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Jiang H, Galtes D, Wang J, Rockman HA. G protein-coupled receptor signaling: transducers and effectors. Am J Physiol Cell Physiol 2022; 323:C731-C748. [PMID: 35816644 PMCID: PMC9448338 DOI: 10.1152/ajpcell.00210.2022] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 06/27/2022] [Accepted: 07/10/2022] [Indexed: 01/14/2023]
Abstract
G protein-coupled receptors (GPCRs) are of considerable interest due to their importance in a wide range of physiological functions and in a large number of Food and Drug Administration (FDA)-approved drugs as therapeutic entities. With continued study of their function and mechanism of action, there is a greater understanding of how effector molecules interact with a receptor to initiate downstream effector signaling. This review aims to explore the signaling pathways, dynamic structures, and physiological relevance in the cardiovascular system of the three most important GPCR signaling effectors: heterotrimeric G proteins, GPCR kinases (GRKs), and β-arrestins. We will first summarize their prominent roles in GPCR pharmacology before transitioning into less well-explored areas. As new technologies are developed and applied to studying GPCR structure and their downstream effectors, there is increasing appreciation for the elegance of the regulatory mechanisms that mediate intracellular signaling and function.
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Affiliation(s)
- Haoran Jiang
- Department of Medicine, Duke University Medical Center, Durham, North Carolina
| | - Daniella Galtes
- Department of Medicine, Duke University Medical Center, Durham, North Carolina
| | - Jialu Wang
- Department of Medicine, Duke University Medical Center, Durham, North Carolina
| | - Howard A Rockman
- Department of Medicine, Duke University Medical Center, Durham, North Carolina
- Department of Cell Biology, Duke University Medical Center, Durham, North Carolina
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2
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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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3
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The Open Question of How GPCRs Interact with GPCR Kinases (GRKs). Biomolecules 2021; 11:biom11030447. [PMID: 33802765 PMCID: PMC8002388 DOI: 10.3390/biom11030447] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 03/13/2021] [Accepted: 03/15/2021] [Indexed: 01/14/2023] Open
Abstract
G protein-coupled receptors (GPCRs), which regulate a vast number of eukaryotic processes, are desensitized by various mechanisms but, most importantly, by the GPCR kinases (GRKs). Ever since GRKs were first identified, investigators have sought to determine which structural features of GRKs are used to select for the agonist-bound states of GPCRs and how this binding event in turn enhances GRK catalytic activity. Despite a wealth of molecular information from high-resolution crystal structures of GRKs, the mechanisms driving activation have remained elusive, in part because the GRK N-terminus and active site tether region, previously proposed to serve as a receptor docking site and to be key to kinase domain closure, are often disordered or adopt inconsistent conformations. However, two recent studies have implicated other regions of GRKs as being involved in direct interactions with active GPCRs. Atomic resolution structures of GPCR–GRK complexes would help refine these models but are, so far, lacking. Here, we assess three distinct models for how GRKs recognize activated GPCRs, discuss limitations in the approaches used to generate them, and then experimentally test a hypothetical GPCR interaction site in GRK2 suggested by the two newest models.
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4
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Design of substrates and inhibitors of G protein-coupled receptor kinase 2 (GRK2) based on its phosphorylation reaction. Amino Acids 2020; 52:863-870. [PMID: 32577910 DOI: 10.1007/s00726-020-02864-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 06/19/2020] [Indexed: 01/05/2023]
Abstract
The G protein-coupled receptor kinase (GRK) family consists of seven cytosolic serine/threonine (Ser/Thr) protein kinases, and among them, GRK2 is involved in the regulation of an enormous range of both G protein-coupled receptors (GPCRs) and non-GPCR substrates that participate in or regulate many critical cellular processes. GRK2 dysfunction is associated with multiple diseases, including cancers, brain diseases, cardiovascular and metabolic diseases, and therefore GRK2-specific substrates/inhibitors are needed not only for studies of GRK2-mediated cellular functions but also for GRK2-targeted drug development. Here, we first review the structure, regulation and functions of GRK2, and its synthetic substrates and inhibitors. We then highlight recent work on synthetic peptide substrates/inhibitors as promising tools for fundamental studies of the physiological functions of GRK2, and as candidates for applications in clinical diagnostics.
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5
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Guillien M, le Maire A, Mouhand A, Bernadó P, Bourguet W, Banères JL, Sibille N. IDPs and their complexes in GPCR and nuclear receptor signaling. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2020; 174:105-155. [DOI: 10.1016/bs.pmbts.2020.05.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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6
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Penela P, Ribas C, Sánchez-Madrid F, Mayor F. G protein-coupled receptor kinase 2 (GRK2) as a multifunctional signaling hub. Cell Mol Life Sci 2019; 76:4423-4446. [PMID: 31432234 PMCID: PMC6841920 DOI: 10.1007/s00018-019-03274-3] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 08/06/2019] [Accepted: 08/12/2019] [Indexed: 12/18/2022]
Abstract
Accumulating evidence indicates that G protein-coupled receptor kinase 2 (GRK2) is a versatile protein that acts as a signaling hub by modulating G protein-coupled receptor (GPCR) signaling and also via phosphorylation or scaffolding interactions with an extensive number of non-GPCR cellular partners. GRK2 multifunctionality arises from its multidomain structure and from complex mechanisms of regulation of its expression levels, activity, and localization within the cell, what allows the precise spatio-temporal shaping of GRK2 targets. A better understanding of the GRK2 interactome and its modulation mechanisms is helping to identify the GRK2-interacting proteins and its substrates involved in the participation of this kinase in different cellular processes and pathophysiological contexts.
