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Rahman SN, Imhaouran F, Leurs R, Christopoulos A, Valant C, Langmead CJ. Ligand-directed biased agonism at human histamine H 3 receptor isoforms across Gα i/o- and β-arrestin2-mediated pathways. Biochem Pharmacol 2023:115988. [PMID: 38159685 DOI: 10.1016/j.bcp.2023.115988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 12/13/2023] [Accepted: 12/15/2023] [Indexed: 01/03/2024]
Abstract
The histamine H3 receptor (H3R) is a neurotransmitter receptor that is primarily found in the brain, where it controls the release and synthesis of histamine, as well as the release of other neurotransmitters (e.g. dopamine, serotonin). Notably, 20 H3R isoforms are differentially expressed in the human brain as a consequence of alternative gene splicing. The hH3R-445, -415, -365 and -329 isoforms contain the prototypical GPCR (7TM) structure, yet exhibit deletions in the third intracellular loop, a structural domain that is pivotal for G protein-coupling, signaling and regulation. To date, the physiological relevance underlying the individual and combinatorial function of hH3R isoforms remains poorly understood. Nevertheless, given their significant implication in physiological processes (e.g. cognition, homeostasis) and neurological disorders (e.g. Alzheimer's and Parkinson's disease, schizophrenia), widespread targeting of hH3R isoforms by drugs may lead to on-target side effects in brain regions that are unaffected by disease. To this end, isoform- and/or pathway-selective targeting of hH3R isoforms by biased agonists could be of therapeutic relevance for the development of region- and disease-specific drugs. Hence, we have evaluated ligand biased signaling at the hH3R-445, -415, -365 and -329 isoforms across various Gαi/o-mediated (i.e. [35S]GTPγS accumulation, cAMP inhibition, pERK1/2 activation, pAKT T308/S473 activation) and non Gαi/o-mediated (i.e. β-arrestin2 recruitment) endpoints that are relevant to neurological diseases. Our findings indicate that H3R agonists display significantly altered patterns in their degree of ligand bias, in a pathway- and isoform-dependent manner, underlining the significance to investigate GPCRs with multiple isoforms to improve development of selective drugs. SUBJECT CATEGORY: Neuropharmacology.
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Affiliation(s)
- Sabrina N Rahman
- Drug Discovery Biology and Neuromedicines Discovery Centre, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, 3052 VIC, Parkville, Melbourne, Australia; Amsterdam Institute for Molecular Life Sciences, Division of Medicinal Chemistry, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands.
| | - Faissal Imhaouran
- Amsterdam Institute for Molecular Life Sciences, Division of Medicinal Chemistry, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands
| | - Rob Leurs
- Amsterdam Institute for Molecular Life Sciences, Division of Medicinal Chemistry, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands
| | - Arthur Christopoulos
- Drug Discovery Biology and Neuromedicines Discovery Centre, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, 3052 VIC, Parkville, Melbourne, Australia
| | - Céline Valant
- Drug Discovery Biology and Neuromedicines Discovery Centre, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, 3052 VIC, Parkville, Melbourne, Australia.
| | - Christopher J Langmead
- Drug Discovery Biology and Neuromedicines Discovery Centre, Monash Institute of Pharmaceutical Sciences, Monash University, 399 Royal Parade, 3052 VIC, Parkville, Melbourne, Australia.
