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Myers MC, Bilder DM, Cavallaro CL, Chao HJ, Su S, Burford NT, Nayeem A, Wang T, Yan M, Langish RA, Dabros M, Li YX, Rose AV, Behnia K, Onorato JM, Gargalovic PS, Wexler RR, Lawrence RM. Discovery and SAR of aryl hydroxy pyrimidinones as potent small molecule agonists of the GPCR APJ. Bioorg Med Chem Lett 2020; 30:126955. [DOI: 10.1016/j.bmcl.2020.126955] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 01/01/2020] [Indexed: 01/07/2023]
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Scott CE, Tang Y, Alt A, Burford NT, Gerritz SW, Ogawa LM, Zhang L, Kendall DA. Identification and biochemical analyses of selective CB 2 agonists. Eur J Pharmacol 2019; 854:1-8. [PMID: 30951717 DOI: 10.1016/j.ejphar.2019.03.054] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 03/19/2019] [Accepted: 03/28/2019] [Indexed: 12/14/2022]
Abstract
Cannabinoid CB1 and CB2 receptors are activated by Δ9-tetrahydrocannabinol, a psychoactive component of marijuana. The cannabinoid CB1 receptor is primarily located in the brain and is responsible for the psychoactive side effects, whereas the cannabinoid CB2 receptor is located in immune cells and is an attractive target for immune-related maladies. We identify small molecules that selectively bind to the cannabinoid CB2 receptor and can be further developed into therapeutics. The affinity of three molecules, ABK5, ABK6, and ABK7, to the cannabinoid CB2 receptor was determined with radioligand competition binding. The potency of G-protein coupling was determined with GTPγS binding. The three compounds bound selectively to the cannabinoid CB2 receptor, and no binding to the cannabinoid CB1 receptor was detected up to 10 μM. Immunoblotting studies show that the amount of ERK1/2 and MEK phosphorylation increased in a Gi/o-dependent manner. Furthermore, an immune cell line (Jurkat cells) was treated with ABK5, and as a result, inhibited cell proliferation. These three compounds are novel cannabinoid CB2 receptor agonists and hold promise to be further developed to treat inflammation and the often-associated pain.
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Affiliation(s)
- Caitlin E Scott
- Department of Pharmaceutical Sciences, University of Connecticut, 69 N Eagleville Rd, Storrs, CT, 06269, USA
| | - Yaliang Tang
- Department of Pharmaceutical Sciences, University of Connecticut, 69 N Eagleville Rd, Storrs, CT, 06269, USA
| | - Andrew Alt
- Bristol-Myers Squibb, Research and Development, 5 Research Parkway, Wallingford, CT, 06492, USA
| | - Neil T Burford
- Bristol-Myers Squibb, Research and Development, 5 Research Parkway, Wallingford, CT, 06492, USA
| | - Samuel W Gerritz
- Bristol-Myers Squibb, Research and Development, 5 Research Parkway, Wallingford, CT, 06492, USA
| | - Lisa M Ogawa
- Bristol-Myers Squibb, Research and Development, 5 Research Parkway, Wallingford, CT, 06492, USA
| | - Litao Zhang
- Bristol-Myers Squibb, Research and Development, 5 Research Parkway, Wallingford, CT, 06492, USA
| | - Debra A Kendall
- Department of Pharmaceutical Sciences, University of Connecticut, 69 N Eagleville Rd, Storrs, CT, 06269, USA.
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Burford NT, Watson J, Alt A. Standard Curves Are Necessary to Determine Pharmacological Properties for Ligands in Functional Assays Using Competition Binding Technologies. Assay Drug Dev Technol 2018; 15:320-329. [PMID: 29120673 DOI: 10.1089/adt.2017.811] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Homogeneous functional assays that utilize competition binding technology are widely used for determining pharmacological properties such as intrinsic activity and potency. One example is time-resolved fluorescence resonance energy transfer (TR-FRET) 3',5'-cyclic adenosine monophosphate (cAMP) assays, where labeled cAMP (tracer) and a labeled anti-cAMP antibody bind together to produce a TR-FRET signal when the two constituents are proximal to each other. This signal is disrupted when unlabeled and cellularly generated cAMP competes with the tracer cAMP for binding to the labeled antibody. It is important that the resulting assay signal, usually expressed as a TR-FRET ratio, be transformed to cAMP concentration using a cAMP standard curve. However, examples are still generated in the literature wherein investigators have used the ratiometric signal (not transformed using a standard curve) to determine values for intrinsic activity and potency of ligands. Untransformed raw data often produce reasonable looking sigmoidal concentration response curves, perhaps tempting investigators to use the raw data instead of the transformed data for applying pharmacological models. In this article, we describe the correct procedure for determining the potency and intrinsic activity of ligands that result in changes in cAMP levels using a lysate dilution assay of GLP-1 (7-36)-mediated TR-FRET cAMP accumulation and simulated data. We also highlight how the inappropriate use of raw signal data can dramatically affect interpretation of intrinsic activity and potency of ligands, and how this can adversely affect drug discovery programs. These findings apply not only to cAMP functional assays but also to other functional cellular signaling assays that utilize competition binding technologies.
