351
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Kocan M, Pfleger KDG. Detection of GPCR/beta-arrestin interactions in live cells using bioluminescence resonance energy transfer technology. Methods Mol Biol 2009; 552:305-17. [PMID: 19513659 DOI: 10.1007/978-1-60327-317-6_22] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Bioluminescence resonance energy transfer (BRET) is a powerful and increasingly popular technique for studying protein-protein interactions in live cells and real time. In particular, there has been considerable interest in the ability to monitor interactions between G protein-coupled receptors (GPCRs) and proteins that serve as key regulators of receptor function, such as beta-arrestin. The BRET methodology involves heterologous co-expression of genetically fused proteins that link one protein of interest (e.g., a GPCR) to a bioluminescent donor enzyme and a second protein of interest (e.g., beta-arrestin) to an acceptor fluorophore. If the fusion proteins are in close proximity, resonance energy will be transferred from the donor to the acceptor molecule and subsequent fluorescence from the acceptor can be detected at a characteristic wavelength. Such fluorescence is therefore indicative of the proteins of interest linked to the donor and the acceptor interacting directly or as part of a complex. In addition to monitoring protein-protein interactions to elucidate cellular function, BRET also has the exciting potential to become an important technique for live cell high-throughput screening for drugs targeting GPCRs, utilizing ligand-induced interactions with beta-arrestins.
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Affiliation(s)
- Martina Kocan
- Laboratory for Molecular Endocrinology, Western Australian Institute for Medical Research and Centre for Medical Research, University of Western Australia, Perth, Australia
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352
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Redox regulation of interleukin-4 signaling. Immunity 2008; 29:551-64. [PMID: 18957266 DOI: 10.1016/j.immuni.2008.07.019] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2007] [Revised: 05/20/2008] [Accepted: 07/23/2008] [Indexed: 12/14/2022]
Abstract
The physiologic control of cytokine receptor activation is primarily mediated by reciprocal activation of receptor-associated protein tyrosine kinases and protein tyrosine phosphatases (PTPs). Here, we show that immediately after ligand-dependent activation, interleukin (IL)-4 receptor generated reactive oxygen species (ROS) via phosphatidylinositol 3-kinase-dependent activation of NAD(P)H oxidase (NOX)1 and NOX5L. ROS, in turn, promoted IL-4 receptor activation by oxidatively inactivating PTP1B that physically associated with and deactivated IL-4 receptor. However, ROS were not required for the initiation of IL-4 receptor activation. ROS generated by other cytokine receptors, including those for erythropoietin, tumor necrosis factor-alpha, or IL-3, also promoted IL-4 signaling. These data indicate that inactivation of receptor-associated PTP activity by cytokine-generated ROS is a physiologic mechanism for the amplification of cytokine receptor activation in both cis and trans, revealing a role for ROS in cytokine crosstalk.
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353
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Intermolecular interactions identify ligand-selective activity of estrogen receptor alpha/beta dimers. Proc Natl Acad Sci U S A 2008; 105:19012-7. [PMID: 19022902 DOI: 10.1073/pnas.0807274105] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Estrogen receptor (ER) dimerization is prerequisite for its activation of target gene transcription. Because the two forms of ER, ERalpha and ERbeta, exhibit opposing functions in cell proliferation, the ability of ligands to induce ERalpha/beta heterodimers vs. their respective homodimers is expected to have profound impacts on transcriptional outcomes and cellular growth. However, there is a lack of direct methods to monitor the formation of ERalpha/beta heterodimers in vivo and to distinguish the ability of estrogenic ligands to promote ER homo- vs. heterodimerization. Here, we describe bioluminescence resonance energy transfer (BRET) assays for monitoring the formation of ERalpha/beta heterodimers and their respective homodimers in live cells. We demonstrate that although both partners contribute to heterodimerization, ligand-bound ERalpha plays a dominant role. Furthermore, a bioactive component was found to induce ERbeta/beta homodimers, and ERalpha/beta heterodimers but had minimal activity on ERalpha/alpha homodimers, posing a model that compounds promoting ERalpha/beta heterodimer formation might have therapeutic value. Thus, ER homodimer and heterodimer BRET assays are applicable to drug screening for dimer-selective selective ER modulators. Furthermore, this strategy can be used to study other nuclear receptor dimers.
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354
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Dacres H, Dumancic MM, Horne I, Trowell SC. Direct comparison of bioluminescence-based resonance energy transfer methods for monitoring of proteolytic cleavage. Anal Biochem 2008; 385:194-202. [PMID: 19026607 DOI: 10.1016/j.ab.2008.10.040] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Revised: 10/02/2008] [Accepted: 10/17/2008] [Indexed: 12/27/2022]
Abstract
Bioluminescence resonance energy transfer (BRET) is a powerful tool for the study of protein-protein interactions and conformational changes within proteins. Two common implementations of BRET are BRET(1) with Renilla luciferase (RLuc) and coelenterazine h (CLZ, lambda(em) approximately 475 nm) and BRET(2) with the substrate coelenterazine 400a (CLZ400A substrate, lambda(em)=395 nm) as the respective donors. For BRET(1) the acceptor is yellow fluorescent protein (YFP) (lambda(em) approximately 535 nm), a mutant of green fluorescent protein (GFP), and for BRET(2) it is GFP(2) (lambda(em) approximately 515 nm). It is not clear from previous studies which of these systems has superior signal-to-background characteristics. Here we directly compared BRET(1) and BRET(2) by placing two different protease-specific cleavage sequences between the donor and acceptor domains. The intact proteins simulate protein-protein association. Proteolytic cleavage of the peptide linker simulates protein dissociation and can be detected as a change in the BRET ratios. Complete cleavage of its target sequence by thrombin changed the BRET(2) ratio by a factor of 28.9+/-0.2 (relative standard deviation [RSD], n=3) and changed the BRET(1) ratio by a factor of 3.05+/-0.07. Complete cleavage of a caspase-3 target sequence resulted in the BRET ratio changes by factors of 15.45+/-0.08 for BRET(2) and 2.00+/-0.04 for BRET(1). The BRET(2) assay for thrombin was 2.9 times more sensitive compared with the BRET(1) version. Calculated detection limits (blank signal+3sigma(b), where sigma(b)=standard deviation [SD] of blank signal) were 53 pM (0.002 U) thrombin with BRET(1) and 15 pM (0.0005 U) thrombin with BRET(2). The results presented here suggest that BRET(2) is a more suitable system than BRET(1) for studying protein-protein interactions and as a potential sensor for monitoring protease activity.
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Affiliation(s)
- Helen Dacres
- Food Futures Flagship, CSIRO Entomology, Canberra, ACT, Australia.
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355
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Roda A, Guardigli M, Michelini E, Mirasoli M. Nanobioanalytical luminescence: Förster-type energy transfer methods. Anal Bioanal Chem 2008; 393:109-23. [DOI: 10.1007/s00216-008-2435-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Revised: 09/22/2008] [Accepted: 09/23/2008] [Indexed: 12/21/2022]
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356
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Inclusion bodies: Specificity in their aggregation process and amyloid-like structure. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:1815-25. [DOI: 10.1016/j.bbamcr.2008.06.007] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2007] [Revised: 05/28/2008] [Accepted: 06/03/2008] [Indexed: 01/10/2023]
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357
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Kocan M, See HB, Seeber RM, Eidne KA, Pfleger KDG. Demonstration of improvements to the bioluminescence resonance energy transfer (BRET) technology for the monitoring of G protein-coupled receptors in live cells. ACTA ACUST UNITED AC 2008; 13:888-98. [PMID: 18812574 DOI: 10.1177/1087057108324032] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The bioluminescence resonance energy transfer (BRET) technique has become extremely popular for studying protein-protein interactions in living cells and real time. Of particular interest is the ability to monitor interactions between G protein-coupled receptors, such as the thyrotropin-releasing hormone receptor (TRHR), and proteins critical for regulating their function, such as beta-arrestin. Using TRHR/beta-arrestin interactions, we have demonstrated improvements to all 3 generations of BRET (BRET(1), BRET(2), and eBRET) by using the novel forms of luciferase, Rluc2 and Rluc8, developed by the Gambhir laboratory. Furthermore, for the 1st time it was possible to use the BRET2 system to detect ligand-induced G protein-coupled receptor/beta-arrestin interactions over prolonged periods (on the scale of hours rather than seconds) with a very stable signal. As demonstrated by our Z'-factor data, these luciferases increase the sensitivity of BRET to such an extent that they substantially increase the potential applicability of this technology for effective drug discovery high-throughput screening.
