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Durhan ST, Sezer EN, Son CD, Baloglu FK. Fast Screening of Protein-Protein Interactions Using Förster Resonance Energy Transfer (FRET-) Based Fluorescence Plate Reader Assay in Live Cells. APPLIED SPECTROSCOPY 2023; 77:292-302. [PMID: 36345563 DOI: 10.1177/00037028221140914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Protein-protein interactions (PPIs) have great importance for intracellular signal transduction and sustaining the homeostasis of an organism. Thus, the identification of PPIs is necessary to better understand the downstream signaling functions of the proteins in healthy and pathological conditions. Förster resonance energy transfer (FRET) between fluorescent proteins (FPs) is a powerful tool for detecting PPIs in living cells. In literature, FRET analysis methods such as donor photobleaching (FLIM), acceptor photobleaching, spectral imaging, and the three-filter cube method (sensitized emission) are abundantly applied to investigate PPIs; however, they require various expensive instrumentations, and their calculation methods are very time consuming. Since confocal microscopy applications and live cell-based techniques of FRET are very costly, scientists sometimes prefer plate readers for FRET experiments. However, plate reader applications also have many disadvantages and considerations compared to confocal fluorescence microscopy, and complex calculation procedures should be performed. To overcome these problems, we propose a FRET-based high-throughput assay method with a standard monochromator-based microplate reader, which is generally available in most biochemistry laboratories, and an alternative calculation procedure. This rapid, low cost, and effective analysis method enables the scientists to prescreen PPIs in living cells as a preliminary study and quick glance at the experiment before preparing the whole experimental setup with the expensive instrumentations. Additionally, the alternative calculation procedure provides the FRET area comparison without complex bleed-through calculations in a non-conventional manner by shortening the analysis processes with this quick and uncomplicated spectral representation.
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Affiliation(s)
- Seyda Tugce Durhan
- Department of Biological Sciences, 52984Middle East Technical University, Ankara, Turkey
| | - Enise Nalli Sezer
- Department of Biological Sciences, 52984Middle East Technical University, Ankara, Turkey
| | - Cagdas Devrim Son
- Department of Biological Sciences, 52984Middle East Technical University, Ankara, Turkey
| | - Fatma Kucuk Baloglu
- Department of Biological Sciences, 52984Middle East Technical University, Ankara, Turkey
- Department of Biology, 187438Giresun University, Giresun, Turkey
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Patwardhan A, Cheng N, Trejo J. Post-Translational Modifications of G Protein-Coupled Receptors Control Cellular Signaling Dynamics in Space and Time. Pharmacol Rev 2021; 73:120-151. [PMID: 33268549 PMCID: PMC7736832 DOI: 10.1124/pharmrev.120.000082] [Citation(s) in RCA: 75] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are a large family comprising >800 signaling receptors that regulate numerous cellular and physiologic responses. GPCRs have been implicated in numerous diseases and represent the largest class of drug targets. Although advances in GPCR structure and pharmacology have improved drug discovery, the regulation of GPCR function by diverse post-translational modifications (PTMs) has received minimal attention. Over 200 PTMs are known to exist in mammalian cells, yet only a few have been reported for GPCRs. Early studies revealed phosphorylation as a major regulator of GPCR signaling, whereas later reports implicated a function for ubiquitination, glycosylation, and palmitoylation in GPCR biology. Although our knowledge of GPCR phosphorylation is extensive, our knowledge of the modifying enzymes, regulation, and function of other GPCR PTMs is limited. In this review we provide a comprehensive overview of GPCR post-translational modifications with a greater focus on new discoveries. We discuss the subcellular location and regulatory mechanisms that control post-translational modifications of GPCRs. The functional implications of newly discovered GPCR PTMs on receptor folding, biosynthesis, endocytic trafficking, dimerization, compartmentalized signaling, and biased signaling are also provided. Methods to detect and study GPCR PTMs as well as PTM crosstalk are further highlighted. Finally, we conclude with a discussion of the implications of GPCR PTMs in human disease and their importance for drug discovery. SIGNIFICANCE STATEMENT: Post-translational modification of G protein-coupled receptors (GPCRs) controls all aspects of receptor function; however, the detection and study of diverse types of GPCR modifications are limited. A thorough understanding of the role and mechanisms by which diverse post-translational modifications regulate GPCR signaling and trafficking is essential for understanding dysregulated mechanisms in disease and for improving and refining drug development for GPCRs.