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Affiliation(s)
- Petronila Penela
- Departamento de Biología Molecular, Centro de Biología Molecular "Severo Ochoa" (UAM-CSIC), Universidad Autónoma de Madrid, C/Nicolás Cabrera 1, 28049, Madrid, Spain
- Instituto de Investigación Sanitaria La Princesa, 28006, Madrid, Spain
- CIBER de Enfermedades Cardiovasculares, ISCIII (CIBERCV), 28029, Madrid, Spain
| | - Catalina Ribas
- Departamento de Biología Molecular, Centro de Biología Molecular "Severo Ochoa" (UAM-CSIC), Universidad Autónoma de Madrid, C/Nicolás Cabrera 1, 28049, Madrid, Spain
- Instituto de Investigación Sanitaria La Princesa, 28006, Madrid, Spain
- CIBER de Enfermedades Cardiovasculares, ISCIII (CIBERCV), 28029, Madrid, Spain
| | - Francisco Sánchez-Madrid
- Instituto de Investigación Sanitaria La Princesa, 28006, Madrid, Spain
- CIBER de Enfermedades Cardiovasculares, ISCIII (CIBERCV), 28029, Madrid, Spain
- Cell-Cell Communication Laboratory, Vascular Pathophysiology Area, Centro Nacional Investigaciones Cardiovasculares (CNIC), 28029, Madrid, Spain
| | - Federico Mayor
- Departamento de Biología Molecular, Centro de Biología Molecular "Severo Ochoa" (UAM-CSIC), Universidad Autónoma de Madrid, C/Nicolás Cabrera 1, 28049, Madrid, Spain.
- Instituto de Investigación Sanitaria La Princesa, 28006, Madrid, Spain.
- CIBER de Enfermedades Cardiovasculares, ISCIII (CIBERCV), 28029, Madrid, Spain.
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7
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Abbas S, Marino V, Dell’Orco D, Koch KW. Molecular Recognition of Rhodopsin Kinase GRK1 and Recoverin Is Tuned by Switching Intra- and Intermolecular Electrostatic Interactions. Biochemistry 2019; 58:4374-4385. [DOI: 10.1021/acs.biochem.9b00846] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Seher Abbas
- Department of Neuroscience, Division of Biochemistry, University of Oldenburg, 26111 Oldenburg, Germany
| | - Valerio Marino
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134 Verona, Italy
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, Italy
| | - Daniele Dell’Orco
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134 Verona, Italy
| | - Karl-Wilhelm Koch
- Department of Neuroscience, Division of Biochemistry, University of Oldenburg, 26111 Oldenburg, Germany
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8
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A high-affinity peptide substrate for G protein-coupled receptor kinase 2 (GRK2). Amino Acids 2019; 51:973-976. [PMID: 31004228 DOI: 10.1007/s00726-019-02735-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 04/09/2019] [Indexed: 01/07/2023]
Abstract
We synthesized a previously identified β-tubulin-derived G protein-coupled receptor kinase 2 (GKR2) peptide (GR-11-1; DEMEFTEAESNMN) and its amino-terminal extension (GR-11-1-N; GEGMDEMEFTEAESNMN) and carboxyl-terminal extension (GR-11-1-C; DEMEFTEAESNMNDLVSEYQ) peptides with the aim of finding a high-affinity peptide substrate for GRK2. GR-11-1-C showed high affinity for GRK2, but very low affinity for GKR5. Its specificity and sensitivity for GKR2 were greater than those of GR-11-1 and GR-11-1-N. These findings should be useful in designing tools for probing GKR2-mediated intracellular signaling pathways, as well as GRK2-specific drugs.
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9
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Samaradivakara S, Kankanamge D, Senarath K, Ratnayake K, Karunarathne A. G protein γ (Gγ) subtype dependent targeting of GRK2 to M3 receptor by Gβγ. Biochem Biophys Res Commun 2018; 503:165-170. [PMID: 29864421 DOI: 10.1016/j.bbrc.2018.05.204] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 05/29/2018] [Indexed: 01/09/2023]
Abstract
Interactions of cytosolic G protein coupled receptor kinase 2 (GRK2) with activated G protein coupled receptors (GPCRs) induce receptor phosphorylation and desensitization. GRK2 is recruited to active M3-muscarinic receptors (M3R) with the participation of the receptor, Gαq and Gβγ. Since we have shown that signaling efficacy of Gβγ is governed by its Gγ subtype identity, the present study examined whether recruitment of GRK2 to M3R is also Gγ subtype dependent. To capture the dynamics of GRK2-recruitment concurrently with GPCR-G protein activation, we employed live cell confocal imaging and a novel assay based on Gβγ translocation. Data show that M3R activation-induced GRK2 recruitment is Gγ subtype dependent in which Gβγ dimers with low PM-affinity Gγ9 exhibited a two-fold higher GRK2-recruitment compared to high PM affinity Gγ3 expressing cells. Since 12-mammalian Gγ types exhibit a cell and tissue specific expressions and the PM-affinity of a Gγ is linked to its subtype identity, our results indicate a mechanism by which Gγ profile of a cell controls GRK2 signaling and GPCR desensitization.
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Affiliation(s)
- Saroopa Samaradivakara
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH, 43606, USA
| | - Dinesh Kankanamge
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH, 43606, USA
| | - Kanishka Senarath
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH, 43606, USA
| | - Kasun Ratnayake
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH, 43606, USA
| | - Ajith Karunarathne
- Department of Chemistry and Biochemistry, The University of Toledo, Toledo, OH, 43606, USA.
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10
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Molecular Mechanisms of GPCR Signaling: A Structural Perspective. Int J Mol Sci 2017; 18:ijms18122519. [PMID: 29186792 PMCID: PMC5751122 DOI: 10.3390/ijms18122519] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 11/21/2017] [Accepted: 11/22/2017] [Indexed: 01/06/2023] Open
Abstract
G protein-coupled receptors (GPCRs) are cell surface receptors that respond to a wide variety of stimuli, from light, odorants, hormones, and neurotransmitters to proteins and extracellular calcium. GPCRs represent the largest family of signaling proteins targeted by many clinically used drugs. Recent studies shed light on the conformational changes that accompany GPCR activation and the structural state of the receptor necessary for the interactions with the three classes of proteins that preferentially bind active GPCRs, G proteins, G protein-coupled receptor kinases (GRKs), and arrestins. Importantly, structural and biophysical studies also revealed activation-related conformational changes in these three types of signal transducers. Here, we summarize what is already known and point out questions that still need to be answered. Clear understanding of the structural basis of signaling by GPCRs and their interaction partners would pave the way to designing signaling-biased proteins with scientific and therapeutic potential.