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Affiliation(s)
- Martina Kocan
- Laboratory for Molecular Endocrinology-GPCRs, Western Australian Institute for Medical Research (WAIMR), Centre for Medical Research, University of Western Australia, Perth, Western Australia, Australia
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358
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Dacres H, Dumancic MM, Horne I, Trowell SC. Direct comparison of fluorescence- and bioluminescence-based resonance energy transfer methods for real-time monitoring of thrombin-catalysed proteolytic cleavage. Biosens Bioelectron 2008; 24:1164-70. [PMID: 18723336 DOI: 10.1016/j.bios.2008.07.021] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Revised: 06/30/2008] [Accepted: 07/01/2008] [Indexed: 10/21/2022]
Abstract
In this study, a representative FRET system (CFP donor and YFP acceptor) is compared with the BRET(2) system (Renilla luciferase donor, green fluorescent protein(2) (GFP(2)) acceptor and coelenterazine 400a substrate). Cleavage of a thrombin-protease-sensitive peptide sequence inserted between the donor and acceptor proteins was detected by the RET signal. Complete cleavage by thrombin changed the BRET(2) signal by a factor of 28.9+/-0.2 (R.S.D. (relative standard deviation), n=3) and the FRET signal by a factor of 3.2+/-0.1 (R.S.D., n=3). The BRET(2) technique was 50 times more sensitive than the FRET technique for monitoring thrombin concentrations. Detection limits (blank signal+3sigma(b), where sigma(b)=the standard deviation (S.D.) of the blank signal) were calculated to be 3.05 and 0.22nM thrombin for FRET and BRET(2), respectively. This direct comparison suggests that the BRET(2) technique is more suitable than FRET for use in proximity assays such as protease cleavage assays or protein-protein interaction assays.
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Affiliation(s)
- H Dacres
- Food Futures Flagship, CSIRO Entomology, GPO Box 1700, Canberra, ACT 2601, Australia
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359
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Ciruela F. Fluorescence-based methods in the study of protein-protein interactions in living cells. Curr Opin Biotechnol 2008; 19:338-43. [PMID: 18602005 DOI: 10.1016/j.copbio.2008.06.003] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Revised: 06/04/2008] [Accepted: 06/06/2008] [Indexed: 11/29/2022]
Abstract
Multiprotein complexes partake in nearly all cell functions, thus the characterization and visualization of protein-protein interactions in living cells constitute an important step in the study of a large array of cellular mechanisms. Recently, noninvasive fluorescence-based methods using resonance energy transfer (RET), namely bioluminescence-RET (BRET) and fluorescence-RET (FRET), and those centered on protein fragment complementation, such as bimolecular fluorescence complementation (BiFC), have been successfully used in the study of protein interactions. These new technologies are nowadays the most powerful approaches for visualizing the interactions occurring within protein complexes in living cells, thus enabling the investigation of protein behavior in their normal milieu. Here we address the individual strengths and weaknesses of these methods when applied to the study of protein-protein interactions.
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Affiliation(s)
- Francisco Ciruela
- Unitat de Farmacologia, Departament de Patologia i Terapèutica Experimental, Facultat de Medicina (Campus de Bellvitge), IDIBELL-Universitat de Barcelona, 08907 L'Hospitalet del Llobregat, Barcelona, Spain.
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360
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Opioid and chemokine receptor heterodimers: arranged marriages or dangerous liaisons? Biochem J 2008; 412:e7-9. [PMID: 18466114 DOI: 10.1042/bj20080620] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Heterodimerization of GPCRs (G-protein-coupled receptors) has begun to be appreciated as a rich new vein for drug discovery. The possibility of developing modulators for different GPCRs which work at allosteric sites other than the ligand-binding site is not new, but the notion of using a dimeric receptor partner as the target for this intervention has not yet percolated into the broader industrial community. In the present article, I discuss this notion in the context of the heterodimeric delta-opioid receptor-CXCR2 chemokine receptor dimer identified by Parenty et al., in this issue of the Biochemical Journal.
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361
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Liu P, Ahmed S, Wohland T. The F-techniques: advances in receptor protein studies. Trends Endocrinol Metab 2008; 19:181-90. [PMID: 18387308 DOI: 10.1016/j.tem.2008.02.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 02/13/2008] [Accepted: 02/22/2008] [Indexed: 11/20/2022]
Abstract
Recent developments in advanced microscopy techniques, the so-called F-techniques, including Förster resonance energy transfer, fluorescence correlation spectroscopy and fluorescence lifetime imaging, have led to a wide range of novel applications in biology. The F-techniques provide quantitative information on biomolecules and their interactions and give high spatial and temporal resolution. In particular, their application to receptor protein studies has led to new insights into receptor localization, oligomerization, activation and function in vivo. This review focuses on the application of the F-techniques to the study of receptor molecules and mechanisms in the last three years and provides information on new modalities that will further improve their applicability and widen the range of biological questions that can be addressed.
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Affiliation(s)
- Ping Liu
- Department of Chemistry, National University of Singapore, Singapore
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362
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Rebois RV, Robitaille M, Pétrin D, Zylbergold P, Trieu P, Hébert TE. Combining protein complementation assays with resonance energy transfer to detect multipartner protein complexes in living cells. Methods 2008; 45:214-8. [DOI: 10.1016/j.ymeth.2008.06.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2008] [Accepted: 06/16/2008] [Indexed: 10/21/2022] Open
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363
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Detection of heteromerization of more than two proteins by sequential BRET-FRET. Nat Methods 2008; 5:727-33. [DOI: 10.1038/nmeth.1229] [Citation(s) in RCA: 226] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2008] [Accepted: 06/05/2008] [Indexed: 11/08/2022]
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364
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Mellado M, Carrasco YR. Imaging techniques: new insights into chemokine/chemokine receptor biology at the immune system. Pharmacol Ther 2008; 119:24-32. [PMID: 18573535 DOI: 10.1016/j.pharmthera.2008.04.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2008] [Accepted: 04/28/2008] [Indexed: 11/16/2022]
Abstract
Our current knowledge of molecular and cellular responses in vivo is based mainly on event reconstruction from time-freeze observations. Conventional biochemical and genetic methods consider the cell as an individual entity and ligand/receptor pairs as isolated systems. In addition, the data refer to the average behavior of a pool of cells and/or receptors removed from their real-life context. The use of new technologies, particularly real-time imaging approaches, is showing us that biological responses are highly dynamic and extremely dependent on the context in which they take place, and therefore much more diverse than initially envisaged. This review focuses on the mechanistic insights that new imaging techniques, such as those based on resonance energy transfer and two-photon microscopy, contribute to our understanding of how receptors work within a single cell, and how cells work within a tissue. Cell movement is a complex and regulated process; it has a key role in embryogenesis, organogenesis, wound-healing and tumor invasion. Nonetheless, it is in immune system homeostasis and response that cell movement becomes essential. For this reason, immunology is being radically transformed and enriched by these new approaches. We will discuss the use of these techniques for studying chemokine/chemokine receptors and their role in the immune system function, and comment on the potential contribution to the design of therapeutic strategies.
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Affiliation(s)
- Mario Mellado
- Department of Immunology and Oncology, National Centre of Biotechnology/CSIC, Darwin 3, UAM-Campus de Cantoblanco, Madrid E-28049, Spain.
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365
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Melatonin receptors, heterodimerization, signal transduction and binding sites: what's new? Br J Pharmacol 2008; 154:1182-95. [PMID: 18493248 DOI: 10.1038/bjp.2008.184] [Citation(s) in RCA: 219] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Melatonin is a neurohormone that has been claimed to be involved in a wide range of physiological functions. Nevertheless, for most of its effects, the mechanism of action is not really known. In mammals, two melatonin receptors, MT1 and MT2, have been cloned. They belong to the G-protein-coupled receptor (GPCR) superfamily. They share some specific short amino-acid sequences, which suggest that they represent a specific subfamily. Another receptor from the same subfamily, the melatonin-related receptor has been cloned in different species including humans. This orphan receptor also named GPR50 does not bind melatonin and its endogenous ligand is still unknown. Nevertheless, this receptor has been shown to behave as an antagonist of the MT1 receptor, which opens new pharmacological perspectives for GPR50 despite the lack of endogenous or synthetic ligands. Moreover, MT1 and MT2 interact together through the formation of heterodimers at least in cells transfected with the cDNA of these two receptors. Lastly, signalling complexes associated with MT1 and MT2 receptors are starting to be deciphered. A third melatonin-binding site has been purified and characterized as the enzyme quinone reductase 2 (QR2). Inhibition of QR2 by melatonin may explain melatonin's protective effect that has been reported in different animal models and that is generally associated with its well-documented antioxidant properties.
