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Gaborit M, Massotte D. Therapeutic potential of opioid receptor heteromers in chronic pain and associated comorbidities. Br J Pharmacol 2023; 180:994-1013. [PMID: 34883528 DOI: 10.1111/bph.15772] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [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: 02/28/2021] [Revised: 06/07/2021] [Accepted: 07/21/2021] [Indexed: 11/27/2022] Open
Abstract
Chronic pain affects 20% to 45% of the global population and is often associated with the development of anxio-depressive disorders. Treatment of this debilitating condition remains particularly challenging with opioids prescribed to alleviate moderate to severe pain. However, despite strong antinociceptive properties, numerous adverse effects limit opioid use in the clinic. Moreover, opioid misuse and abuse have become a major health concern worldwide. This prompted efforts to design original strategies that would efficiently and safely relieve pain. Targeting of opioid receptor heteromers is one of these. This review summarizes our current knowledge on the role of heteromers involving opioid receptors in the context of chronic pain and anxio-depressive comorbidities. It also examines how heteromerization in native tissue affects ligand binding, receptor signalling and trafficking properties. Finally, the therapeutic potential of ligands designed to specifically target opioid receptor heteromers is considered. LINKED ARTICLES: This article is part of a themed issue on Advances in Opioid Pharmacology at the Time of the Opioid Epidemic. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v180.7/issuetoc.
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Affiliation(s)
- Marion Gaborit
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
| | - Dominique Massotte
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
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2
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Eslami M, Willen D, Papasouliotis O, Schuepbach-Mallpell S, Willen L, Donzé O, Yalkinoglu Ö, Schneider P. Kinetics of free and ligand-bound atacicept in human serum. Front Immunol 2022; 13:1035556. [PMID: 36532058 PMCID: PMC9756848 DOI: 10.3389/fimmu.2022.1035556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 11/07/2022] [Indexed: 12/03/2022] Open
Abstract
BAFF (B cell activation factor of the TNF family/B lymphocyte stimulator, BLyS) and APRIL (a proliferation-inducing ligand) are targeted by atacicept, a decoy receptor consisting of the extracellular domain of TACI (transmembrane activator and calcium-modulator and cyclophilin (CAML) interactor) fused to the Fc portion of human IgG1. The purpose of the study was to characterize free and ligand-bound atacicept in humans. Total and active atacicept in serum of healthy volunteers receiving a single dose of subcutaneous atacicept or in patients treated weekly for one year were measured by ELISA, Western blot, or cell-based assays. Pharmacokinetics of free and bound atacicept were predicted based on total atacicept ELISA results. Persistence of complexes of purified atacicept bound to recombinant ligands was also monitored in mice. Results show that unbound or active atacicept in human serum exceeded 0.1 µg/ml for one week post administration, or throughout a 1-year treatment with weekly administrations. After a single administration of atacicept, endogenous BAFF bound to atacicept was detected after 8 h then increased about 100-fold within 2 to 4 weeks. Endogenous heteromers of BAFF and APRIL bound to atacicept also accumulated, but atacicept-APRIL complexes were not detected. In mice receiving intravenous injections of purified complexes pre-formed in vitro, atacicept-BAFF persisted longer (more than a week) than atacicept-APRIL (less than a day). Thus, only biologically inactive BAFF and BAFF-APRIL heteromers accumulate on atacicept in vivo. The measure of active atacicept provides further support for the once-weekly dosing regimen implemented in the clinical development of atacicept.
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Affiliation(s)
- Mahya Eslami
- Department of Immunobiology, University of Lausanne, Epalinges, Switzerland
| | - Daniela Willen
- Clinical Pharmacology, Translational Medicine, Merck Healthcare KGaA, Darmstadt, Germany
| | - Orestis Papasouliotis
- Translational Medicine, Merck Institute for Pharmacometrics (an affiliate of Merck KGaA), Lausanne, Switzerland
| | | | - Laure Willen
- Department of Immunobiology, University of Lausanne, Epalinges, Switzerland
| | | | - Özkan Yalkinoglu
- Clinical Pharmacology, Translational Medicine, Merck Healthcare KGaA, Darmstadt, Germany
| | - Pascal Schneider
- Department of Immunobiology, University of Lausanne, Epalinges, Switzerland,*Correspondence: Pascal Schneider,
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Toniolo EF, Gupta A, Franciosi AC, Gomes I, Devi LA, Dale CS. Interactions between cannabinoid and opioid receptors in a mouse model of diabetic neuropathy. Pain 2022; 163:1414-1423. [PMID: 34724682 PMCID: PMC9043031 DOI: 10.1097/j.pain.0000000000002527] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 10/19/2021] [Indexed: 11/25/2022]
Abstract
ABSTRACT Diabetic neuropathy, often associated with diabetes mellitus, is a painful condition with no known effective treatment except glycemic control. Studies with neuropathic pain models report alterations in cannabinoid and opioid receptor expression levels; receptors whose activation induces analgesia. We examined whether interactions between CB1R and opioid receptors could be targeted for the treatment of diabetic neuropathy. For this, we generated antibodies that selectively recognize native CB1R-MOR and CB1R-DOR heteromers using a subtractive immunization strategy. We assessed the levels of CB1R, MOR, DOR, and interacting complexes using a model of streptozotocin-induced diabetic neuropathy and detected increased levels of CB1R, MOR, DOR, and CB1R-MOR complexes compared with those in controls. An examination of G-protein signaling revealed that activity induced by the MOR, but not the DOR agonist, was potentiated by low nanomolar doses of CB1R ligands, including antagonists, suggesting an allosteric modulation of MOR signaling by CB1R ligands within CB1R-MOR complexes. Because the peptide endocannabinoid, hemopressin, caused a significant potentiation of MOR activity, we examined its effect on mechanical allodynia and found that it blocked allodynia in wild-type mice and mice with diabetic neuropathy lacking DOR (but have CB1R-MOR complexes). However, hemopressin does not alter the levels of CB1R-MOR complexes in diabetic mice lacking DOR but increases the levels of CB1R-DOR complexes in diabetic mice lacking MOR. Together, these results suggest the involvement of CB1R-MOR and CB1R-DOR complexes in diabetic neuropathy and that hemopressin could be developed as a potential therapeutic for the treatment of this painful condition.
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Affiliation(s)
- Elaine F. Toniolo
- Department of Pharmacology, University of Sao Paulo, Sao Paulo, Brazil
- Department of Anatomy, Laboratory of Neuromodulation and Experimental Pain, University of Sao Paulo, Sao Paulo, Brazil
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- Hospital Sírio-Libanês, São Paulo, Brasil
| | - Achla Gupta
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Adriano C. Franciosi
- Department of Pharmacology, University of Sao Paulo, Sao Paulo, Brazil
- Department of Anatomy, Laboratory of Neuromodulation and Experimental Pain, University of Sao Paulo, Sao Paulo, Brazil
- Hospital Sírio-Libanês, São Paulo, Brasil
| | - Ivone Gomes
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Lakshmi A. Devi
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Camila S. Dale
- Department of Anatomy, Laboratory of Neuromodulation and Experimental Pain, University of Sao Paulo, Sao Paulo, Brazil
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Williams OOF, Coppolino M, George SR, Perreault ML. Sex Differences in Dopamine Receptors and Relevance to Neuropsychiatric Disorders. Brain Sci 2021; 11:1199. [PMID: 34573220 DOI: 10.3390/brainsci11091199] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 09/03/2021] [Accepted: 09/09/2021] [Indexed: 02/06/2023] Open
Abstract
Dopamine is an important neurotransmitter that plays a key role in neuropsychiatric illness. Sex differences in dopaminergic signaling have been acknowledged for decades and have been linked to sex-specific heterogeneity in both dopamine-related behaviours as well as in various neuropsychiatric disorders. However, the overall number of studies that have evaluated sex differences in dopamine signaling, both in health and in these disorders, is low. This review will bring together what is known regarding sex differences in innate dopamine receptor expression and function, as well as highlight the known sex-specific roles of dopamine in addiction, depression, anxiety, schizophrenia, and attention deficit hyperactivity disorder. Due to differences in prognosis, diagnosis, and symptomatology between male and female subjects in disorders that involve dopamine signaling, or in responses that utilize pharmacological interventions that target dopamine receptors, understanding the fundamental sex differences in dopamine receptors is of vital importance for the personalization of therapeutic treatment strategies.
