, UPMC Univ Paris 06, ENS, CNRS, PASTEUR, 75005 Paris, France.
| | - Arnaud Gautier
- École Normale Supérieure, PSL Research University, UPMC Univ Paris 06, CNRS, Département de Chimie, PASTEUR, 24 rue Lhomond, 75005 Paris, France.
- Sorbonne Universités, UPMC Univ Paris 06, ENS, CNRS, PASTEUR, 75005 Paris, France.
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19
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Ramachandran S, Osterhaus SR, Parekh KR, Jacobi AM, Behlke MA, McCray PB. SYVN1, NEDD8, and FBXO2 Proteins Regulate ΔF508 Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Ubiquitin-mediated Proteasomal Degradation. J Biol Chem 2016; 291:25489-25504. [PMID: 27756846 DOI: 10.1074/jbc.m116.754283] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 10/07/2016] [Indexed: 11/06/2022] Open
Abstract
We previously reported that delivery of a microRNA-138 mimic or siRNA against SIN3A to cultured cystic fibrosis (ΔF508/ΔF508) airway epithelia partially restored ΔF508-cystic fibrosis transmembrane conductance regulator (CFTR)-mediated cAMP-stimulated Cl- conductance. We hypothesized that dissecting this microRNA-138/SIN3A-regulated gene network would identify individual proteins contributing to the rescue of ΔF508-CFTR function. Among the genes in the network, we rigorously validated candidates using functional CFTR maturation and electrolyte transport assays in polarized airway epithelia. We found that depletion of the ubiquitin ligase SYVN1, the ubiquitin/proteasome system regulator NEDD8, or the F-box protein FBXO2 partially restored ΔF508-CFTR-mediated Cl- transport in primary cultures of human cystic fibrosis airway epithelia. Moreover, knockdown of SYVN1, NEDD8, or FBXO2 in combination with corrector compound 18 further potentiated rescue of ΔF508-CFTR-mediated Cl- conductance. This study provides new knowledge of the CFTR biosynthetic pathway. It suggests that SYVN1 and FBXO2 represent two distinct multiprotein complexes that may degrade ΔF508-CFTR in airway epithelia and identifies a new role for NEDD8 in regulating ΔF508-CFTR ubiquitination.
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Affiliation(s)
- Shyam Ramachandran
- From the Department of Pediatrics, Pappajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242 and
| | - Samantha R Osterhaus
- From the Department of Pediatrics, Pappajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242 and
| | - Kalpaj R Parekh
- From the Department of Pediatrics, Pappajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242 and
| | | | | | - Paul B McCray
- From the Department of Pediatrics, Pappajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242 and
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20
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Wu Y, Stauffer SR, Stanfield RL, Tapia PH, Ursu O, Fisher GW, Szent-Gyorgyi C, Evangelisti A, Waller A, Strouse JJ, Carter MB, Bologa C, Gouveia K, Poslusney M, Waggoner AS, Lindsley CW, Jarvik JW, Sklar LA. Discovery of Small-Molecule Nonfluorescent Inhibitors of Fluorogen-Fluorogen Activating Protein Binding Pair. ACTA ACUST UNITED AC 2015; 21:74-87. [PMID: 26442911 DOI: 10.1177/1087057115609145] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 09/09/2015] [Indexed: 11/17/2022]
Abstract
A new class of biosensors, fluorogen activating proteins (FAPs), has been successfully used to track receptor trafficking in live cells. Unlike the traditional fluorescent proteins (FPs), FAPs do not fluoresce unless bound to their specific small-molecule fluorogens, and thus FAP-based assays are highly sensitive. Application of the FAP-based assay for protein trafficking in high-throughput flow cytometry resulted in the discovery of a new class of compounds that interferes with the binding between fluorogens and FAP, thus blocking the fluorescence signal. These compounds are high-affinity, nonfluorescent analogs of fluorogens with little or no toxicity to the tested cells and no apparent interference with the normal function of FAP-tagged receptors. The most potent compound among these, N,4-dimethyl-N-(2-oxo-2-(4-(pyridin-2-yl)piperazin-1-yl)ethyl)benzenesulfonamide (ML342), has been investigated in detail. X-ray crystallographic analysis revealed that ML342 competes with the fluorogen, sulfonated thiazole orange coupled to diethylene glycol diamine (TO1-2p), for the same binding site on a FAP, AM2.2. Kinetic analysis shows that the FAP-fluorogen interaction is more complex than a homogeneous one-site binding process, with multiple conformational states of the fluorogen and/or the FAP, and possible dimerization of the FAP moiety involved in the process.
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Affiliation(s)
- Yang Wu
- Department of Pathology, University of New Mexico, Albuquerque, NM, USA Center for Molecular Discovery, University of New Mexico, Albuquerque, NM, USA
| | - Shaun R Stauffer
- Vanderbilt Specialized Chemistry Center, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Robyn L Stanfield
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, USA
| | - Phillip H Tapia
- Center for Molecular Discovery, University of New Mexico, Albuquerque, NM, USA
| | - Oleg Ursu
- Center for Molecular Discovery, University of New Mexico, Albuquerque, NM, USA
| | - Gregory W Fisher
- Molecular Biosensor and Imaging Center, Carnegie Mellon University, Pittsburgh, PA, USA
| | | | - Annette Evangelisti
- Center for Molecular Discovery, University of New Mexico, Albuquerque, NM, USA
| | - Anna Waller
- Center for Molecular Discovery, University of New Mexico, Albuquerque, NM, USA
| | - J Jacob Strouse
- Center for Molecular Discovery, University of New Mexico, Albuquerque, NM, USA
| | - Mark B Carter
- Center for Molecular Discovery, University of New Mexico, Albuquerque, NM, USA
| | - Cristian Bologa
- Center for Molecular Discovery, University of New Mexico, Albuquerque, NM, USA
| | - Kristine Gouveia
- Center for Molecular Discovery, University of New Mexico, Albuquerque, NM, USA
| | - Mike Poslusney
- Vanderbilt Specialized Chemistry Center, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Alan S Waggoner
- Molecular Biosensor and Imaging Center, Carnegie Mellon University, Pittsburgh, PA, USA Department of Biological Science, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Craig W Lindsley
- Vanderbilt Specialized Chemistry Center, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jonathan W Jarvik
- Molecular Biosensor and Imaging Center, Carnegie Mellon University, Pittsburgh, PA, USA Department of Biological Science, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Larry A Sklar
- Department of Pathology, University of New Mexico, Albuquerque, NM, USA Center for Molecular Discovery, University of New Mexico, Albuquerque, NM, USA
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21
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Zhang M, Chakraborty SK, Sampath P, Rojas JJ, Hou W, Saurabh S, Thorne SH, Bruchez MP, Waggoner AS. Fluoromodule-based reporter/probes designed for in vivo fluorescence imaging. J Clin Invest 2015; 125:3915-27. [PMID: 26348895 DOI: 10.1172/jci81086] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 07/30/2015] [Indexed: 12/26/2022] Open
Abstract
Optical imaging of whole, living animals has proven to be a powerful tool in multiple areas of preclinical research and has allowed noninvasive monitoring of immune responses, tumor and pathogen growth, and treatment responses in longitudinal studies. However, fluorescence-based studies in animals are challenging because tissue absorbs and autofluoresces strongly in the visible light spectrum. These optical properties drive development and use of fluorescent labels that absorb and emit at longer wavelengths. Here, we present a far-red absorbing fluoromodule-based reporter/probe system and show that this system can be used for imaging in living mice. The probe we developed is a fluorogenic dye called SC1 that is dark in solution but highly fluorescent when bound to its cognate reporter, Mars1. The reporter/probe complex, or fluoromodule, produced peak emission near 730 nm. Mars1 was able to bind a variety of structurally similar probes that differ in color and membrane permeability. We demonstrated that a tool kit of multiple probes can be used to label extracellular and intracellular reporter-tagged receptor pools with 2 colors. Imaging studies may benefit from this far-red excited reporter/probe system, which features tight coupling between probe fluorescence and reporter binding and offers the option of using an expandable family of fluorogenic probes with a single reporter gene.
