1
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Brust CA, Swanson MA, Bohn LM. Structural and functional insights into the G protein-coupled receptors: CB1 and CB2. Biochem Soc Trans 2023; 51:1533-1543. [PMID: 37646476 PMCID: PMC10586759 DOI: 10.1042/bst20221316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 07/31/2023] [Accepted: 08/01/2023] [Indexed: 09/01/2023]
Abstract
The cannabinoid receptors CB1 and CB2 mediate a variety of physiological processes and continue to be explored as desirable drug targets. Both receptors are activated by the endogenous endocannabinoids and the psychoactive components of marijuana. Over the years, many efforts have been made to make selective ligands; however, the high degree of homology between cannabinoid receptor subtypes introduces challenges in studying either receptor in isolation. Recent advancements in structure biology have resulted in a surge of high-resolution structures, enriching our knowledge and understanding of receptor structure and function. In this review, of recent cannabinoid receptor structures, key features of the inactive and active state CB1 and CB2 are presented. These structures will provide additional insight into the modulation and signaling mechanism of cannabinoid receptors CB1 and CB2 and aid in the development of future therapeutics.
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Affiliation(s)
- Christina A. Brust
- Department of Molecular Medicine, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation and Technology, Jupiter, FL 33458, U.S.A
- The Skaggs Graduate School of Chemical and Biological Sciences at Scripps Research, La Jolla, CA 92037, U.S.A
| | - Matthew A. Swanson
- Department of Molecular Medicine, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation and Technology, Jupiter, FL 33458, U.S.A
- The Skaggs Graduate School of Chemical and Biological Sciences at Scripps Research, La Jolla, CA 92037, U.S.A
| | - Laura M. Bohn
- Department of Molecular Medicine, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation and Technology, Jupiter, FL 33458, U.S.A
- The Skaggs Graduate School of Chemical and Biological Sciences at Scripps Research, La Jolla, CA 92037, U.S.A
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2
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Shoeib AM, Yarbrough AL, Ford BM, Franks LN, Urbaniak A, Hensley LL, Benson LN, Mu S, Radominska-Pandya A, Prather PL. Characterization of cannabinoid receptors expressed in Ewing sarcoma TC-71 and A-673 cells as potential targets for anti-cancer drug development. Life Sci 2021; 285:119993. [PMID: 34592231 PMCID: PMC10395316 DOI: 10.1016/j.lfs.2021.119993] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 09/10/2021] [Accepted: 09/19/2021] [Indexed: 10/20/2022]
Abstract
AIMS Characterizing cannabinoid receptors (CBRs) expressed in Ewing sarcoma (EWS) cell lines as potential targets for anti-cancer drug development. MAIN METHODS CBR affinity and function were examined by competitive binding and G-protein activation, respectively. Cannabinoid-mediated cytotoxicity and cell viability were evaluated by LDH, and trypan blue assays, respectively. KEY FINDINGS qRT-PCR detected CB1 (CB1R) and CB2 receptor (CB2R) mRNA in TC-71 cells. However, binding screens revealed that CBRs expressed exhibit atypical properties relative to canonical receptors, because specific binding in TC-71 could only be demonstrated by the established non-selective CB1/CB2R radioligand [3H]WIN-55,212-2, but not CB1/CB2R radioligand [3H]CP-55,940. Homologous receptor binding demonstrated that [3H]WIN-55,212-2 binds to a single site with nanomolar affinity, expressed at high density. Further support for non-canonical CBRs expression is provided by subsequent binding screens, revealing that only 9 out of 28 well-characterized cannabinoids with high affinity for canonical CB1 and/or CB2Rs were able to displace [3H]WIN-55,212-2, whereas two ligands enhanced [3H]WIN-55,212-2 binding. Five cannabinoids producing the greatest [3H]WIN-55,212-2 displacement exhibited high nanomolar affinity (Ki) for expressed receptors. G-protein modulation and adenylyl cyclase assays further indicate that these CBRs exhibit distinct signaling/functional profiles compared to canonical CBRs. Importantly, cannabinoids with the highest affinity for non-canonical CBRs reduced TC-71 viability and induced cytotoxicity in a time-dependent manner. Studies in a second EWS cell line (A-673) showed similar atypical binding properties of expressed CBRs, and cannabinoid treatment produced cytotoxicity. SIGNIFICANCE Cannabinoids induce cytotoxicity in EWS cell lines via non-canonical CBRs, which might be a potential therapeutic target to treat EWS.
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Affiliation(s)
- Amal M Shoeib
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Azure L Yarbrough
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Benjamin M Ford
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Lirit N Franks
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Alicja Urbaniak
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Lori L Hensley
- Department of Biology, Jacksonville State University, Jacksonville, AL, United States of America
| | - Lance N Benson
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Shengyu Mu
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Anna Radominska-Pandya
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Paul L Prather
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America.
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3
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Howlett AC, Thomas BF, Huffman JW. The Spicy Story of Cannabimimetic Indoles. Molecules 2021; 26:6190. [PMID: 34684770 PMCID: PMC8538531 DOI: 10.3390/molecules26206190] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 10/07/2021] [Accepted: 10/08/2021] [Indexed: 11/17/2022] Open
Abstract
The Sterling Research Group identified pravadoline as an aminoalkylindole (AAI) non-steroidal anti-inflammatory pain reliever. As drug design progressed, the ability of AAI analogs to block prostaglandin synthesis diminished, and antinociceptive activity was found to result from action at the CB1 cannabinoid receptor, a G-protein-coupled receptor (GPCR) abundant in the brain. Several laboratories applied computational chemistry methods to ultimately conclude that AAI and cannabinoid ligands could overlap within a common binding pocket but that WIN55212-2 primarily utilized steric interactions via aromatic stacking, whereas cannabinoid ligands required some electrostatic interactions, particularly involving the CB1 helix-3 lysine. The Huffman laboratory identified strategies to establish CB2 receptor selectivity among cannabimimetic indoles to avoid their CB1-related adverse effects, thereby stimulating preclinical studies to explore their use as anti-hyperalgesic and anti-allodynic pharmacotherapies. Some AAI analogs activate novel GPCRs referred to as "Alkyl Indole" receptors, and some AAI analogs act at the colchicine-binding site on microtubules. The AAI compounds having the greatest potency to interact with the CB1 receptor have found their way into the market as "Spice" or "K2". The sale of these alleged "herbal products" evades FDA consumer protections for proper labeling and safety as a medicine, as well as DEA scheduling as compounds having no currently accepted medical use and a high potential for abuse. The distribution to the public of potent alkyl indole synthetic cannabimimetic chemicals without regard for consumer safety contrasts with the adherence to regulatory requirements for demonstration of safety that are routinely observed by ethical pharmaceutical companies that market medicines.
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Affiliation(s)
- Allyn C. Howlett
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Brian F. Thomas
- Department of Analytical Sciences, The Cronos Group, Toronto, ON M5V 2H1, Canada;
| | - John W. Huffman
- Department of Chemistry, Clemson University, Clemson, SC 29634, USA;
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4
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Murata Y, Harada N, Kishino S, Iwasaki K, Ikeguchi-Ogura E, Yamane S, Kato T, Kanemaru Y, Sankoda A, Hatoko T, Kiyobayashi S, Ogawa J, Hirasawa A, Inagaki N. Medium-chain triglycerides inhibit long-chain triglyceride-induced GIP secretion through GPR120-dependent inhibition of CCK. iScience 2021; 24:102963. [PMID: 34466786 PMCID: PMC8382997 DOI: 10.1016/j.isci.2021.102963] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 01/14/2021] [Accepted: 08/05/2021] [Indexed: 12/13/2022] Open
Abstract
Long-chain triglycerides (LCTs) intake strongly stimulates GIP secretion from enteroendocrine K cells and induces obesity and insulin resistance partly due to GIP hypersecretion. In this study, we found that medium-chain triglycerides (MCTs) inhibit GIP secretion after single LCT ingestion and clarified the mechanism underlying MCT-induced inhibition of GIP secretion. MCTs reduced the CCK effect after single LCT ingestion in wild-type (WT) mice, and a CCK agonist completely reversed MCT-induced inhibition of GIP secretion. In vitro studies showed that medium-chain fatty acids (MCFAs) inhibit long-chain fatty acid (LCFA)-stimulated CCK secretion and increase in intracellular Ca2+ concentrations through inhibition of GPR120 signaling. Long-term administration of MCTs reduced obesity and insulin resistance in high-LCT diet-fed WT mice, but not in high-LCT diet-fed GIP-knockout mice. Thus, MCT-induced inhibition of GIP hypersecretion reduces obesity and insulin resistance under high-LCT diet feeding condition.
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Affiliation(s)
- Yuki Murata
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
| | - Norio Harada
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
| | - Shigenobu Kishino
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Kanako Iwasaki
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
| | - Eri Ikeguchi-Ogura
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
| | - Shunsuke Yamane
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
| | - Tomoko Kato
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
| | - Yoshinori Kanemaru
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
| | - Akiko Sankoda
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
| | - Tomonobu Hatoko
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
| | - Sakura Kiyobayashi
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
| | - Jun Ogawa
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Akira Hirasawa
- Department of Genomic Drug Discovery Science, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Nobuya Inagaki
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
- Corresponding author
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5
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Nagasawa T, Horitani M, Kawaguchi SI, Higashiyama S, Hama Y, Mitsutake S. The molecular mechanism of phytosphingosine binding to FFAR4/GPR120 differs from that of other fatty acids. FEBS Open Bio 2021; 11:3081-3089. [PMID: 34535977 PMCID: PMC8564095 DOI: 10.1002/2211-5463.13301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 09/14/2021] [Accepted: 09/16/2021] [Indexed: 12/21/2022] Open
Abstract
Free fatty acid receptor 4 (FFAR4)/GPR120 comprises a receptor for medium‐ and long‐chain fatty acids. We previously identified phytosphingosine (PHS) as a novel ligand of FFAR4. Although many natural FFAR4 ligands have carboxyl groups, PHS does not, thus suggesting that binding to FFAR4 is driven by a completely different mechanism than other natural ligands such as α‐linolenic acid (ALA). To test this hypothesis, we performed docking simulation analysis using a FFAR4 homology model based on a protein model derived from the crystal structure of activated turkey beta‐1 adrenoceptor. The docking simulation revealed that the probable hydrogen bonds to FFAR4 differ between various ligands. In particular, binding was predicted between R264 of the FFAR4 and the oxygen of the carboxylate group in ALA, as well as between E249 of the FFAR4 and the oxygen of the hydroxy group at the C4‐position in PHS. Alanine substitution at E249 (E249A) dramatically reduced PHS‐induced FFAR4 activation but demonstrated a weaker effect on ALA‐induced FFAR4 activation. Kinetic analysis and Km values clearly demonstrated that the E249A substitution resulted in reduced affinity for PHS but not for ALA. Additionally, we observed that sphingosine, lacking a hydroxyl group at C4‐position, could not activate FFAR4. Our data show that E249 of the FFAR4 receptor is crucial for binding to the hydroxy group at the C4‐position in PHS, and this is a completely different molecular mechanism of binding from ALA. Because GPR120 agonists have attracted attention as treatments for type 2 diabetes, our findings may provide new insights into their development.