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Favaroni A, Hegemann JH. Chlamydia trachomatis Polymorphic Membrane Proteins (Pmps) Form Functional Homomeric and Heteromeric Oligomers. Front Microbiol 2021; 12:709724. [PMID: 34349750 PMCID: PMC8326573 DOI: 10.3389/fmicb.2021.709724] [Citation(s) in RCA: 2] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 06/24/2021] [Indexed: 11/13/2022] Open
Abstract
Chlamydiae are Gram-negative, obligate intracellular bacteria, which infect animals and humans. Adhesion to host cells, the first step in the infection process, is mediated by polymorphic membrane proteins (Pmps). Pmps constitute the largest chlamydial protein family, with 9 members (subdivided into six subtypes) in C. trachomatis and 21 in C. pneumoniae, and are characterized by the presence of multiple copies of GGA(I,L,V) and FxxN motifs. Motif-rich fragments of all nine C. trachomatis Pmps act as adhesins and are essential for infection. As autotransporters, most Pmp proteins are secreted through their β-barrel domain and localize on the surface of the chlamydial cell, where most of them are proteolytically processed. Classical autotransporters are monomeric proteins, which can function as toxins, proteases, lipases and monoadhesive adhesins. Here we show that selected recombinant C. trachomatis Pmp fragments form functional adhesion-competent multimers. They assemble into homomeric and heteromeric filaments, as revealed by non-denaturing gel electrophoresis, size-exclusion chromatography and electron microscopy. Heteromeric filaments reach 2 μm in length, significantly longer than homomeric structures. Filament formation was independent of the number of motifs present in the fragment(s) concerned and their relative affinity for host cells. Our functional studies demonstrated that only adhesion-competent oligomers were able to block a subsequent infection. Pre-loading of infectious chlamydial cells with adhesion-competent Pmp oligomers maintained the subsequent infection, while adhesion-incompetent structures reduced infectivity, presumably by blocking the function of endogenous Pmps. The very large number of possible heteromeric and homomeric Pmp complexes represents a novel mechanism to ensure stable adhesion and possibly host cell immune escape.
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Affiliation(s)
- Alison Favaroni
- Institute of Functional Microbial Genomics, Heinrich-Heine-University, Duesseldorf, Germany
| | - Johannes H Hegemann
- Institute of Functional Microbial Genomics, Heinrich-Heine-University, Duesseldorf, Germany
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Prasad K, de Vries EFJ, Elsinga PH, Dierckx RAJO, van Waarde A. Allosteric Interactions between Adenosine A 2A and Dopamine D 2 Receptors in Heteromeric Complexes: Biochemical and Pharmacological Characteristics, and Opportunities for PET Imaging. Int J Mol Sci 2021; 22:ijms22041719. [PMID: 33572077 PMCID: PMC7915359 DOI: 10.3390/ijms22041719] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 02/02/2021] [Accepted: 02/03/2021] [Indexed: 12/17/2022] Open
Abstract
Adenosine and dopamine interact antagonistically in living mammals. These interactions are mediated via adenosine A2A and dopamine D2 receptors (R). Stimulation of A2AR inhibits and blockade of A2AR enhances D2R-mediated locomotor activation and goal-directed behavior in rodents. In striatal membrane preparations, adenosine decreases both the affinity and the signal transduction of D2R via its interaction with A2AR. Reciprocal A2AR/D2R interactions occur mainly in striatopallidal GABAergic medium spiny neurons (MSNs) of the indirect pathway that are involved in motor control, and in striatal astrocytes. In the nucleus accumbens, they also take place in MSNs involved in reward-related behavior. A2AR and D2R co-aggregate, co-internalize, and co-desensitize. They are at very close distance in biomembranes and form heteromers. Antagonistic interactions between adenosine and dopamine are (at least partially) caused by allosteric receptor–receptor interactions within A2AR/D2R heteromeric complexes. Such interactions may be exploited in novel strategies for the treatment of Parkinson’s disease, schizophrenia, substance abuse, and perhaps also attention deficit-hyperactivity disorder. Little is known about shifting A2AR/D2R heteromer/homodimer equilibria in the brain. Positron emission tomography with suitable ligands may provide in vivo information about receptor crosstalk in the living organism. Some experimental approaches, and strategies for the design of novel imaging agents (e.g., heterobivalent ligands) are proposed in this review.
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Affiliation(s)
- Kavya Prasad
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, The Netherlands; (E.F.J.d.V.); (P.H.E.); (R.A.J.O.D.)
- Correspondence: (K.P.); (A.v.W.); Tel.: +31-50-3613215
| | - Erik F. J. de Vries
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, The Netherlands; (E.F.J.d.V.); (P.H.E.); (R.A.J.O.D.)
| | - Philip H. Elsinga
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, The Netherlands; (E.F.J.d.V.); (P.H.E.); (R.A.J.O.D.)
| | - Rudi A. J. O. Dierckx
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, The Netherlands; (E.F.J.d.V.); (P.H.E.); (R.A.J.O.D.)
- Department of Diagnostic Sciences, Ghent University Faculty of Medicine and Health Sciences, C.Heymanslaan 10, 9000 Gent, Belgium
| | - Aren van Waarde
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, The Netherlands; (E.F.J.d.V.); (P.H.E.); (R.A.J.O.D.)
- Correspondence: (K.P.); (A.v.W.); Tel.: +31-50-3613215
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7
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Zrein A, Bagher AM, Young AP, Denovan-Wright EM, Kelly MEM. Endothelin receptor heteromerization inhibits β-arrestin function in HEK293 cells. Can J Physiol Pharmacol 2020; 98:531-540. [PMID: 32744876 DOI: 10.1139/cjpp-2019-0620] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The endothelin receptor A (ETA) and endothelin receptor B (ETB) are G protein-coupled receptors that are co-expressed in vascular smooth muscle cells. Endothelin-1 (ET-1) activates endothelin receptors to cause microvascular vasoconstriction. Previous studies have shown that heteromerization between ETA and ETB prolongs Ca2+ transients, leading to prolongation of Gαq-dependent signaling and sustained vasoconstriction. We hypothesized that these effects are in part mediated by the resistance of ETA/ETB heteromers to β-arrestin recruitment and subsequent desensitization. Using bioluminescence resonance energy transfer 2 (BRET2), we found that ETB has a relatively equal affinity to form either homomers or heteromers with ETA when co-expressed in the human embryonic kidney 293 (HEK293) cells. When co-expressed, activation of ETA and ETB by ET-1 caused a heteromer-specific reduction and delay in β-arrestin-2 recruitment with a corresponding reduction and delay in ET-1-induced ETA/ETB co-internalization. Furthermore, the co-expression of ETA and ETB inhibited ET-1-induced β-arrestin-1-dependent extracellular signal-regulated kinase (ERK) phosphorylation while prolonging ET-1-induced Gαq-dependent ERK phosphorylation. ETA/ETB heteromerization mediates the long-lasting vasoconstrictor response to ET-1 by the prolongation of Gαq-dependent signaling and inhibition of β-arrestin function.
