1
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Khan R, Laumet G, Leinninger GM. Hungry for relief: Potential for neurotensin to address comorbid obesity and pain. Appetite 2024; 200:107540. [PMID: 38852785 DOI: 10.1016/j.appet.2024.107540] [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: 02/01/2024] [Revised: 05/31/2024] [Accepted: 06/03/2024] [Indexed: 06/11/2024]
Abstract
Chronic pain and obesity frequently occur together. An ideal therapy would alleviate pain without weight gain, and most optimally, could promote weight loss. The neuropeptide neurotensin (Nts) has been separately implicated in reducing weight and pain but could it be a common actionable target for both pain and obesity? Here we review the current knowledge of Nts signaling via its receptors in modulating body weight and pain processing. Evaluating the mechanism by which Nts impacts ingestive behavior, body weight, and analgesia has potential to identify common physiologic mechanisms underlying weight and pain comorbidities, and whether Nts may be common actionable targets for both.
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Affiliation(s)
- Rabail Khan
- Neuroscience Program, Michigan State University, East Lansing, MI, 48824, USA
| | - Geoffroy Laumet
- Neuroscience Program, Michigan State University, East Lansing, MI, 48824, USA; Department of Physiology, Michigan State University, East Lansing, MI, 48824, USA
| | - Gina M Leinninger
- Neuroscience Program, Michigan State University, East Lansing, MI, 48824, USA; Department of Physiology, Michigan State University, East Lansing, MI, 48824, USA.
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2
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Bumbak F, Bower JB, Zemmer SC, Inoue A, Pons M, Paniagua JC, Yan F, Ford J, Wu H, Robson SA, Bathgate RAD, Scott DJ, Gooley PR, Ziarek JJ. Stabilization of pre-existing neurotensin receptor conformational states by β-arrestin-1 and the biased allosteric modulator ML314. Nat Commun 2023; 14:3328. [PMID: 37286565 PMCID: PMC10247727 DOI: 10.1038/s41467-023-38894-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 05/19/2023] [Indexed: 06/09/2023] Open
Abstract
The neurotensin receptor 1 (NTS1) is a G protein-coupled receptor (GPCR) with promise as a drug target for the treatment of pain, schizophrenia, obesity, addiction, and various cancers. A detailed picture of the NTS1 structural landscape has been established by X-ray crystallography and cryo-EM and yet, the molecular determinants for why a receptor couples to G protein versus arrestin transducers remain poorly defined. We used 13CεH3-methionine NMR spectroscopy to show that binding of phosphatidylinositol-4,5-bisphosphate (PIP2) to the receptor's intracellular surface allosterically tunes the timescale of motions at the orthosteric pocket and conserved activation motifs - without dramatically altering the structural ensemble. β-arrestin-1 further remodels the receptor ensemble by reducing conformational exchange kinetics for a subset of resonances, whereas G protein coupling has little to no effect on exchange rates. A β-arrestin biased allosteric modulator transforms the NTS1:G protein complex into a concatenation of substates, without triggering transducer dissociation, suggesting that it may function by stabilizing signaling incompetent G protein conformations such as the non-canonical state. Together, our work demonstrates the importance of kinetic information to a complete picture of the GPCR activation landscape.
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Affiliation(s)
- Fabian Bumbak
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, 47405, USA.
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins and Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia.
| | - James B Bower
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, 47405, USA
| | - Skylar C Zemmer
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, 47405, USA
| | - Asuka Inoue
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, 980-8578, Japan
| | - Miquel Pons
- Biomolecular NMR laboratory, Department of Inorganic and Organic Chemistry, Universitat de Barcelona (UB), 08028, Barcelona, Spain
| | - Juan Carlos Paniagua
- Department of Materials Science and Physical Chemistry & Institute of Theoretical and Computational Chemistry (IQTCUB), Universitat de Barcelona (UB), 08028, Barcelona, Spain
| | - Fei Yan
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3010, Australia
| | - James Ford
- Department of Chemistry, Indiana University, Bloomington, IN, 47405-7102, USA
| | - Hongwei Wu
- Department of Chemistry, Indiana University, Bloomington, IN, 47405-7102, USA
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Scott A Robson
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, 47405, USA
| | - Ross A D Bathgate
- The Florey Institute of Neuroscience and Mental Health and Department of Biochemistry and Pharmacology, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Daniel J Scott
- The Florey Institute of Neuroscience and Mental Health and Department of Biochemistry and Pharmacology, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Paul R Gooley
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Joshua J Ziarek
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, 47405, USA.
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3
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Krumm BE, DiBerto JF, Olsen RHJ, Kang HJ, Slocum ST, Zhang S, Strachan RT, Huang XP, Slosky LM, Pinkerton AB, Barak LS, Caron MG, Kenakin T, Fay JF, Roth BL. Neurotensin Receptor Allosterism Revealed in Complex with a Biased Allosteric Modulator. Biochemistry 2023; 62:1233-1248. [PMID: 36917754 DOI: 10.1021/acs.biochem.3c00029] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Abstract
The NTSR1 neurotensin receptor (NTSR1) is a G protein-coupled receptor (GPCR) found in the brain and peripheral tissues with neurotensin (NTS) being its endogenous peptide ligand. In the brain, NTS modulates dopamine neuronal activity, induces opioid-independent analgesia, and regulates food intake. Recent studies indicate that biasing NTSR1 toward β-arrestin signaling can attenuate the actions of psychostimulants and other drugs of abuse. Here, we provide the cryoEM structures of NTSR1 ternary complexes with heterotrimeric Gq and GoA with and without the brain-penetrant small-molecule SBI-553. In functional studies, we discovered that SBI-553 displays complex allosteric actions exemplified by negative allosteric modulation for G proteins that are Gα subunit selective and positive allosteric modulation and agonism for β-arrestin translocation at NTSR1. Detailed structural analysis of the allosteric binding site illuminated the structural determinants for biased allosteric modulation of SBI-553 on NTSR1.