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366
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Maurel D, Comps-Agrar L, Brock C, Rives ML, Bourrier E, Ayoub MA, Bazin H, Tinel N, Durroux T, Prézeau L, Trinquet E, Pin JP. Cell-surface protein-protein interaction analysis with time-resolved FRET and snap-tag technologies: application to GPCR oligomerization. Nat Methods 2008; 5:561-7. [PMID: 18488035 DOI: 10.1038/nmeth.1213] [Citation(s) in RCA: 377] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Accepted: 04/14/2008] [Indexed: 11/09/2022]
Abstract
Cell-surface proteins are important in cell-cell communication. They assemble into heterocomplexes that include different receptors and effectors. Elucidation and manipulation of such protein complexes offers new therapeutic possibilities. We describe a methodology combining time-resolved fluorescence resonance energy transfer (FRET) with snap-tag technology to quantitatively analyze protein-protein interactions at the surface of living cells, in a high throughput-compatible format. Using this approach, we examined whether G protein-coupled receptors (GPCRs) are monomers or assemble into dimers or larger oligomers--a matter of intense debate. We obtained evidence for the oligomeric state of both class A and class C GPCRs. We also observed different quaternary structure of GPCRs for the neurotransmitters glutamate and gamma-aminobutyric acid (GABA): whereas metabotropic glutamate receptors assembled into strict dimers, the GABA(B) receptors spontaneously formed dimers of heterodimers, offering a way to modulate G-protein coupling efficacy. This approach will be useful in systematic analysis of cell-surface protein interaction in living cells.
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Affiliation(s)
- Damien Maurel
- Centre National de la Recherche Scientifique (CNRS), UMR 5203, Institut de Génomique Fonctionnelle, 141 Rue de la Cardonille, Montpellier F-34000, France
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367
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Dalrymple MB, Pfleger KDG, Eidne KA. G protein-coupled receptor dimers: functional consequences, disease states and drug targets. Pharmacol Ther 2008; 118:359-71. [PMID: 18486226 DOI: 10.1016/j.pharmthera.2008.03.004] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2008] [Accepted: 03/14/2008] [Indexed: 10/22/2022]
Abstract
With an ever-expanding need for reliable therapeutic agents that are highly effective and exhibit minimal deleterious side effects, a greater understanding of the mechanisms underlying G protein-coupled receptor (GPCR) regulation is fundamental. GPCRs comprise more than 30% of all therapeutic drug targets and it is likely that this will only increase as more orphan GPCRs are identified. The past decade has seen a dramatic shift in the prevailing concept of how GPCRs function, in particular the growing acceptance that GPCRs are capable of interacting with one another at a molecular level to form complexes, with significantly different pharmacological properties to their monomeric selves. While the ability of like-receptors to associate and form homodimers raises some interesting mechanistic issues, the possibility that unlike-receptors could heterodimerise in certain tissue types, producing a functionally unique signalling complex that binds specific ligands, provides an invaluable opportunity to refine and redefine pharmacological interventions with greater specificity and efficacy.
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Affiliation(s)
- Matthew B Dalrymple
- Laboratory for Molecular Endocrinology - GPCRs, Western Australian Institute for Medical Research and Centre for Medical Research, University of Western Australia, Nedlands, Perth, WA 6009, Australia
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368
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Guillaume JL, Daulat AM, Maurice P, Levoye A, Migaud M, Brydon L, Malpaux B, Borg-Capra C, Jockers R. The PDZ protein mupp1 promotes Gi coupling and signaling of the Mt1 melatonin receptor. J Biol Chem 2008; 283:16762-71. [PMID: 18378672 DOI: 10.1074/jbc.m802069200] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Intracellular signaling events are often organized around PDZ (PSD-95/Drosophila Disc large/ZO-1 homology) domain-containing scaffolding proteins. The ubiquitously expressed multi-PDZ protein MUPP1, which is composed of 13 PDZ domains, has been shown to interact with multiple viral and cellular proteins and to play important roles in receptor targeting and trafficking. In this study, we show that MUPP1 binds to the G protein-coupled MT(1) melatonin receptor and directly regulates its G(i)-dependent signal transduction. Structural determinants involved in this interaction are the PDZ10 domain of MUPP1 and the valine of the canonical class III PDZ domain binding motif DSV of the MT(1) carboxyl terminus. This high affinity interaction (K(d) approximately 4 nm), which is independent of MT(1) activation, occurs in the ovine pars tuberalis of the pituitary expressing both proteins endogenously. Although the disruption of the MT(1)/MUPP1 interaction has no effect on the subcellular localization, trafficking, or degradation of MT(1), it destabilizes the interaction between MT(1) and G(i) and abolishes G(i)-mediated signaling of MT(1). Our findings highlight a previously unappreciated role of PDZ proteins in promoting G protein coupling to receptors.
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Affiliation(s)
- Jean-Luc Guillaume
- Institut Cochin, Department of Cell Biology, Université Paris Descartes, CNRS (UMR8104), Paris 75014, France
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369
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Gandía J, Lluís C, Ferré S, Franco R, Ciruela F. Light resonance energy transfer-based methods in the study of G protein-coupled receptor oligomerization. Bioessays 2008; 30:82-9. [PMID: 18081019 DOI: 10.1002/bies.20682] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Since most of the functions in cells are mediated by multimeric protein complexes, the determination of protein-protein interactions is an important step in the study of cellular mechanisms. Traditionally, after screening for possible target interactors by means of a yeast two-hybrid screen, several methods are used to validate the initial result before carrying out functional experiments. Nowadays, non-invasive fluorescence-based methods like Bioluminescence Resonance Energy Transfer (BRET) and Fluorescence Resonance Energy Transfer (FRET) are widely used in the study of protein-protein interactions in living cells. In the present review, we address the individual strengths and weaknesses of both RET approaches, providing information on their possible future use in the study of G protein-coupled receptor oligomerization.
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Affiliation(s)
- Jorge Gandía
- Unitat de Farmacologia, Departament de Patologia i Terapèutica Experimental, Facultat de Medicina, Universitat de Barcelona, Spain
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370
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Milligan G. A day in the life of a G protein-coupled receptor: the contribution to function of G protein-coupled receptor dimerization. Br J Pharmacol 2008; 153 Suppl 1:S216-29. [PMID: 17965750 PMCID: PMC2268067 DOI: 10.1038/sj.bjp.0707490] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2007] [Revised: 08/21/2007] [Accepted: 09/06/2007] [Indexed: 02/07/2023] Open
Abstract
G protein-coupled receptors are one of the most actively studied families of proteins. However, despite the ubiquity of protein dimerization and oligomerization as a structural and functional motif in biology, until the last decade they were generally considered as monomeric, non-interacting polypeptides. For the metabotropic glutamate-like group of G protein-coupled receptors, it is now firmly established that they exist and function as dimers or, potentially, even within higher-order structures. Despite some evidence continuing to support the view that rhodopsin-like G protein-coupled receptors are predominantly monomers, many recent studies are consistent with the dimerization/oligomerization of such receptors. Key roles suggested for dimerization of G protein-coupled receptors include control of protein maturation and cell surface delivery and providing the correct framework for interactions with both hetero-trimeric G proteins and arrestins to allow signal generation and its termination. As G protein-coupled receptors are the most targeted group of proteins for the development of therapeutic small molecule medicines, recent indications that hetero-dimerization between co-expressed G protein-coupled receptors may be a common process offers the potential for the development of more selective and tissue restricted medicines. However, many of the key experiments have, so far, been limited to model cell systems. Priorities for the future include the generation of tools and reagents able to identify unequivocally potential G protein-coupled receptor hetero-dimers in native tissues and detailed analyses of the influence of hetero-dimerization on receptor function and pharmacology.
