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Gibbs M, Winnig M, Riva I, Dunlop N, Waller D, Klebansky B, Logan DW, Briddon SJ, Holliday ND, McGrane SJ. Bitter taste sensitivity in domestic dogs (Canis familiaris) and its relevance to bitter deterrents of ingestion. PLoS One 2022; 17:e0277607. [PMID: 36449493 PMCID: PMC9710775 DOI: 10.1371/journal.pone.0277607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 10/31/2022] [Indexed: 12/03/2022] Open
Abstract
As the most favoured animal companion of humans, dogs occupy a unique place in society. Understanding the senses of the dog can bring benefits to both the dogs themselves and their owners. In the case of bitter taste, research may provide useful information on sensitivity to, and acceptance of, diets containing bitter tasting materials. It may also help to protect dogs from the accidental ingestion of toxic substances, as in some instances bitter tasting additives are used as deterrents to ingestion. In this study we examined the receptive range of dog bitter taste receptors (Tas2rs). We found that orthologous dog and human receptors do not always share the same receptive ranges using in vitro assays. One bitter chemical often used as a deterrent, denatonium benzoate, is only moderately active against dTas2r4, and is almost completely inactive against other dog Tas2rs, including dTas2r10, a highly sensitive receptor in humans. We substituted amino acids to create chimeric dog-human versions of the Tas2r10 receptor and found the ECL2 region partly determined denatonium sensitivity. We further confirmed the reduced sensitivity of dogs to this compound in vivo. A concentration of 100μM (44.7ppm) denatonium benzoate was effective as a deterrent to dog ingestion in a two-bottle choice test indicating higher concentrations may increase efficacy for dogs. These data can inform the choice and concentration of bitter deterrents added to toxic substances to help reduce the occurrence of accidental dog poisonings.
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Affiliation(s)
- Matthew Gibbs
- Waltham Petcare Science Institute, Waltham on the Wolds, Melton Mowbray, Leicestershire, United Kingdom
- School of Life Sciences, The Medical School, Queen’s Medical Centre, University of Nottingham, Nottingham, United Kingdom
- * E-mail:
| | | | - Irene Riva
- AXXAM SpA, IMAX Discovery Unit, Bresso, Milan, Italy
| | - Nicola Dunlop
- Waltham Petcare Science Institute, Waltham on the Wolds, Melton Mowbray, Leicestershire, United Kingdom
| | - Daniel Waller
- Waltham Petcare Science Institute, Waltham on the Wolds, Melton Mowbray, Leicestershire, United Kingdom
| | | | - Darren W. Logan
- Waltham Petcare Science Institute, Waltham on the Wolds, Melton Mowbray, Leicestershire, United Kingdom
| | - Stephen J. Briddon
- School of Life Sciences, The Medical School, Queen’s Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Nicholas D. Holliday
- School of Life Sciences, The Medical School, Queen’s Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Scott J. McGrane
- Waltham Petcare Science Institute, Waltham on the Wolds, Melton Mowbray, Leicestershire, United Kingdom
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Schulze AS, Kleinau G, Krakowsky R, Rochmann D, Das R, Worth CL, Krumbholz P, Scheerer P, Stäubert C. Evolutionary analyses reveal immune cell receptor GPR84 as a conserved receptor for bacteria-derived molecules. iScience 2022; 25:105087. [PMID: 36164652 PMCID: PMC9508565 DOI: 10.1016/j.isci.2022.105087] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 07/26/2022] [Accepted: 08/31/2022] [Indexed: 10/31/2022] Open
Abstract
The G protein-coupled receptor 84 (GPR84) is found in immune cells and its expression is increased under inflammatory conditions. Activation of GPR84 by medium-chain fatty acids results in pro-inflammatory responses. Here, we screened available vertebrate genome data and found that GPR84 is present in vertebrates for more than 500 million years but absent in birds and a pseudogene in bats. Cloning and functional characterization of several mammalian GPR84 orthologs in combination with evolutionary and model-based structural analyses revealed evidence for positive selection of bear GPR84 orthologs. Naturally occurring human GPR84 variants are most frequent in Asian populations causing a loss of function. Further, we identified cis- and trans-2-decenoic acid, both known to mediate bacterial communication, as evolutionary highly conserved ligands. Our integrated set of approaches contributes to a comprehensive understanding of GPR84 in terms of evolutionary and structural aspects, highlighting GPR84 as a conserved immune cell receptor for bacteria-derived molecules.
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Affiliation(s)
- Amadeus Samuel Schulze
- Rudolf Schönheimer Institute of Biochemistry, Faculty of Medicine, Leipzig University, Johannisallee 30, 04103 Leipzig, Germany
| | - Gunnar Kleinau
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, Charitéplatz 1, 10117 Berlin, Germany
| | - Rosanna Krakowsky
- Rudolf Schönheimer Institute of Biochemistry, Faculty of Medicine, Leipzig University, Johannisallee 30, 04103 Leipzig, Germany
| | - David Rochmann
- Rudolf Schönheimer Institute of Biochemistry, Faculty of Medicine, Leipzig University, Johannisallee 30, 04103 Leipzig, Germany
| | - Ranajit Das
- Yenepoya Research Centre, Yenepoya University, Mangalore, Karnataka, India
| | - Catherine L Worth
- Independent Data Lab UG, Frauenmantelanger 31, 80937 Munich, Germany
| | - Petra Krumbholz
- Rudolf Schönheimer Institute of Biochemistry, Faculty of Medicine, Leipzig University, Johannisallee 30, 04103 Leipzig, Germany
| | - Patrick Scheerer
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, Charitéplatz 1, 10117 Berlin, Germany
| | - Claudia Stäubert
- Rudolf Schönheimer Institute of Biochemistry, Faculty of Medicine, Leipzig University, Johannisallee 30, 04103 Leipzig, Germany
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Philippe A, Kleinau G, Gruner JJ, Wu S, Postpieszala D, Speck D, Heidecke H, Dowell SJ, Riemekasten G, Hildebrand PW, Kamhieh-Milz J, Catar R, Szczepek M, Dragun D, Scheerer P. Molecular Effects of Auto-Antibodies on Angiotensin II Type 1 Receptor Signaling and Cell Proliferation. Int J Mol Sci 2022; 23:ijms23073984. [PMID: 35409344 PMCID: PMC8999261 DOI: 10.3390/ijms23073984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 03/30/2022] [Accepted: 03/30/2022] [Indexed: 11/16/2022] Open
Abstract
The angiotensin II (Ang II) type 1 receptor (AT1R) is involved in the regulation of blood pressure (through vasoconstriction) and water and ion homeostasis (mediated by interaction with the endogenous agonist). AT1R can also be activated by auto-antibodies (AT1R-Abs), which are associated with manifold diseases, such as obliterative vasculopathy, preeclampsia and systemic sclerosis. Knowledge of the molecular mechanisms related to AT1R-Abs binding and associated signaling cascade (dys-)regulation remains fragmentary. The goal of this study was, therefore, to investigate details of the effects of AT1R-Abs on G-protein signaling and subsequent cell proliferation, as well as the putative contribution of the three extracellular receptor loops (ELs) to Abs-AT1R signaling. AT1R-Abs induced nuclear factor of activated T-cells (NFAT) signaling, which reflects Gq/11 and Gi activation. The impact on cell proliferation was tested in different cell systems, as well as activation-triggered receptor internalization. Blockwise alanine substitutions were designed to potentially investigate the role of ELs in AT1R-Abs-mediated effects. First, we demonstrate that Ang II-mediated internalization of AT1R is impeded by binding of AT1R-Abs. Secondly, exclusive AT1R-Abs-induced Gq/11 activation is most significant for NFAT stimulation and mediates cell proliferation. Interestingly, our studies also reveal that ligand-independent, baseline AT1R activation of Gi signaling has, in turn, a negative effect on cell proliferation. Indeed, inhibition of Gi basal activity potentiates proliferation triggered by AT1R-Abs. Finally, although AT1R containing EL1 and EL3 blockwise alanine mutations were not expressed on the human embryonic kidney293T (HEK293T) cell surface, we at least confirmed that parts of EL2 are involved in interactions between AT1R and Abs. This current study thus provides extended insights into the molecular action of AT1R-Abs and associated mechanisms of interrelated pathogenesis.
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Affiliation(s)
- Aurélie Philippe
- Berlin Institute of Health at Charité—Universitätsmedizin Berlin, BIH Biomedical Innovation Academy, D-10178 Berlin, Germany
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Department of Nephrology and Medical Intensive Care, Campus Virchow Klinikum, D-13353 Berlin, Germany; (J.J.G.); (S.W.); (D.P.); (R.C.)