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Affiliation(s)
- Brian E Krumm
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599-7365, United States
| | - Jeffrey F DiBerto
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599-7365, United States
| | - Reid H J Olsen
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599-7365, United States
| | - Hye Jin Kang
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599-7365, United States
- National Institute of Mental Health Psychoactive Drug Screening Program (NIMH PDSP), School of Medicine, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599-7365, United States
| | - Samuel T Slocum
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599-7365, United States
- National Institute of Mental Health Psychoactive Drug Screening Program (NIMH PDSP), School of Medicine, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599-7365, United States
| | - Shicheng Zhang
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599-7365, United States
| | - Ryan T Strachan
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599-7365, United States
| | - Xi-Ping Huang
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599-7365, United States
- National Institute of Mental Health Psychoactive Drug Screening Program (NIMH PDSP), School of Medicine, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599-7365, United States
| | - Lauren M Slosky
- Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Anthony B Pinkerton
- Conrad Prebys Center for Chemical Genomics at Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California 92037, United States
| | - Lawrence S Barak
- Department of Cell Biology, Duke University, Durham, North Carolina 27710, United States
| | - Marc G Caron
- Department of Cell Biology, Duke University, Durham, North Carolina 27710, United States
- Departments of Medicine and Neurobiology, Duke University, Durham, North Carolina 27710, United States
| | - Terry Kenakin
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599-7365, United States
| | - Jonathan F Fay
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599, United States
| | - Bryan L Roth
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599-7365, United States
- National Institute of Mental Health Psychoactive Drug Screening Program (NIMH PDSP), School of Medicine, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina 27599-7365, United States
- Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7360, United States
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4
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Ramirez-Virella J, Leinninger GM. The Role of Central Neurotensin in Regulating Feeding and Body Weight. Endocrinology 2021; 162:6144574. [PMID: 33599716 PMCID: PMC7951050 DOI: 10.1210/endocr/bqab038] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Indexed: 12/16/2022]
Abstract
The small peptide neurotensin (Nts) is implicated in myriad processes including analgesia, thermoregulation, reward, arousal, blood pressure, and modulation of feeding and body weight. Alterations in Nts have recently been described in individuals with obesity or eating disorders, suggesting that disrupted Nts signaling may contribute to body weight disturbance. Curiously, Nts mediates seemingly opposing regulation of body weight via different tissues. Peripherally acting Nts promotes fat absorption and weight gain, whereas central Nts signaling suppresses feeding and weight gain. Thus, because Nts is pleiotropic, a location-based approach must be used to understand its contributions to disordered body weight and whether the Nts system might be leveraged to improve metabolic health. Here we review the role of Nts signaling in the brain to understand the sites, receptors, and mechanisms by which Nts can promote behaviors that modify body weight. New techniques permitting site-specific modulation of Nts and Nts receptor-expressing cells suggest that, even in the brain, not all Nts circuitry exerts the same function. Intriguingly, there may be dedicated brain regions and circuits via which Nts specifically suppresses feeding behavior and weight gain vs other Nts-attributed physiology. Defining the central mechanisms by which Nts signaling modifies body weight may suggest strategies to correct disrupted energy balance, as needed to address overweight, obesity, and eating disorders.
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Affiliation(s)
- Jariel Ramirez-Virella
- Neuroscience Program, Michigan State University, East Lansing, Michigan, USA
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan, USA
| | - Gina M Leinninger
- Neuroscience Program, Michigan State University, East Lansing, Michigan, USA
- Department of Physiology, Michigan State University, East Lansing, Michigan, USA
- Correspondence: Gina M. Leinninger, PhD, Department of Physiology, Michigan State University, 5400 ISTB, 766 Service Rd, East Lansing, MI 48824, USA.
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5
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Belkacemi L, Darmani NA. Dopamine receptors in emesis: Molecular mechanisms and potential therapeutic function. Pharmacol Res 2020; 161:105124. [PMID: 32814171 DOI: 10.1016/j.phrs.2020.105124] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 07/20/2020] [Accepted: 08/05/2020] [Indexed: 12/19/2022]
Abstract
Dopamine is a member of the catecholamine family and is associated with multiple physiological functions. Together with its five receptor subtypes, dopamine is closely linked to neurological disorders such as schizophrenia, Parkinson's disease, depression, attention deficit-hyperactivity, and restless leg syndrome. Unfortunately, several dopamine receptor-based agonists used to treat some of these diseases cause nausea and vomiting as impending side-effects. The high degree of cross interactions of dopamine receptor ligands with many other targets including G-protein coupled receptors, transporters, enzymes, and ion-channels, add to the complexity of discovering new targets for the treatment of nausea and vomiting. Using activation status of signaling cascades as mechanism-based biomarkers to foresee drug sensitivity combined with the development of dopamine receptor-based biased agonists may hold great promise and seems as the next step in drug development for the treatment of such multifactorial diseases. In this review, we update the present knowledge on dopamine and dopamine receptors and their potential roles in nausea and vomiting. The pre- and clinical evidence provided in this review supports the implication of both dopamine and dopamine receptor agonists in the incidence of emesis. Besides the conventional dopaminergic antiemetic drugs, potential novel antiemetic targeting emetic protein signaling cascades may offer superior selectivity profile and potency.
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Affiliation(s)
- Louiza Belkacemi
- Department of Basic Medical Sciences, College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA, 91766, USA
| | - Nissar A Darmani
- Department of Basic Medical Sciences, College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA, 91766, USA.