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11
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Cannavo A, Komici K, Bencivenga L, D'amico ML, Gambino G, Liccardo D, Ferrara N, Rengo G. GRK2 as a therapeutic target for heart failure. Expert Opin Ther Targets 2017; 22:75-83. [PMID: 29166798 DOI: 10.1080/14728222.2018.1406925] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
INTRODUCTION G protein-coupled receptor (GPCR) kinase-2 (GRK2) is a regulator of GPCRs, in particular β-adrenergic receptors (ARs), and as demonstrated by decades of investigation, it has a pivotal role in the development and progression of cardiovascular disease, like heart failure (HF). Indeed elevated levels and activity of this kinase are able to promote the dysfunction of both cardiac and adrenal α- and β-ARs and to dysregulate other protective signaling pathway, such as sphingosine 1-phospate and insulin. Moreover, recent discoveries suggest that GRK2 can signal independently from GPCRs, in a 'non-canonical' manner, via interaction with non-GPCR molecule or via its mitochondrial localization. Areas covered: Based on this premise, GRK2 inhibition or its genetic deletion has been tested in several disparate animal models of cardiovascular disease, showing to protect the heart from adverse remodeling and dysfunction. Expert opinion: HF is one of the leading cause of death worldwide with enormous health care costs. For this reason, the identification of new therapeutic targets like GRK2 and strategies such as its inhibition represents a new hope in the fight against HF development and progression. Herein, we will update the readers about the 'state-of-art' of GRK2 inhibition as a potent therapeutic strategy in HF.
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Affiliation(s)
- Alessandro Cannavo
- a Center for Translational Medicine , Temple University Lewis Katz School of Medicine , Philadelphia , PA , USA.,b Dpt Translational Medical Sciences , Federico II University of Naples , Naples , Italy
| | - Klara Komici
- b Dpt Translational Medical Sciences , Federico II University of Naples , Naples , Italy
| | - Leonardo Bencivenga
- b Dpt Translational Medical Sciences , Federico II University of Naples , Naples , Italy
| | - Maria Loreta D'amico
- c Istituti Clinici Scientifici Maugeri SpA Società Benefit , Telese Terme Institute , Benevento , Italy
| | - Giuseppina Gambino
- c Istituti Clinici Scientifici Maugeri SpA Società Benefit , Telese Terme Institute , Benevento , Italy
| | - Daniela Liccardo
- b Dpt Translational Medical Sciences , Federico II University of Naples , Naples , Italy
| | - Nicola Ferrara
- b Dpt Translational Medical Sciences , Federico II University of Naples , Naples , Italy.,c Istituti Clinici Scientifici Maugeri SpA Società Benefit , Telese Terme Institute , Benevento , Italy
| | - Giuseppe Rengo
- b Dpt Translational Medical Sciences , Federico II University of Naples , Naples , Italy.,c Istituti Clinici Scientifici Maugeri SpA Società Benefit , Telese Terme Institute , Benevento , Italy
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12
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Yao XQ, Cato MC, Labudde E, Beyett TS, Tesmer JJG, Grant BJ. Navigating the conformational landscape of G protein-coupled receptor kinases during allosteric activation. J Biol Chem 2017; 292:16032-16043. [PMID: 28808053 DOI: 10.1074/jbc.m117.807461] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 08/10/2017] [Indexed: 01/08/2023] Open
Abstract
G protein-coupled receptors (GPCRs) are essential for transferring extracellular signals into carefully choreographed intracellular responses controlling diverse aspects of cell physiology. The duration of GPCR-mediated signaling is primarily regulated via GPCR kinase (GRK)-mediated phosphorylation of activated receptors. Although many GRK structures have been reported, the mechanisms underlying GRK activation are not well-understood, in part because it is unknown how these structures map to the conformational landscape available to this enzyme family. Unlike most other AGC kinases, GRKs rely on their interaction with GPCRs for activation and not phosphorylation. Here, we used principal component analysis of available GRK and protein kinase A crystal structures to identify their dominant domain motions and to provide a framework that helps evaluate how close each GRK structure is to being a catalytically competent state. Our results indicated that disruption of an interface formed between the large lobe of the kinase domain and the regulator of G protein signaling homology domain (RHD) is highly correlated with establishment of the active conformation. By introducing point mutations in the GRK5 RHD-kinase domain interface, we show with both in silico and in vitro experiments that perturbation of this interface leads to higher phosphorylation activity. Navigation of the conformational landscape defined by this bioinformatics-based study is likely common to all GPCR-activated GRKs.
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Affiliation(s)
- Xin-Qiu Yao
- From the Departments of Computational Medicine and Bioinformatics
| | - M Claire Cato
- Biological Chemistry, and.,Life Sciences Institute and
| | | | - Tyler S Beyett
- Life Sciences Institute and.,Program in Chemical Biology, University of Michigan, Ann Arbor, Michigan 48109 and
| | - John J G Tesmer
- Biological Chemistry, and .,Life Sciences Institute and.,Pharmacology, University of Michigan Medical School and
| | - Barry J Grant
- Division of Biological Sciences, University of California San Diego, La Jolla, California 92093
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13
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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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14
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Yang J, Villar VAM, Armando I, Jose PA, Zeng C. G Protein-Coupled Receptor Kinases: Crucial Regulators of Blood Pressure. J Am Heart Assoc 2016; 5:JAHA.116.003519. [PMID: 27390269 PMCID: PMC5015388 DOI: 10.1161/jaha.116.003519] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Jian Yang
- Department of Nutrition, Daping Hospital, The Third Military Medical University, Chongqing, China Department of Cardiology, Chongqing Key Laboratory for Hypertension, Chongqing Institute of Cardiology, Chongqing Cardiovascular Clinical Research Center, Daping Hospital, The Third Military Medical University, Chongqing, China
| | - Van Anthony M Villar
- Division of Renal Diseases & Hypertension, Department of Medicine, The George Washington University School of Medicine and Health Sciences, Washington, DC
| | - Ines Armando
- Division of Renal Diseases & Hypertension, Department of Medicine, The George Washington University School of Medicine and Health Sciences, Washington, DC
| | - Pedro A Jose
- Division of Renal Diseases & Hypertension, Department of Medicine, The George Washington University School of Medicine and Health Sciences, Washington, DC Department of Pharmacology and Physiology, The George Washington University School of Medicine and Health Sciences, Washington, DC
| | - Chunyu Zeng
- Department of Cardiology, Chongqing Key Laboratory for Hypertension, Chongqing Institute of Cardiology, Chongqing Cardiovascular Clinical Research Center, Daping Hospital, The Third Military Medical University, Chongqing, China
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15
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Zheng M, Zhang X, Guo S, Zhang X, Min C, Cheon SH, Oak MH, Kim YR, Kim KM. Agonist-induced changes in RalA activities allows the prediction of the endocytosis of G protein-coupled receptors. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1863:77-90. [PMID: 26477566 DOI: 10.1016/j.bbamcr.2015.10.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 10/10/2015] [Accepted: 10/13/2015] [Indexed: 12/31/2022]
Abstract
GTP binding proteins are classified into two families: heterotrimeric large G proteins which are composed of three subunits, and one subunit of small G proteins. Roles of small G proteins in the intracellular trafficking of G protein-coupled receptors (GPCRs) were studied. Among various small G proteins tested, GTP-bound form (G23V) of RalA inhibited the internalization of dopamine D2 receptor independently of the previously reported downstream effectors of RalA, such as Ral-binding protein 1 and PLD. With high affinity for GRK2, active RalA inhibited the GPCR endocytosis by sequestering the GRK2 from receptors. When it was tested for several GPCRs including an endogenous GPCR, lysophosphatidic acid receptor 1, agonist-induced conversion of GTP-bound to GDP-bound RalA, which presumably releases the sequestered GRK2, was observed selectively with the GPCRs which have tendency to undergo endocytosis. Conversion of RalA from active to inactive state occurred by translocation of RGL, a guanine nucleotide exchange factor, from the plasma membrane to cytosol as a complex with Gβγ. These results suggest that agonist-induced Gβγ-mediated conversion of RalA from the GTP-bound form to the GDP-bound form could be a mechanism to facilitate agonist-induced internalization of GPCRs.
