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Lung H, Wentworth KL, Moody T, Zamarioli A, Ram A, Ganesh G, Kang M, Ho S, Hsiao EC. Wnt pathway inhibition with the porcupine inhibitor LGK974 decreases trabecular bone but not fibrosis in a murine model with fibrotic bone. JBMR Plus 2024; 8:ziae011. [PMID: 38577521 PMCID: PMC10994528 DOI: 10.1093/jbmrpl/ziae011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 12/22/2023] [Accepted: 01/08/2024] [Indexed: 04/06/2024] Open
Abstract
G protein-coupled receptors (GPCRs) mediate a wide spectrum of physiological functions, including the development, remodeling, and repair of the skeleton. Fibrous dysplasia (FD) of the bone is characterized by fibrotic, expansile bone lesions caused by activating mutations in GNAS. There are no effective therapies for FD. We previously showed that ColI(2.3)+/Rs1+ mice, in which Gs-GPCR signaling was hyper-activated in osteoblastic cell lineages using an engineered receptor strategy, developed a fibrotic bone phenotype with trabecularization that could be reversed by normalizing Gs-GPCR signaling, suggesting that targeting the Gs-GPCR or components of the downstream signaling pathway could serve as a promising therapeutic strategy for FD. The Wnt signaling pathway has been implicated in the pathogenesis of FD-like bone, but the specific Wnts and which cells produce them remain largely unknown. Single-cell RNA sequencing on long-bone stromal cells of 9-wk-old male ColI(2.3)+/Rs1+ mice and littermate controls showed that fibroblastic stromal cells in ColI(2.3)+/Rs1+ mice were expanded. Multiple Wnt ligands were up- or downregulated in different cellular populations, including in non-osteoblastic cells. Treatment with the porcupine inhibitor LGK974, which blocks Wnt signaling broadly, induced partial resorption of the trabecular bone in the femurs of ColI(2.3)+/Rs1+ mice, but no significant changes in the craniofacial skeleton. Bone fibrosis remained evident after treatment. Notably, LGK974 caused significant bone loss in control mice. These results provide new insights into the role of Wnt and Gs-signaling in fibrosis and bone formation in a mouse model of Gs-GPCR pathway overactivation.
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Affiliation(s)
- Hsuan Lung
- Department of Medicine, Division of Endocrinology and Metabolism, The Institute for Human Genetics, and the Eli and Edythe Broad Institute for Regeneration Medicine, University of California, San Francisco, CA 94143, United States
- Oral and Craniofacial Sciences Graduate Program, School of Dentistry, University of California, San Francisco, CA 94143, United States
- Department of Dentistry, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung 833, Taiwan
- School of Dentistry, Institute of Oral Medicine, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan
| | - Kelly L Wentworth
- Department of Medicine, Division of Endocrinology and Metabolism, The Institute for Human Genetics, and the Eli and Edythe Broad Institute for Regeneration Medicine, University of California, San Francisco, CA 94143, United States
- Department of Medicine, Division of Endocrinology and Metabolism, University of California, Zuckerberg San Francisco General Hospital, San Francisco, CA 94143, United States
| | - Tania Moody
- Department of Medicine, Division of Endocrinology and Metabolism, The Institute for Human Genetics, and the Eli and Edythe Broad Institute for Regeneration Medicine, University of California, San Francisco, CA 94143, United States
| | - Ariane Zamarioli
- Department of Medicine, Division of Endocrinology and Metabolism, The Institute for Human Genetics, and the Eli and Edythe Broad Institute for Regeneration Medicine, University of California, San Francisco, CA 94143, United States
- Department of Orthopaedics and Anesthesiology, Ribeirao Preto Medical School, University of Sao Paulo, Sao Paulo (SP) 14049-900, Brazil
| | - Apsara Ram
- Department of Medicine, Division of Endocrinology and Metabolism, The Institute for Human Genetics, and the Eli and Edythe Broad Institute for Regeneration Medicine, University of California, San Francisco, CA 94143, United States
| | - Gauri Ganesh
- Department of Medicine, Division of Endocrinology and Metabolism, The Institute for Human Genetics, and the Eli and Edythe Broad Institute for Regeneration Medicine, University of California, San Francisco, CA 94143, United States
| | - Misun Kang
- Oral and Craniofacial Sciences Graduate Program, School of Dentistry, University of California, San Francisco, CA 94143, United States
| | - Sunita Ho
- Oral and Craniofacial Sciences Graduate Program, School of Dentistry, University of California, San Francisco, CA 94143, United States
| | - Edward C Hsiao
- Department of Medicine, Division of Endocrinology and Metabolism, The Institute for Human Genetics, and the Eli and Edythe Broad Institute for Regeneration Medicine, University of California, San Francisco, CA 94143, United States
- Oral and Craniofacial Sciences Graduate Program, School of Dentistry, University of California, San Francisco, CA 94143, United States
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Newman-Tancredi A, Depoortère RY, Kleven MS, Kołaczkowski M, Zimmer L. Translating biased agonists from molecules to medications: Serotonin 5-HT 1A receptor functional selectivity for CNS disorders. Pharmacol Ther 2021; 229:107937. [PMID: 34174274 DOI: 10.1016/j.pharmthera.2021.107937] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 06/01/2021] [Accepted: 06/17/2021] [Indexed: 12/18/2022]
Abstract
Biased agonism (or "functional selectivity") at G-protein-coupled receptors has attracted rapidly increasing interest as a means to improve discovery of more efficacious and safer pharmacotherapeutics. However, most studies are limited to in vitro tests of cellular signaling and few biased agonists have progressed to in vivo testing. As concerns 5-HT1A receptors, which exert a major control of serotonergic signaling in diverse CNS regions, study of biased agonism has previously been limited by the poor target selectivity and/or partial agonism of classically available ligands. However, a new generation of highly selective, efficacious and druggable agonists has advanced the study of biased agonism at this receptor and created new therapeutic opportunities. These novel agonists show differential properties for G-protein signaling, cellular signaling (particularly pERK), electrophysiological effects, neurotransmitter release, neuroimaging by PET and pharmacoMRI, and behavioral tests of mood, motor activity and side effects. Overall, NLX-101 (a.k.a. F15599) exhibits preferential activation of cortical and brain stem 5-HT1A receptors, whereas NLX-112 (a.k.a. befiradol or F13640) shows prominent activation of 5-HT1A autoreceptors in Raphe nuclei and in regions associated with motor control. Accordingly, NLX-101 is potently active in rodent models of depression and respiratory control, whereas NLX-112 shows promising activity in models of Parkinson's disease across several species - rat, marmoset and macaque. Moreover, NLX-112 has also been labeled with 18F to produce the first agonist PET radiopharmaceutical (known as [18F]-F13640) for investigation of the active state of 5-HT1A receptors in rodent, primate and human. The structure-functional activity relationships of biased agonists have been investigated by receptor modeling and novel compounds have been identified which exhibit increased affinity at 5-HT1A receptors and new profiles of cellular signaling bias, notably for β-arrestin recruitment versus pERK. Taken together, the data suggest that 5-HT1A receptor biased agonists constitute potentially superior pharmacological agents for treatment of CNS disorders involving serotonergic mechanisms.
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Affiliation(s)
| | | | | | | | - Luc Zimmer
- Université Claude Bernard Lyon1, Lyon, France; Hospices Civils de Lyon, Lyon, France; Lyon Neuroscience Research Center, CNRS-INSERM, France
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3
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van Gastel J, Leysen H, Boddaert J, Vangenechten L, Luttrell LM, Martin B, Maudsley S. Aging-related modifications to G protein-coupled receptor signaling diversity. Pharmacol Ther 2020; 223:107793. [PMID: 33316288 DOI: 10.1016/j.pharmthera.2020.107793] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 11/26/2020] [Indexed: 02/06/2023]
Abstract
Aging is a highly complex molecular process, affecting nearly all tissue systems in humans and is the highest risk factor in developing neurodegenerative disorders such as Alzheimer's and Parkinson's disease, cardiovascular disease and Type 2 diabetes mellitus. The intense complexity of the aging process creates an incentive to develop more specific drugs that attenuate or even reverse some of the features of premature aging. As our current pharmacopeia is dominated by therapeutics that target members of the G protein-coupled receptor (GPCR) superfamily it may be prudent to search for effective anti-aging therapeutics in this fertile domain. Since the first demonstration of GPCR-based β-arrestin signaling, it has become clear that an enhanced appreciation of GPCR signaling diversity may facilitate the creation of therapeutics with selective signaling activities. Such 'biased' ligand signaling profiles can be effectively investigated using both standard molecular biological techniques as well as high-dimensionality data analyses. Through a more nuanced appreciation of the quantitative nature across the multiple dimensions of signaling bias that drugs possess, researchers may be able to further refine the efficacy of GPCR modulators to impact the complex aberrations that constitute the aging process. Identifying novel effector profiles could expand the effective pharmacopeia and assist in the design of precision medicines. This review discusses potential non-G protein effectors, and specifically their potential therapeutic suitability in aging and age-related disorders.
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Affiliation(s)
- Jaana van Gastel
- Receptor Biology Lab, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium; Faculty of Pharmacy, Biomedical and Veterinary Science, University of Antwerp, Antwerp, Belgium
| | - Hanne Leysen
- Receptor Biology Lab, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium; Faculty of Pharmacy, Biomedical and Veterinary Science, University of Antwerp, Antwerp, Belgium
| | - Jan Boddaert
- Molecular Pathology Group, Faculty of Medicine and Health Sciences, Laboratory of Cell Biology and Histology, Antwerp, Belgium
| | - Laura Vangenechten
- Receptor Biology Lab, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Louis M Luttrell
- Division of Endocrinology, Diabetes & Medical Genetics, Medical University of South Carolina, USA
| | - Bronwen Martin
- Faculty of Pharmacy, Biomedical and Veterinary Science, University of Antwerp, Antwerp, Belgium
| | - Stuart Maudsley
- Receptor Biology Lab, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium; Faculty of Pharmacy, Biomedical and Veterinary Science, University of Antwerp, Antwerp, Belgium.