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Affiliation(s)
- G Milligan
- Molecular Pharmacology Group, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, Scotland, UK.
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371
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Janssens B, Gassen HG. Editorial: No advances without methods in biotech. Biotechnol J 2008; 3:283. [DOI: 10.1002/biot.200890024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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372
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Prinz A, Reither G, Diskar M, Schultz C. Fluorescence and bioluminescence procedures for functional proteomics. Proteomics 2008; 8:1179-96. [DOI: 10.1002/pmic.200700802] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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373
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Bacart J, Corbel C, Jockers R, Bach S, Couturier C. The BRET technology and its application to screening assays. Biotechnol J 2008; 3:311-24. [DOI: 10.1002/biot.200700222] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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374
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Biswas KH, Sopory S, Visweswariah SS. The GAF domain of the cGMP-binding, cGMP-specific phosphodiesterase (PDE5) is a sensor and a sink for cGMP. Biochemistry 2008; 47:3534-43. [PMID: 18293931 DOI: 10.1021/bi702025w] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We describe here a novel sensor for cGMP based on the GAF domain of the cGMP-binding, cGMP-specific phosphodiesterase 5 (PDE5) using bioluminescence resonance energy transfer (BRET). The wild type GAFa domain, capable of binding cGMP with high affinity, and a mutant (GAFa F163A) unable to bind cGMP were cloned as fusions between GFP and Rluc for BRET (2) assays. BRET (2) ratios of the wild type GAFa fusion protein, but not GAFa F163A, increased in the presence of cGMP but not cAMP. Higher basal BRET (2) ratios were observed in cells expressing the wild type GAFa domain than in cells expressing GAFa F163A. This was correlated with elevated basal intracellular levels of cGMP, indicating that the GAF domain could act as a sink for cGMP. The tandem GAF domains in full length PDE5 could also sequester cGMP when the catalytic activity of PDE5 was inhibited. Therefore, these results describe a cGMP sensor utilizing BRET (2) technology and experimentally demonstrate the reservoir of cGMP that can be present in cells that express cGMP-binding GAF domain-containing proteins. PDE5 is the target for the anti-impotence drug sildenafil citrate; therefore, this GAF-BRET (2) sensor could be used for the identification of novel compounds that inhibit cGMP binding to the GAF domain, thereby regulating PDE5 catalytic activity.
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Affiliation(s)
- Kabir Hassan Biswas
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore 560012, India
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375
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Optical techniques to analyze real-time activation and signaling of G-protein-coupled receptors. Trends Pharmacol Sci 2008; 29:159-65. [PMID: 18262662 DOI: 10.1016/j.tips.2007.12.002] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2007] [Revised: 12/14/2007] [Accepted: 12/17/2007] [Indexed: 12/29/2022]
Abstract
The activation of G-protein-coupled receptors (GPCRs) is traditionally measured either by monitoring downstream physiological events or by membrane-based biochemical assays. Neither of these approaches permits detailed kinetic or spatial analysis of receptor activation and signaling. Recently, several optical techniques have been developed to monitor receptor activation either by using purified reconstituted GPCRs or by observing GPCRs, G proteins and second messengers in intact cells. These techniques are providing, literally, new views on both the mechanistic basis of the signaling process and the kinetic and spatial properties of GPCR-mediated signals. They suggest that agonists can activate GPCRs within milliseconds, that different compounds can induce distinct active conformations of GPCRs, that G-protein activation is the rate-limiting step in GPCR signaling, and that cellular signals can be temporally and spatially confined. They are also raising controversial issues, such as whether or not receptors and G proteins are pre-coupled and whether G proteins dissociate during activation.
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376
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Biochemical and Biophysical Analyses of Ras Modification by Ubiquitin. Methods Enzymol 2008. [DOI: 10.1016/s0076-6879(07)38018-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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377
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Kerppola TK. Bimolecular fluorescence complementation: visualization of molecular interactions in living cells. Methods Cell Biol 2008; 85:431-70. [PMID: 18155474 DOI: 10.1016/s0091-679x(08)85019-4] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A variety of experimental methods have been developed for the analysis of protein interactions. The majority of these methods either require disruption of the cells to detect molecular interactions or rely on indirect detection of the protein interaction. The bimolecular fluorescence complementation (BiFC) assay provides a direct approach for the visualization of molecular interactions in living cells and organisms. The BiFC approach is based on the facilitated association between two fragments of a fluorescent protein when the fragments are brought together by an interaction between proteins fused to the fragments. The BiFC approach has been used for visualization of interactions among a variety of structurally diverse interaction partners in many different cell types. It enables detection of transient complexes as well as complexes formed by a subpopulation of the interaction partners. It is essential to include negative controls in each experiment in which the interface between the interaction partners has been mutated or deleted. The BiFC assay has been adapted for simultaneous visualization of multiple protein complexes in the same cell and the competition for shared interaction partners. A ubiquitin-mediated fluorescence complementation assay has also been developed for visualization of the covalent modification of proteins by ubiquitin family peptides. These fluorescence complementation assays have a great potential to illuminate a variety of biological interactions in the future.
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Affiliation(s)
- Tom K Kerppola
- Department of Biological Chemistry, Howard Hughes Medical Institute, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
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378
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Molinari P, Casella I, Costa T. Functional complementation of high-efficiency resonance energy transfer: a new tool for the study of protein binding interactions in living cells. Biochem J 2007; 409:251-61. [PMID: 17868039 DOI: 10.1042/bj20070803] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Green bioluminescence in Renilla species is generated by a ∼100% efficient RET (resonance energy transfer) process that is caused by the direct association of a blue-emitting luciferase [Rluc (Renilla luciferase)] and an RGFP (Renilla green fluorescent protein). Despite the high efficiency, such a system has never been evaluated as a potential reporter of protein–protein interactions. To address the question, we compared and analysed in mammalian cells the bioluminescence of Rluc and RGFP co-expressed as free native proteins, or as fused single-chain polypeptides and tethered partners of self-assembling coiled coils. Here, we show that: (i) no spontaneous interactions generating detectable BRET (bioluminescence RET) signals occur between the free native proteins; (ii) high-efficiency BRET similar to that observed in Renilla occurs in both fusion proteins and self-interacting chimaeras, but only if the N-terminal of RGFP is free; (iii) the high-efficiency BRET interaction is associated with a dramatic increase in light output when the luminescent reaction is triggered by low-quantum yield coelenterazine analogues. Here, we propose a new functional complementation assay based on the detection of the high-efficiency BRET signal that is generated when the reporters Rluc and RGFP are brought into close proximity by a pair of interacting proteins to which they are linked. To demonstrate its performance, we implemented the assay to measure the interaction between GPCRs (G-protein-coupled receptors) and β-arrestins. We show that complementation-induced BRET allows detection of the GPCR–β-arrestin interaction in a simple luminometric assay with high signal-to-noise ratio, good dynamic range and rapid response.