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22
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Larsen MB, Hu J, Frizzell RA, Watkins SC. Simple image-based no-wash method for quantitative detection of surface expressed CFTR. Methods 2015; 96:40-45. [PMID: 26361332 DOI: 10.1016/j.ymeth.2015.09.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 09/04/2015] [Accepted: 09/05/2015] [Indexed: 12/17/2022] Open
Abstract
Cystic fibrosis (CF) is the most common lethal genetic disease among Caucasians. It is caused by mutations in the CF Transmembrane Conductance Regulator (CFTR) gene, which encodes an apical membrane anion channel that is required for regulating the volume and composition of epithelial secretions. The most common CFTR mutation, present on at least one allele in >90% of CF patients, deletes phenylalanine at position 508 (F508del), which causes the protein to misfold. Endoplasmic reticulum (ER) quality control elicits the degradation of mutant CFTR, compromising its trafficking to the epithelial cell apical membrane. The absence of functional CFTR leads to depletion of airway surface liquid, impaired clearance of mucus and bacteria from the lung, and predisposes to recurrent infections. Ultimately, respiratory failure results from inflammation and bronchiectasis. Although high throughput screening has identified small molecules that can restore the anion transport function of F508del CFTR, they correct less than 15% of WT CFTR activity, yielding insufficient clinical benefit. To date, most primary CF drug discovery assays have employed measurements of CFTR's anion transport function, a method that depends on the recruitment of a functional CFTR to the cell surface, involves multiple wash steps, and relies on a signal that saturates rapidly. Screening efforts have also included assays for detection of extracellularly HA-tagged or HRP-tagged CFTR, which require multiple washing steps. We have recently developed tools and cell lines that report the correction of mutant CFTR trafficking by currently available small molecules, and have extended this assay to the 96-well format. This new and simple no-wash assay of F508del CFTR at the cell surface may permit the discovery of more efficacious drugs, and hopefully thereby prevent the catastrophic effects of this disease. In addition, the modular design of this platform should make it useful for other diseases where loss-of-function results from folding and/or trafficking defects in membrane proteins.
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Affiliation(s)
- Mads Breum Larsen
- Department of Cell Biology and Physiology, Center for Biologic Imaging, University of Pittsburgh School of Medicine, 3500 Terrace Street, S233 BST, Pittsburgh, PA 15261, USA.
| | - Jennifer Hu
- Department of Cell Biology and Physiology, Center for Biologic Imaging, University of Pittsburgh School of Medicine, 3500 Terrace Street, S233 BST, Pittsburgh, PA 15261, USA.
| | - Raymond A Frizzell
- Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, 7116 Rangos Research Center, 4401 Penn Avenue, Pittsburgh, PA 15224, USA.
| | - Simon C Watkins
- Department of Cell Biology and Physiology, Center for Biologic Imaging, University of Pittsburgh School of Medicine, 3500 Terrace Street, S233 BST, Pittsburgh, PA 15261, USA.
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23
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miR-16 rescues F508del-CFTR function in native cystic fibrosis epithelial cells. Gene Ther 2015; 22:908-16. [PMID: 26133785 DOI: 10.1038/gt.2015.56] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 05/29/2015] [Accepted: 06/03/2015] [Indexed: 12/21/2022]
Abstract
Cystic fibrosis (CF) is due to mutations in the CFTR gene, which prevents correct folding, trafficking and function of the mutant cystic fibrosis transmembrane conductance regulator (CFTR) protein. The dysfunctional effect of CFTR mutations, principally the F508del-CFTR mutant, is further manifested by hypersecretion of the pro-inflammatory chemokine interleukin-8 into the airway lumen, which further contributes to morbidity and mortality. We have hypothesized that microRNA (miR)-based therapeutics could rescue the dysfunctional consequences of mutant CFTR. Here we report that a miR-16 mimic can effectively rescue F508del-CFTR protein function in airway cell lines and primary cultures, of differentiated human bronchial epithelia from F508del homozygotes, which express mutant CFTR endogenously. We also identify two other miRs, miR-1 and miR-302a, which are also active. Although miR-16 is expressed at basal comparable levels in CF and control cells, miR-1 and miR-302a are undetectable. When miR mimics are expressed in CF lung or pancreatic cells, the expression of the F508del-CFTR protein is significantly increased. Importantly, miR-16 promotes functional rescue of the cyclic AMP-activated apical F508del-CFTR chloride channel in primary lung epithelial cells from CF patients. We interpret these findings to suggest that these miRs may constitute novel targets for CF therapy.
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24
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Bruchez MP. Dark dyes-bright complexes: fluorogenic protein labeling. Curr Opin Chem Biol 2015; 27:18-23. [PMID: 26056741 DOI: 10.1016/j.cbpa.2015.05.014] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 05/15/2015] [Accepted: 05/19/2015] [Indexed: 11/16/2022]
Abstract
Complexes formed between organic dyes and genetically encoded proteins combine the advantages of stable and tunable fluorescent molecules and targetable, biologically integrated labels. To overcome the challenges imposed by labeling with bright fluorescent dyes, a number of approaches now exploit chemical or environmental changes to control the properties of a bound dye, converting dyes from a weakly fluorescent state to a bright, easily detectable complex. Optimized, such approaches avoid the need for removal of unbound dyes, facilitate rapid and simple assays in cultured cells and enable hybrid labeling to function more robustly in living model organisms.
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Affiliation(s)
- Marcel P Bruchez
- Molecular Biosensor and Imaging Center, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA; Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA; Department of Biological Sciences, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA.
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25
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Rudashevskaya EL, Stockner T, Trauner M, Freissmuth M, Chiba P. Pharmacological correction of misfolding of ABC proteins. DRUG DISCOVERY TODAY. TECHNOLOGIES 2015; 12:e87-94. [PMID: 25027379 PMCID: PMC4039138 DOI: 10.1016/j.ddtec.2014.03.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The endoplasmic reticulum (ER) quality control system distinguishes between correctly and incorrectly folded proteins to prevent processing of aberrantly folded conformations along the secretory pathway. Non-synonymous mutations can lead to misfolding of ABC proteins and associated disease phenotypes. Specific phenotypes may at least partially be corrected by small molecules, so-called pharmacological chaperones. Screening for folding correctors is expected to open an avenue for treatment of diseases such as cystic fibrosis and intrahepatic cholestasis.