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4
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Kang P, Li X, Liu Y, Shiers SI, Xiong H, Giannotta M, Dejana E, Price TJ, Randrianalisoa J, Nielsen SO, Qin Z. Transient Photoinactivation of Cell Membrane Protein Activity without Genetic Modification by Molecular Hyperthermia. ACS NANO 2019; 13:12487-12499. [PMID: 31613606 PMCID: PMC7096286 DOI: 10.1021/acsnano.9b01993] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Precise manipulation of protein activity in living systems has broad applications in biomedical sciences. However, it is challenging to use light to manipulate protein activity in living systems without genetic modification. Here, we report a technique to optically switch off protein activity in living cells with high spatiotemporal resolution, referred to as molecular hyperthermia (MH). MH is based on the nanoscale-confined heating of plasmonic gold nanoparticles by short laser pulses to unfold and photoinactivate targeted proteins of interest. First, we show that protease-activated receptor 2 (PAR2), a G-protein-coupled receptor and an important pathway that leads to pain sensitization, can be photoinactivated in situ by MH without compromising cell proliferation. PAR2 activity can be switched off in laser-targeted cells without affecting surrounding cells. Furthermore, we demonstrate the molecular specificity of MH by inactivating PAR2 while leaving other receptors intact. Second, we demonstrate that the photoinactivation of a tight junction protein in brain endothelial monolayers leads to a reversible blood-brain barrier opening in vitro. Lastly, the protein inactivation by MH is below the nanobubble generation threshold and thus is predominantly due to the nanoscale heating. MH is distinct from traditional hyperthermia (that induces global tissue heating) in both its time and length scales: nanoseconds versus seconds, nanometers versus millimeters. Our results demonstrate that MH enables selective and remote manipulation of protein activity and cellular behavior without genetic modification.
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Affiliation(s)
- Peiyuan Kang
- Department of Mechanical Engineering, University of Texas at Dallas, 800 West Campbell Rd., Richardson, Texas 75080, USA
| | - Xiaoqing Li
- Department of Bioengineering, University of Texas at Dallas, 800 West Campbell Rd., Richardson, Texas 75080, USA
| | - Yaning Liu
- Department of Mechanical Engineering, University of Texas at Dallas, 800 West Campbell Rd., Richardson, Texas 75080, USA
| | - Stephanie I. Shiers
- School of Behavioral and Brain Sciences, University of Texas at Dallas, 800 West Campbell Rd., Richardson, Texas 75080, USA
| | - Hejian Xiong
- Department of Mechanical Engineering, University of Texas at Dallas, 800 West Campbell Rd., Richardson, Texas 75080, USA
| | - Monica Giannotta
- Vascular Biology Laboratory, The FIRC Institute of Molecular Oncology (IFOM), 20139 Milan, Italy
| | - Elisabetta Dejana
- Vascular Biology Laboratory, The FIRC Institute of Molecular Oncology (IFOM), 20139 Milan, Italy
- Department of Immunology, Genetics and Pathology, University of Uppsala, 751 05 Uppsala, Sweden
| | - Theodore John Price
- School of Behavioral and Brain Sciences, University of Texas at Dallas, 800 West Campbell Rd., Richardson, Texas 75080, USA
| | - Jaona Randrianalisoa
- Institut de Thermique, Mécanique, Matériaux (ITheMM EA 7548), University of Reims Champagne-Ardenne, Reims Cedex 2, 51687 France
| | - Steven O. Nielsen
- Department of Chemistry and Biochemistry, University of Texas at Dallas, 800 West Campbell Rd., Richardson, Texas 75080, USA
| | - Zhenpeng Qin
- Department of Mechanical Engineering, University of Texas at Dallas, 800 West Campbell Rd., Richardson, Texas 75080, USA
- Department of Bioengineering, University of Texas at Dallas, 800 West Campbell Rd., Richardson, Texas 75080, USA
- Department of Surgery, University of Texas at Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas 75390, USA
- Corresponding Author: . Phone: (972)883-4440
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Biomimetic Membranes with Transmembrane Proteins: State-of-the-Art in Transmembrane Protein Applications. Int J Mol Sci 2019; 20:ijms20061437. [PMID: 30901910 PMCID: PMC6472214 DOI: 10.3390/ijms20061437] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 02/26/2019] [Accepted: 03/13/2019] [Indexed: 12/14/2022] Open
Abstract
In biological cells, membrane proteins are the most crucial component for the maintenance of cell physiology and processes, including ion transportation, cell signaling, cell adhesion, and recognition of signal molecules. Therefore, researchers have proposed a number of membrane platforms to mimic the biological cell environment for transmembrane protein incorporation. The performance and selectivity of these transmembrane proteins based biomimetic platforms are far superior to those of traditional material platforms, but their lack of stability and scalability rule out their commercial presence. This review highlights the development of transmembrane protein-based biomimetic platforms for four major applications, which are biosensors, molecular interaction studies, energy harvesting, and water purification. We summarize the fundamental principles and recent progress in transmembrane protein biomimetic platforms for each application, discuss their limitations, and present future outlooks for industrial implementation.
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Lung H, Hsiao EC, Wentworth KL. Advances in Models of Fibrous Dysplasia/McCune-Albright Syndrome. Front Endocrinol (Lausanne) 2019; 10:925. [PMID: 32038487 PMCID: PMC6993052 DOI: 10.3389/fendo.2019.00925] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 12/18/2019] [Indexed: 11/13/2022] Open
Abstract
The Gs G-protein coupled receptor pathway is a critical regulator of normal bone formation and function. The Gs pathway increases intracellular cAMP levels by ultimately acting on adenylate cyclase. McCune-Albright Syndrome (MAS) and fibrous dysplasia (FD) of the bone are two proto-typical conditions that result from increased cellular Gs signaling activity. Both are caused by somatic activating mutations in the GNAS gene that encodes for the Gsα subunit. FD bone lesions are particularly difficult to treat because of their variability and because of the lack of effective medical therapies. In this review, we briefly discuss the key clinical presentations of FD/MAS. We also review the current status of mouse models that target the Gs GPCR signaling pathway and human cellular models for FD/MAS. These powerful tools and our improving clinical knowledge will allow further elucidation of the roles of GPCR signaling in FD/MS pathogenesis, and facilitate the development of novel therapies for these medically significant conditions.
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Affiliation(s)
- Hsuan Lung
- Division of Endocrinology and Metabolism and the Institute for Human Genetics, Department of Medicine, University of California, San Francisco, San Francisco, CA, United States
- Oral and Craniofacial Sciences Graduate Program, School of Dentistry, University of California, San Francisco, San Francisco, CA, United States
- Department of Dentistry, Chang Gung Memorial Hospital and College of Medicine, Chang Gung University, Kaohsiung, Taiwan
| | - Edward C. Hsiao
- Division of Endocrinology and Metabolism and the Institute for Human Genetics, Department of Medicine, University of California, San Francisco, San Francisco, CA, United States
- Oral and Craniofacial Sciences Graduate Program, School of Dentistry, University of California, San Francisco, San Francisco, CA, United States
- *Correspondence: Edward C. Hsiao
| | - Kelly L. Wentworth
- Division of Endocrinology and Metabolism and the Institute for Human Genetics, Department of Medicine, University of California, San Francisco, San Francisco, CA, United States
- Division of Endocrinology and Metabolism, Zuckerberg San Francisco General Hospital, University of California, San Francisco, San Francisco, CA, United States
- Kelly L. Wentworth
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7
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Abstract
Lipids are potent signaling molecules that regulate a multitude of cellular responses, including cell growth and death and inflammation/infection, via receptor-mediated pathways. Derived from polyunsaturated fatty acids (PUFAs), such as arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), each lipid displays unique properties, thus making their role in inflammation distinct from that of other lipids derived from the same PUFA. This diversity arises from their synthesis, which occurs via discrete enzymatic pathways and because they elicit responses via different receptors. This review will collate the bioactive lipid research to date and summarize the major pathways involved in their biosynthesis and role in inflammation. Specifically, lipids derived from AA (prostanoids, leukotrienes, 5-oxo-6,8,11,14-eicosatetraenoic acid, lipoxins, and epoxyeicosatrienoic acids), EPA (E-series resolvins), and DHA (D-series resolvins, protectins, and maresins) will be discussed herein.
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8
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Capra V, Mauri M, Guzzi F, Busnelli M, Accomazzo MR, Gaussem P, Nisar SP, Mundell SJ, Parenti M, Rovati GE. Impaired thromboxane receptor dimerization reduces signaling efficiency: A potential mechanism for reduced platelet function in vivo. Biochem Pharmacol 2016; 124:43-56. [PMID: 27845050 DOI: 10.1016/j.bcp.2016.11.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 11/10/2016] [Indexed: 12/16/2022]
Abstract
Thromboxane A2 is a potent mediator of inflammation and platelet aggregation exerting its effects through the activation of a G protein-coupled receptor (GPCR), termed TP. Although the existence of dimers/oligomers in Class A GPCRs is widely accepted, their functional significance still remains controversial. Recently, we have shown that TPα and TPβ homo-/hetero-dimers interact through an interface of residues in transmembrane domain 1 (TM1) whose disruption impairs dimer formation. Here, biochemical and pharmacological characterization of this dimer deficient mutant (DDM) in living cells indicates a significant impairment in its response to agonists. Interestingly, two single loss-of-function TPα variants, namely W29C and N42S recently identified in two heterozygous patients affected by bleeding disorders, match some of the residues mutated in our DDM. These two naturally occurring variants display a reduced potency to TP agonists and are characterized by impaired dimer formation in transfected HEK-293T cells. These findings provide proofs that lack of homo-dimer formation is a crucial process for reduced TPα function in vivo, and might represent one molecular mechanism through which platelet TPα receptor dysfunction affects the patient(s) carrying these mutations.
