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Beheshti S, Ershadi S, Zamani F, Azimzadeh M, Wesal MW. Differential impact of a ghrelin receptor antagonist or inverse agonist in the electrical kindling model of epilepsy. Epilepsy Res 2023; 197:107234. [PMID: 37793283 DOI: 10.1016/j.eplepsyres.2023.107234] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 09/23/2023] [Accepted: 09/28/2023] [Indexed: 10/06/2023]
Abstract
Ghrelin is a peptide, which has been shown to affect seizures. However, there is not a consensus about its real impact on the control of seizure severity. We assessed the influence of intra-amygdala injections of a ghrelin receptor (GHSR) antagonist, as well as a GHSR inverse agonist on the electrical kindling-induced seizures. Two unipolar electrodes and a tripolar electrode twisted with a guide cannula were implanted in the skull surface or the basolateral amygdala of adult male rats, respectively. A rapid electrical kindling protocol was applied for kindling epileptogenesis. The stimulations were applied until rats showed three consecutive stage five seizures. Each rat was considered as its control. D-Lys-3-GHRP-6 (1, 12.5, and 25 μg/rat) or [D-Arg, D-phe, D-Trp, heu] substance P (D-SP) (50, 500 and 5000 ng/rat) as the GHSR antagonist or inverse agonist were injected into the basolateral amygdala. Seizure parameters including after-discharge duration (ADD), stage five duration (S5D), and seizure stage (SS) were documented thirty minutes following administration of the drugs or saline. Antagonism of the GHSR in the amygdala, significantly increased seizure induction in the kindled rats, in a dose-dependent manner, and induced spontaneous seizures leading to status epilepticus. Conversely, D-SP had a dose-dependent anticonvulsant activity, indicated by decreased ADD and S5D. The results show that GHSR inverse agonism suppressed seizure severity in the rat amygdala kindling model, whereas GHSR antagonism made seizures more severe. Therefore, when considering the ghrelin system to modulate seizures, it is crucial to note the differential impact of various GHSR ligands.
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Affiliation(s)
- Siamak Beheshti
- Department of Plant and Animal Biology, Faculty of Biological Science and Technology, University of Isfahan, Isfahan, Iran.
| | - Shiva Ershadi
- Department of Plant and Animal Biology, Faculty of Biological Science and Technology, University of Isfahan, Isfahan, Iran
| | - Fatemeh Zamani
- Department of Plant and Animal Biology, Faculty of Biological Science and Technology, University of Isfahan, Isfahan, Iran
| | - Mansour Azimzadeh
- Department of Plant and Animal Biology, Faculty of Biological Science and Technology, University of Isfahan, Isfahan, Iran; Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Universiti Putra Malaysis, 43400 UPM Serdang, Selangor, Malaysia
| | - Mohammad Wasil Wesal
- Department of Biology, Faculty of Education, University of Ghazni, Gazni, Afghanistan
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2
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Yasuda D, Hamano F, Masuda K, Dahlström M, Kobayashi D, Sato N, Hamakubo T, Shimizu T, Ishii S. Inverse agonism of lysophospholipids with cationic head groups at Gi-coupled receptor GPR82. Eur J Pharmacol 2023; 954:175893. [PMID: 37392830 DOI: 10.1016/j.ejphar.2023.175893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 06/20/2023] [Accepted: 06/28/2023] [Indexed: 07/03/2023]
Abstract
GPR82 is an orphan G protein-coupled receptor (GPCR) that has been implicated in lipid storage in mouse adipocytes. However, the intracellular signaling as well as the specific ligands of GPR82 remain unknown. GPR82 is closely related to GPR34, a GPCR for the bioactive lipid molecule lysophosphatidylserine. In this study, we screened a lipid library using GPR82-transfected cells to search for ligands that act on GPR82. By measuring cyclic adenosine monophosphate levels, we found that GPR82 is an apparently constitutively active GPCR that leads to Gi protein activation. In addition, edelfosine (1-O-octadecyl-2-O-methyl-sn-glycero-3-phosphocholine), an artificial lysophospholipid with a cationic head group that exerts antitumor activity, inhibited the Gi protein activation by GPR82. Two endogenous lysophospholipids with cationic head groups, lysophosphatidylcholine (1-oleoyl-sn-glycero-3-phosphocholine) and lysophosphatidylethanolamine (1-oleoyl-sn-glycero-3-phosphoethanolamine), also exhibited GPR82 inhibitory activity, albeit weaker than edelfosine. Förster resonance energy transfer imaging analysis consistently demonstrated that Gi protein-coupled GPR82 has an apparent constitutive activity that is edelfosine-sensitive. Consistent data were obtained from GPR82-mediated binding analysis of guanosine-5'-O-(3-thiotriphosphate) to cell membranes. Furthermore, in GPR82-transfected cells, edelfosine inhibited insulin-induced extracellular signal-regulated kinase activation, like compounds that function as inverse agonists at other GPCRs. Therefore, edelfosine is likely to act as an inverse agonist of GPR82. Finally, GPR82 expression inhibited adipocyte lipolysis, which was abrogated by edelfosine. Our findings suggested that the cationic lysophospholipids edelfosine, lysophosphatidylcholine and lysophosphatidylethanolamine are novel inverse agonists for Gi-coupled GPR82, which is apparently constitutively active, and has the potential to exert lipolytic effects through GPR82.
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Affiliation(s)
- Daisuke Yasuda
- Department of Immunology, Graduate School of Medicine, Akita University, Akita, Japan
| | - Fumie Hamano
- Life Sciences Core Facility, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Kazuyuki Masuda
- Department of Quantitative Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | | | - Daiki Kobayashi
- Department of Immunology, Graduate School of Medicine, Akita University, Akita, Japan
| | - Nana Sato
- Department of Immunology, Graduate School of Medicine, Akita University, Akita, Japan
| | - Takao Hamakubo
- Department of Quantitative Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Takao Shimizu
- Department of Lipid Life Science, National Center for Global Health and Medicine, Tokyo, Japan; Institute of Microbial Chemistry, Tokyo, Japan
| | - Satoshi Ishii
- Department of Immunology, Graduate School of Medicine, Akita University, Akita, Japan.
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Functions of the Zinc-Sensing Receptor GPR39 in Regulating Intestinal Health in Animals. Int J Mol Sci 2022; 23:ijms232012133. [PMID: 36292986 PMCID: PMC9602648 DOI: 10.3390/ijms232012133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 10/08/2022] [Accepted: 10/10/2022] [Indexed: 11/17/2022] Open
Abstract
G protein-coupled receptor 39 (GPR39) is a zinc-sensing receptor (ZnR) that can sense changes in extracellular Zn2+, mediate Zn2+ signal transmission, and participate in the regulation of numerous physiological activities in living organisms. For example, GPR39 activates the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) and phosphatidylinositol3-kinase/protein kinase B (PI3K/AKT) signaling pathways upon Zn2+ stimulation, enhances the proliferation and differentiation of colonic cells, and regulates ion transport, as well as exerting other functions. In recent years, with the increased attention to animal gut health issues and the intensive research on GPR39, GPR39 has become a potential target for regulating animal intestinal health. On the one hand, GPR39 is involved in regulating ion transport in the animal intestine, mediating the Cl− efflux by activating the K+/Cl− synergistic protein transporter, and relieving diarrhea symptoms. On the other hand, GPR39 can maintain the homeostasis of the animal intestine, promoting pH restoration in colonic cells, regulating gastric acid secretion, and facilitating nutrient absorption. In addition, GPR39 can affect the expression of tight junction proteins in intestinal epithelial cells, improving the barrier function of the animal intestinal mucosa, and maintaining the integrity of the intestine. This review summarizes the structure and signaling transduction processes involving GPR39 and the effect of GPR39 on the regulation of intestinal health in animals, with the aim of further highlighting the role of GPR39 in regulating animal intestinal health and providing new directions and ideas for studying the prevention and treatment of animal intestinal diseases.
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4
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Ringuet MT, Furness JB, Furness SGB. G protein-coupled receptor interactions and modification of signalling involving the ghrelin receptor, GHSR1a. J Neuroendocrinol 2022; 34:e13077. [PMID: 34931385 DOI: 10.1111/jne.13077] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 12/05/2021] [Indexed: 12/28/2022]
Abstract
The growth hormone secretagogue receptor 1a (GHSR1a) is intriguing because of its potential as a therapeutic target and its diverse molecular interactions. Initial studies of the receptor focused on the potential therapeutic ability for growth hormone (GH) release to reduce wasting in aging individuals, as well as food intake regulation for treatment of cachexia. Known roles of GHSR1a now extend to regulation of neurogenesis, learning and memory, gastrointestinal motility, glucose/lipid metabolism, the cardiovascular system, neuronal protection, motivational salience, and hedonic feeding. Ghrelin, the endogenous agonist of GHSR1a, is primarily located in the stomach and is absent from the central nervous system (CNS), including the spinal cord. However, ghrelin in the circulation does have access to a small number of CNS sites, including the arcuate nucleus, which is important in feeding control. At some sites, such as at somatotrophs, GHSR1a has high constitutive activity. Typically, ghrelin-dependent and constitutive GHSR1a activation occurs via Gαq/11 pathways. In vitro and in vivo data suggest that GHSR1a heterodimerises with multiple G protein-coupled receptors (GPCRs), including dopamine D1 and D2, serotonin 2C, orexin, oxytocin and melanocortin 3 receptors (MCR3), as well as the MCR3 accessory protein, MRAP2, providing possible mechanisms for its many physiological effects. In all cases, the receptor interaction changes downstream signalling and the responses to receptor agonists. This review discusses the signalling mechanisms of GHSR1a alone and in combination with other GPCRs, and explores the physiological consequences of GHSR1a coupling with other GPCRs.
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Affiliation(s)
- Mitchell Ty Ringuet
- Department of Anatomy and Physiology, University of Melbourne, Parkville, VIC, Australia
| | - John Barton Furness
- Department of Anatomy and Physiology, University of Melbourne, Parkville, VIC, Australia
- Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia
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Sustkova-Fiserova M, Charalambous C, Khryakova A, Certilina A, Lapka M, Šlamberová R. The Role of Ghrelin/GHS-R1A Signaling in Nonalcohol Drug Addictions. Int J Mol Sci 2022; 23:761. [PMID: 35054944 PMCID: PMC8776007 DOI: 10.3390/ijms23020761] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 01/05/2022] [Accepted: 01/06/2022] [Indexed: 01/27/2023] Open
Abstract
Drug addiction causes constant serious health, social, and economic burden within the human society. The current drug dependence pharmacotherapies, particularly relapse prevention, remain limited, unsatisfactory, unreliable for opioids and tobacco, and even symptomatic for stimulants and cannabinoids, thus, new more effective treatment strategies are researched. The antagonism of the growth hormone secretagogue receptor type A (GHS-R1A) has been recently proposed as a novel alcohol addiction treatment strategy, and it has been intensively studied in experimental models of other addictive drugs, such as nicotine, stimulants, opioids and cannabinoids. The role of ghrelin signaling in these drugs effects has also been investigated. The present review aims to provide a comprehensive overview of preclinical and clinical studies focused on ghrelin's/GHS-R1A possible involvement in these nonalcohol addictive drugs reinforcing effects and addiction. Although the investigation is still in its early stage, majority of the existing reviewed experimental results from rodents with the addition of few human studies, that searched correlations between the genetic variations of the ghrelin signaling or the ghrelin blood content with the addictive drugs effects, have indicated the importance of the ghrelin's/GHS-R1As involvement in the nonalcohol abused drugs pro-addictive effects. Further research is necessary to elucidate the exact involved mechanisms and to verify the future potential utilization and safety of the GHS-R1A antagonism use for these drug addiction therapies, particularly for reducing the risk of relapse.
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Affiliation(s)
- Magdalena Sustkova-Fiserova
- Department of Pharmacology, Third Faculty of Medicine, Charles University, Ruska 87, 100 00 Prague, Czech Republic; (C.C.); (A.K.); (A.C.); (M.L.)
| | - Chrysostomos Charalambous
- Department of Pharmacology, Third Faculty of Medicine, Charles University, Ruska 87, 100 00 Prague, Czech Republic; (C.C.); (A.K.); (A.C.); (M.L.)
| | - Anna Khryakova
- Department of Pharmacology, Third Faculty of Medicine, Charles University, Ruska 87, 100 00 Prague, Czech Republic; (C.C.); (A.K.); (A.C.); (M.L.)
| | - Alina Certilina
- Department of Pharmacology, Third Faculty of Medicine, Charles University, Ruska 87, 100 00 Prague, Czech Republic; (C.C.); (A.K.); (A.C.); (M.L.)
| | - Marek Lapka
- Department of Pharmacology, Third Faculty of Medicine, Charles University, Ruska 87, 100 00 Prague, Czech Republic; (C.C.); (A.K.); (A.C.); (M.L.)
| | - Romana Šlamberová
- Department of Physiology, Third Faculty of Medicine, Charles University, Ke Karlovu 4, 120 00 Prague, Czech Republic;
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Targeting the Ghrelin Receptor as a Novel Therapeutic Option for Epilepsy. Biomedicines 2021; 10:biomedicines10010053. [PMID: 35052733 PMCID: PMC8773216 DOI: 10.3390/biomedicines10010053] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 12/22/2021] [Accepted: 12/24/2021] [Indexed: 12/12/2022] Open
Abstract
Epilepsy is a neurological disease affecting more than 50 million individuals worldwide. Notwithstanding the availability of a broad array of antiseizure drugs (ASDs), 30% of patients suffer from pharmacoresistant epilepsy. This highlights the urgent need for novel therapeutic options, preferably with an emphasis on new targets, since “me too” drugs have been shown to be of no avail. One of the appealing novel targets for ASDs is the ghrelin receptor (ghrelin-R). In epilepsy patients, alterations in the plasma levels of its endogenous ligand, ghrelin, have been described, and various ghrelin-R ligands are anticonvulsant in preclinical seizure and epilepsy models. Up until now, the exact mechanism-of-action of ghrelin-R-mediated anticonvulsant effects has remained poorly understood and is further complicated by multiple downstream signaling pathways and the heteromerization properties of the receptor. This review compiles current knowledge, and discusses the potential mechanisms-of-action of the anticonvulsant effects mediated by the ghrelin-R.