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Affiliation(s)
- Elena L Rudashevskaya
- Institute of Medical Chemistry, Medical University of Vienna, Waehringerstrasse 10, Vienna, Austria
| | - Thomas Stockner
- Institute of Pharmacology, Medical University of Vienna, Waehringerstrasse 13, Vienna, Austria
| | - Michael Trauner
- Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Waehringer Guertel 18-20, Austria
| | - Michael Freissmuth
- Institute of Pharmacology, Medical University of Vienna, Waehringerstrasse 13, Vienna, Austria
| | - Peter Chiba
- Institute of Medical Chemistry, Medical University of Vienna, Waehringerstrasse 10, Vienna, Austria
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26
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Rapino D, Sabirzhanova I, Lopes-Pacheco M, Grover R, Guggino WB, Cebotaru L. Rescue of NBD2 mutants N1303K and S1235R of CFTR by small-molecule correctors and transcomplementation. PLoS One 2015; 10:e0119796. [PMID: 25799511 PMCID: PMC4370480 DOI: 10.1371/journal.pone.0119796] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 01/30/2015] [Indexed: 11/18/2022] Open
Abstract
Although, the most common Cystic Fibrosis mutation, ΔF508, in the cystic fibrosis transmembrane regulator. (CFTR), is located in nucleotide binding domain (NBD1), disease-causing mutations also occur in NBD2. To provide information on potential therapeutic strategies for mutations in NBD2, we studied, using a combination of biochemical approaches and newly created cell lines, two disease-causing NBD2 mutants, N1303K and S1235R. Surprisingly, neither was rescued by low temperature. Inhibition of proteasomes with MG132 or aggresomes with tubacin rescued the immature B and mature C bands of N1303K and S1235R, indicating that degradation occurs via proteasomes and aggresomes. We found no effect of the lysosome inhibitor E64. Thus, our results show that these NBD2 mutants are processing mutants with unique characteristics. Several known correctors developed to rescue ΔF508-CFTR, when applied either alone or in combination, significantly increased the maturation of bands B and C of both NBD 2 mutants. The best correction occurred with the combinations of C4 plus C18 or C3 plus C4. Co-transfection of truncated CFTR (∆27-264) into stably transfected cells was also able to rescue them. This demonstrates for the first time that transcomplementation with a truncated version of CFTR can rescue NBD2 mutants. Our results show that the N1303K mutation has a more profound effect on NBD2 processing than S1235R and that small-molecule correctors increase the maturation of bands B and C in NBD2 mutants. In addition, ∆27-264 was able to transcomplement both NDB2 mutants. We conclude that differences and similarities occur in the impact of mutations on NBD2 when compared to ΔF508-CFTR suggesting that individualized strategies may be needed to restore their function. Finally our results are important because they suggest that gene or corrector molecule therapies either alone or in combination individualized for NBD2 mutants may be beneficial for patients bearing N1303K or S1235R mutations.
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Affiliation(s)
- Daniele Rapino
- Department of Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Department of Physiology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
| | - Inna Sabirzhanova
- Department of Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Department of Physiology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
| | - Miquéias Lopes-Pacheco
- Department of Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Department of Physiology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
| | - Rahul Grover
- Department of Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Department of Physiology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
| | - William B. Guggino
- Department of Physiology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
| | - Liudmila Cebotaru
- Department of Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- * E-mail: .
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27
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Protein traffic disorders: an effective high-throughput fluorescence microscopy pipeline for drug discovery. Sci Rep 2015; 5:9038. [PMID: 25762484 PMCID: PMC4356983 DOI: 10.1038/srep09038] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 02/13/2015] [Indexed: 12/12/2022] Open
Abstract
Plasma membrane proteins are essential molecules in the cell which mediate interactions with the exterior milieu, thus representing key drug targets for present pharma. Not surprisingly, protein traffic disorders include a large range of diseases sharing the common mechanism of failure in the respective protein to reach the plasma membrane. However, specific therapies for these diseases are remarkably lacking. Herein, we report a robust platform for drug discovery applied to a paradigmatic genetic disorder affecting intracellular trafficking – Cystic Fibrosis. This platform includes (i) two original respiratory epithelial cellular models incorporating an inducible double-tagged traffic reporter; (ii) a plasma membrane protein traffic assay for high-throughput microscopy screening; and (iii) open-source image analysis software to quantify plasma membrane protein traffic. By allowing direct scoring of compounds rescuing the basic traffic defect, this platform enables an effective drug development pipeline, which can be promptly adapted to any traffic disorder-associated protein and leverage therapy development efforts.
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28
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Schwartz SL, Yan Q, Telmer CA, Lidke KA, Bruchez MP, Lidke DS. Fluorogen-activating proteins provide tunable labeling densities for tracking FcεRI independent of IgE. ACS Chem Biol 2015; 10:539-46. [PMID: 25343439 PMCID: PMC4340345 DOI: 10.1021/cb5005146] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Crosslinking of IgE bound FcεRI on mast cells and basophils by multivalent antigen leads to degranulation and the release of key inflammatory mediators that stimulate the allergic response. Here, we present and characterize the use of fluorogen-activating proteins (FAPs) for single particle tracking of FcεRI to investigate how receptor mobility is influenced after IgE-induced changes in mast cell behavior. FAPs are genetically encoded tags that bind a fluorogen dye and increase its brightness upon binding up to 20,000-fold. We demonstrate that, by titrating fluorogen concentration, labeling densities from ensemble to single particle can be achieved, independent of expression level and without the need for wash steps or photobleaching. The FcεRI γ-subunit fused to a FAP (FAP-γ) provides, for the first time, an IgE-independent probe for tracking this signaling subunit of FcεRI at the single molecule level. We show that the FcεRI γ-subunit dynamics are controlled by the IgE-binding α-subunit and that the cytokinergic IgE, SPE-7, induces mast cell activation without altering FcεRI mobility or promoting internalization. We take advantage of the far-red emission of the malachite green (MG) fluorogen to track FcεRI relative to dynamin-GFP and find that immobilized receptors readily correlate with locations of dynamin recruitment only under conditions that promote rapid endocytosis. These studies demonstrate the usefulness of the FAP system for single molecule studies and have provided new insights into the relationship among FcεRI structure, activity, and mobility.