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Affiliation(s)
- Paola Molinari
- Dipartimento del Farmaco, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Roma, Italy
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379
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Michelini E, Cevenini L, Mezzanotte L, Ablamsky D, Southworth T, Branchini B, Roda A. Spectral-Resolved Gene Technology for Multiplexed Bioluminescence and High-Content Screening. Anal Chem 2007; 80:260-7. [DOI: 10.1021/ac7016579] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Elisa Michelini
- Department of Pharmaceutical Sciences, University of Bologna, Via Belmeloro 6, 40126, Bologna, Italy, Center for Applied Biomedical Research (CRBA), S. Orsola-Malpighi Hospital, Via Massarenti 9, 40138 Bologna, Italy, and Department of Chemistry, Connecticut College, 270 Mohegan Avenue, New London, Connecticut 06320
| | - Luca Cevenini
- Department of Pharmaceutical Sciences, University of Bologna, Via Belmeloro 6, 40126, Bologna, Italy, Center for Applied Biomedical Research (CRBA), S. Orsola-Malpighi Hospital, Via Massarenti 9, 40138 Bologna, Italy, and Department of Chemistry, Connecticut College, 270 Mohegan Avenue, New London, Connecticut 06320
| | - Laura Mezzanotte
- Department of Pharmaceutical Sciences, University of Bologna, Via Belmeloro 6, 40126, Bologna, Italy, Center for Applied Biomedical Research (CRBA), S. Orsola-Malpighi Hospital, Via Massarenti 9, 40138 Bologna, Italy, and Department of Chemistry, Connecticut College, 270 Mohegan Avenue, New London, Connecticut 06320
| | - Danielle Ablamsky
- Department of Pharmaceutical Sciences, University of Bologna, Via Belmeloro 6, 40126, Bologna, Italy, Center for Applied Biomedical Research (CRBA), S. Orsola-Malpighi Hospital, Via Massarenti 9, 40138 Bologna, Italy, and Department of Chemistry, Connecticut College, 270 Mohegan Avenue, New London, Connecticut 06320
| | - Tara Southworth
- Department of Pharmaceutical Sciences, University of Bologna, Via Belmeloro 6, 40126, Bologna, Italy, Center for Applied Biomedical Research (CRBA), S. Orsola-Malpighi Hospital, Via Massarenti 9, 40138 Bologna, Italy, and Department of Chemistry, Connecticut College, 270 Mohegan Avenue, New London, Connecticut 06320
| | - Bruce Branchini
- Department of Pharmaceutical Sciences, University of Bologna, Via Belmeloro 6, 40126, Bologna, Italy, Center for Applied Biomedical Research (CRBA), S. Orsola-Malpighi Hospital, Via Massarenti 9, 40138 Bologna, Italy, and Department of Chemistry, Connecticut College, 270 Mohegan Avenue, New London, Connecticut 06320
| | - Aldo Roda
- Department of Pharmaceutical Sciences, University of Bologna, Via Belmeloro 6, 40126, Bologna, Italy, Center for Applied Biomedical Research (CRBA), S. Orsola-Malpighi Hospital, Via Massarenti 9, 40138 Bologna, Italy, and Department of Chemistry, Connecticut College, 270 Mohegan Avenue, New London, Connecticut 06320
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380
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Galés C, Bouvier M. [New talk between receptor and trimeric G proteins: "an intertwined body dance"]. Med Sci (Paris) 2007; 23:1031-4. [PMID: 18021724 DOI: 10.1051/medsci/200723111031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Céline Galés
- Inserm U858, Equipe 8 Pharmacologie moléculaire et clinique du système nerveux autonome, I2MR, CHU Rangueil, BP84225, 31432 Toulouse Cedex 4, France.
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381
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Berggård T, Linse S, James P. Methods for the detection and analysis of protein-protein interactions. Proteomics 2007; 7:2833-42. [PMID: 17640003 DOI: 10.1002/pmic.200700131] [Citation(s) in RCA: 412] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A large number of methods have been developed over the years to study protein-protein interactions. Many of these techniques are now available to the nonspecialist researcher thanks to new affordable instruments and/or resource centres. A typical protein-protein interaction study usually starts with an initial screen for novel binding partners. We start this review by describing three techniques that can be used for this purpose: (i) affinity-tagged proteins (ii) the two-hybrid system and (iii) some quantitative proteomic techniques that can be used in combination with, e.g., affinity chromatography and coimmunoprecipitation for screening of protein-protein interactions. We then describe some public protein-protein interaction databases that can be searched to identify previously reported interactions for a given bait protein. Four strategies for validation of protein-protein interactions are presented: confocal microscopy for intracellular colocalization of proteins, coimmunoprecipitation, surface plasmon resonance (SPR) and spectroscopic studies. Throughout the review we focus particularly on the advantages and limitations of each method.
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Affiliation(s)
- Tord Berggård
- Department of Biophysical Chemistry, Lund University, Lund, Sweden.
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382
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Subcellular imaging of dynamic protein interactions by bioluminescence resonance energy transfer. Biophys J 2007; 94:1001-9. [PMID: 17921204 DOI: 10.1529/biophysj.107.117275] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Despite the fact that numerous studies suggest the existence of receptor multiprotein complexes, visualization and monitoring of the dynamics of such protein assemblies remain a challenge. In this study, we established appropriate conditions to consider spatiotemporally resolved images of such protein assemblies using bioluminescence resonance energy transfer (BRET) in mammalian living cells. Using covalently linked Renilla luciferase and yellow fluorescent proteins, we depicted the time course of dynamic changes in the interaction between the V2-vasopressin receptor and beta-arrestin induced by a receptor agonist. The protein-protein interactions were resolved at the level of subcellular compartments (nucleus, plasma membrane, or endocytic vesicules) and in real time within tens-of-seconds to tens-of-minutes time frame. These studies provide a proof of principle as well as experimental parameters and controls required for high-resolution dynamic studies using BRET imaging in single cells.
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383
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Rogers KL, Picaud S, Roncali E, Boisgard R, Colasante C, Stinnakre J, Tavitian B, Brûlet P. Non-invasive in vivo imaging of calcium signaling in mice. PLoS One 2007; 2:e974. [PMID: 17912353 PMCID: PMC1991622 DOI: 10.1371/journal.pone.0000974] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2007] [Accepted: 09/05/2007] [Indexed: 11/19/2022] Open
Abstract
Rapid and transient elevations of Ca(2+) within cellular microdomains play a critical role in the regulation of many signal transduction pathways. Described here is a genetic approach for non-invasive detection of localized Ca(2+) concentration ([Ca(2+)]) rises in live animals using bioluminescence imaging (BLI). Transgenic mice conditionally expressing the Ca(2+)-sensitive bioluminescent reporter GFP-aequorin targeted to the mitochondrial matrix were studied in several experimental paradigms. Rapid [Ca(2+)] rises inside the mitochondrial matrix could be readily detected during single-twitch muscle contractions. Whole body patterns of [Ca(2+)] were monitored in freely moving mice and during epileptic seizures. Furthermore, variations in mitochondrial [Ca(2+)] correlated to behavioral components of the sleep/wake cycle were observed during prolonged whole body recordings of newborn mice. This non-invasive imaging technique opens new avenues for the analysis of Ca(2+) signaling whenever whole body information in freely moving animals is desired, in particular during behavioral and developmental studies.
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Affiliation(s)
- Kelly L. Rogers
- Unité d'Embryologie Moléculaire, CNRS URA 2578, Institut Pasteur, Paris, France
- CEA, Service Hospitalier Frédéric Joliot, Inserm, U 803, Imagerie de l'expression des gènes, Orsay, France
| | - Sandrine Picaud
- Unité d'Embryologie Moléculaire, CNRS URA 2578, Institut Pasteur, Paris, France
| | - Emilie Roncali
- CEA, Service Hospitalier Frédéric Joliot, Inserm, U 803, Imagerie de l'expression des gènes, Orsay, France
| | - Raphaël Boisgard
- CEA, Service Hospitalier Frédéric Joliot, Inserm, U 803, Imagerie de l'expression des gènes, Orsay, France
| | - Cesare Colasante
- Unité d'Embryologie Moléculaire, CNRS URA 2578, Institut Pasteur, Paris, France
| | - Jacques Stinnakre
- Unité d'Embryologie Moléculaire, CNRS URA 2578, Institut Pasteur, Paris, France
| | - Bertrand Tavitian
- CEA, Service Hospitalier Frédéric Joliot, Inserm, U 803, Imagerie de l'expression des gènes, Orsay, France
| | - Philippe Brûlet
- Unité d'Embryologie Moléculaire, CNRS URA 2578, Institut Pasteur, Paris, France
- * To whom correspondence should be addressed. E-mail:
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384
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Héroux M, Hogue M, Lemieux S, Bouvier M. Functional Calcitonin Gene-related Peptide Receptors Are Formed by the Asymmetric Assembly of a Calcitonin Receptor-like Receptor Homo-oligomer and a Monomer of Receptor Activity-modifying Protein-1. J Biol Chem 2007; 282:31610-20. [PMID: 17785463 DOI: 10.1074/jbc.m701790200] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
In addition to their interactions with hetero-trimeric G proteins, seven-transmembrane domain receptors are now known to form multimeric complexes that can include receptor homo- or hetero-oligomers and/or accessory proteins that modulate their activity. The calcitonin gene-related peptide (CGRP) receptor requires the assembly of the seven-transmembrane domain calcitonin receptor-like receptor with the single-transmembrane domain receptor activity-modifying protein-1 to reach the cell surface and be active. However, the relative stoichiometric arrangement of these two proteins within a receptor complex remains unknown. Despite recent advances in the development of protein-protein interactions assays, determining the composition and stoichiometric arrangements of such signaling complexes in living cells remains a challenging task. In the present study, we combined bimolecular fluorescence complementation (BiFC) with bioluminescence resonance energy transfer (BRET) to probe the stoichiometric arrangement of the CGRP receptor complex. Together with BRET competition assays, co-immunoprecipitation experiments, and BiFC imaging, dual BRET/BiFC revealed that functional CGRP receptors result from the association of a homo-oligomer of the calcitonin receptor-like receptor with a monomer of the accessory protein receptor activity-modifying protein-1. In addition to revealing the existence of an unexpected asymmetric oligomeric organization for a G protein-coupled receptor, our study illustrates the usefulness of dual BRET/BiFC as a powerful tool for analyzing constitutive and dynamically regulated multiprotein complexes.