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7
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Xu Y, Barnes AP, Alkayed NJ. Role of GPR39 in Neurovascular Homeostasis and Disease. Int J Mol Sci 2021; 22:8200. [PMID: 34360964 PMCID: PMC8346997 DOI: 10.3390/ijms22158200] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 07/24/2021] [Accepted: 07/26/2021] [Indexed: 12/26/2022] Open
Abstract
GPR39, a member of the ghrelin family of G protein-coupled receptors, is zinc-responsive and contributes to the regulation of diverse neurovascular and neurologic functions. Accumulating evidence suggests a role as a homeostatic regulator of neuronal excitability, vascular tone, and the immune response. We review GPR39 structure, function, and signaling, including constitutive activity and biased signaling, and summarize its expression pattern in the central nervous system. We further discuss its recognized role in neurovascular, neurological, and neuropsychiatric disorders.
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Affiliation(s)
- Yifan Xu
- Department of Anesthesiology and Perioperative Medicine, Oregon Health and Science University, Portland, OR 97239, USA;
| | - Anthony P. Barnes
- Knight Cardiovascular Institute, Oregon Health and Science University, Portland, OR 97239, USA;
| | - Nabil J. Alkayed
- Department of Anesthesiology and Perioperative Medicine, Oregon Health and Science University, Portland, OR 97239, USA;
- Knight Cardiovascular Institute, Oregon Health and Science University, Portland, OR 97239, USA;
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8
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Buckinx A, Pierre A, Van Den Herrewegen Y, Guenther E, Gerlach M, Van Laethem G, Kooijman R, De Bundel D, Smolders I. Translational potential of the ghrelin receptor agonist macimorelin for seizure suppression in pharmacoresistant epilepsy. Eur J Neurol 2021; 28:3100-3112. [PMID: 34157194 DOI: 10.1111/ene.14992] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 06/07/2021] [Accepted: 06/14/2021] [Indexed: 01/26/2023]
Abstract
BACKGROUND Current drugs for epilepsy affect seizures, but no antiepileptogenic or disease-modifying drugs are available that prevent or slow down epileptogenesis, which is characterized by neuronal cell loss, inflammation and aberrant network formation. Ghrelin and ghrelin receptor (ghrelin-R) agonists were previously found to exert anticonvulsant, neuroprotective and anti-inflammatory effects in seizure models and immediately after status epilepticus (SE). Therefore, the aim of this study was to assess whether the ghrelin-R agonist macimorelin is antiepileptogenic in the pharmacoresistant intrahippocampal kainic acid (IHKA) mouse model. METHODS SE was induced in C57BL/6 mice by unilateral IHKA injection. Starting 24 h after SE, mice were treated intraperitoneally with macimorelin (5 mg/kg) or saline twice daily for 2 weeks, followed by a 2-week wash-out. Mice were continuously electroencephalogram-monitored, and at the end of the experiment neuroprotection and gliosis were assessed. RESULTS Macimorelin significantly decreased the number and duration of seizures during the treatment period, but had no antiepileptogenic or disease-modifying effect in this dose regimen. While macimorelin did not significantly affect food intake or body weight over a 2-week treatment period, its acute orexigenic effect was preserved in epileptic mice but not in sham mice. CONCLUSIONS While the full ghrelin-R agonist macimorelin was not significantly antiepileptogenic nor disease-modifying, this is the first study to demonstrate its anticonvulsant effects in the IHKA model of drug-refractory temporal lobe epilepsy. These findings highlight the potential use of macimorelin as a novel treatment option for seizure suppression in pharmacoresistant epilepsy.
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Affiliation(s)
- An Buckinx
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Anouk Pierre
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Yana Van Den Herrewegen
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | | | | | - Gaetan Van Laethem
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Ron Kooijman
- Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Dimitri De Bundel
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Ilse Smolders
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels, Belgium
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9
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Wanka L, Behr V, Beck-Sickinger AG. Arrestin-dependent internalization of rhodopsin-like G protein-coupled receptors. Biol Chem 2021; 403:133-149. [PMID: 34036761 DOI: 10.1515/hsz-2021-0128] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 04/28/2021] [Indexed: 01/14/2023]
Abstract
The internalization of G protein-coupled receptors (GPCRs) is an important mechanism regulating the signal strength and limiting the opportunity of receptor activation. Based on the importance of GPCRs, the detailed knowledge about the regulation of signal transduction is crucial. Here, current knowledge about the agonist-induced, arrestin-dependent internalization process of rhodopsin-like GPCRs is reviewed. Arrestins are conserved molecules that act as key players within the internalization process of many GPCRs. Based on highly conserved structural characteristics within the rhodopsin-like GPCRs, the identification of arrestin interaction sites in model systems can be compared and used for the investigation of internalization processes of other receptors. The increasing understanding of this essential regulation mechanism of receptors can be used for drug development targeting rhodopsin-like GPCRs. Here, we focus on the neuropeptide Y receptor family, as these receptors transmit various physiological processes such as food intake, energy homeostasis, and regulation of emotional behavior, and are further involved in pathophysiological processes like cancer, obesity and mood disorders. Hence, this receptor family represents an interesting target for the development of novel therapeutics requiring the understanding of the regulatory mechanisms influencing receptor mediated signaling.
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Affiliation(s)
- Lizzy Wanka
- Institute of Biochemistry, Faculty of Life Sciences, Leipzig University, Brüderstr. 34, D-04103Leipzig, Germany
| | - Victoria Behr
- Institute of Biochemistry, Faculty of Life Sciences, Leipzig University, Brüderstr. 34, D-04103Leipzig, Germany
| | - Annette G Beck-Sickinger
- Institute of Biochemistry, Faculty of Life Sciences, Leipzig University, Brüderstr. 34, D-04103Leipzig, Germany
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Laitakari A, Liu L, Frimurer TM, Holst B. The Zinc-Sensing Receptor GPR39 in Physiology and as a Pharmacological Target. Int J Mol Sci 2021; 22:ijms22083872. [PMID: 33918078 PMCID: PMC8070507 DOI: 10.3390/ijms22083872] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 03/31/2021] [Accepted: 04/06/2021] [Indexed: 12/16/2022] Open
Abstract
The G-protein coupled receptor GPR39 is abundantly expressed in various tissues and can be activated by changes in extracellular Zn2+ in physiological concentrations. Previously, genetically modified rodent models have been able to shed some light on the physiological functions of GPR39, and more recently the utilization of novel synthetic agonists has led to the unraveling of several new functions in the variety of tissues GPR39 is expressed. Indeed, GPR39 seems to be involved in many important metabolic and endocrine functions, but also to play a part in inflammation, cardiovascular diseases, saliva secretion, bone formation, male fertility, addictive and depression disorders and cancer. These new discoveries offer opportunities for the development of novel therapeutic approaches against many diseases where efficient therapeutics are still lacking. This review focuses on Zn2+ as an endogenous ligand as well as on the novel synthetic agonists of GPR39, placing special emphasis on the recently discovered physiological functions and discusses their pharmacological potential.
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Affiliation(s)
- Anna Laitakari
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark; (A.L.); (L.L.); (T.M.F.)
| | - Lingzhi Liu
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark; (A.L.); (L.L.); (T.M.F.)
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
| | - Thomas M. Frimurer
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark; (A.L.); (L.L.); (T.M.F.)
| | - Birgitte Holst
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark; (A.L.); (L.L.); (T.M.F.)
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
- Correspondence:
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Ribeiro LF, Catarino T, Carvalho M, Cortes L, Santos SD, Opazo PO, Ribeiro LR, Oliveiros B, Choquet D, Esteban JA, Peça J, Carvalho AL. Ligand-independent activity of the ghrelin receptor modulates AMPA receptor trafficking and supports memory formation. Sci Signal 2021; 14:14/670/eabb1953. [PMID: 33593997 DOI: 10.1126/scisignal.abb1953] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The biological signals of hunger, satiety, and memory are interconnected. The role of the hormone ghrelin in regulating feeding and memory makes ghrelin receptors attractive targets for associated disorders. We investigated the effects of the high ligand-independent activity of the ghrelin receptor GHS-R1a on the physiology of excitatory synapses in the hippocampus. Blocking this activity produced a decrease in the synaptic content of AMPA receptors in hippocampal neurons and a reduction in GluA1 phosphorylation at Ser845 Reducing the ligand-independent activity of GHS-R1a increased the surface diffusion of AMPA receptors and impaired AMPA receptor-dependent synaptic delivery induced by chemical long-term potentiation. Accordingly, we found that blocking this GHS-R1a activity impaired spatial and recognition memory in mice. These observations support a role for the ligand-independent activity of GHS-R1a in regulating AMPA receptor trafficking under basal conditions and in the context of synaptic plasticity that underlies learning.
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Affiliation(s)
- Luís F Ribeiro
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal.
| | - Tatiana Catarino
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal.,University of Coimbra, IIIUC-Institute for Interdisciplinary Research, 3030-789 Coimbra, Portugal
| | - Mário Carvalho
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal.,MIT-Portugal Bioengineering Systems Doctoral Program, NOVA University of Lisbon, 1099-85, Lisboa, Portugal
| | - Luísa Cortes
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal.,University of Coimbra, IIIUC-Institute for Interdisciplinary Research, 3030-789 Coimbra, Portugal
| | - Sandra D Santos
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal.,University of Coimbra, IIIUC-Institute for Interdisciplinary Research, 3030-789 Coimbra, Portugal
| | - Patricio O Opazo
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, 33000 Bordeaux, France.,CNRS, UMR 5297, 33000 Bordeaux, France
| | - Lyn Rosenbrier Ribeiro
- Functional and Mechanistic Safety, Clinical Pharmacology and Safety Sciences, R&D AstraZeneca, Cambridge CB2 0SL, UK
| | - Bárbara Oliveiros
- Laboratory of Biostatistics and Medical Informatics (LBIM), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal.,Coimbra Institute for Clinical and Biomedical Research (iCBR), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal
| | - Daniel Choquet
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, 33000 Bordeaux, France.,CNRS, UMR 5297, 33000 Bordeaux, France.,Bordeaux Imaging Center, UMS 3420, CNRS-Bordeaux University, US4 INSERM, 33000 Bordeaux, France
| | - José A Esteban
- Department of Molecular Neurobiology, Centro de Biología Molecular "Severo Ochoa," Consejo Superior de Investigaciones Científicas (CSIC)/Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - João Peça
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal.,University of Coimbra, Department of Life Sciences, 3000-456 Coimbra, Portugal
| | - Ana Luísa Carvalho
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal. .,University of Coimbra, Department of Life Sciences, 3000-456 Coimbra, Portugal
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Cornejo MP, Mustafá ER, Cassano D, Banères JL, Raingo J, Perello M. The ups and downs of growth hormone secretagogue receptor signaling. FEBS J 2021; 288:7213-7229. [PMID: 33460513 DOI: 10.1111/febs.15718] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 01/05/2021] [Accepted: 01/14/2021] [Indexed: 12/14/2022]
Abstract
The growth hormone secretagogue receptor (GHSR) has emerged as one of the most fascinating molecules from the perspective of neuroendocrine control. GHSR is mainly expressed in the pituitary and the brain, and plays key roles regulating not only growth hormone secretion but also food intake, adiposity, body weight, glucose homeostasis and other complex functions. Quite atypically, GHSR signaling displays a basal constitutive activity that can be up- or downregulated by two digestive system-derived hormones: the octanoylated-peptide ghrelin and the liver-expressed antimicrobial peptide 2 (LEAP2), which was recently recognized as an endogenous GHSR ligand. The existence of two ligands with contrary actions indicates that GHSR activity can be tightly regulated and that the receptor displays the capability to integrate such opposing inputs in order to provide a balanced intracellular signal. This article provides a summary of the current understanding of the biology of ghrelin, LEAP2 and GHSR and discusses the reconceptualization of the cellular and physiological implications of the ligand-regulated GHSR signaling, based on the latest findings.
