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Gardner J, Eiger DS, Hicks C, Choi I, Pham U, Chundi A, Namjoshi O, Rajagopal S. GPCR kinases differentially modulate biased signaling downstream of CXCR3 depending on their subcellular localization. Sci Signal 2024; 17:eadd9139. [PMID: 38349966 PMCID: PMC10927030 DOI: 10.1126/scisignal.add9139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Accepted: 01/22/2024] [Indexed: 02/15/2024]
Abstract
Some G protein-coupled receptors (GPCRs) demonstrate biased signaling such that ligands of the same receptor exclusively or preferentially activate certain downstream signaling pathways over others. This phenomenon may result from ligand-specific receptor phosphorylation by GPCR kinases (GRKs). GPCR signaling can also exhibit location bias because GPCRs traffic to and signal from subcellular compartments in addition to the plasma membrane. Here, we investigated whether GRKs contributed to location bias in GPCR signaling. GRKs translocated to endosomes after stimulation of the chemokine receptor CXCR3 or other GPCRs in cultured cells. GRK2, GRK3, GRK5, and GRK6 showed distinct patterns of recruitment to the plasma membrane and to endosomes depending on the identity of the biased ligand used to activate CXCR3. Analysis of engineered forms of GRKs that localized to either the plasma membrane or endosomes demonstrated that biased CXCR3 ligands elicited different signaling profiles that depended on the subcellular location of the GRK. Each GRK exerted a distinct effect on the regulation of CXCR3 engagement of β-arrestin, internalization, and activation of the downstream effector kinase ERK. Our work highlights a role for GRKs in location-biased GPCR signaling and demonstrates the complex interactions between ligands, GRKs, and cellular location that contribute to biased signaling.
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Affiliation(s)
- Julia Gardner
- Trinity College, Duke University, Durham, NC, 27710, USA
| | | | - Chloe Hicks
- Trinity College, Duke University, Durham, NC, 27710, USA
| | - Issac Choi
- Department of Medicine, Duke University, Durham, NC, 27710, USA
| | - Uyen Pham
- Department of Biochemistry, Duke University, Durham, NC, 27710, USA
| | - Anand Chundi
- Pratt School of Engineering, Duke University, Durham, NC, 27710, USA
| | - Ojas Namjoshi
- Center for Drug Discovery RTI International, Research Triangle Park, NC, 27709, USA
- Present address: Engine Biosciences, 733 Industrial Rd., San Carlos, CA, 94070, USA
| | - Sudarshan Rajagopal
- Department of Biochemistry, Duke University, Durham, NC, 27710, USA
- Department of Medicine, Duke University, Durham, NC, 27710, USA
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Structures of rhodopsin in complex with G-protein-coupled receptor kinase 1. Nature 2021; 595:600-605. [PMID: 34262173 PMCID: PMC8607881 DOI: 10.1038/s41586-021-03721-x] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 06/11/2021] [Indexed: 02/06/2023]
Abstract
G-protein-coupled receptor (GPCR) kinases (GRKs) selectively phosphorylate activated GPCRs, thereby priming them for desensitization1. Although it is unclear how GRKs recognize these receptors2-4, a conserved region at the GRK N terminus is essential for this process5-8. Here we report a series of cryo-electron microscopy single-particle reconstructions of light-activated rhodopsin (Rho*) bound to rhodopsin kinase (GRK1), wherein the N terminus of GRK1 forms a helix that docks into the open cytoplasmic cleft of Rho*. The helix also packs against the GRK1 kinase domain and stabilizes it in an active configuration. The complex is further stabilized by electrostatic interactions between basic residues that are conserved in most GPCRs and acidic residues that are conserved in GRKs. We did not observe any density for the regulator of G-protein signalling homology domain of GRK1 or the C terminus of rhodopsin. Crosslinking with mass spectrometry analysis confirmed these results and revealed dynamic behaviour in receptor-bound GRK1 that would allow the phosphorylation of multiple sites in the receptor tail. We have identified GRK1 residues whose mutation augments kinase activity and crosslinking with Rho*, as well as residues that are involved in activation by acidic phospholipids. From these data, we present a general model for how a small family of protein kinases can recognize and be activated by hundreds of different GPCRs.