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Affiliation(s)
- Madeleine Héroux
- Department of Biochemistry and Groupe de Recherche Universitaire sur le Médicament, Université de Montréal, Montréal, Québec H3C 3J7, Canada
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385
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De A, Loening AM, Gambhir SS. An improved bioluminescence resonance energy transfer strategy for imaging intracellular events in single cells and living subjects. Cancer Res 2007; 67:7175-83. [PMID: 17671185 PMCID: PMC4161127 DOI: 10.1158/0008-5472.can-06-4623] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Bioluminescence resonance energy transfer (BRET) is currently used for monitoring various intracellular events, including protein-protein interactions, in normal and aberrant signal transduction pathways. However, the BRET vectors currently used lack adequate sensitivity for imaging events of interest from both single living cells and small living subjects. Taking advantage of the critical relationship of BRET efficiency and donor quantum efficiency, we report generation of a novel BRET vector by fusing a GFP(2) acceptor protein with a novel mutant Renilla luciferase donor selected for higher quantum yield. This new BRET vector shows an overall 5.5-fold improvement in the BRET ratio, thereby greatly enhancing the dynamic range of the BRET signal. This new BRET strategy provides a unique platform to assay protein functions from both single live cells and cells located deep within small living subjects. The imaging utility of the new BRET vector is shown by constructing a sensor using two mammalian target of rapamycin pathway proteins (FKBP12 and FRB) that dimerize only in the presence of rapamycin. This new BRET vector should facilitate high-throughput sensitive BRET assays, including studies in single live cells and small living subjects. Applications will include anticancer therapy screening in cell culture and in small living animals.
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Affiliation(s)
- Abhijit De
- Molecular Imaging Program at Stanford and Bio-X Program, Department of Radiology, School of Medicine, Stanford University, Stanford, California 94305, USA
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386
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Inglese J, Johnson RL, Simeonov A, Xia M, Zheng W, Austin CP, Auld DS. High-throughput screening assays for the identification of chemical probes. Nat Chem Biol 2007; 3:466-79. [PMID: 17637779 DOI: 10.1038/nchembio.2007.17] [Citation(s) in RCA: 434] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
High-throughput screening (HTS) assays enable the testing of large numbers of chemical substances for activity in diverse areas of biology. The biological responses measured in HTS assays span isolated biochemical systems containing purified receptors or enzymes to signal transduction pathways and complex networks functioning in cellular environments. This Review addresses factors that need to be considered when implementing assays for HTS and is aimed particularly at investigators new to this field. We discuss assay design strategies, the major detection technologies and examples of HTS assays for common target classes, cellular pathways and simple cellular phenotypes. We conclude with special considerations for configuring sensitive, robust, informative and economically feasible HTS assays.
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MESH Headings
- Animals
- Catalysis
- Chemistry, Pharmaceutical/instrumentation
- Chemistry, Pharmaceutical/methods
- Drug Design
- Drug Evaluation, Preclinical/instrumentation
- Drug Evaluation, Preclinical/methods
- Enzymes/chemistry
- Humans
- Ions
- Kinetics
- Models, Biological
- Models, Chemical
- Receptors, G-Protein-Coupled/metabolism
- Signal Transduction
- Technology, Pharmaceutical/instrumentation
- Technology, Pharmaceutical/methods
- Transcription, Genetic
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Affiliation(s)
- James Inglese
- US National Institutes of Health Chemical Genomics Center, National Institutes of Health, 9800 Medical Center Drive, Bethesda, Maryland 20892-3370, USA.
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387
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Ferré S, Ciruela F, Woods AS, Lluis C, Franco R. Functional relevance of neurotransmitter receptor heteromers in the central nervous system. Trends Neurosci 2007; 30:440-6. [PMID: 17692396 DOI: 10.1016/j.tins.2007.07.001] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Revised: 07/18/2007] [Accepted: 07/19/2007] [Indexed: 10/23/2022]
Abstract
The existence of neurotransmitter receptor heteromers is becoming broadly accepted and their functional significance is being revealed. Heteromerization of neurotransmitter receptors produces functional entities that possess different biochemical characteristics with respect to the individual components of the heteromer. Neurotransmitter receptor heteromers can function as processors of computations that modulate cell signaling. Thus, the quantitative or qualitative aspects of the signaling generated by stimulation of any of the individual receptor units in the heteromer are different from those obtained during coactivation. Furthermore, recent studies demonstrate that some neurotransmitter receptor heteromers can exert an effect as processors of computations that directly modulate both pre- and postsynaptic neurotransmission. This is illustrated by the analysis of striatal receptor heteromers that control striatal glutamatergic neurotransmission.
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Affiliation(s)
- Sergi Ferré
- Behavioral Neuroscience Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Department of Health and Human Services, Baltimore, MD 21224, USA.
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388
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Huang Q, Acha V, Yow R, Schneider E, Sardar DK, Hornsby PJ. Bioluminescence measurements in mice using a skin window. JOURNAL OF BIOMEDICAL OPTICS 2007; 12:054012. [PMID: 17994900 DOI: 10.1117/1.2795567] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Studies of bioluminescence in living animals, such as cell-based biosensor applications, require measurement of light at different wavelengths, but accurate light measurement is impeded by absorption by tissues at wavelengths<600 nm. We present a novel approach to this problem--the use of a plastic window in the skin/body wall of mice--that permits measurements of light produced by bioluminescent cells transplanted into the kidney. The cells coexpressed firefly luciferase (FLuc), a vasopressin receptor--Renilla luciferase (RLuc) fusion protein, and a GFP2-beta-arrestin2 fusion protein. Following coadministration of two luciferase substrates, native coelenterazine and luciferin, bioluminescence is measured via the window using fiber optics and a photon counter. Light emission from the two different luciferases, FLuc and RLuc, is readily distinguishable using appropriate optical filters. When coelenterazine 400a is administered, bioluminescence resonance energy transfer (BRET) occurs between the RLuc and GFP2 fusion proteins and is detected by the use of suitable filters. Following intraperitoneal injection of vasopressin, there is a marked increase in BRET. When rapid and accurate measurement of light from internal organs is required, rather than spatial imaging of bioluminescence, the combination of skin/body wall window and fiber optic light measurement will be advantageous.
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Affiliation(s)
- Qin Huang
- University of Texas Health Science Center, Department of Physiology and Sam and Ann Barshop Institute for Longevity and Aging Studies, San Antonio, Texas 78245, USA
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389
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Tan PK, Wang J, Littler PLH, Wong KK, Sweetnam TA, Keefe W, Nash NR, Reding EC, Piu F, Brann MR, Schiffer HH. Monitoring interactions between receptor tyrosine kinases and their downstream effector proteins in living cells using bioluminescence resonance energy transfer. Mol Pharmacol 2007; 72:1440-6. [PMID: 17715395 DOI: 10.1124/mol.107.039636] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
A limited number of whole-cell assays allow monitoring of receptor tyrosine kinase (RTK) activity in a signaling pathway-specific manner. We present the general use of the bioluminescence resonance energy transfer (BRET) technology to quantitatively study the pharmacology and signaling properties of the receptor tyrosine kinase (RTK) superfamily. RTK BRET-2 assays monitor, in living cells, the specific interaction between RTKs and their effector proteins, which control the activation of specific downstream signaling pathways. A total of 22 BRET assays have been established for nine RTKs derived from four subfamilies [erythroblastic leukemia viral (v-erb-b) oncogene homolog (ErbB), platelet-derived growth factor (PDGF), neurotrophic tyrosine kinase receptor (TRK), vascular endothelial growth factor (VEGF)] monitoring the interactions with five effectors (Grb2, p85, Stat5a, Shc46, PLCgamma1). These interactions are dependent on the RTK kinase activity and autophosphorylation of specific tyrosine residues in the carboxyl terminus. RTK BRET assays are highly sensitive for quantifying ligand-independent (constitutive), agonist-induced, or antagonist-inhibited RTK activity levels. We studied the signaling properties of the PDGF receptor, alpha polypeptide (PDGFRA) isoforms (V561D; D842V and delta842-845) carrying activating mutations identified in gastrointestinal stromal tumors (GIST). All three PDGFRA isoforms are fully constitutively activated, insensitive to the growth factor PDGF-BB, but show differential sensitivity of their constitutive activity to be inhibited by the inhibitor imatinib (Gleevec). Epidermal growth factor receptor (EGFR) BRET structure-function studies identify the tyrosine residues 1068, 1114, and 1148 as the main residues mediating the interaction of EGFR with the adapter protein Grb2. The BRET technology provides an assay platform to study signaling pathway-specific RTK structure-function and will facilitate drug discovery efforts for the identification of novel RTK modulators.