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Affiliation(s)
- María P Cornejo
- Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET), Scientific Research Commission, Province of Buenos Aires (CIC-PBA), National University of La Plata], Buenos Aires, Argentina
| | - Emilio R Mustafá
- Laboratory of Electrophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET), Scientific Research Commission, Province of Buenos Aires (CIC-PBA), National University of La Plata], Buenos Aires, Argentina
| | - Daniela Cassano
- Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET), Scientific Research Commission, Province of Buenos Aires (CIC-PBA), National University of La Plata], Buenos Aires, Argentina
| | - Jean-Louis Banères
- Institut des Biomolécules Max Mousseron (IBMM), UMR 5247, CNRS, Université de Montpellier, Ecole Nationale Supérieure de Chimie de Montpellier, Faculté de Pharmacie, Montpellier cedex 5, France
| | - Jesica Raingo
- Laboratory of Electrophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET), Scientific Research Commission, Province of Buenos Aires (CIC-PBA), National University of La Plata], Buenos Aires, Argentina
| | - Mario Perello
- Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET), Scientific Research Commission, Province of Buenos Aires (CIC-PBA), National University of La Plata], Buenos Aires, Argentina
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13
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Khelifa MS, Skov LJ, Holst B. Biased Ghrelin Receptor Signaling and the Dopaminergic System as Potential Targets for Metabolic and Psychological Symptoms of Anorexia Nervosa. Front Endocrinol (Lausanne) 2021; 12:734547. [PMID: 34646236 PMCID: PMC8503187 DOI: 10.3389/fendo.2021.734547] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 08/16/2021] [Indexed: 12/15/2022] Open
Abstract
Anorexia Nervosa (AN) is a complex disease that impairs the metabolic, mental and physiological health of affected individuals in a severe and sometimes lethal way. Many of the common symptoms in AN patients, such as reduced food intake, anxiety, impaired gut motility or overexercising are connected to both the orexigenic gut hormone ghrelin and the dopaminergic system. Targeting the ghrelin receptor (GhrR) to treat AN seems a promising possibility in current research. However, GhrR signaling is highly complex. First, the GhrR can activate four known intracellular pathways Gαq, Gαi/o, Gα12/13 and the recruitment of β-arrestin. Biased signaling provides the possibility to activate or inhibit only one or a subset of the intracellular pathways of a pleiotropic receptor. This allows specific targeting of physiological functions without adverse effects. Currently little is known on how biased signaling could specifically modulate GhrR effects. Second, GhrR signaling has been shown to be interconnected with the dopaminergic system, particularly in the context of AN symptoms. This review highlights that a biased agonist for the GhrR may be a promising target for the treatment of AN, however extensive and systematic translational studies are still needed and the connection to the dopaminergic system has to be taken into account.
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14
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Liang Y, Yin W, Yin Y, Zhang W. Ghrelin Based Therapy of Metabolic Diseases. Curr Med Chem 2021; 28:2565-2576. [PMID: 32538716 PMCID: PMC11213490 DOI: 10.2174/0929867327666200615152804] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 05/04/2020] [Accepted: 05/18/2020] [Indexed: 11/22/2022]
Abstract
BACKGROUND Ghrelin, a unique 28 amino acid peptide hormone secreted by the gastric X/A like cells, is an endogenous ligand of the growth hormone secretagogue receptor (GHSR). Ghrelin-GHSR signaling has been found to exert various physiological functions, including stimulation of appetite, regulation of body weight, lipid and glucose metabolism, and increase of gut motility and secretion. This system is thus critical for energy homeostasis. OBJECTIVE The objective of this review is to highlight the strategies of ghrelin-GHSR based intervention for therapy of obesity and its related metabolic diseases. RESULTS Therapeutic strategies of metabolic disorders targeting the ghrelin-GHSR pathway involve neutralization of circulating ghrelin by antibodies and RNA spiegelmers, antagonism of ghrelin receptor by its antagonists and inverse agonists, inhibition of ghrelin O-acyltransferase (GOAT), as well as potential pharmacological approach to decrease ghrelin synthesis and secretion. CONCLUSION Various compounds targeting the ghrelin-GHSR system have shown promising efficacy for the intervention of obesity and relevant metabolic disorders in animals and in vitro. Further clinical trials to validate their efficacy in human beings are urgently needed.
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Affiliation(s)
- Yuan Liang
- Key Laboratory of Molecular Cardiovascular Science, Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Wenzhen Yin
- Key Laboratory of Molecular Cardiovascular Science, Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Yue Yin
- Key Laboratory of Molecular Cardiovascular Science, Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Weizhen Zhang
- Key Laboratory of Molecular Cardiovascular Science, Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China
- Department of Surgery, University of Michigan Medical Center, Ann Arbor, MI 48109-0346, USA
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15
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Cornejo MP, Mustafá ER, Barrile F, Cassano D, De Francesco PN, Raingo J, Perello M. THE INTRIGUING LIGAND-DEPENDENT AND LIGAND-INDEPENDENT ACTIONS OF THE GROWTH HORMONE SECRETAGOGUE RECEPTOR ON REWARD-RELATED BEHAVIORS. Neurosci Biobehav Rev 2020; 120:401-416. [PMID: 33157147 DOI: 10.1016/j.neubiorev.2020.10.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 10/18/2020] [Accepted: 10/20/2020] [Indexed: 02/07/2023]
Abstract
The growth hormone secretagogue receptor (GHSR) is a G-protein-coupled receptor (GPCR) highly expressed in the brain, and also in some peripheral tissues. GHSR activity is evoked by the stomach-derived peptide hormone ghrelin and abrogated by the intestine-derived liver-expressed antimicrobial peptide 2 (LEAP2). In vitro, GHSR displays ligand-independent actions, including a high constitutive activity and an allosteric modulation of other GPCRs. Beyond its neuroendocrine and metabolic effects, cumulative evidence shows that GHSR regulates the activity of the mesocorticolimbic pathway and modulates complex reward-related behaviors towards different stimuli. Here, we review current evidence indicating that ligand-dependent and ligand-independent actions of GHSR enhance reward-related behaviors towards appetitive stimuli and drugs of abuse. We discuss putative neuronal networks and molecular mechanisms that GHSR would engage to modulate such reward-related behaviors. Finally, we briefly discuss imaging studies showing that ghrelin would also regulate reward processing in humans. Overall, we conclude that GHSR is a key regulator of the mesocorticolimbic pathway that influences its activity and, consequently, modulates reward-related behaviors via ligand-dependent and ligand-independent actions.
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Affiliation(s)
- María P Cornejo
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA). National University of La Plata], 1900 La Plata, Buenos Aires, Argentina
| | - Emilio R Mustafá
- Laboratory of Electrophysiology of the IMBICE, 1900 La Plata, Buenos Aires, Argentina
| | - Franco Barrile
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA). National University of La Plata], 1900 La Plata, Buenos Aires, Argentina
| | - Daniela Cassano
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA). National University of La Plata], 1900 La Plata, Buenos Aires, Argentina
| | - Pablo N De Francesco
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA). National University of La Plata], 1900 La Plata, Buenos Aires, Argentina
| | - Jesica Raingo
- Laboratory of Electrophysiology of the IMBICE, 1900 La Plata, Buenos Aires, Argentina
| | - Mario Perello
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA). National University of La Plata], 1900 La Plata, Buenos Aires, Argentina.
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16
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Worm DJ, Els‐Heindl S, Beck‐Sickinger AG. Targeting of peptide‐binding receptors on cancer cells with peptide‐drug conjugates. Pept Sci (Hoboken) 2020. [DOI: 10.1002/pep2.24171] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Dennis J. Worm
- Faculty of Life Sciences, Institute of BiochemistryLeipzig University Leipzig Germany
| | - Sylvia Els‐Heindl
- Faculty of Life Sciences, Institute of BiochemistryLeipzig University Leipzig Germany
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17
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Abizaid A, Hougland JL. Ghrelin Signaling: GOAT and GHS-R1a Take a LEAP in Complexity. Trends Endocrinol Metab 2020; 31:107-117. [PMID: 31636018 PMCID: PMC7299083 DOI: 10.1016/j.tem.2019.09.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 09/25/2019] [Accepted: 09/27/2019] [Indexed: 12/30/2022]
Abstract
Ghrelin and the growth hormone secretagogue receptor 1a (GHS-R1a) are important targets for disorders related to energy balance and metabolic regulation. Pharmacological control of ghrelin signaling is a promising avenue to address health issues involving appetite, weight gain, obesity, and related metabolic disorders, and may be an option for patients suffering from wasting conditions like cachexia. In this review, we summarize recent developments in the biochemistry of ghrelin and GHS-R1a signaling. These include unravelling the enzymatic transformations that generate active ghrelin and the discovery of multiple proteins that interact with ghrelin and GHS-R1a to regulate signaling. Furthermore, we propose that harnessing these processes will lead to highly selective treatments to address obesity, diabetes, and other metabolism-linked disorders.
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Affiliation(s)
- Alfonso Abizaid
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | - James L Hougland
- Department of Chemistry, Syracuse University, Syracuse, NY, USA.
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18
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Torres-Fuentes C, Golubeva AV, Zhdanov AV, Wallace S, Arboleya S, Papkovsky DB, El Aidy S, Ross P, Roy BL, Stanton C, Dinan TG, Cryan JF, Schellekens H. Short-chain fatty acids and microbiota metabolites attenuate ghrelin receptor signaling. FASEB J 2019; 33:13546-13559. [DOI: 10.1096/fj.201901433r] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Cristina Torres-Fuentes
- Alimentary Pharmabiotic Centre (APC) Microbiome Ireland, University College Cork, Cork, Ireland
| | - Anna V. Golubeva
- Alimentary Pharmabiotic Centre (APC) Microbiome Ireland, University College Cork, Cork, Ireland
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | | | - Shauna Wallace
- Alimentary Pharmabiotic Centre (APC) Microbiome Ireland, University College Cork, Cork, Ireland
| | - Silvia Arboleya
- Alimentary Pharmabiotic Centre (APC) Microbiome Ireland, University College Cork, Cork, Ireland
- Teagasc Food Research Centre, Cork, Ireland
| | | | - Sahar El Aidy
- Alimentary Pharmabiotic Centre (APC) Microbiome Ireland, University College Cork, Cork, Ireland
| | - Paul Ross
- Alimentary Pharmabiotic Centre (APC) Microbiome Ireland, University College Cork, Cork, Ireland
| | | | - Catherine Stanton
- Alimentary Pharmabiotic Centre (APC) Microbiome Ireland, University College Cork, Cork, Ireland
- Teagasc Food Research Centre, Cork, Ireland
| | - Timothy G. Dinan
- Alimentary Pharmabiotic Centre (APC) Microbiome Ireland, University College Cork, Cork, Ireland
- Department of Psychiatry and Neurobehavioral Science, University College Cork, Cork, Ireland
| | - John F. Cryan
- Alimentary Pharmabiotic Centre (APC) Microbiome Ireland, University College Cork, Cork, Ireland
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Harriet Schellekens
- Alimentary Pharmabiotic Centre (APC) Microbiome Ireland, University College Cork, Cork, Ireland
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
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19
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Barrile F, M'Kadmi C, De Francesco PN, Cabral A, García Romero G, Mustafá ER, Cantel S, Damian M, Mary S, Denoyelle S, Banères JL, Marie J, Raingo J, Fehrentz JA, Perelló M. Development of a novel fluorescent ligand of growth hormone secretagogue receptor based on the N-Terminal Leap2 region. Mol Cell Endocrinol 2019; 498:110573. [PMID: 31499133 DOI: 10.1016/j.mce.2019.110573] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 08/27/2019] [Accepted: 09/03/2019] [Indexed: 01/13/2023]
Abstract
Liver-expressed antimicrobial peptide 2 (LEAP2) was recently recognized as an endogenous ligand for the growth hormone secretagogue receptor (GHSR), which also is a receptor for the hormone ghrelin. LEAP2 blocks ghrelin-induced activation of GHSR and inhibits GHSR constitutive activity. Since fluorescence-based imaging and pharmacological analyses to investigate the biology of GHSR require reliable probes, we developed a novel fluorescent GHSR ligand based on the N-terminal LEAP2 sequence, hereafter named F-LEAP2. In vitro, F-LEAP2 displayed binding affinity and inverse agonism to GHSR similar to LEAP2. In a heterologous expression system, F-LEAP2 labeling was specifically observed in the surface of GHSR-expressing cells, in contrast to fluorescent ghrelin labeling that was mainly observed inside the GHSR-expressing cells. In mice, centrally-injected F-LEAP2 reduced ghrelin-induced food intake, in a similar fashion to LEAP2, and specifically labeled cells in GHSR-expressing brain areas. Thus, F-LEAP2 represents a valuable tool to study the biology of GHSR in vitro and in vivo.