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Key Words
- (Z)-7-[(1R,2R,3R,4S)-3-[[2-(phenylcarbamoyl)hydrazinyl]methyl]-7-oxabicyclo[2.2.1]heptan-2-yl]hept-5-enoic acid
- (Z)-7-[(1S,2S,3R,4R)-3-[(E,3S)-3-hydroxyoct-1-enyl]-5-oxabicyclo[2.2.1]heptan-2-yl]hept-5-enoic acid
- (Z)-7-[(1S,2S,3S,4R)-3-[(E,3R)-3-hydroxy-4-(4-iodophenoxy)but-1-enyl]-7-oxabicyclo[2.2.1]heptan-2-yl]hept-5-enoic acid
- (Z)-7-[(1S,3R,4R,5S)-3-[(E,3R)-3-hydroxyoct-1-enyl]-6,6-dimethyl-4-bicyclo[3.1.1]heptanyl]hept-5-enoic acid
- 3-[(3R)-3-[(4-fluorophenyl)sulfonylamino]-1,2,3,4-tetrahydrocarbazol-9-yl]propanoic acid
- Eicosanoids
- G protein coupled receptors
- I-BOP (PubChem CID: 51015454)
- Pinane Thromboxane A2 (PTA2) (PubChem CID: 25834471)
- Platelets
- Ramatroban (PubChem CID: 123879)
- Receptor dimer
- SQ29,548 (PubChem CID: 6437074)
- Signal transduction
- Thromboxane A(2)
- U46619 (PubChem CID: 5311493)
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Affiliation(s)
- Valérie Capra
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milano, Italy; Department of Health Science, University of Milan, Milano, Italy.
| | - Mario Mauri
- Department of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy.
| | - Francesca Guzzi
- Department of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy.
| | - Marta Busnelli
- CNR, Institute of Neuroscience, University of Milan, Milan, Italy; Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy.
| | - Maria Rosa Accomazzo
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milano, Italy.
| | - Pascale Gaussem
- Inserm UMR-S1140, Faculte' de Pharmacie, Université Paris Descartes, Sorbonne Paris Cité, Paris and AP-HP, Hopital Européen Georges Pompidou, Service d'Hématologie Biologique, Paris, France.
| | - Shaista P Nisar
- School of Physiology and Pharmacology, University of Bristol, Bristol BS8 1TD, UK.
| | - Stuart J Mundell
- School of Physiology and Pharmacology, University of Bristol, Bristol BS8 1TD, UK.
| | - Marco Parenti
- Department of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy.
| | - G Enrico Rovati
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milano, Italy.
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Mechanism of action of pimavanserin in Parkinson's disease psychosis: targeting serotonin 5HT2A and 5HT2C receptors. CNS Spectr 2016; 21:271-5. [PMID: 27503570 DOI: 10.1017/s1092852916000407] [Citation(s) in RCA: 195] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Pimavanserin, a novel agent approved for the treatment of Parkinson's disease psychosis, has potent actions as an antagonist/inverse agonist at serotonin 5HT2A receptors and less potent antagonist/inverse agonist actions at 5HT2C receptors.
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Katz S, Ernst O, Avni D, Athamna M, Philosoph A, Arana L, Ouro A, Hoeferlin LA, Meijler MM, Chalfant CE, Gómez-Muñoz A, Zor T. Exogenous ceramide-1-phosphate (C1P) and phospho-ceramide analogue-1 (PCERA-1) regulate key macrophage activities via distinct receptors. Immunol Lett 2015; 169:73-81. [PMID: 26656944 DOI: 10.1016/j.imlet.2015.12.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 11/17/2015] [Accepted: 12/01/2015] [Indexed: 11/25/2022]
Abstract
Inflammation is an ensemble of tightly regulated steps, in which macrophages play an essential role. Previous reports showed that the natural sphingolipid ceramide 1-phosphate (C1P) stimulates macrophages migration, while the synthetic C1P mimic, phospho-ceramide analogue-1 (PCERA-1), suppresses production of the key pro-inflammatory cytokine TNFα and amplifies production of the key anti-inflammatory cytokine IL-10 in LPS-stimulated macrophages, via one or more unidentified G-protein coupled receptors. We show that C1P stimulated RAW264.7 macrophages migration via the NFκB pathway and MCP-1 induction, while PCERA-1 neither mimicked nor antagonized these activities. Conversely, PCERA-1 synergistically elevated LPS-dependent IL-10 expression in RAW264.7 macrophages via the cAMP-PKA-CREB signaling pathway, while C1P neither mimicked nor antagonized these activities. Interestingly, both compounds have the capacity to additively inhibit TNFα secretion; PCERA-1, but not C1P, suppressed LPS-induced TNFα expression in macrophages in a CREB-dependent manner, while C1P, but not PCERA-1, directly inhibited recombinant TNFα converting enzyme (TACE). Finally, PCERA-1 failed to interfere with binding of C1P to either the cell surface receptor or to TACE. These results thus indicate that the natural sphingolipid C1P and its synthetic analog PCERA-1 bind and activate distinct receptors expressed in RAW264.7 macrophages. Identification of these receptors will be instrumental for elucidation of novel activities of extra-cellular sphingolipids, and may pave the way for the design of new sphingolipid mimics for the treatment of inflammatory diseases, and pathologies which depend on cell migration, as in metastatic tumors.
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Affiliation(s)
- Sebastián Katz
- Department of Biochemistry & Molecular Biology, Life Sciences Institute, Tel-Aviv University, Tel-Aviv 69978, Israel.
| | - Orna Ernst
- Department of Biochemistry & Molecular Biology, Life Sciences Institute, Tel-Aviv University, Tel-Aviv 69978, Israel.
| | - Dorit Avni
- Department of Biochemistry & Molecular Biology, Life Sciences Institute, Tel-Aviv University, Tel-Aviv 69978, Israel.
| | - Muhammad Athamna
- Department of Biochemistry & Molecular Biology, Life Sciences Institute, Tel-Aviv University, Tel-Aviv 69978, Israel.
| | - Amir Philosoph
- Department of Biochemistry & Molecular Biology, Life Sciences Institute, Tel-Aviv University, Tel-Aviv 69978, Israel.
| | - Lide Arana
- Department of Biochemistry & Molecular Biology, University of the Basque Country, P.O. Box 644, Bilbao 48080, Spain.
| | - Alberto Ouro
- Department of Biochemistry & Molecular Biology, University of the Basque Country, P.O. Box 644, Bilbao 48080, Spain.
| | - L Alexis Hoeferlin
- Department of Biochemistry & Molecular Biology, Virginia Commonwealth University, Richmond, VA 23298-0614, United States; Hunter Holmes McGuire Veterans Administration Medical Center, Richmond, VA 23249, United States; The Massey Cancer Center, Richmond, VA 23298, United States.
| | - Michael M Meijler
- Department of Chemistry, Ben-Gurion University of the Negev, Be'er-Sheva 84105, Israel.
| | - Charles E Chalfant
- Department of Biochemistry & Molecular Biology, Virginia Commonwealth University, Richmond, VA 23298-0614, United States; Hunter Holmes McGuire Veterans Administration Medical Center, Richmond, VA 23249, United States; The Massey Cancer Center, Richmond, VA 23298, United States.
| | - Antonio Gómez-Muñoz
- Department of Biochemistry & Molecular Biology, University of the Basque Country, P.O. Box 644, Bilbao 48080, Spain.
| | - Tsaffrir Zor
- Department of Biochemistry & Molecular Biology, Life Sciences Institute, Tel-Aviv University, Tel-Aviv 69978, Israel.
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Janssens J, Etienne H, Idriss S, Azmi A, Martin B, Maudsley S. Systems-Level G Protein-Coupled Receptor Therapy Across a Neurodegenerative Continuum by the GLP-1 Receptor System. Front Endocrinol (Lausanne) 2014; 5:142. [PMID: 25225492 PMCID: PMC4150252 DOI: 10.3389/fendo.2014.00142] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 08/14/2014] [Indexed: 12/31/2022] Open
Abstract
With our increasing appreciation of the true complexity of diseases and pathophysiologies, it is clear that this knowledge needs to inform the future development of pharmacotherapeutics. For many disorders, the disease mechanism itself is a complex process spanning multiple signaling networks, tissues, and organ systems. Identifying the precise nature and locations of the pathophysiology is crucial for the creation of systemically effective drugs. Diseases once considered constrained to a limited range of organ systems, e.g., central neurodegenerative disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington' disease (HD), the role of multiple central and peripheral organ systems in the etiology of such diseases is now widely accepted. With this knowledge, it is increasingly clear that these seemingly distinct neurodegenerative disorders (AD, PD, and HD) possess multiple pathophysiological similarities thereby demonstrating an inter-related continuum of disease-related molecular alterations. With this systems-level appreciation of neurodegenerative diseases, it is now imperative to consider that pharmacotherapeutics should be developed specifically to address the systemic imbalances that create the disorders. Identification of potential systems-level signaling axes may facilitate the generation of therapeutic agents with synergistic remedial activity across multiple tissues, organ systems, and even diseases. Here, we discuss the potentially therapeutic systems-level interaction of the glucagon-like peptide 1 (GLP-1) ligand-receptor axis with multiple aspects of the AD, PD, and HD neurodegenerative continuum.