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Affiliation(s)
- Samantha L. Schwartz
- Department of Pathology and Cancer
Research and Treatment Center, ‡Department of Physics
and Astronomy, University of New Mexico, Albuquerque, New Mexico 87131, United States
- Molecular Biosensor and Imaging Center, ∥Department of Biological
Sciences, ⊥Lane Center for
Computational Biology, #Department of Chemistry, Carnegie Mellon University, Pittsburgh Pennsylvania 15213, United States
| | - Qi Yan
- Department of Pathology and Cancer
Research and Treatment Center, ‡Department of Physics
and Astronomy, University of New Mexico, Albuquerque, New Mexico 87131, United States
- Molecular Biosensor and Imaging Center, ∥Department of Biological
Sciences, ⊥Lane Center for
Computational Biology, #Department of Chemistry, Carnegie Mellon University, Pittsburgh Pennsylvania 15213, United States
| | - Cheryl A. Telmer
- Department of Pathology and Cancer
Research and Treatment Center, ‡Department of Physics
and Astronomy, University of New Mexico, Albuquerque, New Mexico 87131, United States
- Molecular Biosensor and Imaging Center, ∥Department of Biological
Sciences, ⊥Lane Center for
Computational Biology, #Department of Chemistry, Carnegie Mellon University, Pittsburgh Pennsylvania 15213, United States
| | - Keith A. Lidke
- Department of Pathology and Cancer
Research and Treatment Center, ‡Department of Physics
and Astronomy, University of New Mexico, Albuquerque, New Mexico 87131, United States
- Molecular Biosensor and Imaging Center, ∥Department of Biological
Sciences, ⊥Lane Center for
Computational Biology, #Department of Chemistry, Carnegie Mellon University, Pittsburgh Pennsylvania 15213, United States
| | - Marcel P. Bruchez
- Department of Pathology and Cancer
Research and Treatment Center, ‡Department of Physics
and Astronomy, University of New Mexico, Albuquerque, New Mexico 87131, United States
- Molecular Biosensor and Imaging Center, ∥Department of Biological
Sciences, ⊥Lane Center for
Computational Biology, #Department of Chemistry, Carnegie Mellon University, Pittsburgh Pennsylvania 15213, United States
| | - Diane S. Lidke
- Department of Pathology and Cancer
Research and Treatment Center, ‡Department of Physics
and Astronomy, University of New Mexico, Albuquerque, New Mexico 87131, United States
- Molecular Biosensor and Imaging Center, ∥Department of Biological
Sciences, ⊥Lane Center for
Computational Biology, #Department of Chemistry, Carnegie Mellon University, Pittsburgh Pennsylvania 15213, United States
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29
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Awatade NT, Uliyakina I, Farinha CM, Clarke LA, Mendes K, Solé A, Pastor J, Ramos MM, Amaral MD. Measurements of Functional Responses in Human Primary Lung Cells as a Basis for Personalized Therapy for Cystic Fibrosis. EBioMedicine 2014; 2:147-53. [PMID: 26137539 PMCID: PMC4484512 DOI: 10.1016/j.ebiom.2014.12.005] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 12/16/2014] [Accepted: 12/16/2014] [Indexed: 01/08/2023] Open
Abstract
Background The best investigational drug to treat cystic fibrosis (CF) patients with the most common CF-causing mutation (F508del) is VX-809 (lumacaftor) which recently succeeded in Phase III clinical trial in combination with ivacaftor. This corrector rescues F508del-CFTR from its abnormal intracellular localization to the cell surface, a traffic defect shared by all Class II CFTR mutants. Our goal here is to test the efficacy of lumacaftor in other Class II mutants in primary human bronchial epithelial (HBE) cells derived from CF patients. Methods The effect of lumacaftor was investigated in primary HBE cells from non-CF and CF patients with F508del/F508del, A561E/A561E, N1303K/G542X, F508del/G542X and F508del/Y1092X genotypes by measurements of Forskolin plus Genistein-inducible equivalent short-circuit current (Ieq-SC-Fsk + Gen) in perfused open-circuit Ussing chambers. Efficacy of corrector C18 was also assessed on A561E/A561E and F508del/F508del cells. Results Our data indicate that A561E (when present in both alleles) responds positively to lumacaftor treatment at equivalent efficacy of F508del in primary HBE cells. Similarly, lumacaftor has a positive impact on Y1092X, but not on N1303K. Our data also show that cells with only one copy of F508del-CFTR respond less to VX-809. Moreover, there is great variability in lumacaftor responses among F508del-homozygous cells from different donors. Compound C18 failed to rescue A561E-CFTR but not in F508del-CFTR, thus plausibly it has a different mechanism of action distinct from lumacaftor. Conclusions CF patients with A561E (and likely also those with Y1029X) can potentially benefit from lumacaftor. Moreover, the methodology used here exemplifies how ex vivo approaches may apply personalized therapies to CF and possibly other respiratory diseases. A561E and Y1092X CFTR mutations (but not N1303K) respond positively to lumacaftor treatment. One copy of F508del-CFTR responds less to lumacaftor than 2 copies and F508del-responses vary greatly. CF patients with A561E (and likely also those with Y1029X) can potentially benefit from lumacaftor. The methodology used here exemplifies how ex vivo approaches may apply personalized therapies to CF and possibly other respiratory diseases.
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Key Words
- (ΔIeq-sc), equivalent short-circuit currents
- CF, cystic fibrosis
- CFTR, cystic fibrosis transmembrane conductance regulator
- ENaC, epithelial Na+ channel
- Fsk, forskolin
- Gen, Genistein
- HBE (cells), human bronchial epithelial cells
- Innovative treatments
- Mutation-specific therapies
- Personalized medicine
- Rare diseases
- Rte, transepithelial resistance.