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Affiliation(s)
- Franco Barrile
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA), National University of La Plata], 1900, La Plata, Buenos Aires, Argentina
| | - Céline M'Kadmi
- Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 34093, Montpellier, France
| | - Pablo N De Francesco
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA), National University of La Plata], 1900, La Plata, Buenos Aires, Argentina
| | - Agustina Cabral
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA), National University of La Plata], 1900, La Plata, Buenos Aires, Argentina
| | - Guadalupe García Romero
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA), National University of La Plata], 1900, La Plata, Buenos Aires, Argentina
| | - Emilio R Mustafá
- Laboratory of Electrophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA), National University of La Plata], 1900, La Plata, Buenos Aires, Argentina
| | - Sonia Cantel
- Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 34093, Montpellier, France
| | - Marjorie Damian
- Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 34093, Montpellier, France
| | - Sophie Mary
- Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 34093, Montpellier, France
| | - Séverine Denoyelle
- Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 34093, Montpellier, France
| | - Jean-Louis Banères
- Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 34093, Montpellier, France
| | - Jacky Marie
- Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 34093, Montpellier, France
| | - Jesica Raingo
- Laboratory of Electrophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA), National University of La Plata], 1900, La Plata, Buenos Aires, Argentina
| | - Jean-Alain Fehrentz
- Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 34093, Montpellier, France.
| | - Mario Perelló
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA), National University of La Plata], 1900, La Plata, Buenos Aires, Argentina.
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20
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Buckinx A, Van Den Herrewegen Y, Pierre A, Cottone E, Ben Haj Salah K, Fehrentz JA, Kooijman R, De Bundel D, Smolders I. Differential Effects of a Full and Biased Ghrelin Receptor Agonist in a Mouse Kindling Model. Int J Mol Sci 2019; 20:ijms20102480. [PMID: 31137460 PMCID: PMC6567032 DOI: 10.3390/ijms20102480] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 05/15/2019] [Accepted: 05/15/2019] [Indexed: 12/23/2022] Open
Abstract
The ghrelin system has received substantial recognition as a potential target for novel anti-seizure drugs. Ghrelin receptor (ghrelin-R) signaling is complex, involving Gαq/11, Gαi/o, Gα12/13, and β-arrestin pathways. In this study, we aimed to deepen our understanding regarding signaling pathways downstream the ghrelin-R responsible for mediating anticonvulsive effects in a kindling model. Mice were administered the proconvulsive dopamine 1 receptor-agonist, SKF81297, to gradually induce a kindled state. Prior to every SKF81297 injection, mice were treated with a ghrelin-R full agonist (JMV-1843), a Gαq and Gα12 biased ligand unable to recruit β-arrestin (YIL781), a ghrelin-R antagonist (JMV-2959), or saline. Mice treated with JMV-1843 had fewer and less severe seizures compared to saline-treated controls, while mice treated with YIL781 experienced longer and more severe seizures. JMV-2959 treatment did not lead to differences in seizure severity and number. Altogether, these results indicate that the Gαq or Gα12 signaling pathways are not responsible for mediating JMV-1843′s anticonvulsive effects and suggest a possible involvement of β-arrestin signaling in the anticonvulsive effects mediated by ghrelin-R modulation.
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Affiliation(s)
- An Buckinx
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090 Brussels, Belgium.
| | - Yana Van Den Herrewegen
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090 Brussels, Belgium.
| | - Anouk Pierre
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090 Brussels, Belgium.
| | - Eleonora Cottone
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090 Brussels, Belgium.
| | - Khoubaib Ben Haj Salah
- Max Mousseron Institute of Biomolecules UMR524, CNRS, University of Montpellier, Ecole Nationale Supérieure de Chimie de Montpellier, 34090 Montpellier, France.
| | - Jean-Alain Fehrentz
- Max Mousseron Institute of Biomolecules UMR524, CNRS, University of Montpellier, Ecole Nationale Supérieure de Chimie de Montpellier, 34090 Montpellier, France.
| | - Ron Kooijman
- Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), 1050 Brussels, Belgium.
| | - Dimitri De Bundel
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090 Brussels, Belgium.
| | - Ilse Smolders
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090 Brussels, Belgium.
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21
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Ramirez VT, van Oeffelen WEPA, Torres-Fuentes C, Chruścicka B, Druelle C, Golubeva AV, van de Wouw M, Dinan TG, Cryan JF, Schellekens H. Differential functional selectivity and downstream signaling bias of ghrelin receptor antagonists and inverse agonists. FASEB J 2018; 33:518-531. [PMID: 30020830 DOI: 10.1096/fj.201800655r] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The ghrelin receptor [growth hormone secretagogue receptor (GHSR)-1a] represents a promising pharmacologic target for the treatment of metabolic disorders, including obesity and cachexia, via central appetite modulation. The GHSR-1a has a complex pharmacology, highlighted by G-protein-dependent and -independent downstream signaling pathways and high basal constitutive activity. The functional selectivity and signaling bias of many GHSR-1a-specific ligands has not been fully characterized. In this study, we investigated the pharmacologic properties of ghrelin, MK-0677, L692,585, and [d-Lys3]-growth hormone-releasing peptide-6 (Dlys), JMV2959, and [d-Arg(1),d-Phe(5),d-Trp(7, 9),Leu(11)]-substance P (SP-analog). We investigated their effect on basal GHSR-1a constitutive signaling, ligand-directed downstream GHSR-1a signaling, functional selectivity, and signaling bias. Dlys behaved as a partial antagonist with a strong bias toward GHSR-1a-β-arrestin signaling, whereas JMV2959 acted as a full unbiased GHSR-1a antagonist. Moreover, the SP-analog behaved as an inverse agonist increasing G-protein-dependent signaling, but only at high concentrations, whereas, at low concentrations, the SP-analog attenuated β-arrestin-dependent signaling. Considering the limited success in the clinical development of GHSR-1a-targeted drugs so far, these findings provide a novel insight into the pharmacologic characteristics of GHSR-1a ligands and their signaling bias, which has important implications in the design of novel, more selective GHSR-1a ligands with predictable functional outcome and selectivity for preclinical and clinical drug development.-Ramirez, V. T., van Oeffelen, W. E. P. A., Torres-Fuentes, C., Chruścicka, B., Druelle, C., Golubeva, A. V., van de Wouw, M., Dinan, T. G., Cryan, J. F., Schellekens, H. Differential functional selectivity and downstream signaling bias of ghrelin receptor antagonists and inverse agonists.
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Affiliation(s)
- Valerie T Ramirez
- Alimentary Pharmabiotic Centre (APC) Microbiome Ireland, University College Cork, Cork, Ireland
| | | | - Cristina Torres-Fuentes
- Alimentary Pharmabiotic Centre (APC) Microbiome Ireland, University College Cork, Cork, Ireland
| | - Barbara Chruścicka
- Alimentary Pharmabiotic Centre (APC) Microbiome Ireland, University College Cork, Cork, Ireland
| | - Clementine Druelle
- Alimentary Pharmabiotic Centre (APC) Microbiome Ireland, University College Cork, Cork, Ireland
| | - Anna V Golubeva
- Alimentary Pharmabiotic Centre (APC) Microbiome Ireland, University College Cork, Cork, Ireland
| | - Marcel van de Wouw
- Alimentary Pharmabiotic Centre (APC) Microbiome Ireland, University College Cork, Cork, Ireland.,Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Timothy G Dinan
- Alimentary Pharmabiotic Centre (APC) Microbiome Ireland, University College Cork, Cork, Ireland.,Department of Psychiatry, University College Cork, Cork, Ireland; and
| | - John F Cryan
- Alimentary Pharmabiotic Centre (APC) Microbiome Ireland, University College Cork, Cork, Ireland.,Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland.,Food for Health Ireland, University College Cork, Cork, Ireland
| | - Harriët Schellekens
- Alimentary Pharmabiotic Centre (APC) Microbiome Ireland, University College Cork, Cork, Ireland.,Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland.,Food for Health Ireland, University College Cork, Cork, Ireland
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22
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Abstract
Ghrelin, a gastric-derived acylated peptide, regulates energy homeostasis by transmitting information about peripheral nutritional status to the brain, and is essential for protecting organisms against famine. Ghrelin operates brain circuits to regulate homeostatic and hedonic feeding. Recent research advances have shed new light on ghrelin's multifaceted roles in cellular homeostasis, which could maintain the internal environment and overcome metaflammation in metabolic organs. Here, we highlight our current understanding of the regulatory mechanisms of the ghrelin system in energy metabolism and cellular homeostasis and its clinical trials. Future studies of ghrelin will further elucidate how the stomach regulates systemic homeostasis.
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Affiliation(s)
- Shigehisa Yanagi
- Divisions of Neurology, Respirology, Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Kiyotake, Miyazaki 889-1692, Japan
| | - Takahiro Sato
- Molecular Genetics, Institute of Life Science, Kurume University, Kurume 839-0864, Japan
| | - Kenji Kangawa
- Department of Biochemistry, National Cerebral and Cardiovascular Center Research Institute, Suita, Osaka 565-8565, Japan
| | - Masamitsu Nakazato
- Divisions of Neurology, Respirology, Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Kiyotake, Miyazaki 889-1692, Japan; AMED-CREST, Japan Agency for Medical Research and Development, Chiyoda-ku, Tokyo 100-0004, Japan.
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23
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Shimizu Y, Koyama R, Kawamoto T. Rho kinase-dependent desensitization of GPR39; a unique mechanism of GPCR downregulation. Biochem Pharmacol 2017; 140:105-114. [PMID: 28619258 DOI: 10.1016/j.bcp.2017.06.115] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 06/09/2017] [Indexed: 12/14/2022]
Abstract
GPR39, a G-protein-coupled receptor activated by zinc, reportedly activates multiple intracellular signaling pathways via Gs, Gq, G12/13, and β-arrestin, but little is known about downregulation of the receptor upon its activation. To our knowledge, this is the first report on the mechanism of feedback regulation of GPR39 function determined in GPR39-expressing HEK293 cells (HEK293-GPR39) as a model cell system. In HEK293-GPR39 cells, GPR39-C3, which is a positive allosteric modulator, activated cAMP production (downstream of Gs), IP1 accumulation (downstream of Gq), SRF-RE-dependent transcription (downstream of G12/13), and β-arrestin recruitment. GPR39-C3 induced dose- and time-dependent loss of response in cAMP production by second challenge of the compound. This functional desensitization was blocked by the Rho kinase (ROCK) inhibitor, Y-27632, but not by Gq or Gs-pathway inhibitors or inhibition of β-arrestin recruitment. In the receptor localization assay, GPR39-C3 induced internalization of GFP-tagged GPR39. This internalization was also inhibited by Y-27632, which suggested that ROCK activation is critical for internalization and desensitization of GPR39. A novel biased GPR39 positive allosteric modulator, 5-[2-[(2,4-dichlorophenyl)methoxy]phenyl]-2,2-dimethyl-1,3,5,6-tetrahydrobenzo[a]phenanthridin-4-one (GSB-118), which activated cAMP responses and β-arrestin recruitment but showed no effect on SRF-RE-dependent transcription, did not induce desensitization. These results revealed a unique mechanism of desensitization of GPR39.
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Affiliation(s)
- Yuji Shimizu
- Biomolecular Research Laboratories, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-higashi 2-chome, Fujisawa, Kanagawa 251-8555, Japan.
| | - Ryokichi Koyama
- Biomolecular Research Laboratories, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-higashi 2-chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Tomohiro Kawamoto
- Biomolecular Research Laboratories, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-higashi 2-chome, Fujisawa, Kanagawa 251-8555, Japan
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24
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Obestatin controls skeletal muscle fiber-type determination. Sci Rep 2017; 7:2137. [PMID: 28522824 PMCID: PMC5437042 DOI: 10.1038/s41598-017-02337-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 04/11/2017] [Indexed: 01/27/2023] Open
Abstract
Obestatin/GPR39 signaling stimulates skeletal muscle growth and repair by inducing both G-protein-dependent and -independent mechanisms linking the activated GPR39 receptor with distinct sets of accessory and effector proteins. In this work, we describe a new level of activity where obestatin signaling plays a role in the formation, contractile properties and metabolic profile of skeletal muscle through determination of oxidative fiber type. Our data indicate that obestatin regulates Mef2 activity and PGC-1α expression. Both mechanisms result in a shift in muscle metabolism and function. The increase in Mef2 and PGC-1α signaling activates oxidative capacity, whereas Akt/mTOR signaling positively regulates myofiber growth. Taken together, these data indicate that the obestatin signaling acts on muscle fiber-type program in skeletal muscle.
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25
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C-terminal motif of human neuropeptide Y 4 receptor determines internalization and arrestin recruitment. Cell Signal 2016; 29:233-239. [PMID: 27818291 DOI: 10.1016/j.cellsig.2016.11.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Revised: 10/27/2016] [Accepted: 11/01/2016] [Indexed: 12/31/2022]
Abstract
The human neuropeptide Y4 receptor is a rhodopsin-like G protein-coupled receptor (GPCR), which contributes to anorexigenic signals. Thus, this receptor is a highly interesting target for metabolic diseases. As GPCR internalization and trafficking affect receptor signaling and vice versa, we aimed to investigate the molecular mechanism of hY4R desensitization and endocytosis. The role of distinct segments of the hY4R carboxyl terminus was investigated by fluorescence microscopy, binding assays, inositol turnover experiments and bioluminescence resonance energy transfer assays to examine the internalization behavior of hY4R and its interaction with arrestin-3. Based on results of C-terminal deletion mutants and substitution of single amino acids, the motif 7.78EESEHLPLSTVHTEVSKGS7.96 was identified, with glutamate, threonine and serine residues playing key roles, based on site-directed mutagenesis. Thus, we identified the internalization motif for the human neuropeptide Y4 receptor, which regulates arrestin-3 recruitment and receptor endocytosis.