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Affiliation(s)
- Neil T Burford
- 1 Bristol-Myers Squibb Company , Wallingford, Connecticut
| | - John Watson
- 1 Bristol-Myers Squibb Company , Wallingford, Connecticut
| | - Andrew Alt
- 2 Arvinas, Inc. , New Haven, Connecticut
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4
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Ogawa LM, Burford NT, Liao YH, Scott CE, Hine AM, Dowling C, Chin J, Power M, Hunnicutt EJ, Emerick VL, Banks M, Zhang L, Gerritz SW, Alt A, Kendall DA. Discovery of Selective Cannabinoid CB 2 Receptor Agonists by High-Throughput Screening. SLAS Discov 2017; 23:375-383. [PMID: 29257918 DOI: 10.1177/2472555217748403] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The endocannabinoid system (ECS) plays a diverse role in human physiology ranging from the regulation of mood and appetite to immune modulation and the response to pain. Drug development that targets the cannabinoid receptors (CB1 and CB2) has been explored; however, success in the clinic has been limited by the psychoactive side effects associated with modulation of the neuronally expressed CB1 that are enriched in the CNS. CB2, however, are expressed in peripheral tissues, primarily in immune cells, and thus development of CB2-selective drugs holds the potential to modulate pain among other indications without eliciting anxiety and other undesirable side effects associated with CB1 activation. As part of a collaborative effort among industry and academic laboratories, we performed a high-throughput screen designed to discover selective agonists or positive allosteric modulators (PAMs) of CB2. Although no CB2 PAMs were identified, 167 CB2 agonists were discovered here, and further characterization of four select compounds revealed two with high selectivity for CB2 versus CB1. These results broaden drug discovery efforts aimed at the ECS and may lead to the development of novel therapies for immune modulation and pain management with improved side effect profiles.
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Affiliation(s)
- Lisa M Ogawa
- 1 Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT, USA
| | - Neil T Burford
- 2 Bristol-Myers Squibb, Research and Development, Wallingford, CT, USA
| | - Yu-Hsien Liao
- 3 Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT, USA
| | - Caitlin E Scott
- 3 Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT, USA
| | - Ashley M Hine
- 3 Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT, USA
| | - Craig Dowling
- 2 Bristol-Myers Squibb, Research and Development, Wallingford, CT, USA
| | - Jefferson Chin
- 2 Bristol-Myers Squibb, Research and Development, Wallingford, CT, USA
| | - Mike Power
- 2 Bristol-Myers Squibb, Research and Development, Wallingford, CT, USA
| | | | | | - Martyn Banks
- 2 Bristol-Myers Squibb, Research and Development, Wallingford, CT, USA
| | - Litao Zhang
- 2 Bristol-Myers Squibb, Research and Development, Wallingford, CT, USA
| | - Samuel W Gerritz
- 2 Bristol-Myers Squibb, Research and Development, Wallingford, CT, USA
| | - Andrew Alt
- 2 Bristol-Myers Squibb, Research and Development, Wallingford, CT, USA
| | - Debra A Kendall
- 3 Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT, USA
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Livingston KE, Stanczyk MA, Burford NT, Alt A, Canals M, Traynor JR. Pharmacologic Evidence for a Putative Conserved Allosteric Site on Opioid Receptors. Mol Pharmacol 2017; 93:157-167. [PMID: 29233847 DOI: 10.1124/mol.117.109561] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 11/27/2017] [Indexed: 11/22/2022] Open
Abstract
Allosteric modulators of G protein-coupled receptors, including opioid receptors, have been proposed as possible therapeutic agents with enhanced selectivity. BMS-986122 is a positive allosteric modulator (PAM) of the μ-opioid receptor (µ-OR). BMS-986187 is a structurally distinct PAM for the δ-opioid receptor (δ-OR) that has been reported to exhibit 100-fold selectivity in promoting δ-OR over μ-OR agonism. We used ligand binding and second-messenger assays to show that BMS-986187 is an effective PAM at the μ-OR and at the κ-opioid receptor (κ-OR), but it is ineffective at the nociceptin receptor. The affinity of BMS-986187 for δ-ORs and κ-ORs is approximately 20- to 30-fold higher than for μ-ORs, determined using an allosteric ternary complex model. Moreover, we provide evidence, using a silent allosteric modulator as an allosteric antagonist, that BMS-986187 and BMS-986122 bind to a similar region on all three traditional opioid receptor types (µ-OR, δ-OR, and κ-OR). In contrast to the dogma surrounding allosteric modulators, the results indicate a possible conserved allosteric binding site across the opioid receptor family that can accommodate structurally diverse molecules. These findings have implications for the development of selective allosteric modulators.
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Affiliation(s)
- Kathryn E Livingston
- Department of Pharmacology and Edward F. Domino Research Center, University of Michigan, Ann Arbor, Michigan (K.E.L., M.A.S., J.R.T.); Research and Development/Discovery, Bristol-Myers Squibb Company, Wallingford, Connecticut (N.T.B., A.A.); and Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia (M.C.)
| | - M Alexander Stanczyk
- Department of Pharmacology and Edward F. Domino Research Center, University of Michigan, Ann Arbor, Michigan (K.E.L., M.A.S., J.R.T.); Research and Development/Discovery, Bristol-Myers Squibb Company, Wallingford, Connecticut (N.T.B., A.A.); and Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia (M.C.)
| | - Neil T Burford
- Department of Pharmacology and Edward F. Domino Research Center, University of Michigan, Ann Arbor, Michigan (K.E.L., M.A.S., J.R.T.); Research and Development/Discovery, Bristol-Myers Squibb Company, Wallingford, Connecticut (N.T.B., A.A.); and Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia (M.C.)
| | - Andrew Alt
- Department of Pharmacology and Edward F. Domino Research Center, University of Michigan, Ann Arbor, Michigan (K.E.L., M.A.S., J.R.T.); Research and Development/Discovery, Bristol-Myers Squibb Company, Wallingford, Connecticut (N.T.B., A.A.); and Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia (M.C.)
| | - Meritxell Canals
- Department of Pharmacology and Edward F. Domino Research Center, University of Michigan, Ann Arbor, Michigan (K.E.L., M.A.S., J.R.T.); Research and Development/Discovery, Bristol-Myers Squibb Company, Wallingford, Connecticut (N.T.B., A.A.); and Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia (M.C.)
| | - John R Traynor
- Department of Pharmacology and Edward F. Domino Research Center, University of Michigan, Ann Arbor, Michigan (K.E.L., M.A.S., J.R.T.); Research and Development/Discovery, Bristol-Myers Squibb Company, Wallingford, Connecticut (N.T.B., A.A.); and Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia (M.C.)