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Center for Cardiovascular Research, D-10117 Berlin, Germany
- Correspondence: (A.P.); (P.S.); Tel.: +49-30450559318 (A.P.); +49-30450524178 (P.S.)
| | - Gunnar Kleinau
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, D-10117 Berlin, Germany; (G.K.); (D.S.); (P.W.H.); (M.S.)
| | - Jason Jannis Gruner
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Department of Nephrology and Medical Intensive Care, Campus Virchow Klinikum, D-13353 Berlin, Germany; (J.J.G.); (S.W.); (D.P.); (R.C.)
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Center for Cardiovascular Research, D-10117 Berlin, Germany
- Vivantes Humboldt-Klinikum, Department of Urology, D-13509 Berlin, Germany
| | - Sumin Wu
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Department of Nephrology and Medical Intensive Care, Campus Virchow Klinikum, D-13353 Berlin, Germany; (J.J.G.); (S.W.); (D.P.); (R.C.)
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Center for Cardiovascular Research, D-10117 Berlin, Germany
| | - Daniel Postpieszala
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Department of Nephrology and Medical Intensive Care, Campus Virchow Klinikum, D-13353 Berlin, Germany; (J.J.G.); (S.W.); (D.P.); (R.C.)
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Center for Cardiovascular Research, D-10117 Berlin, Germany
| | - David Speck
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, D-10117 Berlin, Germany; (G.K.); (D.S.); (P.W.H.); (M.S.)
| | | | | | - Gabriela Riemekasten
- Priority Area Asthma & Allergy, Research Center Borstel, Airway Research Center North (ARCN), Members of the German Center for Lung Research (DZL), D-23845 Borstel, Germany;
- University of Lübeck, University Clinic Schleswig-Holstein, Department of Rheumatology and Clinical Immunology, Campus Lübeck, D-23538 Lübeck, Germany
| | - Peter W. Hildebrand
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, D-10117 Berlin, Germany; (G.K.); (D.S.); (P.W.H.); (M.S.)
- Leipzig University, Medical Faculty Leipzig, Institute for Medical Physics and Biophysics, D-04107 Leipzig, Germany
- Berlin Institute of Health at Charité—Universitätsmedizin Berlin, D-10178 Berlin, Germany
| | - Julian Kamhieh-Milz
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Department of Transfusion Medicine, D-10117 Berlin, Germany;
| | - Rusan Catar
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Department of Nephrology and Medical Intensive Care, Campus Virchow Klinikum, D-13353 Berlin, Germany; (J.J.G.); (S.W.); (D.P.); (R.C.)
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Center for Cardiovascular Research, D-10117 Berlin, Germany
| | - Michal Szczepek
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, D-10117 Berlin, Germany; (G.K.); (D.S.); (P.W.H.); (M.S.)
| | - Duska Dragun
- Berlin Institute of Health at Charité—Universitätsmedizin Berlin, BIH Biomedical Innovation Academy, D-10178 Berlin, Germany
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Department of Nephrology and Medical Intensive Care, Campus Virchow Klinikum, D-13353 Berlin, Germany; (J.J.G.); (S.W.); (D.P.); (R.C.)
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Center for Cardiovascular Research, D-10117 Berlin, Germany
| | - Patrick Scheerer
- Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, D-10117 Berlin, Germany; (G.K.); (D.S.); (P.W.H.); (M.S.)
- DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, D-13353 Berlin, Germany
- Correspondence: (A.P.); (P.S.); Tel.: +49-30450559318 (A.P.); +49-30450524178 (P.S.)
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4
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Structural Complexity and Plasticity of Signaling Regulation at the Melanocortin-4 Receptor. Int J Mol Sci 2020; 21:ijms21165728. [PMID: 32785054 PMCID: PMC7460885 DOI: 10.3390/ijms21165728] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 08/03/2020] [Accepted: 08/06/2020] [Indexed: 02/06/2023] Open
Abstract
The melanocortin-4 receptor (MC4R) is a class A G protein-coupled receptor (GPCR), essential for regulation of appetite and metabolism. Pathogenic inactivating MC4R mutations are the most frequent cause of monogenic obesity, a growing medical and socioeconomic problem worldwide. The MC4R mediates either ligand-independent or ligand-dependent signaling. Agonists such as α-melanocyte-stimulating hormone (α-MSH) induce anorexigenic effects, in contrast to the endogenous inverse agonist agouti-related peptide (AgRP), which causes orexigenic effects by suppressing high basal signaling activity. Agonist action triggers the binding of different subtypes of G proteins and arrestins, leading to concomitant induction of diverse intracellular signaling cascades. An increasing number of experimental studies have unraveled molecular properties and mechanisms of MC4R signal transduction related to physiological and pathophysiological aspects. In addition, the MC4R crystal structure was recently determined at 2.75 Å resolution in an inactive state bound with a peptide antagonist. Underpinned by structural homology models of MC4R complexes simulating a presumably active-state conformation compared to the structure of the inactive state, we here briefly summarize the current understanding and key players involved in the MC4R switching process between different activity states. Finally, these perspectives highlight the complexity and plasticity in MC4R signaling regulation and identify gaps in our current knowledge.
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Jacobi SF, Khajavi N, Kleinau G, Teumer A, Scheerer P, Homuth G, Völzke H, Wiegand S, Kühnen P, Krude H, Gong M, Raile K, Biebermann H. Evaluation of a rare glucose-dependent insulinotropic polypeptide receptor variant in a patient with diabetes. Diabetes Obes Metab 2019; 21:1168-1176. [PMID: 30784161 DOI: 10.1111/dom.13634] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2018] [Revised: 12/23/2018] [Accepted: 01/04/2019] [Indexed: 12/14/2022]
Abstract
AIMS Glucose-dependent insulinotropic polypeptide (GIP) is an incretin hormone that augments insulin secretion in pancreatic β-cells via its glucose-dependent insulinotropic polypeptide receptor (GIPR). Recent genome-wide association studies identified a single nucleotide variant (SNV) in the GIPR encoding gene (GIPR), rs1800437, that is associated with obesity and insulin resistance. In the present study, we tested whether GIPR variants contribute to obesity and disturb glucose homeostasis or diabetes in specific patient populations. MATERIALS AND METHODS Exon sequencing of GIPR was performed in 164 children with obesity and insulin resistance and in 80 children with paediatric-onset diabetes of unknown origin. The Study of Health in Pomerania (SHIP) cohort, comprising 8320 adults, was screened for the GIPR variant Arg217Leu. GIPR variants were expressed in COS-7 cells and cAMP production was measured upon stimulation with GIP. Cell surface expression was determined by ELISA. Protein homology modelling of the GIPR variants was performed to extract three-dimensional information of the receptor. RESULTS A heterozygous missense GIPR variant Arg217Leu (rs200485112) was identified in a patient of Asian ancestry. Functional characterization of Arg217Leu revealed reduced surface expression and signalling after GIP challenge. The homology model of the GIPR structure supports the observed functional relevance of Arg217Leu. CONCLUSION In vitro functional studies and protein homology modelling indicate a potential relevance of the GIPR variant Arg217Leu in receptor function. The heterozygous variant displayed partial co-segregation with diabetes. Based on these findings, we suggest that GIPR variants may play a role in disturbed glucose homeostasis and may be of clinical relevance in homozygous patients.
