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Ripoll L, von Zastrow M, Blythe EE. Intersection of GPCR trafficking and cAMP signaling at endomembranes. J Cell Biol 2025; 224:e202409027. [PMID: 40131202 PMCID: PMC11934914 DOI: 10.1083/jcb.202409027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2024] [Revised: 02/11/2025] [Accepted: 03/13/2025] [Indexed: 03/26/2025] Open
Abstract
GPCRs comprise the largest family of signaling receptors and control essentially every physiological process. Many biochemical reactions underlying GPCR signaling are now elucidated to atomic resolution in cell-free preparations, but how elemental signaling reactions are organized in intact cells remains less clear. Significant progress has been made toward bridging this knowledge gap by leveraging new tools and methodologies enabling the experimental detection, localization, and manipulation of defined signaling reactions in living cells. Here, we chronicle advances at this rapidly moving frontier of molecular and cell biology, focusing on GPCR-initiated signaling through the classical cAMP pathway as an example. We begin with a brief review of established concepts. We then discuss the still-evolving understanding that ligand-induced GPCR signaling occurs from endomembranes as well as the plasmalemma, and that this enables cells to flexibly sculpt downstream signaling responses in both space and time. Finally, we note some key limitations of the present understanding and propose some promising directions for future investigation.
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Affiliation(s)
- Léa Ripoll
- Department of Psychiatry and Behavioral Sciences, University of California, San Francisco, San Francisco, CA, USA
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, USA
| | - Mark von Zastrow
- Department of Psychiatry and Behavioral Sciences, University of California, San Francisco, San Francisco, CA, USA
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, USA
- Quantitative Biology Institute, University of California, San Francisco, San Francisco, CA, USA
| | - Emily E. Blythe
- Department of Psychiatry and Behavioral Sciences, University of California, San Francisco, San Francisco, CA, USA
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, USA
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2
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Reed EB, Sitikov A, Shin KWD, Hamanaka RB, Cetin-Atalay R, Mutlu GM, Mongin AA, Dulin NO. Gα12 and Gα13 proteins are required for transforming growth factor-β-induced myofibroblast differentiation. Biochem J 2024; 481:1937-1948. [PMID: 39621448 DOI: 10.1042/bcj20240317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2024] [Revised: 11/13/2024] [Accepted: 12/02/2024] [Indexed: 12/14/2024]
Abstract
Myofibroblast differentiation, characterized by accumulation of cytoskeletal and extracellular matrix proteins by fibroblasts, is a key process in wound healing and pathogenesis of tissue fibrosis. Transforming growth factor-β (TGF-β) is the most powerful known driver of myofibroblast differentiation. TGF-β signals through transmembrane receptor serine/threonine kinases that phosphorylate Smad transcription factors (Smad2/3) leading to activation of transcription of target genes. Heterotrimeric G proteins mediate distinct signaling from seven-transmembrane G protein coupled receptors, which are not known to be linked to Smad activation. We tested whether G protein signaling plays any role in TGF-β-induced myofibroblast differentiation, using primary cultured human lung fibroblasts. Activation of Gαs by cholera toxin blocked TGF-β-induced myofibroblast differentiation without affecting Smad2/3 phosphorylation. Neither inhibition of Gαi by pertussis toxin nor siRNA-mediated combined knockdown of Gαq and Gα11 had a significant effect on TGF-β-induced myofibroblast differentiation. In contrast, combined knockdown of Gα12 and Gα13 significantly inhibited TGF-β-stimulated expression of myofibroblast marker proteins (collagen-1, fibronectin, smooth-muscle α-actin), with siGα12 being significantly more potent than siGα13. Mechanistically, combined knockdown of Gα12 and Gα13 resulted in substantially reduced phosphorylation of Smad2 and Smad3 in response to TGF-β, which was accompanied by a significant decrease in the expression of TGF-β receptors (TGFBR1, TGFBR2) and of Smad3. Thus, our study uncovers a novel role of Gα12/13 proteins in the control of TGF-β signaling and myofibroblast differentiation.