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Affiliation(s)
- Tomotaka Nagasawa
- The United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima, Japan
| | - Masaki Horitani
- The United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima, Japan.,Department of Applied Biochemistry and Food Science, Faculty of Agriculture, Saga University, Saga, Japan
| | - Shin-Ichi Kawaguchi
- The United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima, Japan.,Center for Education and Research in Agricultural Innovation, Faculty of Agriculture, Saga University, Saga, Japan
| | - Shigeki Higashiyama
- Division of Cell Growth and Tumor Regulation, Proteo-Science Center, Ehime University, Matsuyama, Japan.,Department of Molecular and Cellular Biology, Osaka International Cancer Institute, Osaka, Japan
| | - Yoichiro Hama
- The United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima, Japan.,Department of Applied Biochemistry and Food Science, Faculty of Agriculture, Saga University, Saga, Japan
| | - Susumu Mitsutake
- The United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima, Japan.,Department of Applied Biochemistry and Food Science, Faculty of Agriculture, Saga University, Saga, Japan
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6
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Aderibigbe AO, Pandey P, Doerksen RJ. Negative allosteric modulators of cannabinoid receptor 1: Ternary complexes including CB1, orthosteric CP55940 and allosteric ORG27569. J Biomol Struct Dyn 2021; 40:5729-5747. [PMID: 33480332 DOI: 10.1080/07391102.2021.1873187] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
In October 2019, the first X-ray crystal structure of a ternary cannabinoid receptor 1 (CB1) complex (PDB ID: 6KQI) was published, including the well-known orthosteric agonist, CP55940, and the well-studied negative allosteric modulator, ORG27569. Prior to the release of 6KQI, we applied binding pocket analysis and molecular docking to carefully prepared computational models of the ternary CB1 complex, in order to predict the binding site for ORG27569 with the CP55940-bound CB1 receptor. We carefully studied the binding pose of agonist ligands in the CB1 orthosteric pocket, including CP55940. Our computational studies identified the most favorable binding site for ORG27569, in the CP55940-CB1 complex, to be at the intracellular end of the receptor. However, in the 6KQI structure, ORG27569 was found at an extrahelical, intramembrane site on the complex, a site that partially overlaps with the site predicted in our calculations to be second-best. We performed molecular dynamics simulations of the CP55940-bound CB1 complex with ORG27569 at different binding sites. Our analysis of the simulations indicated that ORG27569 bound favorably and stably in each simulation, but, as in the earlier calculations, bound best at the intracellular site, which is different than that found in the crystal structure. These results suggest that the intracellular site might serve as an alternative binding site in CB1. Our studies show that the computational techniques we used are valuable in identifying ligand-binding pockets in proteins, and could be useful for the study of the interaction mode of other allosteric modulators.
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Affiliation(s)
- AyoOluwa O Aderibigbe
- Department of BioMolecular Sciences, Division of Medicinal Chemistry, School of Pharmacy, University of Mississippi, University, MS, USA
| | - Pankaj Pandey
- Department of BioMolecular Sciences, Division of Medicinal Chemistry, School of Pharmacy, University of Mississippi, University, MS, USA.,National Center for Natural Products Research, University of Mississippi, University, Mississippi, USA
| | - Robert J Doerksen
- Department of BioMolecular Sciences, Division of Medicinal Chemistry, School of Pharmacy, University of Mississippi, University, MS, USA.,Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, University, MS, USA
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7
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Alves VL, Gonçalves JL, Aguiar J, Teixeira HM, Câmara JS. The synthetic cannabinoids phenomenon: from structure to toxicological properties. A review. Crit Rev Toxicol 2020; 50:359-382. [PMID: 32530350 DOI: 10.1080/10408444.2020.1762539] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The word "cannabinoid" refers to every chemical substance, regardless of structure or origin, that joins the cannabinoid receptors of the body and brain and that have similar effects to those produced by the Cannabis plant and based on their source of production, cannabinoids can be classified into endocannabinoids, phytocannabinoids and synthetic cannabinoids. Synthetic cannabinoids represent the largest class of drugs detected through the EU Early Warning System with a total of 190 substances notified from 2008 to 2018 and about 280 have been reported worldwide to the United Nations Office on Drugs and Crime. Sprayed on natural herb mixtures with the aim to mimic the euphoria effect of cannabis and sold as "herbal smoking blends" or "herbal incense" under brand names like "Spice" or "K2", synthetic cannabinoids are available from websites for the combination with herbal materials or more recently, for the use in e-cigarettes. Currently labeled as "not for human consumption" to circumvent legislation, their legal status varies by country with many government institutions currently pushing for their control. However, due to the emergence of new substances, it requires a constant update of the list of controlled drugs. Little is known about how these substances work and their toxic effects in humans and the same product could vary not only in the amount and in the type of substance added. In the last years, synthetic cannabinoids have been associated with deaths and acute intoxications in Europe and, despite a range of new measures introduced in this area, continue to represent a challenge to current drug policy models. These synthetic substances are much more potent than natural cannabis, as well as displayed greater efficacy, acting as full agonists at the cannabinoid receptors. It is possible that, along with being highly potent, some may also have long half-lives, potentially leading to a prolonged psychoactive effect. The present work provides a review on existing literature about the development of synthetic cannabinoids as substances of abuse, current patterns of abuse and their legal status, chemical classification, and some pharmacological and toxicological properties.
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Affiliation(s)
- Vera L Alves
- CQM - Centro de Química da Madeira, Universidade da Madeira, Funchal, Portugal
| | - João L Gonçalves
- CQM - Centro de Química da Madeira, Universidade da Madeira, Funchal, Portugal
| | - Joselin Aguiar
- CQM - Centro de Química da Madeira, Universidade da Madeira, Funchal, Portugal
| | - Helena M Teixeira
- Faculdade de Medicina da Universidade de Coimbra, Azinhaga de Santa Comba, Coimbra, Portugal.,Instituto Nacional de Medicina Legal e Ciências Forenses, Coimbra, Portugal
| | - José S Câmara
- CQM - Centro de Química da Madeira, Universidade da Madeira, Funchal, Portugal.,Faculdade de Ciências Exactas e da Engenharia, Universidade da Madeira, Funchal, Portugal
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8
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Tebo C, Mazer-Amirshahi M, DeGeorge L, Gelfand B, Leak C, Tolliver S, Sauter D. Suspected synthetic cannabinoid receptor agonist intoxication: Does analysis of samples reflect the presence of suspected agents? Am J Emerg Med 2019; 37:1846-1849. [DOI: 10.1016/j.ajem.2018.12.044] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 12/20/2018] [Accepted: 12/23/2018] [Indexed: 12/31/2022] Open
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9
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Navarro G, Varani K, Reyes-Resina I, Sánchez de Medina V, Rivas-Santisteban R, Sánchez-Carnerero Callado C, Vincenzi F, Casano S, Ferreiro-Vera C, Canela EI, Borea PA, Nadal X, Franco R. Cannabigerol Action at Cannabinoid CB 1 and CB 2 Receptors and at CB 1-CB 2 Heteroreceptor Complexes. Front Pharmacol 2018; 9:632. [PMID: 29977202 PMCID: PMC6021502 DOI: 10.3389/fphar.2018.00632] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 05/25/2018] [Indexed: 12/21/2022] Open
Abstract
Cannabigerol (CBG) is one of the major phytocannabinoids present in Cannabis sativa L. that is attracting pharmacological interest because it is non-psychotropic and is abundant in some industrial hemp varieties. The aim of this work was to investigate in parallel the binding properties of CBG to cannabinoid CB1 (CB1R) and CB2 (CB2R) receptors and the effects of the compound on agonist activation of those receptors and of CB1–CB2 heteroreceptor complexes. Using [3H]-CP-55940, CBG competed with low micromolar Ki values the binding to CB1R and CB2R. Homogeneous binding in living cells, which is only technically possible for the CB2R, provided a 152 nM Ki value. Also interesting, CBG competed the binding of [3H]-WIN-55,212-2 to CB2R but not to CB1R (Ki: 2.7 versus >30 μM). The phytocannabinoid modulated signaling mediated by receptors and receptor heteromers even at low concentrations of 0.1–1 μM. cAMP, pERK, β-arrestin recruitment and label-free assays in HEK-293T cells expressing the receptors and treated with endocannabinoids or selective agonists proved that CBG is a partial agonist of CB2R. The action on cells expressing heteromers was similar to that obtained in cells expressing the CB2R. The effect of CBG on CB1R was measurable but the underlying molecular mechanisms remain uncertain. The results indicate that CBG is indeed effective as regulator of endocannabinoid signaling.