- SEM, standard error of the mean
- TEER, transepithelial electrical resistance
- Vte, transepithelial voltage
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Affiliation(s)
- Nikhil T Awatade
- University of Lisboa, Faculty of Sciences, BioFIG-Center for Biodiversity, Functional and Integrative Genomics, Campo Grande, C8 bdg, 1749-016 Lisboa, Portugal
| | - Inna Uliyakina
- University of Lisboa, Faculty of Sciences, BioFIG-Center for Biodiversity, Functional and Integrative Genomics, Campo Grande, C8 bdg, 1749-016 Lisboa, Portugal
| | - Carlos M Farinha
- University of Lisboa, Faculty of Sciences, BioFIG-Center for Biodiversity, Functional and Integrative Genomics, Campo Grande, C8 bdg, 1749-016 Lisboa, Portugal
| | - Luka A Clarke
- University of Lisboa, Faculty of Sciences, BioFIG-Center for Biodiversity, Functional and Integrative Genomics, Campo Grande, C8 bdg, 1749-016 Lisboa, Portugal
| | - Karina Mendes
- University of Lisboa, Faculty of Sciences, BioFIG-Center for Biodiversity, Functional and Integrative Genomics, Campo Grande, C8 bdg, 1749-016 Lisboa, Portugal
| | - Amparo Solé
- Adult Cystic Fibrosis Unit, University Hospital la Fe, Boulevar Sur, 46026 Valencia, Spain
| | - Juan Pastor
- Thoracic Surgery Service, University Hospital la Fe, Av. Campanar 21, 46009 Valencia, Spain
| | - Maria Margarida Ramos
- University of Lisboa, Faculty of Sciences, BioFIG-Center for Biodiversity, Functional and Integrative Genomics, Campo Grande, C8 bdg, 1749-016 Lisboa, Portugal
| | - Margarida D Amaral
- University of Lisboa, Faculty of Sciences, BioFIG-Center for Biodiversity, Functional and Integrative Genomics, Campo Grande, C8 bdg, 1749-016 Lisboa, Portugal
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Caohuy H, Yang Q, Eudy Y, Ha TA, Xu AE, Glover M, Frizzell RA, Jozwik C, Pollard HB. Activation of 3-phosphoinositide-dependent kinase 1 (PDK1) and serum- and glucocorticoid-induced protein kinase 1 (SGK1) by short-chain sphingolipid C4-ceramide rescues the trafficking defect of ΔF508-cystic fibrosis transmembrane conductance regulator (ΔF508-CFTR). J Biol Chem 2014; 289:35953-68. [PMID: 25384981 DOI: 10.1074/jbc.m114.598649] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Cystic fibrosis (CF) is due to a folding defect in the CF transmembrane conductance regulator (CFTR) protein. The most common mutation, ΔF508, prevents CFTR from trafficking to the apical plasma membrane. Here we show that activation of the PDK1/SGK1 signaling pathway with C4-ceramide (C4-CER), a non-toxic small molecule, functionally corrects the trafficking defect in both cultured CF cells and primary epithelial cell explants from CF patients. The mechanism of C4-CER action involves a series of mutual autophosphorylation and phosphorylation events between PDK1 and SGK1. Detailed mechanistic studies indicate that C4-CER initially induces autophosphorylation of SGK1 at Ser(422). SGK1[Ser(P)(422)] and C4-CER coincidently bind PDK1 and permit PDK1 to autophosphorylate at Ser(241). Then PDK1[Ser(P)(241)] phosphorylates SGK1[Ser(P)(422)] at Thr(256) to generate fully activated SGK1[Ser(422), Thr(P)(256)]. SGK1[Ser(P)(422),Thr(P)(256)] phosphorylates and inactivates the E3 ubiquitin ligase Nedd4-2. ΔF508-CFTR is thus free to traffic to the plasma membrane. Importantly, C4-CER-mediated activation of both PDK1 and SGK1 is independent of the PI3K/Akt/mammalian target of rapamycin signaling pathway. Physiologically, C4-CER significantly increases maturation and stability of ΔF508-CFTR (t½ ∼10 h), enhances cAMP-activated chloride secretion, and suppresses hypersecretion of interleukin-8 (IL-8). We suggest that candidate drugs for CF directed against the PDK1/SGK1 signaling pathway, such as C4-CER, provide a novel therapeutic strategy for a life-limiting disorder that affects one child, on average, each day.
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Affiliation(s)
- Hung Caohuy
- From the Department of Anatomy, Physiology, and Genetics, School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814 and
| | - Qingfeng Yang
- From the Department of Anatomy, Physiology, and Genetics, School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814 and
| | - Yvonne Eudy
- From the Department of Anatomy, Physiology, and Genetics, School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814 and
| | - Thien-An Ha
- From the Department of Anatomy, Physiology, and Genetics, School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814 and
| | - Andrew E Xu
- From the Department of Anatomy, Physiology, and Genetics, School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814 and
| | - Matthew Glover
- the Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15224
| | - Raymond A Frizzell
- the Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15224
| | - Catherine Jozwik
- From the Department of Anatomy, Physiology, and Genetics, School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814 and
| | - Harvey B Pollard
- From the Department of Anatomy, Physiology, and Genetics, School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814 and
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31
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Ramachandran S, Osterhaus SR, Karp PH, Welsh MJ, McCray PB. A genomic signature approach to rescue ΔF508-cystic fibrosis transmembrane conductance regulator biosynthesis and function. Am J Respir Cell Mol Biol 2014; 51:354-62. [PMID: 24669817 DOI: 10.1165/rcmb.2014-0007oc] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The most common cystic fibrosis (CF) mutation, ΔF508, causes protein misfolding, leading to proteosomal degradation. We recently showed that expression of miR-138 enhances CF transmembrane conductance regulator (CFTR) biogenesis and partially rescues ΔF508-CFTR function in CF airway epithelia. We hypothesized that a genomic signature approach can be used to identify new bioactive small molecules affecting ΔF508-CFTR rescue. The Connectivity Map was used to identify 27 small molecules with potential to restore ΔF508-CFTR function in airway epithelia. The molecules were screened in vitro for efficacy in improving ΔF508-CFTR trafficking, maturation, and chloride current. We identified four small molecules that partially restore ΔF508-CFTR function in primary CF airway epithelia. Of these, pyridostigmine showed cooperativity with corrector compound 18 in improving ΔF508-CFTR function. There are few CF therapies based on new molecular insights. Querying the Connectivity Map with relevant genomic signatures offers a method to identify new candidates for rescuing ΔF508-CFTR function.
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32
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Saunders MJ, Block E, Sorkin A, Waggoner AS, Bruchez MP. A bifunctional converter: fluorescein quenching scFv/fluorogen activating protein for photostability and improved signal to noise in fluorescence experiments. Bioconjug Chem 2014; 25:1556-64. [PMID: 25072845 PMCID: PMC4140548 DOI: 10.1021/bc500273n] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
![]()
Monoclonal antibodies are one of
the most useful and ubiquitous
affinity reagents used in the biological sciences. Immunostaining
of fixed and live cells for microscopy or cytometry measurements frequently
employs fluorescently labeled antibodies, in particular fluorescein-labeled
antibodies. This dye emits light at a wavelength overlapping with
cellular autofluorescence, making it difficult to measure antibody
binding to proteins of relatively low copy number or in cells of high
green autofluorescence. A number of high affinity fluorescein binding
antibodies and antibody domains have been developed that quench the
dye’s fluorescence. Using a fluorescein-binding recombinant
antibody domain genetically fused to a fluorogen activating protein
(FAP), we demonstrate a molecular converter capable of binding and
quenching fluorescein, while binding and activating a fluorogenic
triarylmethane dye. This reagent converts fluorescein conjugates to
far-red fluorescent probes, where cellular autofluorescence is low,
improving signal-to-background of cell-based antibody binding measurements
by ∼7-fold. Microscopy experiments show colocalization of both
fluorescein and MG fluorescence. This dual affinity fluorescein-quenching-FAP
can also be used to convert fluorescein to the red fluorescing MG
fluorogen on biological molecules other than antibodies.