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Affiliation(s)
- Simon F Jacobi
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; Institute of Experimental Pediatric Endocrinology, Berlin, Germany
- University Heart Center Freiburg-Bad Krozingen, Department of Congenital Heart Disease and Pediatric Cardiology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Noushafarin Khajavi
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; Institute of Experimental Pediatric Endocrinology, Berlin, Germany
| | - Gunnar Kleinau
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; Institute of Experimental Pediatric Endocrinology, Berlin, Germany
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health; Institut für Medizinische Physik und Biophysik, Group Protein X-ray Crystallography and Signal Transduction, Berlin, Germany
| | - Alexander Teumer
- Department SHIP/Clinical-Epidemiological Research, Institute for Community Medicine, University Medicine Greifswald, Greifswald, Germany
| | - Patrick Scheerer
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health; Institut für Medizinische Physik und Biophysik, Group Protein X-ray Crystallography and Signal Transduction, Berlin, Germany
| | - Georg Homuth
- Department of Functional Genomics, Interfaculty Institute for Genetics and Functional Genomics, University Medicine, University Greifswald, Greifswald, Germany
| | - Henry Völzke
- Department SHIP/Clinical-Epidemiological Research, Institute for Community Medicine, University Medicine Greifswald, Greifswald, Germany
- German Center for Diabetes Research (DZD), Site Greifswald, Greifswald, Germany
| | - Susanna Wiegand
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; Institute of Experimental Pediatric Endocrinology, Berlin, Germany
| | - Peter Kühnen
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; Institute of Experimental Pediatric Endocrinology, Berlin, Germany
| | - Heiko Krude
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; Institute of Experimental Pediatric Endocrinology, Berlin, Germany
| | - Maolian Gong
- Experimental and Clinical Research Center (ECRC), a joint collaboration of Charité and Max-Delbrück-Center of Molecular Medicine, Berlin, Germany
| | - Klemens Raile
- Experimental and Clinical Research Center (ECRC), a joint collaboration of Charité and Max-Delbrück-Center of Molecular Medicine, Berlin, Germany
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; Department of Paediatric Endocrinology and Diabetology, Berlin, Germany
| | - Heike Biebermann
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; Institute of Experimental Pediatric Endocrinology, Berlin, Germany
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An incretin-based tri-agonist promotes superior insulin secretion from murine pancreatic islets via PLC activation. Cell Signal 2018; 51:13-22. [DOI: 10.1016/j.cellsig.2018.07.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 07/24/2018] [Accepted: 07/24/2018] [Indexed: 01/22/2023]
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7
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Lagarias P, Vrontaki E, Lambrinidis G, Stamatis D, Convertino M, Ortore G, Mavromoustakos T, Klotz KN, Kolocouris A. Discovery of Novel Adenosine Receptor Antagonists through a Combined Structure- and Ligand-Based Approach Followed by Molecular Dynamics Investigation of Ligand Binding Mode. J Chem Inf Model 2018; 58:794-815. [PMID: 29485875 DOI: 10.1021/acs.jcim.7b00455] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
An intense effort is made by pharmaceutical and academic research laboratories to identify and develop selective antagonists for each adenosine receptor (AR) subtype as potential clinical candidates for "soft" treatment of various diseases. Crystal structures of subtypes A2A and A1ARs offer exciting opportunities for structure-based drug design. In the first part of the present work, Maybridge HitFinder library of 14400 compounds was utilized to apply a combination of structure-based against the crystal structure of A2AAR and ligand-based methodologies. The docking poses were rescored by CHARMM energy minimization and calculation of the desolvation energy using Poisson-Boltzmann equation electrostatics. Out of the eight selected and tested compounds, five were found positive hits (63% success). Although the project was initially focused on targeting A2AAR, the identified antagonists exhibited low micromolar or micromolar affinity against A2A/A3, ARs, or A3AR, respectively. Based on these results, 19 compounds characterized by novel chemotypes were purchased and tested. Sixteen of them were identified as AR antagonists with affinity toward combinations of the AR family isoforms (A2A/A3, A1/A3, A1/A2A/A3, and A3). The second part of this work involves the performance of hundreds of molecular dynamics (MD) simulations of complexes between the ARs and a total of 27 ligands to resolve the binding interactions of the active compounds, which were not achieved by docking calculations alone. This computational work allowed the prediction of stable and unstable complexes which agree with the experimental results of potent and inactive compounds, respectively. Of particular interest is that the 2-amino-thiophene-3-carboxamides, 3-acylamino-5-aryl-thiophene-2-carboxamides, and carbonyloxycarboximidamide derivatives were found to be selective and possess a micromolar to low micromolar affinity for the A3 receptor.
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Affiliation(s)
- Panagiotis Lagarias
- Division of Pharmaceutical Chemistry, Department of Pharmacy, School of Health Sciences , National and Kapodistrian University of Athens , Panepistimiopolis-Zografou , 15771 Athens , Greece
| | - Eleni Vrontaki
- Division of Pharmaceutical Chemistry, Department of Pharmacy, School of Health Sciences , National and Kapodistrian University of Athens , Panepistimiopolis-Zografou , 15771 Athens , Greece
| | - George Lambrinidis
- Division of Pharmaceutical Chemistry, Department of Pharmacy, School of Health Sciences , National and Kapodistrian University of Athens , Panepistimiopolis-Zografou , 15771 Athens , Greece
| | - Dimitrios Stamatis
- Division of Pharmaceutical Chemistry, Department of Pharmacy, School of Health Sciences , National and Kapodistrian University of Athens , Panepistimiopolis-Zografou , 15771 Athens , Greece
| | - Marino Convertino
- Department of Biochemistry & Biophysics , University of North Carolina at Chapel Hill , 120 Mason Farm Road , Chapel Hill , North Carolina 27599 , United States
| | - Gabriella Ortore
- Department of Pharmacy , University of Pisa , 56126 Pisa , Italy
| | - Thomas Mavromoustakos
- Division of Organic Chemistry, Department of Chemistry, School of Science , National and Kapodistrian University of Athens , Panepistimiopolis-Zografou , 15771 Athens , Greece
| | - Karl-Norbert Klotz
- Institute of Pharmacology and Toxicology , University of Würzburg Versbacher Str. 9 , 97078 Würzburg , Germany
| | - Antonios Kolocouris
- Division of Pharmaceutical Chemistry, Department of Pharmacy, School of Health Sciences , National and Kapodistrian University of Athens , Panepistimiopolis-Zografou , 15771 Athens , Greece
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8
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Kumar P, Ashokan A, Aradhyam GK. Apelin binding to human APJ receptor leads to biased signaling. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2016; 1864:1748-1756. [DOI: 10.1016/j.bbapap.2016.09.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 08/26/2016] [Accepted: 09/22/2016] [Indexed: 12/15/2022]
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9
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Sandal M, Behrens M, Brockhoff A, Musiani F, Giorgetti A, Carloni P, Meyerhof W. Evidence for a Transient Additional Ligand Binding Site in the TAS2R46 Bitter Taste Receptor. J Chem Theory Comput 2015; 11:4439-49. [PMID: 26575934 DOI: 10.1021/acs.jctc.5b00472] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Most human G protein coupled receptors (GPCRs) are activated by small molecules binding to their 7-transmembrane (7-TM) helix bundle. They belong to basally diverging branches: the 25 bitter taste 2 receptors and most members of the very large rhodopsin-like/class A GPCRs subfamily. Some members of the class A branch have been suggested to feature not only an orthosteric agonist-binding site but also a more extracellular or "vestibular" site, involved in the binding process. Here we use a hybrid molecular mechanics/coarse-grained (MM/CG) molecular dynamics approach on a widely studied bitter taste receptor (TAS2R46) receptor in complex with its agonist strychnine. Three ∼1 μs molecular simulation trajectories find two sites hosting the agonist, which together elucidate experimental data measured previously and in this work. This mechanism shares similarities with the one suggested for the evolutionarily distant class A GPCRs. It might be instrumental for the remarkably broad but specific spectrum of agonists of these chemosensory receptors.
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Affiliation(s)
- Massimo Sandal
- Computational Biophysics, German Research School for Simulation Sciences , 52425 Jülich, Germany
| | - Maik Behrens
- Department of Molecular Genetics, German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE) , Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany
| | - Anne Brockhoff
- Department of Molecular Genetics, German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE) , Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany
| | - Francesco Musiani
- Scuola Internazionale Superiore di Studi Avanzati (SISSA/ISAS) , Via Bonomea 265, 34151 Trieste, Italy.,Laboratory of Bioinorganic Chemistry, Department of Pharmacy and Biotechnology (FaBIT), University of Bologna , Viale Giuseppe Fanin 40, I-40127, Bologna, Italy
| | - Alejandro Giorgetti
- Computational Biophysics, German Research School for Simulation Sciences , 52425 Jülich, Germany.,Department of Biotechnology, University of Verona , Ca' Vignal 1, Strada Le Grazie 15, 37134 Verona, Italy
| | - Paolo Carloni
- Computational Biophysics, German Research School for Simulation Sciences , 52425 Jülich, Germany
| | - Wolfgang Meyerhof
- Department of Molecular Genetics, German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE) , Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany
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10
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Wifling D, Bernhardt G, Dove S, Buschauer A. The extracellular loop 2 (ECL2) of the human histamine H4 receptor substantially contributes to ligand binding and constitutive activity. PLoS One 2015; 10:e0117185. [PMID: 25629160 PMCID: PMC4309601 DOI: 10.1371/journal.pone.0117185] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 12/21/2014] [Indexed: 11/25/2022] Open
Abstract
In contrast to the corresponding mouse and rat orthologs, the human histamine H4 receptor (hH4R) shows extraordinarily high constitutive activity. In the extracellular loop (ECL), replacement of F169 by V as in the mouse H4R significantly reduced constitutive activity. Stabilization of the inactive state was even more pronounced for a double mutant, in which, in addition to F169V, S179 in the ligand binding site was replaced by M. To study the role of the FF motif in ECL2, we generated the hH4R-F168A mutant. The receptor was co-expressed in Sf9 insect cells with the G-protein subunits Gαi2 and Gβ1γ2, and the membranes were studied in [3H]histamine binding and functional [35S]GTPγS assays. The potency of various ligands at the hH4R-F168A mutant decreased compared to the wild-type hH4R, for example by 30- and more than 100-fold in case of the H4R agonist UR-PI376 and histamine, respectively. The high constitutive activity of the hH4R was completely lost in the hH4R-F168A mutant, as reflected by neutral antagonism of thioperamide, a full inverse agonist at the wild-type hH4R. By analogy, JNJ7777120 was a partial inverse agonist at the hH4R, but a partial agonist at the hH4R-F168A mutant, again demonstrating the decrease in constitutive activity due to F168A mutation. Thus, F168 was proven to play a key role not only in ligand binding and potency, but also in the high constitutive activity of the hH4R.