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Lyons EL, Leone-Kabler S, Kovach AL, Thomas BF, Howlett AC. Cannabinoid receptor subtype influence on neuritogenesis in human SH-SY5Y cells. Mol Cell Neurosci 2020; 109:103566. [PMID: 33049367 DOI: 10.1016/j.mcn.2020.103566] [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: 07/26/2019] [Revised: 10/01/2020] [Accepted: 10/06/2020] [Indexed: 10/23/2022] Open
Abstract
Human SH-SY5Y neuroblastoma cells stably expressing exogenous CB1 (CB1XS) or CB2 (CB2XS) receptors were developed to investigate endocannabinoid signaling in the extension of neuronal projections. Expression of cannabinoid receptors did not alter proliferation rate, viability, or apoptosis relative to parental SH-SY5Y. Transcripts for endogenous cannabinoid system enzymes (diacylglycerol lipase, monoacylglycerol lipase, α/β-hydrolase domain containing proteins 6 and 12, N-acyl phosphatidylethanolamine-phospholipase D, and fatty acid amide hydrolase) were not altered by CB1 or CB2 expression. Endocannabinoid ligands 2-arachidonoylglycerol (2-AG) and anandamide were quantitated in SH-SY5Y cells, and diacylglycerol lipase inhibitor tetrahydrolipstatin decreased 2-AG abundance by 90% but did not alter anandamide abundance. M3 muscarinic agonist oxotremorine M, and inhibitors of monoacylglycerol lipase and α/β hydrolase domain containing proteins 6 &12 increased 2-AG abundance. CB1 receptor expression increased lengths of short (<30 μm) and long (>30 μm) projections, and this effect was significantly reduced by tetrahydrolipstatin, indicative of stimulation by endogenously produced 2-AG. Pertussis toxin, Gβγ inhibitor gallein, and β-arrestin inhibitor barbadin did not significantly alter long projection length in CB1XS, but significantly reduced short projections, with gallein having the greatest inhibition. The rho kinase inhibitor Y27632 increased CB1 receptor-mediated long projection extension, indicative of actin cytoskeleton involvement. CB1 receptor expression increased GAP43 and ST8SIA2 mRNA and decreased ITGA1 mRNA, whereas CB2 receptor expression increased NCAM and SYT mRNA. We propose that basal endogenous production of 2-AG provides autocrine stimulation of CB1 receptor signaling through Gi/o, Gβγ, and β-arrestin mechanisms to promote neuritogenesis, and rho kinase influences process extension.
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Affiliation(s)
- Erica L Lyons
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, One Medical Center Blvd., Winston-Salem, NC 27157, USA.
| | - Sandra Leone-Kabler
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, One Medical Center Blvd., Winston-Salem, NC 27157, USA.
| | - Alexander L Kovach
- Discovery Sciences, RTI International, PO Box 12194, Research Triangle Park, NC 27709, USA.
| | - Brian F Thomas
- Discovery Sciences, RTI International, PO Box 12194, Research Triangle Park, NC 27709, USA.
| | - Allyn C Howlett
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, One Medical Center Blvd., Winston-Salem, NC 27157, USA.
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Gozé C, Bergé G, M'Kadmi C, Floquet N, Gagne D, Galleyrand JC, Fehrentz JA, Martinez J. Involvement of tryptophan W276 and of two surrounding amino acid residues in the high constitutive activity of the ghrelin receptor GHS-R1a. Eur J Pharmacol 2010; 643:153-61. [PMID: 20599926 DOI: 10.1016/j.ejphar.2010.06.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 06/07/2010] [Accepted: 06/10/2010] [Indexed: 10/19/2022]
Abstract
The human ghrelin receptor (GHS-R1a) is known to display a high level of signaling in the absence of ligand. The Trp276, located in the fully conserved CWXP motif of G protein-coupled receptors, is believed to function as a rotameric switch in these receptors. A comparative modelling of GHS-R1a with the motilin receptor, the most related G protein-coupled receptor to GHS-R1a known to date, but characterized by a very low ligand-independent signaling level, revealed that only two surrounding residues of Trp276, that are Val131 and Ile134, were different from these receptors. We mutated them at once in GHS-R1a to create a "motilin receptor-like" environment of Trp276 in order to study the consequences on GHS-R1a activation. We studied the pharmacological properties of the W276A, V131L-I134M GHS-R1a mutants. Basal as well as maximal ghrelin-induced signaling was assessed both by inositol-phosphate accumulation and SRE pathways. As compared to the wild type receptor, the SRE-luciferase assay displayed a markedly impaired basal activity for W276A whereas that of V131L-I134M was, strikingly, two fold increased. Nevertheless, the efficacy of ghrelin to bind or to stimulate mutant receptors remained unchanged. It is concluded that Trp276, Val131 and Ile134 have a significant impact on constitutive signaling of GHS-R1a, V131L-I134M being the first example of a GHS-R1a mutant with a higher basal activity than the wild type receptor.