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Affiliation(s)
- Mei Zheng
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju 500-757, Republic of Korea
| | - Xiaohan Zhang
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju 500-757, Republic of Korea
| | - Shuohan Guo
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju 500-757, Republic of Korea
| | - Xiaowei Zhang
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju 500-757, Republic of Korea
| | - Chengchun Min
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju 500-757, Republic of Korea
| | - Seung Hoon Cheon
- Department of Medicinal Chemistry, College of Pharmacy, Chonnam National University, Gwang-Ju 500-757, Republic of Korea
| | - Min-Ho Oak
- College of Pharmacy, Mokpo National University, Muan-gun, Jeollanamdo 534-729, Republic of Korea
| | - Young Ran Kim
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju 500-757, Republic of Korea
| | - Kyeong-Man Kim
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju 500-757, Republic of Korea.
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16
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Allen SJ, Parthasarathy G, Darke PL, Diehl RE, Ford RE, Hall DL, Johnson SA, Reid JC, Rickert KW, Shipman JM, Soisson SM, Zuck P, Munshi SK, Lumb KJ. Structure and Function of the Hypertension Variant A486V of G Protein-coupled Receptor Kinase 4. J Biol Chem 2015; 290:20360-73. [PMID: 26134571 DOI: 10.1074/jbc.m115.648907] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Indexed: 11/06/2022] Open
Abstract
G-protein-coupled receptor (GPCR) kinases (GRKs) bind to and phosphorylate GPCRs, initiating the process of GPCR desensitization and internalization. GRK4 is implicated in the regulation of blood pressure, and three GRK4 polymorphisms (R65L, A142V, and A486V) are associated with hypertension. Here, we describe the 2.6 Å structure of human GRK4α A486V crystallized in the presence of 5'-adenylyl β,γ-imidodiphosphate. The structure of GRK4α is similar to other GRKs, although slight differences exist within the RGS homology (RH) bundle subdomain, substrate-binding site, and kinase C-tail. The RH bundle subdomain and kinase C-terminal lobe form a strikingly acidic surface, whereas the kinase N-terminal lobe and RH terminal subdomain surfaces are much more basic. In this respect, GRK4α is more similar to GRK2 than GRK6. A fully ordered kinase C-tail reveals interactions linking the C-tail with important determinants of kinase activity, including the αB helix, αD helix, and the P-loop. Autophosphorylation of wild-type GRK4α is required for full kinase activity, as indicated by a lag in phosphorylation of a peptide from the dopamine D1 receptor without ATP preincubation. In contrast, this lag is not observed in GRK4α A486V. Phosphopeptide mapping by mass spectrometry indicates an increased rate of autophosphorylation of a number of residues in GRK4α A486V relative to wild-type GRK4α, including Ser-485 in the kinase C-tail.
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Affiliation(s)
- Samantha J Allen
- From Screening and Protein Sciences, Merck Research Laboratories, North Wales, Pennsylvania 19454 and
| | - Gopal Parthasarathy
- Structural Chemistry, Merck Research Laboratories, West Point, Pennsylvania 19486
| | - Paul L Darke
- From Screening and Protein Sciences, Merck Research Laboratories, North Wales, Pennsylvania 19454 and
| | - Ronald E Diehl
- From Screening and Protein Sciences, Merck Research Laboratories, North Wales, Pennsylvania 19454 and
| | - Rachael E Ford
- From Screening and Protein Sciences, Merck Research Laboratories, North Wales, Pennsylvania 19454 and
| | - Dawn L Hall
- From Screening and Protein Sciences, Merck Research Laboratories, North Wales, Pennsylvania 19454 and
| | - Scott A Johnson
- Structural Chemistry, Merck Research Laboratories, West Point, Pennsylvania 19486
| | - John C Reid
- Structural Chemistry, Merck Research Laboratories, West Point, Pennsylvania 19486
| | - Keith W Rickert
- From Screening and Protein Sciences, Merck Research Laboratories, North Wales, Pennsylvania 19454 and
| | - Jennifer M Shipman
- From Screening and Protein Sciences, Merck Research Laboratories, North Wales, Pennsylvania 19454 and
| | - Stephen M Soisson
- Structural Chemistry, Merck Research Laboratories, West Point, Pennsylvania 19486
| | - Paul Zuck
- From Screening and Protein Sciences, Merck Research Laboratories, North Wales, Pennsylvania 19454 and
| | - Sanjeev K Munshi
- From Screening and Protein Sciences, Merck Research Laboratories, North Wales, Pennsylvania 19454 and
| | - Kevin J Lumb
- From Screening and Protein Sciences, Merck Research Laboratories, North Wales, Pennsylvania 19454 and
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17
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Sato PY, Chuprun JK, Schwartz M, Koch WJ. The evolving impact of g protein-coupled receptor kinases in cardiac health and disease. Physiol Rev 2015; 95:377-404. [PMID: 25834229 PMCID: PMC4551214 DOI: 10.1152/physrev.00015.2014] [Citation(s) in RCA: 106] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are important regulators of various cellular functions via activation of intracellular signaling events. Active GPCR signaling is shut down by GPCR kinases (GRKs) and subsequent β-arrestin-mediated mechanisms including phosphorylation, internalization, and either receptor degradation or resensitization. The seven-member GRK family varies in their structural composition, cellular localization, function, and mechanism of action (see sect. II). Here, we focus our attention on GRKs in particular canonical and novel roles of the GRKs found in the cardiovascular system (see sects. III and IV). Paramount to overall cardiac function is GPCR-mediated signaling provided by the adrenergic system. Overstimulation of the adrenergic system has been highly implicated in various etiologies of cardiovascular disease including hypertension and heart failure. GRKs acting downstream of heightened adrenergic signaling appear to be key players in cardiac homeostasis and disease progression, and herein we review the current data on GRKs related to cardiac disease and discuss their potential in the development of novel therapeutic strategies in cardiac diseases including heart failure.
