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Moose JE, Leets KA, Mate NA, Chisholm JD, Hougland JL. An overview of ghrelin O-acyltransferase inhibitors: a literature and patent review for 2010-2019. Expert Opin Ther Pat 2020; 30:581-593. [PMID: 32564644 DOI: 10.1080/13543776.2020.1776263] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
INTRODUCTION The peptide hormone ghrelin regulates physiological processes associated with energy homeostasis such as appetite, insulin signaling, glucose metabolism, and adiposity. Ghrelin has also been implicated in a growing number of neurological pathways involved in stress response and addiction behavior. For ghrelin to bind the growth hormone secretagogue receptor 1a (GHS-R1a) and activate signaling, the hormone must first be octanoylated on a specific serine side chain. This key transformation is performed by the enzyme ghrelin O-acyltransferase (GOAT), and therefore GOAT inhibitors may be useful in treating disorders related to ghrelin signaling such as diabetes, obesity, and related metabolic syndromes. AREAS COVERED This report covers ghrelin and GOAT as potential therapeutic targets and summarizes work on GOAT inhibitors through the end of 2019, highlighting recent successes with both peptidomimetics and small molecule GOAT inhibitors as potent modulators of GOAT-catalyzed ghrelin octanoylation. EXPERT OPINION A growing body of biochemical and structural knowledge regarding the ghrelin/GOAT system now enables multiple avenues for identifying and optimizing GOAT inhibitors. We are at the beginning of a new era with increased opportunities for leveraging ghrelin and GOAT in the understanding and treatment of multiple health conditions including diabetes, obesity, and addiction.
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Affiliation(s)
- Jacob E Moose
- Department of Chemistry and BioInspired Syracuse, Syracuse University , Syracuse, NY, USA
| | - Katelyn A Leets
- Department of Chemistry and BioInspired Syracuse, Syracuse University , Syracuse, NY, USA
| | - Nilamber A Mate
- Department of Chemistry and BioInspired Syracuse, Syracuse University , Syracuse, NY, USA
| | - John D Chisholm
- Department of Chemistry and BioInspired Syracuse, Syracuse University , Syracuse, NY, USA
| | - James L Hougland
- Department of Chemistry and BioInspired Syracuse, Syracuse University , Syracuse, NY, USA
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Jeon SG, Hong SB, Nam Y, Tae J, Yoo A, Song EJ, Kim KI, Lee D, Park J, Lee SM, Kim JI, Moon M. Ghrelin in Alzheimer's disease: Pathologic roles and therapeutic implications. Ageing Res Rev 2019; 55:100945. [PMID: 31434007 DOI: 10.1016/j.arr.2019.100945] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 07/25/2019] [Accepted: 08/16/2019] [Indexed: 12/11/2022]
Abstract
Ghrelin, which has many important physiological roles, such as stimulating food intake, regulating energy homeostasis, and releasing insulin, has recently been studied for its roles in a diverse range of neurological disorders. Despite the several functions of ghrelin in the central nervous system, whether it works as a therapeutic agent for neurological dysfunction has been unclear. Altered levels and various roles of ghrelin have been reported in Alzheimer's disease (AD), which is characterized by the accumulation of misfolded proteins resulting in synaptic loss and cognitive decline. Interestingly, treatment with ghrelin or with the agonist of ghrelin receptor showed attenuation in several cases of AD-related pathology. These findings suggest the potential therapeutic implications of ghrelin in the pathogenesis of AD. In the present review, we summarized the roles of ghrelin in AD pathogenesis, amyloid beta (Aβ) homeostasis, tau hyperphosphorylation, neuroinflammation, mitochondrial deficit, synaptic dysfunction and cognitive impairment. The findings from this review suggest that ghrelin has a novel therapeutic potential for AD treatment. Thus, rigorously designed studies are needed to establish an effective AD-modifying strategy.
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Nicke L, Müller R, Geyer A, Els-Heindl S. Side Chain Orientation of Tryptophan Analogues Determines Agonism and Inverse Agonism in Short Ghrelin Peptides. ChemMedChem 2019; 14:1849-1855. [PMID: 31442005 PMCID: PMC6899459 DOI: 10.1002/cmdc.201900409] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 08/23/2019] [Indexed: 02/06/2023]
Abstract
We describe two synthetic amino acids with inverted side chain stereochemistry, which induce opposite biological activity. Phe4 is an important part of the activation motif of ghrelin, and in short peptide inverse agonists such as KwFwLL-NH2 , the aromatic core is necessary for inactivation of the receptor. To restrict indole/phenyl mobility and simultaneously strengthen the interaction between peptide and receptor, we exchanged the natural monoaryl amino acids for diaryl amino acids derived from tryptophan. By standard solid-phase peptide synthesis, each of them was inserted into ghrelin or in the aromatic core of the inverse agonist. Both ghrelin analogues showed nanomolar activity, indicating sufficient space to accommodate the additional side chain. In contrast, diaryl amino acids in the inverse agonist had considerable influence on receptor signaling. Whereas the introduction of Wsf maintains inverse agonism of the peptide, Wrf shifts the receptor more to active states and can induce agonism depending on its introduction site.
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Affiliation(s)
- Lennart Nicke
- Faculty of Chemistry, Philipps-University Marburg, Hans-Meerwein-Strasse 4, 35032, Marburg, Germany
| | - Ronny Müller
- Faculty of Life Sciences, Institute of Biochemistry, Leipzig University, Brüderstrasse 34, 04103, Leipzig, Germany
| | - Armin Geyer
- Faculty of Chemistry, Philipps-University Marburg, Hans-Meerwein-Strasse 4, 35032, Marburg, Germany
| | - Sylvia Els-Heindl
- Faculty of Life Sciences, Institute of Biochemistry, Leipzig University, Brüderstrasse 34, 04103, Leipzig, Germany
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Cleverdon ER, McGovern-Gooch KR, Hougland JL. The octanoylated energy regulating hormone ghrelin: An expanded view of ghrelin's biological interactions and avenues for controlling ghrelin signaling. Mol Membr Biol 2017; 33:111-124. [PMID: 29143554 DOI: 10.1080/09687688.2017.1388930] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Ghrelin is a small peptide hormone that requires a unique post-translational modification, serine octanoylation, to bind and activate the GHS-R1a receptor. Initially demonstrated to stimulate hunger and appetite, ghrelin-dependent signaling is implicated in a variety of neurological and physiological processes influencing diseases such as diabetes, obesity, and Prader-Willi syndrome. In addition to its cognate receptor, recent studies have revealed ghrelin interacts with a range of binding partners within the bloodstream. Defining the scope of ghrelin's interactions within the body, understanding how these interactions work in concert to modulate ghrelin signaling, and developing molecular tools for controlling ghrelin signaling are essential for exploiting ghrelin for therapeutic effect. In this review, we discuss recent findings regarding the biological effects of ghrelin signaling, outline binding partners that control ghrelin trafficking and stability in circulation, and summarize the current landscape of inhibitors targeting ghrelin octanoylation.
