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Thompson MD, Chidiac P, Jose PA, Hauser AS, Gorvin CM. Genetic variants of accessory proteins and G proteins in human genetic disease. Crit Rev Clin Lab Sci 2025; 62:113-134. [PMID: 39743506 PMCID: PMC11854058 DOI: 10.1080/10408363.2024.2431853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 01/14/2024] [Accepted: 11/16/2024] [Indexed: 01/04/2025]
Abstract
We present a series of three articles on the genetics and pharmacogenetics of G protein- coupled receptors (GPCR). In the first article, we discuss genetic variants of the G protein subunits and accessory proteins that are associated with human phenotypes; in the second article, we build upon this to discuss "G protein-coupled receptor (GPCR) gene variants and human genetic disease" and in the third article, we survey "G protein-coupled receptor pharmacogenomics". In the present article, we review the processes of ligand binding, GPCR activation, inactivation, and receptor trafficking to the membrane in the context of human genetic disease resulting from pathogenic variants of accessory proteins and G proteins. Pathogenic variants of the genes encoding G protein α and β subunits are examined in diverse phenotypes. Variants in the genes encoding accessory proteins that modify or organize G protein coupling have been associated with disease; these include the contribution of variants of the regulator of G protein signaling (RGS) to hypertension; the role of variants of activator of G protein signaling type III in phenotypes such as hypoxia; the contribution of variation at the RGS10 gene to short stature and immunological compromise; and the involvement of variants of G protein-coupled receptor kinases (GRKs), such as GRK4, in hypertension. Variation in genes that encode proteins involved in GPCR signaling are outlined in the context of the changes in structure and function that may be associated with human phenotypes.
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Affiliation(s)
- Miles D. Thompson
- Krembil Brain Institute, Toronto Western Hospital, Toronto, Ontario, Canada
| | - Peter Chidiac
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Pedro A. Jose
- Division of Renal Diseases & Hypertension, Departments of Medicine and Pharmacology/Physiology, The George Washington University School of Medicine and Health Sciences, Washington, District of Columbia, USA
| | - Alexander S. Hauser
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Caroline M. Gorvin
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, West Midlands, UK
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Free Fatty Acid Receptors (FFARs) in Adipose: Physiological Role and Therapeutic Outlook. Cells 2022; 11:cells11040750. [PMID: 35203397 PMCID: PMC8870169 DOI: 10.3390/cells11040750] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 02/17/2022] [Accepted: 02/17/2022] [Indexed: 12/11/2022] Open
Abstract
Fatty acids (FFAs) are important biological molecules that serve as a major energy source and are key components of biological membranes. In addition, FFAs play important roles in metabolic regulation and contribute to the development and progression of metabolic disorders like diabetes. Recent studies have shown that FFAs can act as important ligands of G-protein-coupled receptors (GPCRs) on the surface of cells and impact key physiological processes. Free fatty acid-activated receptors include FFAR1 (GPR40), FFAR2 (GPR43), FFAR3 (GPR41), and FFAR4 (GPR120). FFAR2 and FFAR3 are activated by short-chain fatty acids like acetate, propionate, and butyrate, whereas FFAR1 and FFAR4 are activated by medium- and long-chain fatty acids like palmitate, oleate, linoleate, and others. FFARs have attracted considerable attention over the last few years and have become attractive pharmacological targets in the treatment of type 2 diabetes and metabolic syndrome. Several lines of evidence point to their importance in the regulation of whole-body metabolic homeostasis including adipose metabolism. Here, we summarize our current understanding of the physiological functions of FFAR isoforms in adipose biology and explore the prospect of FFAR-based therapies to treat patients with obesity and Type 2 diabetes.
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Pharmacologic and Clinical Considerations of Nalmefene, a Long Duration Opioid Antagonist, in Opioid Overdose. PSYCHIATRY INTERNATIONAL 2021. [DOI: 10.3390/psychiatryint2040028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Opioid use disorder is a well-established and growing problem in the United States. It is responsible for both psychosocial and physical damage to the affected individuals with a significant mortality rate. Given both the medical and non-medical consequences of this epidemic, it is important to understand the current treatments and approaches to opioid use disorder and acute opioid overdose. Naloxone is a competitive mu-opioid receptor antagonist that is used for the reversal of opioid intoxication. When given intravenously, naloxone has an onset of action of approximately 2 min with a duration of action of 60–90 min. Related to its empirical dosing and short duration of action, frequent monitoring of the patient is required so that the effects of opioid toxicity, namely respiratory depression, do not return to wreak havoc. Nalmefene is a pure opioid antagonist structurally similar to naltrexone that can serve as an alternative antidote for reversing respiratory depression associated with acute opioid overdose. Nalmefene is also known as 6-methylene naltrexone. Its main features of interest are its prolonged duration of action that surpasses most opioids and its ability to serve as an antidote for acute opioid overdose. This can be pivotal in reducing healthcare costs, increasing patient satisfaction, and redistributing the time that healthcare staff spend monitoring opioid overdose patients given naloxone.
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Seeman MV. History of the dopamine hypothesis of antipsychotic action. World J Psychiatry 2021; 11:355-364. [PMID: 34327128 PMCID: PMC8311512 DOI: 10.5498/wjp.v11.i7.355] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 04/22/2021] [Accepted: 06/22/2021] [Indexed: 02/06/2023] Open
Abstract
The dopamine hypothesis of how antipsychotic drugs exert their beneficial effect in psychotic illness has an interesting history that dates back to 1950. This hypothesis is not to be confused with the dopamine hypothesis of schizophrenia; the aim of the latter is to explain the etiology of schizophrenia. The present review does not deal with schizophrenia but, rather, with the historical development of our current understanding of the dopamine-associated actions of the drugs that reduce the symptoms of psychosis. This historical review begins with the serendipitous discovery of chlorpromazine, a drug synthesized around a chemical core that initially served to produce man-made dyes. This molecular core subsequently contributed to the chemistry of antihistamines. It was with the aim of producing a superior antihistamine that chlorpromazine was synthesized; instead, it revolutionized the treatment of psychosis. The first hypothesis of how this drug worked was that it induced hypothermia, a cooling of the body that led to a tranquilization of the mind. The new, at the time, discoveries of the presence of chemical transmitters in the brain soon steered investigations away from a temperature-related hypothesis toward questioning how this drug, and other drugs with similar properties and effects, modulated endogenous neurotransmission. As a result, over the years, researchers from around the world have begun to progressively learn what antipsychotic drugs do in the brain.
