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Trujillo J, Khan AS, Adhikari DP, Stoneman MR, Chacko JV, Eliceiri KW, Raicu V. Implementation of FRET Spectrometry Using Temporally Resolved Fluorescence: A Feasibility Study. Int J Mol Sci 2024; 25:4706. [PMID: 38731924 PMCID: PMC11083457 DOI: 10.3390/ijms25094706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2024] [Revised: 04/21/2024] [Accepted: 04/22/2024] [Indexed: 05/13/2024] Open
Abstract
Förster resonance energy transfer (FRET) spectrometry is a method for determining the quaternary structure of protein oligomers from distributions of FRET efficiencies that are drawn from pixels of fluorescence images of cells expressing the proteins of interest. FRET spectrometry protocols currently rely on obtaining spectrally resolved fluorescence data from intensity-based experiments. Another imaging method, fluorescence lifetime imaging microscopy (FLIM), is a widely used alternative to compute FRET efficiencies for each pixel in an image from the reduction of the fluorescence lifetime of the donors caused by FRET. In FLIM studies of oligomers with different proportions of donors and acceptors, the donor lifetimes may be obtained by fitting the temporally resolved fluorescence decay data with a predetermined number of exponential decay curves. However, this requires knowledge of the number and the relative arrangement of the fluorescent proteins in the sample, which is precisely the goal of FRET spectrometry, thus creating a conundrum that has prevented users of FLIM instruments from performing FRET spectrometry. Here, we describe an attempt to implement FRET spectrometry on temporally resolved fluorescence microscopes by using an integration-based method of computing the FRET efficiency from fluorescence decay curves. This method, which we dubbed time-integrated FRET (or tiFRET), was tested on oligomeric fluorescent protein constructs expressed in the cytoplasm of living cells. The present results show that tiFRET is a promising way of implementing FRET spectrometry and suggest potential instrument adjustments for increasing accuracy and resolution in this kind of study.
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Affiliation(s)
- Justin Trujillo
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA; (J.T.); (A.S.K.); (D.P.A.); (M.R.S.)
| | - Aliyah S. Khan
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA; (J.T.); (A.S.K.); (D.P.A.); (M.R.S.)
| | - Dhruba P. Adhikari
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA; (J.T.); (A.S.K.); (D.P.A.); (M.R.S.)
| | - Michael R. Stoneman
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA; (J.T.); (A.S.K.); (D.P.A.); (M.R.S.)
| | - Jenu V. Chacko
- Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI 53705, USA; (J.V.C.); (K.W.E.)
| | - Kevin W. Eliceiri
- Center for Quantitative Cell Imaging, University of Wisconsin-Madison, Madison, WI 53705, USA; (J.V.C.); (K.W.E.)
- Departments of Biomedical Engineering and Medical Physics, University of Wisconsin-Madison, Madison, WI 53705, USA
- Morgridge Institute for Research, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Valerica Raicu
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA; (J.T.); (A.S.K.); (D.P.A.); (M.R.S.)
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Bestsennaia E, Maslov I, Balandin T, Alekseev A, Yudenko A, Abu Shamseye A, Zabelskii D, Baumann A, Catapano C, Karathanasis C, Gordeliy V, Heilemann M, Gensch T, Borshchevskiy V. Channelrhodopsin-2 Oligomerization in Cell Membrane Revealed by Photo-Activated Localization Microscopy. Angew Chem Int Ed Engl 2024; 63:e202307555. [PMID: 38226794 DOI: 10.1002/anie.202307555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 01/03/2024] [Accepted: 01/15/2024] [Indexed: 01/17/2024]
Abstract
Microbial rhodopsins are retinal membrane proteins that found a broad application in optogenetics. The oligomeric state of rhodopsins is important for their functionality and stability. Of particular interest is the oligomeric state in the cellular native membrane environment. Fluorescence microscopy provides powerful tools to determine the oligomeric state of membrane proteins directly in cells. Among these methods is quantitative photoactivated localization microscopy (qPALM) allowing the investigation of molecular organization at the level of single protein clusters. Here, we apply qPALM to investigate the oligomeric state of the first and most used optogenetic tool Channelrhodopsin-2 (ChR2) in the plasma membrane of eukaryotic cells. ChR2 appeared predominantly as a dimer in the cell membrane and did not form higher oligomers. The disulfide bonds between Cys34 and Cys36 of adjacent ChR2 monomers were not required for dimer formation and mutations disrupting these bonds resulted in only partial monomerization of ChR2. The monomeric fraction increased when the total concentration of mutant ChR2 in the membrane was low. The dissociation constant was estimated for this partially monomerized mutant ChR2 as 2.2±0.9 proteins/μm2 . Our findings are important for understanding the mechanistic basis of ChR2 activity as well as for improving existing and developing future optogenetic tools.
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Affiliation(s)
- Ekaterina Bestsennaia
- Institute of Biological Information Processing 1, IBI-1 (Molecular and Cellular Physiology), Forschungszentrum Jülich, 52428, Jülich, Germany
| | - Ivan Maslov
- Dynamic Bioimaging Lab, Advanced Optical Microscopy Centre and the Biomedical Research Institute, Hasselt University, B3590, Diepenbeek, Belgium
- Laboratory for Photochemistry and Spectroscopy, Division for Molecular Imaging and Photonics, Department of Chemistry, KU Leuven, 3001, Leuven, Belgium
| | - Taras Balandin
- Institute of Biological Information Processing 7, IBI-7 (Structural Biochemistry), Forschungszentrum Jülich, 52428, Jülich, Germany
| | - Alexey Alekseev
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37075, Göttingen, Germany
| | - Anna Yudenko
- Department of Biomedical Sciences, University Medical Center Groningen, University of Groningen, 9713 AV, Groningen, The Netherlands
| | - Assalla Abu Shamseye
- Institute of Biological Information Processing 1, IBI-1 (Molecular and Cellular Physiology), Forschungszentrum Jülich, 52428, Jülich, Germany
- Institute of Biological Information Processing 7, IBI-7 (Structural Biochemistry), Forschungszentrum Jülich, 52428, Jülich, Germany
| | - Dmitrii Zabelskii
- Institute of Biological Information Processing 7, IBI-7 (Structural Biochemistry), Forschungszentrum Jülich, 52428, Jülich, Germany
- European XFEL, 22869, Schenefeld, Germany
| | - Arnd Baumann
- Institute of Biological Information Processing 1, IBI-1 (Molecular and Cellular Physiology), Forschungszentrum Jülich, 52428, Jülich, Germany
| | - Claudia Catapano
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, 60438, Frankfurt, Germany
| | - Christos Karathanasis
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, 60438, Frankfurt, Germany
| | - Valentin Gordeliy
- Institute of Biological Information Processing 7, IBI-7 (Structural Biochemistry), Forschungszentrum Jülich, 52428, Jülich, Germany
| | - Mike Heilemann
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, 60438, Frankfurt, Germany
| | - Thomas Gensch
- Institute of Biological Information Processing 1, IBI-1 (Molecular and Cellular Physiology), Forschungszentrum Jülich, 52428, Jülich, Germany
| | - Valentin Borshchevskiy
- Institute of Biological Information Processing 7, IBI-7 (Structural Biochemistry), Forschungszentrum Jülich, 52428, Jülich, Germany
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3
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The M 1 muscarinic receptor is present in situ as a ligand-regulated mixture of monomers and oligomeric complexes. Proc Natl Acad Sci U S A 2022; 119:e2201103119. [PMID: 35671422 PMCID: PMC9214538 DOI: 10.1073/pnas.2201103119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Although it is appreciated that members of the large family of rhodopsin-like cell surface receptors can form dimeric or larger protein complexes when expressed at high levels in cultured cells, their organizational state within native cells and tissues of the body is largely unknown. We assessed this in neurons of the central nervous system by replacing the M1 muscarinic acetylcholine receptor in mice with a form of this receptor with an added fluorescent protein. Receptor function was unaltered by this change, and the biophysical approach we used demonstrated that the receptor exists as a mixture of monomers and dimers or oligomers. Drug treatments that target this receptor promote its monomerization, which may have significance for receptor function. The quaternary organization of rhodopsin-like G protein-coupled receptors in native tissues is unknown. To address this we generated mice in which the M1 muscarinic acetylcholine receptor was replaced with a C-terminally monomeric enhanced green fluorescent protein (mEGFP)–linked variant. Fluorescence imaging of brain slices demonstrated appropriate regional distribution, and using both anti-M1 and anti–green fluorescent protein antisera the expressed transgene was detected in both cortex and hippocampus only as the full-length polypeptide. M1-mEGFP was expressed at levels equal to the M1 receptor in wild-type mice and was expressed throughout cell bodies and projections in cultured neurons from these animals. Signaling and behavioral studies demonstrated M1-mEGFP was fully active. Application of fluorescence intensity fluctuation spectrometry to regions of interest within M1-mEGFP–expressing neurons quantified local levels of expression and showed the receptor was present as a mixture of monomers, dimers, and higher-order oligomeric complexes. Treatment with both an agonist and an antagonist ligand promoted monomerization of the M1-mEGFP receptor. The quaternary organization of a class A G protein-coupled receptor in situ was directly quantified in neurons in this study, which answers the much-debated question of the extent and potential ligand-induced regulation of basal quaternary organization of such a receptor in native tissue when present at endogenous expression levels.
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Cevheroğlu O, Murat M, Mingu-Akmete S, Son ÇD. Ste2p Under the Microscope: the Investigation of Oligomeric States of a Yeast G Protein-Coupled Receptor. J Phys Chem B 2021; 125:9526-9536. [PMID: 34433281 DOI: 10.1021/acs.jpcb.1c05872] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Oligomerization of G protein-coupled receptors (GPCRs) may play important roles in maturation, internalization, signaling, and pharmacology of these receptors. However, the nature and extent of their oligomerization is still under debate. In our study, Ste2p, a yeast mating pheromone GPCR, was tagged with enhanced green fluorescent protein (EGFP), mCherry, and with split florescent protein fragments at the receptor C-terminus. The Förster resonance energy transfer (FRET) technique was used to detect receptors' oligomerization by calculating the energy transfer from EGFP to mCherry. Stimulation of Ste2p oligomers with the receptor ligand did not result in any significant change on observed FRET values. The bimolecular fluorescence complementation (BiFC) assay was combined with FRET to further investigate the tetrameric complexes of Ste2p. Our results suggest that in its quiescent (nonligand-activated) state, Ste2p is found at least as a tetrameric complex on the plasma membrane. Intriguingly, receptor tetramers in their active form showed a significant increase in FRET. This study provides a direct in vivo visualization of Ste2p tetramers and the pheromone effect on the extent of the receptor oligomerization.
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Affiliation(s)
- Orkun Cevheroğlu
- Stem Cell Institute, Ankara University, Cankaya, 06520 Ankara, Turkey
| | - Merve Murat
- Stem Cell Institute, Ankara University, Cankaya, 06520 Ankara, Turkey.,Department of Biological Sciences, Middle East Technical University, Cankaya, 06800 Ankara, Turkey
| | - Sara Mingu-Akmete
- Stem Cell Institute, Ankara University, Cankaya, 06520 Ankara, Turkey.,Department of Biological Sciences, Middle East Technical University, Cankaya, 06800 Ankara, Turkey
| | - Çağdaş D Son
- Department of Biological Sciences, Middle East Technical University, Cankaya, 06800 Ankara, Turkey
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5
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Gertzen CGW, Gohlke H, Häussinger D, Herebian D, Keitel V, Kubitz R, Mayatepek E, Schmitt L. The many facets of bile acids in the physiology and pathophysiology of the human liver. Biol Chem 2021; 402:1047-1062. [PMID: 34049433 DOI: 10.1515/hsz-2021-0156] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 05/14/2021] [Indexed: 12/12/2022]
Abstract
Bile acids perform vital functions in the human liver and are the essential component of bile. It is therefore not surprising that the biology of bile acids is extremely complex, regulated on different levels, and involves soluble and membrane receptors as well as transporters. Hereditary disorders of these proteins manifest in different pathophysiological processes that result in liver diseases of varying severity. In this review, we summarize our current knowledge of the physiology and pathophysiology of bile acids with an emphasis on recently established analytical approaches as well as the molecular mechanisms that underlie signaling and transport of bile acids. In this review, we will focus on ABC transporters of the canalicular membrane and their associated diseases. As the G protein-coupled receptor, TGR5, receives increasing attention, we have included aspects of this receptor and its interaction with bile acids.