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Affiliation(s)
- Adel Zrein
- Department of Pharmacology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Amina M Bagher
- Department of Pharmacology and Toxicology, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Alexander P Young
- Department of Pharmacology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | | | - Melanie E M Kelly
- Department of Pharmacology, Dalhousie University, Halifax, NS B3H 4R2, Canada.,Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, NS B3H 4R2, Canada
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8
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Tiwari V, He SQ, Huang Q, Liang L, Yang F, Chen Z, Tiwari V, Fujita W, Devi LA, Dong X, Guan Y, Raja SN. Activation of µ-δ opioid receptor heteromers inhibits neuropathic pain behavior in rodents. Pain 2020; 161:842-855. [PMID: 31815916 PMCID: PMC7085422 DOI: 10.1097/j.pain.0000000000001768] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Several reports support the idea that µ- and δ-opioid receptors (ORs) may exist as heterodimers in brain regions involved in pain signaling. The unique pharmacology of these heteromers may present a novel analgesic target. However, the role of µ-δ heteromers in sensory neurons involved in pain and opioid analgesia remains unclear, particularly during neuropathic pain. We examined the effects of spinal nerve injury on µ-δ heteromer expression in dorsal root ganglion (DRG) neurons and the effects of a µ-δ heteromer-targeting agonist, CYM51010, on neuropathic pain behavior in rats and mice. An L5 spinal nerve ligation (SNL) in rats significantly decreased µ-δ heteromer expression in L5 DRG but increased heteromer levels in uninjured L4 DRG. Importantly, in SNL rats, subcutaneous injection of CYM51010 inhibited mechanical hypersensitivity in a dose-related manner (EC50: 1.09 mg/kg) and also reversed heat hyperalgesia and attenuated ongoing pain (2 mg/kg, subcutaneously). HEK-293T cell surface-labeled with µ- and δ-ORs internalized both receptors after exposure to CYM51010. By contrast, in cells transfected with µ-OR alone, CYM51010 was significantly less effective at inducing receptor internalization. Electrophysiologic studies showed that CYM51010 inhibited the C-component and windup phenomenon in spinal wide dynamic range neurons of SNL rats. The pain inhibitory effects of CYM51010 persisted in morphine-tolerant rats but was markedly attenuated in µ-OR knockout mice. Our studies show that spinal nerve injury may increase µ-δ heterodimerization in uninjured DRG neurons, and that µ-δ heteromers may be a potential therapeutic target for relieving neuropathic pain, even under conditions of morphine tolerance.
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Affiliation(s)
- Vinod Tiwari
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Shao-Qiu He
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Qian Huang
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Lingli Liang
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Fei Yang
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Zhiyong Chen
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Vineeta Tiwari
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Wakako Fujita
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Lakshmi A. Devi
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Xinzhong Dong
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, the Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
- Howard Hughes Medical Institute, the Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
| | - Yun Guan
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
- Department of Neurological Surgery, the Johns Hopkins University, School of Medicine, Baltimore, MD, USA
| | - Srinivasa N. Raja
- Department of Anesthesiology and Critical Care Medicine, the Johns Hopkins University, School of Medicine, Baltimore, Maryland, 21205, USA
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Cordisco Gonzalez S, Mustafá ER, Rodriguez SS, Perello M, Raingo J. Dopamine Receptor Type 2 and Ghrelin Receptor Coexpression Alters Ca V2.2 Modulation by G Protein Signaling Cascades. ACS Chem Neurosci 2020; 11:3-13. [PMID: 31808667 DOI: 10.1021/acschemneuro.9b00426] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Voltage-gated calcium channels type 2.2 (CaV2.2) are activated by action potentials at presynaptic terminals, and their calcium current induces neurotransmitter release. In this context, regulating CaV2.2 is critical, and one of the most important mechanisms for doing so is through its G protein-coupled receptor (GPCR) activity. Two such GPCRs are the ghrelin (GHSR) and the dopamine type 2 (D2R) receptors. We previously demonstrated that constitutive GHSR activity reduces CaV2.2 forward trafficking and that ghrelin-induced GHSR activity inhibits CaV2.2 currents. On the other hand, dopamine-induced D2R activity also inhibits CaV2.2 currents. It has been recently shown that D2R and GHSR form heteromers in hypothalamic neurons. This interaction profoundly changes the signaling cascades activated by dopamine and is necessary for dopamine-dependent anorexia. Here we explored how D2R-GHSR coexpression in HEK293T cells modulates the effect that each GPCR has on CaV2.2. We found that D2R-GHSR coexpression reduces the inhibition of CaV2.2 currents by agonist-induced D2R activation and added a new source of basal CaV2.2 current inhibition to the one produced by GHSR solely expression. We investigated the signaling cascades implicated and found that constitutive GHSR activity, Gq protein, and Gβγ subunit play a critical role in these altered effects. Moreover, we found that the effect of D2R agonist on native calcium currents in hypothalamic neurons is reduced when both D2R and GHSR are overexpressed. In summary, our results allow us to propose a novel mechanism for controlling CaV2.2 currents involving the coexpression of two physiologically relevant GPCRs.
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Abrusán G, Marsh JA. Ligand Binding Site Structure Influences the Evolution of Protein Complex Function and Topology. Cell Rep 2019; 22:3265-3276. [PMID: 29562182 PMCID: PMC5873459 DOI: 10.1016/j.celrep.2018.02.085] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 01/17/2018] [Accepted: 02/22/2018] [Indexed: 02/06/2023] Open
Abstract
It has been suggested that the evolution of protein complexes is significantly influenced by stochastic, non-adaptive processes. Using ligand binding as a proxy of function, we show that the structure of ligand-binding sites significantly influences the evolution of protein complexes. We show that homomers with multi-chain binding sites (MBSs) evolve new functions slower than monomers or other homomers, and those binding cofactors and metals have more conserved quaternary structure than other homomers. Moreover, the ligands and ligand-binding pockets of homologous MBS homomers are more similar than monomers and other homomers. Our results suggest strong evolutionary selection for quaternary structure in cofactor-binding MBS homomers, whereas neutral processes are more important in complexes with single-chain binding sites. They also have pharmacological implications, suggesting that complexes with single-chain binding sites are better targets for selective drugs, whereas MBS homomers are good candidates for broad-spectrum antibiotic and multitarget drug design. Ligand binding site structure significantly influences protein function evolution MBS homomers have more similar ligand binding pockets than monomers and other homomers Cofactor and metal-binding MBS homomers have more conserved QS than other homomers MBS homomers are promising targets for developing antibiotics and multitarget drugs
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Affiliation(s)
- György Abrusán
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Crewe Road, Edinburgh EH4 2XU, UK.
| | - Joseph A Marsh
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Crewe Road, Edinburgh EH4 2XU, UK
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Abstract
Opioids are the most effective drugs for the treatment of severe pain, but they also cause addiction and overdose deaths, which have led to a worldwide opioid crisis. Therefore, the development of safer opioids is urgently needed. In this article, we provide a critical overview of emerging opioid-based strategies aimed at effective pain relief and improved side effect profiles. These approaches comprise biased agonism, the targeting of (i) opioid receptors in peripheral inflamed tissue (by reducing agonist access to the brain, the use of nanocarriers, or low pH-sensitive agonists); (ii) heteromers or multiple receptors (by monovalent, bivalent, and multifunctional ligands); (iii) receptor splice variants; and (iv) endogenous opioid peptides (by preventing their degradation or enhancing their production by gene transfer). Substantial advancements are underscored by pharmaceutical development of new opioids such as peripheral κ-receptor agonists, and by treatments augmenting the action of endogenous opioids, which have entered clinical trials. Additionally, there are several promising novel opioids comprehensively examined in preclinical studies, but also strategies such as biased agonism, which might require careful rethinking.
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Affiliation(s)
- Halina Machelska
- Department of Experimental Anesthesiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Melih Ö Celik
- Department of Experimental Anesthesiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
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12
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Porzionato A, Stocco E, Guidolin D, Agnati L, Macchi V, De Caro R. Receptor-Receptor Interactions of G Protein-Coupled Receptors in the Carotid Body: A Working Hypothesis. Front Physiol 2018; 9:697. [PMID: 29930516 PMCID: PMC6000251 DOI: 10.3389/fphys.2018.00697] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Accepted: 05/18/2018] [Indexed: 12/15/2022] Open
Abstract
In the carotid body (CB), a wide series of neurotransmitters and neuromodulators have been identified. They are mainly produced and released by type I cells and act on many different ionotropic and metabotropic receptors located in afferent nerve fibers, type I and II cells. Most metabotropic receptors are G protein-coupled receptors (GPCRs). In other transfected or native cells, GPCRs have been demonstrated to establish physical receptor–receptor interactions (RRIs) with formation of homo/hetero-complexes (dimers or receptor mosaics) in a dynamic monomer/oligomer equilibrium. RRIs modulate ligand binding, signaling, and internalization of GPCR protomers and they are considered of relevance for physiology, pharmacology, and pathology of the nervous system. We hypothesize that RRI may also occur in the different structural elements of the CB (type I cells, type II cells, and afferent fibers), with potential implications in chemoreception, neuromodulation, and tissue plasticity. This ‘working hypothesis’ is supported by literature data reporting the contemporary expression, in type I cells, type II cells, or afferent terminals, of GPCRs which are able to physically interact with each other to form homo/hetero-complexes. Functional data about cross-talks in the CB between different neurotransmitters/neuromodulators also support the hypothesis. On the basis of the above findings, the most significant homo/hetero-complexes which could be postulated in the CB include receptors for dopamine, adenosine, ATP, opioids, histamine, serotonin, endothelin, galanin, GABA, cannabinoids, angiotensin, neurotensin, and melatonin. From a methodological point of view, future studies should demonstrate the colocalization in close proximity (less than 10 nm) of the above receptors, through biophysical (i.e., bioluminescence/fluorescence resonance energy transfer, protein-fragment complementation assay, total internal reflection fluorescence microscopy, fluorescence correlation spectroscopy and photoactivated localization microscopy, X-ray crystallography) or biochemical (co-immunoprecipitation, in situ proximity ligation assay) methods. Moreover, functional approaches will be able to show if ligand binding to one receptor produces changes in the biochemical characteristics (ligand recognition, decoding, and trafficking processes) of the other(s). Plasticity aspects would be also of interest, as development and environmental stimuli (chronic continuous or intermittent hypoxia) produce changes in the expression of certain receptors which could potentially invest the dynamic monomer/oligomer equilibrium of homo/hetero-complexes and the correlated functional implications.