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Bisignano P, Burford NT, Shang Y, Marlow B, Livingston KE, Fenton AM, Rockwell K, Budenholzer L, Traynor JR, Gerritz SW, Alt A, Filizola M. Ligand-Based Discovery of a New Scaffold for Allosteric Modulation of the μ-Opioid Receptor. J Chem Inf Model 2015; 55:1836-43. [PMID: 26347990 DOI: 10.1021/acs.jcim.5b00388] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
With the hope of discovering effective analgesics with fewer side effects, attention has recently shifted to allosteric modulators of the opioid receptors. In the past two years, the first chemotypes of positive or silent allosteric modulators (PAMs or SAMs, respectively) of μ- and δ-opioid receptor types have been reported in the literature. During a structure-guided lead optimization campaign with μ-PAMs BMS-986121 and BMS-986122 as starting compounds, we discovered a new chemotype that was confirmed to display μ-PAM or μ-SAM activity depending on the specific substitutions as assessed by endomorphin-1-stimulated β-arrestin2 recruitment assays in Chinese Hamster Ovary (CHO)-μ PathHunter cells. The most active μ-PAM of this series was analyzed further in competition binding and G-protein activation assays to understand its effects on ligand binding and to investigate the nature of its probe dependence.
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Affiliation(s)
- Paola Bisignano
- Department of Structural and Chemical Biology, Icahn School of Medicine at Mount Sinai , New York, New York 10029, United States
| | - Neil T Burford
- Discovery, Bristol-Myers Squibb Company , Wallingford, Connecticut 06492, United States
| | - Yi Shang
- Department of Structural and Chemical Biology, Icahn School of Medicine at Mount Sinai , New York, New York 10029, United States
| | - Brennica Marlow
- Department of Structural and Chemical Biology, Icahn School of Medicine at Mount Sinai , New York, New York 10029, United States
| | - Kathryn E Livingston
- Department of Pharmacology, University of Michigan Medical School , Ann Arbor, Michigan 48109, United States
| | - Abigail M Fenton
- Department of Pharmacology, University of Michigan Medical School , Ann Arbor, Michigan 48109, United States
| | - Kristin Rockwell
- Discovery, Bristol-Myers Squibb Company , Wallingford, Connecticut 06492, United States
| | - Lauren Budenholzer
- Department of Molecular Biophysics and Biochemistry, Yale University , New Haven, Connecticut 06520, United States
| | - John R Traynor
- Department of Pharmacology, University of Michigan Medical School , Ann Arbor, Michigan 48109, United States
| | - Samuel W Gerritz
- Discovery, Bristol-Myers Squibb Company , Wallingford, Connecticut 06492, United States
| | - Andrew Alt
- Discovery, Bristol-Myers Squibb Company , Wallingford, Connecticut 06492, United States
| | - Marta Filizola
- Department of Structural and Chemical Biology, Icahn School of Medicine at Mount Sinai , New York, New York 10029, United States
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7
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Burford NT, Livingston KE, Canals M, Ryan MR, Budenholzer LML, Han Y, Shang Y, Herbst JJ, O'Connell J, Banks M, Zhang L, Filizola M, Bassoni DL, Wehrman TS, Christopoulos A, Traynor JR, Gerritz SW, Alt A. Discovery, synthesis, and molecular pharmacology of selective positive allosteric modulators of the δ-opioid receptor. J Med Chem 2015; 58:4220-9. [PMID: 25901762 DOI: 10.1021/acs.jmedchem.5b00007] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Allosteric modulators of G protein-coupled receptors (GPCRs) have a number of potential advantages compared to agonists or antagonists that bind to the orthosteric site of the receptor. These include the potential for receptor selectivity, maintenance of the temporal and spatial fidelity of signaling in vivo, the ceiling effect of the allosteric cooperativity which may prevent overdose issues, and engendering bias by differentially modulating distinct signaling pathways. Here we describe the discovery, synthesis, and molecular pharmacology of δ-opioid receptor-selective positive allosteric modulators (δ PAMs). These δ PAMs increase the affinity and/or efficacy of the orthosteric agonists leu-enkephalin, SNC80 and TAN67, as measured by receptor binding, G protein activation, β-arrestin recruitment, adenylyl cyclase inhibition, and extracellular signal-regulated kinases (ERK) activation. As such, these compounds are useful pharmacological tools to probe the molecular pharmacology of the δ receptor and to explore the therapeutic potential of δ PAMs in diseases such as chronic pain and depression.
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Affiliation(s)
- Neil T Burford
- †Research and Development/Discovery, Bristol-Myers Squibb Company, 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Kathryn E Livingston
- ‡Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | | | | | | | - Ying Han
- †Research and Development/Discovery, Bristol-Myers Squibb Company, 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Yi Shang
- ⊥Department of Structural and Chemical Biology Icahn School of Medicine at Mount Sinai (ISMMS), New York, New York 10029-6574, United States
| | - John J Herbst
- †Research and Development/Discovery, Bristol-Myers Squibb Company, 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Jonathan O'Connell
- #FORMA Therapeutics, Arsenal Street, Suite 100, Watertown, Massachusetts 02472, United States
| | - Martyn Banks
- †Research and Development/Discovery, Bristol-Myers Squibb Company, 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Litao Zhang
- †Research and Development/Discovery, Bristol-Myers Squibb Company, 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Marta Filizola
- ⊥Department of Structural and Chemical Biology Icahn School of Medicine at Mount Sinai (ISMMS), New York, New York 10029-6574, United States
| | - Daniel L Bassoni
- ∞DiscoveRx Corporation, 42501 Albrae Street, Suite 100, Fremont, California 94538, United States
| | - Tom S Wehrman
- ×Primity Bio, 3350 Scott Boulevard, Ste 6101, Santa Clara, California 95054, United States
| | | | - John R Traynor
- ‡Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Samuel W Gerritz
- †Research and Development/Discovery, Bristol-Myers Squibb Company, 5 Research Parkway, Wallingford, Connecticut 06492, United States
| | - Andrew Alt
- †Research and Development/Discovery, Bristol-Myers Squibb Company, 5 Research Parkway, Wallingford, Connecticut 06492, United States
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8
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Abstract
The continued evolution of our understanding of G protein-coupled receptor (GPCR) signaling has revealed new opportunities for drug discovery. Specifically, biased agonism at GPCRs and allosteric modulation of GPCRs both represent emerging areas of GPCR biology that hold promise for the development of novel GPCR-targeted therapeutics that may provide greater therapeutic efficacy and/or improved side-effect profiles. To obtain initial chemical leads, high-throughput screening (HTS) of a large compound library for the desired activity is often deployed during the early stages of a discovery program. The identification of allosteric modulators, in particular, poses significant challenges for HTS. We describe several HTS protocols designed for the identification of GPCR ligands, with a particular focus on the identification of allosteric modulators.