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Affiliation(s)
- Eleanor B Reed
- Department of Medicine, Section of Pulmonary and Critical Care Medicine, The University of Chicago, Chicago, IL, U.S.A
| | - Albert Sitikov
- Department of Medicine, Section of Pulmonary and Critical Care Medicine, The University of Chicago, Chicago, IL, U.S.A
| | - Kun Woo D Shin
- Department of Medicine, Section of Pulmonary and Critical Care Medicine, The University of Chicago, Chicago, IL, U.S.A
| | - Robert B Hamanaka
- Department of Medicine, Section of Pulmonary and Critical Care Medicine, The University of Chicago, Chicago, IL, U.S.A
| | - Rengül Cetin-Atalay
- Department of Medicine, Section of Pulmonary and Critical Care Medicine, The University of Chicago, Chicago, IL, U.S.A
| | - Gökhan M Mutlu
- Department of Medicine, Section of Pulmonary and Critical Care Medicine, The University of Chicago, Chicago, IL, U.S.A
| | - Alexander A Mongin
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, U.S.A
| | - Nickolai O Dulin
- Department of Medicine, Section of Pulmonary and Critical Care Medicine, The University of Chicago, Chicago, IL, U.S.A
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3
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Reed EB, Sitikov A, Hamanaka RB, Cetin-Atalay R, Mutlu GM, Mongin AA, Dulin NO. Critical role of Gα12 and Gα13 proteins in TGF-β-induced myofibroblast differentiation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.29.596473. [PMID: 38854083 PMCID: PMC11160726 DOI: 10.1101/2024.05.29.596473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Myofibroblast differentiation, characterized by accumulation of cytoskeletal and extracellular matrix proteins by fibroblasts, is a key process in wound healing and pathogenesis of tissue fibrosis. Transforming growth factor-β (TGF-β) is the most powerful known driver of myofibroblast differentiation. TGF-β signals through transmembrane receptor serine/threonine kinases that phosphorylate Smad transcription factors (Smad2/3) leading to activation of transcription of target genes. Heterotrimeric G proteins mediate a distinct signaling from seven-transmembrane G protein coupled receptors, not commonly linked to Smad activation. We asked if G protein signaling plays any role in TGF-β-induced myofibroblast differentiation, using primary cultured human lung fibroblasts. Activation of Gαs by cholera toxin blocked TGF-β-induced myofibroblast differentiation without affecting Smad2/3 phosphorylation. Inhibition of Gαi by pertussis toxin, or siRNA-mediated combined knockdown of Gαq and Gα11 had no significant effect on TGF-β-induced myofibroblast differentiation. A combined knockdown of Gα12 and Gα13 resulted in a drastic inhibition of TGF-β-stimulated expression of myofibroblast marker proteins (collagen-1, fibronectin, smooth-muscle α-actin), with siGα12 being significantly more potent than siGα13. Mechanistically, a combined knockdown of Gα12 and Gα13 resulted in a substantially reduced phosphorylation of Smad2 and Smad3 in response to TGF-β, which was accompanied by a significant decrease in the expression of TGFβ receptors (TGFBR1, TGFBR2) and of Smad3 under siGα12/13 conditions. In conclusion, our study uncovers a novel role of Gα12/13 proteins in the control of TGF-β signaling and myofibroblast differentiation.