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6
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Seyedabadi M, Ghahremani MH, Albert PR. Biased signaling of G protein coupled receptors (GPCRs): Molecular determinants of GPCR/transducer selectivity and therapeutic potential. Pharmacol Ther 2019; 200:148-178. [PMID: 31075355 DOI: 10.1016/j.pharmthera.2019.05.006] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 04/26/2019] [Indexed: 02/07/2023]
Abstract
G protein coupled receptors (GPCRs) convey signals across membranes via interaction with G proteins. Originally, an individual GPCR was thought to signal through one G protein family, comprising cognate G proteins that mediate canonical receptor signaling. However, several deviations from canonical signaling pathways for GPCRs have been described. It is now clear that GPCRs can engage with multiple G proteins and the line between cognate and non-cognate signaling is increasingly blurred. Furthermore, GPCRs couple to non-G protein transducers, including β-arrestins or other scaffold proteins, to initiate additional signaling cascades. Receptor/transducer selectivity is dictated by agonist-induced receptor conformations as well as by collateral factors. In particular, ligands stabilize distinct receptor conformations to preferentially activate certain pathways, designated 'biased signaling'. In this regard, receptor sequence alignment and mutagenesis have helped to identify key receptor domains for receptor/transducer specificity. Furthermore, molecular structures of GPCRs bound to different ligands or transducers have provided detailed insights into mechanisms of coupling selectivity. However, receptor dimerization, compartmentalization, and trafficking, receptor-transducer-effector stoichiometry, and ligand residence and exposure times can each affect GPCR coupling. Extrinsic factors including cell type or assay conditions can also influence receptor signaling. Understanding these factors may lead to the development of improved biased ligands with the potential to enhance therapeutic benefit, while minimizing adverse effects. In this review, evidence for ligand-specific GPCR signaling toward different transducers or pathways is elaborated. Furthermore, molecular determinants of biased signaling toward these pathways and relevant examples of the potential clinical benefits and pitfalls of biased ligands are discussed.
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Affiliation(s)
- Mohammad Seyedabadi
- Department of Pharmacology, School of Medicine, Bushehr University of Medical Sciences, Iran; Education Development Center, Bushehr University of Medical Sciences, Iran
| | | | - Paul R Albert
- Ottawa Hospital Research Institute, Neuroscience, University of Ottawa, Canada.
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7
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Kumar A, Plückthun A. In vivo assembly and large-scale purification of a GPCR - Gα fusion with Gβγ, and characterization of the active complex. PLoS One 2019; 14:e0210131. [PMID: 30620756 PMCID: PMC6324789 DOI: 10.1371/journal.pone.0210131] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 12/04/2018] [Indexed: 12/13/2022] Open
Abstract
G protein coupled receptors (GPCRs) are central players in recognizing a variety of stimuli to mediate diverse cellular responses. This myriad of functions is accomplished by their modular interactions with downstream intracellular transducers, such as heterotrimeric G proteins and arrestins. Assembling a specific GPCR-G protein pair as a purified complex for their structural and functional investigations remains a challenging task, however, because of the low affinity of the interaction. Here, we optimized fusion constructs of the Gα subunit of the heterotrimeric G protein and engineered versions of rat Neurotensin receptor 1 (NTR1), coexpressed and assembled in vivo with Gβ and Gγ. This was achieved by using the baculovirus-based MultiBac system. We thus generated a functional receptor-G protein fusion complex, which can be efficiently purified using ligand-based affinity chromatography on large scales. Additionally, we utilized a purification method based on a designed ankyrin repeat protein tightly binding to Green Fluorescent Protein (GFP-DARPin) that may be used as a generic approach for a large-scale purification of GPCR-G protein fusion complexes for which no ligands column can be generated. The purification methods described herein will support future studies that aim to understand the structural and functional framework of GPCR activation and signaling.
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Affiliation(s)
- Abhinav Kumar
- Department of Biochemistry, University of Zürich, Zürich, Switzerland
| | - Andreas Plückthun
- Department of Biochemistry, University of Zürich, Zürich, Switzerland
- * E-mail:
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8
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Redegeld FA, Yu Y, Kumari S, Charles N, Blank U. Non-IgE mediated mast cell activation. Immunol Rev 2018; 282:87-113. [DOI: 10.1111/imr.12629] [Citation(s) in RCA: 101] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Frank A. Redegeld
- Division of Pharmacology; Utrecht Institute for Pharmaceutical Sciences; Utrecht University; Utrecht The Netherlands
| | - Yingxin Yu
- Division of Pharmacology; Utrecht Institute for Pharmaceutical Sciences; Utrecht University; Utrecht The Netherlands
| | - Sangeeta Kumari
- Division of Pharmacology; Utrecht Institute for Pharmaceutical Sciences; Utrecht University; Utrecht The Netherlands
| | - Nicolas Charles
- INSERM U1149; Centre de Recherche sur l'Inflammation; Paris France
- CNRS ERL8252; Paris France
- Université Paris-Diderot; Sorbonne Paris Cité; Faculté de Médecine; Site Xavier Bichat; Paris France
| | - Ulrich Blank
- INSERM U1149; Centre de Recherche sur l'Inflammation; Paris France
- CNRS ERL8252; Paris France
- Université Paris-Diderot; Sorbonne Paris Cité; Faculté de Médecine; Site Xavier Bichat; Paris France
- Inflamex Laboratory of Excellence; Paris France
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9
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Besserer-Offroy É, Brouillette RL, Lavenus S, Froehlich U, Brumwell A, Murza A, Longpré JM, Marsault É, Grandbois M, Sarret P, Leduc R. The signaling signature of the neurotensin type 1 receptor with endogenous ligands. Eur J Pharmacol 2017; 805:1-13. [DOI: 10.1016/j.ejphar.2017.03.046] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 03/15/2017] [Accepted: 03/21/2017] [Indexed: 12/17/2022]
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10