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Affiliation(s)
- David Wifling
- Institute of Pharmacy, Pharmaceutical/Medicinal Chemistry II, University of Regensburg, Regensburg, Germany
| | - Günther Bernhardt
- Institute of Pharmacy, Pharmaceutical/Medicinal Chemistry II, University of Regensburg, Regensburg, Germany
| | - Stefan Dove
- Institute of Pharmacy, Pharmaceutical/Medicinal Chemistry II, University of Regensburg, Regensburg, Germany
| | - Armin Buschauer
- Institute of Pharmacy, Pharmaceutical/Medicinal Chemistry II, University of Regensburg, Regensburg, Germany
- * E-mail:
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11
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Ragnarsson L, Andersson Å, Thomas WG, Lewis RJ. Extracellular Surface Residues of the α1B-Adrenoceptor Critical for G Protein–Coupled Receptor Function. Mol Pharmacol 2014; 87:121-9. [DOI: 10.1124/mol.114.094557] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
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12
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Jiang X, Dias JA, He X. Structural biology of glycoprotein hormones and their receptors: insights to signaling. Mol Cell Endocrinol 2014; 382:424-451. [PMID: 24001578 DOI: 10.1016/j.mce.2013.08.021] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 08/20/2013] [Accepted: 08/24/2013] [Indexed: 01/18/2023]
Abstract
This article reviews the progress made in the field of glycoprotein hormones (GPH) and their receptors (GPHR) by several groups of structural biologists including ourselves aiming to gain insight into GPH signaling mechanisms. The GPH family consists of four members, with follicle-stimulating hormone (FSH) being the prototypic member. GPH members belong to the cystine-knot growth factor superfamily, and their receptors (GPHR), possessing unusually large N-terminal ectodomains, belong to the G-protein coupled receptor Family A. GPHR ectodomains can be divided into two subdomains: a high-affinity hormone binding subdomain primarily centered on the N-terminus, and a second subdomain that is located on the C-terminal region of the ectodomain that is involved in signal specificity. The two subdomains unexpectedly form an integral structure comprised of leucine-rich repeats (LRRs). Following the structure determination of hCG in 1994, the field of FSH structural biology has progressively advanced. Initially, the FSH structure was determined in partially glycosylated free form in 2001, followed by a structure of FSH bound to a truncated FSHR ectodomain in 2005, and the structure of FSH bound to the entire ectodomain in 2012. Comparisons of the structures in three forms led a proposal of a two-step monomeric receptor activation mechanism. First, binding of FSH to the FSHR high-affinity hormone-binding subdomain induces a conformational change in the hormone to form a binding pocket that is specific for a sulfated-tyrosine found as sTyr 335 in FSHR. Subsequently, the sTyr is drawn into the newly formed binding pocket, producing a lever effect on a helical pivot whereby the docking sTyr provides as the 'pull & lift' force. The pivot helix is flanked by rigid LRRs and locked by two disulfide bonds on both sides: the hormone-binding subdomain on one side and the last short loop before the first transmembrane helix on the other side. The lift of the sTyr loop frees the tethered extracellular loops of the 7TM domain, thereby releasing a putative inhibitory influence of the ectodomain, ultimately leading to the activating conformation of the 7TM domain. Moreover, the data lead us to propose that FSHR exists as a trimer and to present an FSHR activation mechanism consistent with the observed trimeric crystal form. A trimeric receptor provides resolution of the enigmatic, but important, biological roles played by GPH residues that are removed from the primary FSH-binding site, as well as several important GPCR phenomena, including negative cooperativity and asymmetric activation. Further reflection pursuant to this review process revealed additional novel structural characteristics such as the identification of a 'seat' sequence in GPH. Together with the 'seatbelt', the 'seat' enables a common heteodimeric mode of association of the common α subunit non-covalently and non-specifically with each of the three different β subunits. Moreover, it was possible to establish a dimensional order that can be used to estimate LRR curvatures. A potential binding pocket for small molecular allosteric modulators in the FSHR 7TM domain has also been identified.
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Affiliation(s)
- Xuliang Jiang
- EMD Serono Research & Development Institute, Billerica, MA 01821, United States.
| | - James A Dias
- Department of Biomedical Sciences, School of Public Health, University at Albany-SUNY, Albany, NY 12222, United States
| | - Xiaolin He
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States
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13
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Soriano-Ursúa MA, Trujillo-Ferrara JG, Correa-Basurto J, Vilar S. Recent structural advances of β1 and β2 adrenoceptors yield keys for ligand recognition and drug design. J Med Chem 2013; 56:8207-23. [PMID: 23862978 DOI: 10.1021/jm400471z] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Because they represent attractive drug targets, adrenoceptors have been widely studied. Recent progress in structural data of β-adrenoceptors allows us to understand and predict key interactions in ligand recognition and receptor activation. Nevertheless, an important aspect of this process has only begun to be explored: the stabilization of a conformational state of these receptors upon contact with a ligand and the capacity of a ligand to influence receptor conformation through allosteric modulation, biased signaling, and selectivity. The aim of the present Perspective is to identify the well-defined orthosteric binding site and possible allosteric sites and to analyze the importance of the ligand-receptor interaction in the stabilization of certain receptor conformations. For this purpose, we have reviewed recent advances made through the use of X-ray data from ligand-β-adrenoceptor (including ADRB1 and ADRB2) crystal structures. Most importantly, implications in the medicinal chemistry field are explored in relation to drug design.
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Affiliation(s)
- Marvin A Soriano-Ursúa
- Departments of Biochemistry and Physiology, Laboratory of Molecular Modeling and Bioinformatics, Postgraduate Research Section, Escuela Superior de Medicina, Instituto Politécnico Nacional , Plan de San Luis y Dı́az Mirón s/n, Mexico City, 11340, Mexico
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14
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Hu G, Suo Y, Huang J. A crucial role of the RGS domain in trans-Golgi network export of AtRGS1 in the protein secretory pathway. MOLECULAR PLANT 2013; 6:1933-1944. [PMID: 23793400 DOI: 10.1093/mp/sst109] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The secretory pathway is responsible for the transport of newly synthesized transmembrane proteins from the endoplasmic reticulum to their destinations via the Golgi/trans-Golgi network (TGN). Cargo proteins at each station are actively sorted by specific sorting signals on the cargo and the corresponding coat complexes. Here, we used the Arabidopsis regulator of G-protein signaling (AtRGS1), which contains an N-terminal potentially sensing glucose seven-transmembrane domain and a C-terminal RGS domain, as a model to uncover sorting motifs required for its cell surface expression. Expression of wild-type and truncated or mutated AtRGS1 fluorescent fusion proteins identified two cysteine residues in the extracellular N-terminus that are essential for endoplasmic reticulum exit and/or correct folding of AtRGS1. The linker between the seven-transmembrane and RGS domains contains an endoplasmic reticulum export signal, whereas the C-terminus is dispensable for the plasma membrane expression of AtRGS1. Interestingly, deletion of the RGS domain results in Golgi/TGN localization of the truncated AtRGS1. Further analysis using site-directed mutagenesis showed that a tyrosine-based motif embedded in the RGS domain is essential for Golgi/TGN export of AtRGS1. These results reveal a new role for the RGS domain in regulating AtRGS1 trafficking from the Golgi/TGN to the plasma membrane and explain the interaction between the seven-transmembrane and RGS domains.
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Affiliation(s)
- Guangzhen Hu
- National Key Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Feng Lin Road, Shanghai 200032, China
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15
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Kleinau G, Neumann S, Grüters A, Krude H, Biebermann H. Novel insights on thyroid-stimulating hormone receptor signal transduction. Endocr Rev 2013; 34:691-724. [PMID: 23645907 PMCID: PMC3785642 DOI: 10.1210/er.2012-1072] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The TSH receptor (TSHR) is a member of the glycoprotein hormone receptors, a subfamily of family A G protein-coupled receptors. The TSHR is of great importance for the growth and function of the thyroid gland. The TSHR and its endogenous ligand TSH are pivotal proteins with respect to a variety of physiological functions and malfunctions. The molecular events of TSHR regulation can be summarized as a process of signal transduction, including signal reception, conversion, and amplification. The steps during signal transduction from the extra- to the intracellular sites of the cell are not yet comprehensively understood. However, essential new insights have been achieved in recent years on the interrelated mechanisms at the extracellular region, the transmembrane domain, and intracellular components. This review contains a critical summary of available knowledge of the molecular mechanisms of signal transduction at the TSHR, for example, the key amino acids involved in hormone binding or in the structural conformational changes that lead to G protein activation or signaling regulation. Aspects of TSHR oligomerization, signaling promiscuity, signaling selectivity, phenotypes of genetic variations, and potential extrathyroidal receptor activity are also considered, because these are relevant to an understanding of the overall function of the TSHR, including physiological, pathophysiological, and pharmacological perspectives. Directions for future research are discussed.