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Affiliation(s)
- Jonathan Janssens
- Translational Neurobiology Group, VIB Department of Molecular Genetics, University of Antwerp, Antwerp, Belgium
| | - Harmonie Etienne
- Translational Neurobiology Group, VIB Department of Molecular Genetics, University of Antwerp, Antwerp, Belgium
| | - Sherif Idriss
- Translational Neurobiology Group, VIB Department of Molecular Genetics, University of Antwerp, Antwerp, Belgium
| | - Abdelkrim Azmi
- Translational Neurobiology Group, VIB Department of Molecular Genetics, University of Antwerp, Antwerp, Belgium
| | - Bronwen Martin
- Metabolism Unit, National Institute on Aging, National Institutes of Health, Bethesda, MD, USA
| | - Stuart Maudsley
- Translational Neurobiology Group, VIB Department of Molecular Genetics, University of Antwerp, Antwerp, Belgium
- *Correspondence: Stuart Maudsley, Translational Neurobiology Group, VIB Department of Molecular Genetics, University of Antwerp, Universiteitsplein 1, Building V, Antwerpen B2610, Belgium e-mail:
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12
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Clarke WP, Chavera TA, Silva M, Sullivan LC, Berg KA. Signalling profile differences: paliperidone versus risperidone. Br J Pharmacol 2013; 170:532-45. [PMID: 23826915 PMCID: PMC3791992 DOI: 10.1111/bph.12295] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 06/20/2013] [Accepted: 06/25/2013] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND AND PURPOSE Paliperidone is an active metabolite of the second-generation atypical antipsychotic, risperidone recently approved for the treatment of schizophrenia and schizoaffective disorder. Because paliperidone differs from risperidone by only a single hydroxyl group, questions have been raised as to whether there are significant differences in the effects elicited between these two drugs. EXPERIMENTAL APPROACH We compared the relative efficacies of paliperidone versus risperidone to regulate several cellular signalling pathways coupled to four selected GPCR targets that are important for either therapeutic or adverse effects: human dopamine D2 , human serotonin 2A receptor subtype (5-HT2A ), human serotonin 2C receptor subtype and human histamine H1 receptors. KEY RESULTS Whereas the relative efficacies of paliperidone and risperidone were the same for some responses, significant differences were found for several receptor-signalling systems, with paliperidone having greater or less relative efficacy than risperidone depending upon the receptor-response pair. Interestingly, for 5-HT2A -mediated recruitment of β-arrestin, 5-HT2A -mediated sensitization of ERK, and dopamine D2 -mediated sensitization of adenylyl cyclase signalling, both paliperidone and risperidone behaved as agonists. CONCLUSIONS AND IMPLICATIONS These results suggest that the single hydroxyl group of paliperidone promotes receptor conformations that can differ from those of risperidone leading to differences in the spectrum of regulation of cellular signal transduction cascades. Such differences in signalling at the cellular level could lead to differences between paliperidone and risperidone in therapeutic efficacy or in the generation of adverse effects.
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MESH Headings
- Adenylyl Cyclases/metabolism
- Animals
- Antipsychotic Agents/chemistry
- Antipsychotic Agents/pharmacology
- Arrestins/metabolism
- CHO Cells
- Cricetinae
- Cricetulus
- Dopamine Agonists/pharmacology
- Dose-Response Relationship, Drug
- Drug Inverse Agonism
- Extracellular Signal-Regulated MAP Kinases/metabolism
- Histamine Agonists/pharmacology
- Humans
- Isoxazoles/chemistry
- Isoxazoles/pharmacology
- Molecular Structure
- Paliperidone Palmitate
- Pyrimidines/chemistry
- Pyrimidines/pharmacology
- Receptor, Serotonin, 5-HT2A/drug effects
- Receptor, Serotonin, 5-HT2A/genetics
- Receptor, Serotonin, 5-HT2A/metabolism
- Receptor, Serotonin, 5-HT2C/drug effects
- Receptor, Serotonin, 5-HT2C/genetics
- Receptor, Serotonin, 5-HT2C/metabolism
- Receptors, Dopamine D2/drug effects
- Receptors, Dopamine D2/genetics
- Receptors, Dopamine D2/metabolism
- Receptors, Histamine H1/drug effects
- Receptors, Histamine H1/genetics
- Receptors, Histamine H1/metabolism
- Risperidone/chemistry
- Risperidone/pharmacology
- Serotonin Receptor Agonists/pharmacology
- Signal Transduction/drug effects
- Structure-Activity Relationship
- Transfection
- beta-Arrestins
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Affiliation(s)
- W P Clarke
- Department of Pharmacology, University of Texas Health Science Center, San Antonio, TX, USA
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13
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Systems Analysis of Arrestin Pathway Functions. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 118:431-67. [DOI: 10.1016/b978-0-12-394440-5.00017-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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14
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Martin B, Chadwick W, Yi T, Park SS, Lu D, Ni B, Gadkaree S, Farhang K, Becker KG, Maudsley S. VENNTURE--a novel Venn diagram investigational tool for multiple pharmacological dataset analysis. PLoS One 2012; 7:e36911. [PMID: 22606307 PMCID: PMC3351456 DOI: 10.1371/journal.pone.0036911] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 04/10/2012] [Indexed: 12/24/2022] Open
Abstract
As pharmacological data sets become increasingly large and complex, new visual analysis and filtering programs are needed to aid their appreciation. One of the most commonly used methods for visualizing biological data is the Venn diagram. Currently used Venn analysis software often presents multiple problems to biological scientists, in that only a limited number of simultaneous data sets can be analyzed. An improved appreciation of the connectivity between multiple, highly-complex datasets is crucial for the next generation of data analysis of genomic and proteomic data streams. We describe the development of VENNTURE, a program that facilitates visualization of up to six datasets in a user-friendly manner. This program includes versatile output features, where grouped data points can be easily exported into a spreadsheet. To demonstrate its unique experimental utility we applied VENNTURE to a highly complex parallel paradigm, i.e. comparison of multiple G protein-coupled receptor drug dose phosphoproteomic data, in multiple cellular physiological contexts. VENNTURE was able to reliably and simply dissect six complex data sets into easily identifiable groups for straightforward analysis and data output. Applied to complex pharmacological datasets, VENNTURE's improved features and ease of analysis are much improved over currently available Venn diagram programs. VENNTURE enabled the delineation of highly complex patterns of dose-dependent G protein-coupled receptor activity and its dependence on physiological cellular contexts. This study highlights the potential for such a program in fields such as pharmacology, genomics, and bioinformatics.
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Affiliation(s)
- Bronwen Martin
- Metabolism Unit, Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Wayne Chadwick
- Receptor Pharmacology Unit, Laboratory of Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Tie Yi
- Metabolism Unit, Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Sung-Soo Park
- Receptor Pharmacology Unit, Laboratory of Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Daoyuan Lu
- Receptor Pharmacology Unit, Laboratory of Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Bin Ni
- Receptor Pharmacology Unit, Laboratory of Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Shekhar Gadkaree
- Diabetes Section, Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Kathleen Farhang
- Diabetes Section, Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Kevin G. Becker
- Gene Expression and Genomics Unit, Research Resources Branch, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Stuart Maudsley
- Receptor Pharmacology Unit, Laboratory of Neuroscience, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
- * E-mail:
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Hsiao EC, Nguyen TD, Ng JK, Scott MJ, Chang WC, Zahed H, Conklin BR. Constitutive Gs activation using a single-construct tetracycline-inducible expression system in embryonic stem cells and mice. Stem Cell Res Ther 2011; 2:11. [PMID: 21375737 PMCID: PMC3226282 DOI: 10.1186/scrt52] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2010] [Accepted: 03/04/2011] [Indexed: 01/19/2023] Open
Abstract
INTRODUCTION The controlled expression of many genes, including G-protein coupled receptors (GPCRs), is important for delineating gene functions in complex model systems. Binary systems for inducible regulation of transgene expression are widely used in mice. One system is the tTA/TRE expression system, composed of a tetracycline-dependent DNA binding factor and a separate tetracycline operon. However, the requirement for two separate transgenes (one for each tTA or TRE component) makes this system less amenable to models requiring directed cell targeting, increases the risk of multiple transgene integration sites, and requires extensive screening for appropriately-functioning clones. METHODS We developed a single, polycistronic tetracycline-inducible expression platform to control the expression of multiple cistrons in mammalian cells. This platform has three basic constructs: regulator, responder, and destination vectors. The modular platform is compatible with both the TetOff (tTA) and TetOn (rtTA) systems. The modular Gateway recombineering-compatible components facilitate rapidly generating vectors to genetically modify mammalian cells. We apply this system to use the elongation factor 1α (EF1α) promoter to drive doxycycline-regulated expression of both the fluorescent marker mCherry and an engineered Gs-coupled GPCR "Rs1" separated by a 2A ribosomal skip site. RESULTS We show that our combined expression construct drives expression of both the mCherry and Rs1 transgenes in a doxycycline-dependent manner. We successfully target the expression construct into the Rosa26 locus of mouse embryonic stem (ES) cells. Rs1 expression in mouse ES cells increases cAMP accumulation via both basal and ligand-induced Gs mechanisms and is associated with increased embryoid body size. Heterozygous mice carrying the Rs1 expression construct showed normal growth and weight, and developed small increases in bone formation that could be observed in the calvaria. CONCLUSIONS Our results demonstrate the feasibility of a single-vector strategy that combines both the tTA and TRE tetracycline-regulated components for use in cells and mouse models. Although the EF1α promoter is useful for driving expression in pluripotent cells, a single copy of the EF1α promoter did not drive high levels of mCherry and Rs1 expression in the differentiated tissues of adult mice. These findings indicate that promoter selection is an important factor when developing transgene expression models.