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Affiliation(s)
| | | | - James L Hougland
- a Department of Chemistry , Syracuse University , Syracuse , NY , USA
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6
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Els-Heindl S, Bellmann-Sickert K, Beck-Sickinger AG. C-terminus of a hexapeptidic ghrelin receptor inverse agonist can switch peptide behavior from inverse agonism to agonism. Biopolymers 2017; 106:101-8. [PMID: 26566778 DOI: 10.1002/bip.22768] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 11/05/2015] [Accepted: 11/09/2015] [Indexed: 11/10/2022]
Abstract
Subtle changes in the sequence at the N-terminus and in the aromatic core of hexapeptidic ghrelin receptor inverse agonists can switch behavior from inverse agonism to agonism, but the C-terminal role of the sequence is unclear. Thus, analogs of the ghrelin receptor inverse agonist KbFwLL-NH2 (b = β-(3-benzothienyl)-d-alanine) were synthesized by solid phase peptide synthesis in order to identify the influence of aromaticity, charge, and hydrophobicity. Potency and efficacy of the hexapeptides were evaluated in inositol triphosphate turnover assays. Notably, modifications directly at the C-terminal Leu(6) could influence peptide efficacy leading to decreased constitutive activity. High hydrophobicity at the C-terminal position was of importance for elevated inverse agonist activity, the introduction of charged amino acids led to decreased potency. In contrast, structure-activity relationship studies of Leu(5) located closer to the aromatic core revealed an agonism-inducing position. These findings imply that amino acids with possible cation-π or π-π interactions and a suitable orientation at the C-terminus of the aromatic core induce agonism. Receptor binding studies showed that most peptides bind to the receptor at a concentration of 1 µM and modification directly at the C-terminus is generally more accepted than Leu(5) substitution. Interestingly, this observation is not dependent on the type of modification. These studies reveal another switch region of the short ghrelin receptor ligand pointing out the sensitivity of the ghrelin receptor binding pocket.
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Affiliation(s)
- Sylvia Els-Heindl
- Faculty of Biosciences, Pharmacy and Psychology, Institute of Biochemistry, Universität Leipzig, Brüderstraße 34, Leipzig, 04103, Germany
| | - Kathrin Bellmann-Sickert
- Faculty of Biosciences, Pharmacy and Psychology, Institute of Biochemistry, Universität Leipzig, Brüderstraße 34, Leipzig, 04103, Germany
| | - Annette G Beck-Sickinger
- Faculty of Biosciences, Pharmacy and Psychology, Institute of Biochemistry, Universität Leipzig, Brüderstraße 34, Leipzig, 04103, Germany
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Ferro P, Krotov G, Zvereva I, Rodchenkov G, Segura J. Structure-activity relationship for peptídic growth hormone secretagogues. Drug Test Anal 2016; 9:87-95. [PMID: 26811125 DOI: 10.1002/dta.1947] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 11/05/2015] [Accepted: 12/10/2015] [Indexed: 11/11/2022]
Abstract
Growth hormone releasing peptides (GHRPs) could be widely used by cheating athletes because they produce growth hormone (GH) secretion, so may generate an ergogenic effect in the body. Knowledge of the essential amino acids needed in GHRP structure for interaction with the target biological receptor GHSR1a, the absorption through different administration routes, and the maintenance of pharmacological activity of potential biotransformation products may help in the fight against their abuse in sport. Several GHRPs and truncated analogues with the common core Ala-Trp-(D-Phe)-Lys have been studied with a radio-competitive assay for the GHSR1a receptor against the radioactive natural ligand ghrelin. Relevant chemical modifications influencing the activity for positions 1, 2, 3, and 7 based on the structure aa-aa-aa-Ala-Trp-(D-Phe)-Lys have been obtained. To test in vivo the applicability of the activities observed, the receptor assay activity in samples from excretion studies performed after nasal administration of GHRP-1, GHRP-2, GHRP-6, Hexarelin, and Ipamorelin was confirmed. Overall results obtained allow to infer structure-activity information for those GHRPs and to detect GHSR1a binding (intact GHRPs plus active metabolites) in excreted urines. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- P Ferro
- Bioanalysis Research Group, Neuroscience Research Program, IMIM (Hospital del Mar Medical Research Institute), Barcelona, Spain
| | - G Krotov
- Antidoping Centre, Moscow, Russia
| | | | | | - J Segura
- Bioanalysis Research Group, Neuroscience Research Program, IMIM (Hospital del Mar Medical Research Institute), Barcelona, Spain.,Department of Experimental and Health Sciences, Pompeu Fabra University, Barcelona, Spain
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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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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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Schellekens H, De Francesco PN, Kandil D, Theeuwes WF, McCarthy T, van Oeffelen WEPA, Perelló M, Giblin L, Dinan TG, Cryan JF. Ghrelin's Orexigenic Effect Is Modulated via a Serotonin 2C Receptor Interaction. ACS Chem Neurosci 2015; 6:1186-97. [PMID: 25727097 DOI: 10.1021/cn500318q] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Understanding the intricate pathways that modulate appetite and subsequent food intake is of particular importance considering the rise in the incidence of obesity across the globe. The serotonergic system, specifically the 5-HT2C receptor, has been shown to be of critical importance in the regulation of appetite and satiety. The GHS-R1a receptor is another key receptor that is well-known for its role in the homeostatic control of food intake and energy balance. We recently showed compelling evidence for an interaction between the GHS-R1a receptor and the 5-HT2C receptor in an in vitro cell line system heterologously expressing both receptors. Here, we investigated this interaction further. First, we show that the GHS-R1a/5-HT2C dimer-induced attenuation of calcium signaling is not due to coupling to GαS, as no increase in cAMP signaling is observed. Next, flow cytometry fluorescence resonance energy transfer (fcFRET) is used to further demonstrate the direct interaction between the GHS-R1a receptor and 5-HT2C receptor. In addition, we demonstrate colocalized expression of the 5-HT2C and GHS-R1a receptor in cultured primary hypothalamic and hippocampal rat neurons, supporting the biological relevance of a physiological interaction. Furthermore, we demonstrate that when 5-HT2C receptor signaling is blocked ghrelin's orexigenic effect is potentiated in vivo. In contrast, the specific 5-HT2C receptor agonist lorcaserin, recently approved for the treatment of obesity, attenuates ghrelin-induced food intake. This underscores the biological significance of our in vitro findings of 5-HT2C receptor-mediated attenuation of GHS-R1a receptor activity. Together, this study demonstrates, for the first time, that the GHS-R1a/5-HT2C receptor interaction translates into a biologically significant modulation of ghrelin's orexigenic effect. This data highlights the potential development of a combined GHS-R1a and 5-HT2C receptor treatment strategy in weight management.
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Affiliation(s)
| | - Pablo N. De Francesco
- Laboratory
of Neurophysiology, Multidisciplinary Institute of Cell Biology, National Scientific and Technical Research Council, La Plata, Argentina
| | | | | | | | | | - Mario Perelló
- Laboratory
of Neurophysiology, Multidisciplinary Institute of Cell Biology, National Scientific and Technical Research Council, La Plata, Argentina
| | - Linda Giblin
- Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland
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Kilian TM, Klöting N, Bergmann R, Els-Heindl S, Babilon S, Clément-Ziza M, Zhang Y, Beck-Sickinger AG, Chollet C. Rational design of dual peptides targeting ghrelin and Y2 receptors to regulate food intake and body weight. J Med Chem 2015; 58:4180-93. [PMID: 25905598 DOI: 10.1021/jm501702q] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Ghrelin and Y2 receptors play a central role in appetite regulation inducing opposite effects. The Y2 receptor induces satiety, while the ghrelin receptor promotes hunger and weight gain. However, the food regulating system is tightly controlled by interconnected pathways where redundancies can lead to poor efficacy and drug tolerance when addressing a single molecule. We developed a multitarget strategy to synthesize dual peptides simultaneously inhibiting the ghrelin receptor and stimulating the Y2 receptor. Dual peptides showed dual activity in vitro, and one compound induced a slight diminution of food intake in a rodent model of obesity. In addition, stability studies in rats revealed different behaviors between the dual peptide and its corresponding monomers. The Y2 receptor agonist was unstable in blood, while the dual peptide showed an intermediate stability compared to that of the highly stable ghrelin receptor inverse agonist.