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Affiliation(s)
- Gunnar Kleinau
- Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, Ostring 3, Augustenburger Platz 1, 13353 Berlin, Germany.
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16
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Müller A, Kleinau G, Piechowski CL, Müller TD, Finan B, Pratzka J, Grüters A, Krude H, Tschöp M, Biebermann H. G-protein coupled receptor 83 (GPR83) signaling determined by constitutive and zinc(II)-induced activity. PLoS One 2013; 8:e53347. [PMID: 23335960 PMCID: PMC3546042 DOI: 10.1371/journal.pone.0053347] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Accepted: 11/27/2012] [Indexed: 12/31/2022] Open
Abstract
The G-protein coupled receptor 83 (GPR83) is an orphan G-protein coupled receptor for which the natural ligand(s) and signaling pathway(s) remain to be identified. Previous studies suggest a role of GPR83 in the regulation of thermogenesis and the control of circulating adiponectin. The aim of this study was to gain insights into the molecular underpinnings underlying GPR83 signaling. In particular, we aimed to assess the underlying G-protein activated signaling pathway of GPR83 and how this pathway is affected by mutational activation and zinc(II) challenge. Finally, we assessed the capacity of GPR83 for homodimerization. Our results show for the first time that mouse (m) GPR83 has high basal Gq/11 activity without affecting Gi or Gs signaling. Furthermore, we found that, under physiological conditions, zinc(II) (but not calcium(II) and magnesium(II)) potently activates mGPR83, thus identifying zinc(II) as an endogenous molecule with agonistic capability to activate mGPR83. In line with the observation that zinc(II)-ions activate mGPR83, we identified a cluster of ion-binding sensitive amino acids (e.g. His145, His204, Cys207, Glu217) in an activation sensitive receptor region of mGPR83. The occurrence of a constitutive activating mutant and a zinc(II)-binding residue at the N-terminal part corroborate the importance of this region in mGPR83 signal regulation. Finally, our results indicate that mGPR83 forms homodimers, which extend the current knowledge and molecular facets of GPR83 signaling.
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Affiliation(s)
- Anne Müller
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Gunnar Kleinau
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Carolin L. Piechowski
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Timo D. Müller
- Institute of Diabetes and Obesity, Helmholtz Center Munich, German Research Center for Environmental Health (GmbH), Munich, Germany
| | - Brian Finan
- Institute of Diabetes and Obesity, Helmholtz Center Munich, German Research Center for Environmental Health (GmbH), Munich, Germany
| | - Juliane Pratzka
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Annette Grüters
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Heiko Krude
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Matthias Tschöp
- Institute of Diabetes and Obesity, Helmholtz Center Munich, German Research Center for Environmental Health (GmbH), Munich, Germany
- Department of Metabolic Diseases, Technical University, Munich, Germany
| | - Heike Biebermann
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
- * E-mail:
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17
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Caltabiano G, Gonzalez A, Cordomí A, Campillo M, Pardo L. The Role of Hydrophobic Amino Acids in the Structure and Function of the Rhodopsin Family of G Protein-Coupled Receptors. Methods Enzymol 2013; 520:99-115. [DOI: 10.1016/b978-0-12-391861-1.00005-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2023]
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18
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Adenosiland: Walking through adenosine receptors landscape. Eur J Med Chem 2012; 58:248-57. [DOI: 10.1016/j.ejmech.2012.10.022] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 10/12/2012] [Accepted: 10/15/2012] [Indexed: 11/22/2022]
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19
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Gong Y, Fu W, Chen K. Dopamine D1receptor and serotonin 5-HT1Areceptor agonist effects of the natural product (–)-stepholidine: molecular modelling and dynamics simulations. MOLECULAR SIMULATION 2012. [DOI: 10.1080/08927022.2012.679619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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20
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Wheatley M, Wootten D, Conner MT, Simms J, Kendrick R, Logan RT, Poyner DR, Barwell J. Lifting the lid on GPCRs: the role of extracellular loops. Br J Pharmacol 2012; 165:1688-1703. [PMID: 21864311 DOI: 10.1111/j.1476-5381.2011.01629.x] [Citation(s) in RCA: 224] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
GPCRs exhibit a common architecture of seven transmembrane helices (TMs) linked by intracellular loops and extracellular loops (ECLs). Given their peripheral location to the site of G-protein interaction, it might be assumed that ECL segments merely link the important TMs within the helical bundle of the receptor. However, compelling evidence has emerged in recent years revealing a critical role for ECLs in many fundamental aspects of GPCR function, which supported by recent GPCR crystal structures has provided mechanistic insights. This review will present current understanding of the key roles of ECLs in ligand binding, activation and regulation of both family A and family B GPCRs.
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Affiliation(s)
- M Wheatley
- School of Biosciences, University of Birmingham, Birmingham, UKDrug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, AustraliaDepartment of Pharmacology, Monash University, Parkville, Victoria, AustraliaSchool of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, UK
| | - D Wootten
- School of Biosciences, University of Birmingham, Birmingham, UKDrug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, AustraliaDepartment of Pharmacology, Monash University, Parkville, Victoria, AustraliaSchool of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, UK
| | - M T Conner
- School of Biosciences, University of Birmingham, Birmingham, UKDrug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, AustraliaDepartment of Pharmacology, Monash University, Parkville, Victoria, AustraliaSchool of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, UK
| | - J Simms
- School of Biosciences, University of Birmingham, Birmingham, UKDrug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, AustraliaDepartment of Pharmacology, Monash University, Parkville, Victoria, AustraliaSchool of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, UK
| | - R Kendrick
- School of Biosciences, University of Birmingham, Birmingham, UKDrug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, AustraliaDepartment of Pharmacology, Monash University, Parkville, Victoria, AustraliaSchool of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, UK
| | - R T Logan
- School of Biosciences, University of Birmingham, Birmingham, UKDrug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, AustraliaDepartment of Pharmacology, Monash University, Parkville, Victoria, AustraliaSchool of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, UK
| | - D R Poyner
- School of Biosciences, University of Birmingham, Birmingham, UKDrug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, AustraliaDepartment of Pharmacology, Monash University, Parkville, Victoria, AustraliaSchool of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, UK
| | - J Barwell
- School of Biosciences, University of Birmingham, Birmingham, UKDrug Discovery Biology Laboratory, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, AustraliaDepartment of Pharmacology, Monash University, Parkville, Victoria, AustraliaSchool of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, UK
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21
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Peeters MC, Wisse LE, Dinaj A, Vroling B, Vriend G, Ijzerman AP. The role of the second and third extracellular loops of the adenosine A1 receptor in activation and allosteric modulation. Biochem Pharmacol 2012; 84:76-87. [PMID: 22449615 DOI: 10.1016/j.bcp.2012.03.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Revised: 03/13/2012] [Accepted: 03/14/2012] [Indexed: 10/28/2022]
Abstract
The adenosine A1 receptor is a member of the large membrane protein family that signals through G proteins, the G protein-coupled receptors (GPCRs). GPCRs consist of seven transmembrane domains connected by three intracellular and three extracellular loops. Their N-terminus is extracellular, the C-terminal tail is in the cytoplasm. The transmembrane domains in receptor subfamilies that bind the same endogenous ligand, such as dopamine or adenosine, tend to be highly similar. In contrast, the loop regions can vary greatly, both in sequence and in length, and the role these loops have in the activation mechanism of the receptors remains unclear. Here, we investigated the activating role of the second and third extracellular loop of the human adenosine A1 receptor. By means of an (Ala)3 mutagenic scan in which consecutive sets of three amino acids were mutated into alanine residues in EL2 and a classical alanine scan in EL3, we revealed a strong regulatory role for the second extracellular loop (EL2) of the human adenosine A1 receptor. Besides many residues in the second and the third extracellular loops important for adenosine A1 receptor activation, we also identified two residues in EL2, a tryptophan and a glutamate, that affect the influence of the allosteric modulator PD81,723. These results, combined with a comparison of the different receptor loop regions, provide insight in the activation mechanism of this typical class A GPCR and further emphasize the unique pharmacological profile the loops can provide to individual receptors, even within subfamilies of GPCRs.