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Affiliation(s)
- Edward C Hsiao
- Gladstone Institute of Cardiovascular Disease, 1650 Owens St., San Francisco, CA 94158, USA
- Division of Endocrinology and Metabolism, Department of Medicine, 400 Parnassus Ave., University of California, San Francisco, CA 94143-1222, USA
| | - Trieu D Nguyen
- Gladstone Institute of Cardiovascular Disease, 1650 Owens St., San Francisco, CA 94158, USA
| | - Jennifer K Ng
- Gladstone Institute of Cardiovascular Disease, 1650 Owens St., San Francisco, CA 94158, USA
| | - Mark J Scott
- Gladstone Institute of Cardiovascular Disease, 1650 Owens St., San Francisco, CA 94158, USA
| | - Wei Chun Chang
- Department of Cellular and Molecular Pharmacology, 600 16th Street Rm. S-222, University of California, San Francisco, CA 94158-2140, USA
| | - Hengameh Zahed
- Gladstone Institute of Neurological Disease, 1650 Owens St., San Francisco, CA 94158, USA
- Biomedical Sciences Graduate Program, 513 Parnassus Ave. Rm. HSE-1285, University of California, San Francisco, CA 94158-0505, USA
| | - Bruce R Conklin
- Gladstone Institute of Cardiovascular Disease, 1650 Owens St., San Francisco, CA 94158, USA
- Department of Medicine, 505 Parnassus Ave., University of California, San Francisco, CA 94143, USA
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Urwyler S. Allosteric modulation of family C G-protein-coupled receptors: from molecular insights to therapeutic perspectives. Pharmacol Rev 2011; 63:59-126. [PMID: 21228259 DOI: 10.1124/pr.109.002501] [Citation(s) in RCA: 164] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Allosteric receptor modulation is an attractive concept in drug targeting because it offers important potential advantages over conventional orthosteric agonism or antagonism. Allosteric ligands modulate receptor function by binding to a site distinct from the recognition site for the endogenous agonist. They often have no effect on their own and therefore act only in conjunction with physiological receptor activation. This article reviews the current status of allosteric modulation at family C G-protein coupled receptors in the light of their specific structural features on the one hand and current concepts in receptor theory on the other hand. Family C G-protein-coupled receptors are characterized by a large extracellular domain containing the orthosteric agonist binding site known as the "venus flytrap module" because of its bilobal structure and the dynamics of its activation mechanism. Mutational analysis and chimeric constructs have revealed that allosteric modulators of the calcium-sensing, metabotropic glutamate and GABA(B) receptors bind to the seven transmembrane domain, through which they modify signal transduction after receptor activation. This is in contrast to taste-enhancing molecules, which bind to different parts of sweet and umami receptors. The complexity of interactions between orthosteric and allosteric ligands is revealed by a number of adequate biochemical and electrophysiological assay systems. Many allosteric family C GPCR modulators show in vivo efficacy in behavioral models for a variety of clinical indications. The positive allosteric calcium sensing receptor modulator cinacalcet is the first drug of this type to enter the market and therefore provides proof of principle in humans.
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Affiliation(s)
- Stephan Urwyler
- Department of Chemistry and Biochemistry, University of Berne, P/A Weissensteinweg 3, CH-3303 Jegenstorf, Berne, Switzerland.
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17
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Atwood BK, Lopez J, Wager-Miller J, Mackie K, Straiker A. Expression of G protein-coupled receptors and related proteins in HEK293, AtT20, BV2, and N18 cell lines as revealed by microarray analysis. BMC Genomics 2011; 12:14. [PMID: 21214938 PMCID: PMC3024950 DOI: 10.1186/1471-2164-12-14] [Citation(s) in RCA: 301] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2010] [Accepted: 01/07/2011] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND G protein coupled receptors (GPCRs) are one of the most widely studied gene superfamilies. Thousands of GPCR research studies have utilized heterologous expression systems such as human embryonic kidney cells (HEK293). Though often treated as 'blank slates', these cell lines nevertheless endogenously express GPCRs and related signaling proteins. The outcome of a given GPCR study can be profoundly influenced by this largely unknown complement of receptors and/or signaling proteins. Little easily accessible information exists that describes the expression profiles of the GPCRs in cell lines. What is accessible is often limited in scope - of the hundreds of GPCRs and related proteins, one is unlikely to find information on expression of more than a dozen proteins in a given cell line. Microarray technology has allowed rapid analysis of mRNA levels of thousands of candidate genes, but though often publicly available, the results can be difficult to efficiently access or even to interpret. RESULTS To bridge this gap, we have used microarrays to measure the mRNA levels of a comprehensive profile of non-chemosensory GPCRs and over a hundred GPCR signaling related gene products in four cell lines frequently used for GPCR research: HEK293, AtT20, BV2, and N18. CONCLUSIONS This study provides researchers an easily accessible mRNA profile of the endogenous signaling repertoire that these four cell lines possess. This will assist in choosing the most appropriate cell line for studying GPCRs and related signaling proteins. It also provides a better understanding of the potential interactions between GPCRs and those signaling proteins.
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Affiliation(s)
- Brady K Atwood
- Department of Psychological & Brain Sciences, The Gill Center for Biomolecular Science, Indiana University, Bloomington, Indiana, USA
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18
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Digby GJ, Conn PJ, Lindsley CW. Orthosteric- and allosteric-induced ligand-directed trafficking at GPCRs. CURRENT OPINION IN DRUG DISCOVERY & DEVELOPMENT 2010; 13:587-594. [PMID: 20812150 PMCID: PMC3821179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Many orthosteric agonists differentially activate downstream effectors of GPCRs. Such defined induction of signaling has strongly supported the hypothesis termed 'ligand-directed trafficking of receptor signaling' (LDTRS). More recently, subtype-selective GPCR activators, such as allosteric agonists and positive allosteric modulators, have also exhibited the capacity to activate specific signaling pathways. Based on this finding, it may be possible to achieve ligand-specific receptor active states that optimize the biological responses specific to GPCRs. This review discusses recent studies in which both orthosteric and allosteric compounds have been demonstrated to induce LDTRS.
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Affiliation(s)
- Gregory J Digby
- Vanderbilt University School of Medicine, Department of Pharmacology, 12415D MRBIV (Langford), Nashville, TN 37232, USA
| | - P Jeffrey Conn
- Vanderbilt University School of Medicine, Department of Pharmacology, 12415D MRBIV (Langford), Nashville, TN 37232, USA
- Vanderbilt University School of Medicine, Vanderbilt Program in Drug Discovery, 12415D MRBIV (Langford), Nashville, TN 37232, USA
| | - Craig W Lindsley
- Vanderbilt University School of Medicine, Department of Pharmacology, 12415D MRBIV (Langford), Nashville, TN 37232, USA
- Vanderbilt University School of Medicine, Vanderbilt Program in Drug Discovery, 12415D MRBIV (Langford), Nashville, TN 37232, USA
- Vanderbilt University, Department of Chemistry, 7330 Stevenson Center, Station B 351822, Nashville, TN 37235, USA
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Choi IH, Kim HJ, Jung JH, Nam KY, Yoo SE, Kang NS, No KT. Bayesian Model for the Classification of GPCR Agonists and Antagonists. B KOREAN CHEM SOC 2010. [DOI: 10.5012/bkcs.2010.31.8.2163] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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20
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An evolutionarily conserved arginine is essential for Tre1 G protein-coupled receptor function during germ cell migration in Drosophila melanogaster. PLoS One 2010; 5:e11839. [PMID: 20676220 PMCID: PMC2911388 DOI: 10.1371/journal.pone.0011839] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2010] [Accepted: 06/29/2010] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND G protein-coupled receptors (GPCRs) play central roles in mediating cellular responses to environmental signals leading to changes in cell physiology and behaviors, including cell migration. Numerous clinical pathologies including metastasis, an invasive form of cell migration, have been linked to abnormal GPCR signaling. While the structures of some GPCRs have been defined, the in vivo roles of conserved amino acid residues and their relationships to receptor function are not fully understood. Trapped in endoderm 1 (Tre1) is an orphan receptor of the rhodopsin class that is necessary for primordial germ cell migration in Drosophila melanogaster embryos. In this study, we employ molecular genetic approaches to identify residues in Tre1 that are critical to its functions in germ cell migration. METHODOLOGY/PRINCIPAL FINDINGS First, we show that the previously reported scattershot mutation is an allele of tre1. The scattershot allele results in an in-frame deletion of 8 amino acids at the junction of the third transmembrane domain and the second intracellular loop of Tre1 that dramatically impairs the function of this GPCR in germ cell migration. To further refine the molecular basis for this phenotype, we assayed the effects of single amino acid substitutions in transgenic animals and determined that the arginine within the evolutionarily conserved E/N/DRY motif is critical for receptor function in mediating germ cell migration within an intact developing embryo. CONCLUSIONS/SIGNIFICANCE These structure-function studies of GPCR signaling in native contexts will inform future studies into the basic biology of this large and clinically important family of receptors.
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Stables MJ, Gilroy DW. Old and new generation lipid mediators in acute inflammation and resolution. Prog Lipid Res 2010; 50:35-51. [PMID: 20655950 DOI: 10.1016/j.plipres.2010.07.005] [Citation(s) in RCA: 232] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Revised: 07/08/2010] [Accepted: 07/08/2010] [Indexed: 01/02/2023]
Abstract
Originally regarded as just membrane constituents and energy storing molecules, lipids are now recognised as potent signalling molecules that regulate a multitude of cellular responses via receptor-mediated pathways, including cell growth and death, and inflammation/infection. Derived from polyunsaturated fatty acids (PUFAs), such as arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), each lipid displays unique properties, thus making their role in inflammation distinct from that of other lipids derived from the same PUFA. The diversity of their actions arises because such metabolites are synthesised via discrete enzymatic pathways and because they elicit their response via different receptors. This review will collate the bioactive lipid research to date and summarise the findings in terms of the major pathways involved in their biosynthesis and their role in inflammation and its resolution. It will include lipids derived from AA (prostanoids, leukotrienes, 5-oxo-6,8,11,14-eicosatetraenoic acid, lipoxins and epoxyeicosatrienoic acids), EPA (E-series resolvins), and DHA (D-series resolvins, protectins and maresins).