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Affiliation(s)
- Tom-Marten Kilian
- †Faculty of Biosciences, Pharmacy and Psychology, Institute of Biochemistry, Universität Leipzig, Brüderstrasse 34, 04103 Leipzig, Germany
| | - Nora Klöting
- ‡Integrated Research and Treatment Center Adiposity Diseases (IFB), Core Unit "Animal Models", Universität Leipzig, Liebigstrasse 21, 04103 Leipzig, Germany
| | - Ralf Bergmann
- §Department of Radiopharmaceutical and Chemical Biology, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, P.O. Box 510119, 01314 Dresden, Germany
| | - Sylvia Els-Heindl
- †Faculty of Biosciences, Pharmacy and Psychology, Institute of Biochemistry, Universität Leipzig, Brüderstrasse 34, 04103 Leipzig, Germany
| | - Stefanie Babilon
- †Faculty of Biosciences, Pharmacy and Psychology, Institute of Biochemistry, Universität Leipzig, Brüderstrasse 34, 04103 Leipzig, Germany
| | - Mathieu Clément-Ziza
- ∥CECAD - Cluster of Excellence, University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany
| | - Yixin Zhang
- ⊥B CUBE-Center for Molecular Bioengineering, Technische Universität Dresden, Arnoldstrasse 18, 01307 Dresden, Germany
| | - Annette G Beck-Sickinger
- †Faculty of Biosciences, Pharmacy and Psychology, Institute of Biochemistry, Universität Leipzig, Brüderstrasse 34, 04103 Leipzig, Germany
| | - Constance Chollet
- †Faculty of Biosciences, Pharmacy and Psychology, Institute of Biochemistry, Universität Leipzig, Brüderstrasse 34, 04103 Leipzig, Germany.,⊥B CUBE-Center for Molecular Bioengineering, Technische Universität Dresden, Arnoldstrasse 18, 01307 Dresden, Germany
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Callaghan B, Kosari S, Pustovit RV, Sartor DM, Ferens D, Ban K, Baell J, Nguyen TV, Rivera LR, Brock JA, Furness JB. Hypotensive effects of ghrelin receptor agonists mediated through a novel receptor. Br J Pharmacol 2014; 171:1275-86. [PMID: 24670149 DOI: 10.1111/bph.12527] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Revised: 09/27/2013] [Accepted: 11/12/2013] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND AND PURPOSE Some agonists of ghrelin receptors cause rapid decreases in BP. The mechanisms by which they cause hypotension and the pharmacology of the receptors are unknown. EXPERIMENTAL APPROACH The effects of ligands of ghrelin receptors were investigated in rats in vivo, on isolated blood vessels and on cells transfected with the only molecularly defined ghrelin receptor, growth hormone secretagogue receptor 1a (GHSR1a). KEY RESULTS Three agonists of GHSR1a receptors, ulimorelin, capromorelin and CP464709, caused a rapid decrease in BP in the anaesthetized rat. The effect was not reduced by either of two GHSR1a antagonists, JMV2959 or YIL781, at doses that blocked effects on colorectal motility, in vivo. The rapid hypotension was not mimicked by ghrelin, unacylated ghrelin or the unacylated ghrelin receptor agonist, AZP531. The early hypotension preceded a decrease in sympathetic nerve activity. Early hypotension was not reduced by hexamethonium or by baroreceptor (sino-aortic) denervation. Ulimorelin also relaxed isolated segments of rat mesenteric artery, and, less potently, relaxed aorta segments. The vascular relaxation was not reduced by JMV2959 or YIL781. Ulimorelin, capromorelin and CP464709 activated GHSR1a in transfected HEK293 cells at nanomolar concentrations. JMV2959 and YIL781 both antagonized effects in these cells, with their pA2 values at the GHSR1a receptor being 6.55 and 7.84. CONCLUSIONS AND IMPLICATIONS Our results indicate a novel vascular receptor or receptors whose activation by ulimorelin, capromorelin and CP464709 lowered BP. This receptor is activated by low MW GHSR1a agonists, but is not activated by ghrelin.
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Affiliation(s)
- Brid Callaghan
- Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Vic., Australia
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Synthesis and in vitro/in vivo evaluation of novel mono- and trivalent technetium-99m labeled ghrelin peptide complexes as potential diagnostic radiopharmaceuticals. Nucl Med Biol 2014; 42:28-37. [PMID: 25218025 DOI: 10.1016/j.nucmedbio.2014.08.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 06/23/2014] [Accepted: 08/16/2014] [Indexed: 02/02/2023]
Abstract
INTRODUCTION Ghrelin is an endogenous hormone present in blood. It is released from the oxyntic cells (X/A-like cells) of the stomach and fundus and can exist in two forms: as an acylated and des-acylated ghrelin. Ghrelin is an endogenous ligand of the growth hormone receptor (growth hormone secretagogue receptor, GHS-R). Overexpression of GHS-R1a receptor was identified in cells of different types of tumors (e.g. pituitary adenoma, neuroendocrine tumors of the thyroid, lung, breast, gonads, prostate, stomach, colorectal, endocrine and non-endocrine pancreatic tumors). This fact suggests that gamma radionuclide labeled ghrelin peptide may be considered as a potential diagnostic radiopharmaceutical. METHODS Ghrelin peptide labeled with mono- and trivalent technetium-99m complexes, (99m)Tc-Lys-GHR, has been prepared on the n.c.a. scale. The physicochemical (stability, charge, shape, lipophilicity) and biological (receptor affinity, biodistribution) properties of the conjugates have been studied relevant to use the conjugates as receptor-based diagnostic radiopharmaceuticals. RESULTS The obtained conjugates [(99m)Tc(CO)3LN,O(CN-Lys-GHR)](+), (99m)Tc(CO)3LS,O(CN-Lys-GHR) and (99m)Tc(NS3)(CN-Lys-GHR) show different shape, charge, lipophilicity and two of them, (99m)Tc(CO)3LS,O(CN-Lys-GHR) and (99m)Tc(NS3)(CN-Lys-GHR), high stability in neutral aqueous solutions, even in the presence of excess concentration of histidine/cysteine competitive standard ligands or human serum. The in vitro binding affinity of (99m)Tc-Lys-GHR conjugates with respect to growth hormone secretagogue receptor (GHS-R1a) present on DU-145 cells was in the range of IC50 from 45 to 54 nM. The conjugate (99m)Tc(CO)3LS,O(CN-Lys-GHR) exhibited excretion route by the liver and kidney in comparable degree, while the more lipophilic conjugate (99m)Tc(NS3)(CN-Lys-GHR)-mainly by the liver. CONCLUSIONS Basing on the results concerning physicochemical and biochemical properties, the conjugates (99m)Tc(CO)3LS,O(CN-Lys-GHR) and (99m)Tc(NS3)(CN-Lys-GHR) might be considered to be promising models for diagnostic radiopharmaceutical.
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Callaghan B, Furness JB. Novel and Conventional Receptors for Ghrelin, Desacyl-Ghrelin, and Pharmacologically Related Compounds. Pharmacol Rev 2014; 66:984-1001. [DOI: 10.1124/pr.113.008433] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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Holubová M, Nagelová V, Lacinová Z, Haluzík M, Sýkora D, Moulin A, Blayo AL, Fehrentz JA, Martinez J, Stofkova A, Jurčovičová J, Zelezná B, Maletínská L. Triazole GHS-R1a antagonists JMV4208 and JMV3002 attenuate food intake, body weight, and adipose tissue mass in mice. Mol Cell Endocrinol 2014; 393:120-8. [PMID: 24953973 DOI: 10.1016/j.mce.2014.06.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 05/19/2014] [Accepted: 06/05/2014] [Indexed: 12/29/2022]
Abstract
The only peripherally released orexigenic hormone, ghrelin, plays a key role in food intake and body weight regulation. Antagonizing the ghrelin receptor, GHS-R1a, represents a promising approach for anti-obesity therapy. In our study, two novel GHS-R1a antagonists JMV4208 and JMV3002, which are trisubstituted 1,2,4-triazoles, decreased food intake in fasted lean mice in a dose-dependent manner, with ED50 values of 5.25 and 2.05 mg/kg, respectively. Both compounds were stable in mouse blood, with half-lives of 90 min (JMV4208) and 60 min (JMV3002), and disappeared from the blood 8h after administration. Fourteen days of treatment with the ghrelin antagonists (20 mg/kg twice a day) decreased food intake, body weight and adipose tissue mass in mice with diet-induced obesity (DIO). These results are likely attributable to an impact on food intake reduction and an attenuated expression of the lipogenesis-promoting enzymes (acetyl-CoA carboxylase 1 in subcutaneous fat and fatty acid synthase in subcutaneous and intraperitoneal fat). The decrease in fat mass negatively impacted circulating leptin levels. These data suggest that JMV4208 and JMV3002 could be useful therapeutic agents for the treatment of obesity.