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Affiliation(s)
- Christoph G W Gertzen
- Institute of Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,Center for Structural Studies (CSS), Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Holger Gohlke
- Institute of Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,John von Neumann Institute for Computing (NIC), Jülich Supercomputing Centre (JSC), Institute of Biological Information Processing (IBI-7: Structural Biochemistry), Institute of Bio- and Geosciences (IBG-4: Bioinformatics), Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Dieter Häussinger
- Department of Gastroenterology, Hepatology and Infectious Diseases, University Hospital Düsseldorf, Düsseldorf, Germany
| | - Diran Herebian
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, Medical Faculty, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Verena Keitel
- Department of Gastroenterology, Hepatology and Infectious Diseases, University Hospital Düsseldorf, Düsseldorf, Germany
| | - Ralf Kubitz
- Department of Gastroenterology, Hepatology and Infectious Diseases, University Hospital Düsseldorf, Düsseldorf, Germany
| | - Ertan Mayatepek
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, Medical Faculty, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Lutz Schmitt
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
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6
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Franco R, Cordomí A, Llinas Del Torrent C, Lillo A, Serrano-Marín J, Navarro G, Pardo L. Structure and function of adenosine receptor heteromers. Cell Mol Life Sci 2021; 78:3957-3968. [PMID: 33580270 PMCID: PMC11072997 DOI: 10.1007/s00018-021-03761-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 01/07/2021] [Accepted: 01/15/2021] [Indexed: 11/25/2022]
Abstract
Adenosine is one of the most ancient signaling molecules and has receptors in both animals and plants. In mammals there are four specific receptors, A1, A2A, A2B, and A3, which belong to the superfamily of G-protein-coupled receptors (GPCRs). Evidence accumulated in the last 20 years indicates that GPCRs are often expressed as oligomeric complexes formed by a number of equal (homomers) or different (heteromers) receptors. This review presents the data showing the occurrence of heteromers formed by A1 and A2A, A2A and A2B, and A2A and A3 receptors highlighting (i) their tetrameric structural arrangements, and (ii) the functional diversity that those heteromers provide to adenosinergic signaling.
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Affiliation(s)
- Rafael Franco
- Molecular Neurobiology Laboratory, Department Biochemistry and Molecular Biomedicine, School of Biology, University of Barcelona, Diagonal 643, Catalonia, 08028, Barcelona, Spain.
- Centro de Investigación en Red, Enfermedades Neurodegenerativas (CiberNed), Instituto de Salud Carlos iii, Madrid, Spain.
| | - Arnau Cordomí
- Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, Campus Universitari, 08193, Bellaterra (Barcelona), Spain
| | - Claudia Llinas Del Torrent
- Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, Campus Universitari, 08193, Bellaterra (Barcelona), Spain
| | - Alejandro Lillo
- Department of Biochemistry and Physiology, School of Pharmacy and Food Science, University of Barcelona, Catalonia, Barcelona, Spain
| | - Joan Serrano-Marín
- Molecular Neurobiology Laboratory, Department Biochemistry and Molecular Biomedicine, School of Biology, University of Barcelona, Diagonal 643, Catalonia, 08028, Barcelona, Spain
| | - Gemma Navarro
- Centro de Investigación en Red, Enfermedades Neurodegenerativas (CiberNed), Instituto de Salud Carlos iii, Madrid, Spain
- Department of Biochemistry and Physiology, School of Pharmacy and Food Science, University of Barcelona, Catalonia, Barcelona, Spain
| | - Leonardo Pardo
- Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, Campus Universitari, 08193, Bellaterra (Barcelona), Spain
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7
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Paprocki J, Biener G, Stoneman M, Raicu V. In-Cell Detection of Conformational Substates of a G Protein-Coupled Receptor Quaternary Structure: Modulation of Substate Probability by Cognate Ligand Binding. J Phys Chem B 2020; 124:10062-10076. [DOI: 10.1021/acs.jpcb.0c06081] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Joel Paprocki
- Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Gabriel Biener
- Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Michael Stoneman
- Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Valerică Raicu
- Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
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8
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Stoneman MR, Biener G, Raicu V. Proposal for simultaneous analysis of fluorescence intensity fluctuations and resonance energy transfer (IFRET) measurements. Methods Appl Fluoresc 2020; 8:035011. [DOI: 10.1088/2050-6120/ab9b68] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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9
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Li BB, Scott EY, Chamberlain MD, Duong BTV, Zhang S, Done SJ, Wheeler AR. Cell invasion in digital microfluidic microgel systems. SCIENCE ADVANCES 2020; 6:eaba9589. [PMID: 32832633 PMCID: PMC7439438 DOI: 10.1126/sciadv.aba9589] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Accepted: 06/02/2020] [Indexed: 05/27/2023]
Abstract
Microfluidic methods for studying cell invasion can be subdivided into those in which cells invade into free space and those in which cells invade into hydrogels. The former techniques allow straightforward extraction of subpopulations of cells for RNA sequencing, while the latter preserve key aspects of cell interactions with the extracellular matrix (ECM). Here, we introduce "cell invasion in digital microfluidic microgel systems" (CIMMS), which bridges the gap between them, allowing the stratification of cells on the basis of their invasiveness into hydrogels for RNA sequencing. In initial studies with a breast cancer model, 244 genes were found to be differentially expressed between invading and noninvading cells, including genes correlating with ECM-remodeling, chemokine/cytokine receptors, and G protein transducers. These results suggest that CIMMS will be a valuable tool for probing metastasis as well as the many physiological processes that rely on invasion, such as tissue development, repair, and protection.
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Affiliation(s)
- Bingyu B. Li
- Institute for Biomaterials and Biomedical Engineering, University of Toronto, 164 College St., Toronto, ON M5S 3G9, Canada
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College St., Toronto, ON M5S 3E1, Canada
| | - Erica Y. Scott
- Institute for Biomaterials and Biomedical Engineering, University of Toronto, 164 College St., Toronto, ON M5S 3G9, Canada
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College St., Toronto, ON M5S 3E1, Canada
- Department of Chemistry, University of Toronto, 80 St. George St., Toronto, ON M5S 3H6, Canada
| | - M. Dean Chamberlain
- Institute for Biomaterials and Biomedical Engineering, University of Toronto, 164 College St., Toronto, ON M5S 3G9, Canada
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College St., Toronto, ON M5S 3E1, Canada
- Department of Chemistry, University of Toronto, 80 St. George St., Toronto, ON M5S 3H6, Canada
| | - Bill T. V. Duong
- Institute for Biomaterials and Biomedical Engineering, University of Toronto, 164 College St., Toronto, ON M5S 3G9, Canada
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College St., Toronto, ON M5S 3E1, Canada
- Department of Chemistry, University of Toronto, 80 St. George St., Toronto, ON M5S 3H6, Canada
| | - Shuailong Zhang
- Institute for Biomaterials and Biomedical Engineering, University of Toronto, 164 College St., Toronto, ON M5S 3G9, Canada
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College St., Toronto, ON M5S 3E1, Canada
- Department of Chemistry, University of Toronto, 80 St. George St., Toronto, ON M5S 3H6, Canada
| | - Susan J. Done
- Laboratory Medicine Program, University Health Network, 200 Elizabeth St., Toronto, ON M5G 2C4, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A1, Canada
| | - Aaron R. Wheeler
- Institute for Biomaterials and Biomedical Engineering, University of Toronto, 164 College St., Toronto, ON M5S 3G9, Canada
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College St., Toronto, ON M5S 3E1, Canada
- Department of Chemistry, University of Toronto, 80 St. George St., Toronto, ON M5S 3H6, Canada
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10
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Raghuraman H, Chatterjee S, Das A. Site-Directed Fluorescence Approaches for Dynamic Structural Biology of Membrane Peptides and Proteins. Front Mol Biosci 2019; 6:96. [PMID: 31608290 PMCID: PMC6774292 DOI: 10.3389/fmolb.2019.00096] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 09/11/2019] [Indexed: 12/31/2022] Open
Abstract
Membrane proteins mediate a number of cellular functions and are associated with several diseases and also play a crucial role in pathogenicity. Due to their importance in cellular structure and function, they are important drug targets for ~60% of drugs available in the market. Despite the technological advancement and recent successful outcomes in determining the high-resolution structural snapshot of membrane proteins, the mechanistic details underlining the complex functionalities of membrane proteins is least understood. This is largely due to lack of structural dynamics information pertaining to different functional states of membrane proteins in a membrane environment. Fluorescence spectroscopy is a widely used technique in the analysis of functionally-relevant structure and dynamics of membrane protein. This review is focused on various site-directed fluorescence (SDFL) approaches and their applications to explore structural information, conformational changes, hydration dynamics, and lipid-protein interactions of important classes of membrane proteins that include the pore-forming peptides/proteins, ion channels/transporters and G-protein coupled receptors.
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Affiliation(s)
- H. Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, Kolkata, India
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11
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Park PSH. Rhodopsin Oligomerization and Aggregation. J Membr Biol 2019; 252:413-423. [PMID: 31286171 DOI: 10.1007/s00232-019-00078-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 06/25/2019] [Indexed: 12/18/2022]
Abstract
Rhodopsin is the light receptor in photoreceptor cells of the retina and a prototypical G protein-coupled receptor. Two types of quaternary structures can be adopted by rhodopsin. If rhodopsin folds and attains a proper tertiary structure, it can then form oligomers and nanodomains within the photoreceptor cell membrane. In contrast, if rhodopsin misfolds, it cannot progress through the biosynthetic pathway and instead will form aggregates that can cause retinal degenerative disease. In this review, emerging views are highlighted on the supramolecular organization of rhodopsin within the membrane of photoreceptor cells and the aggregation of rhodopsin that can lead to retinal degeneration.
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Affiliation(s)
- Paul S-H Park
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH, 44106, USA.
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12
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Qu W, Mai Z, Zhang C, Du M, Yang F, Chen T. Time-lapse FRET analysis reveals the ability of Bax dimer to trigger mitochondrial outer membrane permeabilization. Biochem Biophys Res Commun 2019; 514:881-887. [PMID: 31084935 DOI: 10.1016/j.bbrc.2019.05.039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 05/04/2019] [Indexed: 10/26/2022]
Abstract
Bax oligomerization is essential for triggering mitochondrial outer membrane permeabilization (MOMP) in many apoptotic programs. However, it is controversial whether Bax dimer is sufficient to trigger MOMP. In this report, multiple Gaussian function-based FRET analysis (Multi-Gaussian FRET analysis) was used to dissect the dimerization and then tetramerization of Bax in relation to MOMP. Multi-Gaussian FRET analysis on the time-lapse FRET images of single living cells co-expressing CFP-Bax and YFP-Bax revealed that formation of mitochondrial Bax homodimers preceded MOMP within 3 min and Bax dimer transformed into tetramer within 6 min concomitantly with complete MOMP within 10 min, providing direct evidence in support of the sufficient ability of Bax dimers to trigger MOMP at least in natural cells.
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Affiliation(s)
- Wenfeng Qu
- MOE Key Laboratory of Laser Life Science & College of Biophotonics, South China Normal University, Guangzhou, 510631, China
| | - Zihao Mai
- MOE Key Laboratory of Laser Life Science & College of Biophotonics, South China Normal University, Guangzhou, 510631, China
| | - Chenshuang Zhang
- MOE Key Laboratory of Laser Life Science & College of Biophotonics, South China Normal University, Guangzhou, 510631, China
| | - Mengyan Du
- MOE Key Laboratory of Laser Life Science & College of Biophotonics, South China Normal University, Guangzhou, 510631, China
| | - Fangfang Yang
- MOE Key Laboratory of Laser Life Science & College of Biophotonics, South China Normal University, Guangzhou, 510631, China
| | - Tongsheng Chen
- MOE Key Laboratory of Laser Life Science & College of Biophotonics, South China Normal University, Guangzhou, 510631, China.