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Affiliation(s)
- Mary V Seeman
- Department of Psychiatry, University of Toronto, Toronto M5P 3L6, Ontario, Canada
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Ovlund T, Pacini G, Ahrén B. Impact of Incretin Hormone Receptors on Insulin-Independent Glucose Disposal in Model Experiments in Mice. Front Endocrinol (Lausanne) 2021; 12:680153. [PMID: 34168617 PMCID: PMC8217865 DOI: 10.3389/fendo.2021.680153] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Accepted: 05/19/2021] [Indexed: 12/14/2022] Open
Abstract
A large contribution to glucose elimination from the circulation is achieved by insulin-independent processes. We have previously shown that the two incretin hormones, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) increase this process and, therefore, seem to contribute to glucose disposal both through this effect and through the classical incretin effect resulting in enhanced insulin levels. We have now explored in more detail the potential contribution by incretin hormone receptors to insulin-independent processes for glucose elimination. To that end, we have performed intravenous glucose tests (0.35g/kg) in C57BL/6J mice and analyzed glucose elimination rate and glucose effectiveness (i.e., insulin-independent glucose disposal, SG) in wildtype mice and in mice with genetic deletion of GIP receptors or GLP-1 receptors. We performed studies with or without complete blockade of insulin secretion by the drug diazoxide (25 mg/kg). The mice were anesthetized with a novel fentanyl citrate/fluanisone formulation, called Fluafent, together with midazolam. Initially we demonstrated that glucose and insulin data after intravenous and oral glucose were not different using this anesthesia compared to the previously commonly used combination of HypnormR and midazolam. The results show that SG was reduced in GLP-1 receptor knockout mice, whereas there was no difference between GIP receptor knockout mice and wildtype mice, and this was evident both under normal conditions and after complete inhibition of insulin secretion. The study therefore indicates that insulin-independent glucose elimination requires active GLP-1 receptors and thus that the two incretin hormone receptor types show dissociated relevance for this process.
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Affiliation(s)
- Tina Ovlund
- Department of Clinical Sciences Lund, Lund University, Lund, Sweden
| | | | - Bo Ahrén
- Department of Clinical Sciences Lund, Lund University, Lund, Sweden
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Bertoldo E, Adami G, Rossini M, Giollo A, Orsolini G, Viapiana O, Gatti D, Fassio A. The Emerging Roles of Endocrine Hormones in Different Arthritic Disorders. Front Endocrinol (Lausanne) 2021; 12:620920. [PMID: 34093428 PMCID: PMC8177688 DOI: 10.3389/fendo.2021.620920] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Accepted: 04/20/2021] [Indexed: 12/17/2022] Open
Abstract
The relationship between endocrine hormones and the spectrum of rheumatic conditions has long been discussed in the literature, focusing primarily on sexual hormones, such as estrogens, androgens, prolactin (PRL). Estrogens are indeed involved in the pathogenesis of the main inflammatory arthritis thanks to their effects on the immune system, both stimulatory and inhibitory. The PRL system has been discovered in synovial tissue of rheumatoid arthritis (RA) and psoriatic arthritis (PsA), patients and has been propose as a new potential therapeutic target. Besides sexual hormones, in the last years scientific interest about the crosstalk of immune system with other class of hormones has grown. Hormones acting on the bone tissue (i.e. parathyroid hormone, vitamin D) and modulators of the Wnt pathway (i.e. Dickkopf-1) have been demonstrated to play active role in inflammatory arthritis course, defining a new field of research named osteoimmunology. PTH, which is one of the main determinants of Dkkopf-1, plays a crucial role in bone erosions in RA and a correlation between PTH, Trabecular Bone Score (TBS) and disease activity has been found in ankylosing spondylitis (AS). In PSA is under studying the interaction among IL-17 and bone metabolism. The purpose of this review is to discuss and summarize the recent data about the interaction between endocrine hormone and immune system in the main rheumatic disorders, covering in particular the role of bone-related hormones and cytokines. We will describe this relationship from a biochemical, diagnostic and therapeutic perspective, with a particular focus on RA, PsA and AS.
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Affiliation(s)
- Eugenia Bertoldo
- Rheumatology Unit, Department of Medicine, University of Verona, Verona, Italy
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Dunn HA, Orlandi C, Martemyanov KA. Beyond the Ligand: Extracellular and Transcellular G Protein-Coupled Receptor Complexes in Physiology and Pharmacology. Pharmacol Rev 2019; 71:503-519. [PMID: 31515243 PMCID: PMC6742926 DOI: 10.1124/pr.119.018044] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
G protein-coupled receptors (GPCRs) remain one of the most successful targets of U.S. Food and Drug Administration-approved drugs. GPCR research has predominantly focused on the characterization of the intracellular interactome's contribution to GPCR function and pharmacology. However, emerging evidence uncovers a new dimension in the biology of GPCRs involving their extracellular and transcellular interactions that critically impact GPCR function and pharmacology. The seminal examples include a variety of adhesion GPCRs, such as ADGRLs/latrophilins, ADGRBs/brain angiogenesis inhibitors, ADGRG1/GPR56, ADGRG6/GPR126, ADGRE5/CD97, and ADGRC3/CELSR3. However, recent advances have indicated that class C GPCRs that contain large extracellular domains, including group III metabotropic glutamate receptors (mGluR4, mGluR6, mGluR7, mGluR8), γ-aminobutyric acid receptors, and orphans GPR158 and GPR179, can also participate in this form of transcellular regulation. In this review, we will focus on a variety of identified extracellular and transcellular GPCR-interacting partners, including teneurins, neurexins, integrins, fibronectin leucine-rich transmembranes, contactin-6, neuroligin, laminins, collagens, major prion protein, amyloid precursor protein, complement C1q-likes, stabilin-2, pikachurin, dystroglycan, complement decay-accelerating factor CD55, cluster of differentiation CD36 and CD90, extracellular leucine-rich repeat and fibronectin type III domain containing 1, and leucine-rich repeat, immunoglobulin-like domain and transmembrane domains. We provide an account on the diversity of extracellular and transcellular GPCR complexes and their contribution to key cellular and physiologic processes, including cell migration, axon guidance, cellular and synaptic adhesion, and synaptogenesis. Furthermore, we discuss models and mechanisms by which extracellular GPCR assemblies may regulate communication at cellular junctions. SIGNIFICANCE STATEMENT: G protein-coupled receptors (GPCRs) continue to be the prominent focus of pharmacological intervention for a variety of human pathologies. Although the majority of GPCR research has focused on the intracellular interactome, recent advancements have identified an extracellular dimension of GPCR modulation that alters accepted pharmacological principles of GPCRs. Herein, we describe known endogenous allosteric modulators acting on GPCRs both in cis and in trans.