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Affiliation(s)
- M Holubová
- Institute of Organic Chemistry and Biochemistry, AS CR, Prague, Czech Republic; Third Department of Medicine, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic
| | - V Nagelová
- Institute of Organic Chemistry and Biochemistry, AS CR, Prague, Czech Republic
| | - Z Lacinová
- Third Department of Medicine, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic
| | - M Haluzík
- Third Department of Medicine, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic
| | - D Sýkora
- Institute of Chemical Technology, Department of Analytical Chemistry, Prague, Czech Republic
| | - A Moulin
- IBMM UMR 5274, CNRS - Universités Montpellier 1- Montpellier 2, Faculté de Pharmacie, Montpellier, France
| | - A L Blayo
- IBMM UMR 5274, CNRS - Universités Montpellier 1- Montpellier 2, Faculté de Pharmacie, Montpellier, France
| | - J A Fehrentz
- IBMM UMR 5274, CNRS - Universités Montpellier 1- Montpellier 2, Faculté de Pharmacie, Montpellier, France
| | - J Martinez
- IBMM UMR 5274, CNRS - Universités Montpellier 1- Montpellier 2, Faculté de Pharmacie, Montpellier, France
| | - A Stofkova
- Department of Normal, Pathological and Clinical Physiology, Third Faculty of Medicine, Charles University, Prague, Czech Republic
| | - J Jurčovičová
- Department of Normal, Pathological and Clinical Physiology, Third Faculty of Medicine, Charles University, Prague, Czech Republic
| | - B Zelezná
- Institute of Organic Chemistry and Biochemistry, AS CR, Prague, Czech Republic
| | - L Maletínská
- Institute of Organic Chemistry and Biochemistry, AS CR, Prague, Czech Republic.
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McCoull W, Barton P, Brown AJH, Bowker SS, Cameron J, Clarke DS, Davies RDM, Dossetter AG, Ertan A, Fenwick M, Green C, Holmes JL, Martin N, Masters D, Moore JE, Newcombe NJ, Newton C, Pointon H, Robb GR, Sheldon C, Stokes S, Morgan D. Identification, Optimization, and Pharmacology of Acylurea GHS-R1a Inverse Agonists. J Med Chem 2014; 57:6128-40. [DOI: 10.1021/jm500610n] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- William McCoull
- AstraZeneca, Mereside, Alderley Park, Macclesfield SK10 4TG, U.K
| | - Peter Barton
- AstraZeneca, Mereside, Alderley Park, Macclesfield SK10 4TG, U.K
| | | | | | - Jennifer Cameron
- AstraZeneca, Mereside, Alderley Park, Macclesfield SK10 4TG, U.K
| | - David S. Clarke
- AstraZeneca, Mereside, Alderley Park, Macclesfield SK10 4TG, U.K
| | | | | | - Anne Ertan
- AstraZeneca, Mereside, Alderley Park, Macclesfield SK10 4TG, U.K
| | - Mark Fenwick
- AstraZeneca, Mereside, Alderley Park, Macclesfield SK10 4TG, U.K
| | - Clive Green
- AstraZeneca, Mereside, Alderley Park, Macclesfield SK10 4TG, U.K
| | - Jane L. Holmes
- AstraZeneca, Mereside, Alderley Park, Macclesfield SK10 4TG, U.K
| | - Nathaniel Martin
- AstraZeneca, Mereside, Alderley Park, Macclesfield SK10 4TG, U.K
| | - David Masters
- AstraZeneca, Mereside, Alderley Park, Macclesfield SK10 4TG, U.K
| | - Jane E. Moore
- AstraZeneca, Mereside, Alderley Park, Macclesfield SK10 4TG, U.K
| | | | - Claire Newton
- AstraZeneca, Mereside, Alderley Park, Macclesfield SK10 4TG, U.K
| | - Helen Pointon
- AstraZeneca, Mereside, Alderley Park, Macclesfield SK10 4TG, U.K
| | - Graeme R. Robb
- AstraZeneca, Mereside, Alderley Park, Macclesfield SK10 4TG, U.K
| | | | - Stephen Stokes
- AstraZeneca, Mereside, Alderley Park, Macclesfield SK10 4TG, U.K
| | - David Morgan
- AstraZeneca, Mereside, Alderley Park, Macclesfield SK10 4TG, U.K
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Abstract
The prevalence of obesity continues to increase and has reached epidemic proportions. Accumulating data over the past few decades have given us key insights and broadened our understanding of the peripheral and central regulation of energy homeostasis. Despite this, the currently available pharmacological treatments, reducing body weight, remain limited due to poor efficacy and side effects. The gastric peptide ghrelin has been identified as the only orexigenic hormone from the periphery to act in the hypothalamus to stimulate food intake. Recently, a role for ghrelin and its receptor at the interface between homeostatic control of appetite and reward circuitries modulating the hedonic aspects of food has also emerged. Nonhomeostatic factors such as the rewarding and motivational value of food, which increase with food palatability and caloric content, can override homeostatic control of food intake. This nonhomeostatic decision to eat leads to overconsumption beyond nutritional needs and is being recognized as a key component in the underlying causes for the increase in obesity incidence worldwide. In addition, the hedonic feeding behavior has been linked to food addiction and an important role for ghrelin in the development of addiction has been suggested. Moreover, plasma ghrelin levels are responsive to conditions of stress, and recent evidence has implicated ghrelin in stress-induced food-reward behavior. The prominent role of the ghrelinergic system in the regulation of feeding gives rise to it as an effective target for the development of successful antiobesity pharmacotherapies that not only affect satiety but also selectively modulate the rewarding properties of food and reduce the desire to eat.
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Delporte C. Structure and physiological actions of ghrelin. SCIENTIFICA 2013; 2013:518909. [PMID: 24381790 PMCID: PMC3863518 DOI: 10.1155/2013/518909] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 11/10/2013] [Indexed: 05/30/2023]
Abstract
Ghrelin is a gastric peptide hormone, discovered as being the endogenous ligand of growth hormone secretagogue receptor. Ghrelin is a 28 amino acid peptide presenting a unique n-octanoylation modification on its serine in position 3, catalyzed by ghrelin O-acyl transferase. Ghrelin is mainly produced by a subset of stomach cells and also by the hypothalamus, the pituitary, and other tissues. Transcriptional, translational, and posttranslational processes generate ghrelin and ghrelin-related peptides. Homo- and heterodimers of growth hormone secretagogue receptor, and as yet unidentified receptors, are assumed to mediate the biological effects of acyl ghrelin and desacyl ghrelin, respectively. Ghrelin exerts wide physiological actions throughout the body, including growth hormone secretion, appetite and food intake, gastric secretion and gastrointestinal motility, glucose homeostasis, cardiovascular functions, anti-inflammatory functions, reproductive functions, and bone formation. This review focuses on presenting the current understanding of ghrelin and growth hormone secretagogue receptor biology, as well as the main physiological effects of ghrelin.