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13
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Qu W, Du M, Yang F, Mai Z, Zhang C, Lin F, Ma Y, Chen T. Gaussian FRET two-hybrid assays for determining the stoichiometry of hetero-oligomeric complexes in single living cells. Biochem Biophys Res Commun 2019; 512:492-497. [DOI: 10.1016/j.bbrc.2019.03.089] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Accepted: 03/15/2019] [Indexed: 10/27/2022]
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14
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Pin JP, Kniazeff J, Prézeau L, Liu JF, Rondard P. GPCR interaction as a possible way for allosteric control between receptors. Mol Cell Endocrinol 2019; 486:89-95. [PMID: 30849406 DOI: 10.1016/j.mce.2019.02.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 02/19/2019] [Accepted: 02/20/2019] [Indexed: 12/17/2022]
Abstract
For more than twenty years now, GPCR dimers and larger oligomers have been the subject of intense debates. Evidence for a role of such complexes in receptor trafficking to and from the plasma membrane have been provided. However, one main issue is of course to determine whether or not such a phenomenon can be responsible for an allosteric and reciprocal control (allosteric control) of the subunits. Such a possibility would indeed add to the possible ways a cell integrates various signals targeting GPCRs. Among the large GPCR family, the class C receptors that include mGlu and GABAB receptors, represent excellent models to examine such a possibility as they are mandatory dimers. In the present review, we will report on the observed allosteric interaction between the subunits of class C GPCRs, both mGluRs and GABABRs, and on the structural bases of these interactions. We will then discuss these findings for other GPCR types such as the rhodopsin-like class A receptors. We will show that many of the observations made with class C receptors have also been reported with class A receptors, suggesting that the mechanisms involved in the allosteric control between subunits in GPCR dimers may not be unique to class C GPCRs.
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Affiliation(s)
- Jean-Philippe Pin
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France.
| | - Julie Kniazeff
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Laurent Prézeau
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Jiang-Feng Liu
- Cellular Signaling Laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Philippe Rondard
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
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15
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Fluorescence-based approaches for monitoring membrane receptor oligomerization. J Biosci 2018. [DOI: 10.1007/s12038-018-9762-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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16
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Marsango S, Ward RJ, Alvarez-Curto E, Milligan G. Muscarinic receptor oligomerization. Neuropharmacology 2018; 136:401-410. [PMID: 29146505 PMCID: PMC6078712 DOI: 10.1016/j.neuropharm.2017.11.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 11/01/2017] [Accepted: 11/13/2017] [Indexed: 12/30/2022]
Abstract
G protein-coupled receptors (GPCRs) have been classically described as monomeric entities that function by binding in a 1:1 stoichiometric ratio to both ligand and downstream signalling proteins. However, in recent years, a growing number of studies has supported the hypothesis that these receptors can interact to form dimers and higher order oligomers although the molecular basis for these interactions, the overall quaternary arrangements and the functional importance of GPCR oligomerization remain topics of intense speculation. Muscarinic acetylcholine receptors belong to class A of the GPCR family. Each muscarinic receptor subtype has its own particular distribution throughout the central and peripheral nervous systems. In the central nervous system, muscarinic receptors regulate several sensory, cognitive, and motor functions while, in the peripheral nervous system, they are involved in the regulation of heart rate, stimulation of glandular secretion and smooth muscle contraction. Muscarinic acetylcholine receptors have long been used as a model for the study of GPCR structure and function and to address aspects of GPCR dimerization using a broad range of approaches. In this review, the prevailing knowledge regarding the quaternary arrangement for the various muscarinic acetylcholine receptors has been summarized by discussing work ranging from initial results obtained using more traditional biochemical approaches to those generated with more modern biophysical techniques. This article is part of the Special Issue entitled 'Neuropharmacology on Muscarinic Receptors'.
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Affiliation(s)
- Sara Marsango
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, UK.
| | - Richard J Ward
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, UK.
| | - Elisa Alvarez-Curto
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
| | - Graeme Milligan
- Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
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17
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Raicu V. Extraction of information on macromolecular interactions from fluorescence micro-spectroscopy measurements in the presence and absence of FRET. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2018; 199:340-348. [PMID: 29631099 DOI: 10.1016/j.saa.2018.03.075] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 03/26/2018] [Indexed: 06/08/2023]
Abstract
Investigations of static or dynamic interactions between proteins or other biological macromolecules in living cells often rely on the use of fluorescent tags with two different colors in conjunction with adequate theoretical descriptions of Förster Resonance Energy Transfer (FRET) and molecular-level micro-spectroscopic technology. One such method based on these general principles is FRET spectrometry, which allows determination of the quaternary structure of biomolecules from cell-level images of the distributions, or spectra of occurrence frequency of FRET efficiencies. Subsequent refinements allowed combining FRET frequency spectra with molecular concentration information, thereby providing the proportion of molecular complexes with various quaternary structures as well as their binding/dissociation energies. In this paper, we build on the mathematical principles underlying FRET spectrometry to propose two new spectrometric methods, which have distinct advantages compared to other methods. One of these methods relies on statistical analysis of color mixing in subpopulations of fluorescently tagged molecules to probe molecular association stoichiometry, while the other exploits the color shift induced by FRET to also derive geometric information in addition to stoichiometry. The appeal of the first method stems from its sheer simplicity, while the strength of the second consists in its ability to provide structural information.
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Affiliation(s)
- Valerică Raicu
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, United States of America.
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18
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Corby MJ, Stoneman MR, Biener G, Paprocki JD, Kolli R, Raicu V, Frick DN. Quantitative microspectroscopic imaging reveals viral and cellular RNA helicase interactions in live cells. J Biol Chem 2017; 292:11165-11177. [PMID: 28483922 DOI: 10.1074/jbc.m117.777045] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 04/29/2017] [Indexed: 01/12/2023] Open
Abstract
Human cells detect RNA viruses through a set of helicases called RIG-I-like receptors (RLRs) that initiate the interferon response via a mitochondrial signaling complex. Many RNA viruses also encode helicases, which are sometimes covalently linked to proteases that cleave signaling proteins. One unresolved question is how RLRs interact with each other and with viral proteins in cells. This study examined the interactions among the hepatitis C virus (HCV) helicase and RLR helicases in live cells with quantitative microspectroscopic imaging (Q-MSI), a technique that determines FRET efficiency and subcellular donor and acceptor concentrations. HEK293T cells were transfected with various vector combinations to express cyan fluorescent protein (CFP) or YFP fused to either biologically active HCV helicase or one RLR (i.e. RIG-I, MDA5, or LGP2), expressed in the presence or absence of polyinosinic-polycytidylic acid (poly(I:C)), which elicits RLR accumulation at mitochondria. Q-MSI confirmed previously reported RLR interactions and revealed an interaction between HCV helicase and LGP2. Mitochondria in CFP-RIG-I:YFP-RIG-I cells, CFP-MDA5:YFP-MDA5 cells, and CFP-MDA5:YFP-LGP2 cells had higher FRET efficiencies in the presence of poly(I:C), indicating that RNA causes these proteins to accumulate at mitochondria in higher-order complexes than those formed in the absence of poly(I:C). However, mitochondria in CFP-LGP2:YFP-LGP2 cells had lower FRET signal in the presence of poly(I:C), suggesting that LGP2 oligomers disperse so that LGP2 can bind MDA5. Data support a new model where an LGP2-MDA5 oligomer shuttles NS3 to the mitochondria to block antiviral signaling.
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Affiliation(s)
- M J Corby
- From the Departments of Chemistry and Biochemistry
| | | | | | | | - Rajesh Kolli
- From the Departments of Chemistry and Biochemistry
| | - Valerica Raicu
- Physics, and .,Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201
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19
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Methods used to study the oligomeric structure of G-protein-coupled receptors. Biosci Rep 2017; 37:BSR20160547. [PMID: 28062602 PMCID: PMC5398257 DOI: 10.1042/bsr20160547] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 01/05/2017] [Accepted: 01/06/2017] [Indexed: 02/02/2023] Open
Abstract
G-protein-coupled receptors (GPCRs), which constitute the largest family of cell surface receptors, were originally thought to function as monomers, but are now recognized as being able to act in a wide range of oligomeric states and indeed, it is known that the oligomerization state of a GPCR can modulate its pharmacology and function. A number of experimental techniques have been devised to study GPCR oligomerization including those based upon traditional biochemistry such as blue-native PAGE (BN-PAGE), co-immunoprecipitation (Co-IP) and protein-fragment complementation assays (PCAs), those based upon resonance energy transfer, FRET, time-resolved FRET (TR-FRET), FRET spectrometry and bioluminescence resonance energy transfer (BRET). Those based upon microscopy such as FRAP, total internal reflection fluorescence microscopy (TIRFM), spatial intensity distribution analysis (SpIDA) and various single molecule imaging techniques. Finally with the solution of a growing number of crystal structures, X-ray crystallography must be acknowledged as an important source of discovery in this field. A different, but in many ways complementary approach to the use of more traditional experimental techniques, are those involving computational methods that possess obvious merit in the study of the dynamics of oligomer formation and function. Here, we summarize the latest developments that have been made in the methods used to study GPCR oligomerization and give an overview of their application.
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20
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King C, Raicu V, Hristova K. Understanding the FRET Signatures of Interacting Membrane Proteins. J Biol Chem 2017; 292:5291-5310. [PMID: 28188294 DOI: 10.1074/jbc.m116.764282] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 02/07/2017] [Indexed: 12/30/2022] Open
Abstract
FRET is an indispensable experimental tool for studying membrane proteins. Currently, two models are available for researchers to determine the oligomerization state of membrane proteins in a static quenching FRET experiment: the model of Veatch and Stryer, derived in 1977, and the kinetic theory-based model for intraoligomeric FRET, derived in 2007. Because of confinement in two dimensions, a substantial amount of FRET is generated by energy transfer between fluorophores located in separate oligomers in the two-dimensional bilayer. This interoligomeric FRET (also known as stochastic, bystander, or proximity FRET) is not accounted for in either model. Here, we use the kinetic theory formalism to describe the dependence of the FRET efficiency measured in an experiment (i.e. the "total apparent FRET efficiency") on the interoligomeric FRET due to random proximity within the bilayer and the intraoligomeric FRET resulting from protein-protein interactions. We find that data analysis with both models without consideration of the proximity FRET leads to incorrect conclusions about the oligomeric state of the protein. We show that knowledge of the total surface densities of fluorophore-labeled membrane proteins is essential for correctly interpreting the measured total apparent FRET efficiency. We also find that bulk, two-color, static quenching FRET experiments are best suited for the study of monomeric, dimerizing, or dimeric proteins but have limitations in discerning the order of larger oligomers. The theory and methodology described in this work will allow researchers to extract meaningful parameters from static quenching FRET measurements in biological membranes.
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Affiliation(s)
- Christopher King
- the Program in Molecular Biophysics, Johns Hopkins University, Baltimore, Maryland 21218 and
| | - Valerica Raicu
- the Department of Physics, University of Wisconsin, Milwaukee, Wisconsin 53211
| | - Kalina Hristova
- the Program in Molecular Biophysics, Johns Hopkins University, Baltimore, Maryland 21218 and .,From the Department of Materials Science and Engineering and
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21
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Cevheroğlu O, Kumaş G, Hauser M, Becker JM, Son ÇD. The yeast Ste2p G protein-coupled receptor dimerizes on the cell plasma membrane. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:698-711. [PMID: 28073700 DOI: 10.1016/j.bbamem.2017.01.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 12/23/2016] [Accepted: 01/05/2017] [Indexed: 12/17/2022]
Abstract
Dimerization of G protein-coupled receptors (GPCR) may play an important role in maturation, internalization, signaling and/or pharmacology of these receptors. However, the location where dimerization occurs is still under debate. In our study, variants of Ste2p, a yeast mating pheromone GPCR, were tagged with split EGFP (enhanced green fluorescent protein) fragments inserted between transmembrane domain seven and the C-terminus or appended to the C-terminus. Bimolecular Fluorescence Complementation (BiFC) assay was used to determine where receptor dimerization occurred during protein trafficking by monitoring generation of EGFP fluorescence, which occurred upon GPCR dimerization. Our results suggest that these tagged receptors traffic to the membrane as monomers, undergo dimerization or higher ordered oligomerization predominantly on the plasma membrane, and are internalized as dimers/oligomers. This study is the first to provide direct in vivo visualization of GPCR dimerization/oligomerization, during trafficking to and from the plasma membrane.
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Affiliation(s)
- Orkun Cevheroğlu
- Department of Biological Sciences, Middle East Technical University, Universiteler Mah. Dumlupinar Blv. No: 1, 06800 Cankaya, Ankara, Turkey; Department of Microbiology, University of Tennessee, Knoxville, TN 37996, United States
| | - Gözde Kumaş
- Department of Biological Sciences, Middle East Technical University, Universiteler Mah. Dumlupinar Blv. No: 1, 06800 Cankaya, Ankara, Turkey
| | - Melinda Hauser
- Department of Microbiology, University of Tennessee, Knoxville, TN 37996, United States
| | - Jeffrey M Becker
- Department of Microbiology, University of Tennessee, Knoxville, TN 37996, United States
| | - Çağdaş D Son
- Department of Biological Sciences, Middle East Technical University, Universiteler Mah. Dumlupinar Blv. No: 1, 06800 Cankaya, Ankara, Turkey.