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Affiliation(s)
- Henry A Dunn
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida
| | - Cesare Orlandi
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida
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Thompson MD, Capra V, Clunes MT, Rovati GE, Stankova J, Maj MC, Duffy DL. Cysteinyl Leukotrienes Pathway Genes, Atopic Asthma and Drug Response: From Population Isolates to Large Genome-Wide Association Studies. Front Pharmacol 2016; 7:299. [PMID: 27990118 PMCID: PMC5131607 DOI: 10.3389/fphar.2016.00299] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 08/24/2016] [Indexed: 02/05/2023] Open
Abstract
Genetic variants associated with asthma pathogenesis and altered response to drug therapy are discussed. Many studies implicate polymorphisms in genes encoding the enzymes responsible for leukotriene synthesis and intracellular signaling through activation of seven transmembrane domain receptors, such as the cysteinyl leukotriene 1 (CYSLTR1) and 2 (CYSLTR2) receptors. The leukotrienes are polyunsaturated lipoxygenated eicosatetraenoic acids that exhibit a wide range of pharmacological and physiological actions. Of the three enzymes involved in the formation of the leukotrienes, arachidonate 5 lipoxygenase 5 (ALOX5), leukotriene C4 synthase (LTC4S), and leukotriene hydrolase (LTA4H) are all polymorphic. These polymorphisms often result in variable production of the CysLTs (LTC4, LTD4, and LTE4) and LTB4. Variable number tandem repeat sequences located in the Sp1-binding motif within the promotor region of the ALOX5 gene are associated with leukotriene burden and bronchoconstriction independent of asthma risk. A 444A > C SNP polymorphism in the LTC4S gene, encoding an enzyme required for the formation of a glutathione adduct at the C-6 position of the arachidonic acid backbone, is associated with severe asthma and altered response to the CYSLTR1 receptor antagonist zafirlukast. Genetic variability in the CysLT pathway may contribute additively or synergistically to altered drug responses. The 601 A > G variant of the CYSLTR2 gene, encoding the Met201Val CYSLTR2 receptor variant, is associated with atopic asthma in the general European population, where it is present at a frequency of ∼2.6%. The variant was originally found in the founder population of Tristan da Cunha, a remote island in the South Atlantic, in which the prevalence of atopy is approximately 45% and the prevalence of asthma is 36%. In vitro work showed that the atopy-associated Met201Val variant was inactivating with respect to ligand binding, Ca2+ flux and inositol phosphate generation. In addition, the CYSLTR1 gene, located at Xq13-21.1, has been associated with atopic asthma. The activating Gly300Ser CYSLTR1 variant is discussed. In addition to genetic loci, risk for asthma may be influenced by environmental factors such as smoking. The contribution of CysLT pathway gene sequence variants to atopic asthma is discussed in the context of other genes and environmental influences known to influence asthma.
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Affiliation(s)
- Miles D Thompson
- Biochemical Genetics and Metabolomics Laboratory, Department of Pediatrics, University of California, San Diego, La JollaCA, USA; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ONCanada
| | - Valerie Capra
- Department of Health Sciences, San Paolo Hospital, Università degli Studi di Milano Milano, Italy
| | - Mark T Clunes
- Department of Physiology/Neuroscience, School of Medicine, Saint George's University Saint George's, Grenada
| | - G E Rovati
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano Milano, Italy
| | - Jana Stankova
- Division of Immunology and Allergy, Department of Pediatrics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke QC, Canada
| | - Mary C Maj
- Department of Biochemistry, School of Medicine, Saint George's University Saint George's, Grenada
| | - David L Duffy
- QIMR Berghofer Medical Research Institute, Herston QLD, Australia
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MacKenzie M, Hall R. Pharmacogenomics and pharmacogenetics for the intensive care unit: a narrative review. Can J Anaesth 2016; 64:45-64. [PMID: 27752976 DOI: 10.1007/s12630-016-0748-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 08/31/2016] [Accepted: 09/30/2016] [Indexed: 12/17/2022] Open
Abstract
PURPOSE Knowledge of how alterations in pharmacogenomics and pharmacogenetics may affect drug therapy in the intensive care unit (ICU) has received little study. We review the clinically relevant application of pharmacogenetics and pharmacogenomics to drugs and conditions encountered in the ICU. SOURCE We selected relevant literature to illustrate the important concepts contained within. PRINCIPAL FINDINGS Two main approaches have been used to identify genetic abnormalities - the candidate gene approach and the genome-wide approach. Genetic variability in response to drugs may occur as a result of alterations of drug-metabolizing (cytochrome P [CYP]) enzymes, receptors, and transport proteins leading to enhancement or delay in the therapeutic response. Of relevance to the ICU, genetic variation in CYP-450 isoenzymes results in altered effects of midazolam, fentanyl, morphine, codeine, phenytoin, clopidogrel, warfarin, carvedilol, metoprolol, HMG-CoA reductase inhibitors, calcineurin inhibitors, non-steroidal anti-inflammatory agents, proton pump inhibitors, and ondansetron. Changes in cholinesterase enzyme function may affect the disposition of succinylcholine, benzylisoquinoline muscle relaxants, remifentanil, and hydralazine. Genetic variation in transport proteins leads to differences in the response to opioids and clopidogrel. Polymorphisms in drug receptors result in altered effects of β-blockers, catecholamines, antipsychotic agents, and opioids. Genetic variation also contributes to the diversity and incidence of diseases and conditions such as sepsis, malignant hyperthermia, drug-induced hypersensitivity reactions, cardiac channelopathies, thromboembolic disease, and congestive heart failure. CONCLUSION Application of pharmacogenetics and pharmacogenomics has seen improvements in drug therapy. Ongoing study and incorporation of these concepts into clinical decision making in the ICU has the potential to affect patient outcomes.