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Affiliation(s)
- Priscila Y Sato
- Center for Translational Medicine and Department of Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania; and Advanced Institutes of Convergence Technology, Suwon, South Korea
| | - J Kurt Chuprun
- Center for Translational Medicine and Department of Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania; and Advanced Institutes of Convergence Technology, Suwon, South Korea
| | - Mathew Schwartz
- Center for Translational Medicine and Department of Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania; and Advanced Institutes of Convergence Technology, Suwon, South Korea
| | - Walter J Koch
- Center for Translational Medicine and Department of Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania; and Advanced Institutes of Convergence Technology, Suwon, South Korea
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18
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Beautrait A, Michalski KR, Lopez TS, Mannix KM, McDonald DJ, Cutter AR, Medina CB, Hebert AM, Francis CJ, Bouvier M, Tesmer JJG, Sterne-Marr R. Mapping the putative G protein-coupled receptor (GPCR) docking site on GPCR kinase 2: insights from intact cell phosphorylation and recruitment assays. J Biol Chem 2014; 289:25262-75. [PMID: 25049229 PMCID: PMC4155688 DOI: 10.1074/jbc.m114.593178] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
G protein-coupled receptor kinases (GRKs) phosphorylate agonist-occupied receptors initiating the processes of desensitization and β-arrestin-dependent signaling. Interaction of GRKs with activated receptors serves to stimulate their kinase activity. The extreme N-terminal helix (αN), the kinase small lobe, and the active site tether (AST) of the AGC kinase domain have previously been implicated in mediating the allosteric activation. Expanded mutagenesis of the αN and AST allowed us to further assess the role of these two regions in kinase activation and receptor phosphorylation in vitro and in intact cells. We also developed a bioluminescence resonance energy transfer-based assay to monitor the recruitment of GRK2 to activated α2A-adrenergic receptors (α2AARs) in living cells. The bioluminescence resonance energy transfer signal exhibited a biphasic response to norepinephrine concentration, suggesting that GRK2 is recruited to Gβγ and α2AAR with EC50 values of 15 nm and 8 μm, respectively. We show that mutations in αN (L4A, V7E, L8E, V11A, S12A, Y13A, and M17A) and AST (G475I, V477D, and I485A) regions impair or potentiate receptor phosphorylation and/or recruitment. We suggest that a surface of GRK2, including Leu4, Val7, Leu8, Val11, and Ser12, directly interacts with receptors, whereas residues such as Asp10, Tyr13, Ala16, Met17, Gly475, Val477, and Ile485 are more important for kinase domain closure and activation. Taken together with data on GRK1 and GRK6, our data suggest that all three GRK subfamilies make conserved interactions with G protein-coupled receptors, but there may be unique interactions that influence selectivity.
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Affiliation(s)
- Alexandre Beautrait
- From the Department of Biochemistry and the Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | | | | | | | | | | | | | | | | | - Michel Bouvier
- From the Department of Biochemistry and the Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - John J G Tesmer
- the Departments of Pharmacology and Biological Chemistry, Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109
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19
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Sandler I, Zigdon N, Levy E, Aharoni A. The functional importance of co-evolving residues in proteins. Cell Mol Life Sci 2014; 71:673-82. [PMID: 23995987 PMCID: PMC11113390 DOI: 10.1007/s00018-013-1458-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2013] [Revised: 07/26/2013] [Accepted: 08/13/2013] [Indexed: 10/26/2022]
Abstract
Computational approaches for detecting co-evolution in proteins allow for the identification of protein-protein interaction networks in different organisms and the assignment of function to under-explored proteins. The detection of co-variation of amino acids within or between proteins, moreover, allows for the discovery of residue-residue contacts and highlights functional residues that can affect the binding affinity, catalytic activity, or substrate specificity of a protein. To explore the functional impact of co-evolutionary changes in proteins, a combined experimental and computational approach must be recruited. Here, we review recent studies that apply computational and experimental tools to obtain novel insight into the structure, function, and evolution of proteins. Specifically, we describe the application of co-evolutionary analysis for predicting high-resolution three-dimensional structures of proteins. In addition, we describe computational approaches followed by experimental analysis for identifying specificity-determining residues in proteins. Finally, we discuss studies addressing the importance of such residues in terms of the functional divergence of proteins, allowing proteins to evolve new functions while avoiding crosstalk with existing cellular pathways or forming reproductive barriers and hence promoting speciation.