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Affiliation(s)
- Robert L Bertekap
- Lead Discovery, Bristol-Myers Squibb Company, 5 Research Parkway, Wallingford, CT, 06492, USA
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Burford NT, Wehrman T, Bassoni D, O'Connell J, Banks M, Zhang L, Alt A. Identification of selective agonists and positive allosteric modulators for µ- and δ-opioid receptors from a single high-throughput screen. ACTA ACUST UNITED AC 2014; 19:1255-65. [PMID: 25047277 DOI: 10.1177/1087057114542975] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Hetero-oligomeric complexes of G protein-coupled receptors (GPCRs) may represent novel therapeutic targets exhibiting different pharmacology and tissue- or cell-specific site of action compared with receptor monomers or homo-oligomers. An ideal tool for validating this concept pharmacologically would be a hetero-oligomer selective ligand. We set out to develop and execute a 1536-well high-throughput screen of over 1 million compounds to detect potential hetero-oligomer selective ligands using a β-arrestin recruitment assay in U2OS cells coexpressing recombinant µ- and δ-opioid receptors. Hetero-oligomer selective ligands may bind to orthosteric or allosteric sites, and we might anticipate that the formation of hetero-oligomers may provide novel allosteric binding pockets for ligand binding. Therefore, our goal was to execute the screen in such a way as to identify positive allosteric modulators (PAMs) as well as agonists for µ, δ, and hetero-oligomeric receptors. While no hetero-oligomer selective ligands were identified (based on our selection criteria), this single screen did identify numerous µ- and δ-selective agonists and PAMs as well as nonselective agonists and PAMs. To our knowledge, these are the first µ- and δ-opioid receptor PAMs described in the literature.
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Affiliation(s)
- Neil T Burford
- Leads Discovery and Optimization, Bristol-Myers Squibb Company, Wallingford, CT, USA
| | | | | | | | - Martyn Banks
- Leads Discovery and Optimization, Bristol-Myers Squibb Company, Wallingford, CT, USA
| | - Litao Zhang
- Leads Discovery and Optimization, Bristol-Myers Squibb Company, Wallingford, CT, USA
| | - Andrew Alt
- Leads Discovery and Optimization, Bristol-Myers Squibb Company, Wallingford, CT, USA
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10
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Burford NT, Traynor JR, Alt A. Positive allosteric modulators of the μ-opioid receptor: a novel approach for future pain medications. Br J Pharmacol 2014; 172:277-86. [PMID: 24460691 DOI: 10.1111/bph.12599] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 01/09/2014] [Accepted: 01/19/2014] [Indexed: 01/09/2023] Open
Abstract
UNLABELLED Morphine and other agonists of the μ-opioid receptor are used clinically for acute and chronic pain relief and are considered to be the gold standard for pain medication. However, these opioids also have significant side effects, which are also mediated via activation of the μ-opioid receptor. Since the latter half of the twentieth century, researchers have sought to tease apart the mechanisms underlying analgesia, tolerance and dependence, with the hope of designing drugs with fewer side effects. These efforts have revolved around the design of orthosteric agonists with differing pharmacokinetic properties and/or selectivity profiles for the different opioid receptor types. Recently, μ-opioid receptor-positive allosteric modulators (μ-PAMs) were identified, which bind to a (allosteric) site on the μ-opioid receptor separate from the orthosteric site that binds an endogenous agonist. These allosteric modulators have little or no detectable functional activity when bound to the receptor in the absence of orthosteric agonist, but can potentiate the activity of bound orthosteric agonist, seen as an increase in apparent potency and/or efficacy of the orthosteric agonist. In this review, we describe the potential advantages that a μ-PAM approach might bring to the design of novel therapeutics for pain that may lack the side effects currently associated with opioid therapy. LINKED ARTICLES This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2.
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Affiliation(s)
- N T Burford
- GPCR Lead Discovery & Optimization, Bristol-Myers Squibb Company, Wallingford, CT, USA
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11
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Noblin DJ, Bertekap RL, Burford NT, Hendricson A, Zhang L, Knox R, Banks M, O'Connell J, Alt A. Development of a high-throughput calcium flux assay for identification of all ligand types including positive, negative, and silent allosteric modulators for G protein-coupled receptors. Assay Drug Dev Technol 2012; 10:457-67. [PMID: 22746835 DOI: 10.1089/adt.2011.443] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In recent years, the increased use of cell-based functional assays for G protein-coupled receptors in high-throughput screening has enabled the design of robust assays to identify allosteric modulators (AMs) in addition to the more traditional orthosteric agonists and antagonists. In this article, the authors describe a screening format able to identify all ligand types using a triple-add assay that measures changes in cytosolic calcium concentration with three separate additions and reads in the same assay plate. This triple-add assay captures more small molecule ligand types than previously described assay formats without a significant increase in screening cost. Finally, the customizability of the triple-add assay to suit the needs of various AM screening programs is demonstrated.