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Affiliation(s)
- Christine Delporte
- Laboratory of Pathophysiological and Nutritional Biochemistry, Université Libre de Bruxelles, 808 Route de Lennik, Bat G/E-CP611, 1070 Brussels, Belgium
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Wellman PJ, Clifford PS, Rodriguez JA. Ghrelin and ghrelin receptor modulation of psychostimulant action. Front Neurosci 2013; 7:171. [PMID: 24093007 PMCID: PMC3782693 DOI: 10.3389/fnins.2013.00171] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 09/02/2013] [Indexed: 12/03/2022] Open
Abstract
Ghrelin (GHR) is an orexigenic gut peptide that modulates multiple homeostatic functions including gastric emptying, anxiety, stress, memory, feeding, and reinforcement. GHR is known to bind and activate growth-hormone secretagogue receptors (termed GHR-Rs). Of interest to our laboratory has been the assessment of the impact of GHR modulation of the locomotor activation and reward/reinforcement properties of psychostimulants such as cocaine and nicotine. Systemic GHR infusions augment cocaine stimulated locomotion and conditioned place preference (CPP) in rats, as does food restriction (FR) which elevates plasma ghrelin levels. Ghrelin enhancement of psychostimulant function may occur owing to a direct action on mesolimbic dopamine function or may reflect an indirect action of ghrelin on glucocorticoid pathways. Genomic or pharmacological ablation of GHR-Rs attenuates the acute locomotor-enhancing effects of nicotine, cocaine, amphetamine and alcohol and blunts the CPP induced by food, alcohol, amphetamine and cocaine in mice. The stimulant nicotine can induce CPP and like amphetamine and cocaine, repeated administration of nicotine induces locomotor sensitization in rats. Inactivation of ghrelin circuit function in rats by injection of a ghrelin receptor antagonist (e.g., JMV 2959) diminishes the development of nicotine-induced locomotor sensitization. These results suggest a key permissive role for GHR-R activity for the induction of locomotor sensitization to nicotine. Our finding that GHR-R null rats exhibit diminished patterns of responding for intracranial self-stimulation complements an emerging literature implicating central GHR circuits in drug reward/reinforcement. Finally, antagonism of GHR-Rs may represent a smoking cessation modality that not only blocks nicotine-induced reward but that also may limit weight gain after smoking cessation.
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Affiliation(s)
- Paul J Wellman
- Behavioral Neuroscience Program, Department of Psychology, Texas A&M University College Station, TX, USA
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Schellekens H, Dinan TG, Cryan JF. Taking two to tango: a role for ghrelin receptor heterodimerization in stress and reward. Front Neurosci 2013; 7:148. [PMID: 24009547 PMCID: PMC3757321 DOI: 10.3389/fnins.2013.00148] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 08/01/2013] [Indexed: 12/25/2022] Open
Abstract
The gut hormone, ghrelin, is the only known peripherally derived orexigenic signal. It activates its centrally expressed receptor, the growth hormone secretagogue receptor (GHS-R1a), to stimulate food intake. The ghrelin signaling system has recently been suggested to play a key role at the interface of homeostatic control of appetite and the hedonic aspects of food intake, as a critical role for ghrelin in dopaminergic mesolimbic circuits involved in reward signaling has emerged. Moreover, enhanced plasma ghrelin levels are associated with conditions of physiological stress, which may underline the drive to eat calorie-dense "comfort-foods" and signifies a role for ghrelin in stress-induced food reward behaviors. These complex and diverse functionalities of the ghrelinergic system are not yet fully elucidated and likely involve crosstalk with additional signaling systems. Interestingly, accumulating data over the last few years has shown the GHS-R1a receptor to dimerize with several additional G-protein coupled receptors (GPCRs) involved in appetite signaling and reward, including the GHS-R1b receptor, the melanocortin 3 receptor (MC3), dopamine receptors (D1 and D2), and more recently, the serotonin 2C receptor (5-HT2C). GHS-R1a dimerization was shown to affect downstream signaling and receptor trafficking suggesting a potential novel mechanism for fine-tuning GHS-R1a receptor mediated activity. This review summarizes ghrelin's role in food reward and stress and outlines the GHS-R1a dimer pairs identified to date. In addition, the downstream signaling and potential functional consequences of dimerization of the GHS-R1a receptor in appetite and stress-induced food reward behavior are discussed. The existence of multiple GHS-R1a heterodimers has important consequences for future pharmacotherapies as it significantly increases the pharmacological diversity of the GHS-R1a receptor and has the potential to enhance specificity of novel ghrelin-targeted drugs.
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The expression of GHS-R in primary neurons is dependent upon maturation stage and regional localization. PLoS One 2013; 8:e64183. [PMID: 23755116 PMCID: PMC3673981 DOI: 10.1371/journal.pone.0064183] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 04/12/2013] [Indexed: 01/03/2023] Open
Abstract
Ghrelin is a hormone with a crucial role in the regulation of appetite, regulation of inflammation, glucose metabolism and cell proliferation. In the brain ghrelin neurons are located in the cortex (sensorimotor area, cingular gyrus), and the fibres of ghrelin neurons in hypothalamus project directly to the dorsal vagal complex (DVC). Ghrelin binds the growth hormone secretagogue receptor (GHS-R) a G-protein-coupled receptor with a widespread tissue distribution, indeed these receptors are localized both in nonnervous, organs/tissues (i.e. adipose tissue, myocardium, adrenals, gonads, lung, liver, arteries, stomach, pancreas, thyroid, and kidney) as well as in central nervous system (CNS) and higher levels of expression in the pituitary gland and the hypothalamus and lower levels of expression in other organs, including brain. A GHS-R specific monoclonal antibody has been developed and characterized and through it we demonstrate that GHS-R is expressed in primary neurons and that its expression is dependent upon their developmental stage and shows differences according to the brain region involved, with a more pronounced expression in hippocampal rather than cortical neurons. A characterization of GHS-R within the central nervous system is of extreme importance in order to gain insights on its role in the modulation of neurodegenerative events such as Alzheimer’s disease.
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McCoull W, Barton P, Broo A, Brown AJH, Clarke DS, Coope G, Davies RDM, Dossetter AG, Kelly EE, Knerr L, MacFaul P, Holmes JL, Martin N, Moore JE, Morgan D, Newton C, Österlund K, Robb GR, Rosevere E, Selmi N, Stokes S, Svensson TS, Ullah VBK, Williams EJ. Identification of pyrazolo-pyrimidinones as GHS-R1a antagonists and inverse agonists for the treatment of obesity. MEDCHEMCOMM 2013. [DOI: 10.1039/c2md20340e] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Schellekens H, McNamara O, Dinan TG, McCarthy JV, McGlacken GP, Cryan JF. Semagacestat, a γ-secretase inhibitor, activates the growth hormone secretagogue (GHS-R1a) receptor. J Pharm Pharmacol 2012; 65:528-38. [PMID: 23488781 DOI: 10.1111/jphp.12010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 10/18/2012] [Indexed: 12/14/2022]
Abstract
OBJECTIVES Semagacestat, is a γ-secretase inhibitor, which belongs to a class of drugs that are being developed as therapeutic agents for Alzheimer's disease (AD). This study aims to evaluate another potential effect of semagacestat, namely its ability to stimulate the growth hormone secretagogue receptor (GHS-R1a), which may also contribute to its therapeutic efficacy. METHODS The GHS-R1a-activating potential of semagacestat and its synthetic precursor was assessed in an in vitro calcium mobilization assay in cells expressing the GHS-R1a receptor and compared with that of the endogenous peptide GHS-R1a agonist, acyl-ghrelin, as well as the non-peptidyl synthetic GHS-R1a agonist, MK0677. In addition, semagacestat-mediated cellular trafficking of the GHS-R1a receptor, expressed as an enhanced green fluorescent protein tagged fusion protein, was analysed. KEY FINDINGS Semagacestat and its precursor were shown to activate the GHS-R1a receptor, as demonstrated by an increased GHS-R1a-mediated intracellular calcium influx. Moreover, a synergistic GHS-R1a receptor activation was shown following a combined exposure to ghrelin and semagacestat. In addition, GHS-R1a receptor internalization was observed upon exposure to semagacestat and its precursor. CONCLUSION These data suggest a novel molecular mechanism of action for semagacestat via modest GHS-R1a receptor activation. Studies focusing on the relative functional consequence of such effects in vivo are now warranted.