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Affiliation(s)
- Inga Sandler
- Department of Life Sciences, Ben-Gurion University of the Negev, 84105 Be’er Sheva, Israel
| | - Nitzan Zigdon
- Department of Life Sciences, Ben-Gurion University of the Negev, 84105 Be’er Sheva, Israel
| | - Efrat Levy
- Department of Life Sciences, Ben-Gurion University of the Negev, 84105 Be’er Sheva, Israel
| | - Amir Aharoni
- Department of Life Sciences, Ben-Gurion University of the Negev, 84105 Be’er Sheva, Israel
- National Institute for Biotechnology in the Negev (NIBN), Ben-Gurion University of the Negev, 84105 Be’er Sheva, Israel
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20
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Structural insights into G protein-coupled receptor kinase function. Curr Opin Cell Biol 2013; 27:25-31. [PMID: 24680427 DOI: 10.1016/j.ceb.2013.10.009] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Revised: 10/30/2013] [Accepted: 10/31/2013] [Indexed: 11/20/2022]
Abstract
The atomic structure of a protein can greatly advance our understanding of molecular recognition and catalysis, properties of fundamental importance in signal transduction. However, a single structure is incapable of fully describing how a protein functions, particularly when allostery is involved. Recent advances in the structure and function of G protein-coupled receptor (GPCR) kinases (GRKs) have concentrated on the mechanism of their inhibition by small and large molecules. These studies have generated a wealth of new information on the conformational flexibility of these enzymes, which opens new avenues for the development of selective chemical probes and provides deeper insights into the molecular basis for activation of these enzymes by GPCRs and phospholipids.
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21
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Biochemical and Cellular Specificity of Peptide Inhibitors of G Protein-Coupled Receptor Kinases. Int J Pept Res Ther 2013; 20:1-12. [PMID: 25530741 DOI: 10.1007/s10989-013-9357-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Identifying novel allosteric inhibitors of G protein-coupled receptor kinases (GRKs) would be of considerable use in limiting both the extent of desensitization of GPCRs as well as downstream positive regulation through GRKs. Several peptides have previously been identified as inhibitors of specific GRKs, but to date there have been few comparisons of the selectivities of these materials on the seven GRKs, modifications to allow cell penetration, or off-target activities. The goal of this study was to determine if a panel of peptides mimicking domains on either GPCRs or GRKs would exhibit selective inhibition of GRKs 2, 5, 6 and 7 phosphorylation of rhodopsin. Peptides included sequences from GRK5; helices 3, 9, and 10 (α3, α9, and α10) in the RH domain, and the N-terminal peptide (N-Ter), as well as the intracellular loop 1 (iL1) of the β2-adrenergic receptor (β2AR), and the Gα transducin C-tail (TCT). While some selectivity for individual GRKs was found, overall selectivity was limited and often not reflective of structural predictions. Off-target effects were probed by determining peptide inhibition of adenylyl cyclase (AC) and PKA, and while peptides had no effect on AC activity, N-Ter, iL1, and α10 were potent inhibitors of PKA. To probe inhibition of GRK activity in intact cells, we synthesized TAT-tagged peptides, and found that TAT-α9-R169A and TAT-TCT inhibited isoproterenol-stimulated GRK phosphorylation of the β2AR; however, the TAT peptides also inhibited isoproterenol and forskolin stimulation of AC activity. Our findings demonstrate potent peptide inhibition of GRK activities in vitro, highlight the differences in the environments of biochemical and cell-based assays, and illustrate the care that must be exercised in interpreting results of either assay alone.
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22
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Sterne-Marr R, Baillargeon AI, Michalski KR, Tesmer JJ. Expression, purification, and analysis of G-protein-coupled receptor kinases. Methods Enzymol 2013; 521:347-66. [PMID: 23351749 PMCID: PMC4297658 DOI: 10.1016/b978-0-12-391862-8.00019-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
G-protein-coupled receptor (GPCR) kinases (GRKs) were first identified based on their ability to specifically phosphorylate activated GPCRs. Although many soluble substrates have since been identified, the chief physiological role of GRKs still remains the uncoupling of GPCRs from heterotrimeric G-proteins by promoting β-arrestin binding through the phosphorylation of the receptor. It is expected that GRKs recognize activated GPCRs through a docking site that not only recognizes the active conformation of the transmembrane domain of the receptor but also stabilizes a more catalytically competent state of the kinase domain. Many of the recent gains in understanding GRK-receptor interactions have been gleaned through biochemical and structural analysis of recombinantly expressed GRKs. Described herein are current techniques and procedures being used to express, purify, and assay GRKs in both in vitro and living cells.
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Affiliation(s)
- Rachel Sterne-Marr
- Biology Department, Siena College, Morrell Science Center, Loudonville, New York, USA
| | - Alison I. Baillargeon
- Department of Chemistry and Biochemistry, Siena College, Morrell Science Center, Loudonville, New York, USA
| | - Kevin R. Michalski
- Department of Chemistry and Biochemistry, Siena College, Morrell Science Center, Loudonville, New York, USA
| | - John J.G. Tesmer
- Life Sciences Institute and the Department of Pharmacology, University of Michigan, Ann Arbor, Michigan, USA,Corresponding author:
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23
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Andresen BT. A pharmacological primer of biased agonism. Endocr Metab Immune Disord Drug Targets 2011; 11:92-8. [PMID: 21476970 PMCID: PMC3182416 DOI: 10.2174/187153011795564179] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Accepted: 02/15/2011] [Indexed: 01/14/2023]
Abstract
Biased agonism is one of the fastest growing topics in G protein-coupled receptor pharmacology; moreover, biased agonists are used in the clinic today: carvedilol (Coreg®) is a biased agonist of beta-adrenergic receptors. However, there is a general lack of understanding of biased agonism when compared to traditional pharmacological terminology. Therefore, this review is designed to provide a basic introduction to classical pharmacology as well as G protein-coupled receptor signal transduction in order to clearly explain biased agonism for the non-scientist clinician and pharmacist. Special emphasis is placed on biased agonists of the beta-adrenergic receptors, as these drugs are highly prescribed, and a hypothetical scenario based on current clinical practices and proposed mechanisms for treating disease is discussed in order to demonstrate the need for a more thorough understanding of biased agonism in clinical settings. Since biased agonism provides a novel mechanism for treating disease, greater emphasis is being placed to develop biased agonists; therefore, it is important for biased agonism to be understood in equal measure of traditional pharmacological concepts. This review, along with many others, can be used to teach the basic concepts of biased agonism, and this review also serves to introduce the subsequent reviews that examine, in more depth, the relevance of biased agonism towards the angiotensin type 1 receptor, parathyroid hormone receptor, and natural biased ligands towards chemokine receptors.