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Lau KM, Ma FMT, Xia JT, Chan QKY, Ng CF, To KF. Activation of GPR30 stimulates GTP-binding of Gαi1 protein to sustain activation of Erk1/2 in inhibition of prostate cancer cell growth and modulates metastatic properties. Exp Cell Res 2016; 350:199-209. [PMID: 27908592 DOI: 10.1016/j.yexcr.2016.11.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 11/11/2016] [Accepted: 11/27/2016] [Indexed: 12/27/2022]
Abstract
Previously, we reported that GPR30 activation by the receptor-specific, non-estrogenic ligand G-1 inhibited in vitro and in vivo growth of prostate cancer (PCa) cells via sustained Erk1/2 activation. Mechanism underlying the sustained Erk1/2 activation for PCa cell growth inhibition remains unclear. Here we report that G-1, through GPR30, activated Gαi1 proteins to sustain Erk1/2 activation but failed to activate adenylyl cyclase (AC) for cAMP production in PCa cells. The chemical-induced activation of AC-cAMP-PKA signaling attenuated Erk1/2 activity and blocked the cell growth inhibitory effects of G-1. Furthermore, PCa predominantly expressed Gαi1 proteins. Silencing of Gαi1 expression blocked the inhibitory effects of G-1 on PCa cell growth. By gene expression profiling, GPR30 activation by G-1 interfered expression of cell cycle regulators and machinery elements to modulate PCa cell growth and the RACGAP1 interactome to control metastatic properties. In this regard, we demonstrated that G-1 inhibited PCa cell migration and invasion with reduced formations of filopodia and stress fibers through a GPR30-dependent pathway. Taken together, our findings revealed the underlying mechanism for sustaining Erk1/2 activation upon GPR30 activation by G-1 in PCa cells and the GPR30-mediated pathways in controlling PCa cell growth and metastatic properties.
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Affiliation(s)
- Kin-Mang Lau
- Department of Anatomical and Cellular Pathology, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China.
| | - Fanny Man-Ting Ma
- Department of Anatomical and Cellular Pathology, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Jenny Tian Xia
- Department of Anatomical and Cellular Pathology, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Queeny Kwan Yi Chan
- Department of Anatomical and Cellular Pathology, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Chi-Fai Ng
- Division of Urology, Department of Surgery, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Ka-Fai To
- Department of Anatomical and Cellular Pathology, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China.
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11
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Bolivar JH, Muñoz-García JC, Castro-Dopico T, Dijkman PM, Stansfeld PJ, Watts A. Interaction of lipids with the neurotensin receptor 1. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:1278-87. [DOI: 10.1016/j.bbamem.2016.02.032] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 02/02/2016] [Accepted: 02/24/2016] [Indexed: 10/22/2022]
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12
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Adamson RJ, Watts A. Kinetics of the early events of GPCR signalling. FEBS Lett 2014; 588:4701-7. [PMID: 25447525 PMCID: PMC4266533 DOI: 10.1016/j.febslet.2014.10.043] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 10/10/2014] [Accepted: 10/27/2014] [Indexed: 11/28/2022]
Abstract
Little is known of the kinetics of interactions between GPCRs and their signalling partners. NTS1 binds Gαi1 and Gαs with affinities of 15 ± 6 nM and 31 ± 18 nM (SE), respectively. This SPR assay may be applicable to multiple partners in the signalling cascade. We provide the first direct evidence for GPCR-G protein coupling in nanodiscs.
Neurotensin receptor type 1 (NTS1) is a G protein-coupled receptor (GPCR) that affects cellular responses by initiating a cascade of interactions through G proteins. The kinetic details for these interactions are not well-known. Here, NTS1-nanodisc-Gαs and Gαi1 interactions were studied. The binding affinities of Gαi1 and Gαs to NTS1 were directly measured by surface plasmon resonance (SPR) and determined to be 15 ± 6 nM and 31 ± 18 nM, respectively. This SPR configuration permits the kinetics of early events in signalling pathways to be explored and can be used to initiate descriptions of the GPCR interactome.
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Affiliation(s)
- Roslin J Adamson
- Biomembrane Structure Unit, Biochemistry Department, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Anthony Watts
- Biomembrane Structure Unit, Biochemistry Department, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
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13
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Nimitvilai S, Arora DS, McElvain MA, Brodie MS. Suppression of Gq Function Using Intra-Pipette Delivery of shRNA during Extracellular Recording in the Ventral Tegmental Area. Front Cell Neurosci 2013; 7:7. [PMID: 23408114 PMCID: PMC3569574 DOI: 10.3389/fncel.2013.00007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 01/16/2013] [Indexed: 11/13/2022] Open
Abstract
Selective suppression of protein function in the brain can be achieved using specific silencing RNAs administered in vivo. A viral delivery system is often employed to transfect neurons with small hairpin RNA (shRNA) directed against specific proteins, and intervals of several days are allowed between microinjection of the shRNA-containing virus into the brain and experiments to assess suppression of gene function. Here we report studies using extracellular recording of dopaminergic neurons of the ventral tegmental area (DA VTA neurons) recorded in brain slices in which lentivirus containing shRNA directed against Gq was included in the recording pipette, and suppression of Gq-related function was observed within the time frame of the recording. The action of neurotensin (NT) is associated with activation of Gq, and the firing rate of DA VTA neurons is increased by NT. With shRNA directed against Gq in the pipette, there was a significant reduction of NT excitation within 2 h. Likewise, time-dependent dopamine desensitization, which we have hypothesized to be Gq-dependent, was not observed when shRNA directed against Gq was present in the pipette and dopamine was tested 2 h after initiation of recording. As the time interval (2 h) is relatively short, we tested whether blockade of protein synthesis with cycloheximide delivered via the recording pipette would alter Gq-linked responses similarly. Both NT-induced excitation and dopamine desensitization were inhibited in the presence of cycloheximide. Inclusion of shRNA in the recording pipette may be an efficient and selective way to dampen responses linked to Gq, and, more generally, the use of lentiviral-packaged shRNA in the recording pipette is a means to produce selective inhibition of the function of specific proteins in experiments.