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Affiliation(s)
- Harriët Schellekens
- Food for Health Ireland and School of Pharmacy, University College Cork, Cork, Ireland
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Schellekens H, van Oeffelen WEPA, Dinan TG, Cryan JF. Promiscuous dimerization of the growth hormone secretagogue receptor (GHS-R1a) attenuates ghrelin-mediated signaling. J Biol Chem 2012; 288:181-91. [PMID: 23161547 DOI: 10.1074/jbc.m112.382473] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
G protein-coupled receptors (GPCRs), such as the ghrelin receptor (GHS-R1a), the melanocortin 3 receptor (MC(3)), and the serotonin 2C receptor (5-HT(2C)), are well known for their key role in the homeostatic control of food intake and energy balance. Ghrelin is the only known gut peptide exerting an orexigenic effect and has thus received much attention as an anti-obesity drug target. In addition, recent data have revealed a critical role for ghrelin in dopaminergic mesolimbic circuits involved in food reward signaling. This study investigates the downstream signaling consequences and ligand-mediated co-internalization following heterodimerization of the GHS-R1a receptor with the dopamine 1 receptor, as well as that of the GHS-R1a-MC(3) heterodimer. In addition, a novel heterodimer between the GHS-R1a receptor and the 5-HT(2C) receptor was identified. Interestingly, dimerization of the GHS-R1a receptor with the unedited 5-HT(2C)-INI receptor, but not with the partially edited 5-HT(2C)-VSV isoform, significantly reduced GHS-R1a agonist-mediated calcium influx, which was completely restored following pharmacological blockade of the 5-HT(2C) receptor. These results combined suggest a potential novel mechanism for fine-tuning GHS-R1a receptor-mediated activity via promiscuous dimerization of the GHS-R1a receptor with other G protein-coupled receptors involved in appetite regulation and food reward. These findings may uncover novel mechanisms of significant relevance for the future pharmacological targeting of the GHS-R1a receptor in the homeostatic regulation of energy balance and in hedonic appetite signaling, both of which play a significant role in the development of obesity.
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Els S, Schild E, Petersen PS, Kilian TM, Mokrosinski J, Frimurer TM, Chollet C, Schwartz TW, Holst B, Beck-Sickinger AG. An aromatic region to induce a switch between agonism and inverse agonism at the ghrelin receptor. J Med Chem 2012; 55:7437-49. [PMID: 22920150 DOI: 10.1021/jm300414b] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The ghrelin receptor displays a high constitutive activity suggested to be involved in the regulation of appetite and food intake. Here, we have created peptides with small changes in the core binding motif -wFw- of the hexapeptide KwFwLL-NH(2) that can swap the peptide behavior from inverse agonism to agonism, indicating the importance of this sequence. Introduction of β-(3-benzothienyl)-d-alanine (d-Bth), 3,3-diphenyl-d-alanine (d-Dip) and 1-naphthyl-d-alanine (d-1-Nal) at position 2 resulted in highly potent and efficient inverse agonists, whereas the substitution of d-tryptophane at position 4 with 1-naphthyl-d-alanine (d-1-Nal) and 2-naphthyl-d-alanine (d-2-Nal) induces agonism in functional assays. Competitive binding studies showed a high affinity of the inverse agonist K-(d-1-Nal)-FwLL-NH(2) at the ghrelin receptor. Moreover, mutagenesis studies of the receptor revealed key positions for the switch between inverse agonist and agonist response. Hence, only minor changes in the peptide sequence can decide between agonism and inverse agonism and have a major impact on the biological activity.
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Affiliation(s)
- Sylvia Els
- Institute of Biochemistry, Universität Leipzig, Brüderstraße 34, 04103 Leipzig, Germany
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Abstract
The main benefit of natural peptides, peptide analogs and newly designed peptides as therapeutics, lies in their high selectivity and affinity, which are frequently in the nanomolar range. New drugs targeting protein–protein interactions often require larger interaction sites than small molecules can offer. Thus, many peptidic drugs are already applied in therapy at the current state. The next generation of peptide-based therapeutic agents is currently on its way from basic research to clinical studies and eventually to the pharmaceutical market. Development of more robust and long-lasting drugs owing to well-known and new stabilization strategies is yielding novel and continuously improving peptide drugs. The introduction of smart linkers that exhibit stability towards blood plasma but intracellular lability will lead to target-oriented activity, which might successfully decrease side effects. In this review, peptidic therapeutics on the market, in clinical studies and some of those in basic research are characterized. Stabilization strategies and intelligent linkers are discussed with respect to their use in peptide drug therapy.
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Cardona Cano S, Merkestein M, Skibicka KP, Dickson SL, Adan RAH. Role of ghrelin in the pathophysiology of eating disorders: implications for pharmacotherapy. CNS Drugs 2012; 26:281-96. [PMID: 22452525 DOI: 10.2165/11599890-000000000-00000] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Ghrelin is the only known circulating orexigenic hormone. It increases food intake by interacting with hypothalamic and brainstem circuits involved in energy balance, as well as reward-related brain areas. A heightened gut-brain ghrelin axis is an emerging feature of certain eating disorders such as anorexia nervosa and Prader-Willi syndrome. In common obesity, ghrelin levels are lowered, whereas post-meal ghrelin levels remain higher than in lean individuals. Agents that interfere with ghrelin signalling have therapeutic potential for eating disorders, including obesity. However, most of these drugs are only in the preclinical phase of development. Data obtained so far suggest that ghrelin agonists may have potential in the treatment of anorexia nervosa, while ghrelin antagonists seem promising for other eating disorders such as obesity and Prader-Willi syndrome. However, large clinical trials are needed to evaluate the efficacy and safety of these drugs.
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Chollet C, Bergmann R, Pietzsch J, Beck-Sickinger AG. Design, Evaluation, and Comparison of Ghrelin Receptor Agonists and Inverse Agonists as Suitable Radiotracers for PET Imaging. Bioconjug Chem 2012; 23:771-84. [DOI: 10.1021/bc2005889] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
| | - Ralf Bergmann
- Institute of Radiopharmacy, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
| | - Jens Pietzsch
- Institute of Radiopharmacy, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
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McGirr R, McFarland MS, McTavish J, Luyt LG, Dhanvantari S. Design and characterization of a fluorescent ghrelin analog for imaging the growth hormone secretagogue receptor 1a. ACTA ACUST UNITED AC 2011; 172:69-76. [DOI: 10.1016/j.regpep.2011.08.011] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Revised: 08/17/2011] [Accepted: 08/23/2011] [Indexed: 01/11/2023]
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Rediger A, Piechowski CL, Yi CX, Tarnow P, Strotmann R, Grüters A, Krude H, Schöneberg T, Tschöp MH, Kleinau G, Biebermann H. Mutually opposite signal modulation by hypothalamic heterodimerization of ghrelin and melanocortin-3 receptors. J Biol Chem 2011; 286:39623-31. [PMID: 21940628 PMCID: PMC3234785 DOI: 10.1074/jbc.m111.287607] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 09/03/2011] [Indexed: 12/22/2022] Open
Abstract
Interaction and cross-talk of G-protein-coupled receptors (GPCRs) are of considerable interest because an increasing number of examples implicate a profound functional and physiological relevance of homo- or hetero-oligomeric GPCRs. The ghrelin (growth hormone secretagogue receptor (GHSR)) and melanocortin-3 (MC3R) receptors are both known to have orexigenic effects on the hypothalamic control of body weight. Because in vitro studies indicate heterodimerization of GHSR and MC3R, we investigated their functional interplay. Combined in situ hybridization and immunohistochemistry indicated that the vast majority of GHSR-expressing neurons in the arcuate nucleus also express MC3R. In vitro coexpression of MC3R and GHSR promoted enhanced melanocortin-induced intracellular cAMP accumulation compared with activation of MC3R in the absence of GHSR. In contrast, agonist-independent basal signaling activity and ghrelin-induced signaling of GHSR were impaired, most likely due to interaction with MC3R. By taking advantage of naturally occurring GHSR mutations and an inverse agonist for GHSR, we demonstrate that the observed enhanced MC3R signaling capability depends directly on the basal activity of GHSR. In conclusion, we demonstrate a paradigm-shifting example of GPCR heterodimerization allowing for mutually opposite functional influence of two hypothalamic receptors controlling body weight. We found that the agonist-independent active conformation of one GPCR can determine the signaling modalities of another receptor in a heterodimer. Our discovery also implies that mutations within one of two interacting receptors might affect both receptors and different pathways simultaneously. These findings uncover mechanisms of important relevance for pharmacological targeting of GPCR in general and hypothalamic body weight regulation in particular.