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Affiliation(s)
- Devin J Noblin
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut, USA
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Pendri A, Dodd DS, Chen J, Cvijic ME, Kang L, Baska RA, Carlson KE, Burford NT, Sun C, Ewing WR, Gerritz SW. Solid phase synthesis of 1,5-diarylpyrazole-4-carboxamides: discovery of antagonists of the CB-1 receptor. ACS Comb Sci 2012; 14:197-204. [PMID: 22340081 DOI: 10.1021/co200147y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
We have developed a solid phase synthesis route to 1,5-substituted pyrazole-4-carboxamides with three diversity points aimed at the discovery of new compounds as potential G-Protein coupled receptor (GPCR) ligands. The new chemistry involves acylation of a resin bound secondary amine with a β-ketoester via transamidation, conversion of the resulting β-ketoamide to the corresponding vinylogous amide, pyrazole formation upon reaction with a aryl hydrzine, and cleavage of the product from the resin. Using the reported methodology, we describe the syntheses of multiple arrays of pyrazoles that were used collectively to construct a library of more than 1000 analogues. Several members of this library displayed submicromolar antagonist activities at the cannabinoid subtype 1 (CB-1) receptor.
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Affiliation(s)
- Annapurna Pendri
- Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut
06492, United States
| | - Dharmpal S. Dodd
- Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut
06492, United States
| | - Jing Chen
- Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut
06492, United States
| | - Mary Ellen Cvijic
- Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut
06492, United States
| | - Liya Kang
- Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut
06492, United States
| | - Rose A. Baska
- Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut
06492, United States
| | - Kenneth E. Carlson
- Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut
06492, United States
| | - Neil T. Burford
- Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut
06492, United States
| | - Chongqing Sun
- Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut
06492, United States
| | - William R. Ewing
- Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut
06492, United States
| | - Samuel W. Gerritz
- Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut
06492, United States
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13
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Harikrishnan LS, Srivastava N, Kayser LE, Nirschl DS, K K, Roy A, Gupta A, Karmakar S, Karatt T, Mathur A, Burford NT, Chen J, Kong Y, Cvijic M, Cooper CB, Poss MA, Trainor GL, Wong TW. Identification and optimization of small molecule antagonists of vasoactive intestinal peptide receptor-1 (VIPR1). Bioorg Med Chem Lett 2012; 22:2287-90. [DOI: 10.1016/j.bmcl.2012.01.082] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Revised: 01/17/2012] [Accepted: 01/20/2012] [Indexed: 10/14/2022]
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14
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Burford NT, Watson J, Bertekap R, Alt A. Strategies for the identification of allosteric modulators of G-protein-coupled receptors. Biochem Pharmacol 2011; 81:691-702. [DOI: 10.1016/j.bcp.2010.12.012] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 12/09/2010] [Accepted: 12/10/2010] [Indexed: 11/15/2022]
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15
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Ellsworth BA, Wang Y, Zhu Y, Pendri A, Gerritz SW, Sun C, Carlson KE, Kang L, Baska RA, Yang Y, Huang Q, Burford NT, Cullen MJ, Johnghar S, Behnia K, Pelleymounter MA, Washburn WN, Ewing WR. Discovery of pyrazine carboxamide CB1 antagonists: The introduction of a hydroxyl group improves the pharmaceutical properties and in vivo efficacy of the series. Bioorg Med Chem Lett 2007; 17:3978-82. [PMID: 17513109 DOI: 10.1016/j.bmcl.2007.04.087] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2007] [Revised: 04/24/2007] [Accepted: 04/25/2007] [Indexed: 10/23/2022]
Abstract
Structure-activity relationships for a series of pyrazine carboxamide CB1 antagonists are reported. Pharmaceutical properties of the series are improved via inclusion of hydroxyl-containing sidechains. This structural modification sufficiently improved ADME properties of an orally inactive series such that food intake reduction was achieved in rat feeding models. Compound 35 elicits a 46% reduction in food intake in ad libidum fed rats 4-h post-dose.
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Affiliation(s)
- Bruce A Ellsworth
- Pharmaceutical Research Institute, Bristol Myers Squibb Co., PO Box 5400 Princeton, NJ 08543, USA.
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16
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Li JJ, Chao HG, Wang H, Tino JA, Lawrence RM, Ewing WR, Ma Z, Yan M, Slusarchyk D, Seethala R, Sun H, Li D, Burford NT, Stoffel RH, Salyan ME, Li CY, Witkus M, Zhao N, Rich A, Gordon DA. Discovery of a Potent and Novel Motilin Agonist. J Med Chem 2004; 47:1704-8. [PMID: 15027861 DOI: 10.1021/jm0304865] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A novel series of dihydro- and tetrahydrotriazolopyridazine-1,3-dione-based amino acid derivatives were identified as very potent motilin receptor agonists. Incorporating one additional phenylethyl glycinamide subunit to 1 (EC(50) = 660 nM) was found to improve in vitro potency approximately 3000-fold, resulting in compound 10 (EC(50) = 0.22 nM). The more potent enantiomer 11A has an EC(50) of 0.047 nM in the motilin receptor functional assay and a K(i) of 0.7 nM in the binding assay. In addition, compound 11A was shown to have a significantly reduced tendency to cause receptor desensitization as compared with the motilin receptor agonist ABT-229.
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Affiliation(s)
- James J Li
- Discovery Chemistry, Bristol-Myers Squibb Pharmaceutical Research Institute, P.O. Box 5400, Princeton, New Jersey 08643-5400, USA.