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22
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Stoneman MR, Paprocki JD, Biener G, Yokoi K, Shevade A, Kuchin S, Raicu V. Quaternary structure of the yeast pheromone receptor Ste2 in living cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1859:1456-1464. [PMID: 27993568 DOI: 10.1016/j.bbamem.2016.12.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 12/05/2016] [Accepted: 12/08/2016] [Indexed: 12/15/2022]
Abstract
Transmembrane proteins known as G protein-coupled receptors (GPCRs) have been shown to form functional homo- or hetero-oligomeric complexes, although agreement has been slow to emerge on whether homo-oligomerization plays functional roles. Here we introduce a platform to determine the identity and abundance of differing quaternary structures formed by GPCRs in living cells following changes in environmental conditions, such as changes in concentrations. The method capitalizes on the intrinsic capability of FRET spectrometry to extract oligomer geometrical information from distributions of FRET efficiencies (or FRET spectrograms) determined from pixel-level imaging of cells, combined with the ability of the statistical ensemble approaches to FRET to probe the proportion of different quaternary structures (such as dimers, rhombus or parallelogram shaped tetramers, etc.) from averages over entire cells. Our approach revealed that the yeast pheromone receptor Ste2 forms predominantly tetramers at average expression levels of 2 to 25 molecules per pixel (2.8·10-6 to 3.5·10-5molecules/nm2), and a mixture of tetramers and octamers at expression levels of 25-100 molecules per pixel (3.5·10-5 to 1.4·10-4molecules/nm2). Ste2 is a class D GPCR found in the yeast Saccharomyces cerevisiae of the mating type a, and binds the pheromone α-factor secreted by cells of the mating type α. Such investigations may inform development of antifungal therapies targeting oligomers of pheromone receptors. The proposed FRET imaging platform may be used to determine the quaternary structure sub-states and stoichiometry of any GPCR and, indeed, any membrane protein in living cells. This article is part of a Special Issue entitled: Interactions between membrane receptors in cellular membranes edited by Kalina Hristova.
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Affiliation(s)
- Michael R Stoneman
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI, USA.
| | - Joel D Paprocki
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Gabriel Biener
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Koki Yokoi
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Aishwarya Shevade
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Sergei Kuchin
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Valerică Raicu
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI, USA; Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, USA.
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23
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Greife A, Felekyan S, Ma Q, Gertzen CGW, Spomer L, Dimura M, Peulen TO, Wöhler C, Häussinger D, Gohlke H, Keitel V, Seidel CAM. Structural assemblies of the di- and oligomeric G-protein coupled receptor TGR5 in live cells: an MFIS-FRET and integrative modelling study. Sci Rep 2016; 6:36792. [PMID: 27833095 PMCID: PMC5105069 DOI: 10.1038/srep36792] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 10/21/2016] [Indexed: 12/15/2022] Open
Abstract
TGR5 is the first identified bile acid-sensing G-protein coupled receptor, which has emerged as a potential therapeutic target for metabolic disorders. So far, structural and multimerization properties are largely unknown for TGR5. We used a combined strategy applying cellular biology, Multiparameter Image Fluorescence Spectroscopy (MFIS) for quantitative FRET analysis, and integrative modelling to obtain structural information about dimerization and higher-order oligomerization assemblies of TGR5 wildtype (wt) and Y111 variants fused to fluorescent proteins. Residue 111 is located in transmembrane helix 3 within the highly conserved ERY motif. Co-immunoprecipitation and MFIS-FRET measurements with gradually increasing acceptor to donor concentrations showed that TGR5 wt forms higher-order oligomers, a process disrupted in TGR5 Y111A variants. From the concentration dependence of the MFIS-FRET data we conclude that higher-order oligomers - likely with a tetramer organization - are formed from dimers, the smallest unit suggested for TGR5 Y111A variants. Higher-order oligomers likely have a linear arrangement with interaction sites involving transmembrane helix 1 and helix 8 as well as transmembrane helix 5. The latter interaction is suggested to be disrupted by the Y111A mutation. The proposed model of TGR5 oligomer assembly broadens our view of possible oligomer patterns and affinities of class A GPCRs.
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Affiliation(s)
- Annemarie Greife
- Chair for Molecular Physical Chemistry, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Suren Felekyan
- Chair for Molecular Physical Chemistry, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Qijun Ma
- Chair for Molecular Physical Chemistry, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Christoph G W Gertzen
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Lina Spomer
- Clinic for Gastroenterology, Hepatology and Infectious Diseases, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Mykola Dimura
- Chair for Molecular Physical Chemistry, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Thomas O Peulen
- Chair for Molecular Physical Chemistry, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Christina Wöhler
- Clinic for Gastroenterology, Hepatology and Infectious Diseases, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Dieter Häussinger
- Clinic for Gastroenterology, Hepatology and Infectious Diseases, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Holger Gohlke
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Verena Keitel
- Clinic for Gastroenterology, Hepatology and Infectious Diseases, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Claus A M Seidel
- Chair for Molecular Physical Chemistry, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
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24
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Quaternary structures of opsin in live cells revealed by FRET spectrometry. Biochem J 2016; 473:3819-3836. [PMID: 27623775 DOI: 10.1042/bcj20160422] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 09/12/2016] [Indexed: 02/06/2023]
Abstract
Rhodopsin is a prototypical G-protein-coupled receptor (GPCR) that initiates phototransduction in the retina. The receptor consists of the apoprotein opsin covalently linked to the inverse agonist 11-cis retinal. Rhodopsin and opsin have been shown to form oligomers within the outer segment disc membranes of rod photoreceptor cells. However, the physiological relevance of the observed oligomers has been questioned since observations were made on samples prepared from the retina at low temperatures. To investigate the oligomeric status of opsin in live cells at body temperatures, we utilized a novel approach called Förster resonance energy transfer spectrometry, which previously has allowed the determination of the stoichiometry and geometry (i.e. quaternary structure) of various GPCRs. In the current study, we have extended the method to additionally determine whether or not a mixture of oligomeric forms of opsin exists and in what proportion. The application of this improved method revealed that opsin expressed in live Chinese hamster ovary (CHO) cells at 37°C exists as oligomers of various sizes. At lower concentrations, opsin existed in an equilibrium of dimers and tetramers. The tetramers were in the shape of a near-rhombus. At higher concentrations of the receptor, higher-order oligomers began to form. Thus, a mixture of different oligomeric forms of opsin is present in the membrane of live CHO cells and oligomerization occurs in a concentration-dependent manner. The general principles underlying the concentration-dependent oligomerization of opsin may be universal and apply to other GPCRs as well.
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25
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Shivnaraine RV, Kelly B, Sankar KS, Redka DS, Han YR, Huang F, Elmslie G, Pinto D, Li Y, Rocheleau JV, Gradinaru CC, Ellis J, Wells JW. Allosteric modulation in monomers and oligomers of a G protein-coupled receptor. eLife 2016; 5. [PMID: 27151542 PMCID: PMC4900804 DOI: 10.7554/elife.11685] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 04/30/2016] [Indexed: 12/03/2022] Open
Abstract
The M2 muscarinic receptor is the prototypic model of allostery in GPCRs, yet the molecular and the supramolecular determinants of such effects are unknown. Monomers and oligomers of the M2 muscarinic receptor therefore have been compared to identify those allosteric properties that are gained in oligomers. Allosteric interactions were monitored by means of a FRET-based sensor of conformation at the allosteric site and in pharmacological assays involving mutants engineered to preclude intramolecular effects. Electrostatic, steric, and conformational determinants of allostery at the atomic level were examined in molecular dynamics simulations. Allosteric effects in monomers were exclusively negative and derived primarily from intramolecular electrostatic repulsion between the allosteric and orthosteric ligands. Allosteric effects in oligomers could be positive or negative, depending upon the allosteric-orthosteric pair, and they arose from interactions within and between the constituent protomers. The complex behavior of oligomers is characteristic of muscarinic receptors in myocardial preparations. DOI:http://dx.doi.org/10.7554/eLife.11685.001 Proteins called G protein-coupled receptors (GPCRs) are found on the surface of cells throughout the body. Hormones or other signal molecules – collectively known as ligands – from outside the cell can bind to the receptors to activate them. This causes a change in the structure of the receptor, which triggers a signal inside the cell to alter the cell’s behavior. GPCRs are known to form clusters of two or more receptor units, but it is not known if these clusters have unique properties or what role they play in cells. Many drugs can bind to GPCRs and most of them block the activity of the receptors by taking the place of the natural ligand. Another way to alter the activity of a GPCR is with so-called 'allosteric' drugs. These bind to different sites on the receptor than the natural ligands do and can inhibit or enhance binding of the ligands by altering the shape of the receptor. Shivnaraine et al. investigated how a type of GPCR called muscarinic cholinergic receptors interact within clusters. This involved developing a method to track the receptor in mammalian cells using a fluorescent sensor that detects changes in the allosteric site. The experiments show that two or more GPCRs need to interact for the receptors to respond to allosteric drugs in a manner that reflects the normal effect of the drugs on the body. This result is unexpected in light of the assumption that individual receptor molecules act independently. Shivnaraine et al.’s findings indicate that the clusters may play a role in the normal behavior of GPCRs in cells. A future challenge is to understand exactly how the GPCRs interact with each other. DOI:http://dx.doi.org/10.7554/eLife.11685.002
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Affiliation(s)
- Rabindra V Shivnaraine
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Canada
| | - Brendan Kelly
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Canada
| | | | - Dar'ya S Redka
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Canada
| | - Yi Rang Han
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Canada
| | - Fei Huang
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Canada
| | - Gwendolynne Elmslie
- Departments of Psychiatry and Pharmacology, Hershey Medical Center, Hershey, United States
| | - Daniel Pinto
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Canada
| | - Yuchong Li
- Department of Physics, University of Toronto, Toronto, Canada
| | | | | | - John Ellis
- Departments of Psychiatry and Pharmacology, Hershey Medical Center, Hershey, United States
| | - James W Wells
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Canada
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26
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Abstract
Protease signaling in cells elicits multiple physiologically important responses via protease-activated receptors (PARs). There are 4 members of this family of G-protein-coupled receptors (PAR1-4). PARs are activated by proteolysis of the N terminus to reveal a tethered ligand. The rate-limiting step of PAR signaling is determined by the efficiency of proteolysis of the N terminus, which is regulated by allosteric binding sites, cofactors, membrane localization, and receptor dimerization. This ultimately controls the initiation of PAR signaling. In addition, these factors also control the cellular response by directing signaling toward G-protein or β-arrestin pathways. PAR1 signaling on endothelial cells is controlled by the activating protease and heterodimerization with PAR2 or PAR3. As a consequence, the genetic and epigenetic control of PARs and their cofactors in physiologic and pathophysiologic conditions have the potential to influence cellular behavior. Recent studies have uncovered polymorphisms that result in PAR4 sequence variants with altered reactivity that interact to influence platelet response. This further demonstrates how interactions within the plasma membrane can control the physiological output. Understanding the structural rearrangement following PAR activation and how PARs are allosterically controlled within the plasma membrane will determine how best to target this family of receptors therapeutically. The purpose of this article is to review how signaling from PARs is influenced by alternative cleavage sites and the physical interactions within the membrane. Going forward, it will be important to relate the altered signaling to the molecular arrangement of PARs in the cell membrane and to determine how these may be influenced genetically.
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Pediani JD, Ward RJ, Godin AG, Marsango S, Milligan G. Dynamic Regulation of Quaternary Organization of the M1 Muscarinic Receptor by Subtype-selective Antagonist Drugs. J Biol Chem 2016; 291:13132-46. [PMID: 27080256 PMCID: PMC4933229 DOI: 10.1074/jbc.m115.712562] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Indexed: 12/14/2022] Open
Abstract
Although rhodopsin-like G protein-coupled receptors can exist as both monomers and non-covalently associated dimers/oligomers, the steady-state proportion of each form and whether this is regulated by receptor ligands are unknown. Herein we address these topics for the M1 muscarinic acetylcholine receptor, a key molecular target for novel cognition enhancers, by using spatial intensity distribution analysis. This method can measure fluorescent particle concentration and assess oligomerization states of proteins within defined regions of living cells. Imaging and analysis of the basolateral surface of cells expressing some 50 molecules·μm−2 human muscarinic M1 receptor identified a ∼75:25 mixture of receptor monomers and dimers/oligomers. Both sustained and shorter term treatment with the selective M1 antagonist pirenzepine resulted in a large shift in the distribution of receptor species to favor the dimeric/oligomeric state. Although sustained treatment with pirenzepine also resulted in marked up-regulation of the receptor, simple mass action effects were not the basis for ligand-induced stabilization of receptor dimers/oligomers. The related antagonist telenzepine also produced stabilization and enrichment of the M1 receptor dimer population, but the receptor subtype non-selective antagonists atropine and N-methylscopolamine did not. In contrast, neither pirenzepine nor telenzepine altered the quaternary organization of the related M3 muscarinic receptor. These data provide unique insights into the selective capacity of receptor ligands to promote and/or stabilize receptor dimers/oligomers and demonstrate that the dynamics of ligand regulation of the quaternary organization of G protein-coupled receptors is markedly more complex than previously appreciated. This may have major implications for receptor function and behavior.