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Affiliation(s)
- Meghan MacKenzie
- Pharmacy Department, Nova Scotia Health Authority, Halifax, NS, Canada.,College of Pharmacy, Dalhousie University, Halifax, NS, Canada
| | - Richard Hall
- Departments of Anesthesia, Pain Management and Perioperative Medicine and Critical Care Medicine and Pharmacology, Dalhousie University and the Nova Scotia Health Authority, Halifax, NS, B3H 3A7, Canada.
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Thompson MD, Kenna GA. Variation in the Serotonin Transporter Gene and Alcoholism: Risk and Response to Pharmacotherapy. Alcohol Alcohol 2015; 51:164-71. [PMID: 26311211 DOI: 10.1093/alcalc/agv090] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 07/15/2015] [Indexed: 01/06/2023] Open
Abstract
SLC6A4, the gene encoding the serotonin transporter protein (5-HTT), has been extensively examined as a risk factor for alcohol dependence (AD). More recently, variability in the transporter gene was identified to be a potential moderator of treatment response to serotonergic medications such as ondansetron and sertraline. There is an insertion-deletion polymorphism in the promoter region (5-HTTLPR) of the SLC6A4, with the most common alleles being a 14-repeat short (S) allele and a 16-repeat long (L) allele. The S allele has often been associated with AD. By contrast, the L allele has been associated with pharmacological responsiveness in some individuals with AD. Differences in clinical phenotype may determine the utility of the 5-HTTLPR polymorphism as a moderator of pharmacological interventions for AD. We review the AD typology and disease onset in the context of pharmacogenetic and genomic studies that examine the utility of 5-HTTLPR in improving treatment outcomes.
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Affiliation(s)
- Miles D Thompson
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada
| | - George A Kenna
- Center for Alcohol and Addiction Studies, Brown University, Providence, RI, USA
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Thompson MD, Hendy GN, Percy ME, Bichet DG, Cole DEC. G protein-coupled receptor mutations and human genetic disease. Methods Mol Biol 2015; 1175:153-87. [PMID: 25150870 DOI: 10.1007/978-1-4939-0956-8_8] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Genetic variations in G protein-coupled receptor genes (GPCRs) disrupt GPCR function in a wide variety of human genetic diseases. In vitro strategies and animal models have been used to identify the molecular pathologies underlying naturally occurring GPCR mutations. Inactive, overactive, or constitutively active receptors have been identified that result in pathology. These receptor variants may alter ligand binding, G protein coupling, receptor desensitization and receptor recycling. Receptor systems discussed include rhodopsin, thyrotropin, parathyroid hormone, melanocortin, follicle-stimulating hormone (FSH), luteinizing hormone, gonadotropin-releasing hormone (GNRHR), adrenocorticotropic hormone, vasopressin, endothelin-β, purinergic, and the G protein associated with asthma (GPRA or neuropeptide S receptor 1 (NPSR1)). The role of activating and inactivating calcium-sensing receptor (CaSR) mutations is discussed in detail with respect to familial hypocalciuric hypercalcemia (FHH) and autosomal dominant hypocalemia (ADH). The CASR mutations have been associated with epilepsy. Diseases caused by the genetic disruption of GPCR functions are discussed in the context of their potential to be selectively targeted by drugs that rescue altered receptors. Examples of drugs developed as a result of targeting GPCRs mutated in disease include: calcimimetics and calcilytics, therapeutics targeting melanocortin receptors in obesity, interventions that alter GNRHR loss from the cell surface in idiopathic hypogonadotropic hypogonadism and novel drugs that might rescue the P2RY12 receptor congenital bleeding phenotype. De-orphanization projects have identified novel disease-associated receptors, such as NPSR1 and GPR35. The identification of variants in these receptors provides genetic reagents useful in drug screens. Discussion of the variety of GPCRs that are disrupted in monogenic Mendelian disorders provides the basis for examining the significance of common pharmacogenetic variants.
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Affiliation(s)
- Miles D Thompson
- Department of Pharmacology, University of Toronto, 1 King's College Circle, Toronto, ON, Canada, M5S 1A8,
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Ragnarsson L, Andersson Å, Thomas WG, Lewis RJ. Extracellular surface residues of the α1B-adrenoceptor critical for G protein-coupled receptor function. Mol Pharmacol 2015; 87:121-9. [PMID: 25352041 DOI: 10.1124/mol.114.094557] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2025] Open
Abstract
Ligand binding and conformational changes that accompany signaling from G protein-coupled receptors (GPCRs) have mostly focused on the role of transmembrane helices and intracellular loop regions. However, recent studies, including several GPCRs cocrystallized with bound ligands, suggest that the extracellular surface (ECS) of GPCRs plays an important role in ligand recognition, selectivity, and binding, as well as potentially contributing to receptor activation and signaling. This study applied alanine-scanning mutagenesis to investigate the role of the complete ECS of the α1B-adrenoreceptor on norepinephrine (NE) potency, affinity, and efficacy. Half (24 of 48) of the ECS mutations significantly decreased NE potency in an inositol 1-phosphate assay. Most mutations reduced NE affinity (17) determined from [(3)H]prazosin displacement studies, whereas four mutations at the entrance to the NE binding pocket enhanced NE affinity. Removing the influence of NE affinity and receptor expression levels on NE potency gave a measure of NE efficacy, which was significantly decreased for 11 of 48 ECS mutants. These different effects tended to cluster to different regions of the ECS, which is consistent with different regions of the ECS playing discrete functional roles. Exposed ECS residues at the entrance to the NE binding pocket mostly affected NE affinity, whereas buried or structurally significant residues mostly affected NE efficacy. The broad potential for ECS mutations to affect GPCR function has relevance for the increasing number of nonsynonymous single nucleotide polymorphisms now being identified in GPCRs.