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Affiliation(s)
| | - Elena Stocco
- Department of Neuroscience, University of Padua, Padua, Italy
| | - Diego Guidolin
- Department of Neuroscience, University of Padua, Padua, Italy
| | - Luigi Agnati
- Department of Diagnostic, Clinical Medicine and Public Health, University of Modena and Reggio Emilia, Modena, Italy
| | - Veronica Macchi
- Department of Neuroscience, University of Padua, Padua, Italy
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13
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Łażewska D, Kieć-Kononowicz K. Progress in the development of histamine H 3 receptor antagonists/inverse agonists: a patent review (2013-2017). Expert Opin Ther Pat 2018; 28:175-196. [PMID: 29334795 DOI: 10.1080/13543776.2018.1424135] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
INTRODUCTION Since years, ligands blocking histamine H3 receptor (H3R) activity (antagonists/inverse agonists) are interesting targets in the search for new cures for CNS disorders. Intensive works done by academic and pharmaceutical company researchers have led to many potent and selective H3R antagonists/inverse agonists. Some of them have reached to clinical trials. AREAS COVERED Patent applications from January 2013 to September 2017 and the most important topics connected with H3R field are analysed. Espacenet, Patentscope, Pubmed, GoogleScholar or Cochrane Library online databases were principially used to collect all the materials. EXPERT OPINION The research interest in histamine H3R field is still high although the number of patent applications has decreased during the past 4 years (around 20 publications). Complexity of histamine H3R biology e.g. many isoforms, constitutive activity, heteromerization with other receptors (dopamine D2, D1, adenosine A2A) and pharmacology make not easy realization and evaluation of therapeutic potential of anti-H3R ligands. First results from clinical trials have verified potential utility of histamine H3R antagonist/inverse agonists in some diseases. However, more studies are necessary for better understanding of an involvement of the histaminergic system in CNS-related disorders and helping more ligands approach to clinical trials and the market. Lists of abbreviations: hAChEI - human acetylcholinesterase inhibitor; hBuChEI - human butyrylcholinesterase inhibitor; hMAO - human monoamine oxidase; MAO - monoamine oxidase.
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Affiliation(s)
- Dorota Łażewska
- a Department of Technology and Biotechnology of Drugs , Jagiellonian University Medical College , Kraków , Poland
| | - Katarzyna Kieć-Kononowicz
- a Department of Technology and Biotechnology of Drugs , Jagiellonian University Medical College , Kraków , Poland
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14
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Abstract
Opioids are the most effective drugs for the treatment of severe pain, but they also cause addiction and overdose deaths, which have led to a worldwide opioid crisis. Therefore, the development of safer opioids is urgently needed. In this article, we provide a critical overview of emerging opioid-based strategies aimed at effective pain relief and improved side effect profiles. These approaches comprise biased agonism, the targeting of (i) opioid receptors in peripheral inflamed tissue (by reducing agonist access to the brain, the use of nanocarriers, or low pH-sensitive agonists); (ii) heteromers or multiple receptors (by monovalent, bivalent, and multifunctional ligands); (iii) receptor splice variants; and (iv) endogenous opioid peptides (by preventing their degradation or enhancing their production by gene transfer). Substantial advancements are underscored by pharmaceutical development of new opioids such as peripheral κ-receptor agonists, and by treatments augmenting the action of endogenous opioids, which have entered clinical trials. Additionally, there are several promising novel opioids comprehensively examined in preclinical studies, but also strategies such as biased agonism, which might require careful rethinking.
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Affiliation(s)
- Halina Machelska
- Department of Experimental Anesthesiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Melih Ö Celik
- Department of Experimental Anesthesiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
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15
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Abstract
Dopamine D3 receptors (D3R) modulate neuronal activity in several brain regions including cortex, striatum, cerebellum, and hippocampus. A growing body of evidence suggests that aberrant D3R signaling contributes to multiple brain diseases, such as Parkinson’s disease, essential tremor, schizophrenia, and addiction. In line with these findings, D3R has emerged as a potential target in the treatment of neurological disorders. However, the mechanisms underlying neuronal D3R signaling are poorly understood, either in healthy or diseased brain. Here, I review the molecular mechanisms involved in D3R signaling via monomeric D3R and heteromeric receptor complexes (e.g., D3R-D1R, D3R-D2R, D3R-A2aR, and D3R-D3nf). I focus on D3R signaling pathways that, according to recent reports, contribute to pathological brain states. In particular, I describe evidence on both quantitative (e.g., increased number or affinity) and qualitative (e.g., switched signaling) changes in D3R that has been associated with brain dysfunction. I conclude with a description of basic mechanisms that modulate D3R signaling such as desensitization, as disruption of these mechanisms may underlie pathological changes in D3R signaling. Because several lines of evidence support the idea that imbalances in D3R signaling alter neural function, a better understanding of downstream D3R pathways is likely to reveal novel therapeutic strategies toward dopamine-related brain disorders.
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Affiliation(s)
- G Aleph Prieto
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, USA
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16
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Abstract
This review summarizes modern data on the structure and functions ofheteromersformed by D1 and D2 dopamine receptors focusing on their role in the mechanisms of drug dependence. This article discusses potential functional significance of heterodimeric D1-D2 dopamine receptorsdue to their localization in the brain as well as unique pharmacological propertiesversus constituent monomers. It is shown that heteromerization results in dramatic changes in activated signaling pathways compare to the corresponding monomers. These studies update our current knowledge of ligand-receptor interactions and provide better understanding of dopamine receptors pharmacology. Furthermore elucidation of significance of heterodimeric D1-D2 dopamine receptors as drug targets is important for the development of new effective drug addiction treatment.