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Affiliation(s)
- M C Peeters
- Division of Medicinal Chemistry, Leiden/Amsterdam Centre for Drug Research, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands
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22
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Carroll CE, Marada S, Stewart DP, Ouyang JX, Ogden SK. The extracellular loops of Smoothened play a regulatory role in control of Hedgehog pathway activation. Development 2012; 139:612-21. [PMID: 22223683 DOI: 10.1242/dev.075614] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The Hedgehog (Hh) signaling pathway plays an instructional role during development, and is frequently activated in cancer. Ligand-induced pathway activation requires signaling by the transmembrane protein Smoothened (Smo), a member of the G-protein-coupled receptor (GPCR) superfamily. The extracellular (EC) loops of canonical GPCRs harbor cysteine residues that engage in disulfide bonds, affecting active and inactive signaling states through regulating receptor conformation, dimerization and/or ligand binding. Although a functional importance for cysteines localized to the N-terminal extracellular cysteine-rich domain has been described, a functional role for a set of conserved cysteines in the EC loops of Smo has not yet been established. In this study, we mutated each of the conserved EC cysteines, and tested for effects on Hh signal transduction. Cysteine mutagenesis reveals that previously uncharacterized functional roles exist for Smo EC1 and EC2. We provide in vitro and in vivo evidence that EC1 cysteine mutation induces significant Hh-independent Smo signaling, triggering a level of pathway activation similar to that of a maximal Hh response in Drosophila and mammalian systems. Furthermore, we show that a single amino acid change in EC2 attenuates Hh-induced Smo signaling, whereas deletion of the central region of EC2 renders Smo fully active, suggesting that the conformation of EC2 is crucial for regulated Smo activity. Taken together, these findings are consistent with loop cysteines engaging in disulfide bonds that facilitate a Smo conformation that is silent in the absence of Hh, but can transition to a fully active state in response to ligand.
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Affiliation(s)
- Candace E Carroll
- Department of Biochemistry, St Jude Children's Research Hospital, 262 Danny Thomas Place, MS 340, Memphis, TN 38105, USA
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23
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Unal H, Jagannathan R, Karnik SS. Mechanism of GPCR-Directed Autoantibodies in Diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 749:187-99. [DOI: 10.1007/978-1-4614-3381-1_13] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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24
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Fanelli F, De Benedetti PG. Update 1 of: computational modeling approaches to structure-function analysis of G protein-coupled receptors. Chem Rev 2011; 111:PR438-535. [PMID: 22165845 DOI: 10.1021/cr100437t] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Francesca Fanelli
- Dulbecco Telethon Institute, University of Modena and Reggio Emilia, via Campi 183, 41125 Modena, Italy.
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25
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Unal H, Karnik SS. Domain coupling in GPCRs: the engine for induced conformational changes. Trends Pharmacol Sci 2011; 33:79-88. [PMID: 22037017 DOI: 10.1016/j.tips.2011.09.007] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 09/23/2011] [Accepted: 09/29/2011] [Indexed: 11/28/2022]
Abstract
Recent solved structures of G protein-coupled receptors (GPCRs) provide insights into variation of the structure and molecular mechanisms of GPCR activation. In this review, we provide evidence for the emerging paradigm of domain coupling facilitated by intrinsic disorder of the ligand-free state in GPCRs. The structure-function and dynamic studies suggest that ligand-bound GPCRs exhibit multiple active conformations in initiating cellular signals. Long-range intramolecular and intermolecular interactions at distant sites on the same receptor are crucial factors that modulate signaling function of GPCRs. Positive or negative coupling between the extracellular, the transmembrane and the intracellular domains facilitates cooperativity of activating 'switches' as requirements for the functional plasticity of GPCRs. Awareness that allosteric ligands robustly affect domain coupling provides a novel mechanistic basis for rational drug development, small molecule antagonism and GPCR regulation by classical as well as nonclassical modes.
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Affiliation(s)
- Hamiyet Unal
- Department of Molecular Cardiology, Lerner Research Institute, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA
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26
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Three "hotspots" important for adenosine A(2B) receptor activation: a mutational analysis of transmembrane domains 4 and 5 and the second extracellular loop. Purinergic Signal 2011; 8:23-38. [PMID: 21818573 PMCID: PMC3286537 DOI: 10.1007/s11302-011-9251-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Accepted: 07/14/2011] [Indexed: 01/13/2023] Open
Abstract
G protein-coupled receptors (GPCRs) are a major drug target and can be activated by a range of stimuli, from photons to proteins. Despite the progress made in the last decade in molecular and structural biology, their exact activation mechanism is still unknown. Here we describe new insights in specific regions essential in adenosine A2B receptor activation (A2BR), a typical class A GPCR. We applied unbiased random mutagenesis on the middle part of the human adenosine A2BR, consisting of transmembrane domains 4 and 5 (TM4 and TM5) linked by extracellular loop 2 (EL2), and subsequently screened in a medium-throughput manner for gain-of-function and constitutively active mutants. For that purpose, we used a genetically engineered yeast strain (Saccharomyces cerevisiae MMY24) with growth as a read-out parameter. From the random mutagenesis screen, 12 different mutant receptors were identified that form three distinct clusters; at the top of TM4, in a cysteine-rich region in EL2, and at the intracellular side of TM5. All mutant receptors show a vast increase in agonist potency and most also displayed a significant increase in constitutive activity. None of these residues are supposedly involved in ligand binding directly. As a consequence, it appears that disrupting the relatively “silent” configuration of the wild-type receptor in each of the three clusters readily causes spontaneous receptor activity.
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27
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Shim JY, Rudd J, Ding TT. Distinct second extracellular loop structures of the brain cannabinoid CB(1) receptor: implication in ligand binding and receptor function. Proteins 2011; 79:581-97. [PMID: 21120862 DOI: 10.1002/prot.22907] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The G-protein-coupled receptor (GPCR) second extracellular loop (E2) is known to play an important role in receptor structure and function. The brain cannabinoid (CB(1)) receptor is unique in that it lacks the interloop E2 disulfide linkage to the transmembrane (TM) helical bundle, a characteristic of many GPCRs. Recent mutation studies of the CB(1) receptor, however, suggest the presence of an alternative intraloop disulfide bond between two E2 Cys residues. Considering the oxidation state of these Cys residues, we determine the molecular structures of the 17-residue E2 in the dithiol form (E2(dithiol)) and in the disulfide form (E2(disulfide)) of the CB(1) receptor in a fully hydrated 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayer, using a combination of simulated annealing and molecular dynamics simulation approaches. We characterize the CB(1) receptor models with these two E2 forms, CB(1)(E2(dithiol)) and CB(1)(E2(disulfide)), by analyzing interaction energy, contact number, core crevice, and cross correlation. The results show that the distinct E2 structures interact differently with the TM helical bundle and uniquely modify the TM helical topology, suggesting that E2 of the CB(1) receptor plays a critical role in stabilizing receptor structure, regulating ligand binding, and ultimately modulating receptor activation. Further studies on the role of E2 of the CB(1) receptor are warranted, particularly comparisons of the ligand-bound form with the present ligand-free form.
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Affiliation(s)
- Joong-Youn Shim
- JL Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, North Carolina 27707, USA.
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28
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Shim JY. Understanding functional residues of the cannabinoid CB1. Curr Top Med Chem 2011; 10:779-98. [PMID: 20370713 DOI: 10.2174/156802610791164210] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Accepted: 10/27/2009] [Indexed: 02/07/2023]
Abstract
The brain cannabinoid (CB(1)) receptor that mediates numerous physiological processes in response to marijuana and other psychoactive compounds is a G protein coupled receptor (GPCR) and shares common structural features with many rhodopsin class GPCRs. For the rational development of therapeutic agents targeting the CB(1) receptor, understanding of the ligand-specific CB(1) receptor interactions responsible for unique G protein signals is crucial. For a more than a decade, a combination of mutagenesis and computational modeling approaches has been successfully employed to study the ligand-specific CB(1) receptor interactions. In this review, after a brief discussion about recent advances in understanding of some structural and functional features of GPCRs commonly applicable to the CB(1) receptor, the CB(1) receptor functional residues reported from mutational studies are divided into three different types, ligand binding (B), receptor stabilization (S) and receptor activation (A) residues, to delineate the nature of the binding pockets of anandamide, CP55940, WIN55212-2 and SR141716A and to describe the molecular events of the ligand-specific CB(1) receptor activation from ligand binding to G protein signaling. Taken these CB(1) receptor functional residues, some of which are unique to the CB(1) receptor, together with the biophysical knowledge accumulated for the GPCR active state, it is possible to propose the early stages of the CB(1) receptor activation process that not only provide some insights into understanding molecular mechanisms of receptor activation but also are applicable for identifying new therapeutic agents by applying the validated structure-based approaches, such as virtual high throughput screening (HTS) and fragment-based approach (FBA).