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Affiliation(s)
- Gemma Navarro
- Department of Biochemistry and Physiology, Faculty of Pharmacy, University of Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red, Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
| | - Katia Varani
- Department of Medical Sciences, Institute of Pharmacology, University of Ferrara, Ferrara, Italy
| | - Irene Reyes-Resina
- Centro de Investigación Biomédica en Red, Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain.,Molecular Neurobiology Laboratory, Department of Biochemistry and Molecular Biomedicine, University of Barcelona, Barcelona, Spain
| | | | - Rafael Rivas-Santisteban
- Centro de Investigación Biomédica en Red, Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain.,Molecular Neurobiology Laboratory, Department of Biochemistry and Molecular Biomedicine, University of Barcelona, Barcelona, Spain
| | | | - Fabrizio Vincenzi
- Department of Medical Sciences, Institute of Pharmacology, University of Ferrara, Ferrara, Italy
| | - Salvatore Casano
- Department of Breeding and Cultivation, Phytoplant Research S.L., Córdoba, Spain
| | | | - Enric I Canela
- Centro de Investigación Biomédica en Red, Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain.,Molecular Neurobiology Laboratory, Department of Biochemistry and Molecular Biomedicine, University of Barcelona, Barcelona, Spain
| | - Pier Andrea Borea
- Department of Medical Sciences, Institute of Pharmacology, University of Ferrara, Ferrara, Italy
| | - Xavier Nadal
- Department of R&D - Extraction, Phytoplant Research S.L., Córdoba, Spain
| | - Rafael Franco
- Centro de Investigación Biomédica en Red, Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain.,Molecular Neurobiology Laboratory, Department of Biochemistry and Molecular Biomedicine, University of Barcelona, Barcelona, Spain
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10
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Ford BM, Franks LN, Tai S, Fantegrossi WE, Stahl EL, Berquist MD, Cabanlong CV, Wilson CD, Penthala NR, Crooks PA, Prather PL. Characterization of structurally novel G protein biased CB 1 agonists: Implications for drug development. Pharmacol Res 2017; 125:161-177. [PMID: 28838808 DOI: 10.1016/j.phrs.2017.08.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 08/11/2017] [Accepted: 08/12/2017] [Indexed: 01/08/2023]
Abstract
The human cannabinoid subtype 1 receptor (hCB1R) is highly expressed in the CNS and serves as a therapeutic target for endogenous ligands as well as plant-derived and synthetic cannabinoids. Unfortunately, acute use of hCB1R agonists produces unwanted psychotropic effects and chronic administration results in development of tolerance and dependence, limiting the potential clinical use of these ligands. Studies in β-arrestin knockout mice suggest that interaction of certain GPCRs, including μ-, δ-, κ-opioid and hCB1Rs, with β-arrestins might be responsible for several adverse effects produced by agonists acting at these receptors. Indeed, agonists that bias opioid receptor activation toward G-protein, relative to β-arrestin signaling, produce less severe adverse effects. These observations indicate that therapeutic utility of agonists acting at hCB1Rs might be improved by development of G-protein biased hCB1R agonists. Our laboratory recently reported a novel class of indole quinulidinone (IQD) compounds that bind cannabinoid receptors with relatively high affinity and act with varying efficacy. The purpose of this study was to determine whether agonists in this novel cannabinoid class exhibit ligand bias at hCB1 receptors. Our studies found that a novel IQD-derived hCB1 receptor agonist PNR-4-20 elicits robust G protein-dependent signaling, with transduction ratios similar to the non-biased hCB1R agonist CP-55,940. In marked contrast to CP-55,940, PNR-4-20 produces little to no β-arrestin 2 recruitment. Quantitative calculation of bias factors indicates that PNR-4-20 exhibits from 5.4-fold to 29.5-fold bias for G protein, relative to β-arrestin 2 signaling (when compared to G protein activation or inhibition of forskolin-stimulated cAMP accumulation, respectively). Importantly, as expected due to reduced β-arrestin 2 recruitment, chronic exposure of cells to PNR-4-20 results in significantly less desensitization and down-regulation of hCB1Rs compared to similar treatment with CP-55,940. PNR-4-20 (i.p.) is active in the cannabinoid tetrad in mice and chronic treatment results in development of less persistent tolerance and no significant withdrawal signs when compared to animals repeatedly exposed to the non-biased full agoinst JWH-018 or Δ9-THC. Finally, studies of a structurally similar analog PNR- 4-02 show that it is also a G protein biased hCB1R agonist. It is predicted that cannabinoid agonists that bias hCB1R activation toward G protein, relative to β-arrestin 2 signaling, will produce fewer and less severe adverse effects both acutely and chronically.
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Affiliation(s)
- Benjamin M Ford
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
| | - Lirit N Franks
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
| | - Sherrica Tai
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
| | - William E Fantegrossi
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
| | - Edward L Stahl
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, USA.
| | - Michael D Berquist
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
| | - Christian V Cabanlong
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
| | - Catheryn D Wilson
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
| | - Narsimha R Penthala
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
| | - Peter A Crooks
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
| | - Paul L Prather
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA.
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Badal S, Smith KN, Rajnarayanan R. Analysis of natural product regulation of cannabinoid receptors in the treatment of human disease. Pharmacol Ther 2017; 180:24-48. [PMID: 28583800 DOI: 10.1016/j.pharmthera.2017.06.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The organized, tightly regulated signaling relays engaged by the cannabinoid receptors (CBs) and their ligands, G proteins and other effectors, together constitute the endocannabinoid system (ECS). This system governs many biological functions including cell proliferation, regulation of ion transport and neuronal messaging. This review will firstly examine the physiology of the ECS, briefly discussing some anomalies in the relay of the ECS signaling as these are consequently linked to maladies of global concern including neurological disorders, cardiovascular disease and cancer. While endogenous ligands are crucial for dispatching messages through the ECS, there are also commonalities in binding affinities with copious exogenous ligands, both natural and synthetic. Therefore, this review provides a comparative analysis of both types of exogenous ligands with emphasis on natural products given their putative safer efficacy and the role of Δ9-tetrahydrocannabinol (Δ9-THC) in uncovering the ECS. Efficacy is congruent to both types of compounds but noteworthy is the effect of a combination therapy to achieve efficacy without unideal side-effects. An example is Sativex that displayed promise in treating Huntington's disease (HD) in preclinical models allowing for its transition to current clinical investigation. Despite the in vitro and preclinical efficacy of Δ9-THC to treat neurodegenerative ailments, its psychotropic effects limit its clinical applicability to treating feeding disorders. We therefore propose further investigation of other compounds and their combinations such as the triterpene, α,β-amyrin that exhibited greater binding affinity to CB1 than CB2 and was more potent than Δ9-THC and the N-alkylamides that exhibited CB2 selective affinity; the latter can be explored towards peripherally exclusive ECS modulation. The synthetic CB1 antagonist, Rimonabant was pulled from commercial markets for the treatment of diabetes, however its analogue SR144528 maybe an ideal lead molecule towards this end and HU-210 and Org27569 are also promising synthetic small molecules.
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Affiliation(s)
- S Badal
- Department of Basic Medical Sciences, Faculty of Medical Sciences, University of the West Indies, Mona, Jamaica.
| | - K N Smith
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - R Rajnarayanan
- Jacobs School of Medicine and Biomedical Sciences, Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, NY 14228, USA
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Ford BM, Tai S, Fantegrossi WE, Prather PL. Synthetic Pot: Not Your Grandfather's Marijuana. Trends Pharmacol Sci 2017; 38:257-276. [PMID: 28162792 PMCID: PMC5329767 DOI: 10.1016/j.tips.2016.12.003] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 11/08/2016] [Accepted: 12/13/2016] [Indexed: 01/05/2023]
Abstract
In the early 2000s in Europe and shortly thereafter in the USA, it was reported that 'legal' forms of marijuana were being sold under the name K2 and/or Spice. Active ingredients in K2/Spice products were determined to be synthetic cannabinoids (SCBs), producing psychotropic actions via CB1 cannabinoid receptors, similar to those of Δ9-tetrahydrocannabinol (Δ9-THC), the primary active constituent in marijuana. Often abused by adolescents and military personnel to elude detection in drug tests due to their lack of structural similarity to Δ9-THC, SCBs are falsely marketed as safe marijuana substitutes. Instead, SCBs are a highly structural diverse group of compounds, easily synthesized, which produce very dangerous adverse effects occurring by, as of yet, unknown mechanisms. Therefore, available evidence indicates that K2/Spice products are clearly not safe marijuana alternatives.
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Affiliation(s)
- Benjamin M Ford
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Sherrica Tai
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, USA; Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - William E Fantegrossi
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Paul L Prather
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
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Ford BM, Franks LN, Radominska-Pandya A, Prather PL. Tamoxifen Isomers and Metabolites Exhibit Distinct Affinity and Activity at Cannabinoid Receptors: Potential Scaffold for Drug Development. PLoS One 2016; 11:e0167240. [PMID: 27936172 PMCID: PMC5147891 DOI: 10.1371/journal.pone.0167240] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 11/10/2016] [Indexed: 01/29/2023] Open
Abstract
Tamoxifen (Tam) is a selective estrogen receptor (ER) modulator (SERM) that is an essential drug to treat ER-positive breast cancer. Aside from known actions at ERs, recent studies have suggested that some SERMs like Tam also exhibit novel activity at cannabinoid subtype 1 and 2 receptors (CB1R and CB2Rs). Interestingly, cis- (E-Tam) and trans- (Z-Tam) isomers of Tam exhibit over a 100-fold difference in affinity for ERs. Therefore, the current study assessed individual isomers of Tam and subsequent cytochrome P450 metabolic products, 4-hydroxytamoxifen (4OHT) and 4-hydroxy-N-desmethyl tamoxifen (End) for affinity and activity at CBRs. Results showed that Z-4OHT, but not Z-Tam or Z-End, exhibits higher affinity for both CB1 and CB2Rs relative to the E-isomer. Furthermore, Z- and E-isomers of Tam and 4OHT show slightly higher affinity for CB2Rs, while both End isomers are relatively CB1R-selective. When functional activity was assessed by G-protein activation and regulation of the downstream effector adenylyl cyclase, all isomers examined act as full CB1 and CB2R inverse agonists. Interestingly, Z-Tam appears to be more efficacious than the full inverse agonist AM630 at CB2Rs, while both Z-Tam and Z-End exhibit characteristics of insurmountable antagonism at CB1 and CB2Rs, respectively. Collectively, these results suggest that the SERMs Tam, 4OHT and End elicit ER-independent actions via CBRs in an isomer-specific manner. As such, this novel structural scaffold might be used to develop therapeutically useful drugs for treatment of a variety of diseases mediated via CBRs.