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Affiliation(s)
- Melanie J Stables
- Centre for Clinical Pharmacology and Therapeutics, Division of Medicine, 5 University Street, University College London, London WC1E 6JJ, United Kingdom
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22
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Uchida H, Yamazaki K, Fukuma M, Yamada T, Hayashida T, Hasegawa H, Kitajima M, Kitagawa Y, Sakamoto M. Overexpression of leucine-rich repeat-containing G protein-coupled receptor 5 in colorectal cancer. Cancer Sci 2010; 101:1731-7. [PMID: 20384634 PMCID: PMC11159016 DOI: 10.1111/j.1349-7006.2010.01571.x] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5) is a 7-transmembrane receptor reportedly expressed in stem cells of the intestinal crypts and hair follicles of mice. Overexpression of LGR5 is observed in some types of cancer; however, there has been no specific assessment in colorectal tumorigenesis. We performed quantitative RT-PCR for LGR5 expression in 37 representative cancer cell lines, and showed that LGR5 mRNA was frequently overexpressed in colon cancer cell lines. Moreover, LGR5 expression was higher in colon cancer cell lines derived from metastatic tumors compared with those from primary tumors. In clinical specimens, there was significant overexpression of LGR5 in 35 of 50 colorectal cancers (CRCs), and in seven of seven sporadic colonic adenomas, compared with matched normal mucosa. This suggests up-regulation of LGR5 from the early stage of colorectal tumorigenesis. LGR5 expression showed marked variation among CRC cases and correlated significantly with lymphatic invasion, vascular invasion, tumor depth, lymph node metastasis, and tumor stage (IIIC vs. IIIB). In addition to cancer cells, crypt base columnar cells of the small intestine and colon were shown by in situ hybridization to express LGR5. This is the first report suggesting the involvement of LGR5, not only in early events but also in late events in colorectal tumorigenesis.
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Affiliation(s)
- Hiroshi Uchida
- Department of Pathology, School of Medicine, Keio University, Tokyo, Japan
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Cleland TA. Early transformations in odor representation. Trends Neurosci 2010; 33:130-9. [PMID: 20060600 DOI: 10.1016/j.tins.2009.12.004] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Revised: 11/28/2009] [Accepted: 12/18/2009] [Indexed: 01/18/2023]
Abstract
Sensory representations are repeatedly transformed by neural computations that determine which of their attributes can be effectively processed at each stage. Whereas some early computations are common across multiple sensory systems, they can utilize dissimilar underlying mechanisms depending on the properties of each modality. Recent work in the olfactory bulb has substantially clarified the neural algorithms underlying early odor processing. The high-dimensionality of odor space strictly limits the utility of topographical representations, forcing similarity-dependent computations such as decorrelation to employ unusual neural algorithms. The distinct architectures and properties of the two prominent computational layers in the olfactory bulb suggest that the bulb is directly comparable not only to the retina but also to primary visual cortex.
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Affiliation(s)
- Thomas A Cleland
- Department of Psychology, Cornell University, Ithaca, NY 14853, USA.
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Saveanu A, Jaquet P. Somatostatin-dopamine ligands in the treatment of pituitary adenomas. Rev Endocr Metab Disord 2009; 10:83-90. [PMID: 18651224 DOI: 10.1007/s11154-008-9086-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Accepted: 06/12/2008] [Indexed: 01/18/2023]
Abstract
Somatostatin receptors (sst1-5) and dopamine receptor 2 (D2DR) are well expressed and co-localized in several human pituitary adenomas, suggesting possible functional interactions in the control of hormonal hypersecretion and tumor cell growth. The present review describes the expression and functionality of these receptors in the different classes of human pituitary adenomas. The sst2 agonists, octreotide and lanreotide, control GH hypersecretion and tumor growth in about 65% of somatotropinomas. The D2DR agonists, bromocriptine and cabergoline, control about 90% of prolactinomas. Such drugs are much less effective in the control of the others pituitary adenomas also expressing ssts and D2DR receptors. The second part summarizes the current knowledge on new chimeric compounds with sst2, sst5, and D2DR affinity. Such ligands bearing distinct ssts and DRD2 pharmacophores may synergistically produce an increased control of secretion and/or of proliferation in the different types of pituitary adenomas. The mechanisms of action of such chimeric molecules through increased binding affinities, prolonged bioavailability, ligand-induced modulation of receptors heterodimerization, are discussed.
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Affiliation(s)
- Alexandru Saveanu
- CRN2M UMR 6231, Centre National de la Recherche Scientifique, Universite de la Mediterranee, Faculté de Médecine Nord, Marseille, France.
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Reyes‐Alcaraz A, Tzanov T, Garriga P. Stabilization of Membrane Proteins: the Case of G‐Protein‐Coupled Receptors. Eng Life Sci 2008. [DOI: 10.1002/elsc.200700059] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Saveanu A, Jaquet P, Brue T, Barlier A. Relevance of coexpression of somatostatin and dopamine D2 receptors in pituitary adenomas. Mol Cell Endocrinol 2008; 286:206-13. [PMID: 18241980 DOI: 10.1016/j.mce.2007.12.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Revised: 12/10/2007] [Accepted: 12/12/2007] [Indexed: 02/06/2023]
Abstract
Dopamine and somatostatin are both involved in the negative control of normal pituitary cells. Dopamine subtype 2 receptor (D2DR) and somatostatin receptor (sst) agonists, mainly directed to sst2, are used in the treatment of pituitary adenomas. Nevertheless, a majority of corticotroph and gonadotroph adenomas and a third of somatotroph adenomas are still not sufficiently controlled by these treatments. D2DR and sst1, 2, 3 and 5 are present in most pituitary adenomas. These receptors may interact by heterodimerization as shown for sst1-sst5, sst5-D2DR, sst2-sst3 and sst2-D2DR suggesting possible additive effects. D2DR and sst2 agonist cotreatment showed limited additivity on GH secretion in acromegaly. Moreover, new chimeric compounds with sst2, D2DR and sst5 affinity have shown an increased control of secretion and/or proliferation of different types of pituitary adenomas in cell culture. Together with the multi-sst ligand drugs recently developed, these dopamine-somatostatin ligands represent a new opportunity in the combinatory treatment of pituitary adenomas.
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Affiliation(s)
- A Saveanu
- Laboratory Interactions Cellulaires Neuroendocriniennes, UMR 6544 CNRS, Institut Fédératif Jean Roche, Faculté de Médecine Nord, Université de la Méditerranée, Marseille, France.
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Small molecule activators of SIRT1 as therapeutics for the treatment of type 2 diabetes. Nature 2008; 450:712-6. [PMID: 18046409 DOI: 10.1038/nature06261] [Citation(s) in RCA: 1309] [Impact Index Per Article: 81.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Accepted: 09/17/2007] [Indexed: 01/04/2023]
Abstract
Calorie restriction extends lifespan and produces a metabolic profile desirable for treating diseases of ageing such as type 2 diabetes. SIRT1, an NAD+-dependent deacetylase, is a principal modulator of pathways downstream of calorie restriction that produce beneficial effects on glucose homeostasis and insulin sensitivity. Resveratrol, a polyphenolic SIRT1 activator, mimics the anti-ageing effects of calorie restriction in lower organisms and in mice fed a high-fat diet ameliorates insulin resistance, increases mitochondrial content, and prolongs survival. Here we describe the identification and characterization of small molecule activators of SIRT1 that are structurally unrelated to, and 1,000-fold more potent than, resveratrol. These compounds bind to the SIRT1 enzyme-peptide substrate complex at an allosteric site amino-terminal to the catalytic domain and lower the Michaelis constant for acetylated substrates. In diet-induced obese and genetically obese mice, these compounds improve insulin sensitivity, lower plasma glucose, and increase mitochondrial capacity. In Zucker fa/fa rats, hyperinsulinaemic-euglycaemic clamp studies demonstrate that SIRT1 activators improve whole-body glucose homeostasis and insulin sensitivity in adipose tissue, skeletal muscle and liver. Thus, SIRT1 activation is a promising new therapeutic approach for treating diseases of ageing such as type 2 diabetes.
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28
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Chang WC, Ng JK, Nguyen T, Pellissier L, Claeysen S, Hsiao EC, Conklin BR. Modifying ligand-induced and constitutive signaling of the human 5-HT4 receptor. PLoS One 2007; 2:e1317. [PMID: 18338032 PMCID: PMC2267039 DOI: 10.1371/journal.pone.0001317] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2007] [Accepted: 11/18/2007] [Indexed: 11/26/2022] Open
Abstract
G protein–coupled receptors (GPCRs) signal through a limited number of G-protein pathways and play crucial roles in many biological processes. Studies of their in vivo functions have been hampered by the molecular and functional diversity of GPCRs and the paucity of ligands with specific signaling effects. To better compare the effects of activating different G-protein signaling pathways through ligand-induced or constitutive signaling, we developed a new series of RASSLs (receptors activated solely by synthetic ligands) that activate different G-protein signaling pathways. These RASSLs are based on the human 5-HT4b receptor, a GPCR with high constitutive Gs signaling and strong ligand-induced G-protein activation of the Gs and Gs/q pathways. The first receptor in this series, 5-HT4-D100A or Rs1 (RASSL serotonin 1), is not activated by its endogenous agonist, serotonin, but is selectively activated by the small synthetic molecules GR113808, GR125487, and RO110-0235. All agonists potently induced Gs signaling, but only a few (e.g., zacopride) also induced signaling via the Gq pathway. Zacopride-induced Gq signaling was enhanced by replacing the C-terminus of Rs1 with the C-terminus of the human 5-HT2C receptor. Additional point mutations (D66A and D66N) blocked constitutive Gs signaling and lowered ligand-induced Gq signaling. Replacing the third intracellular loop of Rs1 with that of human 5-HT1A conferred ligand-mediated Gi signaling. This Gi-coupled RASSL, Rs1.3, exhibited no measurable signaling to the Gs or Gq pathway. These findings show that the signaling repertoire of Rs1 can be expanded and controlled by receptor engineering and drug selection.