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Affiliation(s)
- Eleanor B. Reed
- Department of Medicine, Section of Pulmonary and Critical Care Medicine, The University of Chicago, Chicago, IL, USA
| | - Albert Sitikov
- Department of Medicine, Section of Pulmonary and Critical Care Medicine, The University of Chicago, Chicago, IL, USA
| | - Robert B. Hamanaka
- Department of Medicine, Section of Pulmonary and Critical Care Medicine, The University of Chicago, Chicago, IL, USA
| | - Rengül Cetin-Atalay
- Department of Medicine, Section of Pulmonary and Critical Care Medicine, The University of Chicago, Chicago, IL, USA
| | - Gökhan M. Mutlu
- Department of Medicine, Section of Pulmonary and Critical Care Medicine, The University of Chicago, Chicago, IL, USA
| | - Alexander A. Mongin
- Department of Neuroscience & Experimental Therapeutics, Albany Medical College, Albany, NY
| | - Nickolai O. Dulin
- Department of Medicine, Section of Pulmonary and Critical Care Medicine, The University of Chicago, Chicago, IL, USA
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4
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Nürnberg B, Beer-Hammer S, Reisinger E, Leiss V. Non-canonical G protein signaling. Pharmacol Ther 2024; 255:108589. [PMID: 38295906 DOI: 10.1016/j.pharmthera.2024.108589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 12/18/2023] [Accepted: 01/08/2024] [Indexed: 02/17/2024]
Abstract
The original paradigm of classical - also referred to as canonical - cellular signal transduction of heterotrimeric G proteins (G protein) is defined by a hierarchical, orthograde interaction of three players: the agonist-activated G protein-coupled receptor (GPCR), which activates the transducing G protein, that in turn regulates its intracellular effectors. This receptor-transducer-effector concept was extended by the identification of regulators and adapters such as the regulators of G protein signaling (RGS), receptor kinases like βARK, or GPCR-interacting arrestin adapters that are integrated into this canonical signaling process at different levels to enable fine-tuning. Finally, the identification of atypical signaling mechanisms of classical regulators, together with the discovery of novel modulators, added a new and fascinating dimension to the cellular G protein signal transduction. This heterogeneous group of accessory G protein modulators was coined "activators of G protein signaling" (AGS) proteins and plays distinct roles in canonical and non-canonical G protein signaling pathways. AGS proteins contribute to the control of essential cellular functions such as cell development and division, intracellular transport processes, secretion, autophagy or cell movements. As such, they are involved in numerous biological processes that are crucial for diseases, like diabetes mellitus, cancer, and stroke, which represent major health burdens. Although the identification of a large number of non-canonical G protein signaling pathways has broadened the spectrum of this cellular communication system, their underlying mechanisms, functions, and biological effects are poorly understood. In this review, we highlight and discuss atypical G protein-dependent signaling mechanisms with a focus on inhibitory G proteins (Gi) involved in canonical and non-canonical signal transduction, review recent developments and open questions, address the potential of new approaches for targeted pharmacological interventions.
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Affiliation(s)
- Bernd Nürnberg
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute of Experimental and Clinical Pharmacology and Pharmacogenomics, and ICePhA Mouse Clinic, University of Tübingen, Wilhelmstraße 56, D-72074 Tübingen, Germany.
| | - Sandra Beer-Hammer
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute of Experimental and Clinical Pharmacology and Pharmacogenomics, and ICePhA Mouse Clinic, University of Tübingen, Wilhelmstraße 56, D-72074 Tübingen, Germany
| | - Ellen Reisinger
- Gene Therapy for Hearing Impairment Group, Department of Otolaryngology - Head & Neck Surgery, University of Tübingen Medical Center, Elfriede-Aulhorn-Straße 5, D-72076 Tübingen, Germany
| | - Veronika Leiss
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute of Experimental and Clinical Pharmacology and Pharmacogenomics, and ICePhA Mouse Clinic, University of Tübingen, Wilhelmstraße 56, D-72074 Tübingen, Germany
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5
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Li QY, Li Y, Inoue A, Lu R, Xu A, Ruan KH. Reversing thromboxane A2 receptor activity from calcium to cAMP signaling by shifting Gαq to Gαs covalently linked to the receptor. Biochem Eng J 2022. [DOI: 10.1016/j.bej.2022.108465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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von Zastrow M. Proteomic Approaches to Investigate Regulated Trafficking and Signaling of G Protein-Coupled Receptors. Mol Pharmacol 2021; 99:392-398. [PMID: 33361190 PMCID: PMC8058503 DOI: 10.1124/molpharm.120.000178] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 11/09/2020] [Indexed: 12/14/2022] Open
Abstract
Advances in proteomic methodologies based on quantitative mass spectrometry are now transforming pharmacology and experimental biology more broadly. The present review will discuss several examples based on work in the author's laboratory, which focuses on delineating relationships between G protein-coupled receptor signaling and trafficking in the endocytic network. The examples highlighted correspond to those discussed in a talk presented at the 2019 EB/ASPET meeting, which was organized by Professor Joe Beavo to commemorate his receipt of the Julius Axelrod Award. SIGNIFICANCE STATEMENT: GPCRs are allosteric machines that signal by interacting with other cellular proteins, and this, in turn, is determined by a complex interplay between the biochemical, subcellular localization, and membrane trafficking properties of receptors relative to transducer and regulatory proteins. The present minireview highlights recent advances and challenges in elucidating this dynamic cell biology and toward delineating the cellular basis of drug action at the level of defined GPCR interaction networks using proteomic approaches enabled by quantitative mass spectrometry.