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MESH Headings
- Animals
- Arcuate Nucleus of Hypothalamus/metabolism
- COS Cells
- Chlorocebus aethiops
- Cyclic AMP/genetics
- Cyclic AMP/metabolism
- Gene Expression Regulation/physiology
- Ghrelin/genetics
- Ghrelin/metabolism
- HEK293 Cells
- Humans
- Mice
- Mice, Knockout
- Mutation
- Nerve Tissue Proteins/agonists
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Neurons/metabolism
- Protein Multimerization/physiology
- Receptor, Melanocortin, Type 3/agonists
- Receptor, Melanocortin, Type 3/genetics
- Receptor, Melanocortin, Type 3/metabolism
- Receptors, Ghrelin/agonists
- Receptors, Ghrelin/genetics
- Receptors, Ghrelin/metabolism
- Signal Transduction/physiology
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Affiliation(s)
- Anne Rediger
- From the Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Carolin L. Piechowski
- From the Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Chun-Xia Yi
- the Metabolic Diseases Institute, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio 45267, and
| | - Patrick Tarnow
- From the Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Rainer Strotmann
- the Institute of Biochemistry, Medical Faculty, University of Leipzig, 04103 Leipzig, Germany
| | - Annette Grüters
- From the Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Heiko Krude
- From the Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Torsten Schöneberg
- the Institute of Biochemistry, Medical Faculty, University of Leipzig, 04103 Leipzig, Germany
| | - Matthias H. Tschöp
- the Metabolic Diseases Institute, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio 45267, and
| | - Gunnar Kleinau
- From the Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Heike Biebermann
- From the Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
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31
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Satou M, Nakamura Y, Ando H, Sugimoto H. Understanding the functional significance of ghrelin processing and degradation. Peptides 2011; 32:2183-90. [PMID: 21763742 DOI: 10.1016/j.peptides.2011.06.029] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Revised: 06/08/2011] [Accepted: 06/30/2011] [Indexed: 10/18/2022]
Abstract
Post-translational modification, cleavage and processing of circulating hormones are common themes in the control of hormone activities. Full-length ghrelin is a 28 amino acid protein that exists in several modified and processed forms, including addition of an acyl moiety at the third serine of the N-terminus. When modified with octanoic acid, the first five N-terminal residues of ghrelin can modulate a signaling pathway via the ghrelin receptor GHSR1a. Although modification via a lipid moiety is essential for binding and activation of GHSR1a by ghrelin, many reports suggest that a desacyl form of ghrelin exists and has synergistic, opposing and distinct properties as compared to the acyl form. Therefore, it is important to clarify the physiological relevance of ghrelin derivatives. Based on lines of evidence from various studies, we propose that a larger proportion of secreted ghrelin is present in the deacylated form and furthermore, that circulating acyl and desacyl forms of ghrelin may be hydrolyzed to form short peptide fragments. Here, we summarize the results of studies aimed at understanding ghrelin processing and its implications for physiological function, as well as our recent findings regarding enzymes in the blood capable of generating processed forms of ghrelin.
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Affiliation(s)
- Motoyasu Satou
- Departments of Biochemistry, Dokkyo Medical University School of Medicine, 880 Kitakobayashi, Mibu, Tochigi 321-0293, Japan
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32
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Gahete MD, Córdoba-Chacón J, Kineman RD, Luque RM, Castaño JP. Role of ghrelin system in neuroprotection and cognitive functions: implications in Alzheimer's disease. Peptides 2011; 32:2225-8. [PMID: 21983104 PMCID: PMC3228413 DOI: 10.1016/j.peptides.2011.09.019] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2011] [Revised: 07/27/2011] [Accepted: 09/26/2011] [Indexed: 12/11/2022]
Abstract
Alzheimer's disease (AD) is a multifactorial progressive neurodegenerative disorder characterized by loss of memory and cognitive deficits, strongly influenced by the metabolic status, in which the impairment of neuropeptides/neurotransmitters systems has been previously observed. Ghrelin is a multifunctional hormone produced in a wide variety of tissues, which has been associated with the progression of obesity and metabolic syndrome, but has been also linked to neuromodulation, neuroprotection and memory and learning processes. In addition, ghrelin system also acts in an autocrine/paracrine fashion where the majority of its components [ghrelin variants (native ghrelin, In1-ghrelin), acylation enzyme (GOAT) and receptors (GHS-Rs)] are expressed in the different regions of central nervous system. In spite of all these pieces of information strongly suggesting a close association between ghrelin system and AD, which could be of pathophysiological relevance, few studies have been addressed to clarify this relationship. In this work, the role of ghrelin system in neuroprotection, memory consolidation and learning is reviewed, and its influence in AD, as well as the regulation of its expression in the brain of AD patients, is discussed.
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Affiliation(s)
- Manuel D. Gahete
- Department of Cell Biology, Physiology and Immunology, University of Córdoba, Hospital Universitario Reina Sofía, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), and CIBER Fisiopatología de la Obesidad y Nutrición, Córdoba, Spain
- Section of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Illinois at Chicago, IL, USA
- Research and Development Division, Jesse Brown Veterans Affairs Medical Center, Chicago, IL, USA
| | - José Córdoba-Chacón
- Department of Cell Biology, Physiology and Immunology, University of Córdoba, Hospital Universitario Reina Sofía, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), and CIBER Fisiopatología de la Obesidad y Nutrición, Córdoba, Spain
- Section of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Illinois at Chicago, IL, USA
| | - Rhonda D. Kineman
- Section of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Illinois at Chicago, IL, USA
- Research and Development Division, Jesse Brown Veterans Affairs Medical Center, Chicago, IL, USA
| | - Raúl M. Luque
- Department of Cell Biology, Physiology and Immunology, University of Córdoba, Hospital Universitario Reina Sofía, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), and CIBER Fisiopatología de la Obesidad y Nutrición, Córdoba, Spain
| | - Justo P. Castaño
- Department of Cell Biology, Physiology and Immunology, University of Córdoba, Hospital Universitario Reina Sofía, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), and CIBER Fisiopatología de la Obesidad y Nutrición, Córdoba, Spain
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33
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Nishi Y, Yoh J, Hiejima H, Kojima M. Structures and molecular forms of the ghrelin-family peptides. Peptides 2011; 32:2175-82. [PMID: 21839128 DOI: 10.1016/j.peptides.2011.07.024] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2011] [Revised: 07/08/2011] [Accepted: 07/22/2011] [Indexed: 11/23/2022]
Abstract
Ghrelin is an acylated peptide hormone produced mainly from the stomach. The major active products of the ghrelin gene in the stomach of rats, mice and humans are 28-amino acid peptides acylated at the serine-3 position with an n-octanoyl group (C8:0), called simply ghrelin. However, recent studies have revealed that the ghrelin gene can generate a variety of bioactive molecules besides ghrelin. These include acyl forms of ghrelin other than C8:0-ghrelin (i.e., n-decanoyl ghrelin or n-decenoyl ghrelin), des-acyl ghrelin, obestatin and ghrelin-associated peptides originated from the ghrelin gene. This review surveys the structures of the ghrelin peptides and molecular forms of ghrelin gene-derived products, and summarizes the knowledge about the functions of these peptides, with an emphasis on the acyl forms of the ghrelin peptide.