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Affiliation(s)
- Matthew J Saunders
- Molecular Biosensor and Imaging Center, §Department of Biological Sciences, ∥Department of Chemistry, Carnegie-Mellon University , Pittsburgh, Pennsylvania 15213, United States
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Favia M, Mancini MT, Bezzerri V, Guerra L, Laselva O, Abbattiscianni AC, Debellis L, Reshkin SJ, Gambari R, Cabrini G, Casavola V. Trimethylangelicin promotes the functional rescue of mutant F508del CFTR protein in cystic fibrosis airway cells. Am J Physiol Lung Cell Mol Physiol 2014; 307:L48-61. [PMID: 24816489 DOI: 10.1152/ajplung.00305.2013] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Cystic fibrosis transmembrane conductance regulator (CFTR) carrying the F508del mutation is retained in endoplasmic reticulum and fails to traffic to the cell surface where it functions as a protein kinase A (PKA)-activated chloride channel. Pharmacological correctors that rescue the trafficking of F508del CFTR may overcome this defect; however, the rescued F508del CFTR still displays reduced chloride permeability. Therefore, a combined administration of correctors and potentiators of the gating defect is ideal. We recently found that 4,6,4'-trimethylangelicin (TMA), besides inhibiting the expression of the IL-8 gene in airway cells in which the inflammatory response was challenged with Pseudomonas aeruginosa, also potentiates the cAMP/PKA-dependent activation of wild-type CFTR or F508del CFTR that has been restored to the plasma membrane. Here, we demonstrate that long preincubation with nanomolar concentrations of TMA is able to effectively rescue both F508del CFTR-dependent chloride secretion and F508del CFTR cell surface expression in both primary or secondary airway cell monolayers homozygous for F508del mutation. The correction effect of TMA seems to be selective for CFTR and persisted for 24 h after washout. Altogether, the results suggest that TMA, besides its anti-inflammatory and potentiator activities, also displays corrector properties.
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Affiliation(s)
- Maria Favia
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Maria T Mancini
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Valentino Bezzerri
- Laboratory of Molecular Pathology, Department of Pathology and Diagnostics, University Hospital Verona, Verona, Italy
| | - Lorenzo Guerra
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Onofrio Laselva
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Anna C Abbattiscianni
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Lucantonio Debellis
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Stephan J Reshkin
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Roberto Gambari
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy; and
| | - Giulio Cabrini
- Laboratory of Molecular Pathology, Department of Pathology and Diagnostics, University Hospital Verona, Verona, Italy
| | - Valeria Casavola
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy; Centre of Excellence in Comparative Genomics, University of Bari, Bari, Italy
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Luz S, Cihil KM, Brautigan DL, Amaral MD, Farinha CM, Swiatecka-Urban A. LMTK2-mediated phosphorylation regulates CFTR endocytosis in human airway epithelial cells. J Biol Chem 2014; 289:15080-93. [PMID: 24727471 PMCID: PMC4031558 DOI: 10.1074/jbc.m114.563742] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Cystic fibrosis transmembrane conductance regulator (CFTR) is a Cl−-selective ion channel expressed in fluid-transporting epithelia. Lemur tyrosine kinase 2 (LMTK2) is a transmembrane protein with serine and threonine but not tyrosine kinase activity. Previous work identified CFTR as an in vitro substrate of LMTK2, suggesting a functional link. Here we demonstrate that LMTK2 co-immunoprecipitates with CFTR and phosphorylates CFTR-Ser737 in human airway epithelial cells. LMTK2 knockdown or expression of inactive LMTK2 kinase domain increases cell surface density of CFTR by attenuating its endocytosis in human airway epithelial cells. Moreover, LMTK2 knockdown increases Cl− secretion mediated by the wild-type and rescued ΔF508-CFTR. Compared with the wild-type CFTR, the phosphorylation-deficient mutant CFTR-S737A shows increased cell surface density and decreased endocytosis. These results demonstrate a novel mechanism of the phospho-dependent inhibitory effect of CFTR-Ser737 mediated by LMTK2 via endocytosis and inhibition of the cell surface density of CFTR Cl− channels. These data indicate that targeting LMTK2 may increase the cell surface density of CFTR Cl− channels and improve stability of pharmacologically rescued ΔF508-CFTR in patients with cystic fibrosis.
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Affiliation(s)
- Simão Luz
- From the Centre for Biodiversity, Functional and Integrative Genomics, University of Lisboa, 1749-016 Lisboa, Portugal
| | - Kristine M Cihil
- the Department of Nephrology, Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania 15201
| | - David L Brautigan
- the Center for Cell Signaling and Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, and
| | - Margarida D Amaral
- From the Centre for Biodiversity, Functional and Integrative Genomics, University of Lisboa, 1749-016 Lisboa, Portugal
| | - Carlos M Farinha
- From the Centre for Biodiversity, Functional and Integrative Genomics, University of Lisboa, 1749-016 Lisboa, Portugal
| | - Agnieszka Swiatecka-Urban
- the Department of Nephrology, Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania 15201, the Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
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35
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Gallo E, Vasilev KV, Jarvik J. Fluorogen-activating-proteins as universal affinity biosensors for immunodetection. Biotechnol Bioeng 2014; 111:475-84. [PMID: 24122476 PMCID: PMC4334571 DOI: 10.1002/bit.25127] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 09/13/2013] [Accepted: 10/02/2013] [Indexed: 11/11/2022]
Abstract
Fluorogen-activating-proteins (FAPs) are a novel platform of fluorescence biosensors utilized for protein discovery. The technology currently demands molecular manipulation methods that limit its application and adaptability. Here, we highlight an alternative approach based on universal affinity reagents for protein detection. The affinity reagents were engineered as bi-partite fusion proteins, where the specificity moiety is derived from IgG-binding proteins-Protein A or Protein G-and the signaling element is a FAP. In this manner, primary antibodies provide the antigenic selectivity against a desired protein in biological samples, while FAP affinity reagents target the constant region (Fc) of antibodies and provide the biosensor component of detection. Fluorescence results using various techniques indicate minimal background and high target specificity for exogenous and endogenous proteins in mammalian cells. Additionally, FAP-based affinity reagents provide enhanced properties of detection previously absent using conventional affinity systems. Distinct features explored in this report include: (1) unfixed signal wavelengths (excitation and emission) determined by the particular fluorogen chosen, (2) real-time user controlled fluorescence on-set and off-set, (3) signal wavelength substitution while performing live analysis, and (4) enhanced resistance to photobleaching.
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Affiliation(s)
- Eugenio Gallo
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA 15213
| | - Kalin V. Vasilev
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA 15213
| | - Jonathan Jarvik
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA 15213
- Molecular Biosensor and Imaging Center, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA 15213
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Pharmacological chaperoning: a primer on mechanism and pharmacology. Pharmacol Res 2014; 83:10-9. [PMID: 24530489 DOI: 10.1016/j.phrs.2014.01.005] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 01/29/2014] [Indexed: 12/26/2022]
Abstract
Approximately forty percent of diseases are attributable to protein misfolding, including those for which genetic mutation produces misfolding mutants. Intriguingly, many of these mutants are not terminally misfolded since native-like folding, and subsequent trafficking to functional locations, can be induced by target-specific, small molecules variably termed pharmacological chaperones, pharmacoperones, or pharmacochaperones (PCs). PC targets include enzymes, receptors, transporters, and ion channels, revealing the breadth of proteins that can be engaged by ligand-assisted folding. The purpose of this review is to provide an integrated primer of the diverse mechanisms and pharmacology of PCs. In this regard, we examine the structural mechanisms that underlie PC rescue of misfolding mutants, including the ability of PCs to act as surrogates for defective intramolecular interactions and, at the intermolecular level, overcome oligomerization deficiencies and dominant negative effects, as well as influence the subunit stoichiometry of heteropentameric receptors. Not surprisingly, PC-mediated structural correction of misfolding mutants normalizes interactions with molecular chaperones that participate in protein quality control and forward-trafficking. A variety of small molecules have proven to be efficacious PCs and the advantages and disadvantages of employing orthostatic antagonists, active-site inhibitors, orthostatic agonists, and allosteric modulator PCs are considered. Also examined is the possibility that several therapeutic agents may have unrecognized activity as PCs, and this chaperoning activity may mediate/contribute to therapeutic action and/or account for adverse effects. Lastly, we explore evidence that pharmacological chaperoning exploits intrinsic ligand-assisted folding mechanisms. Given the widespread applicability of PC rescue of mutants associated with protein folding disorders, both in vitro and in vivo, the therapeutic potential of PCs is vast. This is most evident in the treatment of lysosomal storage disorders, cystic fibrosis, and nephrogenic diabetes insipidus, for which proof of principle in humans has been demonstrated.