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Affiliation(s)
- Bradley T Andresen
- Department of Internal Medicine, Division of Endocrinology, University of Missouri, MO 65201, USA.
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24
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Gurevich EV, Tesmer JJG, Mushegian A, Gurevich VV. G protein-coupled receptor kinases: more than just kinases and not only for GPCRs. Pharmacol Ther 2011; 133:40-69. [PMID: 21903131 DOI: 10.1016/j.pharmthera.2011.08.001] [Citation(s) in RCA: 319] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 08/01/2011] [Indexed: 12/24/2022]
Abstract
G protein-coupled receptor (GPCR) kinases (GRKs) are best known for their role in homologous desensitization of GPCRs. GRKs phosphorylate activated receptors and promote high affinity binding of arrestins, which precludes G protein coupling. GRKs have a multidomain structure, with the kinase domain inserted into a loop of a regulator of G protein signaling homology domain. Unlike many other kinases, GRKs do not need to be phosphorylated in their activation loop to achieve an activated state. Instead, they are directly activated by docking with active GPCRs. In this manner they are able to selectively phosphorylate Ser/Thr residues on only the activated form of the receptor, unlike related kinases such as protein kinase A. GRKs also phosphorylate a variety of non-GPCR substrates and regulate several signaling pathways via direct interactions with other proteins in a phosphorylation-independent manner. Multiple GRK subtypes are present in virtually every animal cell, with the highest expression levels found in neurons, with their extensive and complex signal regulation. Insufficient or excessive GRK activity was implicated in a variety of human disorders, ranging from heart failure to depression to Parkinson's disease. As key regulators of GPCR-dependent and -independent signaling pathways, GRKs are emerging drug targets and promising molecular tools for therapy. Targeted modulation of expression and/or of activity of several GRK isoforms for therapeutic purposes was recently validated in cardiac disorders and Parkinson's disease.
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Affiliation(s)
- Eugenia V Gurevich
- Department of Pharmacology, Vanderbilt University, 2200 Pierce Avenue, Preston Research Building, Rm. 454, Nashville, TN 37232, United States.
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25
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Huang CC, Orban T, Jastrzebska B, Palczewski K, Tesmer JJG. Activation of G protein-coupled receptor kinase 1 involves interactions between its N-terminal region and its kinase domain. Biochemistry 2011; 50:1940-9. [PMID: 21265573 PMCID: PMC3069497 DOI: 10.1021/bi101606e] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
G protein-coupled receptor kinases (GRKs) phosphorylate activated G protein-coupled receptors (GPCRs) to initiate receptor desensitization. In addition to the canonical phosphoacceptor site of the kinase domain, activated receptors bind to a distinct docking site that confers higher affinity and activates GRKs allosterically. Recent mutagenesis and structural studies support a model in which receptor docking activates a GRK by stabilizing the interaction of its ∼20-amino acid N-terminal region with the kinase domain. This interaction in turn stabilizes a closed, more active conformation of the enzyme. To investigate the importance of this interaction for the process of GRK activation, we first validated the functionality of the N-terminal region in rhodopsin kinase (GRK1) by site-directed mutagenesis and then introduced a disulfide bond to cross-link the N-terminal region of GRK1 with its specific binding site on the kinase domain. Characterization of the kinetic and biophysical properties of the cross-linked protein showed that disulfide bond formation greatly enhances the catalytic efficiency of the peptide phosphorylation, but receptor-dependent phosphorylation, Meta II stabilization, and inhibition of transducin activation were unaffected. These data indicate that the interaction of the N-terminal region with the kinase domain is important for GRK activation but does not dictate the affinity of GRKs for activated receptors.
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Affiliation(s)
- Chih-chin Huang
- Life Sciences Institute, 210 Washtenaw Avenue, University of Michigan, Ann Arbor, Michigan 48109-2216, United States
| | - Tivadar Orban
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4965, United States
| | - Beata Jastrzebska
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4965, United States
| | - Krzysztof Palczewski
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4965, United States
| | - John J. G. Tesmer
- Life Sciences Institute, 210 Washtenaw Avenue, University of Michigan, Ann Arbor, Michigan 48109-2216, United States
- Department of Pharmacology, 210 Washtenaw Avenue, University of Michigan, Ann Arbor, Michigan 48109-2216, United States
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26
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Huang CC, Tesmer JJG. Recognition in the face of diversity: interactions of heterotrimeric G proteins and G protein-coupled receptor (GPCR) kinases with activated GPCRs. J Biol Chem 2011; 286:7715-7721. [PMID: 21199869 DOI: 10.1074/jbc.r109.051847] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
G protein-coupled receptors (GPCRs) represent the largest class of integral membrane protein receptors in the human genome. Despite the great diversity of ligands that activate these GPCRs, they interact with a relatively small number of intracellular proteins to induce profound physiological change. Both heterotrimeric G proteins and GPCR kinases are well known for their ability to specifically recognize GPCRs in their active state. Recent structural studies now suggest that heterotrimeric G proteins and GPCR kinases identify activated receptors via a common molecular mechanism despite having completely different folds.
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Affiliation(s)
| | - John J G Tesmer
- From the Life Sciences Institute and; Department of Pharmacology, University of Michigan, Ann Arbor, Michigan 48109-2216.
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27
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Molecular basis for activation of G protein-coupled receptor kinases. EMBO J 2010; 29:3249-59. [PMID: 20729810 DOI: 10.1038/emboj.2010.206] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Accepted: 07/28/2010] [Indexed: 11/09/2022] Open
Abstract
G protein-coupled receptor (GPCR) kinases (GRKs) selectively recognize and are allosterically regulated by activated GPCRs, but the molecular basis for this interaction is not understood. Herein, we report crystal structures of GRK6 in which regions known to be critical for receptor phosphorylation have coalesced to stabilize the kinase domain in a closed state and to form a likely receptor docking site. The crux of this docking site is an extended N-terminal helix that bridges the large and small lobes of the kinase domain and lies adjacent to a basic surface of the protein proposed to bind anionic phospholipids. Mutation of exposed, hydrophobic residues in the N-terminal helix selectively inhibits receptor, but not peptide phosphorylation, suggesting that these residues interact directly with GPCRs. Our structural and biochemical results thus provide an explanation for how receptor recognition, phospholipid binding, and kinase activation are intimately coupled in GRKs.