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Affiliation(s)
- Lotten Ragnarsson
- Institute for Molecular Bioscience (L.R., Å.A., R.J.L.) and School of Biomedical Sciences (W.G.T.), The University of Queensland, Brisbane, Queensland, Australia
| | - Åsa Andersson
- Institute for Molecular Bioscience (L.R., Å.A., R.J.L.) and School of Biomedical Sciences (W.G.T.), The University of Queensland, Brisbane, Queensland, Australia
| | - Walter G Thomas
- Institute for Molecular Bioscience (L.R., Å.A., R.J.L.) and School of Biomedical Sciences (W.G.T.), The University of Queensland, Brisbane, Queensland, Australia
| | - Richard J Lewis
- Institute for Molecular Bioscience (L.R., Å.A., R.J.L.) and School of Biomedical Sciences (W.G.T.), The University of Queensland, Brisbane, Queensland, Australia
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Thompson MD, Xhaard H, Sakurai T, Rainero I, Kukkonen JP. OX1 and OX2 orexin/hypocretin receptor pharmacogenetics. Front Neurosci 2014; 8:57. [PMID: 24834023 PMCID: PMC4018553 DOI: 10.3389/fnins.2014.00057] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2013] [Accepted: 03/12/2014] [Indexed: 01/01/2023] Open
Abstract
Orexin/hypocretin peptide mutations are rare in humans. Even though human narcolepsy is associated with orexin deficiency, this is only extremely rarely due to mutations in the gene coding prepro-orexin, the precursor for both orexin peptides. In contrast, coding and non-coding variants of the OX1 and OX2 orexin receptors have been identified in many human populations; sometimes, these have been associated with disease phenotype, although most confer a relatively low risk. In most cases, these studies have been based on a candidate gene hypothesis that predicts the involvement of orexins in the relevant pathophysiological processes. In the current review, the known human OX1/HCRTR1 and OX2/HCRTR2 genetic variants/polymorphisms as well as studies concerning their involvement in disorders such as narcolepsy, excessive daytime sleepiness, cluster headache, polydipsia-hyponatremia in schizophrenia, and affective disorders are discussed. In most cases, the functional cellular or pharmacological correlates of orexin variants have not been investigated—with the exception of the possible impact of an amino acid 10 Pro/Ser variant of OX2 on orexin potency—leaving conclusions on the nature of the receptor variant effects speculative. Nevertheless, we present perspectives that could shape the basis for further studies. The pharmacology and other properties of the orexin receptor variants are discussed in the context of GPCR signaling. Since orexinergic therapeutics are emerging, the impact of receptor variants on the affinity or potency of ligands deserves consideration. This perspective (pharmacogenetics) is also discussed in the review.
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Affiliation(s)
- Miles D Thompson
- University of Toronto Epilepsy Research Program, Department of Pharmacology, University of Toronto Toronto, ON, Canada
| | - Henri Xhaard
- Faculty of Pharmacy, Centre for Drug Research, University of Helsinki Helsinki, Finland
| | - Takeshi Sakurai
- Department of Molecular Neuroscience and Integrative Physiology, Faculty of Medicine, Kanazawa University Kanazawa, Japan
| | | | - Jyrki P Kukkonen
- Biochemistry and Cell Biology, Department of Veterinary Biosciences, University of Helsinki Helsinki, Finland
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G protein-coupled receptor accessory proteins and signaling: pharmacogenomic insights. Methods Mol Biol 2014; 1175:121-52. [PMID: 25150869 DOI: 10.1007/978-1-4939-0956-8_7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The identification and characterization of the genes encoding G protein-coupled receptors (GPCRs) and the proteins necessary for the processes of ligand binding, GPCR activation, inactivation, and receptor trafficking to the membrane are discussed in the context of human genetic disease. In addition to functional GPCR variants, the identification of genetic disruptions affecting proteins necessary to GPCR functions have provided insights into the function of these pathways. Gsα and Gβ subunit polymorphisms have been found to result in complex phenotypes. Disruptions in accessory proteins that normally modify or organize heterotrimeric G-protein coupling may also result in disease states. These include the contribution of variants of the regulator of G protein signaling (RGS) protein to hypertension; the role variants of the activator of G protein signaling (AGS) proteins to phenotypes (such as the type III AGS8 variant to hypoxia); the contribution of G protein-coupled receptor kinase (GRK) proteins, such as GRK4, in disorders such as hypertension. The role of accessory proteins in GPCR structure and function is discussed in the context of genetic disorders associated with disruption of the genes that encode them. An understanding of the pharmacogenomics of GPCR and accessory protein signaling provides the basis for examining both GPCR pharmacogenetics and the genetics of monogenic disorders that result from disruption of given receptor systems.