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Affiliation(s)
- Wei Chun Chang
- Gladstone Institute of Cardiovascular Disease, University of California at San Francisco, San Francisco, California, United States of America
- Graduate Program in Pharmaceutical Sciences and Pharmacogenomics, University of California at San Francisco, San Francisco, California, United States of America
| | - Jennifer K. Ng
- Gladstone Institute of Cardiovascular Disease, University of California at San Francisco, San Francisco, California, United States of America
| | - Trieu Nguyen
- Gladstone Institute of Cardiovascular Disease, University of California at San Francisco, San Francisco, California, United States of America
| | - Lucie Pellissier
- Institut de Génomique Fonctionnelle, Universités de Montpellier, CNRS UMR 5203, Montpellier, France
- INSERM U661, Montpellier, France
| | - Sylvie Claeysen
- Institut de Génomique Fonctionnelle, Universités de Montpellier, CNRS UMR 5203, Montpellier, France
- INSERM U661, Montpellier, France
| | - Edward C. Hsiao
- Gladstone Institute of Cardiovascular Disease, University of California at San Francisco, San Francisco, California, United States of America
- Department of Medicine, University of California at San Francisco, San Francisco, California, United States of America
| | - Bruce R. Conklin
- Gladstone Institute of Cardiovascular Disease, University of California at San Francisco, San Francisco, California, United States of America
- Department of Medicine, University of California at San Francisco, San Francisco, California, United States of America
- Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California, United States of America
- * To whom correspondence should be addressed. E-mail:
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Sichardt K, Nieber K. Adenosine A(1) receptor: Functional receptor-receptor interactions in the brain. Purinergic Signal 2007; 3:285-98. [PMID: 18404442 PMCID: PMC2072922 DOI: 10.1007/s11302-007-9065-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Accepted: 07/24/2007] [Indexed: 12/20/2022] Open
Abstract
Over the past decade, many lines of investigation have shown that receptor-mediated signaling exhibits greater diversity than previously appreciated. Signal diversity arises from numerous factors, which include the formation of receptor dimers and interplay between different receptors. Using adenosine A1 receptors as a paradigm of G protein-coupled receptors, this review focuses on how receptor-receptor interactions may contribute to regulation of the synaptic transmission within the central nervous system. The interactions with metabotropic dopamine, adenosine A2A, A3, neuropeptide Y, and purinergic P2Y1 receptors will be described in the first part. The second part deals with interactions between A1Rs and ionotropic receptors, especially GABAA, NMDA, and P2X receptors as well as ATP-sensitive K+ channels. Finally, the review will discuss new approaches towards treating neurological disorders.
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Affiliation(s)
- Kathrin Sichardt
- Institute of Pharmacy, University of Leipzig, Talstr. 33, 04103 Leipzig, Germany
| | - Karen Nieber
- Institute of Pharmacy, University of Leipzig, Talstr. 33, 04103 Leipzig, Germany
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30
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Gilchrist A. Modulating G-protein-coupled receptors: from traditional pharmacology to allosterics. Trends Pharmacol Sci 2007; 28:431-7. [PMID: 17644194 DOI: 10.1016/j.tips.2007.06.012] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Accepted: 06/29/2007] [Indexed: 10/23/2022]
Abstract
Signal transduction is the means by which cells respond to variations in their environment. G-protein-coupled receptors (GPCRs) are the largest family of cell-surface receptors, accounting for >1% of the human genome. GPCRs respond to a wide variety of extracellular signals, including peptides, ions, amino acids, hormones, growth factors, light and odorant molecules. The receptors couple with heterotrimeric G proteins to transduce their signal across the membrane and into the cell. This coupling promotes the exchange of GDP for GTP on the Galpha subunit, leading to effector activation by both Galpha-GTP and Gbetagamma. Functional selectivity, whereby conformational changes in GPCRs induced by agonist binding lead to unique conformations that can differentially modulate the G protein coupling process, was first proposed over a decade ago. The implications are far reaching in pharmacology, as it means that a GPCR could have a different pharmacological profile depending on which G protein is activated and that the same GPCR could have different roles depending on the activating molecule as well as the G proteins present in the local environment.
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31
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Gao Y, Kitagawa K, Hiramatsu Y, Kikuchi H, Isobe T, Shimada M, Uchida C, Hattori T, Oda T, Nakayama K, Nakayama KI, Tanaka T, Konno H, Kitagawa M. Up-regulation of GPR48 induced by down-regulation of p27Kip1 enhances carcinoma cell invasiveness and metastasis. Cancer Res 2007; 66:11623-31. [PMID: 17178856 DOI: 10.1158/0008-5472.can-06-2629] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A reduced expression level of the cyclin-dependent kinase inhibitor p27(Kip1) is associated with increased tumor malignancy and poor prognosis in individuals with various types of cancer. To investigate the basis for this relation, we applied microarray analysis to screen for genes differentially expressed between p27(+/-) and parental (p27(+/+)) HCT116 human colon carcinoma cells. Expression of the gene for G protein-coupled receptor 48 (GPR48) was increased in the p27(+/-) cells. Forced expression of GPR48 increased both in vitro invasive activity and lung metastasis potency of HCT116 cells. In contrast, depletion of endogenous GPR48 by RNA interference reduced the invasive potential of HeLa and Lewis lung carcinoma cells not only in vitro but also in vivo. Moreover, GPR48 expression was significantly associated with lymph node metastasis and inversely correlated with p27 expression in human colon carcinomas. GPR48 may thus play an important role in invasiveness and metastasis of carcinoma and might therefore represent a potential prognostic marker or therapeutic target.
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Affiliation(s)
- Yun Gao
- Department of Biochemistry 1, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
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32
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Rovati GE, Capra V, Neubig RR. The highly conserved DRY motif of class A G protein-coupled receptors: beyond the ground state. Mol Pharmacol 2006; 71:959-64. [PMID: 17192495 DOI: 10.1124/mol.106.029470] [Citation(s) in RCA: 278] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Despite extensive study of heptahelical G protein-coupled receptors (GPCRs), the precise mechanism of G protein activation is unknown. The role of one highly conserved stretch of residues, the amino acids glutamic acid/aspartic acid-arginine-tyrosine (i.e., the E/DRY motif), has received considerable attention with respect to regulating GPCR conformational states. In the consensus view, glutamic acid/aspartic acid maintains the receptor in its ground state, because mutations frequently induce constitutive activity (CA). This hypothesis has been confirmed by the rhodopsin ground-state crystal structure and by computational modeling approaches. However, some class A GPCRs are resistant to CA, suggesting alternative roles for the glutamic acid/aspartic acid residue and the E/DRY motif. Here, we propose two different subgroups of receptors within class A GPCRs that make different use of the E/DRY motif, independent of the G protein type (G(s), G(i), or G(q)) to which the receptor couples. In phenotype 1 receptors, nonconservative mutations of the glutamic acid/aspartic acid-arginine residues, besides inducing CA, increase affinity for agonist binding, retain G protein coupling, and retain an agonist-induced response. In contrast, in second phenotype receptors, the E/DRY motif is more directly involved in governing receptor conformation and G protein coupling/recognition. Hence, mutations of the glutamic acid/aspartic acid residues do not induce CA. Conversely, nonconservative mutations of the arginine of the E/DRY motif always impair agonist-induced receptor responses and, generally, reduce agonist binding affinity. Thus, it is essential to look beyond the rhodopsin ground-state model of conformational activation to clarify the role of this highly conserved triplet in GPCR activation and function.
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Affiliation(s)
- G Enrico Rovati
- Laboratory of Molecular Pharmacology, Department of Pharmacological Sciences, University of Milan, Via Balzaretti 9, 20133 Milan, Italy.
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33
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Kalatskaya I, Schüssler S, Seidl C, Jochum M, Faussner A. C-terminal fusion of eGFP to the bradykinin B2 receptor strongly affects down-regulation but not receptor internalization or signaling. Biol Chem 2006; 387:603-10. [PMID: 16740132 DOI: 10.1515/bc.2006.077] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A functional comparison was made between the wild-type bradykinin B2 receptor (B2wt) and the chimera B2eGFP (enhanced green-fluorescent protein fused to the C-terminus of B2wt), both stably expressed in HEK 293 cells. There was almost no difference in terms of ligand-inducible receptor phosphorylation and internalization, signal transduction (accumulation of inositol phosphates) or expression and affinity. However, stimulation for up to 8 h with 10 microM bradykinin (BK) resulted in a strong decrease in surface receptors (by 60% within 5 h) in B2wt, but not in B2eGFP. When the expression levels of both constructs where comparably reduced using a weaker promoter, long-term stimulation resulted in a reduction in surface receptors for B2wt(low) to less than 20% within 1 h, whereas the chimera B2eGFP(low) still displayed 50% binding activity after 2 h. A 1-h incubation in the absence of BK resulted in a recovery of 60% of the binding in B2wt(low) after 1-h stimulation with BK, but of only 20% after 7-h stimulation. In contrast, B2eGFP(low) levels were restored to more than 70%, even after 7-h stimulation. These data indicate that although the fusion of eGFP to B2wt does not affect its ligand-induced internalization, it strongly reduces the down-regulation, most likely by promoting receptor recycling over degradation.
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Affiliation(s)
- Irina Kalatskaya
- Abteilung für Klinische Chemie und Klinische Biochemie, Ludwig-Maximilians-Universität München, Nussbaumstrasse 20, D-80336 München, Germany
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34
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Hulshof JW, Vischer HF, Verheij MHP, Fratantoni SA, Smit MJ, de Esch IJP, Leurs R. Synthesis and pharmacological characterization of novel inverse agonists acting on the viral-encoded chemokine receptor US28. Bioorg Med Chem 2006; 14:7213-30. [PMID: 16843661 DOI: 10.1016/j.bmc.2006.06.054] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2006] [Revised: 06/08/2006] [Accepted: 06/23/2006] [Indexed: 11/16/2022]
Abstract
G-protein coupled receptors encoded by viruses represent an unexplored class of potential drug targets. In this study, we describe the synthesis and pharmacological characterization of the first class of inverse agonists acting on the HCMV-encoded receptor US28. It is shown that replacement of the 4-hydroxy group of lead compound 1 with a methylamine group results in a significant 6-fold increase in affinity. Interestingly, increasing the rigidity of the spacer by the introduction of a double bond also leads to a significant increase in binding affinity compared to 1. These novel inverse agonists serve as valuable tools to elucidate the role of constitutive signaling in the pathogenesis of viral infection and may have therapeutic potential as leads for new antiviral drugs.