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17
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Burford NT, Wang D, Sadée W. G-protein coupling of mu-opioid receptors (OP3): elevated basal signalling activity. Biochem J 2000; 348 Pt 3:531-7. [PMID: 10839983 PMCID: PMC1221094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
To determine mu-opioid receptor (OP(3)) signalling activity, guanosine 5'-[gamma-[(35)S]thio]triphosphate (GTP[(35)S]) binding to G-proteins was measured in the membranes of human embryonic kidney cells (HEK-293) transfected with mu-opioid receptor (HEK-mu). GTP[(35)S] binding to HEK-mu membranes was significantly elevated compared with HEK-293 control membranes (without OP(3)), and this was abolished by pertussis-toxin pretreatment. The irreversible antagonist beta-chlornaltrexamine (beta-CNA) dose-dependently decreased elevated basal G-protein coupling of HEK-mu to control levels in cells devoid of OP(3). This characterizes beta-CNA as an inverse OP(3) agonist. Immunoprecipitation of solubilized G-proteins with G(i3)alpha antisera demonstrated that basal GTP[(35)S] binding to G(i3)alpha was also substantially elevated in HEK-mu membranes over the control, whereas G(i3)alpha protein levels were unchanged. Basal GTP[(35)S] binding to G(i1)alpha/G(i2)alpha and G(o)alpha was also increased twofold in HEK-mu membranes over the control. Morphine further increased coupling to each of these Galpha proteins with similar potency, but not to G(q)/(11)alpha or G(s)alpha. These results indicate that the wild-type OP(3) can couple constitutively to endogenously expressed G(i3)alpha, G(i1)alpha/G(i2)alpha and G(o)alpha subunits of G-proteins in HEK-293 cells.
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Affiliation(s)
- N T Burford
- Department of Biopharmaceutical Sciences and Pharmaceutical Chemistry, School of Pharmacy, Box 0446, University of California, San Francisco, CA 94143-0446, USA
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18
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Abstract
Previous studies have shown that the agonist [D-Ala2, N-Me-Phe4, Gly-ol5]enkephalin (DAMGO) but not morphine induces mu-opioid receptor internalization [Arden, J.R., Segredo, V., Wang, Z., Lameh, J., Sadee, W., 1995. J. Neurochem. 65, 1636-1645]. In the present study we investigated the relationship between internalization of the mu-opioid receptor and the specific G proteins activated following treatment with morphine, DAMGO and endomorphin I (Tyr-Pro-Trp-Phe-NH2) (a putative endogenous mu-opioid receptor agonist) in human embryonic kidney (HEK) cells. Endomorphin I and DAMGO, but not morphine, caused mu-opioid receptor internalization. Morphine, DAMGO and endomorphin I each activated Gi1 alpha/Gi2 alpha, Go alpha and Gi3 alpha to a similar extent, but not Gq alpha/G11 alpha or Gs alpha in HEK membranes. Therefore, the three ligands tested differed in their ability to internalize mu-opioid receptors even though they were similar in activating individual G proteins.
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Affiliation(s)
- N T Burford
- Department of Biopharmaceutical Sciences and Pharmaceutical Chemistry, University of California, San Francisco 94143-0446, USA.
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19
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Abstract
Internalization and recycling of G protein-coupled receptors (GPCRs), such as the mu-opioid receptor, largely depend on agonist stimulation, whereas certain other receptor types recycle constitutively, e.g., the transferrin receptor. To investigate structural domains involved in mu-opioid receptor internalization, we constructed two truncation mutants bracketing a Ser/Thr-rich domain (354ThrSerSerThrIleGluGlnGlnAsn362) unique to the C-terminus of the mu-opioid receptor (mutants Trunc354 and Trunc363). Ligand binding did not differ substantially, and G protein coupling was slightly lower for these mu-receptor constructs, in particular for Trunc363. To permit localization of the receptor by immunocytochemistry, an epitope tag was added to the N-terminus of the wild-type and mutant receptors. Both the wild-type mu-opioid receptor and Trunc363 resided largely at the plasma membrane and internalized into vesicles upon stimulation with the agonist [D-Ala2,N-Me-Phe4,Gly-ol5]-enkephalin. Internalization occurred into vesicles that contain transferrin receptors, as shown previously, as well as clathrin, but not caveolin. In contrast, even without any agonist present, Trunc354 colocalized in intracellular vesicles with clathrin and transferrin receptors, but not caveolin. On blocking internalization by hyperosmolar sucrose or acid treatment, Trunc354 translocated to the plasma membrane, indicating that the mutant internalized into clathrin-coated vesicles and recycled constitutively. Despite agonist-independent internalization of Trunc354, basal G protein coupling was not elevated, suggesting distinct mechanisms for coupling and internalization. Furthermore, a portion of the C-terminus, particularly the Ser/Thr domain, appears to suppress mu-receptor internalization, which can be overcome by agonist stimulation. These results demonstrate that a mutant GPCR can be constructed such that internalization, normally an agonist-dependent process, can occur spontaneously without concomitant G protein activation.