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Affiliation(s)
- Catherine Gozé
- Institut des Biomolécules Max Mousseron, UMR, CNRS, Universités Montpellier, France.
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Modulation of interleukin signalling and gene expression in cardiac myocytes by endothelin-1. Int J Biochem Cell Biol 2009; 42:263-72. [PMID: 19861169 DOI: 10.1016/j.biocel.2009.10.021] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Revised: 10/14/2009] [Accepted: 10/16/2009] [Indexed: 12/26/2022]
Abstract
The related inflammatory cytokines, interleukin- (IL-) 1beta and IL-33, are both implicated in the response of the heart to injury. They also activate mitogen-activated protein kinases (MAPKs) in cardiac myocytes. The hypertrophic Gq protein-coupled receptor agonist endothelin-1 is a potentially cardioprotective peptide and may modulate the inflammatory response. Endothelin-1 also stimulates (MAPKs) in cardiac myocytes and promotes rapid changes in expression of mRNAs encoding intercellular and intracellular signalling components including receptors for IL-33 (ST2) and phosphoprotein phosphatases. Prior exposure to endothelin-1 may specifically modulate the response to IL-33 and, more globally, influence MAPK activation by different stimuli. Neonatal rat ventricular myocytes were exposed to IL-1beta or IL-33 with or without pre-exposure to endothelin-1 (5h) and MAPK activation assessed. IL-33 activated ERK1/2, JNKs and p38-MAPK, but to a lesser degree than IL-1beta. Endothelin-1 increased expression of soluble IL-33 receptors (sST2 receptors) which may prevent binding of IL-33 to the cell-surface receptors. However, pretreatment with endothelin-1 only inhibited activation of p38-MAPK by IL-33 with no significant influence on ERK1/2 and a small increase in activation of JNKs. Inhibition of p38-MAPK signalling following pretreatment with endothelin-1 was also detected with IL-1beta, H(2)O(2) or tumour necrosis factor alpha (TNFalpha) indicating an effect intrinsic to the signalling pathway. Endothelin-1 pretreatment suppressed the increase in expression of IL-6 mRNA induced by IL-1beta and decreased the duration of expression of TNFalpha mRNA. Coupled with the general decrease in p38-MAPK signalling, we conclude that endothelin-1 attenuates the cardiac myocyte inflammatory response, potentially to confer cardioprotection.
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Cao X, Qin J, Xie Y, Khan O, Dowd F, Scofield M, Lin MF, Tu Y. Regulator of G-protein signaling 2 (RGS2) inhibits androgen-independent activation of androgen receptor in prostate cancer cells. Oncogene 2006; 25:3719-34. [PMID: 16449965 DOI: 10.1038/sj.onc.1209408] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Hormones acting through G protein-coupled receptors (GPCRs) can cause androgen-independent activation of androgen receptor (AR) in prostate cancer cells. Regulators of G-protein signaling (RGS) proteins, through their GTPase activating protein (GAP) activities, inhibit GPCR-mediated signaling by inactivating G proteins. Here, we identified RGS2 as a gene specifically downregulated in androgen-independent prostate cancer cells. Expression of RGS2, but not other RGS proteins, abolished androgen-independent AR activity in androgen-independent LNCaP cells and CWR22Rv1 cells. In LNCaP cells, RGS2 inhibited G(q)-coupled GPCR signaling. Expression of exogenous wild-type RGS2, but not its GAP-deficient mutant, significantly reduced AR activation by constitutively activated G(q)Q209L mutant whereas silencing endogenous RGS2 by siRNA enhanced G(q)Q209L-stimulated AR activity. RGS2 had no effect on RGS-insensitive G(q)Q209L/G188S-induced AR activation. Furthermore, extracellular signal-regulated kinase 1/2 (ERK1/2) was found to be involved in RGS2-mediated regulation of androgen-independent AR activity. In addition, RGS2 functioned as a growth suppressor for androgen-independent LNCaP cells whereas androgen-sensitive LNCaP cells with RGS2 silencing had a growth advantage under steroid-reduced conditions. Finally, RGS2 expression level was significantly decreased in human prostate tumor specimens. Taken together, our results suggest RGS2 as a novel regulator of AR signaling and its repression may be an important step during prostate tumorigenesis and progression.