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MESH Headings
- Adenylyl Cyclases/metabolism
- Animals
- Binding, Competitive
- Breast Neoplasms/drug therapy
- Breast Neoplasms/metabolism
- CHO Cells
- Cannabinoid Receptor Agonists/metabolism
- Cannabinoid Receptor Agonists/pharmacology
- Cannabinoid Receptor Antagonists/metabolism
- Cannabinoid Receptor Antagonists/pharmacology
- Colforsin/metabolism
- Colforsin/pharmacology
- Cricetinae
- Cricetulus
- Cyclic AMP/metabolism
- Cyclohexanols/metabolism
- Cyclohexanols/pharmacology
- Female
- GTP-Binding Proteins/metabolism
- Guanosine 5'-O-(3-Thiotriphosphate)/metabolism
- Humans
- Indoles/metabolism
- Indoles/pharmacology
- Isomerism
- Receptor, Cannabinoid, CB1/agonists
- Receptor, Cannabinoid, CB1/antagonists & inhibitors
- Receptor, Cannabinoid, CB1/metabolism
- Receptor, Cannabinoid, CB2/agonists
- Receptor, Cannabinoid, CB2/antagonists & inhibitors
- Receptor, Cannabinoid, CB2/metabolism
- Selective Estrogen Receptor Modulators/chemistry
- Selective Estrogen Receptor Modulators/metabolism
- Selective Estrogen Receptor Modulators/pharmacology
- Tamoxifen/analogs & derivatives
- Tamoxifen/chemistry
- Tamoxifen/metabolism
- Tamoxifen/pharmacology
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Affiliation(s)
- Benjamin M. Ford
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Lirit N. Franks
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Anna Radominska-Pandya
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Paul L. Prather
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
- * E-mail:
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14
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Iyer MR, Cinar R, Liu J, Godlewski G, Szanda G, Puhl H, Ikeda SR, Deschamps J, Lee YS, Steinbach PJ, Kunos G. Structural Basis of Species-Dependent Differential Affinity of 6-Alkoxy-5-Aryl-3-Pyridinecarboxamide Cannabinoid-1 Receptor Antagonists. Mol Pharmacol 2015; 88:238-44. [PMID: 26013543 DOI: 10.1124/mol.115.098541] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 05/26/2015] [Indexed: 12/15/2022] Open
Abstract
6-Alkoxy-5-aryl-3-pyridincarboxamides, including the brain-penetrant compound 14G: [5-(4-chlorophenyl)-6-(cyclopropylmethoxy)-N-[(1R,2R)-2-hydroxy-cyclohexyl]-3-pyridinecarboxamide] and its peripherally restricted analog 14H: [5-(4-chlorophenyl)-N-[(1R,2R)-2-hydroxycyclohexyl]-6-(2-methoxyethoxy)-3-pyridinecarboxamide], have been recently introduced as selective, high-affinity antagonists of the human cannabinoid-1 receptor (hCB1R). Binding analyses revealed two orders of magnitude lower affinity of these compounds for mouse and rat versus human CB1R, whereas the affinity of rimonabant is comparable for all three CB1Rs. Modeling of ligand binding to CB1R and binding assays with native and mutant (Ile105Met) hCB1Rs indicate that the Ile105 to Met mutation in rodent CB1Rs accounts for the species-dependent affinity of 14G: and 14H: . Our work identifies Ile105 as a new pharmacophore component for developing better hCB1R antagonists and invalidates rodent models for assessing the antiobesity efficacy of 14G: and 14H: .
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Affiliation(s)
- Malliga R Iyer
- Laboratory of Physiologic Studies (M.R.I., R.C., J.L., G.G., G.S., G.K.) and Laboratory of Molecular Physiology (H.P., S.R.I.), National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland; Naval Research Laboratory, Washington, D.C. (J.D.); and Center for Molecular Modeling, Center for Information Technology, National Institutes of Health, Bethesda, Maryland (Y.-S.L., P.J.S.)
| | - Resat Cinar
- Laboratory of Physiologic Studies (M.R.I., R.C., J.L., G.G., G.S., G.K.) and Laboratory of Molecular Physiology (H.P., S.R.I.), National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland; Naval Research Laboratory, Washington, D.C. (J.D.); and Center for Molecular Modeling, Center for Information Technology, National Institutes of Health, Bethesda, Maryland (Y.-S.L., P.J.S.)
| | - Jie Liu
- Laboratory of Physiologic Studies (M.R.I., R.C., J.L., G.G., G.S., G.K.) and Laboratory of Molecular Physiology (H.P., S.R.I.), National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland; Naval Research Laboratory, Washington, D.C. (J.D.); and Center for Molecular Modeling, Center for Information Technology, National Institutes of Health, Bethesda, Maryland (Y.-S.L., P.J.S.)
| | - Grzegorz Godlewski
- Laboratory of Physiologic Studies (M.R.I., R.C., J.L., G.G., G.S., G.K.) and Laboratory of Molecular Physiology (H.P., S.R.I.), National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland; Naval Research Laboratory, Washington, D.C. (J.D.); and Center for Molecular Modeling, Center for Information Technology, National Institutes of Health, Bethesda, Maryland (Y.-S.L., P.J.S.)
| | - Gergö Szanda
- Laboratory of Physiologic Studies (M.R.I., R.C., J.L., G.G., G.S., G.K.) and Laboratory of Molecular Physiology (H.P., S.R.I.), National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland; Naval Research Laboratory, Washington, D.C. (J.D.); and Center for Molecular Modeling, Center for Information Technology, National Institutes of Health, Bethesda, Maryland (Y.-S.L., P.J.S.)
| | - Henry Puhl
- Laboratory of Physiologic Studies (M.R.I., R.C., J.L., G.G., G.S., G.K.) and Laboratory of Molecular Physiology (H.P., S.R.I.), National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland; Naval Research Laboratory, Washington, D.C. (J.D.); and Center for Molecular Modeling, Center for Information Technology, National Institutes of Health, Bethesda, Maryland (Y.-S.L., P.J.S.)
| | - Stephen R Ikeda
- Laboratory of Physiologic Studies (M.R.I., R.C., J.L., G.G., G.S., G.K.) and Laboratory of Molecular Physiology (H.P., S.R.I.), National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland; Naval Research Laboratory, Washington, D.C. (J.D.); and Center for Molecular Modeling, Center for Information Technology, National Institutes of Health, Bethesda, Maryland (Y.-S.L., P.J.S.)
| | - Jeffrey Deschamps
- Laboratory of Physiologic Studies (M.R.I., R.C., J.L., G.G., G.S., G.K.) and Laboratory of Molecular Physiology (H.P., S.R.I.), National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland; Naval Research Laboratory, Washington, D.C. (J.D.); and Center for Molecular Modeling, Center for Information Technology, National Institutes of Health, Bethesda, Maryland (Y.-S.L., P.J.S.)
| | - Yong-Sok Lee
- Laboratory of Physiologic Studies (M.R.I., R.C., J.L., G.G., G.S., G.K.) and Laboratory of Molecular Physiology (H.P., S.R.I.), National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland; Naval Research Laboratory, Washington, D.C. (J.D.); and Center for Molecular Modeling, Center for Information Technology, National Institutes of Health, Bethesda, Maryland (Y.-S.L., P.J.S.)
| | - Peter J Steinbach
- Laboratory of Physiologic Studies (M.R.I., R.C., J.L., G.G., G.S., G.K.) and Laboratory of Molecular Physiology (H.P., S.R.I.), National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland; Naval Research Laboratory, Washington, D.C. (J.D.); and Center for Molecular Modeling, Center for Information Technology, National Institutes of Health, Bethesda, Maryland (Y.-S.L., P.J.S.)
| | - George Kunos
- Laboratory of Physiologic Studies (M.R.I., R.C., J.L., G.G., G.S., G.K.) and Laboratory of Molecular Physiology (H.P., S.R.I.), National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland; Naval Research Laboratory, Washington, D.C. (J.D.); and Center for Molecular Modeling, Center for Information Technology, National Institutes of Health, Bethesda, Maryland (Y.-S.L., P.J.S.)