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Affiliation(s)
- John D Pediani
- From the Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom and
| | - Richard J Ward
- From the Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom and
| | - Antoine G Godin
- Institut d'Optique and CNRS, Laboratoire Photonique, Numérique et Nanosciences (LP2N) and Université de Bordeaux, LP2N, F-33405, UMR 5298, 33405 Talence Cedex, France
| | - Sara Marsango
- From the Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom and
| | - Graeme Milligan
- From the Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom and
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28
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Patowary S, Pisterzi LF, Biener G, Holz JD, Oliver JA, Wells JW, Raicu V. Experimental verification of the kinetic theory of FRET using optical microspectroscopy and obligate oligomers. Biophys J 2016; 108:1613-1622. [PMID: 25863053 DOI: 10.1016/j.bpj.2015.02.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 01/26/2015] [Accepted: 02/02/2015] [Indexed: 11/20/2022] Open
Abstract
Förster resonance energy transfer (FRET) is a nonradiative process for the transfer of energy from an optically excited donor molecule (D) to an acceptor molecule (A) in the ground state. The underlying theory predicting the dependence of the FRET efficiency on the sixth power of the distance between D and A has stood the test of time. In contrast, a comprehensive kinetic-based theory developed recently for FRET efficiencies among multiple donors and acceptors in multimeric arrays has waited for further testing. That theory has been tested in the work described in this article using linked fluorescent proteins located in the cytoplasm and at the plasma membrane of living cells. The cytoplasmic constructs were fused combinations of Cerulean as donor (D), Venus as acceptor (A), and a photo-insensitive molecule (Amber) as a nonfluorescent (N) place holder: namely, NDAN, NDNA, and ADNN duplexes, and the fully fluorescent quadruplex ADAA. The membrane-bound constructs were fused combinations of GFP2 as donor (D) and eYFP as acceptor (A): namely, two fluorescent duplexes (i.e., DA and AD) and a fluorescent triplex (ADA). According to the theory, the FRET efficiency of a multiplex such as ADAA or ADA can be predicted from that of analogs containing a single acceptor (e.g., NDAN, NDNA, and ADNN, or DA and AD, respectively). Relatively small but statistically significant differences were observed between the measured and predicted FRET efficiencies of the two multiplexes. While elucidation of the cause of this mismatch could be a worthy endeavor, the discrepancy does not appear to question the theoretical underpinnings of a large family of FRET-based methods for determining the stoichiometry and quaternary structure of complexes of macromolecules in living cells.
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Affiliation(s)
- Suparna Patowary
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin
| | | | - Gabriel Biener
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin
| | - Jessica D Holz
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin
| | - Julie A Oliver
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin
| | - James W Wells
- The Leslie L. Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Valerică Raicu
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin; Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin.
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29
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Scarselli M, Annibale P, McCormick PJ, Kolachalam S, Aringhieri S, Radenovic A, Corsini GU, Maggio R. Revealing G-protein-coupled receptor oligomerization at the single-molecule level through a nanoscopic lens: methods, dynamics and biological function. FEBS J 2015; 283:1197-217. [PMID: 26509747 DOI: 10.1111/febs.13577] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 09/29/2015] [Accepted: 10/23/2015] [Indexed: 11/30/2022]
Abstract
The introduction of super-resolution fluorescence microscopy has allowed the visualization of single proteins in their biological environment. Recently, these techniques have been applied to determine the organization of class A G-protein-coupled receptors (GPCRs), and to determine whether they exist as monomers, dimers and/or higher-order oligomers. On this subject, this review highlights recent evidence from photoactivated localization microscopy (PALM), which allows the visualization of single molecules in dense samples, and single-molecule tracking (SMT), which determines how GPCRs move and interact in living cells in the presence of different ligands. PALM has demonstrated that GPCR oligomerization depends on the receptor subtype, the cell type, the actin cytoskeleton, and other proteins. Conversely, SMT has revealed the transient dynamics of dimer formation, whereby receptors show a monomer-dimer equilibrium characterized by rapid association and dissociation. At steady state, depending on the subtype, approximately 30-50% of receptors are part of dimeric complexes. Notably, the existence of many GPCR dimers/oligomers is also supported by well-known techniques, such as resonance energy transfer methodologies, and by approaches that exploit fluorescence fluctuations, such as fluorescence correlation spectroscopy (FCS). Future research using single-molecule methods will deepen our knowledge related to the function and druggability of homo-oligomers and hetero-oligomers.
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Affiliation(s)
- Marco Scarselli
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy
| | - Paolo Annibale
- Laboratory of Nanoscale Biology, Institute of Bioengineering, School of Engineering, EPFL, Lausanne, Switzerland
| | | | - Shivakumar Kolachalam
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy
| | - Stefano Aringhieri
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy
| | - Aleksandra Radenovic
- Laboratory of Nanoscale Biology, Institute of Bioengineering, School of Engineering, EPFL, Lausanne, Switzerland
| | - Giovanni U Corsini
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy
| | - Roberto Maggio
- Biotechnological and Applied Clinical Sciences Department, University of L'Aquila, Italy
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30
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Yuan X, Khokhani D, Wu X, Yang F, Biener G, Koestler BJ, Raicu V, He C, Waters CM, Sundin GW, Tian F, Yang CH. Cross-talk between a regulatory small RNA, cyclic-di-GMP signalling and flagellar regulator FlhDC for virulence and bacterial behaviours. Environ Microbiol 2015; 17:4745-63. [PMID: 26462993 DOI: 10.1111/1462-2920.13029] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 08/14/2015] [Accepted: 08/15/2015] [Indexed: 12/01/2022]
Abstract
Dickeya dadantii is a globally dispersed phytopathogen which causes diseases on a wide range of host plants. This pathogen utilizes the type III secretion system (T3SS) to suppress host defense responses, and secretes pectate lyase (Pel) to degrade the plant cell wall. Although the regulatory small RNA (sRNA) RsmB, cyclic diguanylate monophosphate (c-di-GMP) and flagellar regulator have been reported to affect the regulation of these two virulence factors or multiple cell behaviours such as motility and biofilm formation, the linkage between these regulatory components that coordinate the cell behaviours remain unclear. Here, we revealed a sophisticated regulatory network that connects the sRNA, c-di-GMP signalling and flagellar master regulator FlhDC. We propose multi-tiered regulatory mechanisms that link the FlhDC to the T3SS through three distinct pathways including the FlhDC-FliA-YcgR3937 pathway; the FlhDC-EcpC-RpoN-HrpL pathway; and the FlhDC-rsmB-RsmA-HrpL pathway. Among these, EcpC is the most dominant factor for FlhDC to positively regulate T3SS expression.
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Affiliation(s)
- Xiaochen Yuan
- Department of Biological Sciences, University of Wisconsin, Milwaukee, WI, 53211, USA
| | - Devanshi Khokhani
- Department of Biological Sciences, University of Wisconsin, Milwaukee, WI, 53211, USA
| | - Xiaogang Wu
- Department of Biological Sciences, University of Wisconsin, Milwaukee, WI, 53211, USA
| | - Fenghuan Yang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Gabriel Biener
- Department of Physics, University of Wisconsin, Milwaukee, WI, 53211, USA
| | - Benjamin J Koestler
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, 48824, USA
| | - Valerica Raicu
- Department of Biological Sciences, University of Wisconsin, Milwaukee, WI, 53211, USA.,Department of Physics, University of Wisconsin, Milwaukee, WI, 53211, USA
| | - Chenyang He
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Christopher M Waters
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, 48824, USA
| | - George W Sundin
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI, 48824, USA
| | - Fang Tian
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Ching-Hong Yang
- Department of Biological Sciences, University of Wisconsin, Milwaukee, WI, 53211, USA
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31
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Singh DR, Cao Q, King C, Salotto M, Ahmed F, Zhou XY, Pasquale EB, Hristova K. Unliganded EphA3 dimerization promoted by the SAM domain. Biochem J 2015; 471:101-9. [PMID: 26232493 PMCID: PMC4692061 DOI: 10.1042/bj20150433] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 07/28/2015] [Accepted: 07/31/2015] [Indexed: 01/03/2023]
Abstract
The erythropoietin-producing hepatocellular carcinoma A3 (EphA3) receptor tyrosine kinase (RTK) regulates morphogenesis during development and is overexpressed and mutated in a variety of cancers. EphA3 activation is believed to follow a 'seeding mechanism' model, in which ligand binding to the monomeric receptor acts as a trigger for signal-productive receptor clustering. We study EphA3 lateral interactions on the surface of live cells and we demonstrate that EphA3 forms dimers in the absence of ligand binding. We further show that these dimers are stabilized by interactions involving the EphA3 sterile α-motif (SAM) domain. The discovery of unliganded EphA3 dimers challenges the current understanding of the chain of EphA3 activation events and suggests that EphA3 may follow the 'pre-formed dimer' model of activation known to be relevant for other receptor tyrosine kinases. The present work also establishes a new role for the SAM domain in promoting Eph receptor lateral interactions and signalling on the cell surface.
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Affiliation(s)
- Deo R Singh
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21212, U.S.A
| | - QingQing Cao
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21212, U.S.A
| | - Christopher King
- Program in Molecular Biophysics, Johns Hopkins University, Baltimore, MD 21212, U.S.A
| | - Matt Salotto
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21212, U.S.A
| | - Fozia Ahmed
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21212, U.S.A
| | - Xiang Yang Zhou
- Vaccine Center, The Wistar Institute, Philadelphia, PA 19104, U.S.A
| | - Elena B Pasquale
- Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, U.S.A
| | - Kalina Hristova
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21212, U.S.A. Program in Molecular Biophysics, Johns Hopkins University, Baltimore, MD 21212, U.S.A.
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32
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Biased signalling: the instinctive skill of the cell in the selection of appropriate signalling pathways. Biochem J 2015; 470:155-67. [DOI: 10.1042/bj20150358] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
GPCRs (G-protein-coupled receptors) are members of a family of proteins which are generally regarded as the largest group of therapeutic drug targets. Ligands of GPCRs do not usually activate all cellular signalling pathways linked to a particular seven-transmembrane receptor in a uniform manner. The fundamental idea behind this concept is that each ligand has its own ability, while interacting with the receptor, to activate different signalling pathways (or a particular set of signalling pathways) and it is this concept which is known as biased signalling. The importance of biased signalling is that it may selectively activate biological responses to favour therapeutically beneficial signalling pathways and to avoid adverse effects. There are two levels of biased signalling. First, bias can arise from the ability of GPCRs to couple to a subset of the available G-protein subtypes: Gαs, Gαq/11, Gαi/o or Gα12/13. These subtypes produce the diverse effects of GPCRs by targeting different effectors. Secondly, biased GPCRs may differentially activate G-proteins or β-arrestins. β-Arrestins are ubiquitously expressed and function to terminate or inhibit classic G-protein signalling and initiate distinct β-arrestin-mediated signalling processes. The interplay of G-protein and β-arrestin signalling largely determines the cellular consequences of the administration of GPCR-targeted drugs. In the present review, we highlight the particular functionalities of biased signalling and discuss its biological effects subsequent to GPCR activation. We consider that biased signalling is potentially allowing a choice between signalling through ‘beneficial’ pathways and the avoidance of ‘harmful’ ones.
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33
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Vischer HF, Castro M, Pin JP. G Protein-Coupled Receptor Multimers: A Question Still Open Despite the Use of Novel Approaches. Mol Pharmacol 2015; 88:561-71. [PMID: 26138074 DOI: 10.1124/mol.115.099440] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Accepted: 07/02/2015] [Indexed: 12/11/2022] Open
Abstract
Heteromerization of G protein-coupled receptors (GPCRs) can significantly change the functional properties of involved receptors. Various biochemical and biophysical methodologies have been developed in the last two decades to identify and functionally evaluate GPCR heteromers in heterologous cells, with recent approaches focusing on GPCR complex stoichiometry and stability. Yet validation of these observations in native tissues is still lagging behind for the majority of GPCR heteromers. Remarkably, recent studies, particularly some involving advanced fluorescence microscopy techniques, are contributing to our current knowledge of aspects that were not well known until now, such as GPCR complex stoichiometry and stability. In parallel, a growing effort is being applied to move the field forward into native systems. This short review will highlight recent developments to study the stoichiometry and stability of GPCR complexes and methodologies to detect native GPCR dimers.