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Affiliation(s)
- Mark von Zastrow
- Departments of Cellular and Molecular Pharmacology, and Psychiatry and Behavioral Science, San Francisco School of Medicine, and Quantitative Biology Institute, University of California, San Francisco, California
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Höring C, Seibel U, Tropmann K, Grätz L, Mönnich D, Pitzl S, Bernhardt G, Pockes S, Strasser A. A Dynamic, Split-Luciferase-Based Mini-G Protein Sensor to Functionally Characterize Ligands at All Four Histamine Receptor Subtypes. Int J Mol Sci 2020; 21:ijms21228440. [PMID: 33182741 PMCID: PMC7698210 DOI: 10.3390/ijms21228440] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Revised: 11/06/2020] [Accepted: 11/08/2020] [Indexed: 02/06/2023] Open
Abstract
In drug discovery, assays with proximal readout are of great importance to study target-specific effects of potential drug candidates. In the field of G protein-coupled receptors (GPCRs), the determination of GPCR-G protein interactions and G protein activation by means of radiolabeled GTP analogs ([35S]GTPγS, [γ-32P]GTP) has widely been used for this purpose. Since we were repeatedly faced with insufficient quality of radiolabeled nucleotides, there was a requirement to implement a novel proximal functional assay for the routine characterization of putative histamine receptor ligands. We applied the split-NanoLuc to the four histamine receptor subtypes (H1R, H2R, H3R, H4R) and recently engineered minimal G (mini-G) proteins. Using this method, the functional response upon receptor activation was monitored in real-time and the four mini-G sensors were evaluated by investigating selected standard (inverse) agonists and antagonists. All potencies and efficacies of the studied ligands were in concordance with literature data. Further, we demonstrated a significant positive correlation of the signal amplitude and the mini-G protein expression level in the case of the H2R, but not for the H1R or the H3R. The pEC50 values of histamine obtained under different mini-G expression levels were consistent. Moreover, we obtained excellent dynamic ranges (Z’ factor) and the signal spans were improved for all receptor subtypes in comparison to the previously performed [35S]GTPγS binding assay.
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Affiliation(s)
- Carina Höring
- Correspondence: (C.H.); , (A.S.); Tel.: +49-941-943-4748 (C.H.); +49-941-943-4821 (A.S.)
| | | | | | | | | | | | | | | | - Andrea Strasser
- Correspondence: (C.H.); , (A.S.); Tel.: +49-941-943-4748 (C.H.); +49-941-943-4821 (A.S.)
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Deal J, Pleshinger DJ, Johnson SC, Leavesley SJ, Rich TC. Milestones in the development and implementation of FRET-based sensors of intracellular signals: A biological perspective of the history of FRET. Cell Signal 2020; 75:109769. [PMID: 32898611 DOI: 10.1016/j.cellsig.2020.109769] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 08/28/2020] [Accepted: 08/31/2020] [Indexed: 01/24/2023]
Abstract
Fӧrster resonance energy transfer (FRET) has been described for more than a century. FRET has become a mainstay for the study of protein localization in living cells and tissues. It has also become widely used in the fields that comprise cellular signaling. FRET-based probes have been developed to monitor second messenger signals, the phosphorylation state of peptides and proteins, and subsequent cellular responses. Here, we discuss the milestones that led to FRET becoming a widely used tool for the study of biological systems: the theoretical description of FRET, the insight to use FRET as a molecular ruler, and the isolation and genetic modification of green fluorescent protein (GFP). Each of these milestones were critical to the development of a myriad of FRET-based probes and reporters in common use today. FRET-probes offer a unique opportunity to interrogate second messenger signals and subsequent protein phosphorylation - and perhaps the most effective approach for study of cAMP/PKA pathways. As such, FRET probes are widely used in the study of intracellular signaling pathways. Yet, somehow, the potential of FRET-based probes to provide windows through which we can visualize complex cellular signaling systems has not been fully reached. Hence we conclude by discussing the technical challenges to be overcome if FRET-based probes are to live up to their potential for the study of complex signaling networks.