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Yan Q, Schwartz SL, Maji S, Huang F, Szent-Gyorgyi C, Lidke DS, Lidke KA, Bruchez MP. Localization microscopy using noncovalent fluorogen activation by genetically encoded fluorogen-activating proteins. Chemphyschem 2013; 15:687-695. [PMID: 24194371 DOI: 10.1002/cphc.201300757] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Revised: 09/02/2013] [Indexed: 11/10/2022]
Abstract
The noncovalent equilibrium activation of a fluorogenic malachite green dye and its cognate fluorogen-activating protein (FAP) can produce a sparse labeling distribution of densely tagged genetically encoded proteins, enabling single molecule detection and super-resolution imaging in fixed and living cells. These sparse labeling conditions are achieved by control of the dye concentration in the milieu, and do not require any photoswitching or photoactivation. The labeling is achieved by using physiological buffers and cellular media, in which additives and switching buffers are not required to obtain super-resolution images. We evaluate the super-resolution properties and images obtained from a selected FAP clone fused to actin, and show that the photon counts per object are between those typically reported for fluorescent proteins and switching-dye pairs, resulting in 10-30 nm localization precision per object. This labeling strategy complements existing approaches, and may simplify multicolor labeling of cellular structures.
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Affiliation(s)
- Qi Yan
- Molecular Biosensor and Imaging Center, Carnegie Mellon Unviersity, Pittsburgh PA 15213.,Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213
| | - Samantha L Schwartz
- Department of Pathology and Cancer Research and Treatment Center, University of New Mexico, Albuquerque, NM 87131
| | - Suvrajit Maji
- Molecular Biosensor and Imaging Center, Carnegie Mellon Unviersity, Pittsburgh PA 15213.,Lane Center for Computational Biology, Carnegie Mellon University, Pittsburgh, PA 15213
| | - Fang Huang
- Department of Physics, University of New Mexico, Albuquerque, NM 87131
| | - Chris Szent-Gyorgyi
- Molecular Biosensor and Imaging Center, Carnegie Mellon Unviersity, Pittsburgh PA 15213
| | - Diane S Lidke
- Department of Pathology and Cancer Research and Treatment Center, University of New Mexico, Albuquerque, NM 87131
| | - Keith A Lidke
- Department of Physics, University of New Mexico, Albuquerque, NM 87131
| | - Marcel P Bruchez
- Molecular Biosensor and Imaging Center, Carnegie Mellon Unviersity, Pittsburgh PA 15213.,Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213.,Lane Center for Computational Biology, Carnegie Mellon University, Pittsburgh, PA 15213.,Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213
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Yates BP, Peck MA, Berget PB. Directed evolution of a fluorogen-activating single chain antibody for function and enhanced brightness in the cytoplasm. Mol Biotechnol 2013; 54:829-41. [PMID: 23242633 DOI: 10.1007/s12033-012-9631-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Directed evolution is an exceptionally powerful tool that uses random mutant library generation and screening techniques to engineer or optimize functions of proteins. One class of proteins for which this process is particularly effective is antibodies, where properties such as antigen specificity and affinity can be selected to yield molecules with improved efficacy as molecular labels or in potential therapeutics. Typical antibody structure includes disulfide bonds that are required for stability and proper folding of the domains. However, these bonds are unable to form in the reducing environment of the cytoplasm, stymieing the effectiveness of optimized antibodies in many research applications. We have removed disulfide-forming cysteine residues in a single chain antibody fluorogen-activating protein (FAP), HL4, and employed directed evolution to select a derivative that is capable of activity in the cytoplasm. A subsequent round of directed evolution was targeted at increasing the overall brightness of the fluoromodule (FAP-fluorogen complex). Ultimately, this approach produced a novel FAP that exhibits strong activation of its cognate fluorogen in the reducing environment of the cytoplasm, significantly expanding the range of applications for which fluoromodule technology can be utilized.
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Affiliation(s)
- Bradley P Yates
- Department of Biological Sciences & Molecular Biosensor and Imaging Center, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA
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Hanrahan JW, Sampson HM, Thomas DY. Novel pharmacological strategies to treat cystic fibrosis. Trends Pharmacol Sci 2013; 34:119-25. [PMID: 23380248 DOI: 10.1016/j.tips.2012.11.006] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 11/28/2012] [Accepted: 11/28/2012] [Indexed: 12/15/2022]
Abstract
Cystic fibrosis (CF) is a lethal disease caused by mutations in the CFTR gene. The most frequent mutation is deletion of a phenylalanine residue (ΔF508) that results in retention of the mutant, but otherwise functional, protein in the endoplasmic reticulum (ER). There have been recent advances in the identification of chemically diverse corrector compounds that allow ΔF508-CFTR protein to traffic from the ER to the plasma membrane. The most studied correctors fall into two categories, pharmacological chaperones that bind to the mutant protein and circumvent its recognition by the cellular protein quality control systems and proteostasis regulators that modify the cellular pathways responsible for protein quality control and trafficking. This review focuses on recent advances in the field, strategies for the development of drugs from corrector compounds for the treatment of CF, and identification of their targets and mechanism(s) of action.
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Affiliation(s)
- John W Hanrahan
- Cystic Fibrosis Translation Research centre, Faculty of Medicine, McGill University, 3655 Promenade Sir William Osler, Montreal H3G 1Y6, Quebec, Canada
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40
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Brown M, Stafford LJ, Onisk D, Joaquim T, Tobb A, Goldman L, Fancy D, Stave J, Chambers R. Snorkel: an epitope tagging system for measuring the surface expression of membrane proteins. PLoS One 2013; 8:e73255. [PMID: 24023844 PMCID: PMC3759426 DOI: 10.1371/journal.pone.0073255] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 07/17/2013] [Indexed: 02/01/2023] Open
Abstract
Tags are widely used to monitor a protein’s expression level, interactions, protein trafficking, and localization. Membrane proteins are often tagged in their extracellular domains to allow discrimination between protein in the plasma membrane from that in internal pools. Multipass membrane proteins offer special challenges for inserting a tag since the extracellular regions are often composed of small loops and thus inserting an epitope tag risks perturbing the structure, function, or location of the membrane protein. We have developed a novel tagging system called snorkel where a transmembrane domain followed by a tag is appended to the cytoplasmic C-terminus of the membrane protein. In this way the tag is displayed extracellularly, but structurally separate from the membrane protein. We have tested the snorkel tag system on a diverse panel of membrane proteins including GPCRs and ion channels and demonstrated that it reliably allows for monitoring of the surface expression.