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Espinosa-Bustos C, Lagos CF, Romero-Parra J, Zárate AM, Mella-Raipán J, Pessoa-Mahana H, Recabarren-Gajardo G, Iturriaga-Vásquez P, Tapia RA, Pessoa-Mahana CD. Design, Synthesis, Biological Evaluation and Binding Mode Modeling of Benzimidazole Derivatives Targeting the Cannabinoid Receptor Type 1. Arch Pharm (Weinheim) 2015; 348:81-8. [DOI: 10.1002/ardp.201400201] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 10/26/2014] [Accepted: 10/30/2014] [Indexed: 12/19/2022]
Affiliation(s)
- Christian Espinosa-Bustos
- Department of Pharmacy, Faculty of Chemistry; Pontificia Universidad Catolica de Chile; Santiago Chile
| | - Carlos F. Lagos
- Department of Endocrinology, School of Medicine; Pontificia Universidad Catolica de Chile; Santiago Chile
| | - Javier Romero-Parra
- Department of Pharmacy, Faculty of Chemistry; Pontificia Universidad Catolica de Chile; Santiago Chile
| | - Ana M. Zárate
- Department of Pharmacy, Faculty of Chemistry; Pontificia Universidad Catolica de Chile; Santiago Chile
| | - Jaime Mella-Raipán
- Institute of Chemistry and Biochemistry, Faculty of Science; Universidad de Valparaiso, Playa Ancha; Valparaíso Chile
| | - Hernán Pessoa-Mahana
- Department of Organic and Physical Chemistry, Faculty of Chemical and Pharmaceutical Sciences; Universidad de Chile; Santiago Chile
| | | | | | - Ricardo A. Tapia
- Department of Organic Chemistry, Faculty of Chemistry; Pontificia Universidad Catolica de Chile; Santiago Chile
| | - C. David Pessoa-Mahana
- Department of Pharmacy, Faculty of Chemistry; Pontificia Universidad Catolica de Chile; Santiago Chile
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16
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17
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Prospective therapeutic agents for obesity: Molecular modification approaches of centrally and peripherally acting selective cannabinoid 1 receptor antagonists. Eur J Med Chem 2014; 79:298-339. [DOI: 10.1016/j.ejmech.2014.04.011] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 04/03/2014] [Accepted: 04/04/2014] [Indexed: 01/29/2023]
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19
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Liu H, Patel RY, Doerksen RJ. Structure of the cannabinoid receptor 1: homology modeling of its inactive state and enrichment study based on CB1 antagonist docking. MEDCHEMCOMM 2014. [DOI: 10.1039/c4md00121d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Multiple cannabinoid 1 receptor models were prepared and the best one was selected based on the models' performance in selecting known ligands from a pool of competitors.
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Affiliation(s)
- Haining Liu
- Department of Medicinal Chemistry
- School of Pharmacy
- University of Mississippi
- University, USA
| | - Ronak Y. Patel
- Department of Medicinal Chemistry
- School of Pharmacy
- University of Mississippi
- University, USA
| | - Robert J. Doerksen
- Department of Medicinal Chemistry
- School of Pharmacy
- University of Mississippi
- University, USA
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20
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Takeuchi M, Hirasawa A, Hara T, Kimura I, Hirano T, Suzuki T, Miyata N, Awaji T, Ishiguro M, Tsujimoto G. FFA1-selective agonistic activity based on docking simulation using FFA1 and GPR120 homology models. Br J Pharmacol 2013; 168:1570-83. [PMID: 22639973 DOI: 10.1111/j.1476-5381.2012.02052.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE The free fatty acid FFA1 receptor and GPR120 are GPCRs whose endogenous ligands are medium- and long-chain FFAs, and they are important in regulating insulin and GLP-1 secretion respectively. Given that the ligands of FFA1 receptor and GPR120 have similar properties, selective pharmacological tools are required to study their functions further. EXPERIMENTAL APPROACH We used a docking simulation approach using homology models for each receptor. Biological activity was assessed by phosphorylation of ERK and elevation of intracellular calcium ([Ca(2+) ]i ) in cells transfected with FFA1 receptor or GPR120. Insulin secretion from murine pancreatic beta cells (MIN6) was also measured. KEY RESULTS Calculated hydrogen bonding energies between a series of synthetic carboxylic acid compounds and the homology models of the FFA1 receptor and GPR120, using docking simulations, correlated well with the effects of the compounds on ERK phosphorylation in transfected cells (R(2) = 0.65 for FFA1 receptor and 0.76 for GPR120). NCG75, the compound with the highest predicted selectivity for FFA1 receptors from this structure-activity relationship analysis, activated ERK and increased [Ca(2+) ]i as potently as the known FFA1 receptor-selective agonist, Compound 1. Site-directed mutagenesis analysis based on the docking simulation showed that different amino acid residues were important for the recognition and activation by FFA1 receptor agonists. Moreover, NCG75 strongly induced ERK and [Ca(2+) ]i responses, and promoted insulin secretion from MIN6 cells, which express endogenous FFA1 receptors. CONCLUSION AND IMPLICATIONS A docking simulation approach using FFA1 receptor and GPR120 homology models could be useful in predicting FFA1 receptor-selective agonists.
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Affiliation(s)
- Masato Takeuchi
- Department of Genomic Drug Discovery Science, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
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Sethi R, Thapa N, Saxena A, Chahil R. "K2/Spice": have you updated your differentials? A case report. Prim Care Companion CNS Disord 2013; 15:12l01402. [PMID: 23930230 DOI: 10.4088/pcc.12l01402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Affiliation(s)
- Roopa Sethi
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut (Dr Sethi); Department of Psychiatry, Carilion Clinic-Virginia Tech Carilion School of Medicine, Roanoke (Dr Thapa); Department of Integrative Physiology, University of North Texas Health Science Center, Fort Worth (Dr Saxena); and Veterans Affairs Medical Center, Salem, Virginia (Dr Chahil)
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22
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Rempel V, Volz N, Hinz S, Karcz T, Meliciani I, Nieger M, Wenzel W, Bräse S, Müller CE. 7-Alkyl-3-benzylcoumarins: a versatile scaffold for the development of potent and selective cannabinoid receptor agonists and antagonists. J Med Chem 2012; 55:7967-77. [PMID: 22916707 DOI: 10.1021/jm3008213] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A series of 7-alkyl-3-benzylcoumarins was designed, synthesized, and tested at cannabinoid CB(1) and CB(2) receptors in radioligand binding and cAMP accumulation studies. 7-Alkyl-3-benzylcoumarins were found to constitute a versatile scaffold for obtaining potent CB receptor ligands with high potency at either CB(1) or CB(2) and a broad spectrum of efficacies. Fine-tuning of compound properties was achieved by small modifications of the substitution pattern. The most potent compounds of the present series include 5-methoxy-3-(2-methylbenzyl)-7-pentyl-2H-chromen-2-one (19a, PSB-SB-1201), a selective CB(1)antagonist (K(i) CB(1) 0.022 μM), 5-methoxy-3-(2-methoxybenzyl)-7-pentyl-2H-chromen-2-one (21a, PSB-SB-1202), a dual CB(1)/CB(2)agonist (CB(1)K(i) 0.032 μM, EC(50) 0.056 μM; CB(2)K(i) 0.049 μM, EC(50) 0.014 μM), 5-hydroxy-3-(2-hydroxybenzyl)-7-(2-methyloct-2-yl)-2H-chromen-2-one (25b, PSB-SB-1203), a dual CB(1)/CB(2) ligand that blocks CB(1) but activates CB(2) receptors (CB(1)K(i) 0.244 μM; CB(2)K(i) 0.210 μM, EC(50) 0.054 μM), and 7-(1-butylcyclopentyl)-5-hydroxy-3-(2-hydroxybenzyl)-2H-chromen-2-one (27b, PSB-SB-1204), a selective CB(2) receptor agonist (CB(1)K(i) 1.59 μM; CB(2)K(i) 0.068 μM, EC(50) 0.048 μM).
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Affiliation(s)
- Viktor Rempel
- Pharmaceutical Chemistry I, Pharmaceutical Institute, PharmaCenter Bonn, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
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Jin MJ, Lee J, In MK, Yoo HH. Characterization of in vitro metabolites of CP 47,497, a synthetic cannabinoid, in human liver microsomes by LC-MS/MS. J Forensic Sci 2012; 58:195-9. [PMID: 22931239 DOI: 10.1111/j.1556-4029.2012.02261.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 09/19/2011] [Accepted: 10/29/2011] [Indexed: 11/29/2022]
Abstract
CP 47,497, a potent cannabinoid receptor type 1 agonist, is the main active ingredient in the herbal mixture "Spice" sold in European countries. The illegal use of "Spice" for its psychoactive effects has become a social issue. In this study, the in vitro metabolism of CP 47,497 was investigated in human liver microsomes to characterize the metabolic fate of CP 47,497. CP 47,497 was incubated with human liver microsomes, and the reaction mixture was analyzed using liquid chromatography-tandem mass spectrometry. A total of eight metabolites were detected in human liver microsomes and structurally characterized based on mass spectral data. The main metabolic pathways involved hydroxylations or oxygenations. The identified metabolites were mono-oxygenated metabolites (M1 and M4), mono-hydroxylated metabolites (M3, M5, M6, M7, and M8), and a di-oxygenated metabolite (M2). The detection of these metabolites could confirm the presence of CP 47,497 in biological samples; therefore, collectively, they would be excellent indicators of "Spice" drug abuse.
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Affiliation(s)
- Ming J Jin
- Doping Control Center, Korea Institute of Science and Technology, Seoul, Korea
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24
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Psychoyos D, Vinod KY. Marijuana, Spice 'herbal high', and early neural development: implications for rescheduling and legalization. Drug Test Anal 2012; 5:27-45. [PMID: 22887867 DOI: 10.1002/dta.1390] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 07/02/2012] [Indexed: 01/16/2023]
Abstract
Marijuana is the most widely used illicit drug by pregnant women in the world. In utero exposure to Δ⁹-tetrahydrocannabinol (Δ⁹-THC), a major psychoactive component of marijuana, is associated with an increased risk for anencephaly and neurobehavioural deficiencies in the offspring, including attention deficit hyperactivity disorder (ADHD), learning disabilities, and memory impairment. Recent studies demonstrate that the developing central nervous system (CNS) is susceptible to the effects of Δ⁹-THC and other cannabimimetics, including the psychoactive ingredients of the branded product 'Spice' branded products. These exocannabinoids interfere with the function of an endocannabinoid (eCB) system, present in the developing CNS from E12.5 (week 5 of gestation in humans), and required for proliferation, migration, and differentiation of neurons. Until recently, it was not known whether the eCB system is also present in the developing CNS during the initial stages of its ontogeny, i.e. from E7.0 onwards (week 2 of gestation in humans), and if so, whether this system is also susceptible to the action of exocannabinoids. Here, we review current data, in which the presence of an eCB system during the initial stage of development of the CNS is demonstrated. Furthermore, we focus on recent advances on the effect of canabimimetics on early gestation. The relevance of these findings and potential adverse developmental consequences of in utero exposure to 'high potency' marijuana, Spice branded products and/or cannabinoid research chemicals during this period is discussed. Finally, we address the implication of these findings in terms of the potential dangers of synthetic cannabinoid use during pregnancy, and the ongoing debate over legalization of marijuana.