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Affiliation(s)
- J Deal
- Basic Medical Sciences Graduate Program, University of South Alabama, Mobile, AL 36688, USA; Center for Lung Biology, Departments of Biomolecular Engineering, University of South Alabama, Mobile, AL 36688, USA
| | - D J Pleshinger
- Center for Lung Biology, Departments of Biomolecular Engineering, University of South Alabama, Mobile, AL 36688, USA; Pharmacology and Biomolecular Engineering, University of South Alabama, Mobile, AL 36688, USA
| | - S C Johnson
- Basic Medical Sciences Graduate Program, University of South Alabama, Mobile, AL 36688, USA; Pharmacology and Biomolecular Engineering, University of South Alabama, Mobile, AL 36688, USA
| | - S J Leavesley
- Basic Medical Sciences Graduate Program, University of South Alabama, Mobile, AL 36688, USA; Center for Lung Biology, Departments of Biomolecular Engineering, University of South Alabama, Mobile, AL 36688, USA; Pharmacology and Biomolecular Engineering, University of South Alabama, Mobile, AL 36688, USA; Chemical and Biomolecular Engineering, University of South Alabama, Mobile, AL 36688, USA
| | - T C Rich
- Basic Medical Sciences Graduate Program, University of South Alabama, Mobile, AL 36688, USA; Center for Lung Biology, Departments of Biomolecular Engineering, University of South Alabama, Mobile, AL 36688, USA; Pharmacology and Biomolecular Engineering, University of South Alabama, Mobile, AL 36688, USA.
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Stoeber M, Jullié D, Li J, Chakraborty S, Majumdar S, Lambert NA, Manglik A, von Zastrow M. Agonist-selective recruitment of engineered protein probes and of GRK2 by opioid receptors in living cells. eLife 2020; 9:54208. [PMID: 32096468 PMCID: PMC7041944 DOI: 10.7554/elife.54208] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 01/29/2020] [Indexed: 12/21/2022] Open
Abstract
G protein-coupled receptors (GPCRs) signal through allostery, and it is increasingly clear that chemically distinct agonists can produce different receptor-based effects. It has been proposed that agonists selectively promote receptors to recruit one cellular interacting partner over another, introducing allosteric ‘bias’ into the signaling system. However, the underlying hypothesis - that different agonists drive GPCRs to engage different cytoplasmic proteins in living cells - remains untested due to the complexity of readouts through which receptor-proximal interactions are typically inferred. We describe a cell-based assay to overcome this challenge, based on GPCR-interacting biosensors that are disconnected from endogenous transduction mechanisms. Focusing on opioid receptors, we directly demonstrate differences between biosensor recruitment produced by chemically distinct opioid ligands in living cells. We then show that selective recruitment applies to GRK2, a biologically relevant GPCR regulator, through discrete interactions of GRK2 with receptors or with G protein beta-gamma subunits which are differentially promoted by agonists. About a third of all drugs work by targeting a group of proteins known as G-protein coupled receptors, or GPCRs for short. These receptors are found on the surface of cells and transmit messages across the cell’s outer barrier. When a signaling molecule, like a hormone, is released in the body, it binds to a GPCR and changes the receptor’s shape. The change in structure affects how the GPCR interacts and binds to other proteins on the inside of the cell, triggering a series of reactions that alter the cell’s activity. Scientists have previously seen that a GPCR can trigger different responses depending on which signaling molecule is binding on the surface of the cell. However, the mechanism for this is unknown. One hypothesis is that different signaling molecules change the GPCR’s preference for binding to different proteins on the inside of the cell. The challenge has been to observe this happening without interfering with the process. Stoeber et al. have now tested this idea by attaching fluorescent tags to proteins that bind to activated GPCRs directly and without binding other signaling proteins. This meant these proteins could be tracked under a microscope as they made their way to bind to the GPCRs. Stoeber et al. focused on one particular GPCR, known as the opioid receptor, and tested the binding of two different opioid signaling molecules, etorphine and Dynorphin A. The experiments revealed that the different opioids did affect which of the engineered proteins would preferentially bind to the opioid receptor. This was followed by a similar experiment, where the engineered proteins were replaced with another protein called GRK2, which binds to the opioid receptor under normal conditions in the cell. This showed that GRK2 binds much more strongly to the opioid receptor when Dynorphin A is added compared to adding etorphine. These findings show that GPCRs can not only communicate that a signaling molecule is binding but can respond differently to convey what molecule it is more specifically. This could be important in developing drugs, particularly to specifically trigger the desired response and reduce side effects. Stoeber et al. suggest that an important next step for research is to understand how the GPCRs preferentially bind to different proteins.