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26
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Aydemir TB, Troche C, Kim MH, Cousins RJ. Hepatic ZIP14-mediated Zinc Transport Contributes to Endosomal Insulin Receptor Trafficking and Glucose Metabolism. J Biol Chem 2016; 291:23939-23951. [PMID: 27703010 DOI: 10.1074/jbc.m116.748632] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 09/12/2016] [Indexed: 12/12/2022] Open
Abstract
Zinc influences signaling pathways through controlled targeted zinc transport. Zinc transporter Zip14 KO mice display a phenotype that includes impaired intestinal barrier function with low grade chronic inflammation, hyperinsulinemia, and increased body fat, which are signatures of diet-induced diabetes (type 2 diabetes) and obesity in humans. Hyperglycemia in type 2 diabetes and obesity is caused by insulin resistance. Insulin resistance results in inhibition of glucose uptake by liver and other peripheral tissues, principally adipose and muscle and with concurrently higher hepatic glucose production. Therefore, modulation of hepatic glucose metabolism is an important target for antidiabetic treatment approaches. We demonstrate that during glucose uptake, cell surface abundance of zinc transporter ZIP14 and mediated zinc transport increases. Zinc is distributed to multiple sites in hepatocytes through sequential translocation of ZIP14 from plasma membrane to early and late endosomes. Endosomes from Zip14 KO mice were zinc-deficient because activities of the zinc-dependent insulin-degrading proteases insulin-degrading enzyme and cathepsin D were impaired; hence insulin receptor activity increased. Transient increases in cytosolic zinc levels are concurrent with glucose uptake and suppression of glycogen synthesis. In contrast, Zip14 KO mice exhibited greater hepatic glycogen synthesis and impaired gluconeogenesis and glycolysis related to low cytosolic zinc levels. We can conclude that ZIP14-mediated zinc transport contributes to regulation of endosomal insulin receptor activity and glucose homeostasis in hepatocytes. Therefore, modulation of ZIP14 transport activity presents a new target for management of diabetes and other glucose-related disorders.
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Affiliation(s)
- Tolunay Beker Aydemir
- From the Food Science and Human Nutrition Department and Center for Nutritional Sciences College of Agricultural and Life Sciences and
| | - Catalina Troche
- From the Food Science and Human Nutrition Department and Center for Nutritional Sciences College of Agricultural and Life Sciences and
| | - Min-Hyun Kim
- From the Food Science and Human Nutrition Department and Center for Nutritional Sciences College of Agricultural and Life Sciences and
| | - Robert J Cousins
- From the Food Science and Human Nutrition Department and Center for Nutritional Sciences College of Agricultural and Life Sciences and .,the Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, Florida 32611
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27
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Smith RG. Dissociating ghrelin-dependent G protein from β-arrestin-2 signaling in transgenic rats. Sci Signal 2016; 9:fs6. [PMID: 27095592 DOI: 10.1126/scisignal.aaf7292] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The gut-derived hormone ghrelin regulates growth hormone release, appetite, metabolism, and immune function through its receptor, the growth hormone secretagogue receptor 1a (GHSR1a). In this issue of Science Signaling, Chebani et al decode GHSR1a signaling by using transgenic rats with a mutation in GHSR1a that prevents its interaction with β-arrestin. These mutant rats are more responsive to endogenous ghrelin, resulting in increased fat deposition and insulin resistance without affecting food intake.
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Affiliation(s)
- Roy G Smith
- Department of Metabolism and Aging, Scripps Research Institute-Florida, 130 Scripps Way, #3B3, Jupiter, FL 33458, USA.
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28
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Chebani Y, Marion C, Zizzari P, Chettab K, Pastor M, Korostelev M, Geny D, Epelbaum J, Tolle V, Morisset-Lopez S, Pantel J. Enhanced responsiveness of Ghsr Q343X rats to ghrelin results in enhanced adiposity without increased appetite. Sci Signal 2016; 9:ra39. [PMID: 27095593 DOI: 10.1126/scisignal.aae0374] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The ability of the gut hormone ghrelin to promote positive energy balance is mediated by the growth hormone secretagogue receptor (GHSR). GHSR is a G protein-coupled receptor (GPCR) that is found centrally and peripherally and that can signal in a ligand-independent manner basally or when heterodimerized with other GPCRs. However, current Ghsr knockout models cannot dissect ghrelin-dependent and ghrelin-independent signaling, precluding assessment of the physiological importance of these signaling pathways. An animal model carrying a Ghsr mutation that preserves GHSR cell surface abundance, but selectively alters GHSR signaling, would be a useful tool to decipher GHSR signaling in vivo. We used rats with the Ghsr(Q343X) mutation (Ghsr(M/M)), which is predicted to delete the distal part of the GHSR carboxyl-terminal tail, a domain critical for the signal termination processes of receptor internalization and β-arrestin recruitment. In cells, the GHSR-Q343X mutant showed enhanced ligand-induced G protein-dependent signaling and blunted activity of processes involved in GPCR signal termination. Ghsr(M/M)rats displayed enhanced responses to submaximal doses of ghrelin or GHSR agonist. Moreover, Ghsr(M/M)rats had a more stable body weight under caloric restriction, a condition that increases endogenous ghrelin tone, whereas under standard housing conditions,Ghsr(M/M)rats showed increased body weight and adiposity and reduced glucose tolerance. Overall, our data stress the physiological role of the distal domain of GHSR carboxyl terminus as a suppressor of ghrelin sensitivity, and we propose using the Ghsr(M/M)rat as a physiological model of gain of function in Ghsr to identify treatments for obesity-related conditions.
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Affiliation(s)
- Yacine Chebani
- INSERM, Université Paris Descartes, Sorbonne Paris Cité, UMR-S 894, Centre de Psychiatrie & Neurosciences, 75014 Paris, France
| | - Candice Marion
- INSERM, Université Paris Descartes, Sorbonne Paris Cité, UMR-S 894, Centre de Psychiatrie & Neurosciences, 75014 Paris, France
| | - Philippe Zizzari
- INSERM, Université Paris Descartes, Sorbonne Paris Cité, UMR-S 894, Centre de Psychiatrie & Neurosciences, 75014 Paris, France
| | - Khadidja Chettab
- INSERM, Université Paris Descartes, Sorbonne Paris Cité, UMR-S 894, Centre de Psychiatrie & Neurosciences, 75014 Paris, France
| | - Marie Pastor
- INSERM, Université Paris Descartes, Sorbonne Paris Cité, UMR-S 894, Centre de Psychiatrie & Neurosciences, 75014 Paris, France
| | - Marie Korostelev
- INSERM, Université Paris Descartes, Sorbonne Paris Cité, UMR-S 894, Centre de Psychiatrie & Neurosciences, 75014 Paris, France
| | - David Geny
- INSERM, Université Paris Descartes, Sorbonne Paris Cité, UMR-S 894, Centre de Psychiatrie & Neurosciences, 75014 Paris, France
| | - Jacques Epelbaum
- INSERM, Université Paris Descartes, Sorbonne Paris Cité, UMR-S 894, Centre de Psychiatrie & Neurosciences, 75014 Paris, France. CNRS, Muséum national d'Histoire naturelle, UMR 7179, Mécanismes adaptatifs et évolution, 91800 Brunoy, France
| | - Virginie Tolle
- INSERM, Université Paris Descartes, Sorbonne Paris Cité, UMR-S 894, Centre de Psychiatrie & Neurosciences, 75014 Paris, France
| | - Séverine Morisset-Lopez
- Centre de Biophysique Moléculaire, CNRS, UPR 4301, Université d'Orléans, 45071 Orléans, France
| | - Jacques Pantel
- INSERM, Université Paris Descartes, Sorbonne Paris Cité, UMR-S 894, Centre de Psychiatrie & Neurosciences, 75014 Paris, France. Department of Molecular Physiology and Biophysics, Vanderbilt School of Medicine, Nashville, TN 37232, USA
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29
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Passoni I, Leonzino M, Gigliucci V, Chini B, Busnelli M. Carbetocin is a Functional Selective Gq Agonist That Does Not Promote Oxytocin Receptor Recycling After Inducing β-Arrestin-Independent Internalisation. J Neuroendocrinol 2016; 28. [PMID: 26751410 PMCID: PMC5021139 DOI: 10.1111/jne.12363] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 12/30/2015] [Accepted: 01/07/2016] [Indexed: 01/08/2023]
Abstract
Carbetocin, a long-acting oxytocin analogue, has been reported to elicit interesting and peculiar behavioural effects. The present study investigated the molecular pharmacology of carbetocin, aiming to better understand the molecular basis of its action in the brain. Using bioluminescence resonance energy transfer biosensors, we characterised the effects of carbetocin on the three human oxytocin/vasopressin receptors expressed in the nervous system: the oxytocin receptor (OXTR) and the vasopressin V1a (V1aR) and V1b (V1bR) receptors. Our results indicate that (i) carbetocin activates the OXTR but not the V1aR and V1bR at which it may act as an antagonist; (ii) carbetocin selectively activates only the OXTR/Gq pathway displaying a strong functional selectivity; (iii) carbetocin is a partial agonist at the OXTR/Gq coupling; (iv) carbetocin promotes OXTR internalisation via a previously unreported β-arrestin-independent pathway; and (v) carbetocin does not induce OXTR recycling to the plasma membrane. Altogether, these molecular pharmacology features identify carbetocin as a substantially different analogue compared to the endogenous oxytocin and, consequently, carbetocin is not expected to mimic oxytocin in the brain. Whether these unique features of carbetocin could be exploited therapeutically remains to be established.
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Affiliation(s)
- I Passoni
- Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, Milan, Italy
| | - M Leonzino
- CNR, Institute of Neuroscience, Milan, Italy
| | - V Gigliucci
- CNR, Institute of Neuroscience, Milan, Italy
| | - B Chini
- CNR, Institute of Neuroscience, Milan, Italy
- Humanitas Clinical and Research Institute, Rozzano, Italy
| | - M Busnelli
- Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, Milan, Italy
- CNR, Institute of Neuroscience, Milan, Italy
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30
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Distinct phosphorylation sites on the ghrelin receptor, GHSR1a, establish a code that determines the functions of ß-arrestins. Sci Rep 2016; 6:22495. [PMID: 26935831 PMCID: PMC4776146 DOI: 10.1038/srep22495] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 02/15/2016] [Indexed: 01/14/2023] Open
Abstract
The growth hormone secretagogue receptor, GHSR1a, mediates the biological activities
of ghrelin, which includes the secretion of growth hormone, as well as the
stimulation of appetite, food intake and maintenance of energy homeostasis. Mapping
phosphorylation sites on GHSR1a and knowledge of how these sites control specific
functional consequences unlocks new strategies for the development of therapeutic
agents targeting individual functions. Herein, we have identified the
phosphorylation of different sets of sites within GHSR1a which engender distinct
functionality of ß-arrestins. More specifically, the
Ser362, Ser363 and Thr366 residues
at the carboxyl-terminal tail were primarily responsible for ß-arrestin
1 and 2 binding, internalization and ß-arrestin-mediated proliferation
and adipogenesis. The Thr350 and Ser349 are not
necessary for ß-arrestin recruitment, but are involved in the
stabilization of the GHSR1a-ß-arrestin complex in a manner that
determines the ultimate cellular consequences of ß-arrestin signaling.
We further demonstrated that the mitogenic and adipogenic effect of ghrelin were
mainly dependent on the ß-arrestin bound to the phosphorylated GHSR1a.
In contrast, the ghrelin function on GH secretion was entirely mediated by G protein
signaling. Our data is consistent with the hypothesis that the phosphorylation
pattern on the C terminus of GHSR1a determines the signaling and physiological
output.
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31
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Abstract
Since their discovery, G protein-coupled receptors (GPCRs) constitute one of the most studied proteins leading to important discoveries and perspectives in terms of their biology and implication in physiology and pathophysiology. This is mostly linked to the remarkable advances in the development and application of the biophysical resonance energy transfer (RET)-based approaches, including bioluminescence and fluorescence resonance energy transfer (BRET and FRET, respectively). Indeed, BRET and FRET have been extensively applied to study different aspects of GPCR functioning such as their activation and regulation either statically or dynamically, in real-time and intact cells. Consequently, our view on GPCRs has considerably changed opening new challenges for the study of GPCRs in their native tissues in the aim to get more knowledge on how these receptors control the biological responses. Moreover, the technological aspect of this field of research promises further developments for robust and reliable new RET-based assays that may be compatible with high-throughput screening as well as drug discovery programs.