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Affiliation(s)
- Philip K Tan
- ACADIA Pharmaceuticals, 3911 Sorrento Valley Blvd., San Diego, CA 92121, USA
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390
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Villalobos V, Naik S, Piwnica-Worms D. Current State of Imaging Protein-Protein Interactions In Vivo with Genetically Encoded Reporters. Annu Rev Biomed Eng 2007; 9:321-49. [PMID: 17461729 DOI: 10.1146/annurev.bioeng.9.060906.152044] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Signaling pathways regulating proliferation, differentiation, and inflammation are commonly mediated through protein-protein interactions as well as reversible modification (e.g., phosphorylation) of proteins. To facilitate the study of regulated protein-protein interactions in cells and living animals, new imaging tools, many based on optical signals and capable of quantifying protein interactions in vivo, have advanced the study of induced protein interactions and their modification, as well as accelerated the rate of acquisition of these data. In particular, use of protein fragment complementation as a reporter strategy can accurately and rapidly dissect protein interactions with a variety of readouts, including absorbance, fluorescence, and bioluminescence. This review focuses on the development and validation of bioluminescent protein fragment complementation reporters that use either Renilla luciferase or firefly luciferase in vivo. Enhanced luciferase complementation provides a platform for near real-time detection and characterization of regulated and small-molecule-induced protein-protein interactions in intact cells and living animals and enables a wide range of novel applications in drug discovery, chemical genetics, and proteomics research.
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Affiliation(s)
- Victor Villalobos
- Molecular Imaging Center, Mallinckrodt Institute of Radiology, and Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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391
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Abstract
Drugs are named for their primary receptor target and overt action (agonism, antagonism) but the observation of multiple or collateral efficacies emanating from drugs activating a single receptor target is posing a challenge for drug classification and nomenclature. With increasing abilities to detect alteration in cellular function has come the identification of efficacies that are not necessarily manifest in obvious changes in cell response. Specifically, some agonists selectively activate cellular pathways, demonstrate phenotypic behaviour associated with cell type and some antagonists actively induce receptor internalization without activation. In addition, the effects of allosteric modulators can be linked to the nature of the co-binding ligand posing a similar complication in classification and naming. Thus, accurate labels for this new generation of selective drugs may require identification of receptor partners (G-protein type, beta-arrestin) or pathway or, in the case of allosteric modulators, identification of co-binding ligands. The association of distinct phenotypic behaviours with molecules opens the opportunity to better associate clinical effects with distinct pharmacological properties.
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Affiliation(s)
- T P Kenakin
- Biochemical and Cellular Targets, GlaxoSmithKline Research and Development, Research Triangle Park, NC 27709, USA.
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392
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Pfleger KDG, Dalrymple MB, Dromey JR, Eidne KA. Monitoring interactions between G-protein-coupled receptors and β-arrestins. Biochem Soc Trans 2007; 35:764-6. [PMID: 17635143 DOI: 10.1042/bst0350764] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
β-Arrestins 1 and 2 are ubiquitously expressed intracellular adaptor and scaffolding proteins that play important roles in GPCR (G-protein-coupled receptor) desensitization, internalization, intracellular trafficking and G-protein-independent signalling. Recent developments in BRET (bioluminescence resonance energy transfer) technology enable novel insights to be gained from real-time monitoring of GPCR–β-arrestin complexes in live cells for prolonged periods. In concert with confocal microscopy, assays for studying internalization and recycling kinetics such as ELISAs, and techniques for measuring downstream signalling pathways such as those involving MAPKs (mitogen-activated protein kinases), investigators can now use a range of experimental tools to elucidate the ever-expanding roles of β-arrestins in mediating GPCR function.
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Affiliation(s)
- K D G Pfleger
- 7TM Laboratory/Laboratory for Molecular Endocrinology, Western Australian Institute for Medical Research (WAIMR) and Centre for Medical Research, University of Western Australia, Nedlands, Perth, WA 6009, Australia.
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393
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Abstract
Semiconductor quantum dots are inorganic fluorescent nanocrystals that, because of their unique optical properties compared with those of organic fluorophores, have become popular as fluorescent imaging probes. Although external light excitation is typically required for imaging with quantum dots, a new type of quantum dot conjugate has been reported that can luminesce with no need for external excitation. These self-illuminating quantum dot conjugates can be prepared by coupling of commercially available carboxylate-presenting quantum dots to the light-emitting protein Renilla luciferase. When the conjugates are exposed to the luciferase's substrate coelenterazine, the energy released by substrate catabolism is transferred to the quantum dots through bioluminescence resonance energy transfer, leading to quantum dot light emission. This protocol describes step-by-step procedures for the preparation and characterization of these self-illuminating quantum dot conjugates. The preparation process is relatively simple and can be done in less than 2 hours. The availability of self-illuminating quantum dot conjugates will provide many new possibilities for in vivo imaging and detection, such as monitoring of in vivo cell trafficking, multiplex bioluminescence imaging and new quantum dot-based biosensors.
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Affiliation(s)
- Min-Kyung So
- Molecular Imaging Program at Stanford, Department of Radiology, Stanford University School of Medicine, 1201 Welch Road, Stanford, California 94305-5484, USA
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394
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Pfleger KDG, Seeber RM, Eidne KA. Bioluminescence resonance energy transfer (BRET) for the real-time detection of protein-protein interactions. Nat Protoc 2007; 1:337-45. [PMID: 17406254 DOI: 10.1038/nprot.2006.52] [Citation(s) in RCA: 159] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A substantial range of protein-protein interactions can be readily monitored in real time using bioluminescence resonance energy transfer (BRET). The procedure involves heterologous coexpression of fusion proteins, which link proteins of interest to a bioluminescent donor enzyme or acceptor fluorophore. Energy transfer between these proteins is then detected. This protocol encompasses BRET1, BRET2 and the recently described eBRET, including selection of the donor, acceptor and substrate combination, fusion construct generation and validation, cell culture, fluorescence and luminescence detection, BRET detection and data analysis. The protocol is particularly suited to studying protein-protein interactions in live cells (adherent or in suspension), but cell extracts and purified proteins can also be used. Furthermore, although the procedure is illustrated with references to mammalian cell culture conditions, this protocol can be readily used for bacterial or plant studies. Once fusion proteins are generated and validated, the procedure typically takes 48-72 h depending on cell culture requirements.
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Affiliation(s)
- Kevin D G Pfleger
- 7TM Laboratory/Laboratory for Molecular Endocrinology, Western Australian Institute for Medical Research, University of Western Australia, Nedlands, Perth, Western Australia 6009, Australia.