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Affiliation(s)
- Sudarat Nimitvilai
- Department of Physiology and Biophysics, University of Illinois at Chicago Chicago, IL, USA
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14
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van Rijn RM, Harvey JH, Brissett DI, DeFriel JN, Whistler JL. Novel screening assay for the selective detection of G-protein-coupled receptor heteromer signaling. J Pharmacol Exp Ther 2012; 344:179-88. [PMID: 23097213 DOI: 10.1124/jpet.112.198655] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Drugs targeting G-protein-coupled receptors (GPCRs) make up more than 25% of all prescribed medicines. The ability of GPCRs to form heteromers with unique signaling properties suggests an entirely new and unexplored pool of drug targets. However, current in vitro assays are ill equipped to detect heteromer-selective compounds. We have successfully adapted an approach, using fusion proteins of GPCRs and chimeric G proteins, to create an in vitro screening assay (in human embryonic kidney cells) in which only activated heteromers are detectable. Here we show that this assay can demonstrate heteromer-selective G-protein bias as well as measure transinhibition. Using this assay, we reveal that the δ-opioid receptor agonist ADL5859, which is currently in clinical trials, has a 10-fold higher potency against δ-opioid receptor homomers than δ/μ-opioid receptor heteromers (pEC(50) = 6.7 ± 0.1 versus 5.8 ± 0.2). The assay enables the screening of large compound libraries to identify heteromer-selective compounds that could then be used in vivo to determine the functional role of heteromers and develop potential therapeutic agents.
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Affiliation(s)
- Richard M van Rijn
- Ernest Gallo Clinic and Research Center, Department of Neurology, University of California, San Francisco, 5858 Horton Street, Suite 200, Emeryville, CA 94608, USA.
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Nimitvilai S, Arora DS, Brodie MS. Reversal of dopamine inhibition of dopaminergic neurons of the ventral tegmental area is mediated by protein kinase C. Neuropsychopharmacology 2012; 37:543-56. [PMID: 21976045 PMCID: PMC3242316 DOI: 10.1038/npp.2011.222] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Adaptation of putative dopaminergic (pDA) neurons in the ventral tegmental area (VTA) to drugs of abuse may alter information processing related to reward and reinforcement and is an important factor in the development of addiction. We have demonstrated that prolonged increases in the concentration of dopamine (DA) result in a time-dependent decrease in sensitivity of pDA neurons to DA, which we termed DA inhibition reversal (DIR). In this study, we used extracellular recordings to examine factors mediating DIR. A 40 min administration of DA (2.5-10 μM), but not the DA D2 receptor agonist quinpirole (50-200 nM), resulted in inhibition of neuronal firing followed by DIR. In the presence of 100 nM cocaine, inhibition followed by DIR was seen with much lower DA concentrations. Reversal of quinpirole inhibition could be induced by an activator of protein kinase C, but not of protein kinase A. Inhibitors of protein kinase C or phospholipase C blocked the development of DIR. Disruption of intracellular calcium release also prevented DIR. Reduction of extracellular calcium or inhibition of store-operated calcium entry blocked DIR, but the L-type calcium channel blocker nifedipine did not. DIR was age-dependent and not seen in pDA VTA neurons from rat pups younger than 15 days postnatally. Our data indicate that DIR is mediated by protein kinase C, and implicate a conventional protein kinase C. This characterization of DIR gives insight into the regulation of autoinhibition of pDA VTA neurons, and the resulting long-term alteration in information processing related to reward and reinforcement.
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Affiliation(s)
- Sudarat Nimitvilai
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, USA
| | - Devinder S Arora
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, USA
| | - Mark S Brodie
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, USA,Department of Physiology and Biophysics, University of Illinois at Chicago, 835 South Wolcott, Room E-202, M/C 901, Chicago, IL 60612-7342, USA, Tel: +1 312 996 2373, Fax: +1 312 996 1414, E-mail:
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16
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Oates J, Watts A. Uncovering the intimate relationship between lipids, cholesterol and GPCR activation. Curr Opin Struct Biol 2011; 21:802-7. [DOI: 10.1016/j.sbi.2011.09.007] [Citation(s) in RCA: 185] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 09/23/2011] [Accepted: 09/29/2011] [Indexed: 11/16/2022]
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Directed evolution of a G protein-coupled receptor for expression, stability, and binding selectivity. Proc Natl Acad Sci U S A 2008; 105:14808-13. [PMID: 18812512 DOI: 10.1073/pnas.0803103105] [Citation(s) in RCA: 152] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We outline a powerful method for the directed evolution of integral membrane proteins in the inner membrane of Escherichia coli. For a mammalian G protein-coupled receptor, we arrived at a sequence with an order-of-magnitude increase in functional expression that still retains the biochemical properties of wild type. This mutant also shows enhanced heterologous expression in eukaryotes (12-fold in Pichia pastoris and 3-fold in HEK293T cells) and greater stability when solubilized and purified, indicating that the biophysical properties of the protein had been under the pressure of selection. These improvements arise from multiple small contributions, which would be difficult to assemble by rational design. In a second screen, we rapidly pinpointed a single amino acid substitution in wild type that abolishes antagonist binding while retaining agonist-binding affinity. These approaches may alleviate existing bottlenecks in structural studies of these targets by providing sufficient quantities of stable variants in defined conformational states.