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Affiliation(s)
- Mohammed Akli Ayoub
- Biologie et Bioinformatique des Systèmes de Signalisation, Institut National de la Recherche Agronomique, UMR85, Unité Physiologie de la Reproduction et des Comportements; CNRS, UMR7247, Nouzilly, France; LE STUDIUM(®) Loire Valley Institute for Advanced Studies, Orléans, France.
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32
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Muniz BG, Isokawa M. Ghrelin receptor activity amplifies hippocampal N-methyl-d-aspartate receptor-mediated postsynaptic currents and increases phosphorylation of the GluN1 subunit at Ser896 and Ser897. Eur J Neurosci 2015; 42:3045-53. [PMID: 26490687 DOI: 10.1111/ejn.13107] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 10/13/2015] [Accepted: 10/15/2015] [Indexed: 12/31/2022]
Abstract
Although ghrelin and its cognate receptor growth hormone secretagogue receptor (GHSR1a) are highly localized in the hypothalamic nuclei for the regulation of metabolic states and feeding, GHSR1a is also highly localized in the hippocampus, suggesting its involvement in extra-hypothalamic functions. Indeed, exogenous application of ghrelin has been reported to improve hippocampal learning and memory. However, the underlying mechanism of ghrelin regulation of hippocampal functions is poorly understood. Here, we report ghrelin-promoted phosphorylation of GluN1 and amplified N-methyl-d-aspartate receptor (NMDAR)-mediated excitatory postsynaptic currents in the CA1 pyramidal cells of the hippocampus in slice preparations. The ghrelin-induced responses were sensitive to a GHSR1a antagonist and inverse agonist, and were absent in GHSR1a homozygous knock-out mice. These results indicated that activation of GHSR1a was critical in the ghrelin-induced enhancement of the NMDAR function. Interestingly, heterozygous mouse hippocampi were also insensitive to ghrelin treatment, suggesting that a slight reduction in the availability of GHSR1a may be sufficient to negate the effect of ghrelin on GluN1 phosphorylation and NMDAR channel activities. In addition, NMDAR-mediated spike currents, which are of dendritic origin, were blocked by the GHSR1a antagonist, suggesting the presence of GHSR1a on the pyramidal cell dendrites in physical proximity to NMDAR. Together with our findings on the localization of GHSR1a in the CA1 region of the hippocampus, which was shown by fluorescent ghrelin binding, immunoreactivity, and enhanced green fluorescent protein reporter gene expression, we conclude that the activation of GHSR1a favours rapid modulation of the NMDAR-mediated glutamatergic synaptic transmission by phosphorylating GluN1 in the hippocampus.
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Affiliation(s)
- Brandon G Muniz
- Department of Health and Biomedical Sciences, The University of Texas Rio Grande Valley, One West University Boulevard, Brownsville, TX, 78520, USA
| | - Masako Isokawa
- Department of Health and Biomedical Sciences, The University of Texas Rio Grande Valley, One West University Boulevard, Brownsville, TX, 78520, USA
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33
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Bioorthogonal Labeling of Ghrelin Receptor to Facilitate Studies of Ligand-Dependent Conformational Dynamics. ACTA ACUST UNITED AC 2015; 22:1431-1436. [DOI: 10.1016/j.chembiol.2015.09.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 09/21/2015] [Accepted: 09/28/2015] [Indexed: 01/09/2023]
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34
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M'Kadmi C, Leyris JP, Onfroy L, Galés C, Saulière A, Gagne D, Damian M, Mary S, Maingot M, Denoyelle S, Verdié P, Fehrentz JA, Martinez J, Banères JL, Marie J. Agonism, Antagonism, and Inverse Agonism Bias at the Ghrelin Receptor Signaling. J Biol Chem 2015; 290:27021-27039. [PMID: 26363071 DOI: 10.1074/jbc.m115.659250] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Indexed: 01/14/2023] Open
Abstract
The G protein-coupled receptor GHS-R1a mediates ghrelin-induced growth hormone secretion, food intake, and reward-seeking behaviors. GHS-R1a signals through Gq, Gi/o, G13, and arrestin. Biasing GHS-R1a signaling with specific ligands may lead to the development of more selective drugs to treat obesity or addiction with minimal side effects. To delineate ligand selectivity at GHS-R1a signaling, we analyzed in detail the efficacy of a panel of synthetic ligands activating the different pathways associated with GHS-R1a in HEK293T cells. Besides β-arrestin2 recruitment and ERK1/2 phosphorylation, we monitored activation of a large panel of G protein subtypes using a bioluminescence resonance energy transfer-based assay with G protein-activation biosensors. We first found that unlike full agonists, Gq partial agonists were unable to trigger β-arrestin2 recruitment and ERK1/2 phosphorylation. Using G protein-activation biosensors, we then demonstrated that ghrelin promoted activation of Gq, Gi1, Gi2, Gi3, Goa, Gob, and G13 but not Gs and G12. Besides, we identified some GHS-R1a ligands that preferentially activated Gq and antagonized ghrelin-mediated Gi/Go activation. Finally, we unambiguously demonstrated that in addition to Gq, GHS-R1a also promoted constitutive activation of G13. Importantly, we identified some ligands that were selective inverse agonists toward Gq but not of G13. This demonstrates that bias at GHS-R1a signaling can occur not only with regard to agonism but also to inverse agonism. Our data, combined with other in vivo studies, may facilitate the design of drugs selectively targeting individual signaling pathways to treat only the therapeutically relevant function.
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Affiliation(s)
- Céline M'Kadmi
- Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 05
| | - Jean-Philippe Leyris
- the Institut des Neurosciences de Montpellier, Hôpital Saint-Eloi, 80 Avenue Augustin Fliche, BP 74103, 34091 Montpellier Cedex 05
| | - Lauriane Onfroy
- the Institut des Maladies Métaboliques et Cardiovasculaires, INSERM, U1048, Université Toulouse III Paul Sabatier, Centre Hospitalier Universitaire de Toulouse, 31432 Toulouse, France
| | - Céline Galés
- the Institut des Maladies Métaboliques et Cardiovasculaires, INSERM, U1048, Université Toulouse III Paul Sabatier, Centre Hospitalier Universitaire de Toulouse, 31432 Toulouse, France
| | - Aude Saulière
- the Institut des Maladies Métaboliques et Cardiovasculaires, INSERM, U1048, Université Toulouse III Paul Sabatier, Centre Hospitalier Universitaire de Toulouse, 31432 Toulouse, France
| | - Didier Gagne
- Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 05
| | - Marjorie Damian
- Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 05
| | - Sophie Mary
- Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 05
| | - Mathieu Maingot
- Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 05
| | - Séverine Denoyelle
- Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 05
| | - Pascal Verdié
- Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 05
| | - Jean-Alain Fehrentz
- Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 05
| | - Jean Martinez
- Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 05
| | - Jean-Louis Banères
- Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 05
| | - Jacky Marie
- Institut des Biomolécules Max Mousseron, UMR 5247 CNRS-Université Montpellier-ENSCM, Faculté de Pharmacie, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 05,.
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35
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Guthrie GJ, Aydemir TB, Troche C, Martin AB, Chang SM, Cousins RJ. Influence of ZIP14 (slc39A14) on intestinal zinc processing and barrier function. Am J Physiol Gastrointest Liver Physiol 2015; 308:G171-8. [PMID: 25428902 PMCID: PMC4312952 DOI: 10.1152/ajpgi.00021.2014] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
ZIP14 is a zinc transport protein with high expression in the small intestine and liver. Zip14 is upregulated during endotoxemia and leads to increased liver zinc content and transient hypozinemia. Since body zinc status and inflammation are associated with changes in intestinal permeability, we hypothesized that ZIP14 may influence intestinal permeability. Wild-type (WT) and Zip14 knockout (KO) mice were used to determine ZIP14-associated intestinal zinc metabolism and effects on permeability. Fractionation of plasma membranes revealed that ZIP14 is localized to the basolateral membrane of enterocytes. Studies utilizing (65)Zn administered by subcutaneous injection revealed greater zinc accumulation in the SI of Zip14 KO mice compared with WT mice. Isolation of endosomes confirmed the presence of ZIP14. Quantification of endosomal zinc concentration by FluoZin-3AM fluorescence demonstrated that zinc is trapped in endosomes of Zip14 KO mice. Intestinal permeability assessed both by plasma FITC-dextran following gavage and by serum endotoxin content was greater in Zip14 KO mice. Threonine phosphorylation of the tight junction protein occludin, which is necessary for tight junction assembly, was reduced in KO mice. Claudin 1 and 2, known to have an inverse relationship in regards to tight junction integrity, reflected impaired barrier function in KO jejunum. These data suggest involvement of ZIP14 in providing zinc for a regulatory role needed for maintenance of the intestinal barrier. In conclusion, ZIP14 is a basolaterally localized protein in enterocytes and is involved in endosomal trafficking of zinc and is necessary for proper maintenance of intestinal tight junctions.
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Affiliation(s)
- Gregory J. Guthrie
- Food Science and Human Nutrition Department and Center for Nutritional Sciences, College of Agricultural and Life Sciences, University of Florida, Gainesville, Florida
| | - Tolunay B. Aydemir
- Food Science and Human Nutrition Department and Center for Nutritional Sciences, College of Agricultural and Life Sciences, University of Florida, Gainesville, Florida
| | - Catalina Troche
- Food Science and Human Nutrition Department and Center for Nutritional Sciences, College of Agricultural and Life Sciences, University of Florida, Gainesville, Florida
| | - Alyssa B. Martin
- Food Science and Human Nutrition Department and Center for Nutritional Sciences, College of Agricultural and Life Sciences, University of Florida, Gainesville, Florida
| | - Shou-Mei Chang
- Food Science and Human Nutrition Department and Center for Nutritional Sciences, College of Agricultural and Life Sciences, University of Florida, Gainesville, Florida
| | - Robert J. Cousins
- Food Science and Human Nutrition Department and Center for Nutritional Sciences, College of Agricultural and Life Sciences, University of Florida, Gainesville, Florida
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36
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Mear Y, Blanchard MP, Defilles C, Brue T, Figarella-Branger D, Graillon T, Manavela M, Barlier A, Enjalbert A, Thirion S. Ghrelin receptor (GHS-R1a) and its constitutive activity in somatotroph adenomas: a new co-targeting therapy using GHS-R1a inverse agonists and somatostatin analogs. J Clin Endocrinol Metab 2014; 99:E2463-71. [PMID: 25272306 DOI: 10.1210/jc.2014-2753] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
CONTEXT The ghrelin receptor GHS-R1a is highly expressed in human somatotroph adenomas and exhibits unusually high basal signaling activity. In humans, the suppression of this constitutive activity by mutation induces a short stature. OBJECTIVE Using a GHS-R1a inverse agonist, modified substance P (MSP), we explored the role of GHS-R1a constitutive activity in GH hypersecretion from somatotroph adenomas and as a putative therapeutic target. DESIGN The effects of MSP were assessed on GH secretion from 19 human somatotroph tumors in vitro. Moreover, these effects were compared with those of octreotide (somatostatin receptor subtype 2 [sst2] agonist) and with the combination of both drugs. Expression and localization of GHS-R1a and sst2 were studied. RESULTS For all tumors, MSP inhibited GH secretion in a dose-dependent manner from 13 to 64%. Moreover, MSP enhanced octreotide-induced GH inhibition. For five tumors, the effects of combined MSP plus octreotide treatment were significantly higher than the sum of effects of each drug alone. MSP increased the membrane localization of GHS-R1a and of microdomains colocalizing sst2-GHS-R1a, highlighting the cooperation between the two drugs. CONCLUSIONS The GHS-R1a inverse agonist could open new therapeutic options for acromegalic patients, particularly patients partially sensitive to octreotide whose GH secretion is not completely controlled by the sst2 agonist.