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Affiliation(s)
- X Cao
- Department of Pharmacology, Creighton University School of Medicine, Omaha, NE 68178, USA
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Krysan K, Reckamp KL, Dalwadi H, Sharma S, Rozengurt E, Dohadwala M, Dubinett SM. Prostaglandin E2 Activates Mitogen-Activated Protein Kinase/Erk Pathway Signaling and Cell Proliferation in Non–Small Cell Lung Cancer Cells in an Epidermal Growth Factor Receptor–Independent Manner. Cancer Res 2005; 65:6275-81. [PMID: 16024629 DOI: 10.1158/0008-5472.can-05-0216] [Citation(s) in RCA: 190] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cyclooxygenase 2 (COX-2) overexpression is found in a wide variety of human cancers and is linked to all stages of tumorigenesis. Elevated tumor COX-2 expression is associated with increased angiogenesis, tumor invasion, suppression of host immunity and promotes tumor cell resistance to apoptosis. Previous reports have linked the COX-2 product prostaglandin E2 (PGE2) to the abnormal activation of the mitogen-activated protein kinase/Erk kinase pathway. Here we show that PGE2 is able to rapidly stimulate Erk phosphorylation in a subset of non-small cell lung cancer (NSCLC) cell lines. This effect is not evident in bronchial epithelial cells. In contrast to previous reports in colon cancer, we found that Erk activation as well as cellular proliferation induced by PGE2 was not inhibited by pretreatment of the cells with epidermal growth factor receptor (EGFR) inhibitors. Activation of the Erk pathway by PGE2 was also resistant to src kinase inhibitors but sensitive to the protein kinase C inhibition. PGE2 effects are mediated through four G protein-coupled receptors. Selective inhibition of EP receptors revealed the possible involvement of Ca2+-dependent signaling in PGE2-mediated activation of Erk. Our data indicate the presence of an EGFR-independent activation of the mitogen-activated protein kinase/Erk pathway by PGE2 in NSCLC cells. These findings provide evidence for the possible link between tumor COX-2 overexpression and elevated Erk-mediated cancer cell proliferation and migration. Importantly, these findings suggest that COX-2 overexpression may contribute to EGFR inhibitor resistance in NSCLC.
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Affiliation(s)
- Kostyantyn Krysan
- UCLA Lung Cancer Research Program of Jonsson Comprehensive Cancer Center, David Geffen School of Medicine at UCLA, Los Angeles, California 90095-1690, USA
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Powell CS, Wright MM, Jackson RM. p38mapk and MEK1/2 inhibition contribute to cellular oxidant injury after hypoxia. Am J Physiol Lung Cell Mol Physiol 2003; 286:L826-33. [PMID: 14672918 DOI: 10.1152/ajplung.00119.2003] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Lung epithelial cells produce increased reactive oxygen species (ROS) after hypoxia exposure, and they are more susceptible after hypoxia to injury by agents that generate superoxide [O2-; e.g., 2,3-dimethoxy-1,4-naphthoquinone (DMNQ)]. Cellular GSH and MnSOD both decrease in hypoxic lung epithelial cells, altering the redox state. Because ROS participate in signaling pathways involved in cell death or survival, we tested the hypothesis that mitogen-activated protein kinases (MAPK) were involved in a protective response against cellular injury during reoxygenation. Human lung epithelial A549 cells were incubated in hypoxia (<1% O2 for 24 h) and then reoxygenated by return to air. p38mapk and MKK3 phosphorylation both decreased after hypoxia. During reoxygenation, cells were incubated with DMNQ (0-50 microM), a redox cycling quinone that produces O2-. Hypoxia preexposure significantly increased epithelial cell lysis resulting from DMNQ. Addition of the p38mapk inhibitors SB-202190 or SB-203580 markedly increased cytotoxicity, as did the mitogen/extracellular signal-regulated kinase (MEK) 1/2 inhibitor PD-98059 (all 10 microM), suggesting a protective effect of downstream molecules activated by the kinases. Transfection of A549 cells with a dominant active MKK3 plasmid (MKK3[Glu]) partially inhibited cytolysis resulting from DMNQ, whereas the inactive MKK3 plasmid (MKK3[Ala]) had less evident protective effects. Stress-related signaling pathways in epithelial cells are modulated by hypoxia and confer protection from reoxygenation, since hypoxia and chemical inhibition of p38mapk and MEK1/2 similarly increase cytolysis resulting from O2-.