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Affiliation(s)
- Janneke W Hulshof
- Leiden/Amsterdam Center for Drug Research, LACDR, Division of Medicinal Chemistry, Faculty of Sciences, Vrije Universiteit, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
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35
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Reiter E, Lefkowitz RJ. GRKs and beta-arrestins: roles in receptor silencing, trafficking and signaling. Trends Endocrinol Metab 2006; 17:159-65. [PMID: 16595179 DOI: 10.1016/j.tem.2006.03.008] [Citation(s) in RCA: 508] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2005] [Revised: 03/07/2006] [Accepted: 03/21/2006] [Indexed: 01/27/2023]
Abstract
Stimulation of cell-surface seven-transmembrane receptors (7TMRs) elicits biological responses to a wide range of extracellular signals, including many hormones. Classically, heterotrimeric GTP-binding proteins (G proteins) are recruited to the activated conformation of 7TMRs. Only two other families of protein have this remarkable characteristic: G-protein-coupled receptor kinases and beta-arrestins. These two protein families have long been known to have a central and coordinated role in the "desensitization" of G protein activation by 7TMRs. In addition, G-protein-coupled receptor kinases and beta-arrestins are involved in an increasing number of interactions with non-receptor proteins, broadening the variety of their cellular functions. These newly appreciated attributes of these two families of protein highlight their unique ability to coordinate the various aspects of 7TMR functions.
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Affiliation(s)
- Eric Reiter
- Departments of Medicine and Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
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36
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Millan MJ. Multi-target strategies for the improved treatment of depressive states: Conceptual foundations and neuronal substrates, drug discovery and therapeutic application. Pharmacol Ther 2006; 110:135-370. [PMID: 16522330 DOI: 10.1016/j.pharmthera.2005.11.006] [Citation(s) in RCA: 389] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2005] [Accepted: 11/28/2005] [Indexed: 12/20/2022]
Abstract
Major depression is a debilitating and recurrent disorder with a substantial lifetime risk and a high social cost. Depressed patients generally display co-morbid symptoms, and depression frequently accompanies other serious disorders. Currently available drugs display limited efficacy and a pronounced delay to onset of action, and all provoke distressing side effects. Cloning of the human genome has fuelled expectations that symptomatic treatment may soon become more rapid and effective, and that depressive states may ultimately be "prevented" or "cured". In pursuing these objectives, in particular for genome-derived, non-monoaminergic targets, "specificity" of drug actions is often emphasized. That is, priority is afforded to agents that interact exclusively with a single site hypothesized as critically involved in the pathogenesis and/or control of depression. Certain highly selective drugs may prove effective, and they remain indispensable in the experimental (and clinical) evaluation of the significance of novel mechanisms. However, by analogy to other multifactorial disorders, "multi-target" agents may be better adapted to the improved treatment of depressive states. Support for this contention is garnered from a broad palette of observations, ranging from mechanisms of action of adjunctive drug combinations and electroconvulsive therapy to "network theory" analysis of the etiology and management of depressive states. The review also outlines opportunities to be exploited, and challenges to be addressed, in the discovery and characterization of drugs recognizing multiple targets. Finally, a diversity of multi-target strategies is proposed for the more efficacious and rapid control of core and co-morbid symptoms of depression, together with improved tolerance relative to currently available agents.
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Affiliation(s)
- Mark J Millan
- Institut de Recherches Servier, Centre de Recherches de Croissy, Psychopharmacology Department, 125, Chemin de Ronde, 78290-Croissy/Seine, France.
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Gjoni T, Desrayaud S, Imobersteg S, Urwyler S. The positive allosteric modulator GS39783 enhances GABA(B) receptor-mediated inhibition of cyclic AMP formation in rat striatum in vivo. J Neurochem 2006; 96:1416-22. [PMID: 16441514 DOI: 10.1111/j.1471-4159.2006.03660.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We studied the effects of the positive allosteric modulator GS39783 on GABA(B) receptors at a biochemical level in vivo. Changes in extracellular levels of cyclic AMP following GABA(B) receptor activation were monitored in the striatum of freely moving rats using microdialysis. Locally applied GABA(B) agonist R(-)-baclofen inhibited cyclic AMP formation stimulated by a water-soluble forskolin analogue in a concentration-dependent manner (EC50 7.3 microM, maximal inhibition 40%). The selective GABA(B) antagonist CGP56999 reversed R(-)-baclofen-induced cyclic AMP inhibition to control levels, but not higher. Orally applied GS39783 lacked effects on its own but, together with a threshold concentration of R(-)-baclofen (1 microM), significantly decreased cyclic AMP formation in a dose-dependent fashion. Effects of GS39783 were revoked with CGP56999, showing dependence on GABA(B) receptor activation and suggesting allosteric modulation as a mechanism of action in vivo. Administered with a maximally active dose of R(-)-baclofen, GS39783 failed to further inhibit cyclic AMP formation. The data obtained with CGP56999 and the lack of effect of GS39783 alone suggest that there is no detectable endogenous activation of GABA(B) receptors controlling cyclic AMP formation in rat striatum. To our knowledge, these results provide the first biochemical demonstration of in vivo activity of a G protein-coupled receptor-positive allosteric modulator.
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Affiliation(s)
- Tina Gjoni
- Novartis Institutes for BioMedical Research, Neuroscience, Basel, Switzerland
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38
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Maudsley S, Martin B, Luttrell LM. The origins of diversity and specificity in g protein-coupled receptor signaling. J Pharmacol Exp Ther 2005; 314:485-94. [PMID: 15805429 PMCID: PMC2656918 DOI: 10.1124/jpet.105.083121] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The modulation of transmembrane signaling by G protein-coupled receptors (GPCRs) constitutes the single most important therapeutic target in medicine. Drugs acting on GPCRs have traditionally been classified as agonists, partial agonists, or antagonists based on a two-state model of receptor function embodied in the ternary complex model. Over the past decade, however, many lines of investigation have shown that GPCR signaling exhibits greater diversity and "texture" than previously appreciated. Signal diversity arises from numerous factors, among which are the ability of receptors to adopt multiple "active" states with different effector-coupling profiles; the formation of receptor dimers that exhibit unique pharmacology, signaling, and trafficking; the dissociation of receptor "activation" from desensitization and internalization; and the discovery that non-G protein effectors mediate some aspects of GPCR signaling. At the same time, clustering of GPCRs with their downstream effectors in membrane microdomains and interactions between receptors and a plethora of multidomain scaffolding proteins and accessory/chaperone molecules confer signal preorganization, efficiency, and specificity. In this context, the concept of agonist-selective trafficking of receptor signaling, which recognizes that a bound ligand may select between a menu of active receptor conformations and induce only a subset of the possible response profile, presents the opportunity to develop drugs that change the quality as well as the quantity of efficacy. As a more comprehensive understanding of the complexity of GPCR signaling is developed, the rational design of ligands possessing increased specific efficacy and attenuated side effects may become the standard mode of drug development.
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Affiliation(s)
- Stuart Maudsley
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Gerontology Research Center, 5600 Nathan Shock Drive, Johns Hopkins Medical Center, Baltimore, MD, USA.
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Abstract
The superfamily of G-protein-coupled receptors (GPCRs) was discussed at a recent Cambridge Healthtech Institute meeting. Scientists working in both academia and industry participated in 2 days of talks that addressed important issues related to the use of GPCRs as targets. The meeting delved into questions and strategies surrounding receptor structure, lack of knowledge about endogenous ligands, novel methodology for identifying compounds from high-throughput screening, the development process from hits to leads, and what constitutes adequate proof-of-principle studies. This report highlights several presentations related to the ongoing search for more effective GPCR-targeted drug discovery efforts.
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40
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Cui K, Luo X, Xu K, Ven Murthy MR. Role of oxidative stress in neurodegeneration: recent developments in assay methods for oxidative stress and nutraceutical antioxidants. Prog Neuropsychopharmacol Biol Psychiatry 2004; 28:771-99. [PMID: 15363603 DOI: 10.1016/j.pnpbp.2004.05.023] [Citation(s) in RCA: 196] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/10/2004] [Indexed: 01/31/2023]
Abstract
Reactive oxygen species (ROS) are produced in the course of normal metabolism and they serve important physiological functions. However, because of their high reactivity, accumulation of ROS beyond the immediate needs of the cell may affect cellular structure and functional integrity, by bringing about oxidative degradation of critical molecules, such as the DNA, proteins, and lipids. Although cells possess an intricate network of defense mechanisms to neutralize excess ROS and reduce oxidative stress, some tissues, especially the brain, are much more vulnerable to oxidative stress because of their elevated consumption of oxygen and the consequent generation of large amounts of ROS. For the same reason, the mitochondrial DNA (mtDNA) of brain cells is highly susceptible to structural alterations resulting in mitochondrial dysfunction. Several lines of evidence strongly suggest that these effects of ROS may be etiologically related to a number of neurodegenerative disorders. Nutraceutical antioxidants are dietary supplements that can exert positive pharmacological effects on specific human diseases by neutralizing the negative effects of ROS. The present communication concentrates on a review of recent concepts and methodological developments, some of them based on the results of work from our own laboratory, on the following aspects: (1) the complex interactions and complementary interrelationships between oxidative stress, mitochondrial dysfunction, and various forms of neural degeneration; (2) fractionation and isolation of substances with antioxidant properties from plant materials, which are extensively used in the human diet and, therefore, can be expected to be less toxic in any pharmacological intervention; (3) recent developments in methodologies that can be used for the assay of oxidative stress and determination of biological activities of exogenous and endogenous antioxidants; and (4) presentation of simple procedures based on polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) of the resulting amplicon for investigations of structural alterations in mtDNA.
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Affiliation(s)
- Ke Cui
- Department of Medical Biology, Faculty of Medicine, Laval University, Québec, Canada G1K 7P4
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41
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Sadler K, Tam JP. Shape-mimetics of G-protein-coupled receptors in therapeutic drug design and screening. Drug Dev Res 2004. [DOI: 10.1002/ddr.10391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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