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28
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Baameur F, Morgan DH, Yao H, Tran TM, Hammitt RA, Sabui S, McMurray JS, Lichtarge O, Clark RB. Role for the regulator of G-protein signaling homology domain of G protein-coupled receptor kinases 5 and 6 in beta 2-adrenergic receptor and rhodopsin phosphorylation. Mol Pharmacol 2009; 77:405-15. [PMID: 20038610 DOI: 10.1124/mol.109.058115] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Phosphorylation of G protein-coupled receptors (GPCRs) by GPCR kinases (GRKs) is a major mechanism of desensitization of these receptors. GPCR activation of GRKs involves an allosteric site on GRKs distinct from the catalytic site. Although recent studies have suggested an important role of the N- and C-termini and domains surrounding the kinase active site in allosteric activation, the nature of that site and the relative roles of the RH domain in particular remain unknown. Based on evolutionary trace analysis of both the RH and kinase domains of the GRK family, we identified an important cluster encompassing helices 3, 9, and 10 in the RH domain in addition to sites in the kinase domain. To define its function, a panel of GRK5 and -6 mutants was generated and screened by intact-cell assay of constitutive GRK phosphorylation of the beta(2)-adrenergic receptor (beta 2AR), in vitro GRK phosphorylation of light-activated rhodopsin, and basal catalytic activity measured by tubulin phosphorylation and autophosphorylation. A number of double mutations within helices 3, 9, and 10 reduced phosphorylation of the beta2AR and rhodopsin by 50 to 90% relative to wild-type GRK, as well as autophosphorylation and tubulin phosphorylation. Based on these results, helix 9 peptide mimetics were designed, and several were found to inhibit rhodopsin phosphorylation by GRK5 with an IC(50) of approximately 30 microM. In summary, our studies have uncovered previously unrecognized functionally important sites in the regulator of G-protein signaling homology domain of GRK5 and -6 and identified a peptide inhibitor with potential for specific blockade of GRK-mediated phosphorylation of receptors.
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Affiliation(s)
- Faiza Baameur
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Medical School, 6431 Fannin St, Houston, TX 77030, USA
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29
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Gehret AU, Jones BW, Tran PN, Cook LB, Greuber EK, Hinkle PM. Role of helix 8 of the thyrotropin-releasing hormone receptor in phosphorylation by G protein-coupled receptor kinase. Mol Pharmacol 2009; 77:288-97. [PMID: 19906838 DOI: 10.1124/mol.109.059733] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The thyrotropin-releasing hormone (TRH) receptor undergoes rapid and extensive agonist-dependent phosphorylation attributable to G protein-coupled receptor (GPCR) kinases (GRKs), particularly GRK2. Like many GPCRs, the TRH receptor is predicted to form an amphipathic helix, helix 8, between the NPXXY motif at the cytoplasmic end of the seventh transmembrane domain and palmitoylation sites at Cys335 and Cys337. Mutation of all six lysine and arginine residues between the NPXXY and residue 340 to glutamine (6Q receptor) did not prevent the receptor from stimulating inositol phosphate turnover but almost completely prevented receptor phosphorylation in response to TRH. Phosphorylation at all sites in the cytoplasmic tail was inhibited. The phosphorylation defect was not reversed by long incubation times or high TRH concentrations. As expected for a phosphorylation-defective receptor, the 6Q-TRH receptor did not recruit arrestin, undergo the typical arrestin-dependent increase in agonist affinity, or internalize well. Lys326, directly before phenylalanine in the common GPCR motif NPXXY(X)(5-6)F(R/K), was critical for phosphorylation. The 6Q-TRH receptor was not phosphorylated effectively in cells overexpressing GRK2 or in in vitro kinase assays containing purified GRK2. Phosphorylation of the 6Q receptor was partially restored by coexpression of a receptor with an intact helix 8 but without phosphorylation sites. Phosphorylation was inhibited but not completely prevented by alanine substitution for cysteine palmitoylation sites. Positively charged amino acids in the proximal tail of the beta2-adrenergic receptor were also important for GRK-dependent phosphorylation. The results indicate that positive residues in helix 8 of GPCRs are important for GRK-dependent phosphorylation.
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Affiliation(s)
- Austin U Gehret
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
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30
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Pao CS, Barker BL, Benovic JL. Role of the amino terminus of G protein-coupled receptor kinase 2 in receptor phosphorylation. Biochemistry 2009; 48:7325-33. [PMID: 19715378 DOI: 10.1021/bi900408g] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
G protein-coupled receptor kinases (GRKs) specifically phosphorylate activated G protein-coupled receptors. While the X-ray crystal structures of several GRKs have been determined, the mechanism of interaction of GRK with GPCRs is currently unknown. To further characterize the role of the GRK2 amino terminus in receptor interaction and phosphorylation, we generated a series of point mutations within the first 10 amino acids of GRK2 and tested their ability to phosphorylate receptor and nonreceptor substrates. Although all mutants exhibited some impairment in receptor phosphorylation, three of the mutants, D3K, L4A, and D10A, were the most severely affected. Using the beta2-adrenergic receptor and rhodopsin as receptor substrates and tubulin as a nonreceptor substrate, we demonstrated that the kinase activity toward the receptors was severely decreased in the mutants, while they fully retained their ability to phosphorylate tubulin. Moreover, the amino-terminal mutants were able to bind to the receptor but, in contrast to wild-type GRK2, were not activated by receptor binding. A synthetic peptide containing residues 1-14 of GRK2 served as a noncompetitive inhibitor of receptor phosphorylation by GRK2, while a comparable peptide from GRK5 had no effect on GRK2 activity. Secondary structure prediction and circular dichroism suggest that the GRK2 amino-terminal peptide forms an amphipathic alpha-helix. Taken together, we propose a mechanism whereby the extreme amino terminus of GRK2 forms an intramolecular interaction that selectively enhances the catalytic activity of the kinase toward receptor substrates.
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Affiliation(s)
- Christina S Pao
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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