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Affiliation(s)
- N L Vekshina
- V.P. Serbsky Federal Medical Research Center on Psychiatry and Narcology, Moscow, Russia
| | - P K Anokhin
- V.P. Serbsky Federal Medical Research Center on Psychiatry and Narcology, Moscow, Russia
| | - A G Veretinskaya
- V.P. Serbsky Federal Medical Research Center on Psychiatry and Narcology, Moscow, Russia
| | - I Yu Shamakina
- V.P. Serbsky Federal Medical Research Center on Psychiatry and Narcology, Moscow, Russia
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17
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Xu Q, Lin X, Matiukas A, Zhang X, Veenstra RD. Specificity of the connexin W3/4 locus for functional gap junction formation. Channels (Austin) 2016; 10:453-65. [PMID: 27304225 PMCID: PMC5034775 DOI: 10.1080/19336950.2016.1200775] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 05/23/2016] [Accepted: 06/08/2016] [Indexed: 10/21/2022] Open
Abstract
The N-terminal (NT) domain of the connexins forms an essential transjunctional voltage (Vj) sensor and pore-forming domain that when truncated, tagged, or mutated often leads to formation of a nonfunctional channel. The NT domain is relatively conserved among the connexins though the α- and δ-group connexins possess a G2 residue not found in the β- and γ-group connexins. Deletion of the connexin40 G2 residue (Cx40G2Δ) affected the Vj gating, increased the single channel conductance (γj), and decreased the relative K(+)/Cl(-) permeability (PK/PCl) ratio of the Cx40 gap junction channel. The conserved α/β-group connexin D2/3 and W3/4 loci are postulated to anchor the NT domain within the pore via hydrophilic and hydrophobic interactions with adjacent connexin T5 and M34 residues. Cx40D3N and D3R mutations produced limited function with progressive reductions in Vj gating and noisy low γj gap junction channels that reduced the γj of wild-type Cx40 channels from 150 pS to < 50 pS when coexpressed. Surprisingly, hydrophobic Cx40 W4F and W4Y substitution mutations were not compatible with function despite their ability to form gap junction plaques. These data are consistent with minor and major contributions of the G2 and D3 residues to the Cx40 channel pore structure, but not with the postulated hydrophobic W4 intermolecular interactions. Our results indicate an absolute requirement for an amphipathic W3/4 residue that is conserved among all α/β/δ/γ-group connexins. We alternatively hypothesize that the connexin D2/3-W3/4 locus interacts with the highly conserved FIFR M1 motif to stabilize the NT domain within the pore.
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Affiliation(s)
- Qin Xu
- Department of Pharmacology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Xianming Lin
- Department of Pharmacology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Arvydas Matiukas
- Department of Pharmacology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Xian Zhang
- Department of Pharmacology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Richard D. Veenstra
- Department of Pharmacology, SUNY Upstate Medical University, Syracuse, NY, USA
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, NY, USA
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18
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Abstract
More than 800 different human membrane-spanning G-protein-coupled receptors (GPCRs) serve as signal transducers at biological barriers. These receptors are activated by a wide variety of ligands such as peptides, ions and hormones, and are able to activate a diverse set of intracellular signaling pathways. GPCRs are of central importance in endocrine regulation, which underpins the significance of comprehensively studying these receptors and interrelated systems. During the last decade, the capacity for multimerization of GPCRs was found to be a common and functionally relevant property. The interaction between GPCR monomers results in higher order complexes such as homomers (identical receptor subtype) or heteromers (different receptor subtypes), which may be present in a specific and dynamic monomer/oligomer equilibrium. It is widely accepted that the oligomerization of GPCRs is a mechanism for determining the fine-tuning and expansion of cellular processes by modification of ligand action, expression levels, and related signaling outcome. Accordingly, oligomerization provides exciting opportunities to optimize pharmacological treatment with respect to receptor target and tissue selectivity or for the development of diagnostic tools. On the other hand, GPCR heteromerization may be a potential reason for the undesired side effects of pharmacological interventions, faced with numerous and common mutual signaling modifications in heteromeric constellations. Finally, detailed deciphering of the physiological occurrence and relevance of specific GPCR/GPCR-ligand interactions poses a future challenge. This review will tackle the aspects of GPCR oligomerization with specific emphasis on family A GPCRs involved in endocrine regulation, whereby only a subset of these receptors will be discussed in detail.
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Affiliation(s)
- Gunnar Kleinau
- Institute of Experimental Pediatric Endocrinology (IEPE)Charité-Universitätsmedizin, Berlin, Germany
| | - Anne Müller
- Institute of Experimental Pediatric Endocrinology (IEPE)Charité-Universitätsmedizin, Berlin, Germany
| | - Heike Biebermann
- Institute of Experimental Pediatric Endocrinology (IEPE)Charité-Universitätsmedizin, Berlin, Germany
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19
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Affiliation(s)
- Dominique Massotte
- Institut des Neurosciences Cellulaires et Intégratives Strasbourg, France
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20
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Schuepbach-Mallepell S, Das D, Willen L, Vigolo M, Tardivel A, Lebon L, Kowalczyk-Quintas C, Nys J, Smulski C, Zheng TS, Maskos K, Lammens A, Jiang X, Hess H, Tan SL, Schneider P. Stoichiometry of Heteromeric BAFF and APRIL Cytokines Dictates Their Receptor Binding and Signaling Properties. J Biol Chem 2015; 290:16330-42. [PMID: 25953898 DOI: 10.1074/jbc.m115.661405] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [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: 04/24/2015] [Indexed: 12/31/2022] Open
Abstract
The closely related TNF family ligands B cell activation factor (BAFF) and a proliferation-inducing ligand (APRIL) serve in the generation and maintenance of mature B-lymphocytes. Both BAFF and APRIL assemble as homotrimers that bind and activate several receptors that they partially share. However, heteromers of BAFF and APRIL that occur in patients with autoimmune diseases are incompletely characterized. The N and C termini of adjacent BAFF or APRIL monomers are spatially close and can be linked to create single-chain homo- or hetero-ligands of defined stoichiometry. Similar to APRIL, heteromers consisting of one BAFF and two APRILs (BAA) bind to the receptors B cell maturation antigen (BCMA), transmembrane activator and CAML interactor (TACI) but not to the BAFF receptor (BAFFR). Heteromers consisting of one APRIL and two BAFF (ABB) bind to TACI and BCMA and weakly to BAFFR in accordance with the analysis of the receptor interaction sites in the crystallographic structure of ABB. Receptor binding correlated with activity in reporter cell line assays specific for BAFFR, TACI, or BCMA. Single-chain BAFF (BBB) and to a lesser extent single-chain ABB, but not APRIL or single-chain BAA, rescued BAFFR-dependent B cell maturation in BAFF-deficient mice. In conclusion, BAFF-APRIL heteromers of different stoichiometries have distinct receptor-binding properties and activities. Based on the observation that heteromers are less active than BAFF, we speculate that their physiological role might be to down-regulate BAFF activity.
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Affiliation(s)
| | - Dolon Das
- From the Department of Biochemistry, University of Lausanne, CH-1066 Epalinges, Switzerland
| | - Laure Willen
- From the Department of Biochemistry, University of Lausanne, CH-1066 Epalinges, Switzerland
| | - Michele Vigolo
- From the Department of Biochemistry, University of Lausanne, CH-1066 Epalinges, Switzerland
| | - Aubry Tardivel
- From the Department of Biochemistry, University of Lausanne, CH-1066 Epalinges, Switzerland
| | - Luc Lebon
- From the Department of Biochemistry, University of Lausanne, CH-1066 Epalinges, Switzerland
| | | | - Josquin Nys
- From the Department of Biochemistry, University of Lausanne, CH-1066 Epalinges, Switzerland
| | - Cristian Smulski
- From the Department of Biochemistry, University of Lausanne, CH-1066 Epalinges, Switzerland
| | | | - Klaus Maskos
- Proteros Biostructures GmbH, D-82152 Planegg, Germany
| | | | - Xuliang Jiang
- the EMD Serono Research and Development Institute, Billerica, Massachusetts 01821
| | - Henry Hess
- a subsidiary of Merck KGaA, D-64293 Darmstadt, Germany
| | - Seng-Lai Tan
- the EMD Serono Research and Development Institute, Billerica, Massachusetts 01821
| | - Pascal Schneider
- From the Department of Biochemistry, University of Lausanne, CH-1066 Epalinges, Switzerland,
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21
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Guidolin D, Agnati LF, Marcoli M, Borroto-Escuela DO, Fuxe K. G-protein-coupled receptor type A heteromers as an emerging therapeutic target. Expert Opin Ther Targets 2014; 19:265-83. [PMID: 25381716 DOI: 10.1517/14728222.2014.981155] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION The discovery of receptor-receptor interactions (RRIs) in the early 1980s provided evidence that G-protein-coupled receptors (GPCRs) operate not only as monomers but also as heteromers, in which integration of the incoming signals takes place already at the plasma membrane level through allosteric RRIs. These integrative mechanisms give sophisticated dynamics to the structure and function of these receptor assemblies in terms of modulation of recognition, G-protein signaling and selectivity and switching to β-arrestin signaling. AREAS COVERED The present review briefly describes the concept of direct RRI and the available data on the mechanisms of oligomer formation. Further, pharmacological data concerning the best characterized heteromers involving type A GPCRs will be analyzed to evaluate their profile as possible targets for the treatment of various diseases, in particular of impacting diseases of the CNS. EXPERT OPINION GPCR heteromers have the potential to open a completely new field for pharmacology with likely a major impact in molecular medicine. Novel pharmacological strategies for the treatment of several pathologies have already been proposed. However, several challenges still exist to accurately characterize the role of the identified heteroreceptor complexes in pathology and to develop heteromer-specific ligands capable of efficiently exploiting their pharmacological features.