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Affiliation(s)
- Joong-Youn Shim
- J.L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, 700 George Street, Durham, NC 27707, USA.
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29
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Mugumbate G, Jackson GE, van der Spoel D. Open conformation of adipokinetic hormone receptor from the malaria mosquito facilitates hormone binding. Peptides 2011; 32:553-9. [PMID: 20804800 DOI: 10.1016/j.peptides.2010.08.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Revised: 08/19/2010] [Accepted: 08/22/2010] [Indexed: 11/20/2022]
Abstract
Insect flight requires rapid mobilization of energy reserves during flight, which is mediated and regulated by hormonal control via adipokinetic hormones. The structure of the G-protein receptors to which these hormones bind, are crucial in understanding many of the physiological processes in which they play a central role. To date no 3D structure of an insect G-protein coupled receptor (GPCR) is available. Here, the first models of the 3D structures of a GPCR from the malaria mosquito are presented. Homology modeling of the receptor identified from the genome of Anopheles gambiae was used to construct two models of the receptor. The 7 transmembrane helical bundles of these two models are based on the crystal structures of beta2-adrenergic receptor and rhodopsin. The flexible loop regions were modeled using high temperature simulated annealing and constrained molecular dynamic simulations. The two receptor models differ in a number of critical features, the most important of which is that the rhodopsin-based model has a 'closed' structure while the beta2-based structure is 'open'. The 'open' conformation provides easy access of the hormone to the binding pocket. Docking calculations with the insect adipokinetic hormones, AKH-1 (pGlu-Leu-Thr-Phe-Thr-Pro-Ala-Trp-NH(2)) from the malaria mosquito and Del-CC (pGlu-Lys-Asn-Phe-Ser-Pro-Asn-Trp-Gly-Asn-NH(2)) from the blister beetle showed that while the binding motif of the two is similar, AKH-1 has more than 30 times higher affinity than Del-CC, which strongly suggests that the binding is specific, and that the correct binding site was identified. Using these models it is possible to design antagonists, which block the binding site and are thus species-specific insecticides.
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Affiliation(s)
- Grace Mugumbate
- Department of Chemistry, University of Cape Town, Private Bag x3, Rondebosch, 7701, Cape Town, South Africa
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30
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Wichard JD, ter Laak A, Krause G, Heinrich N, Kühne R, Kleinau G. Chemogenomic analysis of G-protein coupled receptors and their ligands deciphers locks and keys governing diverse aspects of signalling. PLoS One 2011; 6:e16811. [PMID: 21326864 PMCID: PMC3033908 DOI: 10.1371/journal.pone.0016811] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Accepted: 01/12/2011] [Indexed: 11/28/2022] Open
Abstract
Understanding the molecular mechanism of signalling in the important super-family of G-protein-coupled receptors (GPCRs) is causally related to questions of how and where these receptors can be activated or inhibited. In this context, it is of great interest to unravel the common molecular features of GPCRs as well as those related to an active or inactive state or to subtype specific G-protein coupling. In our underlying chemogenomics study, we analyse for the first time the statistical link between the properties of G-protein-coupled receptors and GPCR ligands. The technique of mutual information (MI) is able to reveal statistical inter-dependence between variations in amino acid residues on the one hand and variations in ligand molecular descriptors on the other. Although this MI analysis uses novel information that differs from the results of known site-directed mutagenesis studies or published GPCR crystal structures, the method is capable of identifying the well-known common ligand binding region of GPCRs between the upper part of the seven transmembrane helices and the second extracellular loop. The analysis shows amino acid positions that are sensitive to either stimulating (agonistic) or inhibitory (antagonistic) ligand effects or both. It appears that amino acid positions for antagonistic and agonistic effects are both concentrated around the extracellular region, but selective agonistic effects are cumulated between transmembrane helices (TMHs) 2, 3, and ECL2, while selective residues for antagonistic effects are located at the top of helices 5 and 6. Above all, the MI analysis provides detailed indications about amino acids located in the transmembrane region of these receptors that determine G-protein signalling pathway preferences.
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Affiliation(s)
- Jörg D. Wichard
- Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany
- Bayer-Schering Pharma, Berlin, Germany
| | | | - Gerd Krause
- Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany
| | | | - Ronald Kühne
- Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany
- * E-mail:
| | - Gunnar Kleinau
- Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
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31
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Peeters MC, Westen GJP, Guo D, Wisse LE, Muller CE, Beukers MW, IJzerman AP. GPCR structure and activation: an essential role for the first extracellular loop in activating the adenosine A
2B
receptor. FASEB J 2010; 25:632-43. [DOI: 10.1096/fj.10-164319] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Miriam C. Peeters
- Division of Medicinal ChemistryLeiden/Amsterdam Centre for Drug ResearchLeiden UniversityLeidenThe Netherlands
| | - Gerard J. P. Westen
- Division of Medicinal ChemistryLeiden/Amsterdam Centre for Drug ResearchLeiden UniversityLeidenThe Netherlands
| | - Dong Guo
- Division of Medicinal ChemistryLeiden/Amsterdam Centre for Drug ResearchLeiden UniversityLeidenThe Netherlands
| | - Lisanne E. Wisse
- Division of Medicinal ChemistryLeiden/Amsterdam Centre for Drug ResearchLeiden UniversityLeidenThe Netherlands
| | - Christa E. Muller
- PharmaCenter BonnPharmaceutical InstitutePharmaceutical Chemistry IPharmaceutical Sciences Bonn (PSB)University of BonnBonnGermany
| | - Margot W. Beukers
- Division of Medicinal ChemistryLeiden/Amsterdam Centre for Drug ResearchLeiden UniversityLeidenThe Netherlands
| | - Adriaan P. IJzerman
- Division of Medicinal ChemistryLeiden/Amsterdam Centre for Drug ResearchLeiden UniversityLeidenThe Netherlands
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32
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Unal H, Jagannathan R, Bhat MB, Karnik SS. Ligand-specific conformation of extracellular loop-2 in the angiotensin II type 1 receptor. J Biol Chem 2010; 285:16341-50. [PMID: 20299456 DOI: 10.1074/jbc.m109.094870] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The orientation of the second extracellular loop (ECL2) is divergent in G-protein coupled receptor (GPCR) structures determined. This discovery provoked the question, is the ECL2 conformation differentially regulated in the GPCRs that respond to diffusible ligands? We have determined the conformation of the ECL2 of the angiotensin II type 1 receptor by reporter-cysteine accessibility mapping in different receptor states (i.e. empty, agonist-bound and antagonist-bound). We introduced cysteines at each position of ECL2 of an N-terminal epitope-tagged receptor surrogate lacking all non-essential cysteines and then measured reaction of these with a cysteine-reactive biotin probe. The ability of biotinylated mutant receptors to react with a steptavidin-HRP-conjugated antibody was used as the basis for examining differences in accessibility. Two segments of ECL2 were accessible in the empty receptor, indicating an open conformation of ECL2. These segments were inaccessible in the ligand-bound states of the receptor. Using the accessibility constraint, we performed molecular dynamics simulation to predict ECL2 conformation in different states of the receptor. Analysis suggested that a lid conformation similar to that of ECL2 in rhodopsin was induced upon binding both agonist and antagonist, but exposing different accessible segments delimited by the highly conserved disulfide bond. Our study reveals the ability of ECL2 to interact with diffusing ligands and to adopt a ligand-specific lid conformation, thus, slowing down dissociation of ligands when bound. Distinct conformations induced by the bound agonist and the antagonist around the conserved disulfide bond suggest an important role for this disulfide bond in producing different functional states of the receptor.
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Affiliation(s)
- Hamiyet Unal
- Department of Molecular Cardiology, Lerner Research Institute, The Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA
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33
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Huszár J, Timár Z, Bogár F, Penke B, Kiss R, Szalai KK, Schmidt É, Papp A, Keserű G. Aspartic acid scaffold in bradykinin B1 antagonists. J Pept Sci 2009; 15:423-34. [DOI: 10.1002/psc.1134] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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34
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Kleinau G, Krause G. Thyrotropin and homologous glycoprotein hormone receptors: structural and functional aspects of extracellular signaling mechanisms. Endocr Rev 2009; 30:133-51. [PMID: 19176466 DOI: 10.1210/er.2008-0044] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The TSH receptor (TSHR) together with the homologous lutropin/choriogonadotropin receptor and the follitropin receptor are glycoprotein hormone receptors (GPHRs). They constitute a subfamily of the rhodopsin-like G protein-coupled receptors with seven transmembrane helices. GPHRs and their corresponding hormones are pivotal proteins with respect to a variety of physiological functions. The identification and characterization of intra- and intermolecular signaling determinants as well as signaling mechanisms are prerequisites to gaining molecular insights into functions and (pathogenic) dysfunctions of GPHRs. Knowledge about activation mechanisms is fragmentary, and the specific aspects have still not been understood in their entirety. Therefore, here we critically review the data available for these receptors and bring together structural and functional findings with a focus on the important large extracellular portion of the TSHR. One main focus is the particular function of structural determinants in the initial steps of the activation such as: 1) hormone binding at the extracellular site; 2) hormone interaction at a second binding site in the hinge region; 3) signal regulation via sequence motifs in the hinge region; and 4) synergistic signal amplification by cooperative effects of the extracellular loops toward the transmembrane region. Comparison and consolidation of data from the homologous glycoprotein hormone receptors TSHR, follitropin receptor, and lutropin/choriogonadotropin receptor provide an overview of extracellular mechanisms of signal initiation, conduction, and regulation at the TSHR and homologous receptors. Finally, we address the issue of structural implications and suggest a refined scenario for the initial signaling process on GPHRs.