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Affiliation(s)
- Henry F Vischer
- Amsterdam Institute for Molecules, Medicines and Systems, Division of Medicinal Chemistry, Faculty of Sciences, VU University Amsterdam, Amsterdam, The Netherlands (H.F.V.); Molecular Pharmacology Laboratory, Biofarma Research Group (GI-1685), University of Santiago de Compostela, Center for Research in Molecular Medicine and Chronic Diseases, Santiago de Compostela, Spain (M.C.); and Centre National de la Recherche Scientifique, Institut de Génomique Fonctionnelle, Université de Montpellier, Montpellier, France (J.-P.P.)
| | - Marián Castro
- Amsterdam Institute for Molecules, Medicines and Systems, Division of Medicinal Chemistry, Faculty of Sciences, VU University Amsterdam, Amsterdam, The Netherlands (H.F.V.); Molecular Pharmacology Laboratory, Biofarma Research Group (GI-1685), University of Santiago de Compostela, Center for Research in Molecular Medicine and Chronic Diseases, Santiago de Compostela, Spain (M.C.); and Centre National de la Recherche Scientifique, Institut de Génomique Fonctionnelle, Université de Montpellier, Montpellier, France (J.-P.P.)
| | - Jean-Philippe Pin
- Amsterdam Institute for Molecules, Medicines and Systems, Division of Medicinal Chemistry, Faculty of Sciences, VU University Amsterdam, Amsterdam, The Netherlands (H.F.V.); Molecular Pharmacology Laboratory, Biofarma Research Group (GI-1685), University of Santiago de Compostela, Center for Research in Molecular Medicine and Chronic Diseases, Santiago de Compostela, Spain (M.C.); and Centre National de la Recherche Scientifique, Institut de Génomique Fonctionnelle, Université de Montpellier, Montpellier, France (J.-P.P.)
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34
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Marsango S, Caltabiano G, Pou C, Varela Liste MJ, Milligan G. Analysis of Human Dopamine D3 Receptor Quaternary Structure. J Biol Chem 2015; 290:15146-62. [PMID: 25931118 PMCID: PMC4463457 DOI: 10.1074/jbc.m114.630681] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 04/23/2015] [Indexed: 01/11/2023] Open
Abstract
The dopamine D3 receptor is a class A, rhodopsin-like G protein-coupled receptor that can form dimers and/or higher order oligomers. However, the molecular basis for production of these complexes is not well defined. Using combinations of molecular modeling, site-directed mutagenesis, and homogenous time-resolved FRET, the interfaces that allow dopamine D3 receptor monomers to interact were defined and used to describe likely quaternary arrangements of the receptor. These were then compared with published crystal structures of dimeric β1-adrenoreceptor, μ-opioid, and CXCR4 receptors. The data indicate important contributions of residues from within each of transmembrane domains I, II, IV, V, VI, and VII as well as the intracellular helix VIII in the formation of D3-D3 receptor interfaces within homo-oligomers and are consistent with the D3 receptor adopting a β1-adrenoreceptor-like quaternary arrangement. Specifically, results suggest that D3 protomers can interact with each other via at least two distinct interfaces: the first one comprising residues from transmembrane domains I and II along with those from helix VIII and a second one involving transmembrane domains IV and V. Moreover, rather than existing only as distinct dimeric species, the results are consistent with the D3 receptor also assuming a quaternary structure in which two transmembrane domain I-II-helix VIII dimers interact to form a "rhombic" tetramer via an interface involving residues from transmembrane domains VI and VII. In addition, the results also provide insights into the potential contribution of molecules of cholesterol to the overall organization and potential stability of the D3 receptor and possibly other GPCR quaternary structures.
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Affiliation(s)
- Sara Marsango
- From the Molecular Pharmacology Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom and
| | - Gianluigi Caltabiano
- Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Chantevy Pou
- From the Molecular Pharmacology Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom and
| | - María José Varela Liste
- From the Molecular Pharmacology Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom and
| | - Graeme Milligan
- From the Molecular Pharmacology Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom and
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35
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Duc NM, Kim HR, Chung KY. Structural mechanism of G protein activation by G protein-coupled receptor. Eur J Pharmacol 2015; 763:214-22. [PMID: 25981300 DOI: 10.1016/j.ejphar.2015.05.016] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 03/03/2015] [Accepted: 05/11/2015] [Indexed: 12/17/2022]
Abstract
G protein-coupled receptors (GPCRs) are a family of membrane receptors that regulate physiology and pathology of various organs. Consequently, about 40% of drugs in the market targets GPCRs. Heterotrimeric G proteins are composed of α, β, and γ subunits, and act as the key downstream signaling molecules of GPCRs. The structural mechanism of G protein activation by GPCRs has been of a great interest, and a number of biochemical and biophysical studies have been performed since the late 80's. These studies investigated the interface between GPCR and G proteins and the structural mechanism of GPCR-induced G protein activation. Recently, arrestins are also reported to be important molecular switches in GPCR-mediated signal transduction, and the physiological output of arrestin-mediated signal transduction is different from that of G protein-mediated signal transduction. Understanding the structural mechanism of the activation of G proteins and arrestins would provide fundamental information for the downstream signaling-selective GPCR-targeting drug development. This review will discuss the structural mechanism of GPCR-induced G protein activation by comparing previous biochemical and biophysical studies.
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Affiliation(s)
- Nguyen Minh Duc
- School of Pharmacy, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon 440-746, Republic of Korea
| | - Hee Ryung Kim
- School of Pharmacy, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon 440-746, Republic of Korea
| | - Ka Young Chung
- School of Pharmacy, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon 440-746, Republic of Korea.
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36
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Aslanoglou D, Alvarez-Curto E, Marsango S, Milligan G. Distinct Agonist Regulation of Muscarinic Acetylcholine M2-M3 Heteromers and Their Corresponding Homomers. J Biol Chem 2015; 290:14785-96. [PMID: 25918156 PMCID: PMC4505543 DOI: 10.1074/jbc.m115.649079] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Indexed: 01/01/2023] Open
Abstract
Each subtype of the muscarinic receptor family of G protein-coupled receptors is activated by similar concentrations of the neurotransmitter acetylcholine or closely related synthetic analogs such as carbachol. However, pharmacological selectivity can be generated by the introduction of a pair of mutations to produce Receptor Activated Solely by Synthetic Ligand (RASSL) forms of muscarinic receptors. These display loss of potency for acetylcholine/carbachol alongside a concurrent gain in potency for the ligand clozapine N-oxide. Co-expression of a form of wild type human M2 and a RASSL variant of the human M3 receptor resulted in concurrent detection of each of M2-M2 and M3-M3 homomers alongside M2-M3 heteromers at the surface of stably transfected Flp-InTM T-RExTM 293 cells. In this setting occupancy of the receptors with a muscarinic antagonist was without detectable effect on any of the muscarinic oligomers. However, selective agonist occupancy of the M2 receptor resulted in enhanced M2-M2 homomer interactions but decreased M2-M3 heteromer interactions. By contrast, selective activation of the M3 RASSL receptor did not significantly alter either M3-M3 homomer or M2-M3 heteromer interactions. Selectively targeting closely related receptor oligomers may provide novel therapeutic opportunities.
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Affiliation(s)
- Despoina Aslanoglou
- From the Molecular Pharmacology Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Elisa Alvarez-Curto
- From the Molecular Pharmacology Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Sara Marsango
- From the Molecular Pharmacology Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Graeme Milligan
- From the Molecular Pharmacology Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
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37
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Ward RJ, Pediani JD, Godin AG, Milligan G. Regulation of oligomeric organization of the serotonin 5-hydroxytryptamine 2C (5-HT2C) receptor observed by spatial intensity distribution analysis. J Biol Chem 2015; 290:12844-57. [PMID: 25825490 PMCID: PMC4432300 DOI: 10.1074/jbc.m115.644724] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Indexed: 12/19/2022] Open
Abstract
The questions of whether G protein-coupled receptors exist as monomers, dimers, and/or oligomers and if these species interconvert in a ligand-dependent manner are among the most contentious current issues in biology. When employing spatial intensity distribution analysis to laser scanning confocal microscope images of cells stably expressing either a plasma membrane-associated form of monomeric enhanced green fluorescent protein (eGFP) or a tandem version of this fluorophore, the eGFP tandem was identified as a dimer. Similar studies on cells stably expressing an eGFP-tagged form of the epidermal growth factor receptor demonstrated that, although largely a monomer in the basal state, this receptor rapidly became predominantly dimeric upon the addition of its ligand epidermal growth factor. In cells induced to express an eGFP-tagged form of the serotonin 5-hydroxytryptamine 2C (5-HT2C) receptor, global analysis of construct quantal brightness was consistent with the predominant form of the receptor being dimeric. However, detailed spatial intensity distribution analysis demonstrated the presence of multiple forms ranging from monomers to higher-order oligomers. Furthermore, treatment with chemically distinct 5-HT2C receptor antagonists resulted in a time-dependent change in the quaternary organization to one in which there was a preponderance of receptor monomers. This antagonist-mediated effect was reversible, because washout of the ligand resulted in the regeneration of many of the oligomeric forms of the receptor.
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Affiliation(s)
- Richard J Ward
- From the Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - John D Pediani
- From the Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Antoine G Godin
- the University of Bordeaux, LP2N, UMR 5298, F-33405 Talence, France, and the Institut d'Optique Graduate School and CNRS, LP2N, UMR 5298, F-33405 Talence, France
| | - Graeme Milligan
- From the Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom,
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Liste MJV, Caltabiano G, Ward RJ, Alvarez-Curto E, Marsango S, Milligan G. The molecular basis of oligomeric organization of the human M3 muscarinic acetylcholine receptor. Mol Pharmacol 2015; 87:936-53. [PMID: 25769304 DOI: 10.1124/mol.114.096925] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 03/13/2015] [Indexed: 11/22/2022] Open
Abstract
G protein-coupled receptors, including the M3 muscarinic acetylcholine receptor, can form homo-oligomers. However, the basis of these interactions and the overall organizational structure of such oligomers are poorly understood. Combinations of site-directed mutagenesis and homogenous time-resolved fluorescence resonance energy transfer studies that assessed interactions between receptor protomers at the surface of transfected cells indicated important contributions of regions of transmembrane domains I, IV, V, VI, and VII as well as intracellular helix VIII to the overall organization. Molecular modeling studies based on both these results and an X-ray structure of the inactive state of the M3 receptor bound by the antagonist/inverse agonist tiotropium were then employed. The results could be accommodated fully by models in which a proportion of the cell surface M3 receptor population is a tetramer with rhombic, but not linear, orientation. This is consistent with previous studies based on spectrally resolved, multiphoton fluorescence resonance energy transfer. Modeling studies furthermore suggest an important role for molecules of cholesterol at the dimer + dimer interface of the tetramer, which is consistent with the presence of cholesterol at key locations in many G protein-coupled receptor crystal structures. Mutants that displayed disrupted quaternary organization were often poorly expressed and showed immature N-glycosylation. Sustained treatment of cells expressing such mutants with the muscarinic receptor inverse agonist atropine increased cellular levels and restored both cell surface delivery and quaternary organization to many of the mutants. These observations suggest that organization as a tetramer may occur before plasma membrane delivery and may be a key step in cellular quality control assessment.
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Affiliation(s)
- María José Varela Liste
- Molecular Pharmacology Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, Scotland, United Kingdom (M.J.V.L., G.C., R.J.W., E.A.-C., S.M., G.M.), and Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Spain (G.C.)
| | - Gianluigi Caltabiano
- Molecular Pharmacology Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, Scotland, United Kingdom (M.J.V.L., G.C., R.J.W., E.A.-C., S.M., G.M.), and Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Spain (G.C.)
| | - Richard J Ward
- Molecular Pharmacology Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, Scotland, United Kingdom (M.J.V.L., G.C., R.J.W., E.A.-C., S.M., G.M.), and Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Spain (G.C.)
| | - Elisa Alvarez-Curto
- Molecular Pharmacology Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, Scotland, United Kingdom (M.J.V.L., G.C., R.J.W., E.A.-C., S.M., G.M.), and Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Spain (G.C.)
| | - Sara Marsango
- Molecular Pharmacology Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, Scotland, United Kingdom (M.J.V.L., G.C., R.J.W., E.A.-C., S.M., G.M.), and Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Spain (G.C.)
| | - Graeme Milligan
- Molecular Pharmacology Group, Institute of Molecular, Cell, and Systems Biology, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, Scotland, United Kingdom (M.J.V.L., G.C., R.J.W., E.A.-C., S.M., G.M.), and Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Spain (G.C.)