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Affiliation(s)
- Delphine Psychoyos
- Center for Environmental and Genetic Medicine, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030, USA.
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25
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Ligand-specific homology modeling of human cannabinoid (CB1) receptor. J Mol Graph Model 2012; 38:155-64. [PMID: 23079645 DOI: 10.1016/j.jmgm.2012.05.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 05/09/2012] [Accepted: 05/15/2012] [Indexed: 12/20/2022]
Abstract
Cannabinoid (CB1) receptor is a therapeutic drug target, and its structure and conformational changes after ligand binding are of great interest. To study the protein conformations in ligand bound state and assist in drug discovery, CB1 receptor homology models are needed for computer-based ligand screening. The known CB1 ligands are highly diverse structurally, so CB1 receptor may undergo considerable conformational changes to accept different ligands, which is challenging for molecular docking methods. To account for the flexibility of CB1 receptor, we constructed four CB1 receptor models based on four structurally distinct ligands, HU-210, ACEA, WIN55212-2 and SR141716A, using the newest X-ray crystal structures of human β₂ adrenergic receptor and adenosine A(2A) receptor as templates. The conformations of these four CB1-ligand complexes were optimized by molecular dynamics (MD) simulations. The models revealed interactions between CB1 receptor and known binders suggested by experiments and could successfully discriminate known ligands and non-binders in our docking assays. MD simulations were used to study the most flexible ligand, ACEA, in its free and bound states to investigate structural mobility achieved by the rearrangement of the fatty acid chain. Our models may capture important conformational changes of CB1 receptor to help improve accuracy in future CB1 drug screening.
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26
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In silico investigation of interactions between human cannabinoid receptor-1 and its antagonists. J Mol Model 2012; 18:3831-45. [PMID: 22402754 DOI: 10.1007/s00894-012-1381-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Accepted: 02/14/2012] [Indexed: 12/28/2022]
Abstract
Cannabinoid receptor-1 (CB(1)) is widely expressed in the central nervous system and plays a vital role in regulating food intake and energy expenditure. CB(1) antagonists such as Rimonabant have been used in clinic to inhibit food intake, and therefore reduce body weight in obese animals and humans. To investigate the binding modes of CB(1) antagonists to the receptor, both receptor- and ligand-based methods were implemented in this study. At first, a pharmacophore model was generated based on 31 diverse CB(1) antagonists collected from literature. A test set validation and a simulated virtual screening evaluation were then performed to verify the reliability and discriminating ability of the pharmacophore. Meanwhile, the homology model of CB(1) receptor was constructed based on the crystal structure of human β (2) adrenergic receptor (β (2)-AR). Several classical antagonists were then docked into the optimized homology model with induced fit docking method. A hydrogen bond between the antagonists and Lys192 on the third transmembrane helix of the receptor was formed in the docking study, which has proven to be critical for receptor-ligand interaction by biological experiments. The structure obtained from induced fit docking was then confirmed to be a reliable model for molecular docking from the result of the simulated virtual screening. The consistency between the pharmacophore and the homology structure further proved the previous observation. The built receptor structure and antagonists' pharmacophore should be useful for the understanding of inhibitory mechanism and development of novel CB(1) antagonists.
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27
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Durdagi S, Papadopoulos MG, Mavromoustakos T. An effort to discover the preferred conformation of the potent AMG3 cannabinoid analog when reaching the active sites of the cannabinoid receptors. Eur J Med Chem 2012; 47:44-51. [DOI: 10.1016/j.ejmech.2011.10.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Revised: 08/29/2011] [Accepted: 10/06/2011] [Indexed: 11/26/2022]
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28
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Fanelli F, De Benedetti PG. Update 1 of: computational modeling approaches to structure-function analysis of G protein-coupled receptors. Chem Rev 2011; 111:PR438-535. [PMID: 22165845 DOI: 10.1021/cr100437t] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Francesca Fanelli
- Dulbecco Telethon Institute, University of Modena and Reggio Emilia, via Campi 183, 41125 Modena, Italy.
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29
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Seely KA, Prather PL, James LP, Moran JH. Marijuana-based drugs: innovative therapeutics or designer drugs of abuse? Mol Interv 2011; 11:36-51. [PMID: 21441120 DOI: 10.1124/mi.11.1.6] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The principal psychoactive component of marijuana, Δ(9)-tetrahydrocannabinol (THC), activates CB1 cannabinoid receptors (CB1Rs). Unfortunately, pharmacological research into the design of effective THC analogs has been hampered by psychiatric side effects. THC-based drug design of a less academic nature, however, has led to the marketing of "synthetic marijuana," labeled as K2 or "Spice," among other terms, which elicits psychotropic actions via CB1R activation. Because of structural dissimilarity to THC, the active ingredients of K2/Spice preparations are widely unregulated. The K2/Spice "phenomenon" provides a context for considering whether marijuana-based drugs will truly provide innovative therapeutics or merely perpetuate drug abuse.
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Affiliation(s)
- Kathryn A Seely
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
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30
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Shim JY. Understanding functional residues of the cannabinoid CB1. Curr Top Med Chem 2011; 10:779-98. [PMID: 20370713 DOI: 10.2174/156802610791164210] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Accepted: 10/27/2009] [Indexed: 02/07/2023]
Abstract
The brain cannabinoid (CB(1)) receptor that mediates numerous physiological processes in response to marijuana and other psychoactive compounds is a G protein coupled receptor (GPCR) and shares common structural features with many rhodopsin class GPCRs. For the rational development of therapeutic agents targeting the CB(1) receptor, understanding of the ligand-specific CB(1) receptor interactions responsible for unique G protein signals is crucial. For a more than a decade, a combination of mutagenesis and computational modeling approaches has been successfully employed to study the ligand-specific CB(1) receptor interactions. In this review, after a brief discussion about recent advances in understanding of some structural and functional features of GPCRs commonly applicable to the CB(1) receptor, the CB(1) receptor functional residues reported from mutational studies are divided into three different types, ligand binding (B), receptor stabilization (S) and receptor activation (A) residues, to delineate the nature of the binding pockets of anandamide, CP55940, WIN55212-2 and SR141716A and to describe the molecular events of the ligand-specific CB(1) receptor activation from ligand binding to G protein signaling. Taken these CB(1) receptor functional residues, some of which are unique to the CB(1) receptor, together with the biophysical knowledge accumulated for the GPCR active state, it is possible to propose the early stages of the CB(1) receptor activation process that not only provide some insights into understanding molecular mechanisms of receptor activation but also are applicable for identifying new therapeutic agents by applying the validated structure-based approaches, such as virtual high throughput screening (HTS) and fragment-based approach (FBA).
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Affiliation(s)
- Joong-Youn Shim
- J.L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, 700 George Street, Durham, NC 27707, USA.
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31
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Tiburu EK, Tyukhtenko S, Zhou H, Janero DR, Struppe J, Makriyannis A. Human cannabinoid 1 GPCR C-terminal domain interacts with bilayer phospholipids to modulate the structure of its membrane environment. AAPS JOURNAL 2011; 13:92-8. [PMID: 21234731 DOI: 10.1208/s12248-010-9244-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Accepted: 11/21/2010] [Indexed: 02/08/2023]
Abstract
G protein-coupled receptors (GPCRs) play critical physiological and therapeutic roles. The human cannabinoid 1 GPCR (hCB1) is a prime pharmacotherapeutic target for addiction and cardiometabolic disease. Our prior biophysical studies on the structural biology of a synthetic peptide representing the functionally significant hCB1 transmembrane helix 7 (TMH7) and its cytoplasmic extension, helix 8 (H8), [hCB1(TMH7/H8)] demonstrated that the helices are oriented virtually perpendicular to each other in membrane-mimetic environments. We identified several hCB1(TMH7/H8) structure-function determinants, including multiple electrostatic amino-acid interactions and a proline kink involving the highly conserved NPXXY motif. In phospholipid bicelles, TMH7 structure, orientation, and topology relative to H8 are dynamically modulated by the surrounding membrane phospholipid bilayer. These data provide a contextual basis for the present solid-state NMR study to investigate whether intermolecular interactions between hCB1(TMH7/H8) and its phospholipid environment may affect membrane-bilayer structure. For this purpose, we measured (1)H-(13)C heteronuclear dipolar couplings for the choline, glycerol, and acyl-chain regions of dimyristoylphosphocholine in a magnetically aligned hCB1(TMH7/H8) bicelle sample. The results identify discrete regional interactions between hCB1(TMH7/H8) and membrane lipid molecules that increase phospholipid motion and decrease phospholipid order, indicating that the peptide's partial traversal of the bilayer alters membrane structure. These data offer new insight into hCB1(TMH7/H8) properties and support the concept that the membrane bilayer itself may serve as a mechanochemical mediator of hCB1/GPCR signal transduction. Since interaction with its membrane environment has been implicated in hCB1 function and its modulation by small-molecule therapeutics, our work should help inform hCB1 pharmacology and the design of hCB1-targeted drugs.