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Affiliation(s)
- Yves Mear
- Aix-Marseille University (Y.M., M.-P.B., C.D., T.B., T.G., A.B., A.E., S.T.), Centre National de la Recherche Scientifique, CRN2M UMR7286, 13344 Marseille, France; APHM, Conception (A.B., A.E.), Laboratory of Molecular Biology, 13385 Marseille, France; APHM, Timone, Department of Endocrinology (T.B.), Department of Neurosurgery (T.G.), and Laboratory of Neuropathology (D.F.-B.), 13385 Marseille, France; Aix-Marseille University (D.F.-B.), INSERM, CRO2 UMR911, 13385 Marseille, France; and Buenos Aires University (M.M.), Department of Endocrinology, Hospital de Clinicas, Buenos Aires 1120, Argentina
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Evron T, Peterson SM, Urs NM, Bai Y, Rochelle LK, Caron MG, Barak LS. G Protein and β-arrestin signaling bias at the ghrelin receptor. J Biol Chem 2014; 289:33442-55. [PMID: 25261469 DOI: 10.1074/jbc.m114.581397] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The G protein-coupled ghrelin receptor GHSR1a is a potential pharmacological target for treating obesity and addiction because of the critical role ghrelin plays in energy homeostasis and dopamine-dependent reward. GHSR1a enhances growth hormone release, appetite, and dopamine signaling through G(q/11), G(i/o), and G(12/13) as well as β-arrestin-based scaffolds. However, the contribution of individual G protein and β-arrestin pathways to the diverse physiological responses mediated by ghrelin remains unknown. To characterize whether a signaling bias occurs for GHSR1a, we investigated ghrelin signaling in a number of cell-based assays, including Ca(2+) mobilization, serum response factor response element, stress fiber formation, ERK1/2 phosphorylation, and β-arrestin translocation, utilizing intracellular second loop and C-tail mutants of GHSR1a. We observed that GHSR1a and β-arrestin rapidly form metastable plasma membrane complexes following exposure to an agonist, but replacement of the GHSR1a C-tail by the tail of the vasopressin 2 receptor greatly stabilizes them, producing complexes observable on the plasma membrane and also in endocytic vesicles. Mutations of the contiguous conserved amino acids Pro-148 and Leu-149 in the GHSR1a intracellular second loop generate receptors with a strong bias to G protein and β-arrestin, respectively, supporting a role for conformation-dependent signaling bias in the wild-type receptor. Our results demonstrate more balance in GHSR1a-mediated ERK signaling from G proteins and β-arrestin but uncover an important role for β-arrestin in RhoA activation and stress fiber formation. These findings suggest an avenue for modulating drug abuse-associated changes in synaptic plasticity via GHSR1a and indicate the development of GHSR1a-biased ligands as a promising strategy for selectively targeting downstream signaling events.
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Affiliation(s)
| | | | | | - Yushi Bai
- From the Departments of Cell Biology
| | | | - Marc G Caron
- From the Departments of Cell Biology, Neurobiology, and Medicine, Duke University, Medical Center, Durham, North Carolina 27710
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38
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Sivertsen B, Holliday N, Madsen AN, Holst B. Functionally biased signalling properties of 7TM receptors - opportunities for drug development for the ghrelin receptor. Br J Pharmacol 2014; 170:1349-62. [PMID: 24032557 DOI: 10.1111/bph.12361] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 06/17/2013] [Accepted: 08/06/2013] [Indexed: 12/23/2022] Open
Abstract
UNLABELLED The ghrelin receptor is a 7 transmembrane (7TM) receptor involved in a variety of physiological functions including growth hormone secretion, increased food intake and fat accumulation as well as modulation of reward and cognitive functions. Because of its important role in metabolism and energy expenditure, the ghrelin receptor has become an important therapeutic target for drug design and the development of anti-obesity compounds. However, none of the compounds developed so far have been approved for commercial use. Interestingly, the ghrelin receptor is able to signal through several different signalling pathways including Gαq , Gαi/o , Gα12/13 and arrestin recruitment. These multiple signalling pathways allow for functionally biased signalling, where one signalling pathway may be favoured over another either by selective ligands or through mutations in the receptor. In the present review, we have described how ligands and mutations in the 7TM receptor may bias the receptors to favour either one G-protein over another or to promote G-protein independent signalling pathways rather than G-protein-dependent pathways. For the ghrelin receptor, both agonist and inverse agonists have been demonstrated to signal more strongly through the Gαq -coupled pathway than the Gα12/13 -coupled pathway. Similarly a ligand that promotes Gαq coupling over Gαi coupling has been described and it has been suggested that several different active conformations of the receptor may exist dependent on the properties of the agonist. Importantly, ligands with such biased signalling properties may allow the development of drugs that selectively modulate only the therapeutically relevant physiological functions, thereby decreasing the risk of side effects. LINKED ARTICLES This article is part of a themed section on Neuropeptides. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2013.170.issue-7.
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Affiliation(s)
- B Sivertsen
- Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, the Panum Institute, University of Copenhagen, Copenhagen, Denmark
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39
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Yuan MJ, Huang H, Huang CX. Potential new role of the GHSR-1a-mediated signaling pathway in cardiac remodeling after myocardial infarction (Review). Oncol Lett 2014; 8:969-971. [PMID: 25120643 PMCID: PMC4114710 DOI: 10.3892/ol.2014.2245] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2013] [Accepted: 05/15/2014] [Indexed: 11/17/2022] Open
Abstract
The gastrointestinal hormone ghrelin has important cardiovascular protective effects, however, its specific mechanisms are not yet completely understood. Recent studies have shown that the ghrelin receptor, growth hormone secretagogue receptor type 1a (GHSR-1a), regulates cell proliferation, apoptosis and inflammation-related signaling pathways. In human aortic endothelial cells, ghrelin activates NO production through AMP-activated protein kinase (AMPK) and Akt activation, and these effects can be blocked by knockdown of GHSR-1a. Obese mice have been found to exhibit an increased GHSR-1a content and expression in the heart, associated with an increase in phosphatidylinositol 3-kinase (PI3K) content and an increase AKT content and phosphorylation. Furthermore, GHSR-1a expression was observed to be increased in heart failure after myocardial infarction (MI) in rats. Given such complexity in GHSR-1a signaling and crosstalk with the AMPK and PI3K/Akt signaling pathways, both of which are well-known factors involved in cardiac remodeling after MI, we speculate that GHSR-1a signaling may play a regulatory role in cardiac protection and hope to identify new drugs targets. However, to date, no direct association between GHSR-1a and cardiac remodeling has been found. Therefore, further studies are required.
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Affiliation(s)
- Ming-Jie Yuan
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
| | - He Huang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
| | - Cong-Xin Huang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
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40
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The growth hormone secretagogue receptor: its intracellular signaling and regulation. Int J Mol Sci 2014; 15:4837-55. [PMID: 24651458 PMCID: PMC3975427 DOI: 10.3390/ijms15034837] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 03/06/2014] [Accepted: 03/11/2014] [Indexed: 01/29/2023] Open
Abstract
The growth hormone secretagogue receptor (GHSR), also known as the ghrelin receptor, is involved in mediating a wide variety of biological effects of ghrelin, including: stimulation of growth hormone release, increase of food intake and body weight, modulation of glucose and lipid metabolism, regulation of gastrointestinal motility and secretion, protection of neuronal and cardiovascular cells, and regulation of immune function. Dependent on the tissues and cells, activation of GHSR may trigger a diversity of signaling mechanisms and subsequent distinct physiological responses. Distinct regulation of GHSR occurs at levels of transcription, receptor interaction and internalization. Here we review the current understanding on the intracellular signaling pathways of GHSR and its modulation. An overview of the molecular structure of GHSR is presented first, followed by the discussion on its signaling mechanisms. Finally, potential mechanisms regulating GHSR are reviewed.
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41
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Mear Y, Enjalbert A, Thirion S. GHS-R1a constitutive activity and its physiological relevance. Front Neurosci 2013; 7:87. [PMID: 23754971 PMCID: PMC3665924 DOI: 10.3389/fnins.2013.00087] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Accepted: 05/09/2013] [Indexed: 12/14/2022] Open
Abstract
Abundant evidences have shown that ghrelin, by its binding to GHS-R1a, plays an important role for fundamental physiological functions. Increasing attention is given to the GHS-R1a unusually high constitutive activity and its contribution to downstream signaling and physiological processes. Here, we review recent lines of evidences showing that the interaction between ligand-binding pocket TM domains and the ECL2 could be partially responsible for this high constitutive activity. Interestingly, GHSR-1a constitutive activity activates in turn the downstream PLC, PKC, and CRE signaling pathways and this activation is reversed by the inverse agonist [D-Arg1, D-Phe5, D-Trp7,9, Leu11]-substance P (MSP). Noteworthy, GHSR-1a exhibits a C-terminal-dependent constitutive internalization. Non-sense GHS-R1a mutation (Ala204Glu), first discovered in Moroccan patients, supports the role of GHSR-1a constitutive activity in physiological impairments. Ala204Glu-point mutation, altering exclusively the GHSR-1a constitutive activity, was associated with familial short stature syndrome. Altogether, these findings suggest that GHS-R1a constitutive activity could contribute to GH secretion or body weight regulation. Consequently, future research on basic and clinical applications of GHS-R1a inverse agonists will be challenging and potentially rewarding.
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Affiliation(s)
- Yves Mear
- CNRS, CRN2M UMR7286, Aix Marseille University Marseille, France
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42
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Simon AC, Loverdo C, Gaffuri AL, Urbanski M, Ladarre D, Carrel D, Rivals I, Leterrier C, Benichou O, Dournaud P, Szabo B, Voituriez R, Lenkei Z. Activation-dependent plasticity of polarized GPCR distribution on the neuronal surface. J Mol Cell Biol 2013; 5:250-65. [PMID: 23585691 DOI: 10.1093/jmcb/mjt014] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Directionality of information flow through neuronal networks is sustained at cellular level by polarized neurons. However, specific targeting or anchoring motifs responsible for polarized distribution on the neuronal surface have only been identified for a few neuronal G-protein-coupled receptors (GPCRs). Here, through mutational and pharmacological modifications of the conformational state of two model GPCRs, the axonal CB1R cannabinoid and the somatodendritic SSTR2 somatostatin receptors, we show important conformation-dependent variations in polarized distribution. The underlying mechanisms include lower efficiency of conformation-dependent GPCR endocytosis in axons, compared with dendrites, particularly at moderate activation levels, as well as endocytosis-dependent transcytotic delivery of GPCRs from the somatodendritic domain to distal axonal portions, shown by using compartmentalized microfluidic devices. Kinetic modeling predicted that GPCR distribution polarity is highly regulated by steady-state endocytosis, which is conformation dependent and is able to regulate the relative amount of GPCRs targeted to axons and that axonally polarized distribution is an intermediary phenotype that appears at moderate basal activation levels. Indeed, we experimentally show that gradual changes in basal activation-dependent endocytosis lead to highly correlated shifts of polarized GPCR distribution on the neuronal surface, which can even result in a fully reversed polarized distribution of naturally somatodendritic or axonal GPCRs. In conclusion, polarized distribution of neuronal GPCRs may have a pharmacologically controllable component, which, in the absence of dominant targeting motifs, could even represent the principal regulator of sub-neuronal distribution. Consequently, chronic modifications of basal GPCR activation by therapeutic or abused drugs may lead to previously unanticipated changes in brain function through perturbation of polarized GPCR distribution on the neuronal surface.
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Affiliation(s)
- Anne C Simon
- Laboratoire de Neurobiologie, CNRS UMR7637, ESPCI-ParisTech, 10 Rue Vauquelin, Paris 75005, France
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43
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GI functions of GPR39: novel biology. Curr Opin Pharmacol 2012; 12:647-52. [PMID: 22884904 DOI: 10.1016/j.coph.2012.07.019] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 07/24/2012] [Accepted: 07/27/2012] [Indexed: 01/20/2023]
Abstract
GPR39 is an orphan GPCR receptor belonging to the ghrelin/motilin receptor subfamily. The receptor is constitutively active and Zn(2+) is a physiological agonist of GPR39. The receptor is emerging as an important regulator of gastrointestinal motility and secretion. Although GPR39 does not seem to be involved in the regulation of food intake, contradictory results are available on the role of GPR39 in the regulation of body weight. A well-established stimulatory role for GPR39 has been defined in insulin secretion which makes the receptor an attractive target for the treatment of type 1 or 2 diabetes. GPR39 signaling also inhibits apoptosis and mediates neural synaptic signaling. Novel ligands of GPR39 are warranted to reveal the main physiological role of this receptor.
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44
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Gaffuri AL, Ladarre D, Lenkei Z. Type-1 cannabinoid receptor signaling in neuronal development. Pharmacology 2012; 90:19-39. [PMID: 22776780 DOI: 10.1159/000339075] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Accepted: 04/13/2012] [Indexed: 01/21/2023]
Abstract
The type-1 cannabinoid receptor (CB1R) was initially identified as the neuronal target of Δ(9)-tetrahydrocannabinol (THC), the major psychoactive substance of marijuana. This receptor is one of the most abundant G-protein-coupled receptors in the adult brain, the target of endocannabinoid ligands and a well-characterized retrograde synaptic regulator. However, CB1Rs are also highly and often transiently expressed in neuronal populations in the embryonic and early postnatal brain, even before the formation of synapses. This suggests important physiological roles for CB1Rs during neuronal development. Several recent reviews have summarized our knowledge about the role of the endocannabinoid (eCB) system in neurodevelopment and neurotransmission by focusing on the metabolism of endocannabinoid molecules. Here, we review current knowledge about the effects of the modulation of CB1R signaling during the different phases of brain development. More precisely, we focus on reports that directly implicate CB1Rs during progenitor cell migration and differentiation, neurite outgrowth, axonal pathfinding and synaptogenesis. Based on theoretical considerations and on the reviewed experimental data, we propose a new model to explain the diversity of experimental findings on eCB signaling on neurite growth and axonal pathfinding. In our model, cell-autonomus and paracrine eCBs acting on CB1Rs are part of a global inhibitory network of cytoskeletal effectors, which act in concert with positive-feedback local-excitation loops, to ultimately yield highly polarized neurons.