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395
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Huang X, Li L, Qian H, Dong C, Ren J. A resonance energy transfer between chemiluminescent donors and luminescent quantum-dots as acceptors (CRET). Angew Chem Int Ed Engl 2007; 45:5140-3. [PMID: 16826612 DOI: 10.1002/anie.200601196] [Citation(s) in RCA: 198] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Xiangyi Huang
- College of Chemistry & Chemical Engineering, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, China
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396
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Xu X, Soutto M, Xie Q, Servick S, Subramanian C, von Arnim AG, Johnson CH. Imaging protein interactions with bioluminescence resonance energy transfer (BRET) in plant and mammalian cells and tissues. Proc Natl Acad Sci U S A 2007; 104:10264-9. [PMID: 17551013 PMCID: PMC1891211 DOI: 10.1073/pnas.0701987104] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2007] [Indexed: 11/18/2022] Open
Abstract
FRET is a well established method for cellular and subcellular imaging of protein interactions. However, FRET obligatorily necessitates fluorescence excitation with its concomitant problems of photobleaching, autofluorescence, phototoxicity, and undesirable stimulation of photobiological processes. A sister technique, bioluminescence resonance energy transfer (BRET), avoids these problems because it uses enzyme-catalyzed luminescence; however, BRET signals usually have been too dim to image effectively in the past. Using a new generation electron bombardment-charge-coupled device camera coupled to an image splitter, we demonstrate that BRET can be used to image protein interactions in plant and animal cells and in tissues; even subcellular imaging is possible. We have applied this technology to image two different protein interactions: (i) dimerization of the developmental regulator, COP1, in plant seedlings; and (ii) CCAAT/enhancer binding protein alpha (C/EBPalpha) in the mammalian nucleus. This advance heralds a host of applications for imaging without fluorescent excitation and its consequent limitations.
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Affiliation(s)
- Xiaodong Xu
- *Department of Biological Sciences, Box 1634-B, Vanderbilt University, Nashville, TN 37235; and
| | - Mohammed Soutto
- *Department of Biological Sciences, Box 1634-B, Vanderbilt University, Nashville, TN 37235; and
| | - Qiguang Xie
- *Department of Biological Sciences, Box 1634-B, Vanderbilt University, Nashville, TN 37235; and
| | - Stein Servick
- *Department of Biological Sciences, Box 1634-B, Vanderbilt University, Nashville, TN 37235; and
| | - Chitra Subramanian
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996
| | - Albrecht G. von Arnim
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996
| | - Carl Hirschie Johnson
- *Department of Biological Sciences, Box 1634-B, Vanderbilt University, Nashville, TN 37235; and
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397
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Zhang Y, So MK, Loening AM, Yao H, Gambhir SS, Rao J. HaloTag protein-mediated site-specific conjugation of bioluminescent proteins to quantum dots. Angew Chem Int Ed Engl 2007; 45:4936-40. [PMID: 16807952 DOI: 10.1002/anie.200601197] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Yan Zhang
- Molecular Imaging Program at Stanford, Department of Radiology, Stanford University School of Medicine, 1201 Welch Road, Stanford, CA 94305-5484, USA
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398
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Dupré DJ, Robitaille M, Richer M, Ethier N, Mamarbachi AM, Hébert TE. Dopamine Receptor-interacting Protein 78 Acts as a Molecular Chaperone for Gγ Subunits before Assembly with Gβ. J Biol Chem 2007; 282:13703-15. [PMID: 17363375 DOI: 10.1074/jbc.m608846200] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Heterotrimeric G proteins play a central role in intracellular communication mediated by extracellular signals, and both Galpha and Gbetagamma subunits regulate effectors downstream of activated receptors. The particular constituents of the G protein heterotrimer affect both specificity and efficiency of signal transduction. However, little is known about mechanistic aspects of G protein assembly in the cell that would certainly contribute to formation of heterotrimers of specific composition. It was recently shown that phosducin-like protein (PhLP) modulated both Gbetagamma expression and subsequent signaling by chaperoning nascent Gbeta and facilitating heterodimer formation with Ggamma subunits (Lukov, G. L., Hu, T., McLaughlin, J. N., Hamm, H. E., and Willardson, B. M. (2005) EMBO J. 24, 1965-1975; Humrich, J., Bermel, C., Bunemann, M., Harmark, L., Frost, R., Quitterer, U., and Lohse, M. J. (2005) J. Biol. Chem. 280, 20042-20050). Here we demonstrate using a variety of techniques that DRiP78, an endoplasmic reticulum resident protein known to regulate the trafficking of several seven transmembrane receptors, interacts specifically with the Ggamma subunit but not Gbeta or Galpha subunits. Furthermore, we demonstrate that DRiP78 and the Gbeta subunit can compete for the Ggamma subunit. DRiP78 also protects Ggamma from degradation until a stable partner such as Gbeta is provided. Furthermore, DRiP78 interaction may represent a mechanism for assembly of specific Gbetagamma heterodimers, as selectivity was observed among Ggamma isoforms for interaction with DRiP78 depending on the presence of particular Gbeta subunits. Interestingly, we could detect an interaction between DRiP78 and PhLP, suggesting a role of DRiP78 in the assembly of Gbetagamma by linking Ggamma to PhLP.Gbeta complexes. Our results, therefore, suggest a role of DRiP78 as a chaperone in the assembly of Gbetagamma subunits of the G protein.
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Affiliation(s)
- Denis J Dupré
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, H3G 1Y6, Canada
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399
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Laudet B, Prudent R, Filhol O, Cochet C. Des agents thérapeutiques ciblant des interactions protéine-protéine. Med Sci (Paris) 2007; 23:273-8. [PMID: 17349288 DOI: 10.1051/medsci/2007233273] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Protein-protein interactions have a key role in transduction pathways that regulate many cellular functions. Structural and functional properties of protein-protein interface are now better understood, therefore offering attractive opportunities for therapeutic intervention. Developping small molecules that modulate protein-protein interactions is challenging. Nethertheless, significant progress in this endeavour has been made on several fronts. Here, we use few illustrative examples to summarize recent work in this emerging field.
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Affiliation(s)
- Béatrice Laudet
- Inserm U873, Institut de Recherches en Technologies et Sciences pour le Vivant, CEA Grenoble, 17, rue des Martyrs, 38054 Grenoble Cedex 9, France
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400
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Lopez-Gimenez JF, Canals M, Pediani JD, Milligan G. The alpha1b-adrenoceptor exists as a higher-order oligomer: effective oligomerization is required for receptor maturation, surface delivery, and function. Mol Pharmacol 2007; 71:1015-29. [PMID: 17220353 DOI: 10.1124/mol.106.033035] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Approaches to identify G protein-coupled receptor oligomers rather than dimers have been lacking. Using concatamers of fluorescent proteins, we established conditions to monitor sequential three-color fluorescence resonance energy transfer (3-FRET) and used these to detect oligomeric complexes of the alpha(1b)-adrenoceptor in single living cells. Mutation of putative key hydrophobic residues in transmembrane domains I and IV resulted in substantial reduction of sequential 3-FRET and was associated with lack of protein maturation, prevention of plasma membrane delivery, and elimination of signaling function. Although these mutations prevented cell surface delivery, bimolecular fluorescence complementation studies indicated that they did not ablate protein-protein interactions and confirmed endoplasmic reticulum/Golgi retention of the transmembrane domain I plus transmembrane domain IV mutated receptor. The transmembrane domain I plus transmembrane domain IV mutated receptor was a "dominant-negative" in blocking cell surface delivery of the wild-type receptor. Mutations only in transmembrane domain I did not result in a reduction in 3-FRET, whereas restricting mutation to transmembrane domain IV did result in reduced 3-FRET. Mutations in either transmembrane domain I or transmembrane domain IV, however, were sufficient to eliminate cell surface delivery. Terminal N-glycosylation is insufficient to determine cell surface delivery because both transmembrane domain I and transmembrane domain IV mutants matured as effectively as the wild-type receptor. These data indicate that the alpha(1b)-adrenoceptor is able to form oligomeric rather than only simple dimeric complexes and that disruption of effective oligomerization by introducing mutations into transmembrane domain IV has profound consequences for cell surface delivery and function.
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MESH Headings
- Cell Line
- Cell Membrane/metabolism
- Dimerization
- Fluorescence Resonance Energy Transfer
- Glycosylation
- Humans
- Mutagenesis, Site-Directed
- Protein Transport
- Receptors, Adrenergic, alpha-1/chemistry
- Receptors, Adrenergic, alpha-1/genetics
- Receptors, Adrenergic, alpha-1/metabolism
- Receptors, Adrenergic, alpha-1/physiology
- Receptors, Cell Surface
- Transfection
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Affiliation(s)
- Juan F Lopez-Gimenez
- Molecular Pharmacology Group, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, Scotland, United Kingdom
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