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Affiliation(s)
- Diego Guidolin
- University of Padova, Department of Molecular Medicine , via Gabelli 65, 35121 Padova , Italy +39 049 8272316 ; +39 049 8272319 ;
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22
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Abstract
The concept of platelets as important players in the process of atherogenesis has become increasingly accepted due to accumulating experimental and clinical evidence. Despite the progress in understanding the molecular details of atherosclerosis, particularly by using animal models, the inflammatory and thrombotic roles of activated platelet s especially in the human system remain difficult to dissect, as often only the complications of atherosclerosis, i.e., stroke and myocardial infarction are definable but not the plaque burden. Platelet indices including platelet count and mean platelet volume (MPV) and soluble mediators released by activated platelets are associated with atherosclerosis. The chemokine CXCL4 has multiple atherogenic activities, e.g., altering the differentiation of T cells and macrophages by inhibiting neutrophil and monocyte apoptosis and by increasing the uptake of oxLDL and synergizing with CCL5. CCL5 is released and deposited on endothelium by activated platelets thereby triggering atherogenic monocyte recruitment, which can be attenuated by blocking the corresponding chemokine receptor CCR5. Atheroprotective and plaque stabilizing properties are attributed to CXCL12, which plays an important role in regenerative processes by attracting progenitor cells. Its release from luminal attached platelets accelerates endothelial healing after injury. Platelet surface molecules GPIIb/IIIa, GP1bα, P-selectin, JAM-A and the CD40/CD40L dyade are crucially involved in the interaction with endothelial cells, leukocytes and matrix molecules affecting atherogenesis. Beyond the effects on the arterial inflammatory infiltrate, platelets affect cholesterol metabolism by binding, modifying and endocytosing LDL particles via their scavenger receptors and contribute to the formation of lipid laden macrophages. Current medical therapies for the prevention of atherosclerotic therapies enable the elucidation of mechanisms linking platelets to inflammation and atherosclerosis.
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Affiliation(s)
- Philipp von Hundelshausen
- Institute for Cardiovascular Prevention, Ludwig-Maximilians-University of Munich Munich, Germany ; German Centre for Cardiovascular Research (DZHK), Partner Site Munich Heart Alliance Munich, Germany
| | - Martin M N Schmitt
- Institute for Cardiovascular Prevention, Ludwig-Maximilians-University of Munich Munich, Germany
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23
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Borroto-Escuela DO, Brito I, Romero-Fernandez W, Di Palma M, Oflijan J, Skieterska K, Duchou J, Van Craenenbroeck K, Suárez-Boomgaard D, Rivera A, Guidolin D, Agnati LF, Fuxe K. The G protein-coupled receptor heterodimer network (GPCR-HetNet) and its hub components. Int J Mol Sci 2014; 15:8570-90. [PMID: 24830558 PMCID: PMC4057749 DOI: 10.3390/ijms15058570] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 03/26/2014] [Accepted: 04/30/2014] [Indexed: 01/09/2023] Open
Abstract
G protein-coupled receptors (GPCRs) oligomerization has emerged as a vital characteristic of receptor structure. Substantial experimental evidence supports the existence of GPCR-GPCR interactions in a coordinated and cooperative manner. However, despite the current development of experimental techniques for large-scale detection of GPCR heteromers, in order to understand their connectivity it is necessary to develop novel tools to study the global heteroreceptor networks. To provide insight into the overall topology of the GPCR heteromers and identify key players, a collective interaction network was constructed. Experimental interaction data for each of the individual human GPCR protomers was obtained manually from the STRING and SCOPUS databases. The interaction data were used to build and analyze the network using Cytoscape software. The network was treated as undirected throughout the study. It is comprised of 156 nodes, 260 edges and has a scale-free topology. Connectivity analysis reveals a significant dominance of intrafamily versus interfamily connections. Most of the receptors within the network are linked to each other by a small number of edges. DRD2, OPRM, ADRB2, AA2AR, AA1R, OPRK, OPRD and GHSR are identified as hubs. In a network representation 10 modules/clusters also appear as a highly interconnected group of nodes. Information on this GPCR network can improve our understanding of molecular integration. GPCR-HetNet has been implemented in Java and is freely available at http://www.iiia.csic.es/~ismel/GPCR-Nets/index.html.
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Affiliation(s)
| | - Ismel Brito
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, 17177 Stockholm, Sweden.
| | | | - Michael Di Palma
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, 17177 Stockholm, Sweden.
| | - Julia Oflijan
- Department of Physiology, Faculty of Medicine, University of Tartu, Tartu 50411, Estonia.
| | - Kamila Skieterska
- Laboratory of Eukaryotic Gene Expression and Signal Transduction (LEGEST), Ghent University, 9000 Ghent, Belgium.
| | - Jolien Duchou
- Laboratory of Eukaryotic Gene Expression and Signal Transduction (LEGEST), Ghent University, 9000 Ghent, Belgium.
| | - Kathleen Van Craenenbroeck
- Laboratory of Eukaryotic Gene Expression and Signal Transduction (LEGEST), Ghent University, 9000 Ghent, Belgium.
| | - Diana Suárez-Boomgaard
- Department of Cell Biology, School of Science, University of Málaga, 29071 Málaga, Spain.
| | - Alicia Rivera
- Department of Cell Biology, School of Science, University of Málaga, 29071 Málaga, Spain.
| | - Diego Guidolin
- Department of Molecular Medicine, University of Padova, Padova 35121, Italy.
| | - Luigi F Agnati
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, 17177 Stockholm, Sweden.
| | - Kjell Fuxe
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, 17177 Stockholm, Sweden.
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24
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Chen Y, Gao N, Jiang J. Surface matters: enhanced bactericidal property of core-shell Ag-Fe2O3 nanostructures to their heteromer counterparts from one-pot synthesis. Small 2013; 9:3242-3246. [PMID: 23585383 DOI: 10.1002/smll.201300543] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Indexed: 06/02/2023]
Abstract
A facile one-pot synthesis of Ag@Fe2 O3 core-shell and Ag-Fe2 O3 heteromer nanoparticles is developed, and the core-shell nanoparticles show superior antibacterial properties compared to their heteromer counterparts and plain Ag nanoparticles. The mechanism for the increased efficiency is proposed to be due to the enhanced Ag ion release from the iron oxide shell-protected pristine Ag surface.
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Affiliation(s)
- Yingjie Chen
- i-Lab and Division of Nanobiomedicine, Suzhou Key Laboratory of Nanobiomedical Characterization, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, 215123, China
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25
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Abstract
Mutations in connexin50 (Cx50) cause dominant cataracts in both humans and mice. The exact mechanisms by which mutations cause these variable phenotypes are poorly understood. We have examined the functional properties of gap junctions made by three Cx50 mutations, V44E, D47N, and V79L, expressed in mammalian cell lines. V44E trafficked to the plasma membrane properly and formed gap junctional plaques. However, the mutant did not form functional gap junctions when expressed alone, or with wild-type (WT) Cx46 and Cx50, indicating that V44E is a dominant negative inhibitor of WT connexin function. In contrast, D47N subunits did not localize to junctional plaques or form functional homotypic gap junctions; however, mixed expression of D47N and WT subunits of either Cx50 or Cx46 resulted in functional intercellular channels, with high levels of coupling. Single-channel studies indicated that D47N formed heteromeric channels with WT Cx46 with unique properties. Unlike either V44E or D47N, V79L formed functional homotypic intercellular channels. However, the mutation caused an alteration in voltage gating and a dramatic reduction in the single-channel open probability, resulting in much lower levels of conductance in cells expressing V79L alone, or together with WT connexin subunits. Thus, each mutation produced distinct changes in the properties of junctional coupling. V44E failed to form intercellular channels in any configuration, D47N formed only heteromeric channels with WT connexins, and V79L formed homotypic and heteromeric channels with altered properties. These results suggest that unique interactions between mutant and wild-type lens connexins might underlie the development of various cataract phenotypes in humans.