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Mazurkiewicz JE, Herrick-Davis K, Barroso M, Ulloa-Aguirre A, Lindau-Shepard B, Thomas RM, Dias JA. Single-molecule analyses of fully functional fluorescent protein-tagged follitropin receptor reveal homodimerization and specific heterodimerization with lutropin receptor. Biol Reprod 2015; 92:100. [PMID: 25761594 DOI: 10.1095/biolreprod.114.125781] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 03/02/2015] [Indexed: 01/27/2023] Open
Abstract
We have previously shown that the carboxyl terminus (cT) of human follicle-stimulating hormone (FSH, follitropin) receptor (FSHR) is clipped before insertion into the plasma membrane. Surprisingly, several different constructs of FSHR fluorescent fusion proteins (FSHR-FPs) failed to traffic to the plasma membrane. Subsequently, we discovered that substituting the extreme cT of luteinizing hormone (LH) receptor (LHR) to create an FSHR-LHRcT chimera has no effect on FSHR functionality. Therefore, we used this approach to create an FSHR-LHRcT-FP fusion. We found this chimeric FSHR-LHRcT-FP was expressed in HEK293 cells at levels similar to reported values for FSHR in human granulosa cells, bound FSH with high affinity, and transduced FSH binding to produce cAMP. Quantitative fluorescence resonance energy transfer (FRET) analysis of FSHR-LHRcT-YFP/FSHR-LHRcT-mCherry pairs revealed an average FRET efficiency of 12.9 ± 5.7. Advanced methods in single-molecule analyses were applied in order to ascertain the oligomerization state of the FSHR-LHRcT. Fluorescence correlation spectroscopy coupled with photon-counting histogram analyses demonstrated that the FSHR-LHRcT-FP fusion protein exists as a freely diffusing homodimer in the plasma membrane. A central question is whether LHR could oligomerize with FSHR, because both receptors are coexpressed in differentiated granulosa cells. Indeed, FRET analysis revealed an average FRET efficiency of 14.4 ± 7.5 when the FSHR-LHR cT-mCherry was coexpressed with LHR-YFP. In contrast, coexpression of a 5-HT2cVSV-YFP with FSHR-LHR cT-mCherry showed only 5.6 ± 3.2 average FRET efficiency, a value indistinguishable from the detection limit using intensity-based FRET methods. These data demonstrate that coexpression of FSHR and LHR can lead to heterodimerization, and we hypothesize that it is possible for this to occur during granulosa cell differentiation.
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Affiliation(s)
- Joseph E Mazurkiewicz
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, New York
| | | | - Margarida Barroso
- Center for Cardiovascular Science, Albany Medical College, Albany, New York
| | - Alfredo Ulloa-Aguirre
- Research Support Network, Instituto Nacional de Ciencias Médicas y Nutrición SZ-Universidad Nacional Autónoma de México, México D.F., México
| | - Barbara Lindau-Shepard
- Division of Genetic Disorders, Wadsworth Center, New York State Department of Health, Albany, New York
| | - Richard M Thomas
- Department of Biomedical Sciences, State University of New York at Albany, Albany, New York
| | - James A Dias
- Department of Biomedical Sciences, State University of New York at Albany, Albany, New York
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Ferré S. The GPCR heterotetramer: challenging classical pharmacology. Trends Pharmacol Sci 2015; 36:145-52. [PMID: 25704194 PMCID: PMC4357316 DOI: 10.1016/j.tips.2015.01.002] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 01/15/2015] [Accepted: 01/20/2015] [Indexed: 01/09/2023]
Abstract
Two concepts are gaining increasing acceptance in G protein-coupled receptor (GPCR) pharmacology: (i) pre-coupling of GPCRs with their preferred signaling molecules, and (ii) GPCR oligomerization. This is begging for the introduction of new models such as GPCR oligomer-containing signaling complexes with GPCR homodimers as functional building blocks. This model favors the formation of GPCR heterotetramers - heteromers of homodimers coupled to their cognate G protein. The GPCR heterotetramer offers an optimal framework for a canonical antagonistic interaction between activated Gs and Gi proteins, which can simultaneously bind to their respective preferred receptors and to adenylyl cyclase (AC) catalytic units. This review addresses the current evidence for pre-coupling of the various specific components that provide the very elaborate signaling machinery exemplified by the Gs-Gi-AC-coupled GPCR heterotetramer.
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Affiliation(s)
- Sergi Ferré
- Integrative Neurobiology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health (NIH), Triad Technology Building, 333 Cassell Drive, Baltimore, MD 21224, USA.
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Mishra AK, Mavlyutov T, Singh DR, Biener G, Yang J, Oliver JA, Ruoho A, Raicu V. The sigma-1 receptors are present in monomeric and oligomeric forms in living cells in the presence and absence of ligands. Biochem J 2015; 466:263-271. [PMID: 25510962 PMCID: PMC4500508 DOI: 10.1042/bj20141321] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The sigma-1 receptor (S1R) is a 223-amino-acid membrane protein that resides in the endoplasmic reticulum and the plasma membrane of some mammalian cells. The S1R is regulated by various synthetic molecules including (+)-pentazocine, cocaine and haloperidol and endogenous molecules such as sphingosine, dimethyltryptamine and dehydroepiandrosterone. Ligand-regulated protein chaperone functions linked to oxidative stress and neurodegenerative disorders such as amyotrophic lateral sclerosis (ALS) and neuropathic pain have been attributed to the S1R. Several client proteins that interact with S1R have been identified including various types of ion channels and G-protein coupled receptors (GPCRs). When S1R constructs containing C-terminal monomeric GFP2 and YFP fusions were co-expressed in COS-7 cells and subjected to FRET spectrometry analysis, monomers, dimers and higher oligomeric forms of S1R were identified under non-liganded conditions. In the presence of the prototypic S1R agonist, (+)-pentazocine, however, monomers and dimers were the prevailing forms of S1R. The prototypic antagonist, haloperidol, on the other hand, favoured higher order S1R oligomers. These data, in sum, indicate that heterologously expressed S1Rs occur in vivo in COS-7 cells in multiple oligomeric forms and that S1R ligands alter these oligomeric structures. We suggest that the S1R oligomerization states may regulate its function(s).
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Affiliation(s)
- Ashish K. Mishra
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, U.S.A
| | - Timur Mavlyutov
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI 53211, U.S.A
| | - Deo R. Singh
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, U.S.A
| | - Gabriel Biener
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, U.S.A
| | - Jay Yang
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, WI 53211, U.S.A
| | - Julie A. Oliver
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, U.S.A
| | - Arnold Ruoho
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI 53211, U.S.A
| | - Valerică Raicu
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, U.S.A
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, U.S.A
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42
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Zakrys L, Ward RJ, Pediani JD, Godin AG, Graham GJ, Milligan G. Roundabout 1 exists predominantly as a basal dimeric complex and this is unaffected by binding of the ligand Slit2. Biochem J 2014; 461:61-73. [PMID: 24673457 DOI: 10.1042/bj20140190] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Robo (Roundabout) receptors and their Slit polypeptide ligands are known to play key roles in neuronal development and have been implicated in both angiogenesis and cancer. Like the other family members, Robo1 is a large single transmembrane domain polypeptide containing a series of well-defined extracellular elements. However, the intracellular domain lacks structural definition and little is known about the quaternary structure of Robo receptors or how binding of a Slit might affect this. To address these questions combinations of both autofluorescent protein-based FRET imaging and time-resolved FRET were employed. Both approaches identified oligomeric organization of Robo1 that did not require the presence of the intracellular domain. SpIDA (spatial intensity distribution analysis) of eGFP-tagged forms of Robo1 indicated that for a C-terminally deleted version approximately two-thirds of the receptor was present as a dimer and one-third as a monomer. By contrast, full-length Robo1 was present almost exclusively as a dimer. In each case this was unaffected by the addition of Slit2, although parallel studies demonstrated the biological activity of Slit2 and its interaction with Robo1. Deletion of both the immunoglobulin and fibronectin type III extracellular repeats prevented dimer formation, with the immunoglobulin repeats providing the bulk of the protein-protein interaction affinity.
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Affiliation(s)
| | - Richard J Ward
- *Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow G12 8QQ, Scotland, U.K
| | - John D Pediani
- *Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow G12 8QQ, Scotland, U.K
| | - Antoine G Godin
- ‡Laboratoire Photonique, Numérique et Nanosciences (LP2N) Institut d'Optique Graduate School, CNRS and Université Bordeaux, 351 cours de la libération, 33405 Talence Cedex, France
| | - Gerard J Graham
- †Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, U.K
| | - Graeme Milligan
- *Molecular Pharmacology Group, Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow G12 8QQ, Scotland, U.K
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Raicu V, Singh DR. FRET spectrometry: a new tool for the determination of protein quaternary structure in living cells. Biophys J 2014; 105:1937-45. [PMID: 24209838 DOI: 10.1016/j.bpj.2013.09.015] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 09/11/2013] [Accepted: 09/12/2013] [Indexed: 11/30/2022] Open
Abstract
Förster resonance energy transfer (FRET) is an exquisitely sensitive method for detection of molecular interactions and conformational changes in living cells. The recent advent of fluorescence imaging technology with single-molecule (or molecular-complex) sensitivity, together with refinements in the kinetic theory of FRET, provide the necessary tool kits for determining the stoichiometry and relative disposition of the protomers within protein complexes (i.e., quaternary structure) of membrane receptors and transporters in living cells. In contrast to standard average-based methods, this method relies on the analysis of distributions of apparent FRET efficiencies, E(app), across the image pixels of individual cells expressing proteins of interest. The most probable quaternary structure of the complex is identified from the number of peaks in the E(app) distribution and their dependence on a single parameter, termed pairwise FRET efficiency. Such peaks collectively create a unique FRET spectrum corresponding to each oligomeric configuration of the protein. Therefore, FRET could quite literally become a spectrometric method--akin to that of mass spectrometry--for sorting protein complexes according to their size and shape.
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Affiliation(s)
- Valerică Raicu
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin; Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin.
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Kan W, Adjobo-Hermans M, Burroughs M, Faibis G, Malik S, Tall GG, Smrcka AV. M3 muscarinic receptor interaction with phospholipase C β3 determines its signaling efficiency. J Biol Chem 2014; 289:11206-11218. [PMID: 24596086 DOI: 10.1074/jbc.m113.538546] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Phospholipase Cβ (PLCβ) enzymes are activated by G protein-coupled receptors through receptor-catalyzed guanine nucleotide exchange on Gαβγ heterotrimers containing Gq family G proteins. Here we report evidence for a direct interaction between M3 muscarinic receptor (M3R) and PLCβ3. Both expressed and endogenous M3R interacted with PLCβ in coimmunoprecipitation experiments. Stimulation of M3R with carbachol significantly increased this association. Expression of M3R in CHO cells promoted plasma membrane localization of YFP-PLCβ3. Deletion of the PLCβ3 C terminus or deletion of the PLCβ3 PDZ ligand inhibited coimmunoprecipitation with M3R and M3R-dependent PLCβ3 plasma membrane localization. Purified PLCβ3 bound directly to glutathione S-transferase (GST)-fused M3R intracellular loops 2 and 3 (M3Ri2 and M3Ri3) as well as M3R C terminus (M3R/H8-CT). PLCβ3 binding to M3Ri3 was inhibited when the PDZ ligand was removed. In assays using reconstituted purified components in vitro, M3Ri2, M3Ri3, and M3R/H8-CT potentiated Gαq-dependent but not Gβγ-dependent PLCβ3 activation. Disruption of key residues in M3Ri3N and of the PDZ ligand in PLCβ3 inhibited M3Ri3-mediated potentiation. We propose that the M3 muscarinic receptor maximizes the efficiency of PLCβ3 signaling beyond its canonical role as a guanine nucleotide exchange factor for Gα.
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Affiliation(s)
- Wei Kan
- Departments of Pharmacology and Physiology and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Merel Adjobo-Hermans
- Department of Biochemistry, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands
| | - Michael Burroughs
- Departments of Pharmacology and Physiology and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Guy Faibis
- Departments of Pharmacology and Physiology and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Sundeep Malik
- Departments of Pharmacology and Physiology and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Gregory G Tall
- Departments of Pharmacology and Physiology and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Alan V Smrcka
- Departments of Pharmacology and Physiology and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642; Biochemistry and Biophysics and University of Rochester School of Medicine and Dentistry, Rochester, New York 14642; Aab Institute of Cardiovascular Research, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642 and.