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Affiliation(s)
- Anand Patwardhan
- Department of Pharmacology and the Biomedical Sciences Graduate Program, School of Medicine, University of California, San Diego, La Jolla, California
| | - Norton Cheng
- Department of Pharmacology and the Biomedical Sciences Graduate Program, School of Medicine, University of California, San Diego, La Jolla, California
| | - JoAnn Trejo
- Department of Pharmacology and the Biomedical Sciences Graduate Program, School of Medicine, University of California, San Diego, La Jolla, California
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Nagi K, Kaur S, Bai Y, Shenoy SK. In-frame fusion of SUMO1 enhances βarrestin2's association with activated GPCRs as well as with nuclear pore complexes. Cell Signal 2020; 75:109759. [PMID: 32860951 DOI: 10.1016/j.cellsig.2020.109759] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 08/17/2020] [Accepted: 08/22/2020] [Indexed: 01/11/2023]
Abstract
Small ubiquitin like modifier (SUMO) conjugation or SUMOylation of βarrestin2 promotes its association with the clathrin adaptor protein AP2 and facilitates rapid β2 adrenergic receptor (β2AR) internalization. However, disruption of the consensus SUMOylation site in βarrestin2, did not prevent βarrestin2's association with activated β2ARs, dopamine D2 receptors (D2Rs), angiotensin type 1a receptors (AT1aRs) and V2 vasopressin receptors (V2Rs). To address the role of SUMOylation in the trafficking of βarrestin and GPCR complexes, we generated and characterized a yellow fluorescent protein (YFP) tagged βarrestin2-SUMO1 chimeric protein, which is resistant to de-SUMOylation. In HEK-293 cells, YFP-SUMO1 predominantly localized in the nucleus, whereas YFP-βarrestin2 is cytoplasmic. YFP-βarrestin2-SUMO1 in addition to being cytoplasmic, is localized at the nuclear membrane. Nonetheless, βarrestin2-SUMO1 associated robustly with agonist-activated β2ARs as evaluated by co-immunoprecipitation, confocal microscopy and bioluminescence resonance energy transfer (BRET). βarrestin2-SUMO1 associated strongly with the D2R, which forms transient complexes with βarrestin2. But, βarrestin2-SUMO1 and βarrestin2 showed equivalent binding with the V2R, which forms stable complexes with βarrestin2. βarrestin2 expression level directly correlated with the steady state levels of the unmodified form of RanGAP1, which upon SUMOylation associates with nuclear membrane. On the other hand, βarrestin2-SUMO1 not only localized at the nuclear membrane, but also formed a macromolecular complex with RanGAP1. Taken together, our data suggest that SUMOylation of βarrestin2 promotes its protein interactions at both cell and nuclear membranes. Furthermore, βarrestin2-SUMO1 presents as a useful tool to characterize βarrestin2 recruitment to GPCRs, which form transient and unstable complex with βarrestin2.
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Affiliation(s)
- Karim Nagi
- Department of Medicine, Division of Cardiology, Duke University Medical Center, Durham, NC 27710, USA; College of Medicine, QU Health, Qatar University, Doha, Qatar
| | - Suneet Kaur
- Department of Medicine, Division of Cardiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Yushi Bai
- Department of Medicine, Division of Cardiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Sudha K Shenoy
- Department of Medicine, Division of Cardiology, Duke University Medical Center, Durham, NC 27710, USA; Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA.
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Toth K, Nagi K, Slosky LM, Rochelle L, Ray C, Kaur S, Shenoy SK, Caron MG, Barak LS. Encoding the β-Arrestin Trafficking Fate of Ghrelin Receptor GHSR1a: C-Tail-Independent Molecular Determinants in GPCRs. ACS Pharmacol Transl Sci 2019; 2:230-246. [PMID: 32259059 DOI: 10.1021/acsptsci.9b00018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Indexed: 12/14/2022]
Abstract
G-protein-coupled receptors (GPCRs) can bias signaling through distinct biochemical pathways that originate from G-protein/receptor and β-arrestin/receptor complexes. Receptor conformations supporting β-arrestin engagement depend on multiple receptor determinants. Using ghrelin receptor GHR1a, we demonstrate by bioluminescence resonance energy transfer and fluorescence microscopy a critical role for its second intracellular loop 2 (ICL2) domain in stabilizing β-arrestin/GHSR1a core interactions and determining receptor trafficking fate. We validate our findings in ICL2 gain- and loss-of-function experiments assessing β-arrestin and ubiquitin-dependent internalization of the CC chemokine receptor, CCR1. Like all CC and CXC subfamily chemokine receptors, CCR1 lacks a critical proline residue found in the ICL2 consensus domain of rhodopsin-family GPCRs. Our study indicates that ICL2, C-tail determinants, and the orthosteric binding pocket that regulates β-arrestin/receptor complex stability are sufficient to encode a broad repertoire of the trafficking fates observed for rhodopsin-family GPCRs, suggesting they provide the essential elements for regulating a large fraction of β-arrestin signaling bias.
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Affiliation(s)
- Krisztian Toth
- Departments of Cell Biology, Neurobiology, and Medicine, Duke University Medical Center, Durham, North Carolina 27710, United States.,Pharmaceutical Sciences, Campbell University, Buies Creek, North Carolina 27506, United States
| | - Karim Nagi
- Departments of Cell Biology, Neurobiology, and Medicine, Duke University Medical Center, Durham, North Carolina 27710, United States.,College of Medicine, Qatar University, P.O. Box 2713, Doha, Qatar
| | - Lauren M Slosky
- Departments of Cell Biology, Neurobiology, and Medicine, Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Lauren Rochelle
- Departments of Cell Biology, Neurobiology, and Medicine, Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Caroline Ray
- Departments of Cell Biology, Neurobiology, and Medicine, Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Suneet Kaur
- Departments of Cell Biology, Neurobiology, and Medicine, Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Sudha K Shenoy
- Departments of Cell Biology, Neurobiology, and Medicine, Duke University Medical Center, Durham, North Carolina 27710, United States.,Departments of Cell Biology, Neurobiology, and Medicine, Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Marc G Caron
- Departments of Cell Biology, Neurobiology, and Medicine, Duke University Medical Center, Durham, North Carolina 27710, United States.,Departments of Cell Biology, Neurobiology, and Medicine, Duke University Medical Center, Durham, North Carolina 27710, United States.,Departments of Cell Biology, Neurobiology, and Medicine, Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Larry S Barak
- Departments of Cell Biology, Neurobiology, and Medicine, Duke University Medical Center, Durham, North Carolina 27710, United States
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