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Sulon SM, Benovic JL. Targeting G protein-coupled receptor kinases (GRKs) to G protein-coupled receptors. ACTA ACUST UNITED AC 2021; 16:56-65. [PMID: 33718657 DOI: 10.1016/j.coemr.2020.09.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
G protein-coupled receptors (GPCRs) interact with three protein families following agonist binding: heterotrimeric G proteins, G protein-coupled receptor kinases (GRKs) and arrestins. GRK-mediated phosphorylation of GPCRs promotes arrestin binding to uncouple the receptor from G protein, a process called desensitization, and for many GPCRs, arrestin binding also promotes receptor endocytosis and intracellular signaling. Thus, GRKs play a central role in modulating GPCR signaling and localization. Here we review recent advances in this field which include additional insight into how GRKs target GPCRs and bias signaling, and the development of specific inhibitors to dissect GRK function in model systems.
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Affiliation(s)
- Sarah M Sulon
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Jeffrey L Benovic
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
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Abstract
G protein-coupled receptor (GPCR) signaling is crucial for many physiological processes. A signature of such pathways is high amplification, a concept originating from retinal rod phototransduction, whereby one photoactivated rhodopsin molecule (Rho*) was long reported to activate several hundred transducins (GT*s), each then activating a cGMP-phosphodiesterase catalytic subunit (GT*·PDE*). This high gain at the Rho*-to-GT* step has been challenged more recently, but estimates remain dispersed and rely on some nonintact rod measurements. With two independent approaches, one with an extremely inefficient mutant rhodopsin and the other with WT bleached rhodopsin, which has exceedingly weak constitutive activity in darkness, we obtained an estimate for the electrical effect from a single GT*·PDE* molecular complex in intact mouse rods. Comparing the single-GT*·PDE* effect to the WT single-photon response, both in Gcaps-/- background, gives an effective gain of only ∼12-14 GT*·PDE*s produced per Rho*. Our findings have finally dispelled the entrenched concept of very high gain at the receptor-to-G protein/effector step in GPCR systems.
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Salas-Estrada LA, Leioatts N, Romo TD, Grossfield A. Lipids Alter Rhodopsin Function via Ligand-like and Solvent-like Interactions. Biophys J 2018; 114:355-367. [PMID: 29401433 PMCID: PMC5984976 DOI: 10.1016/j.bpj.2017.11.021] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 09/20/2017] [Accepted: 11/09/2017] [Indexed: 10/18/2022] Open
Abstract
Rhodopsin, a prototypical G protein-coupled receptor, is a membrane protein that can sense dim light. This highly effective photoreceptor is known to be sensitive to the composition of its lipidic environment, but the molecular mechanisms underlying this fine-tuned modulation of the receptor's function and structural stability are not fully understood. There are two competing hypotheses to explain how this occurs: 1) lipid modulation occurs via solvent-like interactions, where lipid composition controls membrane properties like hydrophobic thickness, which in turn modulate the protein's conformational equilibrium; or 2) protein-lipid interactions are ligand-like, with specific hot spots and long-lived binding events. By analyzing an ensemble of all-atom molecular dynamics simulations of five different states of rhodopsin, we show that a local ordering effect takes place in the membrane upon receptor activation. Likewise, docosahexaenoic acid acyl tails and phosphatidylethanolamine headgroups behave like weak ligands, preferentially binding to the receptor in inactive-like conformations and inducing subtle but significant structural changes.
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Affiliation(s)
- Leslie A Salas-Estrada
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York
| | - Nicholas Leioatts
- Department of Theoretical and Computational Biophysics, Max Plank Institute for Biophysical Chemistry, Göttingen, Germany
| | - Tod D Romo
- Center for Integrated Research Computing, University of Rochester, Rochester, New York
| | - Alan Grossfield
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York.