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Affiliation(s)
- Clio Rubinos
- Department of Biological and Vision Sciences and the Graduate Center for Vision Research, State University of New York College of Optometry, New York, New York; and
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26
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Harvey JH, Long DH, England PM, Whistler JL. Tuned-Affinity Bivalent Ligands for the Characterization of Opioid Receptor Heteromers. ACS Med Chem Lett 2012; 3:640-644. [PMID: 23585918 DOI: 10.1021/ml300083p] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Opioid receptors, including the mu and delta opioid receptors (MOR and DOR) are important targets for the treatment of pain. Although there is mounting evidence that these receptors form heteromers, the functional role of the MOR/DOR heteromer remains unresolved. We have designed and synthesized bivalent ligands as tools to elucidate the functional role of the MOR/DOR heteromer. Our ligands (L2 and L4) are comprised of a compound with low affinity at the DOR tethered to a compound with high affinity at the MOR, with the goal of producing ligands with "tuned affinity" at MOR/DOR heteromers compared to DOR homomers. Here we show that both L2 and L4 demonstrate enhanced affinity at MOR/DOR heteromers compared to DOR homomers, thereby providing unique pharmacological tools to dissect the role of the MOR/DOR heteromer in pain.
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Affiliation(s)
- Jessica H. Harvey
- Ernest Gallo Clinic and Research Center, 5858 Horton Street, Suite 200,
Emeryville, California 94608, United States
- University of California, San Francisco, Genentech Hall, 600 16th Street, San
Francisco, California 94158, United States
| | - Darcie H. Long
- Ernest Gallo Clinic and Research Center, 5858 Horton Street, Suite 200,
Emeryville, California 94608, United States
| | - Pamela M. England
- University of California, San Francisco, Genentech Hall, 600 16th Street, San
Francisco, California 94158, United States
| | - Jennifer L. Whistler
- Ernest Gallo Clinic and Research Center, 5858 Horton Street, Suite 200,
Emeryville, California 94608, United States
- University of California, San Francisco, Genentech Hall, 600 16th Street, San
Francisco, California 94158, United States
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27
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Fuxe K, Borroto-Escuela DO, Romero-Fernandez W, Diaz-Cabiale Z, Rivera A, Ferraro L, Tanganelli S, Tarakanov AO, Garriga P, Narváez JA, Ciruela F, Guescini M, Agnati LF. Extrasynaptic neurotransmission in the modulation of brain function. Focus on the striatal neuronal-glial networks. Front Physiol 2012; 3:136. [PMID: 22675301 PMCID: PMC3366473 DOI: 10.3389/fphys.2012.00136] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Accepted: 04/23/2012] [Indexed: 12/20/2022] Open
Abstract
Extrasynaptic neurotransmission is an important short distance form of volume transmission (VT) and describes the extracellular diffusion of transmitters and modulators after synaptic spillover or extrasynaptic release in the local circuit regions binding to and activating mainly extrasynaptic neuronal and glial receptors in the neuroglial networks of the brain. Receptor-receptor interactions in G protein-coupled receptor (GPCR) heteromers play a major role, on dendritic spines and nerve terminals including glutamate synapses, in the integrative processes of the extrasynaptic signaling. Heteromeric complexes between GPCR and ion-channel receptors play a special role in the integration of the synaptic and extrasynaptic signals. Changes in extracellular concentrations of the classical synaptic neurotransmitters glutamate and GABA found with microdialysis is likely an expression of the activity of the neuron-astrocyte unit of the brain and can be used as an index of VT-mediated actions of these two neurotransmitters in the brain. Thus, the activity of neurons may be functionally linked to the activity of astrocytes, which may release glutamate and GABA to the extracellular space where extrasynaptic glutamate and GABA receptors do exist. Wiring transmission (WT) and VT are fundamental properties of all neurons of the CNS but the balance between WT and VT varies from one nerve cell population to the other. The focus is on the striatal cellular networks, and the WT and VT and their integration via receptor heteromers are described in the GABA projection neurons, the glutamate, dopamine, 5-hydroxytryptamine (5-HT) and histamine striatal afferents, the cholinergic interneurons, and different types of GABA interneurons. In addition, the role in these networks of VT signaling of the energy-dependent modulator adenosine and of endocannabinoids mainly formed in the striatal projection neurons will be underlined to understand the communication in the striatal cellular networks.
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Affiliation(s)
- Kjell Fuxe
- Department of Neuroscience, Karolinska InstitutetStockholm, Sweden
| | | | | | - Zaida Diaz-Cabiale
- Department of Physiology, School of Medicine, University of MálagaMálaga, Spain
| | - Alicia Rivera
- Department of Cell Biology, Faculty of Sciences, University of MálagaMálaga, Spain
| | - Luca Ferraro
- Pharmacology Section, Department of Clinical and Experimental Medicine, University of FerraraFerrara, Italy
| | - Sergio Tanganelli
- Pharmacology Section, Department of Clinical and Experimental Medicine, University of FerraraFerrara, Italy
| | - Alexander O. Tarakanov
- Russian Academy of Sciences, St. Petersburg Institute for Informatics and AutomationSaint Petersburg, Russia
| | - Pere Garriga
- Departament d’Enginyeria Química, Centre de Biotecnologia Molecular, Universitat Politècnica de CatalunyaBarcelona, Spain
| | - José Angel Narváez
- Department of Physiology, School of Medicine, University of MálagaMálaga, Spain
| | - Francisco Ciruela
- Unitat de Farmacologia, Departament Patologia i Terapèutica Experimental, Universitat de BarcelonaBarcelona, Spain
| | - Michele Guescini
- Department of Biomolecular Sciences, University of Urbino “CarloBo”Urbino, Italy
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28
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Berg KA, Patwardhan AM, Akopian AN. Receptor and channel heteromers as pain targets. Pharmaceuticals (Basel) 2012; 5:249-78. [PMID: 24281378 PMCID: PMC3763638 DOI: 10.3390/ph5030249] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Revised: 02/04/2012] [Accepted: 02/15/2012] [Indexed: 12/20/2022] Open
Abstract
Recent discoveries indicate that many G-protein coupled receptors (GPCRs) and channels involved in pain modulation are able to form receptor heteromers. Receptor and channel heteromers often display distinct signaling characteristics, pharmacological properties and physiological function in comparison to monomer/homomer receptor or ion channel counterparts. It may be possible to capitalize on such unique properties to augment therapeutic efficacy while minimizing side effects. For example, drugs specifically targeting heteromers may have greater tissue specificity and analgesic efficacy. This review will focus on current progress in our understanding of roles of heteromeric GPCRs and channels in pain pathways as well as strategies for controlling pain pathways via targeting heteromeric receptors and channels. This approach may be instrumental in the discovery of novel classes of drugs and expand our repertoire of targets for pain pharmacotherapy.
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Affiliation(s)
- Kelly A. Berg
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA; (K.A.B.)
| | - Amol M. Patwardhan
- Department of Anesthesiology, Arizona Health Sciences Center, Tucson, AZ 85724, USA; (A.M.P.)
| | - Armen N. Akopian
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA; (K.A.B.)