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Affiliation(s)
- Miriam Stoeber
- Department of Psychiatry, University of California, San Francisco, San Francisco, United States.,Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Damien Jullié
- Department of Psychiatry, University of California, San Francisco, San Francisco, United States.,Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
| | - Joy Li
- Department of Psychiatry, University of California, San Francisco, San Francisco, United States.,Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
| | - Soumen Chakraborty
- Center for Clinical Pharmacology, Washington University School of Medicine, St. Louis, United States.,St Louis College of Pharmacy, St. Louis, United States
| | - Susruta Majumdar
- Center for Clinical Pharmacology, Washington University School of Medicine, St. Louis, United States.,St Louis College of Pharmacy, St. Louis, United States
| | - Nevin A Lambert
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, United States
| | - Aashish Manglik
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, United States.,Department of Anesthesia, University of California, San Francisco, San Francisco, United States
| | - Mark von Zastrow
- Department of Psychiatry, University of California, San Francisco, San Francisco, United States.,Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
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Kuschak M, Namasivayam V, Rafehi M, Voss JH, Garg J, Schlegel JG, Abdelrahman A, Kehraus S, Reher R, Küppers J, Sylvester K, Hinz S, Matthey M, Wenzel D, Fleischmann BK, Pfeifer A, Inoue A, Gütschow M, König GM, Müller CE. Cell-permeable high-affinity tracers for G q proteins provide structural insights, reveal distinct binding kinetics and identify small molecule inhibitors. Br J Pharmacol 2020; 177:1898-1916. [PMID: 31881095 PMCID: PMC7070167 DOI: 10.1111/bph.14960] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 11/26/2019] [Accepted: 12/01/2019] [Indexed: 12/13/2022] Open
Abstract
Background and Purpose G proteins are intracellular switches that transduce and amplify extracellular signals from GPCRs. The Gq protein subtypes, which are coupled to PLC activation, can act as oncogenes, and their expression was reported to be up‐regulated in cancer and inflammatory diseases. Gq inhibition may be an efficient therapeutic strategy constituting a new level of intervention. However, diagnostic tools and therapeutic drugs for Gq proteins are lacking. Experimental Approach We have now developed Gq‐specific, cell‐permeable 3H‐labelled high‐affinity probes based on the macrocyclic depsipeptides FR900359 (FR) and YM‐254890 (YM). The tracers served to specifically label and quantify Gq proteins in their native conformation in cells and tissues with high accuracy. Key Results FR and YM displayed low nanomolar affinity for Gαq, Gα11 and Gα14 expressed in CRISPR/Cas9 Gαq‐knockout cells, but not for Gα15. The two structurally very similar tracers showed strikingly different dissociation kinetics, which is predicted to result in divergent biological effects. Computational studies suggested a “dowel” effect of the pseudoirreversibly binding FR. A high‐throughput binding assay led to the discovery of novel Gq inhibitors, which inhibited Gq signalling in recombinant cells and primary murine brown adipocytes, resulting in enhanced differentiation. Conclusions and Implications The Gq protein inhibitors YM and FR are pharmacologically different despite similar structures. The new versatile tools and powerful assays will contribute to the advancement of the rising field of G protein research.