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Komolov KE, Benovic JL. G protein-coupled receptor kinases: Past, present and future. Cell Signal 2017; 41:17-24. [PMID: 28711719 DOI: 10.1016/j.cellsig.2017.07.004] [Citation(s) in RCA: 121] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 07/10/2017] [Indexed: 02/08/2023]
Abstract
This review is provided in recognition of the extensive contributions of Dr. Robert J. Lefkowitz to the G protein-coupled receptor (GPCR) field and to celebrate his 75th birthday. Since one of the authors trained with Bob in the 80s, we provide a history of work done in the Lefkowitz lab during the 80s that focused on dissecting the mechanisms that regulate GPCR signaling, with a particular emphasis on the GPCR kinases (GRKs). In addition, we highlight structure/function characteristics of GRK interaction with GPCRs as well as a review of two recent reports that provide a molecular model for GRK-GPCR interaction. Finally, we offer our perspective on some future studies that we believe will drive this field.
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Affiliation(s)
- Konstantin E Komolov
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States
| | - Jeffrey L Benovic
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, United States.
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He Y, Gao X, Goswami D, Hou L, Pal K, Yin Y, Zhao G, Ernst OP, Griffin P, Melcher K, Xu HE. Molecular assembly of rhodopsin with G protein-coupled receptor kinases. Cell Res 2017; 27:728-747. [PMID: 28524165 PMCID: PMC5518878 DOI: 10.1038/cr.2017.72] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 04/06/2017] [Accepted: 04/11/2017] [Indexed: 12/26/2022] Open
Abstract
G protein-coupled receptor kinases (GRKs) play pivotal roles in desensitizing GPCR signaling but little is known about how GRKs recognize and phosphorylate GPCRs due to the technical difficulties in detecting the highly dynamic GPCR/GRK interaction. By combining a genetic approach with multiple biochemical assays, we identified the key determinants for the assembly of the prototypical GPCR rhodopsin with its kinase GRK1. Our work reveals that the regulatory G-protein signaling homology (RH) domain of GRKs is the primary binding site to GPCRs and an active conformation of the GRK1 kinase domain is required for efficient interaction with rhodopsin. In addition, we provide a mechanistic solution for the longstanding puzzle about the gain-of-function Q41L mutation in GRK5. This mutation is in the RH domain and increases the capacity of the GRK mutant to interact with and to desensitize GPCRs. Finally we present the principal architecture of a rhodopsin/GRK complex through negative stain electron microscopy reconstruction. Together, these data define the key components for the rhodopsin/GRK1 interaction and provide a framework for understanding GRK-mediated desensitization of GPCRs.
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Affiliation(s)
- Yuanzheng He
- Laboratory of Structural Sciences, Center for Structural Biology and Drug Discovery, Van Andel Research Institute, Grand Rapids, MI 49503, USA
| | - Xiang Gao
- Laboratory of Structural Sciences, Center for Structural Biology and Drug Discovery, Van Andel Research Institute, Grand Rapids, MI 49503, USA
| | - Devrishi Goswami
- Department of Molecular Therapeutics, The Scripps Research Institute, Scripps Florida, Jupiter, FL 33458, USA.,Current address: Amgen, Thousand Oaks, CA 91320, USA
| | - Li Hou
- VARI-SIMM Center, Center for Structure and Function of Drug Targets, CAS-Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Kuntal Pal
- Laboratory of Structural Sciences, Center for Structural Biology and Drug Discovery, Van Andel Research Institute, Grand Rapids, MI 49503, USA
| | - Yanting Yin
- Laboratory of Structural Sciences, Center for Structural Biology and Drug Discovery, Van Andel Research Institute, Grand Rapids, MI 49503, USA.,VARI-SIMM Center, Center for Structure and Function of Drug Targets, CAS-Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Gongpu Zhao
- The Cryo-EM Core, Van Andel Research Institute, Grand Rapids, MI 49503, USA
| | - Oliver P Ernst
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Patrick Griffin
- Department of Molecular Therapeutics, The Scripps Research Institute, Scripps Florida, Jupiter, FL 33458, USA
| | - Karsten Melcher
- Laboratory of Structural Sciences, Center for Structural Biology and Drug Discovery, Van Andel Research Institute, Grand Rapids, MI 49503, USA
| | - H Eric Xu
- Laboratory of Structural Sciences, Center for Structural Biology and Drug Discovery, Van Andel Research Institute, Grand Rapids, MI 49503, USA.,VARI-SIMM Center, Center for Structure and Function of Drug Targets, CAS-Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
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