- Department of Endodontics, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
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29
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Fuxe K, Borroto-Escuela DO, Romero-Fernandez W, Tarakanov AO, Calvo F, Garriga P, Tena M, Narvaez M, Millón C, Parrado C, Ciruela F, Agnati LF, Narvaez JA, Díaz-Cabiale Z. On the existence and function of galanin receptor heteromers in the central nervous system. Front Endocrinol (Lausanne) 2012; 3:127. [PMID: 23112793 PMCID: PMC3481144 DOI: 10.3389/fendo.2012.00127] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2012] [Accepted: 10/05/2012] [Indexed: 12/04/2022] Open
Abstract
Galanin receptor (GalR) subtypes 1-3 linked to central galanin neurons may form heteromers with each other and other types of G protein-coupled receptors in the central nervous system (CNS). These heteromers may be one molecular mechanism for galanin peptides and their N-terminal fragments (gal 1-15) to modulate the function of different types of glia-neuronal networks in the CNS, especially the emotional and the cardiovascular networks. GalR-5-HT1A heteromers likely exist with antagonistic GalR-5-HT1A receptor-receptor interactions in the ascending midbrain raphe 5-HT neuron systems and their target regions. They represent a novel target for antidepressant drugs. Evidence is given for the existence of GalR1-5-HT1A heteromers in cellular models with trans-inhibition of the protomer signaling. A GalR1-GalR2 heteromer is proposed to be a galanin N-terminal fragment preferring receptor (1-15) in the CNS. Furthermore, a GalR1-GalR2-5-HT1A heterotrimer is postulated to explain why only galanin (1-15) but not galanin (1-29) can antagonistically modulate the 5-HT1A receptors in the dorsal hippocampus rich in gal fragment binding sites. The results underline a putative role of different types of GalR-5-HT1A heteroreceptor complexes in depression. GalR antagonists may also have therapeutic actions in depression by blocking the antagonistic GalR-NPYY1 receptor interactions in putative GalR-NPYY1 receptor heteromers in the CNS resulting in increases in NPYY1 transmission and antidepressant effects. In contrast the galanin fragment receptor (a postulated GalR1-GalR2 heteromer) appears to be linked to the NPYY2 receptor enhancing the affinity of the NPYY2 binding sites in a putative GalR1-GalR2-NPYY2 heterotrimer. Finally, putative GalR-α2-adrenoreceptor heteromers with antagonistic receptor-receptor interactions may be a widespread mechanism in the CNS for integration of galanin and noradrenaline signals also of likely relevance for depression.
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Affiliation(s)
- Kjell Fuxe
- Department of Neuroscience, Karolinska InstitutetStockholm, Sweden
- *Correspondence: Kjell Fuxe, Department of Neuroscience, Karolinska Institutet, Retzius väg 8, 17177 Stockholm, Sweden. e-mail:
| | | | | | - Alexander O. Tarakanov
- St. Petersburg Institute for Informatics and Automation, Russian Academy of SciencesSaint Petersburg, Russia
| | - Feliciano Calvo
- Department of Neuroscience, Karolinska InstitutetStockholm, Sweden
| | - Pere Garriga
- Centre de Biotecnologia Molecular, Departament d’Enginyeria Química, Universitat Politécnica de CatalunyaBarcelona, Spain
| | - Mercé Tena
- Centre de Biotecnologia Molecular, Departament d’Enginyeria Química, Universitat Politécnica de CatalunyaBarcelona, Spain
| | - Manuel Narvaez
- Department of Physiology, School of Medicine, University of MálagaMálaga, Spain
| | - Carmelo Millón
- Department of Physiology, School of Medicine, University of MálagaMálaga, Spain
| | - Concepción Parrado
- Department of Histology, School of Medicine, University of MálagaMálaga, Spain
| | - Francisco Ciruela
- Unitat de Farmacologia, Departament Patologia i Terapéutica Experimental, Universitat de BarcelonaBarcelona, Spain
| | - Luigi F. Agnati
- Department of Biomedical Sciences, University of Modena and Reggio EmiliaModena, Italy
- Istituto di Ricovero e Cura a Carattere ScientificoLido Venice, Italy
| | - José A. Narvaez
- Department of Physiology, School of Medicine, University of MálagaMálaga, Spain
| | - Zaida Díaz-Cabiale
- Department of Physiology, School of Medicine, University of MálagaMálaga, Spain
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30
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Tang Y, Yang J, Lunzer MM, Powers MD, Portoghese PS. A κ Opioid Pharmacophore Becomes a Spinally Selective κ-δ Agonist When Modified with a Basic Extender Arm. ACS Med Chem Lett 2011; 2:7-10. [PMID: 24936231 DOI: 10.1021/ml1001294] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [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: 06/06/2010] [Accepted: 10/06/2010] [Indexed: 11/29/2022] Open
Abstract
We have explored the concept of a molecular extender arm attached to a κ opioid agonist pharmacophore 3 (ICI-199,441) in an effort to potentially interact with a complementary group on a neighboring opioid receptor. The molecular arm containing a terminal amine group was lengthened incrementally from 11 up to 18 atoms. Increasing the number of atoms in the arm produced virtually no change in the mouse intracerebroventricular (i.c.v.) antinociceptive potency. In contrast, the intrathecal (i.t.) potency of 6 (KDA-16) with a 16-atom arm was dramatically increased, as reflected by its antinociceptive i.c.v./i.t. ED50 ratio of ∼130. Further lengthening led to a decreased ED50 ratio. In vivo selective antagonist studies of KDA-16 revealed that κ and δ opioid receptors were responsible for the greatly enhanced i.t. potency. Calcium release experiments in HEK-293 cells suggested that KDA-16 selectively activate κ-δ heteromers. These data are consistent with the reported possible presence of heteromeric κ-δ opioid receptors in mouse spinal cord but not in the brain. The use of a molecular extender arm may be useful for developing spinally selective analgesics.
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Affiliation(s)
- Ye Tang
- Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Jie Yang
- Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Mary M. Lunzer
- Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Michael D. Powers
- Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Philip S. Portoghese
- Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota, Minneapolis, Minnesota 55455, United States
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31
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Hipser C, Bushlin I, Gupta A, Gomes I, Devi LA. Role of antibodies in developing drugs that target G-protein-coupled receptor dimers. Mt Sinai J Med 2010; 77:374-80. [PMID: 20687183 PMCID: PMC2917817 DOI: 10.1002/msj.20199] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
G-protein-coupled receptors are important molecular targets in drug discovery. These receptors play a pivotal role in physiological signaling pathways and are targeted by nearly 50% of currently available drugs. Mounting evidence suggests that G-protein-coupled receptors form dimers, and various studies have shown that dimerization is necessary for receptor maturation, signaling, and trafficking. However, the physiological implications of dimerization in vivo have not been well explored because detection of GPCR dimers in endogenous systems has been a challenging task. One exciting new approach to this challenge is the generation of antibodies against specific G-protein-coupled receptor dimers. Such antibodies could be used as tools for characterization of heteromer-specific function; as reagents for their purification, tissue localization, and regulation in vivo; and as probes for mapping their functional domains. In addition, such antibodies could serve as alternative ligands for G-protein-coupled receptor heteromers. Thus, heteromer-specific antibodies represent novel tools for the exploration and manipulation of G-protein-coupled receptor-dimer pharmacology.
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Affiliation(s)
- Chris Hipser
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, NY, USA
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32
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Yekkirala AS, Kalyuzhny AE, Portoghese PS. Standard opioid agonists activate heteromeric opioid receptors: evidence for morphine and [d-Ala(2)-MePhe(4)-Glyol(5)]enkephalin as selective μ-δ agonists. ACS Chem Neurosci 2010; 1:146-54. [PMID: 22816017 DOI: 10.1021/cn9000236] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [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: 10/01/2009] [Accepted: 11/16/2009] [Indexed: 12/15/2022] Open
Abstract
Research in the opioid field has relied heavily on the use of standard agonist ligands such as morphine, [d-Ala(2)-MePhe(4)-Glyol(5)]enkephalin (DAMGO), U69593, bremazocine, [d-Pen(2)d-Pen(5)]enkephalin (DPDPE), and deltorphin-II as tools for investigating the three major types of opioid receptors, MOP (μ), KOP (κ), and DOP (δ), that mediate antinociception. The functional selectivity of these ligands has been based on the assumption that opioid receptors exist as homomers. As numerous studies in cultured cells have suggested that opioid receptors can associate both as homomers and heteromers, we have investigated the selectivity of these standard ligands using intracellular calcium release and [(35)S]GTPγS assays in HEK-293 cells that contain singly and coexpressed opioid receptors. The present study reveals that morphine and DAMGO, traditionally classified as μ selective agonists, selectively activate μ-δ heteromeric opioid receptors with greater efficacy than homomeric opioid receptors. Moreover, standard ligands that have been widely employed as κ- and δ-selective agonists display little or no differences in the activation of homomeric and heteromeric opioid receptors. The far-reaching implications of these results are discussed.
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Affiliation(s)
| | | | - Philip S. Portoghese
- Department of Pharmacology
- Department of Neuroscience, School of Medicine
- Department of Medicinal Chemistry, College of Pharmacy
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