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MESH Headings
- Analgesics/pharmacology
- Analgesics, Opioid/pharmacology
- Animals
- Binding, Competitive/physiology
- Cells, Cultured
- Coated Vesicles/chemistry
- Coated Vesicles/metabolism
- Endocytosis/genetics
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-
- Enkephalins/pharmacology
- Epitopes/genetics
- Epitopes/metabolism
- Fluorescent Antibody Technique
- GTP-Binding Proteins/metabolism
- Humans
- Kidney/cytology
- Ligands
- Microscopy, Confocal
- Morphine/pharmacology
- Mutagenesis/physiology
- Rats
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/genetics
- Receptors, Opioid, mu/metabolism
- Receptors, Transferrin/metabolism
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Affiliation(s)
- V Segredo
- Department of Biopharmaceutical Sciences and Pharmaceutical Chemistry, University of California, San Francisco 94143-0446, U.S.A
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20
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Burford NT, Nahorski SR, Chung SK, Chang YT, Wilcox RA. Binding and activity of the nine possible regioisomers of myo-inositol tetrakisphosphate at the inositol 1,4,5-trisphosphate receptor. Cell Calcium 1997; 21:301-10. [PMID: 9160166 DOI: 10.1016/s0143-4160(97)90118-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
All 9 racemic regioisomers (15 enantiomerically) of myo-inositol tetrakisphosphates (IP4s): DL-Ins(1,2,4,5)P4 [A], DL-Ins(1,2,4,6)P4 [B], Ins(1,2,3,5)P4 [C], Ins(1,3,4,6)P4 [D], Ins(2,4,5,6)P4 [E], DL-Ins(1,3,4,5)P4 [F], DL-Ins(1,2,5,6)P4 [G], DL-Ins(1,2,3,4)P4 [H] and DL-Ins(1,4,5,6)P4 [I] [Chung S-K., Chang Y-T. Synthesis of all possible regioisomers of myo-inositol tetrakisphosphate. J Chem Soc Chem Commun 1995; 11-13] were investigated for their ability to bind to the D-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] receptor in bovine adrenal cortical membranes, and for their ability to mobilize 45Ca2+ from Ins(1,4,5)P3-sensitive Ca2+ stores in permeabilized Chinese hamster ovary (CHO) cells. DL-Ins(1,2,4,5)P4 (Ki = 11 nM) bound to Ins(1,4,5)P3 receptors with an affinity only 2-fold lower than Ins(1,4,5)P3 (Ki = 6 nM). Ins(1,2,3,5)P4, Ins(1,3,4,6)P4, Ins(2,4,5,6)P4, DL-Ins(1,3,4,5)P4, DL-Ins(1,2,3,4)P4 and DL-Ins(1,4,5,6)P4 bound with affinities of between 0.4-0.7 microM. DL-Ins(1,2,4,6)P4 and DL-Ins(1,2,5,6)P4 bound to the Ins(1,4,5)P3 receptor with low affinity (approximately 2-3 microM). All but one of the IP4s mediated release of 45Ca2+ from stores of permeabilized CHO cells with a similar rank order of potency as that for Ins(1,4,5)P3 receptor binding, being between 16-fold and 50-fold less potent at releasing 45Ca2+ compared with their apparent binding affinities to the Ins(1,4,5)P3 receptor. The notable exception was Ins(1,2,3,5)P4, which showed an approximately 200-fold lower potency compared with its affinity for the Ins(1,4,5)P3 receptor. Ins(1,2,3,5)P4 may be a useful lead compound for the rational design of novel synthetic Ins(1,4,5)P3 analogues possessing structure-activity profiles with relatively high binding affinity, but low intrinsic efficacy, and hence partial agonists and antagonists at the Ins(1,4,5)P3 receptor.
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Affiliation(s)
- N T Burford
- Department of Cell Physiology and Pharmacology, University of Leicester, UK
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21
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Abstract
Human m1 muscarinic acetylcholine receptor mutants were screened to determine receptor domains and cellular pathways relevant to down-regulation. Mutations in the second intracellular loop and the junctions of the third intracellular loop of the receptor, where a role for receptor activation or internalization had been previously demonstrated in HEK293 cells, were selected for this study. To assess receptor down-regulation, the m1 receptor mutants were transfected into Chinese hamster ovary cells. Because receptor internalization is expected to precede down-regulation, mutants displaying intact internalization were selected to permit interpretation of mutational effects on down-regulation alone. Four mutations were identified that specifically impaired down-regulation without altering receptor internalization: V127A, I211A, E360A, and K362A. The results define new receptor domains in the second intracellular loop and the junctions of the third intracellular loop that are involved in down-regulation. These same four mutants were also defective in signaling via the phospholipase C and the adenylyl cyclase pathways and in G protein activation, as measured by [35S]GTP gamma S binding. However, the level of second messenger stimulation correlated poorly with the extent of down-regulation. In summary, several mutations of the m1 receptor selectively affect down-regulation, demonstrating that internalization and down-regulation represent distinct events driven by different cellular mechanisms.
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Affiliation(s)
- M S Shockley
- Department of Biopharmaceutical Sciences, University of California at San Francisco 94143-0446, USA
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22
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Burford NT, Nahorski SR. Muscarinic m1 receptor-stimulated adenylate cyclase activity in Chinese hamster ovary cells is mediated by Gs alpha and is not a consequence of phosphoinositidase C activation. Biochem J 1996; 315 ( Pt 3):883-8. [PMID: 8645172 PMCID: PMC1217289 DOI: 10.1042/bj3150883] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The mechanism underlying muscarinic m1 receptor-mediated increases in adenosine 3',5'-cyclic monophosphate (cAMP) was investigated in Chinese hamster ovary (CHO) cells expressing human recombinant m1 muscarinic receptors (CHO-ml cells). Stimulation of CHO-ml cells with carbachol resulted in marked accumulation of Ins(1,4,5)P3 and cAMP, in an atropine-sensitive manner, with EC50 values (log M) of -5.16 +/- 0.06 and -3.93 +/- 0.07 respectively. Basal and agonist-stimulated cAMP accumulation were unaffected by a 5 min pretreatment with l microM phorbol 12,13-dibutyrate and were not attenuated by pertussis toxin (100 ng/ml, 20h). Agonist-stimulated cAMP accumulation was also observed in CHO-ml cell membranes incubated in a buffer containing 100 nM free Ca2+. Guanosine 5'- [gamma-thio]triphosphate (10 microM) potentiated agonist-stimulated cAMP accumulation in CHO-ml cell membranes, implicating a G-protein involvement in this response. Co-incubation of carbachol with forskolin (10 microM) produced a greater than additive accumulation of cAMP in CHO-ml cells. Furthermore, a C-terminal-directed anti-Gs alpha serum attenuated both carbachol-stimulated (in CHO-ml cell membranes) and isoprenaline-stimulated (in CHO-beta 2 cell membranes) cAMP accumulation with a similar dose-dependency. These results suggest that muscarinic agonist-stimulated cAMP accumulation in CHO-ml cells occurs via activation of Gs alpha and not as a consequence of phosphoinositidase C activation.