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Mancia F, Hendrickson WA. Expression of recombinant G-protein coupled receptors for structural biology. MOLECULAR BIOSYSTEMS 2007; 3:723-34. [PMID: 17882334 DOI: 10.1039/b713558k] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Filippo Mancia
- Howard Hughes Medical Institute and Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
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19
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Suga H, Haga T. Ligand screening system using fusion proteins of G protein-coupled receptors with G protein alpha subunits. Neurochem Int 2007; 51:140-64. [PMID: 17659814 DOI: 10.1016/j.neuint.2007.06.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2007] [Revised: 06/07/2007] [Accepted: 06/08/2007] [Indexed: 01/04/2023]
Abstract
G protein-coupled receptors (GPCRs) constitute one of the largest families of genes in the human genome, and are the largest targets for drug development. Although a large number of GPCR genes have recently been identified, ligands have not yet been identified for many of them. Various assay systems have been employed to identify ligands for orphan GPCRs, but there is still no simple and general method to screen for ligands of such GPCRs, particularly of G(i)-coupled receptors. We have examined whether fusion proteins of GPCRs with G protein alpha subunit (Galpha) could be utilized for ligand screening and showed that the fusion proteins provide an effective method for the purpose. This article focuses on the followings: (1) characterization of GPCR genes and GPCRs, (2) identification of ligands for orphan GPCRs, (3) characterization of GPCR-Galpha fusion proteins, and (4) identification of ligands for orphan GPCRs using GPCR-Galpha fusion proteins.
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Affiliation(s)
- Hinako Suga
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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Abstract
Three neurotensin (NT) receptors have been cloned to date, two of which, NTS1 and NTS2, belong to the family of seven transmembrane domain receptors coupled to G proteins (GPCRs). NTS1 and NTS2 may activate multiple signal transduction pathways, involving several G proteins. However, whereas NT acts as an agonist towards all NTS1-mediated pathways, this peptide may exert either agonist or antagonist activities, depending on the NTS2-mediated pathway in question. Studies on these receptors reinforce the concept of independence between multiple signals potentially mediated through a single GPCR, generating a wide diversity of functional responses depending on the host cell and the ligand.
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Affiliation(s)
- Didier Pelaprat
- INSERM, U.773, CRB3, EA 3512, Faculté de Médecine Xavier Bichat, 16 rue Henri Huchard, BP416, 75870 Paris Cedex 18, France.
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Grisshammer R, White JF, Trinh LB, Shiloach J. Large-scale expression and purification of a G-protein-coupled receptor for structure determination -- an overview. ACTA ACUST UNITED AC 2006; 6:159-63. [PMID: 16211513 DOI: 10.1007/s10969-005-1917-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2004] [Accepted: 01/16/2005] [Indexed: 10/25/2022]
Abstract
Structure determination of G-protein-coupled receptors and other applications, such as nuclear magnetic resonance studies, require milligram quantities of purified, functional receptor protein on a regular basis. We present an overview on expression and purification studies with a receptor for neurotensin. Functional expression in Escherichia coli and an automated two-column purification routine allow ongoing crystallization experiments and studies on receptor-bound ligands.
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Affiliation(s)
- Reinhard Grisshammer
- Laboratory of Molecular Biology of the National Institute of Diabetes and Digestive and Kidney Diseases, Department of Health and Human Services, National Institutes of Health, Bethesda, Maryland 20892, USA.
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22
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Zuo X, Li S, Hall J, Mattern MR, Tran H, Shoo J, Tan R, Weiss SR, Butt TR. Enhanced expression and purification of membrane proteins by SUMO fusion in Escherichia coli. ACTA ACUST UNITED AC 2006; 6:103-11. [PMID: 16211506 PMCID: PMC7088008 DOI: 10.1007/s10969-005-2664-4] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2004] [Accepted: 01/16/2005] [Indexed: 11/30/2022]
Abstract
Severe acute respiratory syndrome coronavirus (SARS-CoV) membrane protein and 5-lipoxygenase-activating protein (FLAP) are among a large number of membrane proteins that are poorly expressed when traditional expression systems and methods are employed. Therefore to efficiently express difficult membrane proteins, molecular biologists will have to develop novel or innovative expression systems. To this end, we have expressed the SARS-CoV M and FLAP proteins in Escherichia coli by utilizing a novel gene fusion expression system that takes advantage of the natural chaperoning properties of the SUMO (small ubiquitin-related modifier) tag. These chaperoning properties facilitate proper protein folding, which enhances the solubility and biological activity of the purified protein. In addition to these advantages, we found that SUMO Protease 1, can cleave the SUMO fusion high specificity to generate native protein. Herein, we demonstrate that the expression of FLAP and SARS-CoV membrane proteins are greatly enhanced by SUMO fusions in E. coli.