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Affiliation(s)
- Anne-Lise Gaffuri
- Neurobiology Laboratory, ESPCI-ParisTech, ESPCI-CNRS UMR 7637, Paris, France
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45
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Portelli J, Thielemans L, Ver Donck L, Loyens E, Coppens J, Aourz N, Aerssens J, Vermoesen K, Clinckers R, Schallier A, Michotte Y, Moechars D, Collingridge GL, Bortolotto ZA, Smolders I. Inactivation of the constitutively active ghrelin receptor attenuates limbic seizure activity in rodents. Neurotherapeutics 2012; 9:658-72. [PMID: 22669710 PMCID: PMC3441926 DOI: 10.1007/s13311-012-0125-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Ghrelin is a pleiotropic neuropeptide that has been recently implicated in epilepsy. Animal studies performed to date indicate that ghrelin has anticonvulsant properties; however, its mechanism of anticonvulsant action is unknown. Here we show that the anticonvulsant effects of ghrelin are mediated via the growth hormone secretagogue receptor (GHSR). To our surprise, however, we found that the GHSR knockout mice had a higher seizure threshold than their wild-type littermates when treated with pilocarpine. Using both in vivo and in vitro models, we further discovered that inverse agonism and desensitization/internalization of the GHSR attenuate limbic seizures in rats and epileptiform activity in hippocampal slices. This constitutes a novel mechanism of anticonvulsant action, whereby an endogenous agonist reduces the activity of a constitutively active receptor.
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Affiliation(s)
- Jeanelle Portelli
- Center for Neurosciences, Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium
| | - Leen Thielemans
- Janssen Research and Development, a Division of Janssen Pharmaceutica NV, 2340 Beerse, Belgium
| | - Luc Ver Donck
- Janssen Research and Development, a Division of Janssen Pharmaceutica NV, 2340 Beerse, Belgium
| | - Ellen Loyens
- Center for Neurosciences, Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium
| | - Jessica Coppens
- Center for Neurosciences, Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium
| | - Najat Aourz
- Center for Neurosciences, Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium
| | - Jeroen Aerssens
- Janssen Research and Development, a Division of Janssen Pharmaceutica NV, 2340 Beerse, Belgium
| | - Katia Vermoesen
- Center for Neurosciences, Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium
| | - Ralph Clinckers
- Center for Neurosciences, Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium
| | - Anneleen Schallier
- Center for Neurosciences, Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium
| | - Yvette Michotte
- Center for Neurosciences, Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium
| | - Dieder Moechars
- Janssen Research and Development, a Division of Janssen Pharmaceutica NV, 2340 Beerse, Belgium
| | - Graham L. Collingridge
- MRC Centre for Synaptic Plasticity, School of Physiology and Pharmacology, University of Bristol, BS8 1TD Bristol, United Kingdom
- Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, 151-746 Seoul, Gwanakgu Korea
| | - Zuner A. Bortolotto
- MRC Centre for Synaptic Plasticity, School of Physiology and Pharmacology, University of Bristol, BS8 1TD Bristol, United Kingdom
| | - Ilse Smolders
- Center for Neurosciences, Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium
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46
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Ligands and signaling proteins govern the conformational landscape explored by a G protein-coupled receptor. Proc Natl Acad Sci U S A 2012; 109:8304-9. [PMID: 22573814 DOI: 10.1073/pnas.1119881109] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The dynamic character of G protein-coupled receptors is essential to their function. However, the details of how ligands stabilize a particular conformation to selectively activate a signaling pathway and how signaling proteins affect this conformational repertoire remain unclear. Using a prototypical peptide-activated class A G protein-coupled receptor (GPCR), the ghrelin receptor, reconstituted as a monomer into lipid discs and labeled with a fluorescent conformational reporter, we demonstrate that ligand efficacy and functional selectivity are directly related to different receptor conformations. Of importance, our data bring direct evidence that distinct effector proteins affect the conformational landscape of the ghrelin receptor in different ways. Whereas G proteins affect the balance between active and inactive receptor substates in favor of the active state, agonist-induced arrestin recruitment is accompanied by a marked change in the structural features of the receptor that adopt a conformation different from that observed in the absence of arrestin. In contrast to G proteins and arrestins, μ-AP2 has no significant effect on the organization of the transmembrane core of the receptor. Such a modulation of a GPCR conformational landscape by pharmacologically distinct ligands and effectors provides insights into the structural bases that decisively affect ligand efficacy and subsequent biological responses. This is also likely to have major implications for the design of drugs activating specific GPCR-associated signaling pathways.
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47
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Reimann F, Tolhurst G, Gribble FM. G-protein-coupled receptors in intestinal chemosensation. Cell Metab 2012; 15:421-31. [PMID: 22482725 DOI: 10.1016/j.cmet.2011.12.019] [Citation(s) in RCA: 174] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 11/21/2011] [Accepted: 12/15/2011] [Indexed: 12/25/2022]
Abstract
Food intake is detected by the chemical senses of taste and smell and subsequently by chemosensory cells in the gastrointestinal tract that link the composition of ingested foods to feedback circuits controlling gut motility/secretion, appetite, and peripheral nutrient disposal. G-protein-coupled receptors responsive to a range of nutrients and other food components have been identified, and many are localized to intestinal chemosensory cells, eliciting hormonal and neuronal signaling to the brain and periphery. This review examines the role of G-protein-coupled receptors as signaling molecules in the gut, with a particular focus on pathways relevant to appetite and glucose homeostasis.
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Affiliation(s)
- Frank Reimann
- Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Addenbrooke's Hospital, Hills Road, Cambridge, UK.
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48
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Bazzacco P, Billon-Denis E, Sharma KS, Catoire LJ, Mary S, Le Bon C, Point E, Banères JL, Durand G, Zito F, Pucci B, Popot JL. Nonionic Homopolymeric Amphipols: Application to Membrane Protein Folding, Cell-Free Synthesis, and Solution Nuclear Magnetic Resonance. Biochemistry 2012; 51:1416-30. [DOI: 10.1021/bi201862v] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Paola Bazzacco
- Unité Mixte de Recherche
7099, Centre National de la Recherche Scientifique and Université Paris 7, Institut de Biologie Physico-Chimique,
13 rue Pierre-et-Marie Curie, F-75005 Paris, France
| | - Emmanuelle Billon-Denis
- Unité Mixte de Recherche
7099, Centre National de la Recherche Scientifique and Université Paris 7, Institut de Biologie Physico-Chimique,
13 rue Pierre-et-Marie Curie, F-75005 Paris, France
| | - K. Shivaji Sharma
- Université d′Avignon et des Pays de Vaucluse, Equipe Chimie
Bioorganique et Systèmes Amphiphiles, 33 rue Louis Pasteur,
F-84000 Avignon, France
| | - Laurent J. Catoire
- Unité Mixte de Recherche
7099, Centre National de la Recherche Scientifique and Université Paris 7, Institut de Biologie Physico-Chimique,
13 rue Pierre-et-Marie Curie, F-75005 Paris, France
| | - Sophie Mary
- Unité Mixte de Recherche 5247, Centre National de la Recherche Scientifique and Universités de Montpellier 1 & 2, Faculté de Pharmacie, Institut des Biomolécules Max Mousseron, 15 avenue Charles Flahault, F-34093 Montpellier Cedex 05, France
| | - Christel Le Bon
- Unité Mixte de Recherche
7099, Centre National de la Recherche Scientifique and Université Paris 7, Institut de Biologie Physico-Chimique,
13 rue Pierre-et-Marie Curie, F-75005 Paris, France
| | - Elodie Point
- Unité Mixte de Recherche
7099, Centre National de la Recherche Scientifique and Université Paris 7, Institut de Biologie Physico-Chimique,
13 rue Pierre-et-Marie Curie, F-75005 Paris, France
| | - Jean-Louis Banères
- Unité Mixte de Recherche 5247, Centre National de la Recherche Scientifique and Universités de Montpellier 1 & 2, Faculté de Pharmacie, Institut des Biomolécules Max Mousseron, 15 avenue Charles Flahault, F-34093 Montpellier Cedex 05, France
| | - Grégory Durand
- Université d′Avignon et des Pays de Vaucluse, Equipe Chimie
Bioorganique et Systèmes Amphiphiles, 33 rue Louis Pasteur,
F-84000 Avignon, France
- Unité Mixte de Recherche 5247, Centre National de la Recherche Scientifique and Universités de Montpellier 1 & 2, Faculté de Pharmacie, Institut des Biomolécules Max Mousseron, 15 avenue Charles Flahault, F-34093 Montpellier Cedex 05, France
| | - Francesca Zito
- Unité Mixte de Recherche
7099, Centre National de la Recherche Scientifique and Université Paris 7, Institut de Biologie Physico-Chimique,
13 rue Pierre-et-Marie Curie, F-75005 Paris, France
| | - Bernard Pucci
- Université d′Avignon et des Pays de Vaucluse, Equipe Chimie
Bioorganique et Systèmes Amphiphiles, 33 rue Louis Pasteur,
F-84000 Avignon, France
- Unité Mixte de Recherche 5247, Centre National de la Recherche Scientifique and Universités de Montpellier 1 & 2, Faculté de Pharmacie, Institut des Biomolécules Max Mousseron, 15 avenue Charles Flahault, F-34093 Montpellier Cedex 05, France
| | - Jean-Luc Popot
- Unité Mixte de Recherche
7099, Centre National de la Recherche Scientifique and Université Paris 7, Institut de Biologie Physico-Chimique,
13 rue Pierre-et-Marie Curie, F-75005 Paris, France
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49
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Chow KBS, Sun J, Chu KM, Tai Cheung W, Cheng CHK, Wise H. The truncated ghrelin receptor polypeptide (GHS-R1b) is localized in the endoplasmic reticulum where it forms heterodimers with ghrelin receptors (GHS-R1a) to attenuate their cell surface expression. Mol Cell Endocrinol 2012; 348:247-54. [PMID: 21903149 DOI: 10.1016/j.mce.2011.08.034] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 08/24/2011] [Accepted: 08/26/2011] [Indexed: 11/27/2022]
Abstract
The ghrelin receptor (GHS-R1a) is remarkable amongst G-protein-coupled receptors for its high degree of constitutive activity, and this agonist-independent activity may be important for its physiological function in the control of food intake and body weight. Ghrelin receptors form heterodimers with the truncated ghrelin receptor polypeptide (GHS-R1b), which has a dominant-negative effect on ghrelin receptor function. Here we show that GHS-R1b has an intracellular localization distinct from ghrelin receptors, being primarily localized in the endoplasmic reticulum. Immunocytochemical studies suggest that GHS-R1b decreases the plasma membrane expression of ghrelin receptors, but the overall distribution profile of ghrelin receptors in isolated subcellular fractions is unaffected by GHS-R1b. Using bioluminescence resonance energy transfer methods, we have shown that while ghrelin receptor homodimers are evenly distributed in all subcellular fractions, GHS-R1a/GHS-R1b heterodimers are concentrated within the endoplasmic reticulum and these results suggest that GHS-R1b traps ghrelin receptors within the endoplasmic reticulum by the process of oligomerization. Furthermore, ghrelin receptors constitutively activated extracellular signal-regulated kinases 1/2 in the endoplasmic reticulum, but this small response was not affected by GHS-R1b and its physiological relevance is uncertain. Taken together, these results suggest that ghrelin receptors can be retained in the endoplasmic reticulum by heterodimerization with GHS-R1b, and constitutive activation of phospholipase C is attenuated due to decreased cell surface expression of ghrelin receptors. However, sufficient ghrelin receptor homodimers can still be expressed on the cell surface for maximal responses to agonist stimulation.
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Affiliation(s)
- Kevin B S Chow
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China
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50
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Delporte C. Recent advances in potential clinical application of ghrelin in obesity. J Obes 2012; 2012:535624. [PMID: 22523666 PMCID: PMC3317165 DOI: 10.1155/2012/535624] [Citation(s) in RCA: 17] [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: 06/17/2011] [Accepted: 12/04/2011] [Indexed: 02/07/2023] Open
Abstract
Ghrelin is the natural ligand of the growth hormone secretagogue receptor (GHS-R1a). Ghrelin is a 28 amino acid peptide possessing a unique acylation on the serine in position 3 catalyzed by ghrelin O-acyltransferase (GOAT). Ghrelin stimulates growth hormone secretion, but also appetite, food intake, weight gain, and gastric emptying. Ghrelin is involved in weight regulation, obesity, type 2 diabetes, and metabolic syndrome. Furthermore, a better understanding of ghrelin biology led to the identification of molecular targets modulating ghrelin levels and/or its biological effects: GOAT, ghrelin, and GHS-R1a. Furthermore, a recent discovery, showing the involvement of bitter taste receptor T2R in ghrelin secretion and/or synthesis and food intake, suggested that T2R could represent an additional interesting molecular target. Several classes of ghrelin-related pharmacological tools for the treatment of obesity have been or could be developed to modulate the identified molecular targets.
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Affiliation(s)
- Christine Delporte
- Laboratory of Biological Chemistry and Nutrition, Faculty of Medicine, Université libre de Bruxelles, 1070 Brussels, Belgium
- *Christine Delporte:
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