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Affiliation(s)
- Elvis K Tiburu
- Center for Drug Discovery and Department of Chemistry and Chemical Biology, Northeastern University, 360 Huntington Avenue, 116 Mugar Hall, Boston, Massachusetts 02115-5000, United States of America
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32
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Pérez‐Nueno VI, Ritchie DW. Applying in silico tools to the discovery of novel CXCR4 inhibitors. Drug Dev Res 2010. [DOI: 10.1002/ddr.20406] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Violeta I. Pérez‐Nueno
- INRIA Nancy – Grand Est, LORIA (Laboratoire Lorrain de Recherche en Informatique et ses Applications), Vandoeuvre‐les‐Nancy, France
| | - David W. Ritchie
- INRIA Nancy – Grand Est, LORIA (Laboratoire Lorrain de Recherche en Informatique et ses Applications), Vandoeuvre‐les‐Nancy, France
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Scrima M, Di Marino S, Grimaldi M, Mastrogiacomo A, Novellino E, Bifulco M, D'Ursi AM. Binding of the hemopressin peptide to the cannabinoid CB1 receptor: structural insights. Biochemistry 2010; 49:10449-57. [PMID: 21062041 DOI: 10.1021/bi1011833] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Hemopressin, a bioactive nonapeptide derived from the α1 chain of hemoglobin, was recently shown to possess selective antagonist activity at the cannabinoid CB(1) receptor [Heimann, A. S., et al. (2007) Proc. Natl. Acad. Sci. U.S.A. 104, 20588-20593]. CB(1) receptor antagonists have been extensively studied for their possible therapeutic use in the treatment of obesity, drug abuse, and heroin addiction. In particular, many compounds acting as CB(1) receptor antagonists have been synthesized and subjected to experiments as possible anti-obesity drugs, but their therapeutic application is still complicated by important side effects. Using circular dichroism and nuclear magnetic resonance spectroscopy, this work reports the conformational analysis of hemopressin and its truncated, biologically active fragment hemopressin(1-6). The binding modes of both hemopressin and hemopressin(1-6) are investigated by molecular docking calculations. Our conformational data indicate that regular turn structures in the central portion of hemopressin and hemopressin(1-6) are critical for an effective interaction with the receptor. The results of molecular docking calculations, indicating similarities and differences in comparison to the most accepted CB(1) pharmacophore model, suggest the possibility of new chemical scaffolds for the design of new CB(1) antagonist lead compounds.
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Affiliation(s)
- Mario Scrima
- Department of Pharmaceutical Sciences, University of Salerno, I-84084 Fisciano, Italy
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34
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Weber KC, De Lima EF, De Mello PH, Da Silva ABF, Honório KM. Research Article: Insights into the Molecular Requirements for the Anti-obesity Activity of a Series of CB1 Ligands. Chem Biol Drug Des 2010; 76:320-9. [DOI: 10.1111/j.1747-0285.2010.01016.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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35
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Sun Q, Hirasawa A, Hara T, Kimura I, Adachi T, Awaji T, Ishiguro M, Suzuki T, Miyata N, Tsujimoto G. Structure-activity relationships of GPR120 agonists based on a docking simulation. Mol Pharmacol 2010; 78:804-10. [PMID: 20685848 DOI: 10.1124/mol.110.066324] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
GPR120 is a G protein-coupled receptor expressed preferentially in the intestinal tract and adipose tissue, that has been implicated in mediating free fatty acid-stimulated glucagon-like peptide-1 (GLP-1) secretion. To develop GPR120-specific agonists, a series of compounds (denoted as NCG compounds) derived from a peroxisome proliferator-activated receptor γ agonist were synthesized, and their structure-activity relationships as GPR120 agonists were explored. To examine the agonistic activities of these newly synthesized NCG compounds, and of compounds already shown to have GPR120 agonistic activity (grifolic acid and MEDICA16), we conducted docking simulation in a GPR120 homology model that was developed on the basis of a photoactivated model derived from the crystal structure of bovine rhodopsin. We calculated the hydrogen bonding energies between the compounds and the GPR120 model. These energies correlated well with the GPR120 agonistic activity of the compounds (R(2) = 0.73). NCG21, the NCG compound with the lowest calculated hydrogen bonding energy, showed the most potent extracellular signal-regulated kinase (ERK) activation in a cloned GPR120 system. Furthermore, NCG21 potently activated ERK, intracellular calcium responses and GLP-1 secretion in murine enteroendocrine STC-1 cells that express GPR120 endogenously. Moreover, administration of NCG21 into the mouse colon caused an increase in plasma GLP-1 levels. Taken together, our present study showed that a docking simulation using a GPR120 homology model might be useful to predict the agonistic activity of compounds.
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Affiliation(s)
- Qi Sun
- Department of Genomic Drug Discovery Science, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan
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36
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Lange JHM, Coolen HKAC, van der Neut MAW, Borst AJM, Stork B, Verveer PC, Kruse CG. Design, Synthesis, Biological Properties, and Molecular Modeling Investigations of Novel Tacrine Derivatives with a Combination of Acetylcholinesterase Inhibition and Cannabinoid CB1 Receptor Antagonism. J Med Chem 2010; 53:1338-46. [DOI: 10.1021/jm901614b] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Jos H. M. Lange
- Solvay Pharmaceuticals, Research Laboratories, C. J. van Houtenlaan 36, 1381 CP Weesp, The Netherlands
| | - Hein K. A. C. Coolen
- Solvay Pharmaceuticals, Research Laboratories, C. J. van Houtenlaan 36, 1381 CP Weesp, The Netherlands
| | | | - Alice J. M. Borst
- Solvay Pharmaceuticals, Research Laboratories, C. J. van Houtenlaan 36, 1381 CP Weesp, The Netherlands
| | - Bob Stork
- Solvay Pharmaceuticals, Research Laboratories, C. J. van Houtenlaan 36, 1381 CP Weesp, The Netherlands
| | - Peter C. Verveer
- Solvay Pharmaceuticals, Research Laboratories, C. J. van Houtenlaan 36, 1381 CP Weesp, The Netherlands
| | - Chris G. Kruse
- Solvay Pharmaceuticals, Research Laboratories, C. J. van Houtenlaan 36, 1381 CP Weesp, The Netherlands
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37
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Reggio PH. Toward the design of cannabinoid CB1 receptor inverse agonists and neutral antagonists. Drug Dev Res 2009. [DOI: 10.1002/ddr.20337] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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38
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Schifano F, Corazza O, Deluca P, Davey Z, Di Furia L, Farre' M, Flesland L, Mannonen M, Pagani S, Peltoniemi T, Pezzolesi C, Scherbaum N, Siemann H, Skutle A, Torrens M, Van Der Kreeft P. Psychoactive drug or mystical incense? Overview of the online available information on Spice products. ACTA ACUST UNITED AC 2009. [DOI: 10.1080/17542860903350888] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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39
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Ahn KH, Bertalovitz AC, Mierke DF, Kendall DA. Dual role of the second extracellular loop of the cannabinoid receptor 1: ligand binding and receptor localization. Mol Pharmacol 2009; 76:833-42. [PMID: 19643997 DOI: 10.1124/mol.109.057356] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The seven transmembrane alpha-helices of G protein-coupled receptors (GPCRs) are the hallmark of this superfamily. Intrahelical interactions are critical to receptor assembly and, for the GPCR subclass that binds small molecules, ligand binding. Most research has focused on identifying the ligand binding pocket within the helical bundle, whereas the role of the extracellular loops remains undefined. Molecular modeling of the cannabinoid receptor 1 (CB1) extracellular loop 2 (EC2), however, suggests that EC2 is poised for key interactions. To test this possibility, we employed alanine scanning mutagenesis of CB1 EC2 and identified two distinct regions critical for ligand binding, G protein coupling activity, and receptor trafficking. Receptors with mutations in the N terminus of EC2 (W255A, N256A) were retained in the endoplasmic reticulum and did not bind the agonist (1R,3R,4R)-3-[2-hydroxy-4-(1,1-dimethylheptyl)-phenyl]-4-(3-hydroxypropyl)cyclohexan-1-ol (CP55940) or the inverse agonist N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide(SR141716A). In contrast, the C terminus of EC2 differentiates agonist and inverse agonist; the P269A, H270A, and I271A receptors exhibited diminished binding for several agonists but bound inverse agonists SR141716A, N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (AM251), and 4-[6-methoxy-2-(4-methoxyphenyl)benzofuran-3-carbonyl]benzonitrile (LY320135) with wild-type receptor affinity. The F268A receptor involving substitution in the Cys-X-X-X-Ar motif, displayed both impaired localization and ligand binding. Other amino acid substitutions at position 268 revealed that highly hydrophobic residues are required to accomplish both functions. It is noteworthy that a F268W receptor was trafficked to the cell surface yet displayed differential binding preference for inverse agonists comparable with the P269A, H270A, and I271A receptors. The findings are consistent with a dual role for EC2 in stabilizing receptor assembly and in ligand binding.
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Affiliation(s)
- Kwang H Ahn
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269-3125, USA
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40
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Durdagi S, Papadopoulos MG, Zoumpoulakis PG, Koukoulitsa C, Mavromoustakos T. A computational study on cannabinoid receptors and potent bioactive cannabinoid ligands: homology modeling, docking, de novo drug design and molecular dynamics analysis. Mol Divers 2009; 14:257-76. [DOI: 10.1007/s11030-009-9166-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Accepted: 05/17/2009] [Indexed: 11/28/2022]
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41
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Rational design, synthesis and biological evaluation of new 1,5-diarylpyrazole derivatives as CB1 receptor antagonists, structurally related to rimonabant. Eur J Med Chem 2008; 43:2627-38. [DOI: 10.1016/j.ejmech.2008.01.043] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2007] [Revised: 01/25/2008] [Accepted: 01/31/2008] [Indexed: 11/22/2022]
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42
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Di Marzo V. CB1 receptor antagonism: biological basis for metabolic effects. Drug Discov Today 2008; 13:1026-41. [DOI: 10.1016/j.drudis.2008.09.001] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2008] [Revised: 08/20/2008] [Accepted: 09/01/2008] [Indexed: 11/15/2022]
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43
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Durdagi S, Reis H, Papadopoulos MG, Mavromoustakos T. Comparative molecular dynamics simulations of the potent synthetic classical cannabinoid ligand AMG3 in solution and at binding site of the CB1 and CB2 receptors. Bioorg Med Chem 2008; 16:7377-87. [DOI: 10.1016/j.bmc.2008.06.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2008] [Revised: 05/31/2008] [Accepted: 06/11/2008] [Indexed: 11/26/2022]
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44
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Zheng D, Bode AM, Zhao Q, Cho YY, Zhu F, Ma WY, Dong Z. The cannabinoid receptors are required for ultraviolet-induced inflammation and skin cancer development. Cancer Res 2008; 68:3992-8. [PMID: 18483286 DOI: 10.1158/0008-5472.can-07-6594] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Solar UV irradiation is an important carcinogen that leads to the development of skin cancer, which is the most common human cancer. However, the receptors that mediate UV-induced skin carcinogenesis have not yet been unequivocally identified. Here we showed that UV irradiation directly activates cannabinoid receptors 1 and 2 (CB1/2). Notably, our data indicated that the absence of the CB1/2 receptors in mice results in a dramatic resistance to UVB-induced inflammation and a marked decrease in UVB-induced skin carcinogenesis. A marked attenuation of UVB-induced activation of mitogen-activated protein kinases and nuclear factor- kappaB was associated with CB1/2 deficiency. These data provide direct evidence indicating that the CB1/2 receptors play a key role in UV-induced inflammation and skin cancer development.