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Affiliation(s)
- Gunnar Kleinau
- Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany
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35
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Vangelista L, Secchi M, Lusso P. Rational design of novel HIV-1 entry inhibitors by RANTES engineering. Vaccine 2008; 26:3008-15. [PMID: 18243436 DOI: 10.1016/j.vaccine.2007.12.023] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2007] [Revised: 12/05/2007] [Accepted: 12/06/2007] [Indexed: 10/22/2022]
Abstract
The discovery that the CC chemokines RANTES, MIP-1alpha and MIP-1beta act as potent natural inhibitors of HIV-1, the causative agent of AIDS, and the subsequent identification of CCR5 as a major virus coreceptor have triggered a wealth of basic and applied research approaches aimed at developing safe and effective viral entry inhibitors. Some of these efforts have focused on RANTES engineering with the goal of enhancing the antiviral activity of the native molecule while reducing or abrogating its inflammatory properties. The wavefront generated a decade ago is still on its course, with a flow of promising leads constantly emerging and being evaluated in preclinical studies. Here, we present an overview of this rapidly evolving field, highlighting the most important features of RANTES molecular architecture and structure-function relationships.
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Affiliation(s)
- Luca Vangelista
- Department of Biological and Technological Research, San Raffaele Scientific Institute, Via Olgettina n. 58, 20132 Milan, Italy
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36
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Choi MY, Fuerst EJ, Rafaeli A, Jurenka R. Role of extracellular domains in PBAN/pyrokinin GPCRs from insects using chimera receptors. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2007; 37:296-306. [PMID: 17368193 DOI: 10.1016/j.ibmb.2006.12.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Revised: 12/07/2006] [Accepted: 12/08/2006] [Indexed: 05/14/2023]
Abstract
Pheromone biosynthesis-activating neuropeptide (PBAN) is a peptide used by a variety of moths to regulate pheromone production. Pyrokinins are peptides that activate muscle contraction in a variety of insects. These peptides have a common FXPRLamide C-terminal ending that is required for activity. Receptors have been identified from a moth and Drosophila as belonging to the rhodopsin family of G-protein coupled receptors (GPCRs) with sequence similarity to neuromedin U receptors from vertebrates. No insect GPCR has been characterized with regard to role of extracellular domains required for peptide binding and receptor activation. To begin characterizing these GPCRs we created chimera receptors using a PBAN-receptor from a moth and pyrokinin-receptors from Drosophila where extracellular domains were swapped. The N-terminal of the moth GPCR has two N-glycosylation sites that when replaced with glutamines, activity was reduced but not absent, indicating these sites contribute to receptor stability. Activity was greatly reduced by replacing the 2nd extracellular loop that has an N-glycosylation site and a cysteine that can form a disulfide bridge with a cysteine at the beginning of the 3rd transmembrane domain. Exchange of the 3rd extracellular loop between the moth and Drosophila receptor resulted in differential activation by PBAN or a diapause hormone peptide. This result indicates that the 3rd extracellular loop is directly involved in peptide ligand recognition. Results are discussed in context of the structural features of insect GPCRs that are required for receptor activation as compared to vertebrate receptors.
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Affiliation(s)
- Man-Yeon Choi
- Department of Entomology, Iowa State University, 434 Science II, Ames, IA 50011-3222, USA
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37
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Isin B, Rader AJ, Dhiman HK, Klein-Seetharaman J, Bahar I. Predisposition of the dark state of rhodopsin to functional changes in structure. Proteins 2007; 65:970-83. [PMID: 17009319 DOI: 10.1002/prot.21158] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
As the only member of the family of G-protein-coupled receptors for which atomic coordinates are available, rhodopsin is widely studied for insight into the molecular mechanism of G-protein-coupled receptor activation. The currently available structures refer to the inactive, dark state, of rhodopsin, rather than the light-activated metarhodopsin II (Meta II) state. A model for the Meta II state is proposed here by analyzing elastic network normal modes in conjunction with experimental data. Key mechanical features and interactions broken/formed in the proposed model are found to be consistent with the experimental data. The model is further tested by using a set of Meta II fluorescence decay rates measured to empirically characterize the deactivation of rhodopsin mutants. The model is found to correctly predict 93% of the experimentally observed effects in 119 rhodopsin mutants for which the decay rates and misfolding data have been measured, including a systematic analysis of Cys-->Ser replacements reported here. Based on the detailed comparison between model and experiments, a cooperative activation mechanism is deduced that couples retinal isomerization to concerted changes in conformation, facilitated by the intrinsic dynamics of rhodopsin. A global hinge site is identified near the retinal-binding pocket that ensures the efficient propagation of signals from the central transmembrane region to both cytoplasmic and extracellular ends. The predicted activation mechanism opens the transmembrane helices at the critical G-protein binding cytoplasmic domain. This model provides a detailed, mechanistic description of the activation process, extending experimental observations and yielding new insights for further tests.
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Affiliation(s)
- Basak Isin
- Department of Computational Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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38
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Yamamoto T. Roles of the ribosomal protein S19 dimer and the C5a receptor in pathophysiological functions of phagocytic leukocytes. Pathol Int 2007; 57:1-11. [PMID: 17199736 DOI: 10.1111/j.1440-1827.2007.02049.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Monocytes and neutrophils, the major phagocytic leukocytes, migrate to inflammatory sites by sensing chemoattractants such as anaphylatoxin C5a with membrane receptors such as C5a receptor. Upon stimulation, the leukocytes increase cytoplasmic Ca(2+) concentration and generate radical oxygen species. These leukocytes have different functions in inflammation. Neutrophils migrate more rapidly and induce vascular plasma leakage upon infiltration. Monocytes infiltrate tissue more slowly but have superior capacities of phagocytosis and antigen presentation. There must be mechanisms to separately recruit the leukocyte species at an inflammatory site. Ribosomal protein S19 (RP S19) is a component of ribosome. During apoptosis, RP S19 is dimerized and obtains a ligand capacity to C5a receptor. The RP S19 dimer attracts monocytes to phagocytically clear the apoptotic cells that released the dimer molecules. The phagocytic monocytes/macrophages then translocate to regional lymph nodes and present apoptotic cell-derived antigens. Oppositely, the RP S19 dimer inhibits C5a-induced neutrophil migration and promotes apoptosis of neutrophils via the C5a receptor. The RP S19 dimer seems to prevent excessive tissue destruction induced by neutrophils. Skp is a molecular chaperon of Gram-negative bacteria. Skp also attracts monocytes and neutrophils as a ligand of C5a receptor. However, it promotes neither cytoplasmic Ca(2+) enhancement nor radical oxygen generation.
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Affiliation(s)
- Tetsuro Yamamoto
- Department of Molecular Pathology, Faculty of Medical and Pharmaceutical Sciences, Kumamoto University Graduate School, Honjo, Kumamoto, Japan.
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39
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Abstract
Opioids are the most effective and widely used drugs in the treatment of severe pain. They act through G protein-coupled receptors. Four families of endogenous ligands (opioid peptides) are known. The standard exogenous opioid analgesic is morphine. Opioid agonists can activate central and peripheral opioid receptors. Three classes of opioid receptors (mu, delta, kappa) have been identified. Multiple pathways ofopioid receptor signaling (e.g., G(i/o) coupling, cAMP inhibition, Ca++ channel inhibition) have been described. The differential regulation of effectors, preclinical pharmacology, clinical applications, and side effects will be reviewed in this chapter.
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Affiliation(s)
- C Zöllner
- Klinik für Anaesthesiologie und operative Intensivmedizin, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12200 Berlin, Germany
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40
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Fanelli F, De Benedetti PG. Computational Modeling Approaches to Structure−Function Analysis of G Protein-Coupled Receptors. Chem Rev 2005; 105:3297-351. [PMID: 16159154 DOI: 10.1021/cr000095n] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Francesca Fanelli
- Dulbecco Telethon Institute and Department of Chemistry, University of Modena and Reggio Emilia, via Campi 183, 41100 Modena, Italy.
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