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Affiliation(s)
- Yoshihiro Nishi
- Department of Physiology, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka 830-0011, Japan.
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34
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Maletínská L, Matyšková R, Maixnerová J, Sýkora D, Pýchová M, Spolcová A, Blechová M, Drápalová J, Lacinová Z, Haluzík M, Zelezná B. The Peptidic GHS-R antagonist [D-Lys(3)]GHRP-6 markedly improves adiposity and related metabolic abnormalities in a mouse model of postmenopausal obesity. Mol Cell Endocrinol 2011; 343:55-62. [PMID: 21704671 DOI: 10.1016/j.mce.2011.06.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Revised: 06/09/2011] [Accepted: 06/09/2011] [Indexed: 10/18/2022]
Abstract
It was demonstrated that estrogen deficiency and consuming high fat (HF) diet enhanced orexigenic activity of ghrelin. Therefore, we hypothesized that antagonizing of ghrelin action would attenuate food intake and body weight in mice obese both from ovariectomy (OVX) and feeding a HF diet. Ghrelin receptor antagonist [D-Lys(3)]GHRP-6 after seven days of subcutaneous treatment markedly decreased food intake in OVX mice fed both HF and standard diets; furthermore, it reduced body weight and blood glucose, insulin and leptin, and increased β-hydroxybutyrate level and uncoupling-protein-1 mRNA in brown adipose tissue. Pair-feeding revealed that effect of [D-Lys(3)]GHRP-6 was primary anorexigenic. Estrogen supplementation reduced anorexigenic effects of [D-Lys(3)]GHRP-6. OVX [D-Lys(3)]GHRP-6 treatment in mice on HF diet resulted in markedly increased circulating level and liver expression of a major metabolic regulator, fibroblast growth factor 21. Our data suggest that ghrelin antagonists could be especially beneficial in individuals with common obesity combined with estrogen deficiency.
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Affiliation(s)
- L Maletínská
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
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35
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Sabbatini FM, Melotto S, Bernasconi G, Bromidge SM, D'Adamo L, Rinaldi M, Savoia C, Mundi C, Di Francesco C, Zonzini L, Costantini VJA, Perini B, Valerio E, Pozzan A, Perdonà E, Visentini F, Corsi M, Di Fabio R. Azabicyclo[3.1.0]hexane-1-carbohydrazides as Potent and Selective GHSR1a Ligands Presenting a Specific in vivo Behavior. ChemMedChem 2011; 6:1981-5. [DOI: 10.1002/cmdc.201100285] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Revised: 07/17/2011] [Indexed: 11/07/2022]
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36
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Abstract
Obesity is fast becoming the scourge of our time. It is one of the biggest causes of death and disease in the industrialized world, and affects as many as 32% of adults and 17% of children in the USA, considered one of the world's fattest nations. It can also cost countries billions of dollars per annum in direct and indirect care, latest estimates putting the USA bill for obesity-related costs at $147 billion in 2008. It is becoming clear that the pathophysiology of obesity is vastly more complicated than the simple equation of energy in minus energy out. A combination of genetics, sex, perinatal environment and life-style factors can influence diet and energy metabolism. In this regard, psychological stress can have significant long-term impact upon the propensity to gain and maintain weight. In this review, we will discuss the ability of psychological stress and ultimately glucocorticoids (GCs) to alter appetite regulation and metabolism. We will specifically focus on (i) GC regulation of appetite and adiposity, (ii) the apparent sexual dimorphism in stress effects on obesity and (iii) the ability of early life stress to programme obesity in the long term.
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Affiliation(s)
- Sarah J Spencer
- Department of Physiology, Faculty of Medicine, Monash UniversityMelbourne, Vic., Australia.
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37
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Potter R, Horti AG, Ravert HT, Holt DP, Finley P, Scheffel U, Dannals RF, Wahl RL. Synthesis and in vivo evaluation of (S)-6-(4-fluorophenoxy)-3-((1-[11C]methylpiperidin-3-yl)methyl)-2-o-tolylquinazolin-4(3H)-one, a potential PET tracer for growth hormone secretagogue receptor (GHSR). Bioorg Med Chem 2011; 19:2368-72. [PMID: 21388815 DOI: 10.1016/j.bmc.2011.02.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Revised: 02/04/2011] [Accepted: 02/11/2011] [Indexed: 10/18/2022]
Abstract
The peptide hormone ghrelin mediates through action on its receptor, the growth hormone secretagogue receptor (GHSR), and is known to play an important role in a variety of metabolic functions including appetite stimulation, weight gain, and suppression of insulin secretion. In light of the fact that obesity is one of the major health problems plaguing the modern society, the ghrelin signaling system continues to remain an important and attractive pharmacological target for the treatment of obesity. In vivo imaging of the GHSR could shed light on the mechanism by which ghrelin affects feeding behavior and thus offers a new therapeutic perspective for the development of effective treatments. Recently, a series of piperidine-substituted quinazolinone derivatives was reported to be selective and potent GHSR antagonists with high binding affinities. Described herein is the synthesis, in vitro, and in vivo evaluation of (S)-6-(4-fluorophenoxy)-3-((1-[(11)C]methylpiperidin-3-yl)methyl)-2-o-tolylquinazolin-4(3H)-one ([(11)C]1), a potential PET radioligand for imaging GHSR.
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Affiliation(s)
- Rachel Potter
- Division of Nuclear Medicine, Department of Radiology, The Johns Hopkins University School of Medicine, 600 North Wolfe Street, Baltimore, MD 21287-0816, USA
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38
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Current world literature. Curr Opin Endocrinol Diabetes Obes 2011; 18:83-98. [PMID: 21178692 DOI: 10.1097/med.0b013e3283432fa7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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39
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Els S, Beck-Sickinger AG, Chollet C. Ghrelin receptor: high constitutive activity and methods for developing inverse agonists. Methods Enzymol 2010; 485:103-21. [PMID: 21050913 DOI: 10.1016/b978-0-12-381296-4.00006-3] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The ghrelin receptor is a G protein-coupled receptor (GPCR) mainly distributed in the brain, and also expressed in peripheral tissues. Remarkably, the ghrelin receptor possesses a naturally high constitutive activity representing 50% of its maximal activity. Its endogenous ligand ghrelin is the only known orexigenic gastrointestinal peptide and plays a central role in the regulation of appetite, food intake, and energy homeostasis. Reducing the constitutive activity of the ghrelin receptor by inverse agonists is the strategy adopted by our group to develop anti-obesity drugs. Therefore, short peptides were synthesized and showed high inverse agonist potency toward the ghrelin receptor. This review describes the methods used to synthesize the peptides and to evaluate their biological activity. Peptide synthesis was performed on solid phase using a Fmoc/tBu-strategy. Peptide potency was measured with a signal transduction assay, the inositol trisphosphate turnover assay, adapted to a receptor expressing constitutive activity.
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Affiliation(s)
- Sylvia Els
- Institute of Biochemistry, Leipzig University, Brüderstrasse, Leipzig, Germany
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