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Affiliation(s)
- Duo Zheng
- Hormel Institute, University of Minnesota, Austin, Minnesota, USA.
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45
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Yanamala N, Tirupula KC, Klein-Seetharaman J. Preferential binding of allosteric modulators to active and inactive conformational states of metabotropic glutamate receptors. BMC Bioinformatics 2008; 9 Suppl 1:S16. [PMID: 18315847 PMCID: PMC2259417 DOI: 10.1186/1471-2105-9-s1-s16] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Metabotropic glutamate receptors (mGluRs) are G protein coupled receptors that play important roles in synaptic plasticity and other neuro-physiological and pathological processes. Allosteric mGluR ligands are particularly promising drug targets because of their modulatory effects--enhancing or suppressing the response of mGluRs to glutamate. The mechanism by which this modulation occurs is not known. Here, we propose the hypothesis that positive and negative modulators will differentially stabilize the active and inactive conformations of the receptors, respectively. To test this hypothesis, we have generated computational models of the transmembrane regions of different mGluR subtypes in two different conformations. The inactive conformation was modeled using the crystal structure of the inactive, dark state of rhodopsin as template and the active conformation was created based on a recent model of the light-activated state of rhodopsin. Ligands for which the nature of their allosteric effects on mGluRs is experimentally known were docked to the modeled mGluR structures using ArgusLab and Autodock softwares. We find that the allosteric ligand binding pockets of mGluRs are overlapping with the retinal binding pocket of rhodopsin, and that ligands have strong preferences for the active and inactive states depending on their modulatory nature. In 8 out of 14 cases (57%), the negative modulators bound the inactive conformations with significant preference using both docking programs, and 6 out of 9 cases (67%), the positive modulators bound the active conformations. Considering results by the individual programs only, even higher correlations were observed: 12/14 (86%) and 8/9 (89%) for ArgusLab and 10/14 (71%) and 7/9 (78%) for AutoDock. These findings strongly support the hypothesis that mGluR allosteric modulation occurs via stabilization of different conformations analogous to those identified in rhodopsin where they are induced by photochemical isomerization of the retinal ligand--despite the extensive differences in sequences between mGluRs and rhodopsin.
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Affiliation(s)
- Naveena Yanamala
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA.
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Padgett LW, Howlett AC, Shim JY. Binding mode prediction of conformationally restricted anandamide analogs within the CB1 receptor. J Mol Signal 2008; 3:5. [PMID: 18302793 PMCID: PMC2289822 DOI: 10.1186/1750-2187-3-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2007] [Accepted: 02/26/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND CB1 cannabinoid receptors are G-protein coupled receptors for endocannabinoids including anandamide and 2-arachidonoylglycerol. Because these arachidonic acid metabolites possess a 20-carbon polyene chain as the alkyl terminal moiety, they are highly flexible with the potential to adopt multiple biologically relevant conformations, particularly those in a bent form. To better understand the molecular interactions associated with binding and steric trigger mechanisms of receptor activation, a series of conformationally-restricted anandamide analogs having a wide range of affinity and efficacy were evaluated. RESULTS A CB1 receptor model was constructed to include the extracellular loops, particularly extracellular loop 2 which possesses an internal disulfide linkage. Using both Glide (Schrödinger) and Affinity (Accelrys) docking programs, binding conformations of six anandamide analogs were identified that conform to rules applicable to the potent, efficacious and stereoselective non-classical cannabinoid CP55244. Calculated binding energies of the optimum structures from both procedures correlated well with the reported binding affinity values. The most potent and efficacious of the ligands adopted conformations characterized by interactions with both the helix-3 lysine and hydrophobic residues that interact with CP55244. The other five compounds formed fewer or less energetically favorable interactions with these critical residues. The flexibility of the tested anandamide analogs, measured by torsion angles around the benzene as well as the stretch between side chain moieties, could contribute to the differences in ability to interact with the CB1 receptor. CONCLUSION Analyses of multiple poses of conformationally-restricted anandamide analogs permitted identification of favored amino acid interactions within the CB1 receptor binding pocket. A ligand possessing both high affinity and cannabinoid agonist efficacy was able to interact with both polar and hydrophobic interaction sites utilized by the potent and efficacious non-classical cannabinoid CP55940. In contrast, other analogs characterized by reduced affinity or efficacy exhibited less favorable interactions with those key residues.
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Affiliation(s)
- Lea W Padgett
- Neuroscience of Drug Abuse Research Program, Julius L, Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, NC 27707, USA.
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Gonzalez A, Duran LS, Araya-Secchi R, Garate JA, Pessoa-Mahana CD, Lagos CF, Perez-Acle T. Computational modeling study of functional microdomains in cannabinoid receptor type 1. Bioorg Med Chem 2008; 16:4378-89. [PMID: 18342519 DOI: 10.1016/j.bmc.2008.02.070] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2007] [Revised: 02/18/2008] [Accepted: 02/21/2008] [Indexed: 10/22/2022]
Abstract
The seven transmembrane helices (TMH) G-protein-coupled receptors (GPCRs) constitute one of the largest superfamily of signaling proteins found in mammals. Some of its members, in which the cannabinoid (CB) receptors are included, stand out because their functional states can be modulated by a broad spectrum of effector molecules. The relative ligand promiscuity exhibited by these receptors could be related with particular attributes conferred by their molecular architecture and represents a motivating issue to be explored. In this regard, this study represents an effort to investigate the cannabinoid receptor type 1 (CB1) ligand recognition plasticity, using comparative modeling, molecular dynamics (MD) simulations and docking. Our results suggest that a cooperative set of subtle structural rearrangements within the TMHs provide to the CB1 protein the plasticity to reach alternate configurations. These changes include the relaxation of intramolecular constraints, the rotations, translations and kinks of the majority of TMHs and the reorganization of the ligand binding cavities.
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Affiliation(s)
- Angel Gonzalez
- Centre for Bioinformatics CBUC, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Portugal 49-6513492, Santiago, Chile.
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Durdagi S, Papadopoulos MG, Papahatjis DP, Mavromoustakos T. Combined 3D QSAR and molecular docking studies to reveal novel cannabinoid ligands with optimum binding activity. Bioorg Med Chem Lett 2007; 17:6754-63. [DOI: 10.1016/j.bmcl.2007.10.044] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2007] [Revised: 10/11/2007] [Accepted: 10/13/2007] [Indexed: 11/28/2022]
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Unique agonist-bound cannabinoid CB1 receptor conformations indicate agonist specificity in signaling. Eur J Pharmacol 2007; 581:19-29. [PMID: 18162180 DOI: 10.1016/j.ejphar.2007.11.053] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2007] [Revised: 11/08/2007] [Accepted: 11/21/2007] [Indexed: 11/20/2022]
Abstract
Cannabinoid drugs differ in their rank order of potency to produce analgesia versus other central nervous system effects. We propose that these differences are due to unique agonist-bound cannabinoid CB1 receptor conformations that exhibit different affinities for individual subsets of intracellular signal transduction pathways. In order to test this hypothesis, we have used plasmon-waveguide resonance (PWR) spectroscopy, a sensitive method that can provide direct information about ligand-protein and protein-protein interactions, and can detect conformational changes in lipid-embedded proteins. A recombinant epitope-tagged human cannabinoid CB1 receptor was expressed in insect Sf9 cells, solubilized and purified using two-step affinity chromatography. The purified receptor was incorporated into a lipid bilayer on the surface of the PWR resonator. PWR spectroscopy demonstrated that cannabinoid agonists exhibit high affinity (KD=0.2+/-0.03 nM and 2+/-0.4 nM for CP 55,940 and WIN 55,212-2, respectively) for the purified epitope tagged hCB(1) receptor. Interestingly however, these structurally different cannabinoid agonists shifted the PWR spectra in opposite directions, indicating that CP 55,940 and WIN 55,212-2 binding leads to different hCB1 receptor conformations. Furthermore, PWR experiments also indicated that these CP 55,940-and WIN 55,212-bound hCB1 receptor conformations exhibit slightly different affinities to an inhibitory G protein heterotrimer, Gi1 (KD=27+/-8 nM and KD=10.7+/-4.7 nM, respectively), whereas they strikingly differ in their ability to activate this G protein type.
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Paiva ACM, Oliveira L, Horn F, Bywater RP, Vriend G. Modeling GPCRs. ERNST SCHERING FOUNDATION SYMPOSIUM PROCEEDINGS 2007:23-47. [PMID: 17703576 DOI: 10.1007/2789_2006_002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Many GPCR models have been built over the years for many different purposes, of which drug-design undoubtedly has been the most frequent one. The release of the structure of bovine rhodopsin in August 2000 enabled us to analyze models built before that period to learn things for the models we build today. We conclude that the GPCR modeling field is riddled with "common knowledge". Several characteristics of the bovine rhodopsin structure came as a big surprise, and had obviously not been predicted, which led to large errors in the models. Some of these surprises, however, could have been predicted if the modelers had more rigidly stuck to the rule that holds for all models, namely that a model should explain all experimental facts, and not just those facts that agree with the modeler's preconceptions.
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Affiliation(s)
- A C M Paiva
- CMBI NCMLS, UMC, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands
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