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Affiliation(s)
- Charles S Powell
- Research Service, VAMC (151 1201 NW 16(th) St., Miami, FL 33125-1693, USA
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García‐García E, Rosales C. Signal transduction during Fc receptor‐mediated phagocytosis. J Leukoc Biol 2002. [DOI: 10.1189/jlb.72.6.1092] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Erick García‐García
- Immunology Department, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City
| | - Carlos Rosales
- Immunology Department, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City
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Lefkowitz RJ, Pierce KL, Luttrell LM. Dancing with different partners: protein kinase a phosphorylation of seven membrane-spanning receptors regulates their G protein-coupling specificity. Mol Pharmacol 2002; 62:971-4. [PMID: 12391258 DOI: 10.1124/mol.62.5.971] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Robert J Lefkowitz
- Department of Medicine, Howard Hughes Medical Institute, Duke University Medical Center, Durham, North Carolina 27710, USA.
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Abstract
Calcium is a universal intracellular signal that is responsible for controlling a plethora of cellular processes. Understanding how such a simple ion can regulate so many diverse cellular processes is a key goal of calcium- and cell-biologists. One molecule that is sensitive to changes in intracellular calcium levels is Ras. This small GTPase operates as a binary molecular switch, and regulates cell proliferation and differentiation. Here, we focus on examining the link between calcium and Ras signalling and, in particular, we speculate as to how the complexity of calcium signalling could regulate Ras activity.
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Affiliation(s)
- Peter J Cullen
- The Henry Wellcome Laboratories for Integrated Cell Signalling, Department of Biochemistry, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, UK.
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Schwindinger WF, Robishaw JD. Heterotrimeric G-protein betagamma-dimers in growth and differentiation. Oncogene 2001; 20:1653-60. [PMID: 11313913 DOI: 10.1038/sj.onc.1204181] [Citation(s) in RCA: 161] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Heterotrimeric G-proteins are components of the signal transduction pathways for the soluble and cell-contact signals that regulate normal growth and differentiation. There is now a greater appreciation of the role of the Gbetagamma-dimer in the regulation of a variety of intracellular effectors, including ion channels, adenylyl cyclase, and phospholipase Cbeta. In many cases, Gbetagamma-dimers are required for the activation of mitogen activated protein kinase (MAPK) pathways that promote cellular proliferation, although the underlying mechanisms have yet to be fully elucidated. Activation of phosphotidylinositol-3-kinase (PI3K) is a critical step in the intracellular transduction of survival signals. Gbetagamma-dimers directly activate PI3Kgamma as well as the more widely distributed PI3Kbeta. The activation of PI3Kgamma by Gbetagamma-dimers likely involves direct binding of specific Gbetagamma-dimers to both subunits of PI3Kgamma. Thus, Gbetagamma-dimers transmit signals from numerous receptors to a variety of intracellular effectors in distinct cellular contexts. Five distinct Gbeta-subunits and 12 distinct Ggamma-subunits have been identified. New experimental approaches are needed to elucidate the specific roles of individual Gbetagamma-dimers in the pathways that transduce signals for proliferation and survival.
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Affiliation(s)
- W F Schwindinger
- Weis Center for Research, Geisinger Clinic, 100 North Academy Avenue, Danville, PA 17822, USA
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