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Affiliation(s)
- Xun Zuo
- LifeSensors, Inc., 271 Great Valley Parkway, Malvern, PA 19355 USA
| | - Shuisen Li
- School of BioMedical Engineering, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 USA
| | - John Hall
- LifeSensors, Inc., 271 Great Valley Parkway, Malvern, PA 19355 USA
| | | | - Hiep Tran
- LifeSensors, Inc., 271 Great Valley Parkway, Malvern, PA 19355 USA
| | - Joshua Shoo
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260
| | - Robin Tan
- Department of Biological Sciences, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260
| | - Susan R. Weiss
- Department of Microbiology, University of Pennsylvania Medical School, Philadelphia, PA 19104 USA
| | - Tauseef R. Butt
- LifeSensors, Inc., 271 Great Valley Parkway, Malvern, PA 19355 USA
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Chao C, Tallman ML, Ives KL, Townsend CM, Hellmich MR. Gastrointestinal hormone receptors in primary human colorectal carcinomas. J Surg Res 2005; 129:313-21. [PMID: 16051276 DOI: 10.1016/j.jss.2005.04.038] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2005] [Revised: 04/25/2005] [Accepted: 04/26/2005] [Indexed: 10/25/2022]
Abstract
BACKGROUND In this study, the prevalence and identity of the cells expressing functional receptors for the gastrointestinal (GI) peptide hormones: gastrin, bombesin, and neurotensin in dissociated cells from 20 freshly resected human primary colorectal carcinomas were determined. MATERIALS AND METHODS GI peptide hormone-induced increases in the concentration of free intracellular Ca(2+) ([Ca(2+)](i)) were used as an assay for the detection of functional receptors. Reverse-transcription polymerase chain reaction (RT-PCR) was performed in a subset of tumor samples. Agonist-responsive cells were identified as either of epithelial or stromal origin by immunocytochemistry with cytokeratin and vimentin antibodies, respectively. RESULTS Overall, expression of GI peptide hormone receptors was more frequent in stromal cells when compared to epithelial cells. Of the three receptors, expression of bombesin receptor (95%) was most prevalent in vimentin-positive (stromal) cells; whereas, gastrin receptor expression by cytokeratin-positive (epithelial) cells was more common (39%). A single gastrin receptor splice variant differentially regulates [Ca(2+)](i) in a cell-type specific manner. The gastrin receptor-expression profile in the 11 colon cancer-derived cell lines did not reflect the prevalence of expression in primary human cancers. CONCLUSIONS The Ca(2+) assay is a sensitive method for detecting functional GI peptide hormone receptor expression by colon cancer cells. Because this approach utilizes living cells, it is amenable to further functional analyses of signal transduction mechanisms at the single cell level. Importantly, our data provide a rationale for examining of the role of these GI peptide hormones and their cognate receptors in mesenchymal cell biology.
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Affiliation(s)
- Celia Chao
- Department of Surgery, The University of Texas Medical Branch, Galveston, Texas 77555, USA
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St-Gelais F, Legault M, Bourque MJ, Rompré PP, Trudeau LE. Role of calcium in neurotensin-evoked enhancement in firing in mesencephalic dopamine neurons. J Neurosci 2004; 24:2566-74. [PMID: 15014132 PMCID: PMC6729478 DOI: 10.1523/jneurosci.5376-03.2004] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Neurotensin (NT) increases neurotransmission within the mesolimbic dopamine system by enhancing the firing rate of dopaminergic (DAergic) neurons and by acting at the nerve terminal level. The signal transduction pathways involved in these effects have not been characterized, but NT receptors are coupled to the phospholipase C pathway and Ca(2+) mobilization. However, an enhancement of intracellular Ca(2+) concentration ([Ca(2+)](i)) evoked by NT in DAergic neurons has yet to be demonstrated. Furthermore, the hypothesis that the excitatory effects of NT in DAergic neurons are Ca(2+) dependent is currently untested. In whole-cell recording experiments, DAergic neurons in culture were identified by their selective ability to express a cell-specific green fluorescent protein reporter construct. These experiments confirmed that NT increases firing rate in cultured DAergic neurons. This effect was Ca(2+) dependent because it was blocked by intracellular dialysis with BAPTA. Using Ca(2+) imaging, we showed that NT caused a rapid increase in [Ca(2+)](i) in DAergic neurons. Most of the Ca(2+) originated from the extracellular medium. NT-induced excitation and Ca(2+) influx were blocked by SR48692, an antagonist of the type 1 NT receptor. Blocking IP(3) receptors using heparin prevented the excitatory effect of NT. Moreover, Zn(2+) and SKF96365 both blocked the excitatory effect of NT, suggesting that nonselective cationic conductances are involved. Finally, although NT can also induce a rise in [Ca(2+)](i) in astrocytes, we find that NT-evoked excitation of DAergic neurons can occur independently of astrocyte activation.
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Affiliation(s)
- Fannie St-Gelais
- Département de Pharmacologie, Centre de Recherche en Sciences Neurologiques, Université de Montréal, Montréal, Québec, Canada H3T IJ4
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Abstract
Receptors of the of seven transmembrane spanning, heterotrimeric G protein coupled family (GPCR) play crucial roles in regulating physiological functions and consequently are targets for the action of many classes of drugs. Activation of receptor by agonist leads to the dissociation of GDP from Galpha of the Galphabetagamma heterotrimer, followed by the binding of GTP to Galpha and subsequent modulation of downstream effectors. The G protein heterotrimer is reformed by GTPase activity of the Galpha subunit, forming Galpha-GDP and so allowing Galpha and Gbetagamma to recombine. The [35S]GTPgammaS assay measures the level of G protein activation following agonist occupation of a GPCR, by determining the binding of the non-hydrolyzable analog [35S]GTPgammaS to Galpha subunits. Thus, the assay measures a functional consequence of receptor occupancy at one of the earliest receptor-mediated events. The assay allows for traditional pharmacological parameters of potency, efficacy and antagonist affinity, with the advantage that agonist measures are not subjected to amplification or other modulation that may occur when analyzing parameters further downstream of the receptor. In general the assay is experimentally more feasible for receptors coupled to the abundant G(i/o) proteins. Nevertheless, [35S]GTPgammaS binding assays are used with GPCRs that couple to the G(s) and G(q) families of G proteins, especially in artificial expression systems, or using receptor-Galpha constructs or immunoprecipitation of [35S]GTPgammaS-labeled Galpha. The relative simplicity of the assay has made it very popular and its use is providing insights into contemporary pharmacological topics including the roles of accessory proteins in signaling, constitutive activity of receptors and agonist specific signaling.