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45
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Ferré S, Casadó V, Devi LA, Filizola M, Jockers R, Lohse MJ, Milligan G, Pin JP, Guitart X. G protein-coupled receptor oligomerization revisited: functional and pharmacological perspectives. Pharmacol Rev 2014; 66:413-34. [PMID: 24515647 DOI: 10.1124/pr.113.008052] [Citation(s) in RCA: 427] [Impact Index Per Article: 42.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Most evidence indicates that, as for family C G protein-coupled receptors (GPCRs), family A GPCRs form homo- and heteromers. Homodimers seem to be a predominant species, with potential dynamic formation of higher-order oligomers, particularly tetramers. Although monomeric GPCRs can activate G proteins, the pentameric structure constituted by one GPCR homodimer and one heterotrimeric G protein may provide a main functional unit, and oligomeric entities can be viewed as multiples of dimers. It still needs to be resolved if GPCR heteromers are preferentially heterodimers or if they are mostly constituted by heteromers of homodimers. Allosteric mechanisms determine a multiplicity of possible unique pharmacological properties of GPCR homomers and heteromers. Some general mechanisms seem to apply, particularly at the level of ligand-binding properties. In the frame of the dimer-cooperativity model, the two-state dimer model provides the most practical method to analyze ligand-GPCR interactions when considering receptor homomers. In addition to ligand-binding properties, unique properties for each GPCR oligomer emerge in relation to different intrinsic efficacy of ligands for different signaling pathways (functional selectivity). This gives a rationale for the use of GPCR oligomers, and particularly heteromers, as novel targets for drug development. Herein, we review the functional and pharmacological properties of GPCR oligomers and provide some guidelines for the application of discrete direct screening and high-throughput screening approaches to the discovery of receptor-heteromer selective compounds.
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Affiliation(s)
- Sergi Ferré
- Integrative Neurobiology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes on Drug Abuse, Department of Health and Human Services, 333 Cassell Drive, Baltimore, Maryland 21224.
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46
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Desai AJ, Roberts DJ, Richards GO, Skerry TM. Role of receptor activity modifying protein 1 in function of the calcium sensing receptor in the human TT thyroid carcinoma cell line. PLoS One 2014; 9:e85237. [PMID: 24454825 PMCID: PMC3890319 DOI: 10.1371/journal.pone.0085237] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 12/02/2013] [Indexed: 12/15/2022] Open
Abstract
The Calcium Sensing Receptor (CaSR) plays a role in calcium homeostasis by sensing minute changes in serum Ca(2+) and modulating secretion of calciotropic hormones. It has been shown in transfected cells that accessory proteins known as Receptor Activity Modifying Proteins (RAMPs), specifically RAMPs 1 and 3, are required for cell-surface trafficking of the CaSR. These effects have only been demonstrated in transfected cells, so their physiological relevance is unclear. Here we explored CaSR/RAMP interactions in detail, and showed that in thyroid human carcinoma cells, RAMP1 is required for trafficking of the CaSR. Furthermore, we show that normal RAMP1 function is required for intracellular responses to ligands. Specifically, to confirm earlier studies with tagged constructs, and to provide the additional benefit of quantitative stoichiometric analysis, we used fluorescence resonance energy transfer to show equal abilities of RAMP1 and 3 to chaperone CaSR to the cell surface, though RAMP3 interacted more efficiently with the receptor. Furthermore, a higher fraction of RAMP3 than RAMP1 was observed in CaSR-complexes on the cell-surface, suggesting different ratios of RAMPs to CaSR. In order to determine relevance of these findings in an endogenous expression system we assessed the effect of RAMP1 siRNA knock-down in medullary thyroid carcinoma TT cells, (which express RAMP1, but not RAMP3 constitutively) and measured a significant 50% attenuation of signalling in response to CaSR ligands Cinacalcet and neomycin. Blockade of RAMP1 using specific antibodies induced a concentration-dependent reduction in CaSR-mediated signalling in response to Cinacalcet in TT cells, suggesting a novel functional role for RAMP1 in regulation of CaSR signalling in addition to its known role in receptor trafficking. These data provide evidence that RAMPs traffic the CaSR as higher-level oligomers and play a role in CaSR signalling even after cell surface localisation has occurred.
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Affiliation(s)
- Aditya J. Desai
- The Mellanby Centre for Bone Research, Department of Human Metabolism, University of Sheffield, Sheffield, United Kingdom
| | - David J. Roberts
- The Mellanby Centre for Bone Research, Department of Human Metabolism, University of Sheffield, Sheffield, United Kingdom
| | - Gareth O. Richards
- The Mellanby Centre for Bone Research, Department of Human Metabolism, University of Sheffield, Sheffield, United Kingdom
| | - Timothy M. Skerry
- The Mellanby Centre for Bone Research, Department of Human Metabolism, University of Sheffield, Sheffield, United Kingdom
- * E-mail:
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47
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Chung KY. Structural Aspects of GPCR-G Protein Coupling. Toxicol Res 2014; 29:149-55. [PMID: 24386514 PMCID: PMC3877993 DOI: 10.5487/tr.2013.29.3.149] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 09/10/2013] [Accepted: 09/17/2013] [Indexed: 11/24/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are membrane receptors; approximately 40% of drugs on the market target GPCRs. A precise understanding of the activation mechanism of GPCRs would facilitate the development of more effective and less toxic drugs. Heterotrimeric G proteins are important molecular switches in GPCR-mediated signal transduction. An agonist-activated receptor interacts with specific sites on G proteins and promotes the release of GDP from the Gα subunit. Because of the important biological role of the GPCR-G protein coupling, conformational changes in the G protein upon receptor coupling have been of great interest. One of the most important questions was the interface between the GPCR and G proteins and the structural mechanism of GPCR-induced G protein activation. A number of biochemical and biophysical studies have been performed since the late 80s to address these questions; there was a significant breakthrough in 2011 when the crystal structure of a GPCR-G protein complex was solved. This review discusses the structural aspects of GPCR-G protein coupling by comparing the results of previous biochemical and biophysical studies to the GPCR-G protein crystal structure.
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Affiliation(s)
- Ka Young Chung
- School of Pharmacy, Sungkyunkwan University, Suwon, Korea
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48
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Biener G, Stoneman MR, Acbas G, Holz JD, Orlova M, Komarova L, Kuchin S, Raicu V. Development and experimental testing of an optical micro-spectroscopic technique incorporating true line-scan excitation. Int J Mol Sci 2013; 15:261-76. [PMID: 24378851 PMCID: PMC3907809 DOI: 10.3390/ijms15010261] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 12/15/2013] [Accepted: 12/23/2013] [Indexed: 11/17/2022] Open
Abstract
Multiphoton micro-spectroscopy, employing diffraction optics and electron-multiplying CCD (EMCCD) cameras, is a suitable method for determining protein complex stoichiometry, quaternary structure, and spatial distribution in living cells using Förster resonance energy transfer (FRET) imaging. The method provides highly resolved spectra of molecules or molecular complexes at each image pixel, and it does so on a timescale shorter than that of molecular diffusion, which scrambles the spectral information. Acquisition of an entire spectrally resolved image, however, is slower than that of broad-bandwidth microscopes because it takes longer times to collect the same number of photons at each emission wavelength as in a broad bandwidth. Here, we demonstrate an optical micro-spectroscopic scheme that employs a laser beam shaped into a line to excite in parallel multiple sample voxels. The method presents dramatically increased sensitivity and/or acquisition speed and, at the same time, has excellent spatial and spectral resolution, similar to point-scan configurations. When applied to FRET imaging using an oligomeric FRET construct expressed in living cells and consisting of a FRET acceptor linked to three donors, the technique based on line-shaped excitation provides higher accuracy compared to the point-scan approach, and it reduces artifacts caused by photobleaching and other undesired photophysical effects.
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Affiliation(s)
- Gabriel Biener
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA.
| | - Michael R Stoneman
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA.
| | - Gheorghe Acbas
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA.
| | - Jessica D Holz
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA.
| | - Marianna Orlova
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA.
| | - Liudmila Komarova
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA.
| | - Sergei Kuchin
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA.
| | - Valerică Raicu
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA.
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Arachiche A, Mumaw MM, de la Fuente M, Nieman MT. Protease-activated receptor 1 (PAR1) and PAR4 heterodimers are required for PAR1-enhanced cleavage of PAR4 by α-thrombin. J Biol Chem 2013; 288:32553-32562. [PMID: 24097976 DOI: 10.1074/jbc.m113.472373] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Thrombin is a potent platelet agonist that activates platelets and other cells of the cardiovascular system by cleaving its G-protein-coupled receptors, protease-activated receptor 1 (PAR1), PAR4, or both. We now show that cleaving PAR1 and PAR4 with α-thrombin induces heterodimer formation. PAR1-PAR4 heterodimers were not detected when unstimulated; however, when the cells were stimulated with 10 nm α-thrombin, we were able to detect a strong interaction between PAR1 and PAR4 by bioluminescence resonance energy transfer. In contrast, activating the receptors without cleavage using PAR1 and PAR4 agonist peptides (TFLLRN and AYPGKF, respectively) did not enhance heterodimer formation. Preventing PAR1 or PAR4 cleavage with point mutations or hirugen also prevented the induction of heterodimers. To further characterize the PAR1-PAR4 interactions, we mapped the heterodimer interface by introducing point mutations in transmembrane helix 4 of PAR1 or PAR4 that prevented heterodimer formation. Finally, we show that mutations in PAR1 or PAR4 at the heterodimer interface prevented PAR1-assisted cleavage of PAR4. These data demonstrate that PAR1 and PAR4 require allosteric changes induced via receptor cleavage by α-thrombin to mediate heterodimer formation, and we have determined the PAR1-PAR4 heterodimer interface. Our findings show that PAR1 and PAR4 have dynamic interactions on the cell surface that should be taken into account when developing and characterizing PAR antagonists.
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Affiliation(s)
- Amal Arachiche
- From the Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106
| | - Michele M Mumaw
- From the Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106
| | - María de la Fuente
- From the Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106
| | - Marvin T Nieman
- From the Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio 44106.
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Herrick-Davis K, Grinde E, Cowan A, Mazurkiewicz JE. Fluorescence correlation spectroscopy analysis of serotonin, adrenergic, muscarinic, and dopamine receptor dimerization: the oligomer number puzzle. Mol Pharmacol 2013; 84:630-42. [PMID: 23907214 DOI: 10.1124/mol.113.087072] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The issue of G protein-coupled receptor (GPCR) oligomer status has not been resolved. Although many studies have provided evidence in favor of receptor-receptor interactions, there is no consensus as to the exact oligomer size of class A GPCRs. Previous studies have reported monomers, dimers, tetramers, and higher-order oligomers. In the present study, this issue was examined using fluorescence correlation spectroscopy (FCS) with photon counting histogram (PCH) analysis, a sensitive method for monitoring diffusion and oligomer size of plasma membrane proteins. Six different class A GPCRs were selected from the serotonin (5-HT2A), adrenergic (α1b-AR and β2-AR), muscarinic (M1 and M2), and dopamine (D1) receptor families. Each GPCR was C-terminally labeled with green fluorescent protein (GFP) or yellow fluorescent protein (YFP) and expressed in human embryonic kidney 293 cells. FCS provided plasma membrane diffusion coefficients on the order of 7.5 × 10(-9) cm(2)/s. PCH molecular brightness analysis was used to determine the GPCR oligomer size. Known monomeric (CD-86) and dimeric (CD-28) receptors with GFP and YFP tags were used as controls to determine the molecular brightness of monomers and dimers. PCH analysis of fluorescence-tagged GPCRs revealed molecular brightness values that were twice the monomeric controls and similar to the dimeric controls. Reduced χ(2) analyses of the PCH data best fit a model for a homogeneous population of homodimers, without tetramers or higher-order oligomers. The homodimer configuration was unaltered by agonist treatment and was stable over a 10-fold range of receptor expression level. The results of this study demonstrate that biogenic amine receptors freely diffusing within the plasma membrane are predominantly homodimers.
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Affiliation(s)
- Katharine Herrick-Davis
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, New York (K.H.-D., E.G., J.E.M.); and Center for Cell Analysis and Modeling, University of Connecticut Health Center, Farmington, Connecticut (A.C.)
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