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Affiliation(s)
| | | | - Dale Onisk
- SDIX, Newark, Delaware, United States of America
| | - Tony Joaquim
- SDIX, Newark, Delaware, United States of America
| | - Alhagie Tobb
- SDIX, Newark, Delaware, United States of America
| | | | - David Fancy
- SDIX, Newark, Delaware, United States of America
| | - James Stave
- SDIX, Newark, Delaware, United States of America
| | - Ross Chambers
- SDIX, Newark, Delaware, United States of America
- * E-mail:
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Szent-Gyorgyi C, Stanfield RL, Andreko S, Dempsey A, Ahmed M, Capek S, Waggoner AS, Wilson IA, Bruchez MP. Malachite green mediates homodimerization of antibody VL domains to form a fluorescent ternary complex with singular symmetric interfaces. J Mol Biol 2013; 425:4595-613. [PMID: 23978698 DOI: 10.1016/j.jmb.2013.08.014] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 08/15/2013] [Accepted: 08/16/2013] [Indexed: 01/19/2023]
Abstract
We report that a symmetric small-molecule ligand mediates the assembly of antibody light chain variable domains (VLs) into a correspondent symmetric ternary complex with novel interfaces. The L5* fluorogen activating protein is a VL domain that binds malachite green (MG) dye to activate intense fluorescence. Crystallography of liganded L5* reveals a 2:1 protein:ligand complex with inclusive C2 symmetry, where MG is almost entirely encapsulated between an antiparallel arrangement of the two VL domains. Unliganded L5* VL domains crystallize as a similar antiparallel VL/VL homodimer. The complementarity-determining regions are spatially oriented to form novel VL/VL and VL/ligand interfaces that tightly constrain a propeller conformer of MG. Binding equilibrium analysis suggests highly cooperative assembly to form a very stable VL/MG/VL complex, such that MG behaves as a strong chemical inducer of dimerization. Fusion of two VL domains into a single protein tightens MG binding over 1000-fold to low picomolar affinity without altering the large binding enthalpy, suggesting that bonding interactions with ligand and restriction of domain movements make independent contributions to binding. Fluorescence activation of a symmetrical fluorogen provides a selection mechanism for the isolation and directed evolution of ternary complexes where unnatural symmetric binding interfaces are favored over canonical antibody interfaces. As exemplified by L5*, these self-reporting complexes may be useful as modulators of protein association or as high-affinity protein tags and capture reagents.
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Affiliation(s)
- Chris Szent-Gyorgyi
- Molecular Biosensor and Imaging Center, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
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42
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Holleran JP, Zeng J, Frizzell RA, Watkins SC. Regulated recycling of mutant CFTR is partially restored by pharmacological treatment. J Cell Sci 2013; 126:2692-703. [PMID: 23572510 DOI: 10.1242/jcs.120196] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Efficient trafficking of the cystic fibrosis transmembrane conductance regulator (CFTR) to and from the cell surface is essential for maintaining channel density at the plasma membrane (PM) and ensuring proper physiological activity. The most common mutation, F508del, exhibits reduced surface expression and impaired function despite treatment with currently available pharmacological small molecules, called correctors. To gain more detailed insight into whether CFTR enters compartments that allow corrector stabilization in the cell periphery, we investigated the peripheral trafficking itineraries and kinetics of wild type (WT) and F508del in living cells using high-speed fluorescence microscopy together with fluorogen activating protein detection. We directly visualized internalization and accumulation of CFTR WT from the PM to a perinuclear compartment that colocalized with the endosomal recycling compartment (ERC) markers Rab11 and EHD1, reaching steady-state distribution by 25 minutes. Stimulation by protein kinase A (PKA) depleted this intracellular pool and redistributed CFTR channels to the cell surface, elicited by reduced endocytosis and active translocation to the PM. Corrector or temperature rescue of F508del also resulted in targeting to the ERC and exhibited subsequent PKA-stimulated trafficking to the PM. Corrector treatment (24 hours) led to persistent residence of F508del in the ERC, while thermally destabilized F508del was targeted to lysosomal compartments by 3 hours. Acute addition of individual correctors, C4 or C18, acted on peripheral trafficking steps to partially block lysosomal targeting of thermally destabilized F508del. Taken together, corrector treatment redirects F508del trafficking from a degradative pathway to a regulated recycling route, and proteins that mediate this process become potential targets for improving the efficacy of current and future correctors.
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Affiliation(s)
- John P Holleran
- University of Pittsburgh School of Medicine, Department of Cell Biology, BSTS 225, 3500 Terrace St, Pittsburgh, PA 15261, USA
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Shank NI, Pham HH, Waggoner AS, Armitage BA. Twisted cyanines: a non-planar fluorogenic dye with superior photostability and its use in a protein-based fluoromodule. J Am Chem Soc 2012; 135:242-51. [PMID: 23252842 DOI: 10.1021/ja308629w] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The cyanine dye thiazole orange (TO) is a well-known fluorogenic stain for DNA and RNA, but this property precludes its use as an intracellular fluorescent probe for non-nucleic acid biomolecules. Further, as is the case with many cyanines, the dye suffers from low photostability. Here, we report the synthesis of a bridge-substituted version of TO named α-CN-TO, where the central methine hydrogen of TO is replaced by an electron withdrawing cyano group, which was expected to decrease the susceptibility of the dye toward singlet oxygen-mediated degradation. An X-ray crystal structure shows that α-CN-TO is twisted drastically out of plane, in contrast to TO, which crystallizes in the planar conformation. α-CN-TO retains the fluorogenic behavior of the parent dye TO in viscous glycerol/water solvent, but direct irradiation and indirect bleaching studies showed that α-CN-TO is essentially inert to visible light and singlet oxygen. In addition, the twisted conformation of α-CN-TO mitigates nonspecific binding and fluorescence activation by DNA and a previously selected TO-binding protein and exhibits low background fluorescence in HeLa cell culture. α-CN-TO was then used to select a new protein that binds and activates fluorescence from the dye. The new α-CN-TO/protein fluoromodule exhibits superior photostability to an analogous TO/protein fluoromodule. These properties indicate that α-CN-TO will be a useful fluorogenic dye in combination with specific RNA and protein binding partners for both in vitro and cell-based applications. More broadly, structural features that promote nonplanar conformations can provide an effective method for reducing nonspecific binding of cationic dyes to nucleic acids and other biomolecules.
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Affiliation(s)
- Nathaniel I Shank
- Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
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