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Affiliation(s)
- Markus Kuschak
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - Vigneshwaran Namasivayam
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - Muhammad Rafehi
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - Jan H Voss
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - Jaspal Garg
- Institute of Pharmacology and Toxicology, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Jonathan G Schlegel
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - Aliaa Abdelrahman
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - Stefan Kehraus
- Institute of Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Raphael Reher
- Institute of Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Jim Küppers
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - Katharina Sylvester
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - Sonja Hinz
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - Michaela Matthey
- Medical Faculty, Institute of Physiology I, Life and Brain Center, University of Bonn, Bonn, Germany.,Department of Systems Physiology, Medical Faculty, Ruhr University Bochum, Bochum, Germany
| | - Daniela Wenzel
- Medical Faculty, Institute of Physiology I, Life and Brain Center, University of Bonn, Bonn, Germany.,Department of Systems Physiology, Medical Faculty, Ruhr University Bochum, Bochum, Germany
| | - Bernd K Fleischmann
- Medical Faculty, Institute of Physiology I, Life and Brain Center, University of Bonn, Bonn, Germany
| | - Alexander Pfeifer
- Institute of Pharmacology and Toxicology, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Asuka Inoue
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, Japan
| | - Michael Gütschow
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - Gabriele M König
- Institute of Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Christa E Müller
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
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11
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Detection and Quantitative Analysis of Dynamic GPCRs Interactions Using Flow Cytometry-Based FRET. RECEPTOR-RECEPTOR INTERACTIONS IN THE CENTRAL NERVOUS SYSTEM 2018. [DOI: 10.1007/978-1-4939-8576-0_14] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Heterotrimeric G protein Gαs subunit attenuates PLEKHG2, a Rho family-specific guanine nucleotide exchange factor, by direct interaction. Cell Signal 2017; 32:115-123. [PMID: 28108261 DOI: 10.1016/j.cellsig.2017.01.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 01/15/2017] [Indexed: 11/21/2022]
Abstract
PLEKHG2 is a Gβγ-dependent guanine nucleotide exchange factor (GEF) for the small GTPases Rac and Cdc42, and has been shown to mediate signalling pathways such as actin cytoskeleton reorganization and serum response element (SRE)-dependent gene transcription. Here we show that the constitutively active mutant of the Gαs subunit significantly attenuated PLEKHG2-induced SRE-mediated gene transcription. Strikingly, we observed that the constitutive activation of endogenous Gαs by treatment with CTx caused a similar inhibitory effect on PLEKHG2-induced activation of SRE. However, both the enforced expression of the catalytic subunit β of protein kinase A and the treatment with dibutyl-cyclic AMP failed to mimic the inhibitory effect of Gαs on PLEKHG2. Furthermore, the dominant negative mutant of protein kinase A had no effect on PLEKHG2-mediated SRE activation. Performing immunoprecipitation and an in vitro pulldown assay, we found that PLEKHG2 directly interacted with the active form of the Gαs subunit in cells. The interaction between PLEKHG2 and Gαs required the N-terminal region of PLEKHG2, which includes the DH domain, a functional domain of GEF, suggesting that Gαs directly masks the DH domain of PLEKHG2. In a previous study, we reported that Gβγ accelerates PLEKHG2-mediated SRE-dependent gene transcription. Interestingly, Gαs also inhibited the hyperactivation of SRE induced by the co-expression of Gβγ and PLEKHG2; however, Gαs and Gβγ bind to different regions of PLEKHG2. This is the first report to show that PLEKHG2 is a novel effector of Gαs, and is negatively regulated by the Gαs subunit through direct interaction.
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Pupo AS, García-Sáinz JA. A Latin American Perspective on G Protein-Coupled Receptors. Mol Pharmacol 2016; 90:570-572. [PMID: 27754900 DOI: 10.1124/mol.116.106062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 08/25/2016] [Indexed: 11/22/2022] Open
Abstract
G protein-coupled receptors are sensors that interact with a large variety of elements, including photons, ions, and large proteins. Not surprisingly, these receptors participate in the numerous normal physiologic processes that we refer to as health and in its perturbations that constitute disease. It has been estimated that a large percentage of drugs currently used in therapeutics target these proteins, and this percentage is larger when illegal drugs are included. The state of the art in this field can be defined with the oxymoron "constant change," and enormous progress has been made in recent years. A group of scientists working in Latin America were invited to contribute minireviews for this special section to present some of the work performed in this geographical region and foster further international collaboration.
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Affiliation(s)
- André S Pupo
- Department of Pharmacology, Instituto de Biociências, Universidade Estadual Paulista, Botucatu, São Paulo, Brazil (A.S.P.); and Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico (J.A.G.-S.)
| | - J Adolfo García-Sáinz
- Department of Pharmacology, Instituto de Biociências, Universidade Estadual Paulista, Botucatu, São Paulo, Brazil (A.S.P.); and Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico (J.A.G.-S.)
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