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Affiliation(s)
- N T Burford
- Department of Cell Physiology and Pharmacology, University of Leicester, U.K
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23
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Tobin AB, Willars GB, Burford NT, Nahorski SR. Relationship between agonist binding, phosphorylation and immunoprecipitation of the m3-muscarinic receptor, and second messenger responses. Br J Pharmacol 1995; 116:1723-8. [PMID: 8528551 PMCID: PMC1909083 DOI: 10.1111/j.1476-5381.1995.tb16654.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
1. Phosphoinositidase C-linked m3-muscarinic receptors expressed in Chinese hamster ovary cells (CHO-m3 cells) are phosphorylated on serine following agonist stimulation. 2. m3-Muscarinic receptor phosphorylation is concentration-dependent requiring a carbachol concentration of 13.2 microM for half maximal stimulation. 3. The phosphorylation concentration-response curve lies to the left of the curve for carbachol binding to muscarinic receptors (KD = 100 microM) in membranes from CHO-m3 cells. In contrast, receptor phosphorylation closely correlates with receptor-mediated phosphoinositidase C activation (EC50 for inositol 1,4,5 trisphosphate accumulation during the peak and plateau phases were 7.14 microM and 5.92 microM respectively) but not with rapid agonist-mediated calcium elevation (EC50 = 0.32 microM) measured in fura-2-AM loaded cells. 4. These data suggest a dissociation of receptor phosphorylation from agonist occupation. Such an apparent 'receptor reserve' for m3-muscarinic receptor phosphorylation may be indicative of a mechanism that is dependent on a small amplification of the receptor signal, though probably dissociated from the calcium signal.
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Affiliation(s)
- A B Tobin
- Leicester University, Dept. Of Cell Physiology and Pharmacology
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24
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Burford NT, Tobin AB, Nahorski SR. Differential coupling of m1, m2 and m3 muscarinic receptor subtypes to inositol 1,4,5-trisphosphate and adenosine 3',5'-cyclic monophosphate accumulation in Chinese hamster ovary cells. J Pharmacol Exp Ther 1995; 274:134-42. [PMID: 7616390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Agonist-stimulated accumulation of inositol 1,4,5-trisphosphate and adenosine 3',5'-cyclic monophosphate (cAMP) were measured in Chinese hamster ovary (CHO) cells expressing m1 (CHO-m1), m2 (CHO-m2) or m3 (CHO-m3) muscarinic receptors. At similar levels of expression (approximately 1000 fmol of receptor per mg of protein), m1 and m3 muscarinic receptors mediated similar carbachol-stimulated, biphasic accumulation of inositol-1,4,5-trisphosphate in intact cells and similar release of preloaded 45Ca++ from permeabilized cells. However, CHO-m1 cells produced a 4-fold greater agonist-stimulated accumulation of cAMP compared with CHO-m3 cells, in a pertussis toxin-insensitive manner. CHO-m2 cells (expressing approximately 100 fmol of receptor per mg of protein) coupled to the inhibition of adenylyl cyclase in a pertussis toxin-sensitive manner. However, after pertussis toxin pretreatment, agonist stimulation mediated a 50% potentiation of forskolin-stimulated cAMP accumulation. Muscarinic m1, m2 and m3 receptor-mediated stimulation of cAMP accumulation, correlated with the apparent binding affinity of carbachol for these receptors, suggesting a lack of an apparent receptor reserve for this response. Reducing the level of m3 muscarinic receptors by approximately 50% resulted in no detectable stimulation of cAMP accumulation. The results suggest that m1 and m3 muscarinic receptors, expressed at similar levels in CHO cells, couple to the activation of phospholipase C with similar efficiency. However, m1 muscarinic receptors couple with greater efficiency to the stimulation of adenylyl cyclase compared with m3 muscarinic receptors. Muscarinic m1, m2 and m3 receptor-mediated cAMP accumulation in CHO cells does not appear to be a consequence of phospholipase C activation.
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Affiliation(s)
- N T Burford
- Department of Cell Physiology and Pharmacology, University of Leicester, United Kingdom
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25
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Burford NT, Tobin AB, Nahorski SR. Coupling of muscarinic m1, m2 and m3 acetylcholine receptors, expressed in Chinese hamster ovary cells, to pertussis toxin-sensitive/insensitive guanine nucleotide-binding proteins. Eur J Pharmacol 1995; 289:343-51. [PMID: 7621908 DOI: 10.1016/0922-4106(95)90112-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Chinese hamster ovary (CHO) cells expressing recombinant human m1 (CHO-m1 cells), m2 (CHO-m2 cells), or m3 (CHO-m3 cells) muscarinic receptors were characterised pharmacologically with [3H]N-methylscopolamine. Agonist-stimulated coupling of these receptors with guanine nucleotide-binding proteins (G proteins) was measured by guanine nucleotide- and pertussis toxin-modification of carbachol competition-binding curves, and pertussis toxin-sensitivity of agonist-stimulated [35S]guanosine 5'-O-(3-thiotriphosphate) ([35S]GTP gamma S) binding, in membrane preparations of the CHO cell clones. High affinity agonist binding and agonist-stimulated [35S]GTP gamma S binding was abolished in CHO-m2 cell membranes (expressing 99 +/- 25 fmol of [3H]N-methylscopolamine binding sites/mg protein) after pertussis toxin pretreatment of cells, suggesting that muscarinic m2 receptors expressed in these cell membranes couple predominantly with pertussis toxin-sensitive G proteins. CHO-m1 (713 +/- 102 fmol/mg protein) and CHO-m3 (1212 +/- 279 fmol/mg protein) cell membranes produced smaller elevations in agonist-stimulated [35S]GTP gamma S binding considering the higher receptor levels, compared with CHO-m2 cell membranes. Pertussis toxin pretreatment of these clones also resulted in a significant attenuation of agonist-stimulated [35S]GTP gamma S binding suggesting that, under these experimental conditions, muscarinic m1 and m3 receptors can couple with both pertussis toxin-sensitive and pertussis toxin-insensitive G proteins. Guanine nucleotide-modification of agonist binding in CHO-m1 and CHO-m3 cell membranes was comparatively smaller than in CHO-m2 cell membranes.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- N T Burford
- Department of Cell Physiology and Pharmacology, University of Leicester, UK
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26
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Affiliation(s)
- D G Lambert
- Department of Pharmacology and Therapeutics, University of Leicester, U.K
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