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Thompson MD, Cole DEC, Capra V, Siminovitch KA, Rovati GE, Burnham WM, Rana BK. Pharmacogenetics of the G protein-coupled receptors. Methods Mol Biol 2014; 1175:189-242. [PMID: 25150871 DOI: 10.1007/978-1-4939-0956-8_9] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Pharmacogenetics investigates the influence of genetic variants on physiological phenotypes related to drug response and disease, while pharmacogenomics takes a genome-wide approach to advancing this knowledge. Both play an important role in identifying responders and nonresponders to medication, avoiding adverse drug reactions, and optimizing drug dose for the individual. G protein-coupled receptors (GPCRs) are the primary target of therapeutic drugs and have been the focus of these studies. With the advance of genomic technologies, there has been a substantial increase in the inventory of naturally occurring rare and common GPCR variants. These variants include single-nucleotide polymorphisms and insertion or deletions that have potential to alter GPCR expression of function. In vivo and in vitro studies have determined functional roles for many GPCR variants, but genetic association studies that define the physiological impact of the majority of these common variants are still limited. Despite the breadth of pharmacogenetic data available, GPCR variants have not been included in drug labeling and are only occasionally considered in optimizing clinical use of GPCR-targeted agents. In this chapter, pharmacogenetic and genomic studies on GPCR variants are reviewed with respect to a subset of GPCR systems, including the adrenergic, calcium sensing, cysteinyl leukotriene, cannabinoid CB1 and CB2 receptors, and the de-orphanized receptors such as GPR55. The nature of the disruption to receptor function is discussed with respect to regulation of gene expression, expression on the cell surface (affected by receptor trafficking, dimerization, desensitization/downregulation), or perturbation of receptor function (altered ligand binding, G protein coupling, constitutive activity). The large body of experimental data generated on structure and function relationships and receptor-ligand interactions are being harnessed for the in silico functional prediction of naturally occurring GPCR variants. We provide information on online resources dedicated to GPCRs and present applications of publically available computational tools for pharmacogenetic studies of GPCRs. As the breadth of GPCR pharmacogenomic data becomes clearer, the opportunity for routine assessment of GPCR variants to predict disease risk, drug response, and potential adverse drug effects will become possible.
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Affiliation(s)
- Miles D Thompson
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON, Canada, M5S 1A8,
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16
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Ma JN, Burstein ES. The protease activated receptor 2 (PAR2) polymorphic variant F240S constitutively activates PAR2 receptors and potentiates responses to small-molecule PAR2 agonists. J Pharmacol Exp Ther 2013; 347:697-704. [PMID: 24078870 DOI: 10.1124/jpet.113.208744] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
AC-55541 [N-[[1-(3-bromo-phenyl)-eth-(E)-ylidene-hydrazinocarbonyl]-(4-oxo-3,4-dihydro-phthalazin-1-yl)-methyl]-benzamide] and AC-264613 [2-oxo-4-phenylpyrrolidine-3-carboxylic acid [1-(3-bromo-phenyl)-(E/Z)-ethylidene]-hydrazide] are the first two small-molecule agonists described for the G protein-coupled receptor protease-activated receptor 2 (PAR2), but whether they activate PAR2 through a similar mechanism as its tethered peptide ligand or soluble peptide mimetics of its tethered peptide ligand is unclear. Extracellular loop 2 (ECL2) has been shown to play a critical role in the activation mechanism of PAR2. Therefore, we constructed a series of PAR2 receptors mutated in ECL2, including a previously described polymorphic variant of PAR2 (F240S), and compared AC-55541 and AC-264613 to SLIGRL and a potent analog of SLIGRL called 2-furoyl LIGRLO in a series of functional assays, including cellular proliferation, phosphatidylinositol hydrolysis, and β-arrestin recruitment assays. Surprisingly, receptors with the F240S mutation were constitutively active in all functional assays tested. Furthermore, AC-55541 and AC-264613 were potentiated over 30-fold at the receptors with the F240S mutation, whereas SLIGRL and 2-furoyl LIGRLO were much less affected. In contrast, mutagenesis of charged residues in ECL2 confirmed their important role in the actions of peptide agonists of PAR2, whereas these mutations did not significantly affect activation of PAR2 by AC-55541 or AC-264613. These results suggest that F240S PAR2 receptors may be useful in screens to detect novel small-molecule PAR2 modulators and that further work on the biological importance of the F240S PAR2 variant is warranted.
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Affiliation(s)
- Jian-Nong Ma
- ACADIA Pharmaceuticals Inc., San Diego, California
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Gpr171, a putative P2Y-like receptor, negatively regulates myeloid differentiation in murine hematopoietic progenitors. Exp Hematol 2012; 41:102-12. [PMID: 23022127 DOI: 10.1016/j.exphem.2012.09.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 08/29/2012] [Accepted: 09/10/2012] [Indexed: 11/23/2022]
Abstract
Gpr171 is an orphan G-protein-coupled receptor putatively related to the P2Y family of purinergic receptors (P2YRs) for extracellular nucleotides, a group of mediators previously shown to regulate hematopoietic progenitor cells. No information is currently available on the ligand responsible for Gpr171 activation and its biological role remains unknown. We reconstructed Gpr171 phylogenesis in mice and confirmed that Gpr171 is evolutionally related to members of a P2Y gene-cluster localized on mouse chromosome 3. As a first step toward unveiling a role for Gpr171, we investigated its expression profile in murine hematopoietic cells. As opposed to other P2YRs, we found that Gpr171 expression is down-regulated in monocytes and granulocytes, suggesting a negative role in myeloid lineage specification. To test Gpr171 functional role, we next enforced Gpr171 expression in a myeloblastic cell line (32D cells) and in primary Sca-1(+) hematopoietic progenitors, and observed a decreased expression of myeloid markers upon induction of Gpr171, as well as an increased generation of colonies in vitro. Conversely, Gpr171 silencing induced opposite results, diminishing the expression of myeloid markers and the clonogenic potential of 32D cells. In vivo, mice transplanted with hematopoietic progenitor cells overexpressing Gpr171 displayed a significant reduction in the percentage of Mac-1(+)Gr-1(-) cells. As a preliminary step in the investigation of Gpr171 role in murine hematopoiesis, our findings indicate that the orphan receptor Gpr171 negatively regulates myeloid differentiation. Together with phylogenic analyses, our data suggest that Gpr171 may have followed a separate evolutionary pathway as compared to other P2YRs belonging to the same gene cluster.
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Abstract
Migraine with aura (MA) may share some but not all risk factors with other forms of migraine. As common migraine without aura (MO) has been associated with the chromosome 1p36 locus, we tested its involvement in MA by using two-point parametric linkage analysis to analyze 64 multiplex MA families. A logarithm of the odds score of 1.9 was suggestive of chromosome 1p36 linkage to MA. The transmission disequilibrium test analysis was then performed in 79 nuclear families with one MA parent and one MA offspring. We identified the presence of genetic association at chromosome 1p36 with MA (P=0.045, Bonferroni corrected): the locus encoding the 5HT(1D) receptor gene. Although these data suggest that the 1p36 locus may protect against MA, consistent with the role of the 5HT(1D) receptor in migraine treatment with triptan drugs, the study is subject to the limitations associated with studying a small number of affected families. As a result, we contrast evidence suggesting that the chromosome 1p36 locus is strongly MO associated with our finding that 1p36 has a more limited contribution to MA in the families we analyzed. Further work using a genome-wide association study approach in familial typical migraine, consisting of those affected by MO or MA, will serve to further distinguish how and why MA differs from MO.