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Affiliation(s)
- C Harrison
- Department of Pharmacology, University of Michigan Medical School, 1301 MSRB III, West Medical Center Drive, Ann Arbor, MI 48109-0632, USA
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Luca S, White JF, Sohal AK, Filippov DV, van Boom JH, Grisshammer R, Baldus M. The conformation of neurotensin bound to its G protein-coupled receptor. Proc Natl Acad Sci U S A 2003; 100:10706-11. [PMID: 12960362 PMCID: PMC196868 DOI: 10.1073/pnas.1834523100] [Citation(s) in RCA: 200] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2003] [Indexed: 11/18/2022] Open
Abstract
G protein-coupled receptors (GPCRs) mediate the perception of smell, light, taste, and pain. They are involved in signal recognition and cell communication and are some of the most important targets for drug development. Because currently no direct structural information on high-affinity ligands bound to GPCRs is available, rational drug design is limited to computational prediction combined with mutagenesis experiments. Here, we present the conformation of a high-affinity peptide agonist (neurotensin, NT) bound to its GPCR NTS-1, determined by direct structural methods. Functional receptors were expressed in Escherichia coli, purified in milligram amounts by using optimized procedures, and subsequently reconstituted into lipid vesicles. Solid-state NMR experiments were tailored to allow for the unequivocal detection of microgram quantities of 13C,15N-labeled NT(8-13) in complex with functional NTS-1. The NMR data are consistent with a disordered state of the ligand in the absence of receptor. Upon receptor binding, the peptide undergoes a linear rearrangement, adopting a beta-strand conformation. Our results provide a viable structural template for further pharmacological investigations.
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Affiliation(s)
- Sorin Luca
- Department of NMR-Based Structural Biology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
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Hermans E. Biochemical and pharmacological control of the multiplicity of coupling at G-protein-coupled receptors. Pharmacol Ther 2003; 99:25-44. [PMID: 12804697 DOI: 10.1016/s0163-7258(03)00051-2] [Citation(s) in RCA: 221] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
For decades, it has been generally proposed that a given receptor always interacts with a particular GTP-binding protein (G-protein) or with multiple G-proteins within one family. However, for several G-protein-coupled receptors (GPCR), it now becomes generally accepted that simultaneous functional coupling with distinct unrelated G-proteins can be observed, leading to the activation of multiple intracellular effectors with distinct efficacies and/or potencies. Multiplicity in G-protein coupling is frequently observed in artificial expression systems where high densities of receptors are obtained, raising the question of whether such complex signalling reveals artefactual promiscuous coupling or is a genuine property of GPCRs. Multiple biochemical and pharmacological evidence in favour of an intrinsic property of GPCRs were obtained in recent studies. Thus, there are now many examples showing that the coupling to multiple signalling pathways is dependent on the agonist used (agonist trafficking of receptor signals). In addition, the different couplings were demonstrated to involve distinct molecular determinants of the receptor and to show distinct desensitisation kinetics. Such multiplicity of signalling at the level of G-protein coupling leads to a further complexity in the functional response to agonist stimulation of one of the most elaborate cellular transmission systems. Indeed, the physiological relevance of such versatility in signalling associated with a single receptor requires the existence of critical mechanisms of dynamic regulation of the expression, the compartmentalisation, and the activity of the signalling partners. This review aims at summarising the different studies that support the concept of multiplicity of G-protein coupling. The physiological and pharmacological relevance of this coupling promiscuity will be discussed.
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Affiliation(s)
- Emmanuel Hermans
- Laboratoire de Pharmacologie Expérimentale, Université Catholique de Louvain, FARL 54.10, Avenue Hippocrate 54, B-1200 Brussels, Belgium.
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Najimi M, Gailly P, Maloteaux JM, Hermans E. Distinct regions of C-terminus of the high affinity neurotensin receptor mediate the functional coupling with pertussis toxin sensitive and insensitive G-proteins. FEBS Lett 2002; 512:329-33. [PMID: 11852105 DOI: 10.1016/s0014-5793(02)02285-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The functional coupling of C-terminally truncated mutants of the high affinity rat neurotensin (NT) receptor (NTS1) was characterized in transfected Chinese hamster ovary cells. On cells expressing NTRDelta372 (truncated NTS1 lacking the entire 52 amino acid C-terminus), NT failed to promote [(35)S]guanosine 5'-[gamma-(35)S]triphosphate binding whereas a robust pertussis toxin (PTx) sensitive response was observed in cells expressing a partially truncated receptor (NTRDelta401 lacking the last 23 residues). Similar results were obtained when measuring the ability of NT to induce the production of arachidonic acid. Since neither deletions impaired the NT-induced phosphoinositide hydrolysis, these results indicate that the membrane proximal region of the C-terminus is specifically involved in the functional coupling of the receptor with PTx sensitive G-proteins. This region was also found to be involved in the control of receptor internalization. However, PTx failed to impair internalization, indicating that these two properties are not directly related.
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Affiliation(s)
- Mustapha Najimi
- Laboratoire de Pharmacologie Exprimentale (FARL), Département de Physiologie et de Pharmacologie, Université catholique de Louvain 54.10, Avenue Hippocrate 54, B-1200, Brussels, Belgium
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