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Xiao Y, He W, Russell IJ. Genetic polymorphisms of the beta2-adrenergic receptor relate to guanosine protein-coupled stimulator receptor dysfunction in fibromyalgia syndrome. J Rheumatol 2011; 38:1095-103. [PMID: 21406495 DOI: 10.3899/jrheum.101104] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE To determine the genotype frequencies of ß(2)-adrenergic receptor (ß(2)AR) gene polymorphisms (Gly16Arg, Glu27Gln) in patients with fibromyalgia syndrome (FM) by comparison with unrelated healthy controls. We sought any clinical association with these polymorphisms and determined whether the polymorphisms would associate with a biologic guanosine protein-coupled stimulator receptor (Gs) dysfunction in FM. METHODS Study subjects included 97 clinically characterized patients with FM and 59 controls. The ß(2)AR polymorphisms at codons 16 and 27 were determined using polymerase chain reaction-restriction fragment length polymorphism. The Gs functions of peripheral blood mononuclear cells (PBMC) were tested using isoproterenol (ISO) as the adrenergic Gs ligand and measuring intracellular cyclic adenosine monophosphate (cAMP) levels. RESULTS The frequency of the ß(2)AR gene polymorphism Gly16Arg in FM (43.5%) was significantly lower than in controls (63.2%), suggesting that this genotype might have some effect on the risk of developing FM. The only clinical association in FM was with sleep dysfunction. Patients with FM who carried the ß(2)AR polymorphism Arg16Arg also exhibited significantly lower PBMC basal cAMP levels (p < 0.05) and lower ISO-stimulated cAMP levels (p < 0.05) than FM carrying Gly16Gly or Gly16Arg. CONCLUSION This confirms a relationship between ß(2)AR polymorphism and FM. It is the first study to demonstrate ß(2)AR polymorphism-related differences in intracellular cAMP responses of FM PBMC after ß(2)AR stimulation in vitro. These findings may explain some of the differences in responsiveness of FM subgroups to the adrenergic agonist medications currently approved for FM treatment.
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Affiliation(s)
- Yangming Xiao
- Division of Clinical Immunology, Department of Medicine, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA.
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Parhamifar L, Sime W, Yudina Y, Vilhardt F, Mörgelin M, Sjölander A. Ligand-induced tyrosine phosphorylation of cysteinyl leukotriene receptor 1 triggers internalization and signaling in intestinal epithelial cells. PLoS One 2010; 5:e14439. [PMID: 21203429 PMCID: PMC3010979 DOI: 10.1371/journal.pone.0014439] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Accepted: 11/30/2010] [Indexed: 12/17/2022] Open
Abstract
Background Leukotriene D4 (LTD4) belongs to the bioactive lipid group known as eicosanoids and has implications in pathological processes such as inflammation and cancer. Leukotriene D4 exerts its effects mainly through two different G-protein-coupled receptors, CysLT1 and CysLT2. The high affinity LTD4 receptor CysLT1R exhibits tumor-promoting properties by triggering cell proliferation, survival, and migration in intestinal epithelial cells. In addition, increased expression and nuclear localization of CysLT1R correlates with a poorer prognosis for patients with colon cancer. Methodology/Principal Findings Using a proximity ligation assay and immunoprecipitation, this study showed that endogenous CysLT1R formed heterodimers with its counter-receptor CysLT2R under basal conditions and that LTD4 triggers reduced dimerization of CysLTRs in intestinal epithelial cells. This effect was dependent upon a parallel LTD4-induced increase in CysLT1R tyrosine phosphorylation. Leukotriene D4 also led to elevated internalization of CysLT1Rs from the plasma membrane and a simultaneous increase at the nucleus. Using sucrose, a clathrin endocytic inhibitor, dominant-negative constructs, and siRNA against arrestin-3, we suggest that a clathrin-, arrestin-3, and Rab-5-dependent process mediated the internalization of CysLT1R. Altering the CysLT1R internalization process at either the clathrin or the arrestin-3 stage led to disruption of LTD4-induced Erk1/2 activation and up-regulation of COX-2 mRNA levels. Conclusions/Significance Our data suggests that upon ligand activation, CysLT1R is tyrosine-phosphorylated and released from heterodimers with CysLT2R and, subsequently, internalizes from the plasma membrane to the nuclear membrane in a clathrin-, arrestin-3-, and Rab-5-dependent manner, thus, enabling Erk1/2 signaling and downstream transcription of the COX-2 gene.
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Affiliation(s)
- Ladan Parhamifar
- Cell and Experimental Pathology, Department of Laboratory Medicine, Clinical Research Center, Lund University, Skåne University Hospital, Malmö, Sweden
| | - Wondossen Sime
- Cell and Experimental Pathology, Department of Laboratory Medicine, Clinical Research Center, Lund University, Skåne University Hospital, Malmö, Sweden
| | - Yuliana Yudina
- Cell and Experimental Pathology, Department of Laboratory Medicine, Clinical Research Center, Lund University, Skåne University Hospital, Malmö, Sweden
| | - Frederik Vilhardt
- Institute of Cellular and Molecular Medicine, Panum Institute, Copenhagen University, Copenhagen, Denmark
| | - Matthias Mörgelin
- Infectious Medicine, Department of Clinical Science, Lund University, Lund, Sweden
| | - Anita Sjölander
- Cell and Experimental Pathology, Department of Laboratory Medicine, Clinical Research Center, Lund University, Skåne University Hospital, Malmö, Sweden
- * E-mail:
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Torigoe H, Ono A, Kozasa T. Detection of single nucleotide polymorphisms by the specific interaction between transition metal ions and mismatched base pairs in duplex DNA. TRANSIT METAL CHEM 2010. [DOI: 10.1007/s11243-010-9445-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Functional consequences of nonsynonymous single nucleotide polymorphisms in the CB2 cannabinoid receptor. Pharmacogenet Genomics 2010; 20:157-66. [PMID: 20124950 DOI: 10.1097/fpc.0b013e3283367c6b] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE To test the hypothesis that the two nonsynonymous single nucleotide polymorphisms at the CB2 cannabinoid receptor gene may have functional consequences on human CB2. METHODS Q63R, H316Y, and Q63R/H316 mutations were made in recombinant human CB2 by the method of site-directed mutagenesis. After these mutant CB2 receptors were stably transfected into HEK293 cells, ligand binding, ligand-induced activity, and constitutive activity assays were performed to test the functional significance of these mutations. RESULTS In general, our results showed that the CB2 polymorphic receptors are able to bind cannabinoid ligands and mediate signal transduction. However, in ligand-induced cyclic AMP accumulation assays, the cannabinoid agonists WIN55212-2 and 2-arachidonoylglycerol had reduced efficacy in cells expressing the polymorphic receptors as compared with the CB2 wild-type receptor. Furthermore, in constitutive activity assays, the H316Y and Q63R/H316Y polymorphic receptors exhibited higher constitutive activity than the CB2 wild-type receptor. CONCLUSION Our data shows that the presence of the polymorphisms at both positions 63 and 316 produce alterations in the CB2 receptor functions. Moreover, these findings strengthen the idea that the CB2 polymorphic receptors may contribute to the etiology of certain diseases.
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Morgan NG, Dhayal S. Unsaturated fatty acids as cytoprotective agents in the pancreatic beta-cell. Prostaglandins Leukot Essent Fatty Acids 2010; 82:231-6. [PMID: 20206490 DOI: 10.1016/j.plefa.2010.02.018] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
It is widely accepted that, in type 2 diabetes, elevated levels of free fatty acids and glucose contribute to a state of glucolipotoxicity in which beta-cell function declines and, ultimately, cell viability is compromised. This suggests that beta-cells do not readily tolerate chronic elevations in fatty acid levels. In vitro studies suggest, however, that beta-cells respond differentially to long chain fatty acids, such that saturated species are lipotoxic whereas long chain mono-unsaturated fatty acids can provide cytoprotection. This difference does not appear to be mediated by a mutual metabolic antagonism between saturated and unsaturated species (although differential alterations in neutral lipid disposition may occur in response to these fatty acids) and the mechanisms remain unclear. This review summaries the current understanding of the actions of mono-unsaturated fatty acids in beta-cells and highlights areas of controversy as well as key unresolved issues which require to be addressed.
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Affiliation(s)
- Noel G Morgan
- Institute of Biomedical & Clinical Science, Peninsula Medical School (University of Exeter), Plymouth, UK.
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Watelet JB, Gillard M, Benedetti MS, Lelièvre B, Diquet B. Therapeutic management of allergic diseases. Drug Metab Rev 2009; 41:301-43. [PMID: 19601717 DOI: 10.1080/10837450902891204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Allergic diseases are characterized by the activation of inflammatory cells and by a massive release of mediators. The aim of this chapter was to describe succinctly the modes of action, indications, and side effects of the major antiallergic and antiasthmatic drugs. When considering the ideal pharmacokinetic characteristics of a drug, a poorly metabolized drug may confer a lower variability in plasma concentrations and metabolism-based drug interactions, although poorly metabolized drugs may be prone to transporter-based disposition and interactions. The ideal pharmacological properties of a drug include high binding affinity, high selectivity, and appropriate association and dissociation rates. Finally, from a patient perspective, the frequency and route of administration are important considerations for ease of use.
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Affiliation(s)
- Jean-Baptiste Watelet
- Department of Otohinolaryngology, Head and Neck Surgery, Ghent University Hospital, Ghent University, Belgium.
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Smith NJ, Stoddart LA, Devine NM, Jenkins L, Milligan G. The action and mode of binding of thiazolidinedione ligands at free fatty acid receptor 1. J Biol Chem 2009; 284:17527-39. [PMID: 19398560 DOI: 10.1074/jbc.m109.012849] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The endogenous ligands for free fatty acid receptor 1 (FFA1) are medium and longer chain free fatty acids. However, a range of selective, small molecule ligands have recently been developed as tool compounds to explore the therapeutic potential of this receptor, whereas clinically employed thiazolidinedione "glitazone" drugs are also agonists at FFA1. Each of these classes of agonist was able to promote phosphorylation of the ERK1/2 mitogen-activated protein (MAP) kinases in cells able to express human FFA1 on demand. However, although both lauric acid and the synthetic agonist GW9508X produced rapid and transient ERK1/2 MAP kinase phosphorylation, the thiazolidinedione rosiglitazone produced responses that were sustained for a substantially longer period. Despite this difference, the effects of each ligand required FFA1 and were transduced in each case predominantly via G proteins of the Galphaq/Galpha11 family. Different glitazone drugs also displayed markedly different efficacy and kinetics of sustainability of ERK1/2 MAP kinase phosphorylation. A number of orthosteric binding site mutants of FFA1 were generated, and despite variations in the changes of potency and efficacy of the three ligand classes in different functional end point assays, these were consistent with rosiglitazone also binding at the orthosteric site. Four distinct polymorphic variants of human FFA1 have been described. Despite previous indications that these display differences in function and pharmacology, they all responded in entirely equivalent ways to lauric acid, rosiglitazone, and GW9508X in measures of ERK1/2 MAP kinase phosphorylation, enhancement of binding of [35S]GTPgammaS (guanosine 5'-O-(3-[35S]thio)triphosphate) to Galphaq, and elevation of intracellular [Ca2+], suggesting that individuals expressing each variant are likely to respond equivalently to orthosteric agonists of FFA1.
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Affiliation(s)
- Nicola J Smith
- Molecular Pharmacology Group, Neuroscience and Molecular Pharmacology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
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